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Takahiro Hayashi

Publications and source records attributed to Takahiro Hayashi.

At least 19 recordsLinked to original sources
PubMed2006

Preventive effect of Shigyaku-san on progression of acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats.

The study examined whether Shigyaku-san (Si-Ni-San) extract (TJ-35), a traditional Kampo medicine, prevents acute gastric mucosal lesion progression in rats treated once with compound 48/80 (C48/80). Rats treated with C48/80 (0.75 mg/kg body weight, i.p.) received TJ-35 (0.15, 0.35 or 0.75 g/kg body weight, p.o.) 0.5 h after the treatment at which time gastric mucosal lesions appeared. At 0.5 h after C48/80 treatment, the gastric mucosa of the treated rats had increased myeloperoxidase (an index of neutrophil infiltration) and xanthine oxidase activities and thiobarbituric acid reactive substances (an index of lipid peroxidation) content. At 3 h after C48/80 treatment, the gastric mucosa of the treated rats showed progressive lesions and further increases in myeloperoxidase and xanthine oxidase activities and thiobarbituric acid reactive substances content and decreases in vitamin E, ascorbic acid and adherent mucus contents and Se-glutathione peroxidase activity. Post-administered TJ-35 attenuated all these changes found at 3 h after C48/80 treatment dose-dependently. These results indicate that TJ-35 prevents the progression of C48/80-induced acute gastric mucosal lesions in rats possibly by attenuating enhanced neutrophil infiltration, enhanced lipid peroxidation associated with decreased vitamin E and ascorbic acid contents and Se-glutathione peroxidase activity, and destruction of the defensive barrier in the gastric mucosa.

Animals↗
PubMed2006

Effects of alcohol consumption on cardiovascular events in male patients with healed myocardial infarction.

BACKGROUND: In Western countries, many studies have shown that among healthy people moderate drinkers have a lower incidence of cardiovascular events than abstainers and heavy drinkers. However, it is not clear whether this is true in patients with a healed myocardial infarction (MI). METHODS AND RESULTS: In the present study cardiovascular events were defined as cardiac events or strokes. Male patients only were included because the incidence of cardiovascular events is low in females. In patients younger than 65 years, the incidence of cardiovascular events was 34.6 persons per year (54 cases: 3.9%) of abstainers, 17.4 persons per year (20 cases: 1.9%) of moderate drinkers (p<0.01 vs abstainers) and 30.3 s persons per year (18 cases: 3.2%) of heavy drinkers. However, in those aged 65 years or older, the incidence was 47.8 persons per year (24 cases: 4.5%) of abstainers, 58.4 persons per year (14 cases: 5.6%) of moderate drinkers, and 314.8 persons per year (12 cases: 19.7%) of heavy drinkers. In this age group, cardiovascular events were significantly higher in heavy drinkers than in the other 2 groups (p<0.01), and the incidence was not lower in the moderate drinkers than in abstainers as shown in the younger group. CONCLUSIONS: In patients younger than 65 years with a healed MI, drinking limited less than 30 ml/day (moderate intake) reduces the incidence of cardiovascular events, but not in those aged 65 years or older.

Age Factors↗
PubMed2005

Usefulness of ST-segment elevation in the inferior leads in predicting ventricular septal rupture in patients with anterior wall acute myocardial infarction.

The ventricular septum receives its blood supply from the septal perforators of the left anterior descending (LAD) coronary artery and the right coronary artery. However, when the LAD artery extends to the inferior wall, beyond the apex (so-called wrapped LAD), the ventricular septum near the apex receives blood supply only from the LAD artery. As a consequence, ventricular septal rupture (VSR) would seem more likely in myocardial infarction with occlusion of this type of LAD artery. To test this hypothesis, we compared electrocardiographic findings in 21 patients who had anterior acute myocardial infarction that was complicated by VSR with those in 275 patients who had acute myocardial infarction that was not complicated by VSR. We observed ST-segment elevation in all inferior leads (II, III, and aVF) in addition to anterior leads in 42.9% of patients (9 of 21) who had VSR but in only 3.6% of those (10 of 275) who did not have VSR. Abnormal Q waves appeared in all 3 inferior leads in 44.4% of patients (8 of 18) who had VSR but in only 4.0% of those (10 of 250) who did not have VSR. Thus, the incidence of ST-segment elevation and abnormal Q waves in the inferior leads was significantly (p <0.001) greater in the VSR group. In addition, multivariate analysis of patient characteristics, including advanced age, female gender, and coronary morphology, showed VSR to be significantly correlated with ST-segment elevation (odds ratio 16.93, 95% confidence interval 4.13 to 69.30) and abnormal Q waves (odds ratio 13.64, 95% confidence interval 3.16 to 58.79) in the 3 inferior leads. In conclusion, these electrocardiographic findings can be useful predictors of complication by VSR.

Aged↗
PubMed2005

Wave structure analysis of guided waves in a bar with an arbitrary cross-section.

Both dispersion curves and wave structures, which are displacement distributions on a bar cross-section, are essential for guided wave NDEs. Theoretical dispersion curves and wave structures for a bar with an arbitrary cross-section are derived in this paper using a special modeling technique called the semi-analytical finite element method (SAFEM). The guidelines for guided wave NDEs of bar-like structures are also shown based on wave structure and modal analysis. First, the relationship between the dispersion curves and their corresponding wave structures were obtained for a square rod. Modes with longitudinal vibration have higher group velocities and torsional modes have constant phase and group velocities. Next, the relationship between the dispersion curves and wave structures for a rail are detailed. The rail is used to represent a bar with a complex cross-section. Similar to the square rod results, the rail's longitudinal modes have higher group velocities. However, the rail contains modes with local vibration. Finally, single mode detection and excitation techniques are introduced. A single mode can be obtained by detecting and exciting with a weighted function that corresponds to a specific mode's wave structure.

Journal Article↗
PubMed2005

Plaque erosion in the culprit lesion is prone to develop a smaller myocardial infarction size compared with plaque rupture.

BACKGROUND: Acute myocardial infarction (MI) stems from a disruption of the plaque in the coronary artery. Based on postmortem examinations, such plaque disruption has been classified as either a rupture or an erosion. Unfortunately, it has been difficult to clinically identify plaque ruptures and plaque erosions during the development of acute MI. To elucidate the relationships between clinical features and the morphological characteristics of the infarct-related lesions, we observed the culprit lesions in patients with acute MI by coronary angioscopy and intravascular ultrasound. METHODS: We examined culprit lesions in 107 patients with acute MI using coronary angioscopy and intravascular ultrasound immediately before performing percutaneous coronary intervention. The lesions were then classified as plaque ruptures or nonruptured erosions, and their clinical features were compared. RESULTS: Among the lesions studied, 44 were classified as plaque ruptures, 28 were classified as plaque erosions, and 35 were unclassified. Patients with nonruptured eroded plaques had more preinfarction angina before the onset of MI than those with ruptured plaques (53.6% vs 22.7%, P = .0074). They also had less ST-segment elevation MI (71.4% vs 93.2%, P = .0185), lower peak creatine kinase levels (2029 +/- 1517 vs 4033 +/- 2699 IU/L, P = .0009), less distal embolization after percutaneous coronary intervention (3.6% vs 36.4%, P = .0014), and less Q-wave MI 1 month after onset (40.7% vs 88.4%, P < .0001). CONCLUSION: Patients with eroded plaque lesions have smaller infarctions than those with ruptured plaque lesions, suggesting that an eroded plaque is less potently thrombogenic than a ruptured plaque.

Aged↗
PubMed2005

Defect imaging with guided waves in a pipe.

Guided wave techniques are expected to become an effective means for rapid, long-range inspection of pipes. Such techniques still have many practical difficulties in application, however, due to the complex characteristics of guided waves such as dispersion and their multimodal nature. A defect imaging technique is developed in this study to overcome the complexities of guided wave inspection. Received signals are separated into single-mode waveforms with a mode extraction technique and then spatial waveforms on the pipe surface at an arbitrary time are reconstructed. The predicted waveforms can provide a defect image at the moment when an incident wave arrives at a defect region, which is based on a time-reversal technique. This defect imaging technique is experimentally verified using eight signals detected at eight different circumferential positions. Images of artificial defects are obtained with one-hole and two-hole test pipes, and increasing the frequency of incident waves increases the resolution of the images. Holes and pipe ends are recognizable in the images, but the reconstructed images contain some errors in the area behind the defects where guided waves do not propagate or do not reflect back to the receiving transducers.

Journal Article↗
PubMed2005

Calcium antagonists for secondary prevention of myocardial infarction: is there a need to shift from short-acting to long-acting types?

BACKGROUND: Although short-acting nifedipine does not prevent myocardial infarction (MI), calcium antagonists with a long half-life may be effective. METHODS AND RESULTS: The present study was a retrospective analysis of the incidences of cardiac events among patients with a healed MI treated with 3 times-a-day type nifedipine (half-life 1.8 h; n=617), twice-a-day type nifedipine (half-life 4.0 h; n=527) and those not taking calcium antagonists (n=1,593) from 1986 to 1993, and the incidences of those on once-a-day type calcium antagonists (half-life 11.0 h; n=903) and those not taking calcium antagonists (n=2,788) from 1994 to 2001. Cardiac events included cardiac death and nonfatal recurrent MI. Single and multivariate analyses using the Cox-Hazard model were performed. From 1986 to 1993 cardiac events occurred in 38 patients with 3-times-a-day nifedipine (6.2%, hazard ratio and 95% confidence interval: 1.45 and 0.93-2.27), in 18 patients with twice-a-day nifedipine (3.4%: 0.68 and 0.39-1.20), 57 patients without calcium antagonists (3.6%). Cardiac events also occurred in 11 patients with once-a-day type nifedipine (1.2%: 0.72 and 0.37-1.42) and 48 patients without calcium antagonists (1.7%). Of the once-a-day type calcium antagonists, cardiac events were the lowest (2 patients, 0.6%: 0.32 and 0.08-1.31) in patients with amlodipine (half-life 39.0 h; n=334), which has the longest half-life. None of these drugs were a significant factor in the increase or decrease in the incidence of cardiac events. However, there was a good correlation between the half-life of the calcium antagonist and the hazard ratio for reducing cardiac events. CONCLUSION: Although there was a tendency toward a reduction in cardiac events using calcium antagonists with long half-life, none of these drugs could significantly reduce the incidence of cardiac events in patients with a healed MI.

Amlodipine↗
PubMed2005

Recent decline in hospital mortality among patients with acute myocardial infarction.

BACKGROUND: Many patients with acute myocardial infarction will still die after admission. Recent trends in hospital mortality were analyzed to identify aspects that need improvement. METHODS AND RESULTS: A total of 1,247 patients admitted to Kinki University School of Medicine within 24 h of the onset of infarction were analyzed between 1975 and 2001. The percentage of patients discharged with 100% occlusion decreased gradually from 31.3% during 1975-1982 to 2.1% during 1998-2001, while those with 50% stenosis or less gradually increased from 12.5% to 82.5% during the same period (trends: p < 0.01). The cardiac death rate was 17.1% in 1975-1982, and 7.7% in 1998-2001, showing a significant decrease with time (p < 0.01). This decrease was particularly marked among those admitted within 6 h of the onset of infarction. Death due to cardiac rupture decreased significantly with time (p < 0.001). In contrast, the non-cardiac death rate, amounting to 2.2% on average, did not decline. CONCLUSIONS: Cardiac deaths due to acute myocardial infarction have decreased markedly of late. However, patients must be admitted within 6 h of the onset of infarction to benefit from this improvement. More effort should be made to improve the general care of patients in order to reduce the incidence of non-cardiac death.

Aged↗
PubMed2004

Comparison of risk factors in acute myocardial infarction and unstable angina pectoris in patients < or =66 versus >66 years of age.

A prospective study was conducted of the differences in clinical characteristics between patients with acute myocardial infarction and those with unstable angina pectoris admitted to hospitals in the South-Osaka district of Japan. Gender and smoking were identified as discriminant risk factors for the incidence of acute myocardial infarction in patients < or =66 years with acute coronary syndromes; however, age alone affected the mode of presentation in older patients.

Age Factors↗
PubMed2004

Effect of Oren-gedoku-to (Huanglian-Jie-Du-Tang) extract on disruption of hepatic antioxidant defense systems in rats treated with D-galactosamine.

We have indicated that the antioxidant action of Oren-gedoku-to (Huanglian-Jie-Du-Tang) extract (TJ-15), a traditional Chinese herbal medicine, may contribute to its preventive effect on the progression of D-galactosamine (GAL)-induced liver injury in rats. Herein, we examined a possibility that TJ-15 exerts this preventive effect by attenuating the disruption of hepatic antioxidant defense systems in GAL-treated rats. TJ-15 (500 mg/kg) was orally administered to rats injected with GAL (500 mg/kg, i.p.) at 6 h after hepatotoxin treatment. In the liver of rats treated with GAL alone, the concentration of thiobarbituric acid-reactive substances (TBARS), an index of lipid peroxidation, increased at 24 h, but not at 6 h, while reduced glutathione (GSH) and ascorbic acid concentrations and superoxide dismutase (SOD), catalase, and Se-glutathione peroxidase (Se-GSH-px) activities decreased at 24 h, but not at 6 h. Post-administered TJ-15 prevented all these changes observed at 24 h after GAL treatment. TJ-15 administered to GAL-untreated rats in the same manner did not affect the hepatic TBARS, GSH, and ascorbic acid concentrations and SOD, catalase, and Se-GSH-px activities. These results indicate that post-administered TJ-15 attenuates the disruption of hepatic antioxidant defense systems in GAL-treated rats, which may contribute to its preventive effect on the progression of GAL-induced liver injury.

Animals↗
PubMed2004

Beta-blockers prevent cardiac events in Japanese patients with myocardial infarction.

BACKGROUND: Although the favorable effects of beta-blockers in the treatment of myocardial infarction (MI) have been repeatedly demonstrated in Western countries, administration of this drug has been limited in Japan. METHODS AND RESULTS: The study group of 1,896 patients with MI was retrospectively divided into 1,029 patients treated by beta-blockers and 867 not treated by beta-blockers, and the incidences of cardiac events, consisting of recurrent MI, death because of worsening heart failure, and sudden death, and cardiovascular events, comprising cardiac events and stroke, were compared in both groups. There were 45 cardiac events (4.4%, 30.1 patients/1,000 patients. year) among the beta-blocker group, which was significantly less than the 56 cardiac events (6.5%, 52.3 patients/1,000 patients. year) among the no-beta-blocker group (p<0.05). The total mortality was 92 (8.9%, 61.6 patients/1,000 patients. year) and 124 (14.3%, 115.8 patients/1,000 patients. year), respectively, and cardiac death occurred in 42 (4.1%, 28.1 patients/1,000 patients. year) and 53 (6.1%, 49.5 patients/1,000 patients. year), respectively, indicating that both these events occurred significantly less in the beta-blocker group (p<0.01 and p<0.05). CONCLUSIONS: Beta-blockers prevent cardiac events in Japanese patients with MI. However, a placebo-controlled, double-blind, multicenter, clinical trial conducted on a large scale in Japan would further contribute more precise information of the useful effects of beta-blockers.

Adrenergic beta-Antagonists↗
PubMed2004

Increased cardiac mortality in women compared with men in patients with acute myocardial infarction.

OBJECTIVE: It has been reported that women with acute myocardial infarction (AMI) have a higher short-term mortality rate than men, but the reason is not known. The profile in relation to age, gender and risk factors was evaluated to compare AMI and unstable angina pectoris (UAP). METHODS: Findings from 984 patients including 580 patients with AMI (129 women, 451 men) and 404 patients with UAP (131 women, 273 men) were analyzed by the South Osaka Acute Coronary Syndrome Study Group (SACS). The primary endpoint of the study was in-hospital death. The primary endpoints of interest (cardiac death) were fatal recurrent myocardial infarction, death from congestive heart failure, and sudden death. RESULTS: Cardiac death during hospitalization within 30 days in AMI was higher in women than in men (12.4% vs 6.7%, p < 0.05). On the other hand, in UAP there was no significant difference between women and men (1.5% vs 0.7%, NS). The incidence of cardiac death in AMI was significantly higher for patients 75 years old and older (19.0%) than for patients less than 55 years old (4.2%), 55-64 years old (3.5%) and 65-74 years old (4.7%) (p < 0.001, respectively). CONCLUSIONS: Cardiac death was higher for women compared with men in patients with AMI. The worse prognosis for the AMI women patients was likely to be derived from less performance of percutaneous coronary intervention, and a high incidence of severe myocardial infarction. Further research should be focused on the analysis of various clinical backgrounds.

Age Factors↗
PubMed2004

[Diagnosis of vascular complications at the puncture site after cardiac catheterization].

OBJECTIVES: Cardiac catheterization is increasingly used for the diagnosis or treatment of coronary artery disease. Previous studies that revealed the incidence of complications such as arteriovenous fistula and pseudoaneurysm were based on retrospective analysis of cohorts referred to vascular surgery. This study was designed to determine the incidence of arteriovenous fistula and pseudoaneurysm after percutaneous transluminal angiography. METHODS: All 557 consecutive patients undergoing cardiac catheterization were examined by ultrasonography from March 1, 2001 to April 1, 2002, to investigate the occurrence of arteriovenous fistula and pseudoaneurysm at the puncture site. RESULTS: Pseudoaneurysm was found in 16 patients (2.9%), and arteriovenous fistula in 12 patients (2.2%). Pseudoaneurysm in 7 patients (43.8%) and arteriovenous fistula in 6 patients (50.0%) were diagnosed only by ultrasonic examination. There were more female patients (9 patients, 56.3%) than male with pseudoaneurysm (p < 0.01). The puncture site was located after the division of the deep femoral artery and superficial femoral artery in all patients with complications. CONCLUSIONS: Ultrasonic examination was useful for diagnosis of complications such as arteriovenous fistula and pseudoaneurysm after cardiac catheterization.

Aged↗
PubMed2003

Guided wave dispersion curves for a bar with an arbitrary cross-section, a rod and rail example.

Theoretical and experimental issues of acquiring dispersion curves for bars of arbitrary cross-section are discussed. Since a guided wave can propagate over long distances in a structure, guided waves have great potential for being applied to the rapid non-destructive evaluation of large structures such as rails in the railroad industry. Such fundamental data as phase velocity, group velocity, and wave structure for each guided wave mode is presented for structures with complicated cross-sectional geometries as rail. Phase velocity and group velocity dispersion curves are obtained for bars with an arbitrary cross-section using a semi-analytical finite element method. Since a large number of propagating modes with close phase velocities exist, dispersion curves consisting of only dominant modes are obtained by calculating the displacement at a received point for each mode. These theoretical dispersion curves agree in characteristic parts with the experimental dispersion curves obtained by a two-dimensional Fourier transform technique.

Journal Article↗
PubMed2003

Analysis of flexural mode focusing by a semianalytical finite element method.

Focusing is one of the most promising techniques for the detection of small defects in pipe works, in which guided waves including longitudinal and flexural modes are tuned so that ultrasonic energy can be focused at a target point in a pipe, and analysis of reflected waves gives information on defects such as location and size. In this paper, the focusing technique is discussed by way of a simulation of guided wave propagation in pipe by a semianalytical finite element method (SAFE). Experiments and SAFE calculations were compared for waveforms transmitted by a single transducer and received at different circumferential positions initially, and then the focusing phenomena were experimentally observed using focusing parameters obtained by calculations. Calculation and visualization were conducted to clarify focusing phenomena in pipe in investigating the potential of the focusing technique. These results show that the time-reversal idea helps in understanding focusing and that resolution of focusing is strongly affected by incident waveforms as well as the number of channels available in an experiment.

Journal Article↗
PubMed2003

Pravastatin reduces the incidence of cardiac events among patients with myocardial infarction.

We retrospectively compared the incidence of cardiac events in myocardial infarction (MI) patients treated in our departments between 1990 and 1999 with pravastatin or without cholesterol-lowering agents. Our aim was to evaluate the efficacy of pravastatin in the secondary prevention of MI. Cardiac events--defined as fatal or nonfatal recurrent MI, sudden cardiac death, and death from congestive heart failure--occurred in 8 (2.2%) of 356 MI patients treated with pravastatin (17.1 cases/1.000 person x year) and in 39 (5.6%) of 700 MI patients not treated with cholesterol-lowering agents (54.3 cases/1000 person x year), which represented a significant decline among those taking pravastatin (P < 0.05, odds ratio: 0.39, 95% (CI: 0.18-0.84). Likewise, total mortality was significantly lower among patients treated with pravastatin (18 cases, 5.1%; 38.4 cases/1,000 person x year vs 77 cases, 11.0%; 107.2 cases/1,000 person x year, P < 0.01, odds ratio: 0.43, 95% CI: 0.25-0.73). Subgroup analysis revealed a significantly lower incidence or cardiac events in the pravastatin group for 6 of the items among 53 patient characteristics, and was lower but not significant for 45 items and was greater but not significant only for 2 items. Furthermore, multivariate analysis confirmed pravastatin to be a useful factor for preventing the occurrence of cardiac events in MI patients (P < 0.05, odds ratio: (0.44, 95% CI: 0.20-0.95), and Kaplan-Meier curves also showed pravastatin to significantly reduce the incidence of both cardiac events and total mortality. These findings are consistent with those previously reported by several large-scale clinical trials carried out in Western countries, and demonstrate that pravastatin is useful for secondary prevention of MI in Japanese patients.

Aged↗
PubMed2002

Evaluation of antilipid peroxidative action of propolis ethanol extract.

The antilipid peroxidative action of the ethanol extract of Brazilian propolis at a concentration of 47% (w/v) was evaluated by examining the inhibitory effect of the extract on the formation of hydroperoxide- and endoperoxide-type lipid peroxides during heating of authentic polyunsaturated fatty acids and on Fe(3+)-ADP/ascorbic acid- and Fe(3+)-ADP/NADPH-dependent lipid peroxidation reactions in rat liver microsomes. Hydroperoxide-type lipid peroxides were measured by the haemoglobin-methylene blue method and endoperoxide-type lipid peroxides by the thiobarbituric acid (TBA), Fe(3+)-TBA and LPO-586 methods. Propolis ethanol extract inhibited dose-dependently the formation of hydroperoxide- and endoperoxide-type lipid peroxides during heating of linoleic acid, linolenic acid or arachidonic acid and the amount of the extract causing a half inhibition of these lipid peroxide formations ranged between 20 and 75 microg. Propolis ethanol extract inhibited dose-dependently both Fe(3+)-ADP/ascorbic acid- and Fe(3+)-ADP/NADPH-dependent lipid peroxidation reactions in rat liver microsomes when lipid peroxides produced in both reactions were measured by the TBA method. The amount of propolis extract causing a half inhibition of the Fe(3+)-ADP/ascorbic acid-dependent lipid peroxidation was about 5 microg, while that of the extract causing a half inhibition of the Fe(3+)-ADP/NADPH-dependent lipid peroxidation was about 0.15 microg. These results indicate that the propolis ethanol extract exerts an antilipid peroxidative action at very low doses.

Adenosine Diphosphate↗