MRI analysis of the changes in apparent water diffusion coefficient, T(2) relaxation time, and cerebral blood flow and volume in the temporal evolution of cerebral infarction following permanent middle cerebral artery occlusion in rats.

Detailed knowledge of similarities and differences between animal models and human stroke is decisive for selecting clinically effective drugs based on efficacy data obtained preclinically. Differences in the temporal evolution of stroke pathologies between animal models and man have been reported. In view of the importance of this issue for the development of neuroprotective treatments, the temporal evolution of stroke pathologies in the rat permanent middle cerebral artery occlusion (pMCAO) model has been evaluated with magnetic resonance imaging modalities under experimental conditions matching as close as possible those used in humans. Changes in the ipsilateral and contralateral cortex and striatum of cerebral blood flow (CBF) and volume (CBV), apparent diffusion coefficient (ADC), and spin-spin relaxation time (T(2)), as well as total cortical and striatal infarct volumes, calculated from CBF, ADC, and T(2) maps, were determined starting 1 h up to 216 h post-pMCAO. The temporal evolution of the MRI parameters in this rat model was similar to that observed in humans. In particular, the ADC values were decreased for more than 3 days and returned back to baseline between 4 to 8 days, to increase by day 9 only. Thus the stroke pathology in this rat model develops at a similar pace as in stroke patients arguing against a fundamental difference in the mechanisms involved. The infarct volumes however develop differently in this rat model as they invariably increase over the first 48 h, while in humans the evolution of infarct volume is slower and more heterogeneous.

Economical microscope configuration for direct mycological examination with fluorescence in dermatology.

BACKGROUND: The use of fluorochromes such as Blankophor or Calcofluor allows to detect immediately and without ambiguity fungal elements in dermatological preparations. Whereas fluorescence microscopy is widely practised in clinical laboratories, it is not generally used in private practice because of the high price of a epifluorescence microscope. OBJECTIVE: To propose an economical microscope configuration to visualize fungal elements using fluorescence. METHODS: The preparations were examined with a standard microscope for routine observations, equipped with only two supplementary filters. RESULTS: Because the fungal elements produce a particularly bright fluorescence, a 25-watt halogen light is sufficient to visualize them in dermatological preparations: CONCLUSIONS: The proposed microscope configuration for direct mycological examination is particularly economical since equipment for epifluorescence and a vapour mercury lamp are not necessary.

High-resolution magnetic resonance angiography of the mouse brain: application to murine focal cerebral ischemia models.

Three-dimensional time-of-flight high-resolution magnetic resonance angiography was applied to visualize the cerebral vasculature of the mouse brain. In normal mice, angiograms of good quality, showing the essential details of the arterial cerebrovascular anatomy, could be obtained in only 2.5 min without the use of contrast agents. Signals from slowly flowing blood, e.g., in veins, could also be detected after administration of a blood pool contrast agent. The technique was applied to mouse models of permanent and transient brain ischemia, involving the occlusion of the middle cerebral artery. High-resolution magnetic resonance angiography proved to be a very useful tool for verifying the success of the occlusion in these models.

Time course of spirapril-induced structural and functional changes after myocardial infarction in rats followed with magnetic resonance imaging.

Structural alterations after myocardial infarction (MI) in rats are usually examined only after death of the experimental animal. Magnetic resonance imaging (MRI) allows repeated and noninvasive measurements of important structural [left ventricular (LV) mass, LV wall thickness, LV chamber radius] as well as function [LV end-systolic and LV end-diastolic volume, stroke volume (SV), ejection fraction (EF)] parameters for a prolonged period. We describe our experience in a series of experiments in rats. Three weeks after MI, infarct size (IS) was determined by MRI and the rats were divided into two groups with equal IS. Three weeks later, treatment with the angiotensin-converting enzyme (ACE) inhibitor spirapril (10 mg/kg in food) or placebo was started. In both groups, the first MRI scan taken before the treatment showed moderately dilated left ventricles and signs of impaired LV function, i.e., an increase in LV end-systolic and end-diastolic volume and decreased EF. After 3-week treatment, no significant differences with respect to heart structure and function were detected as compared with those of untreated animals. Prolonged treatment for 10 weeks with spirapril resulted in significant reduction of LV dilatation, LV mass, and LV end-systolic and end-diastolic volume, which was accompanied by improved EF. Hemodynamic examinations after treatment for 6 months showed, in contrast to control animals, no increase in right ventricular systolic pressure in animals receiving spirapril. Furthermore, histologic examination of perfusion-fixed hearts at the end of the study demonstrated more pronounced LV dilatation in control animals, thus confirming the in vivo MRI data. Delayed treatment with spirapril proved to have beneficial effects on structure and function of infarcted hearts within 10 weeks. Spirapril limited LV dilatation, reduced LV weight and LV end-systolic and end-diastolic volumes, and improved EF.