Deposits of beta-amyloid are apparent in ageing and Alzheimer's disease, but the role of this peptide in neurodegeneration is unclear. The free-radical theory of ageing may also account for Alzheimer-type degeneration and consequently links between free-radical generation and beta-amyloid have been sought. We demonstrate here that beta-amyloid interacts with endothelial cells on blood vessels to produce and excess of superoxide radicals, with attendant alterations in endothelial structure and function. The superoxide radical can scavenge endothelium-derived relaxing factor and produce potent oxidizing agents, which can cause lipid peroxidation and other degenerative changes. The alterations in vascular tone and endothelial damage are prevented by the oxygen-radical-scavenging enzyme superoxide dismutase. These observations suggest a normal vasoactive role for beta-amyloid as well as a mechanism by which beta-amyloid may play a role in vascular abnormalities and neurodegeneration mediated by free radicals.

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The neurotoxic and proinflammatory actions of the Alzheimer peptide amyloid-beta (Abeta) are dependent on its aggregation and beta-sheet conformation. Chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin for arthritis decreases the risk of developing Alzheimer's disease (AD) by unknown mechanisms. We report that these drugs inhibit human Abeta aggregation in vitro and reverse the beta-sheet conformation of preformed fibrils at clinically relevant doses. Aspirin prevented enhanced Abeta aggregation by aluminum, an environmental risk factor for AD. This anti-aggregatory effect was restricted to NSAIDs and was not exhibited by other drugs used in AD therapy. NSAIDS may have a role in the prevention and treatment of AD, in addition to a number of age-related disorders such as arthritis, cardiovascular disease and cancer.

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Background. Osteoradionecrosis of the jaw (ORN) is an infrequent yet potentially devastating complication of radiation therapy to the head and neck region. Treatment options include antimicrobial therapy, local sequestrectomy, resection, and the use of hyperbaric oxygen (HBO). Published data on ORN are difficult to compare because of the lack of a universally accepted classification and staging system, and the literature on the use of HBO to either prevent or successfully manage ORN is controversial and inconclusive. Therefore, we aimed to establish a standard approach for using HBO at our institution.

beta-Amyloid (A beta) toxicity has a critical role in the pathology of Alzheimer's disease (AD) but its function in the neurodegenerative process is not clearly established. Recently, we demonstrated a novel action of beta-amyloid on peripheral blood vessels: endothelial dysfunction through reactive oxygen species. Here we report the direct effect of A beta on cerebrovascular endothelium. Following treatment with A beta 1-40, bovine cerebral arteries showed characteristic features of endothelial dysfunction such as increased contraction to vasoconstrictor and diminished relaxation to endothelium-dependent vasodilators. Electron microscopy revealed significant damage to the endothelium by A beta. Pretreatment with the antioxidant superoxide dismutase (SOD) and PBN (n-tert-butyl-alpha-phenylnitrone) antagonized the effects of A beta. Endothelial damage induced by A beta could produce ischemic and inflammatory changes contributing to the pathology of AD.

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