Search PubMed⌕ Search

Biomedical subjects

A Dell

Publications and source records attributed to A Dell.

At least 163 records · Page 9Linked to original sources
PubMed1987

Glycosphingolipids of lectin-resistant mutants of the highly metastatic mouse tumor cell line, MDAY-D2.

Neutral and acidic glycolipids in MDAY-D2, a highly metastatic murine tumor cell line, were examined and compared with glycolipids of MDW4 and D33W25-1, two lectin-resistant mutants of MDAY-D2 from distinct genetic complementation classes. D33W25-1 remained highly metastatic while MDW4 cells were found to be nonmetastatic (Dennis, J. W., Donaghue, T., Florian, M., and Kerbel, R. S., Nature (Lond.), 292: 242-245, 1981 and Dennis, J. W. et al., Cancer Res., 46: 4594-4600, 1986). Glycolipid structures were identified by fast-atom bombardment mass spectrometry, methylation analysis, exoglycosidase treatment, and immunostaining. The metastatic MDAY-D2 was found to contain GM3, GM2, IV3GalNAc-GM1b, and high levels of GM1a, GM1b, and GD1a. MDW4 showed a 3-fold decrease in total ganglioside content compared to MDAY-D2 and a corresponding increase in the precursor, glucosylceramide. MDW4 was deficient in GM1 and accumulated GM2 and NeuNG-GM2, indicating a lack of gangliosides having NeuNAc alpha 2-3Gal beta 1-3 terminal sequence. Neosynthesis of GD3 was also observed in MDW4. The metastatic mutant D33W25-1 had a similar pattern of gangliosides as that found in MDAY-D2 cells with N-glycolyl rather than N-acetyl neuraminic acid. These results suggest that the metastatic property of these cell lines may be related to the level of ganglioside, and that the substitution of N-glycolyl for N-acetyl neuraminic acid does not reduce metastatic capacity.

Animals↗
PubMed1986

Isolation and characterization of poly-N-acetyllactosaminylceramides accumulated in the erythrocytes of congenital dyserythropoietic anemia type II patients.

Congenital dyserythropoietic anemia type II or hereditary erythroblastic polynuclearity with positive acidified serum test (HEMPAS) is a rare genetic disease inherited by a recessive mode. Previous studies on HEMPAS erythrocytes have shown that Band 3 and Band 4.5 glycoproteins were not glycosylated by lactosaminoglycans, while polylactosaminyl carbohydrates are accumulated as glycolipids (P. Scartezzini et al., Br J. Haematol., 51 (1982) 569; M.N. Fukuda et al., Br. J. Haematol., 56 (1984)55). Presently, we have isolated polylactosaminyl lipids from HEMPAS blood cells and analyzed their structures by fast atom bombardment-mass spectrometry (FAB-MS), methylation analysis, endo-beta-galactosidase digestion. The results indicate that polylactosaminyl lipids accumulated in HEMPAS erythrocytes are a species of poly-N-acetyllactosaminylceramides which are also present in normal erythrocytes, but at 7 approximately 9 times lower level. Isolated polylactosaminylceramides exhibit I-, i-, H- and Lex antigenic activities which suggest that the polylactosaminylceramides are derived from both erythrocytes and granulocytes.

Anemia, Dyserythropoietic, Congenital↗
PubMed1986

Asn-linked oligosaccharides in lectin-resistant tumor-cell mutants with varying metastatic potential.

MDW4, a wheat germ agglutinin-resistant mutant of the metastatic murine tumor MDAY D2 has previously been shown to be poorly metastatic when injected intravenously and non-metastatic when injected subcutaneously into syngeneic mice. W4EB8, a Bandeiraea simplicifolia (BSII) lectin-selected subline of MDW4 has previously been shown to be intermediate between that of MDAY-D2 and MDW4 cell for sensitivity to lectin and metastatic phenotype when injected intravenously into mice. The Asn-linked oligosaccharides from MDAY-D2, MDW4 and W4EB8 cells were released enzymatically with peptide N-glycosidase, reduced with tritiated sodium borohydride and fractionated by Concanavalin-A--Sepharose affinity chromatography and high-performance liquid chromatography (HPLC). Structures of the major fractions were determined by a combination of glycosidase digestion and sizing, gas-liquid chromatography/mass spectrometry and by proton nuclear magnetic resonance. Wild-type and mutant cells processed high-mannose-type structures to biantennary (GlcNAc)2(Man)3(GlcNAc)2. In MDAY-D2 cells this structure was processed further to sialylated tetra-antennary complex with polylactosamine-containing antennae terminating in either sialic acid or alpha 1-3-linked galactose. MDW4 cells had four or five times more (GlcNAc)2(Man)3(GlcNAc)2 than MDAY-D2 cells and a major component of tri-antennary (GlcNAc)3(Man)3(GlcNAc)2 (i.e. 2,2,6-substituted tri-mannosyl core) that was not found in wild-type cells. The partial revertant, W4EB8 had intermediate levels of mutant (GlcNAc)3(Man)3(GlcNAc)2 and sialylated complex-type carbohydrates. The results indicate that a shift in expression from incomplete complex type to sialylated tri/tetra-antennary complex-type carbohydrates in tumor cell may enhance the metastatic potential of tumor cells in the experimental metastasis assay. In addition, somatic cell hybridization analysis indicated that the defect in MDW4 cells was identical to that of the Chinese hamster ovary mutant Lec8: a deficiency in UDP-galactose transport into the golgi.

Asparagine↗
PubMed1986

Structures of O-linked oligosaccharides isolated from normal granulocytes, chronic myelogenous leukemia cells, and acute myelogenous leukemia cells.

O-Linked oligosaccharides were isolated from normal granulocytes, chronic myelogenous leukemia cells, and acute myelogenous leukemia cells by alkaline borohydride treatment. Oligosaccharides were fractionated by Sephadex G-50 gel filtration and QAE-Sephadex column chromatography, and their structures were elucidated by fast atom bombardment-mass spectrometry after permethylation and methylation analysis before and after specific exoglycosidase treatments. Results show that normal granulocytes and chronic myelogenous leukemia cells contain a series of O-linked oligosaccharides with the following structure, (formula: see text) where, in normal granulocytes n = 0 is major and n = 1 or 2, and thus polylactosaminyl oligosaccharides are present as minor components. However, these polylactosaminyl oligosaccharides were barely detectable in chronic myelogenous leukemia cells. On the other hand, acute myelogenous leukemia cells, which represent poorly differentiated myeloid cells, mainly contain short O-linked oligosaccharides with 2----6-linked sialic acid as follows. (formula: see text) These results suggest that structures of O-linked oligosaccharides vary in the different maturation stages along the same cell lineage.

Carbohydrate Conformation↗
PubMed1986

Enzymic degradation of the mycobacterial O-methyl-D-glucose polysaccharide by a Rhizopus-mold alpha amylase, an enzyme active on 6-O-methyl-amylo-oligosaccharides.

An enzyme activity that catalyzes hydrolysis of an alpha-(1----4)-linked 6-O-methyl-D-glucan was detected in, and purified from, Rhizopus oryzae mold. The enzyme acts like an alpha amylase and digests unmodified amylo-oligosaccharides 10 to 15 times as fast as it does the 6-O-methyl and 6-deoxy derivatives. When the limit product obtained by digesting the mycobacterial O-methyl-D-glucose polysaccharide with pancreatic alpha amylase and Aspergillus glucoamylase was further digested with the Rhizopus alpha amylase, di-, tri-, and tetra-saccharide fragments composed of alpha-(1----4)-linked 6-O-methyl-D-glucose were released. The rest of the molecule was recovered as oligosaccharides terminated by two, or three, alpha-(1----4)-linked 6-O-methyl-D-glucose residues.

Carbohydrate Conformation↗
PubMed1986

Structures of glycosphingolipids isolated from human embryonal carcinoma cells. The presence of mono- and disialosyl glycolipids with blood group type 1 sequence.

Structures of glycolipids present in the human embryonal carcinoma cell PA1, were elucidated by fast atom bombardment-mass spectrometry, methylation analysis, and exo- and endoglycosidase digestion. PA1 cells contain globotriaosylceramide, sialosylgangliotriaosylceramide, sialylated and nonsialylated lacto-N-neotetraosylceramide, and the following glycolipids with a blood group type 1 sequence: (formula; see text) The two former glycolipids, lacto-N-tetraosylceramide and sialosyllacto-N-tetraosylceramide, reacted with monoclonal antibodies, K21 and K4, respectively. K21 and K4 antigens are present in many of the human embryonal carcinoma cells but not in a variety of other cell lines, suggesting that sialylated but not fucosylated blood group type 1 sequences are characteristic markers for human embryonal carcinoma cells and malignant teratocarcinomas.

Antigens↗
PubMed1986

GM1 gangliosidosis (type 1) in a cat.

A kitten with clinical and morphological symptoms of a neurovisceral lysosomal-storage disease has been shown to have a marked deficiency of acidic beta-D-galactosidase in the brain, kidney and spleen. Chromatography on concanavalin A-Sepharose and inhibition studies with 2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine, a selective inhibitor of the neutral broad-specificity beta-D-galactosidase, have shown that the residual beta-D-galactosidase at pH 4.0 in the tissues of the affected cat is due to the neutral beta-D-galactosidase and that there is a complete deficiency of the acidic (lysosomal) beta-D-galactosidase. There is marked accumulation in all tissues and excretion in the urine of neutral oligosaccharides. Analysis of these oligosaccharides by fast-atom-bombardment mass spectrometry and g.l.c. suggests that they arise from the incomplete catabolism of N-glycans of glycoproteins. The ganglioside content of all the tissues is elevated, and it has been shown by t.l.c. that the concentration of a ganglioside fraction with a mobility similar to that of GM1 ganglioside is particularly increased. There is also some evidence of accumulation of glycosaminoglycans in the brain. The clinical symptoms, the complete deficiency of acidic beta-D-galactosidase and the storage products in visceral organs all suggest that this is a case of feline GM1-type gangliosidosis comparable with the severe infantile (Type 1) form of the disease in humans.

Alkaloids↗
PubMed1986

A novel mass spectrometric procedure to rapidly determine the position of O-acylated residues in the sequence of naturally occurring oligosaccharides.

A novel procedure is described for the assignment of the position of O-acylated residues in the sequence of oligosaccharides. The procedure is both rapid and sensitive and complements existing carbohydrate techniques. The procedure involves the use of derivatisation, using conditions under which naturally occurring O-acyl groups are stable, and subsequent fast atom bombardment mass spectrometric analysis of the derivatised product. The derivatisation enhances and directs fragmentation providing unambiguous sequence data. The protocol described is shown to be applicable to acetyl groups and to more complex acyl groups such as long chain fatty acids.

Acylation↗
PubMed1986

Structure of a novel sialylated fucosyl lacto-N-norhexaosylceramide isolated from chronic myelogenous leukemia cells.

A novel sialylated fucosyl glycolipid, which is present at an elevated level in chronic myelogenous leukemia cells, was isolated. The structure of this fucoganglioside was elucidated by methylation analysis, fast atom bombardment-mass spectrometry, and enzymatic degradation, followed by reaction with anti-Lex, Gal beta 1----4 (Fuc alpha 1----3) GlcNAc beta 1----, monoclonal antibody. The structure of this ganglioside was found to be: (Formula: see text). This structure is unique in that a fucose is attached to the internal N-acetylglucosamine but not to the subterminal N-acetylglucosamine. Since this glycolipid is apparently absent in normal granulocytes or acute myelogenous leukemia cells, it can be a specific marker for chronic myelogenous leukemia cells. Based on the structures of this fucoganglioside and normal granulocyte glycolipids, a biosynthetic pathway of extension, sialylation, followed by fucosylation is proposed.

Antibodies, Monoclonal↗
PubMed1986

Structural analysis of the major urinary oligosaccharides in feline alpha-mannosidosis.

Two homologous series of urinary oligosaccharides were identified by h.p.l.c. and fast-atom-bombardment mass spectrometry in feline alpha-mannosidosis. The predominant series has the composition Man2-8GlcNAc2 and a minor series the composition Man2-9GlcNAc. The structure of the most abundant oligosaccharide, which accounts for over 80% of the urinary oligosaccharide, was shown to be alpha-D-Manp(1----3)[alpha-D-Manp-(1----6)]beta-D-Manp -(1----4)-beta-D-GlcpNA c-(1----4)-D-GlcNAc by gas chromatography and mass spectrometry. Such a structure is consistent with the incomplete catabolism of complex N-linked glycans due to a deficiency of alpha-D-mannosidase in tissue lacking an endohexosaminidase activity.

Animals↗
PubMed1986

Characterization of acetylated and acetolyzed glycoprotein high-mannose core oligosaccharides by fast-atom-bombardment mass spectrometry.

Fast-atom-bombardment mass spectrometry has been applied to acetylated neutral and phosphorylated oligosaccharides from yeast glycoproteins and to their acetolysis products. Although acetylation increases the sample molecular weight and the complexity of the spectra, it also enhances the sensitivity of detection, is applicable to samples that contain salt, and is especially useful for analysis of phosphorylated derivatives. Acetylation by trifluoroacetic anhydride/glacial acetic acid is particularly convenient and can be done rapidly on a small amount of material. Acetolysis by acetic anhydride/glacial acetic acid/H2SO4 is done on the acetylated oligosaccharides, and the acetylated fragments are recovered by solvent extraction and immediately subjected to mass spectrometry. The methodology allows molecular weight determinations and sequence analysis by acetolysis to be carried out on a few micrograms of isolated oligosaccharide in a few hours.

Acetylation↗
PubMed1986

Host-Pathogen Interactions : XXIX. Oligogalacturonides Released from Sodium Polypectate by Endopolygalacturonic Acid Lyase Are Elicitors of Phytoalexins in Soybean.

Recent studies have demonstrated that an apparently homogeneous preparation of an alpha-1,4-d-endopolygalacturonic acid lyase (EC 4.2.2.2) isolated from the phytopathogenic bacterium Erwinia carotovora induced phytoalexin accumulation in cotyledons of soybean (Glycine max [L.] Merr. cv Wayne) and that this pectin-degrading enzyme released heat-stable elicitors of phytoalexins from soybean cell walls, citrus pectin, and sodium polypectate (KR Davis et al. 1984 Plant Physiol 74: 52-60). The present paper reports the purification, by anion-exchange chromatography on QAE-Sephadex columns followed by gel-permeation chromatography on a Bio-Gel P-6 column, of the two fractions with highest specific elicitor activity present in a crude elicitor-preparation obtained by lyase treatment of sodium polypectate. Structural analysis of the fraction with highest specific elicitor activity indicated that the major, if not only, component was a decasaccharide of alpha-1,4-d-galactosyluronic acid that contained the expected product of lyase cleavage, 4-deoxy-beta-l-5-threohexopyranos-4-enyluronic acid (4,5-unsaturated galactosyluronic acid), at the nonreducing terminus. This modified decagalacturonide fraction exhibited half-maximum and maximum elicitor activity at 1 microgram/cotyledon (6 micromolar) and 5 micrograms/cotyledon (32 micromolar) galactosyluronic acid equivalents, respectively. Reducing 90 to 95% of the carboxyl groups of the galactosyluronic acid residues abolished the elicitor activity of the decagalacturonide fraction. The second most elicitor-active fraction contained mostly undeca-alpha-1,4-d-galactosyluronic acid that contained 4,5-unsaturated galactosyluronic acid at the nonreducing termini. This fraction exhibited half-maximum and maximum elicitor activity at approximately 3 micrograms/cotyledon (17 micromolar) and 6 micrograms/cotyledon (34 micromolar) galactosyluronic acid equivalents, respectively. These results confirm and extend previous observations that oligogalacturonides derived from the pectic polysaccharides of plant cell walls can serve as regulatory molecules that induce phytoalexin accumulation in soybean. These results are consistent with the hypothesis that oligogalacturonides play a role in disease resistance in plants.

Journal Article↗
PubMed1986

The actions of N-terminal fragments of corticotrophin on steroidogenesis in dispersed rat adrenal cells in vitro.

The finding that the rat adrenal zona glomerulosa cell shows specific sensitivity to stimulation by alpha-MSH and related peptides has been confirmed both in vivo and in vitro, raising the possibility that alpha-MSH may have a physiological role in the control of glomerulosa function and aldosterone secretion. To define more closely the structural features which confer teh specificity of the glomerulosa response, other ACTH derived peptides have been tested for their specificity of actions on rat adrenal cells in vitro. The peptides tested were ACTH(5-24), ACTH(1-12), ACTH(1-14), ACTH(1-15), ACTH(1-16) and ACTH(1-17). Their actions were compared with those of alpha-MSH and ACTH(1-24). All of the ACTH-derived peptides stimulated glomerulosa corticosterone production with sensitivities similar to that of alpha-MSH; minimum effective concentration was 10 nmol/l. Also, like alpha-MSH, the shorter ACTH peptides stimulated aldosterone production only relatively weakly in these cells from animals on normal sodium intake. Only ACTH(5-24), ACTH(1-16) and ACTH(1-17) stimulated fasciculata/reticularis cells at concentrations up to 1 mumol/1. The actions of all of the shorter peptides were thus unlike those of ACTH(1-24) which stimulates both cell types with approximately equal sensitivity, and which furthermore strongly stimulates aldosterone production. The data suggest that the 18-24 region of the ACTH molecule contains the signal for a fasciculata/reticularis response, and the region 1-13 that for glomerulosa specificity. They confirm the view that, in the rat, alpha-MSH itself may be the specific pituitary glomerulosa-stimulating agent which much experimental work has predicted. They also indicate that synthetic ACTH(1-17) analogues should be used with caution.

Adrenal Cortex↗
PubMed1985

Structural studies of the O-antigen polysaccharides of Klebsiella O5 and Escherichia coli O8.

The O-antigen polysaccharides of Klebsiella serotype O5 and Escherichia coli serotype O8 are serologically very similar or identical. The structures of these two polysaccharides have now been re-investigated. N.m.r. spectroscopy, chromium trioxide oxidation, hydrolysis with a specific phage enzyme, and f.a.b. mass spectrometry were the principal methods used. It is concluded that the O-antigen has the following structure, in which D-Man3Me is 3-O-methyl-D-mannose and n is approximately 10. (Formula: see text) Biosynthetic studies indicate that these antigens are synthesised by addition of D-mannopyranosyl groups to the "non-reducing" end of the mannan chain, and it seems possible that addition of a 3-O-methyl-D-mannopyranosyl group involves termination.

Carbohydrate Conformation↗
PubMed1985

Structures of sialylated fucosyl polylactosaminoglycans isolated from chronic myelogenous leukemia cells.

Polylactosaminoglycans were isolated from human chronic myelogenous leukemia cells and their structures were elucidated. The lactosaminoglycan saccharides were isolated by hydrazinolysis and fractionated by QAE-Sephadex. The structures of fractionated oligosaccharides were analyzed by fast atom bombardment-mass spectrometry and methylation before and after treatment with specific exoglycosidases, such as alpha 2----3 specific neuraminidase. Based on these experiments, the structures of sialyl polylactosaminoglycans of chronic myelogenous leukemia cells were found to contain the following unique structure which is absent in normal mature granulocytes: (formula; see text) In addition to this, chronic myelogenous leukemia polylactosaminoglycans can be distinguished from normal granulocyte polylactosaminoglycans by the following characteristics. Leukemic polylactosaminoglycans are (a) shorter, (b) more highly sialylated and contain fully sialylated, tetrasialosyl polylactosaminoglycans, (c) are less fucosylated at C-3 of N-acetylglucosamine of polylactosaminyl side chains, and (d) contain a significant amount of sialyl Lex, NeuNAc alpha 2----3Gal beta 1----4(Fuc alpha 1----3)GlcNAc beta 1----3, structure. These results indicate that chronic myelogenous leukemia cells express unique polylactosaminoglycan structures which are distinct from normal mature granulocytes.

Amino Sugars↗
PubMed1985

A novel mass spectrometric procedure for the rapid determination of the types of carbohydrate chains present in glycoproteins: application to alpha-galactosidase I from Vicia faba seeds.

A fast atom bombardment mass spectrometric protocol has been developed to determine the type of oligosaccharide chain present in glycoproteins. The procedure is based on acetolysis of the intact glycoconjugate, extraction of the peracetylated carbohydrate fragments and analysis by fast atom bombardment mass spectrometry. The molecular ions present in the FAB spectra uniquely define the composition of the oligosaccharides with respect to hexose, aminohexose and sialic acid content. High mannose oligosaccharides yield a series of peracetylated hexose oligomers whereas complex-type oligosaccharides afford a series of N-acetyl-lactosamine containing species. Fucosylation is usually not detected but sialylated oligosaccharides are readily identified and the type of sialic acid is also defined. The method has been tested on three glycoproteins of known structure - fetuin, ribonuclease B and erythrocyte Band 3 - and on a glycoprotein of unknown structure - alpha-galactosidase I, an enzyme lectin from Vicia faba. The latter is shown to contain high mannose carbohydrate chains.

Anion Exchange Protein 1, Erythrocyte↗