Publications

BACKGROUND AND PURPOSE Neuroprotection is an important strategy for ischemic stroke treatment. Cajaninstilbene acid (CSA), a unique stilbenoid with a styryl group, is a potential neuroprotective agent. Hence, this study aimed to evaluate the neuroprotective effect and molecular mechanism of CSA against cerebral ischemia/reperfusion (I/R) damages. EXPERIMENTAL APPROACH The ischemic stroke was modeled by oxygen and glucose deprivation/reoxygenation (OGD/R) in SH-SY5Y cells and transient middle cerebral artery occlusion/reperfusion (MCAO/R) in rats. Tert-butyl hydroperoxide (t-BHP) was used to induce oxidative stress in cells. The signaling pathways were analyzed by Western blotting and inhibitor blocking. KEY RESULTS CSA possessed significant neuroprotective activity, as evidenced by the reduced cell death in OGD/R or t-BHP injured cells, and decreased infarct volume and neurological deficits in MCAO/R rats. Further studies indicated that the protective effect was achieved via the antioxidant activity of CSA, which decreased the oxidative stress and its related mitochondrial dysfunction in cells. Notably, Nrf2 was activated in cells and MCAO/R rats by CSA, and the inhibition of Nrf2 by brusatol weakened CSA-mediated neuroprotection. Furthermore, after applying a series of kinase inhibitors, CSA-induced Nrf2 activation was markedly inhibited by BML-275 (an AMPK inhibitor), implying that AMPK was the dominant kinase to regulate the Nrf2 pathway for CSA’s neuroprotective effects with enhanced AMPK phosphorylation observed both in vivo and in vitro. CONCLUSION AND IMPLICATION CSA exerted neuroprotection via activating AMPK/Nrf2 pathway to reduce I/R-induced cellular oxidative stress and mitochondrial disfunction. CSA could be a potential neuroprotective drug candidate for the treatment of ischemic stroke.

The lack of nocturnal decline in lood pressure (BP) has been associated with an increase in end-organ-damage and cardiovascular events [Verdecchia et al. Hypertension 1994;24:793-801], although results are still controversial partly due to the inability to properly reproduce over time the classification of patients into dippers and non-dippers [Omboni et al. J Hypertens 1988;16:733-738]. Moreover, the non-dipping status has been frequently related to an increase in nocturnal activity and/or differences in quality of sleep [Kario et al. Hypertension 1999;34:685-691]. With the aim to assess the relationship between activity and BP, we studied 160 mild-to-moderate hypertensive patients (82 men), 54.2±1.3 (mean±SE) years of age. BP was measured at 20-minute intervals during the day and at 30-minute intervals at night for 48 consecutive hours with an ambulatory Spacelabs 90207 device. Physical activity was simultaneously monitored by wrist actigraphy. Circadian parameters of BP and activity established by population multiple-components analysis [Fernández & Hermida. Chronobiol Int 1998;15:191-204] were compared between dippers (n=67) and non-dippers (systolic nocturnal decline<10%) by nonparametric testing. Diurnal and nocturnal means of BP and activity were computed for each patient according to individual resting hours determined by actigraphy. Despite highly statistically significant differences in nocturnal mean as well as in each hourly nightly mean of BP between dippers and non-dippers, there were no differences on those parameters in activity. Duration of sleep as well as 24-hour mean and standard deviation of activity were also similar between groups (P>0.108), although non-dippers have a slightly decrease in diurnal mean of activity (P=0.030). The highly significantly different circadian variation in BP between dipper and non-dipper patients with essential hypertensive is not related to a significant increase in nocturnal physical activity.

Due to recent regulations encouraging the reduction of single-use plastic waste, compostable plastics are replacing polyethylene (PE) for applications in the form of thin films. Seven commercial brands of compostable bags and three brands of PE bags (conventional, oxodegradable and recycled), as well as their corresponding resins, were assessed in terms of major components of the polymeric matrix, qualitative and quantitative composition in additives of bags and their leachates, and ecotoxicological effects on test species representative of the main marine taxa, namely microalgae, copepods, sea-urchin embryos, bivalves and fish. Polybutylene-adipate-terephthalate (PBAT), an oil-based polymer, was the main component of all compostable bags analysed, and most of them also included in their composition polylactic-acid (PLA) and starch. Compostable bags showed a higher number of chemical additives than conventional PE bags, and generally higher concentrations of phthalate plasticizers and organophosphate flame retardants. This includes chemicals registered in the EU as exhibiting acute and chronic aquatic toxicity levels 1 and 2. Following standard procedures for plastic leachates, no effects of any product were found on microalgae and fish larva, but bioplastics consistently showed a higher short term aquatic toxicity to marine invertebrates compared to PE items. None of the toxicity levels found though support concerning effects at environmentally relevant plastic densities. Remarkably higher levels of some metals were found in recycled PE compared to first-use conventional PE bags. In conclusion, based on these findings, compostable bags cannot be considered chemically or ecotoxicologically safer products than PE bags.

Abstract The presence of even minute amounts of protein aggregates in solution can significantly alter the kinetics of amyloid formation. Removal of such pre‐existing aggregates is critical for reproducible analysis of amyloid formation. Here we examine the effects of membrane filtration on insulin fibrillization. We find that filtration of insulin with large pore membranes (≥100 nm) generally slows fibril formation relative to unfiltered solutions by removing pre‐aggregated protein. Unexpectedly, filtration with small pore membranes (&lt;100 nm) showed no beneficial effect and, in some cases, accelerated insulin fibril formation. This effect may be due to fragmentation of pre‐existing aggregates during filtration through small pore membranes, which can increase the number of amyloid‐forming precursors. These findings reveal the complexity of removing protein aggregates via filtration and suggest optimal filtration protocols for conducting fibril formation analysis of insulin and similar amyloidogenic proteins. Biotechnol. Bioeng. 2012; 109:840–845. © 2011 Wiley Periodicals, Inc.

Abstract We examined the effect of increasing the number of sampled amplified fragment length polymorphism (AFLP) bands to reconstruct an accurate and well‐supported AFLP‐based phylogeny. In silico AFLP was performed using simulated DNA sequences evolving along balanced and unbalanced model trees with recent, uniform and ancient radiations and average branch lengths (from the most internal node to the tip) ranging from 0.02 to 0.05 substitutions per site. Trees were estimated by minimum evolution (ME) and maximum parsimony (MP) methods from both DNA sequences and virtual AFLP fingerprints. The comparison of the true tree with the estimated AFLP trees suggests that moderate numbers of AFLP bands are necessary to recover the correct topology with high bootstrap support values (i.e. &gt;70%). Fewer numbers of bands are necessary for shorter tree lengths and for balanced than for unbalanced tree topologies. However, branch length estimation was rather unreliable and did not improve substantially after a certain number of bands were sampled. These results hold for different levels of genome coverage and number of taxa analysed. In silico AFLP using bacterial genomic DNA sequences recovered a well‐supported tree topology that mirrored an empirical phylogeny based on a set of 31 orthologous gene sequences when as few as 263 AFLP bands were scored. These results suggest that AFLPs may be an efficient alternative to traditional DNA sequencing for accurate topology reconstruction of shallow trees when not very short ancestral branches exist.