IL-2, IL-7, and IL-15: Multistage regulators of CD4(+) T helper cell differentiation.

Cytokines represent a class of environmental factors that are critical drivers of immune cell development. Cytokines of the common gamma-chain family, including interleukin (IL)-2, IL-7, and IL-15, have been the subject of intense experimental scrutiny and have well-defined roles as regulators of diverse immune cell types including CD4(+) T helper cells. Because of their pleiotropic effects on T-cell development and function, researchers and clinicians have attempted to harness the capabilities of these cytokines for therapeutic benefit. In this review, we summarize the recent progress in our understanding of the molecular mechanisms underlying the effects of these cytokines on CD4(+) T cell development and briefly discuss how these immunomodulatory cytokines are being used in efforts to treat human disease.

IL-7 signalling represses Bcl-6 and the TFH gene program.

The transcriptional repressor Bcl-6 is linked to the development of both CD4(+) T follicular helper (TFH) and central memory T (TCM) cells. Here, we demonstrate that in response to decreased IL-2 signalling, T helper 1 (TH1) cells upregulate Bcl-6 and co-initiate TFH- and TCM-like gene programs, including expression of the cytokine receptors IL-6Rα and IL-7R. Exposure of this potentially bi-potent cell population to IL-6 favours the TFH gene program, whereas IL-7 signalling represses TFH-associated genes including Bcl6 and Cxcr5, but not the TCM-related genes Klf2 and Sell. Mechanistically, IL-7-dependent activation of STAT5 contributes to Bcl-6 repression. Importantly, antigen-specific IL-6Rα(+)IL-7R(+) CD4(+) T cells emerge from the effector population at late time points post influenza infection. These data support a novel role for IL-7 in the repression of the TFH gene program and evoke a divergent regulatory mechanism by which post-effector TH1 cells may contribute to long-term cell-mediated and humoral immunity.

Bcl-6 directly represses the gene program of the glycolysis pathway.

Despite the increasing knowledge of the molecular events that induce the glycolysis pathway in effector T cells, very little is known about the transcriptional mechanisms that dampen the glycolysis program in quiescent cell populations such as memory T cells. Here we found that the transcription factor Bcl-6 directly repressed genes encoding molecules involved in the glycolysis pathway, including Slc2a1, Slc2a3, Pkm and Hk2, in type 1 helper T cells (TH1 cells) exposed to low concentrations of interleukin 2 (IL-2). Thus, Bcl-6 had a role opposing the IL-2-sensitive glycolytic transcriptional program that the transcription factors c-Myc and HIF-1α promote in effector T cells. Additionally, the TH1 lineage-specifying factor T-bet functionally antagonized the Bcl-6-dependent repression of genes encoding molecules in the glycolysis pathway, which links the molecular balance of these two factors to regulation of the metabolic gene program.

Analysis of human rotaviruses from a single location over an 18-year time span suggests that protein coadaption influences gene constellations.

UNLABELLED: Rotaviruses (RVs) are 11-segmented, double-stranded RNA viruses that cause severe gastroenteritis in children. In addition to an error-prone genome replication mechanism, RVs can increase their genetic diversity by reassorting genes during host coinfection. Such exchanges allow RVs to acquire advantageous genes and adapt in the face of selective pressures. However, reassortment may also impose fitness costs if it unlinks genes/proteins that have accumulated compensatory, coadaptive mutations and that operate best when kept together. To better understand human RV evolutionary dynamics, we analyzed the genome sequences of 135 strains (genotype G1/G3/G4-P[8]-I1-C1-R1-A1-N1-T1-E1-H1) that were collected at a single location in Washington, DC, during the years 1974 to 1991. Intragenotypic phylogenetic trees were constructed for each viral gene using the nucleotide sequences, thereby defining novel allele level gene constellations (GCs) and illuminating putative reassortment events. The results showed that RVs with distinct GCs cocirculated during the vast majority of the collection years and that some of these GCs persisted in the community unchanged by reassortment. To investigate the influence of protein coadaptation on GC maintenance, we performed a mutual information-based analysis of the concatenated amino acid sequences and identified an extensive covariance network. Unexpectedly, amino acid covariation was highest between VP4 and VP2, which are structural components of the RV virion that are not thought to directly interact. These results suggest that GCs may be influenced by the selective constraints placed on functionally coadapted, albeit noninteracting, viral proteins. This work raises important questions about mutation-reassortment interplay and its impact on human RV evolution. IMPORTANCE: Rotaviruses are devastating human pathogens that cause severe diarrhea and kill >450,000 children each year. The virus can evolve by accumulating mutations and by acquiring new genes from other strains via a process called reassortment. However, little is known about the relationship between mutation accumulation and gene reassortment for rotaviruses and how it impacts viral evolution. In this study, we analyzed the genome sequences of human strains found in clinical fecal specimens that were collected at a single hospital over an 18-year time span. We found that many rotaviruses did not reassort their genes but instead maintained them as specific sets (i.e., constellations). By analyzing the encoded proteins, we discovered concurrent amino acid changes among them, which suggests that they are functionally coadapted to operate best when kept together. This study increases our understanding of how rotaviruses evolve over time in the human population.

Effectiveness of telephone-based follow-up support delivered in combination with a multi-component smoking cessation intervention in family practice: a cluster-randomized trial.

OBJECTIVE: To determine whether telephone-based smoking cessation follow-up counseling (FC), when delivered as part of a multi-component intervention program is associated with increased rates of follow-up support and smoking abstinence. METHODS: A cluster randomized controlled-trial was conducted within family medicine practices in Ontario, Canada. Consecutive adult patients who smoked were enrolled at two time points, the baseline period (2009) and the post-intervention period (2009-2011). Smoking abstinence was determined by telephone interview 4 months following enrollment. Both groups implemented a multi-component intervention program. Practices randomized to the FC group could also refer patients to a follow-up support program which involved 5 telephone contacts over a 2-month period. RESULTS: Eight practices, 130 providers, and 928 eligible patients participated in the study. No statistically significant difference in 7-day point-prevalence abstinence was observed between intervention groups. There was a significant increase in referral to follow-up in both intervention groups. Significantly higher rates of smoking abstinence [25.7% vs. 11.3%; adjusted OR 3.1 (95% CI: 1.1, 8.6), p<0.05] were documented among the twenty-nine percent of FC participants who were referred to the follow-up support program compared to the MC group. CONCLUSION: Access to external follow-up support did not increase rates at which follow-up support was delivered.

Transitions in smoking status over time in a population-based panel study of smokers.

INTRODUCTION: Few studies have examined the transitions of smokers in the general population through multiple periods of daily, occasional smoking, or abstinence over time. Transitions from daily to occasional smoking are particularly of interest as these may be steps toward cessation. METHODS: The Ontario Tobacco Survey panel study followed 4,355 baseline smokers, semiannually for up to 3 years. Probabilities of all possible changes in smoking status more than 6 months were estimated using 13,000 repeated measures observations generated from sets of 3 consecutive interviews (n = 9,932 daily smokers, 1,245 occasion smokers, and 1,823 abstinent for at least 30 days, at Time 1). RESULTS: For initial daily smokers, an estimated 83% remained daily smokers more than 2 follow-ups. The majority of those who had been abstinent for 30 days at 1 interview, were also former smokers at the following interview. In contrast, occasional smoking status was unstable and future smoking status was dependent upon smoking history and subjective dependence. Among daily smokers who became occasional smokers 6 months later, an estimated 20% became a former smoker, at the next interview, but 50% returned to daily smoking. Daily, turned occasional smokers who rebounded back to daily smoking were more likely to describe themselves as addicted at Time 1. Continuing occasional smokers were somewhat less likely to intend to quit, or have tried, despite considering themselves less addicted. CONCLUSIONS: Reducing to occasional smoking can be a stepping stone toward cessation but entails a greater risk of return to daily smoking, compared with complete abstinence.

Perceived risk and quitting behaviors: results from the ITC 4-country survey.

OBJECTIVE: To rigorously test the relation between perceived risk (i.e., belief about the likelihood of harm) and quitting smoking. METHODS: Data from a longitudinal study with a nonrestrictive sample of smokers (N = 4307) from the United States, Canada, the United Kingdom, and Australia were examined to predict quitting behaviors at 8-12 months. RESULTS: Perceived risk predicted plans to quit, quit attempts, and, to some extent, sustained quitting. The relation was stronger for relatively simple (e.g., plans to quit) than for complex behaviors (e.g., sustained quitting). CONCLUSION: Perceived risk plays a significant role in predicting quitting smoking, more so for relatively simple behaviors.

Planned quit attempts among Ontario smokers: impact on abstinence.

AIMS: To examine the use and role of planned quit attempts by smokers and their impact on abstinence. DESIGN: Retrospective, using longitudinal data from the Ontario Tobacco Survey. SETTING: Ontario, Canada. PARTICIPANTS: A total of 551 adult smokers who reported having made a quit attempt during 2007-08. MEASUREMENTS: Reported planning of the most recent quit attempt (i.e. unplanned or planned some time in advance), engaging in preparatory behaviours believed to be related to planning (i.e. use of quit aids such as pharmacotherapy, formal support or health professionals) and abstinence at 1 week and 1 month following the attempt. FINDINGS: Of the smokers, 73.6% planned their quit attempt in advance. Reported planning was more likely among those who thought they were very addicted, compared with those who were less addicted [odds ratio (OR)=2.22, 95% confidence interval (CI): 1.15-4.28]. Smokers who planned a quit attempt were much more likely to use a quit aid (OR=3.50, 95% CI: 1.80-6.79), particularly pharmacotherapy (OR=6.13, 95% CI: 3.05-12.34). The odds of abstaining for 1 week were lower among those who planned (OR=0.45, 95% CI: 0.22-0.89), independent of perceived addiction. No significant difference was observed for abstinence lasting 1 month. Other factors associated with abstinence were smoking fewer cigarettes per day and having personal support. CONCLUSIONS: Although most quit attempts were planned and planners had higher odds of using quit aids, planning did not increase the likelihood of success.

Are occasional smokers a heterogeneous group? An exploratory study.

BACKGROUND: Occasional smokers represent an important segment of all smokers and have been described to be a heterogeneous group in terms of past experience and likelihood of maintaining nondaily smoking behavior. METHODS: In the prospective Ontario Tobacco Survey, 408 occasional smokers were followed for a year. Characteristics of subgroups of occasional smokers, as suggested by previous literature, were studied for personal and smoking behavior group differences. Agglomerative hierarchical clustering was also used to empirically identify subgroups of occasional smokers using average linkage. Smoking status at 1-year follow-up was examined overall and by the identified subgroups to determine if any were useful predictors of persistent status as nondaily smoking and likelihood of smoking cessation. RESULTS: Significant differences were seen among the subgroups of occasional smokers suggested in previous studies including the number of quit attempts, setting a firm quit date, and whether or not participants cared others knew they smoked in descriptive analyses. Exploratory cluster analysis suggested 4 clusters of occasional smokers based on differences in age, perceived addiction, and history of daily smoking. Subgroups based on participants' history of smoking, self-reported addiction level, and empirically identified cluster subgroups resulted in significant differences of smoking status at 1-year follow-up. CONCLUSIONS: This study suggests that occasional smokers may be a heterogeneous group with different subgroups characterized by age, accumulated smoking experience and smoking pattern, as well as factors associated with the likelihood of quitting altogether, over time, and perceived addiction.

Building research capacity for evidence-informed tobacco control in Canada: a case description.

Tobacco use remains the leading cause of death and disability in Canada. Insufficient research capacity can inhibit evidence-informed decision making for tobacco control. This paper outlines a Canadian project to build research capacity, defined as a community's ability to produce research that adequately informs practice, policy, and future research in a timely, practical manner. A key component is that individuals and teams within the community must mutually engage around common, collectively negotiated goals to address specific practices, policies or programs of research. An organizing framework, a set of activities to build strategic recruitment, productivity tools, and procedures for enhancing social capital are described. Actions are intended to facilitate better alignment between research and the priorities of policy developers and service providers, enhance the external validity of the work performed, and reduce the time required to inform policy and practice.

Prevalence and correlates of purchasing contraband cigarettes on First Nations reserves in Ontario, Canada.

AIMS: Non-First Nations people purchasing cigarettes on First Nations reserves do not pay applicable taxes. We estimated prevalence and identified correlates of purchasing contraband cigarettes on reserves; we also quantified the share of contraband purchased on reserves relative to reported total cigarette consumption and the associated financial impact on taxation revenue. DESIGN: Data from the Ontario Tobacco Survey, a regionally stratified representative population telephone survey that over-samples smokers. SETTING: Ontario, Canada. PARTICIPANTS: A total of 1382 adult current smokers. MEASUREMENTS: Reported status of purchasing cigarettes on reserves and the quantity of cigarettes bought on reserves. The prevalence of purchasing cigarettes on reserves was assessed with descriptive statistics. A two-part model was used to analyse correlates of having recently purchased contraband. FINDINGS: A total of 25.8% reported recent purchasing and 11.5% reported usual purchasing. Heavy smoking, having no plans to quit and lower education were correlated with recent purchasing. Heavy smoking and not having plans to quit were also correlated with buying more packs of cigarettes on reserves. Contraband purchases on reserves accounted for 14.0% of the reported total cigarette consumption and resulted in an estimated tax loss of $122.2 million. CONCLUSIONS: There was substantial purchasing of contraband cigarettes on reserves in Ontario, resulting in significant losses in tax revenues. The availability of these cheap cigarettes undermines the effectiveness of tobacco taxation to reduce smoking. Wherever indicated, governments should strengthen their contraband prevention and control measures, as recommended by the Framework Convention on Tobacco Control, to ensure that tobacco taxation achieves its intended health benefits and that tax revenues are protected.

Prevalence of cigarette smoking among young adults in Pakistan.

OBJECTIVE: To obtain information about the prevalence of cigarette smoking among a selected sample of university students in Karachi and build our understanding of the determinants of smoking with respect to family smoking, smoking in the home, smoke-free public places, and quit smoking cessation programmes. METHODS: Data were collected as a part of a pilot project initiated by Jinnah University Karachi. Participants were 629 university students (432 males and 197 females) aged 18-25 years from ten universities in Karachi. Descriptive statistics and Logistic regression analyses were used to determine the results and conclusions. RESULTS: Thirty-nine per cent of students had smoked a whole cigarette in their life time, whereas 25% had smoked 100 or more cigarettes in their lifetime. Overall, 23% of students (31% male and 6% female) were classified as a current smoker and their mean age and standard deviation of smoking initiation was 17 +/- 2.7 years (17 +/- 2.6) for males and 16 +/- 2.9 females. Sixty-three percent of smokers reported that public places should be smoke-free. Logistic regression analyses adjusted by age and gender suggested that parental and sibling influence and number of close friends and individuals who smoke at home were highly predictive of being a smoker. CONCLUSION: Findings from this study suggest that student were generally open to smoking cessation treatment and no-smoking restrictions.

Vigorous motor activity in Caenorhabditis elegans requires efficient clearance of dopamine mediated by synaptic localization of the dopamine transporter DAT-1.

The catecholamine dopamine (DA) functions as a powerful modulatory neurotransmitter in both invertebrates and vertebrates. As in man, DA neurons in the nematode Caenorhabditis elegans express a cocaine-sensitive transporter (DAT-1), presumably to regulate synaptic DA signaling and limit DA spillover to extrasynaptic sites, although evidence supporting this is currently lacking. In this report, we describe and validate a novel and readily quantifiable phenotype, swimming-induced paralysis (SWIP) that emerges in DAT-1-deficient nematodes when animals exert maximal physical activity in water. We verify the dependence of SWIP on DA biosynthesis, vesicular packaging, synaptic release, and on the DA receptor DOP-3. Using DAT-1 specific antibodies and GFP::DAT-1 fusions, we demonstrate a synaptic enrichment of DAT-1 that is achieved independently of synaptic targeting of the vesicular monoamine transporter (VMAT). Importantly, dat-1 deletions and point mutations that disrupt DA uptake in cultured C. elegans neurons and/or impact DAT-1 synaptic localization in vivo generate SWIP. SWIP assays, along with in vivo imaging of wild-type and mutant GFP::DAT-1 fusions identify a distal COOH terminal segment of the transporter as essential for efficient somatic export, synaptic localization and in vivo DA clearance. Our studies provide the first description of behavioral perturbations arising from altered trafficking of DATs in vivo in any organism and support a model whereby endogenous DA actions in C. elegans are tightly regulated by synaptic DAT-1.

Doctors' views of clinical practice guidelines: a qualitative exploration using innovation theory.

RATIONALE, AIMS AND OBJECTIVES: The authors undertook this qualitative study as part of a larger evaluation of the effect of eight clinical practice guidelines issued by an arm's-length government agency in a Canadian province. Using Orlandi and colleagues' version of the Rogers diffusion of innovation model as a framework, the authors mapped doctors' views on implementation of clinical practice guidelines. METHODS: In semi-structured interviews with 45 representative doctors, the authors elicited doctors' framework of meaning for behaviour change in general and for clinical practice guideline uptake in particular. These were then compared with the adapted Orlandi/Rogers diffusion of innovation model to confirm, amend or challenge that model. RESULTS: Doctors identified the following influences on changes to their clinical practice and on clinical practice guideline uptake, within a five-step innovation model: 1 innovation: evidence change is required, perceived need for change; 2 communication: awareness of innovation; 3 adoption: evidence of improved outcomes without increased patient risk, opinion leader support, consistency with current trends; 4 implementation: patient and family acceptability; and 5 maintenance: system support, patient and family support, observed improved patient outcomes without increased risk. CONCLUSIONS: Innovation for doctors is a complex decision process rather than a single decision point. Change occurs in the context of professional networks and patient and family support and demand.

Youth smokers' beliefs about different cessation approaches: are we providing cessation interventions they never intend to use?

INTRODUCTION: Most youth smokers intend to quit, but the majority is neither aware nor interested in most conventional cessation approaches. As such, a critical first step in understanding youth cessation is to better understand the beliefs youth have about different cessation options. METHODS: This cross-sectional study used self-reported data collected from 26,379 grade 9 to 12 students in Ontario, Canada. We examined both the attitudes of youth smokers toward common smoking cessation approaches and factors associated with intentions to join a school-based cessation program. RESULTS: The majority of youth smokers intend to quit smoking but tend to have negative attitudes toward most formal smoking cessation approaches; Nicotine Replacement Therapy (NRT) was an exception. Among occasional smokers, self-identification as a smoker and being physically active were positively associated with intending to join a school-based cessation program. Having tried to quit smoking at least once in the past year more than doubled the likelihood of being interested in a school-based program among both occasional and daily smokers. CONCLUSION: Findings have the potential for informing the development of more effective campaigns for engaging adolescent smokers into smoking cessation treatment. Results also reinforce the need for programmatic innovation within and beyond school settings.

A practical, cost-effective method for recruiting people into healthy eating behavior programs.

INTRODUCTION: The population impact of programs designed to develop healthy eating behaviors is limited by the number of people who use them. Most public health providers and researchers rely on purchased mass media, which can be expensive, on public service announcements, or clinic-based recruitment, which can have limited reach. Few studies offer assistance for selecting high-outreach and low-cost strategies to promote healthy eating programs. The purpose of this study was 1) to determine whether classified newspaper advertising is an effective and efficient method of recruiting participants into a healthy eating program and 2) to determine whether segmenting messages by transtheoretical stage of change would help engage individuals at all levels of motivation to change their eating behavior. METHODS: For 5 days in 1997, three advertisements corresponding to different stages of change were placed in a Canadian newspaper with a daily circulation of 75,000. RESULTS: There were 282 eligible people who responded to newspaper advertisements, and the cost was Can $1.11 (U.S. $0.72) per recruit. This cost compares favorably with the cost efficiency of mass media, direct mail, and other common promotional methods. Message type was correlated with respondent's stage of change, and this correlation suggested that attempts to send different messages to different audience segments were successful. CONCLUSION: Classified advertisements appear to be a highly cost-efficient method for recruiting a diverse range of participants into healthy eating programs and research about healthy eating.

From evidence-based practice making to practice-based evidence making: creating communities of (research) and practice.

Models of research translation frequently emphasize independent roles for research producers and intended users. This article describes a novel approach for enhancing exchange between researchers and practitioners. The framework is based on Wenger's notion of Communities of Practice (CoP) where knowledge is regarded as a social enterprise at the center of member interactions. Research-based practices and policies emerge when research producers and users mutually engage one another about specific health promotion problems through negotiation and by creating and sharing technical standards and other resources. CoPs are more than loose networks or task-oriented teams. They aim to create both social and intellectual capital through mutual negotiation, reciprocity, trust, and cohesion. A Consortium of Quitline Operators across North America and a Canadian project to enhance research capacity for tobacco control research serve as examples of how the model has been successfully operationalized.

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.

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.