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Biomedical subjects

M Muller

Publications and source records attributed to M Muller.

At least 271 records · Page 15Linked to original sources
PubMed1986

[Regulation of prolactin and growth hormone gene expression in pituitary cell culture].

The rat pituitary tumor derived cell lines of the "GH" family offer a fruitful model for studying the expressions of the prolactin (rPRL) and growth hormone (rGH) genes in basic and regulated states. In order to assess the potential role of DNA methylation in the basic expressions of rPRL and rGH genes we have used different cell strains which produce either high level of rPRL (GH3B6 cells) or of rGH (GC cells) and minute amounts of both hormones (GH3CDL cells). The cleavage patterns generated by the methylation sensitive enzymes Hpa II and Msp I indicated an inverse correlation between the extent of gene methylation and the level of expression. However the use of 5-azacytidine which decreases DNA methylation suggested a variable importance of gene methylation in the respective control of rPRL and rGH genes depending on the cell lines. In an other hand we attempted to elucidate some of the mechanisms by which thyroliberin (TRH) enhances rPRL gene transcription in GH3B6 cells. Preliminary results indicated that the persistent occupancy of the TRH receptors was required to sustain at least for the first 5 hours the increased rate of rPRL gene transcription. In addition the possible relationship between the TRH-induced acute rPRL release and the stimulation of rPRL gene transcription was investigated. The results suggested that the activators of the C kinase-mediated pathway which are actually involved in the stimulation of the acute release were not sufficient alone for eliciting the maximum TRH response at the gene level.

Animals↗
PubMed1985

Role of solute drag in intestinal transport.

This study presents experiments related to the role of solvent drag and solute drag in the transmembrane movement of nonelectrolytes in a perfused rat intestine preparation. Conditions were chosen to simulate the effects of luminal hyperosmolarity on the permeability of tracer solutes. Data are presented on net water flux, transepithelial potentials, and lumen-to-blood and blood-to-lumen tracer solute movements during control electrolyte perfusion and after making the perfusate hyperosmotic. The results indicate that both solvent drag and solute drag can play significant roles in the transepithelial movement of solute and solute permeabilities in the rat ileum preparation. It is suggested that the potential roles of solvent drag and solute drag should be accounted for or considered during the characterization of the mechanisms of biological membrane function.

Animals↗
PubMed1984

Growth of Aboriginal infants.

Aboriginal infants at Cherbourg Aboriginal Settlement in Queensland now have growth rates which are similar to those of white Australian infants. The proportion of children under 90% of the standard weight-for-age appears to be the same as for white Australian children and meets the international standards. Apart from premature infants, no children have been found in the accepted "at risk" categories.

Australia↗
PubMed1983

Immunologic reactivity in marrow graft recipients receiving cyclosporine to prevent graft-versus-host disease.

In vitro and in vivo immunologic parameters were determined in 26 patients treated continuously with cyclosporine to prevent graft-versus-host-disease (GVHD) after allogeneic bone marrow transplantation (BMT) for acute and chronic leukemia and for aplastic anemia. A group of 18 patients was tested 6 months after BMT and another group of 10 patients was tested after one year. At 6 months after BMT, 94% of the patients had normal serum IgG and IgM levels, whereas at one year 29% of them had low IgA levels. The proportion of patients with normal lymphocyte responses in vitro at 6 months after BMT was 69% and 76% for the responses to concanavalin A and to soluble antigens; 75% and 53% for the responses to allogeneic cells and pokeweed mitogen, respectively; and 89% for the response to phytohemagglutinin. All but one were able to generate suppressor cells upon con A stimulation. At one year after the graft, only one patient had demonstrable multiple abnormalities in in vitro tests. Skin test reactivity at one year was comparable to pre-graft reactivity. After BMT a lymphopenia persisted for 6 months. The rate of infectious complications was high during the first 3 months after BMT, and it diminished progressively as immune functions returned to normal. Infection was the cause of death in two cases (one disseminated cytomegalovirus infection and one septicemia). GHVD occurred in 12 patients; in nine of them the disease was transient and mild, only 1 patient developed severe chronic GVHD. Acute GVHD did not influence the tempo of immunologic reconstitution. In comparison to other studies, it seems that cyclosporine does not delay immune restoration, or increase morbidity from infection, while preventing GVHD and its complications efficiently.

Anemia, Aplastic↗
PubMed1982

Effects of solvent and solute drag on transmembrane diffusion.

The present study compares and quantitates both solvent drag and solute drag forces in a system with both heteropore and homopore membranes. It is shown that tracer solute permeability can be increased if solution flow or driver solute flux is in the direction of tracer diffusion. Either force can decrease tracer permeability if the force can decrease tracer permeability if the force is opposite to the direction of tracer diffusion. The two forces can be additive or one force may reduce the effect of the other force. In the particular system quantitated, solute drag is shown to be some 300 times more effective than solvent drag on a mole-to-mole basis. The use of a number of solute pairs on other homopore and heteropore membranes confirms the finding that the two drag forces can be analyzed or manipulated in a variety of systems.

Carbonates↗
PubMed1981

Localization of the phosphoester bond hydrolyzed by the major apurinic/apyrmidinic endodeoxyribonuclease from rat-liver chromatin.

The major apurinic/apyrimidinic (AP) endodeoxyribonuclease from rat liver chromatin, an enzyme specific for AP sites in DNA, cleaves the phosphodiester bridge which is the immediate neighbour of the AP site on its 5' side leaving 3'-hydroxyl and 5'-phosphate ends. In contrast with Escherichia coli endonuclease VI, this chromatin enzyme is inactive on reduced AP sites.

Animals↗
PubMed1979

Effect of gravity on lymphocyte proliferation.

Reports on postflight examination of lymphocytes from crew members of soviet and american spaceships show a depression of reactivity towards mitogens in vitro. The purpose of this communication is to present experimental evidence that gravity can interfere with lymphocyte activation. Lymphocytes were incubated in the presence of concanavalin A in a centrifuge at 2 and 4 g for four days. This environment causes a significant acceleration of the response to the mitogen. In addition, remarkable differences in the ultrastructure of cells grown at 1 g and 4 g are observed by electron microscopy. This investigation is related to the experiment "Effect of weightlessness on lymphocyte proliferation" experiment which will be performed during the first Spacelab mission.

Animals↗