Adolescent smoking behaviour and cigarette brand preference in Japan.

OBJECTIVES: As part of efforts to develop a smoking control strategy for Japanese adolescents, the results of two nationwide surveys on adolescent smoking behaviour were compared. DESIGN: Descriptive study on smoking behaviour among high school students was conducted. Self-reporting anonymous questionnaires were administered to 115,814 students in 1996 and 106,297 in 2000 through randomly sampled junior and senior high schools throughout Japan. MAIN OUTCOME MEASURES: Smoking prevalence, proportion of smokers by usual sources of cigarettes, national estimated cigarettes consumed by minors, share of cigarette brands smoked by high school students. RESULTS: The experiment rate among junior high school boys decreased in 2000 compared with that in 1996, whereas current and daily smoking rates did not. Although prevalence among Japanese girls was much lower than that among boys, prevalence among girls increased in 2000. The main source of cigarettes among high school smokers was vending machines. The proportion of smokers who usually purchased cigarettes from vending machines increased in 2000, in spite of the 1998 introduction of restrictions on night-time operations. Japanese adolescents were more likely than adults to smoke American cigarette brands, and the adolescent market share of American brands has increased rapidly, especially for menthol brands. CONCLUSIONS: This survey revealed the seriousness of the problem of smoking behaviour among Japanese high school students, and suggested that this behaviour may be influenced by social environmental factors, including the marketing strategies of the tobacco industry. Action should be taken to reduce the prevalence and impact of pro-tobacco marketing messages and to abolish cigarette vending machines.

Excretory/secretory products of plerocercoids of Spirometra erinaceieuropaei induce the expression of inducible nitric oxide synthase mRNA in murine hepatocytes.

In this study, we observed the level of normal murine hepatocyte inducible NOS (iNOS) mRNA by semi-quantitative polymerase chain reaction (SQ-PCR) analysis after stimulation with ES products (ESP) and/or ESP fractions from the plerocercoids. We found that ESP are able to induce the expression of iNOS gene in a dose-dependent fashion. Treatment of ESP with polymyxin B did not affect their ability to induce the expression of iNOS gene, suggesting that bacterial lipopolysaccharide (LPS) is not involved. The iNOS-inducing factor (a) is soluble, and may be a component whose molecular mass exceeds 94 kDa as analyzed by a combination of SDS-PAGE and SQ-PCR. The peak of iNOS mRNA level was detected 3 h after stimulation with ESP; the mRNA level decreased sharply from 9 h. Dexamethasone inhibited the induction of mRNA for hepatocyte iNOS. In contrast, cycloheximide stimulated the induction; this suggests that de nova protein synthesis is important in the regulation of the ESP-induced expression of iNOS mRNA. Actinomycin D blocked the induction. In addition, the results of Northern blot analysis showed that ESP suppressed the LPS (10 micrograms/ml) and interferon-gamma (IFN-gamma, 100 U/ml)-induced hepatocyte iNOS mRNA expression in a dose-dependent fashion and the suppressing effect was more marked when hepatocytes were exposed to ESP 3 h prior to LPS and IFN-gamma. These results demonstrate that the soluble factor(s) of ESP is capable of inducing murine iNOS gene expression in hepatocytes in the absence of added cytokines.

Excretory/secretory products from plerocercoids of Spirometra erinacei reduce iNOS and chemokine mRNA levels in peritoneal macrophages stimulated with cytokines and/or LPS.

During infection with plerocercoids of Spirometra erinacei, organisms in the peritoneal cavity of infected animals have many bound inflammatory leukocytes yet survive apparently unharmed. Coculture of IFN gamma and LPS stimulated mouse peritoneal macrophages with live plerocercoids suppressed the mRNA expression of the inducible isoform of nitric oxide synthase (iNOS) and JE, the murine homologue of monocyte chemotactic protein-1 (MCP-1). Excretory/secretory (ES) products from plerocercoids also suppressed the induced iNOS and JE mRNA and reduced nitrite production of macrophages in a dose dependent manner. The suppression of inducible mRNA levels in macrophages cultured for 24 h with ES products varied with the nature of the stimuli; IFN gamma/ LPS-induced iNOS mRNA levels were effected less than were iNOS mRNA levels induced by IFN gamma/IL-2 or IFN gamma/ TNF alpha. Similar findings were obtained when nitrite production was measured. Thus modulation of LPS and cytokine inducible mRNA levels appear to be the primary target of ES products. We speculate that a major physiological role for this inhibitory activity in ES products might be the down regulation of pro-inflammatory gene expression.