Journal of Alzheimer's disease : JAD
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A strong perception exists that elderly people are at risk for persistent cognitive deterioration lasting longer than six months following major surgery, particularly heart surgery. Furthermore, based on laboratory evidence, investigators hypothesize that surgery or anesthesia might precipitate incident dementia. Recent clinical studies have found that cognition might frequently be impaired within the first few months postoperatively, and that such impairment may be associated with death or debility. ⋯ There is evidence that most patients recover cognition in the long-term, and that for those who experience persistent decline, this is probably attributable to underlying undiagnosed neurological disease or other co-morbidities rather than to surgery or to anesthesia. There is currently minimal clinical evidence linking surgery or anesthesia to incident dementia. Rigorous clinical research is needed to resolve the controversy whether anesthesia or surgery is likely to cause persistent neurological decline or to precipitate dementia.
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PET imaging of amyloid-β has recently emerged as a valuable biomarker to support the in vivo diagnosis of Alzheimer's disease (AD). So far, however, no tracer is available suitable for general clinical routine application. Florbetaben is a promising 18F-labeled amyloid-β-targeted PET tracer currently in Phase 2/3 clinical development. ⋯ Ongoing florbetaben PET trials deal with correlating the in vivo PET signal to post mortem histopathology evaluation, and with investigating the value of the tracer to predict progression to AD at the stage of mild cognitive impairment. The preclinical and clinical data currently available verify florbetaben as a safe and efficacious PET tracer suitable for detection of amyloid-β deposition in the brain. The results of the ongoing trials will contribute to current knowledge on the characteristics of florbetaben, and will help to determine the future potential of florbetaben PET imaging as a visual adjunct to supplement the routine clinical "AD diagnostic toolbox".
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Review
Membrane anchored and lipid raft targeted β-secretase inhibitors for Alzheimer's disease therapy.
β-secretase, a key enzyme involved in amyloid-β generation, is an attractive candidate for Alzheimer's disease therapy. Transition-state inhibitors of β-secretase are designed to achieve specificity. However, these inhibitors bind only to the active conformation of the enzyme and as the active β-secretase is sequestered in subcellular compartments, new strategies have to be implemented. ⋯ In addition, membrane-anchoring of soluble inhibitors reduces the dimensionality of the inhibitor and consequently increases the inhibitor concentration at the target membrane plane. Such inhibitors have great potential in terms of substrate selectivity and reduced side effects. Not only for β-secretase, this strategy could be applied for many membrane targets that are localized either at the plasma membrane or in the endocytic compartments.
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Neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, Prion disease, Huntington's disease, and amyotrophic lateral sclerosis are increasingly being realized to have common cellular and molecular mechanisms including protein aggregation and inclusion body formation in selected brain regions. The aggregates usually consist of insoluble fibrillar aggregates containing misfolded protein with β-sheet conformation. The most probable explanation is that inclusions and the aggregates symbolize an end stage of a molecular cascade of several events, and that earlier event in the cascade may be more directly tied up to pathogenesis than the inclusions themselves. ⋯ Compelling evidence suggests the role of misfolded proteins in the form of oligomers might lead to synaptic dysfunction, neuronal apoptosis and brain damage. However, the mechanism by which oligomers trigger neurodegeneration still remains mysterious. The aim of this article is to review the literature around the molecular mechanism and role of oligomers in neurodegeneration and leading approaches toward rational therapeutics.