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Biomedical subjects

N Moatti

Publications and source records attributed to N Moatti.

At least 19 recordsLinked to original sources
PubMed1992

Amino acid transport systems in the human hepatoma cell line Hep G2.

The human hepatoma cell line Hep G2 was used to investigate amino acid transport systems in human liver tissue. The ubiquitous transport systems responsible for the uptake of most neutral amino acids (systems A, ASC and L) were found to be present. Transport system A was predominant for proline uptake but system ASC was the major Na(+)-dependent transport system, particularly for glutamine. The specific hepatic system N was functional, but only partially mediated glutamine uptake. The study of Na(+)-independent arginine uptake demonstrated the presence of the cationic transport system Y+, reflecting the transformed nature of Hep G2 cells.

Alanine↗
PubMed1992

IL-1 beta, a strong mediator for glucose uptake by rheumatoid and non-rheumatoid cultured human synoviocytes.

Higher basal 2-deoxy-D-glucose uptake in rheumatoid synovial cells than in non-rheumatoid synovial cells, was found to be associated with an increased interleukin-1 beta (IL-1 beta) secretion (respectively 850 +/- 238 vs. 8.3 +/- 2.4 pg/24 h/10(5) cells, mean +/- S.E.M.). When exogenous human recombinant IL-1 beta was added to cultures, a marked stimulation of 2-deoxy-D-glucose uptake was performed by both human synovial cultured cells, in a time-dependent and dose-dependent manner (IL-1 beta 0-100 ng/ml). In non-rheumatoid synoviocytes, stimulation occurred 1-3 h following the addition of 1 ng/ml interleukin-1 beta and increased up to 24 hours (respectively +150% and +261.4% after 6 and 24 hours association time). Rheumatoid synovial cells were less sensitive to 1 ng/ml IL-1 beta (respectively +80% and +146.4%). IL-1 beta increased significantly the Vmax for 2-deoxy-D-glucose uptake by synovial cells, with no change in the Km. This effect was protein synthesis-dependent, and not secondary to prostaglandin E2 synthesis or cell growth. IL-1 beta possesses an important effect on glucose homeostasis in synovial cells, which could be indirect and/or regulated by the presence of natural inhibitors.

Arthritis, Rheumatoid↗
PubMed1992

Only prolidase I activity is present in human plasma.

1. After ion exchange chromatographic separation, liver prolidase exhibits two isoforms (prolidase I and II). 2. The activity of both was explored in human and rat tissues, and in normal and cytolytic human plasma. 3. The activity of prolidase I, eluted at the lowest ionic strength, was stimulated by 24 hr of preincubation with 1 mM MnCl2, but prolidase II activity was strongly inhibited by this long preincubation. In both normal and cytolytic human plasma, chromatographic separation also disclosed that only prolidase I activity was present. 4. This isoform displayed properties resembling those of liver and kidney prolidase I. 5. To explain the absence of prolidase II activity from the plasma, we tested the possibility that its tissue distribution differed. 6. However, this was not substantiated by the distribution found, or by the location, molecular weight and behavior of human liver prolidase II after neuraminidase treatment. 7. We also explored the hypothesis that plasma proteins inhibit prolidase II activity, and found that albumin almost abolished this activity after 6 hr incubation.

Animals↗
PubMed1992

Coronary calcification and its relation to extracoronary atherosclerosis in asymptomatic hypercholesterolemic men. The PCV METRA Group.

BACKGROUND: The prevalence of coronary calcifications and extracoronary plaques was studied in patients with asymptomatic hypercholesterolemia. METHODS AND RESULTS: Ultrafast computed tomography for coronary calcification (presence or absence: calcium score) and echographic assessment of carotid, aortic, and femoral plaques were performed in 111 hypercholesterolemic men: 65% had coronary calcification, 72% had extracoronary plaque. The two lesions were associated as: 1) compared with subjects without coronary calcification, those with calcification had a higher prevalence of aortic (p less than 0.05) and femoral (p less than 0.01) plaque and of two diseased sites (p less than 0.05); 2) the prevalence of coronary calcification was higher in the presence than in the absence of aortic (p less than 0.05) or femoral (p less than 0.01) plaque and higher in two (p less than 0.01) and three diseased (p less than 0.05) sites than in no diseased site; 3) the calcium score was higher in the presence than in the absence of carotid (p less than 0.05), aortic (p less than 0.05), or femoral (p less than 0.001) plaque, higher in two (p less than 0.001) and three diseased (p less than 0.05) sites than in no diseased sites, and higher in two (p less than 0.01) than in one diseased site; and 4) the calcium score correlated with femoral plaque (p less than 0.001). Overall, the presence of two or three diseased extracoronary sites versus no or one diseased site showed a power of 78% for predicting coronary calcification. Coronary calcium score correlated with age (p less than 0.01) and triglycerides (p less than 0.05). CONCLUSIONS: The close relation between coronary calcium and extracoronary plaques suggests that echography of extracoronary vessels could aid in the screening of coronary atherosclerosis in high-risk, asymptomatic individuals.

Adult↗
PubMed1992

[Modified LDL and atherosclerosis. Nature of modifications. Physicochemical and biological properties].

The role of plasma LDL in atherogenesis is now well established. Cholesteryl ester accumulation within macrophages leads to foam cell formation, an early atherosclerotic process. In vitro, foam cell formation scarcely ever occurs in the presence of native LDL. Modification of these lipoproteins is necessary for their binding to macrophage scavenger receptors. In vitro modifications reported have involved chemical reactions, physical mechanisms, enzymatic reactions, cellular interactions and association with macromolecules. In vivo, they can occur by glycation or desialylation, smoking or by hemodynamic interactions. Alterations of the physicochemical properties of LDL are induced by oxidation and include an increase in their density and their net electronegative charge, changes in lecithin composition, polyunsaturated fatty acid peroxidation of lipids and apolipoprotein B100 degradation. Apolipoprotein B100 fragmentation leads to an impairment of uptake through LDL receptors, while uptake through macrophage scavenger receptors is enhanced. Modified LDL have also other particularities such as cytotoxicity, chemotactism for circulating monocytes, inhibition of resident macrophage mobility, vasoconstriction, perturbation of the arachidonic acid cascade, involvement in haemostasis and immune mechanisms. Hypotheses concerning the role of modified LDL, in particular oxidized LDL, in atherogenesis open new therapeutic prospects.

Animals↗
PubMed1992

[Hypertension has no effect on coronary calcifications in asymptomatic patients with hypercholesterolemia].

Since calcium in coronary artery walls is considered as an indicator for atherosclerosis, we used ultrafast computed tomography to quantify it non invasively in 111 hypercholesterolemic men. They were selected at worksite by a cholesterol screening program, had total cholesterol (TC) above 5.2 (6.88 +/- 0.82, SD) mmol/l, were aged from 30 to 63 (46 +/- 5 years), had never been treated with lipid lowering or antihypertensive drug, and had no clinical coronary heart disease. Body mass index, blood pressure, smoking and other serum lipids as HDL cholesterol, triglyceride (TG) were evaluated. Calcium score of proximal coronary arteries was calculated on 30 contiguous 3 mm slices from areas and peak density of calcium lesions. The mean score was 30 +/- 69 and ranged from 0 to 440. A zero score was found in 39 subjects who differed from the 72 others only by TG levels (1.44 +/- 0.60 vs 1.85 +/- 0.80; p < 0.05). A multiple regression analysis showed that elevated calcium score was associated independently to age (F = 6.6; p < 0.05) and TG (F = 6; p < 0.05) but not to blood. Thus 65% of these asymptomatic subjects had a non-zero calcium score in coronary arteries. Elevated calcium score was influenced independently by age and triglyceride level, but not by other risk factors, such as blood pressure. This potential adverse effect of moderate triglyceride elevation on large coronary arteries merits attention in the assessment of the risk of coronary heart disease.

Adult↗
PubMed1991

Interleukin-1 beta-induced changes in the kinetic constants of L-proline uptake in human skin fibroblasts.

The effects of interleukin-1 beta (IL-1) on L-proline uptake in human skin fibroblasts were investigated. Exposure of the fibroblasts to IL-1 (5, 10 or 50 pg/ml) for 2 h did not change L-proline uptake. In contrast, inhibition was observed after 6 h of IL-1 treatment, and only 60% of the control uptake remained after incubation for 24 h with 10 pg of IL-1/ml. IL-1 depressed the activity of both transfer systems; the low-affinity system inhibited by alpha-(methylamino)isobutyric acid (Me-AIB), corresponding to system A, and a high-affinity transfer system which is unaffected by Me-AIB. The inhibitory effect increased as the L-proline concentration decreased. To determine whether IL-1-induced prostaglandin release influences proline uptake, indomethacin (14 microM) was added as a cyclo-oxygenase inhibitor. Indomethacin itself decreased L-proline uptake but to a lesser extent than did IL-1. When IL-1 was tested in the presence of indomethacin, the inhibition of L-proline uptake was still observed, with values between those obtained with each substance in isolation. This suggests that the inhibitory effect of IL-1 on proline uptake by skin fibroblast does not only involve the prostaglandins that accumulate in the medium, but no firm conclusion can be drawn, due to the fact that the inhibition by the two agents was not statistically independent. Kinetic analyses for 1 min combined with inhibition experiments showed that IL-1 induced a decrease in the Km and Vmax, values of the high-affinity transport system, whereas it increased the Km of system A. Therefore the two systems of proline uptake in skin fibroblasts are probably inhibited by IL-1 via different mechanisms.

Biological Transport↗
PubMed1991

Respective effects of glucose and glutamine on the glutamine synthetase activity of human skin fibroblasts.

The activity of Glutamine Synthetase (GS) was measured during the growth of human diploid skin fibroblasts cultured for three weeks in the presence or absence of either glucose or glutamine or both. In medium free of both glucose and glutamine, a single late peak in GS activity was observed concomitantly with delayed small cell protein increment. In all media containing either glucose or glutamine or both. GS activity rose sharply during rapid cell growth, displayed a plateau, and then decreased once the cells had reached confluency. The variations in extracellular amino acid levels were also determined and were found to depend on the composition of the medium but not on the cell culture duration. These results demonstrate, for the first time as far as we know, that strong GS activity is present in rapidly growing skin fibroblasts. In contrast to many other mammalian cell types, GS activity in human skin fibroblasts appears not to be subject to regulation by extracellular glutamine. This difference may well be connected with cell differentiation.

Amino Acids↗
PubMed1991

Biochemical diagnosis of hepatic glycogen storage diseases: 20 years French experience.

French experience of 242 cases of liver glycogenoses is reported. Screening tests based on serum biochemical data and glucagon tolerance tests are briefly reviewed. The diagnosis of types I glycogen storage disease (GSD) was ascertained in 73 patients' liver biopsies by measurement of glycogen content and by studying the glucose-6-phosphatase system. Liver biopsies were also required at the beginning for the diagnosis of other hepatic GSDs; later on, the possibilities of diagnosis using peripheral blood cells were investigated. Eighty-four cases of type III GSD were confirmed by measurement of debranching enzyme activity and glycogen content using either liver biopsies (78 cases) and/or erythrocytes (37 cases); enzyme determination was also performed in leukocytes and/or fibroblasts for 18 patients. Twenty-four cases of type VI GSD underwent liver biopsies, and the diagnosis could be confirmed using mononuclear or polymorphonuclear cells for 11 of these patients. Sixty-one patients were identified as type IX GSD; phosphorylase kinase deficiency was demonstrated in erythrocytes for all patients, and a liver biopsy was analyzed for 26 of these cases. From this experience, the possibilities of diagnosis of liver GSD using peripheral blood cells are emphasized.

Blood Chemical Analysis↗
PubMed1991

Influence of uremia on polymorphonuclear leukocytes oxidative metabolism in end-stage renal disease and dialyzed patients.

The oxygen (O2) consumption, and superoxide anion (O2-.) and hydrogen peroxide (H2O2) production by polymorphonuclear leukocytes (PMNs) were investigated in 5 end-stage renal disease patients, before and after the 1st, 4th and 10th dialysis sessions. Resting values of O2-. production and O2 consumption were not significantly different from values for PMNs from normal subjects. After stimulation by opsonized zymosan or phorbol myristate acetate, the three parameters measured were significantly (p less than 0.001) enhanced in comparison with healthy control values. Cross-incubation studies showed a lack of effect of patient plasma on O2-. production by stimulated control cells: PMN oxidative metabolism would therefore appear to be increased in these patients. The anomalies observed probably arise via a mechanism involving a cellular dysfunction resulting from the renal disease, rather than from the presence of a plasma factor.

Adult↗
PubMed1991

[In vitro activity of twenty antibiotics against Rhodococcus equi].

The in vitro susceptibility of nine Rhodococcus equi strains (seven isolates from immunocompromised patients mainly HIV positive and two reference strains) to twenty various antibiotics were assessed for bacteriostatic effects by an agar dilution method. Imipenem and ceftriaxone were the most effective of the beta-lactams studied. The lowest MIC were noted with vancomycin, teicoplanin, erythromycin, clarithromycin, rifampicin, gentamicin and doxycycline. A longitudinal survey, including three strains isolated from the same patient, showed the emergence of rifampicin resistance and a marked increase of the MIC to imipenem.

Actinomycetales Infections↗
PubMed1991

Fractionation of charge-modified low density lipoproteins by fast protein liquid chromatography.

We describe a methodology developed to separate different forms of charge-modified low density lipoproteins (LDL) using the fast protein liquid chromatography (FPLC) system from Pharmacia. Lipoproteins were isolated by sequential ultracentrifugation and introduced onto an anion-exchange column (Mono Q HR 5/5). The multistep NaCl gradient elution was optimized and the analytical variables were determined on copper-oxidized LDL. After oxidation by copper for various times (up to 48 h), five forms were obtained (fractions A, B, C, D, and E). Within-run and day-to-day reproducibility were better than 8.6% and 10%, respectively. Protein and cholesterol recovery after the chromatographic separation was good (greater than 82%) and the detection limit was about 1 microgram. The more negative forms of collected LDL were mainly characterized by an increase in the lipid peroxidation product content, a depletion of vitamin E, an alteration of apoB and increased degradation by macrophages. The proposed methodology was applied to the study of LDL modifications generated by human umbilical endothelial cells and the protective effect of antioxidants (vitamin E and probucol).

Antioxidants↗
PubMed1991

Monoclonal and oligoclonal gammopathies in heart-transplant recipients.

Immunoglobulin abnormalities in serum from 76 heart-transplant recipients were examined by cellulose acetate and agarose gel electrophoresis. Monoclonal components were typed by immunofixation. IgG, IgA, and IgM and total kappa and lambda light chains were quantified by immunonephelometry. We confirm that both monoclonal and oligoclonal immunoglobulin banding are common in serum from these patients. Of the 149 serum samples examined, 21 (15%) had one monoclonal component and 53 (35%) had two or more. These monoclonal immunoglobulins were generally present at a low concentration and were transient. The class of immunoglobulins most commonly involved was IgG (about sevenfold more numerous than IgM); monoclonal IgA components and free light chains were not detected. The nephelometric kappa/lambda and heavy chain/light chain ratios were poor indicators of these abnormalities. Immunoglobulin abnormalities were not correlated with the sex and age of recipients, the pre-existing cardiopathy, the time since transplantation, or plasma concentrations of cyclosporine, but did correlate with plasma immunoglobulin concentration, biopsy findings, and viral infections, especially cytomegalovirus (CMV). A monoclonal IgG purified from a patient with a high titer of anti-CMV antibodies did not react with CMV antigens. The origin of these immunoglobulin abnormalities is unclear. Our data suggest that the presence of monoclonal or oligoclonal banding in heart-transplant recipients is of limited prognostic significance.

Adult↗
PubMed1991

[Membrane phospholipid peroxidation in renal insufficiency and chronic hemodialysis].

Lipid peroxidation is a result of the fatty acid side-chains of cellular membrane phospholipids attack by oxygen-derived free radicals. It has been suggested that some of the complications related to haemodialysis may be due to ineffective antioxidant systems and/or an increased free oxygen radical production. Serum antioxidant activity in patients undergoing regular dialysis treatment has been shown to be significantly decreased and to exhibit high malondialdehyde levels indicating that the patients were susceptible to cellular injury by lipid peroxidation. Superoxide dismutase and glutathion peroxidase activities are decreased in plasma and erythrocytes. Moreover, in uremia, blood cell and mononuclear cell membranes contents of vitamin E are reduced. Thus, chronic uremic patients seem to have defective plasma and cellular antioxidant mechanisms together with an increase of circulating free radical reaction products.

Antioxidants↗
PubMed1990

Serum lipid abnormalities in heart transplant recipients: predominance of HDL2-like particles in the HDL pattern.

Accelerated coronary atherosclerosis is a major risk limiting long-term survival after heart transplantation and is commonly associated with dyslipoproteinemia even in subjects who were not dyslipoproteinemic before intervention. The purpose of this study was to analyse the abnormalities in the lipid profiles of 2 different groups of heart-transplanted males: 18 subjects with underlying ischemic heart disease (IHD) and 19 subjects with non-obstructive cardiomyopathy of unknown aetiology (CM). Both groups were compared to 33 healthy males. All patients were under immunosuppressive therapy including prednisone, cyclosporin A and azathioprine. A moderate hyperlipidemia was found in all transplant recipients, associated with high HDL-cholesterol concentrations in the CM group (1.80 +/- 0.37 vs. 1.29 +/- 0.23 mmol/l) and normal HDL-cholesterol levels in the IHD group (1.40 +/- 0.23 mmol/l). HDL subfractionation showed a marked increase in HDL2-cholesterol (CM: 1.12 +/- 0.32; IHD: 0.69 +/- 0.28; control: 0.40 +/- 0.17 mmol/l) while HDL3-cholesterol was significantly lower than in the control group. Analysis of HDL particle sizes showed in all transplant subjects an increase of an intermediate size particle HDL2a (diameter 9.0 +/- 0.10 nm) which is a minor form in control subjects. In the CM group, both the common HDL2b (10.2 +/- 0.13 nm) and HDL2a were abundant in 13 of 17 patients. The pattern was more heterogeneous in the IHD group but witnessed to a high frequency of HDL2a particles either alone (5/14) or associated with larger HDL2b (4/14) or with small HDL3 (4/14).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomyopathies↗
PubMed1990

[Evaluation of 2 bacterial filters connected to the respirator for the prevention of nosocomial pulmonary infection].

Among 37 patients that are admitted for a more than 3 days breathing reanimation, 19 are ventilated with bacterial filter Pall BB 22 15 and 18 with Darex Hygrobac, exchanged every days and connected to the Y piece. In this study, 6 patients are ventilated with a humidifier (pilot population). For these 43 patients, 130 protected swabs were made with the RCS Biotest placed on the expired gaz. The day of the taking off the expiratory tube was rinsed with 100 ml of aseptic water which are strained on the membrane. The two filters give very good and comparable bacteriological results. The filters prevents nosocomial pulmonary infections making a bacterial frontier between the patient and the respirator and reducing aerial contamination from one patient to another.

Air Microbiology↗