Caring for an individual with Alzheimer’s disease is especially challenging and impacts every aspect of the lives of the informal caregivers. Informal caregiving is defined as unpaid care provided by family or friends to people with a chronic illness or disability (Young & Newman, 2002). Caregiver burden involves the physical, psychological, social and emotional problems experienced by a caregiver of an impaired loved one (Gwyther & George, 2006). Alzheimer’s disease caregivers report more depression than their caregiving and non-caregiving peers, experience increased physical decline, and often experience financial challenges. Evidence suggests Alzheimer’s disease caregiver burden is a result of both care recipient and caregiver factors. Pearlin et al’s Stress Process model (1990) is widely used to examine triggers in caregiver burden. The model consists of antecedents, stressors, and outcomes. Few studies have examined moderators in the burden process in Alzheimer’s disease caregiving. Whether resilience accounts for variance in outcomes associated with caregiver burden is not addressed in the literature. Data from a convenience sample of Alzheimer’s disease caregivers (N=111) were examined for the purpose of exploring the moderating effect of resilience on the relationship between stressors and caregiver burden predictors. RESULTS: Resilience did not moderate the relationship between the caregiver stressors and caregiver burden. However, results indicated a relationship between resilience and caregiver burden. Specifically, as resilience increases, caregiver burden decreased. This finding highlights the importance of Alzheimer’s caregivers and implementing support and interventions that will increase their resilience.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 160-193).

Thesis (M.Tech.-Medical Technology)--Cape Technikon, 1997. / Bibliography: leaf 96-114. Also available online.

Alzheimer’s disease (AD) is a neurodegenerative disorder that is one of such diseases associated with protein aggregation. Aβ is the main protein component of senile plaques in AD, and is neurotoxic when aggregated. In particular, soluble oligomeric forms of Aβ are closely related to neurotoxicity. In this dissertation, we examine the differences in Aβ aggregation intermediates, and final structures formed when only a simple modification in Aβ 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 Αβ species show that spherical aggregates corresponding to the most toxic Αβ 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 Aβ 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 Αβ 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 Aβ 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 Aβ1-40 aggregation. Hsp20 also prevents Aβ toxicity in the same concentration ranges of it aggregation prevention activity. Hsp17.7 and Hsp27, however, can inhibit Αβ1-40 aggregation but not toxicity. A number of experiments to examine the mechanism of Hsp20 suggest that multivalent binding of sHsp to Aβ is necessary for the toxicity prevention activity. Conclusively, different Aβ incubation conditions in vitro can affect the rate of Aβ 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 Aβ aggregation inhibitors to be used in the treatment of AD.

Amyloid diseases are a world-wide problem causing great human suffer and large economical costs. Although amyloid deposits, a common denominator in all amyloid disorders, are detrimental to the surrounding tissue, there is a poor correlation between total amyloid burden and clinical symptoms. Soluble oligomers are much more potent to exert a tissue damaging effect.  Alzheimer’s disease (AD) is strongly linked to self-assembly of the amyloid-β (Aβ) peptide. Antibodies selectively targeting cytotoxic Aβ-species are useful both for understanding oligomer formation and for their therapeutic abilities. We hypothesized that the effect of avidity would compensate for a low single site affinity and be enough to selectively target oligomers. To evaluate this hypothesis, we focused on the IgM isotype having ten antigen-binding sites. In accordance with the hypothesis, the IgM isotype effectively bound oligomeric Aβ also in presence of a vast excess of its monomeric counterpart, clearly illustrating the potentiating effect of avidity. As a continuation of this work, we have shown that the avidity effect from a bivalent binding is enough to induce oligomer specificity. This finding facilitates a direct application on the clinically more useful IgG isotype, where the binding properties now can be controlled in detail. The method is general and we have, using this technique, also designed oligomer specific antibodies targeting α-synuclein. Transthyretin (TTR) is an amyloidogenic protein involved in both hereditary and sporadic amyloidosis. The cytotoxicity of TTR is intriguing since studies have shown cytotoxic potential from oligomers, tetramers and even monomers. Elucidation of the molecular properties associated with TTR cytotoxicity is hence of interest. By preventing tetramer dissociation, TTR aggregation and TTR-induced cytotoxicity is abolished. Based on this rationale, a current therapeutic strategy is to stabilize the TTR tetramer with small molecules. The kinetic stability within the spectra of known TTR mutations spans more than three orders of magnitude. However, although the most stable mutants are inert, a poor correlation within the group of cytotoxic variants exists where the cytotoxic effect is not potentiated in proportion to their kinetic stability. Through analysis of a large spectra of TTR variants, our results indicate that TTR induced cytotoxicity requires an intermediate stability of the TTR molecule. The kinetic stability should be low enough to permit tetramer dissociation and the thermodynamic stability high enough to prevent instant aggregation and to allow formation of the cytotoxic fold.

Alzheimer’s disease is a neurodegenerative disease characterised by progressive memory deterioration and cognitive impairment. Pathological hallmarks are extracellular senile plaques, neurofibrillary tangles and neuron loss. Senile plaques are produced through altered processing of the membrane-bound protein APP. Different neurotransmitter signal transduction pathways have been implicated in the formation or development of Alzheimer’s pathologies, but the molecular mechanisms behind these changes are not well known. The overall aims of this thesis were to identify novel genes with differential expression in Alzheimer’s disease and to investigate mechanisms initiating these changes and their relationship to the disease. A real-time RT-PCR strategy was developed to enable detection of small mRNA changes in human brain autopsy samples. This approach was first used to investigate levels of expression of a candidate gene (MAO), and later employed to verify gene expression differences detected by cDNA microarray analysis. Of several genes verified as differentially expressed in the patients, ITPKB (Inositol 1,4,5-trisphosphate 3-kinase B) and RGS4 (Regulator of G-protein signalling 4) presented the largest expression differences in Alzheimer’s cases compared to control samples. Several splice variants of RGS4 showed similar down-regulation levels and one rare haplotype was associated with decreased RGS4 expression. Functional studies in SH-SY5Y cell cultures overexpressing RGS4 showed that it is likely that RGS4 affects APP processing by regulating PRKC expression levels. The combined expression of RGS4 and ITPKB is for the first time presented in this thesis as genes with altered mRNA levels in Alzheimer’s disease. These two genes are implicated in the same signalling pathway that modifies calcium levels in the cell. Furthermore, the fact that RGS4 affects APP processing suggests that RGS4 is involved in the development of senile plaques. This motivates further functional studies of this gene and suggests that RGS4 may become a new potential drug target for Alzheimer’s disease.

Alzheimer’s disease (AD) is the most common cause of dementia. A characteristic feature of AD is the presence of amyloid plaques in the cortex and hippocampus of the brain. The principal component of these plaques is the amyloid-β (Aβ) peptide, a cleavage product from proteolytic processing of amyloid precursor protein (APP). A central event in AD pathogenesis is the ability of Aβ monomers to aggregate into amyloid fibrils. This process involves the formation of various Aβ intermediates, including protofibrils. Protofibrils have been implicated in familial AD, as the Arctic APP mutation is associated with enhanced rate of protofibril formation in vitro. This thesis focuses on Aβ aggregation and neurotoxicity in vitro, with special emphasis on protofibril formation. Using synthetic Aβ peptides with and without the Arctic mutation, we demonstrated that the Arctic mutation accelerated both Aβ1-42 protofibril- and fibril formation, and that these processes were affected by changes in the physiochemical environment. Oxidation of Aβ methionine delayed trimer and protofibril formation in vitro. Interestingly, these oxidized peptides did not have the neurotoxic potential of their un-oxidized counterparts, suggesting that formation of trimers and further aggregation into protofibrils is necessary for the neurotoxic actions of Aβ. In agreement, stabilization of Aβ wild type protofibrils with the omega-3 (ω3) fatty acid docosahexaenoic acid (DHA) sustained Aβ induced neurotoxicity; whereas in absence of DHA, neurotoxicity was reduced as Aβ fibrils were formed. These results suggest that the neurotoxic potential of Aβ is mainly confined to soluble aggregated forms of Aβ, not Aβ monomer/dimers or fibrillar Aβ. Stabilization of Aβ protofibrils with DHA might seem contradictory, as ω3 fatty acids generally are considered beneficial for cognition. However, we also demonstrated that DHA supplementation reduced Aβ levels in cell models of AD, providing a possible mechanism for the reported beneficial effects of DHA on cognitive measures in vivo.

The p38 mitogen-activated protein kinase [p38(MAPK)] mediates responses to extracellular stressors. An increase in the phosphorylated form of p38(MAPK) [p-p38(MAPK)] has been associated with early events in Alzheimer disease (AD). Although most often associated with processes including apoptosis, inflammation and oxidative stress, p-p38(MAPK) also mediates beneficial physiological functions, such as cell growth, survival and phagocytosis of cellular pathogens. Amyloid plaques [β-amyloid aggregates] are a hallmark of AD-related pathology. As p38(MAPK) has been detected in the vicinity of senile plaques, we combined immunohistochemistry and stereological sampling to quantify the distribution of plaques and p-p38(MAPK)-immunoreactive (IR) cells in the sensorimotor cortex of 3-, 6- and 10-month-old TgCRND8 mice. This animal model expresses an aggressive nature of the AD-related human amyloid-β protein precursor (APP). It was confirmed by the appearance of both dense-core (thioflavin-S-positive) and diffuse plaques, even in the youngest mice. p-p38(MAPK)-IR cells were associated with both dense-core and diffuse plaques, but the expected age-dependent increase in the density of plaque-associated p-p38(MAPK)-IR cells was restricted to dense-core plaques. Furthermore, the density of dense-core plaque-associated p-p38(MAPK)-IR cells was inversely correlated with the size of the core within the given plaque, which supports a role for these microglia in restricting core growth. p-p38(MAPK)-IR cells were also observed throughout wildtype and TgCRND8 mouse cortical parenchyma, but the density of these non-plaque-associated cells remained constant, regardless of age or genotype. We conclude that the constitutive presence of p-p38(MAPK)-IR microglia in aging mouse brain is indicative of a longitudinal role for this kinase in normal brain physiology. Additionally, the majority of p-p38(MAPK)-IR cells were predominantly co-immunoreactive for the Macrophage-1 (CD11b/CD18) microglial marker, regardless of whether they were associated with plaques or localized to the parenchyma. We suggest that the facts that a pool of p-p38(MAPK)-IR microglia appears to restrict b-amyloid plaque core development and the non-pathological role of p-p38(MAPK) in parenchyma, needs to be considered when anticipating targeted p38(MAPK) therapeutics in the context of clinical AD.

The research was designed to investigate the effects of AIT-082, a derivative of the purine hypoxanthine containing a para-amino benzoic acid moiety, on neural cells. AIT-082 has been shown to possess a number of neurotrophic and neuroprotective properties and to enhance memory. Furthermore, AIT-082 is undergoing clinical trials as a potential treatment for Alzheimers disease.<p>The first part of the study investigated the ability of AIT-082 to influence cellular ATP levels in cortical neurons. Decreased energy metabolism is a key point in Yings (Ying, 1996a) theory of the development of Alzheimers disease. Previous work with AIT-082 had shown that it could protect hippocampal neurons from cellular damage caused by sublethal doses of glutamate. Specifically, AIT-082 prevented neurite degeneration. Also, AIT-082 was shown to increase mitochondrial membrane potential, especially at the distal tips of the neurites, in hippocampal neurons. I hypothesized that AIT-082 was protecting the neurons by increasing the ability of the mitochondria to generate ATP and thereby increasing the amount of ATP available to the cell. ATP was collected and measured from cortical neuron cultures that were exposed to glutamate, AIT-082, glutamate and AIT-082. The ATP levels were compared to the ATP levels from cortical neuron cultures that were exposed to vehicle for glutamate and AIT-082. The results did not significantly increase ATP levels in cortical neurons following glutamate exposure. <p>The next set of experiments involved investigations into the ability of AIT-082 to influence phosphorylation events in neural cells. AIT-082 shares some neurotrophic and neuroprotective properties with a group of drugs called the immunophilin ligands. The neuroprotective properties of the immunophilin ligands are mainly due to their ability to influence protein phosphorylation by inhibiting the activity of calcineurin a protein phosphatase. The first set of experiments used western blot techniques to measure serine peptide and threonine peptide phosphorylation levels in proteins from whole brain homogenates that were incubated with vehicle, AIT-082, and GMP. Both AIT-082 and GMP caused an increase in the level of serine peptide phosphorylation compared to vehicle but only the increase caused by GMP treatment proved to be significant. Further, threonine phosphorylation levels were significantly increased by GMP but not AIT-082. Phosphorylation levels of short peptide sequences containing either a phosphorylated serine or threonine residue were also measured in neuronal and astrocytic cultures. The neuronal cultures were exposed to 4 h of hypoxia to mimic the conditions of reduced energy availability observed in Alzheimers disease brains. Astrocyte cultures were exposed to 4 h of hypoxia/ischemia for the same reason. Both cell types were allowed to recover for 0, 1, 4, 12 and 24 hours with or without AIT-082 following the insult. AIT-082 treatment did not significantly affect phosphorylation levels of proteins harvested from either neuron or astrocyte cultures at any time period. I conclude therefore, that AIT-082 is not able to influence phosphorylation of the short amino acid sequences containing phosphorylated serine or threonine residues that could be detected by the primary antibodies used in my experiments.

The research was designed to investigate the effects of AIT-082, a derivative of the purine hypoxanthine containing a para-amino benzoic acid moiety, on neural cells. AIT-082 has been shown to possess a number of neurotrophic and neuroprotective properties and to enhance memory. Furthermore, AIT-082 is undergoing clinical trials as a potential treatment for Alzheimers disease.<p>The first part of the study investigated the ability of AIT-082 to influence cellular ATP levels in cortical neurons. Decreased energy metabolism is a key point in Yings (Ying, 1996a) theory of the development of Alzheimers disease. Previous work with AIT-082 had shown that it could protect hippocampal neurons from cellular damage caused by sublethal doses of glutamate. Specifically, AIT-082 prevented neurite degeneration. Also, AIT-082 was shown to increase mitochondrial membrane potential, especially at the distal tips of the neurites, in hippocampal neurons. I hypothesized that AIT-082 was protecting the neurons by increasing the ability of the mitochondria to generate ATP and thereby increasing the amount of ATP available to the cell. ATP was collected and measured from cortical neuron cultures that were exposed to glutamate, AIT-082, glutamate and AIT-082. The ATP levels were compared to the ATP levels from cortical neuron cultures that were exposed to vehicle for glutamate and AIT-082. The results did not significantly increase ATP levels in cortical neurons following glutamate exposure. <p>The next set of experiments involved investigations into the ability of AIT-082 to influence phosphorylation events in neural cells. AIT-082 shares some neurotrophic and neuroprotective properties with a group of drugs called the immunophilin ligands. The neuroprotective properties of the immunophilin ligands are mainly due to their ability to influence protein phosphorylation by inhibiting the activity of calcineurin a protein phosphatase. The first set of experiments used western blot techniques to measure serine peptide and threonine peptide phosphorylation levels in proteins from whole brain homogenates that were incubated with vehicle, AIT-082, and GMP. Both AIT-082 and GMP caused an increase in the level of serine peptide phosphorylation compared to vehicle but only the increase caused by GMP treatment proved to be significant. Further, threonine phosphorylation levels were significantly increased by GMP but not AIT-082. Phosphorylation levels of short peptide sequences containing either a phosphorylated serine or threonine residue were also measured in neuronal and astrocytic cultures. The neuronal cultures were exposed to 4 h of hypoxia to mimic the conditions of reduced energy availability observed in Alzheimers disease brains. Astrocyte cultures were exposed to 4 h of hypoxia/ischemia for the same reason. Both cell types were allowed to recover for 0, 1, 4, 12 and 24 hours with or without AIT-082 following the insult. AIT-082 treatment did not significantly affect phosphorylation levels of proteins harvested from either neuron or astrocyte cultures at any time period. I conclude therefore, that AIT-082 is not able to influence phosphorylation of the short amino acid sequences containing phosphorylated serine or threonine residues that could be detected by the primary antibodies used in my experiments.