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Biomedical subjects

K Ishihara

Publications and source records attributed to K Ishihara.

At least 811 records · Page 45Linked to original sources
PubMed1976

N-Acetylgalactosamine 4,6-bissulfate in rat urine. I. Isolation, identification and chemical synthesis.

By starting with 4 1 of rat urine, it was possible to obtain a sulfate ester of hexosamine in crystalline form. A series of identification procedures including chemical analyses, enzymatic digestion, proton magnetic resonance spectroscopy and infrared spectroscopy showed that this substance is 2-acetamido-2-deoxy-D-galactose 4,6-bissulfate. The trivial name for this compound is N-acetylgalactosamine 4,6-bissulfate; Quantitation by isotopic techniques indicated the urine possessed an average concentration of 8 muM N-acetylgalactosamine 4,6-bissulfate. Further extension of these studies necessitated the chemical synthesis of N-acetylgalactosamine 4,6-bissulfate and related compounds to be used for references or as biological substrates. Direct sulfation of N-acetylgalactosamine was attempted first, and strong preference for attack on the primary hydroxyl group (position 6) was found for chlorosulfonic acid. Thus, the reaction with 2.2 molar equivalents of the sulfating agent gave N-acetylgalactosamine 6-sulfate and its derivatives bearing a second sulfate at either position 1 (minor) or position 3 (major). The lack of sulfation at position 4 could be attributed to steric effects of the sulfate group preferentially attached to position 6. Another experiment in which UDP-N-acetylgalactosamine 4-sulfate was used in place of the free sugar led to the formation of a bissulfated sugar-nucleotide which, on subsequent hydrolysis with mild acid, afforded N-acetylgalactosamine 4,6-bissulfate, the same compound as that obtained from rat urine.

Acetylgalactosamine↗
PubMed1976

N-Acetylgalactosamine 4,6-bissulfate in rat urine. II. Occurrence in rat cartilage and blood.

The intraperitoneal injection of inorganic [35S]sulfate to rat was followed by the rapid appearance in urine of a labeled compound which behaved as N-acetylgalactosamine 4,6-bissulfate on paper chromatography and paper electrophoresis and when treated with two sulfatases with a high degree of specificity toward the sulfate bonds at positions 4 and 6, respectively. Enzymatically-prepared N-acetylgalactosamine 4,6-[6-35S]bissulfate was injected intravenously into rats. Of the injected dose, 90% was excreted unchanged in the urine during the subsequent 12 h, suggesting that the urinary N-acetylgalactosamine 4,6-bissulfate may derive from blood as renal filtrate. Examination of the rats injected with inorganic [35S]sulfate revealed the presence of labeled N-acetylgalactosamine 4,6-bissulfate at significant levels in the blood and cartilage, but at much lower levels in the liver. The cartilage component was highest in its rate of 35S uptake, suggesting that the blood component may derive at least in some part from the cartilage. Exposure of surviving cartilage slices to inorganic [35S]sulfate, followed by extraction of the slices with hot 50% ethanol yielded a number of radioactive compounds, of which three were characterized as UDP-N-acetylgalactosamine-4,6-[35S]bissulfate, N-acetylgalactosamine-1-phosphate 4,6-[35S]bissulfate and N-acetylgalactosamine 4,6-[35S]bissulfate. By subjecting the prelabeled tissue to chase incubation, it was possible to show that the UDP-N-acetylgalactosamine-4,6-bissulfate in the tissue disappeared with an approximate half-life of 10 min with a concomitant appearance in the medium of N-acetylgalactosamine 4,6-bissulfate and its 1-phosphate ester. These results suggest the occurrence in cartilage of an enzymatic system which is responsible for rapid turnover of UDP-N-acetylgalactosamine-4,6-bissulfate and possibly required for the rapid secretion of N-acetylgalactosamine 4,6-bissulfate into extracellular field.

Acetylgalactosamine↗
PubMed1976

Leiomyosarcomas of the small intestine induced in dogs by N-methul-N'-nitro-N-nitrosoguanidine.

Leiomyosarcomas of the small intestine were found in dogs during experimental induction of gastric carcinoma by oral administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Leiomyosarcomas were found most frequenly in the duodenum and jejunum, and occasionally in the stomach but never in the ileum, colon, or rectum. The leiomyosarcomas developed in all the dogs given 50 mug/ml of MNNG in deionized water to drink but not in dogs fed on porridge food made from standard pellet diet mashed with MNNG at the same concentration in tap water. Intestinal sarcomas developed in 3 months to 5 years after the end of MNNG administration, and frequently metastasized to the liver and/or the peritoneum.

Administration, Oral↗
PubMed1975

Secretory function of the stomach of Japanese with endoscopically normal gastric mucosa.

Using gastrin-like AOC-tetrapeptide the secretory function of the stomach of Japanese with endoscopically normal gastric mucosa was examined in a multicenter clinical study. Mean one hour secretion volume, mean maximal acidity, and mean maximal acid output were found to be 129.3 +/- 60.0 ml/hr, 103.7 +/- 32.4 mEq/l, and 9.2 +/- 6.9 mEq/hr respectively. Results were analysed according to sex or age by analysis of variance and compared further with the corresponding data reported in the literature.

Adult↗