ObjectiveA positive association between the number of cigarettes smoked per day and obesity has been reported, whereas how other smoking-related indices, such as pack-years and duration of smoking, are related with obesity has been less investigated. We analyzed the age-adjusted cross-sectional association between smoking and obesity in a general Japanese population.MethodsWe used data from a nationwide epidemiological study of Japanese adults (N = 23,106). We compared the prevalence of obesity (defined as body mass index ≥ 25kg/m2) among groups classified by smoking behavior, pack-years, number of cigarettes per day, duration of smoking, and duration and time of smoking cessation.ResultsIn men, current smokers had a lower odds ratio (OR) for obesity of 0.80 (95% confidence interval (CI): 0.72–0.88) compared to non-smokers, whereas past smokers had a higher OR of 1.23 (95% CI: 1.09–1.37) compared to current smokers. In women, there were no differences in obesity between the three groups classified by smoking behavior. However, in both sexes, the prevalence of obesity tended to increase with pack-years and the number of cigarettes per day, but not with duration of smoking in current and past smokers. Further, in male smokers, the risks for obesity were markedly higher in short-term heavy smokers compared with long-term light smokers, even with the same number of pack-years. Regarding the impact of smoking cessation, female past smokers who quit smoking at an age > 55-years had an elevated OR of 1.60 (95% CI:1.05–2.38) for obesity.ConclusionsIn a general Japanese population, obesity is progressively associated with pack-years and number of cigarettes per day, but not with the duration of smoking. When investigating the association between obesity and cigarette smoking, the daily smoking burden and the duration of smoking require to be independently considered.

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BackgroundMannose receptor (MR) is a member of the C-type lectin receptor family involved in pathogen molecular-pattern recognition and thought to be critical in shaping host immune response. The aim of this study was to investigate potential associations of genetic variants in the MRC1 gene with sarcoidosis.MethodsNine single nucleotide polymorphisms (SNPs), encompassing the MRC1 gene, were genotyped in a total of 605 Japanese consisting of 181 sarcoidosis patients and 424 healthy controls.ResultsSuggestive evidence of association between rs691005 SNP and risk of sarcoidosis was observed independent of sex and age in a recessive model (P = 0.001).ConclusionsThese results suggest that MRC1 is an important candidate gene for sarcoidosis. This is the first study to imply that genetic variants in MRC1, a major member of the C-type lectin, contribute to the development of sarcoidosis.

Mannose receptor is a member of the C-type lectin receptor family involved in pathogen molecular pattern recognition and thought to be critical in shaping host immune responses and maintaining homeostasis. The aim of this study was to investigate potential associations of genetic variants in the MRC1 gene with asthma in two independent populations. Seven single-nucleotide polymorphisms (SNPs; rs2477637, rs2253120, rs2477631, rs2477664, rs692527, rs1926736, and rs691005) in the MRC1 gene locus were genotyped and evaluated regarding association with asthma in 870 unrelated Japanese subjects (446 asthmatics, 424 controls). The same markers were validated in 176 unrelated African-American subjects (86 asthmatics, 90 controls). Suggestive evidence of association between five SNPs (rs2477637, rs2253120, rs2477664, rs692527, and rs1926736) and asthma was observed in the analysis of the Japanese population independent of sex, age, smoking status, and atopic status. SNPs rs692527 and rs691005 showed significant association with asthma in the African-American population. Haplotypes containing two linked SNPs (rs692527 and rs1926736) were significantly associated with asthma in both Japanese and African-American populations. Our results suggest that sequence variations in the MRC1 gene are associated with the development of asthma in two independent and ethnically diverse populations.

Asthma and allergic rhinitis often coexist and are increasing worldwide, particularly among the younger generation. Although the prevalences of adult asthma and allergic rhinitis and their risk factors have been reported, there have been few studies focusing on young adults. The aim of this study was to evaluate the prevalences of asthma and allergic rhinitis and their associated factors in Japanese young adults. A questionnaire survey of new students at Hokkaido University about the presence of current wheeze and rhinitis and a history of several viral infections during childhood was conducted in 2008 and 2010. The prevalences of wheeze and rhinitis and their associated factors were evaluated. Of 4076 nonsmoking subjects aged 18-25 years, 261 (6.4%) had current wheeze and 1373 (33.7%) had allergic rhinitis. On multivariate analyses, current wheeze was associated with high body mass index (BMI), atopic dermatitis, allergic rhinitis, food allergy, and a history of measles infection. In contrast, allergic rhinitis was associated with low BMI, current wheeze, atopic dermatitis, food allergy, and no history of measles. When subjects were classified into four groups by the presence or absence of wheeze and rhinitis, both high BMI and a history of measles were positively associated with wheeze without rhinitis but negatively associated with rhinitis without wheeze. High BMI and past measles infection showed contrasting associations with asthma and allergic rhinitis in nonsmoking young adults. It is important to not only recognize the common pathophysiological characteristics of asthma and allergic rhinitis but also to understand their differences.