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Biomedical subjects

K Minami

Publications and source records attributed to K Minami.

At least 19 recordsLinked 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

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

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

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

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↗
PubMed1995

Alterations in intracellular calcium handling associated with the inverse force-frequency relation in human dilated cardiomyopathy.

BACKGROUND: The present study was performed to test the hypothesis that the altered force-frequency relation in human failing dilated cardiomyopathy may be attributed to alterations in intracellular calcium handling. METHODS AND RESULTS: The force-frequency relation was investigated in isometrically contracting ventricular muscle strip preparations from 5 nonfailing human hearts and 7 hearts with end-stage failing dilated cardiomyopathy. Intracellular calcium cycling was measured simultaneously by use of the bioluminescent photoprotein aequorin. Stimulation frequency was increased stepwise from 15 to 180 beats per minute (37 degrees C). In nonfailing myocardium, twitch tension and aequorin light emission rose with increasing rates of stimulation. Maximum average twitch tension was reached at 150 min-1 and was increased to 212 +/- 34% (P < .05) of the value at 15 min-1. Aequorin light emission was lowest at 15 min-1 and was maximally increased at 180 min-1 to 218 +/- 39% (P < .01). In the failing myocardium, average isometric tension was maximum at 60 min-1 (106 +/- 7% of the basal value at 15 min-1, P = NS) and then decreased continuously to 62 +/- 9% of the basal value at 180 min-1 (P < .002). In the failing myocardium, aequorin light emission was highest at 15 min-1. At 180 min-1, it was decreased to 71 +/- 7% of the basal value (P < .01). Including both failing and nonfailing myocardium, there was a close correlation between the frequencies at which aequorin light emission and isometric tension were maximum (r = .92; n = 19; P < .001). Action potential duration decreased similarly with increasing stimulation frequencies in nonfailing and end-stage failing myocardium. Sarcoplasmic reticulum 45Ca2+ uptake, measured in homogenates from the same hearts, was significantly reduced in failing myocardium (3.60 +/- 0.51 versus 1.94 +/- 0.18 (nmol/L).min-1.mg protein-1, P < .005). CONCLUSIONS: These data indicate that the altered force-frequency relation of the failing human myocardium results from disturbed excitation-contraction coupling with decreased calcium cycling at higher rates of stimulation.

Action Potentials↗
PubMed1995

Protein kinase C-independent inhibition of the Ca(2+)-activated K+ channel by angiotensin II and endothelin-1.

We previously reported that the Ca(2+)-activated K+ channel (KCa-channel) in cultured smooth muscle cells from porcine coronary artery was inhibited by protein kinase C (C-kinase). In this study, inhibition of the KCa-channel by receptor-mediated vascular contractile agonists, such as angiotensin II (ANG II) and endothelin-1 (ET-1), was investigated by the patch-clamp technique. In cell-attached patches, addition of ANG II (500 nM) or ET-1 (50 nM) to the bath inhibited the KCa-channel activated by the calcium ionophore A23187 (10-20 microM). Phorbol 12-myristate 13-acetate (PMA, 1 microM), a C-kinase activator, also decreased the open probability of the KCa-channel. The PMA-induced decrease in the open probability was reversed by subsequent application of staurosporine (1 nM), a C-kinase inhibitor, but the ANG II- and ET-1-induced decreases were not reversed by subsequent application of staurosporine (> 30 nM). Pretreatment of smooth muscle cells with 30 nM staurosporine, a protein kinase inhibitor, or 1 mM neomycin, an inhibitor of phospholipase C, also did not abolish the inhibition of the KCa-channel by ANG II. Furthermore, ANG II inhibited the KCa-channel in cells in which C-kinase was down-regulated. These results indicate that, in porcine coronary artery smooth muscle cells, ANG II and ET-1 inhibit the KCa-channel by a C-kinase-independent mechanism.

Alkaloids↗
PubMed1995

Ability of non-cyclic oligosaccharides to form molecular complexes and its use for chiral separation by capillary zone electrophoresis.

The binding constants (K) for complexation of the phenyl acetates with linear alpha-1,4-linked dextrins have been determined from the kinetics of the hydrolyses of the esters. The K value tends to increase with increasing the number of the glucopyranose units, suggesting hydrophobic interaction as a binding force. The weak ability of the linear dextrins to form the molecular complexes makes it possible to separate the enantiomers of binaphthyl derivatives such as 1,1'-binaphthyl-2,2'-dicarboxylic acid, 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate and 2,2'-dihydroxy-1,1'-binaphthyl-3,3'-dicarboxylic acid in their anionic forms. Hydrogen bonding as well as hydrophobic interaction is suggested as an essential force for enantioselective complexation between saccharide and anionic binaphthyl.

Carbohydrate Conformation↗
PubMed1995

Sexual transmission of human T-lymphotropic virus type I among female prostitutes and among patients with sexually transmitted diseases in Fukuoka, Kyushu, Japan.

The authors investigated the prevalence of antibody to human T-lymphotropic virus type I (anti-HTLV-I) in 409 female prostitutes, 446 patients with an episode of sexually transmitted diseases, and 17,345 control blood donors. All subjects were Japanese and all studies were done in Fukuoka, Kyushu, Japan, in 1989. The prevalence of anti-HTLV-I was significantly higher in the prostitutes (5.1%, p < 0.001), in the male patients (2.8%, p < 0.05), and in the female patients (5.7%, p < 0.05) than in the controls (males 1.4%, females 2.2%). Prevalence of anti-HTLV-I in the prostitutes increased with the number of years spent in prostitution, but the increase was not statistically significant. Among the subjects with sexually transmitted diseases, female prostitutes with syphilis, male patients with non-gonococcal urethritis, female patients with syphilis, and female patients with gonorrhea had a significantly higher prevalence of anti-HTLV-I than did the controls. A longitudinal study was done on the 168 prostitutes. Two (1.3%) of the 158 initially seronegative subjects seroconverted over the period of 2 years. These data suggest that the risk of male-to-female transmission of HTLV-I through sexual contact is high among high risk groups in Japan, and they support the possibility of female-to-male transmission of HTLV-I.

Adolescent↗
PubMed1995

Inhibition by carbamazepine of various ion channels-mediated catecholamine secretion in cultured bovine adrenal medullary cells.

The effects of carbamazepine (CBZ) on 22Na+ influx, 45Ca2- influx, catecholamine secretion and cyclic GMP production were examined in cultured bovine adrenal medullary cells. 1) CBZ (40-120 mumol/l) inhibited 22Na+ influx evoked by carbachol in a concentration-dependent manner. CBZ inhibited carbachol-evoked 45Ca2- influx and catecholamine secretion at concentrations similar to those which suppressed 22Na+ influx. 2) CBZ (4-120 mumol/l) inhibited veratridine-induced 22Na+ influx, 45Ca2+ influx and catecholamine secretion. 3) CBZ (12 or 40-120 mumol/l) suppressed 56 mmol/l K(+)-evoked 45Ca2+ influx and catecholamine secretion, respectively. 4) Combination of CBZ with nitrendipine or omega-agatoxin-IVA produced further inhibition of 56 mmol/l K(+)-evoked 45Ca2+ influx and catecholamine secretion, compared to the effect of CBZ alone, whereas CBZ plus omega-conotoxin-GVIA did not produce any further inhibition. 5) CBZ (40 mumol/l) attenuated the production of cyclic GMP caused by muscarine. These results suggest that CBZ at therapeutic concentrations (16-48 mumol/l; 4-12 micrograms/ml) inhibits catecholamine secretion by interfering with nicotinic acetylcholine receptor-associated ion channels, voltage-dependent Na+ channels and N-type voltage-dependent Ca2+ channels, and may have an antimuscarinic effect in adrenal medullary cells.

Adrenal Medulla↗
PubMed1995

Mechanical circulatory support: the Bad Oeynhausen experience.

From September 1987 to February 1994, we treated 147 patients ranging between 11 and 82 years old with different mechanical circulatory support systems. The applied devices were the Bio-Medicus centrifugal pump in 61 patients, the Abiomed BVS System 5000 in 49 patients, the Thoratec ventricular assist device in 42 patients, and the Novacor left ventricular assist device in 7 patients. On the basis of indication for mechanical circulatory support, the patients were divided into three groups: group 1 consisted of 72 patients with postcardiotomy cardiogenic shock; group 2, 50 patients in whom mechanical support was used as a bridge to cardiac transplantation; and group 3 (miscellaneous), 25 patients in cardiogenic shock resulting from acute myocardial infarction (n = 14), acute fulminant myocarditis (n = 3), primary graft failure (n = 2), right heart failure after heart transplantation (n = 3), and acute rejection (n = 3). Time of support ranged from 1 hour to 97 days (mean duration, 10.8 days). Seventy-five patients (51%) were discharged from the hospital. The best survival rate was achieved in group 2 with 72%, followed by group 1 with 44% and then group 3 with 28%. The most frequent complications in group 1 were bleeding (44%), multiple-organ failure (24%), neurologic disorders (18%), and acute renal failure (15%). In group 2, the major complications were bleeding (34%) and cerebrovascular disorders (22%) and in group 3, multiple-organ failure and sepsis (60%) and bleeding (32%).

Adolescent↗
PubMed1995

Left aortic arch with right descending aorta and right ligamentum arteriosum associated with d-TGA and large VSD: surgical treatment of a rare form of vascular ring.

A 1-month-old boy with respiratory distress underwent pulmonary artery banding after diagnosis of d-loop transposition of the great arteries and ventricular septal defect. Respiratory distress recurred after surgery. Angiography, esophagography, and magnetic resonance imaging showed left aortic arch, retroesophageal aorta, and right descending aorta. Surgery at 9 months of age showed a right-sided ligamentum arteriosum. Division of the ligamentum relieved the constriction of the esophagus and trachea caused by this rare form of vascular ring.

Aorta, Thoracic↗
PubMed1995

Seven years of experience with the centrifugal pump in patients with cardiogenic shock.

From September 1987 to September 1994 61 patients between 29 and 78 years of age received mechanical circulatory support by means of the Biomedicus centrifugal pump. The patients were divided into three groups by indication: Group I included 15 patients with early postcardiotomy cardiogenic shock and 24 patients with late postcardiotomy cardiogenic shock. Group II 11 patients with therapy-resistant cardiogenic shock following acute myocardial infarction, and Group III 11 patients with cardiogenic shock of other etiologies. Duration of support was 1 to 347 hours. Survival rates were 46.7% and 33.3% in patients with early and late postcardiotomy cardiogenic shock, respectively (Group I), 27.2% in Group II, and 18.1% in Group III. Most frequent complications were bleeding (40%, 58%) and acute renal failure (26.7%, 29.2%) in Group I and multiple organ failure in Groups II and III (64% and 45.5%). Major causes of death were bleeding and multiple organ failure in Group I (37.5%) and multiple organ failure in Groups II and III (87.5% and 50%). Groups II and III (87.5% and 50%).

Adult↗