Brain Aging and Alzheimer's Disease^*

The most common cause of senile dementia appears to be a pathological process indistinguishable from that found in presenile dementia of the Alzheimer type. Consideration of the neuropathological changes suggest that this disease may involve the interaction of at least three processes: a viral-like infection, a disorder in the immune system and the neurotoxic effect of an environmental agent. The evidence in support of this hypothesis is reviewed. </jats:p

Alzheimer’s Disease: Errors in Gene Expression

Hypotheses concerning the etiology of Alzheimer’s disease are numerous but perhaps two of the most probable involve either an unconventional infectious agent of the scrapie, Creutzfeldt-Jakob family or an error in gene expression. Strong circumstantial evidence supports both hypotheses; however, definitive evidence will require an extensive understanding of the molecular biology of this common cause of senile and presenile dementia.</jats:p

New Evidence for an Active Role of Aluminum in Alzheimer's Disease

ABSTRACT:Application of molecular biological techniques and sensitive elemental analysis have produced new evidence implicating aluminum as an important factor in down regulation of neuronal protein metabolism. Aluminum in Alzheimer's disease may act by electrostatically crosslinking proteins, particularly the methionine containing histone Hl°, and DNA. The consequence of such crosslinking is reduced transcription of at least one neuron specific gene, the low molecular weight component of neurofilaments. In the superior temporal gyrus in Alzheimer's disease, down regulation of this gene occurs in approximately 86% of surviving neurons and, therefore, aluminum must be considered as having an active role in the pathogenesis. Epidemiological studies are reviewed that independently support the hypothesis that environmental aluminum is a significant risk factor. Preliminary evidence also suggests that a disorder in phosphorylation may be an important initiating factor.</jats:p

Chromatin Structure in Scrapie and Alzheimer's Disease

Abstract:Scrapie affected brains exhibit a number of pathological features in common with the human neurodegenerative condition, Alzheimer's disease. The present report describes studies on chromatin structure seen in these two disease processes.Chromatin associated proteins influence transcriptional activity of DNA through an effect upon chromatin structure. We examined chromatin structure by: (1) measuring the capacity of the enzyme micrococcal nuclease to release mono- and dinucleosomes from isolated nuclei and (2) measuring DN A-histone interactions by examining the effect of ambient tonicity upon the release of chromatin proteins.In two strains of mice infected with two strains of scrapie agent there was reduced accessibility to micrococcal nuclease and an increased content on dinucleosomes of the histone HI and Hl° types. These changes precede clinical signs of scrapie and resemble those found in the human conditions of Alzheimer's and Pick's disease. Scrapie mouse brain differs from Alzheimer brain in that scrapie does not alter histone-DNA interactions as monitored by ionically induced histone release from chromatin. Despite similarities, the scrapie agent appears to operate upon different molecular mechanisms than those found in Alzheimer's disease.</jats:p

Microstructural modification in Co/Cu multilayers prepared by low energy ion-assisted deposition

The microstructure of Co/Cu multilayers deposited by low energy ion-assisted deposition was investigated. The samples studied were grown by unbalanced magnetron sputtering with and without an applied d.c. substrate bias of −50 V. Specular and off-specular X-ray reflectivity measurements were performed on the samples and revealed the presence of roughness at the interfaces that was partially correlated throughout the film. The effect of applying a −50 V bias was to suppress the correlation of the lower frequency roughness and to slightly reduce the bilayer period of the multilayer. The differences between the samples are discussed in terms of possible ion bombardment induced smoothing of the layers and densification of the microstructure