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Biomedical subjects

M M Rapport

Publications and source records attributed to M M Rapport.

At least 73 records · Page 4Linked to original sources
PubMed1974

Determination of long-chain base in glycosphingolipids with fluorescamine.

A method is described for determining the long-chain base content of glycosphingolipids after acid hydrolysis, using the new reagent fluorescamine. The reaction is sensitive and can be used to characterize or measure glycosphingolipids in quantities routinely separated by thin-layer chromatography.

Animals↗
PubMed1972

Immunochemical studies of organ and tumor lipids. XIX. Cytolytic action of antibodies directed against cytolipin R.

Rabbit antisera to rat lymphosarcoma contain antibodies that are cytolytic for rat erythrocytes in the presence of complement. The reaction can be inhibited completely by pure cytolipin R showing that (a) immune hemolysis can be mediated through lipid determinants in the membrane, and (b) that cytolipin R determinants are present in the intact erythrocyte membrane and exposed on the surface. Optimal conditions for measurement of cytolysis in this system based on release of (51)Cr are described. Degrees of specificity of a number of different antilymphosarcoma sera are shown, based on inhibition of cytolysis by cytolipin R, cytolipin K, cytolipin H, cytolipin F (F-hapten), glucocerebroside, galactocerebroside, ceramide trisaccharide (cer-glu-gal-gal), and a mixed brain ganglioside preparation. The data suggest that cytolytic antibodies and agglutinating antibodies in these antisera are distinctive despite their common specificity for cytolipin R. Lymphosarcoma cells are more effective than erythrocytes in absorbing cytolytic antibodies.

Animals↗
PubMed1972

On the structure of cytolipin R, a ceramide tetrahexoside hapten from rat lymphosarcoma.

Cytolipin R, a ceramide tetrahexoside isolated from rat lymphosarcoma, was studied by sequential hydrolysis with specific glycosidases which revealed the anomeric configurations of the glycosidic bonds. Sugar linkages were established by combined gas-liquid chromatography and mass spectrometry of the partially methylated alditol acetates prepared after permethylation and hydrolysis of the intact lipid. Results indicated the structure of cytolipin R to be N-acetylgalactosaminyl(beta1-->3)galactosyl(alpha1-->3) galactosyl(beta1-->4)glucosyl ceramide. Cytolipin K (globoside I) differs in having a -galactosyl(alpha1-->4)galactosyl- internal linkage, and this difference must account for the immunological differences between cytolipin K and cytolipin R.

Alkylation↗
PubMed1969

Reactivity of plasmalogens: kinetics of acid-catalyzed hydrolysis.

The acid-catalyzed hydrolysis of the alpha,-unsaturated ether group of two plasmalogens, lysophosphatidal choline and lysophosphatidal ethanolamine, and several model compounds (isobutyl vinyl ether, 1-butenyl ethyl ether, and dihydropyran) was studied by determining the true second-order rate constants. The results indicate that the chemical reactivity of the substituted vinyl ether group in plasmalogens is not appreciably affected by the presence of a bulky substituent on the -carbon. Activation energies, enthalpies, and entropies were also determined (from measurements of the rate constants at different temperatures).

Chemical Phenomena↗
PubMed1968

Sleep patterns of the monkey and brain serotonin concentration: effect of p-chlorophenylalanine.

The amount of time that monkeys (Macaca mulatta) slept was reduced after they were given p-chlorophenylalanine, a selective depletor of serotonin in animal tissues. The time spent in the rapid eye movement stage of sleep was unchanged, but the time in other sleep stages decreased. Seven regions of the brain had a 31 to 46 percent decrease in serotonin content; the concentration of cerebellar serotonin increased by 44 percent.

Animals↗