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K S Rostand

Publications and source records attributed to K S Rostand.

8 recordsLinked to original sources
PubMed1997

Fucosylation of disaccharide precursors of sialyl LewisX inhibit selectin-mediated cell adhesion.

We showed previously that HL-60 and F9 mouse embryonal carcinoma cells will take up and deblock peracetylated Galbeta1-4GlcNAcbeta-O-naphthalenemethanol (Galbeta1-4GlcNAc-NM) and use the disaccharide as a primer of oligosaccharide chains (Sarkar, A. K., Fritz, T. A., Taylor, W. H., and Esko, J. D. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 3323-3327). We now report that another disaccharide, acetylated GlcNAcbeta1-3Gal-naphthalenemethanol (GlcNAcbeta1-3Gal-NM), has even greater potency and that both compounds will inhibit sialyl LewisX (sLex)-dependent cell adhesion. When fed to U937 cells, acetylated forms of Galbeta1-4GlcNAc-NM and GlcNAcbeta1-3Gal-NM primed oligosaccharides in a dose-dependent manner. Analysis of compounds assembled on Galbeta1-4GlcNAc-NM showed only one product, namely Galbeta1-4(Fucalpha1-3)GlcNAc-NM. In contrast, GlcNAcbeta1-3Gal-NM generated Galbeta1-4GlcNAcbeta1-3Gal-NM, Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Gal-NM, NeuAcalpha2-3Galbeta1-4GlcNAcbeta1-3Gal-NM, and NeuAcalpha2-3Galbeta1-4(Fucalpha1-3)GlcNAcbeta1- 3Gal-NM. Both compounds decreased the incorporation of [3H]fucose into cellular glycoconjugates, without affecting the incorporation of [3H]mannosamine, a precursor of sialic acid residues. Moreover, the overall extent of sialylation was not affected based on the reactivity of cells to fluorescein isothiocyanate-conjugated Maackia amurensis lectin. Priming inhibited expression of sLex on cell surface glycoconjugates, which reduced E-selectin-dependent cell adhesion to tumor necrosis factor-alpha-activated human umbilical vein endothelial cells. GlcNAcbeta1-3Gal-NM and Galbeta1-4GlcNAc-NM represent starting points for making enzyme-specific, site-directed inhibitors of glycosyltransferases that could act in living cells.

Acetylation↗
PubMed1993

Cholesterol and cholesterol esters: host receptors for Pseudomonas aeruginosa adherence.

Bacterial adherence to tissues is a necessary step in infection and results from interactions between surface molecules on the bacteria (adhesins) and plasma membrane receptors on host cells. Using a clinical isolate of Pseudomonas aeruginosa, we have examined the receptors required for adherence to Chinese hamster ovary (CHO) cells. In mutant CHO cell lines and mucin-producing lung epithelial cell lines, adherence did not depend on glycoproteins, glycolipids, or proteoglycans. Treating cells with glutaraldehyde and proteases also did not affect adherence. However, treating cells with ethanol diminished adherence and resulted in removal of factors that would facilitate binding of bacteria when coated on plastic culture plates. These factors were purified by solvent extraction and silica gel chromatography and were identified as cholesterol and cholesterol esters by coelution with authentic standards, gas chromatography, 1H NMR, and mass spectrometry. Bacterial adherence was reduced to wild-type CHO cells treated with Lovastatin and to cholesterol-requiring insect cells grown in cholesterol-deficient medium, suggesting that the bacteria bound to plasma membrane cholesterol. Thus, this clinical isolate of Pseudomonas uses cholesterol and cholesterol esters for adherence. We propose that binding to cholesterol and cholesterol esters may affect the pathogenicity of similar Pseudomonas strains.

Animals↗
PubMed1988

Tumor formation dependent on proteoglycan biosynthesis.

The role proteoglycans play in tumor formation was examined by measuring the tumorigenicity of proteoglycan-deficient Chinese hamster ovary cell mutants in nude mice. When 10(7) cells were injected subcutaneously, mutants with less than about 15% of the wild-type level of proteoglycan synthesis did not produce tumors. Mutants defective in the synthesis of heparan sulfate proteoglycans also did not form tumors, whereas mutants with altered chondroitin sulfate proteoglycans were tumorigenic. Tumors arose from mixtures of wild-type and nontumorigenic mutant cells and contained both cell types, suggesting that wild-type cell proteoglycans enabled mutant cells to survive. The failure of heparan sulfate-deficient mutants to form tumors depended on the ability of the host to mount a B cell-mediated immune reaction.

Animals↗
PubMed1986

Articular cartilage proteoglycans from normal and osteoarthritic mice.

Articular cartilage proteoglycans from an osteoarthritic mouse strain, STR/IN, were labeled in vivo with 35S-sulfate and characterized with respect to extractability, ability to aggregate, size of monomer and glycosaminoglycan chains, sulfation of glycosaminoglycans, relative amounts of chondroitin-4 sulfate and chondroitin-6 sulfate, and link proteins. The proportion of 35S-labeled proteoglycans extractable by 0.4M guanidine hydrochloride was the same in control and osteoarthritic animals. However, a greater proportion was extractable by 4M guanidine hydrochloride in the STR/IN animals as compared with the control mice. The ability of the 35S-proteoglycans to aggregate was comparable in controls and osteoarthritic mice, as judged by their exclusion on Sepharose CL-2B. Monomers from both controls and osteoarthritic animals eluted from Sepharose CL-2B with a KAV of 0.47. Glycosaminoglycans from control and osteoarthritic animals eluted from Sepharose CL-6B with a KAV of 0.63, and no differences in sulfation or chondroitin-4 sulfate content were found. Aggregates were immunoprecipitated with link protein-specific antiserum, and only link protein 2 was found in aggregates from control and osteoarthritic animals.

Animals↗
PubMed1986

Isolation, characterization, and amino-terminal amino acid sequence analysis of human neutrophil cathepsin G from normal donors.

Human neutrophil cathepsin G from normal donors has been purified 82-fold using an isolation procedure which included sequential sodium chloride extraction, Aprotonin-Sepharose affinity chromatography, CM-cellulose ion-exchange chromatography, and AcA44 gel filtration chromatography. The inclusion of this last purification step was crucial for separating inactive lower molecular weight species from the active forms of neutrophil cathepsin G and resulted in a higher specific activity of the final preparation. SDS polyacrylamide gradient gel electrophoresis of the purified reduced protein demonstrated three discrete polypeptides of Mr 31,000, 30,000, and 29,500. Peptide analysis of tryptic digests indicated that these three polypeptides are structurally related to each other and represent microheterogeneity of the purified protein. The cathepsin G peptide maps were distinctly different from the peptide maps of neutrophil elastase. The apparent isoelectric points of these forms as determined by two-dimensional electrophoresis was approximately 8.0. Utilizing microsequencing techniques, the first 25 residues of normal neutrophil cathepsin G have been determined and shown to be identical (except for residue 11) with the sequence of 21 residues of cathepsin G isolated from leukemic myeloid cells. A high degree of homology was found when the amino-terminal regions of neutrophil cathepsin G, rat mast cell protease II (65%) and two human serine proteinases, factor D (52%) and neutrophil elastase (48%), were compared. A precipitating monospecific antiserum to cathepsin G was produced by repeated immunizations of guinea pigs. This antiserum has been used in immunoblotting experiments to demonstrate that the intracellular form(s) of this enzyme is the same approximate Mr as the purified enzyme, and to develop a solid-phase radioimmunoassay for measuring neutrophil cathepsin G in the range 5-50 ng/ml.

Amino Acid Sequence↗