MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Annals of Biomedical Engineering' source. Sun, 21 Mar 2010 17:31:36 +0100 http://www.medworm.com/index.php?rid=3386352&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20300846%26dopt%3DAbstract This study demonstrates a new concept of bottom up material synthesis by the control of a biological assembly process. PMID: 20300846 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3386352 Fri, 19 Mar 2010 00:00:00 +0100 3386352 http://www.medworm.com/index.php?rid=3386351&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20300847%26dopt%3DAbstract In this study, we use the concept of flow reduction to characterize the stent efficiency. Also, we use the lattice Boltzmann method (LBM) of a non-Newtonian blood flow. To resolve the characteristics of a highly complex flow, we use an extrapolation method for the wall and stent boundary. To ease the code development and facilitate the incorporation of new physics, a scientific programming strategy based on object-oriented concepts is developed. Reduced velocity, smaller average vorticity magnitude, smaller average shear rate, and increased viscosity are observed when the proposed stent shapes and porosities are used. The rectangular stent is observed to be optimal and to decrease the magnitude of the velocity by 89.25% in the 2D model and 53.92% in the 3D model in the aneurysm sac. Our re... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3386351 Fri, 19 Mar 2010 00:00:00 +0100 3386351 http://www.medworm.com/index.php?rid=3386350&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20300848%26dopt%3DAbstract Authors: Huang X, Zauscher S, Klitzman B, Truskey GA, Reichert WM, Kenan DJ, Grinstaff MW Resorbable scaffolds such as polyglycolic acid (PGA) are employed in a number of clinical and tissue engineering applications owing to their desirable property of allowing remodeling to form native tissue over time. However, native PGA does not promote endothelial cell adhesion. Here we describe a novel treatment with hetero-bifunctional peptide linkers, termed "interfacial biomaterials" (IFBMs), which are used to alter the surface of PGA to provide appropriate biological cues. IFBMs couple an affinity peptide for the material with a biologically active peptide that promotes desired cellular responses. One such PGA affinity peptide was coupled to the integrin binding domain, Arg-Gly-Asp (RGD), to ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3386350 Fri, 19 Mar 2010 00:00:00 +0100 3386350 http://www.medworm.com/index.php?rid=3386349&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20300849%26dopt%3DAbstract The objective of this study was to assess the feasibility to induce colonic contractions using a commercially available battery-operated stimulator (maximum pulse width of 1 ms and maximum amplitude of 10 V). Three pairs of pacing electrodes were inserted into the cecal seromuscular layer of anesthetized pigs. During a first set of in vivo experiments conducted on six animals, a pacing protocol leading to cecum contractions was determined: stimulation bursts with 1 ms pulse width, 10 V amplitude (7-15 mA), 120 Hz frequency, and 30-s burst duration, repeated every 2-5 min. In a second testing phase, an evaluation of the pacing protocol was performed in four animals (120 stimulation bursts in total). By using the battery-operated stimulator, contractions of the cecum and movement of contents... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3386349 Fri, 19 Mar 2010 00:00:00 +0100 3386349 http://www.medworm.com/index.php?rid=3386348&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20300850%26dopt%3DAbstract Authors: Chen D, Chittajallu DR, Passalis G, Kakadiaris IA Quantitative analysis of breast morphometry is critical to breast plastic surgery. Recently, three-dimensional (3D) photography has emerged as a strong new alternative for breast morphometry analysis in comparison to other existing techniques. 3D photography enables the capture of the entire breast surface topology virtually in a single snapshot and without any direct contact with the patient, thus causing minimal discomfort. In this paper, we present a set of computational tools for the quantitative analysis of two key morphological properties of the breast that are of interest to breast plastic surgery based on 3D scans, namely breast shape and volume. The breast shape is modeled using a compact geometric model capable of cap... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3386348 Fri, 19 Mar 2010 00:00:00 +0100 3386348 http://www.medworm.com/index.php?rid=3386347&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20300851%26dopt%3DAbstract Authors: Buibas M, Yu D, Nizar K, Silva GA An optical flow gradient algorithm was applied to spontaneously forming networks of neurons and glia in culture imaged by fluorescence optical microscopy in order to map functional calcium signaling with single pixel resolution. Optical flow estimates the direction and speed of motion of objects in an image between subsequent frames in a recorded digital sequence of images (i.e., a movie). Computed vector field outputs by the algorithm were able to track the spatiotemporal dynamics of calcium signaling patterns. We begin by briefly reviewing the mathematics of the optical flow algorithm, and then describe how to solve for the displacement vectors and how to measure their reliability. We then compare computed flow vectors with manually estimate... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3386347 Fri, 19 Mar 2010 00:00:00 +0100 3386347 http://www.medworm.com/index.php?rid=3382435&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20238165%26dopt%3DAbstract Authors: Heidenreich EA, Ferrero JM, Doblaré M, Rodríguez JF Many problems in Biology and Engineering are governed by anisotropic reaction-diffusion equations with a very rapidly varying reaction term. This usually implies the use of very fine meshes and small time steps in order to accurately capture the propagating wave while avoiding the appearance of spurious oscillations in the wave front. This work develops a family of macro finite elements amenable for solving anisotropic reaction-diffusion equations with stiff reactive terms. The developed elements are incorporated on a semi-implicit algorithm based on operator splitting that includes adaptive time stepping for handling the stiff reactive term. A linear system is solved on each time step to update the transmembrane po... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3382435 Thu, 18 Mar 2010 00:00:00 +0100 3382435 http://www.medworm.com/index.php?rid=3382434&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20238166%26dopt%3DAbstract Authors: Tang T, Oh S, Sadleir RJ We compared two 16-electrode electrical impedance tomography (EIT) current patterns on their ability to reconstruct and quantify small amounts of bleeding inside a neonatal human head using both simulated and phantom data. The current patterns used were an adjacent injection RING pattern (with electrodes located equidistantly on the equator of a sphere) and an EEG current pattern based on the 10-20 EEG electrode layout. Structures mimicking electrically important structures in the infant skull were included in a spherical numerical forward model and their effects on reconstructions were determined. The EEG pattern was found to be a better topology to localize and quantify anomalies within lateral ventricular regions. The RING electrode pattern could no... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3382434 Thu, 18 Mar 2010 00:00:00 +0100 3382434 http://www.medworm.com/index.php?rid=3374556&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20232148%26dopt%3DAbstract Authors: Pérez MA, Palacios J Damage accumulation in the cement mantle and debonding of the bone-cement interface are basic events that contribute to the long-term failure of cemented hip reconstructions. In this work, a numerical study with these two process coupled is presented. Previously uniform bone-cement interface mechanical properties were only considered. In this work, a new approach assuming nonuniform and random bone-cement interface mechanical properties was applied to investigate its effect on cement degradation. This methodology was also applied to simulate and compare the degradation process of the cement and bone-cement interface in three different concepts of design: Exeter, Charnley, and ABG II stems. Nonuniform and random mechanical properties of the bone-cement... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3374556 Tue, 16 Mar 2010 00:00:00 +0100 3374556 http://www.medworm.com/index.php?rid=3374555&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20232149%26dopt%3DAbstract Authors: Ye-Lin Y, Garcia-Casado J, Prats-Boluda G, Martinez-de-Juan JL Surface electroenterogram (EEnG) recording is a novel technique for monitoring intestinal motility non-invasively. However, surface EEnG recordings are contaminated by cardiac activity, the respiratory artefact, movement artefacts and other types of interference. The goal of this work is to remove electrocardiogram (ECG) interference and movement artefacts from surface EEnG by means of a combined method of empirical mode decomposition and independent component analysis. For this purpose, 11 recording sessions were conducted on animal models. In order to quantify the effectiveness of the proposed method, several parameters were calculated from each session: signal-to-ECG interference ratio (S/I), energy over 2 Hz (E... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3374555 Tue, 16 Mar 2010 00:00:00 +0100 3374555 http://www.medworm.com/index.php?rid=3374554&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20232150%26dopt%3DAbstract This study established an objective 3D imaging and analysis method for tendon microstructure, which characterizes directionality and anisotropy of the tendon microstructure and quantitative measures of damage that will advance investigations of the microstructural basis of degradation that precedes overuse injuries. PMID: 20232150 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3374554 Tue, 16 Mar 2010 00:00:00 +0100 3374554 http://www.medworm.com/index.php?rid=3374553&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20232151%26dopt%3DAbstract Authors: Leach JR, Rayz VL, Soares B, Wintermark M, Mofrad MR, Saloner D Atherosclerosis at the carotid bifurcation is a major risk factor for stroke. As mechanical forces may impact lesion stability, finite element studies have been conducted on models of diseased vessels to elucidate the effects of lesion characteristics on the stresses within plaque materials. It is hoped that patient-specific biomechanical analyses may serve clinically to assess the rupture potential for any particular lesion, allowing better stratification of patients into the most appropriate treatments. Due to a sparsity of in vivo plaque rupture data, the relationship between various mechanical descriptors such as stresses or strains and rupture vulnerability is incompletely known, and the patient-specific util... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3374553 Tue, 16 Mar 2010 00:00:00 +0100 3374553 http://www.medworm.com/index.php?rid=3374552&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20232152%26dopt%3DAbstract Authors: Loerakker S, Stekelenburg A, Strijkers GJ, Rijpkema JJ, Baaijens FP, Bader DL, Nicolay K, Oomens CW Mechanical loading of soft tissues covering bony prominences can cause skeletal muscle damage, ultimately resulting in a severe pressure ulcer termed deep tissue injury. Recently, by means of an experimental-numerical approach, it was shown that local tissue deformations cause tissue damage once a deformation threshold is exceeded. In the present study, the effects of load exposure time and intermittent load relief on the development of deformation-induced muscle damage were investigated. The data showed that a 2 h loading period caused more damage than 10 min loading. Intermittent load reliefs of 2 min during a 2 h loading period had minimal effect on the evolution of skeletal ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3374552 Tue, 16 Mar 2010 00:00:00 +0100 3374552 http://www.medworm.com/index.php?rid=3374551&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20232153%26dopt%3DAbstract Authors: Shi Y, Lawford PV, Hose DR There is significant interest in the development and application of variable speed impeller-pump type ventricular assist devices designed to generate pulsatile blood flow. However, no study has so far been carried out to investigate the systemic cardiovascular response to various aspects of pump motion. In this article, a numerical model is constructed for the simulation of the cardiovascular response in the heart failure condition under representative cases of pulsatile impeller pump support. The native cardiovascular model is based on a previously validated model, and the impeller pump is modeled by directly fitting the pressure-flow curves that describe the pump characteristics. The model developed is applied to study circulatory dynamics under di... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3374551 Tue, 16 Mar 2010 00:00:00 +0100 3374551 http://www.medworm.com/index.php?rid=3362840&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20225124%26dopt%3DAbstract Authors: Pierce DM, Trobin W, Raya JG, Trattnig S, Bischof H, Glaser C, Holzapfel GA Accurate techniques for simulating the deformation of soft biological tissues are an increasingly valuable tool in many areas of biomechanical analysis and medical image computing. To model the complex morphology and response of articular cartilage, a hyperviscoelastic (dispersed) fiber-reinforced constitutive model is employed to complete two specimen-specific finite element (FE) simulations of an indentation experiment, with and without considering fiber dispersion. Ultra-high field Diffusion Tensor Magnetic Resonance Imaging (17.6 T DT-MRI) is performed on a specimen of human articular cartilage before and after indentation to approximately 20% compression. Based on this DT-MRI data, we detail a nov... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3362840 Fri, 12 Mar 2010 00:00:00 +0100 3362840 http://www.medworm.com/index.php?rid=3362839&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20225125%26dopt%3DAbstract Authors: Rubin JB, Paltiel AD, Saltzman WM With the founding of the National Institute of Biomedical Imaging and Bioengineering (NIBIB) in 1999, the National Institutes of Health (NIH) made explicit its dedication to expanding research in biomedical engineering. Ten years later, we sought to examine how closely federal funding for biomedical engineering aligns with U.S. health priorities. Using a publicly accessible database of research projects funded by the NIH in 2008, we identified 641 grants focused on biomedical engineering, 48% of which targeted specific diseases. Overall, we found that these disease-specific NIH-funded biomedical engineering research projects align with national health priorities, as quantified by three commonly utilized measures of disease burden: cause of dea... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3362839 Fri, 12 Mar 2010 00:00:00 +0100 3362839 http://www.medworm.com/index.php?rid=3362841&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20221900%26dopt%3DAbstract Authors: Yu F, Li R, Parks E, Takabe W, Hsiai TK Zebrafish is an emerging model system for cardiac conduction and regeneration. Zebrafish heart regenerates after 20% ventricular resection within 60 days. Whether cardiac conduction phenotype correlated with cardiomyocyte regeneration remained undefined. Longitudinal monitoring of the adult zebrafish heart (n = 12) was performed in terms of atrial contraction (PR intervals), ventricular depolarization (QRS complex) and repolarization (heart rated corrected QTc interval). Baseline electrocardiogram (ECG) signals were recorded one day prior to resection and twice per week over 59 days. Immunostaining for gap junctions with anti-Connexin-43 antibody was compared between the sham (n = 5) and ventricular resection at 60 days post-resection (d... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3362841 Thu, 11 Mar 2010 00:00:00 +0100 3362841 http://www.medworm.com/index.php?rid=3362842&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20221805%26dopt%3DAbstract Authors: Dubey DK, Tomar V Biological materials have evolved over millions of years and are often found as complex composites with superior properties compared to their relatively weak original constituents. Hard biomaterials such as nacre, bone, and dentin have intrigued researchers for decades for their high stiffness and toughness, multifunctionality, and self-healing capabilities. Challenges lie in identifying nature's mechanisms behind imparting such properties and her pathways in fabricating these composites. The route frequently acquired by nature is embedding submicron- or nano-sized mineral particles in protein matrix in a well-organized hierarchical arrangement. The key here is the formation of large amount of precisely and carefully designed organic-inorganic interfaces and ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3362842 Wed, 10 Mar 2010 00:00:00 +0100 3362842 http://www.medworm.com/index.php?rid=3355120&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20217478%26dopt%3DAbstract We present experimental findings regarding variability and stability of the electrical impedance properties of medical grade stainless steel needle electrodes in vitro. Monopolar impedance spectra (1 Hz to 1 MHz) were measured and scanning electron microscope images were obtained for five needle types with active electrode area from 0.28 to 0.7 mm(2). A saline tank (0.9% NaCl) was used as tissue model. Measurements were done before and after electrolytic treatment with anodic and cathodic DC currents of 1 muA. With active electrode areas below 1 mm(2), high influence from electrode polarization impedance (EPI) was expected at low frequencies (LF). For higher frequencies (HF) the EPI decreases and the impedance of the surrounding tissue is more pronounced. The hypothesis tested was that the... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3355120 Tue, 09 Mar 2010 00:00:00 +0100 3355120 http://www.medworm.com/index.php?rid=3355119&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20217479%26dopt%3DAbstract This article presents an EMG-to-moment optimization model suitable for clinical studies to estimate the contribution of agonist and antagonist muscle groups to the net ankle joint moment during dynamic and isometric tasks. The proposed EMG-to-moment model took into account realistic muscle properties such as the electromechanical delay, and a force-length-velocity relationship with subject-specific muscle anthropometric data. Subjects performed isometric ankle plantar-flexion (fixed-end contraction) and dynamic tasks (heel-raise) in two positions, seated and upright. Two models were compared: the proposed EMG-to-moment model calibrated on eight dynamic and isometric tasks (Model 8-tasks) and on two dynamic tasks (Model 2-tasks), and a published reference model. First, each model was calibr... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3355119 Tue, 09 Mar 2010 00:00:00 +0100 3355119 http://www.medworm.com/index.php?rid=3355118&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20217480%26dopt%3DAbstract This study investigates strain-induced differentiation and proliferation of MSCs, and investigates the cellular mechanisms of mechanotransduction. MSCs were seeded onto a collagen-coated silicone substrate and exposed to cyclic tensile mechanical strain of 2.5% at 0.17 Hz for 1-14 days. To examine mechanotransduction, cells were strained in the presence of the stretch-activated cation channel (SACC) blocker, gadolinium chloride (GdCl(3)); the extracellular regulated kinase (ERK) inhibitor, U0126; the p38 inhibitor, SB203580; and the phosphatidylinosito1 3-kinase (PI3-kinase) inhibitor, LY294002. Following exposure to strain, the osteogenic markers Cbfalpha1, collagen type I, osteocalcin, and BMP2 were temporally expressed. Exposure to strain in the presence of GdCl(3) (10 muM) reduced the ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3355118 Tue, 09 Mar 2010 00:00:00 +0100 3355118 http://www.medworm.com/index.php?rid=3355123&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20213211%26dopt%3DAbstract Authors: Cho YK, Shin H, Lee SK, Kim T Microfabrication technologies have a high potential for novel approaches to access living cells at a cellular or even at a molecular level. In the course of reviewing and discussing the current application of microinterface systems including nanointerfaces to stimulate and analyze cellular responses with subcellular resolution, this article focuses on interfaces based on microfluidics, nanoparticles, and scanning electrochemical microscopy (SECM). Micro/nanointerface systems provide a novel, attractive means for cell study because they are capable of regulating and monitoring cellular signals simultaneously and repeatedly, leading us to an enhanced understanding and interpretation of cellular responses. Therefore, it is hoped that the integrated m... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3355123 Sat, 06 Mar 2010 00:00:00 +0100 3355123 http://www.medworm.com/index.php?rid=3355122&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20213212%26dopt%3DAbstract This study formulates governing equations for active transport across semi-permeable membranes within the framework of the theory of mixtures. In mixture theory, which models the interactions of any number of fluid and solid constituents, a supply term appears in the conservation of linear momentum to describe momentum exchanges among the constituents. In past applications, this momentum supply was used to model frictional interactions only, thereby describing passive transport processes. In this study, it is shown that active transport processes, which impart momentum to solutes or solvent, may also be incorporated in this term. By projecting the equation of conservation of linear momentum along the normal to the membrane, a jump condition is formulated for the mechano-electrochemical pot... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3355122 Sat, 06 Mar 2010 00:00:00 +0100 3355122 http://www.medworm.com/index.php?rid=3355121&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20213213%26dopt%3DAbstract Authors: Xiong FL, Goetz WA, Chong CK, Chua YL, Pfeifer S, Wintermantel E, Yeo JH Recent developments in aortic valve replacement include the truly stentless pericardial bioprostheses with single point attached commissures (SPAC) implantation technique. The leaflet geometry available for the SPAC valves can either be a simple tubular or a complex three-dimensional structure molded using specially designed molds. Our main objective was to compare these two leaflet designs, the tubular vs. the molded, by dynamic finite element simulation. Time-varying physiological pressure loadings over a full cardiac cycle were simulated using ABAQUS. Dynamic leaflet behavior, leaflet coaptation parameters, and stress distribution were compared. The maximum effective valve orifice area during systole i... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3355121 Sat, 06 Mar 2010 00:00:00 +0100 3355121 http://www.medworm.com/index.php?rid=3340196&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20204699%26dopt%3DAbstract In conclusion, LIUS may potentially prove very effective clinically for preventing osteoporotic bone fractures. PMID: 20204699 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3340196 Fri, 05 Mar 2010 00:00:00 +0100 3340196 http://www.medworm.com/index.php?rid=3340195&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20204700%26dopt%3DAbstract Authors: Museyko O, Eisa F, Hess A, Schett G, Kalender WA, Engelke K Registration of bone structures is a common problem in medical research as well as in clinical applications. Intrasubject rigid 3D monomodality registration of segmented bone structures of CT images and multimodality registration of muMR and segmented muCT bone images were performed with the multiresolution intensity-based technique implemented in ITK. The registration results for binary volumes of interest (VOI) masks and for segmented gray value VOIs were compared. To determine the registration quality, in the monomodality case the sum of squared difference, the sum of absolute differences, and the normalized symmetric difference of binary masks and in the multimodality case Mattes mutual information were applied. T... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3340195 Fri, 05 Mar 2010 00:00:00 +0100 3340195 http://www.medworm.com/index.php?rid=3340194&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20204701%26dopt%3DAbstract The objective of this work was development of an easy to handle real-time pulse reactor for evaluation of biological and tissue engineered heart valves under different pressures and long-term conditions. The pulse reactor was made of medical grade materials for placement in a 37 degrees C incubator. Heart valves were mounted in a housing disc moving horizontally in culture medium within a cylindrical culture reservoir. The microprocessor-controlled system was driven by pressure resulting in a cardiac-like cycle enabling competent opening and closing of the leaflets with adjustable pulse rates and pressures between 0.25 to 2 Hz and up to 180/80 mmHg, respectively. A custom-made imaging system with an integrated high-speed camera and image processing software allow calculation of effective o... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3340194 Fri, 05 Mar 2010 00:00:00 +0100 3340194 http://www.medworm.com/index.php?rid=3331075&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20198510%26dopt%3DAbstract Authors: Baxter FR, Bowen CR, Turner IG, Dent AC Electrical potentials in mechanically loaded bone have been implicated as signals in the bone remodeling cycle. Recently, interest has grown in exploiting this phenomenon to develop electrically active ceramics for implantation in hard tissue which may induce improved biological responses. Both polarized hydroxyapatite (HA), whose surface charge is not dependent on loading, and piezoelectric ceramics, which produce electrical potentials under stress, have been studied in order to determine the possible benefits of using electrically active bioceramics as implant materials. The polarization of HA has a positive influence on interfacial responses to the ceramic. In vivo studies of polarized HA have shown polarized samples to induce improve... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3331075 Wed, 03 Mar 2010 00:00:00 +0100 3331075 http://www.medworm.com/index.php?rid=3331081&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20195758%26dopt%3DAbstract In this study, computational fluid dynamics (CFD) was used to estimate the performance of first stage HLHS surgery, the Norwood operation. An image data transfer system was developed to convert clinical images into three-dimensional geometry. To confirm software applicability, a validation process was carried out to eliminate any influence of numerical procedures. The velocities derived from echocardiography measurements were used as boundary conditions, and pressure waves measured by a cardiac catheter simultaneous with an electrocardiogram (ECG) were employed to validate the results of CFD simulation. Calculated results were congruent with the in vivo measurement results. The blood flow circulations were successfully simulated and the distribution of blood flow in each vessel was estimat... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3331081 Tue, 02 Mar 2010 00:00:00 +0100 3331081 http://www.medworm.com/index.php?rid=3331080&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20195759%26dopt%3DAbstract Authors: PMID: 20195759 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3331080 Tue, 02 Mar 2010 00:00:00 +0100 3331080 http://www.medworm.com/index.php?rid=3331077&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20195762%26dopt%3DAbstract We describe a novel stretch device optimized for high-resolution live-cell imaging. The unit assembles onto standard inverted microscopes and applies constant magnitude or cyclic stretch at physiological magnitudes to cultured cells on elastic membranes. Interchangeable modular indenters enable delivery of equibiaxial and uniaxial stretch profiles. Strain analysis performed by tracking fluorescent microspheres adhered onto the substrate demonstrated reproducible application of stretch profiles. In endothelial cells transiently expressing enhanced green fluorescent protein (EGFP)-vimentin and paxillin-DsRed2 and subjected to constant magnitude equibiaxial stretch, the two-dimensional strain tensor demonstrated efficient transmission through the extracellular matrix and focal adhesions. Decr... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3331077 Tue, 02 Mar 2010 00:00:00 +0100 3331077 http://www.medworm.com/index.php?rid=3331076&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20195763%26dopt%3DAbstract The objective of this study was to determine the viscoelastic properties present within the intermediate zone of the porcine temporomandibular joint (TMJ) disc using nanoindentation. A 50-mum conospherical indenter tip using a displacement-controlled ramp function with a 600 nm/s loading and unloading rate, a 3000-nm peak displacement with a holding period of 30 s was used to indent the samples. Experimental load-relaxation tests were performed on the TMJ disc to determine the response in three different directions; the mediolateral, anteroposterior, and articular surface directions. The experimental data were analyzed using a generalized Maxwell model to obtain values for short- and long-time relaxation modulus and of material time constants. The short time relaxation modulus E ( I ) valu... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3331076 Tue, 02 Mar 2010 00:00:00 +0100 3331076 http://www.medworm.com/index.php?rid=3331079&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20195760%26dopt%3DAbstract In this study, we implement the effects of MMP-mediated proteolysis in a force-based computational model of 3D migration, testing two matrix ligand-MMP relationships that have been observed experimentally: linear and log-linear. The model for both scenarios predicts maximal motility at intermediate matrix ligand and MMP levels, with the linear case providing more physiologically compelling results. Recent experimental results suggesting MMP influence on integrin expression are also integrated into the model. While the biphasic behavior is retained, with MMP-integrin feedback peak cell speed is observed in a low ligand, high MMP regime instead of at intermediate ligand and MMP levels for both ligand-MMP relationships. The simulation provides insight into the expanding role of cell-matrix in... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3331079 Sat, 27 Feb 2010 00:00:00 +0100 3331079 http://www.medworm.com/index.php?rid=3331078&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20195761%26dopt%3DAbstract Authors: Spencer P, Ye Q, Park J, Topp EM, Misra A, Marangos O, Wang Y, Bohaty BS, Singh V, Sene F, Eslick J, Camarda K, Katz JL Results from clinical studies suggest that more than half of the 166 million dental restorations that were placed in the United States in 2005 were replacements for failed restorations. This emphasis on replacement therapy is expected to grow as dentists use composite as opposed to dental amalgam to restore moderate to large posterior lesions. Composite restorations have higher failure rates, more recurrent caries, and increased frequency of replacement as compared to amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and premature failu... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3331078 Sat, 27 Feb 2010 00:00:00 +0100 3331078 http://www.medworm.com/index.php?rid=3303352&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20177779%26dopt%3DAbstract In conclusion, the proposed method can improve the degree of automation of model-based hip replacement surgical systems. PMID: 20177779 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3303352 Tue, 23 Feb 2010 00:00:00 +0100 3303352 http://www.medworm.com/index.php?rid=3303351&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20177780%26dopt%3DAbstract This study presents a new steady-state visual evoked potential (SSVEP)-based brain computer interface (BCI). SSVEPs, induced by phase-tagged flashes in eight light emitting diodes (LEDs), were used to control four cursor movements (up, right, down, and left) and four button functions (on, off, right-, and left-clicks) on a screen menu. EEG signals were measured by one EEG electrode placed at Oz position, referring to the international EEG 10-20 system. Since SSVEPs are time-locked and phase-locked to the onsets of SSVEP flashes, EEG signals were bandpass-filtered and segmented into epochs, and then averaged across a number of epochs to sharpen the recorded SSVEPs. Phase lags between the measured SSVEPs and a reference SSVEP were measured, and targets were recognized based on these phase la... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3303351 Tue, 23 Feb 2010 00:00:00 +0100 3303351 http://www.medworm.com/index.php?rid=3303350&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20177781%26dopt%3DAbstract The objective of this work was to assess the effect of 10% (w/v) polyvinylpyrrolidone (PVP) on the pattern of intracellular ice formation (IIF) in human adipose tissue derived adult stem cells (ASCs) in the absence of serum and other cryoprotective agents (CPAs). The freezing experiments were carried out using a fluorescence microscope equipped with a Linkam cooling stage using two cooling protocols. Both the cooling protocols had a common cooling ramp: cells were cooled from 20 degrees C to -8 degrees C at 20 degrees C/min and then further cooled to -13 degrees C at 1 degrees C/min. At this point we employed either cooling protocol 1: the cells were cooled from -13 degrees C to -40 degrees C at a pre-determined cooling rate of 1, 5, 10, 20, or 40 degrees C/min and then thawed back to 20 d... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3303350 Tue, 23 Feb 2010 00:00:00 +0100 3303350 http://www.medworm.com/index.php?rid=3303349&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20177782%26dopt%3DAbstract This study takes five different coronary stent designs, used in clinical practice, and explores the hemodynamic differences arising due to the difference in their design. Of particular interest is the design of the segments (connectors) that connect two struts. Pulsatile blood flow analysis is performed for each stent, using 3-D computational fluid dynamics (CFD), and various flow features viz. recirculation zones, velocity profiles, wall shear stress (WSS) patterns, and oscillatory shear indices are extracted for comparison. Vessel wall regions with abnormal flow features, particularly low, reverse, and oscillating WSS, are usually more susceptible to restenosis. Unlike previous studies, which have tried to study the effect of design parameters such as strut thickness and strut spacing on... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3303349 Tue, 23 Feb 2010 00:00:00 +0100 3303349 http://www.medworm.com/index.php?rid=3303348&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20177783%26dopt%3DAbstract This study uses poroviscoelasticity (PVE) theory to simulate liver biomechanical response in unconfined compression stress relaxation experiments, for variable ramp strain rates ranging from 0.001 to 0.1 s(-1). Specimens included 17 ex vivo porcine liver samples tested in a humidified temperature-controlled chamber. Liver response was modeled using ABAQUS, and best-fit parameters were determined using non-linear least-squares algorithms. The PVE model was able to capture the behavior of porcine liver in unconfined compression, with regression analyses for the ramp phase demonstrating high correlation between model and experiment (R (2) > 0.993, slope > 0.833, p < 0.05). The advantage of PVE modeling over traditional viscoelastic modeling is the ability to examine interstitial flui... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3303348 Tue, 23 Feb 2010 00:00:00 +0100 3303348 http://www.medworm.com/index.php?rid=3286153&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162353%26dopt%3DAbstract We present a practical and systematic method to reconstruct accurate physical models of the guinea pig ear (n = 1). The method uses a semi-automatic technique to create three-dimensional (3-D) models of the guinea pig cochlea by registration of micro-computed tomography (CT) and histological images. An iterative closest point algorithm was employed to minimize the sum of square errors with respect to the closest histological model and corresponding micro-CT model. This allowed creation of an accurate geometric ear model including external ear canal, tympanic membrane, middle ear cavity, auditory ossicles, and the cochlea. The characteristic cross-sectional areas of scala tympani, scala vestibuli, and scala media were measured. The length, thickness, and apex width of the guinea pig's basil... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286153 Wed, 17 Feb 2010 00:00:00 +0100 3286153 http://www.medworm.com/index.php?rid=3286152&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162354%26dopt%3DAbstract Authors: Vanderpool RR, Naeije R, Chesler NC Hypoxic pulmonary hypertension is a disease of the lung vasculature that is usually quantified by pulmonary vascular resistance (PVR). However, a more complete description of lung vascular function and right ventricular afterload is provided by pulmonary vascular impedance (PVZ) from spectral analysis of pulsatile pressure-flow relationships. We studied pulsatile pressure-flow relationships in isolated, perfused lungs of mice in normoxia, after induction of hypoxic pulmonary hypertension by 10 days of hypoxic exposure, and after the administration of the vasoactive agents sodium nitroprusside and serotonin in order to gain insight into the effects of disease and vasoactive agents on afterload. Chronic hypoxia exposure increased 0 Hz impedanc... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286152 Wed, 17 Feb 2010 00:00:00 +0100 3286152 http://www.medworm.com/index.php?rid=3286147&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162355%26dopt%3DAbstract This study also investigated the EC response to a nicotine chemical stimulus combined with a suspected athero-prone physiological mechanical stimulus. A bioreactor was designed to apply a range of combinations of physiological WSS and THS waveforms. The bioreactor was calibrated and validated using computational fluid dynamics and video extensometry techniques. The bioreactor was used to investigated the biochemical response exhibited by human umbilical vein endothelial cells (HUVECs) exposed to physiological athero-protective (first bioreactor test case, pulsatile WSS combined with pulsatile THS) and athero-prone (second bioreactor test case, oscillating WSS combined with pulsatile THS) mechanical environments. The final testing environment (third bioreactor test case) combined a nicotine... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286147 Wed, 17 Feb 2010 00:00:00 +0100 3286147 http://www.medworm.com/index.php?rid=3286138&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162356%26dopt%3DAbstract Authors: Chesler NC, Barabino G, Bhatia SN, Richards-Kortum R While the percentage of women in biomedical engineering is higher than in many other technical fields, it is far from being in proportion to the US population. The decrease in the proportion of women and underrepresented minorities in biomedical engineering from the bachelors to the masters to the doctoral levels is evidence of a still leaky pipeline in our discipline. In addition, the percentage of women faculty members at the assistant, associate and full professor levels remain disappointingly low even after years of improved recruitment of women into biomedical engineering at the undergraduate level. Worse, the percentage of women graduating with undergraduate degrees in biomedical engineering has been decreasing nationw... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286138 Wed, 17 Feb 2010 00:00:00 +0100 3286138 http://www.medworm.com/index.php?rid=3286137&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162357%26dopt%3DAbstract Authors: Xia G, Tawhai MH, Hoffman EA, Lin CL The airflow characteristics in a computed tomography (CT) based human airway bifurcation model with rigid and compliant walls are investigated numerically. An in-house three-dimensional (3D) fluid-structure interaction (FSI) method is applied to simulate the flow at different Reynolds numbers and airway wall stiffness. As the Reynolds number increases, the airway wall deformation increases and the secondary flow becomes more prominent. It is found that the peak wall shear stress on the rigid airway wall can be five times stronger than that on the compliant airway wall. When adding tethering forces to the model, we find that these forces, which produce larger airway deformation than without tethering, lead to more skewed velocity profiles in... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286137 Wed, 17 Feb 2010 00:00:00 +0100 3286137 http://www.medworm.com/index.php?rid=3286136&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162358%26dopt%3DAbstract Authors: Basciano CA, Kleinstreuer C, Kennedy AS, Dezarn WA, Childress E Combating liver tumors via yttrium-90 ((90)Y) radioembolization is a viable treatment option of nonresectable liver tumors. Employing clinical (90)Y microparticles (i.e., SIR-Spheres((R)) and TheraSpheres((R))) in a computational model of a representative hepatic artery system, laminar transient 3D particle-hemodynamics were simulated. Specifically, optimal particle release positions in the right hepatic (parent) artery as well as the best temporal release window were determined for the microspheres to exit specific outlet daughter vessels, potentially connected to liver tumors. The results illustrate the influence of a curved geometry on the velocity field and the particle trajectory dependence on the spatial and... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286136 Wed, 17 Feb 2010 00:00:00 +0100 3286136 http://www.medworm.com/index.php?rid=3286135&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162359%26dopt%3DAbstract Authors: Desai M, Eaton-Evans J, Hillery C, Bakhshi R, You Z, Lu J, Hamilton G, Seifalian AM Endovascular aneurysm repair (EVAR) has quickly gained popularity for infrarenal abdominal aortic aneurysm repair during the last two decades. The improvement of available EVAR devices is critical for the advancement of patient care in vascular surgery. Problems are still associated with the grafts, many of which can necessitate the conversion of the patient to open repair, or even result in rupture of the aneurysm. This review attempts to address these problems, by highlighting why they occur and what the failings of the currently available stent grafts are, respectively. In addition, the review gives critical appraisal as to the novel methods required for dealing with these problems and ident... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286135 Wed, 17 Feb 2010 00:00:00 +0100 3286135 http://www.medworm.com/index.php?rid=3286134&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162360%26dopt%3DAbstract Authors: van der Krogt MM, Bregman DJ, Wisse M, Doorenbosch CA, Harlaar J, Collins SH Children with cerebral palsy frequently experience foot dragging and tripping during walking due to a lack of adequate knee flexion in swing (stiff-knee gait). Stiff-knee gait is often accompanied by an overly flexed knee during stance (crouch gait). Studies on stiff-knee gait have mostly focused on excessive knee muscle activity during (pre)swing, but the passive dynamics of the limbs may also have an important effect. To examine the effects of a crouched posture on swing knee flexion, we developed a forward-dynamic model of human walking with a passive swing knee, capable of stable cyclic walking for a range of stance knee crouch angles. As crouch angle during stance was increased, the knee naturall... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286134 Wed, 17 Feb 2010 00:00:00 +0100 3286134 http://www.medworm.com/index.php?rid=3286133&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162361%26dopt%3DAbstract Authors: Dash RK, Bassingthwaighte JB New mathematical model equations for O(2) and CO(2) saturations of hemoglobin ([Formula: see text] and [Formula: see text]) are developed here from the equilibrium binding of O(2) and CO(2) with hemoglobin inside RBCs. They are in the form of an invertible Hill-type equation with the apparent Hill coefficients [Formula: see text] and [Formula: see text] in the expressions for [Formula: see text] and [Formula: see text] dependent on the levels of O(2) and CO(2) partial pressures ([Formula: see text] and [Formula: see text]), pH, 2,3-DPG concentration, and temperature in blood. The invertibility of these new equations allows [Formula: see text] and [Formula: see text] to be computed efficiently from [Formula: see text] and [Formula: see text] and vic... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3286133 Wed, 17 Feb 2010 00:00:00 +0100 3286133 http://www.medworm.com/index.php?rid=3270044&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20148308%26dopt%3DAbstract Authors: Auer M, Stollberger R, Regitnig P, Ebner F, Holzapfel GA Existing atherosclerotic plaque imaging techniques such as intravascular ultrasound, multidetector computed tomography, optical coherence tomography, and high-resolution magnetic resonance imaging (hrMRI) require computerized methods to separate and analyze the plaque morphology. In this work, we perform in vitro balloon angioplasty experiments with 10 human femoral arteries using hrMRI and image processing. The vessel segments contain low-grade to high-grade lesions with very different plaque compositions. The experiments are designed to mimic the in vivo situation. We use a semi-automatic image processing tool to extract the three-dimensional (3D) geometries of the tissue components at four characteristic stages of the... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3270044 Thu, 11 Feb 2010 00:00:00 +0100 3270044 http://www.medworm.com/index.php?rid=3263324&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20143262%26dopt%3DAbstract Authors: Malvè M, Del Palomar AP, López-Villalobos JL, Ginel A, Doblaré M The main physiological function of coughing is to remove from the airways the mucus and foreign particles that enter the lungs with respirable air. However, in patients with endotracheal tubes, further surgery has to be performed to improve cough effectiveness. Thus, it is necessary to analyze how this process is carried out in healthy tracheas to suggest ways to improve its efficacy in operated patients. A finite element model of a human trachea is developed and used to analyze the deformability of the tracheal walls under coughing. The geometry of the trachea is obtained from CT of a 70-year-old male patient. A fluid structure interaction approach is used to analyze the deformation of the wall wh... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263324 Tue, 09 Feb 2010 00:00:00 +0100 3263324 http://www.medworm.com/index.php?rid=3263323&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20143263%26dopt%3DAbstract In this study, we use magnetic resonance imaging and computational fluid dynamics to describe hemodynamics in eight AAAs during rest and exercise using patient-specific geometric models, flow waveforms, and pressures as well as appropriately resolved finite-element meshes. We report mean wall shear stress (MWSS) and oscillatory shear index (OSI) at four aortic locations (supraceliac, infrarenal, mid-aneurysm, and suprabifurcation) and turbulent kinetic energy over the entire computational domain on meshes containing more than an order of magnitude more elements than previously reported results (mean: 9.0-million elements; SD: 2.3 M; range: 5.7-12.0 M). MWSS was lowest in the aneurysm during rest 2.5 dyn/cm(2) (SD: 2.1; range: 0.9-6.5), and MWSS increased and OSI decreased at all four locat... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263323 Tue, 09 Feb 2010 00:00:00 +0100 3263323 http://www.medworm.com/index.php?rid=3263327&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20140518%26dopt%3DAbstract Authors: Lin CW, Yuan F Topical application of drugs for treatment of intraocular diseases is often limited by inadequate transport and induced toxicity in corneal tissues. To improve the drug delivery, a mathematical model was developed to numerically simulate the transport process of ethacrynic acid (ECA), a potential drug for glaucoma treatment, in the anterior segment of a typical human eye. The model considered diffusion of ECA in all tissues and the aqueous humor (AH) as well as convection of ECA in the AH. The simulation results showed that ECA concentration in the eye depended on the rate of AH production, the half-life of ECA in the precorneal tear film, and the transport parameters in the model. In addition, the main pathway for ECA clearance from the eye was the trabecular m... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263327 Sat, 06 Feb 2010 00:00:00 +0100 3263327 http://www.medworm.com/index.php?rid=3263326&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20140519%26dopt%3DAbstract This article is based on a lecture I presented as the recipient of the 2009 Pritzker Distinguished Lecturer Award at the Biomedical Engineering Society annual meeting in October 2009. Here, I review more than thirty years of research from my laboratory, beginning with studies designed to test the theory that cells use tensegrity (tensional integrity) architecture to stabilize their shape and sense mechanical signals, which I believed to be critical for control of cell function and tissue development. Although I was trained as a cell biologist, I found that the tools I had at my disposal were insufficient to experimentally test these theories, and thus I ventured into engineering to find critical solutions. This path has been extremely fruitful as it has led to confirmation of the critical ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263326 Sat, 06 Feb 2010 00:00:00 +0100 3263326 http://www.medworm.com/index.php?rid=3263325&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20140520%26dopt%3DAbstract Authors: Peramo A, Marcelo CL This discussion and review article focuses on the possible use of regenerative techniques applied to the interfaces between skin and medical implants. As is widely known, the area of contact between an implant and the skin-the skin-implant interface-is prone to recurrent and persistent problems originated from the lack of integration between the material of the implant and the skin. Producing a long-term successful biointerface between skin and the implanted device is still an unsolved problem. These complications have prevented the development of advanced prosthetics and the evolution of biointegrated devices with new technologies. While previous techniques addressing these issues have relied mostly on the coating of the implants or the modification of th... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263325 Sat, 06 Feb 2010 00:00:00 +0100 3263325 http://www.medworm.com/index.php?rid=3244975&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20135351%26dopt%3DAbstract Authors: Miri R, Graf IM, Bayarri JV, Dössel O Biventricular pacing (BVP) could be improved by identifying the patient-specific optimal electrode positions. Body surface potential map (BSPM) is a non-invasive technique for obtaining the electrophysiology and pathology of a patient. The study proposes the use of BSPM as input for an automated non-invasive strategy based on a personalized computer model of the heart, to identify the patient pathology and specific optimal treatment with BVP devices. The anatomy of a patient suffering from left bundle branch block and myocardial infarction is extracted from a series of MR data sets. The clinical measurements of BSPM are used to parameterize the computer model of the heart to represent the individual pathology. Cardiac electrophysiolog... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3244975 Fri, 05 Feb 2010 00:00:00 +0100 3244975 http://www.medworm.com/index.php?rid=3244974&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20135352%26dopt%3DAbstract Authors: Ganesan P, He S, Xu H The paper presents an image-based network model of retinal vasculature taking account of the 3D vascular distribution of the retina. Mouse retinas were prepared using flat-mount technique and vascular images were obtained using confocal microscopy. The vascular morphometric information obtained from confocal images was used for the model development. The network model developed directly represents the vascular geometry of all the large vessels of the arteriolar and venular trees and models the capillaries using uniformly distributed meshes. The vasculatures in different layers of the retina, namely the superficial, intermediate, and deep layer, were modeled separately in the network and were linked through connecting vessels. The branching data of the vas... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3244974 Fri, 05 Feb 2010 00:00:00 +0100 3244974 http://www.medworm.com/index.php?rid=3244973&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20135353%26dopt%3DAbstract Authors: Sheriff J, Bluestein D, Girdhar G, Jesty J Individuals with mechanical heart valve implants are plagued by flow-induced thromboembolic complications, which are undoubtedly caused by platelet activation. Flow fields in or around the affected regions involve brief exposure to pathologically high-shear stresses on the order of 100 to 1000 dyne/cm(2). Although high shear is known to activate platelets directly, their subsequent behavior is not known. We hypothesize that the post-high-shear activation behavior of platelets is particularly relevant in understanding the increased thrombotic risk associated with blood-recirculating prosthetic cardiovascular devices. Purified platelets were exposed to brief (5-40 s) periods of high-shear stress, and then exposed to longer periods (15-6... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3244973 Fri, 05 Feb 2010 00:00:00 +0100 3244973 http://www.medworm.com/index.php?rid=3244978&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20131096%26dopt%3DAbstract Authors: Coats BW, Keith Sharp M One proposed method to overcome postflight orthostatic intolerance is for astronauts to undergo inflight centrifugation. Cardiovascular responses were compared between centrifuge and gravitational conditions using a seven-compartment cardiovascular model. Vascular resistance, heart rate, and stroke volume values were adopted from literature, while compartmental volumes and compliances were derived from impedance plethysmography of subjects (n = 8) riding on a centrifuge. Three different models were developed to represent the typical male subject who completed a 10-min postflight stand test ("male finisher"), "non-finishing male" and "female" (all non-finishers). A sensitivity analysis found that both cardiac output and arterial pressure were most sensit... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3244978 Thu, 04 Feb 2010 00:00:00 +0100 3244978 http://www.medworm.com/index.php?rid=3244977&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20131097%26dopt%3DAbstract Authors: Nagaoka M, Jiang HL, Hoshiba T, Akaike T, Cho CS Extracellular matrix (ECM) plays important roles in tissue engineering because cellular growth and differentiation, in the two-dimensional cell culture as well as in the three-dimensional space of the developing organism, require ECM with which the cells can interact. Also, the development of new synthetic ECMs is very important because ECMs facilitate the localization and delivery of cells to the specific sites in the body. Therefore, the development of synthetic ECMs to replace the natural ECMs is increasingly essential and promising in tissue engineering. Recombinant genetic engineering method has enabled the synthesis of protein-based polymers with precisely controlled functionalities for the development of new synthetic ECM... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3244977 Thu, 04 Feb 2010 00:00:00 +0100 3244977 http://www.medworm.com/index.php?rid=3244976&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20131098%26dopt%3DAbstract Authors: Bluestein D, Chandran KB, Manning KB Implantable blood recirculating devices have provided life saving solutions to patients with severe cardiovascular diseases. However, common problems of hemolysis and thromboembolism remain an impediment to these devices. In this article, we present a brief review of the work by several groups in the field that has led to the development of new methodologies that may facilitate achieving the daunting goal of optimizing the thrombogenic performance of blood recirculating devices. The aim is to describe work which pertains to the interaction between flow-induced stresses and the blood constituents, and that supports the hypothesis that thromboembolism in prosthetic blood recirculating devices is initiated and maintained primarily by the non-p... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3244976 Thu, 04 Feb 2010 00:00:00 +0100 3244976 http://www.medworm.com/index.php?rid=3239233&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20127511%26dopt%3DAbstract Authors: Hopenfeld B, Ashikaga H The electrophysiological basis underlying the genesis of the U wave remains uncertain. Previous U wave modeling studies have generally been restricted to 1-D or 2-D geometries, and it is not clear whether the U waves generated by these models would match clinically observed U wave body surface potential distributions (BSPDs). We investigated the role of M cells and transmural dispersion of repolarization (TDR) in a 2-D, fully ionic heart tissue slice model and a realistic 3-D heart/torso model. In the 2-D model, while a U wave was present in the ECG with dynamic gap junction conductivity, the ECG with static gap junctions did not exhibit a U wave. In the 3-D model, TDR was necessary to account for the clinically observed potential minimum in the right s... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3239233 Wed, 03 Feb 2010 00:00:00 +0100 3239233 http://www.medworm.com/index.php?rid=3239232&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20127512%26dopt%3DAbstract Authors: Hawkins WA PMID: 20127512 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3239232 Wed, 03 Feb 2010 00:00:00 +0100 3239232 http://www.medworm.com/index.php?rid=3239234&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20127171%26dopt%3DAbstract In conclusion, our simulations question the working principle of the Arteriograph. Our data indicate that the method picks up wave reflection phenomena confined to the brachial artery, and derived values of PWV rather reflect the stiffness of the brachial arteries. PMID: 20127171 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3239234 Tue, 02 Feb 2010 00:00:00 +0100 3239234 http://www.medworm.com/index.php?rid=3231925&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20119846%26dopt%3DAbstract In this study, we present an empirical mode decomposition-based intrinsic mode analysis, which uses the appearance energy index (AEI) to quantify the property of long-term correlation, and structure index (SI) to characterize the internal modulation of data. This presented algorithm was used to investigate the human heartbeat time series downloaded from PhysioBank. We found the profiles of human heartbeat time series of subjects with congestive heart failure (CHF) or atrial fibrillation (AF) are significantly different from those of healthy subjects in internal modulation as shown by SI. Moreover, AEI is the critical characteristics for verifying subjects with CHF from subjects with AF in a degree of long-term correlation. Both AEI and SI contribute to presenting the characteristic profile... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3231925 Sat, 30 Jan 2010 00:00:00 +0100 3231925 http://www.medworm.com/index.php?rid=3221080&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20108164%26dopt%3DAbstract This study demonstrates that dextran can alter endothelial cell function and therefore, caution is advised and time matched dextran controls are necessary when using dextran for dynamic cell studies. PMID: 20108164 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3221080 Thu, 28 Jan 2010 00:00:00 +0100 3221080 http://www.medworm.com/index.php?rid=3221079&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20108165%26dopt%3DAbstract Authors: Ujihara Y, Nakamura M, Miyazaki H, Wada S We developed a mechano-cell model incorporating a cell membrane, a nuclear envelope, and actin filaments to simulate the mechanical behavior of a cell during tensile tests. The computational model depicts a cell as a combination of various spring elements in the framework of the minimum energy concept. A cell membrane and a nuclear envelope are both modeled as shells of a spring network that express elastic resistance to changes in bending, stretching, and surface area. A bundle of actin filaments is represented by a mechanical spring that generates a force as a function of its extension. The interaction between the nuclear envelope and the cell membrane is expressed by a potential energy function with respect to the distance between t... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3221079 Thu, 28 Jan 2010 00:00:00 +0100 3221079 http://www.medworm.com/index.php?rid=3221082&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20108044%26dopt%3DAbstract Authors: Venkatasubramanian RT, Wolkers WF, Shenoi MM, Barocas VH, Lafontaine D, Soule CL, Iaizzo PA, Bischof JC Applications involving freeze-thaw, such as cryoplasty or cryopreservation can significantly alter artery biomechanics including an increase in physiological elastic modulus. Since artery biomechanics plays a significant role in hemodynamics, it is important to understand the mechanisms underlying these changes to be able to help control the biomechanical outcome post-treatments. Understanding of these mechanisms requires investigation of the freeze-thaw effect on arterial components (collagen, smooth muscle cells or SMCs), as well as the components' contribution to the overall artery biomechanics. To do this, isolated fresh swine arteries were subjected to thermal (freeze-t... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3221082 Wed, 27 Jan 2010 00:00:00 +0100 3221082 http://www.medworm.com/index.php?rid=3221081&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20108045%26dopt%3DAbstract Authors: Einav S, Bluestein D, Gharib MM PMID: 20108045 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3221081 Wed, 27 Jan 2010 00:00:00 +0100 3221081 http://www.medworm.com/index.php?rid=3213234&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20099031%26dopt%3DAbstract Authors: Xie HB, Guo JY, Zheng YP In the present contribution, a complexity measure is proposed to assess surface electromyography (EMG) in the study of muscle fatigue during sustained, isometric muscle contractions. Approximate entropy (ApEn) is believed to provide quantitative information about the complexity of experimental data that is often corrupted with noise, short data length, and in many cases, has inherent dynamics that exhibit both deterministic and stochastic behaviors. We developed an improved ApEn measure, i.e., fuzzy approximate entropy (fApEn), which utilizes the fuzzy membership function to define the vectors' similarity. Tests were conducted on independent, identically distributed (i.i.d.) Gaussian and uniform noises, a chirp signal, MIX processes, Rossler equation, ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3213234 Sat, 23 Jan 2010 00:00:00 +0100 3213234 http://www.medworm.com/index.php?rid=3213233&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20099032%26dopt%3DAbstract Authors: Chien S PMID: 20099032 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3213233 Sat, 23 Jan 2010 00:00:00 +0100 3213233 http://www.medworm.com/index.php?rid=3213232&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20099033%26dopt%3DAbstract Authors: Tanimoto K, Yanagida T, Tanne Y, Kamiya T, Huang YC, Mitsuyoshi T, Tanaka N, Tanaka E, Tanne K Hyaluronan (HA) plays a crucial role in the lubricating and buffering properties of synovial fluid. The purpose of this study was to examine the effects of interleukin (IL)-1beta on HA degradation in cultured synovial membrane cells. The rabbit synovial membrane cell line HIG-82 was cultured with and without IL-1beta. The amounts of HA of varying molecular weights in the medium were analyzed using high-performance liquid chromatography, the mRNA levels of HA synthase (HAS) and hyaluronidase (HYAL) were analyzed by means of real-time PCR, and HYAL activity was analyzed by HA zymography. The amounts of HA with a molecular weight lower than 300 kDa, and between 300 and 1900 kDa, in the ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3213232 Sat, 23 Jan 2010 00:00:00 +0100 3213232 http://www.medworm.com/index.php?rid=3213231&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20099034%26dopt%3DAbstract Authors: Lieber SC, Kruithof BP, Aubry N, Vatner SF, Gaussin V Valvular heart disease is a leading cause of morbidity and mortality in adults but little is known about the underlying etiology. A better understanding of the genetic and hemodynamic mechanisms involved in growth and remodeling of heart valves during physiological and pathological conditions is needed for a better understanding of valvular heart disease. Here, we report the design of a miniature tissue culture system (MTCS) that allows the culture of mitral valves from perinatal to adult mice. The design of the MTCS is novel in that fine positioning and cannulation can be conducted with hearts of different sizes (perinatal to adult). Perfusion of the heart and hence, culture of the mitral valve in its natural position, occ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3213231 Sat, 23 Jan 2010 00:00:00 +0100 3213231 http://www.medworm.com/index.php?rid=3213230&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20099035%26dopt%3DAbstract Authors: Charonko J, Karri S, Schmieg J, Prabhu S, Vlachos P Time resolved particle image velocimetry was used to measure wall shear stress (WSS) and oscillatory shear index (OSI) within a 3.0 mm diameter compliant vessel model implanted with an Abbott Vascular XIENCE V((R)) stent in five configurations: baseline, over-expanded, increased vessel diameter, two overlapped stents, and increased stent length. Flow through unstented vessels was also tested for comparison. Flow conditions featured a realistic coronary pressure-flow offset and reversal at average flow rates corresponding to resting (Re = 160, f = 70 bpm) and exercise conditions (Re = 300, f = 120 bpm). Comparisons revealed that the WSS was similar for all cases behind the first strut and downstream of the device, indicating t... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3213230 Sat, 23 Jan 2010 00:00:00 +0100 3213230 http://www.medworm.com/index.php?rid=3201204&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20094913%26dopt%3DAbstract In conclusion, veins buckle into a tortuous shape at high lumen pressures or reduced axial stretch ratios. Our results are useful in understanding the development of venous tortuosity associated with varicose veins, venous valvular insufficiency, diabetic retinopathy, and vein grafts. PMID: 20094913 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3201204 Fri, 22 Jan 2010 00:00:00 +0100 3201204 http://www.medworm.com/index.php?rid=3201203&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20094914%26dopt%3DAbstract This study shows that such a rotary motion can be totally reversed after the implant of a prosthetic valve. This phenomenon, in agreement with clinical observation, appears mostly imputable to the symmetry of the implant. The reversed rotation increases energy dissipation and modifies the pressure distribution with the potential development of new pathologies. The results provide preliminary, physically based, elements for the improvement of surgical procedures or prosthesis. PMID: 20094914 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3201203 Fri, 22 Jan 2010 00:00:00 +0100 3201203 http://www.medworm.com/index.php?rid=3201202&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20094915%26dopt%3DAbstract This study used a human heart computer model which incorporated anatomical structures such as myofiber orientation and a Purkinje system (PS) to study how pacing affected failing hearts. The PS was modeled as a tree structure that reproduced its retrograde activation feature. In addition to a normal geometry, two cardiomyopathies were modeled: dilatation and hypertrophy. A biventricular pacing protocol was tested in the context of atrio-ventricular block. The contribution of the PS was examined by removing it, as well as by increasing endocardial conductivity. Results showed that retrograde conduction into the PS was a determining factor for achieving intraventricular synchrony. Omission of the PS led to an overestimate of the degree of electrical dyssynchrony while assessing CRT. The acti... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3201202 Fri, 22 Jan 2010 00:00:00 +0100 3201202 http://www.medworm.com/index.php?rid=3201201&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20094916%26dopt%3DAbstract In conclusion, the model is able to reproduce several different pathological conditions characterized by heterogeneity in cerebrovascular hemodynamics and cannot only explain generalized results in terms of physiological mechanisms involved, but also, by individualizing parameters, may represent a valuable tool to help with difficult clinical decisions. PMID: 20094916 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3201201 Fri, 22 Jan 2010 00:00:00 +0100 3201201 http://www.medworm.com/index.php?rid=3195786&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087766%26dopt%3DAbstract Authors: O'Flynn PM, O'Sullivan G, Pandit AS Vessel geometry determines blood flow dynamics and plays a crucial role in the pathogenesis of vascular disease. In vivo assessment of three-dimensional (3D) vessel anatomy is vital to improve the realism of arterial flow model geometries and investigate factors associated with the localisation of atherosclerosis. The quantification of vascular geometry is also particularly important for the proper design and preclinical testing of endovascular devices used to treat peripheral arterial disease. The purpose of this study was to quantitatively evaluate the intersubject variability of 3D branching and curvature of the abdominal aorta and its major peripheral arteries. Contrast-enhanced renal MRA scans of healthy abdominal vessels obtained in 12... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195786 Wed, 20 Jan 2010 00:00:00 +0100 3195786 http://www.medworm.com/index.php?rid=3195785&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087767%26dopt%3DAbstract This study aims to provide a more complete description of the mechanical properties of spinal dura mater, including the effect of strain rate. Bovine dura mater was tested under uniaxial tension in both the longitudinal and the circumferential directions at three different strain rates; 0.01, 0.1, and 1.0 s(-1). An Ogden model was fitted to the resulting stress-stretch data. The morphology of the dura mater was assessed using Sirius red and H&E staining. No significant effect of the strain rate was found for the Ogden model parameters. Longitudinal specimens were significantly stronger and more deformable than circumferential samples, probably due to the structural arrangement of the collagen fibers. At low strains, however, the circumferential specimens were stiffer than the longitudi... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195785 Wed, 20 Jan 2010 00:00:00 +0100 3195785 http://www.medworm.com/index.php?rid=3195784&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087768%26dopt%3DAbstract Authors: Yuan W, Li G, Fu BM Charge carried by the surface glycocalyx layer (SGL) of the cerebral endothelium has been shown to significantly modulate the permeability of the blood-brain barrier (BBB) to charged solutes in vivo. The cultured monolayer of bEnd3, an immortalized mouse cerebral endothelial cell line, is becoming a popular in vitro BBB model due to its easy growth and maintenance of many BBB characteristics over repeated passages. To test whether the SGL of bEnd3 monolayer carries similar charge as that in the intact BBB and quantify this charge, which can be characterized by the SGL thickness (L ( f )) and charge density (C ( mf )), we measured the solute permeability of bEnd3 monolayer to neutral solutes and to solutes with similar size but opposite charges: negatively c... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195784 Wed, 20 Jan 2010 00:00:00 +0100 3195784 http://www.medworm.com/index.php?rid=3195783&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087769%26dopt%3DAbstract In this study, a simple mathematical-statistical based metric called Multiple Higher Order Moments (MHOM) is introduced enabling the electrocardiogram (ECG) detection-delineation algorithm to yield acceptable results in the cases of ambulatory holter ECG including strong noise, motion artifacts, and severe arrhythmia(s). In the MHOM measure, important geometric characteristics such as maximum value to minimum value ratio, area, extent of smoothness or being impulsive and distribution skewness degree (asymmetry), occult. In the proposed method, first three leads of high resolution 24-h holter data are extracted and preprocessed using Discrete Wavelet Transform (DWT). Next, a sample to sample sliding window is applied to preprocessed sequence and in each slid, mean value, variance, skewness,... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195783 Wed, 20 Jan 2010 00:00:00 +0100 3195783 http://www.medworm.com/index.php?rid=3195782&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087770%26dopt%3DAbstract In conclusion, a ferrocene mediated glucose biosensor incorporated with reverse iontophoresis function was developed. PMID: 20087770 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195782 Wed, 20 Jan 2010 00:00:00 +0100 3195782 http://www.medworm.com/index.php?rid=3195781&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087771%26dopt%3DAbstract Authors: Fan JC, Waldman SD Mechanical stimulation of engineered cartilage constructs is a commonly applied method used to accelerate tissue formation and improve the mechanical properties of the developed tissue. While the effects of compression and shear have been widely studied, the effect of tension has received relatively little attention. As articular cartilage in vivo is subjected to a degree of static tension (pre-tension) even in the absence of externally applied loads, the purpose of this study was to investigate the effect of intermittent static biaxial tensile strains (BTS) on chondrocyte metabolism and resultant tissue formation. Using a custom-design loading fixture to apply BTS, the optimal conditions for stimulating extracellular matrix synthesis were under average magn... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195781 Wed, 20 Jan 2010 00:00:00 +0100 3195781 http://www.medworm.com/index.php?rid=3195780&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087772%26dopt%3DAbstract In this study, we first present experimental results showing significant residual deformations in the longitudinal direction of two commonly studied arteries in the pig: the common carotid artery and the left anterior descending coronary artery. We concluded that a radially cut ring cannot completely describe the stress-free state of the arteries. Instead, we propose the use of a longitudinal opening angle, in conjunction with the traditional circumferential opening angle, to experimentally quantify the stress-free state of an artery. Secondly, we propose a new kinematic model to account for the addition of longitudinal residual strains through employing the longitudinal opening angle and performed a stress analysis. We found that with the inclusion of longitudinal residual strains in the ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195780 Wed, 20 Jan 2010 00:00:00 +0100 3195780 http://www.medworm.com/index.php?rid=3195779&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087773%26dopt%3DAbstract In this study, porous hydroxyapatite/beta-tricalcium phosphate (HAp/beta-TCP), powdered HAp/beta-TCP, and polyglycolic acid (PGA) fiber mesh were used as scaffolds and transplanted with cultured porcine dental pulp-derived cells into the backs of nude mice. Samples were harvested after 6 weeks. Newly-formed hard tissue was observed in all transplants. When porous HAp/beta-TCP was used, dentin-like hard tissue was observed on the inner wall with minimum cell inclusions and odontoblast-like cells were aligned adjacent to the hard tissue. When HAp/beta-TCP powders or PGA were used, bone-like hard tissues showed cell inclusions and cell alignment was not observed. Hard tissue from the HAp/beta-TCP block group was positive for type I collagen, osteonectin, bone sialoprotein and dentin sialoprot... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195779 Wed, 20 Jan 2010 00:00:00 +0100 3195779 http://www.medworm.com/index.php?rid=3195778&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087774%26dopt%3DAbstract Authors: Siebes M, Ventikos Y Biofluid mechanics is increasingly applied in support of diagnosis and decision-making for treatment of clinical pathologies. Exploring the relationship between blood flow phenomena and pathophysiological observations is enhanced by continuing advances in the imaging modalities, measurement techniques, and capabilities of computational models. When combined with underlying physiological models, a powerful set of tools becomes available to address unmet clinical needs, predominantly in the direction of enhanced diagnosis, as well as assessment and prediction of treatment outcomes. This position paper presents an overview of current approaches and future developments along this theme that were discussed at the 5th International Biofluid Symposium and Worksho... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195778 Wed, 20 Jan 2010 00:00:00 +0100 3195778 http://www.medworm.com/index.php?rid=3195777&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087775%26dopt%3DAbstract The objective of our session at the 2008 International Bio-Fluid Symposium and Workshop was to review the state-of-the-art in image-based modeling of blood flow, and identify future directions. Here we summarize progress in the field of image-based modeling of blood flow and vessel wall dynamics from mid-2005 to early 2009. We first describe the tremendous progress made in the application of image-based modeling techniques to elucidate the role of hemodynamics in vascular pathophysiology, plan treatments for congenital and acquired diseases in individual patients, and design and evaluate endovascular devices. We then review the advances that have been made in improving the methodology for modeling blood flow and vessel wall dynamics in image-based models, and consider issues related to ext... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195777 Wed, 20 Jan 2010 00:00:00 +0100 3195777 http://www.medworm.com/index.php?rid=3195776&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20087776%26dopt%3DAbstract In this study, we quantitatively analyzed the effects of acute noninvasive electrical stimulation from concentric ring electrodes (CRE) to determine the maximum safe current limit. We developed a three-dimensional multi-layer model and calculated the temperature profile under the CRE and the corresponding energy density with electrical-thermal coupled field analysis. Infrared thermography was used to measure skin temperature during electrical stimulation to verify the computer simulations. We also performed histological analysis to study cell morphology and characterize any resulting tissue damage. The simulation results are accurate for low energy density distributions. It can also be concluded that as long as the specified energy density applied is kept below 0.92 (A(2)/cm(4).s(-1)), the... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3195776 Wed, 20 Jan 2010 00:00:00 +0100 3195776 http://www.medworm.com/index.php?rid=3189502&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20082141%26dopt%3DAbstract Authors: Kuang MX, Xiao QJ, Cui CY, Kuang NZ, Hong WQ, Hu AR The purpose of this study is to investigate the mechanism of the formation for thoracic impedance change. On the basis of Ohm's law and the electrical field distribution in the cylindrical volume conductor, the formula about the thoracic impedance change are deduced, and they are demonstrated with the model experiment. The results indicate that the thoracic impedance change caused by single blood vessel is directly proportional to the ratio of the impedance change to the basal impedance of the blood vessel itself, to the length of the blood vessel appearing between the current electrodes, and to the basal impedance between two detective electrodes on the chest surface, while it is inversely proportional to the distance betwee... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3189502 Sat, 16 Jan 2010 00:00:00 +0100 3189502 http://www.medworm.com/index.php?rid=3189501&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20082142%26dopt%3DAbstract Authors: Sejdić E, Komisar V, Steele CM, Chau T Dual-axis swallowing accelerometry is a promising noninvasive tool for the assessment of difficulties during deglutition. The resting and anaerobic characteristics of these signals, however, are still unknown. This paper presents a study of baseline characteristics (stationarity, spectral features, and information content) of dual-axis cervical vibrations. In addition, modeling of a data acquisition system was performed to annul any undesired instrumentation effects. Two independent data collection procedures were conducted to fulfil the goals of the study. For baseline characterization, data were acquired from 50 healthy adult subjects. To model the data acquisition (DAQ) system, ten recordings were obtained while the system was ex... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3189501 Sat, 16 Jan 2010 00:00:00 +0100 3189501 http://www.medworm.com/index.php?rid=3179286&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077008%26dopt%3DAbstract Authors: O'Connell BM, Walsh MT The development of restenosis within the coronary arteries after a stenting procedure has been addressed with the development of the drug eluting stent device. However, in recent times the superiority of the drug eluting stent over bare metal stents has been brought into question. A lack of knowledge regarding the behavior of drug transport from the drug eluting devices contributes to this uncertainty. Questions arise as to whether drug eluting stents deliver sufficient amounts of therapeutic agents into the artery wall to suppress restenosis. Published investigations in this area have focused primarily on trends associated with how variations in stenting conditions affect mass transport behavior. However, experimentally validated numerical models that s... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179286 Thu, 14 Jan 2010 00:00:00 +0100 3179286 http://www.medworm.com/index.php?rid=3179285&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077009%26dopt%3DAbstract Authors: Simon HA, Ge L, Borazjani I, Sotiropoulos F, Yoganathan AP PMID: 20077009 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179285 Thu, 14 Jan 2010 00:00:00 +0100 3179285 http://www.medworm.com/index.php?rid=3179284&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077010%26dopt%3DAbstract Authors: O'Cearbhaill ED, Murphy M, Barry F, McHugh PE, Barron V A limitation of current tissue engineering vascular graft technology is the provision of an expandable, autologous cell source. By harnessing the multipotency of mesenchymal stem cells (MSC), it is hoped that functional vascular cells can be produced. To date, a range of 2D and 3D environments have been investigated for the manipulation of MSC differentiation pathways. To this end, this study aims to test the hypothesis that MSC seeded in various fibrin gel environments will exhibit evidence of a smooth muscle cell (SMC) phenotype. Initially, a range of cell-seeding densities were screened for 2D and 3D fibrin constructs, where it was observed that a seeding densities of 500,000 cells/mL facilitated gel compaction without... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179284 Thu, 14 Jan 2010 00:00:00 +0100 3179284 http://www.medworm.com/index.php?rid=3179283&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077011%26dopt%3DAbstract In this study, high-density cultures of glial cells were analyzed by immunohistochemical methods and impedance spectroscopy. Astrocytes and microglia were cultured at various ratios within the matrix surrounding the probes, and were observed over a period of 2 weeks. Cell seeding conditions and confocal images were compared to impedance data to enable the effects of glial cell type on electrode impedance to be determined. PMID: 20077011 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179283 Thu, 14 Jan 2010 00:00:00 +0100 3179283 http://www.medworm.com/index.php?rid=3179282&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077012%26dopt%3DAbstract Authors: Zamir M, Moore JE, Fujioka H, Gaver DP In the field of fluid flow within the human body, focus has been placed on the transportation of blood in the systemic circulation since the discovery of that system; but, other fluids and fluid flow phenomena pervade the body. Some of the most fascinating fluid flow phenomena within the human body involve fluids other than blood and a service other than transport-the lymphatic and pulmonary systems are two striking examples. While transport is still involved in both cases, this is not the only service which they provide and blood is not the only fluid involved. In both systems, filtration, extraction, enrichment, and in general some "treatment" of the fluid itself is the primary function. The study of the systemic circulation has also be... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179282 Thu, 14 Jan 2010 00:00:00 +0100 3179282 http://www.medworm.com/index.php?rid=3179281&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077013%26dopt%3DAbstract Authors: Friedman MH, Krams R, Chandran KB Interactions between flow and biological cells and tissues are intrinsic to the circulatory, respiratory, digestive and genitourinary systems. In the circulatory system, an understanding of the complex interaction between the arterial wall (a living multi-component organ with anisotropic, non-linear material properties) and blood (a shear-thinning fluid with 45% by volume consisting of red blood cells, platelets, and white blood cells) is vital to our understanding of the physiology of the human circulation and the etiology and development of arterial diseases, and to the design and development of prosthetic implants and tissue-engineered substitutes. Similarly, an understanding of the complex dynamics of flow past native human heart valves an... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179281 Thu, 14 Jan 2010 00:00:00 +0100 3179281 http://www.medworm.com/index.php?rid=3179280&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077014%26dopt%3DAbstract Authors: Marinucci L, Balloni S, Becchetti E, Bistoni G, Calvi EM, Lumare E, Ederli F, Locci P When isolated from the iliac crest human mesenchymal stem cells (hMSC) differentiate into osteoblast-like cells with appropriate stimulation in culture. This in vitro study tested the hypothesis that Biostite((R)) and hydroxyapatite (HA) affect proliferation and differentiation of hMSC into osteoblastic cells. Cell proliferation was determined by measuring (3)H-thymidine incorporation into DNA and typical markers of osteoblastic phenotype were determined by RT-PCR assay. No differences emerged in cell proliferation cultures with Biostite((R)) or hydroxyapatite (HA), but gene expression analysis revealed higher expression of collagen, alkaline phosphatase (ALP), osteopontin and bone sialoprote... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179280 Thu, 14 Jan 2010 00:00:00 +0100 3179280 http://www.medworm.com/index.php?rid=3179279&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077015%26dopt%3DAbstract Authors: Vengrenyuk Y, Kaplan TJ, Cardoso L, Randolph GJ, Weinbaum S The aortic sinus lesions of apolipoprotein E knockout (ApoE KO) mice seldom show any signs of fibrous cap disruption, whereas cap ruptures have been recently reported in the proximal part of their brachiocephalic arteries (BCA). We use histology based finite element analysis to evaluate peak circumferential stresses in aortic and BCA lesions from six 42-56 week-old fat-fed ApoE KO mice. This analysis is able to both explain the greater stability of aortic lesions in mice and provide new insight into the BCA lesion as a model for the stability of human lesions with and without microcalcifications in their fibrous caps. The predicted average peak stress in fibrous caps of aortic lesions of 205.8 kPa is significantly low... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179279 Thu, 14 Jan 2010 00:00:00 +0100 3179279 http://www.medworm.com/index.php?rid=3172685&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069364%26dopt%3DAbstract Authors: Chung CA, Ho SY The strategy of tissue engineering includes seeding cells onto porous scaffolds. The cellular construct is cultured in vitro for a period of time before transplantation for the patient. Because of the intrinsic complexity of biological systems, it is valuable to have models of simulation that can assess the culture conditions and optimize experiments. This work presents a mathematical model to account for the effects of glucose and type II collagen on chondrocyte growth under static culture conditions. Dependence of cell growth on collagen was assumed as a biphasic function of collagen quantity, whereby the cell growth rate increases and then decreases with increasing collagen content. Results from simulation were compared with experimental data in literature. ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172685 Wed, 13 Jan 2010 00:00:00 +0100 3172685 http://www.medworm.com/index.php?rid=3172684&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069365%26dopt%3DAbstract Authors: Chan HL, Wang CL, Fang SC, Chao PK, Wei JD Distinguishing ventricular extrasystoles from normal heartbeats is crucial to cardiac arrhythmia analysis. This paper proposes novel morphological descriptors, the major portrait partition area (MPPA) and point distribution percentage (PDP), which are extracted from the reconstructed phase space of the QRS complex. These measures can be linked to QRS width and prolonged ventricular contraction, and offer several advantages over traditional characterization of the QRS structure: it does not require QRS boundary detection, is robust under R-peak misalignment, and including some information from nearby points. The first four principal components of MPPA variables and PDPs in the first and the third quadrants of the phase space diagram we... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172684 Wed, 13 Jan 2010 00:00:00 +0100 3172684 http://www.medworm.com/index.php?rid=3172683&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069366%26dopt%3DAbstract In this study, we model our three random numeric values in each amino acid with occurrence and non-occurrence of mutation, which are classified as unity and zero, using a 3-6-1 feedforward backpropagation neural network to predict the mutation positions in H5N1 neuraminidases. The results show that the neural network can capture the mutation relationship as measured by prediction sensitivity, specificity, and total correct rate. With the help of translation probability between RNA codes and mutated amino acids, we predict the would-be-mutated amino acids at predicted mutation positions. PMID: 20069366 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172683 Wed, 13 Jan 2010 00:00:00 +0100 3172683 http://www.medworm.com/index.php?rid=3172682&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069367%26dopt%3DAbstract Authors: Yamaguchi T, Ishikawa T, Imai Y, Matsuki N, Xenos M, Deng Y, Bluestein D A major computational challenge for a multiscale modeling is the coupling of disparate length and timescales between molecular mechanics and macroscopic transport, spanning the spatial and temporal scales characterizing the complex processes taking place in flow-induced blood clotting. Flow and pressure effects on a cell-like platelet can be well represented by a continuum mechanics model down to the order of the micrometer level. However, the molecular effects of adhesion/aggregation bonds are on the order of nanometer. A successful multiscale model of platelet response to flow stresses in devices and the ensuing clotting responses should be able to characterize the clotting reactions and their interacti... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172682 Wed, 13 Jan 2010 00:00:00 +0100 3172682 http://www.medworm.com/index.php?rid=3172681&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069368%26dopt%3DAbstract Authors: Chung S, Sudo R, Vickerman V, Zervantonakis IK, Kamm RD Recent advances in microfluidic technologies have opened the door for creating more realistic in vitro cell culture methods that replicate many aspects of the true in vivo microenvironment. These new designs (i) provide enormous flexibility in controlling the critical biochemical and biomechanical factors that influence cell behavior, (ii) allow for the introduction of multiple cell types in a single system, (iii) provide for the establishment of biochemical gradients in two- or three-dimensional geometries, and (iv) allow for high quality, time-lapse imaging. Here, some of the recent developments are reviewed, with a focus on studies from our own laboratory in three separate areas: angiogenesis, cell migration in the con... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172681 Wed, 13 Jan 2010 00:00:00 +0100 3172681 http://www.medworm.com/index.php?rid=3172680&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069369%26dopt%3DAbstract In this study, the involvement of histone deacetylase 6 (HDAC6) in modulating migration of ECs co-cultured with VSMCs by the normal level of laminar shear stress (NSS) was investigated. ECs was either cultured alone or co-cultured with VSMCs under static conditions or subjected to NSS of 15 dyne/cm(2) by using a parallel-plate co-culture flow chamber system. It was demonstrated that both NSS and VSMCs could increase EC migration. The migration level of ECs co-cultured with VSMCs under NSS was not higher than that under the static condition. The process of EC migration regulated by VSMCs and NSS was associated with the increased expression of HDAC6 and low level of acetylated tubulin. The increase in HDAC6 expression was accompanied by a time-dependent decrease in the acetylation of tubulin... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172680 Wed, 13 Jan 2010 00:00:00 +0100 3172680 http://www.medworm.com/index.php?rid=3172679&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069370%26dopt%3DAbstract In this study, defibrillation shock efficacy as a function of shock energy was modeled by a dose response relationship. The frequency distributions of the two parameters characterizing this relationship were estimated from a large clinical study on 634 patients. The estimated parameters were then compared to published data on defibrillation studies performing dose response measurements. After having identified the optimal parameter distributions for the whole population, a Monte Carlo method was used to compare the outcomes of two defibrillation efficacy testing protocols: a safety margin test requiring 2 successes out of 2 trials at 20 J, and the binary search protocol used in the clinical study. Results showed good correspondence with clinical observations. The probabilistic nature of de... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172679 Wed, 13 Jan 2010 00:00:00 +0100 3172679 http://www.medworm.com/index.php?rid=3172678&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069371%26dopt%3DAbstract Authors: Krasteva V, Jekova I, Dotsinsky I, Didon JP Minimum "hands-off" intervals during cardiopulmonary resuscitation (CPR) are required to improve the success rate of defibrillation. In support of such life-saving practice, a shock advisory system (SAS) for automatic analysis of the electrocardiogram (ECG) contaminated by chest compression (CC) artefacts is presented. Ease of use for the automated external defibrillators (AEDs) is aimed and therefore only processing of ECG from usual defibrillation pads is required. The proposed SAS relies on assessment of outstanding components of ECG rhythms and CC artefacts in the time and frequency domain. For this purpose, three criteria are introduced to derive quantitative measures of band-pass filtered CC-contaminated ECGs, combined with thr... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172678 Wed, 13 Jan 2010 00:00:00 +0100 3172678 http://www.medworm.com/index.php?rid=3172677&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20069372%26dopt%3DAbstract Authors: Herz SL, Hasegawa T, Makaryus AN, Parker KM, Homma S, Wang J, Holmes JW Stress echocardiography is an important screening test for coronary artery disease. Currently, cardiologists rely on visual analysis of left ventricular (LV) wall motion abnormalities, which is subjective and qualitative. We previously used finite-element models of the regionally ischemic left ventricle to develop a wall motion measure, 3DFS, for predicting ischemic region size and location from real-time 3D echocardiography (RT3DE). The purpose of this study was to validate these methods against regional blood flow measurements during regional ischemia and to compare the accuracy of our methods to the current state of the art, visual scoring by trained cardiologists. We acquired RT3DE images during 20 bri... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3172677 Wed, 13 Jan 2010 00:00:00 +0100 3172677 http://www.medworm.com/index.php?rid=3164600&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20063123%26dopt%3DAbstract Authors: Weinbaum S In this Inaugural Diversity Lecture I trace the diversity struggles in my own life over the past 46 years since the historic 1963 "I Have a Dream" speech of Martin Luther King, which has changed this nation forever. After a brief personal history, the paper is divided into three major parts; "My consciousness raising years", "Fulfilling the dream", and NIH Minority Scholars Program. The paper ends with some concluding thoughts on the importance of being taken seriously. PMID: 20063123 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3164600 Sat, 09 Jan 2010 00:00:00 +0100 3164600 http://www.medworm.com/index.php?rid=3154921&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20058187%26dopt%3DAbstract We present a 3D code-coupling approach which has been specialized towards cardiovascular blood flow. For the first time, the prescribed geometry movement of the cardiovascular flow model KaHMo (Karlsruhe Heart Model) has been replaced by a myocardial composite model. Deformation is driven by fluid forces and myocardial response, i.e., both its contractile and constitutive behavior. Whereas the arbitrary Lagrangian-Eulerian formulation (ALE) of the Navier-Stokes equations is discretized by finite volumes (FVM), the solid mechanical finite elasticity equations are discretized by a finite element (FEM) approach. Taking advantage of specialized numerical solution strategies for non-matching fluid and solid domain meshes, an iterative data-exchange guarantees the interface equilibrium of the un... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3154921 Fri, 08 Jan 2010 00:00:00 +0100 3154921 http://www.medworm.com/index.php?rid=3154920&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20058188%26dopt%3DAbstract Authors: Anderson JC, Hlastala MP The multiple inert gas elimination technique (MIGET) provides a method for estimating alveolar gas exchange efficiency. Six soluble inert gases are infused into a peripheral vein. Measurements of these gases in breath, arterial blood, and venous blood are interpreted using a mathematical model of alveolar gas exchange (MIGET model) that neglects airway gas exchange. A mathematical model describing airway and alveolar gas exchange predicts that two of these gases, ether and acetone, exchange primarily within the airways. To determine the effect of airway gas exchange on the MIGET, we selected two additional gases, toluene and m-dichlorobenzene, that have the same blood solubility as ether and acetone and minimize airway gas exchange via their low water ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3154920 Fri, 08 Jan 2010 00:00:00 +0100 3154920 http://www.medworm.com/index.php?rid=3149404&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20052615%26dopt%3DAbstract We examined the growth and morphology of these transfected cells and their production of type II collagen and MMP-3. We found that IGF-1 and BMP-2 drove the chondrogenesis of ADSCs, which showed mature chondrocyte-like cells and formed cartilage nodules. These cells also produced type II collagen with a reduced production of MMP-3. Our findings suggested that human ADSCs could differentiate into chondrocyte-like cells driven by IGF-1 and BMP-2 and held promises as an abundant and ready source of stem cells for cartilage repair and regeneration. PMID: 20052615 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3149404 Wed, 06 Jan 2010 00:00:00 +0100 3149404 http://www.medworm.com/index.php?rid=3149403&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20052616%26dopt%3DAbstract Authors: Grasa J, Gómez-Benito MJ, González-Torres LA, Asiaín D, Quero F, García-Aznar JM This work presents a portable non-invasive external fixator to assess and monitor fracture healing in real time. To evaluate the potential of this fixator, a transverse osteotomy was performed in the tibia of six adult sheep (mean age 3 +/- 0.5 years and weight 63 +/- 5 kg). The fractures were stabilized by a specially designed unilateral external fixator, which was instrumented by means of a set of strain gauges. Strains in the external surface of the fixator were monitored during all the healing process. A wireless, remote monitoring of the implant was developed through a specially designed external telemetric device. The strain gauges were arranged in two different half-brid... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3149403 Wed, 06 Jan 2010 00:00:00 +0100 3149403 http://www.medworm.com/index.php?rid=3149408&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20049636%26dopt%3DAbstract In this study, we first prepared BMP-2/poly(lactic-co-glycolic acid) (PLGA) delayed-release microspheres, and then combined collagen, the delayed-release microspheres, and rat autologous bone particulates to form four groups of composite grafts with different combinations: collagen in group A; collagen combined with bone particulates in group B; collagen combined with BMP-2/PLGA delayed-release microspheres in group C; and collagen combined with both bone particulates and BMP-2/PLGA delayed-release microspheres in group D. The four groups of composite grafts were implanted into the gluteus maximus pockets in rats. The ectopic osteogenesis and ALP level in group D (experimental group) were compared with those in groups A, B, and C (control groups) to study whether it had higher osteogenic c... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3149408 Tue, 05 Jan 2010 00:00:00 +0100 3149408 http://www.medworm.com/index.php?rid=3149407&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20049637%26dopt%3DAbstract This study evaluated and advanced our overall understanding of the capacity of composite analogue bone models mimic the structural properties of average healthy adult human bones. PMID: 20049637 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3149407 Tue, 05 Jan 2010 00:00:00 +0100 3149407 http://www.medworm.com/index.php?rid=3149406&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20049638%26dopt%3DAbstract Authors: Stinstra J, Macleod R, Henriquez C We introduce a 3D model of cardiac tissue to study at a microscopic level the relationship between tissue morphology and propagation of depolarization. Unlike the classical bidomain approach, in which tissue properties are described by the apparent conductivity of the tissue, in this "microdomain" approach, we included histology by modeling the actual shape of the intracellular and extracellular spaces that contain spatially distributed gap-junctions and membranes. The histological model of the tissue was generated by a computer algorithm that can be tuned to model different histological changes. For healthy tissue, the model predicted a realistic conduction velocity of 0.42 m/s based solely on the parameters derived from histology. A compari... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3149406 Tue, 05 Jan 2010 00:00:00 +0100 3149406 http://www.medworm.com/index.php?rid=3149405&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20049639%26dopt%3DAbstract Authors: Chua EC, Redmond SJ, McDarby G, Heneghan C There is considerable interest in non-intrusive and reliable continuous ambulatory blood pressure measurement systems. Pulse amplitude is the peak to trough amplitude of the photo-plethysmogram signal. We compared pulse amplitude with a currently popular parameter, the pulse arrival time (PAT), for estimating continuous systolic blood pressure (SBP). Overnight sleep data from 18 young, healthy subjects (14 M 4 F, age 24 +/- 5 years, BMI 23.8 +/- 4.0 kg/m(2)) was analyzed. We found that pulse amplitude was more effective than PAT for estimating SBP during sleep. Mean coherence between pulse amplitude and SBP was significantly stronger than that for PAT [p < 0.001, 95% CI: 0.21-0.25 (finger), 0.11-0.14 (wrist)]. Correlation between p... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3149405 Tue, 05 Jan 2010 00:00:00 +0100 3149405 http://www.medworm.com/index.php?rid=3130220&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20039133%26dopt%3DAbstract Authors: Eilaghi A, Flanagan JG, Simmons CA, Ethier CR The biomechanical environment within the optic nerve head, important in glaucoma, depends strongly on scleral biomechanical properties. Here we use a range of measured nonlinear scleral stress-strain relationships in a finite element (FE) model of the eye to compute the biomechanical environment in the optic nerve head at three levels of intraocular pressure (IOP). Three stress-strain relationships consistent with the 5th, 50th and 95th percentiles of measured human scleral stiffness were selected from a pool of 30 scleral samples taken from 10 eyes and implemented in a generic FE model of the eye using a hyperelastic five-parameter Mooney-Rivlin material model. Computed strains within optic nerve head tissues depended strongly on ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3130220 Tue, 29 Dec 2009 00:00:00 +0100 3130220 http://www.medworm.com/index.php?rid=3120666&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20033775%26dopt%3DAbstract This study demonstrated inbred strain-specific compositional and mechanical changes following exercise in WT and KO mice, and showed evidence of genotype-specific changes in bone in response to loading in a gene disruption model. This study further shows that exercise can influence bone tissue composition and/or mechanical integrity without changes in bone geometry. Together, these data suggest that exercise may represent a possible means to alter tissue quality and mechanical deficiencies caused by many diseases of bone. PMID: 20033775 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3120666 Thu, 24 Dec 2009 00:00:00 +0100 3120666 http://www.medworm.com/index.php?rid=3120665&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20033776%26dopt%3DAbstract In conclusion, the spiral or swirling flow may have certain physiological significance in the aorta and play a positive role in the transport of oxygen by enhancing oxygen flux to the arterial wall. PMID: 20033776 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3120665 Thu, 24 Dec 2009 00:00:00 +0100 3120665 http://www.medworm.com/index.php?rid=3120664&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20033777%26dopt%3DAbstract The objectives of this study were to develop an ex vivo artery injury model for studying endothelial cell (EC) migration and to compare it with an in vitro co-culture arterial wall injury model in terms of the effect of flow on EC migration and its effect on SMC migration and proliferation. Our results demonstrated that shear flow improves reendothelialization in the injured area by promoting EC migration. The migration distance of ECs is much smaller in the arteries than in an in vitro cell culture model (3.57 +/- 1.29 mm vs. 5.2 +/- 1.4 cm, p < 0.001). SMC proliferation was significantly less in the EC intact and reendothelialization areas than in the EC denuded areas indicating that reendothelialization suppresses SMC proliferation. Our models provide a new approach to study techniqu... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3120664 Thu, 24 Dec 2009 00:00:00 +0100 3120664 http://www.medworm.com/index.php?rid=3120663&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20033778%26dopt%3DAbstract We report the use of a multi-layer printed coil circuit for powering (36-94 mW) an implantable microbolus infusion pump (MIP) that can be activated remotely for use in drug infusion in nontethered, freely moving small animals. This implantable device provides a unique experimental tool with applications in the fields of animal behavior, pharmacology, physiology, and functional brain imaging. Two different designs are described: a battery-less pump usable when the animal is inside a home-cage surrounded by a primary inductive coil and a pump powered by a rechargeable battery that can be used for studies outside the home-cage. The use of printed coils for powering of small devices by inductive power transfer presents significant advantages over similar approaches using hand-wound coils in te... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3120663 Thu, 24 Dec 2009 00:00:00 +0100 3120663 http://www.medworm.com/index.php?rid=3120662&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20033779%26dopt%3DAbstract Authors: Boulakia M, Cazeau S, Fernández MA, Gerbeau JF, Zemzemi N This paper deals with the numerical simulation of electrocardiograms (ECG). Our aim is to devise a mathematical model, based on partial differential equations, which is able to provide realistic 12-lead ECGs. The main ingredients of this model are classical: the bidomain equations coupled to a phenomenological ionic model in the heart, and a generalized Laplace equation in the torso. The obtention of realistic ECGs relies on other important features-including heart-torso transmission conditions, anisotropy, cell heterogeneity and His bundle modeling-that are discussed in detail. The numerical implementation is based on state-of-the-art numerical methods: domain decomposition techniques and second order semi-implici... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3120662 Thu, 24 Dec 2009 00:00:00 +0100 3120662 http://www.medworm.com/index.php?rid=3115541&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20024623%26dopt%3DAbstract Authors: Chesnutt JK, Marshall JS A set of measures of red blood cell (RBC) aggregates are developed and applied to examine the aggregate structure under plane shear and channel flows. Some of these measures are based on averages over the set of red blood cells which are in contact with each other at a given time. Other measures are developed by first fitting an ellipse to the planar projection of the aggregate, and then examining the area and aspect ratio of the fit ellipse as well as the orientations of constituent RBCs with respect to the fit ellipse axes. The aggregate structural measures are illustrated using a new mesoscale computational model for blood cell transport, collision and adhesion. The sensitivity of this model to change in adhesive surface energy density and shear rat... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3115541 Sat, 19 Dec 2009 00:00:00 +0100 3115541 http://www.medworm.com/index.php?rid=3115540&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20024624%26dopt%3DAbstract Authors: Erickson JC, O'Grady G, Du P, Obioha C, Qiao W, Richards WO, Bradshaw LA, Pullan AJ, Cheng LK High resolution (HR) multi-electrode mapping is increasingly being used to evaluate gastrointestinal slow wave behaviors. To create the HR activation time (AT) maps from gastric serosal electrode recordings that quantify slow wave propagation, it is first necessary to identify the AT of each individual slow wave event. Identifying these ATs has been a time consuming task, because there has previously been no reliable automated detection method. We have developed an automated AT detection method termed falling-edge, variable threshold (FEVT) detection. It computes a detection signal transform to accentuate the high 'energy' content of the falling edges in the serosal recording, and use... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3115540 Sat, 19 Dec 2009 00:00:00 +0100 3115540 http://www.medworm.com/index.php?rid=3105676&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20020211%26dopt%3DAbstract Authors: Peramo A, Marcelo CL, Goldstein SA, Martin DC Cellular apoptosis and proliferation was analyzed in an in vitro culture system of organotypic human skin explants in the presence or absence of external fixator pins. The effect on the tissues of a mixture of hyaluronic acid and dermatan sulfate (HA + DS) delivered at the skin-pin interface was also studied. After 2 weeks in culture, skin specimens interfaced with fixator pins showed increased keratinocyte apoptosis and proliferation compared to specimens without fixator pins. Simultaneously, a relative reduction of apoptosis and proliferation was observed in specimens treated with the HA + DS mixture, regardless of fixation pin presence. In addition, the HA + DS mixture appeared to help in the preservation of the epidermal basal ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3105676 Fri, 18 Dec 2009 00:00:00 +0100 3105676 http://www.medworm.com/index.php?rid=3105675&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20020212%26dopt%3DAbstract Authors: Athanasiou KA PMID: 20020212 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3105675 Fri, 18 Dec 2009 00:00:00 +0100 3105675 http://www.medworm.com/index.php?rid=3105674&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20020213%26dopt%3DAbstract Authors: Li CP, Lo CW, Lu PC Among the clinical complications of mechanical heart valves (MHVs), hemolysis was previously thought to result from Reynolds stresses in turbulent flows. A more recent hypothesis suggests viscous dissipative stresses at spatial scales similar in size to red blood cells may be related to hemolysis in MHVs, but the resolution of current instrumentation is insufficient to measure the smallest eddy sizes. We studied the St. Jude Medical (SJM) 27 mm valve in the aortic position of a pulsatile circulatory mock loop under physiologic conditions with particle image velocimetry (PIV). Assuming a dynamic equilibrium assumption between the resolved and sub-grid-scale (SGS) energy flux, the SGS energy flux was calculated from the strain rate tensor computed from the re... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3105674 Fri, 18 Dec 2009 00:00:00 +0100 3105674 http://www.medworm.com/index.php?rid=3067746&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19967451%26dopt%3DAbstract Authors: Wen D, Androjna C, Vasanji A, Belovich J, Midura RJ In vivo the hydraulic permeability of cortical bone influences the transport of nutrients, waste products and signaling molecules, thus influencing the metabolic functions of osteocytes and osteoblasts. In the current study two hypotheses were tested: the presence of (1) lipids and (2) collagen matrix in the porous compartment of cortical bone restricts its permeability. Our approach was to measure the radial permeability of adult canine cortical bone before and after extracting lipids with acetone-methanol, and before and after digesting collagen with bacterial collagenase. Our results showed that the permeability of adult canine cortical bone was below 4.0 x 10(-17) m(2), a value consistent with prior knowledge. After extra... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3067746 Sat, 05 Dec 2009 00:00:00 +0100 3067746 http://www.medworm.com/index.php?rid=3067747&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19960368%26dopt%3DAbstract This study underscores the need to conduct three-dimensional simulations throughout the cardiac cycle to fully characterize the complexity and thromboembolic potential of the hinge flows. PMID: 19960368 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering) Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3067747 Fri, 04 Dec 2009 00:00:00 +0100 3067747 http://www.medworm.com/index.php?rid=3057475&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19957039%26dopt%3DAbstract Authors: Arnold EM, Ward SR, Lieber RL, Delp SL Computer models that estimate the force generation capacity of lower limb muscles have become widely used to simulate the effects of musculoskeletal surgeries and create dynamic simulations of movement. Previous lower limb models are based on severely limited data describing limb muscle architecture (i.e., muscle fiber lengths, pennation angles, and physiological cross-sectional areas). Here, we describe a new model of the lower limb based on data that quantifies the muscle architecture of 21 cadavers. The model includes geometric representations of the bones, kinematic descriptions of the joints, and Hill-type models of 44 muscle-tendon compartments. The model allows calculation of muscle-tendon lengths and moment arms over a wide range ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3057475 Thu, 03 Dec 2009 00:00:00 +0100 3057475 http://www.medworm.com/index.php?rid=3057474&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19957040%26dopt%3DAbstract Authors: Sierra DA, Enderle JD The linear homeomorphic muscle model proposed by Enderle and coworkers for the rectus eye muscle is fitted to reflect the dynamics of muscles in the head-neck complex, specifically in muscles involved in gaze shifts. This parameterization of the model for different muscles in the neck region will serve to drive a 3D dynamic computer model for the movement of the head-neck complex, including bony structures and soft tissues, and aimed to study the neural control of the complex during fast eye and head movements such as saccades and gaze shifts. Parameter values for the different muscles in the neck region were obtained by optimization using simulated annealing. These linear homeomorphic muscle models provide non-linear force-velocity profiles and linear le... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3057474 Thu, 03 Dec 2009 00:00:00 +0100 3057474 http://www.medworm.com/index.php?rid=3049340&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19953318%26dopt%3DAbstract In this study, we have used computer simulations of one-dimensional AP conduction in a model of rat ventricular myocytes to verify this interpretation. Our results show that compromised intercellular coupling indeed reduces conduction reserve and predict a response to gap junction uncoupling with heptanol that is consistent with experiments. However, our simulations also show that compromised intercellular coupling is insufficient to explain the increased sensitivity to reduced cellular excitability. A thorough investigation of possible underlying mechanisms, suggests that subtle alterations in the voltage-dependence of steady-state gating for the Na(+) current (I (Na)), combined with compromised intercellular coupling, is a likely mechanism for these observations. PMID: 19953318 [PubM... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3049340 Wed, 02 Dec 2009 00:00:00 +0100 3049340 http://www.medworm.com/index.php?rid=3049339&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19953319%26dopt%3DAbstract Authors: Barker AJ, Lanning C, Shandas R Bicuspid aortic valve (BAV) is often concomitant with aortic dilatation, aneurysm, and dissection. This valve lesion and its complications may affect positional and temporal wall shear stress (WSS), a parameter reported to regulate transcriptional events in vascular remodeling. Thus, this pilot study seeks to determine if the WSS in the ascending aorta (AAo) of BAV patients differs from control patients. Phase-contrast magnetic resonance imaging (PC-MRI) was used to perform flow analysis at the level of the AAo in 15 BAV and 15 control patients. Measurement of the aorta dimensions, flow rates, regurgitant fraction (RF), flow reversal ratio (FRR), temporal and spatial WSS, and shear range indices (SRI) were performed. The BAV and control group sh... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3049339 Wed, 02 Dec 2009 00:00:00 +0100 3049339 http://www.medworm.com/index.php?rid=3049338&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19953320%26dopt%3DAbstract In this study, we performed an extensive analysis of the signals, i.e., responses of a microphone implanted in the cuff and pressure changes in the cuff, which can be recorded during such measurements. We applied several methods to separate the cuff deflation from the arterial pressure pulses, as well as to separate the microphone data into an audible part (Korotkoff sounds) and a low frequency part. The oscillometric technique is based on some empirically derived criteria applied to the oscillometric index, which is defined as a certain characteristic physical property of pressure pulses. In addition to the pressure pulses, which are a typical physical property used for the oscillometric index, we also used in this study other properties such as a time derivative and an audible part of da... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3049338 Wed, 02 Dec 2009 00:00:00 +0100 3049338 http://www.medworm.com/index.php?rid=3049337&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19953321%26dopt%3DAbstract Authors: Goldenstein J, Kazakia G, Majumdar S This is the first observational study examining cortical porosity in vivo in postmenopausal osteopenic women and to incorporate data from two different imaging modalities to further examine the nature of cortical porosity. The goal of this study was to combine high-resolution peripheral computed tomography (HR-pQCT) images, which contain high spatial resolution information of the cortical structure, and magnetic resonance (MR) images, which allow the visualization of soft tissues such as bone marrow, to observe the amount of cortical porosity that contains bone marrow in postmenopausal osteopenic women. The radius of 49 and the tibia of 51 postmenopausal osteopenic women (age 56 +/- 3.7) were scanned using both HR-pQCT and MR imaging. A nor... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3049337 Wed, 02 Dec 2009 00:00:00 +0100 3049337 http://www.medworm.com/index.php?rid=3049336&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19953322%26dopt%3DAbstract Authors: Su SW, Huang S, Wang L, Celler BG, Savkin AV, Guo Y, Cheng TM Safe exercise protocols are critical for effective rehabilitation programs. This paper aims to develop a novel control strategy for an automated treadmill system to reduce the danger of injury during cardiac rehabilitation. We have developed a control-oriented nonparametric Hammerstein model for the control of heart rate during exercises by using support vector regression and correlation analysis. Based on this nonparametric model, a model predictive controller has been built. In order to guarantee the safety of treadmill exercise during rehabilitation, this new automated treadmill system is capable of optimizing system performance over predefined ranges of speed and acceleration. The effectiveness of the proposed a... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3049336 Wed, 02 Dec 2009 00:00:00 +0100 3049336 http://www.medworm.com/index.php?rid=3049335&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19953323%26dopt%3DAbstract Authors: Durst CA, Jane Grande-Allen K For many tissues, cyclic mechanical stimulation is considered necessary to maintain the normal morphology in vitro. The aim of this study was to design and evaluate a simple bioreactor system capable of medium-term (more than 2 weeks) culture of native and engineered aortic valves. The system consists of three pistons in separate cylindrical chambers that are simultaneously driven through the culture medium by a crank and cam assembly. The faces of these pistons have unidirectional valves mounted in opposing orientations that permit flow from one side of the face to the other. A custom designed stent was employed to secure either native or engineered trileaflet valves to the pistons. Computational fluid dynamics and finite element modeling was use... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3049335 Wed, 02 Dec 2009 00:00:00 +0100 3049335 http://www.medworm.com/index.php?rid=3049341&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19949976%26dopt%3DAbstract Authors: Walter EJ, Wells SM Mechanical loading conditions are important factors in the gestational development of fetal tissues. However, little is known about how mechanical loading during development modulates the structure and function of elastic tissues. We hypothesized that developing elastic tissues functionally adapt to their loading conditions. To test this hypothesis, we assessed the changes in the composition, viscoelasticity, and thermoelastic properties of elastic tissue from bovine aortas (functional during gestation) and nuchal ligaments (nonfunctional during gestation). Clear differences in the developmental timeline of elastic tissue structure and function were observed between aortic and ligament elastic tissue. Elastic tissue in the aorta developed earlier than that ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3049341 Tue, 01 Dec 2009 00:00:00 +0100 3049341 http://www.medworm.com/index.php?rid=3034152&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19937468%26dopt%3DAbstract Authors: Karch R, Neumann F, Ullrich R, Heinze G, Neumüller J, Podesser BK, Neumann M In the present study, descriptors from the theory of random heterogeneous media were used to characterize the morphology of the myocardial interstitial space in histological sections from hearts of healthy subjects and of patients with idiopathic dilated cardiomyopathy (DCM). Histological sections from resected DCM hearts (n = 9) were compared with donor hearts showing no signs of cardiac disease (n = 6). From control to DCM, the area fraction varphi(1) of the interstitial space increased from 0.13 +/- 0.05 to 0.27 +/- 0.08, the chord-length z from 1.67 +/- 0.61 to 5.56 +/- 1.78 mum, the pore-size delta from 0.72 +/- 0.13 to 1.73 +/- 0.40 mum, the distance r (min) of the first local minimum in th... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3034152 Wed, 25 Nov 2009 00:00:00 +0100 3034152 http://www.medworm.com/index.php?rid=3034151&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19937469%26dopt%3DAbstract Authors: Cruz EG, Kamper DG Stroke is the leading cause of permanent adult disability in the U.S., frequently resulting in chronic motor impairments. Rehabilitation of the upper limb, particularly the hand, is especially important as arm and hand deficits post-stroke limit the performance of activities of daily living and, subsequently, functional independence. Hand rehabilitation is challenging due to the complexity of motor control of the hand. New instrumentation is needed to facilitate examination of the hand. Thus, a novel actuated exoskeleton for the index finger, the FingerBot, was developed to permit the study of finger kinetics and kinematics under a variety of conditions. Two such novel environments, one applying a spring-like extension torque proportional to angular displace... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3034151 Wed, 25 Nov 2009 00:00:00 +0100 3034151 http://www.medworm.com/index.php?rid=3034153&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19937274%26dopt%3DAbstract The objectives of this study were to examine: (1) the conditions over which delivery of bFGF can be controlled from a heparin-binding delivery system (HBDS) and (2) the effect of bFGF and PDGF-BB released from this system on tendon fibroblast proliferation and matrix gene expression in vitro over a 10-day interval. Delivery of bFGF was controlled using a HBDS. Fibrin matrices containing the HBDS retained bFGF better than did matrices lacking the delivery system over the 10-day period studied. Delivery of bFGF and PDGF-BB using the HBDS stimulated tendon fibroblast proliferation and promoted changes in the expression of matrix genes related to tendon gliding, strength, and remodeling. Both growth factors may be effective in enhancing tendon healing in vivo. PMID: 19937274 [PubMed - as s... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3034153 Tue, 24 Nov 2009 00:00:00 +0100 3034153 http://www.medworm.com/index.php?rid=3034156&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19936925%26dopt%3DAbstract Authors: Biasetti J, Gasser TC, Auer M, Hedin U, Labruto F Abdominal Aortic Aneurysms (AAAs), i.e., focal enlargements of the aorta in the abdomen are frequently observed in the elderly population and their rupture is highly mortal. An intra-luminal thrombus is found in nearly all aneurysms of clinically relevant size and multiply affects the underlying wall. However, from a biomechanical perspective thrombus development and its relation to aneurysm rupture is still not clearly understood. In order to explore the impact of blood flow on thrombus development, normal aortas (n = 4), fusiform AAAs (n = 3), and saccular AAAs (n = 2) were compared on the basis of unsteady Computational Fluid Dynamics simulations. To this end patient-specific luminal geometries were segmented from Computeriz... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3034156 Sat, 21 Nov 2009 00:00:00 +0100 3034156 http://www.medworm.com/index.php?rid=3034155&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19936926%26dopt%3DAbstract Authors: Roszelle BN, Deutsch S, Manning KB In order to aid the ongoing concern of limited organ availability for pediatric heart transplants, Penn State has continued development of a pulsatile Pediatric Ventricular Assist Device (PVAD). Initial studies of the PVAD observed an increase in thrombus formation due to differences in flow field physics when compared to adult sized devices, which included a higher degree of three-dimensionality. This unique flow field brings into question the use of 2D planar particle image velocimetry (PIV) as a flow visualization technique, however the small size and high curvature of the PVAD make other tools such as stereoscopic PIV impractical. In order to test the reliability of the 2D results, we perform a pseudo-3D PIV study using planes both parall... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3034155 Sat, 21 Nov 2009 00:00:00 +0100 3034155 http://www.medworm.com/index.php?rid=3034154&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19936927%26dopt%3DAbstract Authors: Liu JX, Chen YS, Chen LF Registration of magnetic resonance brain images is a geometric operation that determines point-wise correspondences between two brains. It remains a difficult task due to the highly convoluted structure of the brain. This paper presents novel methods, Brain Image Registration Tools (BIRT), that can rapidly and accurately register brain images by utilizing the brain structure information estimated from image derivatives. Source and target image spaces are related by affine transformation and non-rigid deformation. The deformation field is modeled by a set of Wendland's radial basis functions hierarchically deployed near the salient brain structures. In general, nonlinear optimization is heavily engaged in the parameter estimation for affine/non-rigid tr... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3034154 Fri, 20 Nov 2009 00:00:00 +0100 3034154 http://www.medworm.com/index.php?rid=3009357&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19921434%26dopt%3DAbstract Authors: Wang L, Huang Y, Pan K, Jiang X, Liu C Recombinant human bone morphogenetic protein-2 (rhBMP-2) and basic fibroblast growth factor (bFGF) are the focus of research pertaining to the stimulation of bone formation. We ascertained the effects of different concentrations rhBMP-2 on proliferation and differentiation of bone marrow stromal cells (BMSCs) in vitro and on ectopic bone formation in rats. BMSCs were obtained from beagle dogs and cultured in medium containing different concentrations rhBMP-2 and bFGF (0, 25, 50, 100, or 200 ng/mL). In a separate experiment, BMSCs were treated with different ratios (1:1, 2:1, 4:1, or 8:1) of rhBMP to bFGF (in each case the concentration of rhBMP was 100 ng/mL and the bFGF concentrations 100, 50, 25, or 12.5 ng/mL). Proliferation and differ... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3009357 Tue, 17 Nov 2009 00:00:00 +0100 3009357 http://www.medworm.com/index.php?rid=3009356&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19921435%26dopt%3DAbstract Authors: Quiceno-Manrique AF, Godino-Llorente JI, Blanco-Velasco M, Castellanos-Dominguez G This work discusses a method for the selection of dynamic features, based on the calculation of the spectral power through time applied to the detection of systolic murmurs from phonocardiographic recordings. To investigate the dynamic properties of the spectral power during murmurs, several quadratic energy distributions have been studied, namely Wigner-Ville, Choi-Williams, smoothed pseudo Wigner-Ville, exponential, and hyperbolic T-distribution. The classification performance has been compared with that using a Short Time Fourier Transform and Continuous Wavelet Transform representations. Furthermore, this work discusses a variety of nonparametric techniques to estimate the spectral power con... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3009356 Tue, 17 Nov 2009 00:00:00 +0100 3009356 http://www.medworm.com/index.php?rid=3009355&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19921436%26dopt%3DAbstract Authors: Gasser TC, Martufi G, Auer M, Folkesson M, Swedenborg J The reliable assessment of Abdominal Aortic Aneurysm rupture risk is critically important in reducing related mortality without unnecessarily increasing the rate of elective repair. Intra-luminal thrombus (ILT) has multiple biomechanical and biochemical impacts on the underlying aneurysm wall and thrombus failure might be linked to aneurysm rupture. Histological slices from 7 ILTs were analyzed using a sequence of automatic image processing and feature analyzing steps. Derived microstructural data was used to define Representative Volume Elements (RVE), which in turn allowed the estimation of microscopic material properties using the non-linear Finite Element Method. ILT tissue exhibited complex microstructural arrangemen... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3009355 Tue, 17 Nov 2009 00:00:00 +0100 3009355 http://www.medworm.com/index.php?rid=3003836&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19911278%26dopt%3DAbstract The objective of this work was to validate the predicted strain distribution and deformed shape of the inferior glenohumeral ligament using experimental data for two subject-specific finite element models: (1) a continuous model including all capsular regions, and (2) a discrete model including only the inferior glenohumeral ligament. The distribution of maximum principal strain and deformed shape of the glenohumeral capsule was determined for a cadaveric shoulder in a joint position frequently associated with dislocation (60 degrees of glenohumeral abduction, 52 degrees of external rotation, and a 25 N anterior load applied to the humerus). The experimental kinematics were then applied to the two finite element models constructed from the geometry and material properties from the same cad... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3003836 Fri, 13 Nov 2009 00:00:00 +0100 3003836 http://www.medworm.com/index.php?rid=3003835&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19911279%26dopt%3DAbstract Authors: Goudoulas TB, Kastrinakis EG, Nychas SG, Papazoglou LG, Kazakos GM, Kosmas PV In the present study synovial fluid (SF) obtained from the stifle joint of healthy adult dogs and of dogs after cranial cruciate ligament rupture was analyzed regarding its rheological characteristics according to the condition of the joint. The viscoelastic and shear flow properties were measured at 25 and 38 degrees C. The results showed that the healthy SF exhibits practically temperature independent viscosity curve and satisfactory viscoelastic characteristics, i.e. G' > G'', over frequencies of 0.05-5 Hz, and characteristic relaxation time lambda of the order of magnitude of 100 s. Creep measurements demonstrate that the zero shear viscosity was in the range of 10-100 Pa s. In shear flow visc... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3003835 Fri, 13 Nov 2009 00:00:00 +0100 3003835 http://www.medworm.com/index.php?rid=2985589&cid=s_37517_169_f&fid=37517&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19902358%26dopt%3DAbstract In this study, we describe a technique to reconstruct AAA geometry from CT images in an inexpensive and streamlined fashion. A 3D reconstruction technique was implemented with a GUI interface in MATLAB using the active contours technique. The lumen and the thrombus of the AAA were segmented individually in two separate protocols and were then joined together into a hybrid surface. This surface was then used to obtain the aortic wall. This method can deal with very poor contrast images where the aortic wall is indistinguishable from the surrounding features. Data obtained from the segmentation of image sets were smoothed in 3D using a Support Vector Machine technique. The segmentation method presented in this paper is inexpensive and has minimal user-dependency in reconstructing AAA geometr... Annals of Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2985589 Tue, 10 Nov 2009 00:00:00 +0100 2985589