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Biomedical subjects

Y Akazawa

Publications and source records attributed to Y Akazawa.

At least 37 records · Page 2Linked to original sources
PubMed1985

Diabetic osteopenia in central Japan.

A large scale study of diabetic osteopenia was conducted in central Japan. The degree of bone mass loss was measured in 1267 diabetic patients and 646 control subjects. Based on six indices obtained by microdensitometry, the bone mass of 21.1% of the diabetic patients was found to be markedly decreased and that of 8.2% was found to be severely decreased, while only 7.9% of the control group showed bone mass loss. The prevalence of diabetic osteopenia in female patients was significantly higher than in males, but a positive correlation between the degree of bone mass loss and age was observed in both the male and female patients. Patients requiring oral agents or insulin had significantly more bone mass loss than those on dietary therapy alone.

Adolescent↗
PubMed1983

Phosphatidylethanolamine methyltransferase activity in developing, demyelinating, and diabetic mouse brain.

The catalysis by phosphatidylethanolamine methyltransferase (PEMT) of phosphatidylcholine (PC) synthesis by the successive methylation of phosphatidylethanolamine in the presence of S-adenosylmethionine (AdoMet) as methyl donor, was detected in actively myelinating mouse brains. PEMT activity in the microsome fraction of fetal mouse brain at 17 days of gestation was 253 mu u/mg protein and that of adult brain after 7 days of remyelination following 6 weeks cuprizone administration was 148 mu u/mg. These figures are much higher than found in normal adult brains (1.7 mu u/mg). An increase in PEMT activity was observed in the brains of genetically transmitted diabetic mice, C57BL/KsJ-db/db, and streptozotocin-induced diabetic mice; 16.3 and 9.2 mu u/mg, respectively. The methyl group of mecobalamin was transferred to homocysteine producing AdoMet and was further metabolized into choline and acetylcholine in brain slices. These results suggest that in the diabetic state, an increase in PC synthesis is probably required in order to replace damaged myelin or to supply choline or acetylcholine essential to for nerve functions. Mecobalamin might serve as the source of the methyl group utilized for PC synthesis.

Animals↗
PubMed1981

Possible mechanisms of the triphasic effects of neurotensin on the rat blood pressure.

Neurotensin administered intravenously in a dose of 1 nmole/kg produced triphasic blood pressure responses in anesthetized rats: the first depressor, second pressor and third depressor responses. The first depressor response was significantly suppressed by treatment of animals with a mixture of diphenhydramine and metiamide or chronic administration of compound 48/80, but was not modified by treatment with atropine, phentolamine, yohimbine, propranolol, sulpiride and adrenalectomy. The second pressor response was abolished by phentolamine, yohimbine and adrenalectomy. The second phase response was also markedly reduced by diphenhydramine in reserpinized rats and chronic administration of compound 48/80. The third depressor response was blocked by treatment of animals with diphenhydramine or chronic administration of compound 48/80. These results suggest that neurotensin may produce an immediate depressor response (the first phase) partly through a histamine-mediated process, and the second pressor response is produced by catecholamines released from the adrenal medulla through a histamine-mediated process. The third depressor response appears to be mediated mainly by histamine. The participation of mast cells as an origin of histamine which mediates these processes is suggested.

Adrenalectomy↗
PubMed1979

Studies on peptides. LXXXI. Application of a new arginine derivative, NG-mesitylene-2-sulfonylarginine, to the synthesis of substance P and neurotensin.

A new devised arginine derivative, NG-mesitylene-2-sulfonylarginine, Arg(Mts), was employed for the synthesis of hypothalamic substance P and neurotensin. The former was obtained in 74% yield by treatment of the protected undecapeptide amide, Z - Arg(Mts) - Pro - Lys(Z) - Pro - Gln - Gln - Phe - Phe - Gly - Leu - Met(O)-NH2, with methanesulfonic acid in the presence of anisole followed by reduction of the sulfoxide with 2-mercaptoethanol. The latter was obtained in 54% yield by the similar treatment of the protected tridecapeptide ester, Z - Pyr - Leu - Tyr - Glu(OBzl) - Asn - Lys(Z) - Pro - Arg(Mts) - Arg(Mts) - Pro - Tyr - Ile - Leu - OBzl, with methanesulfonic acid. As scavenger, a mixture of anisole-thioanisole-o-cresol (1:1:1, by vol.) was employed to suppress the side reaction, O-mesitylene-2-sulfonation of the Tyr residue.

Amino Acid Sequence↗
PubMed1978

Phosphodiesterase and its Ca2+-dependent activating factor in bovine thyroid.

Properties of cyclic 3',5'-nucleotide phosphodiesterase in the 100,500 X g supernatant of the bovine thyroid were investigated. The enzyme activity was measured by a radioisotopic method using an anionic-exchange resin, and it was found that the activity was stimulated by Mg2+. Sephadex G-200 gel filtration separated the supernatant into an activating factor, which required the presence of Ca2+, and an enzyme form dependent on the factor. The molecular weights were estimated to be 25,000 and 130,000, respectively. There appeared to be another enzyme form of cAMP phosphodiesterase with different dependence on the activating factor as suggested by gel filtration, but this enzyme form could not be clearly separated. cGMP phosphodiesterase purified by gel filtration showed biphasic kinetic behavior in the absence of Ca2+ and the activating factor, whereas, in their presence, the Lineweaver-Burk plot gave a single Km. The activating mechanism of phosphodiesterase may play a role in the control of concentrations of intracellular cyclic 3',5'-nucleotides in the bovine thyroid.

3',5'-Cyclic-AMP Phosphodiesterases↗