6 resultados para biotic and aboitic stress
em Brock University, Canada
Resumo:
The prlmaiy objective of this study was to Identify and describe the physical and psychological stress factors that elementary school teachers experience and how teachers cope with stress. A secondary objective was to offer boards and teachers potential coping strategies counteracting stress and the effects of stress. The sample consisted of 120 elementaiy teachers from southern Ontario. Ten elementaiy schools were randomly chosen. The Teacher Stress Inventory questionnaire (Flmian, 1989) was used. Data were analyzed using a variety of statistics. Test norms and interpretations were performed based on standard results obtained from the author of the questionnaire (Flmian, 1988). Overall, the results indicated that work-related stressors were the main factor for teacher stress. This Included such factors as caseload/class is too big, too much administrative paperwork, and having little time to prepare lessons. Implications for further research and practical suggestions for further reseairch are discussed. Also a variety of recommendations to boards and for individual use are discussed. Some recommendations are having counselling available for teachers, workshops on how to handle stress, and learning how to breathe and using calm visualization.
Resumo:
The allometric scaling relationship observed between metabolic rate (MR) and species body mass can be partially explained by differences in cellular MR (Porter & Brand, 1995). Here, I studied cultured cell lines derived from ten mammalian species to determine whether cells propagated in an identical environment exhibited MR scaling. Oxidative and anaerobic metabolic parameters did not scale significantly with donor body mass in cultured cells, indicating the absence of an intrinsic MR setpoint. The rate of oxygen delivery has been proposed to limit cellular metabolic rates in larger organisms (West et al., 2002). As such cells were cultured under a variety of physiologically relevant oxygen tensions to investigate the effect of oxygen on cellular metabolic rates. Exposure to higher medium oxygen tensions resulted in increased metabolic rates in all cells. Higher MRs have the potential to produce more reactive oxygen species (ROS) which could cause genomic instability and thus reduced lifespan. Longer-lived species are more resistant to oxidative stress (Kapahi et al, 1999), which may be due to greater antioxidant and/or DNA repair capacities. This hypothesis was addressed by culturing primary dermal fibroblasts from eight mammalian species ranging in maximum lifespan from 5 to 120 years. Only the antioxidant manganese superoxide dismutases (MnSOD) positively scaled with species lifespan (p<0.01). Oxidative damage to DNA is primarily repaired by the base excision repair (BER) pathway. BER enzyme activities showed either no correlation or as in the case of polymerase p correlated, negatively with donor species (p<0.01 ). Typically, mammalian cells are cultured in a 20% O2 (atmospheric) environment, which is several-fold higher than cells experience in vivo. Therefore, the secondary aim of this study was to determine the effect of culturing mammalian cells at a more physiological oxygen tension (3%) on BER, and antioxidant, enzyme activities. Consistently, standard culture conditions induce higher antioxidant and DNA ba.se excision repair activities than are present under a more physiological oxygen concentration. Therefore, standard culture conditions are inappropriate for studies of oxidative stress-induced activities and species differences in fibroblast DNA BER repair capacities may represent differences in ability to respond to oxidative stress. An interesting outcome firom this study was that some inherent cellular properties are maintained in culture (i.e. stress responses) while others are not (i.e. MR).
Resumo:
This qualitative research study used grounded theory methodology to explore the settlement experiences and changes in professional identity, self esteem and health status of foreign-trained physicians (FTPs) who resettled in Canada and were not able to practice their profession. Seventeen foreign-trained physicians completed a pre-survey and rated their health status, quality of life, self esteem and stress before and after coming to Canada. They also rated changes in their experiences of violence and trauma, inclusion and belonging, and racism and discrimination. Eight FTPs from the survey sample were interviewed in semi-structured qualitative interviews to explore their experiences with the loss of their professional medical identities and attempts to regain them during resettlement. This study found that without their medical license and identity, this group of FTPs could not fully restore their professional, social, and economic status and this affected their self esteem and health status. The core theme of the loss of professional identity and attempts to regain it while being underemployed were connected with the multifaceted challenges of resettlement which created experiences of lowered selfesteem, and increased stress, anxiety and depression. They identified the re-licensing process (cost, time, energy, few residency positions, and low success rate) as the major barrier to a full and successful settlement and re-establishment of their identities. Grounded research was used to develop General Resettlement Process Model and a Physician Re-licensing Model outlining the tasks and steps for the successfiil general resettlement of all newcomers to Canada with additional process steps to be accomplished by foreign-trained physicians. Maslow's Theory of Needs was expanded to include the re-establishment of professional identity for this group to re-establish levels of safety, security, belonging, self-esteem and self-actualization. Foreign-trained physicians had established prior professional medical identities, self-esteem, recognition, social status, purpose and meaning and bring needed human capital and skills to Canada. However, without identifying and addressing the barriers to their full inclusion in Canadian society, the health of this population may deteriorate and the health system of the host country may miss out on their needed contributions.
Resumo:
Obesity is a condition associated with a wide variety of health problems including hypertension, dyslipidemia, diabetes mellitus, certain forms of cancer, cardiovascular disease, and gallstones (157). TTiere is growing evidence that obesity may also be related to compromised immune function due to altered metabolic, psychological, and physical attributes (93). The aim of this study was to compare: a) immunity-related variables such as frequency of upper respiratory tract infections (URTI) and salivary secretory immunoglobulin A (sIgA) levels between overweight/obese (OB) and normal weight (NW) early-pubertal and late-pubertal girls, and b) stress-related variables such as Cortisol, melatonin, the melatonin/cortisol ratio, testosterone and the testosterone/cortisol ratio. Physical activity levels, stress indicators, and fatigue were used to explain potential differences in the dependent variables. It was hypothesized that the OB females would have lower melatonin (M) and higher Cortisol (C) and testosterone (T) levels compared with NW girls, regardless of maturity status. The altered levels of melatonin, Cortisol, and testosterone, would result in decreased M/C and T/C ratios, despite the increase in testosterone in OB females. It was hypothesized that this altered hormonal status results in a compromised immunity marked by higher frequency of upper respiratory tract infections (URTI) and decreased levels of secretory immunoglobulin A (sIgA). It was also hypothesized that OB girls would participate in less hours of physical activity than their NW counterparts and that this would relate to their stress and immunity levels. Forty (16 early- and 24 late-pubertal) overweight and obese females were compared to fifty-three (27 eariy- and 26 late-pubertal) age-matched normal-weight control subjects. Participants were categorized as early-pubertal (EP) or late-pubertal (LP) using Tanner self-staging of secondary sex characteristics. Subjects were classified into the two adiposity groups according to relative body fat (%BF), where normal weight (NW) subjects had a %BF less than 25%, and overweight and obese (OB) subjects had a %BF greater than 27.5%. Participants completed a number of questionnaires and information was collected on menstrual history, smoking history, alcohol and caffeine consumption, and medical history. Following the determination of maturity status, a complete anthropometric assessment was made including height, body mass, and body composition. All questionnaires and measurements were completed during a one-hour visit between 1 500 and 1900 hours Relative body fat was assessed using bioelectrical impedance analysis. Resting saliva samples were obtained and assayed (ELISA) for testosterone, Cortisol, melatonin and secretory immunoglobulin A. Physical activity was self-reported using the Godin- Shephard Leisure time questionnaire, and quantified using Actigraph GTIM accelerometers, which participants wore for seven consecutive days from the time they woke up in the morning, until the time they went to bed. Late-pubertal girls also completed questionnaires on their perceived stress and fatigue. Finally, all participants also filled out a one-month health log to record frequency of symptoms of upper respiratory tract infections (URTI). Significant age effects were found for testosterone, Cortisol, incidence of sickness, and sIgA when controlling for physical activity, however there were no significant effects of adiposity on any of the variables. There was a trend which neared-significance for an effect of adiposity on sIgA (p=0.01). There were no significant differences between the groups on the total selfreported leisure-time physical activity in METs per week, however EP girls recorded significantly greater levels of moderate, hard, and very hard physical activity from accelerometers. Results of the perceived stress and fatigue questionnaires in late-pubertal girls demonstrated that contrary to what was hypothesized, NW girls reported more stress and more fatigue than OB girls. Results of the present study suggest that excess adiposity in early- and latepubescent girls may not have a negative impact on immunity as hypothesized.
Resumo:
Within the context of international adoption, previous research has focused on parentchild attachment relationships and various aspects of the adoption process. However, less is known about other aspects of parent-child relationships (e.g., cohesion, conflict) within internationally adoptive families. Additionally, there is a need for research that explores both parent and child perceptions of the process of adoption - including pre- and post-adoptive factors - and its connection to the quality of parent-child relationships. This research utilized a qualitatively-oriented methodology to conduct separate, in-depth interviews with 10 adoptive Canadian mothers and their adopted Chinese children (aged 9 to 11 years). Results highlight parent and child reports of mainly strong, positive relationships. Several pre-adoption experiences are examined, including institutionalization, age at the time of adoption, and parental stress/expectations. A key finding concerns the link that adoptive parents perceive between the quality of their child's pre-adoptive care (i.e., mainly early institutionalized care) and the quality of their relationship. Interestingly, this link is perceived in two different ways - either as a challenge for the parent-child relationship or as a means to strengthen it. Post-adoption experiences are also explored, including cultural socialization, creating a transracial family, discussing adoption, parental stress, and sibling involvement. A key finding involves parent and child reports that cultural socialization efforts (i.e., familiarizing children with Chinese culture) are linked to more positive parent-child relationships. The implications of these findings are discussed in relation to theory and practice within the context of international adoption.
Resumo:
The article researches "electric stunning, carbon dioxide stunning, pig behaviour during handling, return to sensibility, facility design, truck loading, density and transport stress".