In vivo MRI and ex vivo quantification of iron and Kupffer cells demonstrate residual phagocytic activity in mouse liver after a gadolinium chloride injection.

Kupffer cells (KCs), the resident macrophages of the liver, display a phagocytic activity that is not well quantified in animal models. Its experimental invalidation in rodents has been carried out by various means, among which the gadolinium chloride (GdCl₃) injection has been widely used, and has been generally monitored by ex vivo techniques. The aim of our study was to determine the KC phagocytic activity induced in mouse liver following a single GdCl₃ injection, through Magnetic Resonance Imaging (MRI) measurement of liver uptake of Ferumoxide in vivo, and through ex vivo quantification of Perls positive and F4/80 labeled macrophages.

The influence of skeletal muscle anisotropy on electroporation: in vivo study and numerical modeling.

The aim of this study was to theoretically and experimentally investigate electroporation of mouse tibialis cranialis and to determine the reversible electroporation threshold values needed for parallel and perpendicular orientation of the applied electric field with respect to the muscle fibers. Our study was based on local electric field calculated with three-dimensional realistic numerical models, that we built, and in vivo visualization of electroporated muscle tissue. We established that electroporation of muscle cells in tissue depends on the orientation of the applied electric field; the local electric field threshold values were determined (pulse parameters: 8 x 100 micros, 1 Hz) to be 80 V/cm and 200 V/cm for parallel and perpendicular orientation, respectively.

Selective iron chelation in Friedreich ataxia: biologic and clinical implications.

Genetic disorders of iron metabolism and chronic inflammation often evoke local iron accumulation. In Friedreich ataxia, decreased iron-sulphur cluster and heme formation leads to mitochondrial iron accumulation and ensuing oxidative damage that primarily affects sensory neurons, the myocardium, and endocrine glands. We assessed the possibility of reducing brain iron accumulation in Friedreich ataxia patients with a membrane-permeant chelator capable of shuttling chelated iron from cells to transferrin, using regimens suitable for patients with no systemic iron overload.

An automated image-processing strategy to analyze dynamic arterial spin labeling perfusion studies. Application to human skeletal muscle under stress.

Arterial spin labeling (ASL) perfusion measurements allow the follow-up of muscle perfusion with high temporal resolution during a stress test. Automated image processing is proposed to estimate perfusion maps from ASL images. It is based on two successive analyses: at first, automated rejection of the image pairs between which a large displacement is detected is performed, followed by factor analysis of the dynamic data and cluster analysis to classify pixels with large signal variation characteristic of vessels.

New insight into abnormal muscle vasodilatory responses in aged hypertensive rats by in vivo nuclear magnetic resonance imaging of perfusion.

Objective: Increased peripheral arterial resistances and decreased maximum vasodilation are characteristic features of chronic hypertension. However, little data are available in the literature regarding the possible alterations in the temporal patterns of vasodilatory responses elicited by various stimuli.

Design: This question was addressed by measuring skeletal muscle perfusion using nuclear magnetic resonance imaging combined with arterial spin labeling.

Evaluation of muscle glycogen content by 13C NMR spectroscopy in adult-onset acid maltase deficiency.

Muscle glycogen storage was measured by in vivo, natural abundance 13C nuclear magnetic resonance spectroscopy in distal and proximal lower limb segments of patients suffering from adult-onset acid maltase deficiency. Interleaved T1-weighted acquisitions of glycogen and creatine served to quantify glycogen excess. For acid maltase deficient patients (n=11), glycogen:creatine was higher than controls (n=12), (1.

Electrotransfer at MR imaging: tool for optimization of gene transfer protocols--feasibility study in mice.

Purpose: To test, by using an electrotransfer protocol for the transfection of skeletal muscle with naked plasmid complementary DNA, whether in vivo magnetic resonance (MR) imaging can help delineate either the spatial extent of the electric field when contrast agent is injected intraperitoneally or the transfection area when contrast agent is injected locally.

Materials And Methods: Three groups of five mice each were examined at 4 T. Gadopentetate dimeglumine was injected intraperitoneally before electroporation in group 1 and after electroporation in group 2.

Ultrafast multiplanar determination of left ventricular hypertrophy in spontaneously hypertensive rats with single-shot spin-echo nuclear magnetic resonance imaging.

Objective: To determine whether left ventricular hypertrophy can be correctly evaluated in hypertensive rats with a new nuclear magnetic resonance (NMR) imaging modality that is relatively simple to operate and provides results of constant quality while offering a high signal-to-noise ratio. DESIGN Left ventricular mass as calculated from the NMR imaging analysis was compared with the actual left ventricular mass measured by gravimetry.

Methods: Single-shot ultrafast spin-echo (SSFSE) imaging of hearts of Wistar-Kyoto rats and spontaneously hypertensive rats was performed at 4 T.