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Biomedical subjects

Y Kishimoto

Publications and source records attributed to Y Kishimoto.

At least 325 records · Page 18Linked to original sources
PubMed1979

Formation of lysosulfatide, 3',6'-anhydropsychosine, ceramide, and sphingosine by saponification of cerebroside sulfate. Effect of the sulfate group on the hydrolysis.

Saponification of cerebroside sulfate (sulfatide) by refluxing with 1 N KOH in 90% n-butanol for 1 h yielded ceramide, sphingosine, lysosulfatide (psychosine-3'-sulfate ester) and a hitherto unknown compound. The latter compound was identified as 3,6-anhydrogalactosyl sphingosine (3',6'-anhydropsychosine) from its mass spectrum. The structure of lysosulfatide was confirmed by reacylating it to sulfatide by condensing it with lignoceroyl chloride. The resulting sulfatide, which was chromatographically identical to control sulfatides, was not oxidized by periodate. The sulfatide was also permethylated and methanolyzed. The sugar moiety obtained was identified as methyl 2,4,6-tri-O-methylgalactoside by gas-liquid chromatography and thin-layer chromatography. The presence of the sulfate group in lysosulfatide was further confirmed by IR spectroscopy and the presence of radioactivity when it was prepared from [35S]sulfatide. The effect of the sulfate group on cleavage of the galactoside linkage and on the formation of the 3,6-anhydro derivative is discussed.

Animals↗
PubMed1978

Metabolic studies of adrenoleukodystrophy.

Two series of metabolic studies were prompted by the previous finding that the brain and adrenal tissues of patients with adrenoleukodystrophy, an X-linked genetic disorder, contain unusually long-chain (C22--C32) fatty acids in cholesterol esters and gangliosides. Postmortem brain tissues from three patients were assayed for activities of the three distinct cholesterol ester hydrolases, using [4-14C]cholesterol oleate, lignocerate and cerotate as the substrates. No deficiency of the crude mitochrondrial (pH 4.2), the microsomal (pH 6.0), or the myelin-localized cholesterol ester hydrolases was detected, although the activities of the myelin-localized cholesterol ester hydrolase against cholesteryl lignocerate and cerotate were too low for reliable assays. The activities of the microsomal and myelin-localized hydrolases were actually higher in adrenoleukodystrophy than in controls. Uptake and exclusion by cultured fibroblasts of [1-14C]stearic, [1-14C]lignoceric and [1-14C)cerotic acids were also examined. All fatty acids were avidly taken up by the fibroblasts. Stearic acid was excluded from the cells much more rapidly than lignoceric or cerotic acid. No difference was observed in the uptake and exclusion of fatty acids between the controls and adrenoleukodystrophy, except that cells from some cases of adrenoleukodystrophy consistently took up the very long chain fatty acids at greater rates than the control cells. Neither did the distribution of the label among individual lipids reveal differences between the controls and adrenoleukodystrophy, although there were interesting and dramatic differences in the metabolism of lignoceric acid and cerotic acid. Cerotic acid appeared largely inert with 90--95% remaining intact over eight days, while lignoceric acid was mostly incorporated into complex lipids. This series of studies did not uncover the fundamental genetic defect underlying adrenoleukodystrophy.

Biological Transport↗
PubMed1978

Total synthesis of stereospecific sphingosine and ceramide.

A small-scale synthesis of the four sphingosine stereoisomers (d-erythro, l-erythro, d-threo, and l-threo) and lignoceroyl d- and l-erythro-sphingosines, which is suitable for synthesis of tritium-labeled compounds, is described. Ethyl dl-erythro-2-acetamino-3-hydroxy-4t-octadecenoate was esterified with l(+)-acetylmandeloyl chloride and the two diastereomers obtained were separated from each other by thin-layer or column chromatography. Each diastereomer was subjected to ethanolysis to obtain ethyl d- or l-erythro-2-amino-3-hydroxy-4t-octadecenoate which was then reduced with LiAlH(4) or NaBH(4) to yield d- or l-erythro-sphingosine. d-erythro-[1-(3)H]Sphingosine with high specific activity was prepared by using LiAl(3)H(4) in the last step. d- and l-threo-sphingosines were synthesized from ethyl dl-threo-2-acetamino-3-hydroxy-4t-octadecenoate by using a similar procedure. Ceramide (lignoceroyl sphingosine) was prepared either by acylating sphingosine or by the following new method. Ethyl dl-erythro-2-amino-3-hydroxy-4t-octadecenoate was converted to the N-lignoceroyl derivative and esterified with l(+)-acetylmandeloyl chloride. The two diastereomers obtained were separated and each isomer was treated with a catalytic amount of sodium ethoxide. One of the products, ethyl d-erythro-2-lignoceroylamino-3-hydroxy-4t- octadecenoate, was reduced with NaBH(4) to yield ceramide. N-palmitoyl dl-erythro-sphingosine was also prepared using an identical procedure. N-lignoceroyl d-erythro-[1-(3)H]sphingosine was prepared by NaB(3)H(4) reduction of the corresponding amide ester. A doubly labeled ceramide, [1-(14)C]lignoceroyl [1-(3)H]sphingosine, containing high specific activity, was prepared by mixing the above N-lignoceroyl d-erythro-[1-(3)H]sphingosine and N-[1-(14)C]lignoceroyl d-erythro-sphingosine. The conversion of the doubly labeled ceramide to 3-keto derivative is also described.

Carbon Radioisotopes↗
PubMed1977

In vivo metabolism of ceramides in rat brain. Fatty acid replacement and esterification of ceramide.

Three double-labeled ceramides, [1-14C]lignoceroyl D-erythro-[1-3H]sphingosine, [1-14C]palmitoyl D-erythro-[1-3H]sphingosine and D-[1-14C]cerebronoyl D-erythro-[3-3H]-sphingosine, were prepared and injected separately into the brains of 18-day-old rats. The animals were killed after 2 h and various sphingolipids were isolated and purified. These lipids were further fractionated into subgroups depending on their fatty acid content (nonhydroxy or alpha-hydroxy, shorter chain or longer chain), 3H/14C ratios obtained in ceramides, cerebrosides, and sphingomyelins containing different fatty acids from the injected material were much higher than the initial ratio. This observation indicates that a replacement of the fatty acid occurred in the injected ceramide. Comparison of the 3H/14C ratios of the cerebrosides and sphingomyelin in a specific fatty acid group with the ratios of the corresponding ceramide indicated that most of these lipids were derived directly from the ceramide. The 3H/14C ratio of the hydroxycerebroside obtained from cerebronyl sphingosine-injected brain was nearly twice the ratio of the injected material. In addition to these lipids, considerable radioactivity was incorporated into an unknown nonpolar material in the brains which had been injected with [1-14C]lignoceroyl or [1-14C]palmitoyl [1-3H]sphingosine. This material was tentatively identified as ceramide fatty acid ester. The 3H/14C ratio of the ester was identical to that of the injected material.

Animals↗