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Biomedical subjects

J S O'Brien

Publications and source records attributed to J S O'Brien.

At least 217 records · Page 12Linked to original sources
PubMed1969

Tay-Sachs disease: generalized absence of a beta-D-N-acetylhexosaminidase component.

Two hexosaminidase components, separable by starch-gel electrophoresis and possessing both beta-D-N-acetylglucosaminidase and beta-D-N-acetylgalactosaminidase activity, are present in human tissues. One of these, hexosaminidase component A, is absent in brain, liver, kidney, skin, cultured skin fibroblasts, blood plasma, and leukocytes from nine patients with Tay-Sachs disease. Hexosaminidase assay may facilitate the early diagnosis of individuals homozygous for Tay-Sachs disease.

Cerebral Cortex↗
PubMed1969

Tissue distribution of glycosphingolipids in a case of Fabry's disease.

A survey was made of the glycolipid composition of various tissues, including liver, spleen, kidney (cortex and medulla), lymph node, pancreas, prostate gland, heart muscle, thenar muscle, gastrointestinal smooth muscle, frontal cerebral cortex, anterior thalamus, brain stem, a peripheral autonomic ganglion, and renal arterial intima and media, from a patient who died with Fabry's disease. The tissues had been fixed in formalin for 3 yr. Analytical data on trihexosyl ceramide from heart muscle and pancreas indicate a structure identical to trihexosyl ceramide from kidney: galactosylgalactosylglucosyl ceramide. Fatty acid compositions of trihexosyl ceramide and dihexosyl ceramide revealed a wide range of fatty acids, with 16:0, 18:0, 20:0, 22:0, 24:0, and 24:1 predominating. These glycolipids comprised 10-41% of the total lipid in the formalin-fixed organs studied. Trihexosyl ceramide predominated in all tissues and was the only glycolipid found in muscle tissues, lymph node, and arterial tissues. Dihexosyl ceramide was found in kidney, pancreas, liver, spleen, and cerebral tissues. The accumulation of trihexosyl ceramide in cardiac muscle and arterial tissues may account in part for the cardiovascular complications so prominent in Fabry's disease.

Adult↗
PubMed1968

Generalized gangliosidosis: beta-galactosidase deficiency.

A profound deficiency (10- to 30-fold) of beta-galactosidase activity was found in tissues (liver, spleen, kidney, and brain) from two patients with generalized gangliosidosis; this deficiency is demonstrated as a failure to cleave both p-nitrophenyl-beta-D-galactopyranoside and ganglioside GM(1) labeled with C(14) in the terminal galactose. We believe that this enzymic defect is responsible for the accumulation of ganglioside GM(1) and is the fundamental enzyme defect in generalized gangliosidosis.

Acid Phosphatase↗
PubMed1968

Lipid composition of the nervous system in Refsum's disease.

The compositions of the major lipids and their constituent fatty acids and fatty aldehydes from cerebral gray matter, white matter, and myelin, spinal cord myelin, and sciatic nerve were determined in a 57 yr old woman who died of Refsum's disease. There were deficiencies of ethanolamine glycerophosphatides (EGP) in gray matter and frontal lobe myelin, and a lipid with the chromatographic properties of lyso-EGP accumulated in all tissues. The proportions of the remaining lipids were nearly normal in the central nervous system tissues. In the sciatic nerve the proportions of sphingolipids were small; this observation is consistent with the severe demyelination noted on pathologic examination. Cholesteryl esters were not detected in any tissue. Phytanate (3,7,11,15-tetramethylhexadecanoate) was present in the glycerophosphatides from each tissue. Higher proportions of phytanate were found in choline glycerophosphatides (CGP) than in EGP or in serine glycerophosphatides (SGP). Hydrolysis with phospholipase established that phytanate was confined to the 1-position of CGP. More phytanate was found in CGP from myelin than from gray or white matter. Fourfold higher proportions of phytanate were found in CGP from sciatic nerve than in CGP from the central nervous system: in sciatic nerve, 24% of the fatty acids of CGP consisted of phytanate. The proportions and compositions of sphingolipid hydroxy fatty acids and odd-numbered fatty acids were normal in each tissue. These findings argue against a defect in sphingolipid alpha-hydroxy acid metabolism in Refsum's disease. The results are consistent with the view that the accumulation of phytanate is responsible for the demyelination.

Aldehydes↗
PubMed1968

Positional distribution of fatty acids in glycerophosphatides of bovine gray matter.

Glycerophosphatides were isolated from ox brain gray matter by column chromatography. The fatty acid compositions of ethanolamine glycerophosphatides (EGP), serine glycerophosphatides (SGP), and choline glycerophosphatides (CGP) were determined by gas-liquid chromatography. The positional distribution of fatty acids in these glycerophosphatides were determined by phospholipase A hydrolysis (Habu habu venom). C(20) and C(22) polyunsaturated acids were confined almost exclusively to the 2-position of these lipids, where they comprised the majority of 2-substituents in EGP and SGP (oleic acid predominated in this position in CGP). In the 1-position, palmitoyl was the major substituent in CGP, stearoyl in SGP, and stearoyl or the corresponding alk-1-enyl group in EGP.

Amino Alcohols↗
PubMed1965

Myelin Membrane: a molecular abnormality.

Myelin was isolated from cerebral white matter from a patient who had died of metachromatic leukodystrophy, and its lipid composition was analyzed. Although the lipid content was nearly normal, the myelin contained a three- to fourfold excess of cerebroside sulfate and a threefold deficiency of cerebroside compared to normal myelin. The deficiency of cerebroside and the excess of cerebroside sulfate may account for defective myelination in this disease.

Amino Alcohols↗