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Biomedical subjects

J Vaysse

Publications and source records attributed to J Vaysse.

At least 19 recordsLinked to original sources
PubMed2000

Operation Everest III: role of plasma volume expansion on VO(2)(max) during prolonged high-altitude exposure.

We hypothesize that plasma volume decrease (DeltaPV) induced by high-altitude (HA) exposure and intense exercise is involved in the limitation of maximal O(2) uptake (VO(2)(max)) at HA. Eight male subjects were decompressed for 31 days in a hypobaric chamber to the barometric equivalent of Mt. Everest (8,848 m). Maximal exercise was performed with and without plasma volume expansion (PVX, 219-292 ml) during exercise, at sea level (SL), at HA (370 mmHg, equivalent to 6, 000 m after 10-12 days) and after return to SL (RSL, 1-3 days). Plasma volume (PV) was determined at rest at SL, HA, and RSL by Evans blue dilution. PV was decreased by 26% (P < 0.01) at HA and was 10% higher at RSL than at SL. Exercise-induced DeltaPV was reduced both by PVX and HA (P < 0.05). Compared with SL, VO(2)(max) was decreased by 58 and 11% at HA and RSL, respectively. VO(2)(max) was enhanced by PVX at HA (+9%, P < 0.05) but not at SL or RSL. The more PV was decreased at HA, the more VO(2)(max) was improved by PVX (P < 0.05). At exhaustion, plasma renin and aldosterone were not modified at HA compared with SL but were higher at RSL, whereas plasma atrial natriuretic factor was lower at HA. The present results suggest that PV contributes to the limitation of VO(2)(max) during acclimatization to HA. RSL-induced PVX, which may be due to increased activity of the renin-aldosterone system, could also influence the recovery of VO(2)(max).

Adult↗
PubMed2000

[Prevalence and prognostic value of serum anti-p53 antibodies in hepatocellular carcinoma. A study of 159 patients].

OBJECTIVES: Genetic alterations in the p53 protein may induce serum anti-p53 antibodies. The aim of this study was to assess the prevalence of serum anti-p53 antibodies in a large series of Western patients with hepatocellular carcinoma and the prognostic value of these antibodies on survival. METHODS: Serum anti-p53 antibodies were assayed in 159 patients with hepatocellular carcinoma, at diagnosis, using an immunoenzymatic method. The initial patient characteristics were compared according to anti-p53 status. The prognostic value of these antibodies on survival was determined by univariate and multivariate analysis. RESULTS: One hundred fifty nine patients with hepatocellular carcinoma were included in the study (129 men, mean age: 68 years). The main associated causes of chronic liver disease were alcohol (n=86), virus C (n=34), and virus B (n=18); 151 patients had cirrhosis. Median follow-up was 306 days. Among the 159 patients, 19 (12%) had serum anti-p53 antibodies. Detection of serum anti-p53 antibodies was significantly correlated with the presence of a multinodular or infiltrative tumor (P<0.03). Survival was not influenced by the presence of anti-p53 antibodies. Serum albumin, ALAT, and alfa-fetoprotein levels were independent prognostic variables. CONCLUSION: In our study, anti-p53 antibodies were rarely found in the serum of patients with hepatocellular carcinoma. Although they were correlated with multinodular or infiltrative tumors, they had no prognostic influence on survival. Thus, assaying serum anti-p53 antibodies does not seem to have any clinical value in those patients.

Aged↗
PubMed1999

Soluble L-selectin level is a marker for coronary artery disease in type 2 diabetic patients.

OBJECTIVE: To investigate whether the fall in soluble L-selectin (sL-selectin) level constitutes a marker for myocardial ischemia. RESEARCH DESIGN AND METHODS: The levels of soluble forms of adhesion molecules, i.e., intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (sE-selectin), P-selectin (sP-selectin), and L-selectin (sL-selectin), were compared in type 2 diabetic patients without inflammatory syndrome but with symptomatic coronary artery disease (CAD) (group 1, n = 11), with silent ischemic disorders and proven coronary stenoses (group 2, n = 11), with silent myocardial ischemia (SMI) and normal coronary angiography (group 3, n = 10), and without proven SMI (group 4, n = 13). These levels were compared with those of 22 control subjects. RESULTS: The sL-selectin level was significantly lower in groups 1, 2, or 3 with symptomatic CAD or with SMI as compared with the control group (P = 0.0004). Group 4 without myocardial ischemia did not significantly differ from the control subjects (P = 0.6). In type 2 diabetic patients, after controlling for HbA1c, a partial correlation between sL-selectin and the CAD status was significant (P = 0.001). sICAM-1 and sP- or sE-selectin did not differ significantly between type 2 diabetic patients and control subjects or among the different groups of patients. The sVCAM-1 level in type 2 diabetic patients was significantly higher than in the control subjects (P = 0.001), but there were no significant intergroup differences (P = 0.4). CONCLUSIONS: In type 2 diabetic patients, sVCAM-1 is increased with regard to glycemic control, whatever the CAD status. In type 2 diabetic patients with symptomatic CAD or SMI associated with coronary stenoses, sL-selectin is significantly decreased. A marked fall in sL-selectin might constitute a marker for silent CAD in type 2 diabetic patients.

Aged↗
PubMed1997

Recovery processes after repeated supramaximal exercise at the altitude of 4,350 m.

We tested the hypothesis that prolonged exposure to high altitude would impair the restoration of muscle power during repeated sprints. Seven subjects performed two 20-s Wingate tests (WT1 and WT2) separated by 5 min of recovery, at sea level (N) and after 5-6 days at 4,350 m (H). Mean power output (MPO) and O2 deficit were measured during WT. O2 uptake (VO2) and ventilation (VE) were measured continuously. Blood velocity in the femoral artery (FBV) was recorded by Doppler ultrasound during recovery. Arterialized blood pH and concentrations of bicarbonate ([HCO3-]), venous plasma lactate ([La-]), norepinephrine ([NE]), and epinephrine ([Epi]) were measured before and after WT1 and WT2. MPO decreased between WT1 and WT2 by 6.9% in N (P < 0.05) and by 10.7% in H (P < 0.01). H did not further decrease MPO. O2 deficit decreased between WT1 and WT2 in H only (P < 0.01). Peak VO2 after WT was reduced by 30-40% in H (P < 0.01), but excess postexercise O2 consumption was not significantly lowered in H. During recovery in H compared with N, VE, exercise-induced acidosis, and [NE] were higher, [Epi] tented to be higher, [La-] was not altered, and [HCO3-] and FBV were lower. The similar [La-] accumulation was associated with a higher exercise-induced acidosis and a larger increase in [NE] in H. We concluded from this study that prolonged exposure to high altitude did not significantly impair the restoration of muscle power during repeated sprints, despite a limitation of aerobic processes during early recovery.

Adult↗
PubMed1992

Biochemical characterization of size-separated human red blood cells.

Human red blood cells (RBC) are heterogeneous with respect to their size; the physiological significance of this heterogeneity has not yet been fully elucidated. To further investigate this problem, some characteristics of human RBC fractionated according to their mean corpuscular volume (MCV) by counterflow centrifugation were determined. Larger RBC are more prone to hypotonic lysis. The membrane protein content per cell increases with the MCV, but no obvious difference in the distribution of the major proteins can be demonstrated. The lipid content per cell also rises with the RBC size, while the percentages of the main lipid components do not significantly vary. However, the variations of sialic acid content per RBC according to MCV are more important than those of protein or lipid; thus, the sialic acid-to-protein ratio gradually increases with the MCV. This indicates that, in spite of the lack of major changes in the membrane composition, some qualitative differences exist between large and small cells.

Cell Separation↗
PubMed1990

Variations in serum alpha-L-fucosidase activity during childhood and pregnancy.

Variations in serum alpha-L-fucosidase activity (AFU) have been studied during childhood and pregnancy. 994 children, ages 1 day to 15 yr, were examined; no sex-linked difference was found, but significant variations according to age were demonstrated. AFU activity rose during the first 10-15 days after birth, remained high during the second month then decreased till the end of the first year, thereafter no significant changes were observed. In pregnancy, AFU activity rose and dropped quickly after delivery; neither hypertension nor fetal distress led to AFU activity changes during pregnancy. Thus, in addition to the great variability of AFU linked to the genetic polymorphism, the physiological factors such as age or pregnancy have to be taken into account to establish the significance of AFU variations in pathological situations.

Adolescent↗
PubMed1990

Saliva flow and composition in humans exposed to acute altitude hypoxia.

The effects of acute hypoxia (2 days at 4350 m) on whole saliva flow and composition were studied on 12 sea-level natives, at rest and following a maximal exercise. Exercise, performed in normoxia and hypoxia, did not induce variations in saliva flow rate, saliva potassium or alpha-amylase concentrations. In contrast, acute hypoxia did lead to an increase in mean saliva flow rate both at rest (0.63 ml.min-1 to 0.93 ml.min-1, P less than 0.01) and after exercise (0.56 ml.min-1 to 1.06 ml.min-1, P less than 0.05) and a decrease in mean saliva potassium concentration at rest (20.8 mmol.l-1 to 14.7 mmol.l-1, P less than 0.01) as well as after exercise (21.7 mmol.l-1 to 16.5 mmol.l-1, P less than 0.05). This effect might be the consequence of a hypoxia-induced stimulation of the parasympathetic nervous system.

Adult↗
PubMed1989

Inhibition by monoclonal anticomplement receptor type 1 on interactions between senescent human red blood cells and monocytic-macrophagic cells.

The effect of different murine monoclonal antibodies (Mab) specific for the glycoprotein complement receptor type 1 (CR1), type 2 (CR2), and type 3 (CR3) on the adhesion to and on the phagocytosis of human senescent red blood cells (S-RBC) by monocytes or by monocyte-derived macrophages (M phi) was investigated. Murine Mab anti-CR3 (anti-Leu 15 and OKM1) were found to inhibit, in the same order of magnitude, on one hand, the Fc receptors (FcR)-dependent rosetting and phagocytosis, and, on the other hand, the S-RBC rosetting and phagocytosis by adherent monocytes. Thus, the specific involvement of the CR3 epitopes recognized by Mab anti-Leu 15 or by OKM1 in the interactions between S-RBC and monocyte/macrophage could not be demonstrated. Murine Mab anti-CR1 was found to be a significant inhibitor of binding to and of phagocytosis of S-RBC (but not of young [Y] RBC) by monocytes or M phi, whereas Mab OKM5 carrying the same isotype as Mab anti-CR1, but a different specificity, was devoid of any significant inhibitory effect. Furthermore, Y-RBC or S-RBC opsonized with Mab anti-CR1 did not form FcR-dependent rosettes and were not internalized by monocytes; in addition, preincubation of phagocytes with Mab anti-CR1 did not inhibit FcR-dependent rosetting and phagocytosis. These results suggest that the effect of anti-CR1 is mediated through a specific binding to CR1 and not through an FcR blockade. As the role of specifically bound IgG on phagocytosis of human S-RBC by macrophages has previously been demonstrated by several authors, the present study suggests that monocyte-macrophage complement receptor type 1 may act in synergy with Fc receptors in the recognition of S-RBC by macrophages. It is shown in addition that the tripeptide Arg-Gly-Asp, identical to the region of iC3b recognized by CR3 and by several adhesion-promoting receptors that are structurally similar to CR3, such as fibronectin or vitronectin, is a significant inhibitor of the binding to and the phagocytosis of S-RBC by monocytic-macrophagic cells.

Antibodies, Monoclonal↗
PubMed1988

Some characteristics of human red blood cells separated according to their size: a comparison with density-fractionated red blood cells.

During their in vivo ageing, red blood cells (RBC) increase in density and become smaller. Age-defined RBC subpopulations are usually collected by centrifugation. A fractionation according to RBC volume has been proposed as an improved alternative to such age separation. Because a few data reported in the literature indicate some discrepancies between the two methods, blood samples were separated either by centrifugation or by counterflow centrifugation, and some characteristics of the RBC thus fractionated were studied. The enzyme activities decrease either when the density rises or when the volume (MCV) decreases. However, the comparison of other RBC characteristics strongly suggests that these two procedures do not lead to the collection of the same RBC subpopulations: for instance, the hemoglobin content increases when the MCV rises, whereas it remains constant whatever the RBC density is. With radiolabelled cells, it is shown 1) that the most dense RBC are recovered in all the size-separated RBC subpopulations, even though they tend to concentrate in the fractions with the largest MCV, and 2) that the smallest RBC are almost fairly distributed in all the RBC subpopulations, whatever their density, whereas the largest RBC are mainly, but not exclusively, present in the high-density fractions. Thus, fractionation according to size does not match separation according to density. Taken together with results from in vivo experiments carried out in mice and with the fact that reticulocytes are present in all the size-separated fractions, these data suggest that counterflow centrifugation may be a very questionable procedure to achieve a RBC fractionation according to age and therefore that RBC volume might not be a reliable criterion of RBC age.

Cell Separation↗
PubMed1988

Does red blood cell size correlate with red blood cell age in mouse?

Mouse red blood cells (RBC) can be fractionated according to their size by counterflow centrifugation. The mean corpuscular hemoglobin content and the enzyme activities (ASAT, LDH, PK and acetylcholinesterase) increase when the mean corpuscular volume (MCV) rises. However, the in-vivo survival of size-separated RBC is similar whatever their MCV is; thus, counterflow centrifugation is not a suitable procedure to achieve an age fractionation of mouse RBC. Moreover, RBC subpopulations collected by counterflow centrifugation are different from those obtained when RBC are fractionated according to their density.

Animals↗
PubMed1988

Effect of diosmin upon red blood cell deformability and osmotic fragility. Relationship with lipid content.

Rats were treated by ingesting forcibly 2 ml of a suspension of four different doses (100, 200, 300 and 400 mg/kg) of diosmin in carboxymethylcellulose (CMC) and were killed immediately or after 3 or 6 hours of fasting. Animals treated by CMC only in a similar way (gavage) exhibited a fall in red blood cell (RBC) membrane cholesterol and an increase in RBC rigidity at the third hour while osmotic fragility remained stable. Diosmin treatment opposed the rise in RBC rigidity evoked by the gavage and induced a dose-dependent decrease of the RBC membrane cholesterol over phospholipid ratio.

Animals↗
PubMed1987

Osmotic properties of human erythrocytes treated by phospholipase A2 from bee venom.

During treatment of human red cells with phospholipase A2 from bee venom, a linear increase of the MCV and of the osmotic fragility occurs in parallel with the cleavage of the accessible phospholipids. However, even after maximal hydrolysis, i.e. degradation of up to 65% of the phosphatidylcholines and up to 6% of the phosphatidyl-ethanolamines, almost no haemolysis is observed and the median corpuscular fragility is only 7% higher than that of control cells incubated without enzyme. Addition of albumin to the medium results in an important rise of the susceptibility to hypotonic saline solutions. Osmotic fragility curves obtained with red cells submitted to mild phospholipase action show evidence of subpopulations of cells with various sensitivities to osmotic lysis. This phenomenon can be partly explained by the heterogeneity of the cleavage intensity among the cell population. This hypothesis is supported by the studies of the lipid composition of phospholipase treated red cells fractionated according to their sensitivity to hypotonic lysis or to their size.

Bee Venoms↗