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M Maurice

Publications and source records attributed to M Maurice.

At least 55 records · Page 3Linked to original sources
PubMed1990

Presence of functional cytochrome P-450 on isolated rat hepatocyte plasma membrane.

Antibodies against cytochrome P-450 are found in some children with autoimmune hepatitis (antiliver/kidney microsome 1) and in patients with ticrynafen hepatitis (antiliver/kidney microsome 2). For an immune reaction against cytochrome P-450 to possibly destroy the hepatocytes, one must assume that cytochrome P-450 is present on the plasma membrane surface of hepatocytes. In a first series of experiments, plasma membranes were prepared with a technique based on the electrostatic attachment of isolated hepatocytes to polyethyleneimine-coated beads. After vortexing, beads were coated with a very pure plasma membrane fraction. Microsomal contamination, judged from the specific activities of glucose-6-phosphatase or NADH-cytochrome c reductase, was less than 1%. Nevertheless, the specific content (per milligram of protein) of CO-binding cytochrome P-450 was 20% of that in microsomes; the specific benzo(a)pyrene hydroxylase activity was 25%, and ethoxycoumarin deethylase 11%. Immunoblots showed the presence of cytochromes P-450 UT-A, UT-H, PB-B, ISF-G and PCN-E, the last three isoenzymes being inducible by, respectively, phenobarbital, 3-methylcholanthrene and dexamethasone. In a second series of experiments, nonpermeabilized isolated hepatocytes from untreated rats were incubated with anticytochrome P-450 antibodies. Immunofluorescence and immunoperoxidase staining confirmed the presence of cytochromes P-450 UT-A, PB-B and ISF-G on the membrane. In a last series of experiments, human antiliver-kidney microsomal 1 antibodies were found to react specifically with rat liver plasma membrane cytochrome P-450 UT-H (IID subfamily). We conclude that several cytochrome P-450 isoenzymes are present, active and inducible on the plasma membrane surface of hepatocytes. It is therefore conceivable that immunization against plasma membrane cytochrome P-450 might lead to the immunological destruction of hepatocytes in some patients.

Animals↗
PubMed1990

Detection of a biliary cell membrane glycoprotein in the serum of cholangiocarcinoma-bearing rats. Possible relevance to the membrane proteins used as serum tumor markers in humans.

Certain markers used in the diagnosis and monitoring of human adenocarcinomas, such as carcinoembryonic antigen are membrane glycoproteins normally absent from the serum. How those proteins may reach the blood after the neoplastic transformation remains debated. In this work, we show that cholangiocarcinoma induced by 3'-methyl-4-dimethylaminoazobenzene in the rat provides some insight into the mechanisms implicated in this process. We observed that the extracellular matrix of all cholangiocarcinomas tested contained large amounts of a glycoprotein identified by a monoclonal antibody termed B10, and previously characterized as an integral membrane protein normally restricted to the apical domain of epithelial cell plasma membrane. The extracellular deposition of the B10-binding glycoprotein in cholangiocarcinomas was associated with the appearance of detectable levels of the protein in the serum, and an abnormal membrane expression of the protein, which was detected on both apical and basal plasma membrane domains of neoplastic biliary cells. We postulate that neoplastic transformation of biliary cells leads to an inappropriate membrane expression of the B10-binding protein, which in turn, results in the extracellular release of the protein and in its diffusion into the blood. The characteristic desmoplastic stroma of cholangiocarcinoma offers the opportunity to easily visualize the release process. A comparable mechanism is likely to explain how certain membrane glycoproteins used as serum markers in human malignancy may reach the blood.

Adenoma, Bile Duct↗
PubMed1989

Permeability of the rat biliary tree to ursodeoxycholic acid.

The permeability of the biliary epithelium to [14C]ursodeoxycholic acid (UDCA), a hypercholeretic bile acid, was compared to that of the 14C-labeled nonhypercholeretic bile acids cholic acid (CA), taurocholic acid (TCA), and tauroursodeoxycholic acid (TUDCA) by means of anterograde intrabiliary infusions and retrograde intrabiliary injections in the anesthetized rat. Anterograde intrabiliary infusions were performed by perfusing an isolated segment of common bile duct in vivo. After anterograde intrabiliary infusions, the fraction of unrecovered UDCA (that had presumably been absorbed from the biliary lumen) was 11.03 +/- 1.03 (SE)% (n = 6) of the administered dose. It was significantly higher than that of TUDCA (1.25 +/- 0.27%; n = 5; P less than 0.01), CA (2.62 +/- 0.43%; n = 4; P less than 0.01), and TCA (2.57 +/- 0.79%; n = 6; P less than 0.01). In separate experiments, bile was collected from the common bile duct and from the left hepatic duct. UDCA recovered from the left hepatic duct was found in the conjugated form, indicating that, after absorption in the common bile duct, it had been conjugated by the hepatocyte and secreted into bile. After retrograde intrabiliary injections of UDCA and CA, the cumulative percentages of recovered radioactivity were not significantly different (84.50 +/- 2.65 and 87.33 +/- 1.80%, respectively); however, peak recovery of UDCA was significantly delayed compared with that of CA. Moreover, UDCA was recovered mostly in the conjugated form, while CA was recovered mostly in the unconjugated form. These results suggest that, in the rat, UDCA is significantly more absorbed by the biliary tree than CA, TUDCA, and TCA. They support the hypothesis that UDCA undergoes a cholehepatic circulation.

Absorption↗
PubMed1989

Expression of rat hepatocyte plasma membrane antigens in hybrid clones: assignment of genes coding for two antigens of the basolateral domain to chromosomes 11 and 13.

Expression of three rat hepatocyte plasma membrane antigens defined by monoclonal antibodies (mAbs) was examined by immunofluorescence in mouse hepatoma x rat hepatocyte hybrid clones segregating rat chromosomes. The antigen defined by mAb B1, a marker of the lateral domain of the hepatocyte plasma membrane in vivo, was expressed in hybrids retaining the rat chromosome 11. The antigen defined by mAb A39, mainly located on the sinusoidal (basal) domain of the plasma membrane in vivo, was expressed when chromosome 13 was present. The genes coding for these two antigens were thus assigned to chromosomes 11 and 13, respectively. The antigen defined by mAb B10, exclusively located on the canalicular (apical) domain of the plasma membrane in vivo, was not expressed in most hybrid clones, and the chromosome location of the gene could not be determined.

Animals↗
PubMed1988

Analysis of hepatocyte plasma membrane polarity during rat azo dye hepatocarcinogenesis using monoclonal antibodies directed against domain-associated antigens.

While carcinogenesis is known to induce various alterations in epithelial cell polarity, little information is available about the fate of plasma membrane polarity during the neoplastic process. Using three monoclonal antibody-defined antigens as markers of the three plasma membrane domains of rat hepatocytes, the sinusoidal, the lateral, and the canalicular, we demonstrated by immunohistochemical techniques that changes in hepatocyte plasma membrane polarity occur at every stage of 3'-methyldimethylaminoazobenzene-induced hepatocarcinogenesis. At the preneoplastic stage, the division of hepatocyte plasma membrane into three distinct domains was retained despite rearrangements in hepatocytic architecture, characterized by the disorganization of hepatocytic plates and the formation of pseudoacinar structures. The most striking change was the distribution of the canalicular-associated antigen over the entire plasma membrane in disorganized plates. At the neoplastic stage, changes in plasma membrane polarity depended on the degree of morphological differentiation of neoplastic cells. Poorly differentiated cells inconstantly expressed the monoclonal antibody-defined antigens and showed no evidence of plasma membrane polarization. Differentiated cells constantly expressed the three antigens, and their plasma membrane was divided into antigenically distinct domains. The changes in hepatocyte plasma membrane polarity demonstrated in situ during 3'-methyldimethylaminoazobenzene hepatocarcinogenesis may therefore be compared with situations known to occur in vitro, in cultured epithelial cells presenting varying degrees of polarization. Our observations suggest that these alterations are of relevance to the in vivo biology of cancer.

Animals↗
PubMed1988

Analysis of hepatocyte plasma membrane domains during rat development using monoclonal antibodies.

The plasma membrane of adult rat hepatocyte consists of three domains, which have been identified by the monoclonal antibodies A39 and A59 as markers of the sinusoidal domain, B1 of the lateral, and B10 of the canalicular domains (Eur J Cell Biol 39:122, 1985). These monoclonal antibodies were used to study, by indirect immunocytochemistry, formation of the hepatocyte plasma membrane domains during development, from day 15 of gestation to day 35 post partum. The antigens defined by A39, B1, and B10 were detected, from day 15, over the major part of the hepatocyte plasma membrane except for the membranes of newly formed bile canaliculi, which were not labeled by B1 and only poorly labeled, if at all, by A39 and B10. As soon as fetuses were 16 days old, B1 labeled predominantly the lateral domain, as in the adult. Labeling with B10 progressively intensified on the membranes of bile canaliculi, but localization was not exclusively canalicular until day 21 post partum. A39 intensely labeled the canalicular membranes at 19-21 days of gestation, while at 35 days post partum it exhibited the predominantly sinusoidal labeling observed in adult hepatocytes. The antigen defined by A59 was not detected before birth and was found exclusively on the sinusoidal domain, as in the adult. These results show that the patterns of antigen distribution on different plasma membrane domains establish themselves at different rates. The marked differences observed between fetal or neonatal and adult hepatocytes might be responsible for immaturity of liver functions in the neonate.

Animals↗
PubMed1988

Formation of plasma membrane domains in rat hepatocytes and hepatoma cell lines in culture.

In vivo, proteins of the hepatocyte plasma membrane are asymmetrically distributed, making it possible to distinguish a sinusoidal, a lateral and a canalicular domain. The conditions that determine hepatocyte plasma membrane polarity have been investigated in vitro, using three monoclonal antibodies directed against integral membrane proteins, which were characteristic of each domain. The localization of the three antigens was studied by immunolabelling of hepatocytes isolated from adult rat liver, primary monolayer cultures and rat hepatoma cell lines. When hepatocytes were isolated, the three antigens spread over the entire cell surface. The lateral antigen redistributed at lateral sites as soon as cell-cell contacts were established, 4 h after the beginning of primary culture. The sinusoidal and canalicular antigens became asymmetrically distributed after 48 h of primary culture, after the formation of bile canaliculus-like structures. In most of the hepatoma lines studied, the three antigens were expressed, except that the canalicular antigen was fully expressed in differentiated clones only. The lateral antigen was always distributed on the contiguous membranes of clustered hepatoma cells, whereas the sinusoidal and canalicular antigens were localized on the entire plasma membrane. However, in a few cells of some clones in which bile canaliculus-like structures were observed, the canalicular membranes were strongly labelled only with the canalicular antibody. In the absence of bile canalicular formations, in both primary culture and cell lines, the canalicular antigen and, to a lesser extent, the sinusoidal antigen accumulated in the Golgi apparatus, suggesting that their transport to the cell surface was altered in the absence of a bile pole. These results show that in hepatic cells, polarization of the plasma membrane is determined by: (1) the existence of cell-cell contacts, which is correlated with the domain-specific localization of the lateral antigen; and (2) the formation of bile canaliculi, which would trigger the development of an asymmetrical distribution of the sinusoidal and canalicular antigens.

Animals↗
PubMed1988

[NMR spectrometry in vivo with a resistive magnet at 1,2 T].

A resistive magnet, operating at 1.2 T, intended to magnetic resonance spectroscopy in man was set up and evaluated in the hospital of Chamonix. Drusch S.A. in collaboration with Institut d' Electronique fondamentale built the system with the following characteristics: weight: 12 t, pole diameter: 55 cm, distance between coils: 36 cm. Cooling the magnet was provided by water flowing at 50 l/min. The magnetic field homogeneity was 3 X 10(-7) in a 60 mm diameter sphere. Stability was regulated at +/- 1 mGs. Five correcting circuits were used (X, Y, Z, Z2, XY). For experiments in man useful window was 120 X 20 cm and allowed measurements in brain and limbs. With this type of magnet, 1H, 31P and 23Na NMR spectra equalled in quality those obtained with superconducting magnets which work at a very higher cost.

Electromagnetic Fields↗
PubMed1987

Aetiology of recurrent aphthous ulcers (RAU).

A significant decrease in the pH of saliva has been detected in patients with recurrent aphthous ulcers (RAU). The decrease in pH was more prominent at night than between meals, and some persistent decrease was noticed even after recovery. The total proteins of saliva in RAU were also significantly decreased. These findings were similar to those observed in patients complaining of peptic ulcers, so it is recommended that patients with RAU should be treated with antacids as well as anticholinergic drugs, and that the possibility of concomitant peptic ulceration should also be investigated.

Humans↗
PubMed1986

Influence of diets with different levels of protein and energy on liver albumin content in the rat.

The influence of protein ingestion on liver albumin synthesis and albumin content was investigated in rats fed protein as a meal (90% casein) given apart from the other dietary components provided ad libitum. In this condition, protein ingestion rapidly stimulates liver total protein synthesis. Separately fed rats were studied 6 and 20 h after the protein meal. Control rats fed mixed diets containing 13 or 80% casein were killed either during the absorptive (night) or postabsorptive (light) periods. The ratio of hepatic albumin synthesis to total protein synthesis remained fairly constant (12-15%) in all groups, indicating that albumin synthesis paralleled total protein synthesis. Liver albumin content measured in microsomes by immunonephelometry was significantly higher in separately fed rats killed 6 h postmeal than in those killed after 20 h. In rats fed 13% casein, the liver albumin content remained high regardless of the time of killing. In rats fed 80% casein, the albumin content was higher during the absorptive period than during the postabsorptive period. Immunoperoxidase staining of the hepatocyte organelles involved in albumin synthesis, especially the Golgi apparatus, was more intense for separately fed rats killed 6 h postmeal than for those killed after 20 h. Livers of rats fed 13% casein also exhibited a pattern indicative of high hepatocyte albumin content, whereas livers of rats fed 80% casein contained less. These results show that, in separate feeding, wide circadian variations of albumin synthesis run parallel to changes in liver albumin content.

Albumins↗
PubMed1985

Ammonium chloride, methylamine and chloroquine reversibly inhibit antibody secretion by plasma cells.

The effects of the lysosomotropic weak bases, NH4Cl, methylamine and chloroquine, on the secretory process of antibody-synthesizing cells were studied. Popliteal lymph node cells taken from rats immunized against horseradish peroxidase (HRP) were incubated with the lysosomotropic agents. The rate of secretion of anti-HRP antibodies was measured using an indirect enzyme-linked immunosorbent assay. These agents induced an inhibition of antibody release within 5 min, and for all four concentrations tested, maximal inhibition was reached after 15 min. A 50% inhibition was obtained with 20 mM NH4Cl, 21.7 mM methylamine and 8.8 X 10(-4) M chloroquine. This effect was rapidly and entirely reversible, regardless of the weak base used, and it increased as the pH of the extracellular media was raised. Under these conditions, intracellular ATP contents remained normal, and protein synthesis did not undergo marked changes except with chloroquine. Inhibition of secretion was accompanied by an intracellular accumulation of antibodies which was equal to the degree of inhibition of antibody release. Immunocytochemical studies of the weak base-treated cells performed by light and electron microscopy showed that this accumulation probably occurred within certain dilated Golgi saccules. In addition, reduced incorporation of fucose into immunoglobulins as well as partial inhibition of the secretion of fucosylated immunoglobulins were observed in the presence of weak bases. These results are consistent with the hypothesis that weak bases inhibit antibody secretion by acting within saccules of the Golgi apparatus. These saccules could maintain an acidic pH important for the migration and/or sorting of immunoglobulins.

Adenosine Triphosphate↗
PubMed1985

Characterization of rat hepatocyte plasma membrane domains by monoclonal antibodies.

The hepatocyte plasma membrane consists of three morphologically and functionally distinct domains, the sinusoidal, the lateral and the canalicular. To study the distribution of antigenic determinants among these domains, we prepared monoclonal antibodies by immunizing mice with a crude, plasma membrane-enriched liver fraction. Four monoclonal antibodies were obtained that recognized various parts of the rat hepatocyte plasma membrane when tested by indirect immunofluorescence and immunoperoxidase assay performed on formaldehyde-fixed liver tissue. Each antibody gave a different staining pattern when analyzed by light and electron microscopy. A59 exclusively labelled the part of the sinusoidal membrane facing the sinusoids. A39 mainly labelled the sinusoidal membrane. B1 mainly labelled the lateral membrane, while the labelling by B10 was almost completely limited to the canalicular membrane. Immunoblotting showed that the antibody B1 recognized an antigen of approximately 100 kilodaltons and that B10 recognized an antigen of approximately 125 to 130 kilodaltons. These antibodies allow us to distinguish the three domains of the hepatocyte plasma membrane.

Animals↗
PubMed1985

[Intravenous labetalol in normotensive coronary patients. Effects on hemodynamics and myocardial metabolism].

The haemodynamic and myocardial metabolic effects of intravenous Labetalol were studied in 7 normotensive coronary patients with at least one significant stenosis on the left anterior descending artery. The study consisted of 5 successive observation periods: basal (I); during atrial pacing at the theoretical maximal heart rate or when anginal pain occurred (II); return to basal conditions (III); 20 minutes after an injection of 1.5 mg/kg of Labetalol over 3 minutes into the pulmonary artery (IV); during repeat atrial pacing at the rate achieved during phase II (V). There was no significant difference between phases I and III except for a slightly faster heart rate in phase III. The effects of Labetalol were assessed by comparing the results during phases III and IV between phases II and V and by analysing the variations between phases I, II, IV and V. In comparison with basal conditions (phase III), Labetalol (phase IV) induced a slight decrease in cardiac output (p less than 0.05), a decrease in aortic pressure and systemic arterial resistances (p less than 0.01) and of the double product. Coronary sinus flow did not change but myocardial oxygen consumption fell by an average of 11% (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Cytoskeleton ultrastructure of podocytes and glomerular endothelial cells in man and in the rat.

The ultrastructural organization of the cytoskeleton of normal podocytes and glomerular endothelial cells was studied in man (adults and children) and in adult Sprague-Dawley rats. In podocytes of both species, cytoplasmic microtubules (MT) were observed in the cell body close to the Golgi apparatus and along the main axis of the major processes where they formed bundles. A network of intermediate filaments (IF) was observed in the cell body and in the major processes where they sometimes formed bundles parallel to MT, especially in man. Numerous clustered microfilaments (MF) were noticed in the foot processes close to the plasma membrane. In glomerular endothelial cells from both species, networks of MT and IF were observed in the cell body, whereas MF surrounded the endothelial fenestrations. The high degree of organization of the cytoskeleton suggests that it may play an important role in several functions of both cell types.

Animals↗
PubMed1983

Comparison between conjugate and non-conjugate immunoperoxidase procedures with special reference to intracellular penetration. Application to albumin localization in rat hepatocytes.

Three immunoenzymatic methods, peroxidase-labelled antibody, peroxidase-labelled immunoglobulin Fab fragment and unlabelled antibody peroxidase-antiperoxidase methods were compared for albumin localization in rat hepatocytes. On liver cryostat sections observed with light microscopy, the peroxidase-antiperoxidase method was the most sensitive, since albumin was detectable at high dilutions of the primary layer antiserum. Penetration of the conjugated and non-conjugated antibodies into liver tissue was evaluated by electron microscope examination of ultrathin transverse sections cut from cryostat sections. The best penetration and staining of hepatocellular organelles were obtained with peroxidase-labelled Fab fragments.

Albumins↗