Targeting Synaptic Dysfunction in Alzheimer’s Disease Therapy

In the past years, major efforts have been made to understand the genetics and molecular pathogenesis of Alzheimer??s disease (AD), which has been translated into extensive experimental approaches aimed at slowing down or halting disease progression. Advances in transgenic (Tg) technologies allowed the engineering of different mouse models of AD recapitulating a range of AD-like features. These Tg models provided excellent opportunities to analyze the bases for the temporal evolution of the disease. Several lines of evidence point to synaptic dysfunction as a cause of AD and that synapse loss is a pathological correlate associated with cognitive decline. Therefore, the phenotypic characterization of these animals has included electrophysiological studies to analyze hippocampal synaptic transmission and long-term potentiation, a widely recognized cellular model for learning and memory. Transgenic mice, along with non-Tg models derived mainly from exogenous application of A??, have also been useful experimental tools to test the various therapeutic approaches. As a result, numerous pharmacological interventions have been reported to attenuate synaptic dysfunction and improve behavior in the different AD models. To date, however, very few of these findings have resulted in target validation or successful translation into disease-modifying compounds in humans. Here, we will briefly review the synaptic alterations across the different animal models and we will recapitulate the pharmacological strategies aimed at rescuing hippocampal plasticity phenotypes. Finally, we will highlight intrinsic limitations in the use of experimental systems and related challenges in translating preclinical studies into human clinical trials.     

Simultaneous Enantiomeric Determination of Propranolol,Metoprolol, Pindolol,and Atenolol in Natural Waters by HPLC on New Polysaccharide‐Based Stationary Phase using a Highly Selective Molecularly Imprinted Polymer Extraction

A simple high performance liquid chromatography method HPLC‐UV for simultaneous enantiomeric determination of propranolol, metoprolol, pindolol, and atenolol in natural water samples was developed and validated, using a molecularly imprinted polymer solid‐phase extraction. To achieve this purpose, Lux® Cellulose‐1/Sepapak‐1 (cellulose tris‐(3,5‐dymethylphenylcarbamate)) (Phenomenex, Madrid, Spain) chiral stationary phase was used in gradient elution and normal phase mode at ambient temperature. The gradient elution program optimized consisted of a progressive change of the mobile phase polarity from n‐hex/EtOH/DEA 90/10/0.5 (v/v/v) to 60/40/0.5 (v/v/v) in 13 min, delivered at a flow rate of 1.3 ml/min and a sudden change of flow rate to 2.3 ml/min in 1 min. Critical steps in any molecularly imprinted polymer extraction protocol such as the flow rate to load the water sample in the cartridges and the breakthrough volume were optimized to obtain the higher extraction recoveries for all compounds. In optimal conditions (100 ml breakthrough volume loaded at 2.0 ml/min), extraction recoveries for the four pairs of β‐blockers were near 100%. The MIP‐SPE‐HPLC‐UV method developed demonstrates good linearity (R² ≥ 0.99), precision, selectivity, and sensitivity. Method limit detection was 3.0 µg/l for propranolol and pindolol enantiomers and 20.0 and 22.0 µg/l for metoprolol and atenolol enantiomers, respectively. The proposed methodology should be suitable for routine control of these emerging pollutants in natural waters for a better understanding of the environmental impact and fate. Chirality 24:860–866, 2012. © 2012 Wiley Periodicals, Inc.     

Therapeutic associated with occupational exposure to silica

Occupational exposure to silica dust has been increasing the possible risk of varieties of pathologies. The aim of this study was to evaluate the protective activity of ethanolic extract of Glycyrrhiza glabra roots at doses of 500 and 1000 mg/kg, p.o., given for 7 days against the toxicity of SiO(2) nanoparticles (50mg/kg intraperitoneal for 6 weeks) in rats. Exposure to silica altered various respiratory and biochemical variables, including ALT, AST, albumin, urea, uric acid, creatinine, catalase, LPO and GSH. Treatments with G. glabra extract significantly improved antioxidant status towards control. Stone workers in the Gwalior region exposed to silica dust had higher prevalence of cough, wheezing and shortness of breath. Increased serum ACE level was noted in the silica exposed group. It is of immense need to monitor this problem for betterment of worker's health.     

Nearshore subtidal community structure compared between inner coast and outer coast sites in Southeast Alaska

Processes that structure subarctic marine communities, particularly in glaciated regions, are not well understood. This understanding is needed as a baseline and to manage these communities in the face of future climate-driven changes. This study investigates two coastal regions of Southeast Alaska with the goals to (a) identify and compare patterns of subtidal community structure for macroalgal, fish, macroinvertebrate (>5?cm), and small epibenthic invertebrate (<5?cm) communities between inner coast and outer coast sites and (b) link patterns of community structure to habitat and environmental parameters. Species assemblage and benthic habitat data were used to compare species diversity and community composition at 6?m and 12?m depths at nine inner coast and nine outer coast sites. Multivariate analysis was applied to reduce environmental variables to major gradients, to resolve community structure, and to relate community structure to habitat and environmental variables. Increased salinity and decreased temperature at outer coast sites compared with inner coast sites were associated with community structure, with greater species diversity at outer coast sites at 6?m depth. Invertebrate community composition was associated with benthic habitat, including crust and coralline algae for macroinvertebrates, and algal cover and substrate for small epibenthic invertebrates. This research suggests that marine communities in glaciated regions are strongly influenced by freshwater input and that future climate-driven changes in freshwater input will likely result in marine community composition changes.     

The synthetic purine reversine selectively induces cell death of cancer cells

The synthetic purine reversine has been shown to possess a dual activity as it promotes the de‐differentiation of adult cells, including fibroblasts, into stem‐cell‐like progenitors, but it also induces cell growth arrest and ultimately cell death of cancer cells, suggesting its possible application as an anti‐cancer agent. Aim of this study was to investigate the mechanism underneath reversine selectivity in inducing cell death of cancer cells by a comparative analysis of its effects on several tumor cells and normal dermal fibroblasts. We found that reversine is lethal for all cancer cells studied as it induces cell endoreplication, a process that malignant cells cannot effectively oppose due to aberrations in cell cycle checkpoints. On the other hand, normal cells, like dermal fibroblasts, can control reversine activity by blocking the cell cycle, entering a reversible quiescent state. However, they can be induced to become sensitive to the molecule when key cell cycle proteins, e.g., p53, are silenced. J. Cell. Biochem. 113: 3207–3217, 2012. © 2012 Wiley Periodicals, Inc.     

Interaction between the C‐terminal domains of measles virus nucleoprotein and phosphoprotein: A tight complex implying one binding site

The intrinsically disordered C‐terminal domain (N_TAIL) of the measles virus (MeV) nucleoprotein undergoes α‐helical folding upon binding to the C‐terminal X domain (XD) of the phosphoprotein. The N_TAIL region involved in binding coupled to folding has been mapped to a conserved region (Box2) encompassing residues 489–506. In the previous studies published in this journal, we obtained experimental evidence supporting a K_D for the N_TAIL–XD binding reaction in the nM range and also showed that an additional N_TAIL region (Box3, aa 517–525) plays a role in binding to XD. In striking contrast with these data, studies published in this journal by Kingston and coworkers pointed out a much less stable complex (K_D in the μM range) and supported lack of involvement of Box3 in complex formation. The objective of this study was to critically re‐evaluate the role of Box3 in N_TAIL–XD binding. Since our previous studies relied on N_TAIL‐truncated forms possessing an irrelevant Flag sequence appended at their C‐terminus, we, herein, generated an N_TAIL devoid of Box3 and any additional C‐terminal residues, as well as a form encompassing only residues 482–525. We then used isothermal titration calorimetry to characterize the binding reactions between XD and these N_TAIL forms. Results effectively argue for the presence of a single XD‐binding site located within Box2, in agreement with the results by Kingston et al., while providing clear experimental support for a high‐affinity complex. Altogether, the present data provide mechanistic insights into the replicative machinery of MeV and clarify a hitherto highly debated point.     

Panmixia supports divergence with gene flow in Darwin's small ground finch, Geospiza fuliginosa, on Santa Cruz, Galápagos Islands

The divergence‐with‐gene‐flow model of speciation has a strong theoretical basis with a growing number of plausible examples in nature, but remains hotly debated. Darwin’s finches of the Galápagos Archipelago have played an important role in our understanding of speciation processes. Recent studies suggest that this group may also provide insights into speciation via divergence with gene flow. On the island of Santa Cruz, recent studies found evidence for adaptive divergence in Darwin’s small ground finch, Geospiza fuliginosa, between ecologically contrasting arid and humid zones. Despite the short geographical distance between these zones, strong disruptive selection during low rainfall periods is expected to generate and maintain adaptive divergence. Conversely, during high rainfall periods, when disruptive selection is predicted to be weakened, population divergence in adaptive traits is expected to break down. Because periods of low and high rainfall irregularly alternate, the geographical pattern of adaptive divergence can be assumed to break down and, importantly, regenerate in situ. Here, we use microsatellite allele frequency data to assess the genetic population structure of G. fuliginosa on Santa Cruz. We sample 21 sites and four ecological zones across the island. We reject hypotheses of population substructure linked to ecological and geographical differences among sites in favour of a single panmictic population. Panmixia implies high levels of gene flow within Santa Cruz, which favours selection over genetic drift as a valid process generating phenotypic divergence in G. fuliginosa on Santa Cruz. We discuss how our findings may support classic adaptation, phenotypic plasticity, matching habitat choice or any combination of these three processes.     

Molecular characterization of Syrian date palm cultivars using plasmid-like DNA markers

Date palm (Phoenix dactylifera L.) is one of the most important domesticated fruit trees in the Near East and North African countries. This tree has been, for several decades, in serious threat of being completely destroyed by the “Bayoud” disease caused by Fusarium oxysporum f. sp. albedinis. In this study, 18 Syrian date palm cultivars and four male trees were analyzed according to the identity of mitochondrial plasmid-like DNAs. A PCR strategy that employs plasmid-like DNAs-specific primer pair was used. These primers amplify a product of either 373-bp or 265-bp that corresponds to the S- (Bayoud-susceptible) or the R-plasmid (Bayoud-resistant), respectively. Generated data revealed that only six cultivars (“Medjool”, “Ashrasi”, “Gish Rabi”, “Khineze”, and yellow- and red-“Kabkab”) have the S-plasmid, suggesting their susceptibility to the fusariosis, while the remaining 12 cultivars and the four male trees contain the R-plasmid, suggesting their resistance to the fusariosis. The PCR process applied here has been proved efficient for the rapid screening for the presence of the S and R DNAs in Syrian date palm. PCR markers developed in this study could be useful for the screening of date palm lines growing in the field. The availability of such diagnostic tool for plasmid characterization in date palm would also be of great importance in establishing propagation and breeding programs of date palm in Syria.     

Protein kinase A-mediated phosphorylation modulates cytochrome c oxidase function and augments hypoxia and myocardial ischemia-related injury

We have investigated the effects of hypoxia and myocardial ischemia/reperfusion on the structure and function of cytochrome c oxidase (CcO). Hypoxia (0.1% O(2) for 10 h) and cAMP-mediated inhibition of CcO activity were accompanied by hyperphosphorylation of subunits I, IVi1, and Vb and markedly increased reactive O(2) species production by the enzyme complex in an in vitro system that uses reduced cytochrome c as an electron donor. Both subunit phosphorylation and enzyme activity were effectively reversed by 50 nm H89 or 50 nm myristoylated peptide inhibitor (MPI), specific inhibitors of protein kinase A, but not by inhibitors of protein kinase C. In rabbit hearts subjected to global and focal ischemia, CcO activity was inhibited in a time-dependent manner and was accompanied by hyperphosphorylation as in hypoxia. Additionally, CcO activity and subunit phosphorylation in the ischemic heart were nearly completely reversed by H89 or MPI added to the perfusion medium. Hyperphosphorylation of subunits I, IVi1, and Vb was accompanied by reduced subunit contents of the immunoprecipitated CcO complex. Most interestingly, both H89 and MPI added to the perfusion medium dramatically reduced the ischemia/reperfusion injury to the myocardial tissue. Our results pointed to an exciting possibility of using CcO activity modulators for controlling myocardial injury associated with ischemia and oxidative stress conditions.