PubMed Health⌕ Search

Biomedical subjects

A Chevalier

Publications and source records attributed to A Chevalier.

At least 73 records · Page 4Linked to original sources
PubMed1992

Urolithiasis in patients with end stage renal failure.

Renal stones from 30 chronic hemodialysis patients were subjected to morphological study by means of microscopic examination and to constitutional analysis with infrared spectrophotometry. In 29 patients calculi could be classified into 3 main types: 1) protein stones made of pure proteins or with a protein core and less than 30% calcium oxalate (9 cases, or 30%)--they were observed predominantly in patients with primary glomerular disease, 2) oxalo-protein stones with a core of calcium oxalate and a total stone content of more than 30% calcium oxalate (15 cases, or 50%)--they appeared to be related to metabolic factors, such as high urinary oxalate and low urinary citrate concentration, and to iatrogenic factors, namely vitamin D3 and calcium salt supplementation, and 3) aluminum-magnesium urate stones, probably induced by aluminum overload (6 cases, or 20%). Thus, our study indicates that a significant proportion (70%) of stones formed by hemodialysis patients may be due to metabolic and iatrogenic factors. Our data suggest that accurate analysis of such stones provides useful information on pathogenetic factors and consequently may give clues to their prophylaxis.

Adult↗
PubMed1992

Neither dietary fructose, dextrose nor starch modifies in vitro glycerol release by adipocytes from streptozotocin-diabetic rats.

Because we found previously that fructose feeding could alter lipolytic responses to isoproterenol and insulin in normal rats, we studied the effects of the same diet in neonatal, streptozotocin-diabetic rats. Twenty-seven 5-wk-old diabetic Sprague-Dawley rats were fed a diet containing 57% carbohydrate as either fructose, dextrose or starch for 6 wk. At the end of the nutritional period, plasma glucose and insulin concentrations in fed rats were similar in the three diabetic groups. Plasma triacylglycerol concentrations were higher in the fructose-fed group than in the other two groups (P < 0.05). Neither the maximal adipocyte lipolytic response (fructose = 1147 +/- 165%, starch = 1823 +/- 329% and dextrose = 1287 +/- 239% of basal values) nor the sensitivity to isoproterenol (ED50) was changed by the dietary carbohydrate exchange. The maximal antilipolytic action of insulin (starch = 68 +/- 10%, dextrose = 41 +/- 13%, fructose = 95 +/- 29% of stimulated lipolysis values) was comparable in the three diet groups. Thus, 6 wk of fructose feeding in diabetic rats increased plasma triacylglycerol concentrations, but had no detectable effect on plasma glucose or insulin concentrations, isoproterenol-induced lipolysis or the antilipolytic action of insulin.

Adipose Tissue↗
PubMed1992

Short- and long-term efficacy of total parathyroidectomy with immediate autografting compared with subtotal parathyroidectomy in hemodialysis patients.

A retrospective study was performed in chronic hemodialysis patients comparing total parathyroidectomy (PTX) followed by immediate autografting (IA) (total PTX+IA) with subtotal parathyroidectomy (subtotal PTX). One hundred six patients with severe, uncontrolled hyperparathyroidism were referred to this center and underwent surgery during the period from 1980 to 1990. Long-term follow-up after PTX was available in 49 of them: 28 patients had total PTX+IA and 21 had subtotal PTX. The two surgical methods were evaluated with respect to preoperative severity of hyperparathyroidism, immediate postoperative results, and long-term parathyroid status, as evaluated by an RIA measuring intact immunoreactive parathyroid hormone (intact iPTH; normal values, 15 to 65 pg/mL). The initial degree of hyperparathyroidism was comparable in the two groups. An excellent short-term control of hyperparathyroidism was achieved in the great majority (95%) of patients with either surgical procedure. However, long-term normalization of parathyroid gland activity was achieved in only one third of patients whereas 33% had elevated intact iPTH levels (> 130 pg/mL; i.e., higher than twice the upper range of normal) and 32% had low intact iPTH levels (< 15 pg/mL), consistent with permanent hypoparathyroidism. No difference was found in the immediate failure rates: 0 of 28 cases after total PTX+IA compared with 2 of 21 cases after subtotal PTX. Similarly, long-term intact iPTH levels were comparable: 400 +/- 105 versus 212 +/- 82 pg/mL (mean +/- SE; P = not significant). Interestingly, long-term serum intact iPTH levels were higher in patients with nodular (N = 18) than with diffusely (N = 26) hyperplastic glands: 556 +/- 146 versus 126 +/- 52 pg/mL (P < 0.001) and recurrence of hyperparathyroidism was more frequent with nodular hyperplasia (11 of 18) than with diffuse hyperplasia (4 of 26) (P < 0.02). In conclusion, although excellent short-term results were obtained with both procedures, satisfactory long-term control of parathyroid gland function was achieved in only one third of the patients, the other two third remaining either hypoparathyroid or developing recurrent hyperparathyroidism. Last, the histological subtype of parathyroid glands was partially predictive of the recurrence of hyperparathyroidism.

Adult↗
PubMed1990

Phospholipase A activity of cultured rat ventricular myocyte is affected by the nature of cellular polyunsaturated fatty acids.

Fatty acid composition of membrane phospholipids of cultured cardiomyocytes can be modified by the type of polyunsaturated fatty acids (n-3 or n-6 PUFA) constituting the culture medium. In this study, we investigated the effect of fatty acid modification on the activities of the key enzymes involved in the deacylation-reacylation cycle of membrane phospholipids. Results showed that cardiomyocytes grown in the presence of n-6 PUFA exhibited a higher specific alkaline phospholipase A (mainly A2) activity (+34%) and a moderately lower lysophospholipase activity (-17%) than when incubated with n-3 PUFA. AcylCoA:lysophosphatidylcholine acyltransferase, acid lysosomal phospholipase A1 and acylCoA synthetase activities were not significantly altered by changes in cellular PUFA composition. It was demonstrated that the differences between phospholipase A activities of the two types of cultured cells were linked neither to a differential leakage of enzyme nor to oxidative injury to the enzyme through blockage of essential sulfhydryl groups. One likely explanation is that the PUFA-induced changes in membrane composition alter membrane physical properties which, in turn, affect membrane-bound phospholipase A activity. Possible beneficial effects of the n-3 PUFA-induced changes on membrane stability are discussed.

Animals↗
PubMed1990

Influence of phospholipid polyunsatured fatty acid composition on some metabolic disorders induced in rat cardiomyocytes by hypoxia and reoxygenation.

The influence of membrane polyunsaturated fatty acid (PUFA) composition on lactate production, energy status, enzyme leakage and cell defences against oxygen free radical production was studied in cultured rat ventricular myocytes during hypoxia and reoxygenation. After 4 days in a conventional serum-supplemented medium, the cardiomyocytes were incubated for 24 h in synthetic media containing either linoleate and arachidonate (SM6 Medium) or linolenate and eicosapentaenoate (SM3 Medium) as unique source of PUFA. The fatty acid n-6/n-3 ratio of phospholipid was 13.1 in SM6 cells and 0.9 in SM3 cells. Hypoxia induced an increase in lactate production, severe decreases in ATP and ADP, leakage of cellular lactate dehydrogenase and reduction of superoxide dismutase and glutathione peroxidase activities. Reoxygenation of hypoxic cells reduced lactate production to normal aerobic values and allowed slight resynthesis of ATP from AMP. However, lactate dehydrogenase release was not stopped by reoxygenation, and decreases in superoxide dismutase and glutathione peroxidase activities were not avoided. The majority of the biochemical parameters measured during normoxia, hypoxia and reoxygenation were not significantly affected by changes in the fatty acid composition of membrane phospholipids, except for reduced superoxide dismutase activity which appeared earlier in SM3 cells during hypoxia. We conclude that the sarcolemmal PUFA composition of cultured rat ventricular myocytes does not significantly influence altered cell metabolism elicited by hypoxia and reoxygenation.

Adenine Nucleotides↗
PubMed1990

Glutaraldehyde effect on hemoglobin: evidence for an ion environment modification based on electron paramagnetic resonance and Mossbauer spectroscopies.

Glutaraldehyde is a widely used reagent for hemoglobin cross-linking in blood substitutes research. However, hemoglobin polymerization by glutaraldehyde involves modifications of its functional properties, such as oxygen affinity, redox potentials, and autoxidation kinetics. The aim of this article is to investigate, by electron paramagnetic resonance and Mossbauer spectroscopies, the changes that occur in the iron environment after glutaraldehyde cross-linking. Spectrometric studies were performed with native hemoglobin and hemoglobin cross-linked as soluble and insoluble polymers. Spectrometry data comparison with glutaraldehyde-modified hemoglobin functional properties allows to interpret from a structural point of view that glutaraldehyde action occurs as a decrease of the O--N(F8His) distance, an increase of the Fe--N(F8His) bond length, and the decrease of the distal-side steric hindrance.

Cross-Linking Reagents↗
PubMed1990

Oxygen and substrate deprivation on isolated rat cardiac myocytes: temporal relationship between electromechanical and biochemical consequences.

The effects of hypoxia and reoxygenation on action potentials (AP), contractions, and certain biochemical parameters were studied in isolated rat ventricular myocytes in monolayer culture in the presence and absence of glucose. Substrate deprivation alone had no influence on the basal properties. In the presence of glucose, a 4-h hypoxic treatment caused only a moderate decrease in AP amplitude and rate. In substrate-free conditions, hypoxia induced a gradual decline in plateau potential level and in AP duration and rate, followed by rhythm abnormalities and a failure of the electromechanical coupling. Spontaneous AP generation then ceased, and the resting potential decreased with increased duration of hypoxia. These alterations were associated with a decrease in ATP content, an increase in the lactate production, and a leakage of about 50% of the total cellular lactate dehydrogenase (LDH). Cells reoxygenated after 150 min hypoxia recovered near-normal function, while the ATP depletion ceased and the rate of lactate and LDH loss was diminished. Conversely, cells reoxygenated after 4 h hypoxia exhibited a further decrease of the residual resting polarization and no change in the decline of intracellular ATP and in the efflux of cytosolic lactate and LDH. The results of this study indicate that (1) the sequence and the extent of functional alterations are dependent on the duration of hypoxia in the absence of exogenous substrate and (2) ATP depletion and the amount of lactate and LDH released during hypoxia are related to the shift from reversibly to irreversibly damaged cells.

Action Potentials↗
PubMed1990

[Back pain at the French National Electricity and Gas Company].

Frequency and severity of sickness absence due to back pain were studied among workers in the French National Electric and Gas Company. The results showed that the prevalence of back pain was less than 10% a year but the annual duration of absence that it involved was relatively important: 30 days in the average per disabled person. In a second part, the prevalence was studied according to individual and occupational variables. Differences according to occupational category are very important: between the occupations the most prone to absence, those of "switchboard operator", "mechanics driver" and "warehouseman" and the ones least exposed "managerial staff" and "skilled technician and upper management", the ratio for the prevalences was 10.

Absenteeism↗
PubMed1990

[Evaluation of mortality in hospitalized mental patients 1968-1982].

Yearly, between 1968 and 1976, and every two years from 1976 to 1982, diagnostic data based on a national classification of mental disorders were homogeneously collected in French public psychiatric hospitals. The hospitalized population was estimated by the person-year method, using data on length of stay. The number of observed deaths was compared with the number of deaths expected (Standardized mortality ratio). The standardized mortality ratio (SMR) for psychiatric inpatients were found irregularly and slightly decreasing, except among women under 45: this SMR was higher in 1982 (9.6) than in 1968 (7.4). The SMR for neuroses, in the under 55 years age group, showed a regular increase especially among women. The SMR for psychoses and mental retardation was decreasing among men. For people aged more than 55 years the SMR was decreasing for all groups of diagnosis.

Adult↗
PubMed1989

Expression of a public idiotype by human monoclonal IgM directed to myelin-associated glycoprotein and characterization of the variability subgroup of their heavy and light chains.

Most studies using rabbit or mouse antisera failed to detect CRI between human IgM directed to MAG. We show here that 9 of 10 such IgM express a public CRI as defined by a nonhuman primate antiserum. Shared idiotype is likely involved in (or close to) the combining site of those IgM since antiidiotypic serum inhibited the binding of IgM to MAG and reacted with IgM having different variable regions of light and heavy chains. Partial aminoterminal sequence of heavy and light chains showed that anti-MAG IgM use either lambda chains (one IgM) or kappa light chains (six IgM) of different variability subgroups (V kappa IV in three instances, V kappa I in two, and V kappa II in one), whereas heavy chains belong to the VHIII (six IgM) or to the VHII (1 IgM) subgroup. These features distinguish these IgM from other human monoclonal IgM with a defined antibody activity, such as rheumatoid factors or cold agglutinins.

Amino Acid Sequence↗
PubMed1989

Analysis of mucosal bladder leucocyte subpopulations in patients treated with intravesical Bacillus Calmette-Guerin.

Immunohistochemical techniques were used to investigate leucocyte subpopulations in the bladders of patients with superficial transitional cell carcinoma treated with BCG Pasteur. Leucocyte subsets were enumerated with a panel of monoclonal antibodies which included CD3, CD4, CD8, TQ1, Leu7, CD15, HLA-DR, CD25, CD22. We demonstrated in the bladders of patients treated with BCG a particular lymphocyte population; the major subset was an inducer (CD4+, TQ1-) which was activated (CD25+, HLA-DR+) and associated with polymorphonuclear eosinophils. There was neither inducer of suppression nor major cytotoxic/suppressive subsets. CD8+ and NK cells could not be the primary mediators of BCG activity. These data supported the hypothesis of a helper T lymphocyte activity associated with lymphokine production and activation of effector killer cells.

BCG Vaccine↗
PubMed1989

The organoleptic characteristics of fructose and sucrose have no differential influence on their consumption by healthy subjects.

Fructose and sucrose have different organoleptic characteristics. We studied their net impact on the rate of sugar consumption in 8 healthy families. Each family, consisting of the two parents and their 1 to 4 children, received the two sugars in a randomised cross-over blind random design. Each sugar was given for a period of one month preceded by an adaptation period of 15 days. We found no significant difference between the amount of fructose or sucrose consumed (2232 +/- 1361 vs. 2260 +/- 1272 g/family/30 days, respectively). All the subjects consumed only moderate amounts from the two sugars (17.9 +/- 8.5 vs. 18.1 +/- 7.7 for fructose and sucrose, respectively). There were no correlations between either the number or the age of children in a family and the consumed quantities per subject. The palatability of the tested sugars were comparable to a lesser or greater extent: 4 families found fructose similar to their usual sugar (sucrose) while the others found it different. Fructose was well tolerated by all the subjects without any gastro-intestinal disturbances. We concluded that fructose and sucrose were nearly equally accepted and consumed in comparable amounts by normal healthy subjects. Thus, the type of sugar used has no effect on the rate of its consumption. Several factors, independent of flavour, might contribute to the development of sugars preferences.

Adult↗
PubMed1989

Comparison of four severity scores in patients with head trauma.

This study examines the performance of four severity scores in a group of 70 consecutive patients with head trauma, hospitalized in the same neurosurgical ICU. On day of admission to the ICU, data were collected from each patient to compute Acute Physiology Score (APS), Simplified Acute Physiology Score (SAPS), Glasgow Coma Scale (GCS), and Therapeutic Intervention Scoring System (TISS). These four scores were statistically correlated with the outcome of patients. Results also indicate that GCS was superior to any other score in predicting outcome of patients and allowed better specificity and sensitivity. Regarding the level of care needed by patients, TISS was superior to any other scoring system. The difficulty in estimating individual prognosis is discussed, since scoring systems are aimed at classifying groups of patients, not individuals. It is concluded that GCS is a simpler and less time consuming method in predicting outcome of patients with head trauma.

Adolescent↗
PubMed1989

[Measurement by isotope study of the cardiac output in the elderly].

Cardiac output and haemodynamic volumetric values (stroke volume, stroke index, left ventricular end-diastolic volume, blood volume, mean corpuscular volume and packed red cell volume) were measured in a population of 69 very old subjects (80 to 102 years) whose heart was regarded as normal on the basis of criteria determined, by radiocardiography and radionuclide ventriculography. These harmless and non-invasive techniques provided reference values in subjects of a seldom explored age group. Altogether, these values were lower than those of younger adults, and they decreased with age. Their reliability is due to the fact that they were obtained by true measurement and not by extrapolation of results observed in adults.

Age Factors↗