Biomedical subjects

A Chedeville

Publications and source records attributed to A Chedeville.

21 records · Page 2Linked to original sources

PubMed1979

[Rat liver phosphoglycerate kinase. I. Purification and kinetic properties in the biosynthesis of 1-3 diphosphoglycerate].

Phosphoglycerate kinase (MgATP 3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3) has been isolated from rat liver with a purification ratio of 960 and a specific activity of 300 IU/mg of protein. The purity of the enzyme preparations was estimated by polyacrylamide gel electrophoresis. The molecular weight, determined by gel filtration is 42 000. The "subunit" size of phosphoglycerate kinase as determined by sodium dodecyl sulfate gel electrophoresis is 46 000, indicating that the enzyme is monomeric. The rate of the enzyme reaction as a function of the concentration of D-3-phosphoglycerate indicated the usual Michaelis Menten relationship. The rate of the enzyme reaction as a function of the concentration of MgATP2- did not fit the usual Michaelis Menten relationship: two distinct regions can be fitted with different straight lines and suggest the presence of two sites for the Mg ATP2-. This hypothesis seems to be confirmed by the study of the action of the free and complexed nucleotides.

Adenosine Diphosphate↗

PubMed1976

Enhancement of murine erythrocyte auto-antibody responses by Rauscher leukemogenic virus and by a weak allogeneic stimulation.

B6/c mice do not develop spontaneous positive direct Coomb's tests (DCT), but they are highly susceptible to the induction of erythrocyte auto-antibodies by immunization with cross reacting rat blood cells (36% positive DCT). Rauscher leukemogenic virus (RLV) does not directly induce DCT in these susceptible mice; neither does the inoculation of parental spleen cells. On the other hand both RLV and allogeneic stimulation by parental spleen cells enhance the incidence of the rat blood cell-induced DCT (up to 75% and 69% respectively). This is discussed in terms of a separate etiology to antinuclear and anti-erythrocyte auto-antibodies and of the possible mechanisms of auto-immune stimulation by oncogenic viruses or allogeneic stimulation.

Animals↗

PubMedDate not supplied

Discrepancy between in vitro and in vivo passaged U-937 human leukemic cells: tumorigenicity and sensitivity to differentiating drugs.

The treatment of nude mice bearing tumors of transplanted human leukemic cells with drugs known to induce differentiation of the same leukemic cells in vitro does not always affect tumor yield, tumor cell differentiation or nude mice survival. We have transplanted human monoblastic leukemic cells of the U-937 cell line into newborn Swiss nu/nu mice. Priming with cyclophosphamide, followed by subcutaneous injections of at least 10 x 10(6) cells allowed us to obtain solid tumors. The cytology, HLA phenotype and in vitro proliferation characteristics of the U-937 tumor cells were conserved. However, these tumor cells were more tumorigenic when reinjected into nude mice and showed a modified response to differentiation induction. A decreased capacity to differentiate with retinoic acid (RA) and a resistance to 1-beta-D arabinofuranosyl cytosine (Ara-C) and 1-25 dihydroxy vitamin D3 (1-25 (OH)2 D3) were noted in three tumor cell lines tested. With regard to the latter, the resistance was not due to a modification of the number of cell receptors. The study shows that though in vivo transplantation of human leukemic cells in nude mice may lead to a selection of resistant cells, systematic checking of in vitro differentiation characteristics of the tumor cells permits the nude mouse model to be maintained for the in vivo screening of new differentiating agents.

Animals↗