PubMed Health⌕ Search

Biomedical subjects

Y Hojo

Publications and source records attributed to Y Hojo.

At least 19 recordsLinked to original sources
PubMed1992

Enhanced spontaneous calcium efflux and decrease of calcium-dependent calcium release from the isolated perfused heart of spontaneously hypertensive rats.

OBJECTIVE: The aim of this study was to clarify the further details of calcium handling in hypertension. DESIGN: By preserving the physiological environment of cell membrane, whole hearts were used for comparison of calcium flux between spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. METHODS: Hearts from SHR and WKY rats were perfused with Krebs-Henseleit solution under constant flow and the effluent collected. RESULTS: After labelling of the heart with 45Ca2+ (100 mumol/l), 45Ca2+ binding was found to be saturated, and washing with calcium-free perfusion solution showed two exponential curves for calcium dissociation, indicating a fast (alpha-) and slow (beta-) phase. The half-lives of the beta-phase for both 4- and 8-week-old SHR were significantly shorter than those for age-matched WKY. Also in this phase, infusion of non-radioactive Ca2+ caused a transient dose-dependent release of 45Ca2+. A significant reduction in the amount of 45Ca2+ release induced by 2 mmol/l Ca2+ was observed in both 4- and 8-week-old SHR compared with age-matched WKY rats. Infusion of lanthanum, caffeine, ionomycin (calcium ionophore) and treatment of the hearts with ethyleneglycol-bis-(beta-aminoethylether)-N,N,N,',N'-tetraac etic acid did not alter 45Ca2+ release by non-radioactive Ca2+. From these observations, 45Ca2+ is presumably released from the intracellular calcium pool, and not from extracellular binding sites or sarcoplasmic reticulum. CONCLUSIONS: These findings suggest that an abnormal calcium-handling defect (enhanced calcium efflux and reduction of membrane-bound Ca2+) exists under physiological conditions before and after the onset of hypertension, and that this may be a primary characteristic of SHR.

Aging↗
PubMed1991

Hypoplastic left heart syndrome with rhabdomyoma of the left ventricle.

A case of primary cardiac tumor with hypoplastic left heart syndrome (HLH) is presented. Sonographic examination at 32 weeks' gestation revealed a large tumor in the left ventricle of the fetal heart. The newborn died of congestive heart failure at 11 days of age. Autopsy demonstrated a large tumor in the left ventricle obliterating most of the left ventricular cavity, aortic atresia, and hypoplastic ascending aorta. Microscopically, the cardiac tumor showed "spider-cells" characteristics of rhabdomyoma.

Female↗
PubMed1991

Thoracoabdominal aortic aneurysm associated with Marfan's syndrome--report of a case.

A case of Marfan's syndrome associated with thoracoabdominal aortic aneurysm and mitral regurgitation in a 29 year old male is reported herein. The aneurysm was replaced with a Y-shaped graft using Crawford's technique, while the major branches of the abdominal aorta were separately cannulated from inside the aneurysm and perfused via partial extracorporeal circulation using a left femoro-femoral bypass. We found this technique useful in the prevention of tissue ischemia during the operation. The patient's postoperative course was uneventful and he has encountered no problems in the year and half since his operation.

Adult↗
PubMed1991

In vivo nephrotoxicity induced in mice by chromium(VI). Involvement of glutathione and chromium(V).

The role of glutathione (GSH) and chromium (V) in chromium (VI)-induced nephrotoxicity in mice was investigated at 24 h after K2Cr(VI)2O7 ip injection. Nephrotoxicity was assessed by measurements of relative kidney weight and serum urea nitrogen. Cr(VI) nephrotoxicity was accompanied by decreased renal GSH and glutathione reductase (GSSG-R) levels. Pretreatment with buthionine sulfoximine, an inhibitor of GSH biosynthesis, enhanced Cr(VI)-induced nephrotoxicity, and remarkably diminished kidney GSH and GSSG-R levels. In contrast, pretreatment with glutathione methyl ester, a GSH-supplying agent, prevented Cr(VI) from exerting a harmful effect on mouse kidney and restored kidney GSH level. Administration of a Cr(V) compound, K3Cr(V)O8, induced much higher toxicity in mouse kidney than Cr(VI), but it failed to diminish renal GSH level. Another Cr(V) compound, Cr(V)-GSH complex, and Cr(III) nitrate did not cause a nephrotoxic effect in mice. The mechanism of Cr(VI)-induced nephrotoxicity was explained using GSH and Cr(V).

Animals↗
PubMed1991

[Truncal valve regurgitation and stenosis in persistent truncus arteriosus: echocardiographic evaluation of pre- and postsurgical states].

Twenty-four patients with persistent truncus arteriosus who underwent total surgical correction at The Hospital for Sick Children in Toronto, Canada between October 1984 and December 1987 were investigated to determine whether the postoperative course is satisfactory even without performing replacement of the truncal valve. All patients but one were less than 6 months of age. There were 9 operative deaths with a mortality rate of 37%. The most significant incremental risk factor was age of less than 30 days at the time of surgery (p < 0.01). The operative mortality did not correlate with the degree of preoperative truncal valve regurgitation nor stenosis. Among 15 hospital survivors, 14 patients were followed by echocardiography within one week after surgery, 4 of whom were reexamined within 2 weeks. Four patients without truncal valve regurgitation and stenosis underwent successful surgery, however, mild regurgitation developed in one 2 weeks after surgery. Among 4 patients with solitary truncal valve regurgitation, 2 improved and the other 2 did not. Among 5 patients with truncal regurgitation and stenosis, 3 improved in both truncal valve regurgitation and stenosis, but improvement was observed in only stenosis in the other 2 patients. One patient with stenosis improved, but developed mild regurgitation 2 weeks later. After radical surgery, 8 of the 10 patients (80%) with regurgitation and/or stenosis showed improvement without performing replacement of the truncal valve.

Age Factors↗
PubMed1990

Intracellular Na+ kinetically interferes with the rotation of the Na(+)-driven flagellar motors of Vibrio alginolyticus.

To understand the mechanism of Na+ movement through the force-generating units of the Na(+)-driven flagellar motors of Vibrio alginolyticus, the effect of intracellular Na+ concentration on motor rotation was investigated. Control cells containing about 50 mM Na+ showed good motility even at 10 mM Na+ in the medium, i.e. in the absence of an inwardly directed Na+ gradient. In contrast, Na(+)-loaded cells containing about 400 mM Na+ showed very poor motility at 500 mM Na+ in the medium, i.e. even in the presence of an inwardly directed Na+ gradient. The membrane potential of the cells, which is a major driving force for the motor under these conditions, was not detectably altered, and consistently with this, Na(+)-coupled sucrose transport was only partly reduced in the Na(+)-loaded cells. Motility of the Na(+)-loaded cells was restored by decreasing the intracellular Na+ concentration, and the rate of restoration of motility correlated with the rate of the Na+ decrease. These results indicate that the absolute concentration of the intracellular Na+ is a determinant of the rotation rate of the Na(+)-driven flagellar motors of V. alginolyticus. A simple explanation for this phenomenon is that the force-generating unit of the motor has an intracellular Na(+)-binding site, at which the intracellular Na+ kinetically interferes with the rate of Na+ influx for motor rotation.

Aminoisobutyric Acids↗
PubMed1987

Selenium and glutathione peroxidase in human saliva and other human body fluids.

Human body fluids such as mixed saliva, erythrocyte, plasma and mature breast milk were analysed for selenium (Se) and Se-dependent glutathione peroxidase (GSH-Px), which is the only active form of Se known in man. Selenium-dependent GSH-Px activity was detected for the first time in human mixed saliva. Body fluid GSH-Px, Se and protein contents expressed in terms of volume increased in the order, saliva less than milk less than plasma less than erythrocyte. However, the sequence of increase for GSH-Px (U/mg protein) and GSH-Px-bound Se (%) was plasma less than milk less than erythrocyte less than saliva, and that for Se (ng/mg protein) was erythrocyte less than saliva less than plasma less than milk. Significant positive correlations were found between GSH-Px and Se contents and between protein and Se contents expressed per volume for human saliva, erythrocyte and the whole human fluids investigated. Positive correlations between erythrocyte and plasma Se (ng/mg protein) and between plasma and saliva GSH-Px-bound Se (%) were also significant.

Body Fluids↗
PubMed1987

Graphic analysis of serotonin effects in dog heart-lung preparation.

Graphical analysis of the effects of serotonin on cardiac function and pulmonary circulation was performed, using the dog heart-lung preparation. The equilibrium points, at which the cardiac output (CO)-curve and venous return (VR)-curve cross in the right atrial pressure (RAP) or left atrial pressure (LAP)-CO relations, were directly recorded on two X-Y recorders. CO- and VR-curves were directly depicted by changing the blood level in the reservoir, and by inducing ventricular fibrillation and simultaneously occluding pulmonary arterial trunk, respectively. Single injections of serotonin, 300 micrograms, into the right or left atrium, induced a negative inotropic response. Low rate (less than 30 micrograms/min) of infusion of serotonin had no effect on the CO-curve or on the slope-gradient of VR-curve in the LAP-CO relation. At a rate of 60 or 120 micrograms/min, however, the CO-curve was moved downwards to the right, indicating a negative inotropic effect. Pulmonary mean filling pressure increased and the slope-gradient of pulmonary VR-curve decreased, indicating an increased resistance to venous return from the pulmonary circulation. Pulmonary arterial pressure was markedly elevated. In order to obtain the capacitance ratio between the extracorporeal circuit and the pulmonary circulation, a shift of blood volume to the pulmonary circulation was induced by elevating the aortic pressure, which also decreased the slope-gradient. The calculated capacitance ratio became greater during the infusion of serotonin, indicating that the capacitance in the pulmonary circulation was lowered. It is likely that serotonin has contractile effects on the pulmonary arterial and venous vascular beds, elevating the pulmonary filling pressure and resistance to venous return.

Animals↗
PubMed1986

Selenium in Japanese baby foods.

The selenium content of various baby foods was determined by spectrofluorimetry. Mean levels of Se (ng ml-1) decreased in the sequence: pasteurized cow's milk (28.4) greater than raw cow's milk (23.1) greater than mature human milk (22.5) greater than milk-based infant formulae (6.6). The sequence of mean values of Se (ng mg-1 protein) was: human milk (1.57) greater than raw cow's milk (0.96) greater than infant formulae (0.37). Dietary Se intake (microgram day-1) of 3 month old infants fed on infant formula and various milks decreased in the order: human milk (21.0) greater than pasteurized cow's milk (18.9) greater than raw cow's milk (15.0) greater than infant formulae (5.4). There was a significant positive correlation (r = 1.00, p less than 0.001) between the Se content of the infant formula product and that of the pasteurized milk product of three manufacturers. Hot air treatment reduced the Se content of cow's milk with increasing temperature and time of heating: loss of Se amounted to 11.1% at 210 degrees C for 25 min. The Se content of human milk was positively correlated (r = 0.64, p less than 0.001) with its protein content and negatively correlated (r = -0.77, p less than 0.01) with its fat content. These correlations were not found for infant formulae.

Animals↗
PubMed1986

Sequential study on glutathione peroxidase and selenium contents of human milk.

Breast milk samples collected sequentially from five lactating women were analysed for selenium and Se-dependent glutathione peroxidase (GSH-Px), which is the only active form of Se known in man. Both GSH-Px and Se contents of breast milk decreased with increasing time of lactation and reached a plateau at a month post-partum. This sequential change was not due to the Se intake of the mother as reflected in urinary Se content. GSH-Px and Se contents of mature milk were strictly regulated irrespective of the Se intake of the mother. There was a significant positive correlation between GSH-Px and Se contents of breast milk. Mean GSH-Px and Se contents and the proportion of GSH-Px-bound Se content of the total Se content in mature milk were 38.8 U ml-1, 22.5 ng ml-1 and 23.4%, respectively. Preservation of mature milk at -20 degrees C decreased linearly its GSH-Px activity with increasing time at a rate of 5.8 U ml-1 day-1.

Adult↗
PubMed1978

Direct recording of cardiac output- and venous return-curves in the dog heart-lung preparation for a graphical analysis of the effects of cardioactive drugs.

The dog heart-lung preparations were prepared. The "equilibrium point", which could be defined as the point at which the cardiac output (CO)-curve and the venous return (VR)-curve crossed, when the CO and VR were plotted against the right atrial pressure, was recorded directly by utilizing an X-Y recorder. The CO-curve was obtained, as a locus of the equilibrium point, by raising and lowering the level of blood in the venous reservoir (competence test). The meaning of the procedure was shown to increase or decrease the mean systemic pressure, and to cause the corresponding parallel shift in the VR-curve. The VR-curve was obtained by changing myocardial contractility. When heart failure was induced by pentobarbital or by chloroform, the equilibrium point shifted downwards to the right, depicting the VR-curve. During development of the failure, the slopes of CO-curves decreased gradually. Effects of cinobufagin and norepinephrine were also analyzed. Utilization of the X-Y recorder enabled us to settle the uniform experimental conditions more easily, and to follow the effects of drugs continuously on a diagram equating the CO- and VR-curves (Gyton's scheme).

Animals↗