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At least 883 records · Page 49Linked to original sources
PubMed1980

Heterosis for brain myelin content in mice.

Biochemical evidence of heterosis (hybrid vigor) for brain myelin content is presented. The concentrations of cerebroside and GM1 ganglioside, two glycolipids known to be abundant in myelin, were higher in the brains of (C57BL/6J X DBA/2J) F1 hybrids than in the brains of either parental strain. Furthermore, brain water content, which is known to be inversely related to myelin content, was lower in the F1 hybrids, especially during the most active period of myelin synthesis. Heterosis was not observed, however, for total brain ganglioside concentration. Additionally, the results do not substantiate a direct developmental-genetic relationship between brain myelin content and susceptibility to audiogenic seizures.

Animals↗
PubMed1980

Demyelination of the mamillary bodies in alcoholism. A combined morphological and biochemical study.

Four different regions of the brain (the mamillary bodies, vermis of the cerebellum, the dorsal and medial part of thalamus, and the quadrigeminal plate) from nine male chronic alcoholics and nine controls were analyzed for morphological and biochemical abnormalities. The mamillary bodies, in contrast to the other three regions, showed loss of myelinated fibers and decreased concentrations of cerebrosides, cholesterol and phospholipids, indicating demyelination. It is concluded that this kind of lesion is common in chronic alcoholism.

Adult↗
PubMed1981

The AB-variant of metachromatic leukodystrophy (postulated activator protein deficiency). Light and electron microscopic findings in a sural nerve biopsy.

THe histopathological findings in a sural nerve biopsy of a new distinct variant of metachromatic leukodystrophy (MLD) are compared to those of classical MLD. The clinical and histological features are typical of a sulfatide lipidosis, yet in vitro activities of arylsulfatases A and B and cerebroside sulfatase are normal. Intact skin fibroblasts, when cultured in a medium supplemented with labelled sulfatide, show impaired in vivo sulfatide hydrolysis. A deficiency of the requisite activator protein is postulated.

Adult↗
PubMed1982

Distribution of lipid synthesizing enzymes, 2',3'-cyclic nucleotide 3'-phosphodiesterase, and myelin proteins in rat forebrain subfractions during development.

The distribution of UDP-galactose:ceramide galactosyltransferase (CGalT) was studied in subcellular fractions of rat forebrain during development using zonal centrifugation on linear gradients. Specialized subfractions: SN 1, a microsomal fraction, SN 4, a myelin-related fraction, and purified myelin were also used for this study. For comparison, two microsomal lipid synthesizing enzymes, a myelin-specific enzyme, 2',3'-cyclic nucleotide 3'-phosphodiesterase and myelin proteins were measured in the same subfractions. UDP-glucose:ceramide glucosyltransferase and cerebroside sulfotransferase were confined to microsomes. CGalT was localized in microsomes, but also in myelin and myelin-related fractions. The developmental change in distribution of CGalT in adult animals toward myelin containing fractions could indicate that the replacement of galactosylceramide in compact myelin could be carried out in close proximity to compact myelin (mesaxon, paranodal loops) rather than in the distant oligodendrocyte perikaryon.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1990

Advances in the molecular genetics of metachromatic leukodystrophy.

Metachromatic leukodystrophy is a lysosomal storage disorder caused by the deficiency of arylsulphatase A (EC 3.1.6.1). This results in the intralysosomal storage of cerebroside sulphate, which leads to a progressive demyelination of the nervous system. The patients usually die within a few years from the onset of symptoms. Clinically, there are different forms of the disease and the molecular basis for this heterogeneity is unknown. The gene for arylsulphatase A has recently been cloned and provides a necessary tool for the exact description of the molecular defects occurring in the different forms of metachromatic leukodystrophy. Metachromatic leukodystrophy can also be caused by the deficiency of an arylsulphatase A activator protein (sphingolipid activator protein B). The cDNA for the precursor of this protein has been isolated and a mutant cDNA of one patient has been analysed. A substantial arylsulphatase A deficiency can also occur in healthy individuals, a phenotype termed pseudodeficiency. Two concurrent mutations have been identified in this low arylsulphatase A activity allele. This permitted the development of a rapid assay which allows the detection of the pseudodeficiency allele. Bone marrow transplantation has been tried in several metachromatic leukodystrophy patients and there is evidence that this treatment might slow or even halt the progression of the disease. A final conclusion as to whether bone marrow transplantation is a suitable therapy for metachromatic leukodystrophy cannot be drawn yet.

Amino Acid Sequence↗
PubMed1988

Interaction of furosemide with lipid membranes.

The interaction of furosemide with different phospholipids was investigated. Its influence on the lipid structure was inferred from its effect on the phase transition properties of lipids and on the conductance of planar bilayer membranes. The thermotropic properties of dipalmitoyl phosphatidylcholine, phosphatidylethanolamine (natural), dipalmitoyl phosphatidylethanolamine, brain sphingomyelin, brain cerebrosides and phosphatidylserine in the presence and absence of furosemide were investigated by differential scanning calorimetry. The modifying effect of furosemide seems to be strongest on phosphatidylethanolamine (natural) and sphingomyelin bilayers. The propensity of furosemide to decrease the electrical resistance of planar lipid membranes was also studied and it is shown that the drug facilitates the transport of ions. Partition coefficients of furosemide between lipid bilayers and water were measured.

Cerebrosides↗
PubMed1988

Stimulation of liver growth and DNA synthesis by glucosylceramide.

The nature of the growth-stimulating effect of glucosylceramide was studied. Mice were injected intraperitoneally with emulsified glucosylceramide and conduritol B epoxide, an inhibitor of cerebroside glucosidase. Within one or two days, the liver grew 18-24%, as reported. Two enzymes involved in DNA synthesis also increased more than the weight. The total liver activity of thymidine kinase increased 46-73%, and the total activity of ornithine decarboxylase increased as much as 101%. It is suggested that elevated liver levels of glucocerebroside stimulate cell proliferation through a relatively direct mechanism.

Animals↗
PubMed1995

Arylsulfatase A and beta-galactosidase activities in leukocytes and lymphocytes from normal and psychiatric subjects. Effects of blood-processing delay and interleukin-2 stimulation.

Arylsulfatase A (ASA) and cerebroside-beta-galactosidase activities in leukocytes serve as a diagnostic tool for determining the presence of metachromatic leukodystrophy and globoid cell leukodystrophy, respectively. It has not been demonstrated whether a delay in blood processing and the presence of mixed cell types in different proportions in leukocytes affect the activities of the two enzymes in these cells. We have in the present study determined the specific activity in leukocytes and lymphocytes (T-cells) prepared from blood samples processed immediately after, 4, and 24 h after collection. In order to determine whether the enzyme activities in lymphocytes reflect expression of genetic trait, and not environmental or "state" influence, the activities of the two enzymes in interleukin 2-stimulated T-cells and resting T-cells were compared. A delay of up to 24 h in blood processing did not significantly change the specific activities of the two enzymes in both leukocytes and lymphocytes. The specific activity of ASA and beta-galactosidase in lymphocytes was 1.4-1.8 times that in leukocytes. The activities of the two enzymes in interleukin 2-stimulated T-cells did not differ from those in resting T-cells. These results indicate that blood-processing delay had no significant effects on ASA and beta-galactosidase activity. The data further indicate that the ASA and beta-galactosidase activity in interleukin 2-stimulated T-cells was not significantly different from resting lymphocytes from either normal or psychiatric subjects exposed to various medications. The activity levels in lymphocytes from psychiatric subjects thus reflect expression of genetic trait, rather than environmental or state influence.

Adult↗
PubMed1979

Membrane instability induced by purified myelin components. Its possible relevance to experimental allergic encephalomyelitis.

The fusogenic properties of purified myelin components in a system employing chicken erythrocytes were studied. Sulphatides, myelin basic protein and the apoprotein of Folch-Lees proteolipid were capable of individually inducing membrane fusion in the presence of Ca2+. By contrast, cerebrosides or a mixture of sulphatides and myelin basic protein (molar ratio 19 : 1) did not show such effect. The fusogenic ability of sulphatide was correlated to its behaviour in mixed monolayers with phospholipids at the air-water interface. Mixed films of sulphatides with phosphatidylcholine or sphingomyelin but not with phosphatidylethanolamine showed reductions of molecular packing and surface potential similar to those found for other fusogenic compounds. The effects of myelin components described could be of importance in the membrane instability and vesicular disruption of myelin occurring in demyelinative disorders.

Animals↗
PubMed1988

Photolabeling of myelin basic protein in lipid vesicles with the hydrophobic reagent 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine.

The hydrophobic photolabel 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine([125I]TID) was used to label myelin basic protein or polylysine in aqueous solution and bound to lipid vesicles of different composition. Although myelin basic protein is a water soluble protein which binds electrostatically only to acidic lipids, unlike polylysine it has several short hydrophobic regions. Myelin basic protein was labeled to a significant extent by TID when in aqueous solution indicating that it has a hydrophobic site which can bind the reagent. However, myelin basic protein was labeled 2-4-times more when bound to the acidic lipids phosphatidylglycerol, phosphatidylserine, phosphatidic acid, and cerebroside sulfate than when bound to phosphatidylethanolamine, or when in solution in the presence of phosphatidylcholine vesicles. It was labeled 5-7-times more than polylysine bound to acidic lipids. These results suggest that when myelin basic protein is bound to acidic lipids, it is labeled from the lipid bilayer rather than from the aqueous phase. However, this conclusion is not unequivocal because of the possibility of changes in the protein conformation or degree of aggregation upon binding to lipid. Within this limitation the results are consistent with, but do not prove, the concept that some of its hydrophobic residues penetrate partway into the lipid bilayer. However, it is likely that most of the protein is on the surface of the bilayer with its basic residues bound electrostatically to the lipid head groups.

Animals↗
PubMed1994

Do the long fatty acid chains of sphingolipids interdigitate across the center of a bilayer of shorter chain symmetric phospholipids?

Novel cerebroside sulfate (CBS) spin labels containing long chain C24 or C26 fatty acids with a nitroxide spin label on the 22nd carbon were synthesized and used to investigate the ability of the long fatty acid chains of glycosphingolipids to interdigitate across the center of a non-interdigitated bilayer of phospholipids formed of symmetric saturated or unsaturated shorter fatty acid chain species, in the presence or absence of cholesterol. The motion of these long chain spin labels incorporated at 1 mole% in dimyristoylphosphatidylcholine (diC14-PC), dipalmitoylphosphatidylcholine (diC16-PC), distearoylphosphatidylcholine (diC18-PC), dibehenoylphosphatidylcholine (diC22-PC), spingomyelin (SM), 1-stearoyl-2-oleoylphosphatidylcholine (18:0.18:1-PC), and dimyristoylphosphatidylethanolamine (diC14-PE) was compared to that of CBS spin labels containing stearic acid spin labeled at the 5th carbon and at the 16th carbon. The results indicated that the C26 chain is interdigitated in the gel phase of diC14-PC, diC16-PC, SM, and possibly diC18-PC, but not diC14-PE, and the C24 chain may interdigitate in diC14-PC but not in the other phospholipids. Thus in order to interdigitate across the center of gel phase bilayers, the long acyl chain of the sphingolipid probably must be long enough to nearly span the phospholipid bilayer. The inability to interdigitate in diC14-PE is likely due to the close packing of this lipid in the gel phase. The C26 chain may also be interdigitated in these lipids in the presence of cholesterol at low temperatures. However, at physiological temperatures in the presence of cholesterol and in the liquid-crystalline phase of all the lipids, the results indicate that the long acyl chain of the glycosphingolipid is not interdigitated, but rather must terminate at the bilayer center. This may force the carbohydrate headgroup of the glycosphingolipid farther above the bilayer surface, allowing it to be recognized better by various carbohydrate binding ligands and proteins.

Cerebrosides↗
PubMed1976

Ascorbic acid-2-sulfate sulfhohydrolase activity of human arylsulfatase A.

Pure human arylsulfatase A (EC 3.1.6.1) was found to hydrolyze ascorbic acid 2-sulfate to ascorbic acid and inorganic sulfate at rates from 200 to 2000 mumol/mg per h depending on the method of assay. This rate was lower than that observed with the synthetic substrate 4-nitrocatechol sulfate, but higher than that seen with the physiological substrate cerebroside sulfate. Extracts of cultured fibroblasts from normal subjects were also shown to hydrolyze ascorbic acid 2-sulfate; extracts of fibroblasts from patients with metachromatic leukodystrophy, known to be deficient in arylsulfatase A, did not. Similarly, hydrolysis of ascorbic acid 2-sulfate was not observed when a partially purified preparation of human arylsulfatase B was tested under a variety of conditions. Thus, in the human, arylsulfatase A appears to be the major, if not the only, ascorbic acid-2-sulfate sulfohydrolase.

Ascorbic Acid↗
PubMed1977

3'-phosphoadenylylsulfate:galactosylceramide 3'-sulfotransferase. An optimized assay in homogenates of developing brain.

An optimized in vitro assay of 3'-phosphoadenylysulfate:galactosylceramide 3'-sulfotransferase (EC 2.8.2.11, galactosylceramide sulfotransferase, formerly known as galactocerebroside sulfotransferase) activity is presented, that can be used in crude homogenate of brain tissue of various developmental stages. The enzyme activity is determined by measuring the [35S]sulfatides formed by the enzymic transfer of [35S]sulfate from 3'-phosphoadenoside 5'-phospho [35S]sulfate to galactosylceramides. The sulfatide formation at 30 degrees C is linear up to 30 min and up to a protein concentration of 1 mg per 0.5 ml assay volume. The presence of 0.4% Triton X-100 and 50 micrometer exogenous bovine cerebrosides are optimal for enzyme activity. The pH optimum of the reaction is at pH 6.5 using 0.1 M imidazole buffer. The enzyme reaction is stimulated by NaCl, KCl, MgCl2, CaCl2, MnCl2, ATP and inhibited by ADP. The developmental enzyme activity pattern of mouse brain is the same, if derived from homogenates and microsomes, respectively, under our assay conditions.

Adenosine Diphosphate↗
PubMed1979

The activity of arylsulfatase A and B on tyrosine O-sulfates.

L-Tyrosine O-sulfate was hydrolyzed by pure human arylsulfatase A (arylsufate sulfohydrolase, EC 3.1.6.1). The rate of hydrolysis was 1/20 of the rate with nitrocatechol sulfate, but was comparable to the rate with cerebroside sulfate. The reaction was optimal at pH 5.3--5.5 and displayed zero order kinetics with time and enzyme concentration. The Km was about 35 mM. The enzyme showed no stereospecificity and hydrolyzed D-tyrosine O-sulfate with Km and V similar to those for the L-isomer. Arylsulfatase B was less than 5% as effective as arylsulfatase A in catalyzing the hydrolysis of the tyrosine sulfates. The daily urinary excretion of tyrosine sulfate by a patient with metachromatic leukodystrophy (arylsulfatase A deficiency) was comparable to the excretion by control subjects. The biological relevance of the tyrosine sulfatase activity of arylsulfatase A remains uncertain.

Cerebroside-Sulfatase↗
PubMed1981

3',5'-Cyclic nucleotide phosphodiesterase activity of the sulphatase A of ox liver.

The sulphatase A (aryl-sulphate sulphohydrolase, EC 3.1.6.1) of ox liver hydrolyses adenosine 3',5'-monophosphate (cyclic AMP) to adenosine 5'-phosphate at an optimum pH of approx. 4.3, close that for the hydrolysis of cerebroside sulphate, a physiological substrate for sulphatase A. The Km is 11.6 mM for cyclic AMP. On polyacrylamide gel electrophoresis sulphatase A migrates as a single protein band which coincides with both the arylsulphatase and phosphodiesterase activities, suggesting that these are due to a single protein. Cyclic AMP competitively inhibits the arylsulphatase activity of sulphatase A, showing that both activities are associated with a single active site on the enzyme. sulphatase A also hydrolyses guanosine 3',5'-monophosphate, but not uridine 3',5'-monophosphate nor adenosine 2',3'-monophosphate.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1977

Age-dependent modulation of 3'-phosphoadenosine-5'-phosphosulfate-galactosylceramide sulfotransferase by lipids extracted from the microsomal membranes and artificial lipid mixtures.

The 3'-phosphoadenosine-5'-phosphosulfate-galactosylceramide-sulfotransferase (cerebroside sulfotransferase) is microsomal enzyme, which shows a definite developmental activity pattern. This report gives evidence that the enzyme activity of partially delipidated microsomes is modulated by the cholesterol:phospholipid ratio of the extracted microsomal lipids in an age-dependent manner. These findings suggest that in vivo the enzyme activity is modulated by the lipid surrounding.

Adenosine Monophosphate↗
PubMed1981

Change of galactolipids and metabolism of fatty acids in the organotypic culture of myelinating mouse brain.

The concentrations of cerebrosides and sulfatides, myelin-characteristic galactolipids, can be determined in organotypic culture of newborn mouse cerebellum by high-performance liquid chromatography. These galactolipids can be detected at 9-days in vitro explants and increased steadily until the explants were more tan 3 weeks old. The levels of nonhydroxycerebroside, hydroxycerebroside, nonhydroxysulfatide, hydroxysulfatide, and monogalactosyl diacylglycerol were 0.3, 0.6, 0.3, 0.2, and 0.3 nmol/mg protein at 9 days in vitro, respectively, and 1.0, 2.7, 0.9, 0.4, and 0.6 at 21 days in vitro, respectively. When serum was removed from the feeding medium after 9 days, the levels of these lipids did not increase and myelination failed to occur. When a 17 day explant was kept in medium containing [1-14C]lignoceric acid for 4 days, considerable radioactivity was taken up by the explant and incorporated into nonhydroxy- and hydroxycerebrosides, sulfatides and sphingomyelin. Most of the radioactivity in the alpha-hydroxy fatty acids was found in cerebronic acid, the product of lignoceric acid alpha-hydroxylation. Similar explants also took up [1-14C]palmitic acid when it was added to the medium. The radioactivity was, however, mostly incorporated into neutral lipids and glycerophospholipids. These observations indicate that the cultured mouse cerebellum explants synthesize and accumulate myelin-characteristic lipids as does brain in vivo.

Aging↗
PubMed1985

Sex-specific difference of the galabiosylceramide level in the glycosphingolipids of human thyroid.

The glycosphingolipids of human thyroid were isolated and characterized by gas-liquid chromatography and sequential enzymic hydrolysis. The major purified components were identified as glucosyl- and galactosyl-ceramides, lactosyl- and galabiosylceramides, globotriaosyl- and globotetraosylceramides. The long-chain base analyses showed a high proportion of phytosphingosine in glycosylceramide and galabiosylceramide. Fatty acids in 22:0, 24:0, 24:1 prevailed, especially in the cerebroside fraction, with a significant content of alpha-hydroxylated species in galactosylceramide. Female thyroid had a very low content of galabiosylceramide and a higher content of glucosylceramide, as compared to male. No significant difference was found in the other neutral glycosphingolipids and gangliosides.

Carbohydrates↗