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Biomedical subjects

M Sekine

Publications and source records attributed to M Sekine.

At least 145 records · Page 8Linked to original sources
PubMed1987

A new extended globoglycolipid carrying the stage specific embryonic antigen-1 (SSEA-1) determinant in mouse kidney.

Two neutral glycolipids carrying the stage specific embryonic antigen-1 (SSEA-1) and SSEA-3 determinants, respectively, were purified from mouse kidney by a combination of column chromatographies and droplet counter-current chromatography. The structures of the glycolipids (GL-X and GL-Y) were determined by means of GLC, 1H-NMR spectroscopy, negative-ion fast atom bombardment mass spectrometry, a methylation study, and sequential degradation. GL-X was demonstrated to be galactosyl beta 1-3globotetraosylceramide, the structure of which had already been characterized to be that of SSEA-3 by Kannagi et al. [1983) J. Biol. Chem. 258, 8934-8942). GL-Y was a new glycolipid containing fucose, galactose, glucose, N-acetylgalactosamine, and N-acetylglucosamine in a molar ratio of 1:4:1:1:1. The methylation study results indicated that it contained 3 mol of terminal sugars composed of 2 mol of galactose and 1 mol of fucose with two branching points at N-acetylgalactosamine and N-acetylglucosamine. From the data obtained by 1H-NMR spectroscopy, mass spectrometry, and a binding assay using an anti-SSEA-1 monoclonal antibody (PM81) cloned by Ball et al. [1983) J. Immunol. 130, 2937-2941), we propose the structure of GL-Y to be Gal beta 1-4GlcNAc beta 1-6GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc beta 1-ceramide. (sequence; see text) Fuc alpha 1 Gal beta 1 This is the first report on the isolation and characterization of a glycolipid carrying the SSEA-1 determinant on its globo-core structure.

Animals↗
PubMed1987

Genetic control of the expression of two extended globoglycolipids carrying either the stage specific embryonic antigen-1 or -3 determinant in mouse kidney.

In the preceding paper (J. Biochem. 101, 553-562 (1987], we reported the structures of two neutral glycolipids (GL-X and GL-Y) purified from mouse kidney, and demonstrated the occurrence of polymorphic variation of these two glycolipids in inbred strains of mice. GL-X was characterized as galactosyl beta 1-3globotetraosylceramide, which was reported to be stage specific embryonic antigen-3 (SSEA-3) by Kannagi et al. (J. Biol. Chem. 258, 8934-8942 (1983], and GL-Y as 3-fucolactosaminyl beta 1-6(galactosyl beta 1-3)globotetraosylceramide, which carries the SSEA-1 determinant. In order to elucidate the mode of genetic control of GL-X and GL-Y expression, two variants, i.e., BALB/c mice expressing GL-Y and DBA/2 mice lacking GL-Y but expressing GL-X as the major neutral glycolipid, were subjected to mating experiments and glycolipid analysis. F1 hybrids expressed GL-Y, therefore GL-Y expression is dominant, and DBA/2 mice were determined to be recessive homozygotes. Through analysis of backcross and F2 mice, DBA/2 mice were demonstrated to carry a single defective autosomal gene, and it is concluded that because of this DBA/2 mice cannot express GL-Y and so accumulate GL-X. An attempt to map the gene controlling GL-Y expression on mouse chromosomes using coat colors and recombinant inbred strains was not successful.

Animals↗
PubMed1986

A Raman spectroscopic study on the sequence dependent conformations of DNA oligomers.

Eighteen kinds of oligodeoxyribonucleic acids have been examined to reveal their structures in aqueous solutions at different ionic strengths by Raman spectroscopy. The structures in solutions were found to be very polymorphic depending on their sequences as well as on the salt concentrations. At a low salt condition a DNA oligomer assumes a unique B form within a B family, for examples Ba, Bh, B', or Bn form. Amongst these DNA oligomers, d(CGCG)2 showed a salt induced Ba-Z transition, while d(GGGGCCCC)2 showed a salt induced Bh-A transition. DNA oligomers with AA/TT sequences were found to prefer B' form even at high salt condition. From comparing the structures of DNA oligomers in solutions with their crystal structures, it is safe to say that the crystal structure of a DNA oligomer is very similar to the structure in the high salt solution.

Base Sequence↗
PubMed1986

The phosphorothioite method. Synthesis of deoxyoligonucleotides on polymer supports by using nucleoside phosphorothioites.

The development of a new method, which is called "the phosphorothioite method", for synthesizing deoxyoligonucleotides on polymer supports is described. Nucleoside phosphorothioites were easily prepared and readily activated by iodine or silver acetate. In the case of the use of iodine, the present method did not require the oxidation step, because it could be simultaneously performed during condensation and thereby the reaction time could be shorten. This method was applied successfully to the polymer support synthesis.

Base Sequence↗
PubMed1985

[A radioimmunoassay of 6-keto PG F1 alpha using [125I]-6-keto PG F1 alpha-tyramide].

We established a radioimmunoassay of 6-keto PG F1 alpha, using 125I-6-keto PG F1 alpha-tyramide, which enabled us more easily to monitor the plasma levels of prostacyclin in clinical fields. Antibodies against 6-keto PG F1 alpha were obtained from rabbits immunized with 6-keto PG F1 alpha-BSA complex, which could be used for RIA at a final dilution of 1:648,000. The detection limit of 6-keto PG F1 alpha was 50-1000 pg/ml. The cross reactivities between PG I2 and PG F1 alpha were 26.6% and 1.62% respectively, but those between other prostaglandins were less than 1%. Using this radioimmunoassay with 125I-6-keto PG F1 alpha-tyramide, plasma levels of 6-keto PG F1 alpha were measured. The recovery rate by this assay was 92.9%, and the intra- and inter-assay coefficients of variation determined were 9.9% and 27.1%, respectively. The mean of plasma levels of 6-keto PG F1 alpha revealed 126.2 +/- 75.3 (mean +/- S.D.) pg/ml in 46 healthy Japanese males, 122.7 +/- 85.2 pg/ml in 60 females, and 124.2 +/- 81.3 pg/ml in 106 Japanese of both sexes.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

An interspecies comparison of gangliosides and neutral glycolipids in adrenal glands.

Gangliosides and neutral glycolipids of adrenal glands of mouse, rat, guinea pig, rabbit, cat, pig, cow, monkey, and chicken were analyzed by thin layer chromatography (TLC). The major gangliosides common to all species had lactosylceramide in their core structure. GM3 containing N-acetylneuraminic acid (NeuAc) was the major ganglioside in rat, guinea pig, rabbit, and cat, whereas GM3 containing N-glycolylneuraminic acid (NeuGc) was the major one in mouse, cow, and monkey. GD3 was also detected in all species except mouse and GD3(NeuAc)2 was the major in pig adrenal gland. GM4(NeuAc) was detected in the adrenal glands of guinea pig and chicken but not in those of the other species. In the neutral glycolipid fractions, galactosylceramide, glucosylceramide, lactosylceramide, globotriaosylceramide and globotetraosylceramide were detected and the proportions of these glycolipids varied among the species. Guinea pig and chicken adrenal glands contained large amounts of galactosylceramide, this being consistent with the presence of GM4 in these two species. Globopentaosylceramide was detected in mouse, guinea pig, cat, and chicken by the TLC-immunostaining procedure.

Adrenal Glands↗
PubMed1985

Neurological mutation characterized by dysmyelination in NCTR-Balb/C mouse with lysosomal lipid storage disease.

Morphological and biochemical studies were performed on the CNS of neurologically affected NCTR-Balb/C mouse. Histological and electron microscopic techniques demonstrated severe myelin deficiency in the affected brains. Neither the presence of lipid-containing macrophages nor reactive gliosis was apparent. Analysis of myelin-associated lipids and proteins revealed prominent depletion of galactocerebroside, sulfatide, and proteolipid proteins. In contrast to the scarcity of myelin-specific constituents a marked accumulation of GM2 and GM3 gangliosides and several neutral glycolipids, i.e., glucocerebroside, lactosylceramide, gangliotriaosylceramide, and gangliotetraosylceramide were found in affected CNS. These abnormalities were already apparent in 12-day-old pups as well as in 65-day-old mice. A significant deficit in the proportion of long-chain fatty acids (C24), notable in both normal and alpha-hydroxy acids of cerebrosides from affected white matter, was measured. The lack of reactive gliosis, the observed depletion of galactocerebroside and sulfatide at the early age of 12 days, and the relative decrease in long-chain fatty acids in affected CNS strongly suggest a defect in myelinogenesis in this mutant rather than a secondary process of myelin breakdown.

Animals↗
PubMed1985

Improvement of bioavailability of poorly absorbed drugs. II. Effect of medium chain glyceride base on the intestinal absorption of cefmetazole sodium in rats and dogs.

The effect of medium chain glyceride (MCG) on the intestinal absorption of cefmetazole sodium (CMZ) was investigated in rats and dogs. In rats, MCG containing glyceryl mono-, di- and tri-caprylate enhanced the intestinal absorption of CMZ after intraduodenal administration, though the promoting effect of MCG was less than that after rectal administration. The promoting effect of MCG was found to be mainly due to glycerylmonocaprylate and dependent on the dosage of MCG. The plasma CMZ levels after intraduodenal administration as MCG solution tended to be slightly higher than those observed after administration as MCG emulsion, though the differences were found to be statistically insignificant. Moreover, the intestinal absorption of CMZ after intraduodenal administration as MCG emulsion was decreased significantly by increasing the amount of water in the emulsion. The promoting effect of MCG in dogs was more clearly demonstrated in the lower intestine than in the upper intestine. Furthermore, the oral bioavailability of pharmaceutical formulations of CMZ was also investigated in dogs. When enteric coated capsules filled with MCG solution were administered to dogs, the bioavailability of CMZ was enhanced significantly.

Animals↗
PubMed1985

Improvement of bioavailability of poorly absorbed drugs. III. Oral acute toxicity and local irritation of medium chain glyceride.

Oral acute toxicity of medium chain glyceride (MCG) was studied in mice and rats. In mice and rats, clinical signs such as irregular respiration, laxity of movement, staggering gait and loss of righting reflex appeared after single oral administration of MCG at a relatively large dose. The LD50 values determined in male and female mice were 26.9 and 28.5 ml/kg, and in male and female rats were 27.4 and 26.7 ml/kg, respectively. In order to evaluate the biological safety of MCG suppository of cefmetazole sodium (CMZ), its local irritation on the mucous membrane was studied. Primary eye irritation of MCG suppository of CMZ was studied in rabbits. Although mild irritation was seen in conjunctivae, no remarkable changes were observed in cornea and iris. Furthermore, primary effect of MCG suppository of CMZ on the rectal mucous membrane was studied macro- and microscopically. It was observed that remarkable histological changes of rectal mucous membrane by MCG suppository of CMZ were not observed in all animals used.

Animals↗
PubMed1985

Improvement of bioavailability of poorly absorbed drugs. IV. Mechanism of the promoting effect of medium chain glyceride on the rectal absorption of water soluble drugs.

The mechanisms of the promoting effect of medium chain glyceride (MCG) containing glyceryl mono-, di- and tri-caprylate on rectal absorption of water soluble drugs were investigated. It was found that the solubility behavior of the drugs in mucosal fluids on the surface of the membrane are critical factor for the enhanced rectal absorption. Moreover, the drugs to be readily absorbed from MCG base may be ones of low partition coefficients to MCG phase as well as high solubility in water. And it was found that MCG can't be absorbed from the rectum, different from oral administration, suggesting an interaction of MCG with absorption membrane, rather than the carrier effect of MCG itself. Furthermore, from the results in the pretreatment experiments and additional administration of MCG alone, it was suggested that the interactions of MCG with the membrane components, as well as the induction of biological or physiological changes, may be at least partly responsible for the promoting effect of MCG.

Animals↗
PubMed1985

Improvement of bioavailability of poorly absorbed drugs. V. Effect of surfactants on the promoting effect of medium chain glyceride for the rectal absorption of beta-lactam antibiotics in rats and dogs.

The promoting effects of medium chain glyceride (MCG) on the rectal absorption of beta-lactam antibiotics were compared among various experimental animals (such as rats, rabbits and dogs). The plasma levels of cefmetazole (CMZ) after rectal administration, when MCG was used as the vehicle, significantly increased in all animals, but the bioavailability of CMZ was greatly varied among the animal species; the bioavailability of CMZ in dogs was apparently less than those in other animals (rats = rabbits greater than dogs). However, in dogs, the promoting effect of MCG on the rectal absorption of CMZ increased by addition of nonionic surfactants such as ether-type (Brij 30 and Brij 35) and ester type (Nikkol MYL-10). And the promoting effect of surfactants in the MCG vehicle is not always correlated with blood hemolysis, suggesting contribution of other physicochemical or biological factors.

Animals↗
PubMed1985

Plasma thromboxane B2, 6-keto PGF1 alpha and cyclic nucleotides levels as related to treadmill exercise test in patients with ischemic heart disease.

Plasma prostanoids and levels of cyclic nucleotides were studied in forty-nine outpatients with precordial pains and subjected to the treadmill exercise test. Blood samples were drawn before, immediately after and 30 minutes after exercise, from antecubital veins. Plasma TXB2, 6-keto PGF1 alpha, cyclic AMP and cyclic GMP levels were measured by radioimmunoassay. The results of exercise tests were evaluated according to the treadmill exercise score (TES) of Hollenberg et al. Patients were divided into two groups; those with TES (-) with ischemic findings in exercise and those with TES (+) with normal exercise response. There were no differences in TXB2 levels between the two groups before exercise. Immediately after exercise statistically significant differences in TXB2 levels were present between the two groups. There were increased levels in the TES (-) group and decreased levels in the TES (+) group (p less than 0.01). Although the 6-keto PGF1 alpha levels were the same between the two groups before exercise, 6-keto PGF1 alpha levels in the TES (+) group increased significantly immediately after exercise. Similar changes were noted in the case of cyclic nucleotides, and the differences increased immediately after exercise. We conclude that high responses of cyclic nucleotides and PGI2 are required to counteract increases in levels of TXA2 and diminution of these responses may be an important phenomenon involved in the physiological status of ischemic heart disease.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Synthesis of branched ribonucleotides.

A synthetic strategy for branched ribonucleotides, which have recently been discovered, was described. A fully protected adenosine unit (5) having the tris (4,5-dichlorophthalimido)trityl (CPTr), bis(anilino)phosphoryl (BAP), and bis(phenylthio)phosphoryl (BPTP) groups as the 5'-, 2'-, and 3'-hydroxyl protecting groups, respectively, was synthesized from adenosine by a five-step reaction involving a new method for the 2'-O-phosphorylation by the use of hexaethylphosphorous triamide. The selective deprotection of appropriate protecting groups from 5 followed by stepwise condensation with two different ribonucleoside derivatives (7 and 10) gave a protected branched ribonucleotide (11) via a 3'-phosphorylated 2'-5' dinucleotide (8). Deprotection of 11 and 8 gave a branched trinucleotide (12) and 3'-phosphorylated dinucleotide (13).

Adenosine↗
PubMed1985

Chemical synthesis of capped RNA fragments and their ability to complex with eukaryotic ribosomes.

In other to examine the binding ability of the 5'-terminal part of eukaryotic mRNA to 80S ribosome, several kinds of oligoribonucleotides, pA-U-G, m7G5'pppA-U-G, m7G5'pppG-U, m7G5'pppA-U-G-A-C-C, were synthesized chemically. The binding experiments of oligonucleotides to 80S ribosome showed that the capped structure as well as AUG are essential for ribosome binding, and the efficiency is enhanced by the 5'-leader sequence if it would include complementary sequence to the 3'-terminal part of 18S rRNA.

Base Sequence↗
PubMed1984

Cyclic diacyl groups for protection of the N6-amino group of deoxyadenosine in oligodeoxynucleotide synthesis.

Three kinds of substituted phthaloyl groups and a succinyl group were introduced onto the N6-amino function of deoxyadenosine derivatives. Among them, the succinyl group was found to be the most effective for prevention of depurination upon detritylation in acidic media and the most stable in basic media. Protection of the N6-amino function of 5'-O-dimethoxytrityldeoxyadenosine and introduction of a succinate linker into the 3'-hydroxyl were achieved simultaneously by a one-step reaction with succinic anhydride. A tetradeoxyribonucleotide, dTpTpTpA containing a 3'-terminal deoxyadenosine was successfully synthesized on a polystyrene support via the phosphotriester method.

Acylation↗