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The amyloid beta protein is deposited in the brains of patients with Alzheimer's disease but its pathogenic role is unknown. In culture, the amyloid beta protein was neurotrophic to undifferentiated hippocampal neurons at low concentrations and neurotoxic to mature neurons at higher concentrations. In differentiated neurons, amyloid beta protein caused(More)
Microdialysis is a widely used in vivo sampling technique commonly used to monitor extracellular levels of a variety of molecules including neurotransmitters and metabolites. To facilitate interpretation of microdialysis results, this study critically examines changes in synaptic morphology induced by microdialysis. Tissue surrounding microdialysis probes(More)
Deposition of the beta-amyloid protein in senile plaques is a pathologic hallmark of Alzheimer disease (AD). Focal deposition of beta amyloid in the adult rat cerebral cortex caused profound neurodegenerative changes, including neuronal loss and degenerating neurons and neurites. Chronic induction of the Alz-50 antigen appeared in neurons around focal(More)
During aging of the human brain, and particularly in Alzheimer's disease, progressive neuronal loss is accompanied by the formation of highly stable intra- and extraneuronal protein fibers. Using fluorescence-activated particle sorting, a method has been developed for purifying essentially to homogeneity the extracellular amyloid fibers that form the cores(More)
The role of growth factors in the pathogenesis of Alzheimer disease is unknown. The beta-amyloid protein accumulates abnormally in the brain in Alzheimer disease and is neurotoxic to differentiated hippocampal neurons in culture. Nerve growth factor (NGF) increased the neurotoxic potency of a beta-amyloid polypeptide by a factor of approximately 100,000,(More)
Neurofibrillary tangles (NFT) are the principal structural alteration of neuronal cell bodies in Alzheimer disease as well as in normal aging of the human brain. While the ultrastructure of these intraneuronal lesions has been extensively studied, the biochemical composition of the fibers comprising the NFT is unknown. We report the production of three(More)
Tissues of subsistence-harvested Arctic mammals were analyzed for silver (Ag), cadmium (Cd), and total mercury (THg). Muscle (or total body homogenates of potential fish and invertebrate prey) was analyzed for stable carbon (delta13C) and nitrogen (delta15N) isotopes to establish trophic interactions within the Arctic food chain. Food web magnification(More)
We evaluated effects of location (i.e., Jackpot Bay, a naturally contaminated site, and Herring Bay, reference site), diet as determined by stable isotopes, and age on mercury concentrations in individual river otters (Lontra canadensis) from Prince William Sound, Alaska, USA. We also investigated the effects of mercury accumulation on survival of river(More)
In western Alaska, mercury (Hg) could be a potential health risk to people whose diet is primarily fish-based. In 2000, total Hg (THg) and methylmercury (MeHg) were examined in northern pike (Esox lucius) and Arctic grayling (Thymallus arcticus) from two watersheds in western Alaska, the Yukon and Kuskokwim rivers. Whitefish (Coregonus sp.) were also(More)
Investigations in Prince William Sound (Alaska, USA) following the Exxon Valdez oil spill (EVOS) revealed that river otters (Lontra canadensis) on oiled shores had lower body mass and elevated values of biomarkers, than did otters living on nonoiled shores. In addition, otters from oiled areas selected different habitats, had larger home ranges, and less(More)