PubMed Health⌕ Search

Biomedical subjects

J Chevallier

Publications and source records attributed to J Chevallier.

At least 55 records · Page 3Linked to original sources
PubMed1988

[Numeration of patients from anonymous data: a method established with the epidemiological data of public health of Paris].

Anonymity in the registration of medical information for computerized data, which is imposed by French legislation, complicates the processing and utilization of epidemiological data at Paris's Public Hospitals ("Assistance Publique de Paris"). The number of patients may only be counted by linkage of anonymous data from files containing information on hospital stays. Some characteristics of this procedure are described. An original method for refusing the procedure giving anormalous results, based on probability calculation, is developed and applied to one example.

Adult↗
PubMed1988

[Human immunodeficiency virus infections and hospital structures: trends in the Public Assistance of Paris].

The evolution of the number of patients with the AIDS virus admitted to the Paris hospitals is monitored by two index systems, one based on the discharge diagnosis and the other a transverse inquiry on a given day, updated every three months since its conception at the beginning of 1986. This index also allows an evaluation of the number of patients consulting for this condition. In 1986, AIDS and AIDS related complexes (ARC) represented 1 p. 100 of the activity of the Assistance Publique Paris hospitals including all in- and outpatients. These conditions will probably account for 2 p. 100 of the activity in 1987. The duration of cumulated hospital stay is on average 30 days per year for AIDS and ARC, divided into roughly 3 admissions, with a tendency towards more under-24 hour stays and domiciliary care. The clinical departments looking after these patients are varied and increasing in number, but most of the work is carried out by Departments of Infectious and Parasitic Medicine.

AIDS-Related Complex↗
PubMed1987

Quantitative determination of the calcium involved in the regulation of the Ca2+-ATPase activity in sarcoplasmic reticulum vesicles.

The dependence of the Ca2+-ATPase activity of sarcoplasmic reticulum vesicles upon the intravesicular concentration of calcium accumulated after active uptake was studied. The internal calcium concentration was modified by addition of the ionophore A23187 at the steady state of accumulation. About half of the calcium accumulated could be released at low ionophore concentration without any concomitant activation of the Ca2+-ATPase. This population of calcium might consist of calcium free in the lumen of the vesicles or bound to the bilayer at sites which do not interact with the ATPase activity. At higher concentrations of ionophore (above 1.75 nmol A23187/mg protein) the release of calcium activated this enzyme. This phenomenon was independent of the extravesicular calcium concentration and might be explained by assuming second species of calcium ions bound to the inner side of the membrane and in close functional interaction with the Ca2+-ATPase.

Animals↗
PubMed1987

Ultrastructural and cytochemical characterization of subcellular fraction of plasmalemmal origin obtained from uterine longitudinal smooth muscle.

The role of Ca2+-ATPase as the driving force for active calcium uptake, involved in the relaxation of smooth muscle, was studied. It was shown by immunocytochemistry that Ca2+-ATPase activity was localized at the plasma membrane level of longitudinal smooth muscle of pregnant rat uteri (18-20 days). To study calcium regulation in uterine longitudinal smooth muscle, 2 microsomal fractions (F1 and F2) were obtained, enriched in plasma membrane material (Lalanne et al., 1984, in: Calcium Regulation in Smooth Muscles. INSERM series, 124, pp. 283-292). In the present paper this material is characterized at both morphologic and cytochemical levels. Both fractions are ultrastructurally heterogeneous: (a) thin sections clearly show 2 populations that differ in vesicular shape and size; (b) negative staining also shows differences in membrane structure, which could be related to biochemical differences and/or to the well known heterogeneity of the plasma membrane. Two reactions (PATAg and concanavalin A-biotin-avidin-ferritin), allowing visualization of cell coat glycans, were performed on F1 and F2 and on thin sections of longitudinal smooth muscle. Plasma membrane and almost all the vesicles of F1 and F2 are reactive. It is concluded that these 2 fractions are characteristic enough for studying, at the molecular level, the ability of plasma membrane to control calcium circulation in uterine smooth muscle.

Animals↗
PubMed1986

Study of the electrokinetic properties of reconstituted sarcoplasmic reticulum vesicles.

A study of electrokinetic properties of reconstituted sarcoplasmic reticulum was undertaken to determine the nature of the groups bearing the negative charge of the membrane. After incorporation of phosphatidylcholine into the bilayer, it was found that the Ca2+-ATPase embedded in functional vesicles bore 3e- per mole. When the surface charge density of the hydrodynamic particles became more negatively charged by incorporation of phosphatidylserine molecules, the reconstituted vesicles had a tendency to build large structures resulting from vesicle-vesicle interaction and containing large amounts of divalent cations. These aggregated structures may partially explain the discrepancy observed between the expected value of the surface charge density and the data obtained by electrophoretic mobility measurements. This work emphasizes the importance of a renewal of the classical interpretation of electrophoretic mobility data in order to analyze the results obtained with biological material. To explain the energy transduction process which takes place in the sarcoplasmic reticulum membrane, it was of interest to determine whether or not variations of the surface electrical properties affect the calcium ion translocation upon ATP hydrolysis. Relatively significant modifications of the bilayer composition and surface charge density did not appreciably affect the calcium transport activity.

Biological Transport↗
PubMed1986

[A project for developing rheumatologic epidemiology in France. The setting up of a network].

The epidemiological approach is indispensable in rheumatology. It involves the collection of quantitative data on the extent and geographical distribution of different rheumatismal pathologies, their socioeconomic consequences, the handicap they produce, the evaluation of a system of care and the risk factors involved. The epidemiological group of the French Rheumatology Society has recorded the data currently available in France and the studies performed in France and abroad. It recommends the setting up of an epidemiological monitoring network on a national scale consisting of rheumatologists and general practitioners.

Epidemiologic Methods↗
PubMed1986

[Rheumatic morbidity seen in their consultation work by rheumatologists of the epidemiology team of the French Rheumatology Society].

The authors present the Epidemiology Team of the French Rheumatology Society. This Society was founded in order to involve practitioners in epidemiologic research in rheumatology and to provide them with practical information likely to be of value to them. The team currently includes 251 rheumatologists and 125 general practitioners. A survey of members was carried out concerning their patients. The data collected concerned a total of 5,581 patients seen by the rheumatologists. The national significance of the findings is discussed.

Female↗
PubMed1986

[Surveys of the epidemiological team of the French Rheumatology Society (RESFR) on the prescription of D-penicillamine in the treatment of rheumatoid polyarthritis].

Two surveys carried out by the Epidemiology Team of the French Rheumatology Society (RESFR) were used to assess the treatment of rheumatoid arthritis (RA) by means of D-penicillamine (DP). In the initial survey, which is described in this article, 119 rheumatologists throughout France were asked to give their opinion as to the place of DP: they use this drug in cases of severe RA, usually after gold salts and synthetic antimalarials have proved ineffective. The dosage is generally 600 mg per day, with a maximum dosage of 900 mg per day. The rheumatologists consider DP an effective treatment with good or fair clinical safety. The most frequent adverse reactions are proteinuria and skin eruptions.

Adult↗
PubMed1986

[The value of breast lymphoscintigraphy in the definition of axillary staging in cancer of the breast].

Axillary lymphoscintigraphy (ALS) has been investigated in 51 patients with operable breast carcinoma between July 1982 and February 1984. Pre-operative intra-tumoral injection of 2.5 cm Ci of technetium 99 m antimony sulfide colloid has been performed before axillary dissection. We compared the scans produced by ALS with the results of pre-operative clinical examination of the axilla (UICC criterias) and to the histological status of the nodes surgically removed. We focused on the statistical methodology because, for us, most of the studies use inadequate tests. Axillary lymphoscintigraphy did not predict axillary metastase in breast cancer with precision. Its score was under clinical exam. Today, we are not allowed to abandon axillary dissection for pre-operative ALS. That simple and non traumatic examination appeared to be of no value in order to determine the axillary metastatic nodal status in breast cancer.

Axilla↗
PubMed1985

Simultaneous preparation of membrane fractions from small amounts of skeletal muscle: a study on mitochondrial and microsomal fractions from MedJ mice.

This work is the first biochemical study of skeletal muscle membranes isolated from mice displaying an inherited neuromuscular disease: MedJ strains. It is focused on the research of a possible alteration of membrane biological activities related to this disease. We describe a procedure which allows the simultaneous preparation of mitochondrial and microsomal fractions from a small amount of skeletal muscle. When EGTA and BSA are present in the buffers, functional mitochondria can be prepared. Under these conditions we found that no major modification occurs for this disease at the mitochondrial inner membrane level. A dramatic impairment of a calcium active transport activity found in the microsomal fraction obtained from MedJ is noticed, suggesting that some modification may occur at this level.

Animals↗
PubMed1984

Isolation and characterization of plasma membranes from rabbit skeletal muscle.

An improved procedure was developed for the isolation of skeletal muscle plasma membranes. This method includes a DNAse treatment of the homogenate prior to the isolation of membranes by differential and sucrose gradient centrifugation techniques. We obtained two light fractions which were highly enriched in many biochemical and chemical plasma membrane markers. These fractions were shown to be mostly inside-out vesicles containing a Ca2+-ATPase activity. These results suggested that this enzyme could participate in the extrusion of calcium ions from the muscle cells.

5'-Nucleotidase↗
PubMed1984

Electrokinetic and hydrodynamic properties of sarcoplasmic reticulum vesicles: a study by laser Doppler electrophoresis and quasi-elastic light scattering.

The electrical properties of sarcoplasmic reticulum vesicles were studied using electrophoretic mobility measurements by laser Doppler velocimetry. Combined with quasi-elastic light scattering analysis, this method enabled us to monitor changes in membrane surface charge density upon addition of NaCl, CaCl2, and MgCl2 solutions. At low ionic strength (4.7 mM), and in the absence of divalent salts, sarcoplasmic reticulum vesicles displayed a zeta potential value of -32.6 mV and a surface charge density of 5.4 10(-3) C/m2, corresponding to one elementary negative charge per 30 nm2 or about 2900 negative charges per vesicle. Upon addition of NaCl (up to 100 mM) vesicles became more negative (from 2900 to 6200 negative charges per vesicle), suggesting chloride binding or adsorption on the membrane. A noticeable increase of the vesicular size was observed upon addition of calcium or magnesium (25 to 30% increase of the hydrodynamic radius for 2.5 mM CaCl2 or MgCl2). This effect was prevented or suppressed by addition of relatively low concentrations of NaCl (50 mM). At low divalent cation concentrations one-third of the total net charge of the vesicles was neutralized suggesting a specific binding of cation on the membrane. At higher salt concentrations no modification of this parameter was observed. These results support the Gouy and Chapman theory about the electrical properties of sarcoplasmic reticulum vesicles.

Animals↗