Aging / Alzheimer's Disease
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Item PHYTOESTROGENS IN THE BRAIN(2013-04-12) Brock, CourtneyPurpose: Soy is one of the top ten herbal supplements taken in the United States. It is generally marketed as a safe and natural way to improve a diverse array of disease conditions such as osteoporosis and to improve menopausal symptoms. Its efficacy, however, has not been completely validated. Genistein, which is a major constituent of soy, is a phytoestrogen, and is thought to elicit some of soy's beneficial effects through activation of estrogen receptors (ER). Despite its wide use, it is currently unclear how genistein might affect the brain. We hypothesize that like estrogen, genistein can be neuroprotective but its capacity to do so is dependent on the availability of "intact" ER-brain derived neurotrophic factor (BDNF) signaling. We have also tested the hypothesis that because ER expression may change as a function of age and sex, such changes may alter genistein's capacity to influence neuroprotective proteins such as BDNF. Methods: This hypothesis was tested using complementary in vitro and in vivo models. For our in vitro experiments we used mouse cerebral cortical explants. Genistein was applied to the cultures at ER activating concentrations. Glutamate was then applied as an excitotoxic insult to induce cell death. Cell death was quantified by measuring the amount of lactate dehydrogenase (LDH) released by the cells into the media. To corroborate our in vitro data, we assessed whether age related changes in ER expression affect genistein's ability to induce BDNF in male and female mice. Results: Our in vitro data indicate that genistein at 100nM significantly reduces the amount of cell death induced by glutamate in cortical explants which express both ERɑ and ERβ. Our in vivo data indicate that age does affect ER expression but it does so in a sex and brain region specific manner. Genistein's effect on BDNF levels were also age, sex, and brain region specific. Conclusions: Our results indicate that genistein can be protective, but its protective effects may be dependent on the expression of appropriate ERs and their capacity to influence BDNF signaling.Item EFFECTS OF SHORT-TERM PHYTOESTROGEN SUPPLEMENTATION ON THE BEHAVIOR OF MALE AND FEMALE MICE(2013-04-12) Sidhu, AkramPurpose: Plant-derived, non-steroidal compounds called phytoestrogens have been widely used as substitutes for estrogen in anticipation of estrogen-like therapeutic effects without producing the side effects associated with estrogen therapy. Human and animal data are still controversial regarding the beneficial effects of such compounds and whether they are differential based on the gender/sex of the subjects. This study investigated the effects of short-term phytoestrogen intake on the age-associated behavioral changes in the young, middle and old mice of both sex. Methods: Separate groups of young (6 months), middle (12 months) and old (24 months) male and female C57BL/6J mice were placed on either a phytoestrogen-free (PF) diet (N=15-17) or a phytoestrogen-rich (PR) diet containing (350-650 mg/kg phytoestrogens (N=16-19) for a period of 16 weeks. After 5 weeks on the diets, the mice were subjected to a series of behavioral tests to measure spontaneous activity (locomotor activity), anxiety (elevated plus maze, EPM), and cognitive function (water maze and active avoidance test). Results: PR mice exhibited increased spontaneous activity when compared to the PF mice, regardless of sex and especially in their rearing activity. In the EPM task, female mice spent less time in the open arms when compared to their males counterpart. At 24 months, PR male mice spent less time in open arms than their age-matched controls. In the water maze, PR mice performed worse than the PF mice which was particularly noticeable in the old mice, however there was no effect of the diet in the males. No major effects of diets were found in the active avoidance paradigm. Conclusions: Overall, short-term supplementation with phytoestrogens did not seem to affect anxiety levels or cognitive, though it may adversely impact spatial learning and memory in female mice, especially of old age.Item EFFECTS OF APOE GENOTYPE, ANTIOXIDANTS AND EXERCISE ON MOTOR AND COGNITIVE FUNCTION(2013-04-12) Chaudhari, KiranPurpose: The ɛ4 allele of apolipoprotein E (ApoE) has been associated with increased risk for development of late-onset Alzheimer's disease (AD). To prevent appearance of brain dysfunction, a healthy lifestyle, such as exercising and eating antioxidants, is often recommended. Physical activity has been shown to have an allele-specific beneficial effect on cognition in humans and rodents. Antioxidant therapy is often suggested to improve brain function, as increased oxidative stress has been correlated with brain dysfunction, especially in ɛ4 carriers. Health conscious individuals are likely to combine exercise with antioxidant intake to increase protection, however recent studies have indicated a negative interaction of these two factors. In some cases, antioxidant intake abolished the beneficial effects of exercise. Our study aimed at determining the nature of the interaction between exercise and antioxidants on functional outcomes in a model of increased AD risk. Methods: Young male and female mice, expressing the human ApoE3 or E4, were placed under one of the treatment: Sedentary/control diet (SedCon), Sedentary /antioxidant-rich diet (Vitamins E and C; SedEC), Exercise/control diet (EXCon), Exercise/ antioxidant-rich diet (EXEC), for 8 weeks prior to behavioral testing. Behavior testing includes running co-ordination (rotorod), spatial learning and memory (Morris Water Maze)and discriminative avoidance and cognitive flexibility (T maze). Results: In a coordination test, the E3 mice performed better than the E4 mice, and a significant improvement was observed with the ExEC treatment in males E3 and females E4. Better spatial learning was detected with EXEC in E3 females but not in E4. In males EX impaired learning index in E3 males. In active avoidance acquisition session, learning performance was improved with EX and EXEC treatment in E3 male, and with EXCon treatment in female E4, whereas cognitive flexibility was improved in both male and female in E3 by all the treatments but not in E4. Conclusions: These results in young mice provide an indication that genotype and sex are critical determinants in the functional outcomes of the treatment.Item TRANSIENT FOCAL CEREBRAL ISCHEMIA INDUCED LONG-TERM COGNITIVE FUNCTION DEFICIT IN AN EXPERIMENTAL ISCHEMIC STROKE MODEL(2013-04-12) Li, WenjunPurpose: Vascular dementia incorporates cognitive dysfunction with vascular disease, which ranks as the second leading cause of dementia in the United States. However, its underlying pathophysiological mechanism is not fully understood and no effective treatment is available. The purpose of the current study was to evaluate long-term cognitive deficits induced by transient middle cerebral artery occlusion (MCAO) in rats and to investigate the potential underlying mechanism. Methods: Sprague-Dawley rats were subjected to transient MCAO or sham surgery. Behavior tests for locomotor activity and cognitive function were conducted at 7 or 30 days after stroke. Hippocampal long term potentiation (LTP) and involvement of GABAergic signaling were evaluated at 30 days after sham surgery or stroke. Immunohistochemistry and Western blots analysis were conducted to determine the effect of MCAO on cell signaling at the hippocampus. Results: Transient MCAO induced progressive decline of cognitive function. At 30 days after stroke, no neuron loss or synaptic makers change in the hippocampus was observed. Reduction of LTP in both side hippocampus was observed at 30 days after stroke, which could be attenuated by blocking of GABAergic signaling. ERK activation was significantly reduced in both side hippocampus at 30 days after stroke. Conclusions: The present study identified a progressive decline of cognitive function after transient focal cerebral ischemia that correlated with suppression of hippocampal LTP, elevation of GABAergic signaling, and inhibition of ERK activation. Our study indicated that attenuating GABAergic activity or enhancing ERK/MAPK activation in the hippocampus might be potential therapeutic targets to prevent and attenuate cognitive function impairment after ischemic stroke.Item A DEPRESSIVE SUBGROUP OF MILD COGNITIVE IMPAIRMENT(2013-04-12) Cushing, BlairPurpose: Late life depression is a risk factor for Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD). MCI represents a transitional period between normal aging and AD and, therefore, represents a potential entry point for preventing AD. Depression is a risk factor for MCI and AD; however, identifying which MCI patients suffer depression-related cognitive impairment remains difficult. The current study sought to identify a clinically-defined depressed sub group among patients with MCI Methods: Data was analyzed from 519 participants (112 MCI) from Project FRONTIER, an ongoing epidemiological study of factors impacting rural aging and health. Depression was assessed with GDS30 and cognition was assessed using the EXIT 25 and RBANS. The sample was randomly split into the training and test sample. Five GDS items were identified in the training sample that were significantly associated with MCI status and were used to create the depressive endophenotype (DepE) of MCI. In the test sample, linear regression was used to examine the impact of depression on neuropsychological tests performance, and logistic regression was conducted to examine the risk of being diagnosed with MCI. Results: In the test sample, DepE was negatively related to RBANS scores of Immediate Memory (B=-2.22, p<0.001), Visuospatial (B=-1.11, p<0.001), Language (B=-1.03, p<0.001), Attention (B=-2.56, p<0.001), and Delayed Memory (B=-1.54, p<0.001), and higher DepE scores were related to poorer executive functioning (EXIT25; B=0.65, p=0.001). DepE scores significantly increased risk for MCI ([OR]= 2.04; 95% CI=l.54-2.69). Conclusions: These findings suggest that a depressed subgroup of MCI exists. Higher DepE scores increased risk for MCI and increased risk for poorer neuropsychological functioning across a range of domains. The DepE may identify those MCI patients who experience depression-related cognitive dysfunction, thereby detecting a selective group that may benefit from depression treatment for prevention of AD.Item REELIN SIGNAL TRANSDUCTION PATHWAY IN APOE3 AND APOE4 TRANSGENIC MICE(2013-04-12) Dugal, MariceliePurpose: The ɛ4 allele of apolipoprotein E (APOE) has been associated with increased risk for the development of late-onset, familial and sporadic Alzheimer's disease (AD). The mechanisms underlying the increase risk of AD development conferred by the ɛ4 allele remains unclear. Reelin and its associated signal transduction pathway are involved in developmental processes, and more specifically, in regulating neuronal migration and cortical lamination in the embryotic brain. Recently, it has been determined that reelin is present in the adult brain throughout the neocortex and hippocampus suggesting a potential role in synaptic plasticity. Furthermore, studies have shown that disruption of the reelin pathway led to decreased memory, impaired long-term potentiation (LTP), and affected dendritic spine morphology. This preliminary study investigated the role of the reelin pathway as a potential mechanism underlying the functional declines associated with APOE polymorphism. Methods: Separate groups of young (7 months) male and female mice expressing human apolipoprotein E4 or E3 in glial cells) were subjected to a series of behavioral tests to measure spontaneous activity, reflexes (walking initiation, alley turn, and negative geotaxis), motor function (wire suspension, bridge walking, coordinated running), and cognitive function (spatial water maze, active avoidance). Brain regions were dissected to determine the levels of reelin and other contributors of its pathway such as dab1, fyn, AMPA and NR2A via western blot analyses. Results: ApoE3 mice took longer latencies to fall in bridge walking, wire suspension, and coordinated running tasks than their ApoE4 counterparts, most notably in males. In the active avoidance task, ApoE3 female mice took fewer trials to reach criterion in session 3 over their ApoE4 counterparts. Western blot analyses will reveal whether reelin may underlie the differences in brain function between genotype and sex. Conclusions: Our results indicate that there may be functional differences between sex as well as ApoE polymorphism. Western blot analyses will reveal whether reelin, dab1, fyn, AMPA and NR2A may underlie the differences in brain function between genotype and sex.Item IN VITRO MODEL FOR ALZHEIMER'S DISEASE DRUG DISCOVERY AND DEVELOPMENT FOCUSING ON OXIDATIVE-NITROSATIVE PATHWAYS(2013-04-12) Wesp, KrystynaPurpose: The Alzheimer's Association estimates that in the absence of disease-modifying treatments the total costs of care for individuals with Alzheimer's disease by all payers will soar from about $170 billion today to more than $1 trillion in 2050. The goal of our project is to develop an in vitro model for testing drugs capable of preventing or slowing the progression of Alzheimer's disease (AD). Previous studies have demonstrated that oxidative-nitrosative stress is an important trigger for Alzheimer's disease and other neurodegenerative disorders. Different nitrosative mechanisms have been proposed for the pathology of this disease, including 3-nitrotyrosination of proteins. Nitric oxide synthase (NOS) is an enzyme that forms nitric oxide. Though important for normal brain function, nitric oxide can react with superoxide formed under oxidative stress conditions to create peroxynitrite, a damaging chemical species that reacts with tyrosine residues to produce aberrant 3-nitrotyrosinated proteins. Recent research has shown certain receptors can modulate NOS activity, but further experiments need to be done to confirm the clinical effectiveness of targeting such receptors with selective drugs as a new therapeutic approach to treating AD and other brain injury states. Our current research is aimed at establishing an in vitro model containing all the necessary elements of the oxidative-nitrosative stress signaling pathway for future drug testing in a cellular model. Methods: Towards this end we have begun to identify relevant pathway elements in a number of cell lines utilizing polymerase chain reaction (PCR) techniques to amplify RNA coding for these elements. This was achieved by culturing cells, extracting purified RNA and reverse transcribing it into DNA and then amplifying the DNA with oligonucleotide primers designed to target specific pathway components (e.g. NOS). Amplified PCR products were confirmed by size determination utilizing agarose gel DNA electrophoresis and DNA sequencing of the correctly-sized bands. Results: Three cell lines, including a neuronal and a glial cell line, have been identified so far that contain a number of the critical elements required for the in vitro model. Conclusions: The identification of a viable in vitro model will allow for further experimentation that can determine the effectiveness of new drugs acting on specific receptor targets to modulate NOS activity and thereby slow the progression of diseases with a nitrosative stress component.Item PATTERNS OF MEDICATION-RELATED PROBLEMS IDENTIFIED DURING A SIX-MONTH MEDICATION MANAGEMENT PROGRAM.(2013-04-12) Liou, AshleyPurpose: Using data from a parent study that evaluated a comprehensive medication management program, this study sought to follow the types of medication-related problems (MRPs) identified at baseline and describe patterns of MRPs over the course of the intervention. The study also examined the most prevalent drug classes contributing to MRPs. Methods: The study examined MRPs at baseline and at 6 months. Drugs were consolidated into a representative therapeutic class. Data on MRPs and drugs had been previously recorded by clinical pharmacists in the study database. Results: 273 MRPs were found at baseline and were reduced to 22 MRPs at 6 months. The most prevalent MRPs at baseline were suboptimal drug (31%), suboptimal dosing (23%), nonadherence (21%), and undertreatment (19%). In comparison, the most prevalent MRP at 6 months was nonadherence (64%), followed by suboptimal drug (14%). At baseline, the most prevalent drugs contributing to overall MRPs were calcium and vitamin D in the category of suboptimal dosing. At 6 months, calcium and vitamin D continued to be the most frequent set of drugs contributing to overall MRPs (32% of the 22 drugs). The second most frequent contributor was antilipidemics, occurring 14% overall. Conclusions: The medication management program was successful in significantly reducing the number and type of MRPS over 6 months. Calcium, vitamin D, and antilipidemics were identified as the most common set of drugs contributing to MRPs. The most common MRP at baseline was suboptimal drug compared to nonadherence at 6 months.Item ERK5/KLF4 SIGNALING IS A SHARED PATHWAY UNDERLYING THE NEUROPROTECTIVE EFFECTS OF H2O2 PRECONDITIONING AND NGF(2013-04-12) Su, ChangPurpose: Oxidative stress has long been implicated in the pathogenesis of various neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. While high levels of oxidative stress is generally associated with neuronal death, a slight rise of reactive oxygen species (ROS) levels can be protective by "preconditioning" cells to develop a resistance against subsequent challenges. However, the mechanisms underlying such a preconditioning (PC)-induced protection are still poorly understood. One clue stems from the observation that the mitogen-activated protein (MAP) kinase ERK5 is recruited both under conditions of H2O2 - induced neuronal preconditioning (PC) as well as following application of the application of the neuroprotectant, Nerve Growth Factor (NGF). This project tests the hypothesis that the ERK5-dependent signaling cascade may function as a convergence point for various protective signals to counteract oxidative stress-induced neuronal death. Methods: We used PC12 cells as our model to study the effect of oxidative stress. Activity of the ERK5 signaling pathway was enhanced by over-expression of active upstream kinease, or blocked by pharmacological inhibitors or RNAi. Cell viability was determined by Calcein Assay. Results: Over-expression of a constitutively active form of MEK5, the upstream activator of ERK5, partially rescued PC12 cells from H2O2-caused death, while inhibition of ERK5 by pharmacological inhibitors or RNAi abolished NGF or PC-induced protection.Furthermore, both NGF and PC increased the expression of the transcription factor, KLF4, which can initiate an anti-apoptotic response in various cell types. Induction of KLF4 by NGF or PC in PC12 cells is blocked by siERK5, suggesting that ERK5 is required in this process. Finally, siKLF4 can also attenuate NGF- or PC-induced neuroprotection. Conclusions: Taken together, our data suggest that ERK5/KLF4 cascade is a common signaling pathway shared by multiple mechanisms to protect neurons from oxidative stress-induced cell death. Since oxidative stress is thought to be a major player in many aging-associated diseases, KLF4 may serve as a therapeutic target, that when activated, counteracts oxidative stress under such conditions.Item DOES THE MORTALITY RISK INDEX PREDICT 6 MONTH MORTALITY IN RESIDENTS LIVING IN A DEMENTIA SPECIAL CARE CENTER?(2013-04-12) Volberding, KristaPurpose: Predicting survival in patients with advanced dementia plays a vital role in the care planning process for these patients. A special care dementia center that is rooted in the philosophy of "humane care" and recognizing dementia as a terminal illness may actually contribute towards increasing life expectancy. This study was designed to test whether the residents of a special dementia care center have a longer life expectancy compared to usual nursing home residents based on a predictive formula developed by Mitchell et al entitled the Mortality Risk Index. If true, this would support the provision of "humane" supportive and non-aggressive or invasive care for patients with advanced dementia which would enable them a longer life expectancy with a focus on comfort care measures. Methods: This was a retrospective chart review of 236 residents who had resided at the JLWest Dementia Special Care Center and had expired over the past 10 years. The life expectancy was predicted utilizing the Mortality Risk Index Score (MRI) calculated from various items from the Minimum Data Set (MDS). Data elements (transcribed from original medical records) were collected from the MDS administered at approximately 6-month intervals, up to 3 years from the date of death. All data was entered into an SPSS Program. Results: The mean Mortality Risk Index for patients at the JLWest Center was 4.89. This value corresponds with a mean estimate of 0.292, indicating that 29.2% (a total of 69) residents would be expected to die within six months of the assessment. In reality 87 residents died within six months of the MDS, representing 36.9% of the resident population. Conclusions: The Mortality Risk Index Score under predicted the amount of deaths in the population at the JLWest dementia special care center. The MRI alone is not a sufficient predictor of death in these dementia patients, indicating there are other aspects related to the disease or care of the illness that must be factored into predicting death.Item THE LINK BETWEEN POTASSIUM AND MILD COGNITIVE IMPAIRMENT IN MEXICAN AMERICANS(2013-04-12) Rohlfing, GeoffreyPurpose: Assessing electrolytes is a cornerstone of the geriatric primary care visit. Research suggests that potassium may be linked to Alzheimer's Disease (AD) and cognitive functioning; however, this link has not been investigated in Mild Cognitive Impairment (MCI) a prodromal category to AD. The purpose of this study was to examine the link between serum electrolytes and diagnosis of MCI. Methods: Data on a total of 473 participants (278 non-Hispanic white and 195 Mexican American) from Project FRONTIER were analyzed. Each participant underwent an interview (i.e. medical history, medications, health behaviors), neuropsychological testing, blood draw, and medical examination, and informant interviews. Weekly consensus reviews were conducted reviewing the data and diagnoses of MCI assigned according to published criteria by clinical experts. Participants classified as cognitively normal control (NC) performed within normal limits on all psychometric assessment. Serum electrolytes included in this study were sodium, chloride, carbon dioxide, and potassium. Age and Education were entered into the models as co-variates. Logistic regression was used to assess the risk of MCI diagnosis. Analysis was split by ethnicity. Results: For Mexican Americans, the results of this study indicated that serum potassium levels significantly increased the risk of diagnosis of MCI (odds ratio [OR]= 3.2, 95% CI=1.2 to 8.2). No other electrolytes were found to significantly increase risk for MCI. For non-Hispanic whites, age and education alone increased risk for MCI diagnosis. No electrolytes were found to increase risk for MCI diagnosis for this ethnic group. Conclusions: Our findings suggested a link between serum potassium levels and a diagnosis of MCI for Mexican Americans. The results of this study support previous research which has suggested that the risk factors for MCI may vary by ethnicity. Additional work is needed to cross-validate these findings and examine their utility in designing treatment protocols.Item BIOPHYSICAL STUDIES OF MEMBRANE TOPOLOGY OF HUMAN PRESENELIN-1(2013-04-12) Midde, KrishnaPurpose: Alzheimer's disease (AD) afflicts ~5 million Americans. Amyloid (Abeta) plaques accumulate in the brain of patients during AD leading to neurodegeneration. Presenelin-1 (PS1), a trans-membrane protein, acts as the catalytic subunit of gamma-secretase enzyme to cleave amyloid precursor protein (APP) and produce Abeta peptides. Mutations in the PS1 gene have been linked to the pathogenesis of early onset of familial AD (FAD). Recently, it has been reported that PS1 also acts as Ca2+ leak channel on the membrane of endoplasmic reticulum (ER). Currently there are divergent views in the literature on the subunit association and the correct membrane topology of PS1 protein. Considering the several physiological functions and the critical role of PS1 in the pathogenesis of AD, we sought to investigate the membrane topology of PS1 protein through various biophysical studies. Methods: Neuroblastoma (SK-N-SH) cells expressing PS1 protein with NH2-terminal tagged yellow fluorescent protein (YFP-PS1) and COOH-terminal tagged cyano fluorescent protein (PS1-CFP) were used as a model in our studies. Membrane localization and subunit association of PS1 were determined by biophysical assays. Expression and colocalization of YFP-PS1 and PS1-CFP proteins were assessed by confocal imaging. Localization of the N-terminal and C-terminal of PS1 was assessed by fluorescence correlation spectroscopy (FCS). Finally subunit aggregation of PS1 protein was determined by Forster Resonance Energy Transfer (FRET) assay. Results: When cells expressing both PS1-CFP and YFP-PS1 proteins were independently excited and imaged, their respective fluorescence overlapped suggesting co-expression and co-localization of the PS1 subunits. The diffusion coefficient of the PS1 protein in the transmembrane was the same (~0.15µm2/s) when FCS was measured in cells with and without 80% glycerol in 1XPBS indicating that the NH2 and COOH termini are facing the cytosolic side of the plasma-membrane. The quench in the fluorescence lifetime of CFP (donor) in the presence of YFP (acceptor) in FRET assay demonstrates the protein-protein interaction between PS1-CFP and YFP-PS1. Conclusions: Both YFP-PS1 and PS1-CFP chimeric proteins are expressed on the plasma membrane and intracellular membranes with NH2-terminal and COOH-terminal oriented towards the cytosolic side of the membrane. PS1 is a dynamic transmembrane protein which associates as dimer or multimer to form ERCa2+ channel and thus regulates intracellular calcium signaling.