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Abstract-Effects of smoking on white matter lesions, such as lacunar infarction and leukoaraiosis, are still controversial.We hypothesized that the endothelial NO synthase (eNOS) genotype was a modulating factor for the effect of smoking on cerebral circulation. We took a cross-sectional population from the participants of a health examination to study the effects of smoking and a single-nucleotide polymorphism in the eNOS gene, T-786C. Smokers and nonsmokers were defined as having a smoking index (cigarettes per day times years) of Ն200 and 0, respectively. One hundred sixty-six male nonsmokers and 344 male smokers were recruited. Cerebral blood flow was measured by the 133 Xe inhalation method. Genotyping of T-786C was performed by using a newly developed allele-specific polymerase chain reaction. Smokers were exposed to greater oxidative stress, as estimated by urinary F 2 -isoprostane excretion. In smokers, CC homozygotes of T-786C showed a significant decrease of cerebral blood flow (56.6Ϯ13.3, 57.6Ϯ11.5, and 44.0Ϯ7.2 mL/min per 100 g tissue for TT, TC, and CC, respectively; Pϭ0.03 by ANOVA) and a significant increase of cerebrovascular resistance, whereas the eNOS genotype did not affect these parameters in nonsmokers. This result indicated that the eNOS genotype could modify cerebrovascular circulation in a general population by potentiating the adverse effect of smoking. Key Words: nitric oxide synthase Ⅲ polymorphism Ⅲ cross-sectional studies Ⅲ cerebral circulation S moking is an established risk factor for cardiovascular diseases. However, the adverse effect of smoking is controversial in some areas of cerebrovascular disease, such as lacunar infarction and white matter changes. 1-7 Such inconsistency may imply the importance of other environmental or genetic factors in modifying the effects of smoking. Because lacunar infarction and white matter changes are based on occlusive changes in small arteries perforating into the white matter and are characterized by decreased cerebral blood flow (CBF) and increased cerebrovascular resistance (CVR), the endothelial NO synthase (eNOS) gene is a good candidate for such a factor; eNOS constitutively produces NO, a potent vasodilator as well as an antitrophic factor for the arterial wall. 8 -11 Several reports have indicated that eNOS plays an essential role in the regulation of basal CBF in humans and in mice. 9,10 Furthermore, because smoking antagonizes the action of NO through the induction of oxidative stress, 12 it is logical to hypothesize that genetic alteration of eNOS activity may be a modifier of the effect of smoking on the cerebral circulation.Recently, the eNOS gene was studied extensively for genetic polymorphisms to elucidate its genetic role in cardiovascular diseases. As a result, a single-nucleotide polymorphism (SNP) in the promoter region, T-786C, was found to modify the promoter activity in vitro. 13 In addition, this SNP and a 27-bp repeat polymorphism in intron 4, called ecNOS4 a/b, were reported to influence eNOS mRNA and protein levels ...

CMF1 protein is expressed in developing striated muscle before the expression of contractile proteins, and depletion of CMF1 in myoblasts results in inability to express muscle-specific proteins. Previous studies of CMF1 identify a functional Rb-binding domain, which is conserved in the murine and human homologues. Here, we show that CMF1 binds Rb family members, while a CMF1 protein with deletion of the Rb-binding domain (Rb-del CMF1) does not. Myogenic cell lines over-expressing Rb-del CMF1 proliferate normally, but exhibit markedly impaired differentiation, including dramatically reduced contractile proteins gene expression and failure to fuse into myotubes. Furthermore, by quantitative real-time polymerase chain reaction, MyoD and Myf5 mRNA levels are comparable to wild-type, while myogenin and contractile protein mRNA levels are significantly attenuated. These data demonstrate that CMF1 regulates myocyte differentiation by interaction with Rb family members to induce expression of myogenic regulatory factors.