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Biomedical subjects

H Uchiyama

Publications and source records attributed to H Uchiyama.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Hemostatic effect of a novel sheeted fibrin adhesive agent, TO-193, on experimental incision models].

TO-193 (TachoComb) is a new fibrin adhesive agent that consists of a collagen sheet coated with fibrin glue. We compared the hemostatic effect of TO-193 in several experimental models with Beriplast P as a fibrin adhesive agent, Avitene and Novacol as a microfibrillar collagen hemostat, and a sponge-like collagen sheet as the constitutional parts of TO-193. In the in vitro bleeding model in which blood leaks out through cotton cloth, the pressure of TO-193 when blood leakage was observed was higher than those of Beriplast P, Avitene, Novacol and the collagen sheet, indicating that TO-193 possessed a strong adhesive effect on the bleeding surface. On the kidney resection surface, TO-193 showed a more potent adhesive effect than those of Beriplast P and the collagen sheet, suggesting that TO-193 has a potent hemostatic effect. In the liver resection, TO-193 significantly reduced the bleeding volume compared with that of Novacol in normal rats. Furthermore, the bleeding volume of TO-193 was about half that of Beriplast P and equivalent to that of Novacol even in anticoagulant-treated rats. From these data, it is expected that TO-193 would be a valuable hemostatic agent for clinical use since TO-193 possesses a potent adhesive ability on the bleeding resection surface and would certainly stop bleeding in both patients with normal coagulation and those with a low blood coagulation condition.

Animals↗
PubMed1999

[Adhesive and sealing effects of TO-193 on tissues and organs in various experimental models].

We studied the adhesive and sealing effects of sheet style fibrin adhesive, TO-193 (TachoComb), on some tissues and organs, comparing them with those of sheet style collagen agent, collagen sponge, Novacol, and Avitene and liquid fibrin adhesive agent, Beriplast P. TO-193 showed more a potent adhesive effect on liver than the sheet style collagen agents and was more potent on bone and skin than the liquid fibrin adhesive agent. Furthermore, TO-193 had a potent sealing effect at the site of incomplete suture immediately after application on a motile organ such as lung and stomach. These effects may be partly attributable to rapid expression of the effect due to the presence of a high concentration of fibrinogen on coverage. Enhancement of fibrin penetrability to the tissues by compression and inhibition of cleavage of coverage by the collagen sponge also may be participating in the effects of TO-193. These results suggest that TO-193 will be a valuable adhesive and sealing agent.

Animals↗
PubMed1999

Beneficial effect of amiodarone on pacing induced terminability of reentrant ventricular tachycardia.

A 33 year-old woman was referred to our hospital for further treatment of ventricular tachycardia (VT). During treatment with amiodarone (200 mg/day), clinical VT at the cycle length of 510 ms was induced. During the VT, rapid ventricular pacing was repeated at progressively shorter cycle lengths after a decrement of 10 ms steps. The VT was entrained by the rapid pacing and reproducibly terminated at a paced cycle length of 380 ms. Four weeks after reducing the amiodarone to 100 mg/day, programmed stimulation was repeated. The VT with the same morphology but with a slightly shorter cycle length of 480 ms was again induced. However, at this time, rapid pacing from the same site could not terminate VT and transient acceleration developed at a shorter paced cycle length of 260 ms. The QT (QTc) interval, effective refractory period at the pacing site and width of the paced QRS complex were similar before and after changing the amiodarone treatment. The most characteristic change of VT in the second study was a widening of the entrainment zone, which was calculated as the difference between VT cycle length and the longest pacing cycle length which interrupts VT during the entrainment (from 130 to > 220 ms), and it may be explained by the preferential shortening of the action potential duration and/or facilitation of the depressed cell to cell conduction within the reentry circuit. Amiodarone must exert a preferential action in the reentry circuit and modulate the conduction property as well as the effective refractory period. We should pay close attention to the efficacy of antitachycardia pacing during the modification of amiodarone treatment.

Adult↗
PubMed1999

Post-traumatic pituitary apoplexy--two case reports.

A 60-year-old female and a 66-year-old male presented with post-traumatic pituitary apoplexy associated with clinically asymptomatic pituitary macroadenoma manifesting as severe visual disturbance that had not developed immediately after the head injury. Skull radiography showed a unilateral linear occipital fracture. Magnetic resonance imaging revealed pituitary tumor with dumbbell-shaped suprasellar extension and fresh intratumoral hemorrhage. Transsphenoidal surgery was performed in the first patient, and the visual disturbance subsided. Decompressive craniectomy was performed in the second patient to treat brain contusion and part of the tumor was removed to decompress the optic nerves. The mechanism of post-traumatic pituitary apoplexy may occur as follows. The intrasellar part of the tumor is fixed by the bony structure forming the sella, and the suprasellar part is free to move, so a rotational force acting on the occipital region on one side will create a shearing strain between the intra- and suprasellar part of the tumor, resulting in pituitary apoplexy. Recovery of visual function, no matter how severely impaired, can be expected if an emergency operation is performed to decompress the optic nerves. Transsphenoidal surgery is the most advantageous procedure, as even partial removal of the tumor may be adequate to decompress the optic nerves in the acute stage. Staged transsphenoidal surgery is indicated to achieve total removal later.

Adenoma↗
PubMed1999

[Management under anesthesia of a patient with renal cell carcinoma extending into the retrohepatic inferior vena cava with the aid of partial cardiopulmonary bypass].

A 70-year-old male with renal cell carcinoma extending into the retrohepatic inferior vena cava was scheduled for radical nephrectomy with vena caval resection under general anesthesia. He had received partial gastrectomy for gastric cancer twelve years before. Computed tomography and inferior vena cavography confirmed that the vena cava was almost completely occluded and that a collateral venous network was well established. It was considered that the surgical approach to the retrohepatic cavals area was technically very difficult, and that there was a high possibility of a pulmonary embolus during the surgical manipulation. To prevent a pulmonary embolus and get good control of the vena cava above the tumor and below the hepatic vein, we decided to use a partial cardiopulmonary bypass (CPB) until the vena cava was clamping above the tumor. Anesthesia was induced with propofol and fentanyl, and maintained with fentanyl and isoflurane-N2O-O2. In the partial CPB blood from the hepatic vein was drained from the inferior vena cava cannula through right atrium, oxygenated by microporus membrane oxygenator, and returned to the left femoral artery. Cannulation to drain the venous circulation entering the vena cava below the tumor was abandoned because the extensive collateral venous network ultimately drains into the superior vena cava. The partial CPB time was 90 min, and the bladder temperature during the CPB was 35-36 degrees C. During the 7.3 hr procedure, the pulmonary embolus did not occur and the total blood loss was 5515 ml. The patient made an uncomplicated recovery and was discharged 30 days after the operation. This newly reported partial-CPB method may be safe and effective for the management under anesthesia of other patients.

Aged↗
PubMed1999

Deletion variant of hepatocyte growth factor prolongs allograft survival after liver transplantation in rats.

BACKGROUND: Despite continued progress in the development of immunosuppressive agents, allograft rejection remains an important cause of morbidity and mortality after liver transplantation. We examined the effect of the deletion variant of hepatocyte growth factor (dHGF) on allograft rejection after liver transplantation. METHODS: Male Dark Agouti rats (RT1a) were selected as donors and male Lewis rats (RT1l) as recipients for a rejection model. The recipients were divided into 2 groups after orthotopic liver transplantation (OLTx): in the dHGF group dHGF was given intravenously twice a day (1 mg/kg/day) after OLTx, whereas in the control group vehicle buffer was given intravenously daily twice after OLTx. The survival period, serum chemistry studies, and histopathologic findings were then compared between the 2 groups. RESULTS: The mean survival period after OLTx in the dHGF group was significantly longer than that in the control group (21.4 +/- 1.3 days vs 11.8 +/- 0.4 days, P < .001). On the 10th posttransplant day the serum albumin level significantly improved in the dHGF group (P < .01), and the serum total bilirubin and aspartate aminotransferase levels were significantly lower in the dHGF group (P < .01 and P < .05, respectively). On the 10th posttransplant day a histologic examination revealed no apparent difference in the severity of rejection between the 2 groups. The number of proliferating cell nuclear antigen-positive hepatocytes in the dHGF group significantly increased (P < .01), whereas the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling-positive hepatocytes were significantly reduced in the dHGF group (P < .01) in comparison with those in the control group. CONCLUSION: dHGF has an antiapoptotic property as well as a proliferative and protective effect on hepatocytes under allograft rejection. dHGF might serve as a novel agent for reducing the harmful effects of hepatic allograft rejection in rats.

Amino Acid Sequence↗
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

Electrophysiological effects of amrinone on the automaticity and membrane current system of the rabbit sinoatrial node cells.

To elucidate the physiological role of phosphodiesterase (PDE) in cardiac pacemaker cells, we studied the electrophysiological effects of amrinone, an inhibitor of PDE type III, on the spontaneous action potential (AP) and membrane currents, using small preparations (0.2 x 0.2 x 0.1 mm) of rabbit sinoatrial (SA) node cells. Amrinone (0.1-1.0 mM) progressively increased the AP amplitude, maximal rate of depolarization, and spontaneous firing frequency, shortened the AP duration, and made the threshold potential more negative. In voltage-clamp experiments using double microelectrode techniques, 0.1 mM amrinone increased the Ca2+ current (I(Ca)) obtained on step depolarization from -40 to -10 mV by 25.86% +/-4.6% (P < 0.05, n = 6), the delayed rectifier K+ current (I(K)) tail obtained on repolarization from 10 to -60 mV by 22.8%+/-4.7% (P < 0.05, n = 6), and the hyperpolarization-activated inward current (Ih) at -90 mV by 19.5%+/-7.3% (P < 0.05, n = 6), respectively. Amrinone did not affect the slope factors of either the inactivation curve for I(Ca) (finfinity curve) or the activation curve for the delayed rectifier I(K) (pinfinity curve). These results suggest that this PDE III inhibitor exerts a positive chronotropic action by enhancing the availability and the conductance of all the tested membrane currents in rabbit SA node cells.

Action Potentials↗
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

Amelioration of liver injury by ischaemic preconditioning.

BACKGROUND: Ischaemic preconditioning, i.e. preparatory brief ischaemia before subsequent long ischaemia, can effectively protect the heart from ischaemia-reperfusion injury in animals. The purpose of this study was to demonstrate the same phenomenon in the liver. METHODS: Using warm ischaemia-reperfusion of 70 per cent of the liver followed by resection of the non-ischaemic portion in rats, livers with 10 min of ischaemic preconditioning, i.e. 10 min of warm ischaemia and reperfusion, were compared with those that had not been subjected to such a manoeuvre. RESULTS: At 120 min after reperfusion following 40 min of warm ischaemia, the livers with 10 min of ischaemic preconditioning had a significantly lower mean(s.d.) serum alanine aminotransferase level (492(217) versus 1236(695) units/l; P < 0005) and lactic dehydrogenase level (7905(4002) versus 15066(9201) units/l; P< 0.05), as well as a higher bile output (0.12(0.03) versus 0.09(0.04) ml per g liver; P < 0.05) and liver tissue adenosine 5'-triphosphate level (78(13) versus 61(11) per cent; P< 0.05) than the control livers. The necrosis rate, histologically defined as the percentage of necrotic area in given liver sections, was reduced significantly by this manoeuvre (mean(s.d.) 1.3(1.3) versus 5.3(1.7) per cent; P< 0.05). CONCLUSION: Ischaemic preconditioning exerts a protective effect on hepatic warm ischaemia-reperfusion injury. Such a manoeuvre may be useful for hepatic resection in the clinical setting.

Adenosine Triphosphate↗
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↗