published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

Stroke is a preventable disease. Minor stroke and transient ischaemic attack (TIA) are important warning signs of the possibility of a major stroke. Worldwide, stroke is the third most common killer and the largest cause of disability. The incidence of stroke is predicted to increase with the predominance of unhealthy lifestyles and the aging population. The adoption of a healthy lifestyle can reduce many of the risk factors. This descriptive study was designed to explore patients’ understanding of modifiable risk factors of cerebrovascular disease. It investigated lifestyle changes actually made, as well as the factors affecting patients’ decisions about whether to make lifestyle changes. The two major factors considered were patients’ sources and level of knowledge and their attitudes and beliefs around making changes. A convenience sample of patients who had suffered a minor stroke or TIA was recruited through a major metropolitan hospital. Thirty-five subjects responded to a postal questionnaire. The mean age was 68 years and 37% of the subjects had sustained some disability as a result of the TIA or minor stroke. The results demonstrated that many subjects had a poor understanding of risk factors of stroke. While smoking was well recognised as a risk factor, subjects showed less awareness of other risk factors, such as excessive alcohol consumption and obesity. Subjects also reported significant confusion regarding diet. Sixty-six percent of subjects depended on doctors as their main source of health information. This may be problematic as the current shortages of General Practitioners has put pressure on doctors to keep appointment times short and reduce the time available for health education. The main barriers to lifestyle change, were lack of motivation, and inadequate, knowledge, guidance, and support and the inability to access good information. Although 83% of subjects suffered from hypertension, medication was the accepted method of control, few subjects realised the significance of lifestyle factors. Nine percent of subjects were only diagnosed with hypertension after their stroke or TIA and few monitor their own blood pressure, despite the wide availability of home monitoring devices. From the findings of this study it is concluded that health promotion and education are very important strategies in the prevention of stroke and it is recommended that this kind of education begins in childhood with tailored, age-specific programs delivered to the public over the lifespan. The role of health screening cannot be underestimated in the detection of risk factors such as hypertension and obesity. Early detection makes effective treatment possible and helps prevent the occurrence of strokes, thus reducing the cost to the community. Long-term health strategies such as improving health resource distribution and enhancing health education are needed where patients and their families participate together in comprehensive education programs. It is hoped that this may lead to a shared understanding, which may translate to patients being more supported, and therefore more able, to make the necessary lifestyle changes. Dysphagia is a common complication following stroke, which can result in significant morbidity and mortality. Multidisciplinary collaboration facilitates management strategies, decision-making and the efficiency of rehabilitation. Nurses are responsible for coordination of management and in particular for continuous monitoring, assessment of swallowing and nutritional state, maintaining safety and preventing complications. An understanding of the issues and strategies relating to management may provide valuable information to enhance the safety, cost-effectiveness and quality of care. A retrospective review of patients’ medical records was used to collect data. A sample of ninety-five adults who were admitted to an Australian public hospital between January 2003 and April 2006, with a diagnosis of dysphagic stroke were recruited. Statistical Package for Social Sciences (SPSS) was used to analyse the quantitative data, while content analysis was used to analyse the qualitative data. All subjects were assessed by a speech pathologist, the mean age was 75 years and 50.5% were male. Except for critically ill subjects, almost all were assessed within three days. Ninety-six percent of subjects had communication problems and 81% had upper limb motor impairment. During hospitalisation almost 60% of subjects had an improvement in their oral intake including 8% resuming their premorbid diet. Eighteen percent were on enteral tube feeding upon discharge, 4% deteriorated and 16% died. It appears that oral intake of most subjects was unsatisfactory. When recorded the mean body weight lost was 2.3kg. At least 22% had malnutrition or dehydration. Forty-five percent aspirated and 22% had respiratory infection. Almost half of the subjects (48%) were discharged to aged care facilities. Eighty percent had no documented follow-up scheduled for management of their dysphagia. Early identification of dysphagia, prudent supervising of appropriate oral intake and mouth care may help to maintain safe swallowing, preventing aspiration and chest infection. Regular checks of body weight, serum albumin level, oral intake and early enteral feeding are essential to guide nutritional support, minimise malnutrition and problematic medication administration. Encouraging oral intake and providing families with support could promote recovery of swallowing skills and help patients to regain the ability to eat independently. Providing helpful information on the care options available may allay patient and family anxiety. A qualified nurse practitioner could assess patients and ensure that a tailored care plan was designed to meet patients’ needs and this may improve the outcomes considerably. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320650 / Thesis (D.Nurs.) - University of Adelaide, School of Population Health and Clinical Practice, 2008

Stroke is one of the most common causes of disability and death worldwide. The most commonly experienced stroke in the clinical setting is focal ischaemia in which the middle cerebral artery (MCA) is occluded and leads to a complex series of various pathophysiological pathways that ultimately lead to neuronal cell death. Several studies have been conducted on various therapeutic agents in the search for a neuroprotective drug and various animal models have been used to carry out this research. While theanine, a component of green tea and minocycline, a tetracycline antibiotic, have been shown to possess some neuroprotective properties, the mechanisms by which these two agents carry out these effects still remains unclear. The objectives of this study were to investigate the mechanisms by which these drugs carry out these neuroprotective effects and their neuroprotective ability in a MCA occlusion model of focal ischaemia. Ischaemia leads to oxidative stress due to the imbalance of free radicals and the endogenous antioxidant defence system. An antioxidant assay using the stable 2, 2-diphenyl-1-picrylhydrazyl (DPPH●) radical was used to assess the antiradical properties of each drug. It was found that minocycline showed superior antioxidant activity in vitro when compared to theanine. Further studies on the drugs‟ ability to attenuate the Fenton reaction (in which iron catalyses the formation of reactive species) were elucidated using electrochemical analysis, UV/VIS studies, ferrozine and ferritin assays. It was found that minocycline, in contrast to theanine, was able to bind to iron ions and thus potentially prevent the participation of iron in metal catalysed radical reaction. The antioxidant activity of both drugs was further investigated by assessing their effect on cyanide-induced superoxide generation and quinolinic acid (QA)-induced lipid peroxidation (LP). Experimental evidence shows that both drugs had no significant effect on the generation of superoxide in vitro and that there was a significant decrease in LP for minocycline in vitro and theanine in vivo. The metal binding and antioxidant properties were postulated to be a possible mechanism through which these agents reduced lipid peroxidation. A study was conducted to determine the effects of the drugs on the biosynthesis of the neurotoxin, QA and it was found that minocycline increases the levels of holoenzyme activity of tryptophan-2, 3-dioxygenase (TDO) in vitro and that theanine reduces the levels of the same enzyme in vivo after treatment for 10 days. TDO is the enzyme that converts tryptophan to other products that enable enzymatic activity to change it to QA. Minocycline was thought to bring about this effect as it has been shown from preceding experimental studies that it is an effective reducing agent. Theanine on the other hand is hypothesised to bring about a reduction in holoenzyme activity by changing the binding of tryptophan to the enzyme or affecting the radicals that participate in the enzymatic degradation of tryptophan. A focal ischaemic model of stroke was induced by occluding the MCA. Histological examination of the hippocampus post -ischaemia shows a reduction in the size of the infarct after pre-treatment with minocycline only. A further study into the effects of the drugs on the generation of superoxide and on the levels of the endogenous glutathione after a stroke was carried out. Pre-treatment of the animals with either theanine or minocycline showed no significant effects on the generation of the radical species or of the endogenous antioxidant which ruled out these as a mechanism of neuroprotection of both drugs, post-ischaemia.The findings of this study provide novel information on the possible mechanisms by which both theanine and minocycline act to bring about neuroprotection. In particular in this study, pre-treatment with minocycline has shown promise in the focal ischaemic model of stroke.

[Truncated abstract] An elevated total plasma homocysteine concentration (tHcy) is associated with an increased risk of myocardial infarction and ischemic stroke. Folic acid, vitamin B6 and B12 supplements significantly reduce tHcy even in people who are not overtly vitamin deficient. If homocysteine is a causal risk factor for atherothrombotic events, treatment with B-vitamins might prove a simple and cost-effective means to reduce cardiovascular risk. However, it remains unclear whether elevated tHcy causes atherosclerosis or is simply a risk marker. To prove that homocysteine is a modifiable risk factor for cardiovascular disease it is necessary to show that lowering tHcy reduces vascular risk. The aim of this study was to determine whether long-term homocysteine-lowering with B-vitamins would improve vascular structure and function in people with a history of stroke. This study was a cross-sectional sub-study of the Vitamins TO Prevent Stroke trial (VITATOPS), a multi-centre, randomised, double-blind, placebo-controlled clinical trial designed to test the efficacy and safety of B-vitamins (folic acid 2mg, vitamin B6 25mg and vitamin B12 0.5mg) in the prevention of vascular events in patients with a recent history of stroke or transient ischemic attack. 173 VITATOPS participants were recruited for the current study. Age, sex, stroke type, medications, cardiovascular risk factors and smoking history were recorded and blood pressure, height, weight, waist and hip girth were measured in all subjects at least two years after randomisation. ... After a mean treatment period of 3.9 ± 0.9 years, the subjects randomised to vitamin treatment had significantly lower tHcy than the subjects randomised to placebo (7.9mol/L, 95%CI 7.5, 8.4 versus 11.8mol/L, 95%CI 10.9, 12.8; p<0.001). There were no significant differences between groups in CIMT (0.84 ± 0.17mm vitamins versus 0.83 ± 0.18mm placebo; p=0.74) or FMD (median of 4.0%, IQR 0.9, 7.2, vitamins versus 3.0%, IQR 0.6, 6.6 placebo; p=0.48). Pooled estimates from the meta-analyses showed that B-vitamin treatment reduces CIMT by 0.10mm (95%CI –0.20, -0.01mm) and increases FMD by 1.4%, (95%CI 0.7, 2.2), although these estimates may have been influenced by positive publication bias. The improvement in FMD was significant in studies of less than eight weeks duration but not in studies with longer treatment periods. The association between tHcy and CIMT and FMD was eliminated by adjustment for renal function and long-term B-vitamin treatment did not alter the strong linear relationship between tHcy and cystatin C. Lowering tHcy did not alter arterial wall inflammation assessed by 18FDG-PET, although small subject numbers meant we were unable to exclude a minor treatment effect. Long-term homocysteine-lowering with B-vitamin treatment did not improve CIMT or FMD or reduce arterial wall inflammation in people with a history of stroke. The relationship between tHcy and these markers of vascular risk was eliminated by adjustment for renal function. Our data are consistent with the hypothesis that elevated tHcy is a risk marker for cardiovascular disease rather than a modifiable causal risk factor.