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Biomedical subjects

K Minami

Publications and source records attributed to K Minami.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1996

Inhibition by protamine of catecholamine secretion and ion influxes in bovine adrenal medullary cells in culture.

To elucidate the mechanism of protamine-induced hypotension, we examined the effects of protamine on catecholamine secretion in bovine adrenal medullary cells and on the serum norepinephrine in the rat. 1) in bovine adrenal medullary cells in culture, protamine at concentrations of 10 to 100 micrograms/ml inhibited catecholamine secretion stimulated by carbachol. The inhibitory effect of protamine was diminished by heparin at concentrations of 3.5 to 14 U/ml. Protamine suppressed carbachol-stimulated 22Na+ influx and 45Ca++2 influx at a concentration similar to that which inhibited catecholamine secretion. Protamine (10-100 micrograms/ml) also inhibited veratridine-induced 22Na+ influx and 45Ca++ influx and 56 mM K(+)-evoked 45Ca++ influx. The inhibition of these ion influxes by protamine was closely correlated with that of catecholamine secretion. 2) In rats, i.v. administration of protamine (10 mg/kg) attenuated the arterial blood pressure and the serum norepinephrine. There was a high correlation (r = 0.96) between the serum norepinephrine and the arterial blood pressure in protaminetreated rats. Furthermore, pretreatment with heparin (1000 U/kg) abolished the protamine-induced decreases in arterial blood pressure and serum norepinephrine. Because protamine seems to inhibit catecholamine secretion by interfering with Na+ influx and Ca++ influx to adrenal medullary cells, the protamine-induced hypotension may be, at least in part, due to inhibition of norepinephrine release and ion channel activities of sympathetic nerve terminals in rats.

Adrenal Medulla↗
PubMed1996

Pathomorphological characteristics of resected mitral valves after unsuccessful valvuloplasty.

OBJECTIVE: Percutaneous mitral valvuloplasty has been shown to be an acceptable alternative to surgery as treatment for selected patients with severe mitral stenosis. We examined hemodynamic, echocardiographic, and pathomorphologic findings in a series of 308 patients undergoing balloon valvuloplasty, 41 of whom underwent subsequent surgery, in search of possible predictors of an unsuccessful outcome. INTERVENTION AND RESULTS: Patients with severe mitral stenosis underwent Inoue single ballon valvuloplasty over a 48-month period and had follow-up for a mean of 14.5+/-16.8 months (range 1 to 64 months). Of the 308 patients, 267 (Group I) were clinically improved and stable throughout follow-up, while subsequent surgery was required in 41 (Group II) after 38.2+/-143.5 days (range 1 to 1212). 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) and left atrial endsystolic dimension by echo (51.3+/-8.0 vs 55.4+/-10.2 mm, p<0.01). Two of the 41 Group II patients underwent surgery for left to right shunting, 1 for tamponade and 2 were lost to follow-up. The excised mitral valves of the remaining 36 patients all showed calcification and/or fibrosis: 9 homogenous, 5 non-homogenous; 19 were classified as having a funnel-shaped deformity, and 3 did not fit into a discrete category. Among the funnel-shaped valves, 13 had a tear versus 6 where dilation was primarily accomplished by stretching. Only one of 9 valves with homogenous calcification was torn, whereas a tear was noted in 3 of the 5 with non-homogenous calcification. CONCLUSION: Funnel-shaped valves and those with non-homogenous distribution of calcification and/or fibrosis appear to be least suitable for balloon valvuloplasty.

Adult↗
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↗
PubMed1995

[Stereotactic radiation therapy with linear accelerator: accuracy of alignment and portal film verification].

Stereotactic radiation therapy with a linear accelerator requires precise alignment of therapeutic radiation distribution to the target volume. To verify the accuracy of alignment, differences between the stereotactic coordinates of the center of the therapeutic radiation distribution determined from portal films and those of the target points determined from CT/MRI or CT/angiographic localization were calculated for 58 points. The average values and one standard deviation were--0.02 +/- 0.50mm, 0.37 +/- 0.39mm and 0.01 +/- 0.25mm in the x, y, and z directions, respectively. The average value of the total deviation was 0.73 +/- 0.07mm. Potential sources of misalignment were misaligned laser pointers, wide laser beam width, improperly zeroed target positioner scale, and motion of the patient couch. The accuracy of alignment should be verified prior to irradiation. Portal film verification is indispensable for strereotactic radiation therapy with a linear accelerator.

Cranial Irradiation↗