Our meta-analysis supports that depression is probably an independent risk factor of hypertension. It is important to take depression into consideration during the process of prevention and treatment of hypertension. Further studies are needed to exclude the effects of other confounding factors.

To assess whether habitual sleep duration or insomnia increase the incidence of hypertension. PubMed, EMBASE and Cochrane were searched without language restriction. Prospective cohort studies of adults with at least a 1-year follow-up duration were included. Habitual sleep duration or symptoms of insomnia were assessed as baseline exposure, and the outcome was incidence of hypertension. Subgroup, meta-regression and sensitivity analyses were conducted to assess heterogeneity, and Egger's test was used to assess publication bias. Eleven studies (17 cohorts) were included. Short sleep duration, sleep continuity disturbance (SCD), early-morning awakening (EMA) and combined symptoms of insomnia increased the risk of hypertension incidence (the relative risks (95% confidence intervals) were 1.21 (1.05–1.40) for short sleep duration, 1.20 (1.06–1.36) for SCD, 1.14 (1.07–1.20) for EMA and 1.05 (1.01–1.08) for combined insomnia symptoms). Less evidence exists to support conclusions about the association between long sleep duration or difficulty falling asleep (DFA) and hypertension incidence. No obvious heterogeneity or publication biases were found. Our meta-analysis demonstrates that short sleep duration and single/combined symptoms of insomnia (except DFA) are associated with an increased risk of hypertension incidence. It is important to consider sleep duration and insomnia during hypertension prevention and treatment. More laboratory studies on potential mechanisms and prospective observational studies with objective measures of sleep are needed.

Stem cell genetics research may be critical to our understanding of carcinogenesis, as both stem cells and cancer cells possess the ability to self-renew. Recent discoveries have indicated that the piwi family of genes plays an essential role in stem cell selfrenewal in diverse organisms. The hiwi gene, the human homolog of the piwi family, participates in germ cell proliferation and its overexpression may cause the development of germ cell malignancy, but its expression and function in epithelial solid cancers have not been explored. In the present study, we investigated whether there was an association between hiwi expression and human gastric cancer and its potential mechanism. RT-PCR findings demonstrated that hiwi was expressed in different gastric cancer cell lines. To identify the HIWI protein in gastric cancer, we developed a specific monoclonal antibody against HIWI and immunohistochemistry was performed on various gastric tissues. We found that the expression ratio of hiwi in normal gastric tissues, atrophic gastritis, intestinal metaplasia and gastric cancers was 10% (5/50), 36% (18/50), 36% (18/50) and 76% (38/50), respectively, which was consistent with precancerous development. Notably, the expression pattern of hiwi in gastric cancer tissues was similar to that of Ki67, which was used as a marker of proliferation. Moreover, the suppression of hiwi by antisense or RNAi inhibited the growth of gastric cancer cells and induced cell cycle arrest in G 2 /M phase. These results suggest that hiwi may be involved in the development of gastric cancer and is a potential target for cancer therapy. ' 2005 Wiley-Liss, Inc.Key words: hiwi; expression; gastric cancer; proliferation Although there is a high incidence of gastric cancer in Asia and gastric cancer remains one of the leading causes of cancer-related death worldwide, 1 the molecular mechanisms underlying its development are poorly understood. Stem cell research will greatly expand our understanding of the mechanisms of carcinogenesis because the homeostatic mechanisms mediating stem cell proliferation are the same processes that become dysregulated in carcinogenesis.2,3 Therefore, the study of stem cell genes may be critical to furthering our understanding of carcinogenesis and to the development of novel strategies for preventing and managing cancer. 4 Because of this, there is a growing interest in studying the roles of genes, which were initially found to be involved in stem cell selfrenewal, in the development of cancer. 5-7The hiwi gene is a human member of the piwi family, which represents the first class of genes known to be required for stem cell self-renewal in diverse organisms.8 Recent discoveries have shown that hiwi may participate in germ cell proliferation and its overexpression may cause germ cell malignancy development. 9These findings raise the hypothesis that hiwi may be present in other types of stem cells and likewise may be involved in the development of cancers.The hiwi gene, located in 12q24.33, was originally isolated from a h...