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Biomedical subjects

E Vicaut

Publications and source records attributed to E Vicaut.

At least 145 records · Page 8Linked to original sources
PubMed1987

Effects of changes in systemic hematocrit on the microcirculation in rat cremaster muscle.

This work aimed to establish how changes in systemic hematocrit ranging from 0.33 to 0.55, affect capillary red cell velocity (measured by the dual-slit correlator method), capillary volume flow, capillary density and arteriolar diameter. These microcirculatory parameters were determined on rat cremaster muscles surgically prepared for in vivo visualization and bathed with a modified Krebs-Henseleit solution. A significant rise in mean red cell velocity and mean volume flow rate in capillaries was found after hemodilution, and a significant drop after hemoconcentration. A large reduction in the number of capillaries with low flow rate was shown after hemodilution; an opposite effect was found after hemoconcentration. The number of capillaries containing erythrocytes did not change significantly in either state. However after hemoconcentration, the number of capillaries containing stationary erythrocytes was significantly larger. Arteriolar diameter did not alter significantly after either hemodilution or hemoconcentration. We conclude that, in the cremaster muscle, hematocrit is an important rheological factor that determines capillary flows without involving arteriolar regulation.

Animals↗
PubMed1987

[Demonstration of a correlation between the degree of pigmentation and the power of inactivation of isoniazid in man].

In a group of 153 white subjects treated for tubercle, individual determinations were made of: a) The power of inactivation of isoniazid. b) The degree of pigmentation (iris, skin, hair) assessed by a weighted pigmented index of the iris. A statistical study of the results shows the clear existence of a narrow positive correlation between these two characters, such that the more pigmented a subject is, the greater is the chance of rapid inactivation of isoniazid. An attempt at a biochemical explanation is proposed. The results in the world literature (Japanese, Swedish, American) are in keeping with these observations. Thus, weakly pigmented tuberculous patients are potentially a new group at risk from anti-TB drugs.

Eye Color↗
PubMed1986

Arterial-venous plasma concentration differences of meprobamate in acute human poisonings.

Arterial-venous plasma concentration differences of meprobamate were studied on admission of acute overdose in man. The patients were divided in two groups. In the control group (n = 25) two successive blood samples were collected from the same vessel. In the study group (n = 35) femoral arterial and venous blood samples were collected simultaneously. In the control group the differences were not significant. In the study group the differences were statistically significant (P less than 0.01). The present study suggests that the origin of blood samples should be stated for toxicological studies and that the toxicokinetics may be more complex than those recognized previously.

Adolescent↗
PubMed1985

Coronary response to large decreases of hemoglobin-O2 affinity in isolated rat heart.

In this study, the consequences of large increases of P50 (O2 partial pressure at 50% oxyhemoglobin saturation) on coronary blood flow (CBF) were investigated in isolated Wistar rat heart. Rightward shifts of the O2 dissociation curve (ODC), obtained by lysing and resealing erythrocytes to encapsulate inositol hexaphosphate (IHP), led to a very large increase in P50 without side effects. Each heart was perfused alternatively with control stored human blood [P50 = 18.8 +/- 0.3 (SE) mmHg] and IHP-treated human blood (P50 = 47.1 +/- 1.7 mmHg), according to the technique of Langendorff (mean perfusion pressure 80 mmHg; hematocrit 25%). Arterial PO2 of 180 mmHg was maintained to keep arterial O2 content identical for both types of blood. When hemoglobin affinity was lowered, CBF decreased from 5.32 +/- 0.20 to 3.40 +/- 0.14 ml X min-1 X g-1, coronary sinus PO2 (PcsO2) rose from 39.9 +/- 0.9 to 69.9 +/- 4.2 mmHg, and myocardial O2 consumption (MVO2) rose slightly from 0.125 +/- 0.005 to 0.149 +/- 0.010 ml O2 X min-1 X g-1 (P less than 0.05). A significant negative correlation was found between CBF and P50 (r = -0.90; n = 32) and a significant positive correlation between PcsO2 and P50 (r = +0.84; n = 28). The coronary blood flow response to high P50 values was not abolished when maximal dilation was induced by adenosine, so this response seems independent of metabolic needs. These experiments have demonstrated that if O2 uptake by erythrocytes remains constant, in the presence of a high P50, sufficient O2 supply may be achieved with substantially less blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1985

Arterio-venous plasma concentration differences in amitriptyline overdose.

The aim of this study was to determine whether femoral arterio-venous plasma concentration differences (AVD) of amitriptyline exist during acute intoxication in man. All patients studied were comatose and were divided into a control group who had two successive blood samples drawn from the same vessel and a study group who had samples drawn from the femoral artery and vein simultaneously. Serial plasma concentrations of amitriptyline were measured by gas liquid chromatography. In each group the differences were assessed by means of the Wilcoxon matched pairs test. In the control group (n = 13) there were no differences (T = 31, n = 12). In the study group (n = 24) the AVD were significantly different (T = 52, n = 23). For amitriptyline, the arterial or venous origin of blood samples for toxicological studies must be stated.

Adolescent↗
PubMed1985

Power of isoniazid acetylation and pigmentation; first experimental tests in the rabbit: comparison with clinical data.

A positive correlation has been observed clinically at the Centre Edouard Rist, Paris, between the degree of pigmentation and the power of isoniazid acetylation in so-called "caucasians". The investigation was based on a relatively small sample of 153 observations, but sufficient to allow a significant statistical analysis. Comparing the results with data published in the literature, it may be assumed that this relationship between the power of acetylation and pigmentation would be applicable to all human beings. The rabbit, having as in man a bi-modal distribution of the power of acetylation, was used for further research of this correlation in that animal. The results of this research in rabbits may be compared with those in man, but further studies are required in view of the interest of this comparison and of the possible consequences of the relationship of pigmentation and the degree of acetylation of isoniazid in human therapeutics.

Acetylation↗
PubMed1985

Effects of changes in hematocrit on red cell flows at capillary bifurcations.

A theoretical study was developed to evaluate effects of changes in hematocrit on red cell flow partitioning at narrow capillary bifurcations of unequal diameters. Non-Newtonian blood viscosity and non-linear relationships between blood and red cell flows at capillary bifurcations are taken into account. Results suggest that heterogeneity of diameters is a determinant of red cell and blood flows heterogeneity not only due to its influence on geometrical resistance but also as a result of its influence on capillary viscosity. Lowering hematocrit reduces differences in viscosities between the two branches. Then more homogeneous red cell flows are induced. Considering three possible relationships for entering blood flow vs. entering discharge hematocrit, the present study stresses that changes in red cell flow for individual capillaries are not parallel to changes in entering red cell flow. Therefore discussion on effects of hemodilution have to take into account not only red cell flow or oxygen arriving to an organ, but also changes in distribution of capillary flows induced by rheological changes due to lower hematocrit.

Blood Viscosity↗
PubMed1983

Experimental assessment of the protective activity of diazepam on the acute toxicity of chloroquine.

The dose of diazepam that reduces the mortality rate of acute intoxications with chloroquine was determined: The oral LD 50 of chloroquine (330 mg/kg) was administered and immediately thereafter diazepam was injected intraperitoneally to male and female rats at dose levels of 2.5, 7.5, 20, 55, and 148 mg/kg. An untreated group served as control. A significant decrease of the mortality rate was observed at the dose levels 7.5, 20, and 55 mg/kg with optimal effect at 20 mg/kg. This mortality rate was analysed by analysis of variance. The occurrence of two types of symptoms: convulsions and respiratory disturbances was analysed by the chi square method.

Analysis of Variance↗
PubMed1983

Effects of different hematocrits on the isolated working rabbit heart reperfused after ischemia.

Increased blood viscosity has frequently been related to ischemic heart diseases. Since blood viscosity depends mainly on hematocrit (HTC), the effects of hemodilution have been studied on the isolated working rabbit heart perfused initially with 50% HCT, submitted to global ischemia for 10 min and reperfused with two different amounts of HCT: 50 and 30%. When the reperfusion was carried out with 50% HCT (N = 10) aortic flow failed to be restored in 4 hearts. When the reperfusion was performed with 30% HCT, all hearts recovered rapidly, reaching the preischemic cardiac output 20 min later. The ratio between cardiac output (C.O.) 20 min after reperfusion and C.O. before ischemia was 0.30 for the high hematocrit group (H.H.) as compared to 0.89 for the low hematocrit group (L.H.). The ratio of the coronary flow (C.F.) 20 min after reperfusion and that of C.F. before ischemia was 0.83 for the H.H. group as compared to 1.30 for the L.H. group. After reperfusion the myocardial oxygen consumption was not significantly different between both groups. The better recovery of heart performance after ischemia when the hearts were reperfused with a 30% HCT suggests that hemodilution results in a better oxygen distribution.

Animals↗
PubMed1981

[Ventilation perfusion distribution: a program for personal computer (author's transl)].

Ventilation perfusion inequality, is analysed with the help of a program written in Basic language, easily implemented on a personal computer. For a gas exchange unit, the main equation describes a mass balance for oxygen, assuming absence of diffusion barrier. The use of a large number of these units allows for calculation of the resulting arterial PO2 in case of abnormal ventilation blood flow distribution. Several simulations are made to study the effect of local variations of VA/Q ratio, and oxygen inhalation upon arterial PO2.

Computers↗
PubMedDate not supplied

In vivo determination of the caloric value of gum arabic in the male rat--biological data.

Sprague-Dawley male rats were given normal diets (UAR A 03) containing various amounts of gum arabic, sucrose and lignin for eight consecutive weeks. The caloric values of the diets were derived by utilizing the indirect method comparing the slopes from food consumption and weight gain curves. While the data obtained from sucrose diets showed that these diets caused a clear incremental effect on energy production with respect to both test animals and controls, and data from lignin diets were found to produce a negative effect on energy yields, gum arabic diets produced results indicating that at certain levels of intake, gum arabic may contribute energy values slightly superior to those of lignin (0 cal-g), possibly between zero and 1 cal/g. However, it was not found possible to attribute a clear-cut quantitative caloric value to this additive from data obtained in this study.

Animals↗