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PubMed1991

Time course dependent changes in contents and physical properties of glycolipid species in Rhodococcus rhodochrous.

The yield of trehalose dimycolate (TDM), the major glycolipid species elaborated by Rhodococcus rhodochrous, a producer of approx. C40-mycolic acid, was not constant in cells cultured for different periods of time. From cells collected at 24, 36, 72, 144 and 172 h of cultivation the following percentages of TDM in diethyl ether soluble lipids (DESL) were found: 10.8%, 23.4%, 10.0%, 9.0% and 5.0%, respectively. In turn, the cellular content accounted for approx. 0.6%, 1.2%, 0.9%, 0.6% and 0.2%, respectively. On the other hand, the yield of galactose monomycolate (GalMM), a minor glycolipid species maintained at approx. 3.4% in DESL during the different periods of time examined; this value represented about 0.3% of the cellular content. The melting temperatures of TDMs fell between 37 degrees C to approximately 97 degrees C with the lowest value from cells grown for 36 h, whereas the melting temperatures of the GalMMs were in a narrow range between 56 degrees C and 64 degrees C. The methyl ester derivatives of the constituent fatty acid moieties of DTMs and GalMMs migrated on thin layer chromatography like methyl esters of C40-C46 mycolic acids, therefore faster than methyl esters of C28-C34 mycolic acids but slower than methyl esters of C50-C56 mycolic acids. Further analysis of the products of pyrolysis of the methyl ester derivatives of the fatty acid moiety released from TDM after alkaline hydrolysis was carried out using gas chromatography combined mass spectrometry.(ABSTRACT TRUNCATED AT 250 WORDS)

Cord Factors↗
PubMed1991

A new class of potent antiproliferative glycolipids.

The synthesis and biological activities of a new class of antiproliferative glycolipids with an unexpected broad spectrum of activity, including a human multidrug resistant cell line, are described. Chemically these compounds are glycolipids derived from N-acetyl-D-glucosamine and glycyrrhetinic acid (beta-aglycone). Peptidation of the glucoacids allyl 3 beta-[[2-acetamido-3-O-[(R)-1-carboxyethyl]- 2-deoxy-4,6-O-isopropylidene-beta-D-glucopyranosyl]oxy]-11-oxo-12- oleanen-30-oate and (R,S)-2-methoxy-3-(octadecyloxy)propyl-2-acetamido-3-O-[(R)-1-carb oxyethyl]- 2-deoxy-4,6-O-isopropylidene-beta-D-glucopyranoside was successfully achieved after activation with O-benzotriazolyl-N,N,N',N' -tetramethyluronium hexafluorophosphate.

Acetylglucosamine↗
PubMed1993

Synthesis and characterization of a 13C-labeled alpha-mannosyl glycolipid analog from [13C]glucose.

A method is described for the synthesis of a [13C]alpha-mannosyl glycolipid analog from [13C]glucose. After acetylation and reduction of glucose (U-13C6, 30%) to tri-O-acetyl-D-glucal (U-13C6, 30%), addition of the nucleophile 2-[2-[2-[2-(tetradecyloxy)ethoxy]ethoxy]ethoxy]- ethanol (tetra-decyltetraglycol) yields the rearrangement product alpha-tetradecyltetraglycol 2,3-dideoxyl-4,6-di-O-acetyl-D-gluco- pyranoside (U-13C6, 30%). The rearrangement product is oxidized with osmium tetroxide to produce tetradecyltetraglycol alpha-mannoside (U-13C6, 30%). The interaction of the glycolipid with the plant lectin concanavalin A is characterized by a vesicle agglutination assay.

Agglutination↗
PubMed1994

Vesicles and other supramolecular systems from biocompatible synthetic glycolipids with hydrocarbon and/or fluorocarbon chains.

A series of double-tailed hydrocarbon and/or fluorocarbon glycolipids derived from galactose and glucose have been prepared. These compounds were obtained upon opening a lactono- and maltonolactone moiety by the amino group of either a glycine, glycylglycine or lysine residue. The carboxyl terminus of the glycyl and glycylglycine conjugates was further reacted with the appropriate double-tailed amine. In the case of lysine, the lactonamide conjugate was functionalized with a hydrocarbon and/or fluorocarbon fatty amine and acid, respectively. The ability of such glycolipids to disperse in water, the morphology of self-assemblies formed and the stability of the supramolecular structure obtained were shown to depend on the presence or absence and on the nature of the aminoacid spacer. Most of the compounds described were shown by conventional techniques (TEM, Cryo-TEM, LLS, etc.) to produce stable vesicular systems.

Animals↗
PubMed1982

Muscle glycolipids in inherited muscular dystrophy of chickens.

Gangliosides and neutral glycolipids of muscles from normal and dystrophic chickens were studied. Total glycolipid content of the degenerating muscles was higher than the normal muscles. In addition, the myopathic muscles contained a ganglioside which was absent in the unaffected muscles from normal and dystrophic chickens. Based on the thin-layer chromatographic mobility, treatment with neuraminidases from Vibrio cholerae and Arthrobacter ureafaciens, and reactivity of the asialo-derivative towards anti-ganglio-N-triaosylceramide antibody, the dystrophic-specific ganglioside was tentatively identified as GM2. Data obtained from young and old dystrophic chickens suggested a direct relationship of this ganglioside to muscular dystrophy.

Aging↗
PubMed1980

Protein, glycoprotein and glycolipid profiles of human arterial and venous tissues.

Selected normal human arteries and veins were solubilized with detergents, neutral salt buffers and organic solvents. Comparative sodium dodecyl sulphate polyacrylamide gels and thin layer chromatographic plates were developed and the patterns compared. The low molecular weight periodic acid--Schiff positive band seen in crude detergent extracts of vascular tissue is predominantly glycolipid. Arterial and venous tissues closely resemble one another with only minor differences in the glycoprotein and glycolipid patterns.

Arteries↗
PubMed1980

ELISA tests for antibodies against mycobacterial glycolipids.

ELISA tests with purified mycobacterial glycolipids and bovine heart cardiolipin are described. The possible clinical use of ELISA tests with mycobacterial glycolipids for the diagnosis of tuberculosis and other mycobacterioses is discussed.

Animals↗
PubMed1985

Use of a polysulfone membrane support for immunochemical analysis of a glycolipid from Mycobacterium leprae.

Polysulfone membranes have been used as a solid support for chromatography and immunoblotting of phenolic glycolipid I from Mycobacterium leprae. These membranes have an advantage over other supports such as nitrocellulose and silica gel in that very little non-specific background binding of antibodies occurs and assays can readily be carried out with IgM antibodies from human sera. An example of use of the polysulfone chromatography system for detection of phenolic glycolipid I in sera from leprosy patients is described.

Antigens, Bacterial↗
PubMedDate not supplied

Immune lysis of lipid vesicles containing myelin basic protein or glycolipid antigens by multiple sclerosis and normal sera.

We have compared the reactivity of sera from 34 multiple sclerosis (MS) patients and 32 normal (N) individuals with lipid vesicles containing myelin basic protein (BP) and several glycolipids reconstituted into a membrane environment. The ability of the sera to cause complement-mediated lysis of lipid vesicles containing these antigens was determined by measuring the release of a water-soluble spin label, tempocholine chloride, from the height of its electron spin resonance spectrum. Only 4 MS sera caused lysis of BP-containing vesicles which was comparable to that produced by specific antibody to BP. A number of both MS and N sera caused significant lysis of vesicles containing GM1 ganglioside or digalactosyldiglyceride. A few MS and N sera also caused significant lysis of vesicles containing GM2, GT1 and GD1a gangliosides. However, in no case was there a statistically significant difference between the mean lysis produced by MS and N sera. There was some overlap between the specific MS and N sera reactive to vesicles containing BP, GM1, GM2, and DGDG while a completely different group of MS and N sera were reactive to GT1 and GD1a gangliosides. This suggested that there was either antigenic cross reactivity between the two groups of glycolipids or two different origins of the immune response to the two groups of antigens. It was concluded that antibody-dependent complement fixation by these particular antigens, in the kind of lipid environment used, is not characteristic of or specific to MS.

Antigens↗
PubMed1989

Phospholipid and glycolipid synthesis in brain structures of Brattleboro rats.

The incorporation of labeled precursors in phospholipids and glycolipids was studied in discrete brain areas of rats with innate vasopressin deficiency (Brattleboro, DI) and intact Long Evans animals (LE). Tracer incorporation was found to be reduced in septal, hypothalamic and hippocampal phospholipids, but enhanced in the glycolipid fraction isolated from the hypothalamus and hippocampus of Brattleboro rats. The results indicate that inherited vasopressin deficit seems to be associated with altered lipid synthesis in some brain areas of the Brattleboro rat, suggesting a probability for impaired translation of chemical signals.

Acetates↗
PubMed1993

Effect of diabetes on levels of lipid peroxides and glycolipids in rat brain.

The effects of diabetes on levels of lipid peroxides and glycolipids in brain were studied in alloxan (18 mg/100 g body weight) diabetic rats. Free fatty acid (FFA) and malondialdehyde (MDA) levels were increased in the brains of diabetic animals. On the other hand, activities of the antioxidative enzymes catalase and superoxide dismutase (SOD) were decreased. The study also showed elevated levels of most of the glycolipid fractions except gangliosides, which were found to decrease in diabetic brain. Administration of insulin to diabetic animals results in the restoration of these parameters to normal levels. These changes observed in diabetic brain may be responsible for the increased frequency of stroke in diabetes.

Alloxan↗
PubMed1990

A glycolipid-specific monoclonal antibody modulates Fc epsilon receptor stimulation of mast cells.

In an effort to identify membrane components participating in coupling stimulus to secretion in mast cells, monoclonal antibodies were produced from spleen cells of mice immunized with plasma membranes isolated from rat mast cells of the RBL-2H3 line. The resultant mAbs were screened by their capacity to modulate the secretory response of these cells to crosslinking of their type 1 Fc epsilon receptor (Fc epsilon RI). Following this scheme, we obtained a hybridoma designated B17, which secretes an IgM-class mAb (B17) that binds to and modulates secretion from RBL-2H3 cells. By immunoblotting, B17 was shown to bind to a membrane component of low molecular weight, later identified as a glycolipid. While B17 partially inhibits IgE binding to RBL-2H3 cells, no noticeable inhibition of B17 binding by IgE was observed. mAb B17 does not cause any secretory response on its own, and its modulatory effect on Fc epsilon RI-mediated secretion is bimodal: it either enhances or inhibits secretion, depending on the B17 dose and also on the nature and dose of the agent used for crosslinking the Fc epsilon RI. When secretion was induced by IgE and suboptimal or optimal doses of multivalent antigen, B17 (2-80 nM) caused an increase in secretion. However, higher doses of B17 (greater than 150 nM) inhibited secretion. Secretion induced by supraoptimal doses of antigen, or by the Fc epsilon RI-specific mAb F4 was inhibited by B17 at all the dose range tested (2-200 nM). In contrast, B17 had no effect on secretion induced by Ca2+ ionophores. These results demonstrate that Fc epsilon RI function is modulated by a mAb binding to a membrane glycolipid.

Animals↗
PubMed1990

A family of glycolipid linked proteins in Eimeria tenella.

A number of proteins in Eimeria tenella are shown to possess a carbohydrate similar to that found on the carboxyl terminus of the variant surface glycoprotein from Trypanosoma brucei. In trypanosomes, this carbohydrate is part of a glycolipid structure responsible for membrane attachment. In common with the variant surface glycoprotein and with other glycolipid linked proteins, the E. tenella proteins were shown to be hydrophobic. Treatment with a crude lipase preparation from T. brucei modifies these proteins to a water-soluble form.

Animals↗
PubMed1990

Microbial glycolipid production under nitrogen limitation and resting cell conditions.

Rhodococcus erythropolis is able to synthesize an anionic trehalose-2,2',3,4-tetraester during cultivation on n-alkanes. Preconditions for an overproduction are nitrogen limitation, temperature- and pH-shift. The optimum carbon source was technical grade n-C-10, which led to 0.35 g g-1 of glycolipid per n-alkane. Electron microscopical observations showed that n-C-14,15 (technical grade) grown cells contained numerous lipid inclusions in contrast to n-C-10 (technical grade) grown cells. Nocardia corynebacteroides synthesizes a novel pentasaccharide lipid and as size products small amounts of trehalose-corynomycolates. Optimum precursors for overproduction are n-alkanes from n-tetradecane to n-hexadecane with yields in the range of 0.17 g g-1 of glycolipid per carbon source.

Biotechnology↗
PubMed1988

Glycoconjugates and cell adhesion: the adhesive proteins laminin, thrombospondin and von Willebrand's factor bind specifically to sulfated glycolipids.

The adhesive glycoproteins laminin, thrombospondin and von Willebrand's factor bind specifically and with high affinity to sulfated glycolipids, and it is this binding that probably accounts for their ability to agglutinate glutaraldehyde-fixed erythrocytes. The 3 proteins differ, however, in the effect of sulfated polysaccharides on their binding to sulfatides. Fucoidan strongly inhibits binding of both laminin and thrombospondin, but not of von Willebrand's factor, suggesting the involvement of laminin or thrombospondin or other unknown sulfatide-binding proteins in specific cell interactions that are also inhibited by fucoidan. Thrombospondin adsorbed onto plastic promotes the attachment and spreading of G361 melanoma cells. Interestingly, fucoidan and an antibody directed against the sulfatide-binding domain of thrombospondin selectively inhibit spreading but not attachment. Sulfatides, but not neutral glycolipids or gangliosides, when adsorbed onto plastic also promote attachment and spreading of G361 melanoma cells. Direct adhesion of G361 cells requires high densities of sulfatide. In the presence of laminin, however, specific adhesion of G361 cells to sulfatide is strongly stimulated and requires only low densities of adsorbed lipid, suggesting that laminin mediates adhesion by cross-linking receptors on the melanoma cell surface to sulfatide adsorbed onto the plastic. Although thrombospondin binds to sulfatide and to G361 cells, it does not enhance but rather inhibits direct and laminin-dependent G361 cell adhesion to sulfatide, presumably because it is unable to bind simultaneously to ligands on opposing surfaces. Thus, sulfated glycoconjugates participate in both laminin- and thrombospondin-mediated cell adhesion, but their mechanisms of interaction are different.

Animals↗
PubMed1989

IgM gammopathy and polyneuropathy react with an antigenic glycolipid present in human central nervous system.

An immunological mechanism may be responsible for the peripheral neuropathies associated with the IgM monoclonal gammopathies. Myelin-associated glycoprotein, and sulfated glucuronic acid-glycosphingolipids of the paragloboside type specific of peripheral nervous system (PNS), have been found to be targets for these antibodies. We report here on the presence of a glycolipid antigen present in central nervous system white matter in 7 of 12 patients with IgM monoclonal gammopathy and neuropathy whose IgM reacts also with the specific sulfated glycolipids of PNS. Immunodetection of the antibodies was performed on thin-layer plates after separation of the glycosphingolipids from peripheral nerve and white matter. The lipid antigen had a migration on thin-layer chromatography close to sulfogalactosylceramide but the sulfatide standard did not react with the monoclonal IgM.

Antigens, Surface↗
PubMed1978

Tissue distribution of EDTA encapsulated within liposomes containing glycolipids or brain phospholipids.

Multilameller liposomes were prepared with various asialoglycolipids, gangliosides, sialic acid, or brain phospholipids in the liposome membrane and with ethylenediaminetetraacetic acid (EDTA) encapsulated in the aqueous compartments. The liposomes containing glycolipids or sialic acid were prepared from a mixture of phosphatidylcholine, cholesterol, and one of the following test substances: galactocerebroside, glucocerebroside, galactocerebroside sulfate, mixed gangliosides, monosialoganglioside GM1, monosialoganglioside GM2, monosialoganglioside GM3, disialoganglioside GD1a, or sialic acid. The liposomes containing brain phospholipids were mixtures of either sphingomyelin and cholesterol or a brain total phospholipid extract and cholesterol. Distributions of 14C-labeled EDTA were determined in mouse tissues from 15 min to 6 h or 12 h after a single injection of liposome preparation. Liver uptake up encapsulated EDTA was lowest from all liposome preparations containing sialic acid or sialogangliosides, regardless of the amount of sialic acid moiety present or the identity of the particular ganglioside; highest uptake of encapsulated EDTA by liver was from liposomes containing galactocerebroside or brain phospholipids. Lungs and brain took up the largest amounts of EDTA from liposomes containing sphingomyelin and lesser amounts from liposomes containing GD1a. Use of mouse brain phospholipid extract to prepare liposomes did not increase uptake of encapsulated EDTA by the brain. EDTA in liposomes containing monosialogangliosides, brain phospholipids, galactocerebroside, or sialic acid was taken up well by spleen and marrow. Highest thymus uptake of encapsulated EDTA was from liposomes containing GD1a. These results demonstrate that inclusion of sialogangliosides in liposome membranes decreases uptake of liposomes by liver, thus making direction of encapsulated drugs to other organs more feasible. Liposomes containing glycolipids also have potential uses as probes of cell surface receptors.

Animals↗