Keitaro Tanaka

Relation between green tea consumption and the severity of coronary atherosclerosis among Japanese men and women

PURPOSE To examine the relation between green tea consumption and arteriographically determined coronary atherosclerosis. METHODS Study subjects were 512 patients (302 men and 210 women) aged 30 years or older who underwent coronary arteriography for the first time at four hospitals in Fukuoka City or one hospital in an adjacent city between September 1996 and August 1997. Lifestyle characteristics including green tea consumption were ascertained before arteriography by a questionnaire supported with interview. RESULTS 117 men (38.7%) and 50 women (23.8%) had significant stenosis of one or more coronary arteries. Green tea consumption tended to be inversely associated with coronary atherosclerosis in men, but not in women. An evident, protective association between green tea and coronary atherosclerosis was observed in a subgroup of 262 men excluding those under dietary or drug treatment for diabetes mellitus. In this subgroup, after adjustment for traditional coronary risk factors and coffee, odds ratios of significant stenosis for consumption of 2-3 cups and 4 or more cups per day were 0.5 (95% confidence interval 0.2-1.2) and 0.4 (0.2-0.9), respectively, as compared with a consumption of one cup per day or less. CONCLUSIONS The results indicate that green tea may be protective against coronary atherosclerosis at least in men.

Green Tea Consumption and Serum Lipids and Lipoproteins in a Population of Healthy Workers in Japan

PURPOSE To examine the relation between green tea consumption and serum lipids and lipoproteins. METHODS The subjects were 13,916 workers (8476 men and 5440 women) aged 40-69 years at over 1000 workplaces in Nagano prefecture, central Japan. They underwent health screening offered by a single medical institute between April 1995 and March 1996 and did not have morbid conditions affecting serum cholesterol levels. Serum concentrations of total cholesterol, high-density lipoprotein (HDL) cholesterol and triglycerides were measured at the screening. The consumption of green tea and other life-style characteristics were ascertained by a questionnaire. The data were analyzed with multivariate linear model. RESULTS Daily consumption of green tea was reported by 86.7% of subjects. Green tea consumption was, statistically, significantly associated with lower levels of serum total cholesterol in both men and women while its associations with serum triglycerides and HDL cholesterol were not statistically significant. The inverse association of serum total cholesterol with green tea consumption appeared to level off at the consumption of more than 10 cups/day. Excluding the outlying subjects drinking more than 10 cups/day (0.4%), the regression analysis adjusting for age, body mass index, ethanol intake, smoking habit, coffee intake, and type of work showed that daily consumption of one cup of green tea was associated with a reduction in serum total cholesterol by 0.015 mmol/L (95% confidence interval 0.006 to 0.024, p < 0.001) in men and 0.015 mmol/L (0.004 to 0.025, p < 0.01) in women. After additional adjustment for selected dietary factors, the inverse association remained statistically significant; one cup of green tea per day was associated with a reduction in serum total cholesterol by 0.010 mmol/L (0.001 to 0.019, p = 0.03) in men and 0.012 mmol/L (0.001 to 0.022, p = 0.03) in women. CONCLUSION Consumption of green tea was associated with lower serum concentration of total cholesterol in Japanese healthy workers age 40-69 years; however, green tea consumption was unrelated to serum HDL-cholesterol and triglycerides.

The relationship between CYP1A1 aryl hydrocarbon hydroxylase activity and lung cancer in a Japanese population.

Because aryl hydrocarbon hydroxylase (AHH) is considered to be responsible for the activation of benzo(a)pyrene and other polyaromatic hydrocarbons in cigarette smoke to carcinogens, it is important to examine CYP1A1 (AHH) activity in the determination of susceptibility to lung cancer. We investigated AHH activity in peripheral mitogen-treated lymphocytes in 108 lung cancer patients and 95 healthy control individuals. Non-induced AHH activity was detectable in all the samples. AHH inducibility (3-methylcholanthrene-induced/non-induced AHH activity) showed a very wide interindividual variation as well as non-induced AHH activity. No significant associations were found between adjusted AHH activity and histologic type of tumor among lung cancer patients. Adjusted AHH inducibility of genotype C [geometric mean and 95% confidence interval (CI); 15.56 and 11.69-20.71] in MspI polymorphism was significantly higher than those of the other two genotypes (P = 0.0001), while no significant difference was observed between genotypes A (4.76 and 3.82-5.93) and B (5.60 and 4.57-6.86). On the other hand, non-induced AHH activity of genotype Val/Val (0.121 and 0.082-0.178 pmol/min/10(6) cells) in isoleucine-valine (Ile-Val) polymorphism was significantly higher than those of genotypes Ile/Ile (0.042 and 0.034-0.052 pmol/min/10(6) cells) and Ile/Val (0.040 and 0.030-0.053 pmol/min/10(6) cells) (P < 0.0001). Even after controlling for age, cigarettes smoked per day and season of the year, high AHH inducibility (7.0 < versus 0 < < or = 3.0: OR and 95 %CI, 12.4 and 2.88-53.4) was an independent risk factor for lung cancer. The data indicate that high AHH inducibility may strongly associate with the susceptibility to lung carcinogenesis.

A long-term follow-up study on risk factors for hepatocellular carcinoma among Japanese patients with liver cirrhosis.

To identify virological parameters (serostatus of hepatitis B surface antigen [HBsAg] and antibodies to hepatitis C virus [anti‐HCV], HCV genotypes and HCV‐RNA titer) and other clinico‐biological and lifestyle variables that may influence or predict the development of hepatocellular carcinoma (HCC) in cirrhosis, we followed 100 cirrhotic patients without HCC, who visited Kyushu University Hospital between 1985 and 1987, until the end of 1995 (follow‐up rate: 98%; average follow‐up period: 5.3 years). After elimination of 4 patients who developed HCC or were censored within the initial 6 months, 37 (39%) out of 96 patients developed HCC during follow‐up. As compared with HBsAg(+) patients, anti‐HCV(+) HBsAg(–) patients demonstrated significantly elevated HCC risk (adjusted hazard ratio [HR]=5.85, 95% confidence interval [CI] 1.65–20.67). Genotype 1 HCV infection was not associated with increased risk compared with genotype 2 (HR = 0.64, 95% CI 0.21–1.99). For genotype 1 HCV infection, patients with HCV‐RNA levels <1 Meq/ml tended to present lower risk than patients with ≥1 Meq/ml (P= 0.03). Male sex, advanced Childs class, lower serum albumin, and higher serum aminotransferase and α‐fetoprotein were also found to be strong predictors. Overall, drinking and smoking habits were not associated with significantly elevated risk. Among virological parameters, anti‐HCV positivity and, possibly high HCV‐RNA titer, were predictive of HCC occurrence in cirrhosis in our clinical setting.

Risk factors for hepatocellular carcinoma among Japanese women.

To elucidate the risk factors for hepatocellular carcinoma (HCC) among women, we made a combined analysis of the data from three case-control studies conducted in high-risk areas of Japan. A total of 120 cases and 257 controls were included in the analysis. After adjustment for the study category, age, and other potential confounders, significantly increased risks were associated with chronic hepatitis-B virus infection (odds ratio [OR]=42.4, 95 percent confidence interval [CI]=11.2–160.2), a past history of blood transfusion (OR=3.7, CI=1.8–7.5), and a history of smoking (OR=2.2, CI=12–4.1). In addition, women with a history of heavy drinking experienced an elevated risk of borderline significance (OR=4.2, CI=0.9–20.4, P=0.07). When these ORs were compared with the corresponding estimates among males from the same case-control studies, no significant differences were observed between the two genders. Among the factors examined in this analysis, drinking and smoking habits—which are more common among Japanese men than women—may partly account for a large male-predominance in the incidence of HCC. Further studies are needed to clarify the roles that sex-hormones and hepatitis-C virus infection might play in the large gender difference of HCC occurrence.

Obesity, body fat distribution and coronary atherosclerosis among Japanese men and women

OBJECTIVE: To investigate the relation of the obesity and body-fat distribution with angiographically defined coronary atherosclerosis.DESIGN: Cross-sectional study in a clinical setting.SUBJECTS: Three hundred and twenty men (median age, 59 y) and 212 women (median age, 67 y) who underwent coronary angiography for suspected or known coronary heart disease at 5 cardiology departments between September 1996 and August 1997. Patients with disease duration >1 y were excluded.MEASUREMENTS: The body mass index (BMI) and the waist to hip circumference ratio (WHR) were used as main exposure variables, and either the presence of significant coronary stenosis or the Gensinis score (≥10 vs<10) as an outcome variable, in a sex-specific multiple logistic regression analysis controlling for age, hospital, and other coronary risk factors.RESULTS: Among male patients, BMI was progressively higher with an increasing number of vessels involved (P trend=0.05); the adjusted odds ratios for the presence of significant stenosis across quartiles of BMI were 1.0 (reference), 1.1, 1.9 and 2.5 (P trend=0.02), and the positive association was more pronounced for younger patients. Among females, however, such associations were not evident. Employing the Gensinis score as an outcome gave similar results. WHR was not significantly associated with either outcome regardless of sex.CONCLUSION: These results suggested that BMI was predictive of coronary stenosis among male patients, but not among female patients. Unlike most previous studies, this study failed to detect a positive association with WHR.

Job strain, Type A behavior pattern, and the prevalence of coronary atherosclerosis in Japanese working men

OBJECTIVE To examine the relation of type A behavior pattern and job strain to angiographically documented coronary stenosis. METHODS Subjects were 197 male Japanese patients with a full-time job. A questionnaire-based interview elicited psychosocial and other factors. Type A behavior pattern was measured by 12 questions, and job strain by the method of Karasek. Significant coronary stenosis was defined when a 75% or greater luminal narrowing occurred at one or more major coronary arteries or when a 50% or greater narrowing occurred at the left main artery. Logistic regression analysis was used to calculate odds ratio (OR) and 95% confidence interval (CI) with adjustment for traditional coronary risk factors and job type. RESULTS Type A behavior pattern was related to a statistically non-significant lower prevalence of the coronary stenosis especially in the absence of job strain (adjusted OR 0.6, 95% CI 0.3-1.2). Job strain was non-significantly associated with a modestly increased prevalence of coronary stenosis (OR 1.7, 95% CI 0.6-5.2). CONCLUSION These findings suggest that both the behavioral pattern and psychosocial work environment may be related to coronary artery stenosis.

Alcohol consumption and severity of angiographically determined coronary artery disease in Japanese men and women.

The relation of alcohol consumption to the severity of coronary atherosclerosis was examined among 323 men and 220 women who underwent coronary arteriography. Severity of coronary atherosclerosis was assessed by the number of vessels obstructed > or =75% in diameter and Gensinis severity score. Alcohol consumption was divided into 5 categories in men (never, past, 1-24, 25-49, and > or =50 ml per day) and 3 categories in women (never, past, and current). Among men, odds ratios of severe stenosis (multiple-vessel disease or Gensinis score >15) decreased substantially and significantly in all current drinking categories but without dose-response effect. There was a weak, inverse association of current alcohol consumption with one-vessel disease, but not with moderate stenosis in terms of Gensinis score (< or =15). Past drinkers showed a fairly large, but statistically nonsignificant, decrease in the odds ratios of not only severe stenosis but also of moderate stenosis. Among women, current drinkers showed a small, statistically nonsignificant decrease in the risk of severe stenosis in terms of Gensinis score. These associations with alcohol use did not change after adjustment for known coronary risk factors. The present findings add to evidence that alcohol drinking confers protection against coronary atherosclerosis.

Relation between type A behavior pattern and the extent of coronary atherosclerosis in Japanese women.

This study examined the relation of Type A behavior pattern and its components to angiographically documented coronary atherosclerosis in 198 Japanese women. A questionnaire-based interview elicited psychosocial and other factors. Type A behavior pattern was measured by 12 questions. Significant coronary stenosis was defined when a 75% or greater luminal narrowing occurred atoneor more major coronary arteries or 50% or greater narrowing occurred at the left main artery. Gensini’s score also was calculated. Logistic regression analysis was used to calculate odds ratios and 95% confidence intervals with adjustment for traditional coronary risk factors and the presence of a job. Global Type A behavior pattern showed no material association with the severity of coronary atherosclerosis assessed by both Gensini’s score and the presence of significant coronary stenosis. However, its subcomponents, enthusiasm and competitiveness, were positively related to the severity of coronary atherosclerosis, whereas self-confidence and perfectionism were negatively related. These findings suggest overall a null association between global Type A and coronary atherosclerosis as well as the presence of toxic or beneficial components of Type A behaviors in Japanese women.