The intraday and interday precision of the method was 6.4% and 7.5%, respectively, with an accuracy of >95%. The limit of quantitation was 0.15 pmol/ml urine. Data Management Lenalidomide IC50 and Analysis Data were entered into a Microsoft Access database. Duplicate data entry was performed to ensure quality control. Descriptive data analysis was conducted to examine the ranges and distribution of continuous variables. Data were examined for normality using the Shapiro�CWilk normality test: NNAL values were skewed and were described as geometric means. Student��s t test (continuous variables) and chi-square test (categorical variables) were used to compare demographics and smoking behavior variables between cigarette and waterpipe smokers, and characteristics of exposure to ETS between nonsmoking females exposed either to cigarette or waterpipe smoke.

When the expected numbers were small (<5 subjects per cell), Fisher��s exact method was used. Mann�CWhitney and Kruskal�CWallis tests were used to evaluate the differences in the levels of NNAL in binary and categorical variables respectively. Spearman��s correlation coefficients were calculated to determine the association between levels of NNAL in nonsmoking females exposed to tobacco smoke and NNAL levels in their husbands and with the number of cigarettes/hagars they smoked in the past 24 hr. SPSS statistical software (release 15) was used for data analysis. All statistical tests were two sided, with 0.05 as the level of significance. Results A total of 51 subjects were recruited, of whom 46 were successfully assayed: 24 (52.

2%) were males and 22 (47.8%) were nonsmoker wives. The demographic characteristics and smoking profiles of participants are shown in Table 1. Of the 24 current male smokers, 13 (54.2%) were exclusive cigarette smokers, and 11 (45.8) were exclusive waterpipe smokers. Among nonsmoking females, 13 (59.1%) reported being exposed to cigarette smoke, and 9 (40.9%) reported exposure to waterpipe smoke. All interviewed subjects were married; the majority had received no formal education (62.5% in males and 72.7% in nonsmoking females). The mean age was 45.3 �� 10.4 (range 24�C60 years) in cigarette smokers and 45.4 �� 15.9 (range 20�C65 years) in waterpipe smokers (p > .05). The mean age was 36.1 �� 11.7 (range 21�C60 years) in nonsmoking females who reported exposure to cigarette smoke and 43.

1 �� 11.5 (range 24�C57 years) in nonsmoking females exposed to waterpipe smoke (p > .05). Table 1. Study Subject Characteristics by Smoking Status (n = 46) Both cigarette and waterpipe smokers had similar ages of smoking initiation and number of years of smoking (p > .05). On average, cigarette smokers consumed 21.5 �� 7 cigarettes/day, and waterpipe smokers consumed 11.9 �� 11 Brefeldin_A hagars (tobacco wads) per day. The mean FTND was 4.5 �� 1 in cigarette smokers, similar to previous studies (Park et al. 2004; Spitz et al.