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E Vicaut

Publications and source records attributed to E Vicaut.

153 records · Page 9Linked to original sources
PubMedDate not supplied

Reactive oxygen species and acute modulation of albumin microvascular leakage in the microcirculation of diabetic rats in vivo.

Endothelial cells have been reported to generate reactive oxygen species such as the superoxide anion, hydrogen peroxide, and the hydroxyl radical. The aim of this work was to evaluate the role of reactive oxygen species in diabetes-induced changes in vascular permeability. Intravital videomicroscopy was used to study albumin microvascular leakage in the cremaster muscle. The extravasation of a fluorescent macromolecular tracer (FITC-albumin) was measured for 1 h and, after computer-aided image analysis, was expressed as variations of normalized gray levels (arbitrary units). The extravasation of the macromolecular tracer was greater in diabetic rats (5.28 +/- 1.29 vs. 1.96 +/- 0.41 AU at 1 h in diabetic and control rats, respectively). Administration of superoxide dismutase (SOD), which dismutates.O(-)(2) to H(2)O(2), and of catalase which reacts with H(2)O(2) to form H(2)O and molecular oxygen failed to inhibit the increased extravasation of the macromolecular tracer when administered separately. However, a significant inhibition of diabetic increase in albumin extravasation was found when these 2 drugs were administered simultaneously, and in this case, the extravasation of the macromolecular tracer at 1 h was similar in diabetic rats (2.11 +/- 0.61 AU) and normoglycemic rats (1.43 +/- 0. 48 AU). No difference was found in adherent leukocytes or in the leukocyte rolling flux between diabetic and normoglycemic rats. We conclude that reactive oxygen species are responsible for an increase in microvascular permeability likely via leukocyte-independent mechanisms.

Albumins↗
PubMedDate not supplied

Red blood cell aggregation and microcirculation in rat cremaster muscle.

Using intravital microscopy of the rat cremaster muscle, we studied the effects of changing red blood cell (RBC) aggregation on RBC arteriolar velocity and perfused capillary density (PCD). To modify RBC aggregation, 2 and/or 10% dextran (molecular weights 40,000, 70,000 or 480,000) or fresh rat plasma was infused into adult male rats via a normovolemic hemodilution procedure. The high-molecular-weight dextrans (70,000 and 480,000) both induced RBC hyperaggregation associated with similar dose-dependent decreases in RBC arteriolar velocity (30 and 40% for dextran concentrations of 2 and 10%, respectively) and in PCD (35 and 37%, respectively, for the two concentrations). Conversely, with 40,000 molecular weight dextran or plasma, we observed a 30% increase in RBC arteriolar velocity, but no change in PCD or hyperaggregation. Intravenous injection of the antiaggregating drug troxerutin (10(-3) M), either before or after 2% dextran 70,000, significantly inhibited the effects of this dextran on RBC arteriolar velocity and on PCD. We conclude that RBC hyperaggregation can lead to changes in both arteriolar velocity and PCD and may, therefore, impair tissue oxygenation.

Animals↗
PubMedDate not supplied

[principal characteristics of tumor microcirculation revealed by experimental techniques in vivo].

In this brief review, we show that intravital microscopy has permitted characterization of the specific aspects of tumour microcirculation. Microvascular networks in tumour are largely different from those in non-tumoural tissue or in non-tumoural neoangiogenesis. Both from the anatomical and the hemodynamical aspects, the tumour microvascular network appears highly chaotic. In vivo measurements have shown the large heterogeneity of oxygen and metabolic status associated with tumour growth. Effects of antiangiogenic drugs can also be tested using intravital microscopy. These techniques have also allowed demonstration of the specific vasomotor response of vessels irrigating tumours, thus allowing specific modulation of tumour blood flow.

Animals↗
PubMedDate not supplied

[Tyrer's Brief Scale for Anxiety used with outpatients. First validation in the French language].

The brief scale for anxiety of Tyrer is a subdivision of the comprehensive psychopathological scale. We studied a serie of 105 anxious outpatients treated for chronic or reactive anxiety, without depressive or psychotic symptoms. We confirm its sensitivity to change, prove its concurrent validity in regard to the Hamilton anxiety rating scale and demonstrate that the brief scale for anxiety is a reliable instrument to assess anxiety with outpatients. Nevertheless the assessment of its internal validity raises the question of the item's selection at the time of the elaboration of the rating scales according to the scale's purpose. Indeed, must we attempt to register all the symptoms of the anxious syndrome, with the risk of including less specific items? Or must we choose the most characteristic and specific items with the risk of obtaining a more reductionist inventory, but more reliable in a "transnosographic" perspective?

Adult↗
PubMedDate not supplied

Cardiac effects of phytic acid induced high P50 with free and limited coronary blood flow.

A blood preparation with a large increase in P50, obtained by a new technique to encapsulate inositol hexaphosphate (IHP) in erythrocytes was evaluated on an isolated heart model. Each heart was alternatively perfused with control stored human blood (P50 = 2.12.+/- 0.9 mmHg) and IHP-treated human blood (P50 = 42.5 +/- 9.33 mmHg). Changes of perfusates were performed when coronary blood flow (CBF) was free and adapted to a constant perfusion pressure (FREE CBF). Changes of perfusates were also performed at a constant but restricted CBF corresponding to 55% of basal value (RESTRICTED CBF). Both bloods were oxygenated and equilibrated to achieve the same acid-base balance, arterial PO2 and O2 content. When CBF was not restricted, switching from control blood to IHP-treated blood, induced a decrease in CBF (-23%), an increase in coronary sinus PO2 (57%) and a decrease in coronary sinus O2 content associated with an increase in myocardial O2 consumption (14%). These metabolic changes were associated with a decrease in left ventricular developed pressure (LVDevP) (-15%) and its maximal positive derivative (-12%). When CBF was restricted, switching from control blood to IHP-treated blood, induced an increase in perfusion pressure (59%). This vasoconstriction was associated with the same changes in the blood gas measurements as those observed when CBF was not restricted, while LVDevP increased significantly (7%). It is concluded that the beneficial effects on myocardial metabolism from the increase in P50 with IHP, are lessened by the cardiodepressive effect of the blood preparation which is predominant when CBF is not restricted.

Animals↗
PubMedDate not supplied

[Hemodilution in persistent postphlebitic ulcers].

By definition, rebel post-phlebitic ulcers are very difficult to cure. However, it has recently been apparent that the classic treatments associated with permanent normovolemic haemodilution are more effective. Two research procedures have been implemented simultaneously to try and explain this beneficial effect of haemodilution, one based on an experimental study of isolated rabbit hearts, and the other on a theoretical model of the blood-flow at capillary level. These studies lead us to believe that a better distribution of tissular oxygenation might be one of the mechanisms responsible for the beneficial effect of permanent normovolemic haemodilution in treatment of rebel post-phlebitic ulcers.

Animals↗
PubMedDate not supplied

Red blood cell aggregation and blood viscosity in an isolated heart preparation.

We studied the effects of moderate changes in red blood cell RBC aggregation on blood flow in the vasodilated vascular bed of an isolated rat heart. We compared a non-aggregating RBC suspension (in Krebs-albumin medium) with RBC suspensions in 1% and 2% Dextran 70 (MW 70000), exhibiting two different degrees of moderate aggregation. Degrees of aggregation were precisely estimated by in vitro laser aggregometry. Each heart was perfused by the non-aggregating RBC suspension and by one aggregating RBC suspensions. Blood flow was measured in a range of perfusion pressure from 40 to 80 mm Hg. For the three RBC suspensions, linear pressure/flow relationships were found. From the comparison between the pressure/flow relationships obtained with Krebs albumin medium and either 1% or 2% Dextran, it was possible to compare in vivo the contribution of RBC to the viscosity (i.e., the relative apparent viscosity) in the 2 aggregating RBC suspensions with that of the non-aggregating RBC suspension. The contribution of RBC to the viscosity was found to be 20% to 25% lower in the 1% RBC suspension than in the non-aggregating RBC suspension. With 2% Dextran which induced a higher degree of aggregation no differences were found between the relative apparent viscosities of the aggregating and the non-aggregating suspension. From the comparison between RBC in 1% Dextran and Krebs-albumin, we concluded that in vivo a moderate RBC aggregation reduces viscous resistance due to the presence of blood in a vascular network. Since no more effect of RBC aggregation per se was found when the degree of aggregation was higher (with RBC in 2% Dextran), this suggests that, in this case, aggregation induces opposite effects along the myocardial vascular network which cancel each other out, thus inducing a nil net balance.

Animals↗