Smokers, differences from nonsmokers

MRI has contributed a wealth of information regarding the neurobiological correlates and consequences of cigarette smoking and nicotine dependence. Recent findings demonstrate that smokers differ from nonsmokers in regional brain structure... 

ETS particles behave quite differently from MSS particles in terms of human retention. Unlike MSS, the retention of ETS in the lung is not affected by evaporative transfer and cloud effects. Instead, ETS retention is influenced mainly by particle size. Theoretical calculations indicate that the percentage retention of particles equivalent in size to ETS particles should vary between 10% and 20%. A value within the theoretical range was obtained Hiller et al. from studies with human mouth-breathing volunteer nonsmokers who orally inhaled polystyrene latex spheres of particle sizes similar to those of diluted sidestream smoke (1654a) and five volunteers who inhaled a tobacco smoke defined as sidestream smoke at a concentration similar to that encountered indoors with smokers present (1654b), estimated the percentage retention of the smoke to be 11%. 

Environmental Exposure. In contrast to these results, several studies on adducts in smokers and nonsmokers have not detected significant differences between these populations. Mean adduct levels in placental DNA of smokers were 1.9/10 nucleotides and in nonsmokers 1.2/10 (28-29). White blood cell DNA adducts were lower than in placenta but also were not significantly different in smokers (0.15/10 ) compared to nonsmokers (0.12/10 ) (30). These results probably reflect the ubiquitous exposure of the general population to PAHs from a number of sources including air pollution and, more importantly, diet. Recently, we have also found a seasonal effect on adduct levels with blood samples collected during... 

Beyond socioeconomic characteristics, vitamin C intake is dependent upon other dietary and nondietary risk factors. It was found that smokers have lower values of vitamin C concentrations in blood at similar levels of intake (Dickinson et aL, 1994) and that their dietary intake of vitamin C is lower than that of nonsmokers (Subar et aL, 1990 Margetts and Jackson, 1993). Also, the diet of alcohol drinkers is different from the diet of nondrinkers. Alcohol drinkers tend to eat less fruits and vegetables and thereby consume less vitamin C (La Vecchia et aL, 1992). 

Model equations can be augmented with expressions accounting for covariates such as subject age, sex, weight, disease state, therapy history, and lifestyle (smoker or nonsmoker, IV drug user or not, therapy compliance, and others). If sufficient data exist, the parameters of these augmented models (or a distribution of the parameters consistent with the data) may be determined. Multiple simulations for prospective experiments or trials, with different parameter values generated from the distributions, can then be used to predict a range of outcomes and the related likelihood of each outcome. Such dose-exposure, exposure-response, or dose-response models can be classified as steady state, stochastic, of low to moderate complexity, predictive, and quantitative. A case study is described in Section 22.6. 

Spring B, Pagoto S, et al (2003) Altered reward value of carbohydrate snacks for female smokers withdrawn from nicotine. Pharmacol Biochem Behav 76(2) 351-360 Staley JK, Krishnan-Sarin S, et al (2001) Sex differences in [ I]beta-C1T SPECT measures of dopamine and serotonin transporter availability in healthy smokers and nonsmokers. Synapse 41(4) 275-284... 

Fig. 2 a Distribution of threshold doses (in Xg kg ) for nicotine nasal spray discrimination in smokers (n = 18) vs. nonsmokers (n = 17). Horizontal lines designate group median thresholds, which did not differ between groups, b Selected subjective responses to nasal spray nicotine doses at, and just below, threshold for discrimination in smokers and nonsmokers. p < 0.05 p < 0.01 for difference between doses. Reprinted from Figs. 1 and 2 in Perkins et al. (2001c) with kind permission from Springer Science and Business Media... 

Fig. 3 Quantitative left) and quantal right) measures of generalization of discrimination across nicotine generalization doses in smokers filled circles or bars, n = ll) vs. nonsmokers (open circles or bars, n = 10). Dotted line indicates 50% or chance responding. Group differences in responding were observed at 20pgkg for quantitative and 12pgkg for quantal responding. Reprinted from Fig. 1 in Perkins et al. (1997) with kind permission from Springer Science and Business Media...

---