Our group previously reported that caveolin-1 (cav-1) was down-regulated by nitric oxide (NO) during cerebral ischemia and reperfusion (I/R). However, the role of cav-1 in regulating blood-brain barrier (BBB) permeability is unclear yet. This study aims to address whether the loss of cav-1 induced by NO production affects BBB permeability. Data showed that the expression of cav-1 in isolated cortical microvessels was down-regulated in ischemia-reperfused rat brains subjected to middle cerebral artery occlusion (MCAO). Treatment of NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, reserved cav-1 expression, inhibited matrix metalloproteinases (MMPs) activity and reduced the BBB permeability. Moreover, cav-1 knockdown remarkably increased MMPs activity in the culture medium of brain microvascular endothelial cells. Cav-1 deficiency mice displayed higher MMPs activity and BBB permeability than that of the wild-type mice. Interestingly, the effects of L-NAME on MMPs activity and BBB permeability were partly reversed in cav-1 deficiency mice. These results suggest that cav-1 plays important roles in regulating MMPs activity and BBB permeability in cerebral I/R injury. After completing the mechanism study, I investigated the potential drug candidate that targets cav-1 for protecting BBB and neuronal damage during cerebral I/R. Results showed that calycosin, an isoflavones from Astragali Radix, up-regulated the expression of cav-1 and inhibited MMPs activity, and decreased the BBB permeability in the MCAO ischemia-reperfused rat brains. I further investigated the neuroprotective effects of isoflavones of Astragali Radix, with in vitro oxygen glucose deprivation (OGD) model and in vivo cerebral ischemia-reperfusion models. In addition to calycosin and formononetin, two major isoflavones in Astragali Radix, daidzein was also included because it is a metabolite of formononetin after absorption. Results showed that all three isoflavones decreased infarction volume and neurological scores in MCAO rats and dose-dependently attenuated neuronal death induced by L-glutamate treatment and oxygen-glucose deprivation plus reoxygenation (OGD/RO). The neuroprotective effects were inhibited by estrogen receptors (ER) antagonist ICI 182,780. Interestingly, combine treatment of isoflavones displayed synergistic effects in both OGD/RO and L-glutamate induced neuronal injury models, as well as in MCAO cerebral ischemia-reperfusion rat brains. Mechanistically, estrogen receptor antagonist partly reduced the synergism in these models. PI3K/Akt activation was synergistically induced by treatment of those isoflavones simultaneously. In summary, cav-1 could be a potential therapeutic target for protecting the BBB in the treatment of cerebral I/R injury. Major findings in this thesis include: 1) Cav-1 plays an important role in maintaining BBB integrity through inhibition of MMPs activity. NO induced MMPs activities and BBB leakage are partially mediated by the down-regulation of cav-1 during cerebral I/R injury. 2) Calycosin treatment reserved cav-1 expression and reduced BBB permeability. 3) Isoflavones synergistically protected neurons against I/R-induced neuronal insults both in vitro and in vivo. The works provide a valuable step towards the clarification of the physiological and pathophysiological functions of cav-1, and a new clue for developing isoflavones as agents targeting cav-1 for the prevention or treatment of ischemic stroke. / published_or_final_version / Chinese Medicine / Doctoral / Doctor of Philosophy

Ischemic stroke is a leading cause of disability and death around the world. Higher concentration of glutamate following ischemic stroke is a factor leading to cell death, including neural stem cell death. Up to now no effective treatments of ischemic stroke are available. Notoginsenoside R1 (Noto R1) is the main component of Panax notoginseng, which is a traditional Chinese medicine for the treatment of cardiovascular disease. Its protective effects on the neural cell were noted recently. The main purpose of this experimental study was to investigate the mechanism of Noto R1 against glutamate neurotoxicity on primary cultured mouse cortical neural stem cells in vitro, and its effects on ischemic stroke on mice brain in vivo. In the in vitro part, primary culture of neural stem cells was prepared from 12.5-day-old C57BL/6N mice embryos cortex. Neural stem cells were confirmed by nestin-staining and differentiation study afterwards. Then neural stem cells were incubated with Noto R1 and glutamate for 24 hours. Cells were fixed for TUNEL staining and caspase-3 staining. Protein was collected for western blot for Bax, Bcl-2, phos-AKT, JNK/SAPK, and phospho-p38 MAPK. Results showed that glutamate has cytotoxicity in a dose-dependent manner on neural stem cells. Noto R1 showed remarkable neuro-protective effects on neural stem cells exposed to excessive glutamate by higher viability. Noto R1 significantly reduced caspase-3 expression and TUNEL-positive cells. Furthermore, Noto R1 increased the protein expression of Bcl-2 and phospho-AKT, and reduced Bax expression. Moreover apoptosis pathway study showed phospho-p38 expression was suppressed in the Noto R1 group. In the in vivo part, Noto R1 was administrated systemically to mice of MCAo followed by reperfusion. Behavior score and viability rate were assessed before sacrifice. TTC staining was performed for evaluating infarct area, volume and edema. H&E staining was applied for histological examination. TUNEL staining, IHC staining of Nestin, AQP4 and GFAP were performed. In the first part of Noto R1 of 40 mg/kg or PBS was injected into venous at the onset of blood vessel occlusion for 2 hours, and then followed by 22 hours of reperfusion. Results were all negative. In the second part, Noto R1 was injected intra-peritoneum for 10 days prior to MCAo which lasted for 1 hour 50 minutes, then reperfusion was allowed for 22 hours. Results showed Noto R1 improved behavior score and viability rate. Meanwhile Noto R1 significantly reduced ischemic area, volume and edema percentage. Moreover TUNEL-positive cells in the affected cortex were significantly decreased. Nestin-positive cell in the striatum were significantly increased in the Noto R1 group, and immunoactivity of AQP4 and GFAP was apparently decrease with Noto R1 treatment. In conclusion, this study showed that Noto R1 protected cultured neural stem cells against glutamate neurotoxicity in vitro via p38 MAPK pathway by inhibiting Bax protein expression and enhancing protein expression of Bcl-2 and phospho-AKT. Moreover, it also demonstrated significant preventive effects against ischemic stroke with mice model in vivo. In a word Noto R1 presents a highly potential candidate preventing ischemic stroke clinically in the future. / published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

Ischemic stroke is a leading cause of death and long-term disability in the world. Although many pathological aspects of mechanisms are considered to be involved in the stroke, accumulating evidences implicated that inflammation accounts for its progression and complications. Tumor necrosis factor-alpha (TNF-α) and nitric oxide are considered as key mediators produced by cells like microglia in the pathogenesis of the disease. Therefore, the development of therapies targeting at the suppression of nitric oxide and TNF-α productions may ameliorate the severity of ischemic stroke. Gastrodia and Uncaria Decoction (GUD) is a traditional herbal decoction that is commonly used in the therapy of post-ischemic stroke in China. Although it shows great efficacy in clinical treatment, few studies have been conducted to investigate the mechanisms of action of GUD. Furthermore, GUD contains a complex mixture of constituents and the effects of these compounds are unknown. In this study, individual herbs from GUD were extracted and the bioactive fractions were further separated using liquid-liquid partition, silica gel chromatography and high performance liquid chromatography (HPLC). The inhibitory effect of the extracts on lipopolysaccharide (LPS)-stimulated nitric oxide production in BV-2 microglial cells was utilized as the biological marker for the screening. After several rounds of purification, a purified bioactive compound was isolated. After spectroscopic analysis by nuclear magnetic resonance and gas chromatography-mass spectrometry, the compound was identified as genipin (1R,4aS,5,7aS-tetrahydro-1-hydroxy-7-(hydroxymethyl)-cyclopenta[c]pyran-4-carboxylic acid, methyl ester). Mechanisms of the suppressive action on signaling pathways were investigated in the LPS-activated BV-2 cells. Our results demonstrated that genipin can dose-dependently inhibit LPS-stimulated nitric oxide overproduction. It can also suppress mRNA levels and protein expressions of inducible nitric oxide synthase (iNOS) and TNF-αupon LPS-induction. In addition, the phosphorylations of phosphoinositide-3 kinase (PI3K) and protein kinase B (Akt) were suppressed. In contrast, the phosphorylations of mitogen-activated protein kinases (MAPKs), nuclear translocation of nuclear factor-κB (NF-κB) p65 and degradation of inhibitory κB-α (IκB-α) were not affected by genipin. Finally, genipin protected murine Neuro-2a neuroblast against neurotoxicity stimulated by the conditioned media transferred from LPS-challenged BV-2 cells. In conclusion, the anti-inflammatory effects of genipin are via the modulation of PI3K/Akt signaling pathway. Genipin and its synthetic analogues may have great potential for developing into new drugs in treating ischemic stroke. In addition, genipin can be used as the chemical marker to standardize the extract of Eucommia ulmoides Oliver as anti-inflammatory agents for treating inflammatory conditions associated with ischemic stroke. / published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

abstract / Chinese Medicine / Doctoral / Doctor of Philosophy

The purpose of this thesis is to describe the organization of the movements of skilled reaching. Our knowledge of reaching behaviour has been limited to an understanding of specific actions. Results from this thesis describe how reaching is the product of interactions of various parameters that assemble in an integrative way in ontogeny, yet can become dismantled on one level, or generally, throughout multiple levels of what constitutes the behaviour after stroke in adults. These findings demonstrate that skilled reaching constitutes motor parameters that may not be visible in a healthy adult, but that function through development, and by inhibitory systems in adults, to create a smooth and finely articulated action. An examination of the movement patterns of reaching within the full context of the behaviour can be applied to therapeutic strategies for motor disorders and, most importantly, deepen our understanding of the relations between reaching and cognition. / xiii, 254 leaves : ill. (some col.) ; 29 cm

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

More than 15 million people worldwide will suffer a stroke each year two thirds will die or be left permanently disabled. Accordingly, stroke represents an enormous financial burden on the community, due to the cost of hospitalisation, treatment and rehabilitation of stroke patients. Despite the significance of this public health problem, a safe and widely applicable stroke therapeutic remains elusive. Cerebral oedema is widely recognised as a common and often fatal complication of stroke that is associated with worsened outcome. However, the exact mechanisms of oedema formation remain unclear, with current therapies largely ineffective in addressing the mechanisms of cerebral swelling, and also being associated with their own negative side-effect profile. This thesis characterises the role of neurogenic inflammation and the neuropeptide, substance P (SP), in mediating the development of blood brain barrier breakdown, cerebral oedema and resultant functional deficits following stroke, using a rodent model of reversible cerebral ischaemia. The findings of this thesis demonstrate that increased SP immunoreactivity, particularly of the penumbral tissue vasculature, is a feature of tissue perfusion following stroke, but not in non-reperfused infarcts. The central role for SP in the breakdown of the BBB following stroke and the associated deleterious effects of such breakdown was confirmed by studies using an NK₁ receptor antagonist. These antagonists conferred a profound attenuation of BBB breakdown, cerebral oedema formation, neuronal death and injury, and the associated development of functional deficits following reversible stroke. Similarly, depletion of all neuropeptides by capsaicin pre-treatment also reduced both histological abnormalities and functional deficits following stroke, confirming the central role of neuropeptides in the secondary injury process after stroke. The NK₁ receptor antagonist was able to be safely combined with the currently approved treatment for stroke, tPA, producing a synergistic effect of greater protection from the ischaemic insult. In particular, histological and functional outcome were markedly improved, as well as a reduction in the risk of intracerebral haemorrhage and death. Furthermore, the NK₁ receptor antagonist was effective even when administered up to 8 h following the onset of ischaemia, and in a variety of stroke severities. We conclude that SP plays a central role in the secondary injury that occurs following stroke, in particular, the genesis of BBB breakdown and cerebral oedema. Accordingly, combination therapy of tPA and an NK₁ receptor antagonist may offer a novel therapeutic strategy for the clinical management of ischaemic stroke of varying severity. / http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1298280 / Thesis (Ph.D.) -- The University of Adelaide, School of Medical Sciences, 2007

More than 15 million people worldwide will suffer a stroke each year two thirds will die or be left permanently disabled. Accordingly, stroke represents an enormous financial burden on the community, due to the cost of hospitalisation, treatment and rehabilitation of stroke patients. Despite the significance of this public health problem, a safe and widely applicable stroke therapeutic remains elusive. Cerebral oedema is widely recognised as a common and often fatal complication of stroke that is associated with worsened outcome. However, the exact mechanisms of oedema formation remain unclear, with current therapies largely ineffective in addressing the mechanisms of cerebral swelling, and also being associated with their own negative side-effect profile. This thesis characterises the role of neurogenic inflammation and the neuropeptide, substance P (SP), in mediating the development of blood brain barrier breakdown, cerebral oedema and resultant functional deficits following stroke, using a rodent model of reversible cerebral ischaemia. The findings of this thesis demonstrate that increased SP immunoreactivity, particularly of the penumbral tissue vasculature, is a feature of tissue perfusion following stroke, but not in non-reperfused infarcts. The central role for SP in the breakdown of the BBB following stroke and the associated deleterious effects of such breakdown was confirmed by studies using an NK₁ receptor antagonist. These antagonists conferred a profound attenuation of BBB breakdown, cerebral oedema formation, neuronal death and injury, and the associated development of functional deficits following reversible stroke. Similarly, depletion of all neuropeptides by capsaicin pre-treatment also reduced both histological abnormalities and functional deficits following stroke, confirming the central role of neuropeptides in the secondary injury process after stroke. The NK₁ receptor antagonist was able to be safely combined with the currently approved treatment for stroke, tPA, producing a synergistic effect of greater protection from the ischaemic insult. In particular, histological and functional outcome were markedly improved, as well as a reduction in the risk of intracerebral haemorrhage and death. Furthermore, the NK₁ receptor antagonist was effective even when administered up to 8 h following the onset of ischaemia, and in a variety of stroke severities. We conclude that SP plays a central role in the secondary injury that occurs following stroke, in particular, the genesis of BBB breakdown and cerebral oedema. Accordingly, combination therapy of tPA and an NK₁ receptor antagonist may offer a novel therapeutic strategy for the clinical management of ischaemic stroke of varying severity. / http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1298280 / Thesis (Ph.D.) -- The University of Adelaide, School of Medical Sciences, 2007

Early deterioration and long-term recurrence were common after stroke or transient ischemic attach (TIA), however, it is unclear whether they were correlated with active embolization and the consequent new cerebral infarct in acute phase. By employing TCD and diffusion weighted imaging (DWI), we studied the significance of the progression of MES and infarcts during acute phase on the clinical outcomes. We found that the disappearance of MES was correlated with better improvement on day 7 of recruitment; for the long-term outcome, occurrence of exacerbating infarct tended to predict recurrent stroke. Treatment aiming to reduce MES and prevent infarct exacerbation in acute phase may improve the prognosis after stroke. / Finally, one study was performed to assess the changes of hemodynamic parameters after stenting of severe stenosis in the MCA. We aimed to investigate whether TCD can reflect the lumen changes after revascularization and detect hyperperfusion. The findings showed that the velocity of stented MCA in most patients normalized within 24 hours after procedure, but the role of TCD in detecting restenosis in long run needed to be verified; no one suffered from hyperperfusion during the period of our study. The long-term outcomes of patients with normalized velocity versus those with persistently high velocity needed to be further studied. Apart from the velocity changes, changes of the collateral flow after intervention may also be an important part of hemodynamic changes. (Abstract shortened by UMI.) / It was suggested that anti-platelet therapy can reduce the MES, but little was known about the efficacy of low molecular weight heparin (LMWH) although in theory LMWH can reduce the red fibrin-dependent thromboemboli. As a sub-analysis of Fraxiparine in Ischemic Stroke (FISS)-tris study, our study did not show advantages of LMWH in eliminating MES compared with aspirin. / Previous studies showed the accuracy of TCD in diagnosis of middle cerebral artery (MCA) stenosis was variable and the positive predictive value (PPV) was less than 50% in a recent report. One of the important reasons was that most criteria were based on the velocity-only method, ignoring other non-velocity information. Thus, we tried to establish new diagnostic criteria by means of designing an assessment form which integrated more characteristics apart from the velocity acceleration. A composite score for each MCA was calculated according to following parameters in the form: Velocity Scale (score 0-6 for peak systolic velocities<140 to ≥300cm/s), Hemodynamic Scale (score 0-5 for focal or diffuse velocity increase; score 0-6 for differences between bilateral MCA; score 17 for damping velocity), Spectrum Scale (score 0-2 for normal spectrum, turbulence and musical murmurs). Our results showed that compared with the previously reported criteria, the score calculated from the assessment form yielded much more balanced accuracy against magnetic resonance angiography (MRA) and digital subtraction angiography (DSA). However, the composition of the assessment form was only based on personal experience and need to be further modified. Multicenter studies with large sample size are also needed to confirm the advantages of this new method. / Second, we performed three studies to investigate the relationship between the progression of MES and the short or long-term outcome and the relationship between MES and different treatments. / Hao, Qing. / Adviser: Ka Sing Wong. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3419. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 155-181). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

University of Macau / Institute of Chinese Medical Sciences