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Biomedical subjects

Y Ogawa

Publications and source records attributed to Y Ogawa.

At least 19 recordsLinked to original sources
PubMed1979

Application of the pH-jump method to the titration of tyrosine residues in bovine alpha-lactalbumin.

A stopped-flow technique has been developed for the zero-time spectrophotometric titration of tyrosine residues in the purely native or in the purely alkaline denatured state of alpha-lactalbumin that undergoes an alkaline conformational transition in the pH region of tyrosine ionization. The progressive absorption change at 298 nm caused by a pH jump from neutral pH is shown to result from the change in ionization of the tyrosine residues brought about by a first-order process of the conformational transition. Extrapolation to zero time gives the titration curve for purely native alpha-lactalbumin. Similarly, the pH jump from highly alkaline pH gives the titration curve for the purely alkaline denatured protein. The method should be generally applicable to other proteins that contain tyrosines. Analysis of the titration curves suggests that the four tyrosines in native alpha-lactalbumin have pK values of 10.5, 11.8, 11.8, and 12.7, respectively. After the alkaline transconformation, all of them become titrated normally with a pK value of 10.3. A comparison of these results with the ionization behavior of tyrosines in hen egg white and human lysozymes is presented and discussed in terms of differences in the sequences of the proteins.

Animals↗
PubMed1979

Electron microscopical and histochemical studies of outer hair cells in acoustically exposed rabbits.

After acoustic exposure, in the infranuclear region of the basal turn histochemically the lactate dehydrogenase activity increased more than normal. In the lower half of the second turn of this region, small vesicles, free ribosomes and coated vesicles decreased in number and cytoplasmic matrix become lower in electron density and lactic dehydrogenase activity decreased. Small vesicles were found to be preferentially distributed in the presynaptic side of the afferent nerve endings. Movement of these small vesicles leads to the speculation that small vesicles have close relationship to the afferent nerve endings.

Animals↗
PubMed1979

Stimulation by catecholamine of purine catabolism in rats and chickens.

The effect of catecholamine in vivo was studied on purine catabolism in rats and chickens. Catecholamine, administered intraperitoneally in a high dose, markedly increased plasma uric acid and allantoin in rats, and an increase was also observed with intravenous infusion of a lower dose of catecholamine. The effects of catecholamine were characterized by inhibition with alpha and beta adrenoceptor antagonists. Regarding the mechanism of this catecholamine action on purine catabolism, it was shown that catecholamine stimulated degradation of tissue ATP into the end-product. Plasma allantoin, the final purine catabolite in rats, elicited by catecholamine could be maintained under conditions of renal failure, although the action of catecholamine in intact rat was short lasting. The effect of catecholamine was potentiated and/or prolonged by angiotensin-II and aminophylline, and a hyperuricemic state could be induced by catecholamine treatment in chickens. In addition, increase of plasma purine catabolite by immobilization stress in rats suggested the involvement of endogenous catecholamine. From these experimental results, it is considered that catecholamines probably play a important role in the pathogenesis of hyperuricemia.

Adrenergic alpha-Antagonists↗
PubMed1979

A case of multiple extra-adrenal pheochromocytomas.

A 22 year old man with two extra-adrenal pheochromocytomas located in the mediastinum and in the pelvis is presented. We believe this is the first report in Japan of extra-adrenal multiple pheochromocytomas in adult located in the two distant places.

Adult↗
PubMed1979

[Pharmacological studies on experimental nephritic rats (6). Antinephritic effects of sodium chondroitin sulfate and other drugs on modified type of Masugi's nephritis].

Using the modified model of Masugi's nephritis in rats, the antinephritic effects of sodium chondroitin sulfate (CS) and other drugs were evaluated by determining the biochemical parameters in urine, serum and renal cortex as well as light microscopic observation in kidneys by preventive and curative tests. In the preventive test where drug treatment was initiated at the same time as the injection of anti-kidney serum, CS (200 mg/kg p.o.) was effective in reducing serum triglyceride level, but was ineffective against other parameters. In the curative test where drug treatment was given from the 10th day after the induction of nephritis, CS (200 mg/kg p.o.) resulted in reductions of urinary excretions of protein and enzymes such as alkaline phosphatase and N-acetyl-beta-glucosaminidase, the inhibition of urinary fibrinolytic activity and reduction in levels of serum cholesterol and triglyceride. Moreover, histological examination indicated a significant reduction of the index of glomerular lesions by the treatment of this drug. Of other drugs, dexamethasone (0.1 mg/kg p.o.) was effective in both tests, while warfarin potassium (0.05 or 0.1 mg/kg p.o.) exerted a beneficial effect only in the preventive test. From these results, the effectiveness of CS in the curative test is probably due to promotion of healing of damaged tissue in the kidneys.

Adrenochrome↗