Stereoselectivity of benzo[a]pyrene diol epoxides by DNA for adduct formation with N2 on guanine.
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Biomedical subjects
Publications and source records attributed to E R Taylor.
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A theoretical model is proposed for the covalent binding of (+) 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene denoted by BPDE I(+), to N2 on guanine. The DNA must kink a minimum of 39 degrees to allow proper hybrid configurations about the C10 and N2 atoms involved in bond formation and to allow stacking of the pyrene moiety with the non-bonded adjacent base pair. Conservative (same sugar puckers and glycosidic angles as in B-DNA) and non-conservative (alternating sugar puckers as in intercalation sites) conformations are found and they are proposed structures in pathways connecting B-DNA, an intercalation site, and a kink site in the formation of a covalently intercalative bound adduct of BPDE I(+) to N2 on guanine. Stereographic projections are presented for (3') and (5') binding in the DNA. Experimental data for bending of DNA by BPDE, orientation of BPDE in DNA and unwinding of superhelical DNA is explained. The structure of a covalent intercalative complex is predicted to result from the reaction. Also, an anti----syn transition of guanine results in a structure which allows the DNA to resume its overall B-form. The only change is that guanine has been rotated by 200 degrees about its glycosidic bond so that the BPDE I(+) is bound in the major groove. The latter step may allow the DNA to be stored with an adduct which may produce an error in the genetic code.
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We examined the effects of physical exercise on smoking relapse. Twenty previously sedentary female smokers were randomly assigned to smoking cessation plus exercise or smoking cessation with frequency contact control. The smoking cessation program included 12 professionally led sessions over 12 weeks. Exercise treatment included three supervised exercise sessions per week for 15 weeks. Contact control included three women's health/wellness lectures per week for 15 weeks. Smoking abstinence was validated by carbon monoxide and saliva cotinine. Mean exercise attendance for exercise subjects was 88% with an increase in estimated VO2 of 25%. The percentage of subjects who quit for 24 hours was 80% for the exercise and 90% for the contact group. One subject in the contact group remained abstinent at the end of the 12-week treatment and at 1-, 3-, and 12-month follow-ups, whereas three subjects in the exercise group were abstinent at these time points. These results suggest that exercise training improves short-term quit rates and may prove a useful strategy for long-term maintenance of smoking cessation.
PURPOSE: This study compares the efficacy of a self-help intervention tailored to the individual's stage of motivational readiness for exercise adoption with a standard self-help exercise promotion intervention. DESIGN: Interventions were delivered at baseline and 1 month; assessments were collected at baseline and 3 months. SETTING: Eleven worksites participating in the Working Healthy Research Trial. SUBJECTS: Participants (n = 1559) were a subsample of employees at participating worksites, individually randomized to one of two treatment conditions. INTERVENTION: Printed self-help exercise promotion materials either (1) matched to the individual's stage of motivational readiness for exercise adoption (motivationally tailored), or (2) standard materials (standard). MEASURES: Measures of stage of motivational readiness for exercise and items from the 7-Day Physical Activity Recall. RESULTS: Among intervention completers (n = 903), chi-square analyses showed that, compared to the standard intervention, those receiving the motivationally tailored intervention were significantly more likely to show increases (37% vs. 27%) and less likely to show either no change (52% vs. 58%) or regression (11% vs. 15%) in stage of motivational readiness. Multivariate analyses of variance showed that changes in stage of motivational readiness were significantly associated with changes in self-reported time spent in exercise. CONCLUSIONS: This is the first prospective, randomized, controlled trial demonstrating the efficacy of a brief motivationally tailored intervention compared to a standard self-help intervention for exercise adoption. These findings appear to support treatment approaches that tailor interventions to the individual's stage of motivational readiness for exercise adoption.
PURPOSE: This study examines the utility of three theoretical models--the stages of change model, self-efficacy theory, and the decisional balance model--in understanding exercise behavior among employed women. DESIGN: Data for this cross-sectional study were collected as part of a routine follow-up of a worksite-based smoking and health risk appraisal study. SETTING: The study was conducted in three Rhode Island worksites, including one manufacturing company, one medical center, and one retail outlet. SUBJECTS: Of a sample of 431 women who completed exercise questionnaires, 293 reported participation in a physical activity over the previous week. The average age of the sample was 41.1 years, and mean years of education was 12.8. MEASURES: Previously validated measures to determine stage of exercise behavior, exercise self-efficacy, exercise decisional balance, and physical activity participation were administered. Additional demographic information was also obtained. RESULTS: Frequency counts revealed that 39% of the population was sedentary, 34% were participating in irregular activity, and 27% were active. MANOVAs followed by one way ANOVAs revealed that women in Precontemplation scored the lowest and those in Maintenance scored the highest on the self-efficacy, pro, and decisional-balance indices, with the trend reversed on the con scale. A chi-square test revealed that women with one or more young children in the home were more likely to be in a lower stage of exercise adoption. CONCLUSIONS: Most of the women in this cross-sectional study did not engage in regular activity. Presence of young children in the home was significantly related to decreased activity.(ABSTRACT TRUNCATED AT 250 WORDS)