Annals of Biomedical EngineeringThis is an RSS file. You can use it to subscribe to this data in your favourite RSS reader, such as GoogleReader, or to display this data on your own website or blog. Subscribe to this data using MyMedWorm.Subscribe to this data using GoogleReader.Subscribe to this data using Bloglines.Subscribe to this data using MyYahoo.

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399 records returned

Osteogenic Responses to Different Concentrations/Ratios of BMP-2 and bFGF in Bone Formation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 ...
Source: Annals of Biomedical Engineering - November 17, 2009 Category: Biomedical Engineering Authors: Wang L, Huang Y, Pan K, Jiang X, Liu C Tags: Ann Biomed Eng Source Type: journals

Selection of Dynamic Features Based on Time-Frequency Representations for Heart Murmur Detection from Phonocardiographic Signals.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 disc...
Source: Annals of Biomedical Engineering - November 17, 2009 Category: Biomedical Engineering Authors: Quiceno-Manrique AF, Godino-Llorente JI, Blanco-Velasco M, Castellanos-Dominguez G Tags: Ann Biomed Eng Source Type: journals

Micromechanical Characterization of Intra-luminal Thrombus Tissue from Abdominal Aortic Aneurysms.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 prope...
Source: Annals of Biomedical Engineering - November 17, 2009 Category: Biomedical Engineering Authors: Gasser TC, Martufi G, Auer M, Folkesson M, Swedenborg J Tags: Ann Biomed Eng Source Type: journals

The Glenohumeral Capsule Should be Evaluated as a Sheet of Fibrous Tissue: A Validated Finite Element Model.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 appli...
Source: Annals of Biomedical Engineering - November 13, 2009 Category: Biomedical Engineering Authors: Moore SM, Ellis B, Weiss JA, McMahon PJ, Debski RE Tags: Ann Biomed Eng Source Type: journals

Rheological Study of Synovial Fluid Obtained from Dogs: Healthy, Pathological, and Post-Surgery, after Spontaneous Rupture of Cranial Cruciate Ligament.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 demonstrat...
Source: Annals of Biomedical Engineering - November 13, 2009 Category: Biomedical Engineering Authors: Goudoulas TB, Kastrinakis EG, Nychas SG, Papazoglou LG, Kazakos GM, Kosmas PV Tags: Ann Biomed Eng Source Type: journals

Three Dimensional Active Contours for the Reconstruction of Abdominal Aortic Aneurysms.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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...
Source: Annals of Biomedical Engineering - November 10, 2009 Category: Biomedical Engineering Authors: Ayyalasomayajula A, Polk A, Basudhar A, Missoum S, Nissim L, Vande Geest JP Tags: Ann Biomed Eng Source Type: journals

A Novel Simulation Strategy for Stent Insertion and Deployment in Curved Coronary Bifurcations: Comparison of Three Drug-Eluting Stents.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study investigates and compares three different second generation DESs when being implanted in the curved main branch of a coronary bifurcation with the aim of providing better insights into the related changes of the mechanical environment. The 3D bifurcation model is based on patient-specific angiographic data that accurately reproduce the in vivo curvatures of the vessel segments. The layered structure of the arterial wall and its anisotropic mechanical behavior are taken into account by applying a novel algorithm to define the fiber orientations. An innovative simulation strategy considering the insertion of a fol...
Source: Annals of Biomedical Engineering - November 7, 2009 Category: Biomedical Engineering Authors: Mortier P, Holzapfel GA, De Beule M, Van Loo D, Taeymans Y, Segers P, Verdonck P, Verhegghe B Tags: Ann Biomed Eng Source Type: journals

Print-and-Peel Fabrication for Microfluidics: What's in it for Biomedical Applications?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article reviews the development and the advances of print-and-peel (PAP) microfabrication. PAP techniques provide means for facile and expedient prototyping of microfluidic devices. Therefore, PAP has the potential for broadening the microfluidics technology by bringing it to researchers who lack regular or any accesses to specialized fabrication facilities and equipment. Microfluidics have, indeed, proven to be an indispensable toolkit for biological and biomedical research and development. Through accessibility to such methodologies for relatively fast and easy prototyping, PAP has the potential to considerably acce...
Source: Annals of Biomedical Engineering - November 7, 2009 Category: Biomedical Engineering Authors: Thomas MS, Millare B, Clift JM, Bao D, Hong C, Vullev VI Tags: Ann Biomed Eng Source Type: journals

Investigation of Pulsatile Flowfield in Healthy Thoracic Aorta Models.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cardiovascular disease is the primary cause of morbidity and mortality in the western world. Complex hemodynamics plays a critical role in the development of aortic dissection and atherosclerosis, as well as many other diseases. Since fundamental fluid mechanics are important for the understanding of the blood flow in the cardiovascular circulatory system of the human body aspects, a joint experimental and numerical study was conducted in this study to determine the distributions of wall shear stress and pressure and oscillatory WSS index, and to examine their correlation with the aortic disorders, especially dissectio...
Source: Annals of Biomedical Engineering - November 5, 2009 Category: Biomedical Engineering Authors: Wen CY, Yang AS, Tseng LY, Chai JW Tags: Ann Biomed Eng Source Type: journals

A System for Recording High Fidelity Cough Sound and Airflow Characteristics.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this study was to develop a system to measure high fidelity voluntary cough sounds to detect lung diseases. To further augment the analysis capability of the system, a non-invasive flow measurement was also incorporated into the design. One of the main design considerations was to increase the fidelity of the recorded sound characteristics by increasing the signal to noise ratio of cough sounds and to minimize acoustical reflections from the environment. To accomplish this goal, a system was designed with a mouthpiece connected to a cylindrical tube. A microphone was attached near the mouthpiece so that it...
Source: Annals of Biomedical Engineering - October 30, 2009 Category: Biomedical Engineering Authors: Goldsmith WT, Mahmoud AM, Reynolds JS, McKinney WG, Afshari AA, Abaza AA, Frazer DG Tags: Ann Biomed Eng Source Type: journals

Purkinje-mediated Effects in the Response of Quiescent Ventricles to Defibrillation Shocks.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study uses a computer modeling approach to assess contributions by the PS to the response to electrical stimulation. Normal sinus rhythm was simulated and epicardial breakthrough sites were distributed in a manner consistent with experimental results. Defibrillation shocks of several strengths and orientations were applied to quiescent ventricles, with and without PS, and electrical activation was analyzed. All shocks induced local polarizations in PS branches parallel to the field, which led to the rapid spread of excitation through the network. This produced early activations at myocardial sites where tissue was une...
Source: Annals of Biomedical Engineering - October 30, 2009 Category: Biomedical Engineering Authors: Boyle PM, Deo M, Plank G, Vigmond EJ Tags: Ann Biomed Eng Source Type: journals

Geometry of the Intervertebral Volume and Vertebral Endplates of the Human Spine.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, existing CT-scans of 77 patients were analyzed to measure the intervertebral disc and vertebral endplate geometry of the lumbar spine. Ten adjacent points on both sides of the vertebrae (S1-superior to T12-inferior) and sagittal and transverse diameters were measured to describe the shape of the caudal and cranial vertebral planes of the vertebrae. It was found that the largest endplate depth is located in the middle or posterior regions of the vertebra, that there is a linear relationship between all inferior endplate depths and the endplate location (p < 0.0001) within the spinal column, and that the su...
Source: Annals of Biomedical Engineering - October 30, 2009 Category: Biomedical Engineering Authors: van der Houwen EB, Baron P, Veldhuizen AG, Burgerhof JG, van Ooijen PM, Verkerke GJ Tags: Ann Biomed Eng Source Type: journals

Editorial.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19862616 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering)
Source: Annals of Biomedical Engineering - October 28, 2009 Category: Biomedical Engineering Authors: McIntire LV Tags: Ann Biomed Eng Source Type: journals

Mathematical Modeling of Flow-Generated Forces in an In Vitro System of Cardiac Valve Development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Heart valve defects are the most common cardiac defects. Therefore, defining the mechanisms of cardiac valve development is critical to our understanding and treatment of these disorders. At early stages of embryonic cardiac development, the heart begins as a simple tube that then becomes constricted into separate atrial and ventricular regions by the formation of small, mound-like structures, called atrioventricular (AV) cushions. As valve development continues, these mounds fuse and then elongate into valve leaflets. A longstanding hypothesis proposes that blood flow-generated shear stress and pressure are critical i...
Source: Annals of Biomedical Engineering - October 28, 2009 Category: Biomedical Engineering Authors: Biechler SV, Potts JD, Yost MJ, Junor L, Goodwin RL, Weidner JW Tags: Ann Biomed Eng Source Type: journals

Changes in the Mechanical Properties and Residual Strain of Elastic Tissue in the Developing Fetal Aorta.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Formed almost exclusively during development, arterial elastic fibers must function for the lifetime of the animal. We have observed dramatic structural and mechanical changes in aortic elastic tissue during gestational and postnatal development. Elastic tissue was isolated from bovine aortas: (i) during late pregnancy and (ii) in adults. Changes in the relative content of aortic elastic tissue were assessed, as were the viscoelastic properties and residual strains of purified aortic elastic tissue rings. As aortic elastic tissue content increased during development, its circumference and thickness increased-but with c...
Source: Annals of Biomedical Engineering - October 27, 2009 Category: Biomedical Engineering Authors: Wells SM, Walter EJ Tags: Ann Biomed Eng Source Type: journals

Mesh Morphing and Response Surface Analysis: Quantifying Sensitivity of Vertebral Mechanical Behavior.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Vertebrae provide essential biomechanical stability to the skeleton. In this work novel morphing techniques were used to parameterize three aspects of the geometry of a specimen-specific finite element (FE) model of a rat caudal vertebra (process size, neck size, and end-plate offset). Material properties and loading were also parameterized using standard techniques. These parameterizations were then integrated within an RSM framework and used to produce a family of FE models. The mechanical behavior of each model was characterized by predictions of stress and strain. A metamodel was fit to each of the responses to yie...
Source: Annals of Biomedical Engineering - October 27, 2009 Category: Biomedical Engineering Authors: Sigal IA, Whyne CM Tags: Ann Biomed Eng Source Type: journals

Effect of Focal Adhesion Proteins on Endothelial Cell Adhesion, Motility and Orientation Response to Cyclic Strain.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Focal adhesion proteins link cell surface integrins and intracellular actin stress fibers and therefore play an important role in mechanotransduction and cell motility. When endothelial cells are subjected to cyclic mechanical strain, time-lapse imaging revealed that cells underwent significant morphological changes with their resultant long axes aligned away from the strain direction. To explore how this response is regulated by focal adhesion-associated proteins the expression levels of paxillin, focal adhesion kinase (FAK), and zyxin were knocked down using gene silencing techniques. In addition, rescue of endogenou...
Source: Annals of Biomedical Engineering - October 27, 2009 Category: Biomedical Engineering Authors: Ngu H, Feng Y, Lu L, Oswald SJ, Longmore GD, Yin FC Tags: Ann Biomed Eng Source Type: journals

Systems Analysis of the Role of Bone Morphogenic Protein 4 in Endothelial Inflammation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Shear stress is an important factor in the onset and progression of atherosclerosis. High and unidirectional laminar stress is seen as protective, while low and oscillatory shear stress is considered pro-inflammatory and pro-atherogenic. The mechanosensitive response of endothelial cells is governed by a complex system of genes, proteins, and signals that operate at distinctly different time scales. We propose a dynamic mathematical model that quantitatively describes this mechanosensing system and permits novel insights into its functioning. The model, the first of its kind, is constructed within the guidelines of Bio...
Source: Annals of Biomedical Engineering - October 23, 2009 Category: Biomedical Engineering Authors: Yin W, Jo H, Voit EO Tags: Ann Biomed Eng Source Type: journals

An Integrated Computational and Experimental Model of Nitric Oxide-Red Blood Cell Interactions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we developed a flow system that uses gaseous delivery of NO through a polymeric semi-permeable membrane to obtain precise and uniform NO concentrations for NO-RBC interactions. We conducted experiments using the flow system to study the effect of NO concentrations, hematocrit and RBC suspension flow rates on NO-RBC interactions. We developed a computational model to simulate NO transport and to estimate the reaction rate constant for NO-RBC interaction in the flow system. Our results showed that NO consumption of RBCs (i) increased linearly with an increase in available NO, and (ii) decreased with increase i...
Source: Annals of Biomedical Engineering - October 21, 2009 Category: Biomedical Engineering Authors: Deonikar P, Kavdia M Tags: Ann Biomed Eng Source Type: journals

A Comparative Study of Intracranial EEG Files Using Nonlinear Classification Methods.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study is a comparative evaluation of nonlinear classification methods with a focus on nonlinear decision functions and the standard method of support vector machines for seizure detection. These nonlinear classification methods are used on key features that were extracted on subdural EEG data after a thorough evaluation of all the frequency bands from 1 to 44 Hz. The sensitivity, specificity, and accuracy of seizure detection reveal that the gamma frequencies (36-44 Hz) are most suitable for detecting seizure files using a unique 2D decisional plane. We evaluated 157 intracranial EEG files from 14 patients by calculat...
Source: Annals of Biomedical Engineering - October 16, 2009 Category: Biomedical Engineering Authors: Tito M, Cabrerizo M, Ayala M, Jayakar P, Adjouadi M Tags: Ann Biomed Eng Source Type: journals

Prediction of Extravascular Burden of Carbon Monoxide (CO) in the Human Heart.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Clinically significant myocardial abnormalities (e.g., arrhythmias, S-T elevation) occur in patients with mild-to-severe carbon monoxide (CO) poisoning. We enhanced our previous whole body model [Bruce, E. N., M. C. Bruce, and K. Erupaka. Prediction of the rate of uptake of carbon monoxide from blood by extravascular tissues. Respir. Physiol. Neurobiol. 161(2):142-159, 2008] by adding a cardiac compartment (containing three vascular and two tissue subcompartments differing in capillary density) to predict myocardial carboxymyoglobin (MbCO) and oxygen tensions (P(c)O(2)) for several CO exposure regimens at rest and duri...
Source: Annals of Biomedical Engineering - October 15, 2009 Category: Biomedical Engineering Authors: Erupaka K, Bruce EN, Bruce MC Tags: Ann Biomed Eng Source Type: journals

Distinguishing Separate Components in High-dimensional Signals by Using the Modified Embedding Method and Forecasting.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The non-linear analysis of medium- and high-dimensional signals (HDS) encounters often difficulties due to the problem of the choice of the proper window width. This problem occurs due to the fact that the autocorrelation time (tau) of HDS reflecting the natural scale of the signal is similar or higher than the predictability of HDS and the predictability points to some degree to the maximal acceptable window width (W). The new approach to the embedding process is proposed in this paper that uses the constant W instead of the constant L. The lag is calculated by using the formula L = W/(m - 1). If L is non-integer, the...
Source: Annals of Biomedical Engineering - October 13, 2009 Category: Biomedical Engineering Authors: Michalak KP Tags: Ann Biomed Eng Source Type: journals

Transient Absorption of Inhaled Vapors into a Multilayer Mucus-Tissue-Blood System.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this study was to evaluate the mass transport of sample chemical species through a simple multilayer system composed of mucus, tissue, and blood components on a transient basis. Individual multilayer models were considered that represent the wall dimensions of the nasal extrathoracic (ET(2)), bronchial (BB), and bronchiolar (bb) airways. Sample vapors considered were acetaldehyde and benzene, which are highly soluble and moderately soluble in mucus, respectively. To determine absorption, mass transport was calculated based on an existing analytical steady state solution, a new analytical transient solution...
Source: Annals of Biomedical Engineering - October 13, 2009 Category: Biomedical Engineering Authors: Tian G, Longest PW Tags: Ann Biomed Eng Source Type: journals

Development of Personalized Annuloplasty Rings: Combination of CT Images and CAD-CAM Tools.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Although the use of personalized annuloplasty rings manufactured for each patient according to the size and morphology of their valve complex could be beneficial for the treatment of mitral insufficiency, this possibility has been limited for reasons of timelines and costs as well as for design and manufacturing difficulties, as has been the case with other personalized implant and prosthetic developments. However, the present quality of medical image capture equipment together with the benefits to be had from computer-aided design and manufacturing technologies (CAD-CAM) and the capabilities furnished by rapid prototy...
Source: Annals of Biomedical Engineering - October 13, 2009 Category: Biomedical Engineering Authors: Díaz Lantada A, Valle-Fernández RD, Morgado PL, Muñoz-García J, Muñoz Sanz JL, Munoz-Guijosa JM, Otero JE Tags: Ann Biomed Eng Source Type: journals

Synthetic Materials in the Study of Cell Response to Substrate Rigidity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
While it has long been understood that cells can sense and respond to a variety of stimuli, including soluble and insoluble factors, light, and externally applied mechanical stresses, the extent to which cells can sense and respond to the mechanical properties of their environment has only recently begun to be studied. Cell response to substrate stiffness has been suggested to play an important role in processes ranging from developmental morphogenesis to the pathogenesis of disease states and may have profound implications for cell and tissue culture and tissue engineering. Given the importance of this phenomenon, the...
Source: Annals of Biomedical Engineering - October 8, 2009 Category: Biomedical Engineering Authors: Nemir S, West JL Tags: Ann Biomed Eng Source Type: journals

Molecular Modeling and Affinity Determination of scFv Antibody: Proper Linker Peptide Enhances Its Activity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, a dual approach that coordinates molecule modeling, biological measurements, and affinity evaluation was developed to quantify the binding activity of a novel stable miniaturized anti-CD20 antibody or single-chain fragment variable (scFv) with a linker peptide. Upon computer-guided homology modeling, distance geometry analysis, and molecular superimposition and optimization, three new linker peptides PT1, PT2, and PT3 with respective 7, 10, and 15 residues were proposed and three engineered antibodies were then constructed by linking the cloned V (H) and V (L) domains and fusing to a derivative of human IgG1...
Source: Annals of Biomedical Engineering - October 8, 2009 Category: Biomedical Engineering Authors: Gu X, Jia X, Feng J, Shen B, Huang Y, Geng S, Sun Y, Wang Y, Li Y, Long M Tags: Ann Biomed Eng Source Type: journals

A Method to Replicate the Microstructure of Heart Tissue In Vitro Using DTMRI-Based Cell Micropatterning.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A novel cell culture methodology is described in which diffusion tensor magnetic resonance imaging (DTMRI) and cell micropatterning are combined to fabricate cell monolayers that replicate realistic cross-sectional tissue structure. As a proof-of-principle, neonatal rat ventricular myocyte (NRVM) monolayers were cultured to replicate the tissue microstructure of murine ventricular cross-sections. Specifically, DTMRI-measured in-plane cardiac fiber directions were converted into soft-lithography photomasks. Silicone stamps fabricated from the photomasks deposit fibronectin patterns to guide local cellular alignment. Fib...
Source: Annals of Biomedical Engineering - October 5, 2009 Category: Biomedical Engineering Authors: Badie N, Satterwhite L, Bursac N Tags: Ann Biomed Eng Source Type: journals

Biomechanical Assessment of Brain Dynamic Responses Due to Blast Pressure Waves.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A mechanized and integrated computational scheme is introduced to determine the human brain responses in an environment where the human head is exposed to explosions from trinitrotoluene (TNT), or other high-yield explosives, in military applications. The procedure is based on a three-dimensional (3-D) non-linear finite element method (FEM) that implements a simultaneous conduction of explosive detonation, shock wave propagation, blast-head interactions, and the confronting human head. The processes of blast propagation in the air and blast interaction with the head are modeled by an Arbitrary Lagrangian-Eulerian (ALE)...
Source: Annals of Biomedical Engineering - October 5, 2009 Category: Biomedical Engineering Authors: Chafi MS, Karami G, Ziejewski M Tags: Ann Biomed Eng Source Type: journals

Constitutive Modeling of Liver Tissue: Experiment and Theory.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Realistic surgical simulation requires incorporation of the mechanical properties of soft tissue in mathematical models. In actual deformation of soft-tissue during surgical intervention, the tissue is subject to tension, compression, and shear. Therefore, characterization and modeling of soft-tissue in all these three deformation modes are necessary. In this paper we applied two types of pure shear test, unconfined compression and uniaxial tension test to characterize porcine liver tissue. Digital image correlation technique was used to accurately measure the tissue deformation field. Due to gravity and its effect on ...
Source: Annals of Biomedical Engineering - October 5, 2009 Category: Biomedical Engineering Authors: Gao Z, Lister K, Desai JP Tags: Ann Biomed Eng Source Type: journals

High-Resolution Fluid-Structure Interaction Simulations of Flow Through a Bi-Leaflet Mechanical Heart Valve in an Anatomic Aorta.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have performed high-resolution fluid-structure interaction simulations of physiologic pulsatile flow through a bi-leaflet mechanical heart valve (BMHV) in an anatomically realistic aorta. The results are compared with numerical simulations of the flow through an identical BMHV implanted in a straight aorta. The comparisons show that although some of the salient features of the flow remain the same, the aorta geometry can have a major effect on both the flow patterns and the motion of the valve leaflets. For the studied configuration, for instance, the BMHV leaflets in the anatomic aorta open much faster and undergo ...
Source: Annals of Biomedical Engineering - October 5, 2009 Category: Biomedical Engineering Authors: Borazjani I, Ge L, Sotiropoulos F Tags: Ann Biomed Eng Source Type: journals

Thermal Imaging of Cutaneous Temperature Modifications in Runners During Graded Exercise.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper we used high-resolution thermal imaging to visualize the human whole body anterior cutaneous temperature (T (c)) variations in well-trained runners during graded exercise. Fifteen male volunteers underwent a graded treadmill test until reaching their individual maximal heart rate. Total body T (c) decreased as the subjects started the exercise. Thighs and forearms exhibited the earliest response. A further T (c) diminution occurred with the progress of the exercise. At the exercise interruption, T (c) values were in average 3-5 degrees C lower than at baseline. T (c) increased during recovery from exercis...
Source: Annals of Biomedical Engineering - October 1, 2009 Category: Biomedical Engineering Authors: Merla A, Mattei PA, Di Donato L, Romani GL Tags: Ann Biomed Eng Source Type: journals

Nanobioengineering is a rapidly growing field in biomedical engineering. Introduction to the Special Issue.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19764120 [PubMed - in process] (Source: Annals of Biomedical Engineering)
Source: Annals of Biomedical Engineering - September 20, 2009 Category: Biomedical Engineering Authors: Bao G, Rastegar S Tags: Ann Biomed Eng Source Type: journals

Irregular Changes in the Structure of Flowing Blood at Low Flow Conditions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The structural organization of the dispersed phase of blood was studied by measuring the conductance (G) and the capacitance (C) of red blood cell (RBC) suspensions flowing in a vertical channel. Steady-state C and G signals exhibit erratic fluctuations around mean values; the root mean square of the fluctuating signals decreases rapidly as the average flow rate (<upsilon>) increases from 0.21 to ~4.17 mm/s and then less rapidly at higher velocities. The intensity of oscillations is substantially reduced for suspensions with weaker aggregating media. Analysis of the fluctuations performed in the framework of the ...
Source: Annals of Biomedical Engineering - September 17, 2009 Category: Biomedical Engineering Authors: Pribush A, Meiselman HJ, Meyerstein D, Meyerstein N Tags: Ann Biomed Eng Source Type: journals

Differences in the Crack Resistance of Interstitial, Osteonal and Trabecular Bone Tissue.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The purpose of this work was to investigate differences which may exist in the crack resistance of the microstructural bone tissues, i.e., osteonal, interstitial and trabecular bone. Indentations, using varying loads were used to initiate cracks of the same size scale as those which exist habitually in bone. The crack lengths and corresponding toughness values are presented for each of the tissues. Specimens were prepared using standard nanoindentation preparation techniques. Young's modulus and hardness were measured using a Berkovich tip, while cracks were produced using a cube-corner tip. Crack lengths were subseque...
Source: Annals of Biomedical Engineering - September 17, 2009 Category: Biomedical Engineering Authors: Mullins LP, Sassi V, McHugh PE, Bruzzi MS Tags: Ann Biomed Eng Source Type: journals

Modulation of ATP/ADP Concentration at the Endothelial Cell Surface by Flow: Effect of Cell Topography.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Determining how flow affects the concentration of the adenine nucleotides ATP and ADP at the vascular endothelial cell (EC) surface is essential for understanding flow-induced mobilization of intracellular calcium. Previously, mathematical models were formulated to describe the ATP/ADP concentration at the EC surface; however, all previous models assumed the endothelium to be flat. In the present study we investigate the effect of surface undulations on ATP/ADP concentration at the EC surface. The results demonstrate that under certain geometric and flow conditions, the ATP + ADP concentration at the EC surface is cons...
Source: Annals of Biomedical Engineering - September 17, 2009 Category: Biomedical Engineering Authors: Choi HW, Barakat AI Tags: Ann Biomed Eng Source Type: journals

Feasible Stability Region in the Frontal Plane During Human Gait.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The inability to adequately control the motion of the center of mass (COM) in the frontal plane may result in a loss of balance causing a sideways fall during human gait. The primary purposes of this study were (1) to derive the feasible stability region (FSR) in the mediolateral direction, and (2) to compare the FSR with the COM motion state taken from 193 trials among 39 young subjects at liftoff during walking at different speeds. The lower boundary of the FSR was derived, at a given initial COM location, as the minimum rightward COM velocity, at liftoff of the left foot, required to bring the COM into the base of s...
Source: Annals of Biomedical Engineering - September 16, 2009 Category: Biomedical Engineering Authors: Yang F, Espy D, Pai YC Tags: Ann Biomed Eng Source Type: journals

A Controllably Anisotropic Conductivity or Diffusion Phantom Constructed from Isotropic Layers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Phantoms with controllable and well-defined anisotropy are needed to test methods for imaging electrical anisotropy. We developed and tested a phantom that had properties similar to a homogeneous anisotropic conductive medium. The phantom was constructed with alternate slices of isotropic gel having different conductivities. The degree of anisotropy in the phantom could be varied easily by changing the relative conductivity of the two gels. We tested the stability of several phantoms and found their properties were maintained for approximately 8 h following construction. The phantom has application to electrical impeda...
Source: Annals of Biomedical Engineering - September 15, 2009 Category: Biomedical Engineering Authors: Sadleir RJ, Neralwala F, Te T, Tucker A Tags: Ann Biomed Eng Source Type: journals

Computational Simulations of Magnetic Particle Capture in Arterial Flows.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The aim of Magnetic Drug Targeting (MDT) is to concentrate drugs, attached to magnetic particles, in a specific part of the human body by applying a magnetic field. Computational simulations are performed of blood flow and magnetic particle motion in a left coronary artery and a carotid artery, using the properties of presently available magnetic carriers and strong superconducting magnets (up to B approximately 2 T). For simple tube geometries it is deduced theoretically that the particle capture efficiency scales as [Formula: see text], with Mn (p) the characteristic ratio of the particle magnetization force and the ...
Source: Annals of Biomedical Engineering - September 15, 2009 Category: Biomedical Engineering Authors: Haverkort JW, Kenjereš S, Kleijn CR Tags: Ann Biomed Eng Source Type: journals

The Feasibility of Irreversible Electroporation for the Treatment of Breast Cancer and Other Heterogeneous Systems.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study investigates applying IRE to treat primary breast tumors located within a fatty extracellular matrix despite IREs dependence on the heterogeneous properties of tissue. In vitro experiments were performed on MDA-MB-231 human mammary carcinoma cells to determine a baseline electric field threshold (1000 V/cm) to cause IRE for a given set of pulse parameters. The threshold was incorporated into a three-dimensional numerical model of a heterogeneous system to simulate IRE treatments. Treatment-relevant protocols were found to be capable of treating targeted tissue over a large range of heterogeneous properties witho...
Source: Annals of Biomedical Engineering - September 14, 2009 Category: Biomedical Engineering Authors: Neal RE, Davalos RV Tags: Ann Biomed Eng Source Type: journals

Detecting Mitoses in Time-Lapse Images of Embryonic Epithelia Using Intensity Analysis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Although the frequency and orientation of mitoses can significantly affect the mechanics of early embryo development, these data have not been available due to a shortage of suitable automated techniques. Fluorescence imaging, though popular, requires biochemical intervention and is not always possible or desirable. Here, a new technique that takes advantage of a localized intensity change that occurs in bright field images is used to identify mitoses. The algorithm involves mapping a deformable, sub-cellular triangular mesh from one time-lapse image to the next so that corresponding regions can be identified. Triangle...
Source: Annals of Biomedical Engineering - September 14, 2009 Category: Biomedical Engineering Authors: Siva P, Brodland GW, Clausi D Tags: Ann Biomed Eng Source Type: journals

Effect of Eddy Length Scale on Mechanical Loading of Blood Cells in Turbulent Flow.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this work is to investigate the effect of turbulent eddy length scale on blood cell damage, and in particular to test the hypothesis that only eddies similar in size to blood cells can cause damage. The microscale flow near a red blood cell (RBC) in an idealized turbulent eddy is modeled computationally using an immersed boundary method. The model is validated for the special case of a tank-treading RBC. In comparisons between turbulent flow fields, based on Kolmogorov theory, the model predicts that damage due to the smallest eddies is almost independent of the Kolmogorov length scale. The model predicts ...
Source: Annals of Biomedical Engineering - September 14, 2009 Category: Biomedical Engineering Authors: Dooley PN, Quinlan NJ Tags: Ann Biomed Eng Source Type: journals

Wall Shear Stress and Pressure Distribution on Aneurysms and Infundibulae in the Posterior Communicating Artery Bifurcation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A growing number of cases of rupture at an infundibulum, progression of infundibulum to a frank aneurysm, and subarachnoid hemorrhage (SAH) in the posterior communicating artery (PCoA) have been reported. Using patient-specific geometric models of the supraclinoid internal carotid artery (ICA) with PCoA infundibulum or aneurysm, high-resolution computational fluid dynamics simulations were performed by solving the Navier-Stokes equations with a spectral/hp element method. Simulation results show that the flow impinges at the distal wall of infundibulum near the outside of the ICA bend and creates a region of higher pre...
Source: Annals of Biomedical Engineering - September 11, 2009 Category: Biomedical Engineering Authors: Baek H, Jayaraman MV, Karniadakis GE Tags: Ann Biomed Eng Source Type: journals

Chondrogenesis and Integration of Mesenchymal Stem Cells Within an In Vitro Cartilage Defect Repair Model.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this study was to compare the in vitro chondrogenic differentiation and integration of agarose hydrogels seeded with either chondrocytes or bone marrow-derived mesenchymal stem cells (MSCs) in defects created in cartilage explants. Chondrocytes and MSCs were isolated from porcine donors, suspended in 2% agarose and then injected into cylindrical defects within the explants. These constructs were maintained in a chemically defined medium supplemented with 10 ng/mL of TGF-beta3. Cartilage integration was assessed by histology and mechanical push-out tests. After 6 weeks in culture, chondrocyte-seeded constru...
Source: Annals of Biomedical Engineering - September 11, 2009 Category: Biomedical Engineering Authors: Vinardell T, Thorpe SD, Buckley CT, Kelly DJ Tags: Ann Biomed Eng Source Type: journals

Log Energy Entropy-Based EEG Classification with Multilayer Neural Networks in Seizure.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, normal EEG series recorded from healthy volunteers and epileptic EEG series recorded from patients within and without seizure are classified by using Multilayer Neural Network (MLNN) architectures with respect to several time domain entropy measures such as Shannon Entropy (ShanEn), Log Energy Entropy (LogEn), and Sample Entropy (Sampen). In tests, the MLNN is performed with several numbers of neurons for both one hidden layer and two hidden layers. The results show that segments in seizure have significantly lower entropy values than normal EEG series. This result indicates an important increase of EEG regu...
Source: Annals of Biomedical Engineering - September 10, 2009 Category: Biomedical Engineering Authors: Aydın S, Saraoğlu HM, Kara S Tags: Ann Biomed Eng Source Type: journals

A Conductivity Approach to Measuring Fixed Charge Density in Intervertebral Disc Tissue.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A new method for measuring the fixed charge density (FCD) in intervertebral disc (IVD) tissues employing a two-point electrical conductivity approach was developed. In this technique, the tissue is first confined and equilibrated in a potassium chloride (KCl) solution, and the tissue conductivity is then measured. This is then repeated with a second concentration of KCl solution. The FCD can be determined from the conductivity measurements. Using this method, the FCD values of bovine annulus fibrosus (AF) and nucleus pulposus (NP) tissues were determined to be 0.060 +/- 0.027 mEq/g wet tissue and 0.19 +/- 0.039 mEq/g w...
Source: Annals of Biomedical Engineering - September 10, 2009 Category: Biomedical Engineering Authors: Jackson AR, Yuan TY, Huang CY, Gu WY Tags: Ann Biomed Eng Source Type: journals

Finger Thermoregulatory Model Assessing Functional Impairment in Raynaud's Phenomenon.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study we use Control System Theory to model finger thermoregulatory processes in response to a standardized cold challenge (a diagnostic test routinely performed for differential diagnosis of RP). The proposed model is based on a homeostatic negative feedback loop, characterized by five distinct parameters which describe how the control mechanisms are activated and maintained. Thermal infrared imaging data from 14 systemic sclerosis subjects (SSc), 14 PRP, and 16 healthy control subjects (HCS) were processed. HCS presented the fastest active recovery, with the highest gain. PRP presented the slowest and weakest rec...
Source: Annals of Biomedical Engineering - September 3, 2009 Category: Biomedical Engineering Authors: Mariotti A, Grossi G, Amerio P, Orlando G, Mattei PA, Tulli A, Romani GL, Merla A Tags: Ann Biomed Eng Source Type: journals

Introduction to the Special Issue.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Authors: PMID: 19731035 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering)
Source: Annals of Biomedical Engineering - September 3, 2009 Category: Biomedical Engineering Tags: Ann Biomed Eng Source Type: journals

A Mathematical Model of Drug Release from Liposomes by Low Frequency Ultrasound.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Administration of drugs using small (<100 nm) unilamellar liposomes enables effective targeting of tumors and inflamed tissue. Therapeutic efficacy may be enhanced by triggering liposomal drug release in the desired organ in a controlled manner using a noninvasive external signal. Previous studies have demonstrated that low frequency ultrasound (LFUS) can be used to control the release of drugs from liposomes. LFUS irradiation has a twofold effect: (1) it causes the impermeable liposome membrane to become permeable and (2) it induces liposome disintegration. Immediately upon cessation of LFUS irradiation the membran...
Source: Annals of Biomedical Engineering - September 2, 2009 Category: Biomedical Engineering Authors: Enden G, Schroeder A Tags: Ann Biomed Eng Source Type: journals

Three-Wall Segment (TriSeg) Model Describing Mechanics and Hemodynamics of Ventricular Interaction.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, the TriSeg model enables realistic simulation of ventricular mechanics including interaction between left and right ventricular pump mechanics, dynamics of septal geometry, and myofiber mechanics in the three ventricular walls. PMID: 19718527 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering)
Source: Annals of Biomedical Engineering - August 28, 2009 Category: Biomedical Engineering Authors: Lumens J, Delhaas T, Kirn B, Arts T Tags: Ann Biomed Eng Source Type: journals

Augmenting Regional Cerebral Blood Flow Using External-to-Internal Carotid Artery Flow Diversion Method.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this study was to assess the effect of flow diversion by external carotid artery (ECA) occlusion on ipsilateral regional cerebral blood flow (rCBF). Local cerebral hyperperfusion in rats (n = 12) was induced by ligating the right ECA. Ipsilateral rCBF was determined pre- and post-ligation for 120 min using a laser Doppler flow meter. Sham animals (n = 6) were subjected to the craniotomy without ligation of the right ECA. In a separate series of rats (n = 5), brain tissue oxygen levels (pO(2)) in the right and left brain hemispheres were determined before and 90 min after ligation of the right ECA using a t...
Source: Annals of Biomedical Engineering - August 27, 2009 Category: Biomedical Engineering Authors: Divani AA, Berezina TL, Vazquez G, Zaets SB, Tummala R, Qureshi AI Tags: Ann Biomed Eng Source Type: journals