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1.  The DRD4 Exon III VNTR, Bupropion, and Associations With Prospective Abstinence 
Nicotine & Tobacco Research  2012;15(7):1190-1200.
Introduction:
DRD4 Exon III Variable Number of Tandem Repeat (VNTR) variation was found to interact with bupropion to influence prospective smoking abstinence, in a recently published longitudinal analyses of N = 331 individuals from a randomized double-blind placebo-controlled trial of bupropion and intensive cognitive–behavioral mood management therapy.
Methods:
We used univariate, multivariate, and longitudinal logistic regression to evaluate gene, treatment, time, and interaction effects on point prevalence and continuous abstinence at end of treatment, 6 months, and 12 months, respectively, in N = 416 European ancestry participants in a double-blind pharmacogenetic efficacy trial randomizing participants to active or placebo bupropion. Participants received 10 weeks of pharmacotherapy and 7 sessions of behavioral therapy, with a target quit date 2 weeks after initiating both therapies. VNTR genotypes were coded with the long allele dominant resulting in 4 analysis categories. Covariates included demographics, dependence measures, depressive symptoms, and genetic ancestry. We also performed genotype-stratified secondary analyses.
Results:
We observed significant effects of time in longitudinal analyses of both abstinence outcomes, of treatment in individuals with VNTR long allele genotypes for both abstinence outcomes, and of covariates in some analyses. We observed non-significantly larger differences in active versus placebo effect sizes in individuals with VNTR long allele genotypes than in individuals without the VNTR long allele, in the directions previously reported.
Conclusions:
VNTR by treatment interaction differences between these and previous analyses may be attributable to insufficient size of the replication sample. Analyses of multiple randomized clinical trials will enable identification and validation of factors mediating treatment response.
doi:10.1093/ntr/nts245
PMCID: PMC3682839  PMID: 23212438
2.  The ability of plasma cotinine to predict nicotine and carcinogen exposure is altered by differences in CYP2A6: the influence of genetics, race and sex 
Background
Cotinine, a nicotine metabolite, is a biomarker of tobacco, nicotine and carcinogen exposure. However a given cotinine level may not represent the same tobacco exposure; for example, African Americans have higher cotinine levels than Caucasians after controlling for exposure.
Methods
Cotinine levels are determined by the amount of cotinine formation and the rate of cotinine removal which are both mediated by the enzyme CYP2A6. Since CYP2A6 activity differs by sex (estrogen induces CYP2A6) and genotype, their effect on cotinine formation and removal were measured in non-smoking Caucasians (Study 1, n=181) infused with labeled nicotine and cotinine. The findings were then extended to ad libitum smokers (Study 2, n=163).
Results
Study 1: Reduced CYP2A6 activity altered cotinine formation less than cotinine removal resulting in ratios of formation to removal of 1.31 and 1.12 in CYP2A6 reduced and normal metabolizers (P=0.01), or 1.39 and 1.12 in males and females (P=0.001), suggesting an overestimation of tobacco exposure in slower metabolizers. Study 2: Cotinine again overestimated tobacco and carcinogen exposure by ≥25% in CYP2A6 reduced metabolizers (≈2 fold between some genotypes) and in males.
Conclusions
In people with slower, relative to faster, CYP2A6 activity cotinine accumulates resulting in substantial differences in cotinine levels for a given tobacco exposure.
Impact
Cotinine levels may be misleading when comparing those with differing CYP2A6 genotypes within a race, between races with differing frequencies of CYP2A6 gene variants (i.e. African Americans have higher frequencies of reduced function variants contributing to their higher cotinine levels) or between the sexes.
doi:10.1158/1055-9965.EPI-12-1234-T
PMCID: PMC3617060  PMID: 23371292
Tobacco; Cotinine; CYP2A6; Polycyclic aromatic hydrocarbons; NNAL
3.  Nicotinic Acetylcholine Receptor Variation and Response to Smoking Cessation Therapies 
Pharmacogenetics and genomics  2013;23(2):94-103.
Objective
Evaluate nicotinic acetycholine receptor (nAChR) single nucleotide polymorphism (SNP) association with seven day point prevalence abstinence (abstinence) in randomized clinical trials of smoking cessation therapies (RCTs) in individuals grouped by pharmacotherapy randomization to inform the development of personalized smoking cessation therapy.
Methods
We quantified association of four SNPs at three nAChRs with abstinence in eight RCTs. Participants were 2,633 outpatient treatment-seeking, self-identified European ancestry individuals smoking ≥10 cigarettes per day, recruited via advertisement, prescribed pharmacotherapy, and provided with behavioral therapy. Interventions included nicotine replacement therapy (NRT), bupropion, varenicline, placebo or combined NRT and bupropion, and five modes of group and individual behavioral therapy. Outcome measures tested in multivariate logistic regression were end of treatment (EOT) and six month (6MO) abstinence, with demographic, behavioral and genetic covariates.
Results
“Risk” alleles previously associated with smoking heaviness were significantly (P<0.05) associated with reduced abstinence in the placebo pharmacotherapy group (PG) at 6MO [for rs588765 OR (95%CI) 0.41 (0.17–0.99)], and at EOT and at 6MO [for rs1051730, 0.42 (0.19–0.93) and 0.31 (0.12–0.80)], and with increased abstinence in the NRT PG at 6MO [for rs588765 2.07 (1.11–3.87) and for rs1051730 2.54 (1.29–4.99)]. We observed significant heterogeneity in rs1051730 effects (F=2.48, P=0.021) between PGs.
Conclusions
chr15q25.1 nAChR SNP risk alleles for smoking heaviness significantly increase relapse with placebo treatment and significantly increase abstinence with NRT. These SNP-PG associations require replication in independent samples for validation, and testing in larger sample sizes to evaluate whether similar effects occur in other PGs.
doi:10.1097/FPC.0b013e32835cdabd
PMCID: PMC3563676  PMID: 23249876
logistic regression; mediation analysis; nAChR variation; nicotine dependence; pharmacotherapy; randomized clinical trials
4.  Pharmacogenetic Smoking Cessation Intervention in a Health Care Setting: A Pilot Feasibility Study 
Nicotine & Tobacco Research  2012;15(2):518-526.
Introduction:
There is increasing evidence that response to pharmacological treatment for nicotine dependence may be moderated by genetic polymorphisms. However, the feasibility, acceptability, and impact of genetically tailoring treatment in real-world clinical settings are unknown.
Methods:
We conducted a multiphased, mixed-methods feasibility study with current smokers to develop and evaluate a patient-centered, theoretically grounded personalized medicine treatment protocol. The initial research phase included formative work to develop intervention materials. The second phase included a randomized pilot trial to evaluate the intervention. Trial participants (n = 36) were genotyped for ANKK1 rs1800497 and were randomized to receive genetic feedback (GF) plus standard behavioral counseling (BC) for smoking cessation or BC without GF. All participants received genetically tailored pharmacotherapy (nicotine patch or bupropion).
Results:
The intervention was feasible to implement and was acceptable to participants based on satisfaction ratings and objective measures of participation. There was no evidence that the GF resulted in adverse psychological outcomes (e.g., depression, fatalism, reduced perceived control over quitting, differential motivation for quitting) based on quantitative or qualitative outcomes.
Conclusions:
Study results suggest that it is feasible to offer treatment within a health care setting that includes genetically tailored pharmacotherapy and doing so had no apparent adverse psychological impacts. Further evaluation of pharmacogenetically tailored smoking cessation interventions appears warranted.
doi:10.1093/ntr/nts173
PMCID: PMC3611995  PMID: 22949583
5.  Chronic psychosocial stressors and salivary biomarkers in emerging adults 
Psychoneuroendocrinology  2011;37(8):1158-1170.
Summary
We investigated whole saliva as a source of biomarkers to distinguish individuals who have, and who have not, been chronically exposed to severe and threatening life difficulties. We evaluated RNA and DNA metrics, expression of 37 candidate genes, and cortisol release in response to the Trier Social Stress Test, as well as clinical characteristics, from 48 individuals stratified on chronic exposure to psychosocial stressors within the last year as measured by the Life Events and Difficulties Schedule. Candidate genes were selected based on their differential gene expression ratio in circulating monocytes from a published genome-wide analysis of adults experiencing different levels of exposure to a chronic stressor.
In univariate analyses, we observed significantly decreased RNA integrity (RIN) score (P = 0.04), and reduced expression of glucocorticoid receptor-regulated genes (Ps < 0.05) in whole saliva RNA from individuals exposed to chronic stressors, as compared to those with no exposure. In those exposed, we observed significantly decreased BMI (P < 0.001), increased ever-smoking and increased lifetime alcohol abuse or dependence (P ≤ 0.03), and a reduction of cortisol release. In post hoc multivariate analyses including clinical and biospecimen-derived variables, we consistently observed significantly decreased expression of IL8 (Ps < 0.05) in individuals exposed, with no significant association to RIN score. Alcohol use disorders, tobacco use, a reduced acute stress response and decreased salivary IL8 gene expression characterize emerging adults chronically exposed to severe and threatening psychosocial stressors.
doi:10.1016/j.psyneuen.2011.11.010
PMCID: PMC3774595  PMID: 22172638
Human; Saliva; Gene expression; IL8; qPCR
6.  COMPARATIVE DYNAMICS OF FOUR SMOKING WITHDRAWAL SYMPTOM SCALES 
Addiction (Abingdon, England)  2012;107(8):1501-1511.
Aims
Examine the association of person-specific trajectories of withdrawal symptoms of urge-to-smoke, negative affect, physical symptoms, and hunger during the first 7 days after smoking cessation with abstinence at end of treatment (EOT) and 6 months.
Design
Hierarchical Linear Modeling (HLM) was used to model person-specific trajectory parameters (level, slope, curvature and volatility) for withdrawal symptoms.
Setting
University-based smoking cessation trials.
Participants
Treatment seeking smokers in clinical trials of transdermal nicotine versus nicotine spray (n=514) and bupropion versus placebo (n=421)
Measurements
Self-reported withdrawal symptoms for 7 days after the planned quit date, and 7 day point prevalence and continuous abstinence at EOT and 6 months.
Findings
In regressions that included trajectory parameters for one group of withdrawal symptoms, both urge-to-smoke and negative affect were predictive of abstinence while physical symptoms and hunger were generally not predictive. In stepwise regressions that included the complete set of trajectory parameters across withdrawal symptoms (for urge-to-smoke, negative affect, physical symptoms, and hunger), with a single exception, only the trajectory parameters for urge-to-smoke were predictive. Area under the Receiver Operator Characteristic curve was 0.594 for covariates alone, and 0.670 for covariates plus urge-to-smoke trajectory parameters.
Conclusion
Among a number of different withdrawal symptoms (urge-to-smoke, negative affect, physical symptoms, and hunger) urge-to-smoke trajectory parameters (level, slope, and volatility) over the first 7 days of smoking cessation show the strongest prediction of both short and long term relapse. Other withdrawal symptoms increase the predictive ability by negligible amounts.
doi:10.1111/j.1360-0443.2012.03838.x
PMCID: PMC3394903  PMID: 22321019
smoking cessation; withdrawal symptoms; urge-to-smoke; negative affect; physical symptoms; hunger; nicotine replacement therapy; bupropion
7.  GENETIC AND ENVIRONMENTAL INFLUENCES ON THE RATIO OF 3’HYDROXYCOTININE TO COTININE IN PLASMA AND URINE 
Pharmacogenetics and genomics  2009;19(5):388-398.
Objectives
The ratio of trans-3’hydroxycotinine/cotinine (3HC/COT) is a marker of CYP2A6 activity, an important determinant of nicotine metabolism. This analysis sought to conduct a combined genetic epidemiologic and pharmacogenetic investigation of the 3HC/COT ratio in plasma and urine.
Methods
One hundred thirty nine twin pairs (110 monozygotic [MZ] and 29 dizygotic [DZ]) underwent a 30-minute infusion of stable isotope-labeled nicotine and its major metabolite, cotinine, followed by an 8-hour in-hospital stay. Blood and urine samples were taken at regular intervals for analysis of nicotine, cotinine, and metabolites. DNA was genotyped to confirm zygosity and for variation in the gene for the primary nicotine metabolic enzyme, CYP2A6 (variants genotyped: *1B, *1×2, *2, *4, *9, *12). Univariate biometric analyses quantified genetic and environmental influences on each measure in the presence and absence of covariates, including measured CYP2A6 genotype.
Results
There was a substantial amount of variation in the free 3HC/COT ratio in plasma (6 hours post-infusion) attributable to additive genetic influences (67.4%, 95% CI = 55.9–76.2%). The heritability estimate was reduced to 61.0% and 49.4%, respectively, after taking into account the effect of covariates and CYP2A6 genotype. In urine (collected over 8 hours), the estimated amount of variation in the 3HC/COT ratio attributable to additive genetic influences was smaller (47.2%, 95% CI = 0–67.2%) and decreased to 44.6% and 42.0% after accounting for covariates and genotype.
Conclusions
Additive genetic factors are prominent in determining variation in plasma 3HC/COT variation but less so in determining variation in urine 3HC/COT.
doi:10.1097/FPC.0b013e32832a404f
PMCID: PMC2849278  PMID: 19300303
pharmacogenetics; nicotine; cotinine; metabolism; CYP2A6; twins; genetics; heritability
8.  DRD1 Associations with Smoking Abstinence Across Slow and Normal Nicotine Metabolizers 
Pharmacogenetics and Genomics  2012;22(7):551-554.
Nicotine metabolism and genetic variation have an impact on nicotine addiction and smoking abstinence, but further research is required. The nicotine metabolite ratio (NMR) is a robust biomarker of nicotine metabolism used to categorize slow and normal nicotine metabolizers (lower 25th quartile cutoff). In two randomized clinical trials of smoking abstinence treatments, we conducted NMR-stratified analyses on smoking abstinence across 13 regions coding for nicotinic acetylcholine receptors and proteins involved in the dopamine reward system. Gene × NMR interaction P-values were adjusted for multiple correlated tests, and we used a Bonferroni-corrected α-level of 0.004 to determine system-wide significance. Three SNPs in DRD1 (rs11746641, rs2168631, rs11749035) had significant interactions (0.001 ≤ adjusted P-values ≤ 0.004), with increased odds of abstinence within slow metabolizers (ORs=3.1–3.5, 95% CI 1.7–6.7). Our findings support the role of DRD1 in nicotine dependence, and identify genetic and nicotine metabolism profiles that may interact to impact nicotine dependence.
doi:10.1097/FPC.0b013e3283539062
PMCID: PMC3376177  PMID: 22495174
Genetic association studies; heterogeneity; smoking abstinence; nicotine metabolism; nicotine metabolite ratio; DRD1
9.  Pain Sensitivity and Opioid Analgesia: A Pharmacogenomic Twin Study 
Pain  2012;153(7):1397-1409.
Opioids are the cornerstone medication for the management of moderate to severe pain. Unfortunately, vast inter-individual differences in dose requirements complicate their effective and safe clinical use. Mechanisms underlying such differences are incompletely understood, are likely multifactorial, and include genetic and environmental contributions. While accumulating evidence suggests that variants of several genes account for some of the observed response variance, the relative contribution of these factors remains unknown. This study used a twin paradigm to provide a global estimate of the genetic and environmental contributions to inter-individual differences in pain sensitivity and analgesic opioid effects. Eighty one monozygotic and 31 dizygotic twin pairs successfully underwent a computer-controlled infusion with the muopioid agonist alfentanil in a single occasion, randomized, double-blind and placebo-controlled study design. Pain sensitivity and analgesic effects were assessed with experimental heat and cold pressor pain models along with important covariates including demographic factors, depression, anxiety, and sleep quality. Significant heritability was detected for cold pressor pain tolerance and opioid-mediated elevations in heat and cold pressor pain thresholds. Genetic effects accounted for 12–60% of the observed response variance. Significant familial effects accounting for 24–32% of observed variance were detected for heat and cold pressor pain thresholds and opioid-mediated elevation in cold pressor pain tolerance. Significant covariates included age, gender, race, education, and anxiety. Results provide a strong rationale for more detailed molecular genetic studies to elucidate mechanisms underlying inter-individual differences in pain sensitivity and analgesic opioid responses. Such studies will require careful consideration of the studied pain phenotype.
doi:10.1016/j.pain.2012.02.022
PMCID: PMC3377769  PMID: 22444188
10.  Aversive and Reinforcing Opioid Effects: A Pharmacogenomic Twin Study 
Anesthesiology  2012;117(1):22-37.
Background
The clinical utility of opioids is limited by adverse drug effects including respiratory depression, sedation, nausea, and pruritus. In addition, abuse of prescription opioids is problematic. Gaining a better understanding of the genetic and environmental mechanisms contributing to an individual’s susceptibility to adverse opioid effects is essential to identify patients at risk.
Methods
A classical twin study paradigm provided estimates for the genetic and familial (genetic and/or shared environment) contribution to acute adverse and affective opioid responses; all secondary outcomes of a larger data set. One hundred and twenty one twin pairs were recruited in a single occasion, randomized, double-blind and placebo controlled study. The mu-opioid receptor agonist alfentanil and saline placebo were administered as target-controlled infusions under carefully monitored laboratory conditions. Measured outcomes included respiratory depression, sedation, nausea, pruritus, drug liking and drug disliking. Demographic information was collected, and aspects of mood and sleep were evaluated.
Results
Significant heritability was detected for respiratory depression (30%), nausea (59%) and drug disliking (36%). Significant familial effects were detected for sedation (29%), pruritus (38%), dizziness (32%), and drug liking (26%). Significant covariates included age, gender, race, ethnicity, education, mood and depression. Covariates affected sedation, pruritus, drug liking and disliking, and dizziness.
Conclusions
This study demonstrates that large scale efforts to collect quantitative and well-defined opioid response data are not only feasible but also produce data that are suitable for genetic analysis. Genetic, environmental and demographic factors work together to control adverse and reinforcing opioid responses, but contribute differently to specific responses.
doi:10.1097/ALN.0b013e31825a2a4e
PMCID: PMC3428265  PMID: 22713632
11.  Gender Stratified Gene and Gene–Treatment Interactions in Smoking Cessation 
The pharmacogenomics journal  2011;12(6):521-532.
We conducted gender-stratified analyses on a systems-based candidate gene study of 53 regions involved in nicotinic response and the brain-reward pathway in two randomized clinical trials of smoking cessation treatments (placebo, bupropion, transdermal and nasal spray nicotine replacement therapy). We adjusted P-values for multiple correlated tests, and used a Bonferroni corrected α-level of 5 × 10−4 to determine system-wide significance. Four SNPs (rs12021667, rs12027267, rs6702335, rs12039988; r2>0.98) in erythrocyte membrane protein band 4.1 (EPB41) had a significant male-specific marginal association with smoking abstinence (OR=0.5; 95% CI 0.3–0.6) at end of treatment (adjusted P<6 × 10−5). rs806365 in cannabinoid receptor 1 (CNR1) had a significant male-specific gene-treatment interaction at 6-month follow-up (adjusted P=3.9 × 10−5); within males using nasal spray, rs806365 was associated with a decrease in odds of abstinence (OR=0.04; 95% CI 0.01–0.2). While the role of CNR1 in substance abuse has been well studied, we report EPB41 for the first time in the nicotine literature.
doi:10.1038/tpj.2011.30
PMCID: PMC3208134  PMID: 21808284
Genetic association studies; heterogeneity; smoking cessation
12.  Varenicline for Smoking Cessation: Nausea Severity and Variation in Nicotinic Receptor Genes 
The Pharmacogenomics Journal  2011;12(4):349-358.
This study evaluated association between common and rare sequence variants in 10 nicotinic acetylcholine receptor subunit genes and the severity of nausea 21 days after initiating the standard, FDA-approved varenicline regimen for smoking cessation. Included in the analysis were 397 participants from a randomized clinical effectiveness trial with complete clinical and DNA resequencing data (mean age = 49.2 years; 68.0% female). Evidence for significant association between common sequence variants in CHRNB2 and nausea severity was obtained after adjusting for age, gender, and correlated tests (all PACT<.05). Individuals with the minor allele of CHRNB2 variants experienced less nausea than did those without the minor allele, consistent with previously reported findings for CHRNB2 and the occurrence of nausea and dizziness as a consequence of first smoking attempt in adolescents, and with the known neurophysiology of nausea. As nausea is the most common reason for discontinuance of varenicline, further pharmacogenetic investigations are warranted.
doi:10.1038/tpj.2011.19
PMCID: PMC3405554  PMID: 21606948
varenicline; nausea; smoking cessation; adherence
13.  Nicotine withdrawal sensitivity, linkage to chr6q26, and association of OPRM1 SNPs in the SMOking in FAMilies (SMOFAM) sample 
Background
Nicotine withdrawal symptoms are related to smoking cessation. A Rasch model has been used to develop a unidimensional sensitivity score representing multiple correlated measures of nicotine withdrawal. A previous autosome-wide screen identified a nonparametric linkage (NPL) log-likelihood ratio (LOD) score of 2.7 on chromosome 6q26 for the sum of nine withdrawal symptoms.
Methods
The objectives of these analyses are: a) to assess the influence of nicotine withdrawal sensitivity on relapse, b) conduct autosome-wide NPL analysis of nicotine withdrawal sensitivity among 158 pedigrees with 432 individuals with microsatellite genotypes and nicotine withdrawal scores, and c) explore family-based association of single nucleotide polymorphism (SNPs) at the mu opioid receptor (MOR) candidate gene (OPRM1) to nicotine withdrawal sensitivity in 172 nuclear pedigrees with 419 individuals with both SNP genotypes and nicotine withdrawal scores.
Results
An increased risk for relapse was associated with nicotine withdrawal sensitivity score (odds ratio, OR=1.25, 95% confidence interval, 95%CI=1.10,1.42). A maximal NPL LOD score of 3.15, suggestive of significant linkage, was identified at chr6q26 for nicotine withdrawal sensitivity. Evaluation of 18 OPRM1 SNPs via the family based association test (FBAT) with the nicotine withdrawal sensitivity score identified eight tagging SNPs with global P-values<0.05 and false discovery rate Q-values<0.06.
Conclusion
An increased risk of relapse, suggestive linkage at chr6q26, and nominally significant association with multiple OPRM1 SNPs was found with Rasch modeled nicotine withdrawal sensitivity score in a multiplex smoking pedigree sample. Future studies should attempt to replicate these findings and investigate the relationship between nicotine withdrawal symptoms and variation at OPRM1.
doi:10.1158/1055-9965.EPI-09-0960
PMCID: PMC3536862  PMID: 19959688
14.  Sensitivity to Secondhand Smoke Exposure Predicts Future Smoking Susceptibility 
Pediatrics  2011;128(2):254-262.
OBJECTIVE:
Susceptibility to cigarette smoking in tobacco-naive youth is a strong predictor of smoking initiation. Identifying mechanisms that contribute to smoking susceptibility provide information about early targets for smoking prevention. This study investigated whether sensitivity to secondhand smoke exposure (SHSe) contributes to smoking susceptibility.
PARTICIPANTS AND METHODS:
Subjects were high-risk, ethnically diverse 8- to 13-year-old subjects who never smoked and who lived with at least 1 smoker and who participated in a longitudinal SHSe reduction intervention trial. Reactions (eg, feeling dizzy) to SHSe were assessed at baseline, and smoking susceptibility was assessed at baseline and 3 follow-up measurements over 12 months. We examined the SHSe reaction factor structure, association with demographic characteristics, and prediction of longitudinal smoking susceptibility status.
RESULTS:
Factor analysis identified “physically unpleasant” and “pleasant” reaction factors. Reported SHSe reactions did not differ across gender or family smoking history. More black preteens reported feeling relaxed and calm, and fewer reported feeling a head rush or buzz compared with non-Hispanic white and Hispanic white counterparts. Longitudinally, 8.5% of subjects tracked along the trajectory for high (versus low) smoking susceptibility. Reporting SHSe as “unpleasant or gross” predicted a 78% reduction in the probability of being assigned to the high–smoking susceptibility trajectory (odds ratio: 0.22 [95% confidence interval: 0.05–0.95]), after covariate adjustment.
CONCLUSIONS:
Assessment of SHSe sensitivity is a novel approach to the study of cigarette initiation etiology and informs prevention interventions.
doi:10.1542/peds.2010-3156
PMCID: PMC3146357  PMID: 21746728
secondhand smoke; sensitivity; smoking susceptibility; trajectories; preteens
15.  Integrative Approach to Pain Genetics Identifies Pain Sensitivity Loci across Diseases 
PLoS Computational Biology  2012;8(6):e1002538.
Identifying human genes relevant for the processing of pain requires difficult-to-conduct and expensive large-scale clinical trials. Here, we examine a novel integrative paradigm for data-driven discovery of pain gene candidates, taking advantage of the vast amount of existing disease-related clinical literature and gene expression microarray data stored in large international repositories. First, thousands of diseases were ranked according to a disease-specific pain index (DSPI), derived from Medical Subject Heading (MESH) annotations in MEDLINE. Second, gene expression profiles of 121 of these human diseases were obtained from public sources. Third, genes with expression variation significantly correlated with DSPI across diseases were selected as candidate pain genes. Finally, selected candidate pain genes were genotyped in an independent human cohort and prospectively evaluated for significant association between variants and measures of pain sensitivity. The strongest signal was with rs4512126 (5q32, ABLIM3, P = 1.3×10−10) for the sensitivity to cold pressor pain in males, but not in females. Significant associations were also observed with rs12548828, rs7826700 and rs1075791 on 8q22.2 within NCALD (P = 1.7×10−4, 1.8×10−4, and 2.2×10−4 respectively). Our results demonstrate the utility of a novel paradigm that integrates publicly available disease-specific gene expression data with clinical data curated from MEDLINE to facilitate the discovery of pain-relevant genes. This data-derived list of pain gene candidates enables additional focused and efficient biological studies validating additional candidates.
Author Summary
The mechanisms underlying pain are incompletely understood, and are hard to study due to the subjective and complex nature of pain. From a genetics perspective, the discovery of genes relevant for the processing of pain in humans has been slow and genome-wide association studies have not been successful in yielding significantly associated variants. Targeted approaches examining specific candidate genes may be more promising. We present a novel integrative approach that combines publicly available molecular data and automatically extracted knowledge regarding pain contained in the literature to assist the discovery of novel pain genes. We prospectively validated this approach by demonstrating a significant association between several newly identified pain gene candidates and sensitivity to cold pressor pain.
doi:10.1371/journal.pcbi.1002538
PMCID: PMC3369906  PMID: 22685391
16.  Adherence to Varenicline in the COMPASS Smoking Cessation Intervention Trial 
Nicotine & Tobacco Research  2011;13(5):361-368.
Introduction:
Patient adherence to smoking cessation medications can impact their effectiveness. It is important to understand the extent to which prescribed medications are actually taken by smokers, how this influences smoking cessation outcomes, and what factors may influence adherence.
Methods:
Smokers recruited from a large health plan were randomized to receive different modes of cessation counseling in combination with varenicline (Swan, G. E., McClure, J. B., Jack, L. M., Zbikowski, S. M., Javitz, H. S., Catz, S. L., et al. 2010.Behavioral counseling and varenicline treatment for smoking cessation. American Journal of Preventive Medicine, 38, 482–490). One thousand one hundred and sixty-one participants were mailed a 28-day varenicline supply when they set a quit date and were able to request up to two refills from the health plan pharmacy at no cost. Pharmacy fill records were obtained and telephone surveys completed at baseline, 21 days, 12 weeks, and 6 months post target quit date.
Results:
Good adherence to varenicline (≥80% of days taken) was associated with a twofold increase in 6-month quit rates compared with poor adherence (52% vs. 25%). Smokers were more likely than nonsmokers to stop varenicline early. Purposeful nonadherence was associated with smoking at 12 weeks and was predicted in multivariate analyses by age, gender, adherence self-efficacy, and initial medication side effect severity.
Conclusions:
Innovative methods for increasing adherence to smoking cessation medications are needed, particularly early in the quit process. Simple metrics of adherence such as number of days cessation medication is taken can and should be routinely incorporated in effectiveness trials and reported to advance future attempts to understand and reduce nonadherence.
doi:10.1093/ntr/ntr003
PMCID: PMC3082504  PMID: 21350041
17.  Association of the Calcyon Neuron-Specific Vesicular Protein Gene (CALY) With Adolescent Smoking Initiation in China and California 
American Journal of Epidemiology  2011;173(9):1039-1048.
Although previous investigations have indicated a role for genetic factors in smoking initiation, the underlying genetic mechanisms are still unknown. In 2,339 adolescents from a Chinese Han population in the Wuhan Smoking Prevention Trial (Wuhan, China, 1998–1999), the authors explored the association of 57 genes in the dopamine pathway with smoking initiation. Using a conservative approach for declaring significance, positive findings were further examined in an independent sample of 603 Caucasian adolescents followed for up to 10 years as part of the Children's Health Study (Southern California, 1993–2009). The authors identified 1 single nucleotide polymorphism (rs2298122) in the calcyon neuron-specific vesicular protein gene (CALY) that was positively associated with smoking initiation in females (odds ratio = 2.21, 95% confidence interval: 1.49, 3.27; P = 8.4 × 10−5) in the Wuhan Smoking Prevention Trial cohort, and they replicated the association in females from the Children's Health Study cohort (hazard rate ratio = 2.05, 95% confidence interval: 1.27, 3.31; P = 0.003). These results suggest that the CALY gene may influence smoking initiation in adolescents, although the potential roles of underlying psychological characteristics that may be components of the smoking-initiation phenotype, such as impulsivity or novelty-seeking, remain to be explored.
doi:10.1093/aje/kwq471
PMCID: PMC3121219  PMID: 21415033
adolescent; dopamine; genetic association studies; smoking
18.  Sensitivity to Secondhand Smoke Exposure Predicts Smoking Susceptibility in 8 to 13 Year-Old Never Smokers 
Purpose
To investigate the sensitivity to secondhand smoke exposure (SHSe) in preteens age 8 to 13 who have never smoked, and to determine whether SHSe sensitivity predicts smoking susceptibility.
Methods
We assessed sensitivity to SHSe using reactions commonly used for assessment of sensitivity to the first smoked cigarette (e.g., feeling dizzy), and investigated the factor structure of these reactions for the purpose of data reduction. We examined the association of each reaction measure and summary score with demographic characteristics and with smoking susceptibility, using logistic regression and ordinal logistic regression.
Results
One factor was identified that captured physical/unpleasant reactions. Older preteens and preteens with more highly educated parents reported fewer reactions to SHSe. More African American preteens reported feeling relaxed or calm compared to all other racial/ethnic groups. Experiencing physical/unpleasant reactions to SHSe predicted lower risk for smoking susceptibility.
Conclusions
This was the first study to extend analytical methodology for sensitivity to active smoking to sensitivity to SHSe in youth who have never smoked. Results suggest a desensitization process with age and lower sensitivity to some reactions in preteens from more highly educated households. Preteens who have more aversive experience s with SHSe tend to be less susceptible to smoking than those who experience fewer aversive reactions. Assessment of sensitivity to SHSe is a novel approach to the study of cigarette use etiology and may contribute to better prediction of smoking initiation.
doi:10.1016/j.jadohealth.2010.06.016
PMCID: PMC3052940  PMID: 21338893
preteens; secondhand smoke; reactions; sensitivity; smoking susceptibility
19.  Cost-effectiveness of varenicline and three different behavioral treatment formats for smoking cessation 
There is a lack of evidence of the relative cost-effectiveness of proactive telephone counseling (PTC) and Web-based delivery of smoking cessation services in conjunction with pharmacotherapy. We calculated the differential cost-effectiveness of three behavioral smoking cessation modalities with varenicline treatment in a randomized trial of current smokers from a large health system. Eligible participants were randomized to one of three smoking cessation interventions: Web-based counseling (n=401), PTC (n=402), or combined PTC-Web counseling (n=399). All participants received a standard 12-week course of varenicline. The primary outcome was a 7-day point prevalent nonsmoking at the 6month follow-up. The Web intervention was the least expensive followed by the PTC and PTC-Web groups. Costs per additional 6-month nonsmoker and per additional lifetime quitter were $1,278 and $2,601 for Web, $1,472 and $2,995 for PTC, and $1,617 and $3,291 for PTC-Web. Cost per life-year (LY) and quality-adjusted life-year (QALY) saved were $1,148 and $1,136 for Web, $1,320 and $1,308 for PTC, and $1,450 and $1,437 for PTC-Web. Based on the cost per LY and QALY saved, these interventions are among the most cost-effective life-saving medical treatments. Web, PTC, and combined PTC-Web treatments were all highly cost-effective, with the Web treatment being marginally more cost-effective than the PTC or combined PTC-Web treatments.
doi:10.1007/s13142-010-0009-8
PMCID: PMC3124766  PMID: 21731592
Smoking cessation; Varenicline; Cost-effectiveness; Quality-adjusted life-years saved; Behavioral intervention
20.  Resequencing of Nicotinic Acetylcholine Receptor Genes and Association of Common and Rare Variants with the Fagerström Test for Nicotine Dependence 
Neuropsychopharmacology  2010;35(12):2392-2402.
Common single-nucleotide polymorphisms (SNPs) at nicotinic acetylcholine receptor (nAChR) subunit genes have previously been associated with measures of nicotine dependence. We investigated the contribution of common SNPs and rare single-nucleotide variants (SNVs) in nAChR genes to Fagerström test for nicotine dependence (FTND) scores in treatment-seeking smokers. Exons of 10 genes were resequenced with next-generation sequencing technology in 448 European-American participants of a smoking cessation trial, and CHRNB2 and CHRNA4 were resequenced by Sanger technology to improve sequence coverage. A total of 214 SNP/SNVs were identified, of which 19.2% were excluded from analyses because of reduced completion rate, 73.9% had minor allele frequencies <5%, and 48.1% were novel relative to dbSNP build 129. We tested associations of 173 SNP/SNVs with the FTND score using data obtained from 430 individuals (18 were excluded because of reduced completion rate) using linear regression for common, the cohort allelic sum test and the weighted sum statistic for rare, and the multivariate distance matrix regression method for both common and rare SNP/SNVs. Association testing with common SNPs with adjustment for correlated tests within each gene identified a significant association with two CHRNB2 SNPs, eg, the minor allele of rs2072660 increased the mean FTND score by 0.6 Units (P=0.01). We observed a significant evidence for association with the FTND score of common and rare SNP/SNVs at CHRNA5 and CHRNB2, and of rare SNVs at CHRNA4. Both common and/or rare SNP/SNVs from multiple nAChR subunit genes are associated with the FTND score in this sample of treatment-seeking smokers.
doi:10.1038/npp.2010.120
PMCID: PMC3055324  PMID: 20736995
Fagerström test for nicotine dependence; single-nucleotide polymorphism; candidate gene association scan; treatment-seeking smokers; addiction & substance abuse; clinical pharmacology; clinical trials; neurogenetics; acetylcholine
22.  Incident Sleep Disordered Breathing in Old Age 
Background.
Little is known about progression of and risk factors for sleep disordered breathing (SDB) in old age. We prospectively examined elderly volunteers to understand how changes in body weight are related to SDB for a period of 20–30 years.
Methods.
Participants were 30 surviving members of a community-based cohort (mean entry age = 57.8) studied over a median follow-up of 23.4 years. SDB was quantified as the apnea–hypopnea index (AHI) via in-lab polysomnography from 215 nights, representing 733.3 person-years of follow-up. Weights were recorded in kilograms. We used linear regression to derive individual trajectories of AHI and weight regressed on time.
Results.
Individuals had relatively low AHI (X = 2.3 [SD = 3.5]) and body mass index (kg/m2; X = 24.6 [SD = 4.6]) at entry. Rates of change in AHI were characterized by positive slopes and linear increases by least squares regression. Mean rate of change was +0.43 events per hour per year, a 3.3% yearly increase relative to the maximum AHI observed for each case. Within individuals, curve fitting indicated statistically significant AHI increases associated not only with increases, but also decreases, in weight.
Conclusions.
Rates of increase in AHI were larger than for aging reported for other organ systems (eg, autonomic, musculoskeletal, and respiratory), possibly reflecting complex mechanistic determination of SDB in old age. Association between decreased weight and increased SDB with advancing years represents an important “proof of concept,” perhaps compatible with failure to maintain airway patency during sleep as a component of generalized muscle weakness in old age.
doi:10.1093/gerona/glq071
PMCID: PMC2920579  PMID: 20498222
Sleep disordered breathing; Aging; Body weight; Longitudinal study
23.  Measuring Addiction Propensity and Severity: The Need for a New Instrument 
Drug and alcohol dependence  2010;111(1-2):4-12.
Drug addiction research requires but lacks a valid and reliable way to measure both the risk (propensity) to develop addiction and the severity of manifest addiction. This paper argues for a new measurement approach and instrument to quantify propensity to and severity of addiction, based on the testable assumption that these constructs can be mapped onto the same dimension of liability to addiction. The case for this new direction becomes clear from a critical review of empirical data and the current instrumentation. The many assessment instruments in use today have proven utility, reliability, and validity, but they are of limited use for evaluating individual differences in propensity and severity. The conceptual and methodological shortcomings of instruments currently used in research and clinical practice can be overcome through the use of new technologies to develop a reliable, valid, and standardized assessment instrument(s) to measure and distinguish individual variations in expression of the underlying latent trait(s) that comprises propensity to and severity of drug addiction. Such instrumentation would enhance our capacity for drug addiction research on linkages and interactions among familial, genetic, psychosocial, and neurobiological factors associated with variations in propensity and severity. It would lead to new opportunities in substance abuse prevention, treatment, and services research, as well as in interventions and implementation science for drug addiction.
doi:10.1016/j.drugalcdep.2010.03.011
PMCID: PMC2930133  PMID: 20462706
tobacco; cannabis assessment; individual differences; adolescents
24.  Smoking Outcome by Psychiatric History after Behavioral and Varenicline Treatment 
Treatment outcomes were compared across smokers enrolled in the COMPASS cessation trial with (PH+, n = 271) and without (PH-, n = 271) a diagnosis of psychiatric history based on medical record evidence of anxiety, depression, psychotic disorder, or bipolar disorder Everyone received behavioral counseling plus varenicline and was followed for 6 months post-quit date. PH+ smokers took varenicline for fewer days on average (59.4 vs. 68.5, P ≤ .01), but did not differ in their use of behavioral treatment. PH+ smokers were more likely to report anxiety and depression, but side-effect intensity ratings did not differ after adjusting for multiple comparisons. Overall, all side-effects were rated as moderate intensity or less. Groups had similar 30 day abstinence rates at 6 months (31.5% PH+ vs. 35.4% PH-, P = .35). In sum, having a psychiatric diagnosis in this trial did not predict worse treatment outcome or worse treatment side-effects.
doi:10.1016/j.jsat.2010.03.007
PMCID: PMC2860053  PMID: 20363092
varenicline; smoking cessation; depression; anxiety; psychiatric illness; side-effects
25.  Behavioral Counseling and Varenicline Treatment for Smoking Cessation 
Background
Smoking remains the primary preventable cause of death and illness in the U.S. Effective, convenient treatment programs are needed to reduce smoking prevalence.
Purpose
This study compared the effectiveness of three modalities of a behavioral smoking-cessation program in smokers using varenicline.
Methods
Current treatment seeking smokers (n=1202) were recruited from a large healthcare organization between October 2006 and October 2007. Eligible participants were randomized to one of three smoking-cessation interventions: web-based counseling (n=401), proactive telephone-based counseling (PTC; n=402), or combined PTC and web counseling (n=399). All participants received a standard 12-week FDA-approved course of varenicline. Self-report determined the primary outcomes (7-day point prevalent abstinence at 3- and 6-month follow-up), the number of days varenicline was taken, and treatment-related symptoms. Behavioral measures determined utilization of both the web- and phone-based counseling.
Results
Intent-to-treat analyses revealed relatively high percentages of abstinence at 3 months (38.9%, 48.5%, 43.4%) and at 6 months (30.7%, 34.3%, 33.8%) for the web, PTC, and PTC web groups, respectively. The PTC group had a significantly higher percentage of abstinence than the web group at 3 months, OR=1.48, 95% CI 1.12–1.96, but no between-group differences in abstinence outcomes were seen at 6 months.
Conclusions
Phone counseling had greater treatment advantage for early cessation and appeared to increase medication adherence, but the absence of differences at 6 months suggests that any of the interventions hold promise when used in conjunction with varenicline.
doi:10.1016/j.amepre.2010.01.024
PMCID: PMC2879135  PMID: 20409497

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