This thesis focuses on the regulation of the ubiquitous second messenger Ca2+ in neuronal physiology and disease. Ca2+ signalling in neurons is regulated by ion channels located in the plasma membrane, as well as in the endoplasmic reticulum (ER) and mitochondrial membranes. Ca2+ signalling is essential for numerous cellular processes, including neuronal excitability, neurotransmitter release, synaptic plasticity, and induction of cell death. Age-related disruptions in Ca2+ signalling may contribute to decline of cognitive function and motor control associated with aging. Furthermore, disruption in neuronal Ca2+ signalling is implicated in several neurodegenerative disorders including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and Amyotrophic Lateral Sclerosis (ALS). In this thesis, I studied neuronal Ca2+ signalling and how it is affected in neurodegenerative disease. First, I examined the role of the ER Ca2+ binding protein Calreticulin (CRT) in AD. CRT is involved in regulation of ER Ca2+ signalling and modulation of susceptibility to cell death. I found that there was an increase in the expression of CRT in in vitro and in vivo models of AD. However, increased levels of CRT did not alter susceptibility of neuronal cells to death induced by AD-related stressors. Second, I examined the role of X-Linked Inhibitor of Apoptosis Protein (XIAP) in the modulation of neuronal Ca2+ signalling. I found that overexpression of XIAP in neuronal cells modified Ca2+ signalling by decreasing Ca2+ flux through multiple plasma membrane and ER channels. These effects appear to be independent of caspase inhibition, which is one of the ways that XIAP can inhibit apoptosis. Third, I examined a compound found in green tea, L-theanine, a glutamate receptor antagonist that is protective in models of excitotoxic neuronal injury. I found that 24 hour L-theanine treatment reduces the amount of Ca2+ released from neuronal intracellular stores in response to both glutamate stimulation and passive leak through ER channels. An acute 30 minute L-theanine treatment had similar effects. In conclusion, these observations further the understanding of the regulation of Ca2+ signalling in neurons and may lead to novel therapeutic strategies in neurodegenerative disease. / October 2008

<p>Alzheimer's disease (AD) is a progressive neurodegenerative disease that affects over 5 million people in the United States alone. This number is predicted to triple to by the year 2050 due to both increasing life expectancies and the absence of disease-attenuating drugs. The etiology of AD remains unclear, and although there are multiple theories implicating everything from oxidative stress to protein misfolding, misregulated metal ions appear as a common thread in disease pathology. </p><p>Chelation therapy has shown some effectiveness in clinical trials, but to date, there are no FDA-approved metal chelators for the treatment of AD. One of the biggest problems with general chelators is their inability to differentiate between the metal ions involved in disease progression verses those involved in normal metabolic function. To address this problem, we have developed a prochelator approach whereby the prochelator (SWH) does not bind metals with significant biological affinity. However, once activated to the chelator (CP) via enzymatic hydrolysis, the molecule is able to bind copper and reduce its toxicity both in vitro and in a cellular model of Alzheimer's Disease. </p><p>Central to this strategy is the site-specificity provided by enzymatic activation of the prochelator. In our system, SWH to CP conversion is mediated by beta-secretase, an enzyme involved in A-beta generation. However, in order to render SWH capable of hydrolysis in cells, we modified the prochelator to contain a dihydrocholesterol membrane anchor attached via a polyethylene glycol linker. From this construct, we created beta-MAP, which is an SWH-based FRET probe to demonstrate beta-secretase-mediated conversion of SWH to CP. beta-MAP was also used to confirm the efficacy of a known beta-secretase inhibitor without the need to for mutated cells lines or expensive antibodies. beta;-MAP and the associated microscopy method represent a significant advancement to the currently available ELISA assays for beta-secretase activity.</p><p>While activation of the prochelator by an enzyme in cells is encouraging, non-specific hydrolysis of the peptide prevents significant accumulation of the chelator on the cell membrane. Furthermore, attachment of the polyethylene glycol and sterol units induce cell toxicity not seen with the native CP peptide. These drawbacks prevent the current prochelator from effectively protecting cells from AD conditions. Structural modifications to overcome these problems, including implementation of a new peptide sequence are planned for future experiments.</p> / Dissertation

Alzheimer’s disease (AD), a chronic terminal disease, progressively impairs cognitive function resulting in deterioration of intellect, memory, and personality. With disease progression, the surrogate decision-maker becomes more involved in intervention choices and end-of-life (EOL) care, which may or may not be based on patients’ wishes or best practice guidelines. Yet surrogate decision outcomes involve important issues of medical futility, quality of life and death. The purpose of this study was to examine factors that influence surrogate health care decision-making for a family member during the terminal stage of AD. A descriptive, predictive design was used to address the research questions: 1.What is the relationship between surrogate gender and decision motives?; 2. Do structure (surrogate age and gender, attachment, interpersonal conflict), interactional context (elder image, caregiving beliefs), situational context (dementia level), and perception (burden) variables predict the type of decision motive (reward seeking, altruistic, distress reduction, punishment avoidance) used by surrogates’ when making healthcare decisions for their family member with AD?; 3. What healthcare decision choices do surrogate decision-makers make for a family member with AD? A convenience sample of 58 women (67.2%) and men surrogates between the ages of 43 to 84 years of age (M = 62.22, SD = 9.67) living in one urban and several rural cities in a southeastern state were recruited. Participants were recruited during facility meetings for families at 15 long-term care facilities and 1 dementia care assisted living facility. The majority of participants were Caucasian (84.5%). Questionnaires were distributed to participants at a facility meeting. After the study was explained, written informed consent was obtained. Each participant was asked to complete the questionnaire booklet and return via mail in a stamped self-addressed envelope to the researcher. Data were analyzed with descriptive and inferential statistics including frequencies, percentages, means, standard deviations, t-tests, and multiple linear regressions. Types of decision motives did not differ by gender. For the regression models, the independent variables included gender, feelings of attachment, interpersonal conflict with the elder, beliefs about caregiving, dementia level and caregiver burden. For the model predicting punishment avoidance decision motive, simultaneous multiple linear regression results indicated that the overall model significantly predicted the dependent variable. The regression model predicting reward seeking decision motive results indicated that the overall model significantly predicted the dependent variable. Two of the variables, dementia level and surrogate burden, significantly contributed to the variance in the reward seeking decision motive. When asked about the decisions they have been asked to make in the past 12 months, surrogates were asked to make life supportive interventions (pain management and nutritional supplements) more frequently than life extending interventions. The most frequent life extending interventions chosen in descending order of frequency include surgery, central line placement, and feeding tube placement. This study supports the importance of providing surrogate and family information on AD and end-of-life healthcare interventions in a therapeutic and supportive environment. Nursing implications address pain management of the cognitively impaired patient, advocacy for advance directive completion and non-futile care, and patient and family AD education. Health care implications include process for completion of an advance directive and the burden of medical futility.

Alzheimer’s disease (AD) is a highly complex and rapidly progressive neurodegenerative disorder characterized by the systemic collapse of cognitive function and formation of dense amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs). AD pathology is derived from the cholinergic, amyloid and tau hypotheses, respectively. Current pharmacotherapy with known anti-cholinesterases, such as Aricept ® and Exelon ®, only offer symptomatic relief without any disease-modifying effects (DMEs). It is now clear that in order to prevent the rapid progression of AD, new therapeutic treatments should target multiple AD pathways as opposed to the traditional “one drug, one target” approach. This research project employed medicinal chemistry tools to develop multifunctional small organic molecules against three key targets of AD pathology – the cholinesterases (AChE and BuChE), AChE-induced and self-induced Aβ1-40 aggregation and generation (β-secretase). A chemical library composed of 112 derivatives was generated to gather structure-activity relationship (SAR) data. The derivatives were based on a novel, non-fused, 2,4-disubstituted pyrimidine ring (2,4-DPR) template with substituents at the C-2 and C-4 position varying in size, steric and electronic properties. Molecular modeling was utilized to investigate their binding modes within the target enzymes and along with the acquired SAR, the chemical library was screened to identify lead multifunctional candidates.

Alzheimer’s disease (AD) is a neurodegenerative disorder that is one of such diseases associated with protein aggregation. A&#946; is the main protein component of senile plaques in AD, and is neurotoxic when aggregated. In particular, soluble oligomeric forms of A&#946; are closely related to neurotoxicity. In this dissertation, we examine the differences in A&#946; aggregation intermediates, and final structures formed when only a simple modification in A&#946; aggregation conditions is made, the presence or absence of mixing during aggregation. We show that intermediates in the aggregation pathway show significantly different structural rearrangements. The protein stabilities of &#913;&#946; species show that spherical aggregates corresponding to the most toxic &#913;&#946; species change their structure the most rapidly in denaturant, and that in general, increased toxicity correlated with decreased aggregate stability. In Alzheimer’s disease, even delaying A&#946; aggregation onset or slowing its progression might be therapeutically useful, as disease onset is late in life. Small heat shock proteins (sHsps) may be useful for prevention of &#913;&#946; aggregation, since sHsps can interact with partly folded intermediate states of proteins to prevent incorrect folding and aggregation. In this research, several small heat shock proteins (sHsps) are tested to prevent A&#946; aggregation and toxicity. sHsps used in this research are Hsp17.7, Hsp27, and Hsp20. All types of Hsp20, Hsp20-MBP, His-Hsp20 and His-Hsp20 without 11 residues in C-terminus, can prevent A&#946;1-40 aggregation. Hsp20 also prevents A&#946; toxicity in the same concentration ranges of it aggregation prevention activity. Hsp17.7 and Hsp27, however, can inhibit &#913;&#946;1-40 aggregation but not toxicity. A number of experiments to examine the mechanism of Hsp20 suggest that multivalent binding of sHsp to A&#946; is necessary for the toxicity prevention activity. Conclusively, different A&#946; incubation conditions in vitro can affect the rate of A&#946; fibril formation, the morphology, the toxicity and the conformation of intermediates in the aggregation pathway. Hsp20 rather than other sHsps may be a useful molecular model for the drug design of the next generation of A&#946; aggregation inhibitors to be used in the treatment of AD.

Title from PDF of title page (University of Missouri--Columbia, viewed on Mar. 15, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. J. David Robertson. Vita. Includes bibliographical references.

Source: Masters Abstracts International, Volume: 47-06, page: 3552. Adviser: Stephen C. Waring. Includes bibliographical references.

Thesis (Ph. D.)--University of Queensland, 2003. / Includes bibliographical references.

Dietary manipulations and their pharmacological outcomes have been increasingly studied in neurodegenerative diseases. However, a systematic comparison among different methods in validated animal models of Alzheimer's disease is made necessary due to several different approaches applied in recent studies. Moreover, despite the large body of evidence on the effects of calorie restriction (CR) and ketogenic diets (KDs) on amyloid pathology, no consistent data is available on the effects of calorie restriction, ketogenic diet or ketone supplements on tau pathology in transgenic models of AD. Moreover, the ketogenic diet used in our studies was custom made with low carbohydrate content and rich in medium chain triglyceride (MCT) oils, known to be rapidly metabolized in the liver, resulting in sustained peripheral ketosis. Chapter 1 tested the ability of KD to induce significant ketosis in a mouse model of amyloid deposition. We showed that, despite the mild ketosis induced, KD fed APP mice presented subtle behavioral improvement shown as faster learning in the radial arm water maze, making less errors than APP mice kept on a control diet. Additionally, we observed decreased Aβ immunoreactivity in the anterior cortex of KD fed versus control fed APP mice, despite the lack of changes in congophilic deposits. Due to the mild ketosis induced, a modified ketogenic diet was devised with decreased maltodextrin content and showed greater peripheral levels of β-hydroxybutyrate. Chapter 2 investigated the effects of a ketogenic diet in two transgenic mouse models of Alzheimer's pathology. Interestingly, we found that both transgenic lines, regardless of diet, weighed less than nontransgenic mice, despite their elevated food intake. The reduced body weight may, in part, be explained by the increased locomotor activity shown by both transgenic lines in both the open field and y-maze. Moreover, KD fed mice performed significantly better on the rotarod compared to mice on the control diet independent of genotype. We did not observed KD-induced changes in spatial or associative memory in the radial arm water maze or contextual fear conditioning, respectively. Furthermore, immunohistochemical levels of amyloid, tau, astrocytic and microglial markers showed no differences between animals fed KD or the control diet. Chapter 3 studied the effects of calorie restriction on a mouse model of tau deposition. We show here that 35% body weight reduction in Tg4510 mice did not prevent increased locomotor activity in the open field, previously reported in chapter 2. Similarly, CR did not affect motor performance or spatial memory assessed by the rotarod and radial arm water maze, respectively. Interestingly, CR Tg4510 mice showed improved short-term memory tested by the novel object recognition despite spending a minimal percentage of the trial time interacting with the objects presented. However, this improvement was not observed when the test was modified to replace the objects with mice. In this case, we noticed that nontransgenic mice spent most of the trial time interacting with the novel mouse whereas Tg4510 mice spent roughly the same amount of time at any of the areas in the test chamber. Moreover, no changes in histopathological or biochemical levels of tau, astrocytic, microglial or synaptic markers were observed. Chapter 4 sought to investigate alternative approaches to inducing ketosis in the brain by either administering BHB intracerebroventricularly (i.c.v.) or by using the acetoacetate (AcAc) diester as a dietary supplement in mice. We observed that i.c.v administration of BHB in 20 months old APP mice did not affect body weight or food intake. Consistent with the lack of effects on behavioral performance, amyloid and congophilic load were not different between APP mice infused with either saline or BHB. We also found that enteral administration of AcAc diester was well tolerated and induced peripheral ketosis for at least 3 hours. Acute ketosis, however, was not sufficient to attenuate behavioral deficits in old APP mice. Chronic dietary supplementation with AcAc was tested in control tet mice and was shown to effectively induce ketosis in mice fed a diet with normal contents of carbohydrates. Nonetheless, we observed that AcAc-induced ketosis was not significantly greater than levels induced by the ketogenic diet tested in our lab. Considering that KD did not rescue behavioral or histopathological features of either amyloid or tau depositing mouse models, we anticipated that dietary supplementation with AcAc would not likely modify the phenotype of the same mouse models tested previously. Taken together, our findings show that our custom made ketogenic diet was effective in inducing and sustaining ketosis and may play an important role in enhancing motor performance in mice. However, the lack of changes on the cognitive and histopathological phenotype of the models studied suggests that KD may not be a disease modifying therapeutic approach to AD. Moreover, calorie restriction showed inconsistent effects on behavioral and histopathological outcomes of a mouse model of tauopathies. Furthermore, dietary supplementation with acetoacetate diester was successful in inducing peripheral ketosis to the same extend as a ketogenic diet even in the context of normal carbohydrate intake, suggesting that it may be of therapeutic interest for diseases of hypometabolism but not a disease modifying therapy in mouse models of Alzheimer's pathology.

The purpose of this research was to determine if incorporating individualized arts and art-making activities into the caregiving of persons with Alzheimer's Disease would help to improve their overall quality of life. To answer this question, I conducted an eight-week qualitative case study of two persons with Alzheimer's Disease. I visited the patients and their caregivers in their homes, and facilitated the incorporation of arts and art-making activities into their caregiving. These activities included painting with watercolors and acrylic paints, sewing, dancing, listening to music, collage, craftwork, storytelling, and sharing past art experiences. As a result of participating in this case study, the two persons with Alzheimer's Disease experienced increased confidence and self-esteem, a positive means of communication and social engagement, an opportunity to be validated and valued as persons with a rich life history and valuable remaining talents, and they developed new physical and mental abilities. / text