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Biomedical subjects

M Denis

Publications and source records attributed to M Denis.

At least 199 records · Page 11Linked to original sources
PubMed1989

Anaerobic biodegradation of hydrocarbons.

The anaerobic biodegradation of hydrocarbons has long been a subject of controversy but enough data have now been accumulated to support the view that hydrocarbons can be metabolized in the natural environment in the absence of molecular oxygen. For a limited number of molecules, anaerobic hydrocarbon metabolism has been demonstrated under fermentative or denitrifying conditions with samples collected from several different biotopes. However, the micro-organisms responsible for anaerobic metabolism generally still need to be isolated and identified and the biochemical mechanisms of the strictly anaerobic strains which carry out hydrocarbon metabolism are still unknown. Despite this restricted knowledge, the improvement in sampling techniques and in experimental methods is now sufficient to confirm the existence of anaerobic hydrocarbon biodegradation. The importance of such metabolism should stimulate research in this field.

Bacteria, Anaerobic↗
PubMed1988

Interaction of the Mr = 90,000 heat shock protein with the steroid-binding domain of the glucocorticoid receptor.

We have investigated the physiochemical characteristics of trypsin-treated, molybdate-stabilized glucocorticoid-receptor complexes from rat liver in the presence of 10 mM sodium molybdate by high performance ion-exchange chromatography, high performance size-exclusion chromatography, and sedimentation analysis. Trypsin treatment was performed under conditions previously reported to degrade the monomeric Mr approximately 94,000 steroid-binding protein to an Mr approximately 27,000 ligand-binding entity (Wrange, O., and Gustafsson, J.-A. (1978) J. Biol. Chem. 253, 856-865). Also in the presence of molybdate, an Mr approximately 27,000 steroid-binding fragment was obtained by limited trypsinization. However, no major differences in the tested physicochemical parameters were seen when trypsin-treated glucocorticoid-receptor complexes were compared with crude cytosolic complexes. Furthermore, the Mr approximately 27,000 steroid-binding fragment generated in the presence of molybdate could be immunoprecipitated by antibodies specific for the glucocorticoid receptor-associated Mr approximately 90,000 heat shock protein. These results provide direct evidence for an interaction of the Mr approximately 90,000 heat shock protein with the steroid-binding domain of the glucocorticoid receptor, known to correspond to the C-terminal third of the receptor protein.

Adrenalectomy↗
PubMed1988

Pleiotropic effects of the Bcg gene. II. Genetic restriction of responses to mitogens and allogeneic targets.

The response of Bcgr and Bcgs spleen cells to allogeneic Ag, mitogens, and in a system of oxidative mitogenesis using neuraminidase and galactose oxidase was investigated in two Bcg congenic systems. The Bcgr macrophages supported the MLR across H-2 barrier much better than the Bcgs macrophages. At sub-optimal or optimal doses of mitogens Bcgr mice were higher responders than their Bcgs counterparts. The superior response of Bcgr spleen cells to Con A was further investigated with the aim of identifying the population expressing this phenotype. T cells of either Bcgr or Bcgs type showed equal ability to respond to Con A in the presence of macrophages. Purified splenic macrophages from Bcgr mice contained a significantly greater percentage of Ia+-bearing macrophages compared to Bcgs mice. Splenic macrophages of the Bcgr type were more efficient than their Bcgs counterparts at restoring the Con A response of accessory cell-depleted spleen cells. Resident peritoneal macrophages as well as splenic dendritic cells from Bcgr and Bcgs mice were equally efficient at restoring this response. Glutaraldehyde-fixed Bcgr splenic macrophages were shown to be more efficient than the Bcgs cells at replenishing the response of Con A-unresponsive spleen cells when supplemented with IL-1.

Animals↗
PubMed1988

Association of the dioxin receptor with the Mr 90,000 heat shock protein: a structural kinship with the glucocorticoid receptor.

The Mr approximately equal to 90,000 heat shock protein, hsp90, readily interacts with the glucocorticoid receptor to form the 9 S, non-DNA-binding receptor complex. This receptor is stabilized in cytosolic preparations by sodium molybdate. In analogy, sodium molybdate stabilizes a 9 S form of the dioxin receptor. Polyclonal antibodies raised against the purified glucocorticoid receptor-associated hsp90 interact with the molybdate-stabilized 9 S dioxin-receptor complex but not with the 4 S dioxin receptor monomer, as assessed by sedimentation shift analysis on sucrose gradients. Thus we conclude that both the dioxin and glucocorticoid receptor can form heteromeric complexes which share a common non-ligand-binding component. These results represent the first demonstration of a structural relationship between the dioxin and glucocorticoid receptors.

Animals↗
PubMed1988

Requirement of hormone for thermal conversion of the glucocorticoid receptor to a DNA-binding state.

A central question arising from the model of eukaryotic gene regulation by steroid hormone receptors is whether or not proteins represent pre-existing gene regulatory proteins that are activated on exposure to the extracellular signal. It has been generally believed that the ligand-binding of steroid hormone receptors triggers an allosteric change in receptor structure, manifested by an increased affinity of the receptor for DNA in vitro and nuclear target elements in vivo, as monitored by nuclear translocation. But this model has been challenged by recent reports indicating that glucocorticoid and progesterone receptors bind specifically in vitro to target DNA sequences even in the absence of hormone. On the other hand, it appears that the hormone induces protection in vivo of the glucocorticoid response element of the tyrosine amino transferase gene. Here we show that under conditions permitting minimal in vitro manipulation, the steroid-free glucocorticoid receptor in crude cytosol associates with the hsp90 heat shock protein (relative molecular mass Mr approximately equal to 90,000) to form a large 300K complex, rather than the 94K liganded receptor monomer. More importantly, we have developed an assay to demonstrate the requirement of hormone to dissociate the 300K complex by heat treatment. Specific DNA-binding activity of the receptor becomes apparent in this process, showing that DNA binding occurs but is inhibited in the large heteromeric complex. We propose a model in which receptor function is repressed by association of the receptor with hsp90. Dissociation of this complex is induced by the binding of steroid and is apparently an irreversible process.

Adrenalectomy↗
PubMed1988

[Respective frequency and radioclinical features of 150 lung diseases observed in 125 patients with human immunodeficiency virus infection].

Seventy out of 125 patients with HIV infection had diffuse alveolo-interstitial pneumonia usually caused by an opportunistic infection, notably pneumocystosis. Nineteen patients had only localized lung opacities due either to usual or tuberculous bacterial infections or to Kaposi's sarcoma. In 10 patients with pleural effusion or mediastinal adenopathy, the condition was due to Kaposi's sarcoma (n = 4) or to mycobacteriosis (n = 3). An opportunistic or usual infection was demonstrated in 17 of the 51 patients with normal radiography of the chest. Finally, 37 patients free from infectious or tumoral pathology had isolated lymphocytic alveolitis.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Pleiotropic effects of the Bcg gene. I. Antigen presentation in genetically susceptible and resistant congenic mouse strains.

The Ag-presentation ability of Bcgr and Bcgs spleen cells was studied in two sets of Bcg-congenic systems; namely, the BALB/c-BALB/c.Bcgr pair and the B10.A-B10.A-Bcgr pair, by using three sonicated soluble bacterial Ag (mycobacterium bovis bacillus Calmette-Guérin, Salmonella typhimurium, and Brucella abortus) as well as a particulate Ag (heat-killed Escherichia coli). Pulsed Bcgr spleen cells were shown to induce a stronger proliferation of the T cell-indicator system than their Bcgs counterparts. No difference in Ag-presenting ability could be shown between Bcgr and Bcgs peritoneal macrophages from normal animals. However, elicited peritoneal macrophages from immune Bcgr mice were superior in their Ag-presentation ability. Differences at the level of Ag presentation of Bcgr and Bcgs splenic cells were investigated further. Depletion of T cells and B cells did not alter the differences in Ag-presenting ability between Bcgr and Bcgs spleen cells. Furthermore, splenic dendritic cells of Bcgr or Bcgs allelic types were equally efficient in presenting bacillus Calmette-Guérin Ag to accessory cell-depleted T cells. In a final experiment, it was shown that spleen macrophages were the cell type involved in the superior Ag presentation by Bcgr splenic cells.

Animals↗
PubMed1988

Two-step purification and N-terminal amino acid sequence analysis of the rat Mr 90,000 heat shock protein.

A fast and efficient method for the isolation of the rat Mr approximately 90,000 heat shock protein is presented, comprising a two-step high-performance anion-exchange and gel-permeation column chromatography. The Mr approximately 90,000 protein was purified to electrophoretic homogeneity in high yield (up to 2 mg per 10g of normal rat liver) in 4-5 h. The purified protein was recognized on protein immunoblots by monospecific rabbit antibodies raised against the rat glucocorticoid receptor-associated Mr approximately 90,000 non-ligand-binding protein. The N-terminal sequence of the first 25 amino acids of the purified protein showed a high degree of similarity with Mr approximately 90,000 heat shock proteins from calf, human, Drosophila, and yeast.

Amino Acid Sequence↗
PubMed1988

Subunit composition of the molybdate-stabilized non-activated glucocorticoid receptor from rat liver.

A monoclonal IgG 2a antibody directed against the activated rat liver glucocorticoid receptor (GR) was used to prepare an immunoaffinity matrix of high capacity. The molybdate-stabilized GR from rat liver cytosol was immunoadsorbed on this gel. A non-hormone-binding protein of Mr approximately 90,000, as determined after denaturing gel electrophoresis, was eluted from this matrix following removal of molybdate and exposure to heat (25 degrees C) and salt (0.15 M NaCl). Subsequently, the Mr approximately 90,000 protein was purified to homogeneity using high-performance ion-exchange chromatography, covalently radiolabelled, and analyzed by high-performance size-exclusion chromatography and sucrose gradient ultracentrifugation. Hydrodynamic characterization indicates that, under our experimental conditions, the molybdate-stabilized rat liver GR (Rs approximately 7.4 nm, s20,w approximately 9.1 S, calculated mol. wt Mr approximately 285,000) includes one steroid-binding unit (Rs approximately 5.5 nm, S20,w approximately 4.3 S, calculated Mr approximately 100,000) and a dimer of Mr approximately 90,000 non-hormone-binding protein (Rs approximately 6.9 nm, S20,w approximately 6.1 S, calculated native Mr approximately 180,000).

Animals↗
PubMed1988

Application of high-performance ion-exchange chromatography to the analysis of cytosolic glucocorticoid receptor.

The use of high-performance ion-exchange chromatography (HPIEC) on a Mono Q column was investigated for the analysis of glucocorticoid receptor. In the presence of 10 mM sodium molybdate, both liganded and unliganded glucocorticoid receptor were eluted as a single and sharp peak (0.32 M NaCl). In the absence of molybdate and after exposure to heat and salt, another peak of specifically bound radioactivity was eluted with 0.08 M NaCl. When HPIEC was performed in the absence of molybdate, two molecular forms of the liganded receptor were detected which eluted with 0.08 M NaCl (Stokes' radius Rs = 5.1 nm, s20,w = 4.6 S, calculated mol. wt Mr approximately 100,000) and 0.32 M NaCl (Rs = 7.3 nm, S20,w = 9.0 S, calculated Mr approximately 280,000). Analysis of both forms with mini-columns of DNA-Ultrogel, DEAE-Trisacryl and hydroxylapatite (HA-Ultrogel) confirmed the identity of the two peaks with transformed and non-transformed glucocorticoid-receptor complexes. These results suggest that HPIEC may provide a useful tool for the rapid resolution and quantification of receptor molecular forms.

Adrenalectomy↗
PubMed1988

Immunopathology of Entamoeba histolytica infections.

Entamoeba histolytica infects almost 10% of the world's population and results in about 100 000 deaths annually(1). Relatively little information is available concerning the immune response and the immunopathology elicited by this parasite, probably due in part to the lack of a truly appropriate animal model(2-4). However, there has been some progress - particularly concerning the interaction of this parasite with cells of the immune system(5,6). This review summarizes the salient features of the cellular immune response and immunopathology, largely from in vitro studies and studies using the gerbil model for invasive amoebiasis(7,8). Overall, the results suggest that invasive amoebtasis induces profound immune dysfunction both at the effector level of macrophages and on their accessory cell potential.

Journal Article↗
PubMed1988

Efficacy of intravenous spiramycin in the treatment of severe Legionnaires' disease.

Spiramycin is a 16-membered macrolide that has been shown in cell and animal models to be active against Legionella spp. The activity of the injectable form of spiramycin was evaluated in the treatment of severe Legionnaires' disease in seven immunocompromised and three previously healthy patients. Seven of the ten patients were cured. Three patients died primarily from the underlying disease or from intercurrent complications. This result and the better tolerance of spiramycin compared with 14-membered macrolides suggest that spiramycin may be a suitable alternative to erythromycin for the treatment of Legionnaires' disease.

Adult↗
PubMed1988

In vitro and in vivo studies of macrophage functions in amebiasis.

Experimental intrahepatic inoculation of the gerbil with Entamoeba histolytica trophozoites was used as a model of liver amebiasis to study the cellular immune response elicited by the parasite. It was shown that abscess-derived macrophages (5 to 20 days old) were deficient in their capacity to develop a respiratory burst, to secrete and express membrane-bound interleukin-1-like activity, and to kill E. histolytica trophozoites as well as to respond to lymphokines in vitro. However, macrophages isolated from the spleen and peritoneal cavities from the same infected animals were not significantly down regulated in these functions. Splenocytes from infected gerbils were shown to develop a strong responsiveness to amebic antigen, whereas their response to concanavalin A was suppressed. Crude E. histolytica extracts or conditioned medium down regulated murine BALB/c macrophage accessory and effector cell functions in vitro in a manner similar to abscess-derived macrophages, whereas crude extracts of the nonvirulent E. histolytica-like Laredo strain did not. Our results indicate that intrinsic or secreted products or both from E. histolytica are actively regulating macrophage functions at the abscess site and can possibly mediate other immunoregulatory mechanisms at distant targets.

Animals↗