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T Ohyama

Publications and source records attributed to T Ohyama.

At least 235 records · Page 13Linked to original sources
PubMed1990

Electrofocusing analysis of DNA polymerase beta in hypophysectomized rat testis.

Isoelectric focusing studies indicated that three peaks of DNA polymerase beta (beta-enzyme) activity were focused at isoelectric point of 7.1, 8.2 and 9.1 in testes of sham-operated rats, whereas in testes of hypophysectomized rats only two peaks of the beta-enzyme activity appeared at pH 7.1 and 9.1 and the peak at pH 8.2 was reconstituted by the treatment of gonadotropins and testosterone. In the brain hypophysectomy did not affect the activities of isoelectrically different beta-enzymes. These facts imply that under in vivo conditions the beta-enzymes in testes focused at different isoelectric points are modified with unknown factors and the beta-enzyme focused at pH 8.2 is affected by pituitary hormones.

Animals↗
PubMed1990

[Antigenic recognition of rats infected with Gnathostoma hispidum: comparison of antigens derived from the advanced third stage larvae of Gnathostoma hispidum and Gnathostoma doloresi].

To increase understanding of immune response of host against G. hispidum, antigenic recognition of rodent gnathostomiasis were identified by the immunoblot method after PAGE of the advanced third stage larvae of G. hispidum and G. doloresi. The molecular weight of the major antigenic bands of G. hispidum extracts were 35 kDa and 16 kDa, and of G. doloresi were 48 kDa, 37 kDa and 35 kDa. Of these bands, the 35 kDa antigen of G. hispidum and G. doloresi was recognized with the sera of rats infected with G. hispidum 5 weeks after inoculation. Lecting staining with endoglycosidase-H or hydrolytic degradation on nitrocellulose strips revealed that the 35 kDa band of G. hispidum possessed the mannose-rich oligosaccharides. On the other hand, the band of G. doloresi had the hybrid-type glycopeptides. The larval extracts and excretory-secretory materials of G. hispidum were not antigenitically identical.

Animals↗
PubMed1990

Diuretic effects of L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS) in anesthetized rats.

A synthetic amino acid, L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS), can be converted to (-)-norepinephrine (NE) by aromatic L-amino acid decarboxylase (AADC) in various mammalian tissues. Recent studies have indicated the pressor and diuretic effects of L-threo-DOPS. In this study, we examined the effects of L-threo-DOPS on renal hemodynamics and function in anesthetized rats, and evaluated possible mechanisms of the diuresis. Intravenous infusion of L-threo-DOPS at 120 micrograms/kg/min exerted a significant increase in mean arterial pressure (MAP). There was a slight but nonsignificant decrease in renal blood flow (RBF). Although the glomerular filtration rate (GFR) remained at a constant level, urine flow (UF) and urinary sodium excretion (UNaV) increased significantly during the drug infusion. Pretreatment with AADC inhibitor, benserazide, completely blocked both the pressor and diuretic effects of L-threo-DOPS. When the renal perfusion pressure was protected from the pressor effect of the drug by using a Blalock clamp, the drug-induced diuresis was abolished. The diuretic effect of L-threo-DOPS was markedly attenuated by the administration of phentolamine. There was a positive correlation between plasma NE concentration and UF during the infusion of L-threo-DOPS. Intrarenal arterial infusion of L-threo-DOPS at 20 micrograms/kg/min was without effect on renal function. These results indicate that diuresis and natriuresis induced by L-threo-DOPS are dependent on the pressor effect of NE via peripheral alpha-adrenoceptor activation.

Anesthesia↗
PubMed1990

Ca2(+)-dependent and independent mechanisms of sustained contraction in vascular smooth muscle of rat aorta.

Norepinephrine (NE), prostaglandin F2 alpha (PG), 12-deoxyphorbol 13-isobutyrate (DPB) and high K+ induced sustained increase in cytosolic Ca2+ [( Ca2+]i) and muscle tension in rat aorta. Verapamil, at the concentration which abolished the high K(+)-induced changes, also abolished the increase in [Ca2+]i due to NE, PG and DPB although contractions were only partially inhibited. Excess EGTA further decreased [Ca2+]i although a part of the contraction was not inhibited. These results indicate that the sustained contractions induced by NE, PG and DPB are due to increase in [Ca2+]i, increase in Ca2+ sensitivity of contractile elements, and a Ca2(+)-independent mechanism.

Animals↗
PubMed1990

Effects of BRL 34915 (cromakalim) on renal hemodynamics and function in anesthetized dogs.

The effects of BRL 34915, a newly developed potassium channel opener, on renal hemodynamics and function were investigated in anesthetized dogs. An i.v. injection of BRL 34915 (4, 20 and 100 micrograms/kg) caused a dose-related reduction of mean arterial pressure but there were no significant changes in renal blood flow. The agent at lower doses (4 and 20 micrograms/kg) produced a slight increasing action on urine formation. When BRL 34915 was infused intrarenally at nonhypotensive doses (0.04 and 0.2 micrograms/kg/min), there were no significant increases in renal blood flow and glomerular filtration rate. At 1.0 micrograms/kg/min, a dose which produced a slight reduction in mean arterial pressure, significant decreases in calculated renal vascular resistance were observed, thereby indicating that BRL 34915 has vasodilator action on the renal vasculature. In cases of infusion at higher doses (0.2 and 1.0 micrograms/kg/min), the levels of urine flow, urinary excretion of sodium and fractional excretion of sodium were elevated significantly and these events were accompanied by decreases in urine osmolality. Although the intrarenal administration of BRL 34915 at higher doses produced no alterations in the fractional excretion of lithium (index of sodium excretion at the proximal tubules), the agent did increase the calculated value of the fractional distal excretion of sodium. These effects seen when BRL 34915 was infused intrarenally were suppressed markedly by glibenclamide (6 mg/kg i.v.), a putative inhibitor of the ATP-sensitive potassium channel. Our results suggest that BRL 34915 has renal vasodilating and diuretic effects as a result of opening the potassium channels within the kidney. The agent-induced diuresis may be due partly to an inhibitory effect on sodium reabsorption at the distal portion of the tubules beyond the proximal tubules.

Animals↗
PubMed1990

Splenic amyloidosis: correlations between chemical types of amyloid protein and morphological features.

Sixty-one autopsy cases of splenic amyloidosis were reviewed to assess the relationship between the morphological patterns and chemical types of amyloid protein. On the basis of immunohistochemical reactions of amyloid protein, the cases were classified into 34 cases of AA and 27 of AL amyloidosis. Amyloid deposition in the spleen was divided into three major sites: the red pulp, the white pulp, and blood vessels. Red pulp involvement by amyloid was noted in 52% of the AL cases but in none of the AA cases. White pulp amyloid deposition was found in 70% of the AL and 35% of the AA cases. This difference was statistically significant (P less than 0.001). On the other hand, vascular deposition of amyloid was invariably noted in all cases with AA or AL amyloidosis, affecting the AA cases rather severely. These results strongly suggest that the widely held concept of deposition of amyloid as predominantly vascular in AL amyloidosis and parenchymal in AA amyloidosis requires revision. Our findings indicate that parenchymal, especially the red pulp, involvement is a consistent feature of AL amyloidosis, whereas vascular involvement is a finding common to both types of systemic amyloidosis.

Adult↗
PubMed1990

[A continuous-step density percoll gradient for use in AIH and life table analysis of pregnancy rates].

For use in artificial insemination with husband's semen (AIH), a continuous-step Percoll density gradient technique was used to wash and concentrate sperm from ejaculate. To evaluate usefulness, the pregnancy rates were analyzed by the life table method. 1. After washing by the continuous-step Percoll density gradient method, sperm density increased from 28.8 X 10(6)/ml (original semen) to 40.9 X 10(6)/ml and sperm motility improved from 52.4% (original semen) to 77.0% respectively. 2. A group of 119 infertile patients whose diagnosis involved oligoasthenozoospermia, cervical factor and unexplained infertility were selected for AIH. After 640 insemination cycles, 37 women conceived with a pregnancy rate of 31.1%. By using life table analysis, the cumulative conception probability rate reached 0.652 after 13 insemination cycles. 3. Cumulative pregnancy rates by diagnostic category were 0.494 in male factor and 0.745 in cervical factor after 12 cycles, respectively. 4. The poorest results were obtained in unexplained infertility with a cumulative pregnancy rate of only 0.355 after 12 cycles. 5. In the follow up study, 24 viable babies were born and seven (18.9%) resulted in spontaneous abortion in the first trimester. These results indicate that the continuous-step Percoll density gradient technique is useful for improving the pregnancy rate in AIH.

Adult↗
PubMed1989

Effects of endothelin on renal function and renin secretion in anesthetized rats.

The infusion of endothelin into the renal artery of anesthetized rats at 1 ng/kg per min, a dose with no influence on renal function, had no effect on the basal levels of plasma renin activity (PRA) and renin secretory rate (RSR), but significantly inhibited the isoproterenol-induced increases in PRA and RSR. Endothelin, 2 ng/kg per min, elicited significant decreases in renal hemodynamics and in urine formation but the mean arterial pressure was not affected. The possibility that endothelin may participate in controlling renal function and renin secretion in vivo warrants further attention.

Anesthesia↗
PubMed1989

Upstream half of adenovirus type 2 enhancer adopts a curved DNA conformation.

The putative enhancer domain of human adenovirus type 2 (Ad2) was revealed to contain a bent DNA structure in the upstream half. By using "deletion analysis", this unusual structure was identified experimentally to span from nucleotide 194 to 269 (figures; nucleotide numbers from the left terminal nucleotide of the viral DNA). This region has almost the same nucleotide sequence as the upstream half of the enhancer and packaging region of Ad5 and, therefore, is thought to contain multiple enhancer elements for transcription and the elements required for packaging of Ad2 DNA. The bent DNA structure of this region was further characterized by analyzing temperature-dependent changes in electrophoretic mobility of the DNA fragments used for bending analysis. Ad2 enhancer provides a good system to investigate the relationship between higher order structure of DNA and transcriptional activation.

Adenoviruses, Human↗
PubMed1989

Endothelin immunoreactivity in medium from cultured porcine aortic endothelial cells correlates with the biological activity.

Using the radioimmunoassay (RIA) of endothelin (ET), we measured immunoreactive ET (IR-ET) in culture medium of porcine aortic endothelial cells. The immunoreactivity in the medium was compared with the biological activity. The amount of IR-ET released into the medium was calculated at 250-350 pg/10(6) cells/hr. The amount of IR-ET released into the culture medium increased progressively with 3-24 hr of incubation and corresponded to the increase in medium-induced vasoconstriction of rat isolated aorta. When the vasoconstrictor activities in the culture medium were plotted against the IR-ET concentration determined by RIA, the concentration-response curve showed similarity to that obtained with synthetic porcine ET. This RIA system will be a useful for investigating mechanisms of ET secretion from endothelial cells.

Animals↗
PubMed1989

Hepatic blood flow and drug metabolism in glycerol-rechallenged rats.

To analyze the hepatic blood flow and drug metabolism during glycerol-induced acute renal failure, 24 male Wistar rats were randomly divided into three groups: Group I received an intra-muscular injection of 1 ml/100 g body weight 50% glycerol, group II a second injection on day 14 and group III a second injection on day 42 after the first injection respectively. The inulin clearance, the aminopyrine N-demethylase activity, the NADPH-cytochrome P-450 activity and the cardiac output and blood flow to the organs were measured before and after glycerol injection. The total hepatic and renal blood flow decreased less significantly in group II compared to group I and III. Various P 450 activities were kept on a high level only in group II. This observation indicates that the maintenance not only of renal but also of hepatic blood flow plays an important role in preventing the development of glycerol-induced acute renal failure. The mechanism may be the induction of various P 450 activities resulting in an increased hepatic clearance of nephrotoxic substances.

Acute Kidney Injury↗
PubMed1989

Effects of Bay K 8644 on renal function and renin secretion in anesthetized rats.

Our previous study on kidney cortical slices showed that Bay K 8644, a dihydropyridine calcium channel agonist, produced a dose-dependent inhibitory action on the release of renin. The present study was performed to examine the effect of Bay K 8644 on renal function and renin secretion in vivo. When Bay K 8644 was directly infused into the renal artery of anesthetized rats, 2 micrograms/kg/min had no effect on renal blood flow (RBF) and glomerular filtration rate (GFR), but decreased urine flow (UF), urinary sodium excretion (UNaV) and fractional sodium excretion (FENa) by about 30%, 55% and 35%, respectively, thereby suggesting that Bay K 8644 enhanced the tubular reabsorption of water and sodium. When 10 micrograms/kg/min were infused, RBF, GFR, UF, UNaV and FENa decreased to about 95%, 70%, 35%, 35% and 30% of each control value. The administration of Bay K 8644 at 10 micrograms/kg/min did not influence the basal levels of plasma renin activity (PRA) and renin secretion rate (RSR), but did inhibit significantly isoproterenol-induced increasing effects on PRA and RSR. These results indicate that the activation of voltage-dependent calcium channels with Bay K 8644 influences the control of renal function and renin secretion in vivo.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1989

The endothelium-derived vasoconstrictor peptide endothelin inhibits renin release in vitro.

The effect of endothelin, a newly identified endothelium-derived vasoconstrictor peptide, on renin release from rat kidney cortical slices was examined. Endothelin produced a concentration-dependent inhibition of renin release and this inhibitory effect was dependent on extracellular calcium. The dihydropyridine calcium channel blockers nifedipine and nicardipine did not antagonize the inhibitory effect induced by endothelin. On the other hand, nifedipine completely antagonized the extracellular high potassium- or Bay K 8644-induced inhibition of renin release. The endothelin-induced inhibition of the release was markedly blocked by the addition of Co2+. Similar blocking effects of Co2+ were also observed with extracellular high potassium or Bay K 8644. Thus, endothelin exerts an inhibitory action on renin release in vitro, in a calcium-dependent manner. This inhibition may be mediated by the increased calcium influx through dihydropyridine-insensitive calcium channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1989

Spontaneous recovery from hypopituitarism due to postpartum hemorrhage.

A rare case is presented of a woman with spontaneous recovery from hypopituitarism following postpartum hemorrhage. One month after delivery, serum thyroid hormone, TSH, LH and FSH levels were low, and their secretion from the pituitary gland responded poorly to the TRH and LH-RH tests. Pituitary TSH response was normal 3 months after delivery. In the LH-RH test, pituitary LH and FSH response returned to normal at 2 months. Pituitary GH secretion and serum cortisol levels induced by ITT already responded normally one month postpartum. Excessive secretion of pituitary PRL was observed 3 months after delivery and improved gradually thereafter. These results indicate that the secretion of pituitary tropic hormones was sensitive to pituitary ischemia in the following order: TSH, gonadotropin, GH and ACTH. The disturbance of these hormones also persisted in the same order.

Adult↗