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Biomedical subjects

R K Yu

Publications and source records attributed to R K Yu.

At least 199 records · Page 11Linked to original sources
PubMed1985

The neuropathy of plasma cell dyscrasia: binding of IgM M-proteins to peripheral nerve glycolipids.

In some patients with neuropathy and plasma cell dyscrasia, the M-proteins bind to peripheral nerves. Binding of M-proteins to peripheral nerve glycolipids was examined by immunostaining after thin-layer chromatography. The IgM from 16 patients with anti-MAG M-proteins bound to the same two glycolipid bands in peripheral nerve. The IgM that bound to the glycolipids had the same idiotype as the anti-MAG M-protein, indicating that it was the M-protein that bound to both glycolipids. The reactive glycolipids did not contain sialic acid and were not gangliosides. No immunostaining of peripheral nerve glycolipids was observed with IgM from patients with neuropathy and IgM M-proteins that did not bind to MAG, and the anti-MAG antibodies did not bind to brain glycolipids. Anti-MAG M-proteins probably bind to the same or closely related carbohydrate determinants that are shared by a number of glycoproteins and glycolipids of peripheral nerve.

Antibodies↗
PubMed1984

Fast atom bombardment mass spectrometry of glycosphingolipids. Glycosphingolipids containing neutral sugars.

Natural and synthetic glycosphingolipids containing neutral sugars have been analyzed by positive and negative ion fast atom bombardment mass spectrometry. Basic structural characterization including saccharide size and sequence and ceramide composition is possible on the basis of the fragment ions observed. The degree of fragmentation could be increased by using higher sample concentrations and lower fast atom beam energies. Commercially available synthetic compounds that had been presumed to be pure were shown to contain homologous fatty acids. Mixtures of glycosphingolipids such as those obtained from Gaucher's spleen and from human erythrocytes can be characterized and quantitated.

Carbohydrates↗
PubMed1984

Isolation and characterization of a novel phytosphingosine-containing GM2 ganglioside from mullet roe (Mugil cephalus).

The major ganglioside from the roe of striped mullet (Mugil cephalus) has been isolated and purified. Compositional analysis of this ganglioside revealed that it contained an equimolar ratio of the following residues: N-acetylneuraminic acid, N-acetylgalactosamine, galactose, glucose, and the long-chain base. Further structural studies by sequential enzymatic hydrolysis, permethylation analysis, and proton NMR spectroscopy indicated that the structure of the oligosaccharide moiety was identical to that of GM2 ganglioside from human brain: GalNAc beta 1----4Gal beta 1----4(3----2 alpha NeuAc)-Glc----ceramide. This ganglioside, however, differed from brain GM2 in its ceramide portion. The most striking differences are the presence of large amounts of C18 and C20 phytosphingosine (over 80% of the total long-chain bases) and the preponderance of monounsaturated alpha-hydroxy fatty acids (over 80%). Such a phytosphingosine-containing GM2 ganglioside has never been reported.

Animals↗
PubMed1984

Gangliosides of normal and neoplastic human melanocytes.

The major ganglioside component isolated from diploid human melanocytes is sialosyllactosylceramide (GM3 86-91% of total sialic acid). The corresponding disialo derivative (GD3) is found as a minor component (2-6% of total sialic acid) in the membranes of these cells. In human melanoma cells, grown in tissue culture, GD3 is the predominant ganglioside component (48-63% of total sialic acid). Withdrawal of TPA from the culture medium of normal melanocytes or addition of TPA to the medium of melanoma cells had no significant effect on GM3/GD3 ratios. We conclude that the difference between the composition of gangliosides is related to the normal vs transformed phenotypes of melanocytes.

Cell Line↗
PubMed1984

Chemical-ionization mass spectra of the permethylated sialo-oligosaccharides liberated from gangliosides.

Permethylated mono- and di-sialo-oligosaccharides liberated from several parent gangliosides have been examined by chemical-ionization mass spectrometry with ammonia as the reagent gas in order to elucidate their structures. Several major fragment-ions, in addition to both the protonated and ammonium adduct molecular-ions, may be readily assigned without interference from the ceramide moiety. Sialic acid-containing di-, tri-, and tetra-saccharide ions can be clearly observed and used to determine the sugar residue to which the sialic acid residue is attached. The neutral-sugar skeletons produced by the loss of sialic acid give rise to both the protonated and the ammonium adduct ions; in the case of tetrasaccharides, these are further degraded to produce di- and tri-saccharide ions. These characteristic ions are useful for the determination of the number of sugar residues and their sequence in an oligosaccharide structure. The chemical-ionization mass spectra of GM3- and GM1-oligosaccharides with isobutane show the ions corresponding to each monosaccharide residue. These results indicate that chemical-ionization mass spectrometry is highly useful in determining the complete sugar-sequence of gangliosides.

Brain Chemistry↗
PubMed1984

Fatty acid and long-chain base composition of gangliosides isolated from adult human brain.

A series of major and minor ganglioside species were isolated from a single human adult brain and analyzed for their lipophilic composition. Hematosides, GM3 and GD3, each showing double bands on thin-layer chromatograms, were separated into the upper band and lower band fractions to be analyzed for the heterogeneity of their ceramide moieties. The upper band fractions of GM3 and GD3 were found to contain relatively high amounts of longer-chain fatty acids (C20-C26), whereas the lower band fractions contained high amounts of shorter-chain fatty acids (C16-C18). Compared to other gangliosides which contain hexosamine, the two hematosides contained a smaller proportion of stearic acid. The proportion of 4-eicosasphingenine was found to increase with increasing sialic acid content in gangliosides. These findings suggest that, in the biosynthesis of various gangliosides, N-acetylhexosamine is preferentially transferred to hematosides rich in stearic acid, and sialic acid residues are preferentially transferred to 4-eicosasphingenine-containing species.

Brain Chemistry↗
PubMed1984

Interaction of ganglioside GM1 and myelin basic protein studied by carbon-13 and proton nuclear magnetic resonance spectroscopy.

The interaction of the myelin basic protein (MBP) and the major endogenous ganglioside GM1 in myelin of the central nervous system has been investigated using both 500-MHz 1H and 67.89 MHz 13C NMR. Titration of MBP by GM1 resulted in 13C NMR signal shifts for the I1e and His residues of MBP at a GM1/MBP mole ratio of one or less. The carbohydrate head group of GM1 was also found to be perturbed. 1H NMR results obtained in a similar manner demonstrated the perturbation of His and Phe residues. At a GM1/MBP mole ratio of 0.5, small perturbation of Trp #116 was observed, and at mole ratios of two and beyond significant involvement of Phe residues and methylated Arg #107 was found. Met #167 was more perturbed than Met #20; hence, more extensive interaction of the lipid is occurring with the C-terminus of the protein than with the N-terminus. No resonances from GM1 bound to MBP at mole ratios of up to one appeared in the spectra. However, as the GM1/MBP mole ratio was increased to eight or greater a major conformational change of MBP was detected. An upfield shift of the GM1 midchain methylene resonance was observed for the GM1/MBP complex. This observation provides strong evidence that the state of GM1 interacting with MBP is different from that of GM1 micelles. The number of saturable GM1 binding sites on MBP is estimated to be four. The data also favor a rapid exchange between bound GM1 and GM1 micelles. Interaction of MBP with the oligosaccharide derived from GM1 was found to be weaker than with GM1. Based on our data, a model for the interaction can be proposed: the first GM1 molecule is bound to the protein molecule through its head group and hydrocarbon chains, followed by the formation of a GM1/MBP complex with a concomitant conformational change of MBP as more GM1 is added.

Animals↗
PubMed1984

Cellular localization of gangliosides in the mouse cerebellum: analysis using neurological mutants.

We have used genetic dissection to study the cellular localization of gangliosides in the mouse cerebellum. This method employs a series of mouse mutations that destroy specific populations of cerebellar neurons at precise stages of development. By correlating the well documented histological changes occurring in these mutants with changes in ganglioside composition, we have obtained strong evidence for a non-random cellular distribution of gangliosides. Most notably, GD1a is more enriched in granule cells that in Purkinje cells, whereas the opposite is true for GT1a. GD3, on the other hand, is heavily enriched in reactive glia and may serve as a useful biochemical marker for the presence of reactive glia in neurological disease. The continued study of gangliosides in the various mouse mutants will help elucidate their cellular localization in the CNS.

Aging↗
PubMed1984

Recent advances in structural analysis of gangliosides: primary and secondary structures.

High-field (500 MHz) proton NMR has been used to elucidate the primary and secondary structures of glycosphingolipids (GSLs). Using 2-D J-correlated spectroscopy (2-D SECSY) which establishes scalar couplings of protons, the monosaccharide composition, anomeric configuration and aglycon structures of a GSL can be established. 2-D nuclear Overhauser effect spectroscopy (2-D NOE) then establishes through-space intra- and inter-residue couplings of cross-relaxing protons. We have found that each anomeric proton is involved in NOE couplings with inter- and intra-residue protons. The inter-residue coupling, resulting from interaction of protons across the glycosidic linkage, establishes the n-1 sugar residue and specific glycosidation site to which the n-residue is linked. When such information is known for each residue and is combined, the sequence of the core oligosaccharide is obtained. The sialylation-induced glycosidation shift is then used to establish the site of sialic acid residue attachment in a ganglioside molecule. We have also observed that the anomeric proton inter-residue NOE couplings can be used to suggest the preferred conformation of an oligosaccharide. We have found that the oligosaccharide residue of globoside exists in a unique and rather rigid conformation which could be stabilized by hydrogen bonds and van der Waals interactions. Since GSLs are known to have a receptor role and are implicated in cell-cell recognition, enzyme-substrate interaction and antigen-antibody interaction, the determination of their conformation should be useful in understanding their biological functions.

Animals↗
PubMed1984

Isolation and characterization of a novel disialoganglioside from bovine adrenal medulla.

A novel GDlb ganglioside which contains only N-glycolylneuraminic acid was isolated from bovine adrenal medulla by DEAE-Sephadex A-25 and Iatrobeads column chromatography. The concentration of this ganglioside was 0.9 nmol lipid-bound sialic acid per gram fresh tissue, which accounted for 2.7% of the disialoganglioside fraction. The structure was elucidated by sugar analysis, neuraminidase digestion, and permethylation studies. The complete structure of this ganglioside was identified as GDlb (NeuGc)2 or II3 (NeuGc)2-GgOse4Cer.

Adrenal Medulla↗
PubMed1984

Genetic analysis of cerebellar lipids in mice susceptible to audiogenic seizures.

The major neutral and acidic cerebellar lipids were studied in audiogenic seizure (AGS)-resistant C57BL/6 (B6) and AGS-susceptible DBA/2J (D2) mice. These cerebellar lipids were also studied in the D2.B6- Iasb congenic mice and in the B6D2F1 hybrids that are mostly AGS resistant. Except for the Iasb gene, which inhibits AGS susceptibility, the D2.B6- Iasb congenic mice are genetically similar to the D2 mice. Because subtle abnormalities in the chemical structure of membranes may underlie epilepsy, we wanted to determine if AGS susceptibility was associated with abnormalities in the distribution of cerebellar lipids. A new method for the analysis of total brain lipids was used in this study. Slight, but significant, differences were found between the B6 and D2 strains for the concentrations (microgram/100 mg wet weight) of sphingomyelin, phosphatidylcholine, and cerebrosides. However, these differences may not be associated with differences in AGS susceptibility since the concentrations of these lipids in the AGS-resistant D2.B6- Iasb and B6D2F1 mice were more similar to the D2 than the B6 concentrations. The expression of Iasb is not responsible for the lipid differences found between the B6 and D2 mice.

Acoustic Stimulation↗
PubMed1984

Genetic analysis of serum thyroxine content and audiogenic seizures in recombinant inbred and congenic strains of mice.

We previously proposed that the audiogenic seizure (AGS) susceptibility of 21 +/- 1-day-old DBA/2 (D2) mice may result from an early postnatal elevation in serum thyroxine (T4) concentration. In the present study we used seven C57 X DBA (BXD) recombinant inbred strains and the D2.B6-Iasb congenic strain to study the association between serum T4 content and susceptibility to AGS. The D2.B6-Iasb congenic mice are genetically similar to the D2 mice except for the Iasb gene, which inhibits AGS susceptibility. The total and estimated free serum T4 concentrations in these strains at 14 +/- 1 days of age were compared with the previously determined AGS susceptibilities of these strains at 21 +/- 1 days of age. We found no significant correlations between serum T4 concentration and AGS susceptibility in these strains. It is unlikely, therefore, that inherited differences in neonatal serum T4 content are directly responsible for differences in susceptibility to AGS in 21 +/- 1-day-old mice. The mechanisms by which the experimental manipulation of serum T4 content influences AGS susceptibility are discussed.

Acoustic Stimulation↗
PubMed1984

GD3 ganglioside is a glycolipid characteristic of immature neuroectodermal cells.

Biochemical studies have indicated that the disialoganglioside, GD3, is a major glycolipid component of the immature vertebrate CNS, but a minor element within the mature CNS. We have investigated its cellular localization in rat CNS by immunofluorescence using a mouse monoclonal antibody that recognizes GD3. In tissue sections of postnatal CNS, the antibody bound to cells in several areas known to contain immature neuroectodermal populations: the subventricular zone beneath the lateral ventricle, the external germinative layer of the cerebellar cortex, and the dentate gyrus of the hippocampus. GD3-containing cells were also found in developing white matter of the forebrain and cerebellar folia. Using a double-label immunofluorescence method, we found that the GD3-positive white matter cells did not express the astrocytic marker, glial fibrillary acidic protein. In adult rat CNS, we could not detect antibody binding to neurons or glia. Scattered GD3-positive cells were apparent in the adult subventricular zone. Our results indicate that GD3 ganglioside is a membrane component characteristically expressed in the rat CNS by neuroectodermal stem cells, both neuronal and glial precursors.

Animals↗
PubMed1984

Autoradiography of ganglioside antigens separated by high-performance thin-layer chromatography with their antibodies.

An improved method is described for the detection of ganglioside antigens with the antibodies on thin-layer chromatograms. The method involves the following steps: Separation of gangliosides on a high-performance thin-layer chromatographic plate, application of antibody solution, and detection of bound antibody with [125I]staphylococcal protein A. Using specific antibodies against gangliosides GM4, GM1, GD3, and asialo GM1 ganglioside, the method allowed positive identification of these antigens on thin-layer plates. It also provides a convenient means of assessing the specificity of an anti-glycolipid antibody.

Antibodies↗
PubMed1984

Cellular distribution of gangliosides in the developing mouse cerebellum: analysis using the staggerer mutant.

The distribution of cerebellar gangliosides was studied in staggerer (sg/sg) mutant mice, where the majority of granule cells die after completing their migration across the molecular layer. In addition, the external granule cell layer in sg/sg mice persists longer than in normal mice. Moreover, in the sg/sg cerebellum, Purkinje cells are significantly reduced in number, and almost none have tertiary branchlet spines. The loss of Purkinje cells and granule cells in sg/sg mice is accompanied by an early-onset reactive gliosis that continues through adulthood. By correlating changes in ganglioside composition with the well-documented histological events of cerebellar development in normal and sg/sg mice, we obtained strong evidence for a nonrandom cellular distribution of gangliosides. The sharpest reduction in the GD1a content of sg/sg cerebellum occurred after 15 days of age, coincident with granule cell loss. GT1a, on the other hand, was significantly reduced from 15 through 150 days in the sg/sg mice. GD3 is a major ganglioside of the undifferentiated granule cell, but it becomes rapidly displaced by the more complex gangliosides with the onset of granule cell maturation. In the sg/sg mice, GD3 persisted at abnormally high levels from 15 to 28 days and then accumulated through adulthood. These findings, and those from other cerebellar mouse mutants, suggest that GD1a is enriched in granule cells and that GT1a is enriched in Purkinje cells. Our findings also suggest that GT1a is more concentrated in branchlet spines than in other regions of the Purkinje cell membrane. GT1b appears to be enriched in both granule cells and Purkinje cells, whereas GM1 appears to be enriched in myelin. Furthermore, the apparent persistence of the embryonic ganglioside GD3 in sg/sg mice results from an early-onset reactive gliosis, together with a partial retardation in granule cell maturation. The accumulation of GD3 beyond 28 days reflects the continued accretion of GD3 in reactive glia.

Animals↗
PubMed1984

Characterization of gangliosides by direct inlet chemical ionization mass spectrometry.

Permethylated derivatives of N-acetylneuraminic acid-containing GM3, N-glycolylneuraminic acid-containing GM3, GD1a, and GD1b, were analyzed by direct inlet ammonia chemical ionization (CI) mass spectrometry. These compounds were found to yield simple fragmentations, prominent fragment ions in the high mass region, and characteristic fragment ions corresponding to the cleavage of glycosidic linkages. This method also provides detailed information on the carbohydrate sequence and lipophilic composition in gangliosides.

Adrenal Glands↗
PubMed1983

The monoclonal antibody A2B5 is specific to ganglioside GQ1c.

The neural specific monoclonal antibody A2B5 was found to interact with GQ1c but not with Gq1b, nor did it interact with other glycolipids such as GM1, GD1a, GD1b, GT1a, GT1b and GA1. Since GQ1c is enriched in embryonic chicken brains but not in adult chicken brains, this antibody should be useful as a tool in assessing the role of GQ1c in neuronal maturation.

Animals↗