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Amyloid-␤ (A␤) toxicity has been postulated to initiate synaptic loss and subsequent neuronal degeneration seen in Alzheimer's disease (AD). We previously demonstrated that the standardized Ginkgo biloba extract EGb 761, commonly used to enhance memory and by AD patients for dementia, inhibits A␤-induced apoptosis in neuroblastoma cells. In this study, we use EGb 761 and its single constituents to associate A␤ species with A␤-induced pathological behaviors in a model organism, Caenorhabditis elegans. We report that EGb 761 and one of its components, ginkgolide A, alleviates A␤-induced pathological behaviors, including paralysis, and reduces chemotaxis behavior and 5-HT hypersensitivity in a transgenic C. elegans. We also show that EGb 761 inhibits A␤ oligomerization and A␤ deposits in the worms. Moreover, reducing oxidative stress is not the mechanism by which EGb 761 and ginkgolide A suppress A␤-induced paralysis because the antioxidant L-ascorbic acid reduced intracellular levels of hydrogen peroxide to the same extent as EGb 761, but was not nearly as effective in suppressing paralysis in the transgenic C. elegans. These findings suggest that (1) EGb 761 suppresses A␤-related pathological behaviors, (2) the protection against A␤ toxicity by EGb 761 is mediated primarily by modulating A␤ oligomeric species, and (3) ginkgolide A has therapeutic potential for prevention and treatment of AD.

Background and Purpose-Determining the underlying cause of stroke is important to optimize secondary prevention treatment. Increased blood levels of natriuretic peptides (B-type natriuretic peptide/N-terminal pro-BNP [BNP/ NT-proBNP]) have been repeatedly associated with cardioembolic stroke. Here, we evaluate their clinical value as pathogenic biomarkers for stroke through a literature systematic review and individual participants' data meta-analysis. Methods-We searched publications in PubMed database until November 2013 that compared BNP and NT-proBNP circulating levels among stroke causes. Standardized individual participants' data were collected to estimate predictive values of BNP/NT-proBNP for cardioembolic stroke. Dichotomized BNP/NT-proBNP levels were included in logistic regression models together with clinical variables to assess the sensitivity and specificity to identify cardioembolic strokes and the additional value of biomarkers using area under the curve and integrated discrimination improvement index. Results-From 23 selected articles, we collected information of 2834 patients with a defined cause. BNP/NT-proBNP levels were significantly elevated in cardioembolic stroke until 72 hours from symptoms onset. Predictive models showed a sensitivity >90% and specificity >80% when BNP/NT-proBNP were added considering the lowest and the highest quartile, respectively. Both peptides also increased significantly the area under the curve and integrated discrimination improvement index compared with clinical models. Sensitivity, specificity, and precision of the models were validated in 197 patients with initially undetermined stroke with final pathogenic diagnosis after ancillary follow-up. Conclusions-Natriuretic peptides are strongly increased in cardioembolic strokes. Future multicentre prospective studies comparing BNP and NT-proBNP might aid in finding the optimal biomarker, the best time point, and the optimal cutoff points for cardioembolic stroke identification. 2 Patients with cardioembolic stroke are treated with anticoagulant drugs, whereas antiplatelet agents are the treatment of choice for patients with large artery atherosclerosis (LAA) stroke and small vessel disease (SVD).3 Cardioembolic strokes are generally more severe and more prone to recurrence than LAA or SVD and account for approximately one fifth of ischemic strokes. 4 However, in spite of the importance of an accurate etiopathogenic classification, the cause of ≈35% of patients remains undetermined, even after complete evaluation.5 This group of patients presents a rate of recurrence of ≈30% during the first year after the event, partly explained by an inappropriate secondary prevention treatment.6 Stroke of undetermined cause is an heterogeneous group that includes patients with 2 or more potential causes of stroke, patients with <50% of stenosis and patients with a negative diagnostic workup.7 From the latter, a negative diagnostic might be caused by a transitory or reversible condition which is difficult to detect, such as a...