Biomedical subjects

H Watanabe

Publications and source records attributed to H Watanabe.

At least 271 records · Page 15Linked to original sources

PubMed2001

Frequency-dependent electrophysiological effects of flecainide, nifekalant and d,l-sotalol on the human atrium.

To compare the effects of class Ic and III antiarrhythmic agents on the termination and prevention of atrial fibrillation, the present study investigated the use-dependent electrophysiological effects of flecainide, nifekalant and d,l-sotalol on the human atrium. Flecainide significantly prolonged effective refractory period (ERP), intra-atrial conduction time (IACT) and monophasic action potential duration (MAPD), and its effects on ERP and IACT were use-dependent. Nifekalalant significantly prolonged ERP and MAPD, and these effects were reverse use-dependent; however, there was no significant change in IACT. d,l-Sotalol significantly prolonged MAPD and the effect was reverse use-dependent. It significantly prolonged ERP, but the effect was not reverse use-dependent. d,l-Sotalol increased IACT in a use-dependent manner. Thus, for atrial fibrillation, class Ic antiarrhythmic agents might be more effective in termination and class III antiarrhythmic agents might be more effective in prevention.

Action Potentials↗

PubMed2001

Prediction of functional recovery in patients with myocardial infarction after revascularization--comparison of low-dose dobutamine stress echocardiography with fluorine-18 fluorodeoxyglucose positron emission tomography.

The present study investigated the agreement between low-dose dobutamine stress echocardiography (LDDSE) and fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and compared each technique's ability to detect myocardial viability and predict functional recovery in 30 patients. All patients underwent revascularization, followed by echocardiography 5+/-3 months. Of the 390 segments analyzed by echocardiography before revascularization, 110 (28%) had abnormal wall motion. LDDSE showed viability in 66 sites of the 110 dyssynergic segments and 58 of these viable segments recovered their wall motion. With FDG-PET, 78 of the 110 dyssynergic segments were diagnosed as viable and 62 of these showed improvement of the wall motion. The sensitivities for LDDSE and FDG-PET to assess functional recovery were 84% and 90%, respectively; specificities were 80% and 64%, respectively. Positive predictive values for LDDSE and FDG-PET were 88% and 79%; negative predictive values were 75% and 78%, respectively. Both methods had good sensitivity for detecting improvement in regional function after revascularization, but LDDSE had a higher specificity for detecting viability and a better positive predictive value for left ventricular functional recovery.

Aged↗

PubMed2001

Inappropriate discharges from an intravenous implantable cardioverter defibrillator due to T-wave oversensing.

This report describes the clinical management of 2 patients with ventricular fibrillation (VF) who received inappropriate shocks from an implantable cardioverter defibrillator (ICD) due to T-wave oversensing. Cardiac sarcoidosis was confirmed as the underlying heart disease in 1 patient and idiopathic dilated cardiomyopathy in the other. Within 2 months after ICD implantation, both patients received several inappropriate shocks during sinus rhythm. Stored electrograms showed decreased R-wave amplitudes and increased T-wave amplitudes. The ICD sensed both R- and T-waves as ventricular activation, which met the rate criteria for VF treatment. Reprogramming the sensing threshold in association with administration of a drug to slow the heart rate decreased the incidence of the inappropriate shocks in both patients, but these palliative measures did not completely suppress the inappropriate shocks. To avoid T-wave oversensing, the repositioning or adding of a sensing lead is required. The potential risk of T-wave oversensing in ICD patients who have small R-wave amplitudes should be recognized.

Adult↗

PubMed2001

Inappropriate discharges by fourth generation implantable cardioverter defibrillators in patients with ventricular arrhythmias.

The study prospectively investigated the incidence, cause and efficient management of inappropriate discharge by the fourth generation implantable cardioverter-defibrillator (ICD) system in 45 patients (mean age, 57+/-16 years). During the follow-up period of 27+/-17 months, 18 patients (40%) experienced one or more inappropriate therapies: sinus and supraventricular tachycardia (15 patients) and T wave oversensing (3 patients). In the 15 patients, re-programming of the tachycardia detection interval and/or additional treatment with beta-blocking agents were effective. In the 3 patients with T wave oversensing, the arrythmia was associated with an increase in T wave amplitude, change in T wave morphology and decreased R wave amplitude, and re-programming of the sensitivity of the local electrogram or changing the number of intervals to detect ventricular tachycardia decreased the number of inappropriate discharges in all 3 patients. In conclusion, inappropriate therapies are common problems in patients treated with the fourth generation ICD system, but most of them can be resolved using the dual-chamber ICD system. However, in patients with T-wave oversensing, it is difficult to avoid inappropriate discharge completely, even if the dual-chamber ICD system is implanted.

Adolescent↗

PubMed2001

Directional distribution of radiation around an accident at a uranium fuel factory in Tokai-mura, 1999.

A beta-ray survey was carried out on concrete walls of the boundary and buildings after a criticality accident at a factory of JCO Co. Ltd. at Tokai-mura. A remarkable distribution of beta counts was observed on the walls depending on the complex internal and external structures of buildings surrounding a precipitation vessel containing uranium 23 days after the accident. The directional distribution function, based on the beta counts on the walls, was consistent with data concerning the neutron dose rate measured in several directions during the accident, suggesting an anisotropic neutron distribution to the residential area.

Humans↗

PubMed2001

Trehalose-producing operon treYZ from Arthrobacter ramosus S34.

Arthrobacter ramosus S34, which produces trehalose from maltooligosaccharide, was isolated. A trehalose-producing operon, treYZ, was cloned from the genome. Expression experiments with treY and treZ confirmed that they coded malto-oligosyltrehalose synthase and malto-oligosyltrehalose trehalohydrolase, respectively. The amino acid sequence of TreY from A. ramosus S34 and that from Arthrobacter sp. Q36 did not show high identity, nor did those of TreZ.

Amino Acid Sequence↗

PubMed2001

Supplemental silk protein, sericin, suppresses colon tumorigenesis in 1,2-dimethylhydrazine-treated mice by reducing oxidative stress and cell proliferation.

This study was done to discover the underlying mechanism of the inhibitory effect of sericin against colon tumorigenesis. Mice were fed a diet with 30 g/kg sericin for 115 d, and given a weekly injection of 1,2-dimethylhydrazine (10 mg/kg body weight) for the initial 10 wk. Dietary supplemental sericin caused a 62% reduction in the incidence of colonic adenoma (P<0.05), but did not affect the incidence of colonic adenocarcinoma. Sericin intake significantly reduced the number of colon adenomas. Consumption of sericin significantly reduced the BrdU labeling index of colonic proliferating cells and the expression of colonic c-myc and c-fos. The levels of colonic 8-hydroxydeoxyguanosine, 4-hydroxynonenal, and inducible nitric oxide synthase protein were significantly suppressed by sericin. The results suggest that dietary sericin suppresses the development of colon tumors by reducing oxidative stress, cell proliferation, and nitric oxide production.

1,2-Dimethylhydrazine↗

PubMed2001

Induction of nitric oxide synthase and subsequent production of nitric oxide not involved in interferon-gamma-induced hyperpermeability of Caco-2 intestinal epithelial monolayers.

Caco-2 cell monolayers exposed to 1000 U/ml interferon-gamma (IFN-gamma) for 6 days elicited inducible nitric oxide synthase (iNOS) expression and increased translayer permeability. This iNOS increase was blocked by pyrrolidinedithiocarbamate (an inhibitor of iNOS induction) but it did not suppress the hyperpermeability response. Furthermore, 2,2'-(hydroxynitrosohydrazino) bis-ethanamine (a NO donor) did not increase monolayer permeability. Therefore, IFN-gamma-induced hyperpermeability is not due to its induction of iNOS activity and resulting increases in NO levels.

Caco-2 Cells↗

PubMed2001

Novel method for assessing myocardial perfusion: visualization and measurement of intramyocardial coronary blood flow in the entire left ventricular wall using contrast enhanced, high frequency Doppler echocardiography.

Using a high frequency ultrasonic transducer, intramyocardial coronary blood flow (IM-CBF) can be visualized and evaluated during hemodynamic changes in the anterior wall and septum of the left ventricle (LV). We tested the hypothesis that detection and quantitative measurement of IM-CBF of entire LV segments are feasible using a high frequency ultrasonic transducer in conjunction with intravenous contrast injection in vivo. A 3 - 8 MHz transducer was used to image and measure IM-CBF in 10 anesthetized dogs. We obtained a color Doppler image of IM-CBF in the LV short-axis view after intravenous Levovist injection (25 mg/ml). The IM-CBF velocity was recorded using spectral Doppler in the antero-septal and infero-posterior wall of closed chest dogs and in the entire LV after opening the chest. A significant increase in IM-CBF velocity was observed in all LV regions after adenosine 5'- triphosphate (ATP) administration. After Levovist(TM) injection, the visualization of IM-CBF was improved and the spectral Doppler pattern of coronary flow velocity was clarified compared to baseline. IM-CBF was assessed in the antero-septal region of the LV before and after left anterior descending coronary artery occlusion. A high frequency ultrasonic transducer in conjunction with intravenous contrast injection improved IM-CBF visualization, enabling quantitative evaluation of the intramyocardial coronary circulation in the entire LV after coronary occlusion and hyperemia. This study may represent a step towards noninvasive assessment of myocardial perfusion before and after coronary reperfusion.

Animals↗

PubMed2001

Prominent systolic coronary flow in a coronary artery fistula with a giant aneurysma.

A 68-year-old Japanese woman was admitted to hospital because of chest oppression during exertion. Coronary angiography showed a coronary artery fistula with a giant aneurysm, which originated from both the left anterior descending (LAD) and right coronary arteries. We investigated coronary blood flow velocity using the Doppler guide wire technique. The coronary flow pattern showed a very prominent systolic component, whereas the diastolic flow components were nearly normal before the operation at the LAD site proximal to the coronary artery fistula. This pattern returned to normal after the operation. This report describes the relationship between the coronary steal phenomenon and coronary flow dynamics investigated directly using the Doppler guidewire technique.

Aged↗

PubMed2001

Acute cholestatic hepatitis caused by a probable allergic reaction to paracetamol in an adolescent.

We reported on an adolescent who suffered from cholestatic hepatitis after taking a low dose of paracetamol. It was suspected that the condition was brought about by an allergic reaction to paracetamol. Paracetamol is one of the representative intrinsic hepatotoxic drugs. There have been only a few reports on liver damage due to an allergic reaction to paracetamol. There is a need to call attention to this particular reaction.

Acetaminophen↗

PubMed2001

Concentrations of trace elements in sweat during sauna bathing.

Trace elements in sweat during sauna bathing were assessed. Sweat collected by the whole body method was compared with that collected by the arm bag method. The sweat samples were collected from ten healthy male adults aged 22-26 years, by heat exposure in dry sauna bathing (60 degrees C, 30 minutes). Concentrations of major (Na, Cl, K, Ca, P and Mg) and trace (Zn, Cu, Fe, Ni, Cr and Mn) elements in sweat tended to be lower in the arm bag method than in the whole body method. It was found that Ca, Mg, Fe and Mn concentrations in the arm bag method were significantly lower than those in the whole body method. The amount of trace elements in sweat measured by the arm bag method was less than that by the whole body method; significant differences were observed in Fe and Mn amounts. These observations suggest that excretion of trace elements by sweating induces trace element decrease. Therefore, athletes and workers who work in a hot environment and sweat much habitually should ingest adequate amounts of trace elements.

Adult↗

PubMed2001

Myxedema accompanied by huge portal-systemic shunt without portal hypertension.

A 43-year-old woman with a huge portal-systemic shunt accompanied by myxedema showed slow speech and behavior. Several imaging studies revealed a bold portal-systemic shunt from the splenic vein to the left renal vein. In addition, hypothyroidism caused by chronic thyroiditis was diagnosed, and synthesized thyroxine replacement was effective for the symptoms. However, the serum ammonia and indocyanin green retention remained in the abnormal range, nevertheless the portal vein pressure was normal and findings of liver cirrohsis were not recognized histologically. Surgical shunt closure was performed, resulting in normalized serum ammonia levels and serum branched chain amino acids /aromatic amino acids ratio, and improvement of the ammonia tolerance test.

Adult↗

PubMed2001

Significant reduction of methicillin-resistant Staphylococcus aureus bacteremia in geriatric wards after introduction of infection control measures against nosocomial infections.

OBJECTIVES: (1) To investigate the efficacy of infection control measures against methicillin-resistant Staphylococcus aureus (MRSA) bacteremias in geriatric wards. (2) To identify predisposing risk factors for MRSA bacteremia. METHODS: Cases with nosocomial bacteremias were retrospectively analyzed between January 1991 and March 1995. The study period was divided into four annual periods and the period 1, January to December 1991, was applied as the control. MATERIALS: We investigated patients with nosocomial bacteremias in geriatric wards (190 beds) of AINO Memorial Hospital, affiliated with Nagasaki University. RESULTS: A significant reduction in cases with MRSA-induced nosocomial bacteremia was observed after the introduction of a stringent infection control and prevention program (period 1 vs. periods 2, 3, and 4: p<0.00833, p<0.00167, and p<0.00167, respectively). The major source of bacteremia included urinary tract infections, intravenous catheter-related infections, and infected decubitus ulcers. Improvement of decubitus ulcer was associated with a significant reduction in MRSA bacteremia (period 1 vs. periods 2 and 3: p<0.00017 and p<0.00833). CONCLUSION: Stringent infection control programs, including prevention and treatment of decubitus ulcers, are necessary in geriatric wards to reduce and prevent MRSA bacteremia.

Aged↗

PubMed2001

[The effect of celiprolol hydrochloride for lipid metabolism--especially for the low density lipoprotein particle size].

Recently, much attention has been paid to small sized low density lipoprotein (LDL) as a risk factor for ischemic heart disease. We investigated the effect of celiprolol hydrochloride (CH), which is a beta 1 selective beta-blocker with high intrinsic sympathomimetic activity (ISA), on the LDL particle size. We treated 41 hypertensive patients with CH and studied the change in LDL particle size according to the score of fast beta lipoprotein and LDL relative mobility value (LDL-Rm) measured by lipoprotein polyacrylamide gel disc electrophoresis (PAGE). We also studied changes in blood pressure, total cholesterol (TC), trygiyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and midband on PAGE. Systolic and dyastolic blood pressure and pulse significantly decreased during treatment. TC levels were significantly decreased at 8 weeks in all subjects and at 4, 8 and 12 weeks in patients with a TC value of over 220 mg/dl. TG levels were significantly decreased at 4 and 8 weeks in patients with initial levels of over 150 mg/dl, and significantly increased at 4 and 8 weeks in those with initial levels of under 150 mg/dl of TG. HDL-C levels did not significantly change during treatment. LDL-C levels were significantly decreased at 4, 8 and 12 weeks in patients with initial levels of over 150 mg/dl. Apo AI, AII, B, CII, CIII and E levels did not significantly change during treatment. Fast beta lipoprotein scores did not significantly change overall during treatment, but were significantly decreased at 4 and 8 weeks in patients initial TG levels of over 150 mg/dl and at 4 and 12 weeks in those with initial levels of over 220 mg/dl of TC. LDL-Rm scores did not significantly change during treatment. Midband scores were significantly reduced overall at 8 weeks, and after 4 and 8 weeks in patients with initial TG levels of over 150 mg/dl and at 4, 8 and 12 weeks in those with initial TC levels of over 220 mg/dl. These results indicated that CH did not change LDL particle size. It was suggested that CH might be a beneficial beta-blocker from the standpoint of prevention for atherosclerosis.

Aged↗

PubMed2001

Expression of bone formation-related molecules in a newly established protein-independent osteosarcoma.

Protein-independent cells are useful for analysis of proteins that are produced by the cells themselves without any consideration of exogenous proteins. This experimental protein-independent tumor system provides new biology of the autonomous nature of neoplastic cells during their evolution. We established a Dunn protein-free osteosarcoma (DPF) cell line, which was derived from parental fetal calf serum (FCS)-dependent murine Dunn osteosarcoma (DOS) cells. The DPF cells grew in a chemically defined protein-free medium at the high seeding density of 1x10(4) cells/well of a 96-well-plate with a similar doubling time to that of cells growing in the presence of FCS, while the cells did not grow at a density lower than 1x10(3)/well. Furthermore, addition of conditioned medium stimulated the growth in a dose-dependent manner. In contrast, DOS did not grow in the protein-free condition at all. Morphological examination revealed that DPF cells exhibited a more round shape than DOS cells. RT-PCR analysis exhibited the augmentation of the RNA message of bone morphogenetic protein-4 (BMP-4) and osteocalcin in DPF cells. Enhanced expression of BMP-4 protein was also demonstrated by immunoblot analysis. Furthermore, alkaline phosphatase (ALP) activity was higher in DPF cells, indicating that bone-formation related molecules may be overexpressed in protein-independent osteosarcoma cells. These results suggest that putative growth factors may play a role in the DPF cell growth in an autocrine fashion, and the acquisition of autonomous growth independent of exogenous proteins may be coupled to the osteogenic differentiation.

Alkaline Phosphatase↗

PubMed2001

High fat diet enhances colonic cell proliferation and carcinogenesis in rats by elevating serum leptin.

We postulated that high fat diet enhances colon cell proliferation and carcinogenesis by elevating serum leptin. To examine this possibility, the present study was conducted to investigate the effect of leptin on the growth of human colon cancer cells (HT29) and the relationship between serum leptin and colon cell proliferation and aberrant crypt foci (ACF) in the 1,2-dimethylhydrazine-treated rats fed graded levels of dietary fat for 28 days. In cell culture experiments, leptin stimulated the growth and proliferation (BrdU incorporation) of colon cancer cells and the expression of c-fos protein. In the in vivo experiments, an elevation of dietary fat caused higher serum leptin and adipose-tissue weight. Colonic cell proliferation (BrdU incorporation), c-fos protein expression and ACF were elevated with increasing dietary fat. There was a significant correlation between serum concentration of leptin and colon cell proliferation and ACF. The results suggest that the enhancement of colon cell proliferation and carcinogenesis by high fat diet is mediated through elevating serum leptin.

1,2-Dimethylhydrazine↗

PubMed2001

[A case of very rare tuberculosis of the testis].

A 61-year old man visited our hospital with a painless swelling of right scrotal contents as the chief complaint. Transillumination test of the right scrotal contents was negative, and a quail's egg sized, elastic hard and smooth induration in the right testis was palpable. The laboratory data were normal except for slightly elevated E.S.R and CRP. Urine examination was normal. Although not only tumor marker, beta-hCG, AFP and LDH but also Plain lung X-ray, DIP and CT were normal, ultrasonography and MRI revealed a well-defined nodule in the right testis. Under the diagnosis of right testicular tumor, right high orchiectomy was performed. A yellowish white nodule of 2.5 cm in diameter was found in the slightly enlarged right testis. Pathologically, the patient was diagnosed as having tuberculotic granuloma with necrotic caseation. However, the epididymis was histologically normal. After operation, an antitubercular medication was started. Subsequently, E.S.R and CRP became normalized. At present, 12 months after surgery, the recurrence is not found. Tuberculosis of testis which shows no lesion in the epididymis is very rare, and ours is the first reported case in the Japanese literature. The importance of tuberculosis as a revival infection should be recognized in social circumstance in which tuberculosis is beginning to spread again.

Humans↗