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Biomedical subjects

T Miki

Publications and source records attributed to T Miki.

At least 901 records · Page 50Linked to original sources
PubMed1986

Proton translocation by cytochrome oxidase vesicles catalyzing the peroxidatic oxidation of ferrocytochrome c.

Coupled with the peroxidatic oxidation of ferrocytochrome c under anaerobic conditions, proteoliposomes reconstituted with a purified preparation of bovine heart cytochrome oxidase ejected protons into the external medium with an apparent H+/e- ratio of 0.9. At the same time, protons in the intravesicular space were consumed. Dicyclohexylcarbodiimide significantly inhibited the proton translocation. Cyanide (0.14 mM) completely inhibited both the peroxidase and proton translocating activities. On the contrary, in the presence of 1 mM CO the proton ejection was abolished almost completely, but 50% of the peroxidase activity persisted. This result suggests the operation of multiple mechanisms in the peroxidase reaction and that the CO-sensitive one is coupled to the proton translocation.

Animals↗
PubMed1986

Calcitonin-induced phosphorylation of rat liver cytosolic proteins.

Calcitonin (CT) stimulated phosphorylation of two liver cytosolic proteins whose molecular weights are 67,000 and 93,000. Stimulation of 67,000-Mr protein phosphorylation began shortly after subcutaneous injection of CT, reaching a maximum at 5 min and decreasing to below the control level at 30 min. The reaction was independent of cyclic AMP or Ca2+, and was not influenced by a calmodulin antagonist, W7. Stimulation of 93,000-Mr protein phosphorylation became evident by 30 min. This reaction was also stimulated by administration of vasopressin or epinephrine, which is known to cause increased phosphorylation of glycogen phosphorylase having the same molecular weight. The phosphorylation of 93,000-Mr protein, stimulated by CT, was dependent on Ca2+ but not on cyclic AMP, and appeared to be inhibited by W7. In addition, CT did not influence the phosphorylation of 61,000-Mr protein, a major protein phosphorylated in a cyclic AMP-dependent manner. These results suggest that CT may exert its effect on liver cells through protein phosphorylation, most probably in a cyclic AMP-independent manner.

Animals↗
PubMed1986

Cytochrome c peroxidase activity of bovine heart cytochrome oxidase incorporated in liposomes and generation of membrane potential.

Cytochrome oxidase vesicles catalyzed the peroxidatic oxidation of ferrocytochrome c. The maximal peroxidase activity in the absence of an uncoupling agent was 9.8 mol ferrocytochrome c oxidized/(s X mol heme a), indicating a 5-fold activation compared with the soluble enzyme system. The peroxidase activity was further enhanced 1.2 to 2.1 times upon addition of an uncoupler, carbonyl cyanide p-trifluoromethoxyphenyl hydrazone. The stoichiometry of the reduction of hydrogen peroxide by ferrocytochrome c was established to be 1 : 2, indicating water formation. Potassium cyanide (0.14 mM) completely inhibited the peroxidase activity. The inhibition by 1 mM CO was 40-77% depending on the energized state of cytochrome oxidase vesicles, but in contrast, 85% inhibition was observed with the soluble enzyme. In the energized state the enzyme showed a slightly lower affinity for CO than in the deenergized state. Coupled with the peroxidase activity, a membrane potential of 72 mV was registered transiently; this may be physiologically significant in relation to the energy transduction mechanism.

Animals↗
PubMed1986

Concentrations of thyroxine-binding globulin in sera and peritoneal dialysates in patients on chronic peritoneal ambulatory dialysis.

Losses in thyroxine-binding globulin (TBG) in peritoneal dialysate and thyroid function were evaluated in patients undergoing continuous ambulatory peritoneal dialysis (CAPD), in comparison to patients on hemodialysis (HD) without TBG loss in the dialysate. The TBG concentration in the peritoneal dialysate was 0.26 +/- 0.09 microgram/ml (mean +/- SD, n = 24), with a daily loss of 2.47 +/- 0.94 mg. The serum TBG level in CAPD patients was 21.0 +/- 4.71 micrograms/ml (n = 24), which was not significantly different from that in HD patients (20.0 +/- 5.72 micrograms/ml, n = 24) or in healthy Japanese subjects. The serum TBG level correlated positively with the TBG loss and TBG level in the peritoneal dialysate (p less than 0.001). The serum T4 level in CAPD patients (4.93 +/- 1.38 microgram/dl, n = 24) was significantly greater than in HD patients (4.08 +/- 1.30 microgram/dl, n = 24, p less than 0.05).

Adult↗
PubMed1986

The effect of 1 alpha-hydroxyvitamin D3 on cell-mediated immunity in hemodialyzed patients.

The immunoregulatory effect of 1 alpha-hydroxyvitamin D3 (1 alpha OHD3), a precursor form of active vitamin D3, was examined in hemodialyzed patients. Four weeks of oral administration of 0.5 micrograms/day 1 alpha OHD3 markedly enhanced the lymphoproliferative responses to mitogens without influencing lymphocyte counts or the ratios of lymphocyte subpopulations. In fact, these responses were nearly normal after treatment. These results suggest that deficiency of 1,25-dihydroxyvitamin D3 may play a role in the impairment of cellular immunity in hemodialyzed patients, and that administration of 1 alpha OHD3 may have therapeutic immunological benefit.

Adult↗
PubMed1986

A case of normocalcemic primary hyperparathyroidism with osteomalacia.

A 59 year-old patient had lumbago and pain in hip joints, knees, and ribs of long duration. Severe hypophosphatemia and high serum ionized calcium were found in spite of normal level of total serum calcium. The serum parathyroid hormone and alkaline phosphatase levels were elevated, and diffuse demineralization of the bones and renal stones were found by x-ray examination. Parathyroid adenoma was diagnosed from the subtraction image of the 99mTc O-4 and 201Tl-Cl2 scintigrams. Osteomalacia was demonstrated by bone biopsy at the right iliac crest. A right lower parathyroid adenoma of 2.0 X 1.8 cm, weighing 4.0 g was removed. The long standing phosphate depletion and hypophosphatemia, due to hyperparathyroidism causing renal damage with nephrocalcinosis and reduced synthesis of active vitamin D, and milk tolerance due to gastroduodenostomy were probably responsible for producing the clinical picture of normocalcemic hyperparathyroidism complicated with osteomalacia.

Adenoma↗
PubMed1986

Deranged metabolism of lipids in patients with chronic renal failure: possible role of secondary hyperparathyroidism.

We wished to investigate the pathophysiology of hypertriglyceridemia in chronic renal failure. Our subjects were 30 patients under hemodialysis for at least five years who had never taken vitamin D analogues or calcitonin preparations. During those five years, triglycerides were high, with no significant changes, although the cholesterol level decreased significantly 10 to 12 months after the first hemodialysis treatment. There was a significant correlation between alkaline phosphatase and triglycerides (p less than 0.025) in these patients in the same assay. In the two patients with hypertriglyceridemia, serum triglycerides decreased to within the normal range by six months after parathyroidectomy, and remained there 30 months after surgery. These results suggested that secondary hyperparathyroidism may be involved in the pathophysiological mechanism of hypertriglyceridemia seen in chronic renal failure.

Adult↗