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PubMedDate not supplied

[Brain sulfatides and cerebrosides in experimental hyperphenylalaninemia].

Effect of acute and chronic hyperphenylalaninemia (HPA) on metabolism of various fractions of sulfatides and cerebrosides from rat brain was studied. Content of all the fractions was distinctly decreased under the effect of HPA. The specific radioactivity in the majority of the sulfatide and cerebroside fractions decreased more significantly in chronic HPA. The data obtained suggest that synthesis of sulfatides and cerebrosides was inhibited in experimental hyperphenylalaninemia.

Acute Disease↗
PubMedDate not supplied

[Ion permeability of cerebroside and sphingomyelin bilayer membranes].

Ionic conductivity of bilayer membranes formed of cerebrosides and sphingomeylins isolated from bovine brains and its dependence on medium pH were studied. It was found that conductivity of the membranes from cerebrosides in KC1, CaCl2 solutions is 2-3 orders, and from sphingomyelin 1-2 orders higher than that of bilayers from lecithin and phospholipids. Both in cerebroside and sphingomyelin membranes the conductivity depended on medium pH, unlike the bilayer membranes of the brain and liver phospholipids.

Calcium Chloride↗
PubMed1979

Synthesis of ceramides and cerebrosides containing both alpha-hydroxy and nonhydroxy fatty acids from lignoceroyl-CoA by rat brain microsomes.

The conversion of [1-14C]lignoceroyl-CoA to nonhydroxy- and alpha-hydroxyceramides and cerebrosides by brain microsomes of developing rat in the presence of NADPH was investigated. A new technique of thin layer chromatography for the separation of these lipids and unreacted substrate was developed for this assay. The synthesis of nonhydroxy- and hydroxyceramides was significantly stimulated by the addition of heat-stable factor, a factor which is essential in the alpha-hydroxylation of free lignoceric acid (I. Singh and Y. Kishimoto, manuscript in preparation). The addition of sphingosine also stimulated the ceramide synthesis to a great extent. When the microsomes or heat-stable factor were crude, the ceramides formed were further converted to cerebrosides, apparently by UDP-galactose contamination. The purification of these subcellular components resulted in the formation of only ceramides which, in turn, were converted to cerebrosides by the addition of UDP-galactose. These observations indicate that hydroxyceramide is the precursor of hydroxycerebroside and is formed by alpha-hydroxylation of lignoceroyl-CoA and N-acylation of sphingosine. However, lignoceroyl-CoA, like free lignoceric acid, does not appear to be the immediate substrate of the alpha-hydroxylation.

Acyl Coenzyme A↗
PubMed2000

Comparative analysis of ceramide structural modification found in fungal cerebrosides by electrospray tandem mass spectrometry with low energy collision-induced dissociation of Li+ adduct ions.

Fungal cerebrosides (monohexosylceramides, or CMHs) exhibit a number of ceramide structural modifications not found in mammalian glycosphingolipids, which present additional challenges for their complete characterization. The use of Li+ cationization, in conjunction with electrospray ionization mass spectrometry and low energy collision-induced dissociation tandem mass spectrometry (ESI-MS/CID-MS), was found to be particularly effective for detailed structural analysis of complex fungal CMHs, especially minor components present in mixtures at extremely low abundance. A substantial increase in both sensitivity and fragmentation was observed on collision-induced dissociation of [M + Li]+ versus [M + Na]+ of the same CMH components analyzed under similar conditions. The effects of particular modifications on fragmentation were first systematically evaluated by analysis of a wide variety of standard CMHs expressing progressively more functionalized ceramides. These included bovine brain galactocerebrosides with non-hydroxy and 2-hydroxy fatty N-acylation; a plant glucocerebroside having (E/Z)-delta8 in addition to (E)-delta4 unsaturation of the sphingoid base; and a pair of fungal cerebrosides known to be further modified by a branching 9-methyl group on the sphingoid moiety, and to have a 2-hydroxy fatty N-acyl moiety either fully saturated or (E)-delta3 unsaturated. The method was then applied to characterization of both major and minor components in CMH fractions from a non-pathogenic mycelial fungus, Aspergillus niger; and from pathogenic strains of Candida albicans (yeast form); three Cryptococcus spp. (all yeast forms); and Paracoccidioides brasiliensis (both yeast and mycelium forms). The major components of all species examined differed primarily (and widely) in the level of 2-hydroxy fatty N-acyl delta3 unsaturation, but among the minor components a significant degree of additional structural diversity was observed, based on differences in sphingoid or N-acyl chain length, as well as on the presence or absence of the sphingoid delta8 unsaturation or 9-methyl group. Some variants were isobaric, and were not uniformly present in all species, affirming the need for MS/CID-MS analysis for full characterization of all components in a fungal CMH fraction. The diversity in ceramide distribution observed may reflect significant species-specific differences among fungi with respect to cerebroside biosynthesis and function.

Acylation↗
PubMed1993

Vesicular transport of myelin proteolipid and cerebroside sulfates to the myelin membrane.

The possibility that cerebroside sulfates and myelin proteolipid (PLP) could be simultaneously located in transport vesicles destined to be assembled in myelin was investigated in the brain of 20 day old rats. The brain was homogenized and fractionated according to Burkart et al. (J Biol Chem 257:3151-3156, 1982) to obtain a microsomal fraction that was further subfractionated in a linear sucrose density gradient following the procedure of Siegrist et al. (J Neurochem 33:497-504, 1979) to obtain a vesicular fraction which has been shown to transport cerebroside sulfates (Burkart et al., as above). This fraction was associated with acid hydrolase activity and had a lipid composition different from that of myelin and microsomal fractions. Studied by slab gel electrophoresis, dot blot, and Western blot analysis, using a highly specific anti-PLP antibody, it was found to contain myelin PLP. In view of previous findings of several laboratories including our own, the presence of myelin proteolipid in a vesicular fraction which is related to the transport of cerebroside sulfates gives further support to the hypothesis that the delivery of both constituents to the myelin membrane could be associated.

Animals↗
PubMed1989

Correlation of the dispersion state of pyrene cerebroside sulfate and its uptake and degradation by cultured cells.

This study aimed at increasing the efficiency and shortening the time required for administering cerebroside sulfate to cultured cells. For this purpose several modes of dispersion of a fluorescent derivative of cerebroside sulfate (sulfatide), in which the natural fatty acid has been replaced by pyrenedodecanoic acid (P12), were incubated with the cells. This fluorescent derivative of cerebroside sulfate (P12-CS) was introduced into the growth medium of the cells using the three following modes of dispersion: (1) P12-CS was dissolved in dimethylsulfoxide and added to the medium, (2) it was precomplexed with serum albumin or (3) incorporated into small, unilamellar vesicles (SUV) of phosphatidylcholine. With each of these respective modes of dispersion, the P12-CS was incubated for periods up to 48 h with cultured lymphoblasts or fibroblasts. Uptake by the cells could be determined by recording directly the cell-associated fluorescence, using a suspension of washed intact cells. The cell lipids were subsequently extracted with mixtures of chloroform/methanol and their fluorescence recorded. When related to the incubation time, uptake of P12-CS by the cells increased continuously using each of the above dispersions. The appearance of fluorescence at 475 nm ('excimer') and the ratio of this to the monomolecular fluorescence at 378 nm ('E/M') could be used as a measure for the presence of the internalized P12-CS in aggregated or fully dispersed states. These values (i.e., E/M), recorded on the suspensions of intact cells were rather high using the aqueous dispersions, intermediate values were observed using the SUV and rather low E/M values (0.5 or less) were observed using the preformed albumin-(P12-CS) complexes. Increasing the mole ratio of albumin to P12-CS (i.e., from 1:2 to 2:1 m/m), decreased the quantity of sulfatide which was taken up by the cells but also further decreased the E/M ratio, suggesting a fully dispersed state of the pyrene lipid within the cell. This indicated that, using an optimal albumin to P12-CS ratio of 1-2 (or its equivalent values in fetal calf serum) permitted an influx of single molecules of P12-CS into the cells. After 48 h, about 50% of the fluorescence of skin fibroblasts was found in metabolic degradation products of P12-CS. The parallel value for fibroblasts derived from a patient with metachromatic leukodystrophy was only about 5%. Appearance of the excimeric emission of a dispersion of P12-CS in water permitted estimation of its critical micellar concentration as being 7.5 x 10(-7) M.

Cell Line↗
PubMed1999

Characterization of sphingolipids from mycopathogens: factors correlating with expression of 2-hydroxy fatty acyl (E)-Delta 3-unsaturation in cerebrosides of Paracoccidioides brasiliensis and Aspergillus fumigatus.

Significant differences exist between mammals and fungi with respect to glycosphingolipid (GSL) structure and biosynthesis. Thus, these compounds, as well as the cellular machinery regulating their expression, have considerable potential as targets for the diagnosis and treatment of fungal diseases. In this study, the major neutral GSL components extracted from both yeast and mycelium forms of the thermally dimorphic mycopathogen Paracoccidioides brasiliensis were purified and characterized by 1H and 13C NMR spectroscopy, ESI-MS and ESI-MS/CID-MS, and GC-MS. The major GSLs of both forms were identified as beta-glucopyranosylceramides (GlcCer) having (4E, 8E)-9-methyl-4,8-sphingadienine as long chain base in combination with either N-2'-hydroxyoctadecanoate or N-2'-hydroxy-(E)-3'-octadecenoate. The mycelium form GlcCer had both fatty acids in a approximately 1:1 ratio, while that of the yeast form had on average only approximately 15% of the (E)-Delta 3-unsaturated fatty acid. Cerebrosides from two strains of Aspergillus fumigatus (237 and ATCC 9197) expressing both GalCer and GlcCer were also purified and characterized by similar methods. The GalCer fractions were found to have approximately 70% and approximately 90% N-2'-hydroxy-(E)-3'-octadecenoate, respectively, in the two strains. In contrast, the GlcCer fractions had N-2'-hydroxy-(E)-3'-octadecenoate at only approximately 20 and approximately 50%, respectively. The remainder in all cases was the saturated 2-OH fatty acid, which has not been previously reported in cerebrosides from A. fumigatus. The availability of detailed structures of both glycosylinositol phosphorylceramides [Levery, S. B., Toledo, M. S., Straus, A. H., and Takahashi, H. K. (1998) Biochemistry 37, 8764-8775] and cerebrosides from P. brasiliensis revealed parallel quantitative differences in expression between yeast and mycelium forms, as well as a striking general partitioning of ceramide structure between the two classes of GSLs. These results are discussed with respect to possible functional roles for fungal sphingolipids, particularly as they relate to the morphological transitions exhibited by P. brasiliensis.

Acylation↗
PubMed1987

Arylsulphatase activity and cerebroside sulphates in the frog oviduct during the reproductive cycle.

The presence of arylsulphatase A and cerebroside sulphates in different tracts of Rana esculenta oviduct during different phases of the reproductive cycle were investigated by histochemical and biochemical procedures. The results indicate that enzyme activity shows seasonal fluctuations connected with the phase of the sexual cycle. The concentrations of cerebroside sulphates (the natural substrates of arylsulphatase A) is related to the activity of this hydrolytic enzyme. The role of arylsulphatase A activity in regulating the substrate concentration, and particularly that of sulphatides, is discussed.

Animals↗
PubMed1991

Synthesis and characterization of NBD-PS: a fluorescent analog of cerebroside arylsulfatase A deficiency disorders.

N-[7-Nitrobenz-2-oxa-1,3-diazol-4-yl]psychosine sulfate (NBD-PS), a fluorescent analog of cerebroside sulfate (CS), was synthesized and tested as an alternative to the radiolabeled forms of CS used for assaying arylsulfatase A (ASA) in its physiological role as a cerebroside sulfate sulfohydrolase. NBD-PS simulates the natural substrate for ASA. Protocols have been developed for its use in differentiating low enzyme activities in diagnostic samples. Hydrolysis of NBD-PS is specific for ASA and optimal assay parameters were identical to those determined for CS. Differentiations between each of the major phenotypes for ASA activity were possible in the set of samples tested. One particular advantage was the ability to discriminate between individuals exhibiting arylsulfatase A pseudodeficiency and the truly deficient individuals with metachromatic leukodystrophy. Differential diagnosis was possible with fibroblast extracts by an assay that is more sensitive than procedures employing radioisotopes. Reaction products may be analyzed quantitatively by HPLC, or semiquantitatively with TLC. NBD-PS provides a simpler, safer, and more cost-effective means of performing natural substrate enzyme assays for ASA. Phenotyping with the fluorescence assay is an effective alternative to the laborious radioactive CS preparations and tissue culture loading studies that have previously been necessary.

4-Chloro-7-nitrobenzofurazan↗
PubMed1980

Prenatal diagnosis of metachromatic leukodystrophy in a family with pseudo arylsulfatase A deficiency by the cerebroside sulfate loading test.

Prenatal diagnosis was requested by a family at risk for metachromatic leukodystrophy (MLD). An examination of the family leukocyte arylsulfatase A profile revealed that the mother had pseudo arylsulfatase A deficiency. Cultured amniotic fluid cells were deficient in arylsulfatase A, so two possibilities were indicated: the fetus was affected with MLD or had the pseudodeficiency phenotype. The only known biochemical test to differentiate the two enzyme deficient phenotypes is cerebroside sulfate loading of growing fibroblasts. The pseudodeficient cells hydrolyze the incorporated sulfatide as efficiently as control cells, whereas MLD cells show no hydrolysis. Application of this test to the at risk cultured amniotic fluid cells resulted in appreciable uptake of the sulfolipid, but no hydrolysis. Control amniotic fluid cell cultures hydrolyzed 82 to 95% of the incorporated sulfatide. Therefore, an affected fetus was indicated. Fibroblasts derived from the aborted fetus showed a deficiency of arylsulfatase A and a similar inability to hydrolyze cerebroside sulfate in the loading test. The loading technique allowed the prenatal diagnosis of MLD when the arylsulfatase A analysis was equivocal.

Amniotic Fluid↗
PubMed2001

Comparative lipid binding study on the cerebroside sulfate activator (saposin B).

Cerebroside sulfate activator (saposin B) is a small protein involved in glycosphingolipid metabolism. It binds certain membrane lipids, making them available to water-soluble enzymes. Defects in this protein are responsible for a form of metachromatic leukodystropy, a progressive neurodegenerative condition. The protein participates in the catabolism of a number of lipids but does show lipid binding selectivity. However, the basis of this selectivity is unclear. Here we assess the relative binding of a number of lipids compared to cerebroside sulfate (sulfatide). We utilize a competitive binding paradigm, in which the lipids compete for protein under favorable conditions and are then switched to a condition in which the complex is stable. This study is unique in that a single molecular species of the activator is employed, and an expanded selection of natural and semisynthetic membrane lipids is surveyed. No simple "binding rule" can be ascertained from these data, but ligands with longer and/or more complex lipoidal and polar adducts appear to be favored.

Animals↗
PubMed1976

The fatty acid composition of major glycosphingolipids (cerebrosides and sulfatides) in human cerebral white matter measured by a simple micromethod.

A micromethod for the investigation of the fatty acid composition of myelin glycosphingolipids (cerebrosides and sulfatides) suitable for general application in the investigation of neurological disorders, especially demyelinating diseases, is presented. Using the lipids extracted from 1 g of material these are freed of phospholipids by Florisil column chromatography and separated by thin-layer chromatography into 2 cerebroside and sulfatide fractions which are analyzed individually. The results obtained from the white matter of 13 normal adult brains are distributed within a narrow range which is most pronounced for the group of long chain fatty acids. Our results also agree with those quoted from literature.

Adolescent↗
PubMed1981

Incorporation of 14C-linoleic acid in cerebrosides of psoriatic and normal human skin.

Psoriasis is marked by loss of glycoalyx. Glycocalyx is composed of glycoproteins and glycolipids such as cerebrosides. It was shown that the incorporation of 14C-linoleic acid in cerebrosides of normal and psoriatic human skin is different. In psoriatic epidermis and corium the turnover of this fatty acid is significantly elevated. It is suggested that in psoriasis the epidermal cell is not able to build up a regular carbohydrate sequences of lipids because the false carbohydrate chain activates the degradation of glycolipids and in compensating for the increased degradation raises the synthesis rate of glycolipids.

Carbon Radioisotopes↗
PubMed1981

Levels and syntheses of cerebrosides and sulfatides in subcellular fractions of jimpy mutants.

During the period of brain development, the levels of nonhydroxy- and hydroxycerebrosides in the cytosol from brains of jimpy mutants were determined by high-performance liquid chromatography and compared to those in the rest of the particulates from the same brains as well as those in the littermate controls. The concentrations of cerebrosides in jimpy brain preparations were much lower than in controls at all ages. In another experiment, [U-14C]glucose was injected intraperitoneally into jimpy mutants and their littermate controls. The amounts of radioactivity incorporated into cerebrosides and sulfatides in brain cytosol, the microsome-rich fraction, and the rest of the heavier particles were determined. Although the total radioactivity incorporated into these lipids was much lower in jimpy, the specific activities were 2-3 times the control value in all subcellular fractions.

Animals↗
PubMed1986

Metabolism of cerebrosides and sulfatides in the nervous system of Xenopus tadpole during metamorphosis.

Xenopus laevis tadpoles undergoing metamorphosis were used to study the turnover of cerebrosides and sulfatides in the nervous system of the frog. Tadpoles at the beginning of metamorphosis were treated by intraperitoneal injection with [U-14C]glucose and radioactivity incorporated into galactosphingolipids of brain and tail was measured after various times. The specific activity of brain cerebrosides increased rapidly for the first 24 hr after injection, reached a plateau after 48 hr, and then declined 40% by 7 days. The specific activity of sulfatides changed somewhat more slowly. Hydroxy fatty acid-containing galactosphingolipids had nearly twice the specific activity compared with their nonhydroxy counterparts in brain. Despite the complete regression of tail nerve cord, metabolism of glycosphingolipids in this tissue also indicated active synthesis as well as degradation during this period. The specific activities of these lipids were similar and all reached a peak 24 hr after injection. Examination of the components of these galactosphingolipids disclosed that only a small fraction (7-25%) of the radioactivity was in the galactose moiety in both brain and tail. The ratios of the radioactivity in fatty acid to that in the sphingoid base were much higher for hydroxycerebroside and hydroxysulfatide than for the nonhydroxy isomers.

Animals↗
PubMed1986

Late-onset Krabbe disease initially diagnosed as cerebroside sulfatase activator deficiency.

Clinical and biochemical findings in a male subject with progressive encephalopathy and peripheral neuropathy are presented. Early development was normal. At age 3.5 years, he had seizures associated with fever. Subsequently, there was progressive neurologic deterioration. A CT brain scan at age 4 years, 2 months demonstrated multiple areas of variable density in the white matter. There was mild slowing of nerve conduction velocities and a sural nerve biopsy revealed segmental demyelinative neuropathy. Metachromatic leukodystrophy was suspected, but arylsulfatase A activity in leukocytes and fibroblasts was in the normal range. The cerebroside sulfate loading test on intact cultured fibroblasts showed attenuated hydrolysis leading to a tentative diagnosis of cerebroside sulfatase activator deficiency. However, the attenuated response of proband fibroblasts was not normalized by supplementation with activator in a reproducible manner, and urine showed hyperexcretion rather than deficiency of activator. Ultimately, an assay for galactosylceramide beta-galactosidase activity established a deficiency of this enzyme leading to the diagnosis of late-onset Krabbe disease.

Cerebroside-Sulfatase↗
PubMed1978

Effects of storage conditions on rat brain ethanolamine glycerophospholipids, cerebrosides, and cholesterol.

The effects of storage on rat brain lipid composition were studied in terms of ethanolamine glycerophospholipid, cerebrosides, and cholesterol. Rat brains were stored at several combinations of temperature and time. Storage conditions were: 2 hr at room temperature, 12 hr of refrigeration, and a sequence of both of these conditions. Two-dimensional thin layer chromatography followed by colorimetric analyses of eluted lipids were used to determine molar ratios of phosphatidylethanolamine, ethanolamine plasmalogen, lysophosphatidylethanolamine, and cerebrosides. Cholesterol was also determined. These studies revealed small but significant increases in lysophosphatidylethanolamine in all three cases. A slight increase was also noted in the apparent molar proportion of cholesterol.

Animals↗
PubMed1986

An improved method for the separation of molecular species of cerebrosides.

A method employing reversed-phase high performance liquid chromatography (HPLC) has been developed for the analysis of molecular species of underivatized cerebrosides. By using a high carbon (20%) C18-silica bead column, monohexosylceramides isolated from bovine brain and Japanese quail intestine could each be separated into 42 and 56 peaks, respectively, and could subsequently be recovered. Under our analytical conditions, underivatized cerebrosides with 24:1 and 22:0 fatty acids were completely separated by single step HPLC. Each of the molecular species was then analyzed by high performance thin layer chromatography and gas chromatography-mass spectrometry (or fast atom bombardment mass spectrometry). This analytical method permits the complete identification of molecular species of glycosphingolipids.

Animals↗