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C C Sweeley

Publications and source records attributed to C C Sweeley.

At least 109 records · Page 6Linked to original sources
PubMed1973

Sphingolipid composition of human platelets.

Total lipid extracts from washed trypsinized human platelets were fractionated into neutral lipids, glycosphingolipids, and phospholipids by silicic acid chromatography. The concentrations and chemical structures of the neutral and acidic glycosphingolipids were then studied in detail. On the basis of sugar molar ratios, studies of permethylation products, and the action of stereospecific glycosidases on the lipids, identifications were made of four neutral glycosphingolipids. Lactosylceramide was the most abundant type and accounted for 64% of the total neutral glycolipid mixture. The major fatty acids of the lactosylceramide were 20:0, 22:0, 24:0, and 24:1; the major long-chain base was 4-sphingenine. The platelets were surprisingly rich in a ceramide fraction, which represented 1.3% of the total platelet lipids. It had a different fatty acid composition than the neutral glycosphingolipid and ganglioside fractions. Hematoside was also isolated from the total lipid fraction of platelets; the neuraminic acid component was N-acetylneuraminic acid. Treatment of platelets with trypsin, chymotrypsin, or thrombin increased the yield of hematoside as compared with a control, while the level of ceramides was not changed. It was concluded that the platelets are similar to leukocytes, liver, and spleen in that lactosylceramide and hematoside are the principal neutral and acidic glycosphingolipids. The presence of a relatively high proportion of ceramide in platelets may be a unique characteristic of this cellular fraction of blood.

Blood Platelets↗
PubMed1972

Generalized accumulation of neutral glycosphingolipids with G M2 ganglioside accumulation in the brain.

Analyses have been made of glycosphingolipids from visceral organs and brain of a patient with an unusual lipid storage disorder diagnosed initially as classical Tay-Sachs disease. Levels of the lipids from fresh-frozen sections of gray and white matter, kidney, spleen, liver, and heart from this patient were compared with those of normal juvenile controls, and the fatty acid composition of accumulated glycosphingolipids was compared with reference compounds. This patient was found to have abnormally high concentrations of a globoside in liver, kidney, and spleen, asialo G(M2) ganglioside in brain and liver, and G(M2) ganglioside in the brain. On the basis of these findings along with the clinical manifestations of Tay-Sachs disease with visceral involvement (hepatosplenomegaly) and demonstration of total deficiency of both A and B components of beta-N-acetylhexosaminidase activity, this glycosphingolipidosis is the same as two previously reported cases of G(M2) gangliosidosis with globoside accumulation and total beta-N-acetylhexosaminidase deficiency.

Brain↗
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↗
PubMed1971

Mass spectrometry of neutral, mono- and disialoglycosphingolipids.

Microgram quantities of complex glycosphingolipids were fully trimethylsilylated and analyzed by mass spectrometry. Reproducible ratios of the intensities of certain sugar fragment ions to the total intensity of ions characteristic of the sphingolipid bases were used to determine the number of monosaccharides in the glycosyl moiety and how many of them were unsubstituted at C-3. N-Acetylated hexosamine residues were readily detected and further characteristic fragment ions appeared if they were the terminal residues of the oligosac-charide chain. It was also possible to distinguish between the N-glycolyl and N-acetyl forms of neuraminic acid and to determine the number of sialic acid residues present in the lipid. Considerable information about the fatty acid and long-chain base composition was obtained from the same mass spectral analysis. It has been concluded that reliable structural information can be obtained from small amounts (less than 50 micro g) of a purified glycosphingolipid.

Acetates↗
PubMed1970

Enzyme replacement in Fabry's disease, an inborn error of metabolism.

Two patients with Fabry's disease were infused with normal plasma to provide active enzyme (ceramide trihexosidase) for hydrolysis of the plasma substrate, galactosylgalactosylglucosylceramide. Maximum ceramide trihexosidase activity occurred 6 hours after infusion of the plasma, attaining a level approximately 150 percent of that in normal plasma; enzymatic activity was detectable for 7 days. The amount of accumulated substrate in the plasma of these recipients decreased about 50 percent on day 10 after infusion. Thus, periodic replacement of ceramide trihexosidase activity in the plasma of patients with Fabry's disease might lead to consistently lower amounts of substrate in the plasma and a decrease in its rate of accumulation in tissues.

Adolescent↗