Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 252
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
2.
Br J Pharmacol ; 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31648367

RESUMO

BACKGROUND AND PURPOSE: Genetics and drug interactions contribute to large interindividual variation in human CYP2D6 activity. Herein, we characterized propranolol inhibition in transgenic (TG) mice which express both mouse CYP2D and human CYP2D6 and in wildtype (WT) mice. Our purpose was to characterize propranolol as a CYP2D inhibitor in human and mouse, and to develop a method for in vivo manipulation of CYP2D6 enzyme activity which could be used to investigate the role of CYP2D6 in drug-induced behaviours. EXPERIMENTAL APPROACH: Dextromethorphan (DEX) metabolism to dextrorphan (DOR) was used to measure CYP2D activity and to characterize propranolol inhibition in vitro and in vivo. We also examined the impact of 24 h propranolol pre-treatment on serum levels of the CYP2D6 substrate haloperidol and haloperidol-induced catalepsy. KEY RESULTS: TG hepatic DOR formation velocity was 3-fold higher than WT in vitro. Propranolol acted as a mechanism-based inhibitor (MBI), inactivating CYP2D in liver microsomes from TG and WT mice, and humans. Intraperitoneal 24 h pre-treatment of TG and WT mice with 20 mg·kg-1 propranolol significantly reduced DOR formation in vivo, and in liver tissue in vitro. Serum haloperidol levels and catalepsy were significantly increased. CONCLUSIONS AND IMPLICATIONS: Propranolol was a potent MBI of DOR formation in liver microsomes from TG and WT mice, and humans; inhibition parameters in TG overlapped with WT mice and with humans. Manipulation of CYP2D with propranolol in vivo in TG and WT mice alters drug response, which will be useful for future investigation of the impact of variation in CYP2D6 on drug interactions and drug responses.

3.
Addiction ; 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31502736

RESUMO

BACKGROUND AND AIMS: Varenicline effectiveness may be related to the level of adherence, which might be reduced by adverse effects such as nausea. The aim of the study was to test a possible effect of nausea on smoking cessation outcomes mediated by adherence. DESIGN: Mediation path analysis. SETTING: Multiple sites within Canada and the United States. PARTICIPANTS: Treatment-seeking smokers receiving varenicline from two smoking cessation clinical trials: Quit2Live (NCT01836276; n = 449) and Pharmacogenetics of Nicotine Addiction Treatment (PNAT) (NCT01314001; n = 421). MEASUREMENTS: Nausea severity was collected through self-report and adherence was biologically assessed using varenicline concentrations (Quit2Live, plasma sample at week 4; PNAT, saliva sample at week 2). In Quit2Live, the end-points were cotinine-verified abstinence at weeks 4, 12 and 26. In PNAT, the end-points were carbon monoxide-verified abstinence at weeks 2, 12 and 26. FINDINGS: Early nausea was not directly associated with abstinence [odds ratio (OR) ranging from 0.73-1.28; P ≥ 0.26]. However early nausea was indirectly associated with lower cessation rates at multiple timepoints (ORs ranging from 0.92-0.94; 95% CI between 0.83-0.99) in a relationship mediated by reduced varenicline adherence (assessed by plasma varenicline concentrations) in the primary trial (Quit2Live). This relationship between nausea, adherence and cessation was similar in direction but weaker in effect size (ORs ranging from 0.98-0.99; 95% CI between 0.90-1.03) in a secondary trial (PNAT), where adherence was assessed using salivary varenicline concentrations. CONCLUSIONS: These data suggest that early nausea during varenicline treatment may be indirectly associated with lower likelihood of smoking cessation through reducing varenicline adherence. Differences in robustness between the trials may be due to the different biological matrices (plasma vs. saliva) and/or timing used to assess varenicline adherence. The results of the first study suggest that improved management of early nausea during varenicline treatment may positively impact smoking cessation success through increasing varenicline adherence.

5.
Free Radic Biol Med ; 143: 471-481, 2019 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-31479717

RESUMO

INTRODUCTION: The simple phenol hydroxytyrosol (OHTyr) has been associated with the beneficial health effects of extra virgin olive oil. Pre-clinical studies have identified Tyr hydroxylation, mediated by cytochrome P450 isoforms CYP2A6 and CYP2D6, as an additional source of OHTyr. AIM: We aimed to (i) confirm Tyr to OHTyr bioconversion in vivo in humans, (ii) assess the cardiovascular benefits of this bioconversion, and (iii) determine their interaction with a polygenic activity score (PAS) from CYP2A6 and CYP2D6 genotypes. METHODS: Randomized, crossover, controlled study. Individuals at cardiovascular risk (n = 33) received: white wine (WW) (females 1, males 2 standard drinks/day), WW plus Tyr capsules (WW + Tyr) (25  mg Tyr capsule, one per WW drink), and water (control) ad libitum. Participants were classified by a PAS as low versus normal activity metabolizers. RESULTS: OHTyr recovery following WW + Tyr was higher than after other interventions (P < 0.05). Low PAS individuals had lower OHTyr/Tyr ratios compared to individuals with normal PAS. WW + Tyr improved endothelial function, increased plasma HDL-cholesterol and antithrombin IIII, and decreased plasma homocysteine, endothelin 1, and CD40L, P65/RELA, and CFH gene expression in peripheral blood mononuclear cells (p < 0.05). Combining Tyr capsule(s) with WW abolished the increase in iNOS, eNOS, VEGFA, and CHF expressions promoted by WW (p < 0.05). CONCLUSIONS: Tyr, and its partial biotransformation into OHTyr, promoted cardiovascular health-related benefits in humans after dietary doses of Tyr. The study design allowed the health effects of individual phenols to be singled out from the dietary matrix in which they are naturally found.

6.
Drug Alcohol Depend ; 204: 107474, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31521954

RESUMO

BACKGROUND: Blacks bear a disproportionate burden of smoking-related diseases and experience greater difficulty quitting smoking than Whites. Nicotine has a high affinity for melanin, and it has been hypothesized that melanin levels might influence nicotine pharmacokinetics and enhance dependence. The aim of this study was to evaluate the hypothesis that melanin affects nicotine disposition kinetics in humans. METHODS: Forty-four Black participants were administered intravenous infusions of deuterium-labeled nicotine and cotinine. Plasma concentrations of nicotine and cotinine were measured, and pharmacokinetic parameters were estimated. The constitutive and facultative melanin indexes were measured using a dermaspectrophotometer. RESULTS: The median constitutive melanin index was 60.7 (32.8-134.7) and the median facultative melanin index 68.1 (38.6-127.1). The mean (±SD) nicotine elimination half-life was 136 min (±33.5), clearance was 1237 mL/min (±331), and Vss was 204 L (±66), or 2.6 L/kg (±0.7). No evidence of significant differences was found in nicotine pharmacokinetic parameters by comparing participants in different melanin index quartiles (outliers with very high melanin index had similar pharmacokinetic values to others). Differences were not statistically significant when adjusted for age, BMI, sex and CYP2A6 genotype or the nicotine metabolite ratio (NMR), and no evidence of significant correlations were found between melanin (facultative or constitutive) and the pharmacokinetic parameters of nicotine or cotinine or tobacco dependence measures. CONCLUSIONS: Based on our finding in this group of Black smokers, we could not confirm the hypothesis that melanin significantly affects nicotine disposition kinetics or measures of tobacco dependence.

7.
Nicotine Tob Res ; 2019 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-31294817

RESUMO

INTRODUCTION: FTND (FagerstrÓ§m test for nicotine dependence) and TTFC (time to smoke first cigarette in the morning) are common measures of nicotine dependence (ND). However, genome-wide meta-analysis for these phenotypes has not been reported. METHODS: Genome-wide meta-analyses for FTND (N = 19,431) and TTFC (N = 18,567) phenotypes were conducted for adult smokers of European ancestry from 14 independent cohorts. RESULTS: We found that SORBS2 on 4q35 (p = 4.05 × 10-8), BG182718 on 11q22 (p = 1.02 × 10-8), and AA333164 on 14q21 (p = 4.11 × 10-9) were associated with TTFC phenotype. We attempted replication of leading candidates with independent samples (FTND, N = 7010 and TTFC, N = 10 061), however, due to limited power of the replication samples, the replication of these new loci did not reach significance. In gene-based analyses, COPB2 was found associated with FTND phenotype, and TFCP2L1, RELN, and INO80C were associated with TTFC phenotype. In pathway and network analyses, we found that the interconnected interactions among the endocytosis, regulation of actin cytoskeleton, axon guidance, MAPK signaling, and chemokine signaling pathways were involved in ND. CONCLUSIONS: Our analyses identified several promising candidates for both FTND and TTFC phenotypes, and further verification of these candidates was necessary. Candidates supported by both FTND and TTFC (CHRNA4, THSD7B, RBFOX1, and ZNF804A) were associated with addiction to alcohol, cocaine, and heroin, and were associated with autism and schizophrenia. We also identified novel pathways involved in cigarette smoking. The pathway interactions highlighted the importance of receptor recycling and internalization in ND. IMPLICATIONS: Understanding the genetic architecture of cigarette smoking and ND is critical to develop effective prevention and treatment. Our study identified novel candidates and biological pathways involved in FTND and TTFC phenotypes, and this will facilitate further investigation of these candidates and pathways.

8.
Nicotine Tob Res ; 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31241144

RESUMO

INTRODUCTION: Alaska Native and American Indian (AN/AI) populations have higher tobacco use prevalence than other ethnic/racial groups. Pharmacogenetic (Pgx) testing to tailor tobacco cessation treatment may improve cessation rates. This study characterized polymorphic variations among AN/AI people in genes associated with metabolism of nicotine and drugs used for tobacco cessation. METHODS: Recruitment of AN/AI individuals represented six subgroups, five geographic subgroups throughout Alaska and a subgroup comprised of AIs from the lower 48 states living in Alaska. We sequenced the CYP2A6 and CYP2B6 genes to identify known and novel gain, reduced, and loss-of-function alleles, including structural variation (e.g., gene deletions, duplications, and hybridizations). RESULTS: Variant allele frequencies differed substantially between AN/AI subgroups. The gene deletion CYP2A6*4 and reduced function CYP2A6*9 alleles were found at high frequency in Northern/Western subgroups and in Lower 48/Interior subgroups, respectively. The reduced function CYP2B6*6 allele was observed in all subgroups and a novel, predicted reduced function CYP2B6 variant was found at relatively high frequency in the Southeastern subgroup. CONCLUSIONS: Diverse CYP2A6 and CYP2B6 variation among the subgroups highlight the need for comprehensive Pgx testing to guide tobacco cessation therapy for AN/AI populations. IMPLICATIONS: Nicotine metabolism is largely determined by CYP2A6 genotype, and variation in CYP2A6 activity has altered the treatment success in other populations. These findings suggest pharmacogenetic-guided smoking cessation drug treatment could provide benefit to this unique population seeking tobacco cessation therapy.

9.
Cancer Epidemiol Biomarkers Prev ; 28(8): 1345-1352, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31160346

RESUMO

BACKGROUND: Precision interventions using biological data may enhance smoking treatment, yet are understudied among smokers who are disproportionately burdened by smoking-related disease. METHODS: We surveyed smokers in the NCI-sponsored Southern Community Cohort Study, consisting primarily of African-American, low-income adults. Seven items assessed attitudes toward aspects of precision smoking treatment, from undergoing tests to acting on results. Items were dichotomized as favorable (5 = strongly agree/4 = agree) versus less favorable (1 = strongly disagree/2 = disagree/3 = neutral); a summary score reflecting generalized attitudes was also computed. Multivariable logistic regression tested independent associations of motivation (precontemplation, contemplation, and preparation) and confidence in quitting (low, medium, and high) with generalized attitudes, controlling for sociodemographic factors and nicotine dependence. RESULTS: More than 70% of respondents endorsed favorable generalized attitudes toward precision medicine, with individual item favorability ranging from 64% to 83%. Smokers holding favorable generalized attitudes reported higher income and education (P < 0.05). Predicted probabilities of favorable generalized attitudes ranged from 63% to 75% across motivation levels [contemplation vs. precontemplation: adjusted odds ratio (AOR) = 2.10, 95% confidence interval (CI), 1.36-3.25, P = 0.001; preparation vs. precontemplation: AOR = 1.83, 95% CI, 1.20-2.78, P = 0.005; contemplation vs. preparation: AOR = 1.15, 95% CI, 0.75-1.77, P = 0.52] and from 59% to 78% across confidence (medium vs. low: AOR = 1.91, 95% CI, 1.19-3.07, P = 0.007; high vs. low: AOR = 2.62, 95% CI, 1.68-4.10, P < 0.001; medium vs. high: AOR = 0.73, 95% CI, 0.48-1.11, P = 0.14). CONCLUSIONS: Among disproportionately burdened community smokers, most hold favorable attitudes toward precision smoking treatment. Individuals with lower motivation and confidence to quit may benefit from additional intervention to engage with precision smoking treatment. IMPACT: Predominantly favorable attitudes toward precision smoking treatment suggest promise for future research testing their effectiveness and implementation.

10.
J Natl Med Assoc ; 2019 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-31084916

RESUMO

OBJECTIVE: The study objective was to identify biobehavioral variables associated with greater intake of nicotine and a tobacco carcinogen among Black light smokers who smoke 1 to 10 cigarettes per day (CPD). METHODS: We analyzed baseline data collected from 426 Black light smokers enrolled in Kick It at Swope III (KIS III), a smoking cessation trial for Black smokers. We examined differences in concentrations of tobacco biomarkers, including urinary total nicotine equivalents (TNE) and total 4-(methylnitrosamino)-1-(3)pyridyl-1-butanonol (NNAL; a human carcinogen), across gender, age, plasma nicotine metabolite ratio (NMR), CPD, and measures of tobacco dependence, including time to first cigarette (TFC), using ANOVA. RESULTS: Tobacco biomarker levels were significantly higher among those who smoked more CPD (6-10 vs 1-5 CPD) and those with greater reported physical dependence on tobacco. Concurrently, those who smoked 1-5 CPD smoked each cigarette more intensely than those who smoked 6-10 CPD. While we found no gender differences overall, among those who smoked 1-5 CPD, women had higher NNAL levels compared to men. The rate of nicotine metabolism, measured by the nicotine metabolite ratio, was not significantly related to TNE or NNAL levels. CONCLUSION: Among Black Light smokers, higher cigarette consumption and greater physical dependence-but not rate of nicotine metabolism, menthol use, or socioeconomic status-were associated with greater toxicant exposure and thus a likely increased risk of tobacco-related diseases. The lack of data on light smokers, and specifically on Blacks, make this observation important given the disproportionate burden of lung cancer in this population.

11.
AIDS ; 33(6): 1083-1088, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30946162

RESUMO

OBJECTIVE: HIV-infected smokers lose more life years to tobacco use than to HIV infection. The nicotine metabolite ratio (NMR), a biomarker of CYP2A6, represents individual variation in the rate at which nicotine is metabolized and is associated with response to smoking cessation treatments. We evaluated whether HIV-infected smokers metabolize nicotine faster than HIV-uninfected smokers, which may contribute to the disproportionate smoking burden and may have important treatment implications. DESIGN: We analysed baseline data from two clinical trials (NCT01710137; NCT01314001) to compare the NMR in HIV-infected smokers (N = 131) to HIV-uninfected smokers (N = 199). METHODS: Propensity scores were used to match the groups 2 : 1 on characteristics that influence NMR: sex, race, BMI and smoking rate. Nicotine metabolites were assessed via liquid chromatography-tandem mass spectrometry methods and the ratio of 3-hydroxycotinine:cotinine was used to compute the NMR. RESULTS: HIV-infected smokers had significantly higher NMR (mean = 0.47, SEM = 0.02) and were more likely to be in the highest NMR quartile compared with HIV-uninfected smokers (mean = 0.34, SEM = 0.02; Ps < 0.001). CONCLUSION: The higher NMR observed among HIV-infected smokers may partially explain higher smoking rates and lower response to transdermal nicotine therapy. Understanding the mechanisms by which HIV and/or ART contribute to faster nicotine metabolism may guide the use of the NMR to personalize tobacco cessation strategies in this underserved population.

12.
Clin Pharmacol Ther ; 106(4): 726-733, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31006110

RESUMO

The HIV type-1 nonnucleoside reverse transcriptase inhibitor, efavirenz, is widely used to treat HIV type-1 infection. Efavirenz is predominantly metabolized into inactive metabolites by cytochrome P450 (CYP)2B6, and patients with certain CYP2B6 genetic variants may be at increased risk for adverse effects, particularly central nervous system toxicity and treatment discontinuation. We summarize the evidence from the literature and provide therapeutic recommendations for efavirenz prescribing based on CYP2B6 genotypes.

13.
Sci Rep ; 9(1): 3240, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30824792

RESUMO

When trying to quit, women are less likely than men to achieve long-term smoking abstinence. Identifying the neuropsychological mechanisms underlying women's higher relapse vulnerability will help clinicians to develop effective tailored smoking cessation interventions. Here we used event-related potentials (ERPs), a direct measure of brain activity, to evaluate the extent to which neurophysiological responses to cigarette-related and other emotional stimuli differ between female and male smokers. Both women and men showed similar patterns of brain reactivity across all picture categories; pleasant and unpleasant images prompted larger Late Positive Potentials (LPPs, a robust measure of motivational relevance) than neutral images in both groups, and cigarette-related images prompted lower LPPs than high arousing emotional images in both groups. Unlike previous studies, there were no differences between male and female smokers with regard to LPP responses to cigarette-related images. This suggests that the LPP may not be ideally suited to discriminate neurophysiological gender differences or that there are simply no gender differences in the neurophysiological responses to cigarette-related stimuli. We collected ERPs from 222 non-nicotine-deprived smokers (101 women) while they watched a slideshow that included high and low emotionally arousing pleasant and unpleasant pictures, cigarette-related, and neutral pictures. We used the mean amplitude of the LPP to assess the affective significance that participants attributed to these pictures.

14.
Addict Biol ; 2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30815984

RESUMO

The nicotine metabolite ratio (NMR; 3-hydroxycotinine/cotinine) is an index of CYP2A6 activity. CYP2A6 is responsible for nicotine's metabolic inactivation and variation in the NMR/CYP2A6 is associated with several smoking behaviors. Our aim was to integrate established alleles and novel genome-wide association studies (GWAS) signals to create a weighted genetic risk score (wGRS) for the CYP2A6 gene for European-ancestry populations. The wGRS was compared with a previous CYP2A6 gene scoring approach designed for an alternative phenotype (C2/N2; cotinine-d2/(nicotine-d2 + cotinine-d2)). CYP2A6 genotypes and the NMR were assessed in European-ancestry participants. The wGRS training set included N = 933 smokers recruited to the Pharmacogenetics of Nicotine Addiction and Treatment clinical trial [NCT01314001]. The replication cohort included N = 196 smokers recruited to the Quit 2 Live clinical trial [NCT01836276]. Comparisons between the two CYP2A6 phenotypes and with fractional clearance were made in a laboratory-based pharmacokinetic study (N = 92 participants). In both the training and replication sets, the wGRS, which included seven CYP2A6 variants, explained 33.8% (P < 0.001) of the variance in NMR, providing improved predictive power to the NMR phenotype when compared with other CYP2A6 gene scoring approaches. NMR and C2/N2 were strongly correlated to nicotine clearance (ρ = 0.70 and ρ = 0.79, respectively; P < 0.001), and to one another (ρ = 0.82; P < 0.001); however reduced function genotypes occurred in slow NMR but throughout C2/N2. The wGRS was able to predict smoking quantity and nicotine intake, to discriminate between NMR slow and normal metabolizers (AUC = 0.79; P < 0.001), and to replicate previous NMR-stratified cessation outcomes showing unique treatment outcomes between metabolizer groups.

15.
Nicotine Tob Res ; 2019 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-30753589

RESUMO

Introduction: One of the most preferable flavors in oral nicotine delivery systems is menthol which masks the harshness of tobacco. However, possible interactions between oral menthol and nicotine on intake and preference remain unclear. Therefore, we aimed to determine the impact of menthol on oral nicotine consumption. Methods: Adult Sprague Dawley female and male rats (n=8/per group) were given a choice of water or drug solution by using two-bottle free choice paradigm for two weeks: vehicle (5% ethanol), nicotine (20 mg/l), menthol (1 g/l) and mentholated nicotine groups. At the end of the study, plasma nicotine levels were determined. Results: When rats were given a choice of nicotine or water, nicotine intake was similar between female and male rats. Menthol addition to nicotine solution significantly increased nicotine intake and preference in male but not female rats without a considerable effect on total fluid intake and body weight change in either sex. The average nicotine intake in male rats was 0.5 ± 0.05 and 1.4 ± 0.12 mg/kg/day for nicotine and menthol-nicotine combination (p<0.05), respectively. The average nicotine intake in female rats was 0.6 ± 0.05 and 0.6 ± 0.03 mg/kg/day for nicotine and menthol-nicotine combination (p>0.05), respectively. Plasma nicotine levels were not significantly different between the groups in either male (nicotine group: 20.8 ± 4.9, mentholated nicotine group: 31.9 ± 3.2 ng/ml) or female (nicotine group: 24.0 ± 3.3, mentholated nicotine group: 17.8 ± 2.9 ng/ml) rats (p>0.05). Conclusions: Menthol increases oral nicotine consumption in male, but not female, rats. Implications: This study may provide data on the co-use of menthol and nicotine in the smokeless tobacco, particularly oral dissolvable tobacco products.

16.
Br J Clin Pharmacol ; 85(5): 960-969, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30706508

RESUMO

AIMS: CYP2A6 is a genetically polymorphic enzyme resulting in differential substrate metabolism and health behaviours. Current phenotyping probes for CYP2A6 exhibit limitations related to procurement (deuterated cotinine), toxicity (coumarin), specificity (caffeine) and age-appropriate administration (nicotine, NIC). In vitro, CYP2A6 selectively forms 2-hydroxymetronidazole (2HM) from metronidazole (MTZ). The purpose of this study was to evaluate MTZ as a CYP2A6 phenotyping probe drug in healthy adults against the well-established method of measuring trans-3-hydroxycotinine (3HC)/cotinine (COT). METHODS: A randomized, cross-over, pharmacokinetic study was completed in 16 healthy, nonsmoking adults. Separated by a washout period of at least 2 weeks, MTZ 500 mg and NIC gum 2 mg were administered and plasma was sampled over 48 hours and 8 hours, respectively. Correlations of plasma metabolite/parent ratios (2HM/MTZ; 3HC/COT) were assessed by Pearson coefficient. CYP2A6 genotyping was conducted and incorporated as a variable of plasma ratio response. RESULTS: Correlations between the plasma ratio 2HM/MTZ and 3HC/COT were ≥ 0.9 at multiple time points (P < 0.001), demonstrating a wide window during which 2HM/MTZ can be queried post-MTZ dose. CYP2A6 genotype had significant impacts on both MTZ and NIC phenotyping ratios with decreased activity predicted phenotypes demonstrating 2HM/MTZ ratios ≤58% and 3HC/COT ratios ≤56% compared with extensive activity predicted phenotypes at all time points examined in the study (P < 0.05). No adverse events were reported in the MTZ arm while 38% (n = 6) of participants reported mild adverse events in the NIC arm. CONCLUSIONS: Metronidazole via 2HM/MTZ performed well as a novel, safe phenotyping probe for CYP2A6 in healthy adults.

17.
J Natl Cancer Inst ; 111(10): 1078-1087, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30657926

RESUMO

BACKGROUND: Black-white differences in smoking abstinence are not well understood. This trial sought to confirm previously reported differences in quitting between blacks and whites and to identify factors underlying this difference. METHODS: During enrollment, 224 black and 225 white low-income smokers were stratified on race and within race on age and sex to ensure balance on these factors known to impact abstinence. The intervention included varenicline for 12 weeks and six guideline-based smoking cessation counseling sessions. The primary endpoint was cotinine-verified 7-day point prevalence smoking abstinence at week 26. A priori socioeconomic, smoking, treatment process (eg, treatment utilization, side effects, withdrawal relief), psychosocial, and biological factors were assessed to investigate race differences in abstinence. Unadjusted odds ratios (OR) were used to compare abstinence between blacks and whites. Adjusted odds ratios from logistic regression models were used to examine predictors of abstinence. All statistical tests were two-sided. RESULTS: Blacks were less likely to achieve abstinence at week 26 (14.3% vs 24.4%, OR = 0.51, 95% confidence interval [CI] = 0.32 to 0.83, P = .007). Utilizing best subsets logistic regression, five factors associated with race jointly predicted abstinence: home ownership (yes/no, OR = 3.03, 95% CI = 1.72 to 5.35, P < .001), study visits completed (range = 0-6, OR = 2.81, 95% CI = 1.88 to 4.20, P < .001), income (household member/$1000, OR = 1.03, 95% CI = 1.01 to 1.06, P = .02), plasma cotinine (per 1 ng/mL, OR = 0.997, 95% CI = 0.994 to 0.999, P = .002), and neighborhood problems (range = 10-30, OR = 0.88, 95% CI = 0.81 to 0.96, P = .003). CONCLUSIONS: The race difference in abstinence was fully explained by lack of home ownership, lower income, greater neighborhood problems, higher baseline cotinine, and higher visit completion, which were disproportionately represented among blacks. Findings illuminate factors that make it harder for blacks in the United States to quit smoking relative to whites and provide important areas for future studies to reduce tobacco-related health disparities.

18.
Clin Epigenetics ; 11(1): 1, 2019 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-30611298

RESUMO

BACKGROUND: DNA methylation alteration extensively associates with smoking and is a plausible link between smoking and adverse health. We examined the association between epigenome-wide DNA methylation and serum cotinine levels as a proxy of nicotine exposure and smoking quantity, assessed the role of SNPs in these associations, and evaluated molecular mediation by methylation in a sample of biochemically verified current smokers (N = 310). RESULTS: DNA methylation at 50 CpG sites was associated (FDR < 0.05) with cotinine levels, 17 of which are novel associations. As cotinine levels are influenced not only by nicotine intake but also by CYP2A6-mediated nicotine metabolism rate, we performed secondary analyses adjusting for genetic risk score of nicotine metabolism rate and identified five additional novel associations. We further assessed the potential role of genetic variants in the detected association between methylation and cotinine levels observing 124 cis and 3898 trans methylation quantitative trait loci (meQTLs). Nineteen of these SNPs were also associated with cotinine levels (FDR < 0.05). Further, at seven CpG sites, we observed a trend (P < 0.05) that altered DNA methylation mediates the effect of SNPs on nicotine exposure rather than a direct consequence of smoking. Finally, we performed replication of our findings in two independent cohorts of biochemically verified smokers (N = 450 and N = 79). CONCLUSIONS: Using cotinine, a biomarker of nicotine exposure, we replicated and extended identification of novel epigenetic associations in smoking-related genes. We also demonstrated that DNA methylation in some of the identified loci is driven by the underlying genotype and may mediate the causal effect of genotype on cotinine levels.


Assuntos
Cotinina/sangue , Metilação de DNA , Epigenômica/métodos , Polimorfismo de Nucleotídeo Único , Fumar/genética , Adulto , Idoso , Ilhas de CpG , Citocromo P-450 CYP2A6/genética , Feminino , Estudos de Associação Genética , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Fumar/sangue , Adulto Jovem
19.
Psychol Addict Behav ; 33(2): 105-116, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30614717

RESUMO

Smokers attempting to quit often attribute smoking relapse to negative affect, craving, and other nicotine withdrawal symptoms. In addition, there is evidence that smoking relapse can increase these symptoms, particularly negative affect. To address this issue, we analyzed data from an 11-week smoking cessation clinical trial in which smokers (n = 1,246) were randomized to receive either nicotine replacement therapy (NRT), varenicline, or placebo, combined with behavioral counseling. Using cross-lagged analyses, we examined the temporal bidirectional relationships between self-reported measures of affect, craving, and composite withdrawal symptoms and biochemically verified smoking abstinence. The relative strength of these temporal relationships was examined by comparing the explained variances of the models. The results showed that higher negative affect, craving, and composite withdrawal symptoms increased the likelihood of subsequent smoking relapse, and that smoking relapse led to subsequent increases in these same symptoms. A comparison of the explained variances found symptom predicting subsequent relapse models to be stronger than those where relapse predicted subsequent symptoms. Although the explained variance findings generally support a negative reinforcement conceptualization of nicotine dependence, the bidirectional relationship between symptoms and smoking relapse suggests that struggling with quitting smoking leads to significant negative affect, craving, and other withdrawal symptoms that do not quickly resolve. These findings highlight the importance of addressing specific symptoms within the context of smoking cessation. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

20.
Nicotine Tob Res ; 2018 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-30561731

RESUMO

Introduction: Alcohol may influence the nicotine metabolite ratio (NMR), an index of the rate of nicotine metabolism that is associated smoking level and lapses. We examined if NMR changes during alcohol use disorder (AUD) treatment and how changes in NMR relate to reductions in drinking. Methods: Using an observational design, 22 daily smokers (63.64% male, Mage=46.77 (11.37)) receiving AUD treatment completed baseline and follow-up appointments three weeks apart. At each appointment, daily alcohol and cigarette use, salivary and urinary NMR, nicotine exposure via urinary total nicotine equivalents (TNE), and carbon monoxide (CO) were assessed. Multilevel models examined the change over time in NMR and its within-person relations with changes in drinks per week. Sex differences were evaluated. Results: There were significant reductions in both salivary and urinary NMR over time for men (p=.02; p=.01, respectively) but not for women (p=.54; p=.90). There were no changes over time in TNE (p=.09), CO (p=.44), or cigarette use (p=.44), in either sex. Drinks per week were significantly reduced for men (29.12 drink reduction, p<.001) but not for women (2.28 drink reduction, p=.80); however, within-person changes in drinking were not associated with changes in salivary or urinary NMR (p=.99; p=.19). Conclusions: The reduction in alcohol use and NMR in men provides indirect support for alcohol increasing NMR. In contrast, the low baseline drinking and lack of alcohol reduction likely underlies the lack of change in NMR in females. Reasons for NMR reductions during AUD treatment and its effects on smoking require further study. Implications: Three weeks of alcohol use disorder treatment among daily smokers coincided with both a significant reduction in alcohol use and a significant reduction in the nicotine metabolite ratio (NMR) for men, however, neither drinking level or NMR changed for women. The findings indirectly support that heavy drinking increases NMR, which is reversed with reduced drinking. Additional research is needed to establish if these changes in NMR correlate with smoking and cessation outcomes.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA