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Biomedical subjects

Paul W McDonald

Publications and source records attributed to Paul W McDonald.

18 recordsLinked to original sources
PubMed2006

The Heaviness of Smoking Index as a predictor of smoking cessation in Canada.

Nicotine addiction is believed to be a major impediment for many people in quitting smoking, but measures of nicotine dependence such as the Heaviness of Smoking Index (HSI) have had mixed success in predicting cessation. Using the National Population Health Survey, the relationship between HSI at baseline in cycle 2 (1996-1997) and successful smoking cessation at cycle 3 (1998-1999) and cycle 4 (2000-2001) was examined in 2938 Canadian adult smokers. A logistic regression model was developed for HSI as a predictor of smoking cessation, and then tested for interaction and confounding. The odds ratio of not smoking in cycle 3 was 2.08 (95% CI: 1.51, 2.86; p<0.001) for low HSI (<2) compared to medium HSI. When the period of follow-up was extended, individuals with both high (>4) HSI scores (OR 2.16; 95% CI: 1.11, 4.21; p=0.02) and low scores (OR 2.22; 95% CI: 1.41, 3.49) had higher odds of not smoking at both cycle 3 and cycle 4 than those with medium HSI scores. The likelihood of reporting cessation was higher than expected in the Canadian population among highly dependent smokers, particularly among older smokers, those with middle or greater income adequacy, and those with no intention to quit smoking. There were no substantial changes to the results when those lost-to-follow-up were treated as continuing smokers. These findings indicate that nicotine dependence is only one factor in succeeding at a quit attempt. Individual and population strategies for smoking cessation may need to consider other influences such as cognitive, affective and environmental factors.

Adolescent↗
PubMed2006

Dopamine signaling architecture in Caenorhabditis elegans.

AIMS: In this review, we highlight the identification and analysis of molecules orchestrating dopamine (DA) signaling in the nematode Caenorhabditis elegans, focusing on recent characterizations of DA transporters and receptors. METHODS: We illustrate the isolation and characterization of molecules important for C. elegans DA synthesis, packaging, reuptake and signaling and examine how mutations in these proteins are being exploited through in vitro and in vivo paradigms to yield novel insights of protein structure, DA signaling pathways and DA-supported behaviors. RESULTS: DA signaling in the worm, as in man, arises by synaptic and nonsynaptic release from a small number of cells that exert modulatory control over a larger network underlying C. elegans behavior. CONCLUSIONS: The C. elegans model system offers unique opportunities to elucidate ill-defined pathways that support DA release, inactivation, and signaling in addition to clarifying mechanisms of DA-mediated behavioral plasticity. Further use of the model offers prospects for the identification of novel genes and proteins whose study may yield benefits for DA-supported neural disorders in man.

Amino Acid Sequence↗
PubMed2006

A multi-level analysis examining how smoking friends, parents, and older students in the school environment are risk factors for susceptibility to smoking among non-smoking elementary school youth.

The purpose of this study was to examine how social models for smoking are related to smoking susceptibility among a sample of non-smoking elementary school students. The Tobacco Module of the School Health Action, Planning and Evaluation System (SHAPES) was administered to 6,431 students (grades 6 to 8) in 57 elementary schools in the province of Ontario, Canada. Multi-level logistic regression analysis was used to examine how smoking friends, parents, and the prevalence of smoking among grade 8 students at a school were related to smoking susceptibility among the 2,478 non-smoking grade 6 and 7 students. Findings indicate that non-smoking grade 6 and 7 students are more likely to be susceptible to smoking if they have (a) smoking friends, (b) a mother who smokes, or (c) two or more close friends who smoke and attend a school with a relatively high smoking rate among the grade 8 students. Sub-populations of non-smoking youth may be at increased risk for smoking because of the elementary school they attend. Future school-based smoking prevention programs might benefit from targeting prevention programming activities to the schools that are putting students at the greatest risk for smoking.

Adolescent↗
PubMed2006

Determinants of physical activity after hospitalization for coronary artery disease: the Tracking Exercise After Cardiac Hospitalization (TEACH) Study.

BACKGROUND: Little is known about physical activity levels in patients with coronary artery disease (CAD) who are not engaged in cardiac rehabilitation. We explored the trajectory of physical activity after hospitalization for CAD, and examined the effects of demographic, medical, and activity-related factors on the trajectory. DESIGN: A prospective cohort study. METHODS: A total of 782 patients were recruited during CAD-related hospitalization. Leisure-time activity energy expenditure (AEE) was measured 2, 6 and 12 months later. Sex, age, education, reason for hospitalization, congestive heart failure (CHF), diabetes, and physical activity before hospitalization were assessed at recruitment. Participation in cardiac rehabilitation was measured at follow-up. RESULTS: AEE was 1948+/-1450, 1676+/-1290, and 1637+/-1486 kcal/week at 2, 6 and 12 months, respectively. There was a negative effect of time from 2 months post-hospitalization on physical activity (P<0.001). Interactions were found between age and time (P=0.012) and education and time (P=0.001). Main effects were noted for sex (men more active than women; P<0.001), CHF (those without CHF more active; P<0.01), diabetes (those without diabetes more active; P<0.05), and previous level of physical activity (those active before hospitalization more active after; P<0.001). Coronary artery bypass graft patients were more active than percutaneous coronary intervention (PCI) patients (P=0.033). CONCLUSIONS: Physical activity levels declined from 2 months after hospitalization. Specific subgroups (e.g. less educated, younger) were at greater risk of decline and other subgroups (e.g. women, and PCI, CHF, and diabetic patients) demonstrated lower physical activity. These groups need tailored interventions.

Adult↗
PubMed2005

A genetic screen in Caenorhabditis elegans for dopamine neuron insensitivity to 6-hydroxydopamine identifies dopamine transporter mutants impacting transporter biosynthesis and trafficking.

The presynaptic dopamine (DA) transporter (DAT) is a major determinant of synaptic DA inactivation, an important target for psychostimulants including cocaine and amphetamine, and a mediator of DA neuron vulnerability to the neurotoxins 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenylpyridinium ion. To exploit genetic approaches for the study of DATs and neural degeneration, we exploited the visibility of green fluorescent protein (GFP)-tagged DA neurons in transgenic nematodes to implement a forward genetic screen for suppressors of 6-OHDA sensitivity. In our initial effort, we identified three novel dat-1 alleles conferring 6-OHDA resistance. Two of the dat-1 alleles derive from point mutations in conserved glycine residues (G55, G90) in contiguous DAT-1 transmembrane domains (TM1 and TM2, respectively), whereas the third allele results in altered translation of the transporter's COOH terminus. Our studies reveal biosynthetic, trafficking and functional defects in the DAT-1 mutants, exhibited both in vitro and in vivo. These studies validate a forward genetic approach to the isolation of DA neuron-specific toxin suppressors and point to critical contributions of the mutated residues, as well as elements of the DAT-1 COOH terminus, to functional expression of catecholamine transporters in neurons.

Adrenergic Agents↗
PubMed2005

What smoking cessation approaches will young smokers use?

The purpose of this study was to examine the attitudes of youth smokers toward nine common smoking cessation approaches. Attitudes were examined among 3660 youth smokers who intended to quit smoking. The majority of youth smokers report that they would never use the smoking cessation approaches that are commonly recommended for youth populations. The approaches that were appealing to youth are quitting on their own and using the advice of friends. Future initiatives need to more effectively communicate to youth the benefits of existing cessation approaches, make existing interventions more appealing, or develop new approaches that address youth needs.

Adolescent↗
PubMed2005

Social modeling in the school environment, student characteristics, and smoking susceptibility: a multi-level analysis.

PURPOSE: To examine how social models in the school environment and individual student characteristics are related to smoking susceptibility. METHODS: Using data from the School Smoking Profile Project, multi-level logistic regression analysis was used to identify school and student characteristics related to smoking susceptibility among 6679 never smokers from 29 secondary schools in Ontario, Canada. RESULTS: If a nonsmoking student attended a school where there was student smoking on the school periphery, he or she was less likely to be susceptible to smoking (OR 0.71, 95% CI 0.57-0.89). A significant contextual interaction between the smoking on the school periphery and friends' disapproval of smoking was identified (beta = 0.68 [0.23], p < .01]; students with friends who disapprove of smoking were more likely to be susceptible to smoking if they attended a school with student smoking on the school periphery. CONCLUSION: Nonsmoking students who attend a school with student smoking on the school periphery are at an increased risk for being susceptible to smoking if they have friends who disapprove of smoking. Future school-based smoking prevention programs might benefit from targeting both individual students and entire schools with programming activities.

Adolescent↗
PubMed2005

Senior student smoking at school, student characteristics, and smoking onset among junior students: a multilevel analysis.

BACKGROUND: Current research on the etiology of tobacco use has largely focused on identifying the influential psychosocial characteristics of individual students; the influences of characteristics in the school environment are generally ignored. The purpose of this study was to simultaneously examine how school and individual student characteristics were related to smoking onset. METHOD: Multilevel logistic regression analysis was used to examine how the senior student smoking rate at a school and the psychosocial characteristics of students were able to differentiate tried-once smokers from experimental smokers in a sample of 4850 grade 9, 10, and 11 students from the School Smoking Profile (SSP) project. RESULTS: Each 1% increase in smoking rate among high school seniors increased the odds that a junior student was an experimental smoker vs. a tried-once smoker (OR 1.07, 95% CI 1.03-1.12). A significant contextual interaction was identified where the senior student smoking rate at a school moderates the negative influence of having close friends who smoke. Influential student characteristics were also identified. CONCLUSIONS: The smoking prevalence of older students at a school is directly related to smoking onset among younger students at that school. Prevention programs should target schools that put students at-risk.

Adolescent↗
PubMed2005

Recruitment of physician offices for an office-based adolescent smoking cessation study.

Physician office settings play an important role in tobacco cessation intervention. However, few tobacco cessation trials are conducted at these sites, in part because of the many challenges associated with recruiting community physician offices into research. The present study identified and implemented strategies for recruiting physician offices into a randomized clinical trial of tobacco screening and cessation interventions with adolescent patients. A total of 30 community physicians participated in focus groups to elicit their perceptions of facilitators of and barriers to initial engagement of physician practices and the subsequent enrollment of the practices in long-term research projects. Physicians identified facilitators such as (a) the involvement of office staff in the recruitment process and (b) on-site presentations of the study's background and aims. Some of the barriers identified were time commitment concerns and the lack of incentives in exchange for participation. These focus group findings were then integrated with theory-based and empirically driven recruitment strategies for a 12-month randomized tobacco intervention trial with adolescent patients. Of 185 office practices approached to participate (screened from a pool of 273 practices), 103 agreed to on-site presentations of the study. Subsequently, almost all of the practices (101) that received the presentation agreed to enroll in the study. Conclusions are that (a) recruitment is a multicomponent process, (b) the processes of communication, engagement, and enrollment must be carefully planned and implemented to achieve maximal results, and (c) the development of effective strategies for recruiting health care provider practices presents an important infrastructure for testing adolescent smoking cessation interventions.

Adolescent↗
PubMed2004

Dopamine transporters depolarize neurons by a channel mechanism.

Neurotransmitter transporters generate larger currents than expected if one assumes fixed stoichiometry models. It remains controversial, however, whether these depolarizing currents arise from high density and rapid turnover rates of a classical transporter, or whether transporters exhibit bona fide channel behavior. Although heterologously expressed transporters show single-channel behavior and noise analysis in native cells strongly suggests channel behavior, no directly observed single-channel events associated with transporters have been reported thus far in native cells. We describe single-channel events arising directly from the Caenorhabditis elegans dopamine transporter (DAT-1) as evidenced by DA-induced channel activity blocked by a high-affinity DAT-1 inhibitor, increased channel activity in neurons that overexpress DAT-1, and loss of channels in dat-1 knockout neurons. Our data indicate that authentic transporter channels underlie depolarizing whole-cell currents. Thus, DA transporters not only transport DA but also exhibit a channel mode of conduction that directly modulates membrane potential and neuronal function.

Animals↗
PubMed2004

Graphic Canadian cigarette warning labels and adverse outcomes: evidence from Canadian smokers.

OBJECTIVES: We assessed the impact of graphic Canadian cigarette warning labels. METHODS: We used a longitudinal telephone survey of 616 adult smokers. RESULTS: Approximately one fifth of participants reported smoking less as a result of the labels; only 1% reported smoking more. Although participants reported negative emotional responses to the warnings including fear (44%) and disgust (58%), smokers who reported greater negative emotion were more likely to have quit, attempted to quit, or reduced their smoking 3 months later. Participants who attempted to avoid the warnings (30%) were no less likely to think about the warnings or engage in cessation behavior at follow-up. CONCLUSIONS: Policymakers should not be reluctant to introduce vivid or graphic warnings for fear of adverse outcomes.

Adult↗
PubMedDate not supplied

A multilevel analysis examining the relationship between social influences for smoking and smoking onset.

OBJECTIVES: To examine how older smoking peers at school and the smoking behavior of friends and family members are related to youth smoking. METHODS: The School Smoking Profile was used to collect data on tobacco use and determinants of tobacco use from 22,091 students from 29 secondary schools in Ontario, Canada. Correlates of occasional and regular smoking were examined using multilevel logistic regression analyses. RESULTS: Students are at increased risk for smoking if they (a) have smoking friends, (b) have smoking family members, and (c) attend a school with a relatively high senior-student smoking rate. CONCLUSION: These findings suggest that prevention programs should target both at-risk schools and at-risk students.

Adolescent↗
PubMedDate not supplied

Telephone counseling for population-based smoking cessation.

OBJECTIVES: To examine the options for use, efficiency, and effectiveness for structuring a population-based telephone smoking-cessation service. METHODS: Callers (n=632) to a 1-800 number were randomized in a 2 (50-minute counseling with 2/6 calls) x 2 (pamphlet/booklet) design with print only control. RESULTS: Six-month use of the service was 0.6% of adult smokers. Service promotion cost 31.02 dollars/person. Telephone counseling resulted in higher continued abstinence (5%) than did print only (1%), P<.05. Amount of print and calls did not increase cessation. Six calls resulted in lower completion rates than 2 (22% vs 56%, P<.05). CONCLUSIONS: For planning, consider 1% use, low-cost promotion, pamphlet, 50-minute initial counseling plus 2 follow-ups, and minimize call-attempts.

Adolescent↗
PubMedDate not supplied

A low-cost, practical method for increasing smokers' interest in smoking cessation programs.

BACKGROUND: Low participation rates reduce the public health impact of smoking cessation programs. Two barriers for improving participation are the cost of media campaigns and the proportion of smokers motivated to quit smoking. The objective of this study was to examine the feasibility of using classified newspaper ads and messages aimed at each stage of change to enhance participation in smoking cessation programs. METHODS: Three classified ads were run concurrently in a local daily newspaper for five consecutive days. The ads were designed to engage smokers in each of Prochaska's five stages of change. Each ad invited smokers or former smokers to call the local health department to participate in a paid focus group to design a new health department program. RESULTS: Calls were received from 181 eligible smokers, including 124 who provided data for the study. Thirty-seven, 34, and 29 percent of smoking respondents were in precontemplation, contemplation and preparation respectively. Half of ex-smokers were in the action stage. Ads cost 174 dollars (Cdn), thus the cost per recruit was less than a dollar. CONCLUSION: Classified ads can recruit smokers from all stages of change. Compared to traditional mass media, classified ads may also be a highly cost-efficient promotional strategy. Results provide justification for further research.

Adult↗
PubMedDate not supplied

The impact of cigarette warning labels and smoke-free bylaws on smoking cessation: evidence from former smokers.

BACKGROUND: To effectively address the health burden of tobacco use, tobacco control programs must find ways of motivating smokers to quit. The present study examined the extent to which former smokers' motivation to quit was influenced by two tobacco control policies recently introduced in the Waterloo Region: a local smoke-free bylaw and graphic cigarette warning labels. METHODS: A random digit-dial telephone survey was conducted with 191 former smokers in southwestern Ontario, Canada in October 2001. Former smokers who had quit in the previous three years rated the factors that influenced their decision to quit and helped them to remain abstinent. RESULTS: Thirty-six percent of former smokers cited smoke-free policies as a motivation to quit smoking. Former smokers who quit following the introduction of a total smoke-free bylaw were 3.06 (CI95 = 1.02-9.19) times more likely to cite smoking bylaws as a motivation to quit, compared to former smokers who quit prior to the bylaw. A total of 31% participants also reported that cigarette warning labels had motivated them to quit. Former smokers who quit following the introduction of the new graphic warning labels were 2.78 (CI9 = 1.20-5.94) times more likely to cite the warnings as a quitting influence than former smokers who quit prior to their introduction. Finally, 38% of all former smokers surveyed reported that smoke-free policies helped them remain abstinent and 27% reported that warning labels helped them do so. CONCLUSION: More stringent smoke-free and labelling policies were associated with a greater impact upon motivations to quit.

Adult↗
PubMedDate not supplied

An examination of the relationship between municipal smoke-free bylaw strength and the odds of being a former smoker.

OBJECTIVE: The purpose of this study was to examine the relationship between municipal no-smoking bylaw strength and the odds of being a former smoker. METHODS: Data from Statistics Canada's Canadian Community Health Survey (Cycle 1.1, 2001) and a validated bylaw scoring scheme (2001) were linked and analyzed to determine whether the odds of being a former smoker were related to the strength of no-smoking bylaws in municipalities that had been matched for potentially confounding factors. The sample consisted of ever smokers (current and former smokers) from Ontario municipalities that did not have a no-smoking bylaw, or had a fully implemented no-smoking bylaw before September 2000. Data were analyzed using a Mantel-Haenszel Chi-square test and a logistic regression. RESULTS: The results from the Mantel-Haenszel (OR = 0.94, 95% CI 0.80-1.12) and logistic regression analyses (OR = 0.95, 95% CI 0.82-1.11) did not find support for the hypothesis that living in a municipality with a strong no-smoking bylaw would increase the odds of being a former smoker. DISCUSSION: Findings were inconsistent with previous studies that have found no-smoking restrictions in homes, workplaces and public places increase the odds that smokers attempt and succeed in quitting smoking. However, results from this study must be interpreted with caution because of the cross-sectional design and limited control of potentially important covariates.

Adult↗
PubMedDate not supplied

Are the recommended taxonomies for the stages of youth smoking onset consistent with youth's perceptions of their smoking status?

BACKGROUND: To examine if the recommended taxonomies for the stages of youth smoking onset are aligned with the beliefs of smoking youth. METHODS: The SHAPES Tobacco Module was administered to 23,047 students (grades 9 to 13) in a convenience sample of 29 secondary schools during the 2000-2001 school year in the province of Ontario, Canada. Cross-tabs were used to compare a student's self-perceived smoking status to their smoking status as determined with the currently recommended stage taxonomies for smoking behaviour. RESULTS: The majority of students classified as regular smokers (52.4%) and experimental smokers (98.9%) did not actually consider themselves to be smokers. Self-reported smoking status appeared to be relatively consistent for the never smoker and established smoker categories. CONCLUSIONS: Additional research is required to develop stage taxonomies that are aligned with the self-perceptions of non-established youth smokers.

Adolescent↗