Novel TASK channels inhibitors derived from dihydropyrrolo[2,1-a]isoquinoline

TASK channels belong to the family of K(+) channels with 4 transmembrane segments and 2 pore domains (4TM/2P) per subunit. These channels have been related to apoptosis in cerebellar granule neurons (CGN), as well as cancer in other tissues. TASK current is regulated by hormones, neurotransmitters, anesthetics and divalent cations, which are not selective. Recently, there has been found some organic compounds that inhibit TASK current selectively. In order to find other modulators, we report here a group of five dihydropyrrolo[2,1-a]isoquinolines (DPIs), four of them with putative anticancer activity, that were evaluated on TASK-1 and TASK-3 channels. The compounds 1, 2 and 3 showed IC50 < 320 μM on TASK-1 and TASK-3, intermediate activity on TASK-1/TASK-3 heterodimer, moderate effect over hslo and TREK-1 (500 μM), and practically not inhibition on Shaker-IR, herg and IRK2.1 potassium channels, when they were expressed heterologously in Xenopus laevis oocytes. In rat CGN, 500 μM of these three compounds induced a decrement by >39% of the TASK-carried leak current. Finally, only compound 1 showed significant protection (∼36%) against apoptotic death of CGN induced by K(+) deprivation. These results suggest that DPI compounds could be potential candidates for designing new selective inhibitors of TASK channels.

Calpain activation induced by glucose deprivation is mediated by oxidative stress and contributes to neuronal damage

The mechanisms leading to neuronal death during glucose deprivation have not been fully elucidated, but a role of oxidative stress has been suggested. In the present study we have investigated whether the production of reactive oxygen species during glucose deprivation, contributes to the activation of calpain, a calcium-dependent protease involved in neuronal injury associated with brain ischemia and cerebral trauma. We have observed a rapid activation of calpain, as monitored by the cleavage of the cytoskeletal protein α-spectrin, after glucose withdrawal, which is reduced by inhibitors of xanthine oxidase, phospholipase A2 and NADPH oxidase. Results suggest that phospholipase A2 and NADPH oxidase contribute to the early activation of calpain after glucose deprivation. In particular NOX2, a member of the NADPH oxidase family is involved, since reduced stimulation of calpain activity is observed after glucose deprivation in hippocampal slices from transgenic mice lacking a functional NOX2. We observed an additive effect of the inhibitors of xanthine oxidase and phospholipase A2 on both ROS production and calpain activity, suggesting a synergistic action of these two enzymes. The present results provide new evidence showing that reactive oxygen species stimulate calpain activation during glucose deprivation and that this mechanism is involved in neuronal death.

Effectiveness of the trivalent influenza vaccine in Navarre, Spain, 2010-2011: a population-based test-negative case-control study

BACKGROUND

Some studies have evaluated vaccine effectiveness in preventing outpatient influenza while others have analysed its effectiveness in preventing hospitalizations. This study evaluates the effectiveness of the trivalent influenza vaccine in preventing outpatient illness and hospitalizations from laboratory-confirmed influenza in the 2010-2011 season.

METHODS

We conducted a nested case-control study in the population covered by the general practitioner sentinel network for influenza surveillance in Navarre, Spain. Patients with influenza-like illness in hospitals and primary health care were swabbed for influenza testing. Influenza vaccination status and other covariates were obtained from health care databases. Using logistic regression, the vaccination status of laboratory-confirmed influenza cases was compared with that of test-negative controls, adjusting for age, sex, comorbidity, outpatient visits in the previous 12 months, health care setting, time between symptom onset and swabbing, period and A(H1N1)pdm09 vaccination. Effectiveness was calculated as (1-odds ratio)x100.

RESULTS

The 303 confirmed influenza cases (88% for A(H1N1)pdm09 influenza) were compared with the 286 influenza test-negative controls. The percentage of persons vaccinated against influenza was 4.3% and 15.7%, respectively (p<0.001). The adjusted estimate of effectiveness was 67% (95% CI: 24%, 86%) for all patients and 64% (95% CI: 8%, 86%) in those with an indication for vaccination (persons age 60 or older or with major chronic conditions). Having received both the 2010-2011 seasonal influenza vaccine and the 2009-2010 pandemic influenza vaccine provided 87% protection (95% CI: 30%, 98%) as compared to those not vaccinated.

CONCLUSION

The 2010-2011 seasonal influenza vaccine had a moderate protective effect in preventing laboratory-confirmed influenza.

Caspase-12 activation is involved in amyloid-β protein-induced synaptic toxicity

Synapse loss is considered to be the best correlate of cognitive impairments in Alzheimer's disease (AD), and growing evidence supports the notion that certain events that trigger neuronal death in AD can be initiated by the local activation of caspases within the synaptic compartment. We have demonstrated previously that presynaptic terminals are particularly vulnerable to endoplasmic-reticulum (ER)-stress depending of amyloid-β protein (Aβ). This toxicity included a notable reduction of actin and synaptophysin protein and mitochondrial dysfunction. This synaptic damage was prevented by incubation with a wide range of caspase inhibitor, suggesting the activation of local synaptic apoptotic mechanisms. The ER-resident caspase-12 was initially identified as a mediator of Aβ neurotoxicity. Thus, the current study was conducted to explore the presence and local activation of the caspase-12 in cortical and hippocampal synaptosomes isolated from rat and from the triple transgenic mouse model of AD (3xTg-AD) in the presence of Aβ and ryanodine. Under these conditions, we found mitochondrial failure accompanied by a reduction in actin levels which was dependent on caspase-12 activation suggesting its participation in Aβ-induced synaptic toxicity.

Cellular viability effects of fatty acid amide hydrolase inhibition on cerebellar neurons

The endocannabinoid anandamide (ANA) participates in the control of cell death inducing the formation of apoptotic bodies and DNA fragmentation. The aim of this study was to evaluate whether the ANA degrading enzyme, the fatty acid amide hydrolase (FAAH), would induce cellular death. Experiments were performed in cerebellar granule neurons cultured with the FAAH inhibitor, URB597 (25, 50 or 100 nM) as well as endogenous lipids such as oleoylethanolamide (OEA) or palmitoylethanolamide (PEA) and cellular viability was determined by MTT test. Neurons cultured with URB597 (25, 50 or 100 nM) displayed a decrease in cellular viability. In addition, if cultured with OEA (25 nM) or PEA (100 nM), cellular death was found. These results further suggest that URB597, OEA or PEA promote cellular death.

Reactive oxygen species are related to ionic fluxes and volume decrease in apoptotic cerebellar granule neurons: role of NOX enzymes

Reactive oxygen species (ROS) are produced early during apoptosis of cerebellar granule neurons induced by low potassium (K5) and staurosporine (Sts). In addition, K5 and Sts activate NADPH oxidases (NOX). Recently, we described that K5 and Sts induce apoptotic volume decrease (AVD) at a time when ROS generation and NOX activity occur. In the present study, we evaluated the relationship between ROS generation and ionic fluxes during AVD. Here, we showed that K5- and Sts-induced AVD was inhibited by antioxidants and that direct ROS production induced AVD. Moreover, NOX inhibitors eliminated AVD induced by both K5 and Sts. Sts, but not K5, failed to induce AVD in cerebellar granule neurons from NOX2 knockout mice. These findings suggest that K5- and Sts-induced AVD is largely mediated by ROS produced by NOX. On the other hand, we also found that the blockage of ionic fluxes involved in AVD inhibited both ROS generation and NOX activity. These findings suggest that ROS generation and NOX activity are involved in ionic fluxes activation, which in turn could maintain ROS generation by activating NOX, leading to a self-amplifying cycle.

[The 2009 H1N1 flu pandemic in Navarre, Spain]

BACKGROUND

To describe flu activity during the 2009-2010 pandemic in Navarre and compare it to previous seasons.

METHODS

An analysis was made of all flu cases reported in primary care and all the virological confirmations made in patients in primary care and in hospitals of Navarre between week 21 of 2009 and week 20 of 2010.

RESULTS

Influenza A (H1N1) Virus 2009 was detected in Navarre between week 23 of 2009 and week 2 of 2010, a period when 39 medically diagnosed cases of flu syndrome per 1,000 inhabitants were registered. The epidemic threshold was surpassed in two periods, with a peak in July and a greater one in November. The greatest incidence was reached in children aged between 5 and 14 years (121 per thousand), followed by the group of under fives. There were 224 hospitalisations (36 per 100,000 inhabitants) with confirmation of Influenza A (H1N1) Virus 2009, 8% of whom required admission to intensive care units and there were four deaths (0.6 per 100,000 inhabitants). The rate of hospitalisation was greater amongst children under five (163 per 100,000 inhabitants), while the probability of referral to intensive care increased with age.

CONCLUSION

In spite of not having a specific vaccine available until the season was very well advanced, Influenza A (H1N1)Virus 2009 produced a flu wave with similar levels to those of other seasons and its repercussion in hospitalisations and serious cases was moderate.

NOX2 mediates apoptotic death induced by staurosporine but not by potassium deprivation in cerebellar granule neurons

Neuronal apoptotic death involves the participation of reactive oxygen species (ROS), but their sources have not been completely elucidated. Previous studies have demonstrated that the ROS-producing enzyme NADPH oxidase is present in neuronal cells and that this enzyme could participate in the apoptotic neuronal death. Cerebellar granule neurons (CGN) undergo apoptosis when cells are transferred from a medium with 25 mM KCl (K25) to a 5 mM KCl (K5) medium or when they are treated with staurosporine (ST). Under these conditions, apoptotic death of CGN is dependent on ROS production. In this study, we evaluated the role of NOX2, an NADPH oxidase homolog, in the apoptotic death of CGN induced by two different conditions. In CGN from NOX2-deficient (ko) mice, a significantly lower rate of apoptotic death occurs compared with wild-type (wt) CGN. Also, caspase-3 activation, NADPH oxidase activity, and superoxide anion production induced by ST were markedly lower in ko neurons than in wt CGN. In contrast to the case with ST, when CGN were treated with K5, no differences were observed between ko and wt cells in any of the parameters measured. However, all NADPH oxidase inhibitors tested noticeably reduced cell death and apoptotic parameters induced by K5 in both wt and ko CGN. These results suggest that NOX2 could be necessary for apoptotic death induced by ST, but not by K5, which could require other member of the NOX family in the apoptotic process.

Role of NADPH oxidase in the apoptotic death of cultured cerebellar granule neurons

Cerebellar granule neurons (CGN) cultured in a medium containing 25 mM KCl and treated with staurosporine (ST) or transferred to a medium with 5 mM KCl (K5) die apoptotically. CGN death is mediated by an increase in reactive oxygen species (ROS) production. When CGN are treated with antioxidants all apoptotic parameters and cell death are markedly diminished, showing a central role for ROS in this process. Recently, it has been suggested that a possible ROS source involved in cell death is a NADPH oxidase. In that regard, we found expression in CGN of the components of NADPH proteins, p40phox, p47phox and p67phox, and p22phox, as well as three homologues of the catalytic subunit of this complex, NOX1, 2, and 4. The inhibition of NADPH oxidase with diphenylene iodonium or 4-(2-aminoethyl)benzenesulfonyl fluoride significantly reduced ROS production, NADPH oxidase activity, all the apoptotic events, and cell death induced by both K5 and ST. We conclude that ROS could be an early signal of apoptotic neuronal death and that NADPH oxidase, including NOX1, 2, and/or 4, could have a central role in apoptotic death induced by different conditions in these neurons.

Variability in the performance of preventive services and in the degree of control of identified health problems: a primary care study protocol

Background

Preventive activities carried out in primary care have important variability that makes necessary to know which factors have an impact in order to establish future strategies for improvement. The present study has three objectives: 1) To describe the variability in the implementation of 7 preventive services (screening for smoking status, alcohol abuse, hypertension, hypercholesterolemia, obesity, influenza and tetanus immunization) and to determine their related factors; 2) To describe the degree of control of 5 identified health problems (smoking, alcohol abuse, hypertension, hypercholesterolemia and obesity); 3) To calculate intraclass correlation coefficients.

Design

Multi-centered cross-sectional study of a randomised sample of primary health care teams from 3 regions of Spain designed to analyse variability and related factors of 7 selected preventive services in years 2006 and 2007. At the end of 2008, we will perform a cross-sectional study of a cohort of patients attended in 2006 or 2007 to asses the degree of control of 5 identified health problems. All subjects older than16 years assigned to a randomised sample of 22 computerized primary health care teams and attended during the study period are included in each region providing a sample with more than 850.000 subjects. The main outcome measures will be implementation of 7 preventive services and control of 5 identified health problems. Furthermore, there will be 3 levels of data collection: 1) Patient level (age, gender, morbidity, preventive services, attendance); 2) Health-care professional level (professional characteristics, years working at the team, workload); 3) Team level (characteristics, electronic clinical record system). Data will be transferred from electronic clinical records to a central database with prior encryption and dissociation of subject, professional and team identity. Global and regional analysis will be performed including standard analysis for primary health care teams and health-care professional level. Linear and logistic regression multilevel analysis adjusted for individual and cluster variables will also be performed. Variability in the number of preventive services implemented will be calculated with Poisson multilevel models. Team and health-care professional will be considered random effects. Intraclass correlation coefficients, standard error and variance components for the different outcome measures will be calculated.

Cytoplasmic calcium mediates oxidative damage in an excitotoxic /energetic deficit synergic model in rats

Excessive calcium is responsible for triggering different potentially fatal metabolic pathways during neurodegeneration. In this study, we evaluated the role of calcium on the oxidative damage produced in an in vitro combined model of excitotoxicity/energy deficit produced by the co-administration of quinolinate and 3-nitropropionate to brain synaptosomal membranes. Synaptosomal fractions were incubated in the presence of subtoxic concentrations of these agents (21 and 166 microm, respectively). In order further to characterize possible toxic mechanisms involved in oxidative damage in this experimental paradigm, agents with different properties - dizocilpine, acetyl L-carnitine, iron porphyrinate and S-allylcysteine - were tested at increasing concentrations (10-1000 microm). Lipid peroxidation was assessed by the formation of thiobarbituric acid-reactive substances. For confirmatory purposes, additional fractions were incubated in parallel in the presence of the intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM). Under physiological conditions of extracellular calcium availability, synaptomes exposed to both toxins displayed an increased lipoperoxidation (76% above controls), and this effect was partially attenuated by the tested agents as follows: dizocilpine = iron porphyrinate > acetyl L-carnitine > S-allylcysteine. When the incubation medium was deprived of calcium, the lipoperoxidative effect achieved in this experimental paradigm was still high (49% above the control), and the order of attenuation was: iron porphyrinate > S-allylcysteine > acetyl L-carnitine > dizocilpine. BAPTA-AM was effective in preventing the pro-oxidant action of both toxins, promoting even lower peroxidative levels than those quantified under basal conditions. Our results suggest that the lipid peroxidation induced in synaptosomal fractions by quinolinate plus 3-nitropropionate is largely dependent on the cytoplasmic concentrations of calcium.

AtMCP1b, a chloroplast-localised metacaspase, is induced in vascular tissue after wounding or pathogen infection

cDNA corresponding to the Arabidopsis type I metacaspase AtMCP1b was isolated from plants infected with Pseudomonas syringae. A positive correlation between AtMCP1b expression and cell death was observed in the presence of staurosporine, a protein kinase inhibitor that induces programmed cell death. The tissue localisation of an AtMCP1b promoter-GUS fusion was observed in the vascular tissue of transgenic plants. GUS activity increased in response to an incompatible DC3000 (avrRpm1) or a compatible DC3000 P. syringae infection, or to wounding. Confocal and immunohistochemical analysis of Arabidopsis thaliana (L.) leaves showed that an AtMCP1b-GFP fusion protein was localised in the chloroplasts. Our data support a positive correlation between AtMCP1b gene expression and cell death in response to wounding or pathogenic interactions. Moreover, the localisation of AtMCP1b gene expression within vascular tissue and cells of abscission regions strongly supports a role for AtMCP1b in programmed cell dismantling events in response to environmental and developmental triggers. The AtMCP1b-GFP subcellular localisation infers a role for the plastid organelles in PCD and, thus, in responses to pathogen attack and development.

Role of brain-derived neurotrophic factor in the protective action of N-methyl-D-aspartate in the apoptotic death of cerebellar granule neurons induced by low potassium

Several neurotrophic factors, including brain-derived neurotrophic factor (BDNF), and neurotransmitters, such as glutamate, may influence neuronal apoptotic death. Rat cerebellar granule neurons (CGN) cultured in low potassium (5 or 10 mM KCl) for more than 5 days in vitro (DIV) die apoptotically. These cells survive in the presence of high potassium (25 mM KCl, K25) or N-methyl-D-aspartate (NMDA), an agonist of glutamatergic receptors. CGN transferred from high to low potassium die apoptotically. Here, we characterized the effect of BDNF and NMDA on the apoptotic death induced by low potassium in CGN. Cell death of CGN by culturing in low potassium for 6 DIV was inhibited by BDNF and NMDA. When CGN were cultured in K25 and transferred to a low-potassium medium, 65% of neurons died after 48 hr. Under these conditions, BDNF, NMDA, or BDNF + NMDA increased CGN survival. Both BDNF and NMDA decreased caspase-9 activity and mRNA caspase-3 levels and activity induced by low potassium. CGN survival induced by BDNF is mediated by TrkB activation, whereas that induced by NMDA is mediated by NMDA receptor and TrkB activation. NMDA, but not BDNF, raised [Ca(2+)](i), which was reduced by low-potassium treatment. These results suggest that NMDA receptor stimulation induces CGN survival through the influx of extracellular Ca(2+) that may evoke the release of BDNF and the activation of TrkB. Complementary mechanisms induced by depolarization and changes in Ca(2+) levels would also contribute to the neuroprotection exerted by NMDA and potassium.