NMR in Biomedicine via MedWorm.com

Neurochemical profile of the mouse hypothalamus using in vivo 1H MRS at 14.1T

NMR in Biomedicine — Wed, 17 Mar 2010 00:00:00 +0100

The hypothalamus plays an essential role in the central nervous system of mammals by among others regulating glucose homeostasis, food intake, temperature, and to some extent blood pressure. Assessments of hypothalamic metabolism using, e.g. 1H MRS in mouse models can provide important insights into its function. To date, direct in vivo 1H MRS measurements of hypothalamus have not been reported. Here, we report that in vivo single voxel measurements of mouse hypothalamus are feasible using 1H MRS at 14.1T. Localized 1H MR spectra from hypothalamus were obtained unilaterally (2-2.2 µL, VOI) and bilaterally (4-4.4 µL) with a quality comparable to that of hippocampus (3-3.5 µL). Using LCModel, a neurochemical profile consisting of 21 metabolites was quantified for both hypothalamus and hip...

BOLD background gradient contributions in diffusion-weighted fMRI - comparison of spin-echo and twice-refocused spin-echo sequences

NMR in Biomedicine — Tue, 16 Mar 2010 00:00:00 +0100

The interaction ('cross terms') between diffusion-weighting gradients and susceptibility-induced background gradient fields around vessels has an impact on apparent diffusion coefficient (ADC) measurements and diffusion-weighted functional magnetic resonance imaging (DFMRI) experiments. Monte-Carlo (MC) simulations numerically integrating the Bloch equations for a large number of random walks in a vascular model were used to investigate to what extent such interactions would influence the extravascular signal change as well as the ADC change observed in DFMRI experiments. The vascular model consists of a set of independent, randomly oriented, infinite cylinders whose internal magnetic susceptibility varies as the state changes between rest and activation. In such a network, the cross terms...

Comparative 1H NMR studies of saturation transfer in copolymer gels and mouse lenses

NMR in Biomedicine — Tue, 16 Mar 2010 00:00:00 +0100

Saturation transfer in cross-linked copolymer gels and excised intact and perforating trauma-induced cataract mouse lenses (4- or 8-week-old) were studied using intermolecular cross-relaxation rates (1/TIS(H2O); 1/TIS), monitored with f2-irradiation at -8.79, -4.00, and 7.13 ppm ([gamma]H2/2[pi] [sim] 69 Hz). [1] The 1/TIS(7.13 ppm) vs dry weight [W (%)] profiles for hydrophilic copolymer gels were far steeper than those for hydrophobic copolymer gels, indicating the participation of an amount of bound water and a number of copolymer hydroxyl groups in the saturation transfer process. In contrast, the 1/TIS(-8.79 ppm) vs W (%) profiles exhibited little difference between the hydrophilic and hydrophobic copolymer gels, indicating the major participation of molecular rigidity, i.e. W (%) in ...

Invasive ductal carcinoma: correlation of apparent diffusion coefficient value with pathological prognostic factors

NMR in Biomedicine — Mon, 15 Mar 2010 00:00:00 +0100

The aim of this study was to correlate the apparent diffusion coefficient (ADC) value of invasive ductal carcinoma with pathological prognostic factors. A prospective study was conducted on 59 untreated female patients (mean age 46 years) with invasive ductal carcinoma. All patients were examined at 1.5 Tesla using dedicated bilateral breast coil. They underwent diffusion weighted MR imaging of the breast using a single shot echo planar imaging with a b-factor of 200 and 400 sec/mm2. Apparent diffusion coefficient (ADC) maps were reconstructed. The ADC value of the breast cancer was calculated and correlated with the pathologic prognostic factors (tumor size, grade and lymph nodes). The mean ADC values of invasive ductal carcinoma were significantly lower in patients with high grade, large...

In vivo chlorine-35, sodium-23 and proton magnetic resonance imaging of the rat brain

NMR in Biomedicine — Mon, 15 Mar 2010 00:00:00 +0100

In this study we demonstrate the feasibility of combined chlorine-35, sodium-23 and proton magnetic resonance imaging (MRI) at 9.4 Tesla, and present the first in vivo chlorine-35 images obtained by means of MRI. With the experimental setup used in this study all measurements could be done in one session without changing the setup or moving the subject. The multinuclear measurement requires a total measurement time of 2 h and provides morphological (protons) and physiological (sodium-23, chlorine-35) information in one scanning session. Chlorine-35, sodium-23 and high resolution proton images were acquired from a phantom, a healthy rat and from a rat displaying a focal cerebral infarction. Compared to the healthy tissue a signal enhancement of a factor of 2.2 ± 0.2 in the chlorine-35 and ...

Effects of motion and b-matrix correction for high resolution DTI with short-axis PROPELLER-EPI

NMR in Biomedicine — Thu, 11 Mar 2010 00:00:00 +0100

In this study, we investigate the effects of alterations in the b-matrix as a result of patient motion on the example of SAP-EPI DTI and eliminate these effects by incorporating our novel single-step non-linear diffusion tensor estimation scheme into the SAP-EPI post-processing procedure. Our simulations and in-vivo studies showed that, in the presence of patient motion, correcting the b-matrix is necessary in order to get more accurate diffusion tensor and white matter pathway reconstructions. Copyright © 2010 John Wiley & Sons, Ltd. (Source: NMR in Biomedicine)

Phenylbutyrate induces apoptosis and lipid accumulations via a peroxisome proliferator-activated receptor gamma-dependent pathway

NMR in Biomedicine — Thu, 11 Mar 2010 00:00:00 +0100

The effects of the selective peroxisome proliferator activated receptor-gamma (PPAR-[gamma]) inhibitor GW9662 on phenylbutyrate (PB)-induced NMR-detectable lipid metabolites was investigated on DU145 prostate cancer cells. DU145 cells were perfused with 10 mM PB in the presence or absence of 1 µM of GW9662 and the results monitored by 31P and diffusion-weighted 1H NMR spectroscopy. GW9662 completely reversed PB-induced NMR-visible lipid and total choline accumulation in 1H spectra and glycerophosphocholine and [beta]-NTP in 31P spectra. In addition, pre-incubation with GW9662 significantly reduced PB-induced caspase-3 activation, reversed the G1 block as measured by flow cytometry, and otherwise had little effect on cell survival as measured by MTT assay. These results suggest that the NM...

Optimization of magnetosonoporation for stem cell labeling

NMR in Biomedicine — Tue, 09 Mar 2010 00:00:00 +0100

This study demonstrated that the optimized MSP cell labeling technique can achieve both high cell viability and intracellular uptake of MR contrast agents, and has the potential to be a useful cell labeling technique to facilitate future clinical translation of MRI-integrated cell therapy. Copyright © 2010 John Wiley & Sons, Ltd. (Source: NMR in Biomedicine)

In vivo diffusion tensor magnetic resonance imaging and fiber tracking of the mouse brain

NMR in Biomedicine — Mon, 08 Mar 2010 00:00:00 +0100

Until very recently, the study of neural architecture using fixed tissue has been a major scientific focus of neurologists and neuroanatomists. A non-invasive detailed insight into the brain's axonal connectivity in vivo has only become possible since the development of diffusion tensor magnetic resonance imaging (DT-MRI). This unique approach of analyzing axonal projections in the living brain was used in the present study to describe major white matter fiber tracts of the mouse brain and also to identify for the first time non-invasively the rich connectivity between the amygdala and different target regions. To overcome the difficulties associated with high spatially and temporally resolved DT-MRI measurements a 4-shot diffusion weighted spin echo (SE) echo planar imaging (EPI) protocol...

Standardized protocol for a depletion of intramyocellular lipids (IMCL)

NMR in Biomedicine — Mon, 08 Mar 2010 00:00:00 +0100

Intramyocellular lipids (IMCL) are flexible fuel stores that are depleted by physical exercise and replenished by fat intake. IMCL or their degradation products are thought to interfere with insulin signaling thereby contributing to insulin resistance. From a practical point of view it is desirable to deplete IMCL prior to replenishing them. So far, it is not clear for how long and at which intensity subjects have to exercise in order to deplete IMCL. We therefore aimed at developing a standardized exercise protocol that is applicable to subjects over a broad range of exercise capacity and insulin sensitivity and allows measuring reliably reduced IMCL levels.Twelve male subjects, including four diabetes type 2 patients, with wide ranges of exercise capacity (VO2peak per total body weight 2...

Silent increase of urinary ethylmalonic acid is an indicator of nonspecific brain dysfunction

NMR in Biomedicine — Fri, 26 Feb 2010 00:00:00 +0100

Our aim was to compare urinary ethylmalonic acid (EMA) levels in subjects who had no apparent clinical reason to have increased levels of this substance but were suffering from non-specific CNS impairment, and healthy controls. Urinary EMA concentrations detected by 1H-NMR spectroscopy were studied in 130 subjects with CNS impairment of unknown origin (with no definite diagnosis, no specific symptoms or signs, and normal common biochemical and metabolic screening results) and 130 age- and sex-matched healthy subjects. EMA levels exceeding two standard deviations (SD) above normal (i.e. 8.1 mmol/molCn) were found in a subgroup of CNS-impaired patients and healthy controls. EMA levels exceeding 2 SD above normal were fourfold prevalent in the urine of patients with non-specific CNS impairmen...

In vivo proton MR spectroscopy findings specific for adenylosuccinate lyase deficiency

NMR in Biomedicine — Sat, 20 Feb 2010 00:00:00 +0100

Adenylosuccinate lyase (ADSL) deficiency is an inherited metabolic disorder affecting predominantly the central nervous system. The disease is characterized by the accumulation of succinylaminoimidazolecarboxamide riboside and succinyladenosine (S-Ado) in tissue and body fluids. Three children presented with muscular hypotonia, psychomotor delay, behavioral abnormalities, and white matter changes on brain MRI. Two of them were affected by seizures. Screening for inborn errors of metabolism including in vitro high resolution proton MRS revealed an ADSL deficiency that was confirmed genetically in all cases. All patients were studied by in vivo proton MRS. In vitro high resolution proton MRS of patient cerebrospinal fluid showed singlet resonances at 8.27 and 8.29 ppm that correspond to accu...

Assessment of therapeutic response of locally advanced breast cancer (LABC) patients undergoing neoadjuvant chemotherapy (NACT) monitored using sequential magnetic resonance spectroscopic imaging (MRSI)