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Biomedical subjects

A Hasegawa

Publications and source records attributed to A Hasegawa.

At least 19 recordsLinked to original sources
PubMed1992

Sphingolipids are essential for the growth of Chinese hamster ovary cells. Restoration of the growth of a mutant defective in sphingoid base biosynthesis by exogenous sphingolipids.

We previously isolated a temperature-sensitive Chinese hamster ovary cell mutant (strain SPB-1) with thermolabile serine palmitoyltransferase, which is involved in the first step of sphingolipid synthesis (Hanada, K., Nishijima, M., and Akamatsu, Y. (1990) J. Biol. Chem. 265, 22137-22142). In this study, sphingolipid-deficient culture medium was used to examine the effect of exogenous sphingolipids on the cell growth of SPB-1. When cultivated in the sphingolipid-deficient medium, SPB-1 cells ceased growing at non-permissive temperatures. Under these conditions, de novo sphingolipid synthesis ceased in the SPB-1 cells, resulting in a decrease in levels of sphingomyelin and ganglioside sialyl lactosylceramide (GM3), whereas the parental CHO-K1 cells grew logarithmically with normal sphingolipid synthesis. Exogenous sphingosine restored the contents of both sphingomyelin and GM3 in the SPB-1 cells near to the parental levels through metabolic utilization and allowed the mutant cells to grow even at the non-permissive temperature. Similarly, exogenous sphingomyelin restored the sphingomyelin levels and only partly the GM3 levels and also suppressed the temperature-sensitivity of the SPB-1 cell growth. In contrast, exogenous glucosylceramide, which restored the GM3 levels but not the sphingomyelin levels, failed to suppress the temperature sensitivity of the SPB-1 cell growth. Combination of exogenous sphingomyelin with ceramide, glucosylceramide, GM3, or sphingoid bases did not show any synergistic or additive effect on the SPB-1 cell growth enhancement, compared with sphingomyelin alone. The results indicated that the temperature sensitivity of the SPB-1 cell growth was due to the lack of cellular sphingolipids, possibly that of sphingomyelin.

Acyltransferases↗
PubMed1992

High affinity binding of the leucocyte adhesion molecule L-selectin to 3'-sulphated-Le(a) and -Le(x) oligosaccharides and the predominance of sulphate in this interaction demonstrated by binding studies with a series of lipid-linked oligosaccharides.

The binding of the leucocyte adhesion molecule L-selectin has been investigated toward several structurally defined lipid-linked oligosaccharides immobilized on silica gel chromatograms or plastic wells. In both assay systems the 3'-sulphated Le(a)/Le(x) type tetrasaccharides [formula: see text] were more strongly bound than 3'-sialyl analogues. A considerable binding was observed to the 3'-sulphated oligosaccharide backbone in the absence of fucose but not to a 3'-sialyl analogue or fuco-oligosaccharide analogues lacking sulphate or sialic acid. Affinity for other sulphated saccharides: 3'-sulphoglucuronyl neolactotetraosyl ceramide and glycolipids with sulphate 3'-linked to terminal or sub-terminal galactose or N-acetylgalactosamine was detected in the chromatogram assay only. These studies, together with earlier reports that L-selectin binding to endothelium is inhibited by sulphatide, highlight the relative importance of sulphate in the adhesive specificity of this protein.

Animals↗
PubMed1992

Synthesis of disialoganglioside GD1 alpha and its positional isomer.

The first total syntheses of disialoganglioside GD1 alpha and its alpha 2-6 positional isomer are described. Suitably protected pentasaccharide derivatives, derived from known pentasaccharide precursors, were selected as the glycosyl acceptors. Using our facile method of stereoselective alpha-glycosidation of sialic acid, these acceptors were coupled with methyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-D-galact o-2- nonulopyranosid)onate in acetonitrile medium in the presence of dimethyl(methylthio)sulfonium triflate (DMTST) to get the desired di-alpha-sialyl hexasaccharide derivatives in moderate yields. The hexasaccharide trichloroacetimidates upon coupling with (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol gave the corresponding beta-linked sphingosine glycosides in high yields. These were subjected in sequence to selective reduction of the azido group and coupling of the thus formed amino group with octadecanoic acid, O-deacylation, and saponification of the methyl ester groups to obtain ganglioside GD1 alpha and its positional isomer having the main-chain residue 2-6 linked.

Carbohydrate Conformation↗
PubMed1992

Covalent binding of morphine to isolated rat hepatocytes.

Incubation of [3H]morphine with isolated hepatocytes caused covalent binding of [3H]-morphine to hepatocellular proteins. Sulfhydryl compounds protected against morphine-induced toxicity and decreased covalent binding. Analysis of covalently bound proteins in the cytosol by electrophoresis indicated that covalently bound radiolabel was associated with macromolecules greater than 25 kDa and increased throughout the incubation. In contrast, covalent binding to the particulate fraction was highly selectively associated with three protein bands of 50-53 and 33 kDa. Covalent binding of morphine to particulate fraction proteins was observed in hepatocytes which exhibited cellular damage. We conclude that the covalent binding of morphine to protein is associated with morphine-induced cytotoxicity.

Animals↗
PubMed1992

Inhibition of tumor-induced angiogenesis by the administration of recombinant interferon-gamma followed by a synthetic lipid-A subunit analogue (GLA-60).

The effect of the administration of recombinant interferon-gamma (rIFN-gamma) and a synthetic lipid A subunit analog (GLA-60) on angiogenesis induced by B16-BL6 melanoma was examined in syngeneic C57BL/6 mice. Intravenous administration of rIFN-gamma followed by GLA-60 (referred to as rIFN-gamma/GLA-60) induced endogenous production of tumor necrosis factor (TNF). This treatment on day 3 after tumor inoculation caused a marked decrease in the number of vessels oriented towards the tumor mass (angiogenic response) and tumor size over a period of 9 days. In contrast, neither rIFN-gamma nor GLA-60 alone, nor GLA-60/rIFN-gamma (reverse sequence of administration), which is unable to induce the production of TNF in the serum, had any effect. Sera induced by the treatment with rIFN-gamma/GLA-60, and recombinant TNF, inhibited the in vitro growth of lung endothelial cells which is considered to be one of the essential events in tumor neovascularization. Multiple i.v. treatments with rIFN-gamma/GLA-60 on days 5, 8 and 11 after s.c. implantation of tumor significantly inhibited primary tumor growth by the amputation time (day 20) and lung metastasis of B16-BL6 cells on day 34, while other treatment modalities had no such effect. Our results indicate that inhibition of lung-tumor metastasis by rIFN-gamma/GLA-60 treatment may be partly due to the inhibition of tumor-associated angiogenesis.

Animals↗
PubMed1992

Synthesis of the methyl thioglycosides of deoxy-N-acetyl-neuraminic acids for use as glycosyl donors.

Methyl 2-thioglycoside derivatives of 4-, 7-, 8-, and 9-deoxy-N-acetylneuraminic acids have been prepared as glycosyl donors for the synthesis of sialoglycoconjates. Reduction of a (phenoxy)thiocarbonyl group, selectively introduced at the 4 position of methyl [2-(trimethylsilyl)ethyl 5-acetamido-3,5-dideoxy-8,9-O-isopropylidene-D- glycero-alpha-D-galacto-2-nonulopyranosid]onate (1), gave the 4-deoxy compound, which was transformed via O-deisopropylidenation, acetylation, selective removal of the 2-(trimethylsilyl)ethyl group, subsequent acetylation, and displacement of the 2-acetoxy group by a methylthio group, into methyl (methyl 5-acetamido-7,8,9-tri-O-acetyl-3,4,5-trideoxy-2-thio-D-manno-2- nonulopyranosid)onate (17). Methyl [2-(trimethylsilyl)ethyl 5-acetamido-8,9-di-O-acetyl-4-O-benzoyl- 3,5,7-trideoxy-alpha-D-galacto-2-nonulopyranosid]onate, prepared from 1 in five steps, and methyl [2-(trimethylsilyl)ethyl 5-acetamido-4,7,9-tri-O-acetyl-3,5,8-trideoxy-alpha-D-galacto-2- nonulopyranosid]onate, prepared from 1 in six steps, were converted via selective removal of the 2-(trimethylsilyl)ethyl group, O-acetylation, and displacement of the 2-acetoxy group by a methylthio group as described for 17, into the corresponding methyl 7- and 8-deoxy-2-thioglycosides. Reductive dechlorination of methyl [2-(trimethylsilyl)ethyl 5-acetamido-4,7-di-O-benzoyl-9-chloro-3,5,9-trideoxy-D-glycero-alpha-D-g alacto- 2-nonulopyranosid]onate, prepared from methyl [2-(trimethylsilyl)ethyl 5-acetamido-3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosid++ +]onate by selective 9-O-tert-butyldimethylsilylation, benzoylation, removal of the 9-silyl group, and selective chlorination, gave a 9-deoxy compound. This was transformed, via O-debenzoylation, O-acetylation, selective removal of the 2(trimethylsilyl)ethyl group, 2-O-acetylation, 2-chlorination, displacement with potassium thioacetate, selective S-deacetylation, and S-methylation, into the methyl 2-thio-alpha-glycoside of 9-deoxy-N-acetylneuraminic acid.

Carbohydrate Conformation↗
PubMed1992

Synthesis of a series of ganglioside GM3 analogs containing a deoxy-N-acetylneuraminic acid residue.

Ganglioside GM3 analogs containing 4-, 7-, 8-, and 9-deoxy-N-acetylneuraminic acids in the place of N-acetylneuraminic acid (Neu5Ac) have been synthesized. Glycosylation of 2-(trimethylsilyl)ethyl O-(6-O-benzoyl-beta-D-galactopyranosyl)-(1----4)-2,6-di- O-benzoyl-beta-D-glucopyranoside with the methyl 2-thioglycoside derivatives of the respective deoxy-N-acetylneuraminic acids, using dimethyl(methylthio)sulfonium triflate as a promoter, gave the four required 2-(trimethylsilyl)ethyl alpha-sialosyl-(2----3b)-beta-lactosides. These were converted via O-acetylation, selective removal of the 2-(trimethylsilyl)ethyl group, and subsequent imidate formation, into the corresponding alpha-sialosyl-(2----3b)-alpha-lactose trichloroacetimidates 15, 17, 19, and 21. Glycosylation of (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol with 15, 17, 19, and 21 in the presence of boron trifluoride etherate afforded the expected beta glycosides, which were transformed in good yields, via selective reduction of the azido group, coupling with octadecanoic acid, O-deacylation, and de-esterification, into the target compounds.

Carbohydrate Conformation↗
PubMed1992

Sialyl Lewis(x) antigen as defined by monoclonal antibody AM-3 is a marker of dysplasia in the colonic adenoma-carcinoma sequence.

Monoclonal antibody AM-3 (MAb AM-3) raised against a sialomucin from human colorectal carcinoma has previously been shown to define a carbohydrate epitope, which is detectable by immunocytochemistry on all investigated colonic carcinomas and is expressed in correlation with the grade of dysplasia in colonic adenomas (Hanski et al., J. Clin. Pathol., 43: 379-385, 1990). Epitope analyses in solid-phase enzyme immunoassays revealed that AM-3 antibody recognizes the sialylated Lewis(x) sequence on a branched O-linked glycan and its reductively cleaved alditol from human amniotic mucins. In comparative binding and binding inhibition studies MAbs AM-3 and CSLEX1 displayed reciprocal affinities to mucins versus gangliosides. Correspondingly, the weaker binding activities of AM-3 versus CSLEX to III3-alpha Fuc-IV3-alpha NeuAc-nLcOse4-Cer or to monogangliosides from human granulocytes were measured. Gangliosides from a human colon carcinoma were recognized by MAb CSLEX1 exhibiting a broader specificity to various sialyl-Lewis(x) antigens and by MAb FH6 reactive to sialyl-dimeric Lewis(x) antigen, but not by MAb AM-3. In conclusion, MAb AM-3 is distinguished from other sialyl Lewis(x)-specific MAbs by its selective reactivity to mucin-carried epitopes on the monomeric antigen.

Adenoma↗
PubMed1992

Synthesis of an S-(alpha-sialosyl)-(2----9)-O-(alpha-sialosyl)-(2----3')-beta-lactos ylceramide.

A ganglioside GD3 analog has been synthesized having an N-acetylneuraminic acid (Neu5Ac) residue alpha-thioglycosidically linked to C-9 of the Neu5Ac residue in the ganglioside GM3 structure. Glycosylation of 2-(trimethylsilyl)ethyl O-(6-O-benzoyl-beta-D-galactopyranosyl)-(1----4)-2,6-di-O-benzoyl-beta-D -glucopyranoside with methyl (methyl 5-acetamido-4,7,8-tri-O-acetyl-9-bromo-3,5,9-trideoxy-D-glycero-alpha-D- galacto-2-nonulopyranosid)onate, which was prepared from methyl (methyl 5-acetamido-3,5-dideoxy-D-glycero-alpha-D-galacto-2- nonulopyranosid)onate by 8,9-O-isopropylidenation, O-acetylation, hydrolysis of the isopropylidene group, selective bromination, and O-acetylation, using dimethyl(methylthio)sulfonium triflate (DMTST) as a promoter, gave the alpha-sialosyl-(2----3')-lactoside 8. Coupling of the O-acetyl derivative of 8 with the sodium salt of methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-alpha-D- galacto-2-nonulopyranosonate gave an alpha-thioglycosidically linked tetrasaccharide. This was converted, via selective removal of the 2-(trimethylsilyl)ethyl group, trichloroacetimidation, and glycosidation with (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol into a ganglioside precursor. Finally the precursor on selective reduction of the azide group, coupling with octadecanoic acid, O-deacylation, and de-esterification gave the analog, S-(N-acetyl-alpha-neuraminosyl)-(2----9)-O-(N-acetyl-9-thio-alpha- neuraminosyl)-(2----3')-beta-lactosylceramide.

Antigens, CD↗
PubMed1992

Synthesis of a position isomer of ganglioside GD3 having an alpha-Neu5Ac-(2----9)-alpha-Neu5Ac linkage.

A position isomer of ganglioside GD3 has been synthesized in which N-acetylneuraminic acid (Neu5Ac) is linked alpha-glycosidically at C-9 of the Neu5Ac residue of the ganglioside GM3, structure. The coupling of 2-(trimethylsilyl)ethyl O-(6-O-benzoyl-beta-D-galactopyranosyl)-(1----4)-2,6-di-O-benzoyl-beta-D -glucopyranoside with methyl O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto -2-nonulopyranosylonate)-(2----9)-(methyl 5-acetamido-4,7,8-tri-O-acetyl-3,5-dideoxy-2-thio-D-glycero-D-galacto-2 -nonulopyranosid)onate, prepared from the corresponding 2-(trimethylsilyl)ethyl glycoside by selective removal of the 2-(trimethylsilyl)ethyl group, 1-O-acetylation, and introduction of the methylthio group with trimethyl(methylthio)silane, using N-iodosuccinimide-trifluoromethanesulfonic acid as a glycosylation catalyst, gave a tetrasaccharide (5). Compound 5 was converted, via O-acetylation, selective removal of the 2-(trimethylsilyl)ethyl group, and subsequent imidate formation, into a protected alpha-Neu5Ac-(2----9)-alpha-Neu5Ac-(2----3')-alpha-lactosyl trichloroacetimidate (8). Glycosylation of (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol with 8 afforded a ceramide precursor which was transformed, via selective reduction of the azido group, coupling with octadecanoic acid, O-deacylation, and hydrolysis of the methyl ester groups, into to the little ganglioside.

Carbohydrate Sequence↗
PubMed1992

Anti-human interleukin-6 receptor antibody inhibits human myeloma growth in vivo.

Myeloma is one of the interleukin (IL)-6-related diseases to which abnormal expression of IL-6 has been reported to be linked. We examined the in vivo inhibitory effect of anti-human IL-6 receptor (IL-6R) antibody on human myeloma cell growth in mice. SCID mice were subcutaneously inoculated with solid tumor of the myeloma cell line S6B45 in which human IL-6 was acting as an autocrine growth factor. Ten intraperitoneal administrations of 100 micrograms of the anti-human IL-6R antibody PM1 at 48-h intervals strongly inhibited the growth of S6B45 cells when the administration started 24 h after tumor inoculation. The tumor growth inhibition in vivo was also observed by administration of the anti-human IL-6 antibody MH166 using the same procedure as for PM1. The inhibitory effect of PM1 was not significant when the administration started 5 or more days after tumor inoculation. This work indicates that anti-human IL-6R antibody, as well as anti-human IL-6 antibody inhibits human myeloma growth in vivo, and provides an animal model for testing the therapeutic value of agents such as antibodies to human IL-6, IL-6R and gp130, an IL-6R-associated signal transducer, in the treatment of human myelomas.

Animals↗
PubMed1992

Detection and serotyping of rotaviruses in stool specimens by using reverse transcription and polymerase chain reaction amplification.

Direct rotavirus serotyping (VP7, G type) in stool specimens was carried out by reverse transcription and polymerase chain reaction amplification (RT-PCR) and compared to serotyping by enzyme immunoassay with monoclonal antibodies (EIA-MAb). The methods used for double-stranded (ds) RNA extraction, RT-PCR amplification, and the primers used were modified from previous reports [Gouvea et al.: Journal of Clinical Microbiology 29:519-523, 1990; Gentsch et al.: Journal of Clinical Microbiology, 1992]. For samples that were positive by both methods, the serotypes obtained were identical, however RT-PCR typing was found to be considerably more sensitive (70.4% samples serotyped) than EIA-MAb (35.6% of samples serotyped). The overall sensitivities for detection of rotavirus in stool samples by latex agglutination, enzyme immunoassay, electron microscopy, polyacrylamide gel electrophoresis, and RT-PCR were essentially the same. The results confirm that RT-PCR typing (genotyping) is extremely valuable for G typing of samples which cannot be typed by EIA-MAb. We also developed a PCR confirmation technique for serotypes 1, 2, and 4.

Acute Disease↗
PubMed1992

Detection of anti-gag antibodies of feline immunodeficiency virus in cat sera by enzyme-linked immunosorbent assay.

Using gag protein of feline immunodeficiency virus (FIV) expressed in Escherichia coli, an enzyme-linked immunosorbent assay (ELISA) system was developed for detection of antibodies to FIV gag protein in cat sera. With serum samples from cats experimentally infected with several strains and an infectious molecular clone of FIV, increases of the antibody titers to FIV gag protein were observed in all cases by the ELISA at early stage of infection. When we examined a total of 415 field cat sera which were previously tested by an indirect immunofluorescence assay (IFA), 9 (12.9%) out of 70 IFA positive sera were judged as negative by the ELISA. However, all 3 serum samples tested among the 9 IFA positive sera had antibodies to gp130 but not to p26 by a radioimmunoprecipitation assay. The results indicated that some IFA positive sera did not have antibodies to the p26 though they have antibodies to other proteins specific for FIV.

Animals↗
PubMed1992

Molecular characterization and heterogeneity of feline immunodeficiency virus isolates.

We have molecularly cloned the complete genomic DNA of TM2 strain of feline immunodeficiency virus (FIV) isolated in Japan and compared its nucleotide and the deduced amino acid sequence with those of previously described U.S. isolates, FIV Petaluma and FIV PPR. The infectious molecular clone of FIV TM2 is different from FIV Petaluma in host cell range; the clone can not infect Crandell feline kidney cells which were permissive for FIV Petaluma. The amino acid sequence homologies, in gag, pol, and env genes between FIV TM2 and Petaluma were 90%, 87%, and 81%, respectively. On the other hand, comparative analysis of each gene between FIV Petaluma and PPR showed 96,95, and 85%, respectively. These results suggested that the genomic diversity was present among FIV strains isolated from geographically distant areas. Interestingly, tat- and rev-like short open reading frames contained inframe stop codons in the FIV Petaluma but not in the FIV TM2.

Amino Acid Sequence↗