Thesis (M. Phil.)--University of Hong Kong, 1983.

published_or_final_version / Community Medicine / Master / Master of Philosophy

No description available.

No description available.

Cell survival in conditions of severe oxygen deprivation depends on a wide variety of biochemical modifications, which result in a large-scale suppression of metabolism, preventing [ATP] from falling to fatally low levels. We investigated whether AMP-activated protein kinase (AMPK) has a role in the coordination of cellular modification during hypoxia, which leads to a regulated state of metabolic suppression in the goldfish (Carassius auratus). Energy charge, AMPK activity, protein and gene expression, as well as the translational capacity and phosphorylation state of a downstream target were measured in goldfish tissues during exposure to hypoxia (-0.3 mg 02/L) for up to 12 h. AMPK activity in the goldfish liver increased by 4-fold at 0.5 h hypoxia and was temporally associated with a —11-fold increase in calculated AMPfree/ATP. No change was observed in total AMPK protein or relative gene expression of identified AMPK isoforms. Changes in AMPK activity were also associated with a decreased rate of protein synthesis and an increase in the phosphorylated form of eukaryotic elongation factor-2 (eEF2; relative to total eEF2). Increases in AMPK activity were not seen in hypoxic goldfish muscle, brain, heart or gill, nor was a significant alteration in cellular energy charge seen in muscle. Still, the present study is the first to show that AMPK activity increases in liver in response to short-term severe hypoxia exposure in a hypoxia-tolerant fish. The decreased rates of protein synthesis, a well known component of metabolic suppression, combined with increased phosphorylation of eEF2, a downstream target of AMPK, potentially implicate the kinase in the cellular effort to suppress metabolism in hypoxia-tolerant species during oxygen deprivation.

Recent evidence suggests a possible role for the prefrontal cortex (PFC) in sleep/wake regulation and sleep-related electroencephalogram (EEG) activity. This study investigated the effects of cell-specific ibotenic acid lesions to the PFC on sleep-wake patterns and the EEG under baseline conditions and during recovery from a 6 h period of sleep deprivation (SD) using gentle handling in rats. Control rats were injected with saline. PFC lesions had no effects on overall amounts of wake, non rapid-eye movement (NREM) sleep, or rapid-eye movement sleep. However, lesioned animals had fewer wake and NREM sleep episodes and longer mean durations of these episodes particularly during the dark phase. Following SD, no significant lesion effects were observed in sleep rebound or homeostatic increase in NREM EEG delta power (a measure of sleep intensity). These results suggest a role for the PFC in sleep-wake regulation, in particular behavioural state stability.

Obesity is becoming a worldwide concern, with more than 300 million individuals who are obese and a further 750 million who are overweight. This increase is important as obesity has been linked to an increased incidence of cardiovascular disease, type two diabetes mellitus, stroke and some cancers. One factor receiving increasing attention to explain variation in obesity prevalence is the role of the built environment. This involves examining how features of the built environment such as green space or food premises vary by neighbourhood area. The presence of such resources within a neighbourhood can influence obesity through encouraging a healthy or unhealthy environment. It is important to understand how neighbourhoods influence obesity. This will allow the creation of effective public policy and urban design initiatives to reduce the obesity prevalence. Little research has examined how the quality of these resources varies between neighbourhoods and their effect on the prevalence of obesity. This thesis addresses this using a systematic site survey tool to investigate how the quality of built environment resources varies by neighbourhood deprivation. It also employs a questionnaire to examine residents’ perception of their neighbourhood as these can influence obesity through the utilisation of healthy resources. Three key findings were identified: there is a significant relationship between deprivation and the number of neighbourhood resources; the quality of these resources increases as deprivation increases; and residents in a high deprivation neighbourhood had a more positive perception of the neighbourhood. As a result, high deprivation neighbourhoods may be less likely to promote obesity as they have higher quality resources and residents have a more positive perception of the environment. These findings suggest that the influence of the built environment is context specific and that it may not be as influential on obesity in Christchurch. It highlights the need to consider both individual and environmental factors in explaining the geographic variation of obesity.

This thesis investigated the links between public transport use and sociodemographic and land use factors. A dataset of address information about regular bus smartcard users was sourced. These addresses were geocoded using Geographical Information Systems, and the address points derived through this process were used to calculate the percentage of regular bus users in Census meshblock spatial areas. This percentage was then compared to a number of different factors, including deprivation levels (a measure of sociodemographic status), average distance to the nearest bus stop and bus route, and a number of variables from the New Zealand Census of Population and Dwellings, using a number of forms of analysis. The number of cardholders in different residential zonings was assessed, along with the average number of trips taken per day by cardholders. Results indicate that there was a relationship between the regular Metrocard users and deprivation, and regular Metrocard users and land use, however the statistical validity of these relationships was low. Principal component analysis and regression analysis were carried out to assess what variables best explained the proportion of bus use. It was found that the presence of International Students in an area accounted for the biggest variation in the levels of bus use, along with people who were Unemployed and of Maori or Pacific ethnicity, and people who have limited access to vehicles. However, the statistical validity of these results was again low.

There is a known link between relative deprivation and street crime among market liberal countries. Although some research has been done with cross-national data, there is none to suggest that the observed link is as valid in a country well known for its extended welfare and generous social expenditure like Sweden. The following study uses longitudinal data to see if this recognized link between relative deprivation and street crime also stands in a country with almost a century long tradition of striving for social-, economic- and cultural equality. Even though Sweden, over the last decade, has been subjected to a series of deregulations due to policy changes at national level, and with a following rise in inequality, it is still considered to be one of the most equal countries in the west. It is therefore not unlikely that the high degree of social security will reduce the negative impact of relative deprivation on social relations among its citizens, perhaps enough so that the correlation will be significantly weakened. The results indicate that the negative impact of relative deprivation on social relations still remains evident, even with a high degree of social security, suggesting that an extensive welfare does not significantly reduce the negative effect of relative deprivation on social relations.

The objective of this study was to investigate the relationship between the revised Repression-Sensitization Scale and perceived parental behavior as measured on the Short Form Children's Reports o' Parental Behavior: An Inventory. The purpose of this study was to examine previous findings and to attempt to isolate additional factors associated with later neurotic disturbances.The results of the present investigation support earlier findings suggesting that the Repression-Sensitization Scale is linearly associated with neuroticism and personal maladjustment. A significant difference was found between repressors and sensitizers and perception of their parents behavior. The findings indicate that parents of repressors are more accepting then parents of sensitizers. Furthermore, sensitizers were found to have experienced a home environment characterized by family conflict and discord.