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Biomedical subjects

S Okuda

Publications and source records attributed to S Okuda.

At least 343 records · Page 19Linked to original sources
PubMed1981

Steric course of deuterium incorporation from [2-2H2]malonyl-CoA into fatty acids by fatty acid synthetases.

The steric course of the enoyl reduction catalyzed by fatty acid synthetase was investigated with the enzymes from bakers' yeast, rat liver and Brevibacterium ammoniagenes. The non-enzymic hydrogen-deuterium exchange of the methylene group of malonyl-CoA was studied by NMR spectroscopy. The half-life period of the methylene protons was 4.8 min at 37 degrees C and 12.2 min at 23 degrees C at p2H 7.5. Deuterium-labeled fatty acids were synthesized by incubating the synthetases with [2-2H2]malonyl-CoA for 8 min. The deuterium-labeled fatty acids thus produced were extracted and subjected to the action of acyl-CoA oxidase, which had been previously shown to catalyze the anti elimination of the pro-2R and pro-3R hydrogens of acyl-CoA. The resulting products, 2,3-dehydroacyl-CoAs, were methylated and converted to 3-chlorofatty acid methyl esters by addition of hydrogen chloride. The deuterium contents of saturated fatty acids and 3-chlorofatty acids were analyzed by gas chromatography-mass spectrometry. The oleic acid produced by the enzyme from B. ammoniagenes was oxidized to nonanoic acid and azelaic acid. The resulting nonanoic acid was also subjected to the action of acyl-CoA oxidase. The deuterium contents of nonanoic acid and trans-2-nonenoic acid were analyzed. The results suggested that fatty acid synthetase from yeast and rat liver incorporated hydrogen from water via a 2-Si attack and the enzyme from B. ammoniagenes incorporated hydrogen via a 2-Re attack during enoyl reduction. The partial racemization of the C-2 position was observed and the magnitude of this racemization was correlated with the deuterium content of synthesized fatty acids. This phenomenon may be attributed to the non-stereospecific hydrogen exchange of the C-2 position of the elongating acyl residue catalyzed by fatty acid synthetases.

Acyl Coenzyme A↗
PubMed1981

Inhibition of gastrin secretion by pirenzepine (LS 519) in treatment of gastric ulcer.

The effects of pirenzepine on the serum gastrin levels in the basal state and in response to a liquid test meal were investigated in nine patients with gastric ulcer. Single-dose administration of the drug caused a significant decrease in the basal gastrin level and significant inhibition of the serum gastrin response. When measured 12 h after the end of drug treatment for 7 days, the serum gastrin levels in the basal state and in response to a test meal tended to be high, but the differences were not statistically significant.

Adult↗
PubMed1981

[Intra-nasal distribution of aerosols with or without vibration].

Intra-nasal distribution of aerosol deposited with or without air flow vibration was investigated by the use of a cast of human nose. In order to analyze the effect of vibration on the particle deposition, the size distribution and the concentration of aerosol were simultaneously measured by an on-lined laser beam scattering particle counter. According to the experimental and the theoretical considerations, it was found that the vibration strongly affected on the motion of particles and then the aerosol particle was more widely and uniformly distributed in the nasal cavity by vibrating the air. This also caused the increasing of particle deposition efficiency and the changing the partial efficiency of each particle size in it. Judging from the above mentioned facts, it was considered that the vibration aerosol therapy would be an useful technique for nasal diseases as well as paranasal sinus diseases.

Aerosols↗
PubMed1980

Carcinoembryonic antigen in gastric juice as an aid in diagnosis of early gastric cancer.

The levels of carcinoembryonic antigen (CEA) in the serum and gastric juice of 58 patients with gastric cancer were determined by radioimmunoassay. The level of serum CEA was not a satisfactory indicator of gastric cancer: it was elevated in only 19.4% of the cases of advanced and unresectable cancer and 4.5% of cases of early cancer examined. However, the CEA level in the gastric juice was significantly higher in patients with gastric cancer than in normal subjects or patients with benign gastric diseases: increased CEA concentrations and outputs in the gastric juice were observed in 54.5% and 40.1%, respectively, of the patients with early gastric cancer, and in 52.9% and 50.0%, respectively, of the patients with advanced gastric cancer. The gross type of gastric cancer had no influence on the gastric CEA level, but the CEA level in the gastric juice tended to be high when the tumors were large, or when they had little or no glandular structure or high mucus-secreting activity.

Biopsy↗
PubMed1980

Incorporation of hydrogen atoms from deuterated water and stereospecifically deuterium-labeled nicotin amide nucleotides into fatty acids with the Escherichia coli fatty acid synthetase system.

The mechanism of hydrogen incorporation into fatty acids was investigated with intact Escherichia coli cells, a crude enzyme preparation and purified reductases of fatty acid synthetase system. The distributions of deuterium atoms incorporated into fatty acids from 2H2O and stereospecifically deuterium-labeled NADPH or NADH were determined by mass spectrometry. When E. coli was grown in 2H2O, almost every hydrogen atom of cellular fatty acids was incorporated from the medium. When fatty acids were synthesized from acetyl-CoA, malonyl-CoA and NADPH in the presence of a crude enzyme preparation of either E. coli or Bacillus subtilis, almost every hydrogen atom was also incorporated from the medium. In contrast to these results, purified beta-ketoacyl acyl carrier reductase directly transferred the HB hydrogen of NADPH to beta-ketoacyl acyl carrier protein, and purified enoyl acyl carrier protein reductase also transferred the HB hydrogen of NADPH and NADH directly to enoyl acyl carrier protein. In the crude enzyme preparation of E. coli, we found high activities which exchanged the HB hydrogen of NADPH with the deuterium of 2h2o. the conflicting results of the origin of hydrogen atoms of fatty acids mentioned above are explained by the presence of enzymes, which catalyzed the rapid exchange of NADPH with the deterium of 2H2O prior to the reaction of fatty acid synthetase.

Deuterium↗
PubMed1980

Gastric hamartomatous polyps in the absence of familial polyposis coli.

Hamartomatous polyps in the stomach have been described as gastric lesions of familial polyposis coli. Four cases of multiple gastric hamartomatous polyps not associated with polyposis coli were encountered. Histologically, all these polyps consisted of normal oxyntic glands with numerous cystic dilatations of the glandular lumens of various sizes. Endoscopically, the polyps were all located in the acid secreting area and had an acid secreting function, which was revealed by the endoscopic Congo red test.

Adult↗
PubMed1980

Effect of trapidil on prostacyclin generation of arterial wall.

Prostacyclin (PGI2) has been reported to be a labile but potent inhibitor of platelet aggregation and a powerful vasodilator. This paper reports the effect of trapidil on PGI2 generation in rat aorta by means of bioassay system. The aortic ring was incubated in 0.05 M Tris HCl buffer (pH 7.5) for 10 min. This incubation medium was added into human PRP, and then incubated at 37 degrees C for 2 min., and ADP was added. PGI2 activity was assayed by the inhibitory percentage of ADP induced platelet aggregation. When the aortic ring was incubated in a medium containing trapidil, PGI2 generation was accelerated. This acceleration was inhibited by pretreatment with indomethacin. Moreover, the aortas of rats intravenously injected with 30 mg/kg of trapidil were incubated in the same way, and PGI2 activity in the medium was estimated. More potent PGI2 activity was observed in the aortas of rat treated with trapidil compared with the controls. These results indicate that acceleration of PGI2 generation from aorta by trapidil is involved in the mode of action of this drug of thrombus formation.

Animals↗
PubMed1980

Substrate control of termination of fatty acid biosynthesis by fatty acid synthetase from Brevibacterium ammoniagenes.

The pattern of fatty acids produced by the fatty acid synthetase complex of Brevibacterium ammoniagenes under several conditions was examined. The fatty acid synthetase obtained from B. ammoniagenes produced oleic acid as well as saturated fatty acids (palmitic and stearic acids). The relative proportions of palmitic to stearic acids varied over a wide range. Such alterations were dependent on the malonyl-CoA concentration and the ratio of acetyl-CoA to malonyl-CoA concentrations. At malonyl-CoA concentrations higher than 100 microM, stearic acid accounted for more than 90% of the saturated fatty acids and the pattern of fatty acid synthesized was independent on the ratio of acetyl-CoA to malonyl-CoA. At malonyl-CoA concentrations lower than 100 microM, raising the acetyl-CoA/malonyl-CoA ratio increased the percentage of palmitic acid. However, the proportion of oleic acid produced remained almost constant under all conditions tested.

Acetyl Coenzyme A↗
PubMed1980

Stereochemistry of dehydrogenation catalyzed by Acyl-CoA oxidase.

The stereochemical course of dehydrogenation catalyzed by acyl-CoA oxidase was investigated using the enzymes from rat liver peroxisomes and Candida lipolytica. Stearoyl-CoA and nonanoyl-CoA, stereospecifically labeled with deuterium at either C-2 or C-3, were incubated with the enzyme, the products were converted to methyl esters and their deuterium contents were measured by gas chromatography-mass spectrometry. The results suggested that acyl-CoA oxidase-catalyzed dehydrogenation occurred by anti-elimination of the pro 2R and pro-3R hydrogens of acyl-CoA.

Acyl Coenzyme A↗
PubMed1980

Stereochemical course of enoyl reduction catalyzed by fatty acid synthetase. Stereochemistry of hydrogen incorporation from reduced pyridine nucleotide.

The stereochemical course of the enoyl reduction catalyzed by fatty acid synthetase was investigated using the enzymes from rat liver and Brevibacterium ammoniagenes. Deuterium-labeled fatty acids were synthesized by incubating the synthetases with either 4R-[4-2H1]- or 4S-[4-2H1]NADPH. The deuterium-labeled fatty acids thus produced were subjected to the action of a stereospecific enzyme, acyl-CoA oxidase. The deuterium-labeled fatty acids and 2,3-dehydroacyl thioesters, the products of acyl-CoA oxidase, were methylated and analyed for deuterium content by gas chromatography-mass spectrometry. These experiments provided information to determine the configuration at the C-3 position of fatty acids formed by fatty acid synthetases. The results suggested that the stereochemistry of hydrogen (as hydride) incorporation from reduced pyridine nucleotides during enoyl reduction was different between rat liver and B. ammoniagenes synthetases: the enoyl reduction of rat liver enzyme involved the re-attack of hydride and that of B. ammoniagenes enzyme involved the si-attack of hydride.

Acyl Coenzyme A↗