Association between parental occupations, educational levels, and household income and children's psychological adjustment in Japan.

OBJECTIVES: Most research on the association between parental or family socio-economic status and psychological adjustment in children has been performed mainly in Western countries, while there is limited evidence of such research in Asian countries. We examined the association of parental occupation and educational levels and household income with children's psychological adjustment in Japan. STUDY DESIGN: This was a cross-sectional study. METHODS: Study subjects were 6329 children aged 3 years. Children's psychological adjustment was assessed using the Strengths and Difficulties Questionnaire. RESULTS: Compared with having an unemployed father, having a father who worked in an administrative and managerial or clerical job was associated with a lower prevalence of peer problems. Compared with having an unemployed mother, having a mother who worked in the professional and engineering, sales, service, or manufacturing process area was associated with a lower prevalence of low prosocial behaviors, whereas having a mother who worked in the clerical, service, or manufacturing process area was associated with an increased prevalence of emotional problems. Having a mother who worked in a clerical area was associated with a higher prevalence of conduct problems. Higher paternal and maternal educational levels were inversely associated with the prevalence of conduct problems and hyperactivity but were positively associated with low prosocial behaviors. A higher household income was inversely associated with the prevalence of emotional problems, conduct problems, and hyperactivity. CONCLUSION: Parental occupation, educational levels, and household income may affect children's psychological adjustment in Japan.

Cigarette smoking and cervical cancer risk: an evaluation based on a systematic review and meta-analysis among Japanese women.

BACKGROUND: There is a body of evidence to suggest that cigarette smoking increases the risk of cervical cancer in women, but no study has examined the magnitude of the association in Japanese women. Here, we evaluated the association between cigarette smoking and the risk of cervical cancer in Japanese women based on a systematic review of epidemiological evidence. METHODS: Original data were obtained from a MEDLINE search using PubMed or from a search of the 'Ichushi' database, as well as by a manual search. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as evaluated previously by the International Agency for Research on Cancer. Meta-analysis of associations was also conducted to obtain a summarized overview of the data. RESULTS: We identified two cohort studies and three case-control studies. All five studies had indicated strong positive associations between cigarette smoking and the risk of cervical cancer. Our summary estimate indicated that the relative risk (RR) for individuals who had ever-smoked relative to never-smokers was 2.03 (95% confidence interval: 1.49-2.57). Four studies had also demonstrated dose-response relationships between cigarette smoking and the risk of cervical cancer. CONCLUSION: We conclude that there is convincing evidence that cigarette smoking increases the risk of cervical cancer among Japanese women.

Preterm birth is associated with higher prevalence of wheeze and asthma in a selected population of Japanese children aged three years.

BACKGROUND: The present cross-sectional study investigated the associations between low birthweight (LBW), high birthweight, preterm birth (PTB), postterm birth, small for gestational age (SGA), and large for gestational age (LGA) and the prevalence of wheeze and asthma in Japanese children aged three years (age range, 33-54 months; mean age, 38.7 months). METHODS: Study subjects were 6364 children. A questionnaire was used to collect all data. Wheeze and asthma were defined according to the criteria of the International Study of Asthma and Allergies in Childhood. RESULTS: The prevalence values of wheeze and asthma were 19.5% and 7.7%, respectively. Of the 6364 subjects, 8.8% were classified as LBW (<2500g), 90.4% as normal birthweight, 0.8% as high birthweight (≥4000g), 4.8% as PTB (<37 weeks), 94.8% as term birth, 0.4% as postterm birth (≥42 weeks), 7.8% as SGA (<10th percentile), 82.5% as appropriate for gestational age, and 9.7% as LGA (>90th percentile). Compared with term birth, PTB was independently positively associated with wheeze and asthma: the adjusted ORs (95% CI) were 1.47 (1.11-1.92) and 1.52 (1.02-2.20), respectively. An independent positive association was shown between PTB and wheeze only in boys; the interaction between PTB and sex was significant. Such an interaction between PTB and sex was not seen for asthma. No evident associations were observed between LBW, high birthweight, postterm birth, SGA, or LGA and wheeze or asthma. CONCLUSIONS: This is the first study in Japan to show that PTB, but not LBW or SGA, was significantly positively associated with childhood wheeze and asthma.

Evidence-based cancer prevention recommendations for Japanese.

A comprehensive evidence-based cancer prevention recommendation for Japanese was developed. We evaluated the magnitude of the associations of lifestyle factors and infection with cancer through a systematic review of the literature, meta-analysis of published data, and pooled analysis of cohort studies in Japan. Then, we judged the strength of evidence based on the consistency of the associations between exposure and cancer and biological plausibility. Important factors were extracted and summarized as an evidence-based, current cancer prevention recommendation: 'Cancer Prevention Recommendation for Japanese'. The recommendation addresses six important domains related to exposure and cancer, including smoking, alcohol drinking, diet, physical activity, body weight and infection. The next step should focus on the development of effective behavior modification programs and their implementation and dissemination.

High birthweight is associated with increased prevalence of dental caries in Japanese children.

OBJECTIVE: We determined the prevalence of dental caries in 3-year-old Japanese children in a cross-sectional study and analysed its associations with birthweight, gestational age and birthweight for gestational age among the study subjects. METHODS: Study subjects were 6327 children. Their parents or guardians completed our study questionnaire with information on birth conditions and oral examinations taken from their Maternal and Child Health Handbooks, as documented by medical personnel at the hospital, clinic or public health centre. Children with one or more primary teeth that had either decayed or been filled were categorized as having caries. RESULTS: The prevalence of dental caries was 14.7%. We found a significant association between high birthweight (≥4000 g) and a higher prevalence of caries, compared with normal birthweight (2500-3999 g). Low birthweight (<2500 g) was not associated with dental caries prevalence. In addition, no measurable associations between gestational age or birthweight for gestational age and caries prevalence were observed. CONCLUSIONS: Our findings indicate that high birthweight might increase the likelihood of dental caries in children.

Prospective study of dietary energy density and weight gain in a Japanese adult population.

High dietary energy density (ED) has been associated with weight gain. However, little is known about the long-term effects of ED on weight changes among free-living subjects, particularly in Japanese and other Asian populations. In this study, we assessed dietary habits and weight changes in participants (5778 males and 7440 females, 35-69 years old) of the Takayama study. ED was estimated using a validated FFQ at baseline only. Information on body weight (BW) was obtained by self-administered questionnaires at baseline and follow-up. Mean BW difference in 9·8 years was 17 (se 4221) g for men and -210 (se 3889) g for women. In men, ED was positively associated with BW at follow-up after controlling for age, BW, height, physical activity score, alcohol consumption, energy intake, years of education at the baseline and change of smoking status during the follow-up. On average, men in the highest quartile of ED (>5·322 kJ/g (>1·272 kcal/g)) gained 138 (se 111) g, whereas men in the lowest ED (<1·057) lost 22 (se 111) g (P for trend=0·01). The association between ED and BW gain was stronger in men with normal weight. In women, the association between ED and weight change was not statistically significant. In conclusion, contrary to some studies that report an association between ED and weight gain in the overweight only, our data suggest that high-ED diets may be associated with weight gain in the lean population as well, at least in male subjects.

Association of vegetable and fruit intake with gastric cancer risk among Japanese: a pooled analysis of four cohort studies.

BACKGROUND: Prospective evidence is inconsistent regarding the association between vegetable/fruit intake and the risk of gastric cancer. METHODS: In an analysis of original data from four population-based prospective cohort studies encompassing 191 232 participants, we used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of gastric cancer incidence according to vegetable and fruit intake and conducted a meta-analysis of HRs derived from each study. RESULTS: During 2 094 428 person-years of follow-up, 2995 gastric cancer cases were identified. After adjustment for potential confounders, we found a marginally significant decrease in gastric cancer risk in relation to total vegetable intake but not total fruit intake: the multivariate-adjusted HR (95% CI; P for trend) for the highest versus the lowest quintile of total vegetable intake was 0.89 (0.77-1.03; P for trend = 0.13) among men and 0.83 (0.67-1.03; P for trend = 0.40) among women. For distal gastric cancer, the multivariate HR for the highest quintile of total vegetable intake was 0.78 (0.63-0.97; P for trend = 0.02) among men. CONCLUSIONS: This pooled analysis of data from large prospective studies in Japan suggests that vegetable intake reduces gastric cancer risk, especially the risk of distal gastric cancer among men.

Body mass index and breast cancer risk in Japan: a pooled analysis of eight population-based cohort studies.

BACKGROUND: A positive association between body mass index (BMI) and breast cancer risk among postmenopausal women has been reported, and a weak inverse association has been suggested among premenopausal women from studies in the Western population. The effects of BMI on breast cancer have remained unclear among the Asian population, especially in premenopausal women. METHODS: We assessed the associations between BMI and breast cancer incidence by a pooled analysis from eight representative large-scale cohort studies in Japan. Cancer incidence was mainly confirmed through regional population-based cancer registries and/or through active patient notification from major local hospitals. Breast cancer was defined as code C50 according to ICD10. Pooled estimates of the hazard ratios (HRs) and 95% confidence interval (CIs) for breast cancer were calculated using random-effects models. RESULTS: Analytic subjects were 183 940 women, 1783 of whom had breast cancer during 2 194 211 person-years of follow-up. A positive association between BMI and the risk of postmenopausal breast cancer was observed (trend P<0.001). The HRs for premenopausal breast cancer were 1.05 (95% CI 0.56-1.99), 1.07 (95% CI 0.76-1.52), 0.91 (95% CI 0.64-1.30), 1.15 (95% CI 0.76-1.73), 1.45 (95% CI 0.71-2.94), and 2.25 (95% CI 1.10-4.60), respectively, in BMIs of <19, 19 to <21, 21 to <23, 25 to <27, 27 to <30, and ≥30 kg/m2. These results were not substantially altered after excluding the patients who were diagnosed with breast cancer in the first 2 years of follow-up. CONCLUSIONS: The increased risk of postmenopausal breast cancer among women with higher BMIs was confirmed in Japanese. A borderline-significant positive association between BMI and premenopausal breast cancer was observed, suggesting that body mass in Asian women might have opposite effects on breast cancer compared with Western women.

Association between body mass index and the colorectal cancer risk in Japan: pooled analysis of population-based cohort studies in Japan.

BACKGROUND: Obesity has been recognized as important risk factors for colorectal cancer. However, limited evidence is available on colorectal cancer and body mass index (BMI) in Asian population. METHODS: We conducted a pooled analysis of eight population-based prospective cohorts studies in Japan with more than 300,000 subjects to evaluate an impact of obesity in terms of BMI on colorectal cancer risk with unified categories. We estimated summary hazard ratio (HR) by pooling of study-specific HR for BMI categories with random effect model. RESULTS: We found a significant positive association between BMI and colorectal cancer risk in male and female. Adjusted HRs for 1 kg/m(2) increase were 1.03 [95% confidence interval (CI) 1.02-1.04] for males and 1.02 (95% CI 1.00-1.03) for females. The association was stronger in colon, especially in proximal colon, relative to rectum. Males showed a stronger association than females. Population attributable fraction for colorectal cancer by BMI ≥ 25 kg/m(2) was 3.62% (95% CI 1.91-5.30) for males and 2.62% (95% CI 0.74-4.47) for females. CONCLUSIONS: We found significant association between BMI and colorectal cancer risk by pooling of data from cohort studies with considerable number of subjects among Japanese population. This information is important in cancer control planning, especially in Asian population.

Green tea consumption and gastric cancer in Japanese: a pooled analysis of six cohort studies.

BACKGROUND: Previous experimental studies have suggested many possible anti-cancer mechanisms for green tea, but epidemiological evidence for the effect of green tea consumption on gastric cancer risk is conflicting. OBJECTIVE: To examine the association between green tea consumption and gastric cancer. METHODS: We analysed original data from six cohort studies that measured green tea consumption using validated questionnaires at baseline. Hazard ratios (HRs) in the individual studies were calculated, with adjustment for a common set of variables, and combined using a random-effects model. RESULTS: During 2 285 968 person-years of follow-up for a total of 219 080 subjects, 3577 cases of gastric cancer were identified. Compared with those drinking <1 cup/day, no significant risk reduction for gastric cancer was observed with increased green tea consumption in men, even in stratified analyses by smoking status and subsite. In women, however, a significantly decreased risk was observed for those with consumption of > or =5 cups/day (multivariate-adjusted pooled HR = 0.79, 95% confidence interval (CI) = 0.65 to 0.96). This decrease was also significant for the distal subsite (HR = 0.70, 95% CI = 0.50 to 0.96). In contrast, a lack of association for proximal gastric cancer was consistently seen in both men and women. CONCLUSIONS: Green tea may decrease the risk of distal gastric cancer in women.

Effect of soymilk consumption on serum estrogen concentrations in premenopausal Japanese women.

BACKGROUND: Estrogens have been implicated in the development of breast cancer. Preliminary evidence suggests that consumption of soy products, which contain isoflavones (phytoestrogens), can reduce serum estrogen levels. Our purpose was to determine the effect of soy consumption on serum estrogen levels in premenopausal women by use of a dietary intervention approach. METHODS: Premenopausal Japanese women were randomly assigned to receive either a soymilk-supplemented diet (n = 31) or a normal (control) diet (n = 29). The women in the soymilk-supplemented group were asked to consume about 400 mL of soymilk (containing about 109 mg of isoflavones) daily during a study period that involved three consecutive menstrual cycles. Follicular-phase blood samples were to be obtained in the menstrual cycles preceding (cycle 1) and following (cycle 3) the 2-month dietary intervention. All statistical tests were two-sided. RESULTS: At the end of the study period, estrone and estradiol levels were decreased by 23% and 27%, respectively, in the soymilk-supplemented group and were increased by 0.6% and 4%, respectively, in the control group. The changes for each hormone between the two groups were not statistically significantly different. In the soymilk-supplemented group, menstrual cycle length was increased by nearly 2 days, and, in the control group, it was decreased by approximately 1 day, a difference that was not statistically significant. A subgroup analysis restricted to subjects who provided follicular-phase blood samples on the same day or 1 day apart in menstrual cycles 1 and 3 showed a reduction in serum estrone levels in the soymilk-supplemented group that was of borderline statistical significance (P = .07 for change in serum estrone level in soymilk-supplemented group versus control group). CONCLUSION: Much larger studies will be required to confirm the ability of soy products to reduce serum estrogen levels.

Skin pigmentation is inversely associated with insulin resistance in healthy Japanese women.

AIM: As a low-pigment skin type is prevalent in men and women with type 1 diabetes, it is possible that skin pigmentation may be associated with insulin resistance. This study aimed to cross-sectionally examine this association in healthy women. METHODS: Study participants were 792 Japanese women who attended a health examination and were not taking any medication for diabetes. Skin pigmentation on the inner upper and lower arms and forehead was measured using a Mexameter® skin colorimeter, a narrow-band reflective spectrophotometer. Data are expressed as a melanin index, which quantifies melanin content. Fasting blood glucose and insulin levels were also measured, and homoeostasis model assessment for insulin resistance (HOMA-IR) scores were calculated. Information on medical history and lifestyle factors were obtained by a self-administered questionnaire, while data on sun exposure were collected through interviews. Plasma 25-hydroxyvitamin D levels were measured in a subsample of women (n=464). RESULTS: Melanin indices at the inner upper and lower arms were significantly and inversely associated with fasting insulin levels and HOMA-IR after controlling for age, body mass index, smoking status, indicators for rater effects, cumulative sun exposure and season at the time of measurement. Additional adjustment for plasma 25-hydroxyvitamin D levels did not alter the results. CONCLUSION: These data suggest that skin pigmentation is associated with insulin resistance, and encourage future studies into the potential role of melanin and related factors in glucose homoeostasis.

The effect of phenethyl alcohol on in vitro DNA synthesis in Escherichia coli.

The effect of phenethyl alcohol on DNA synthesis was examined using several in vitro systems of Escherichia coli H560; i.e., ether-treated cells, membrane fractions and folded chromosomes fortified with DNA polymerase. In all systems, the incorporation of deoxyribonucleotides was much reduced for the phenethyl alcohol-treated cells compared with the non-treated cells. The total activity of DNA polymerases in polA1 cells (mostly DNA polymerase II) was not impaired for the phenethyl alcohol-treated cells and the reduction of the rate of DNA synthesis in vitro was ascribed to the reduction of the chromosomal template activity which was related to trypsin sensitive protein components. The analysis of chromosomes from the phenethyl alcohol-treated cells revealed the remarkable reduction of a protein component of molecular weight approx. 58 000 in contrast with a protein component of molecular weight approx. 30 000.

Solubilization of 6-oxybenzo(a)pyrene radical by caffeine and DNA as studied by magnetic resonance. Observation of intermolecular charge transfer.

Crystals of 6-oxybenzo(a)pyrene free radical, formed chemically from the hydroxy derivative of the carcinogen benzo(a)pyrene, can be solubilized in aqueous solutions of DNA and of caffeine. ESR spectral evidence indicate that the radicals exist as dispersed monomers associated with DNA and with caffeine. Comparison of NMR spin-lattice and spin-spin relaxation times in the protons of caffeine has given direct evidence that a part of the unpaired electron (at least 10(-4)) is transferred from the radical to the associated caffeine molecule. Simple consideration of Mulliken's charge transfer theory, however, leads to the conclusion that the intermolecular charge transfer is not likely to be a major source of stabilization energy of the complex.

Associations of menstrual pain with intakes of soy, fat and dietary fiber in Japanese women.

OBJECTIVE: Intakes of soy, fat, and dietary fiber may be associated with the symptoms of dysmenorrhea through their biological effects on estrogens or prostaglandin production. The present study was to examine the relationships between intakes of soy, fat, and dietary fiber and the severity of menstrual pain. DESIGN: Cross-sectional study. SETTING: Three colleges and two nursing schools. SUBJECTS: A total of 276 Japanese women aged 19-24 y. METHODS: Intakes of nutrients and foods including soy products, isoflavones, fats and dietary fiber were estimated by a validated semiquantitative food frequency questionnaire. Severity of menstrual pain was assessed by the multidimensional scoring system reported by Andersch and Milson. RESULTS: Intake of dietary fiber was significantly inversely correlated with the menstrual pain scale (r=-0.12, P=0.04) after controlling for age, smoking status, age at menarche and total energy intake. Neither soy nor fat intake was significantly correlated with menstrual pain after controlling for the covariates. CONCLUSIONS: The cross-sectional difference in dietary fiber intake across the level of menstrual pain was small in magnitude but warrants further studies.

Active and passive exposure to tobacco smoke in relation to insulin sensitivity and pancreatic ß-cell function in Japanese subjects.

AIM: Several studies have suggested that cigarette-smoking affects insulin sensitivity in Western populations. The present study evaluated glucose tolerance, pancreatic ß-cell function and insulin sensitivity in relation to active and passive smoking among the Japanese. METHODS: A total of 411 men and 586 women were recruited into a community-based cross-sectional study in Gifu, Japan. Diabetes, impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) were screened for by a 75g oral glucose tolerance test. HOMA and insulinogenic (ΔI0-30/ΔG0-30) indexes were used to estimate insulin secretion and sensitivity. To assess the possible association of self-reported smoking status and parameters of glucose metabolism, logistic regression was applied after adjusting for potential confounders. RESULTS: Currently smoking women were more likely to have diabetes, IGT or IFG compared with never-smoking women (OR: 2.26, 95% CI: 1.05-4.84). Heavy-smoking men (≥25 cigarettes/day) were likely to be in the lowest tertile group of ΔI0-30/ΔG0-30 compared with never-smoking men (OR: 2.64, 95% CI: 1.05-6.68, Ptrend=0.04). The number of cigarettes/day was borderline significantly associated with diabetes in men. Also with borderline significance, never-smoking women with smoking husbands were more likely to have diabetes, IGT or IFG (OR: 1.62, 95% CI: 1.00-2.62) and significantly more likely to have lower HOMA-ß (OR: 2.17, 95% CI: 1.36-3.48) than those without smoking husbands. CONCLUSION: The greater the number of cigarettes smoked per day appears to be associated with diabetes among men whereas, among women, both active and passive smoking appear to be associated with diabetic states, including IGT and IFG. An association between smoking status and insulin secretion is also suggested, whereas no significant association was observed with HOMA-IR in this Japanese subjects, suggesting that the influence of smoking on glucose metabolism may differ among races.

Effect of soymilk consumption on serum estrogen and androgen concentrations in Japanese men.

Soy consumption has been associated with a reduced risk of prostate cancer. The mechanism for this association may involve the effect of soy on the endocrine system. We conducted a randomized dietary intervention study to determine the effects of soy consumption on serum levels of steroid hormones in men. Thirty-five men were randomly assigned to either a soymilk-supplemented group or a control group. The men in the soy-supplemented group were asked to consume 400 ml of soymilk daily for 8 weeks. The men in the control group maintained their usual diet. Blood samples were obtained just before the initiation of the dietary period and thereafter every two weeks for 12 weeks. Changes in hormone concentrations were analyzed and compared between the two groups using the mixed linear regression model against weeks from the start of the dietary period. The mean (SD) soymilk intake estimated from dietary records during the dietary study period was 342.9 (SD, 74.2) ml in the soymilk-supplemented group. There was a significant difference between the two groups in terms of changes in serum estrone concentrations, which tended to decrease in the soy-supplemented group and increase in the control group over time. None of the other hormones measured (estradiol, total and free-testosterone, or sex hormone-binding globulin) showed any statistical difference between the two groups in terms of patterns of change. The results of the study indicate that soymilk consumption may modify circulating estrone concentrations in men.

Molecular orbital study on the reaction mechanism of irreversible enzyme inhibitors.

By means of the molecular orbital method, the reaction mechanism of the specific and irreversible enzyme inhibitors, such as cycloserine, L-2-amino-4-methoxy-trans-3-butenoic acid (AMB), and vinylglycine (2-amino-3-butenoic acid), was studied. Firstly, it was attempted to know which pathway is probable between the transamination process and the isomerization one. By comparing the energy increments for these two reactions, the transamination reaction was predicted to be energetically favorable, supporting the proposition of Rando. Upon complexing with the coenzyme-pyridoxal moiety of alanine racemase or aminotransferase, the reactivity of the inhibitors toward the nucleophile was found to be considerably increased due to the lowering of the lowest unoccupied molecular orbital (LUMO), and this was considered to be the reason why the inhibitors become bound with the enzyme irreversibly. The LUMO of aspartate, substrate of aspartate aminotransferase, is higher than those of the inhibitors in the free state, as well as in the pyridoxal-linked state. This difference in the energy of the molecular orbital between substrate and inhibitors was considered to be correlated with the difference in the complex-forming properties of these compounds toward the nucleophile in the enzyme.

Direct evidence of incorporation of 12-O-[20-2H1]tetradecanoylphorbol-13-acetate into artificial membranes as determined by deuterium magnetic resonance.

In order to elucidate the manner of interaction of 12-O-tetradecanoylphorbol-13-acetate (TPA), 2H-NMR spectra of [20-2H1]TPA and 31P-NMR spectra were recorded in the presence of multibilayers of dimyristoylphosphatidylcholine (DMPC). Observation of several pairs of quadrupole splittings directly proves the TPA molecules are intercalated into the multibilayers. Further, reduction of the 31P chemical shift anisotropy of DMPC multibilayers by TPA is more pronounced than that of phorbol 12,13-diacetate (PDA) whose activity of tumor promotion is very weak.