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Biomedical subjects

Y Hara

Publications and source records attributed to Y Hara.

At least 433 records · Page 24Linked to original sources
PubMed1993

Cloning and expression of apical membrane water channel of rat kidney collecting tubule.

Concentrating urine is mandatory for most mammals to prevent water loss from the body. Concentrated urine is produced in response to vasopressin by the transepithelial recovery of water from the lumen of the kidney collecting tubule through highly water-permeable membranes. In this nephron segment, vasopressin regulates water permeability by endo- and exocytosis of water channels from or to the apical membrane. CHIP28 is a water channel in red blood cells and the kidney proximal tubule, but it is not expressed in the collecting tubule. Here we report the cloning of the complementary DNA for WCH-CD, a water channel of the apical membrane of the kidney collecting tubule. WCH-CD is 42% identical in amino-acid sequence to CHIP28. WCH-CD transcripts are detected only in the collecting tubule of the kidney. Immunohistochemically, WCH-CD is localized to the apical region of the kidney collecting tubule cells. Expression of WCH-CD in Xenopus oocytes markedly increases osmotic water permeability. The functional expression and the limited localization of WCH-CD to the apical region of the kidney collecting tubule suggest that WCH-CD is the vasopressin-regulated water channel.

Amino Acid Sequence↗
PubMed1993

Cardiovascular effects of central administration of cholinomimetics in anesthetized cats.

The cardiovascular effects of central administration of cholinomimetics were investigated in anesthetized cats, to identify the site and mechanism of their action. Physostigmine, 10-100 micrograms, given by intracerebroventricular administration (i.c.v.) caused a dose-dependent reduction in blood pressure and renal sympathetic nerve discharges and no change in heart rate, which were antagonized by intravenous injection (i.v.) of atropine but not by methscopolamine or pirenzepine, given intravenously. Carbachol 3-30 micrograms (i.c.v.) reduced blood pressure and renal sympathetic nerve discharges and caused no change in heart rate. The M1 muscarinic agonist, McN-A-343, 100-1000 micrograms (i.c.v.) did not affect blood pressure, heart rate or renal sympathetic nerve discharges. Bilateral application of physostigmine, 10-100 micrograms/site on the ventral medullary surface, decreased blood pressure and renal sympathetic nerve discharges but not heart rate. Carbachol, 3-30 micrograms/site, caused reductions in blood pressure and renal sympathetic nerve discharges and no change in heart rate. Atropine, but not pirenzepine or methscopolamine, reversed the effects of physostigmine or carbachol. Treatment with McN-A-343, 100-1000 micrograms/site, did not alter blood pressure, heart rate or renal sympathetic nerve discharges. Under pretreatment with atropine into the ventral medulla but not pirenzepine, physostigmine, given intravenously, did not influence blood pressure. It is concluded that a cholinergic mechanism, concerned with a depressor response, is located on the ventral medulla. Muscarinic receptors of the non-M1 subtype, possibly M2, are related to this mechanism.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1993

Inhibition of the infectivity of influenza virus by tea polyphenols.

(-)Epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) (1-10 microM) inhibited the infectivity of both influenza A virus and influenza B virus in Madin-Darby canine kidney (MDCK) cells in vitro. Study by electron microscope revealed that EGCg and TF3 (1 mM) agglutinated influenza viruses as well as did antibody, and that they prevented the viruses from adsorbing to MDCK cells. EGCg and TF3 more weakly inhibited adsorption of the viruses to MDCK cells. EGCg and TF3 (1-16 microM) also inhibited haemagglutination by influenza viruses. These findings suggest that tea polyphenols bind to the haemagglutinin of influenza virus, inhibit its adsorption to MDCK cells, and thus block its infectivity.

Animals↗
PubMed1993

Organ-specific unresponsiveness induced by intrathymic injection of donor bone marrow cells and a short course of immunosuppression in the rat heart transplantation model.

Donor- and organ-specific unresponsiveness to Brown Norway (BN) heart allografts was achieved in Lewis (LEW) rats by giving intrathymic donor bone marrow cells (ITBMC) and immunosuppression at the time of transplantation. Antilymphocyte serum (ALS) (1 ml, days 0, 2, 4) extended graft survival to a median survival time (MST) of 29.5 days (n = 6), while ALS + ITBMC extended survival to over 120 days (n = 6). FK506 (1 mg/kg, days 0, 2, 4, 6, 8) too prolonged survival in the FK + ITBMC (n = 6; MST > 140 days) and FK (n = 5; MST > 140 days) groups. BN skin grafting provoked the rejection of long-surviving BN heart grafts in the FK group (n = 5; MST = 14 days), but did not do so in either the ALS + ITBMC (n = 2; MST > 100 days) or the FK + ITBMC (n = 4; MST > 93 days) groups. In the FK + ITBMC group, two of the rats which rejected BN skin grafts received a second BN heart, resulting in the graft being accepted indefinitely (> 100 days) without causing the rejection of the first BN heart grafts. These facts suggest that ITBMC and concurrent T cell depletion are decisive for induction of unresponsiveness by this protocol. BN and WF (Wistar Furth) skin grafts were eventually rejected in the LEW rats which accepted BN heart grafts. Persistent allogeneic chimerism was demonstrated in the graft and recipient spleen, suggesting that chimerism may be one of the possible mechanisms of unresponsiveness.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Breed differences in the histochemical properties of the M. pubo-ischio-femoralis pars medialis myofibre of domestic cocks.

1. Histochemical properties of M. pubo-ischio-femoralis pars medialis (PIF muscle) were compared in 7 breeds of cocks. This muscle was largely composed of Type I fibres and their transitional form (Type I tr). Type IIA fibres were observed in the cranial part. 2. The weight and cross-sectional area of the PIF muscle increased with increasing body weight. However, the relative muscle development to body weight differed among the 7 breeds. 3. A quarter of Type I fibres were of the transitional variety in bantam fowls. Conversely, few, if any, Type I tr fibres were observed in the large breeds where the muscle was poorly developed. 4. As the histochemical properties of Type I fibres made an effective response to the different body weights and the relative PIF muscle development among breeds, it was concluded that PIF muscle performed an important function in supporting the body weight and maintaining posture.

Adenosine Triphosphatases↗
PubMed1993

Different growth rates of male chicken skeletal muscles related to their histochemical properties.

1. Early, M. pubo-ischio-femoralis pars medialis (PIF muscle) and late, M. iliotibialis lateralis pars postacetabularis (ITL muscle), maturing muscles were studied. These two muscles contained different populations of histochemical fibre types. 2. The profile measurements of the muscles showed diphasic allometric growth relative to the weights. In the early stage of growth (up to 15 weeks after hatching), the muscle length, width and depth all increased, while in the later stage (from 15 to 35 weeks) muscle growth resulted mainly from the marked increase in the depth and to a lesser degree, from an increase in the width. 3. Type I fibres, observed predominantly in PIF muscle matured earlier than the Type II fibres of ITL muscle. 4. From these results, the detailed process of skeletal muscle growth in the chicken was discussed.

Animals↗
PubMed1993

Effects of green tea catechins in a rat multi-organ carcinogenesis model.

The effects of dietary administration of green tea catechins (GTC) were examined using a multi-organ carcinogenesis model. Groups of 15 F344 male rats were initially treated with a single i.p. administration of 100 mg/kg body wt N-diethyl-nitrosamine, 4 i.p. administrations of 20 mg/kg body wt N-methylnitrosourea, 4 s.c. doses of 40 mg/kg body wt 1,2-dimethylhydrazine, together with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine for 2 weeks and then 0.1% 2,2'-dihydroxy-di-n-propylnitrosamine for 2 weeks, both in the drinking water, for a total initiation period of 4 weeks. GTC in the diet, at doses of 1.0 or 0.1%, was administered from 1 day before and during carcinogen exposure, after carcinogen exposure or both during and after carcinogen exposure. Further groups of animals were treated with carcinogen, 1% GTC or basal diet alone as controls. All animals were killed at the end of week 36, and all major organs examined histopathologically. The numbers of small intestinal tumors (adenomas and carcinomas) per rat were significantly reduced in the groups treated with 1% GTC during (0.13 +/- 0.35) and after carcinogen exposure (0.31 +/- 0.48) and in those receiving 1% and 0.1% GTC both during and after carcinogen exposure (0.14 +/- 0.36, 0.46 +/- 0.97 respectively) as compared with the carcinogen alone group (1.07 +/- 1.21). On the other hand, numbers of glutathione S-transferase placental form positive liver foci per cm2 were slightly but significantly increased in the groups treated with 1 and 0.1% GTC during carcinogen exposure, 1% GTC after carcinogen exposure and 1% GTC both during and after carcinogen exposure. The results indicated that while GTC inhibits small intestinal carcinogenesis it slightly enhances hepatocarcinogenesis in a dose dependent manner when applied both during and after carcinogen exposure.

1,2-Dimethylhydrazine↗
PubMed1993

Regulation of Na,K-adenosine triphosphatase gene expression by sodium ions in cultured neonatal rat cardiocytes.

Na,K-ATPase (Na,K-pump) plays an important role in the regulation of intracellular ion composition. The purpose of this study is to determine whether Na+ regulates the levels of mRNA coding for Na,K-ATPase alpha and beta subunits in cultured neonatal rat cardiocytes. We measured intracellular Na+ levels ([Na+]i) in cardiocytes using a Na(+)-sensitive fluorescence dye (SBFI). 1 mM ouabain caused a significant increase in [Na+]i in cardiocytes; from 12.8 +/- 0.3 to 28.8 +/- 1.8 mM. Exposure of cardiocytes to 1 mM ouabain resulted in a three- to fourfold increase in alpha 1, alpha 2, and alpha 3 mRNA accumulation, and an approximate two-fold increase in beta 1 mRNA accumulation. A maximum elevation was reached at 60 min in both cases. The ouabain-induced alpha 1 mRNA accumulation was still observed in the Ca(2+)-free culture medium. Exposure of cardiocytes to 10 microM monensin in the absence of extracellular Ca2+ also resulted in a threefold increase in alpha 1 mRNA accumulation. The increased alpha 1 mRNA expression by 1 mM ouabain was associated with a fourfold increase in alpha 1 subunit protein accumulation. Transfection experiments with chimeric plasmids containing 5'-flanking sequences of alpha 1, alpha 2, and alpha 3 isoform genes and a luciferase reporter gene revealed that 1 mM ouabain caused a twofold increase in luciferase activity in each alpha system. These results suggest that Na+ directly regulates Na,K-ATPase gene expression in cardiocytes. The transfection study further supports the premise that Na(+)-responsive elements are located within the 5'-flanking sequences of each alpha isoform gene.

Animals↗
PubMed1993

Effects of dietary tea catechins on alpha-tocopherol levels, lipid peroxidation, and erythrocyte deformability in rats fed on high palm oil and perilla oil diets.

The effects of dietary tea catechins on the levels of alpha-tocopherol and lipid peroxidation in both plasma and erythrocytes, as well as their effects on erythrocyte deformability, were examined in rats fed on high palm and perilla oil diets. The decrease in alpha-tocopherol concentration and the increase in lipid peroxidation level were much more pronounced in the perilla oil group than in the palm oil group. The addition of tea catechins to these diets significantly prevented the alpha-tocopherol concentration from decreasing. These results suggest that tea catechins may counteract a decrease in alpha-tocopherol by acting as an antioxidant in vivo. Furthermore, the lipid peroxidation in the plasma of rats fed perilla oil was slightly but significantly reduced by the supplemented tea catechins. However, no measurable differences were observed in the deformability of the erythrocytes in any of the groups. It is therefore likely that the erythrocytes are not severely enough affected by the lipid peroxidation to influence their deformability.

Animals↗
PubMed1993

[Effect of arotinolol on the incomplete tetanic contractions of the cat soleus muscle--relation to its anti-tremorgenic action].

The effect of arotinolol on the incomplete tetanic contractions of the cat soleus muscle was studied. Isoproterenol and epinephrine injected intravenously decreased the tension and degree of fusion of incomplete tetanic contractions of the soleus muscle in anesthetized cats. Intravenous arotinolol (> 3 micrograms/kg), propranolol (> 30 micrograms/kg) and pindolol (> 3 micrograms/kg) blocked the effects of isoproterenol and epinephrine, but atenolol (-300 micrograms/kg), prazosin (0.1-10 micrograms/kg) and phentolamine (10, 30 micrograms/kg) did not block them. These results indicate that the receptors involved can be classified as of the beta 2-type. It is proposed that arotinolol may inhibit beta 2-adrenoceptors in the extrafusal muscle fibers of slow muscle, and thereby reduces the amplitude of tremor by changing the incomplete tetanic contractions of the muscle to the complete ones.

Adrenergic beta-Antagonists↗
PubMed1993

Changes in reticuloendothelial function in dogs with endotoxin-induced shock.

A shock model was experimentally produced by intravenous injection of a lethal dose (3 mg/kg) of endotoxin under general anesthesia induced by pentobarbital sodium using 7 beagles. The effect of this endotoxic shock on the reticuloendothelial function was investigated. The blood endotoxin concentration peaked immediately after administration and decreased subsequently. However, the value still remained on an increased level (1,051 pg/ml) even at 360 min after endotoxin treatment. The lipid emulsion test as an index of reticuloendothelial phagocytotic activity and the arterial ketone body ratio as an index of the energy charge in the liver decreased after endotoxin treatment and failed to recover during the experiment. Fibronectin, one of opsonic proteins, tended to decrease after injection of the endotoxin and was significantly (p < 0.01) low at 180 and 360 min compared with the value before injection of the endotoxin. These results suggested the depression of the reticuloendothelial function during endotoxin-induced shock.

Animals↗
PubMed1993

Evaluation of extravascular thermal volume in the lung in dogs with endotoxin-induced shock by double indicator dilution method using heat and sodium ions.

Accuracy assessment was undertaken under varying hemodynamic conditions for a lung water volume measurement device which is based on the principle of a double indicator dilution method using heat and sodium ions. Changes in extravascular thermal volume were investigated in dogs with endotoxin-induced shock. The isoproterenol- or propranolol-induced changes in hemodynamics had no effect on the measurement. This confirmed the high accuracy of this measuring method. The measurement revealed a tendency for the extravascular thermal volume to gradually increase (p < 0.05) during endotoxin shock. This confirmed the gradual progression of pulmonary edema during endotoxin shock.

Animals↗
PubMed1993

Involvement of inhibin in the regulation of FSH secretion in prepubertal bulls.

To investigate the physiological importance of inhibin in the regulation of FSH secretion in prepubertal bulls, animals (6-month-old) were passively immunized against inhibin. Five animals were given an i.v. bolus injection of 50 ml inhibin antiserum raised against bovine 32 kDa inhibin in a castrated male goat, and four bulls were given the same amount of castrated male goat serum (control serum) as controls. Treatment with the inhibin antiserum resulted in a marked increase (P < 0.01) in plasma concentrations of FSH within 12 h compared with control animals, and FSH levels in immunized animals remained high until 168 h after the injection. Concentrations of plasma LH and testosterone in the immunized animals were not different from those in the control animals. The present findings provide strong evidence that inhibin plays an important role in the inhibitory regulation of FSH secretion in prepubertal bulls.

Animals↗
PubMed1993

[An elderly case of thrombotic thrombocytopenic purpura].

A 78-year-old woman was admitted to our hospital because of disorientation and fever on January 21, 1992. Two days before admission she experienced vomiting, anorexia and general malaise. Laboratory examinations on admission disclosed a hemoglobin level of 11.1 g/dl and a platelet count of 8,000/microliters. The peripheral blood smear revealed anisocytosis with numerous schistocytes and poikilocytes. Polychromatophilic and nucleated red blood cells were also seen, and the reticulocyte count was 38/1000. Her serum lactate dehydrogenase (LDH) value was 2,977 WU and the total serum bilirubin level was 3.5 mg/dl with 2.7 mg/dl indirect reacting fraction. Serum creatinine was 4.7 mg/dl. Her consciousness became semicomatose after a systemic seizure which lasted approximately 15 seconds and her hemoglobin level decreased to 8.5 g/dl on hospital day 2. Therefore, we diagnosed her as having thrombotic thrombocytopenic purpura (TTP) because of the presence of all 5 features, that is, thrombocytopenia, microangiopathic hemolytic anemia, fluctuating neurologic abnormalities, renal dysfunction and fever. A plasmapheresis with fresh frozen plasma (FFP) replacement was begun on that day. She was also treated with anti-platelet agents, 80 mg/day aspirin, and 300 mg/day dipyridamole. Moreover, packed red blood cells (PRC) were infused. While also receiving diphenylhydantoin and phenobarbital to prevent convulsions, status epilepticus developed on day 3. Because of inhibited spontaneous respiration which was an adverse effect derived from diazepam and sodium thiamylal administered intravenously to treat the status epilepticus, an artificial respiration was initiated.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

[A case of an infant on continuous ambulatory peritoneal dialysis who markedly improved in subjective symptoms after total parathyroidectomy and autotransplantation].

Total parathyroidectomy and autotransplantation to treat secondary hyperparathyroidism (SHP) have been often performed on adult patients with a favorable result, but have rarely been reported in the pediatric literature. We performed the above operations on a 4-year-7-month girl who was treated by continuous ambulatory peritoneal dialysis (CAPD). The postoperative levels of serum calcium remained low in spite of oral calcium and Vitamin D3 medication, and intravenous calcium administration. But an administration of calcium into CAPF fluid has been maintained the normal level of serum calcium. A calcium balance study conducted for 3 days starting the 24th postoperative day showed 391 mg/day of calcium absorption. The girl obtained a relief from the bone pain approximately 2 weeks after the operation and was able to run easily one and a half month after the operation. Total parathyroidectomy and autotransplantation were considered to be an effective treatment for severe symptoms of osteodystrophy in infantile patients with chronic renal failure.

Child, Preschool↗
PubMed1993

[A case of infective endocarditis with subaortic-valve aneurysm].

We report a 64-year-old female patient with a subaortic-valve aneurysm due to infective endocarditis, in whom the aneurysm and its perforation was detected by Doppler color flow imaging. She had severe aortic and mitral valve regurgitation, and underwent aortic valve replacement with plication of the aneurysm. Transthoracic echocardiography doesn't have enough usefulness to clarify periaortic-annular changes, but combination with Doppler color flow imaging is supposed to be informative for subaortic-valve changes same as transesophageal echocardiography especially in the cases with abnormal flow.

Aortic Aneurysm↗