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Biomedical subjects

K Minami

Publications and source records attributed to K Minami.

At least 199 records · Page 11Linked to original sources
PubMed1996

Diminished post-rest potentiation of contractile force in human dilated cardiomyopathy. Functional evidence for alterations in intracellular Ca2+ handling.

Post-rest contractile behavior of isolated myocardium indicates the capacity of the sarcoplasmic reticulum (SR) to store and release Ca2+. We investigated post-rest behavior in isolated muscle strips from nonfailing (NF) and endstage failing (dilated cardiomyopathy [DCM]) human hearts. At a basal stimulation frequency of 1 Hz, contractile parameters of the first twitch after increasing rest intervals (2-240 s) were evaluated. In NF (n = 9), steady state twitch tension was 13.7 +/- 1.8 mN/mm2. With increasing rest intervals, post-rest twitch tension continuously increased to maximally 29.9 +/- 4.1 mN/mm2 after 120s (P < 0.05) and to 26.7 +/- 4.5 mN after 240 s rest. In DCM (n = 22), basal twitch tension was 10.0 +/- 1.5 mN/mm2 and increased to maximally 13.6 +/- 2.2 mN/mm2 after 20 s rest (P < 0.05). With longer rest intervals, however, post-rest twitch tension continuously declined (rest decay) to 4.7 +/- 1.0 mN/mm2 at 240 s (P < 0.05). The rest-dependent changes in twitch tension were associated with parallel changes in intracellular Ca2- transients in NF and DCM (aequorin method). The relation between rest-induced changes in twitch tension and aequorin light emission was similar in NF and DCM, indicating preserved Ca(2-)-responsiveness of the myofilaments. Ryanodine (1 microM) completely abolished post-rest potentiation. Increasing basal stimulation frequency (2 Hz) augmented post-rest potentiation, but did not prevent rest decay after longer rest intervals in DCM. The altered post-rest behavior in failing human myocardium indicates disturbed intracellular Ca2- handling involving altered function of the SR.

Adult↗
PubMed1996

Inhibitory effects of propofol on catecholamine secretion and uptake in cultured bovine adrenal medullary cells.

In the central and peripheral noradrenergic neurons, the balance between noradrenaline release and reuptake determines the level of noradrenaline at the synaptic cleft or the nerve ending. In the present study, we examined the effects of propofol, an intravenous general anaesthetic, on catecholamine secretion and noradrenaline uptake in cultured bovine adrenal medullary cells and on the serum noradrenaline and blood pressure in rats. In cultured adrenal medullary cells, propofol (10-50 mumol/l) concentration-dependently inhibited catecholamine secretion stimulated by carbachol. Propofol suppressed carbachol-evoked 22Na+ influx as well as 45Ca2+ influx at concentrations similar to those which suppressed the catecholamine secretion. Propofol (10-50 mumol/l) also inhibited veratridine-evoked 22Na+ influx, 45Ca2+ influx and catecholamine secretion, whereas it had little effect on the 45Ca2+ influx and catecholamine secretion induced by 56 mmol/l K+. Cultured adrenal medullary cells show [3H] noradrenaline uptake which is sensitive to imipramine. Propofol (10-50 mumol/l) significantly inhibited the imipramine-sensitive uptake of [3H] noradrenaline. In rats, intravenous administration of propofol (2.5 mg/kg) lowered serum noradrenaline and arterial blood pressure. From these findings, in spite of inhibiting noradrenaline uptake, propofol at anaesthetic concentrations (10-30 mumol/l) seems to reduce catecholamine secretion by interfering with Na+ influx through voltage-dependent Na+ channels as well as nicotinic acetylcholine receptor-associated ion channels in the adrenal medulla and, probably, in the sympathetic nervous system. This may explain the propofol-induced hypotension during anaesthesia.

Adrenal Medulla↗
PubMed1996

Prevalence of hepatitis C virus infection among female prostitutes in Fukuoka, Japan.

To assess the risk of sexual transmission of hepatitis C virus (HCV), we surveyed female prostitutes to determine the prevalence of antibody to HCV (anti-HCV) and HCV RNA. Anti-HCV was examined with a second generation anti-HCV test employing a passive hemagglutination assay. HCV RNA was detected by two-stage polymerase chain reaction with primers deduced from the 5'-noncoding region of the HCV genome. All studies were performed in Fukuoka, Japan, from 1989 through 1992 and all subjects were Japanese and had no history of intravenous drug abuse. The prevalence of anti-HCV was significantly higher in the prostitutes (10.1%; 61/604) than in the controls (female blood donors; 0.8%; 52/6632) (P < 0.001). HCV RNA was found in 73.2% of the anti-HCV-positive prostitutes. The prevalence of anti-HCV among prostitutes increased with the number of years spent in prostitution (P < 0.05). Prostitutes with a history of syphilis had a higher prevalence of anti-HCV than those with no history of syphilis, irrespective of the number of years in prostitution. In a longitudinal study of 244 prostitutes, 2 of the 218 initially seronegative subjects showed anti-HCV and HCV RNA over the study period of 3 years. These two persons had no history of percutaneous exposure. Sexual transmission of HCV presents a risk for female prostitutes.

Adolescent↗
PubMed1996

Bacteria closely resembling Helicobacter pylori detected immunohistologically and genetically in resected gallbladder mucosa.

A microorganism with close immunohistological and genetic resemblance to Helicobacter pylori was found in the resected gallbladder mucosa of a 41-year-old woman. The woman was admitted to hospital complaining of fever and right hypochondrial pain. Cholecystectomy was carried out under the diagnosis of gallstones and cholecystitis. A microorganism resembling H. pylori (stained with H&E, Giemsa, and Wartin-Starry) was detected incidentally on pathological examination. The microorganism was also positive for immunohistochemical staining. An amplification reaction was seen on genetic examination by the polymerase chain reaction (PCR) method (urease beta-genes). Our findings suggest that H. pylori may be present in tissues other than gastric mucosa.

Adult↗
PubMed1996

Mechanical circulatory support with the Thoratec assist device in patients with postcardiotomy cardiogenic shock.

BACKGROUND: In spite of modern cardiac surgical techniques, severe cardiogenic shock not responding to pharmacologic therapy and intraaortic balloon pumping develops in about 0.2% to 1.2% of patients undergoing cardiac operations. METHODS: From September 1987 to September 1994, 184 patients were supported with different mechanical circulatory support systems. Nine patients with postcardiotomy cardiogenic shock were supported with the Thoratec ventricular assist device. Four patients suffered early postcardiotomy cardiogenic shock, and 5 patients suffered late postcardiotomy cardiogenic shock. In 6 patients the Thoratec device was applied exclusively, in 2 patients both Bio-Medicus and Thoratec, and in 1 patient both ABIOMED and Thoratec devices were used. Duration of support ranged from 5 to 46 days with a mean duration of 15 days. RESULTS: Four patients (44%) survived and were discharged. Main complications and causes of death were multiple organ failure and sepsis. CONCLUSIONS: The results justify the use of Thoratec assist device in patients with severe preoperative cardiogenic shock.

Adult↗
PubMed1996

Narrow photon beam dosimetry for linear accelerator radiosurgery.

The dosimetric characteristics of linear accelerator radiosurgery for 10-MV X-ray were measured. Measurement of the relative output factor and tissue maximum ratio with a microchamber produced results equivalent to those of measurement with X-ray film. The 80% isodose level width measured with the microchamber was significantly smaller than that measured with the X-ray film. For the measurement of relative output factor and tissue maximum ratio, a microchamber seems to be the more appropriate choice. X-Ray film was found to be suitable for beam profile measurement.

Phantoms, Imaging↗
PubMed1996

Ca(2+)/calmodulin-dependent protein kinase II inhibitor KN-62 inhibits adrenal medullary chromaffin cell functions independent of its action on the kinase.

KN-62, an inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II), inhibited significantly catecholamine secretion and tyrosine hydroxylase activity stimulated by acetylcholine in cultured bovine adrenal medullary cells. KN-62, however, showed an additional inhibitory effect on acetylcholine-induced 45Ca2+ influx, which is essential for functional responses. Carbachol-stimulated 22Na+ influx, veratridine-induced 22Na+ influx, and 56 mM K(+)-evoked 45Ca2+ influx were also attenuated by KN-62. Inhibitions by KN-62 of these ion influxes were correlated closely with those of catecholamine secretion. KN-04, which is a structural analogue of KN-62 but does not inhibit CaM kinase II activity, elicited inhibitory effects on the three kinds of stimulant-evoked ion influxes with an inhibitory potency similar to KN-62. These results suggest that KN-62 inhibits catecholamine secretion and tyrosine hydroxylase activation due to mainly its ion channel blockade on the plasma membrane rather than the inhibition of CaM kinase II activity in the cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1996

Transport of hemodynamically unstable patients by a mobile mechanical circulatory support team.

Advances in medical technology have made it possible to use emergency femoro-femoral bypass (FFB) for transport of hemodynamically unstable patients. In this study, we report on our experience of transport of patients with refractory heart failure by a special mobile mechanical circulatory support team (MMCST) using an intraaortic balloon pump (IABP) or FFB. A total of 22 patients (14 men, 8 women) were supported by the MMCST and transported to our clinic for further diagnostic or therapeutic procedures. The diagnoses in 12 patients was acute myocardial infarction, in 7 patients, dilatative cardiomyopathy (DCM), and in 3 patients, acute fulminant myocarditis. In 15 cases, FFB was implanted (5 in combination with IABP), and in 5 cases, IABP only was implanted. Two patients received maximal dosages of catecholamines. After arrival at our clinic, 11 patients received implants of a more sophisticated support system. From the myocardial infarction group, 3 patients received coronary artery bypass grafting, 1 patient received percutaneous transluminal coronary angioplasty, and 1 patient received heart transplantation as final therapy. In the myocarditis and DCM groups, 7 patients underwent heart transplantation. Finally, 11 patients (50%) survived, and 11 patients died of multiorgan failure or septicemia.

Adult↗
PubMed1996

Management of acute fulminant myocarditis using circulatory support systems.

Although the natural history of acute myocarditis leads to complete recovery in the majority of patients, rapid and irreversible cardiac decompensation resulting in death is known to occur. One possible therapy to improve the poor prognosis of this patient group may be the implantation of circulatory support systems that allow myocardial recovery or bridging to heart transplantation. Therapeutic protocols have been suggested, but clinical experiences in this area are few. In this paper we report on our clinical experiences in cardiogenic shock after acute fulminant myocarditis using different types of circulatory support systems. Three different systems were used: a biomedicus centrifugal pump as a ventricular assist device (VAD) or femoro-femoral bypass (FFB) including oxygenator; Abiomed BVS 5000, and Thoratec ventricular assist device. Hemodynamic criteria for implantation of support systems were cardiac index < 2.0 L/min/m2. SVR = 1000 dyne-s-cm-5, central venous pressure (CVP) or left atrial pressure (LAP) > 20 mm Hg, and urine output < 20 ml/h despite maximal pharmacological therapy. Age total of 5 patients (mean age 29 years, range 15-55 years) in cardiogenic shock after acute fulminant myocarditis were included. Two patients initially were supported for stabilization and transportation from an outside hospital by FFB. Both patients died after a support time of 24 h because of multiorgan failure or neurological disorders after longer periods of resuscitation in the referral hospital. The third patient (55 years) received the Biomedicus pump as CVAD. Myocardial function recovered after a support time of 120 h, and the patient could be weaned. Unfortunately, 2 days after weaning, he developed malignant arrhythmias and died. The 2 remaining patients (15 years and 27 years) with diagnosis of acute fulminant virus myocarditis were supported by biventricular assist device (1 x Thoratec/111 days, 1 x Abiomed/7 days). During the entire time of support, there were no signs of myocardial recovery. The patients were accepted for the heart transplantation (HTX) program. In both cases, HTXs were performed without any complication. The postoperative course was uneventful. The results of mechanical circulatory support in patients with acute fulminant myocarditis are encouraging and justify the resources.

Adult↗
PubMed1996

In-vitro evaluation of biphenylyl acetic acid-beta-cyclodextrin conjugates as colon-targeting prodrugs: drug release behaviour in rat biological media.

Biphenylyl acetic acid was selectively conjugated to one of the primary hydroxyl groups of beta-cyclodextrin through an ester- or amide-linkage, and the physicochemical properties (aqueous solubility and hydrolysis) were investigated. Aqueous solubility of the conjugates was lower than those of either drug or parent beta-cyclodextrin. The amide conjugate was stable in aqueous solution and in rat biological fluids and gastrointestinal contents. The ester conjugate was hydrolysed to beta-cyclodextrin and biphenylyl acetic acid at moderate rates resulting in a V-shaped rate-pH profile in aqueous solution. The ester conjugate released the drug preferentially when incubated with the contents of caecum or colon, whereas no appreciable drug release was observed on incubation with contents of stomach or intestine, nor on incubation with intestinal or liver homogenates, nor on incubation with rat blood. The present results suggest that the ester-type drug conjugate of beta-cyclodextrin may serve as a colon-targeting prodrug.

Animals↗
PubMed1996

Inhibitory effect of adrenomedullin on rat mesangial cell mitogenesis.

We investigated the effects of adrenomedullin on rat mesangial cell proliferation. Adrenomedullin (10(-10)-10(-7) M inhibited both [3H]thymidine incorporation into cultured rat mesangial cells and cell proliferation in a concentration-dependent manner. Adrenomedullin (10(-10)-10(-6) M) stimulated cyclic adenosine monophosphate accumulation in rat mesangial cells in a concentration-dependent manner. These findings suggest that adrenomedullin inhibits proliferation of rat mesangial cells probably through a cyclic adenosine monophosphate-dependent mechanism.

Adrenomedullin↗
PubMed1996

Mechanical circulatory support: lessons from a single centre.

Over recent years, a number of different mechanical circulatory support (MCS) products have been developed to a stage where they are no longer investigational devices. Registry data provide some information, but this is limited by the mix of historical and contemporary data and the voluntary nature of the contributions. As yet, there are no clear guidelines for patient selection, the differential application of generically different devices or for optimal patient management. Ours is a busy centre offering a comprehensive cardiovascular service. This review details our experience since 1987 and 189 patients supported with five different types of device, used in all of the common applications. Our experience has permitted the formulation of some general principles and guidelines. Data published by registries and by individual manufacturers are, as yet, not standardized. We hope that our experience will be of interest to those centres wishing to establish a mechanical assist service.

Academic Medical Centers↗
PubMed1996

[A case of superior vena cava syndrome treated with combination radiation and CRE (CBDCA and VP-16) therapy].

Carboplatin and etoposide were reported to be excellent radiation sensitizers. We encountered a patient with SVC syndrome due to lung cancer who was successfully treated by combination carboplatin, etoposide and hyperfractionation radiotherapy. A 72-year-old man was admitted to our hospital because of remarkable face edema. Computed tomography revealed a huge lung tumor and compressed SVC due to tumor growth. Acute tumor regression was essential for this case. We performed combination chemotherapy and radiation. The regime consisted of CBDCA 300 mg (day 1 1 hr drip infusion) and etoposide 50 mg/day for 21 days by oral administration. Two daily fractionations of 1.4 Gy were delivered 5 days-a-week, with a 4 h interval between fractions (total dose 49.8 Gy). Complete response of huge tumor was attained in this case. The major side effect associated with the therapy was myelosuppression. The patient's quality of life has been remarkably improved with this therapy.

Aged↗
PubMed1996

Predictors of unsuccessful outcome after percutaneous mitral valvulotomy including a new echocardiographic scoring system.

BACKGROUND AND AIMS OF THE STUDY: Percutaneous mitral valvulotomy has been shown to be an accept able alternative to surgery as treatment for selected patients with severe mitral stenosis. Uncertainty still exists regarding predictors of unsuccessful outcome. MATERIALS AND METHODS: 308 patients with severe mitral stenosis underwent Inoue single balloon valvulotomy over a 48-month period and were followed up for a mean of 14.5 +/- 16.8 months (range one to 64 months). Two hundred and sixty-seven (Group I) improved clinically and remained stable throughout the follow up, while subsequent surgery was required in 41 (Group II) after 38.2 +/- 143.5 days (range one to 1,212). Clinical and echocardiographic parameters of the two groups were compared to find significant predictors of an unsuccessful outcome. RESULTS: Significant differences between the groups were observed for NYHA class (2.7 +/- 0.6 vs. 2.9 +/- 0.6, p < 0.05), mitral valve area (1.0 +/- 0.3 vs. 0.9 +/- 0.2 cm2, p < 0.01), left atrial end-systolic dimension by echo (51.3 +/- 8.0 vs. 55.4 +/- 10.2 mm, p < 0.01) and an echocardiographic scoring system including grading for eccentricity of the mitral orifice and distribution of commissural calcification (7.5 +/- 2.0 for Group I and 8.7 +/- 2.0 for Group II, p < 0.001). CONCLUSIONS: Mitral valves that are more likely to have an unsuccessful outcome can be identified by hemodynamic, clinical and echocardiographic criteria, including grading for eccentricity of the mitral orifice and distribution of commissural calcification.

Adult↗
PubMed1996

[Long-term survival after treatment of thoracic aneurysms by thromboexclusion operation].

Since 1982, fourteen patients with aortic aneurysms received thromboexclusion operation. This method was performed in 7 patients with dissecting aortic aneurysms, 6 patients with true thoracic aneurysms, and 1 patient with true thoracoabdominal aneurysm. Among them, 12 patients received the operation of ascending aorta-supraceliac abdominal aorta bypass, one patient received descending aorta-descending aorta bypass, and another one received bilateral axillo-iliac artery bypass. Graft sizes in diameter were from 16 mm to 22 mm. 9 patients received permanent paired-clamps at both the proximal and the distal parts of the thoracic aneurysm, and 5 patients received permanent single-clamp only at the proximal part of the thoracic aneurysm. 5 patients (35.7%) died perioperatively because of low output syndrome, cerebral infarction, hepato-renal insufficiency, and aneurysmal rupture, respectively. 4 late deaths (28.6%) occurred after 4 months, 5 months, 26 months, and 5 years of operation, respectively. Among them, three deaths were due to aneurysmal rupture and one due to heart failure. Although paired-clamps at both the proximal and the distal parts of the thoracic aneurysm were performed in 1 to 3 ruptured-cases, thrombo-occlusion of the thoracic aorta did not occur in any of the cases. Long-term survival was 35.7% in 5 patients after 14 years and 4 months of mean follow-up. Although a single-clamp only at the proximal part of the thoracic aneurysm was performed in 2 of these 5 cases, thrombo-occlusion of the thoracic aorta occurred in all cases. For the four survivors of them, we ran a follow-up survey and found left ventricular hypertrophic pattern in ECG, concentric left ventricular hypertrophy in UCG, and hypertension, but those were absent before operation. We conclude that thromboexclusion method for thoracic aneurysm should be limited only to high-risk patients particularly in bad conditions or to cases with severe adhesion to lung which seem to be inaccessible through direct approach.

Adult↗
PubMed1996

Ultrasound examination of stenotic mitral valves: an in vitro study.

To determine the feasibility of currently used, intravascular ultrasound catheters (12.5 and 20 MHz, 6F and 9F, Boston Scientific Corp., Watertown, MA) for mitral valve disease, ten excised mitral valves from patients with severe mitral stenosis were examined. The specimens were fixed in a glass cylinder perfused with water. The valves were planimetered with the intravascular ultrasound system and investigated regarding pathomorphological changes. The depth field of penetration was between 1.5 and 2 cm (3 to 4 cm diameter) in the 20 MHz catheter and between 2 and 2.5 cm (4 to 5 cm diameter) in the 12.5 MHz catheter. A good correlation of the experimentally recorded valve areas could be ascertained with the Gorlin formula (r = .71, P < .05), the Doppler echocardiography method (r = .69, time method (r = .75, p < .05), and with the two-dimensional echocardiography method (r = .69, P < .05). These results show a sufficient feasibility of the currently used, intravascular ultrasound catheters and enable further steps to be taken with regard to evaluating mitral valve morphology in vivo.

Aged↗