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Biomedical subjects

H Uchiyama

Publications and source records attributed to H Uchiyama.

At least 19 recordsLinked to original sources
PubMed1998

Direct binding of follistatin to a complex of bone-morphogenetic protein and its receptor inhibits ventral and epidermal cell fates in early Xenopus embryo.

In early development of Xenopus laevis, it is known that activities of polypeptide growth factors are negatively regulated by their binding proteins. In this study, follistatin, originally known as an activin-binding protein, was shown to inhibit all aspects of bone morphogenetic protein (BMP) activity in early Xenopus embryos. Furthermore, using a surface plasmon resonance biosensor, we demonstrated that follistatin can directly interact with multiple BMPs at significantly high affinities. Interestingly, follistatin was found to be noncompetitive with the BMP receptor for ligand binding and to form a trimeric complex with BMP and its receptor. The results suggest that follistatin acts as an organizer factor in early amphibian embryogenesis by inhibiting BMP activities by a different mechanism from that used by chordin and noggin.

Animals↗
PubMed1998

Circadian rhythms of rod-cone dominance in the Japanese quail retina.

When the Japanese quail is held in constant darkness, retinal responses (ERG b-waves) increase during the animal's subjective night and decrease during its subjective day. Rod photoreceptors dominate the b-wave responses (lambdamax = 506 nm) to all stimulus intensities at night but only to those intensities below the cone threshold during the day. Above the cone threshold, cones dominate b-wave responses (lambdamax, approximately 550-600 nm) during the day regardless of the state of retinal adaptation. Apparently a circadian oscillator enables cone signals to block rod signals during the day but not at night. The ERG b-wave reflects the activity of bipolar cells that are postsynaptic to rods and cones. The ERG a-wave reflects the activity of both rods and cones. The amplitude of the isolated a-wave (PIII) changes with time of day, as does that of the b-wave, but its spectral sensitivity does not. The PIII responses are maximal at approximately 520 nm both day and night and may reflect multiple receptor mechanisms. The shift in rod-cone dominance detected with the ERG b-wave resembles the Purkinje shift of human vision but, unlike the Purkinje shift, does not require a change in ambient light intensity. The shift occurs in constant darkness, with a period of approximately 24 hr indicative of a circadian rhythm in the functional organization of the retina.

Adaptation, Ocular↗
PubMed1998

Three-dimensional ultrastructure of apoptotic nuclei in rat prostatic epithelial cells revealed by a quick-freezing and deep-etching method.

BACKGROUND: To clarify intranuclear apoptotic changes, we have investigated chromatin organization in apoptotic nuclei of castrated rat prostatic cells by a quick-freezing and deep-etching (QF-DE) method. METHODS: The ventral prostates taken from intact and castrated adult male rats were investigated by light microscopy, in situ end-labeling (ISEL) technique, conventional electron microscopy, and the QF-DE method. RESULTS: In control nuclei, the chromatin fibers were uniformly distributed and formed a network structure. In apoptotic nuclei, destruction of such chromatin networks was detected, which was clearly seen by the QF-DE method. Although it first appeared spotty in the apoptotic nucleus, definite destruction of the intranuclear network occurred in the nuclear center at later stages, and broken fibrous structures were condensed along the nuclear margin. The ISEL technique was applied to the QF-DE method. Localization of damaged DNA fragments could three-dimensionally be detected on replica membranes. CONCLUSIONS: Intranuclear chromatin organization in apoptotic cell death of rat prostates was observed by the QF-DE method. We could examine early-stage apoptotic nuclei at an electron microscopic level, which would not be clarified by other conventional methods.

Animals↗
PubMed1998

Intracellular distribution of the Wilson's disease gene product (ATPase7B) after in vitro and in vivo exogenous expression in hepatocytes from the LEC rat, an animal model of Wilson's disease.

In patients with Wilson's disease, both copper incorporation into ceruloplasmin and excretion of this metal into bile are impaired. These conditions are caused by a genetic defect in the Wilson's disease gene (ATP7B). To investigate the Wilson's disease gene protein (ATPase7B) in hepatocytes, we constructed an expression plasmid carrying full-length complementary DNA for human Wilson's disease gene and attempted to express the gene in hepatocytes of LEC rats, an animal model of Wilson's disease. Transfection of hepatocytes, either in vitro or in vivo, was done using a newly developed cationic liposome containing 1,4-bis(3-(N-hexadecyl) aminopropyl) piperazine. Immunological analyses of human ATPase7B with specific monoclonal antibodies showed human ATPase7B to be a membrane protein with a molecular mass of 155 kd. Analysis of human ATPase7B expressed in hepatocytes from LEC rats suggested that this protein is present in the trans-Golgi network and at the plasma membrane, a distribution pattern similar to that of Menkes' disease protein (ATPase7A). These findings suggest that these two putative copper-transporting P-type ATPases function similarly at the cellular level. Cotransfection and coexpression of the human Wilson's disease gene and ceruloplasmin gene in cultured hepatocytes indicate that the distribution of ceruloplasmin is always accompanied by ATPase7B at the perinuclear region, but that part of ATPase7B localizes irrespective of the distribution of ceruloplasmin. Based on these investigations, we propose that ATPase7B exists in the trans-Golgi network and transports copper into this compartment. This seems to ensure an appropriate delivery of copper to the apoceruloplasmin. On the other hand, part of ATPase7B that is not accompanied by ceruloplasmin in the perinuclear region and at the plasma membrane seems to contribute to efflux of this metal from the hepatocytes. Thus the distribution patterns of ATPase7B in hepatocytes may explain the dual roles of this P-type ATPase in hepatocytes.

Adenosine Triphosphatases↗
PubMed1998

Effects of the ATP-sensitive K channel opener nicorandil on the QT interval and the effective refractory period in patients with congenital long QT syndrome. Investigator Group for K-Channel Openers and Arrhythmias.

Congenital or idiopathic long QT syndrome is characterized by a frequently lethal ventricular arrhythmia called torsades de pointes (TdP) as well as a prolonged QT interval. The long QT interval related to an abnormal gene of the Na+ channel has been shown to be shortened by mexiletine. However, the action of K+ channel openers on the QT interval associated with abnormal genes of the K channel has yet to be studied. Seven patients of five families with long QT syndrome were included in this study, of whom six had syncope and six had documented TdP. Either long QT interval or sudden cardiac death had been observed in family members of all seven patients. At 1 to 3 weeks after admission, when TdP or frequent ventricular arrhythmia had subsided, nicorandil, an ATP-sensitive K channel opener, was administered orally at a dose of 15 mg/day in five patients and at 30 mg/day in the remaining two patients, and the effects were assessed on the third day after drug administration. In four patients, the effective refractory period was measured in the right ventricle before and after administration of K channel opener administration. The QT interval (QTc) prior to administration of the K channel opener was 0.60 +/- 0.09 ms (mean +/- SD) (0.61 +/- 0.10 second(1/2)), which was shortened to 0.54 +/- 0.05 ms (0.55 +/- 0.06 second(1/2)) on the third day of drug administration (P < .05 for both): 10.4 +/- 8.0% (8.6 +/- 5.5%). The QT interval at varying preceding R-R intervals on Holter electrocardiograms showed a shift toward the right as a result of the drug administration. The effective refractory period showed a significant prolongation, 256 +/- 26 ms versus 280 +/- 22 ms before and after drug administration, respectively (P <.05). Intravenous administration of nicorandil resulted in no significant change in heart rate or blood pressure, while QTc showed a tendency to shorten, but nonsignificantly (P = .08). However, a hump on the monophasic action potential was abolished, especially at the long preceding R-R interval induced by premature stimulation of the ventricle. It is concluded that nicorandil shortens the QT interval slightly when administered orally, whereas the effective refractory period shows a slight prolongation. The physiologic and clinical significance of these effects needs to be studied further.

Administration, Oral↗
PubMed1998

Bronchiolitis obliterans after bone marrow transplantation: evaluation with lung scintigraphy.

Bronchiolitis obliterans (BO) has been described as a main pulmonary complication following allogeneic bone marrow transplantation (BMT). Diagnosis of BO is usually based on clinical findings, pulmonary function tests, and computed tomography scan. However, histological examination of an open-lung biopsy specimen may sometimes be necessary to confirm the diagnosis, despite its relative invasiveness. The ventilation lung scan is another useful but non-invasive diagnostic method. In this study, we present two post-transplant BO cases, each showing different clinical conditions, characterized by delayed wash-out on 133Xe gas and airway depositions on radioaerosol inhalation scans. These methods succeeded in revealing pulmonary obstruction in cases where the pulmonary function tests were within normal range and the high-resolution CT scans (HR-CT) of the chest were only minimally abnormal, suggesting their usefulness as an additional tool in the diagnosis of post-transplant BO, as well as in the follow-up to pulmonary obstruction.

Adult↗
PubMed1998

Frequency dependent shortening of conduction time through the reentrant pathway during transient entrainment of ventricular tachycardia.

In a patient with nonischemic ventricular tachycardia (VT), VT was entrained and the conduction time from the pacing site to the entrained local electrogram showed a rate dependent shortening and its degree affected by the pacing site. The QRS complex, which was entrained by the last pacing stimulus, was constant and identical to that of VT and no rate dependent facilitated conduction was observed when the heart was paced at similar paced cycle lengths during sinus rhythm. As the mechanism of the shortening of the conduction time through the reentrant circuit, a shift of the entrance seems most likely.

Aged↗
PubMed1998

[Survival of Vibrio cholerae non-O1 in river sediment during cold season].

To assess the existence of Vibrio cholerae non-O1 in the environment water system during the cold season, the organism was incubated in both river sediment or terrestrial soil as particle matter-water (1:1) suspension. The low temperature condition was set to 5 degrees and 10 degrees C. At 5 degrees C, V. cholerae non-O1 did not grow in any medium, sediment and soil. At 10 degrees C, the decrease of the number of organisms was delayed in river sediment as compared with peptone medium. At 30 degrees C, the organism grew in river sediment and its extract solution. In soil, the organism was decreased immediately under low temperature. Though the number of organisms was decreased temporarily in soil, its number was maintained within 14 days at 30 degrees C. But in the extract solution from soil, the organism was decreased immediately under 5 degrees, 10 degrees, 20 degrees, 30 degrees C. It showed that survival of V. cholerae non-O1 was maintained in particle substances contained water. These results suggested that V. cholerae non-O1 would be able to exist in river sediment during the cold season.

Cold Temperature↗
PubMed1998

[A number of Vibrio cholerae non-O1 isolated from aquatic environments].

To estimated existence of Vibrio cholerae non-O1 in aquatic environments, the organisms isolated from river, estuary and sea water. V. cholerae non-O1 isolated form midstream and estuary water could be counted from 1.6 to 2400 CFU/100 ml by the membrane filtrated method (MF). V. cholerae non-O1 existed in midstream water more than in estuary water. However, the isolated organisms from estuary rate by MF (37.5%) was lower than it by alkaline peptone enrichment medium method (AP) (75.0%), as a result of halophilic bacteria grow an selected medium of MF. And the number of V. cholerae non-O1 isolated from aquatic environment did not correlate environmental parameters. The number of V. cholerae non-O1 isolated from river water varied, it suggested that the organism collectively adhere a floating matter. V. cholerae non-O1 was not detected in 500 ml sea water by AP and MF method. These results conclude that V. cholerae non-O1 exist in river water more than in sea.

Cell Count↗
PubMed1998

Effect of thromboxane synthetase inhibitor on non-heart-beating donors in rat orthotopic liver transplantation.

BACKGROUND: The use of non-heart-beating donors could relieve donor organ shortage provided that the outcome of the recipients is not jeopardized. METHODS: In this study we evaluated the effect of thromboxane synthetase inhibitor (OKY-046) on non-heart-beating donors in orthotopic liver transplantation in rodents. OKY-046 (OKY group, n = 8) or vehicle (control group, n = 8) was given to the donor animals for 60 minutes before the induction of 30 minutes of warm ischemia to the liver before transplantation and survival, and several parameters were compared between the two groups. RESULTS: All recipients in the control group died within 2 days, whereas 67% of those of the OKY group had a 2-day survival and 44% had a 2-week survival (p < 0.01). Bile output from the allograft for 2 hours after reperfusion was significantly larger in the OKY group at all time points (p < 0.05). Furthermore, serum transaminase levels 10 minutes after reperfusion were significantly lower in the OKY group (p < 0.05), although those 120 minutes after reperfusion were comparable between the two groups. The thromboxane B2 level in liver tissue 10 and 120 minutes after reperfusion was significantly lower in the OKY group compared with the control group (p < 0.02 and p < 0.05, respectively). CONCLUSIONS: These results indicate that OKY-046 given to the donor before the induction of warm ischemia could ameliorate ischemia/reperfusion injury of the hepatic allograft by reducing thromboxane A2 production after reperfusion.

Alanine Transaminase↗
PubMed1997

Effects of estrogenic hormones on early development of Xenopus laevis.

Many chemicals released into the environment have estrogenic activity and can disrupt animal development and the function of endocrine systems. In order to study the effects of estrogens on aquatic animals, we examined the effects of certain estrogens on early development in Xenopus laevis. X. laevis embryos were kept in water containing 10(-10), 10(-9), 10(-7), 10(-6), and 10(-5) M 17 beta-estradiol (E2); 17 alpha-estradiol; diethylstilbestrol (DES); 10(-5) M progesterone (P); or dihydrotestosterone (DHT) beginning at developmental stage 3. Survival rates of the embryos developed in water containing 10(-10)-10(-6) M E2 or DES, all concentrations of 17 alpha-estradiol, and 10(-5) M P or DHT, which were over 70% after stage 48, whereas the rates of the embryos treated with 10(-5) M E2 and DES decreased remarkably after stage 27 and all embryos were dead by stages 42 and 32, respectively. Embryos treated with 10(-5) M E2 showed malformations of the head and abdomen and suppressed organogenesis, including crooked vertebrae at stage 38; the head was smaller and the abdomen was larger than in the controls. Similar effects were observed in embryos developed in 10(-5) M DES but not in 10(-5) M 17 alpha-estradiol, P, or DHT. After 10(-5) M E2 treatment, abnormalities were induced only when the treatment was started before stage 39. However, on day 30 after fertilization, the stage of the embryos treated with 10(-6) M E2 was more progressed than that of the controls. Estrogen receptor (ER 4) mRNA was examined in eggs, embryos, and adult female liver by reverse-transcription polymerase chain reaction. ER4 mRNA was expressed in adult liver, unfertilized and fertilized eggs, and embryos, but ER3 mRNA was not expressed. ER4 mRNA in 10(-6) and 10(-5) M E2-treated embryos showed different expression patterns, which may result from the diverse developmental effects of E2. The present results demonstrate that 10(-5) M E2 and DES induced embryo death and malformations and that ER may be involved in the induction of various developmental defects in X. laevis embryos.

Abdomen↗
PubMed1997

Phase Behavior of a Water/Nonionic Surfactant/Oil Ternary System in the Presence of Polymer Oil

The effect of a polymer oil, polydimethyl siloxane, on the phase behavior of the water/C12EO6/isopropyl myristate (IPM) system has been studied. Since the polymer oil is completely soluble in IPM, it was dissolved in IPM and the solutions were used as the oil phase to study its effect. The presence of polymer increases the hydrophobic nature of IPM and thereby decreases the solubilization of oil into the surfactant phase (microemulsion). Moreover, at a certain range of silicone oil concentration in the IPM, a four-phase body consisting of excess water, excess oil, and two surfactant phases is formed within the ternary system. The two surfactant phases are designated as D (with bicontinuous type of structure) and D' (with L3 type of structure). Careful phase behavioral studies revealed that, with increasing silicone oil concentration, a three-phase region containing water phase, D' phase, and an oil-rich D phase develops within the system and this region overlaps with the normal three-phase region of the system containing the water, D, and oil phases to give a four-phase body. The order of various phases from top to bottom in the four-phase body is oil, D, D', and water.

Journal Article↗
PubMed1997

Stent placement for recurrent vasospastic angina resistant to medical treatment.

The successful stent placement for treatment of recurrent vasospastic angina in a patient with nonstenotic coronary arteries is described. Use of the Palmaz-Schatz stent resulted in successful vasodilation that completely prevented anginal attacks. This procedure represents an alternative treatment for patients with vasospastic angina refractory to aggressive medical therapy.

Angina Pectoris, Variant↗
PubMed1997

Serum thrombopoietin levels in patients undergoing autologous peripheral blood stem cell transplantation.

Recently, the ligand for c-mpl has been cloned and initial studies have shown it to be the platelet regulatory factor, thrombopoietin (TPO). To elucidate the role of TPO in the reconstitution of megakaryopoiesis and platelet production after stem cell transplantation, we measured serum TPO levels in nine patients undergoing autologous peripheral blood stem cell transplantation (PBSCT) and in healthy volunteers. Serum TPO levels significantly correlated with the degree of peripheral thrombocytopenia and a strong inverse correlation between serum TPO level and platelet count was observed (r = -0.700, P < 0.001). Serum TPO levels began to rise as the platelet count decreased after chemotherapy, TPO levels peaked at over 25.00 fmoles/ml between days 0 and 10; TPO levels then decreased gradually as the platelet count began to rise. One patient with multiple myeloma received purified CD34+ peripheral blood stem cells. No difference was observed in the kinetics of serum TPO levels between unfractionated and purified PBSCT. These observations suggest that TPO plays a critical role in the reconstitution of megakaryopoiesis and platelet production after PBSCT.

Adolescent↗
PubMed1997

Distribution and localization of galectin purified from Rana catesbeiana oocytes.

Galectins are a family of lectins that recognize beta-D-galactosides independently of calcium ions, and are widely distributed in animals. To characterize a galectin previously purified from oocytes of Rana catesbeiana (American bullfrog), we studied its distribution and localization in several tissues from this frog. Hemagglutination assay and western blotting showed that this lectin is present in many tissues including the liver, skin, kidney, skeletal muscle, and sciatic nerve, but is particularly concentrated in the ovary. Light microscopic immunohistochemistry showed that this lectin is localized in such places as cell-cell junctions, basement membranes, extracellular matrix, or secretory substances in several organs, indicating that this galectin is mainly distributed extracellularly. However, in the ovary, light microscopy showed that this lectin is present in or associated with the yolk platelet. Electron microscopy further revealed that it is localized in the periphery of the yolk platelet (the yolk plasm), but not in the cortical granule. These results indicate that Rana oocytes contain abundant galectin in their yolk platelets in contrast to Xenopus laevis oocytes, which have been found not to contain galectins but other classes of lectins in their yolk platelets and cortical granules.

Amino Acid Sequence↗
PubMed1997

The soluble methane monooxygenase gene cluster of the trichloroethylene-degrading methanotroph Methylocystis sp. strain M.

In methanotrophic bacteria, methane is oxidized to methanol by the enzyme methane monooxygenase (MMO). The soluble MMO enzyme complex from Methylocystis sp. strain M also oxidizes a wide range of aliphatic and aromatic compounds, including trichloroethylene. In this study, heterologous DNA probes from the type II methanotroph Methylosinus trichosporium OB3b were used to isolate souble MMO (sMMO) genes from the type II methanotroph Methylocystis sp. strain M. sMMO genes from strain M are clustered on the chromosome and show a high degree of identity with the corresponding genes from Methylosinus trichosporium OB3b. Sequencing and phylogenetic analysis of the 16S rRNA gene from Methylocystis sp. strain M have confirmed that it is most closely related to the type II methanotroph Methylocystis parvus OBBP, which, unlike Methylocystis sp. strain M, does not possess an sMMO. A similar phylogenetic analysis using the pmoA gene, which encodes the 27-kDa polypeptide of the particulate MMO, also places Methylocystis sp. strain M firmly in the genus Methylocystis. This is the first report of isolation and characterization of methane oxidation genes from methanotrophs of the genus Methylocystis.

Amino Acid Sequence↗