Epithelial sodium channel/degenerin family of ion channels: a variety of functions for a shared structure.

The recently discovered epithelial sodium channel (ENaC)/degenerin (DEG) gene family encodes sodium channels involved in various cell functions in metazoans. Subfamilies found in invertebrates or mammals are functionally distinct. The degenerins in Caenorhabditis elegans participate in mechanotransduction in neuronal cells, FaNaC in snails is a ligand-gated channel activated by neuropeptides, and the Drosophila subfamily is expressed in gonads and neurons. In mammals, ENaC mediates Na+ transport in epithelia and is essential for sodium homeostasis. The ASIC genes encode proton-gated cation channels in both the central and peripheral nervous system that could be involved in pain transduction. This review summarizes the physiological roles of the different channels belonging to this family, their biophysical and pharmacological characteristics, and the emerging knowledge of their molecular structure. Although functionally different, the ENaC/DEG family members share functional domains that are involved in the control of channel activity and in the formation of the pore. The functional heterogeneity among the members of the ENaC/DEG channel family provides a unique opportunity to address the molecular basis of basic channel functions such as activation by ligands, mechanotransduction, ionic selectivity, or block by pharmacological ligands.

The importance of micro-habitat in the breeding of Barn Owls Tyto alba

Capsule Habitat parameters associated with 706 Barn Owl (Tyto alba) nesting boxes in Israel were analysed. Pairs bred in 259 of the boxes. The intensity of agricultural practices at nestbox sites were shown to have only a weak effect on aspects of Barn Owl breeding in this region.

Role of ATP-dependent potassium channels in pulmonary vascular tone of fetal lambs with congenital diaphragmatic hernia.

High mortality in newborn babies with congenital diaphragmatic hernia (CDH) is principally due to persistent pulmonary hypertension. ATP-dependent potassium (K(ATP)) channels might modulate pulmonary vascular tone. We have assessed the effects of Pinacidil, a K(ATP) channel opener, and glibenclamide (GLI), a K(ATP) channel blocker, in near full-term lambs with and without CDH. In vivo, pulmonary hemodynamics were assessed by means of pressure and blood flow catheters. In vitro, we used isolated pulmonary vessels and immunohistochemistry to detect the presence of K(ATP) channels in pulmonary tissue. In vivo, pinacidil (2 mg) significantly reduced pulmonary vascular resistance (PVR) in both controls and CDH animals. GLI (30 mg) significantly increased pulmonary arterial pressure (PAP) and PVR in control animals only. In vitro, pinacidil (10 microM) relaxed, precontracted arteries from lambs with and without CDH. GLI (10(-5) microM) did not raise the basal tone of vessels. We conclude that activation of K(ATP) channels could be of interest to reduce pulmonary vascular tone in fetal lambs with CDH, a condition often associated with persistent pulmonary hypertension of the newborn.

Understanding globalization through football: the new international division of labour, migratory channels and transnational trade circuits

Among all sports, football is the one that saw the largest diffusion during the 20th century. Professional leagues exist on all continents and professional footballers are constantly on the move, trying to reach the wealthiest European clubs. Using the football players' market as an example, this article highlights some key features of economic globalization: the new international division of labour, the ever increasing role played by intermediaries to bind the demand and supply of work on a transnational scale, and the setting up of spatially fragmented trade circuits. These processes form the basis for the creation of a global market of footballers in which clubs and championships play complementary roles and are more than ever functionally integrated beyond national borders.

Mutations in the LHX2 gene are not a frequent cause of micro/anophthalmia.

Purpose: Microphthalmia and anophthalmia are at the severe end of the spectrum of abnormalities in ocular development. A few genes (orthodenticle homeobox 2 [OTX2], retina and anterior neural fold homeobox [RAX], SRY-box 2 [SOX2], CEH10 homeodomain-containing homolog [CHX10], and growth differentiation factor 6 [GDF6]) have been implicated mainly in isolated micro/anophthalmia but causative mutations of these genes explain less than a quarter of these developmental defects. The essential role of the LIM homeobox 2 (LHX2) transcription factor in early eye development has recently been documented. We postulated that mutations in this gene could lead to micro/anophthalmia, and thus performed molecular screening of its sequence in patients having micro/anophthalmia. Methods: Seventy patients having non-syndromic forms of colobomatous microphthalmia (n=25), isolated microphthalmia (n=18), or anophthalmia (n=17), and syndromic forms of micro/anophthalmia (n=10) were included in this study after negative molecular screening for OTX2, RAX, SOX2, and CHX10 mutations. Mutation screening of LHX2 was performed by direct sequencing of the coding sequences and intron/exon boundaries. Results: Two heterozygous variants of unknown significance (c.128C > G [p.Pro43Arg]; c.776C > A [p.Pro259Gln]) were identified in LHX2 among the 70 patients. These variations were not identified in a panel of 100 control patients of mixed origins. The variation c.776C > A (p.Pro259Gln) was considered as non pathogenic by in silico analysis, while the variation c.128C > G (p.Pro43Arg) considered as deleterious by in silico analysis and was inherited from the asymptomatic father. Conclusions: Mutations in LHX2 do not represent a frequent cause of micro/anophthalmia.

Hypoxia-induced inhibition of epithelial Na(+) channels in the lung. Role of Nedd4-2 and the ubiquitin-proteasome pathway.

Transepithelial sodium transport via alveolar epithelial Na(+) channels (ENaC) and Na(+),K(+)-ATPase constitutes the driving force for removal of alveolar edema fluid. Alveolar hypoxia associated with pulmonary edema may impair ENaC activity and alveolar Na(+) absorption through a decrease of ENaC subunit expression at the apical membrane of alveolar epithelial cells (AECs). Here, we investigated the mechanism(s) involved in this process in vivo in the β-Liddle mouse strain mice carrying a truncation of β-ENaC C-terminus abolishing the interaction between β-ENaC and the ubiquitin protein-ligase Nedd4-2 that targets the channel for endocytosis and degradation and in vitro in rat AECs. Hypoxia (8% O2 for 24 h) reduced amiloride-sensitive alveolar fluid clearance by 69% in wild-type mice but had no effect in homozygous mutated β-Liddle littermates. In vitro, acute exposure of AECs to hypoxia (0.5-3% O2 for 1-6 h) rapidly decreased transepithelial Na(+) transport as assessed by equivalent short-circuit current Ieq and the amiloride-sensitive component of Na(+) current across the apical membrane, reflecting ENaC activity. Hypoxia induced a decrease of ENaC subunit expression in the apical membrane of AECs with no change in intracellular expression and induced a 2-fold increase in α-ENaC polyubiquitination. Hypoxic inhibition of amiloride-sensitive Ieq was fully prevented by preincubation with the proteasome inhibitors MG132 and lactacystin or with the antioxidant N-acetyl-cysteine. Our data strongly suggest that Nedd4-2-mediated ubiquitination of ENaC leading to endocytosis and degradation of apical Na(+) channels is a key feature of hypoxia-induced inhibition of transepithelial alveolar Na(+) transport.

Organismos filantrópicos y no gubernamentales en el desarrollo de nuevas ciencias y tecnologías: el caso de las micro y nanotecnologías en México

RESUMEN: La emergencia de nuevas ciencias y tecnologías vienen acompañadas de nuevas dinámicas en la producción, el uso y la diseminación de nuevos conocimientos científicos y tecnológicos. Estas nuevas dinámicas se reflejan en la reorganización de las actividades científicas, en la creación o la reorientación de nuevas temáticas en la investigación, en la emergencia de nuevas preocupaciones y debates sobre los riesgos e implicaciones sociales, y en la participación de nuevos actores en el desarrollo de la ciencia y la tecnología, entre otros factores. En este artículo se presentan los resultados del estudio sobre las funciones de un organismo con orígenes filantrópicos y no gubernamental que ha sido central en el desarrollo de los sistemas microelectromecánicos (MEMS) en México. Las funciones que se analizan han sido y son desarrolladas en las diferentes etapas del desarrollo de esta tecnología emergente en este país. Además de mostrar las funciones desempeñadas por este tipo de organismo, este texto se cuestiona sobre la modelización de las relaciones entre las diferentes entidades presentes en el desarrollo e instalación de nuevas tecnologías. En las conclusiones intentamos avanzar algunos elementos para tomar en cuenta estos organismos y enriquecer los estudios sociales sobre las nuevas ciencias y tecnologías. ABSTRACT: The emergence of new sciences and technologies come with new dynamics in the production, use and dissemination of new scientific and technological knowledge. These new dynamics are reflected in the reorganization of scientific activities, in creating or redirecting new topics in research, in the emergence of new concerns and debates about the risks and social implications, and the participation of new actors in the development of science and technology, among other factors. This article presents the results of the study on the functions of an organism with philanthropic and non-governmental sources that has been central to the development of microelectromechanical systems (MEMS) in Mexico. The functions have been discussed and are developed at different stages of development of this emerging technology in this country. In addition to showing the functions of such a body, this text is questioned on modeling the relationships between the various entities in the development and deployment of new technologies. In the conclusions we try moving some elements to take into account these organisms and enrich social studies on the new sciences and technologies.

The L-Type Ca2+ and KATP channels may contribute to pacing-induced protection against anoxia-reoxygenation in the embryonic heart model

Rapport de synthèse : Implication des canaux Ca2+ de type L et des canaux KATP dans la protection induite par pacing dans un modèle de coeur embryonnaire soumis à l'anoxieréoxygénation. Contexte et but : le canal Ca2+ de type L, les canaux K+ du sarcolemme (sarcKatp) et de la mitochondrie (mitoKatp) interviennent dans le préconditionnement ischémique ou pharmacologique du myocarde. La présente étude cherche à déterminer dans quelle mesure ces canaux peuvent aussi jouer un rôle dans la cardioprotection induite par pacing. Méthodes :des coeurs d'embryons de poulet âgés de 4 jours ont été soumis in ovo à un pacing durant 12 heures, en pratiquant une stimulation électrique ventriculaire asynchrone intermittente à 110% de la fréquence cardiaque intrinsèque. Les coeurs contrôles (sham) et les coeurs stimulés ont ensuite été soumis in vitro à une période d'anoxie de 30 minutes, suivie d'une réoxygénation de 60 minutes. Les coeurs ont été exposés à l'agoniste du canal Ca2+ de type L (Bay-K-8644, BAY-K) ou à son bloqueur (vérapamil, VERAP), à l'antagoniste non sélectif des canaux KATP (glibenclamide, GLIB), ainsi qu'à l'agoniste du canal mitoKATP (diazoxide, DIAZO), ou à son antagoniste (5-hydroxydécanoate, 5-HD). L'électrocardiogramme, le délai électro-mécanique (DEM) reflétant le couplage excitation-contraction, ainsi que la contractilité myocardique ont été systématiquement déterminés pendant l'anoxieréoxygénation. Résultats : en normoxie, la fréquence cardiaque, l'intervalle QT, la conduction atrioventriculaire, le DEM et le raccourcissement ventriculaires étaient identiques dans les coeurs sham et les coeurs stimulés. Par contre, au cours de la réoxygénation post-anoxique, les arythmies cessaient plus précocément et le DEM ventriculaire retrouvait plus rapidement son niveau initial dans les coeurs stimulés, comparés aux sham. Dans les coeurs sham, BAY-K (mais pas le VERAP), DIAZO (mais pas le 5HD) ou GLIB accéléraient la récupération du DEM ventriculaire, reproduisant ainsi la protection induite par le pacing. En revanche, aucun de ces agents n'affectait la récupération des cceurs stimulés. Conclusion : un pacing ventriculaire chronique et intermittent délivré à une fréquence quasi physiologique améliore la tolérance myocardique à une anoxie-réoxygénation ultérieure. L'approche pharmacologique amontré qu'une activation discrète du canal Ca2+ de type L, une inhibition du canal sarcKATP et/ou une ouverture du canal mitoKATP peuvent contribuer à la cardioprotection induite par le pacing.

International union of basic and clinical pharmacology. XCI. structure, function, and pharmacology of acid-sensing ion channels and the epithelial Na+ channel.

The epithelial Na(+) channel (ENaC) and the acid-sensing ion channels (ASICs) form subfamilies within the ENaC/degenerin family of Na(+) channels. ENaC mediates transepithelial Na(+) transport, thereby contributing to Na(+) homeostasis and the maintenance of blood pressure and the airway surface liquid level. ASICs are H(+)-activated channels found in central and peripheral neurons, where their activation induces neuronal depolarization. ASICs are involved in pain sensation, the expression of fear, and neurodegeneration after ischemia, making them potentially interesting drug targets. This review summarizes the biophysical properties, cellular functions, and physiologic and pathologic roles of the ASIC and ENaC subfamilies. The analysis of the homologies between ENaC and ASICs and the relation between functional and structural information shows many parallels between these channels, suggesting that some mechanisms that control channel activity are shared between ASICs and ENaC. The available crystal structures and the discovery of animal toxins acting on ASICs provide a unique opportunity to address the molecular mechanisms of ENaC and ASIC function to identify novel strategies for the modulation of these channels by pharmacologic ligands.

On-line desorption of dried blood spot: A novel approach for the direct LC/MS analysis of micro-whole blood samples.

The aim of this work is to present a new concept, called on-line desorption of dried blood spots (on-line DBS), allowing the direct analysis of a dried blood spot coupled to liquid chromatography mass spectrometry device (LC/MS). The system is based on an inox cell which can receive a blood sample (10 microL) previously spotted on a filter paper. The cell is then integrated into LC/MS system where the analytes are desorbed out of the paper towards a column switching system ensuring the purification and separation of the compounds before their detection on a single quadrupole MS coupled to atmospheric pressure chemical ionisation (APCI) source. The described procedure implies that no pretreatment is necessary in spite the analysis is based on whole blood sample. To ensure the applicability of the concept, saquinavir, imipramine, and verapamil were chosen. Despite the use of a small sampling volume and a single quadrupole detector, on-line DBS allowed the analyses of these three compounds over their therapeutic concentrations from 50 to 500 ng/mL for imipramine and verapamil and from 100 to 1000 ng/mL for saquinavir. Moreover, the method showed good repeatability with relative standard deviation (RSD) lower than 15% based on two levels of concentration (low and high). Function responses were found to be linear over the therapeutic concentration for each compound and were used to determine the concentrations of real patient samples for saquinavir. Comparison of the founded values with those of a validated method used routinely in a reference laboratory showed a good correlation between the two methods. Moreover, good selectivity was observed ensuring that no endogenous or chemical components interfered with the quantitation of the analytes. This work demonstrates the feasibility and applicability of the on-line DBS procedure for bioanalysis.

Effects of antiresorptive agents on bone micro-architecture assessed by Trabecular Bone Score in women age 50 and older. The Manitoba Prospective Study

Antiresorptive agents such as bisphosphonates induce a rapid increase of BMD during the 1st year of treatment and a partial maintenance of bone architecture. Trabecular Bone Score (TBS), a new grey-level texture measurement that can be extracted from the DXA image, correlates with 3D parameters of bone micro-architecture. Aim: To evaluate the longitudinal effect of antiresorptive agents on spine BMD and on site-matched spine microarchitecture as assessed by TBS. Methods: From the BMD database for Province of Manitoba, Canada, we selected women age >50 with paired baseline and follow up spine DXA examinations who had not received any prior HRT or other antiresorptive drug.Women were divided in two subgroups: (1) those not receiving any HRT or antiresorptive drug during follow up (=non-users) and (2) those receiving non-HRT antiresorptive drug during follow up (=users) with high adherence (medication possession ratio >75%) from a provincial pharmacy database system. Lumbar spine TBS was derived by the Bone Disease Unit, University of Lausanne, for each spine DXA examination using anonymized files (blinded from clinical parameters and outcomes). Effects of antiresorptive treatment for users and non-users on TBS and BMD at baseline and during mean 3.7 years follow-up were compared. Results were expressed % change per year. Results: 1150 non-users and 534 users met the inclusion criteria. At baseline, users and non-users had a mean age and BMI of [62.2±7.9 vs 66.1±8.0 years] and [26.3±4.7 vs 24.7±4.0 kg/m²] respectively. Antiresorptive drugs received by users were bisphosphonates (86%), raloxifene (10%) and calcitonin (4%). Significant differences in BMD change and TBS change were seen between users and nonusers during follow-up (p<0.0001). Significant decreases in mean BMD and TBS (−0.36± 0.05% per year; −0.31±0.06% per year) were seen for non-users compared with baseline (p<0.001). A significant increase in mean BMD was seen for users compared with baseline (+1.86±0.0% per year, p<0.0018). TBS of users also increased compared with baseline (+0.20±0.08% per year, p<0.001), but more slowly than BMD. Conclusion: We observed a significant increase in spine BMD and a positive maintenance of bone micro-architecture from TBS with antiresorptive treatment, whereas the treatment naïve group lost both density and micro-architecture. TBS seems to be responsive to treatment and could be suitable for monitoring micro-architecture. This article is part of a Special Issue entitled ECTS 2011. Disclosure of interest: M.-A. Krieg: None declared, A. Goertzen: None declared, W. Leslie: None declared, D. Hans Consulting fees from Medimaps.