Abscisic acid regulation of plant defence responses during pathogen attack

The plant hormone, abscisic acid (ABA), has previously been shown to have an impact on the resistance or susceptibility of plants to pathogens. In this thesis, it was shown that ABA had a regulatory effect on an extensive array of plant defence responses in three different plant and pathogen interaction combinations as well as following the application of an abiotic elicitor. In unique studies using ABA deficient mutants of Arabidopsis, exogenous ABA addition or ABA biosynthesis inhibitor application and simulated drought stress, ABA was shown to have a profound effect on the outcome of interactions between plants and pathogens of differing lifestyles and from different kingdoms. The systems used included a model plant and an important agricultural species: Arabidopsis thaliana (Arabidopsis) and Peronospora parasitica (a biotrophic Oomycete pathogen), Arabidopsis and Pseudomonas syringae pathovar tomato (a biotrophic bacterial pathogen) and an unrelated plant species, soybean (Glycine max) and Phytophthora sojae (a hemibiotrophic Oomycete pathogen), Generally, a higher than basal endogenous ABA concentration within plant tissues at the time of avirulent pathogen inoculation, caused an interaction shift towards what phenotypically resembled susceptibility. Conversely, a lower than basal endogenous ABA concentration in plants inoculated with a virulent pathogen caused a shift towards resistance. An extensive suppressive effect of ABA on defence responses was revealed by a range of techniques that included histochemical, biochemical and molecular approaches. A universal effect of ABA on suppression or induction of the phenylpropanoid pathway via regulation of the key entry point gene, phenylalanine ammonia-lyase (PAL), when stimulated by biotic or abiotic elicitors was shown. ABA also influenced a wide variety of other defence-related components such as: the development of a hypersensitive response (HR), the accumulation of the reactive oxyden species, hydrogen peroxide and the cell wall strengthening compounds lignin and callose, accumulation of SA and the phytoalexin, glyceollin and the transcription of the SA-dependent pathogenesis- related gene (PR-1). The near genome-wide microarray gene expression analysis of an ABA induced susceptible interaction also revealed an yet unprecedented insight into the great diversity of defence responses that were influenced by ABA that included: disease resistance like proteins, antimicrobial proteins as well as phenylpropanoid and tryptophan pathway enzymes. Subtle differences were found in the number and type of defence responses that were regulated by ABA in each type of plant and pathogen interaction that was studied. This thesis has clearly identified in plant/pathogen interactions previously unknown and important roles for ABA in the regulation of many defence responses.

Cardiovascular health behaviours and health needs among people with psychiatric disabilities

Recent research in Australia has found that people with a mental illness experience higher mortality rates from preventable illnesses, such as cardiovascular disease, respiratory disease and diabetes compared to the general population. Lifestyle and other behavioural factors contribute significantly to these illnesses. Lifestyle behaviours that affect these illnesses include lack of physical activity, consumption of a poor diet and cigarette smoking. Research on the influence of these factors has been mainly directed towards the mainstream population in Australia. Consequently, there remains limited understanding of health behaviours among individuals with psychiatric disabilities, their health needs, or factors influencing their participation in protective health behaviours. This thesis presents findings from two studies. Study 1 evaluated the utility of the main components of Roger’s (1983) Protection Motivation Theory (PMT) to explain health behaviours among people with a mental illness. A clinical population of individuals with schizophrenia (N=83), Major Depressive Disorder (MDD) (N=70) and individuals without a mental illness (N=147) participated in the study. Respondents provided information on intentions and self-reported behaviour of engaging in physical activity, following a low-fat diet, and stopping smoking. Study 2 investigated the health care service needs of people with psychiatric disabilities (N=20). Results indicated that the prevalence of overweight, cigarette smoking and a sedentary lifestyle were significantly greater among people with a mental illness compared to that reported for individuals without a mental illness. Major predictors of the lack of intentions to adopt health behaviours among individuals with schizophrenia and MDD were high levels of fear of cardiovascular disease, lack of knowledge of correct dietary principles, lower self-efficacy, a limited social support network and a high level of psychiatric symptoms. In addition, findings demonstrated that psychiatric patients are disproportionately higher users of medical services, but they are under-users of preventive medical care services. These differences are primarily due to a lack of focus on preventive health, feelings of disempowerment and lower satisfaction of patient-doctor relationships. Implications of these results are discussed in terms of designing education and preventive programs for individuals with schizophrenia and MDD.

Mental health and life satisfaction of young Australians : the role of family background

This paper uses the Household, Income and Labour Dynamics in Australia Survey to investigate the factors that influence young Australians’ mental health and life satisfaction, with an emphasis upon the role of family background. It also explores male and female differences concerning those background effects. The results indicate a particularly significant negative association between parental divorce and well-being, and suggest that the timing of divorce matters. Distinguishing the samples by gender shows that this relationship remains significant only for females. Past living arrangements consistently turn out to be statistically insignificant whether the sample used is the total, males or females. The current living arrangements, however, appear to be significantly associated with both mental health and life satisfaction of males. Adding potentially confounding characteristics to our basic regression, which includes only the family background variables, suggests that some of the ‘aggregate’ effects of family background might work indirectly through the mediating variables such as education or lifestyles, though most of them remain direct. Among those, marital status, education, labour market experience and lifestyles seem to be the major factors explaining the dispersion in well-being of young Australians. Income and wealth, on the other hand, have only a minor impact.

Changes in body image satisfaction during pregnancy : a comparison of high exercising and low exercising women

Objective: This study aimed to compare ratings of body image satisfaction (BIS) from 6 months prepregnancy to 23–30 weeks’ gestation for high exercising and low exercising pregnant women. The authors also aimed to assess and compare expectations of BIS for the post-partum period in high and low exercising women.

Design: A partial prospective approach was Implemented.

Sample: A total of 71 healthy pregnant women (40 high exercisers and 31 low exercisers) participated.

Methods: Participants completed a series of questionnaires at 15–22 weeks’ gestation and 23–30 weeks’ gestation.

Main outcome measures: There were two main outcome measures. At 15–22 weeks’ gestation there was an exercise inventory and two versions of the Body Cathexis Scale (BCS) (retrospective prepregnancy BIS and current BIS). At 23–30 weeks’ gestation there was an exercise inventory and two versions of the BCS (current BIS and projected post-partum BIS).

Results: At 15–22 weeks’ gestation, high exercisers demonstrated significantly higher levels of BIS compared to low exercisers. There were no other significant differences between groups. Within groups, high exercisers were significantly more satisfied with their bodies at 15–22 weeks’ gestation compared to 6 months prepregnancy, and expected to be less satisfied with their bodies at 6 weeks’ post-partum than they were during pregnancy. Low exercisers demonstrated no significant changes over time.

Conclusions: The findings suggest that women are able to assimilate the bodily changes of pregnancy without a negative shift in BIS. However, women who exercise during pregnancy may respond more favourably to changes in their bodies at early pregnancy compared to women who remain sedentary.

Patterns of physical activity for adolescent girls in Fiji and Tonga

Behavioural patterns are determined in part by sociocultural factors such as values, expected behaviours and sociopolitical organisation. This paper presents the patterns of physical activity reported by Tongan and Fijian females aged 12-18 years and possible explanations for these patterns. The paper draws on interviews conducted in a wider study of adolescents patterns of eating, physical activity and body size in Tonga, Fiji, New Zealand and Australia. The study examined sociocultural factors that could promote or protect against obesity from the perspective of adolescents in order to develop culturally-appropriate strategies for healthy lifestyles. Twenty four indigenous Fijian and 24 Tongan females aged 12-18 years were interviewed by females who were fluent in participants first languages. Researchers from Australia, Tonga and Fiji analysed the data separately and then together in order to capture cultural nuances and enhance cultural validity. This analysis revealed similarities and differences in both cultural groups. Limitations to physical activity identified by Tongan and Fijian girls included the time spent in household chores and parental restrictions.Fijian girls also identified concern about personal safety as a constraint. These findings are examined in relation to sociocultural factors that appear to limit opportunities for young females to be physically active.

Dutch Indonesians in Australia : second-generation identity in the diaspora

Exploring "local" and "transnational" relationships, this research shows that second-generation relationships with the homeland and with other members in the diaspora are less important regarding (diasporic) identity formation than realities of sedentary diasporic life (in Australia) and that "locality" and diaspora are not opposing concepts but theoretically and practically interconnected.

Exploring jockey and family life through a social health lens

Workplace practices form an overarching social determinant of health for Victorian jockeys and their families. This research highlights the importance of riding opportunity, coping with risk and danger, and the gratification associated with the lifestyle to be key characteristics that impact on jockey family health for the better or worse.

Health beliefs and behaviours of home economics teachers in Victoria

Data from questionnaires mailed to post-primary home economics teachers suggests that they possess untapped knowledge and expertise that could be used in intersectoral approaches to health promotion outside classroom teaching.

Associations of residential density with adolescents’ physical activity in a rapidly urbanizing area of mainland China

In the context of recent social and economic transitions in China, lack of physical activity among adolescents is an emerging health risk, particularly so in rapidly expanding urban areas. Evidence from Western countries suggests that built environment attributes can influence the physical activity participation of young people, but whether or not this is the case for China is unknown. We recruited high school students from ten urban districts in Nanjing, Mainland China (n=2,375; mean age=13.9± 1.0 years old; 46% boys; survey response rate=89%). The outcome variable was selfreported recreational physical activity time; the primary explanatory variable was the residential density of the urban districts. Analysis was conducted using mixed-effects logistic regression models. After adjustment for potential confounding variables, including sedentary behavior and green space, there was a consistent and graduated association between residential density and physical activity; residential density was significantly negatively associated with recreational physical activity time for students from the higher tertile of residential density (OR; 95% CI=0.64; 0.42 to 0.97) compared to those from the lower tertile. The direction and magnitude of the negative association between residential density and physical activity was similar for boys and girls. It should be a public health priority to identify the particular urban environment attributes that can encourage and support young people’s participation in physical activity.

Residential density and adolescent overweight in a rapidly urbanising region of mainland China

Objective This study investigated the association of residential density with overweight among adolescents in an urban area of China.

Methods Using multistage proportional sampling methods, a population-based cross-sectional study was conducted in Nanjing between September and November 2004 (n=2375; mean age=13.9+/-1.0 years old; 46.2% boys; survey response rate=89.3%). Body mass index was calculated from self-reported body weight and height. Overweight, the main outcome variable, was defined as a BMI >/=85 percentile value for age- and gender-specific reference data according to the recommendation for Chinese adolescents. The primary explanatory variable was the residential density of the urban districts. Mixed-effects logistic regression models were used for the analysis.

Results Students in the higher and middle tertiles of residential density had a 2.17-fold (95% CI 1.41 to 3.33) and 1.89-fold (95% CI 1.22 to 2.92) higher likelihood of being overweight, respectively, compared with those in the lower tertile. The associations were slightly attenuated but still significant after adjusting for time spent in recreational physical activity and sedentary behaviour (viewing TV and sitting for academic study).

Conclusions Residential density was positively associated with overweight among urban Chinese adolescents. Our findings warrant further research examining attributes of urban environments associated with adolescents' obesity in China and potential mechanisms between them.

Habitual active transport moderates the association of tv viewing time with body mass index

Background: Television viewing time is associated with obesity risk independent of leisure-time physical activity (LTPA). However,
it is unknown whether the relationship of TV viewing time with body mass index (BMI) is moderated by other domains of physical activity. Methods: A mail survey collected height;weight; TV viewing time; physical activity for transportation (habitual transport behavior; past week walking and bicycling), for recreation (LTPA), and in workplace; and sociodemographic variables in Adelaide, Australia. General linear models examined whether physical activity domains moderate the association between BMI and TV viewing time. Results: Analysis of the sample (N = 1408) found that TV time, habitual transport, and LTPA were independently associated with participant’s BMI. The interaction between TV time and habitual transport with BMI was significant, while that between TV time and LTPA was not. Subgroup analyses found that adjusted mean BMI was significantly higher for the high TV viewing category, compared with the low category,
among participants who were inactive and occasionally active in transport, but not among those who were regularly active. Conclusions: Habitual active transport appeared to moderate the relationship between TV viewing time and BMI. Obesity risk associated with prolonged TV viewing may be mitigated by regular active transport.

Physical activity levels of Hungarian children during school recess

Objective : The purpose of this study was to examine physical activity levels and patterns of physical activity across daily school recess periods, and the contribution of recess to daily physical activity.

Method : Ninety-eight children (61% boys) from three schools in Hungary had their physical activity quantified using uni-axial accelerometry every 5 s for three consecutive school days (Wednesday to Friday). The proportion of time spent in sedentary, light, moderate-to-vigorous, and vigorous physical activity during 5 daily school recess periods was determined using existing age-appropriate cut-points. The relative contribution of recess to daily moderate-to-vigorous physical activity was also determined. Data were collected between May and October 2008.

Results : Boys engaged in significantly more light (30.6 ± 5.2%; 27.7 ± 5.1%), moderate-to-vigorous (24.9 ± 8.9%; 17.5 ± 5.2%) and vigorous physical activity (7.6 ± 4.7%; 4.3 ± 2.9%) than girls during recess. Girls (54.8 ± 8.1%) engaged in more sedentary activity than boys (44.5 ± 10.2%). Physical activity levels were generally similar across multiple recess periods. Recess contributed more moderate-to-vigorous physical activity towards weekday physical activity for boys (13.1%) than girls (10.8%).

Conclusions : Since sedentary activity accounted for the largest proportion of recess, interventions may be needed across all recess periods to promote physical activity during the school day.

The contribution of upper limb and total body movement to adolescents’ energy expenditure whilst playing Nintendo Wii

Little research documents the contribution of upper limb and total body movement to energy expenditure (EE) during active video gaming. To address this, EE, heart rate (HR), and, upper limb and total body movement were assessed in 11- to 17-year-old adolescents whilst playing three active (Nintendo Wii) and one sedentary (XBOX 360) video games. Non-dominant upper limb activity, EE and HR were significantly greater during Wii Sports boxing [mean 267.2 (SD 115.8) J kg−1 min−1; 136.7 (24.5) beats min−1] than tennis or bowling (P ≤ 0.044). For all active games hip activity best predicted EE (R 2 ≥ 0.53), with two-measure models of HR and single-site activity data, and multi-site activity data, similarly explaining the variance in EE (R 2 ≥ 0.64). The physiological cost of upper-body orientated active video games increased when movement of both upper limbs was encouraged. Improvements in EE explanatory power provide support for multi-site activity monitoring during unique, non-ambulatory activities.

Energy expenditure in adolescents playing new generation computer games

Objective: To compare the energy expenditure of adolescents when playing sedentary and new generation active computer games.

Design: Cross sectional comparison of four computer games. Setting Research laboratories.

Participants: Six boys and five girls aged 13–15 years.

Procedure: Participants were fitted with a monitoring device validated to predict energy expenditure. They played four computer games for 15 minutes each. One of the games was sedentary (XBOX 360) and the other three were active (Wii Sports).

Main outcome measure: Predicted energy expenditure, compared using repeated measures analysis of variance.

Results: Mean (standard deviation) predicted energy expenditure when playing Wii Sports bowling (190.6 (22.2) kl/kg/min), tennis (202.5 (31.5) kl/kg/min), and boxing (198.1 (33.9) kl/kg/min) was significantly greater than when playing sedentary games (125.5 (13.7) kl/kg/min) (P<0.001). Predicted energy expenditure was at least 65.1 (95% confidence interval 47.3 to 82.9) kl/kg/min greater when playing active rather than sedentary games.

Conclusions: Playing new generation active computer games uses significantly more energy than playing sedentary computer games but not as much energy as playing the sport itself. The energy used when playing active Wii Sports games was not of high enough intensity to contribute towards the recommended daily amount of exercise in children.

Relationships of land use mix with walking for transport : do land uses and geographical scale matter?

Physical activity and public health recommendations now emphasize the creation of activity-friendly neighborhoods. Mixed land use in a neighborhood is important in this regard, as it reflects the availability of destinations to which residents can walk or ride bicycles, and thus is likely to contribute to residents’ active lifestyles that in turn will influence their overall health. Relationships between land use mix (LUM) and physical activity have not been apparent in some studies, which may be because geographical scale and the specificity of hypothesized environment–behavior associations are not taken into account. We compared the strength of association of four Geographic Information Systems-derived LUM measures with walking for transport and perceived proximity to destinations. We assessed physical activity behaviors of 2,506 adults in 154 Census Collection Districts (CCDs) in Adelaide, Australia, for which ‘‘original’’ LUM measures were calculated, and then refined by either: accounting for the geographic scale of measurement; including only the most-relevant land uses; or, both. The refined (but not the ‘‘original’’) LUM measures had significant associations with the frequency of walking for transport (p < 0.05) and area-corrected measures had significant associations with the duration of walking for transport. All LUM measures had significant associations with perceived proximity to destinations, but stronger associations were seen when using the refined measures compared with the original LUM. Identifying the LUM attributes most strongly associated with walking for transport is a priority and can inform environmental and policy initiatives that are needed to promote health-enhancing physical activity.