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Biomedical subjects

M Gottlieb

Publications and source records attributed to M Gottlieb.

At least 109 records · Page 6Linked to original sources
PubMed1979

Allogeneic marrow transplantation after total lymphoid irradiation (TLI): effect of dose/fraction, thymic irradiation, delayed marrow infusion, and presensitization.

BALB/c mice infused with 30 x 10(6) C57BL/Ka bone marrow (BM) cells 1 day after treatment with fractionated total lymphoid irradiation (TLI) (17 fractions of 200 rads each) became stable mixed chimeras without clinical graft-vs-host disease (GVHD). Mice given 18 fractions of 100, 50, or 25 rads each followed 1 day later by C57BL/Ka BM did not become chimeric, indicating that a critical cumulative radiation dose is required for this effect. Animals given TLI with lead shielding placed over the thymus also developed stable chimerism without GVHD. Thus susceptibility to tolerance induction and protection from GVHD after TLI and allogeneic BM transplantation is not due to alteration of the thymic microenvironment by fractionated irradiation. A delay of 7 or 21 days between completion of TLI and BM administration resulted in a high incidence of graft rejection. Sensitization to minor histocompatibility antigens of the BM donor strain by blood transfusion either before or during TLI resulted in marrow graft rejection in a high percentage of animals.

Animals↗
PubMed1978

Polysaccharides of crithidia fasciculata. Identification and partial characterization of a cell surface constituent.

A carbohydrate-containing fraction was extracted from the trypanosomatid Crithidia fasciculata by a phenol-water procedure. Ion-exchange chromatography separated this fraction into three components: a polysaccharide which was not retained on the column; RNA which eluted upon addition of salt; and, another polysaccharide which eluted upon addition of detergent. The unretained fraction was shown to be composed solely of D-mannose. The mannan, which was heterodisperse on Sephadex G-100, had an average molecular weight of approx. 14 000 as based on analysis of reducing groups. The detergent-eluted material yielded arabinose and galactose upon acid hydrolysis. The arabinogalactan was excluded from Sephadex G-100 and Sephacryl S-200 molecular sieve columns, suggesting a molecular weight greater than or equal to 200 000. Cell fractionation studies showed the bulk of extractable polysaccharide was associated with a particulate fraction. Further determination of the cellular localization of the polysaccharide was accomplished by employing a specific antiserum prepared from rabbits immunized with the polysaccharide extract. The cell surface localization of the arabinogalactan was demonstrated by cell agglutination studies as well as immunocytochemical techniques using fluorescein and ferritin conjugated antibodies.

Animals↗
PubMed1977

A carbohydrate-containing antigen from Trypanosoma cruzi and its detection in the circulation of infected mice.

A polysaccharide-containing fraction has been prepared from the water-soluble material of a phenol-water extract of epimastigote forms of Trypanosoma cruzi. Sera from rabbits immunized with this material have been used to detect trypanosome-derived polysaccharide in plasma of mice acutely infected with this parasite. The polysaccharide nature of the circulating antigen is suggested by its heat stability, resistance to proteinase and nucleases, and destruction by sodium metaperiodate, as well as by its periodic acid-Schiff staining and precipitation with concanavalin A. The antigen appears to be present in different strains of the parasite and in different stages in the life cycle of the parasite.

Animals↗
PubMed1975

The irreversible step in formation of initiation complexes of Escherichia coli.

At some stage during initiation the ribosomal subunits of Escherichia coli must become irreversibly coupled, since polysomal ribosomes, in contrast to free ribosomes, are not dissociated by initiation factor IF-3. To determine when irreversibility develops we have compared the response to IF-3 of mature, puromycin-reactive initiation complexes, made with GTP, and of intermediate, puromycin-unreactive complexes, made with GMPPCP. The latter complexes initially appeared to be dissociated by the factor but this effect was found to be due to artificial loss of the ligands at the Mg2+ concentration customary in the test for dissociation. At a slightly higher Mg2+ concentration (4 mM), sufficient to retain the ligands, the GMPPCP complexes were not significantly dissociated by IF-3, at concentrations that caused complex dissociation of free ribosomes. It thus appears that the intermediate 70S initiation complex, though less stable to ionic dissociation than the mature complex, is in effect irreversible under physiological conditions.

Binding Sites↗