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Jean-Claude Vial

Publications and source records attributed to Jean-Claude Vial.

5 recordsLinked to original sources
PubMed2006

A direct method for measuring mouse capillary cortical blood volume using multiphoton laser scanning microscopy.

Knowledge of the blood volume per unit volume of brain tissue is important for understanding brain function in health and disease. We describe a direct method using two-photon laser scanning microscopy to obtain in vivo the local capillary blood volume in the cortex of anesthetized mouse. We infused fluorescent dyes in the circulating blood and imaged the blood vessels, including the capillaries, to a depth of 600 microm below the dura at the brain surface. Capillary cortical blood volume (CCBV) was calculated without any form recognition and segmentation, by normalizing the total fluorescence measured at each depth and integrating the collected intensities all over the stack. Theoretical justifications are presented and numerical simulations were performed to validate this method which was weakly sensitive to background noise. Then, CCBV had been estimated on seven healthy mice between 2%+/-0.3% and 2.4%+/-0.4%. We showed that this measure of CCBV is reproductible and that this method is highly sensitive to the explored zones in the cortex (vessel density and size). This method, which dispenses with form recognition, is rapid and would allow to study in vivo temporal and highly resolute spatial variations of CCBV under different conditions or stimulations.

Algorithms↗
PubMed2006

In vivo two-photon microscopy study of short-term effects of microbeam irradiation on normal mouse brain microvasculature.

PURPOSE: The purpose of this study was to assess the early effects of microbeam irradiation on the vascular permeability and volume in the parietal cortex of normal nude mice using two-photon microscopy and immunohistochemistry. METHODS AND MATERIALS: The upper part of the left hemisphere of 55 mice was irradiated anteroposteriorly using 18 vertically oriented beams (width 25 microm, interdistance 211 microm; peak entrance doses: 312 or 1000 Gy). At different times after microbeam exposure, the microvasculature in the cortex was analyzed using intravital two-photon microscopy after intravascular injection of fluorescein isothiocyanate (FITC)-dextrans and sulforhodamine B (SRB). Changes of the vascular volume were observed at the FITC wavelength over a maximum depth of 650 mum from the dura. The vascular permeability was detected as extravasations of SRB. RESULTS: For all times (12 h to 1 month) after microbeam irradiation and for both doses, the FITC-dextran remained in the vessels. No significant change in vascular volume was observed between 12 h and 3 months after irradiation. Diffusion of SRB was observed in microbeam irradiated regions from 12 h until 12 days only after a 1000 Gy exposure. CONCLUSION: No radiation damage to the microvasculature was detected in normal brain tissue after a 312 Gy microbeam irradiation. This dose would be more appropriate than 1000 Gy for the treatment of brain tumors using crossfired microbeams.

Animals↗
PubMed2002

NO synthesis, unlike respiration, influences intracellular oxygen tension.

We have developed a new phosphorescent probe, PdTCPPNa(4), whose luminescence properties are affected by local variations of intracellular oxygen tension (PO(2)). Spectrofluorometric measurements on living human umbilical venous endothelial cells loaded with this molecule show that a decrease in extracellular oxygen tension induces a decrease of PO(2), illustrating the phenomenon of oxygen diffusion and validating the use of this probe in living cells. Moreover, KCN- or 2,4-dinitrophenol-induced modifications of respiration do not lead to detectable PO(2) variations, probably because O(2) diffusion is sufficient to allow oxygen supply. On the contrary, activation by acetylcholine or endothelial nitric oxide synthase (eNOS), which produces NO while consuming oxygen, induces a significant decrease in PO(2), whose amplitude is dependent on the acetylcholine dose, i.e., the eNOS activity level. Hence, activated cytosolic enzymes could consume high levels of oxygen which cannot be supplied by diffusion, leading to PO(2) decrease. Other cell physiology mechanisms leading to PO(2) variations can now be studied in living cells with this probe.

2,4-Dinitrophenol↗