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Vasilevko V, Head E. · Institute for Brain Aging & Dementia, University of California, Irvine, CA 92697-4540, USA. · CNS Neurol Disord Drug Targets. · Pubmed #19355931 No free full text.

Abstract: Alzheimer disease (AD) is the most common form of dementia in the elderly and the number of individuals developing the disease is rapidly rising. Interventions focused on reducing beta-amyloid (Abeta), a component of senile plaques within the AD brain offer a promising approach to prevent or slow disease progression. In this review, we describe the immune system and cognitive and neurobiological features of a natural model of human brain aging, the beagle. The immune system of dogs shares many features of the human immune system, including developmental and aging characteristics. Further, dogs naturally accumulate human sequence Abeta as they age, which coincides with declines in learning and memory. A longitudinal study (approximately 2 years) of the response of aged beagles to vaccination with fibrillar Abeta1-42 indicated that despite significant clearance of Abeta, there were limited benefits in cognitive function. However, there was evidence for maintenance of executive function over time. These results are strikingly similar to reports of human clinical immunotherapy trials. We propose that the canine model complements existing animal models and will be helpful in developing new vaccine approaches to slowing or preventing Abeta pathology that can be translated to human clinical trials.

Rohn TT, Head E. · Department of Biology, Science/Nursing Building, Room 228, Boise State University, Boise, Idaho, 83725, USA. · Rev Neurosci. · Pubmed #19317178 No free full text.

Abstract: It has been almost 15 years since the first report of apoptosis as a major mechanism of cell death associated with Alzheimer's disease (AD). Presently, whether neurons die through apoptosis or some other pathway is still a hotly debated issue. However, mounting evidence suggests a role for the activation of caspases and cleavage of critical cellular proteins during the progression of AD. The activation of apoptotic pathways may represent a protracted battle due to the presence of various anti-apoptotic molecules such as Bcl-2 whereby neurons do not immediately execute the apoptotic program but caspase activation occurs discretely at some low level. During this time, caspase cleavage of the amyloid precursor protein (APP), the adaptor protein GGA3 involved with beta-amyloid production, and tau may promote the formation of beta-amyloid (A beta) and neurofibrillary tangles (NFTs). Thus, not only may activation of caspases represent a terminal event associated with AD (i.e. cell death), but also a proximal event that promotes the pathology underlying this disease. Therefore, therapeutics aimed at preventing the activation and execution of apoptosis may provide an effective means of treating AD.

Cotman CW, Head E. · Institute for Brain Aging & Dementia, Department of Neurology, University of California, Irvine, CA 92697-4540, USA. · J Alzheimers Dis. · Pubmed #19096165 No free full text.

Abstract: Aged dogs (beagles) develop losses in executive function, learning and memory. The severity of decline in these cognitive domains represents a spectrum that captures normal aging, mild cognitive impairment and early/mild Alzheimer's disease (AD) in humans. In parallel, dogs naturally accumulate several types of neuropathology (although not all) consistent with human brain aging and AD including cortical atrophy, neuron loss, loss of neurogenesis, amyloid-beta (Abeta) plaques, cerebral amyloid angiopathy and oxidative damage. Many of these neuropathological features correlate with the extent of cognitive decline in a brain region-dependent manner. Dogs are ideally suited for longitudinal studies, and we provide a summary of the beneficial effects of an antioxidant diet, behavioral enrichment, and Abeta immunotherapy. In addition, combinatorial treatment approaches can be a powerful strategy for improving brain function through enhancement of multiple molecular pathways.

Head E. · Department of Neurology, Institute for Brain Aging & Dementia, University of California, 1259 Gillespie Neuroscience Research Facility, Irvine, CA 92697-4540, USA. · Neurochem Res. · Pubmed #18683046 No free full text.

Abstract: Oxidative damage in the brain may lead to cognitive impairments in aged humans. Further, in age-associated neurodegenerative disease, oxidative damage may be exacerbated and associated with additional neuropathology. Epidemiological studies in humans show both positive and negative effects of the use of antioxidant supplements on healthy cognitive aging and on the risk of developing Alzheimer disease (AD). This contrasts with consistent behavioral improvements in aged rodent models. In a higher mammalian model system that naturally accumulates human-type pathology and cognitive decline (aged dogs), an antioxidant enriched diet leads to rapid learning improvements, memory improvements after prolonged treatment and cognitive maintenance. Cognitive benefits can be further enhanced by the addition of behavioral enrichment. In the brains of aged treated dogs, oxidative damage is reduced and there is some evidence of reduced AD-like neuropathology. In combination, antioxidants may be beneficial for promoting healthy brain aging and reducing the risk of neurodegenerative disease.

Head E, Lott IT, Patterson D, Doran E, Haier RJ. · Institute for Brain Aging & Dementia, University of California, Irvine, CA 92697-4540, USA. · J Alzheimers Dis. · Pubmed #17361036 No free full text.

Abstract: Adults with Down syndrome (DS) develop Alzheimer disease (AD) pathology progressively with age but clinical signs of dementia are delayed by at least 10 years after the first signs of disease. Some individuals with DS do not develop dementia despite extensive AD neuropathology. Given the discordance between clinical decline and AD neuropathology, compensatory events may be of particular relevance for this group. Imaging studies using PET suggest compensatory increases in metabolic rate in vulnerable brain regions in DS prior to the development of dementia. Neurobiological studies of similarly aged DS autopsy cases provide further evidence of activation of plasticity mechanisms. Genes that are overexpressed in DS (APP, DSCAM, MNB/DYRK1A, and RCAN1) produce proteins critical for neuron and synapse growth, development and maintenance. We present the hypothesis that these genes may lead to developmental cognitive deficits but paradoxically with aging, may participate in molecular cascades supporting neuronal compensation. Enhancing or supporting compensatory mechanisms in aging individuals with DS may be beneficial as suggested by intervention studies in animal models. In combination, adults with DS may be a unique group of individuals well-suited for studies involving the manipulation or upregulation of compensatory responses as an approach to promote successful brain aging in the general population.

Lott IT, Head E, Doran E, Busciglio J. · Department of Pediatrics and Neurology, Alzheimer Disease Research Center, University of California, Irvine, School of Medicine, Irvine, California 92868, USA. · Curr Alzheimer Res. · Pubmed #17168651 No free full text.

Abstract: Down syndrome (DS) provides a model for studying important aspects of Alzheimer disease (AD). Chromosome 21 contains several genes that have been implicated in neurodegenerative mechanisms. These include Cu/Zn superoxide dismutase (SOD-1), Ets-2 transcription factors, Down Syndrome Critical Region 1 (DSCR1) stress-inducible factor, and the amyloid precursor protein (APP). The accumulation of Abeta plaques is progressive across the lifespan in DS. Overexpression of APP in the obligate region for DS is associated with abundant Abeta plaques and tangles consistent with Braak stage V-VI. Intraneuronal Abeta in DS appears to trigger a pathological cascade leading to oxidative stress and a neurodegeneration typical of AD. There are suggestions that an increase in subcellular processing of APP and factors related to membrane APP cleavage favor the secretion of Abeta with age in DS. A misbalance between SOD-1 and glutathione perioxidase activity in DS has been linked to free radical generation. Ets-2 and DSCR1 overexpression in DS has been linked to cell degeneration. Age-related accumulation of somatic DNA mutations in both DS and AD contribute to oxidative stress that exacerbates the imbalance in gene expression. This leads to enhanced Abeta deposition and further neuronal vulnerability. The consequence of these factors and their temporal relationships is likely to be the subject of future research. Since the pathological processes leading to AD are seen across the lifespan in DS, an opportunity is afforded for early pharmacological intervention in the disorder.

Lott IT, Head E. · Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697, USA. · Neurobiol Aging. · Pubmed #15639317 No free full text.

Abstract: There is evidence to suggest that certain shared features exist in the pathogenesis of vascular disease and Alzheimer disease (AD) in the general population. In Down syndrome (DS) all adults over the age of 40 years develop sufficient neuropathology for a diagnosis of AD. However, vascular disease is not as common in DS as it is in the general population, particularly with respect to the development of atheromas. We discuss biological mechanisms and risk factors that may be common to both diseases including cholesterol metabolism, inflammation, plasminogen activator inhibitor and apolipoprotein E (Apo E). The study of individuals with DS may help to identify common pathogenic links as well as a disassociation between vascular disease and AD.

Head E, Lott IT. · Institute for Brain Aging and Dementia, Department of Neurology, University of California, Irvine, California, USA. · Curr Opin Neurol. · Pubmed #15021233 No free full text.

Abstract: PURPOSE OF REVIEW: Exciting new therapeutic approaches to the treatment or prevention of Alzheimer's disease involve preventing, slowing or reversing beta-amyloid accumulation. These interventions may also apply to the treatment of Alzheimer's disease in Down syndrome. The purpose of the current review is therefore to summarize developments and advances in our understanding of beta-amyloid pathogenesis in Down syndrome over the past year. RECENT FINDINGS: A shift in research to a focus on early events in beta-amyloid pathogenesis in Down syndrome has led to several novel observations. Several authors have reported the accumulation of both soluble and intracellular beta-amyloid before extracellular beta-amyloid (senile plaques) in Down syndrome. Increases in beta-amyloid levels in Down syndrome may reflect the increased expression and protein levels of beta-site amyloid precursor protein cleavage enzyme 2 on chromosome 21. The impact of the accumulation of beta-amyloid may have differential effects on development and aging in Down syndrome. SUMMARY: The past year has seen significant advances in our understanding of beta-amyloid pathogenesis and the functional consequences of beta-amyloid accumulation in Down syndrome. However, there are still large gaps in our knowledge of the pathways involved in beta-amyloid degradation and clearance. It will be critical to conduct clinical trials to test therapeutic strategies that may reduce beta-amyloid in Down syndrome directly to determine the optimal age and dose for specific interventions. Given the differences in the mechanism of beta-amyloid accumulation in Down syndrome, careful consideration needs to be given to potential clinical trials to treat this disorder.

Lott IT, Head E. · Department of Pediatrics, University of California, Irvine, Orange, CA 92868, USA. · Ment Retard Dev Disabil Res Rev. · Pubmed #11553933 No free full text.

Abstract: A subset of aged individuals with Down syndrome (DS) exhibits the clinical features of Alzheimer's disease (AD) but our ability to detect dementia in this population is hampered by developmental differences as well as the sensitivity of existing test tools. Despite the apparent clinical heterogeneity in aged individuals with DS, age-associated neuropathology is a consistent feature. This is due to the fact that trisomy 21 leads to a dose-dependent increase in the production of the amyloid precursor protein and subsequently the production of the amyloidogenic fragments leading to early and predominant senile plaque formation. A review of the existing literature indicates that oxidative damage and neuroinflammation may interact to accelerate the disease process particularly in individuals with DS over the age of 40 years. By combining clinical information with measures of brain-region specific neuropathology we can "work backwards" and identify the earliest and most sensitive clinical change that may signal the onset of AD. For the past 50 years, investigators in the fields of mental retardation, developmental disabilities, and aging have been interested in the curious link between AD and DS. The morphologic and biochemical origins of AD are seen in the early years of the lifespan for individuals with DS. Study of the process by which AD evolves in DS affords an opportunity to understand an important link between development and aging. This review will focus on advances in the molecular and clinical basis of this association.

Haier RJ, Alkire MT, White NS, Uncapher MR, Head E, Lott IT, Cotman CW. · Department of Pediatrics, University of California, Irvine 92697-5000, USA. · Neurology. · Pubmed #14694028 No free full text.

Abstract: BACKGROUND: Adults with Down syndrome (DS) are at increased risk for dementia and provide an opportunity to identify patterns of brain activity that may precede dementia. Studies of early Alzheimer's disease (AD) and risk of AD show decreased function in posterior cingulate and temporal cortex as initial indicators of the disease process, but whether the origin and sequence of predementia brain changes are the same in DS is unknown. METHODS: The regional cerebral glucose metabolic rates (GMR) among middle-aged nondemented people with DS (n = 17), people with moderate AD (n = 10), and age-matched control subjects (n = 24) were compared using PET during a cognitive task. RESULTS: Statistical parametric mapping conjunction analyses showed that 1) both DS and AD groups had lower GMR than their respective controls primarily in posterior cingulate and 2) compared with respective controls, the subjects with DS had higher GMR in the same areas of inferior temporal/entorhinal cortex where the AD subjects had lower GMR. The same results were replicated after 1 year of follow-up. CONCLUSIONS: As the DS subjects were not clinically demented, inferior temporal/entorhinal cortex hypermetabolism may reflect a compensatory response early in disease progression. Compensatory responses may subsequently fail, leading to neurodegenerative processes that the authors anticipate will be detectable in vivo as future GMR decreases in inferior temporal/entorhinal cortex are accompanied by clinical signs of dementia.

Berlau DJ, Corrada MM, Head E, Kawas CH. · Institute of Brain Aging and Dementia, University of California Irvine, Irvine, CA 92697-1400, USA. · Neurology. · Pubmed #19255410 No free full text.

Abstract: BACKGROUND: Many studies have examined the role of APOE genotype in the development of dementia, specifically Alzheimer disease (AD). The APOE epsilon4 allele (APOE4) is a risk factor for both clinical and neuropathologic AD whereas the APOE epsilon2 allele (APOE2) seems to be protective. This would predict, even with advanced age, that APOE2 carriers would be less likely to have dementia and less likely to meet pathologic criteria for AD. METHODS: The first 85 genotyped participants from The 90+ Study to come to autopsy were included. All-cause dementia (using DSM-IV criteria) and AD (using National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria) diagnoses were made by consensus conference using all available information including neuropsychological testing, neurologic examination, and medical records. Neuropathologic examination included Braak and Braak staging for plaques and tangles and diagnosis of neuropathologic AD using National Institute on Aging-Reagan criteria. RESULTS: Across all genotypes, 58.5% of subjects were diagnosed with clinical dementia (81% of dementia was AD) and 50.0% met neuropathologic criteria for AD. Compared to those with an APOE epsilon3/epsilon3 genotype (APOE3/3), APOE4 carriers were more likely to be diagnosed with dementia (odds ratio [OR] = 12.2, 95% confidence interval [CI] = 1.5-102.0), whereas APOE2 carriers were not (OR = 0.3, 95% CI = 0.1-1.3). Surprisingly, both APOE4 (OR = 4.6, 95% CI = 1.3-16.5) and APOE2 (OR = 7.8, 95% CI = 1.5-40.2) carriers were more likely to meet neuropathologic criteria for AD than those with APOE3/3 genotype. CONCLUSIONS: In the oldest old, the presence of the APOE epsilon2 allele (APOE2) was associated with a somewhat reduced risk of dementia, but paradoxically was associated with increased Alzheimer disease (AD) neuropathology. Therefore, oldest old APOE2 carriers may have some mechanism that contributes to the maintenance of cognition independently of the formation of AD pathology.

Movsesyan N, Ghochikyan A, Mkrtichyan M, Petrushina I, Davtyan H, Olkhanud PB, Head E, Biragyn A, Cribbs DH, Agadjanyan MG. · Department of Molecular Immunology, Institute for Molecular Medicine, Huntington Beach, California, United States of America. · PLoS One. · Pubmed #18461171 links to  free full text

Abstract: BACKGROUND: The development of a safe and effective AD vaccine requires a delicate balance between providing an adequate anti-Abeta antibody response sufficient to provide therapeutic benefit, while eliminating an adverse T cell-mediated proinflammatory autoimmune response. To achieve this goal we have designed a prototype chemokine-based DNA epitope vaccine expressing a fusion protein that consists of 3 copies of the self-B cell epitope of Abeta(42) (Abeta(1-11)) , a non-self T helper cell epitope (PADRE), and macrophage-derived chemokine (MDC/CCL22) as a molecular adjuvant to promote a strong anti-inflammatory Th2 phenotype. METHODS AND FINDINGS: We generated pMDC-3Abeta(1-11)-PADRE construct and immunized 3xTg-AD mouse model starting at age of 3-4 months old. We demonstrated that prophylactic immunizations with the DNA epitope vaccine generated a robust Th2 immune response that induced high titers of anti-Abeta antibody, which in turn inhibited accumulation of Abeta pathology in the brains of older mice. Importantly, vaccination reduced glial activation and prevented the development of behavioral deficits in aged animals without increasing the incidence of microhemorrhages. CONCLUSIONS: Data from this transitional pre-clinical study suggest that our DNA epitope vaccine could be used as a safe and effective strategy for AD therapy. Future safety and immunology studies in large animals with the goal to achieve effective humoral immunity without adverse effects should help to translate this study to human clinical trials.

Rohn TT, Vyas V, Hernandez-Estrada T, Nichol KE, Christie LA, Head E. · Department of Biology, Boise State University, Boise, Idaho 83725, USA. · J Neurosci. · Pubmed #18354008 links to  free full text

Abstract: Alzheimer's disease (AD) is characterized by the accumulation of plaques containing beta-amyloid (Abeta) and neurofibrillary tangles (NFTs) consisting of modified tau. Although Abeta deposition is thought to precede the formation of NFTs in AD, the molecular steps connecting these two pathologies is not known. Previous studies have suggested that caspase activation plays an important role in promoting the pathology associated with AD. To further understand the contribution of caspases in disease progression, a triple transgenic Alzheimer's mouse model overexpressing the anti-apoptotic protein Bcl-2 was generated. Here we show that overexpression of Bcl-2 limited caspase-9 activation and reduced the caspase cleavage of tau. Moreover, overexpression of Bcl-2 attenuated the processing of APP (amyloid precursor protein) and tau and reduced the number of NFTs and extracellular deposits of Abeta associated with these animals. In addition, overexpression of Bcl-2 in 3xTg-AD mice improved place recognition memory. These findings suggest that the activation of apoptotic pathways may be an early event in AD and contributes to the pathological processes that promote the disease mechanisms underlying AD.

Petrushina I, Ghochikyan A, Mktrichyan M, Mamikonyan G, Movsesyan N, Davtyan H, Patel A, Head E, Cribbs DH, Agadjanyan MG. · The Institute for Brain Aging and Dementia, University of California, Irvine, Irvine, California 92697-4540, USA. · J Neurosci. · Pubmed #18003852 links to  free full text

Abstract: Active vaccination of elderly Alzheimer's disease (AD) patients with fibrillar amyloid-beta peptide (Abeta42), even in the presence of a potent Th1 adjuvant, induced generally low titers of antibodies in a small fraction (approximately 20% responders) of those that received the AN-1792 vaccine. To improve the immunogenicity and reduce the likelihood of inducing adverse autoreactive T-cells specific for Abeta42, we previously tested in wild-type mice an alternative approach for active immunization: an epitope vaccine that selectively initiate B cell responses toward an immunogenic self-epitope of Abeta in the absence of anti-Abeta T cell responses. Here, we describe a second generation epitope vaccine composed of two copies of Abeta(1-11) fused with the promiscuous nonself T cell epitope, PADRE (pan human leukocyte antigen DR-binding peptide) that completely eliminates the autoreactive T cell responses and induces humoral immune responses in amyloid precursor protein transgenic 2576 mice with pre-existing AD-like pathology. Based on the titers of anti-Abeta(1-11) antibody experimental mice were divided into low, moderate and high responders, and for the first time we report a positive correlation between the concentration of anti-Abeta(1-11) antibody and a reduction of insoluble, cerebral Abeta plaques. The reduction of insoluble Abeta deposition was not associated with adverse events, such as CNS T cell or macrophage infiltration or microhemorrhages. Surprisingly, vaccination did not alter the levels of soluble Abeta. Alternatively, early protective immunization before substantial neuropathology, neuronal loss and cognitive deficits have become firmly established may be more beneficial and safer for potential patients, especially if they can be identified in a preclinical stage by the development of antecedent biomarkers of AD.

Kayed R, Head E, Sarsoza F, Saing T, Cotman CW, Necula M, Margol L, Wu J, Breydo L, Thompson JL, Rasool S, Gurlo T, Butler P, Glabe CG. · Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA. · Mol Neurodegener. · Pubmed #17897471 links to  free full text

Abstract: ABSTRACT: BACKGROUND: Amyloid-related degenerative diseases are associated with the accumulation of misfolded proteins as amyloid fibrils in tissue. In Alzheimer disease (AD), amyloid accumulates in several distinct types of insoluble plaque deposits, intracellular Abeta and as soluble oligomers and the relationships between these deposits and their pathological significance remains unclear. Conformation dependent antibodies have been reported that specifically recognize distinct assembly states of amyloids, including prefibrillar oligomers and fibrils. RESULTS: We immunized rabbits with a morphologically homogeneous population of Abeta42 fibrils. The resulting immune serum (OC) specifically recognizes fibrils, but not random coil monomer or prefibrillar oligomers, indicating fibrils display a distinct conformation dependent epitope that is absent in prefibrillar oligomers. The fibril epitope is also displayed by fibrils of other types of amyloids, indicating that the epitope is a generic feature of the polypeptide backbone. The fibril specific antibody also recognizes 100,000 x G soluble fibrillar oligomers ranging in size from dimer to greater than 250 kDa on western blots. The fibrillar oligomers recognized by OC are immunologically distinct from prefibrillar oligomers recognized by A11, even though their sizes overlap broadly, indicating that size is not a reliable indicator of oligomer conformation. The immune response to prefibrillar oligomers and fibrils is not sequence specific and antisera of the same specificity are produced in response to immunization with islet amyloid polypeptide prefibrillar oligomer mimics and fibrils. The fibril specific antibodies stain all types of amyloid deposits in human AD brain. Diffuse amyloid deposits stain intensely with anti-fibril antibody although they are thioflavin S negative, suggesting that they are indeed fibrillar in conformation. OC also stains islet amyloid deposits in transgenic mouse models of type II diabetes, demonstrating its generic specificity for amyloid fibrils. CONCLUSION: Since the fibril specific antibodies are conformation dependent, sequence-independent, and recognize epitopes that are distinct from those present in prefibrillar oligomers, they may have broad utility for detecting and characterizing the accumulation of amyloid fibrils and fibrillar type oligomers in degenerative diseases.

Berlau DJ, Kahle-Wrobleski K, Head E, Goodus M, Kim R, Kawas C. · Institute of Brain Aging and Dementia, University of California, Irvine, 1515 Hewitt Hall, Irvine, CA 92697-1400, USA. · Arch Neurol. · Pubmed #17698712 links to  free full text

Abstract: BACKGROUND: The apolipoprotein E (APOE) epsilon2 allele has been suggested as having a protective effect and delaying the age at onset of Alzheimer disease. OBJECTIVE: To describe a dissociation between neuropathologic findings with normal cognition in a woman with severe Alzheimer disease with the APOE epsilon2/epsilon2 genotype. DESIGN: Case report from a community-based prospective study of persons 90 years or older (The 90+ Study). PARTICIPANT: A 92-year-old woman without dementia with the APOE epsilon2/epsilon2 genotype who lived independently without significant cognitive or functional loss and was a participant in The 90+ Study. She died in December 2004, and postmortem examination of her brain was performed. INTERVENTION: Neurologic examination and a battery of neuropsychological tests were performed 6 months and 1 month before death. Neuropathologic examination included Braak and Braak staging for senile plaques and neurofibrillary tangles. RESULTS: Neuropathologic examination of the brain revealed advanced senile plaque and neurofibrillary tangle disease consistent with a high likelihood of Alzheimer disease. At clinical evaluation, the participant demonstrated no dementia and only mild cognitive deficits. CONCLUSIONS: The APOE genotype may have contributed to maintenance of cognition despite advanced neuropathologic findings of Alzheimer disease. This case suggests that the APOE epsilon2 isoform may have a protective effect against cognitive decline in Alzheimer disease that may be independent from senile plaques and neurofibrillary tangles.

Opii WO, Joshi G, Head E, Milgram NW, Muggenburg BA, Klein JB, Pierce WM, Cotman CW, Butterfield DA. · Department of Chemistry, Center of Membrane Sciences, and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40506-0055, United States. · Neurobiol Aging. · Pubmed #17055614 links to  free full text

Abstract: Aging and age-related disorders such as Alzheimer's disease (AD) are usually accompanied by oxidative stress as one of the main mechanisms contributing to neurodegeneration and cognitive decline. Aging canines develop cognitive dysfunction and neuropathology similar to those seen in humans, and the use of antioxidants results in reductions in oxidative damage and in improvement in cognitive function in this canine model of human aging. In the present study, the effect of a long-term treatment with an antioxidant-fortified diet and a program of behavioral enrichment on oxidative damage was studied in aged canines. To identify the neurobiological mechanisms underlying these treatment effects, the parietal cortex from 23 beagle dogs (8.1-12.4 years) were treated for 2.8 years in one of four treatment groups: i.e., control food-control behavioral enrichment (CC); control food-behavioral enrichment (CE); antioxidant food-control behavioral enrichment (CA); enriched environment-antioxidant-fortified food (EA). We analyzed the levels of the oxidative stress biomarkers, i.e., protein carbonyls, 3-nitrotyrosine (3-NT), and the lipid peroxidation product, 4-hydroxynonenal (HNE), and observed a decrease in their levels on all treatments when compared to control, with the most significant effects found in the combined treatment, EA. Since EA treatment was most effective, we also carried out a comparative proteomics study to identify specific brain proteins that were differentially expressed and used a parallel redox proteomics approach to identify specific brain proteins that were less oxidized following EA. The specific protein carbonyl levels of glutamate dehydrogenase [NAD (P)], glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alpha-enolase, neurofilament triplet L protein, glutathione-S-transferase (GST) and fascin actin bundling protein were significantly reduced in brain of EA-treated dogs compared to control. We also observed significant increases in expression of Cu/Zn superoxide dismutase, fructose-bisphosphate aldolase C, creatine kinase, glutamate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase. The increased expression of these proteins and in particular Cu/Zn SOD correlated with improved cognitive function. In addition, there was a significant increase in the enzymatic activities of glutathione-S-transferase (GST) and total superoxide dismutase (SOD), and significant increase in the protein levels of heme oxygenase (HO-1) in EA treated dogs compared to control. These findings suggest that the combined treatment reduces the levels of oxidative damage and improves the antioxidant reserve systems in the aging canine brain, and may contribute to improvements in learning and memory. These observations provide insights into a possible neurobiological mechanism underlying the effects of the combined treatment. These results support the combination treatments as a possible therapeutic approach that could be translated to the aging human population who are at risk for age-related neurodegenerative disorders, including Alzheimer's disease.

Mouser PE, Head E, Ha KH, Rohn TT. · Department of Biology, Boise State University, Boise, ID 83725, USA. · Am J Pathol. · Pubmed #16507909 links to  free full text

Abstract: Recent studies demonstrate roles for activation of caspases and cleavage of cellular proteins within neurons of the Alzheimer's disease (AD) brain. To determine whether a similar role for caspases also occurs within glial cells in AD, we designed a site-directed caspase-cleavage antibody specific to glial fibrillary acidic protein (GFAP), a cytoskeleton protein specifically expressed in astrocytes. In vitro characterization of this antibody using both a cell-free system and a cell model system of apoptosis demonstrated that the antibody (termed GFAP caspase-cleavage product antibody or GFAP-CCP Ab) immunolabeled the predicted caspase-cleavage fragment, but not full-length GFAP, by Western blot analysis. To determine whether caspases cleave GFAP in vivo, tissue sections from control and AD brains were examined by immunohistochemistry using the GFAP-CCP Ab. Two prominent features of staining were evident: immunolabeling of degenerating astrocytes in proximity to blood vessels and staining within plaque-rich regions of the AD brain. Furthermore, co-localization of the GFAP-CCP Ab and an antibody specific to active caspase-3 was demonstrated within damaged astrocytes of the AD brain. These data suggest that the activation of caspases and cleavage of cellular proteins such as GFAP may contribute to astrocyte injury and damage in the AD brain.

Head E, Barrett EG, Murphy MP, Das P, Nistor M, Sarsoza F, Glabe CC, Kayed R, Milton S, Vasilevko V, Milgram NW, Agadjanyan MG, Cribbs DH, Cotman CW. · Institute for Brain Aging & Dementia, Department of Neurology, University of California, 1259 Gillespie Neuroscience Research Facility, Irvine, CA 92697-4540, USA. · Vaccine. · Pubmed #16460841 No free full text.

Abstract: We describe a study testing fibrillar beta-amyloid(1-42) (Abeta42) vaccination in dogs. Three young beagles (4.6 years) were immunized twice with Abeta42 and a Th1 adjuvant (TiterMax Gold). Animals generated primarily IgG2 and IgM antibody responses, which were specific for the Abeta(11-30) region of Abeta(1-42). Next, 3 aged beagles (8.9-13.8 years) were immunized 4 times with Abeta(42) and a Th2 adjuvant (Alum). We observed an acute increase in IgG2, a slower increase in IgG1 and Abeta antibodies of broader specificity (Abeta(1-15>) Abeta(11-30>) Abeta(6-20)). A nonsignificant increase in CSF Abeta(1-40) and decrease in Abeta(1-40/1-42) in cortex was detected. Canines may be a useful system for testing an Abeta vaccine.

Chubb C, Inagaki Y, Sheu P, Cummings B, Wasserman A, Head E, Cotman C. · Department of Cognitive Sciences, and Institute for Mathematical Behavioral Sciences, University of California, Irvine, USA. · Neurobiol Aging. · Pubmed #16271803 No free full text.

Abstract: We describe a computer application, "BioVision", that can be trained to quickly and effectively classify and quantify user definable histological objects (e.g., senile plaques, neurofibrillary tangles) within single or double-labeled immunocytochemically stained sections. For a given image population, BioVision is interactively trained (in Independent User Mode) by an investigator to perform the desired classifications. This training yields a statistical model of the different types of objects occurring in the target image population. The resulting model can then be used (in Automated User Mode) to classify all objects in any image or images from the target population. BioVision simplifies the quantification of complex visual objects and improves inter-rater reliability. The program accomplishes classification in two major stages: pixel classification and blob classification. In pixel classification, each pixel is assigned to one of some number of substance classes, based on its chromatic properties and local context, reflecting basic histological distinctions of interest. In the blob classification phase, the image's pixels are first partitioned into "blobs": maximal connected sets of pixels assigned to the same substance class. Then, based on its size, shape, textural and contextual properties, each blob is assigned to a histological object class. A Bayesian classifier is used in each of the pixel and blob classification stages. We report several tests of BioVision. First, we applied BioVision to classify senile plaques and neurofibrillary tangles in several test cases of Alzheimer's brain immunostained for beta-amyloid and PHF-tau and compared the results to those produced by experienced investigators. BioVision was trained to classify Plaque-type blobs as either plaques or plaque-type nonentities, and tangle-type blobs as either tangles or tangle-type nonentities. BioVision classified the objects with an accuracy comparable to the trained investigator. Next, we applied BioVision to the task of counting all the tangles in hippocampal images from 22 Alzheimer's disease (AD) cases selected to span a broad range of dementia levels from the tissue repository of UC Irvine's Center for the study of Brain Aging and Dementia. The tangle counts produced by BioVision proved to be significantly better predictors of the cases' adjusted MMSE scores than any of tangle load, age at death, post mortem interval or the interval between the last MMSE score and death.

Nelson L, Johnson JK, Freedman M, Lott I, Groot J, Chang M, Milgram NW, Head E. · Department of Neurology, University of California, Irvine, Medical Center, 101 City Drive, Route 81, Building 53, Room 225, Orange, CA 92868, USA. · Prog Neuropsychopharmacol Biol Psychiatry. · Pubmed #15795053 No free full text.

Abstract: Individuals with Down syndrome (DS) are at a high risk for developing Alzheimer disease (AD) after the age 40; however, low levels of intellectual functioning, coupled with impaired language ability, confound the detection of AD. Comparative neuropsychological tests developed in animal models of aging and cognition do not require intact language function and can be useful for detecting changes in cognition. Experimental paradigms used to detect age-dependent cognitive deficits in animal models were applied in the present study to measure cognitive function in a group of 20 adults with DS ranging in age from 22 to 58 years. Object discrimination, reversal learning, and spatial and object memory were administered using a modified Wisconsin General Testing Apparatus and reinforcement (penny rewards). When considering age as the only clinical variable to parallel the animal studies, age was significantly correlated with performance on object memory and marginally related to performance on reversal learning and spatial memory. However, when evaluating multiple clinical variables including age, a measure of intellectual ability (FSIQ), scores on the Dementia Questionnaire for Persons with Mental Retardation (DMR), and gender using regression analysis, scores on the DMR were the best predictors of errors of reversal learning, whereas FSIQ was the best predictor of performance on object memory. These results suggest that while age may be related to performance on learning and memory tasks, other clinical variables may be stronger predictors of performance in adults with DS. These changes may reflect prefrontal and medial temporal lobe dysfunction that is associated with the development of AD pathology in DS.

Helguera P, Pelsman A, Pigino G, Wolvetang E, Head E, Busciglio J. · Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697-4550, USA. · J Neurosci. · Pubmed #15745955 links to  free full text

Abstract: Down's syndrome (DS) is characterized by mental retardation and development of Alzheimer's disease (AD). Oxidative stress and mitochondrial dysfunction are both related to neurodegeneration in DS. Several genes in chromosome 21 have been linked to neuronal death, including the transcription factor ets-2. Cortical cultures derived from normal and DS fetal brains were used to study the role of ets-2 in DS neuronal degeneration. ets-2 was expressed in normal human cortical neurons (HCNs) and was markedly upregulated by oxidative stress. When overexpressed in normal HCNs, ets-2 induced a stereotyped sequence of apoptotic changes leading to neuronal death. DS HCNs exhibit intracellular oxidative stress and increased apoptosis after the first week in culture (Busciglio and Yankner, 1995). ets-2 levels were increased in DS HCNs, and, between 7 and 14 d in vitro, DS HCNs showed increased bax, cytoplasmic translocation of cytochrome c and apoptosis inducing factor, and active caspases 3 and 7, consistent with activation of an apoptotic mitochondrial death pathway. Degeneration of DS neurons was reduced by dominant-negative ets-2, suggesting that increased ets-2 expression promotes DS neuronal apoptosis. In the human brain, ets-2 expression was found in neurons and astrocytes. Strong ets-2 immunoreactivity was observed in DS/AD and sporadic AD brains associated with degenerative markers such as bax, intracellular Abeta, and hyperphosphorylated tau. Thus, in DS/AD and sporadic AD brains, converging pathological mechanisms leading to chronic oxidative stress and ets-2 upregulation in susceptible neurons may result in increased vulnerability by promoting the activation of a mitochondrial-dependent proapoptotic pathway of cell death.

Johnson JK, Vogt BA, Kim R, Cotman CW, Head E. · Department of Neurology and Memory and Aging Center, University of California, San Francisco, Calif, USA. · Dement Geriatr Cogn Disord. · Pubmed #15178954 links to  free full text

Abstract: Cognitive impairment in the absence of dementia is common in elderly individuals and is most often studied in the context of an isolated impairment in memory. In the current study, we report the neuropsychological and neuropathological features of a nondemented elderly individual with isolated impairment on a test of executive function (i.e., Trail Making Test) and preserved memory, language, and visuospatial function. Postmortem studies indicated that cortical neurofibrillary tangles (NFT) varied considerably, and some regions contained large numbers of neuritic senile plaques. Semiquantitative immunohistochemistry showed higher NFT and amyloid-beta (Abeta) loads in the frontal cortex relative to the temporal, entorhinal, occipital, and parietal cortices. A survey of the entire cingulate gyrus showed a wide dispersion of Abeta42 with the highest concentration in the perigenual part of the anterior cingulate cortex; Abeta appeared to be linked with neuron loss and did not overlap with the heaviest neuritic degeneration. The current case may represent a nonmemory presentation of mild cognitive impairment (executive mild cognitive impairment) that is associated with frontal and anterior cingulate pathology and may be an early stage of the frontal variant of Alzheimer disease.

Zhao M, Su J, Head E, Cotman CW. · Institute for Brain Aging and Dementia, University of California Irvine, Irvine, CA 92697-4540, USA. · Neurobiol Dis. · Pubmed #14678756 No free full text.

Abstract: The activation of caspase-3 and possibly other caspases during apoptosis may lead to the cleavage of the amyloid precursor protein (APP) and subsequent accumulation of APP cleavage products (cAPP). We examined the association between activated caspase-3 and cAPP in human brain by qualitative and quantitative analysis of in situ immunohistochemistry and Western blots. Frontal cortex and hippocampal tissue from age-matched control and Alzheimer's brains (AD) was used. Both activated caspase-3 and cAPP are increased in AD [Braak and Braak (BB) stage IV-VI] compared to aged control (BB stage 0-1) and transitional (BB stage II-III) cases in the hippocampal and frontal cortex. Caspase-3 activation and the accumulation of APP cleavage fragments appear to either parallel or precede neurofibrillary tangle formation. These findings raise the possibility that the activation of caspase-3 and cleavage of APP may be involved with neuronal degeneration and that pathways characteristic of apoptosis are activated in AD.

Head E, Lott IT, Hof PR, Bouras C, Su JH, Kim R, Haier R, Cotman CW. · Institute for Brain Aging & Dementia, University of California, Irvine, Irvine, California 92697-4540, USA. · J Neuropathol Exp Neurol. · Pubmed #14533781 No free full text.

Abstract: Aged individuals with Down syndrome (DS) develop senile plaques and neurofibrillary tangles consistent with Alzheimer disease (AD). Prior to or in parallel with AD pathology, compensatory growth responses may occur. Immunohistochemistry and confocal microscopy studies in the hippocampus from 15 individuals ranging in age from 5 months to 67 years compared markers of normal and abnormal tau accumulation (phosphorylated tau [AT8, MC-1], tau-1, N-terminal tau) with the extent and location of neuronal growth marker immunoreactivity (BDNF, GAP-43, MAP-2). In middle age (30-40 years), prior to entorhinal neuron loss, the earliest tau accumulation occurred in the outer molecular layer (OML), which was consistent with both pathological and compensatory fetal tau expression. These events were followed at a later age, associated with entorhinal neuron loss, by an increase in GAP-43. Hilar neurons exhibiting a sprouting morphology were also noted. Age-dependent observations in the DS brain in the current study parallel hippocampal compensatory responses described in entorhinal cortex lesion studies in rodents. Thus, compensatory growth responses may occur in DS prior to extensive AD pathology and may be one mechanism underlying observations in PET studies of hypermetabolism in the entorhinal cortex of individuals with DS.