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Biomedical subjects

K Minami

Publications and source records attributed to K Minami.

At least 163 records · Page 9Linked to original sources
PubMed1998

Effect of exercise training and food restriction on endothelium-dependent relaxation in the Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous NIDDM.

We investigated whether endothelial function may be impaired in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of spontaneous NIDDM. The effect of exercise training and food restriction on endothelial function was also studied. OLETF rats were divided into three groups at age 16 weeks: sedentary, exercise trained, and food restricted (70% of the food intake of sedentary rats). Otsuka Long-Evans Tokushima rats were used as the age-matched nondiabetic controls. Endothelium-dependent relaxation of the thoracic aorta induced by histamine was significantly attenuated in the sedentary or food-restricted rats, and exercise training improved endothelial function. Relaxation induced by sodium nitroprusside, a donor of nitric oxide, did not differ significantly among groups. Both exercise training and food restriction significantly suppressed plasma levels of glucose and insulin and serum levels of triacylglycerol and cholesterol and reduced the accumulation of abdominal fat. Insulin sensitivity, as measured by the hyperinsulinemic-euglycemic clamp technique, was significantly decreased in sedentary rats but was enhanced in exercise-trained and food-restricted rats. The urinary excretion of nitrite was significantly decreased in sedentary and food-restricted rats compared with nondiabetic rats and was significantly increased in exercise-trained rats. These results indicate that exercise training, but not food restriction, prevents endothelial dysfunction in NIDDM rats, presumably due to the exercise-induced increase in the production of nitric oxide.

Abdomen↗
PubMed1998

[Selection criteria for aortic valve prostheses: mechanical, stented, or stentless valve or homograft?].

A bioprosthesis is recommended for aortic valve replacement in patients 70 years (recently, 72 or 73 years) of age or older. The bovine pericardial valve is better suited in patients with a small aortic annulus less than 23 mm in diameter, and the porcine stented-bioprosthesis should be used in patients with an annulus larger than 25 mm. A mechanical valve is recommended in patients younger than 70 years of age with chronic atrial fibrillation or a history of thromboembolism. Moreover, a mechanical valve is selected in patients in whom it is necessary to enlarge the aortic root or annulus. When mitral valve replacement or coronary artery bypass grafting in performed concomitantly, the valve prosthesis is selected according to the age of the patient. A homograft is indicated in patients with active valve endocarditis having an abscess at the aortic annulus or root. When a patient with poor ventricular performance resulting from valvular disease is expected to undergo implantation of a ventricular assist device in the near future, a bioprosthesis is preferable.

Aged↗
PubMed1998

Incidence and risk factors of perioperative cerebral complications. Heart transplantation compared to coronary artery bypass grafting and valve surgery.

OBJECTIVE: The aim of this study was to define the neurologic risk of heart transplantation compared to coronary artery bypass grafting (CABG) and valve surgery. DESIGN: A retrospective study. SETTING: A university hospital. PATIENTS: 8001 patients undergoing heart transplantation, CABG and valve surgery. MEASURES: The incidences of perioperative central nervous system (CNS) complications were compared between different procedures. Risk factors were analysed using univariate and multivariate methods. RESULTS: The overall incidence of CNS complications was 19.8% (78/393) in heart transplantation, 3.1% (176/5734) in elective CABG, 9.5% (161/1689) in elective valve surgery, 10.3% (15/146) in emergency CABG and 51.3% (20/39) in emergency valve surgery. Most powerful predictors of CNS complications were preoperative intra-aortic counterpulsation (IABP) in the heart transplantation group, age >65 years in the CABG group and preoperative use of catecholamine in the valve group. CONCLUSIONS: CNS complications occur much more frequently after heart transplantation than elective CABG and valve surgery. The high incidence of CNS complications after emergency operations as well as preoperative catecholamine and IABP as powerful contributing factors suggest that preoperative cerebral hypoperfusion due to a compromised hemodynamic state facilitates postoperative CNS complications and this may partly explain the high incidence of CNS complications after heart transplantation.

Adolescent↗
PubMed1998

[Usefulness of percutaneous low output microwave tissue coagulation therapy for solitary liver cancer].

The possible use of percutaneous transhepatic low output microwave tissue coagulation therapy (PMCT) using ultra-sonography under local anesthesia for solitary liver cancer was studied. The subjects were 13 patients having primary or metastatic liver cancer with solitary liver tumor less than 3 cm in diameter, including 7 hepatocellular carcinomas and 6 metastatic liver cancers. PMCT was performed continuously 3 times at an output of 30 watts for 30 seconds at a time. Tumors less than 3 cm in diameter were completely coagulated by irradiation from 2 to 6 times, judging by enhanced CT. No tumor recurrence was recognized in the coagulation area. However, in two cases of metastasis from pancreatic carcinoma, multiple metastases were found at another site in the liver by 2 months after PMCT. Thus, the results suggest that PMCT is a useful therapy for small liver tumor as a local control.

Aged↗
PubMed1998

Mechanical circulatory support after orthotopic heart transplantation.

Frequently the only therapy for primary graft- and right heart failure, as well as low output syndrome from acute of chronic rejection, is implantation of a mechanical circulatory support system, until recompensation or retransplantation. At our institution, mechanical assist devices were implanted in 25 heart recipients for a cute rejection (n=9), primary graft failure (n=7), acute right heart failure (n=7), and chronic rejection with low output syndrome (n=2). Patients (pts) with primary graft failure (n=3) received an intraaortic balloon pump (IABP), one pt an IABP plus Abiomed-System for left ventricular support, one pt the Thoratec-System for biventricular support. Patients with right heart failure (RHF) received the Biomedicus centrifugal pump for right ventricular support. Nine pts suffered from acute rejection. Six pts received an IABP, one the Biomedicus as femoro-femoral bypass, one the Abiomed-System for biventricular support, two the Thoratec-System for biventricular support and two within this group switched from the Biomedicus pump to the Thoratec-System for biventricular support. Patients with chronic graft failure (n=2) received the Novacor-System (LVAD) for left ventricular support, one received a Tojobo-System and an oxygenator for biventricular support post coronary artery bypass surgery. Support time ranged from 0.5-h to 73 days. Five pts were weaned. Two (8%) of 25 pts were retransplanted, 18 (72%) died in spite of mechanical support from multiple organ failure. The use of a mechanical assist device after heart transplantation is encouraging only in the case of early right heart failure, as well as primary and chronic graft failure. In view of the poor results, the use of mechanical assist devices should not be recommended in the case of heart failure caused by acute rejection.

Adolescent↗
PubMed1998

Development and initial in vivo testing of a new hydraulic drive system (Paedipump) for circulatory support in infants.

The main limitation in the use of circulatory support in children is the lack of an adequate system with regard to size and pumping capacity. Recently, two pneumatically driven ventricular support systems with low volume chambers for use in a pediatric population became available. We have developed a hydraulic drive system with an advantageous exact control of the stroke volume. The system enables two different modes of operation: the full-empty and the filled-empty modes. In both cases the ventricle is empty at the end of systole. This new system was tested in experimental animals (6 pigs, body weight 9.5-14.0 kg) with normal and reduced left ventricular function (MAP<45 mmHg). A 25 ml ventricle (HIA-Medos) was implanted. The full-empty and the filled-empty mode used led to a significant load reduction, both in animals with normal and impaired cardiac function. Plasma lactate levels, pH-values and total body O2-consumption were in the normal range during circulatory support indicating adequate organ perfusion. Results showed that sufficient ventricular support was achieved during all pumping modes due to the possibility of controlling and modifying the stroke volume of the hydraulically driven support system employed according to necessity. This is a promising feature for its future application in infants with congenital or acquired heart diseases.

Animals↗
PubMed1998

Vascular hamartoma of the left ventricle.

Primary tumors of the heart are very rare. We report a case of a 28-year old female patient in whom a tumor of the left ventricle was first diagnosed by transthoracic echocardiography. Angiography, nuclear magnetic resonance imaging and fasting positron emission tomography with 18-fluorodesoxyglucose suggested the diagnosis of a well vascularized tumor. The tumor was subtotally excised during heart surgery under total cardiopulmonary bypass and histological examination identified a predominantly vascular hamartoma.

Adult↗
PubMed1997

Inhibitory effects of anesthetics and ethanol on muscarinic receptors expressed in Xenopus oocytes.

Anesthetics (and ethanol) are known to produce amnesia as well as immobilization. Recent identification of a nonimmobilizing (nonanesthetic) agent (F6 or 1,2-dichlorohexafluorocyclobutane) that impairs learning and memory suggests that distinct mechanisms may be responsible for these two actions of anesthetic agents. Muscarinic receptors are believed to play a role in memory and learning, and we asked if a specific subtype of these receptors is affected by anesthetics as well as the new nonanesthetic. We investigated the effects of halothane, a novel halogenated anesthetic compound F3 (1-chloro-1,2,2-trifluorocyclobutane) and ethanol on acetylcholine-induced current mediated by a muscarinic m1 receptor expressed in Xenopus oocytes. We also studied the effects of halogenated nonanesthetic compounds, F6 and F8 (2,3-chlorooctafluorobutane) on muscarinic m1 receptors. Halothane, F3, F6 and ethanol inhibited muscarinic m1 receptor-induced Ca2+-dependent Cl- currents at pharmacologically relevant concentrations. F8 had no effect on acetylcholine-induced muscarinic m1 receptor function. The protein kinase C inhibitor, bisindolylmaleimide I (GF109203X), enhanced the acetylcholine-induced current and the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA), inhibited this current. GF109203X abolished the inhibitory effects of halothane, F3 and ethanol on muscarinic m1 receptors but had no effect on actions of F6. These results demonstrate that anesthetics and a nonanesthetic inhibit the function of muscarinic m1 receptors and suggest activation of protein kinase C as the mechanism of action of anesthetics and ethanol on these receptors.

Anesthetics, Inhalation↗
PubMed1997

Combined intraarterial chemotherapy and radiotherapy in the treatment of bladder carcinoma.

BACKGROUND: The combination of radiotherapy and cisplatin-based chemotherapy has proved to be an effective treatment for bladder carcinoma in many clinical studies. Intra-arterial approaches to chemotherapy have been developed to reduce systemic toxicities and improve response rates. This study was designed to determine the effectiveness of intra-arterial chemotherapy with cisplatin and doxorubicin combined with radiotherapy in the treatment of patients with invasive bladder carcinoma. The objectives were to evaluate the response rate, bladder preservation rate, toxicity, and survival rate. METHODS: Thirty-five patients with muscle-invasive bladder carcinoma at clinical stage T2-T4N0M0 were each treated with 2courses of intra-arterial cisplatin and doxorubicin at 3-week intervals, whereas radiotherapy was administered for 4 weeks (2 gray [Gy] given a total of 20 times, at 5 fractions per week). Patients with complete responses were given an additional course of chemotherapy (intra-arterial cisplatin and doxorubicin) and irradiation (20 Gy), and patients with residual tumor after the initial chemoradiotherapy underwent cystectomy. RESULTS: A clinical complete response was observed in 26 patients (74%; 95% confidence interval, 59-89%), and an incomplete response was observed in 9 (26%; 95% confidence interval, 11-41%). The bladder was preserved in all patients with a complete response, and it was tumor free in 19 of them (54% of all patients). The actuarial survival rate was 76.6% at 5 years. After a median follow-up interval of 45 months, 28 patients (80%) were alive and 7 (20%) had died due to disease progression. The regimen was well tolerated, with no severe systemic or local toxicities. CONCLUSIONS: The high rates of response, survival, and bladder preservation observed indicate that this combined intra-arterial chemotherapy and radiotherapy regimen would be useful in the management of invasive bladder carcinoma. This was a small Phase II trial; the results are preliminary, and the utility of this treatment modality in patient management remains to be proven.

Adult↗
PubMed1997

6A-O-[(4-biphenylyl)acetyl]-alpha-, -beta-, and -gamma-cyclodextrins and 6A-deoxy-6A-[[(4-biphenylyl)acetyl]amino]-alpha-, -beta-, and -gamma-cyclodextrins: potential prodrugs for colon-specific delivery.

Cyclodextrins (CyDs) are known to be fermented to small saccharides by colonic microflora, whereas they are only slightly hydrolyzable and thus are not easily absorbed in the stomach and small intestine. This property of CyDs is particularly useful for colon-specific delivery of drugs. In this study, an antiinflammatory 4-biphenylylacetic acid (BPAA) was selectively conjugated onto one of the primary hydroxyl groups of alpha-, beta-, and gamma-CyDs through an ester or amide linkage, 6A-O-[(4-biphenylyl)acetyl[-alpha-, -beta-, and -gamma-CyDs (1-3) and 6A-deoxy-6A-[[(4-biphenylyl)acetyl]amino]-alpha-, -beta-, and -gamma-CyDs (4-6). In rat cecal and colonic contents (10%, w/v), 1 and 3 released more than 95% of BPAA within 1-2 h, and 2 released about 50% of the drug within 12 h. The amide prodrugs, 4-6, did not release BPAA in the cecal contents, but gave BPAA/maltose or BPAA/triose conjugates linked through an amide bond. On the other hand, these prodrugs were found to be stable in the contents of rat stomachs and small intestines, in intestinal or liver homogenates, and in rat blood. The serum levels of BPAA increased about 3 h after oral administration of 1 and 3 to rats, accompanying a marked increase in the serum levels, whereas 2 and 4-6 resulted in little increase of the serum levels. These facts suggest that BPAA is released after the ring opening of CyDs followed by the ester hydrolysis, and the BPAA activation takes place site-specifically in the cecum and colon. Therefore, the present CyD prodrug approach provides a versatile means of constructing a novel colon-specific drug delivery system.

Animals↗
PubMed1997

Selective conversion of big endothelins to tracheal smooth muscle-constricting 31-amino acid-length endothelins by chymase from human mast cells.

Chymase from human mast cells selectively cleaved big endothelins (ETs) at the Tyr31-Gly32 bond and produced novel trachea-constricting 31-amino acid-length endothelins, ETs(1-31), without any further degradation products. Chymases from other species, such as the enzymes from rat connective tissue and mucosal mast cells, and the other chymotrypsin-like proteases examined degraded big ETs. ETs(1-31) exhibited various contractile potencies as to the rat trachea in comparison with 21-amino acid-length endothelins, ETs(1-21), and big ETs: ET-1(1-21) > ET-1(1-31) > big ET-1; ET-2(1-31) > ET-2(1-21) > or = big ET-2; ET-3(1-21) > or = ET-3(1-31) > or = big ET-3. Among the ETs(1-31), ET-2(1-31) was the most potent constrictor, its potency being similar to that of ET-1(1-21) and stronger than that of ET-2(1-21). The contractile activity of ETs(1-31) may not be the consequence of conversion to the corresponding ETs(1-21) by phosphoramidon-sensitive ET-converting enzymes or other chymotrypsin-type proteases and metalloendopeptidases, because the contractile activity was not inhibited significantly on treatment with inhibitors of these proteases before the addition of ET-1(1-31). Inhibitors of chymotrypsin-type serine proteases, on the contrary, significantly enhanced the contractile activity exhibited by ET-1(1-31) and big ET-1, but not that by ET-1(1-21). These results suggest that protease(s) on the surface of the rat trachea tends to degrade ETs(1-31) and big ETs, and thereby reduces their contractile activity. Taken together, the results suggest that trachea-constricting ETs(1-31) generated by human chymase may play a role in the hyper-responsive airway in allergic inflammation.

Animals↗
PubMed1997

Extended donor criteria: use of cardiac allografts after carbon monoxide poisoning.

BACKGROUND: An increasing demand for cardiac allografts for the treatment of end-stage cardiac failure has led to a shift in the traditional views about donor criteria. The use of allografts exposed to high concentrations of carbon monoxide is still under discussion. The current literature on this topic is contradictory. We describe our experience with orthotopic cardiac transplantation, using cardiac allografts after carbon monoxide poisoning. METHODS: Between March 13, 1989 and August 1, 1996, 770 orthotopic heart transplantations were performed in our center. Within this period, we accepted five cardiac allografts from brain-dead, carbon monoxide-poisoned donors. Donor history showed carbon monoxide intoxication in all cases. At the time of organ explantation, donor hemodynamic parameters were feeble in all patients. RESULTS: The postoperative course was uneventful in three of the five recipients. The overall 3-year survival rate in this small group is 40%. Induction therapy or rescue therapy with mono/polyclonal antibodies was not necessary. Myocardial right-ventricular biopsies did not show any specific signs of carbon monoxide poisoning. CONCLUSIONS: In our opinion, cardiac allografts from donors exposed to carbon monoxide can be transplanted successfully in infants and adults, if there are no signs of severe hemodynamic dysfunction in the presence of a normal central venous pressure and low-dose support with catecholamines and there are no electrocardiographic changes in combination with elevated transaminase. With extended donor criteria, the hearts of carbon monoxide-poisoned victims could increase the number of suitable organs and lower the death rate of patients on the United Network for Organ Sharing and Eurotransplant International Foundation waiting lists.

Adult↗
PubMed1997

Results of heart transplantation in patients with preexisting malignancies.

Twenty patients with end-stage heart failure and preexisting malignancies underwent heart transplantation at a single center, with a neoplasm-free interval before the procedure of 0 to 240 months. Twelve patients were long-term survivors (2 to 72 months); there were 2 early and 6 late deaths, thus justifying heart transplantation in patients with preexisting malignancies in individual cases.

Contraindications↗
PubMed1997

Long-term follow-up (8 to 17 years) after thromboexclusion operation for thoracic aortic aneurysms.

BACKGROUND: It has been reported that the thromboexclusion operation is a good method for managing certain difficult thoracic aortic aneurysms. METHODS: Forty-four patients underwent graft replacement (group 1) and 14, the thromboexclusion operation (group 2). We reviewed the long-term results of the thromboexclusion operation and compared them with those of graft replacement in our institutions. RESULTS: The hospital mortality rate in groups 1 and 2 was 29.5% (13 patients) and 35.7% (4 patients), respectively. In group 1, the one late death (2.3%) was due to heart failure and in group 2, three of the four late deaths (28.6%) were due to rupture of the excluded thoracic aorta, and one late death was due to heart failure. Long-term follow-up was possible for 23 patients in group 1 and 5 patients in group 2. Survival 3 years after operation was significantly better in group 1 than in group 2 (p < 0.05). Long-term follow-up with blood pressure measurements, chest roentgenograms, electrocardiograms, and echocardiograms showed no significant differences between the preoperative and postoperative findings. However, in group 2, left ventricular hypertrophy and hypertension, which had not been present preoperatively, were found in all of the patients. Also, 1 patient has had persistent hemoptysis. CONCLUSIONS: The thromboexclusion operation has introduced unanticipated problems that were recognized at long-term follow-up.

Adult↗