Akihiko Suyama

Radiation Effects Research Foundation, Hirosima, Hiroshima, Japan

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Publications (13)30.32 Total impact

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    ABSTRACT: We conducted an epidemiological study of the relationship between lung cancer incidence and smoking, with special reference to the benefits of smoking cessation for reducing lung cancer incidence, to promote a local smoking control program. The study was a retrospective cohort study. The population studied was 16,383 male examinees of lung cancer health examinations in 1995 in Tottori Prefecture, Japan. Smoking status from the questionnaire during the health examination was used as the exposure variable. Endpoint (lung cancer incidence) was obtained from the Tottori population-based cancer registry. A multivariable analysis using the Cox proportional hazard model was adapted for statistical analysis. The average follow-up period was 4.3 years. The hazard ratio of current smokers for the incidence of lung cancer was 4.9, whereas that of ex-smokers was 2.2. The dose-response relationship between lung cancer incidence and lifetime cigarette consumption (pack year) was determined. The ratio increased among younger subjects (under 65 years old). The hazard ratio of ex-smokers decreased with years just after quitting smoking, and reached the level of never smokers after 10-19 years from smoking cessation. We reconfirmed that the magnitude of risk estimates of smoking for lung cancer incidence was similar to those of previous studies, and smoking cessation was effective for reducing lung cancer risk.
    Full-text · Article · Jul 2007 · Environmental Health and Preventive Medicine
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    ABSTRACT: Many recent case-control studies have suggested a significant relationship between M235T (the substitution of threonine for methionine at position 235 codon) polymorphism of the angiotensinogen (AGT) gene and hypertension. To investigate whether the M235T polymorphism of AGT gene affects the incidence of hypertension, a retrospective cohort study was performed among Japanese workers. The subjects were Japanese workers at an occupational site in Shimane Prefecture in Japan. The baseline data were set at the received regular health examination in 1992, and a retrospective cohort study was performed for analyzing the incidence of hypertension in 1998. The rates of M235M (MM), M235T (MT) and T235T (TT) genotypes were 4%, 32% and 64%, respectively. The relative risks of MT and TT against MM for the incidence of hypertension by single variance analysis were 1.47 [95% confidence interval (CI) 0.50 - 4.33] and 1.35 (95% CI 0.47 - 3.90), respectively. The relative risks of MT and TT against MM for the incidence of hypertension, adjusted for sex, age, body mass index, fasting glucose and cigarette smoking, drinking and exercise in 1992, were 1.49 (95% CI 0.49 - 4.53) and 1.25 (95% CI 0.42 3.74), respectively. The data from this study suggest that the M235T polymorphism of AGT gene has a weak role in the manifestation of hypertension. Further comprehensive studies are needed to resolve this issue.
    No preview · Article · Jun 2001 · Journal of Epidemiology
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    ABSTRACT: In order to investigate whether the Trp64Arg (a missense mutation of tryptophan for arginine at position 64 codon) polymorphism of the β3-adrenergic receptor (β3-AR) gene is related to the incidence of non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance (IGT), a retrospective cohort study among Japanese workers was conducted. The subjects were Japanese workers at an occupational site in Shimane Prefecture. Informed consent was obtained from 492 workers. The baseline data were obtained at the regular health examination in 1992 and a retrospective cohort study was performed for analyzing the incidence of NIDDM and IGT in 1998. The Trp64Arg polymorphism β3-AR gene for each worker was detected by the single strand conformation polymerase analysis. Relative risks were calculated by the logistic regression analysis. The rates of Trp64Trp (TT), Trp64Arg (TA) and Arg64Arg (AA) genotypes were 66.3%, 31.1% and 2.6%, respectively. The relative risk of (TA + AA) against TT for the incidence of NIDDM and IGT by univariate analysis was 1.37 (95% confidence interval, 0.69-2.72). The relative risk of (TA + AA) against TT for the incidence of NIDDM and IGT adjusted for confounders in a multiple logistic regression model including age, gender, family history, body mass index, alcohol consumption, eating habits and exercise was 1.31 (95% confidence interval, 0.65-2.67). The present findings suggested that a weak association between Trp64Arg polymorphism of the β3-
    Full-text · Article · Jan 2001
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    ABSTRACT: In order to examine the distribution of M235T (the substitution of threonine for methionine at position 235 codon) polymorphism genotypes of the angiotensinogen (AGT) gene and the relationship between M235T polymorphism of the AGT gene and hypertension, a descriptive study and a case-control study were performed among Japanese workers. The subjects were 2042 workers at an occupational site in Shimane Prefecture in Japan. The database was set up for the workers' regular health exami- nation in 1998. The M235T polymorphism of the AGT gene for each worker was defined by the mutant allele specific amplification (MASA) method. The rates of M235M (MM), M235T (MT) and T235T (TT) genotypes were 3.9%, 30.7% and 65.5%, respectively. The odds ratios of MT and TT against MM for hypertension by univariate analysis were 0.77 (95% confidence interval (CI) 0.27-2.18) and 0.77 (95% CI 0.28-2.14), respec- tively. The odds ratios of MT and TT against MM for hypertension, adjusted for body mass index, fasting blood sugar, drinking habits, cigarette smoking and exercise in a logistic regression model, were 0.90 (95% CI 0.29-2.74) and 0.87 (95% CI 0.30-2.58), respectively. The data from this study suggests that there may be no relationship between the M235T polymorphism of the AGT gene and hypertension. Further prospective studies are needed to resolve this issue.
    No preview · Article · Jan 2001
  • Fengzhu Tan · Mikizo Okamoto · Akihiko Suyama · Tetsuya Miyamoto
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    ABSTRACT: A cohort study was conducted to explore the tracking stability of cardiovascular risk factors and relative risk (RR) of factors relating hyperlipidemia in children. The percentages of children remaining persistently at high risk over a four-year tracking were as follows: body mass index (BMI) 65.0%, total cholesterol (T-c) 60.6%, atherogenic index (AI) 56.4%, high density lipoprotein cholesterol (HDL-c) 50.7%, systolic blood pressure (SBP) 44.2% and diastolic blood pressure (DPB) 39.6%. The order of correlation coefficients over four years was BMI > AI > HDL-c > T-c > SBP > DBP and these coefficients in boys were slightly higher than those in girls. The relative risk (RR) of BMI for AI > or = 3 was elevated (RR=4.36, 95% CI: 1.3-14.1). The incidence and RR for AI > or = 3 increased along with the addition of the selected risk factor number. The RR in children with three selected risk factors rose to 8.39 ( 95% CI: 1.2-38.7 ). The stability of tracking was better for BMI, T-c, AI and HDL-c. As the number of multiple factors increased, so did the RR of higher AI in childhood. These results suggest that preventive activities for hyperlipidemia should be focused on children with multiple cardiovascular risk factors.
    No preview · Article · Aug 2000 · Journal of Epidemiology
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    ABSTRACT: In order to evaluate the characteristics of fatigue symptoms and their association with the life style and the health status, we examined using data accumulated by the longitudinal surveys from 1992 to 1998, in 118 six-year primary school children and 129 second-year junior high school children. The complaints of "drowsiness and dullness", such as "become drowsy" (71%), "give a yawn" (59%) and "want to lie down" (51%), respectively, were most frequently observed. The proportion of these complaints was high before the first morning class, but decreased when the children leave school. Notably, the complaints of "difficulty in concentration" annually have increased. Children with undesirable eating habits, particularly those who often eat salty foods, or poor life style, such as staying up late at night tended to have more complaints of fatigue symptoms. By correlation analysis, these complaints were significantly related to the obesity degree, blood pressure, HDL cholesterol and atherogenic index. These results support the hypothesis that fatigue symptoms increase or are associated with life style and health status. Consequently, it is necessary to improve the life style such as dietary habits and rhythm of life for the reduction of fatigue symptom.
    No preview · Article · Aug 2000 · Journal of Epidemiology
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    ABSTRACT: The spread of human immunodeficiency virus (HIV) in Cambodia is mainly caused by sexual transmission and the high-risk group in this country are female commercial sex workers (CSW). There are two types of CSW, direct CSW (DCSW) and indirect CSW (IDCSW), who are different from each other in sexual activities. This study was conducted in order to describe the risk factors on HIV for each type of CSW, and to establish effective preventive strategies against the HIV epidemic among CSW. The participants, 143 DCSW and 94 IDCSW, were interviewed using a questionnaire to determine their demographic characteristics and behaviour. Blood samples were taken for serological tests on HIV, Chlamydia trachomatis and syphilis. The association between their behavioural pattern and their serological results was analysed. The questionnaire study showed that IDCSW had a riskier behavioural pattern than DCSW. The HIV seroprevalence rates of the DCSW and the IDCSW were 52.4% and 22.3%, respectively. Univariate logistic analyses showed a significant association between HIV antibody (HIV-Ab) and current age, age at commencement of commercial sex work, duration of commercial sex work, and the seropositivity of Chlamydia trachomatis-IgG antibody (CT-IgG-Ab) among the DCSW. The analyses also showed a significant relationship between HIV-Ab and CT-IgG-Ab among the IDCSW. Improving condom use rate is very important in order to prevent an HIV epidemic among the two types of CSW. This study also suggests it is important to prevent sexually transmitted disease (STD) such as Chlamydia trachomatis infection. The STD control programme could be efficient for HIV prevention, especially among DCSW.
    Full-text · Article · May 2000 · International Journal of Epidemiology
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    ABSTRACT: To describe epidemiological features on HIV prevalence among female commercial sex workers (CSWs), a cross-sectional study on sexual behaviour and serological prevalence was carried out in Cambodia. The CSWs were interviewed on their demographic characters and behaviour and their blood samples were taken for testing on sexually transmitted diseases, including HIV, Chlamydia trachomatis, syphilis, and hepatitis B. Associations between risk factors and HIV seropositivity were analysed. High seroprevalence of HIV and Chlamydia trachomatis IgG antibody (CT-IgG-Ab) was shown among the CSWs (54 and 81.7%, respectively). Univariate logistic regression analyses showed an association between HIV seropositivity and age, duration of prostitution, the number of clients per day and CT-IgG-Ab. Especially, high-titre chlamydial seropositivity showed a strong significant association with HIV prevalence. In multiple logistic regression analyses, CT-IgG-Ab with higher titre was significantly independently related to HIV infection. These suggest that existence of Chlamydia trachomatis is highly related to HIV prevalence.
    Full-text · Article · Mar 2000 · Epidemiology and Infection
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    ABSTRACT: This study surveyed the sexual behaviour of commercial sex workers and their clients in an attempt to identify factors of transmission of STDs (including HIV/AIDS) and to control their epidemics in Cambodia and South-East Asia. Cross-sectional study. Trained questioners asked items of the questionnaires to each objective subject in December 1996. Data were analysed to show the descriptive status by risk group of each person. 200 direct commercial sex workers, 220 indirect commercial sex workers, and 211 clients in Phnom Penh. Prostitution was widely accepted by both young males and females, and this was an easy way for young girls to obtain money. Although commercial sex workers and clients were knowledgeable about prevention methods against STDs, they seldom used condoms. Some commercial sex workers had been infected with STDs many times, and many of them incompletely treated the diseases by themselves. Social support from governmental and non-governmental organisation was poor. It is very important to support both commercial sex workers in practicing preventive methods against STDs and also visiting physicians when they notice symptoms of STDs. It is strongly recommended that not only governmental but also non-governmental organisations should be more active in this area.
    No preview · Article · Jul 1999 · Journal of Epidemiology
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    ABSTRACT: To describe epidemiological features of HIV prevalence among female commercial sex workers (CSWs) in Cambodia, a cross-sectional study using a questionnaire study and serological tests was carried out from December 1997 to January 1998. We report the main results of the analyses of serological tests in this article. Two hundred ninety six CSWs working in Sisophon and Poi Pet, located in northwest Cambodia, Bantey Mean Chey province, were recruited for interview based on a questionnaire on sexual behavior, and serological tests. The blood samples were examined for HIV antibody, Chlamydia trachomatis IgG antibody, TPHA, Hepatitis B surface antigen, and Hepatitis B surface antibody. The relationship between HIV and the other STD's was analyzed by using logistic regression analysis. The HIV seroprevalence rate was 43.9% (130 out of 296). The seropositive rate of Chlamydia trachomatis IgG antibody (C.T.-IgG-Ab) was 73.3% (217 out of 296). Logistic regression analysis showed a significant association between C.T.-IgG-Ab positive and HIV prevalence. (Odds Ratio: 5.33; 95% Confidence Interval, 2.82-10.07). This study suggests that the existence of Chlamydia trachomatis is closely related with HIV prevalence among CSWs in Cambodia. Other STDs may also increase susceptibility to male-to-female sexual transmission of HIV. This suggests that appropriate prevention against STDs will be needed for the control of HIV prevalence in Cambodia.
    No preview · Article · Feb 1999 · [Nippon kōshū eisei zasshi] Japanese journal of public health

  • No preview · Article · Jan 1999 · Journal of Epidemiology
  • S Morio · J Sugihara · N Okamoto · A Suyama · M Okamoto · H Nakayama
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    ABSTRACT: Physical examinations and a questionnaire survey of life style were carried out on all pupils (105 boys and 110 girls) at the first grade of primary school in Saigo town, Fuse village, Goka village, and Tsuma village of Shimane prefecture in 1992. In 1994, physical examinations and a questionnaire survey were again performed along with a newly-added blood examination on the same cohort. Parents of the pupils answered the questionnaire. The pupils who were included in both the first (in 1992) and the second (in 1994) examinations and surveys (89 boys and 101 girls, but 71 boys and 77 girls for blood examination) were subjects in this study to analyse the relationship between obesity and life style. The results showed (a) the proportional rates of obese boys and girls increased during the two years; (b) the obesity index of boys and girls in the third grades correlated with the obesity index of their mothers; (c) obese boys ate snacks frequently, had a higher speed in eating, and disliked physical exercise; and (d) the obesity index of boys and girls correlated with serum total cholesterol. These findings indicate that obesity occurs as early as the lower grades of primary schools and that it continues for at least two years.
    No preview · Article · Apr 1996 · [Nippon kōshū eisei zasshi] Japanese journal of public health
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    S Morio · N Okamoto · A Kawamoto · A Suyama · M Okamoto · H Nakayama
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    ABSTRACT: To evaluate new national influenza vaccination practices which were started in 1987 under a revised law in Japan. This was a three year, nonrandomised cohort study with information collected by questionnaire between 1989 and 1991. Eight primary schools in the city of Yonago, Tottori, Japan. These schools were selected from 23 schools in the city. Altogether 4251 pupils (1355 boys and 2896 girls) in years 1-4 of the eight primary schools were included in this study, and followed up. Three years later, data for 1619 pupils (768 boys and 851 girls) were obtained and analysed. The one-winter seasonal incidence rates of influenza-like disease were 13.4%, 29.9%, and 10.3% in 1989, 1990, and 1991 respectively. The incidence rate of influenza-like disease in fully vaccinated pupils was significantly lower than that in unvaccinated pupils in 1990, but not in 1989 or 1991. Stepwise multiple regression analysis showed that the incidence of influenza-like disease had a statistical relationship with the frequency of vaccination and the school year (R2 was 0.0148). Standardised parameters of the frequency of vaccination and the school frequency of vaccination and the school year were -0.089 and -0.080 respectively. The preventive effects of influenza vaccine are not strong. There must be some unknown factors that affect the incidence of influenza. This vaccine is useful for pupils in the early school years who seem to have less resistance. All pupils should not be inoculated with the vaccine to reduce influenza transmission in the community or school.
    Preview · Article · Mar 1994 · Journal of Epidemiology & Community Health