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Biomedical subjects

Y Shibuya

Publications and source records attributed to Y Shibuya.

At least 127 records · Page 7Linked to original sources
PubMed1986

Hormonal factors influencing fractional excretion of filtered sodium in normal children.

Fractional excretion of filtered sodium (FENa), plasma renin activity (PRA), urinary kallikrein excretion and main urinary metabolite of prostaglandin F2 alpha (PGF MUM) excretion were measured to evaluate the relationship between FENa and these hormonal factors in 33 healthy children aged 8 to 15 years. FENa showed a significant negative correlation with PRA and PGF MUM excretion (P less than 0.001, P less than 0.01, respectively), suggesting that PRA and PGF MUM are useful investigations in evaluating FENa. Especially PRA is often measured routinely and should be measured first, which may provide useful pathophysiological information on the genesis of abnormal FENa.

Adolescent↗
PubMed1985

Renin-stimulating test in children.

Plasma renin activity (PRA) was measured after various stimuli to evaluate a renin-stimulating test and to screen suppressed PRA in 60 children with labile hypertension aged 10 to 14 years. There was a significant difference between supine PRA and that after both standing (for 15 or 60 minutes) or frusemide administration (P less than 0.001, respectively); however, there was no statistical difference between the PRA while standing or after frusemide. Children who gripped a hand dynamometer for three minutes did not show any change in PRA. Standing upright for 15 minutes or supine rest for 90 minutes after the administration of frusemide i.v. are easily applicable to children and seem the most appropriate renin-stimulating test in childhood. No subjects showed suppressed PRA in this study.

Adolescent↗
PubMed1985

Electrolyte excretion in 12-hour urine and in spot urine. Relationship to plasma renin activity and aldosterone concentration in older children.

Plasma renin activity (PRA) and urinary electrolyte excretion were measured in 137 healthy children aged 6 to 14 years. Plasma aldosterone concentration (PAC) was measured in 52 of the children. Nocturnal 12-hour urine was collected in 110 of the children. Spot urine was collected on two occasions, once just before lying down, once after 90-min supine rest in another 27. Na/K ratio and fractional Na excretion rate (FENa) in 12-hour urine showed a significant inverse correlation with PRA or PAC. Na excretion (mmol/min, mmol/mmol creatinine), Na/K ratio and FENa in the spot urine following 90 min in a supine position showed a significant inverse correlation with PRA or PAC, but they failed to show a significant relationship to PRA or PAC in the spot urine preceding supine rest. A spot urine after 90 min in the supine position is collected easily and hence most appropriate to study the relationship between Na excretion and PRA or PAC clinically.

Adolescent↗
PubMed1985

Induction of interferon-gamma production by human natural killer cells stimulated by hydrogen peroxide.

Interferon (IFN)-inducing activity of hydrogen peroxide in human peripheral mononuclear cells was investigated. Among the mononuclear cells, purified nonadherent cells produced IFN, but not B cells and monocytes. The maximal titer of IFN by purified nonadherent cells was observed after a 72-hr cultivation in the presence of 10(-2) mM H2O2 without affecting their viability. Furthermore, the purified nonadherent cells, but not the unpurified mononuclear cells, showed an augmented cytotoxicity to K562 when stimulated with hydrogen peroxide. By using Percoll discontinuous density gradient centrifugation, peripheral blood nonphagocytic and nonadherent mononuclear cells were divided into the low and high density fractions for which natural killer (NK) cells and T cells were enriched, respectively. The NK-enriched low density fractions, but not the T cell-enriched high density fractions, showed IFN production by the stimulation of hydrogen peroxide. IFN production as well as large granular lymphocytes and HNK-1+, Leu-11+ cells of the NK-enriched fractions were abrogated by treatment of the cells with monoclonal antibody against human NK cells (HNK-1+) but not against T cells (OKT3) in the presence of complement. Moreover, hydrogen peroxide-inducing IFN production seems to be regulated by monocytes. The antiserum neutralizing IFN-alpha and IFN-beta failed to neutralize substantially IFN-produced NK cells. The treatment with either pH 2 or antiserum-neutralizing human IFN-gamma resulted in marked reduction, indicating that a major part of IFN was IFN-gamma. The purified nonadherent cells showed IFN production and augmented cytotoxicity when cultured separately from activated macrophages by opsonized zymosan; furthermore, both IFN production and enhancement of cytotoxicity were abrogated by catalase. These results suggest that both exogenous and endogenous hydrogen peroxide might be responsible for a part of immunoregulation.

Adult↗
PubMed1984

Abnormal sodium and potassium metabolism in orthostatic dysregulation in childhood.

Serum sodium (Na) and potassium (K), 12-hr urine Na, K and Na/K ratio and fractional Na excretion rate (FENa) were examined in 142 children with orthostatic dysregulation (O.D.) aged 6 to 15 years. Serum K and FENa were significantly lower in children with O.D. than in normal children, conflicting with the results of low plasma renin activity and aldosterone concentration in children with O.D. which we had previously reported. This suggests that there might be excessive excretion of a mineralocorticoid other than aldosterone or that there might be abnormal regulation of Na and K metabolism by the renin-angiotensin-aldosterone system.

Adolescent↗