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Biomedical subjects

Y Takamitsu

Publications and source records attributed to Y Takamitsu.

At least 73 records · Page 4Linked to original sources
PubMed1980

Hypouricemia due to an isolated defect in renal tubular urate reabsorption.

During investigation of chronic glomerulonephritis, a 24-year-old man was found to have a low serum urate concentration (0.6-1.3 mg/100 ml). Daily urinary excretion of urate and oxypurines was normal. His urate clearance was markedly increased (43.3-98.0 ml/min), and was substantially unchanged after both the administration of pyrazinamide, an inhibitor of the renal tubular secretion of uric acid, and the administration of probenecid, an inhibitor of the renal tubular reabsorption of uric acid. No other renal tubular abnormalities were detected. It was concluded that the patient had an isolated defect in the renal tubular reabsorption of uric acid. The patient's brother was also found to have hypouricemia due to renal uricosuria, suggesting a genetic origin of the defect.

Adult↗
PubMed1979

Effect of low protein diet and surplus of essential amino acids on the serum concentration and the urinary excretion of methylguanidine and guanidinosuccinic acid in chronic renal failure.

20 patients with moderate renal failure (serum creatinine 4.5--12.0 mg/dl) and some uremic symptoms on a diet ad libitum were treated with a high caloric diet containing 0.5--0.7 g/kg/day protein, supplemented with eight essential amino acids and histidine in the form of solution and/or granules. During the treatment uremic symptoms subsided or diminished without the signs of malnutrition, SUN and the ratio SUN/S-creatinine fell and the nitrogen balance and the ratio N-balance/intake N improved. The serum concentration and the urinary excretion of MG and GSA of the 12 patients were determined by Stein's method using the modified Sakaguchi reaction. In all patients, the serum concentration and the urinary excretion of MG and GSA diminished remarkably during the treatment with a low protein diet alone and furthermore with a low protein diet and essential amino acid supply. We concluded that conservative treatment -- low nitrogen diet supplemented with sufficient calories and essential amino acids -- improved the nutritional state of uremic subjects, and decreased the metabolic production of MG and GSA. The results show that the supplementation of essential amino acids to uremic patients may be a useful treatment.

Adult↗
PubMed1978

Effect of arginine or creatinine administration on the urinary excretion of methylguanidine.

The metabolic pathway of methylguanidine (MG) is mainly speculated from the change in urinary excretion of MG in the arginine (Arg)-injected normal rat, the creatinine (Cr)-injected normal rat, and the Arg-injected uremic rat. 15N-Arg was ingested to 2 uremic patients. Arg administration resulted in marked increase in urinary MG excretion both in the uremic rat and patient, but not in the normal rat. In the first phase of the 15N-Arg ingestion experiment, a rapid rise of 15N atom percent excess of urinary MG was observed in the uremic patient. In the second phase of this study, after 24 h of 15N-Arg ingestion, the 15N atom percent excess of urinary Cr and that of MG closely paralleled. These findings imply that there might be two metabolic origins of MG: one is a formation of MG from Arg itself or an Arg metabolite other than Cr, the other a pathway producing MG via Cr. The former is compatible with the hypothesis by Cohen.

Animals↗
PubMed1977

Potassium activity and plasma membrane potentials in epithelial cells of toad bladder.

Intracellular potassium activity (aki), mucosal and serosal membrane potential (mEm, sEm), short-circuit current (Isc), and transepithelial potential difference in the epithelium of the toad bladder were measured with a potassium-sensitive liquid ion exchanger and an ordinary microelectrode. Under basal conditions, aki was 41.2 +/- 0.5 mM, corresponding to 54.4 mM in free potassium concentration, so half or more of the intracellular potassium may be of bound form or sequestrated within subcellular organelles. The sEm cannot be explained by only the potassium equilibrium potential (Eeq), because the sEm was markedly lower than the Eeq and no relation was found between them. Ouabain and rotenone decreased the aki, but ethacrynic acid, which also inhibited the Isc and the membrane potentials, did not show any effect on aki. Vasopressin decreased aki with an elevation in mEm, whereas prostaglandin E1 increased the aki with elevation in the sEm. These characteristic changes may afford an insight into the mechanisms by which transcellular electrolyte transport occurs.

Animals↗
PubMed1975

Effect of colchicine on the osmotic water flow across the toad urinary bladder.

Osmotic water movement across the toad urinary bladder in response to both vasopressin and cyclic AMP was inhibited by 10(-5) to 10(-4) M colchicine on the serosal but not on the mucosal side. This inhibitory effect was found to be time- and dose-dependent. Colchicine alone did not change basal osmotic flow and a baseline of the short-circuit current (Isc) and also did not affect a vasopressin-induced rise of the Isc. The inhibitory effect was not prevented by the addition of pyruvate. The osmotic water movement produced by 360 mM Urea (mucosal), 360 mM mannitol (serosal) or 2 mug/ml amphotericin B (mucosal), was not affected by 10(-4) M colchicine. These results suggest that colchicine inhibits some biological process subsequent to the formation of cyclic AMP except a directional cytoplasmic streaming process where microtubules may be involved.

Amphotericin B↗
PubMed1972

[Vasopressin].

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Adenylyl Cyclases↗