Matthew Yw Kwan

Cell-Specific Expression of the Parathyroid Hormone (PTH)/PTH-Related Peptide Receptor Gene in Kidney from Kidney-Specific and Ubiquitous Promoters

The kidney is the major site of expression of the PTH/PTH-related peptide receptor (PTHR) gene. Previously we have shown that the PTHR gene is expressed from two promoters in kidney, an upstream kidney-specific promoter (P1) and a downstream promoter (P2) that is active in a wide variety of tissues. Here, we have used immunohistochemical and transcript-specific in situ hybridization techniques to map the expression of the PTHR gene and protein and to determine the distribution of P1- and P2-driven messenger RNAs in renal tissue. Immunohistochemical and immunoelectron microscopic analysis showed that PTHR protein is expressed on both basolateral and luminal membranes of proximal tubular epithelial cells, strongly suggesting a bipolar mode of action of PTH. Receptor protein also was detected on the surface of glomerular podocytes. Strikingly, immunoelectron microscopic analysis showed that endothelial cells of the peritubular vasculature, but not the glomerular vasculature, contain high levels of PTHR protein. We found that both P1 and P2 are expressed at moderate levels in both cortical and medullary epithelial cells of nephrons, correlating well with the immunohistochemical localization of PTHR protein. However, although abundant transcripts were detected in peritubular endothelial cells with P1-specific and coding sequence probes, P2-specific expression was not observed in these cells. These results provide evidence that the physiological effects of PTH- and/or PTH-related peptide on renal tubular function may be mediated not only through direct effects on epithelial cells but also indirectly through endothelial cell-based signaling. In addition to expression in vascular endothelial cells, high levels of P1-specific, but not P2-specific, PTHR messenger RNA were detected in vascular smooth muscle. Taken together, these experiments provide evidence for strong PTHR gene expression in renal vascular tissues. Moreover, given that previous studies have shown that P2, but not P1, is active in other tissues with an abundant vasculature, our results suggest that regulation of PTHR gene expression in renal vascular tissue is distinct from that of other organs.

Sport participation and alcohol and illicit drug use in adolescents and young adults: A systematic review of longitudinal studies

Sport participation can play an important and positive role in the health and development of children and youth. One area that has recently been receiving greater attention is the role that sport participation might play in preventing drug and alcohol use among youth. The current study is a systematic review of 17 longitudinal studies examining the relationship between sport participation and alcohol and drug use among adolescents. Results indicated that sport participation is associated with alcohol use, with 82% of the included studies (14/17) showing a significant positive relationship. Sport participation, however, appears to be related to reduced illicit drug use, especially use of non-cannabis related drugs. Eighty percent of the studies found sport participation associated with decreased illicit drug use, while 50% of the studies found negative association between sport participation and marijuana use. Further investigation revealed that participation in sports reduced the risk of overall illicit drug use, but particularly during high school; suggesting that this may be a critical period to reduce or prevent the use of drugs through sport. Future research must better understand what conditions are necessary for sport participation to have beneficial outcomes in terms of preventing alcohol and/or illicit drug use. This has been absent in the extent literature and will be central to intervention efforts in this area.

Gender, perceived competence and the enjoyment of physical education in children: a longitudinal examination

BackgroundThe current study examined associations between gender, perceived athletic competence, and enjoyment of physical education (PE) class over time in a cohort of children enrolled in grade four (ages 9 or 10) at baseline (n = 2262).MethodsWe assessed each student 5 times over a period of 2 years. We used mixed effects modeling to examine change over time in enjoyment of PE.ResultsEnjoyment of PE declined among girls but remained constant among boys. Higher levels of perceived competence were associated with higher PE enjoyment. A 3-way interaction between gender, competence, and time revealed that PE enjoyment was lowest and declined most markedly among girls with low perceived athletic competence. Among boys with low competence, enjoyment remained at a consistently low level.ConclusionsOur results indicate that lower perceived athletic competence is associated with low enjoyment of PE, and, among girls, with declining enjoyment. Findings suggest that interventions in a PE context that target perceived competence should be considered in future work.

Social norms of alcohol, smoking, and marijuana use within a Canadian university setting.

Abstract Objective: To study actual and perceived substance use in Canadian university students and to compare these rates with US peers. Participants: Students (N = 1,203) from a large Canadian university. Methods: Participants were surveyed using items from the National College Health (NCHA) Assessment of the American College Health Association questionnaire. Results: Alcohol was the most common substance used (65.8%), followed by marijuana (13.5%) and cigarettes (13.5%). Substance use and norms were significantly less than the NCHA US data. Overall, respondents generally perceived the typical Canadian student to have used all 3 substances. Perceived norms significantly predicted use, with students more likely to use alcohol, cigarettes, or marijuana if they perceived the typical student to use these substances. Conclusions: Similar to their US peers, Canadian university students have inaccurate perceptions of peer substance use. These misperceptions may have potentially negative influences on actual substance use and could be a target for intervention. Further research examining the cross-cultural differences for substance abuse is warranted.

Physical Activity Is Associated With Better Health and Psychological Well-Being During Transition to University Life

Abstract. The authors investigated vigorous physical activity, psychological well-being, and self-reported illness during transition to first-year university life in a sample of 175 Canadian under-graduates. At the completion of their first year of university study, participants completed retrospective measures assessing vigorous physical activity, upper respiratory infectious illness (URI), doctor visits, as well as measures of psychological well-being. Based on nationally recommended (US Department of Health and Human Services) standards, 61% of students reported engaging in adequate levels of vigorous activity during their first year at university. The authors found no differences in URIs between sufficiently and insufficiently active students. However, insufficiently active students scored lower on psychological well-being and were twice as likely to have consulted a physician regarding an illness compared with sufficiently active students.

Developmental Coordination Disorder, gender, and body weight: Examining the impact of participation in active play

BACKGROUND To examine whether differences in participation in active play (PAP) can account for gender differences in the relationship between Developmental Coordination Disorder (DCD) and body weight/fat (BMI and percentage fat) in youth. METHODS A cross-sectional investigation of students in grades four through eight (n = 590). Height, weight (BMI), and percentage body fat using bioelectrical impedance analysis (BIA; RJL Systems, MI) were collected. Motor proficiency and physical activity levels were also evaluated. RESULTS We found gender specific patterns in the relationship between PAP, DCD, and BMI and body fat. Among boys with DCD, greater participation in active play is associated with higher BMI and percentage body fat. For girls with the disorder, the opposite relationship is observed. CONCLUSIONS Participation in active play moderates the association between DCD, gender and body weight. Three possible explanations for why PAP is associated with higher BMI and percentage body fat in boys with DCD are provided.

Understanding physical activity and motivations for children with developmental coordination disorder: an investigation using the theory of planned behavior.

Developmental coordination disorder (DCD) is a neurodevelopmental condition, affecting approximately 5-6% of children. Previous research has consistently found children with DCD being less physically active compared to typically-developing (TD) children; however, the psychosocial factors associated with physical activity for children with DCD are poorly understood. The purpose of this study was to examine how theory-based physical activity cognitions impacts physical activity behaviors for children with and without DCD. Participants included a sample of boys (N=61, Mage=13.25 ±.46) with DCD (n=19) and without DCD (n=42), drawn from a larger prospective cohort study. A questionnaire with psychosocial measures was first administered, and accelerometers were used to assess their physical activity behavior over the subsequent week. Findings indicate that DCD was significantly associated with lower physical activity (F(1,58)=6.51, p<.05), and poorer physical activity cognitions (F(4,56) Wilks Lambda=2.78, p<.05). Meditational analyses found attitudes (B=.23, p<.05) and subjective norms (B=.31, p<.05) partially mediating the relationship between DCD and physical activity. Overall, this study further confirms that the activity deficit that exists among boys with DCD, and that the relationship is partially mediated through some physical activity cognitions. Interventions should target the perceived approval of influential people, and the personal evaluations of physical activity for boys with motoric difficulties. These findings further emphasizes the discrepancy in physical activity that exist between boys with DCD and TD boys, and highlight the need to better understand the psychological factors related to physical activity for children with DCD.

Batting last as a home advantage factor in men's NCAA tournament baseball

In baseball and softball, there is a rule that allows the home team to have the last at-bat and thus the final opportunity to win the game. However, in tournament play, this rule is often set aside and, instead, batting order is decided by other means (e.g. tournament rules, the flip of a coin). The purpose of this study was to examine the impact of the batting last rule on game outcome in NCAA mens regional tournament baseball. It was hypothesized that host (i.e. home) teams would win a greater percentage of the games in which they batted last compared with when they batted first. This hypothesis was not supported. Closer examination of the last inning of play showed home teams were no more likely to have won the game during their last bat than visitors playing other visitors. The results suggest that the batting last rule contributes minimally, if at all, to home advantage in NCAA tournament baseball.

The Long Live Kids campaign: awareness of campaign messages.

Media interventions are one strategy used to promote physical activity, but little is known about their effectiveness with children. As part of a larger evaluation, the purpose of this study was to assess the short-term effect of a private industry sponsored media literacy campaign, Long Live Kids, aimed at children in Canada. Specifically, we investigated childrens awareness of the campaign and its correlates. Using a cohort design, a national sample (N = 331, male = 171; mean age = 10.81, SD = 0.99) completed a telephone survey two weeks prior to the campaign release, and again 1 year later. Only 3% of the children were able to recall the Long Live Kids campaign unprompted and 57% had prompted recall. Logistic regression found family income (Wald χ2 = 11.06, p < .05), and free-time physical activity (Wald χ2 = 5.67, p < .01) significantly predicted campaign awareness. Active children (≥3 days/week) were twice as likely to have recalled the campaign compared with inactive children (<3 days/week), whereas children living in high-income households (>

Biological age and sex-related declines in physical activity during adolescence.

60,000/yr) were between 3.5 to 5 times more likely to have campaign recall compared with children living in a low-income households (<