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Biomedical subjects

J Chevalier

Publications and source records attributed to J Chevalier.

At least 73 records · Page 4Linked to original sources
PubMed1995

Consecutive use of hormonally defined serum-free media to establish highly differentiated human renal proximal tubule cells in primary culture.

Highly differentiated human proximal tubule (HPT) cells in primary culture were established from heterogeneous suspension of tubules prepared from the human renal cortex by an original two-step procedure. First, gluconeogenic-competent HPT cells were selected by using a hormonally defined serum-free medium without glucose or insulin; then, the selected HPT cells were grown in a medium containing a low concentration of glucose (1 mM) and insulin (0.5 micrograms/mL) but no antibiotics. HPT cells grown on plastic support formed confluent, cobblestone-like monolayers with numerous mitochondria and pinocytosis vacuoles, solitary cilia, junctional complexes, and a well-developed brush border consisting of densely packed microvilli. Compared with cell monolayers on plastic support, HPT cells grown on porous filter membranes showed better morphologic differentiation. HPT cell monolayers expressed the following differentiated functions of the proximal tubule in situ: a low-affinity, high-capacity Na(+)-dependent glucose transport system inhibited by phlorizin, a high-affinity Na(+)-dependent phosphate transport system, a basolateral organic cation uptake inhibited by mepiperphenidol, parathyroid hormone-sensitive cAMP synthesis, brush-border hydrolase activities, gluconeogenesis-associated enzymes, glutathione-S-transferases and N-acetyl-beta-D-glucosaminidase. The medium containing low glucose and insulin concentrations markedly limited the increase in glycolysis but did not prevent the falls in gluconeogenesis and brush-border hydrolase activity at any time of the culture period. Similar decreases of brush border enzyme activities were obtained for HPT cells grown either on plastic or on porous filter membrane. A thorough characterization study demonstrated that this simple and preparative experimental approach makes it possible to establish highly differentiated HPT cells in primary culture suitable for investigating human renal proximal tubular cell function.

Biological Transport↗
PubMed1995

Interaction between tricyclic psychopharmacons and some antibiotics.

The tricyclic psychopharmacons, e.g. clozapine, promethazine and imipramine cure plasmids and inhibit plasmid transfer among bacteria due to the inhibition of supercoiling activity on DNA gyrase. In addition an interaction was found between clozapine, imipramine, promethazine and some antibiotics, e.g. penicillins and tetracycline in vitro. The nature of interaction is based on a charge transfer complex, which is formed between clozapine, imipramine, promethazine and penicillins. Differential spectrophotometry showed that ampicillin reduced the highest energy peaks of clozapine, promethazine and imipramine. Streptomycin did not alter the spectrum of clozapine; however, tetracycline somewhat reduced all the peaks of clozapine. Clozapine and promethazine exhibited a synergistic effect with ampicillin, tetracycline and gentamicin on Escherichia coli cells in in vitro. This kind of interaction was missing in the case of imipramine.

Anti-Bacterial Agents↗
PubMed1995

[Approach of cellular mechanisms of glomerulosclerosis in a model of accelerated aging the obese Zucker rat].

With age, the morphological changes which occur in renal glomeruli in the absence of any added pathology are an expansion of the extracellular matrices (ECM)--glomerular basement membrane (GBM) and mesangial matrix--and lesions of focal and segmental glomerular hyalinosis (FSGH). Although the mechanisms involved in these glomerular changes are still unknown, an inflammatory step seems to precede the expansion of the extracellular matrices, but the nature of the cytokines and adhesion molecules has yet to be explored. In order to understand the cellular and molecular events of the FSGH, we used the genetically obese Zucker rat (fa/fa) which develops several early FSGH lesions. We observed that FSGH is the result of a modification of the podocyte: 1) bulging of the podocyte with endocytotic vesicles rich in albumin; 2) detachment from the GBM, collapsing of the capillary loops with a progressive disappearance of capillary cells and formation of hyalin and lipid deposits, synthesis of new ECM components; 3) focal adherence of the GBM and the basement lamina of Bowman's capsule and synthesis of new matrix. The detachment of the podocytes from the GBM appeared to be linked to the disappearance of the alpha 3 beta 1 integrin, major molecule which anchors the epithelial cells to the GBM. By immuno-gold techniques, we showed that the density of alpha 3 moieties significantly diminished when podocytes are spreaded over the GBM. This integrin is probably bound to the laminin in the GBM.

Aging↗
PubMed1994

Effect of chronic ANG I-converting enzyme inhibition on aging processes. I. Kidney structure and function.

The effect of angiotensin I-converting enzyme inhibition (ACEI) on the age-related changes in the kidney structure and function was investigated in rodents. Normotensive male Wistar (WAG)/Rij rats were treated with perindopril from the age of 6 mo to the day of killing at 12, 24, or 30 mo. Mean blood pressure, constant from 6 to 30 mo, was reduced by 19 mmHg in treated animals. With age, the major functional modifications were a decrease in glomerular filtration rate and in renal blood flow, a rise in intrarenal vascular resistance (IVR), a reduced tubular reabsorption of salts, and a progressive increase in proteinuria. ACEI significantly reduced IVR and proteinuria. From a structural point of view, the glomeruli showed 1) an increase in size, 2) a decrease in capillary surface, 3) a diffuse thickening of the glomerular basement membrane, 4) an expansion of the mesangial matrix, and 5) an accumulation of albumin droplets in podocytes inducing 6) a dispersed focal and segmental glomerulosclerosis which, at 30 mo, affected < 2% of glomeruli. Of these six age-related structural changes, ACEI delayed the appearance of the three latter changes.

Aging↗
PubMed1993

Effect of glucose and insulin deprivation on differentiation and carbohydrate metabolism of rabbit proximal tubular cells in primary culture.

Rabbit proximal tubule cells in primary culture revert from gluconeogenesis to glycolysis. To determine whether glucose and insulin deprivation of the culture medium could prevent this metabolic conversion without a loss of differentiation, rabbit proximal tubule cells were cultured in hormonally defined medium free of glucose and insulin and compared to rabbit proximal tubule cells cultured in medium supplemented with 17.5 mM glucose and 5 micrograms/ml insulin. In the two culture conditions, RPT cells grew at a similar rate and reached confluency within 4-5 days. Patterns of enzyme activity, including brush-border hydrolases, N-acetyl-beta-D-glucosaminidase and glutathione-S-transferases as a function of culture time were comparable in the two media. During the growth phase in glucose- and insulin-free medium, cells showed higher sodium-dependent glucose uptake. Scanning electron microscopy revealed a high density of microvilli at confluency regardless of the culture conditions. In both the presence and absence of glucose and insulin, the activities of gluconeogenic enzymes, phosphoenolpyruvate carboxykinase and fructose-1,6-bisphosphatase, as well as basal and pyruvate-stimulated glucose production fell markedly as a function of time. By contrast, glucose and insulin deprivation greatly reduced both the lactate production rate and the activities of glycolytic enzymes, pyruvate kinase, hexokinase and lactate dehydrogenase.

Acetylglucosaminidase↗
PubMed1993

Chronic inhalation toxicity of size-separated glass fibers in Fischer 344 rats.

This study was initiated to determine the chronic biological effects in Fisher 344 rats of inhaled size-separated respirable fractions of fibrous glass (FG) having compositions representative of common building insulation wools. Rats were exposed using nose-only inhalation chambers, 6 hr/day, 5 days/week, for 24 months to three concentrations (3, 16, and 30 mg/m3) of two different compositions of FG (designated MMVF 10 and MMVF 11), or to filtered air (negative control). Fibrous glass findings were compared to those from a concurrent inhalation study of chrysotile asbestos and refractory ceramic fiber (RCF). The FGs used in this study were size selected to be largely respirable in the rat and the aerosol generation technique did not alter the dimensions of the fibers. Interim euthanizations took place at 3- to 6-month intervals to monitor progression of pulmonary changes. Fibers were recovered from digested lung tissue for determination of changes in fiber number and morphology. In animals exposed to 30 mg/m3 of MMVF 10 or MMVF 11, 4.2 +/- 0.9 x 10(5) and 6.4 +/- 3.1 x 10(5) fibers/mg dry lung tissue, respectively, were recovered after 24 months of exposure. Exposure to chrysotile asbestos (10 mg/m3) and to a lesser extent RCF (30 mg/m3) resulted in pulmonary fibrosis as well as mesothelioma and significant increases in lung tumors. FG exposure was associated with a nonspecific inflammatory response (macrophage response) in the lungs that did not appear to progress after 6-12 months of exposure. These cellular changes are reversible and are similar to the effects observed after inhalation of an inert dust. No lung fibrosis was observed in the FG-exposed animals. Further, FG exposure resulted in no mesotheliomas and no statistically significant increase in lung tumor incidence when compared to that of the negative control group. These findings, along with previous inhalation studies, suggest that respirable fibrous glass does not represent a significant hazard for fibrotic or neoplastic lung disease in humans.

Aerosols↗
PubMed1992

Comparative study on the antimicrobial effects of Hexomedine and Betadine on the human skin flora.

Studies were carried out to detect the modifications, if any, on the peri-umbilical flora of six healthy volunteers after two or three daily applications of Hexomedine solution (HEX) and Betadine solution (PVI) repeated for five consecutive days. A standardized scrubbing method was used for bacterial sampling. Surviving bacteria were selected with both selective and non-selective media, and then identified by gas chromatographic fatty acid analysis. Both antiseptics were highly effective, showing both immediate and residual antimicrobial activities. The use of HEX led to a slight increase in Gram-positive cocci and a small decrease in coryneforms, but PVI produced a marked increase in Gram-positive cocci and a sharp decrease in coryneforms. The two antiseptics, however, caused no major alteration in the cutaneous microbial population. Indeed, neither the overgrowth of Gram-negative bacilli nor the emergence of resistant species was observed.

Adult↗
PubMed1992

Evaluation of antimicrobial interactions between chlorhexidine, quaternary ammonium compounds, preservatives and excipients.

The antimicrobial interactions of 49 combinations of chlorhexidine, quaternary ammonium compounds, preservatives and excipients were evaluated by the method of Berenbaum and the checkerboard titration method, with Staphylococcus aureus CIP 53154 and Escherichia coli CIP 54127 as test strains. MIC determinations were carried out as a preliminary step, and relative growth intensity was used to describe the bacteriostatic activity of surface-active agents (Amonyl 380 BA, Amonyl 671 SB). In the study of combinations, results were interpreted with Fractional Inhibitory Concentration indexes and represented by isobolograms. A fair correlation was shown between the method of Berenbaum and the checkerboard titration method. Combinations between chlorhexidine, cetrimonium bromide and benzalkonium chloride were synergistic or additive; combinations of antiseptics and preservatives were generally not antagonistic. The methods were also well adapted to the study of interactions involving surface-active agents, a critical problem in the formulation of topical antimicrobial agents.

Anti-Infective Agents, Local↗
PubMed1992

[Contribution of 99m Tc-HMPAO single-photon emission-computed tomography to the perioperative evaluation of subarachnoid hemorrhage caused by ruptured aneurysms].

Twenty one cases of proven subarachnoid hemorrhage (S.A.H.) have been analysed in a protocol especially including transcranial doppler (T.C.D.) and 88mTc-H.M.P.A.O. single photon emission tomography (H.M.P.A.O.-S.P.E.C.T.). Seventeen patients were intraoperatively studied. All data were compared with clinical grading, computerized tomography (C.T.) and angiography. S.P.E.C.T. is a quite recent method of measuring and three-dimensional imaging of brain perfusion. It provides important information for the diagnosis of ischemic syndromes in S.A.H. Sixty-two S.P.E.C.T.-scans were performed in twenty one patients. Fifty-eight were abnormal and showed significant abnormalities of brain perfusion varying in extent and severity. In this preliminary study, we set out to validate the clinical use of H.M.P.A.O.-S.P.E.C.T. for the diagnosis of "vapospasm" comparing S.P.E.C.T. data with classical criteria. We propose a classification which allowed us to quantify the ischemic risk in an attempt to adapt the global therapeutic management to hemodynamic data. This method appears to be very sensitive and reliable in this field. It will introduce, if these first results are confirmed, important criteria for the evaluation of patients presenting with S.A.H. as far as prognosis and treatment are concerned, especially in regard to timing of surgery and institution of medical hemodynamic therapy.

Aneurysm, Ruptured↗
PubMed1991

Morphological and biochemical characterization of the opossum kidney cell line and primary cultures of rabbit proximal tubule cells in serum-free defined medium.

Proliferation, morphology and time course patterns of marker enzyme activities of primary cultures of renal rabbit proximal tubule cells (RPT cells) and Opossum kidney cells (OK cells) in antibiotic-free and serum-free defined medium were investigated. Both RPT and OK cells grew to confluency within 6-8 days. RPT cells were thicker and displayed higher density of both microvilli and mitochondria when compared with OK cells. RPT cells exhibited higher activity of glutathione-S-transferase when compared with OK cells, whereas in the latter, higher glutathione content could be detected. Apical and basolateral membrane enzymes were higher in RPT cells than in OK cells. Stable high glycolytic activity and low gluconeogenesis activity in OK cells pointed out a strict dependence on glycolysis, whereas RPT cells exhibited glucose metabolism shift towards the glycolysis pathway.

Animals↗
PubMed1991

Imaging of myocardial infarction in dogs and humans using monoclonal antibodies specific for human myosin heavy chains.

The use of three different monoclonal antibodies specific for human ventricular myosin heavy chains in the visualization of the location and extent of necrosis in dogs with experimental acute myocardial infarction and in humans is described. Using a classic immunohistochemical method or ex vivo analysis of heart slices in dogs with acute myocardial infarction subjected to intravenous injection of unlabeled antimyosin antibodies or antimyosin antibodies labeled with indium-111, it was observed that all antibody fragments specifically reached the targeted necrotic zone less than 2 h after antibody injection and remained bound for up to 24 h. In a limited but significant number of cases (5 of the 12 humans and 11 of 43 dogs), it was possible to image the necrotic zone in vivo as early as 2 to 4 h after antibody injection. In other cases, individual blood clearance variations retarded or even prevented in vivo necrosis detection. Higher antimyosin fixation values were obtained in the necrotic zones in dogs with a rapid blood clearance relative to that of the other dogs. It is concluded that antimyosin antibodies always reached necrotic areas within 2 h. If blood clearance was rapid, in vivo imaging of the necrotic area was possible 2 to 6 h after necrosis, even in humans. In some cases, however, uncontrolled individual variations in the timing required for sufficient blood clearance hampered this rapid in vivo detection of myocardial necrosis.

Aged↗
PubMed1991

Longitudinal study of solute excretion and glomerular ultrastructure in an experimental model of aging rats free of kidney disease.

Because experimental studies of kidney aging are frequently complicated by the presence of renal disease, we set out to define a model minimizing renal pathology and thus revealing basic aging phenomena. Male and female Wistar/Lou rats were conceived, born, and bred to 42 months in a specific pathogen-free husbandry. They had free access to water and to a protein diet containing 2% fish and 15% vegetable proteins. The mean survival ages of this colony were 39 months for females and 35 months for males. Body weight, 24-hour food and water intake, urinary volume, and solute excretion were measured every 6 months in a group of 12 males and 12 females. Throughout the study, the mean body weight remained close to 180 gm in females and 320 gm in males. Despite this size difference, absolute daily food intake was similar in the two sexes and almost constant over the studied period. Age-related changes in proteinuria and phosphate excretion were greater in males than in females. Decreased urine osmolality and increased urinary volume, on the other hand, were more pronounced in old females than in males. Renal loss of calcium was noticed in both sexes and glucosuria remained discrete. Kidneys examined at 12, 24, and 36 months in both sexes and also at 42 months in females were free of major pathology such as pronounced glomerulosclerosis, tubular nephrosis, tubular cast, or hydronephrosis. In the oldest animals a few foci of interstitial inflammation occasionally were seen. The sole significant morphologic change was a regular but moderate thickening of the glomerular basement membrane, which roughly doubled its size from 12 to 36 months. Morphometric studies failed to demonstrate an increase in mesangial matrix or mesangial cellularity. No changes in foot processes, slit diaphragms, or endothelial fenestrae were seen with increasing age. These observations indicate that basic age-related changes in kidney structure and function of rats fed ad libitum can be reduced to a few parameters provided that adequate strains, diet, and husbandry conditions are selected for experimentation.

Aging↗
PubMed1990

[First-choice orthopedic treatment in congenital hip dislocations discovered after walking age].

The incidence of late discovery of congenital dislocation of the hip is getting lower, thanks to systematic screening. We have treated 14 children during the past 5 years. Clinical diagnosis was confirmed by radiography. Thirteen children were treated by slow reduction, and immobilization according to Somerville-Petit's method. Four surgical treatments were performed (1 Klisic operation by first intention, 3 Salter operations by second intention). Good clinical results have not always correlated with radiologic normalization. These results were evaluated by Séverin's classification: 9 excellent or good (I or II), 4 poor results (III). Although improvement is expected in the future, repeated clinical and radiological supervision permits evaluation of the indications for a subsequent operation at the most favorable time.

Age Factors↗