Different cell death types determination in juvenile mice ovarian follicles.

Follicular atresia is a phenomenon that leads to evacuation of the ovary from the oocytes and the occurrence of menopause. The contribution of various types of cell death in atresia at different follicular developmental stages requires extensive investigation. In this study, we evaluated 3 types of programmed cell death (PCD), apoptosis, autophagy, and necrosis, in juvenile mouse ovary when we can observe all follicular stages as well as atresia. Ovaries from juvenile mice on the 21st post-natal (PN) day were prepared histologically for terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) to evaluate apoptosis and immunohistochemistry for beclin-1 to evaluate the autophagy marker. Necrotic cell death was also assessed by penetration of propidium iodide (PI). The count and percentage of the labeled follicles at different stages in the ovaries were evaluated and compared using the Kruskal-Wallis and Mann-Whitney tests. We detected TUNEL-positive granulosa cells in pre-antral and antral follicles but not in the primordial and primary follicles. Somatic cells and oocytes of primordial, primary, pre-antral and antral follicles reacted to beclin-1. The percentage of the PI-labeled primordial and primary follicles were significantly higher than the beclin-1 positive (P=0.01 and P=0.01). In conclusion, we showed that apoptosis, autophagy, and necrosis play a role in follicular atresia and the contributions of each one depends on the follicular stages. It was also demonstrated that necrosis happens particularly in the small follicles while in the large one, all three cell death types occurred with an equal ratio.

Cumulus cell expansion and first polar body extrusion during in vitro oocyte maturation in relation to morphological and morphometric characteristics of the dromedary camel ovary.

The morphological and morphometric characteristics of the ovary are fundamental properties for in vitro oocyte maturation. Nuclear maturation, including first polar body (1PB) extrusion, cytoplasmic maturation and cumulus cell (CC) expansion are the criteria for in vitro maturation (IVM) of oocyte. This study was designed to determine the effect of morphological and morphometric features of the ovary on CC expansion and 1PB extrusion during IVM of oocyte in the adult female dromedary camel. The weight, volume and three dimensions of ovaries from slaughtered dromedary camels and oocytes inside zona diameter and zona pellucida thickness were measured. The follicles were classified in regard to the size and oocytes according to their ooplasm appearance and CC compactness. Aspirated cumulus oocyte complexes (COCs) were incubated for 48 hr (with a 6-hr interval) in Hams-F10, and CC expansion and 1PB extrusion were assessed. Significant differences were seen in the shape, weight, volume and three dimensions of the ovaries between ≤4-year-old and >4-year-old dromedary camel (p < .5). Approximately, 95.82% of follicles were 2-4 mm in diameter. The mean (±SD) of inside zona diameter of the oocyte and zona pellucida thickness was 132.22 ± 13.8 and 14.64 ± 2.24 µm, respectively, in >4-year-old dromedary camel. The CC expansion and 1PB extrusion were seen in 86% and 21.88% of COCs, respectively. Age and sexual conditions of dromedary camel influence the morphological and morphometric characteristics of the ovary. Most COCs retrieved from 2-6 mm follicles are cultivable. The most slaughterhouse-derived COCs retrieved from 2-6 mm follicles of non-pregnant dromedary camels are excellent and good and yielding a most favourable diameter to achieve the developmental competence for IVM in an optimal time of 24-30 hr; the optimal time for CC expansion is 24-30 hr in this species. However, the CC expansion is a prerequisite process, but not sufficient for IVM.

Association between contraband tobacco and illicit drug use among high school students in Canada.

A particularly challenging issue to tobacco cessation efforts is the availability of contraband cigarettes. While studies have linked contraband tobacco to smoking initiation and poor cessation outcomes, little is known about its association with illicit drug use among adolescents. We examine the association between contraband tobacco and illicit drug use among adolescent students using a national representative sample of 2,136 current smoker students in grades 9-12 from the 2010-2011 Youth Smoking Survey. About 31 % of adolescent current smokers in grades 9-12 use contraband cigarettes. Prevalence in the use of illicit drugs ranged from 9 to 37 %, with MDMA being the most commonly used drug. Adjusted logistic regression revealed that smokers of contraband cigarettes, when compared with non-contraband cigarette smokers, were more likely to use cocaine (OR 2.14; CI 1.29-3.56), heroin (OR 7.92; CI 3.00-20.91), amphetamines (OR 4.25; CI 2.07-8.74), MDMA (OR 2.00; CI 1.25-3.19), hallucinogens (OR 2.18; CI 1.34-3.55), and ketamine (OR 3.48; CI 1.61-7.54). This paper adds to the existing evidence of the negative effects of contraband tobacco by showing that adolescent contraband smokers are more likely to use illicit drugs. Given the addictive nature of these drugs and the potential for such behavior to spill over into adulthood, more efforts should be invested in addressing this problem.

Smoking intensity and intent to continue smoking among menthol and non-menthol adolescent smokers in Canada.

PURPOSE: Research suggests that menthol cigarette use is associated with nicotine dependence. However, findings on the relationship between menthol smoking status and quantity of cigarettes smoked are less clear. The objective of this paper was to examine whether menthol cigarette smoking is associated with higher smoking intensity and intention to continue smoking among adolescents. METHODS: A nationally representative sample of 4,736 Canadian students in grades 9-12 was drawn from the 2010-2011 Canadian Youth Smoking Survey. Associations between smoking intensity and menthol smoking were examined using linear regression. A logistic regression was used to examine whether menthol smoking increased the odds that a student reported intention to continue smoking. RESULTS: Thirty-two percentage of smokers in grades 9-12 smoked menthol cigarettes in the last 30 days. Unadjusted average number of cigarettes reported by menthol smokers was 6.86 compared with 4.59 among non-menthol smokers (p < 0.001). Multivariable results showed that the average number of cigarettes smoked by menthol smokers was greater than non-menthol smokers (ß = 1.92; 95 % CI = 1.16-2.68). Similar results were found using the total number of cigarettes smoked in the past week. Additionally, menthol smokers had greater odds of reporting intent to continue smoking compared with non-menthol smokers (OR = 2.95; 95 % CI = 2.24-3.90). These results were similar when separate analyses were conducted for established smokers and experimental smokers. CONCLUSIONS: The findings of this study along with existing evidence suggest the need for banning mentholated tobacco products in Canada, in part because of its significant effect on adolescent smoking.

Is alcohol mixed with energy drinks consumption associated with susceptibility to smoking?

OBJECTIVE: This paper examines whether adolescent students in Canada who have never smoked but who drink alcohol mixed with energy drinks (AmED) are more susceptible to smoking than those who do not consume AmED. METHODS: A nationally representative sample of 15,875 never-smoking students in grades 9 to 12 from the 2010-2011 Canadian Youth Smoking Survey is used. The association between AmED and susceptibility to smoking is examined using a logistic regression. RESULTS: About 28% of the never-smoking adolescents in grades 9 to 12 are susceptible to smoking, and 13% report using AmED. Results of the adjusted logistic regression analysis show a statistically significant positive association between consuming AmED and susceptibility to smoking. Never-smoking students who reported using AmED are more susceptible to smoking when compared with those who have not consumed AmED (OR=1.89; 95% CI=1.71-2.10). Similar results are obtained when the analysis is stratified by gender. CONCLUSIONS: The consumption of AmED is associated with higher odds of smoking susceptibility among Canadian adolescents. AmED use could be a potential marker for smoking susceptibility among never-smoking adolescents.

Binge drinking and marijuana use among menthol and non-menthol adolescent smokers: findings from the youth smoking survey.

INTRODUCTION: Research has shown that smoking menthol cigarettes induces smoking initiation and hinders cessation efforts especially among youth. The objective of this paper is to examine the association between menthol cigarette smoking and substance use among adolescent students in Canada. METHODS: A nationally representative cross-sectional sample of 4466 Canadian students in grades 7 to 12 from the 2010-2011 Youth Smoking Survey is analyzed. A bivariate probit model is used jointly to examine the association of menthol smoking status with binge drinking and marijuana use. RESULTS: 32% of the current smokers in grades 7 to 12 smoke mentholated cigarettes, 73% are binge drinkers and 79% use marijuana. Results of the bivariate probit regression analysis, controlling for other covariates, show statistically significant differences in the likelihood of binge drinking and marijuana use between menthol and non-menthol smokers. Menthol cigarette smokers are 6% (ME=0.06, 95% CI=0.03-0.09) more likely to binge drink and 7% (ME=0.07, 95% CI=0.05-0.10) more likely to use marijuana. CONCLUSION: Smoking menthol cigarettes is associated with a higher likelihood of binge drinking and marijuana use among Canadian adolescents. Banning menthol in cigarettes may be beneficial to public health.

The effect of graphic cigarette warning labels on smoking behavior: evidence from the Canadian experience.

INTRODUCTION: There is a substantial literature that graphic tobacco warnings are effective; however, there is limited evidence based on actual smoking behavior. The objective of this paper is to assess the effect of graphic cigarette warning labels on smoking prevalence and quit attempts. METHODS: A nationally representative sample of individuals aged 15 years and older from the Canadian National Population Health Survey 1998-2008 is used. The sample consists of 4,853 individuals for the smoking prevalence regression and 1,549 smokers for quit attempts. The generalized estimating equation (GEE) model was used to examine the population-averaged (marginal) effects of tobacco graphic warnings on smoking prevalence and quit attempts. To assess the effect of graphic tobacco health warnings on smoking behavior, we used a scaled variable that takes the value of 0 for the first 6 months in 2001, then increases gradually to 1 from December 2001. RESULTS: We found that graphic warnings had a statistically significant effect on smoking prevalence and quit attempts. In particular, the warnings decreased the odds of being a smoker (odds ratio [OR] = 0.875; 95% CI = 0.821-0.932) and increased the odds of making a quit attempt (OR = 1.330, CI = 1.187-1.490). Similar results were obtained when we allowed for more time for the warnings to appear in retail outlets. CONCLUSION: This study adds to the growing body of evidence on the effectiveness of graphic warnings. Our findings suggest that warnings had a significant effect on smoking prevalence and quit attempts in Canada.

The relationship between job stress and body mass index using longitudinal data from Canada.

OBJECTIVE: This paper examines the effect of job stress, as measured by the job strain model (high job demands and low job control) on an individual's body mass index (BMI) using data from the Canadian National Population Health Survey. METHODS: We use panel data estimation methods to account for unobserved individual-level heterogeneity to better examine the relationship between job-related stress and BMI. RESULTS: Results from the fixed effects and random effects models show no statistically significant difference in BMI levels between individuals in jobs with high/medium strain compared to jobs with low strain. However, in the cross-sectional OLS model, job stress has a positive and significant effect on BMI. These analyses control for socio-demographic factors, lifestyle behavior, workplace social support, occupational and provincial fixed effects. The results suggest that the mixed findings in the previous studies may in part be due to unobserved characteristics that cannot be controlled for using standard cross-sectional analysis. CONCLUSION: This study results suggest the need for further longitudinal evidence in order to have a better understanding of the relationship between job stress and body weight.

The association between workplace smoking bans and self-perceived, work-related stress among smoking workers.

BACKGROUND: There is substantial empirical evidence on the benefits of smoking bans; however, the unintended consequences of this anti-smoking measure have received little attention. This paper examines whether workplace smoking bans (WSB's) are associated with higher self-perceived, work-related stress among smoking workers. METHODS: A longitudinal representative sample of 3,237 individuals from the Canadian National Population Health Survey from 2000 to 2008 is used. Work-related stress is derived from a 12-item job questionnaire. Two categories of WSB's, full and partial, are included in the analysis, with no ban being the reference category. Analysis also controls for individual socio-demographic characteristics, health status, provincial and occupational fixed-effects. We use fixed-effects linear regression to control for individual time-invariant confounders, both measured and unmeasured, which can affect the relationship between WSB's and work-related stress. To examine the heterogeneous effects of WSB's, the analysis is stratified by gender and age. We check the robustness of our results by re-estimating the baseline specification with the addition of different control variables and a separate analysis for non-smokers. RESULTS: Multivariate analysis reveals a positive and statistically significant association between full (ß = 0.75, CI = 0.19-1.32) or partial (ß = 0.69, CI = 0.12-1.26) WSB's, and the level of self-perceived, work-related stress among smoking workers compared to those with no WSB. We also find that this association varies by gender and age. In particular, WSB's are significantly associated with higher work stress only for males and young adults (aged 18-40). No statistically significant association is found between WSB's and the level of self-perceived work-related stress among non-smoking workers. CONCLUSION: The results of this study do not imply that WSB's are the main determinant of self-perceived, work-related stress among smokers but provides suggestive evidence that these may be positively related.

Eating behavior and obesity in Canada: evidence from panel data.

BACKGROUND: Although a growing body of research has examined the association between food prices and the availability of fast food restaurants on weight outcomes, there is limited empirical evidence on the direct effect of eating behavior on body weight. OBJECTIVE: The effect of eating behavior on obesity prevalence among Canadians is examined. METHODS: A nationally representative sample from the Canadian National Population Health Survey (2000-2008) with 29 722 observations is used. Obesity prevalence is estimated by a linear probability model using cross-sectional and panel estimation methods. Separate regressions are estimated for males and females. RESULTS: Multivariate analyses suggest that eating behavior has a statistically significant effect on obesity prevalence. In particular, individuals who reported excellent, very good, and good eating behavior have a lower risk of obesity compared with those with fair or poor eating behavior. Although cross-sectional and panel data methods produce consistent results, the cross-sectional model overestimates the effect of eating behavior on the risk of obesity. This highlights the importance of controlling for unobserved individual factors that may affect how eating behavior is related to body weight. CONCLUSION: Evidence is found showing that eating behavior is an important determinant of obesity prevalence. The findings suggest that improving the eating behavior of individuals would help reduce excessive body weight and its induced health risks.

Disparities in the frequency of fruit and vegetable consumption by socio-demographic and lifestyle characteristics in Canada.

BACKGROUND: The health benefits of adequate fruit and vegetable (F&V) consumption are significant and widely documented. However, many individuals self-report low F&V consumption frequency per day. This paper examines the disparities in the frequency of F&V consumption by socio-demographic and lifestyle characteristics. METHOD: This study uses a representative sample of 93,719 individuals from the Canadian Community Health Survey (2007). A quantile regression model is estimated in order to capture the differential effects of F&V determinants across the conditional distribution of F&V consumption. RESULTS: The conditional and unconditional analyses reveal the existence of a socioeconomic gradient in F&V consumption frequency, in which the low income-education groups consume F&V less frequently than the high income-education groups. We also find significant disparities in F&V consumption frequency by demographic and lifestyle characteristics. The frequency of F&V consumption is relatively lower among: males, those in middle age, singles, smokers, individuals with weak social interaction and households with no children. The quantile regression results show that the association between F&V consumption frequency, and socio-demographic and lifestyle factors varies significantly along the conditional F&V consumption distribution. In particular, individual educational attainment is positively and significantly associated with F&V consumption frequency across different parts of the F&V distribution, while the income level matters only over the lower half of the distribution. F&V consumption follows a U-shaped pattern across the age categories. Those aged 30-39, 40-49 and 50-59 years consume F&V less frequently than those aged 18-29 years. The smallest F&V consumption is among the middle aged adults (40-49). CONCLUSIONS: Understanding the socio-demographic and lifestyle characteristics of individuals with low F&V consumption frequency could increase the effectiveness of policies aimed at promoting F&V consumption. The differential effects of individual characteristics along the F&V consumption distribution suggest the need for a multifaceted approach to address the variation in F&V consumption frequency.

Psychosocial working conditions and the utilization of health care services.

BACKGROUND: While there is considerable theoretical and empirical evidence on how job stress affects physical and mental health, few studies have examined the association between job related stress and health care utilization. Using data from the Canadian National Population Health Survey from 2000 to 2008, this paper examines the association between stressful working conditions, as measured by the job strain model, and the utilization of health care services. METHODS: A zero inflated negative binomial regression is used to examine the excess health care utilization due to job strain. Separate regressions are estimated for both males and females since studies have shown gender differences in health care utilization. RESULTS: Estimates for the whole population show that high or medium job strain has a positive and statistically significant association with the number of visits to both a general practitioner (GP) and a specialist (SP). On average, the number of GP visits is up to 26% more (IRR = 1.26, 95% CI = 1.19-1.31) for individuals with high strain jobs compared to those in the low job strain category. Similarly, SP visits are up to 27% more (IRR = 1.27, 95% CI = 1.14-142) for the high strain category. Results are quantitatively similar for males and females, save for medium strain. In general, findings are robust to the inclusion of workplace social support, health status, provincial and occupational-fixed effects. CONCLUSION: Job strain may be positively associated with the utilization of health care services. This suggests that improving psychosocial working conditions and educating workers on stress-coping mechanisms could be beneficial for the physical and mental health of workers.

The effect of job stress on smoking and alcohol consumption.

This paper examines the effect of job stress on two key health risk-behaviors: smoking and alcohol consumption, using data from the Canadian National Population Health Survey. Findings in the extant literature are inconclusive and are mainly based on standard models which can model differential responses to job stress only by observed characteristics. However, the effect of job stress on smoking and drinking may largely depend on unobserved characteristics such as: self control, stress-coping ability, personality traits and health preferences. Accordingly, we use a latent class model to capture heterogeneous responses to job stress. Our results suggest that the effects of job stress on smoking and alcohol consumption differ substantially for at least two "types" of individuals, light and heavy users. In particular, we find that job stress has a positive and statistically significant impact on smoking intensity, but only for light smokers, while it has a positive and significant impact on alcohol consumption mainly for heavy drinkers. These results provide suggestive evidence that the mixed findings in previous studies may partly be due to unobserved individual heterogeneity which is not captured by standard models.

Oocyte ultrastructural characteristics in camel (Camelus dromedarius) primordial to large antral follicles.

This study was conducted to describe in detail the ultrastructural features and morphological characteristics of camel oocytes from preantral follicles in relation to the sequential stages of follicular development and also for oocytes from antral follicles in relation to their diameter. Camel oocytes from primordial, primary, secondary and also early to late antral follicles were processed and examined by light and transmission electron microscopy. Primordial follicular oocytes were characterized by a layer of flattened granulosa cells around and also eccentric nucleus and few cytoplasmic organelles in the peripheral region. Up to the secondary follicle stage, flat cells were replaced by cuboidal granulosa cells and their number increased and also an increase in the number of organelles such as vesicles, mitochondria and endoplasmic reticulum was observed. In the early antral stage, the formation of zona pellucida, appearance of microvilli and pleomorphic mitochondria was seen and the nucleus was dislocated to the peripheral region. During final growth phase, the extent of endoplasmic reticulum, vesicles and mitochondria increased, the number of lipid droplets decreased and cumulus cell process endings (CCPE) were observed. In conclusion, the growth of camel oocyte is associated with progressive increase in the number of mitochondria, endoplasmic reticulum, Golgi complexes and cytoplasmic vesicles as well as decrease in the number of lipid droplets and the nucleus migration from an eccentric in preantral to a peripheral location in antral follicles.

Chronological and ultrastructural changes in camel (Camelus dromedarius) oocytes during in vitro maturation.

Cumulus-oocyte complexes (COCs) were collected from non-pregnant camels at a local slaughterhouse by aspiration from antral follicles (2-6 mm). In Experiment I, camel COCs (n=304) were matured in vitro in Hams-F10, fixed at different time intervals (6, 12, 18, 24, 30, 36, 42, or 48 h) and stained with 1% aceto-orcein to assess nuclear changes in culture. A majority of the oocytes (81.5%) underwent germinal vesicle break down (GVBD) between 6 and 12h. Forty-eight percent of the oocytes were observed at the metaphase I (M I) stage by 18 h culture. The percentage of matured oocytes (M II stage) at 30 and 42 h were 66.5 and 71% respectively, which were significantly (p<0.05) different to that observed at 24 h (42.5%). In Experiment II, after different periods of culture (12, 24, 36, or 48 h), the COCs (n=26) were processed for transmission electron microscopy. Expansion of both the cumulus and corona radiate cells occurred between 12 and 24 h in the majority of oocytes concomitant with enlargement of the cumulus cell process endings (CCPEs) in the developed perivitelline space. After 12 h of culture disruption of the junctions between CCPEs and the oolemma was observed together with and breakdown of the GV. For 24-36 h of culture cortical granules had spread and aligned along the oolemma. Signs of degeneration in the cytoplasmic organelles of the oocytes were also observed from less than 36 h. After 48 h of culture, larger vesicles and lipid droplets had appeared in the central part of the oocytes and showed uneven distribution throughout the ooplasm. Predominantly non-penetrating CCPEs were also observed in four oocytes by 48 h. In conclusion, based on both light and electron microscopic evaluations, the optimal culture time for the development of competent Camelus dromedarius oocytes in vitro appears to be 30 h using Hams-F10 medium.

Light and transmission electron microscopy of immature camelus dromedarius oocyte.

In order to provide a consistent system for laboratory production of embryos, the characteristics of immature camel oocyte must first be described. The objective of this study was to define ultrastructural features of immature camel oocyte. Ovaries were obtained from camels at a local abattoir, and then transported to the laboratory within 2 h. Camelus cumulus oocyte complexes (COCs) were aspirated from 2-6 mm follicles using a 22-gauge needle. Excellent and good quality COCs were selected and prepared for transmission electron microscopy study using a cavity slide. The fine structure of camel oocyte is morphologically similar to that of other mammalian oocytes. However, some minor differences exist between COC of camel and other mammalian species. Different size and shape of membrane-bound vesicles, lipid droplet, mitochondria and cortical granules were distributed throughout the ooplasm. Discrete or in association with endoplasmic reticulum, Golgi complexes were observed in the periphery of the oocytes. The majority of the oocytes were in the germinal vesicle stage.

Engineering analysis of shoulder dystocia in the human birth process by the finite element method.

This paper presents an engineering analysis of shoulder dystocia (SD) in the human birth process which usually results in damaging the brachial plexus nerves and the humerus and/or clavicle bones of the baby. The goal is to study these injuries from the mechanical engineering point of view. Two separate finite element models of the neonatal neck and the clavicle bone have been simulated using eight-node three-dimensional elements and beam elements respectively. Simulated models have been analysed under suitable boundary conditions using the 'SAP80' finite element package. Finally, results obtained have been verified by comparing them with published clinical and experimental observations.