Coronary artery calcification in Japanese men in Japan and Hawaii

Explanations for the low prevalence of atherosclerosis in Japan versus the United States are often confounded with genetic variation. To help remove such confounding, the authors compared coronary artery calcification (CAC), a marker of subclinical atherosclerosis, between Japanese men in Japan and Japanese men in Hawaii. Findings were based on risk factors and CAC measured from 2001 to 2005 in 311 men in Japan and 300 men in Hawaii. Men were aged 40-50 years and without cardiovascular disease. After age adjustment, there was a threefold excess in the odds of prevalent CAC scores of > or = 10 in Hawaii versus Japan (relative odds = 3.2, 95% confidence interval: 2.1, 4.9). Whereas men in Hawaii had a generally poorer risk factor profile, men in Japan were four times more likely to smoke cigarettes (49.5% vs. 12.7%, p < 0.001). In spite of marked risk factor differences between the samples, none of the risk factors explained the low amounts of CAC in Japan. After risk factor adjustment, the relative odds of CAC scores of > or = 10 in Hawaii versus Japan was 4.0 (95% confidence interval: 2.2, 7.4). Further studies are needed to identify factors that protect against atherosclerosis in Japanese men in Japan.     

What cause of mortality can we predict by cholesterol screening in the Japanese general population?

OBJECTIVE: In a population with a markedly lower coronary mortality such as in Japan, the benefit of cholesterol screening may be different from Western populations. We attempted to assess the importance of cholesterol screening in Japan. DESIGN: A 13.2-year cohort study for cause-specific mortality. SETTING: Three hundred randomly selected districts throughout Japan in which the National Survey on Circulatory Disorders 1980 was performed. SUBJECTS: A total of 9216 community dwelling persons aged 30 years and over, with standardized serum cholesterol measurement and without a past history of cardiovascular disease. RESULTS: There were 1206 deaths, which included 462 deaths due to cardiovascular disease with 79 coronary heart diseases. Hypercholesterolemia (>6.21 mmol L-1) showed a significant positive relation to coronary mortality (relative risk; 2.93, 95% confidence interval; 1.52-5.63) but not to stroke. Although hypocholesterolemia (<4.14 mmol L-1) was significantly associated with an increased risk of liver cancer, noncardiovascular, noncancer disease and all-cause mortality, these associations, except for liver cancer, disappeared after excluding deaths in the first 5 years of the follow-up. The multivariate adjusted attributable risk of hypercholesterolaemia for coronary disease was 0.98 per 1000 person-years, which was threefold higher than that of hypocholesterolemia for liver cancer: 0.32 per 1000 person-years. The attributable risk percentage of hypercholesterolaemia was 66% for coronary heart disease. CONCLUSION: Similar to Western populations, it is recommended to provide screening for hypercholesterolaemia in Japan, especially for males, although its attributable risk for coronary disease might be small.     

Coronary artery calcification by computed tomography in epidemiologic research and cardiovascular disease prevention

Both American and European guidelines recommend coronary artery calcification (CAC) as a tool for screening asymptomatic individuals at intermediate risk for coronary heart disease (CHD). These recommendations are based on epidemiologic studies mostly in the United States. We review (1) the use of CAC in primary prevention of CHD in the United States, (2) epidemiologic studies of CAC in asymptomatic adults outside of the United States, and (3) international epidemiologic studies of CAC. This review will not consider clinical studies of CAC among patients or symptomatic individuals. US studies have shown that CAC is a strong independent predictor of CHD in both sexes among middle-aged and old age groups, various ethnic groups, and individuals with and without diabetes and that CAC plays an important role in reclassifying individuals from intermediate to high risk. Studies in Europe support these conclusions. The Electron-Beam Tomography, Risk Factor Assessment Among Japanese and US Men in the Post-World-War-II birth cohort (ERA JUMP) Study is the first international study to compare subclinical atherosclerosis, including CAC among Japanese, Japanese Americans, Koreans, and whites. It showed that as compared with whites, Japanese had lower levels of atherosclerosis, whereas Japanese Americans had similar or higher levels. CAC is being increasingly used as a screening tool for asymptomatic individuals in Europe and the United States. CAC is a powerful research tool, because it enables us to describe differences in atherosclerotic burden across populations. Such research could identify factors responsible for differences among populations, which may improve CHD prevention.     

Dietary phosphorus and blood pressure: international study of macro- and micro-nutrients and blood pressure

Raised blood pressure is a leading cause of morbidity and mortality worldwide; improved nutritional approaches to population-wide prevention are required. Few data are available on dietary phosphorus and blood pressure and none are available on possible combined effects of phosphorus, magnesium, and calcium on blood pressure. The International Study of Macro- and Micro-Nutrients and Blood Pressure is a cross-sectional epidemiologic study of 4680 men and women ages 40 to 59 from 17 population samples in Japan, China, United Kingdom, and United States. Blood pressure was measured 8 times at 4 visits. Dietary intakes were obtained from four 24-hour recalls plus data on supplement use. Dietary phosphorus was inversely associated with blood pressure in a series of predefined multiple regression models, with the successive addition of potential confounders, both nondietary and dietary. Estimated blood pressure differences per 232 mg/1000 kcal (2 SD) of higher dietary phosphorus were -1.1 to -2.3 mm Hg systolic/-0.6 to -1.5 mm Hg diastolic (n=4680) and -1.6 to -3.5 mm Hg systolic/-0.8 to -1.8 mm Hg diastolic for 2238 "nonintervened" individuals, ie, those without special diet/nutritional supplements or diagnosis/treatment for cardiovascular disease or diabetes. Dietary calcium and magnesium, correlated with phosphorus (partial r=0.71 and r=0.68), were inversely associated with blood pressure. Blood pressures were lower by 1.9 to 4.2 mm Hg systolic/1.2 to 2.4 mm Hg diastolic for people with intakes above versus below country-specific medians for all 3 of the minerals. These results indicate the potential for increased phosphorus/mineral intake to lower blood pressure as part of the recommendations for healthier eating patterns for the prevention and control of prehypertension and hypertension.     

Induction of rat liver bilirubin-conjugating enzymes and glutathione S-transferase by rifampicin

After oral administration of rifampicin and 25-desacetylrifampicin, which is a major metabolite of rifampicin in man but not in rat, to male Wister rats for 7 days, hepatic microsomal cytochrome P450, cytochrome b5, and activities of aniline hydroxylase, aminopyrine demethylase, bilirubin-conjugating enzymes and supernatant glutathione S-transferase were measured. Rifampicin induced bilirubin UDP-glucuronyltransferase, bilirubin UDP-glucosyltransferase, bilirubin UDP-xylosyltransferase and glutathione S-transferase activities, but did not induce mixed function oxidase activities. No inductive effect of desacetylrifampicin on any enzymes was observed. Serum bilirubin increased till the third day, and decreased after 7 days of rifampicin treatment. Plasma clearances of indocyanine green and sulfobromophthalein showed a marked delay after 1 day and 7 days of rifampicin treatment. Induction of bilirubin-conjugating enzymes and glutathione S-transferase by rifampicin in rats was different from that in humans, in which selective induction of mixed function oxidase is reported to occur. This species difference does not seem to be derived from the species difference of rifampicin metabolism, because no effect of desacetylrifampicin was observed. These results suggested that in rats rifampicin directly inhibits the hepatic excretion of bilirubin, whereas it enhances bilirubin conjugation due to enzyme induction.     

Initial change in transient osteoporosis of the hip on magnetic resonance images: a case report

We report the case of a 29-year-old Japanese man with transient osteoporosis of the left hip (TOH) following contralateral TOH, paying special attention to the initial changes on MRI. MR images showed no abnormal findings 6 weeks before the clinical manifestation, but the images just after the onset depicted a linear abnormality equivalent to a subchondral insufficiency fracture. Both radiological findings and clinical symptoms disappeared completely without any surgical intervention within 10 months.     

Effect of combined cardiovascular risk factors on individual and population medical expenditures: a 10-year cohort study of national health insurance in a Japanese population.

BACKGROUND: Although obesity is required for some criteria defining metabolic syndrome, clustering of other risk factors also indicates an increased risk of cardiovascular disease. Whether the relationship between cardiovascular risk factor clustering and medical expenditures differs with body mass index (BMI) requires investigation, especially in a population with a low prevalence of obesity such as that in Japan. METHODS AND RESULTS: A 10-year cohort study of 4,478 Japanese National Health Insurance beneficiaries aged 40-69 years in a community between 1990 and 2001 was carried out in the present study. The clustering of cardiovascular risk factors showed a positive and graded relationship to personal medical expenditures in participants who are overweight (BMI > or =25.0) and normal weight (BMI <25.0). The individual medical expenditures per month were 1.7-fold higher for participants with 2 or 3 risk factors and overweight than for those without these factors (26,782 vs 15,377 Japanese yen). Differences in the geometric means were similarly significant after adjustment for other confounding factors. However, the excess medical expenditures by risk clustering of normal weight categories within the total medical expenditures were higher than those of overweight categories because more participants were of normal weight. CONCLUSIONS: Cardiovascular risk factor clustering and being overweight can be a useful predictor of medical expenditures in a Japanese population.