Pneumatic device for somatosensorial and pain stimulation compatible with magnetic functional resonance (fMRI) and Magnetoencefalography (MEG) DISNESO- 02

A prototype has been developed to study the somatosensory activation using functional magnetic resonance imaging technologies (fMRI) .The complete system is based on two pneumatic pressure valves that activate an applicator which is totally compatible with the magnetic resonance and magnetoencephalography, and is controlled by programmable software. The system provides stimulation on the tender points area with accuracy of 0.8cm2, and it allows to determine the pain threshold in persons with different neuropathologies related with pain processes. It should be useful in the characterization and distinction of somatosensory, motor and pain areas

Significance of ROS in oxygen sensing in cell systems with sensitivy to ohysiological hypoxia

Reactive oxygen species (ROS) are oxygen-containing molecular entities which are more potent and effective oxidizing agents than is molecular oxygen itself. With the exception of phagocytic cells, where ROS play an important physiological role in defense reactions, ROS have classically been considered undesirable byproducts of cell metabolism, existing several cellular mechanisms aimed to dispose them. Recently, however, ROS have been considered important intracellular signaling molecules, which may act as mediators or second messengers in many cell functions. This is the proposed role for ROS in oxygen sensing in systems, such as carotid body chemoreceptor cells, pulmonary artery smooth muscle cells, and erythropoietin-producing cells. These unique cells comprise essential parts of homeostatic loops directed to maintain oxygen levels in multicellular organisms in situations of hypoxia. The present article examines the possible significance of ROS in these three cell systems, and proposes a set of criteria that ROS should satisfy for their consideration as mediators in hypoxic transduction cascades. In none of the three cell types do ROS satisfy these criteria, and thus it appears that alternative mechanisms are responsible for the transduction cascades linking hypoxia to the release of neurotransmitters in chemoreceptor cells, contraction in pulmonary artery smooth muscle cells and erythropoietin secretion in erythropoietin producing cells

Role of Glutathione Redox State in Oxygen Sensing by Carotid Body Chemoreceptor Cells

Producción CientíficaThis article first presents some basic structural traits of the carotid body (CB) arterial chemoreceptors to understand the relationship between the arterial blood PO2 and the activation of chemoreceptor cells, which are the O2 sensing structures of the CB. Some considerations in relation to the intensity of CB blood flow and O2 consumption of the organ would allow us to define the threshold for the detection of the hypoxic stimulus, which would lead us to the cardinal theme of the article, namely whether at the PO2 levels detected by the CB there alterations in the genesis of re-active oxygen species (ROS). An alteration in the rate of ROS productionwould impinge on the glutathione system [reduced glutathione (GSH) and oxidized glutathione (GSSG)], causing modifications in the GSH/GSSG ratio that are detected by direct measurement; the GSH/GSSG system rep-resents the quantitatively most important mechanism to dispose ROS and to maintain the overall redox status or redox environment in mammalian cells.1 The relationship between GSH/GSSG and oxygen chemoreception is approached from two different points of view. We will measure GSH/GSSG levels and calculate the redox environment of the cells and correl-ation with the activity of chemoreceptor cells in normoxia and in hypoxia. We will also present data on pharmacological manipulation of the redox environment of the cells, as assessed by GSH/GSSG quotients, and pos-sible correlations with the level of activity of chemoreceptor cells. The possible mechanisms of coupling between ROS and the GSH/GSSG system to the cellular effector machineries have been reviewed.2,

Metal-Substituted Microporous Aluminophosphates

This chapter aims to present the zeotypes aluminophosphates (AlPOs) as a complementary alternative to zeolites in the isomorphic incorporation of metal ions within all-inorganic microporous frameworks as well as to discuss didactically the catalytic consequences derived from the distinctive features of both frameworks. It does not intend to be a compilation of either all or the most significant publications involving metal-substituted microporous aluminophosphates. Families of AlPOs and zeolites, which include metal ion-substituted variants, are the dominant microporous materials. Both these systems are widely used as catalysts, in particular through aliovalent metal ions substitution. Here, some general description of the synthesis procedures and characterization techniques of the MeAPOs (metal-contained aluminophosphates) is given along with catalytic properties. Next, some illustrative examples of the catalytic possibilities of MeAPOs as catalysts in the transformation of the organic molecules are given. The oxidation of the hardly activated hydrocarbons has probably been the most successful use of AlPOs doped with the divalent transition metal ions Co2+, Mn2+, and Fe2+, whose incorporation in zeolites is disfavoured. The catalytic role of these MeAPOs is rationalized based on the knowledge acquired from a combination of the most advanced characterization techniques. Finally, the importance of the high specificity of the structure-directing agents employed in the preparation of MeAPOs is discussed taking N,N-methyldicyclohexylamine in the synthesis of AFI-structured materials as a driving force. It is shown how such a high specificity could be predicted and how it can open great possibilities in the control of parameters as critical in catalysis as crystal size, inter-and intracrystalline mesoporosity, acidity, redox properties, incorporation of a great variety of heteroatom ions or final environment of the metal site (surrounding it by either P or Al)

General redox environment and carotid body chemoreceptor function

Carotid body (CB) chemoreceptor cells detect physiological levels of hypoxia and generate a hyperventilation, homeostatic in nature, aimed to minimize the deleterious effects of hypoxia. Intimate mechanisms involved in oxygen sensing in chemoreceptor cells remain largely unknown, but reactive oxygen species (ROS) had been proposed as mediators of this process. We have determined glutathione levels and calculated glutathione redox potential (E GSH; indicator of the general redox environment of cells) in rat diaphragms incubated in the presence of oxidizing agents of two types: nonpermeating and permeating through cell membranes; in the latter group, unspecific oxidants and inhibitors of ROS-disposing enzymes were used. Selected concentrations of oxidizing agents were tested for their ability to modify the normoxic and hypoxic activity of chemoreceptor cells measured in vitro as their rate of release of neurotransmitters. Results evidence variable relationships between EGSH and the activity of chemoreceptor cells. The independence of chemoreceptor cell activity from the EGSH would imply that the ability of the CB to play its homeostatic role is largely preserved in any pathological or toxicological contingency causing oxidative stress. Consistent with this suggestion, it was also found that CB-mediated hypoxic hyperventilation was not altered by treatment of intact animals with agents that markedly decreased the EGSH in all tissues assayed. Copyright © 2009 the American Physiological Society.This work was supported by Dirección General de Investigación Científico y Técnica (DGICYT) Grant BFU2007-61848 and by Centro de Investigación Biomédica en Red (CIBER) Grant CB06/06/0050 (FISS-ICIII) JCyL-GR242.Peer Reviewe

Molecular identification of Kvα subunits that contribute to the oxygen-sensitive K+ current of chemoreceptor cells of the rabbit carotid body

Rabbit carotid body (CB) chemoreceptor cells possess a fast-inactivating K+ current that is specifically inhibited by hypoxia. We have studied the expression of Kvα subunits, which might be responsible for this current. RT-PCR experiments identified the expression of Kv1.4, Kv3.4, Kv4.1 and Kv4.3 mRNAs in the rabbit CB. There was no expression of Kv3.3 or Kv4.2 transcripts. Immunocytochemistry with antibodies to tyrosine hydroxylase (anti-TH) and to specific Kv subunits revealed the expression of Kv3.4 and Kv4.3 in chemoreceptor cells, while Kv1.4 was only found in nerve fibres. Kv4.1 mRNA was also found in chemoreceptor cells following in situ hybridization combined with anti-TH antibody labelling. Kv4.1 and Kv4.3 appeared to be present in all chemoreceptor cells, but Kv3.4 was only expressed in a population of them. Electrophysiological experiments applying specific toxins or antibodies demonstrated that both Kv3.4 and Kv4.3 participate in the oxygen-sensitive K+ current of chemoreceptor cells. However, toxin application experiments confirmed a larger contribution of members of the Kv4 subfamily. [Ca2+]i measurements under hypoxic conditions and immunocytochemistry experiments in dispersed CB cells demonstrated the expression of Kv3.4 and Kv4.3 in oxygen-sensitive cells; the presence of Kv3.4 in the chemoreceptor cell membrane was not required for the response to low PO2. In summary, three Kv subunits (Kv3.4, Kv4.1 and Kv4.3) may be involved in the fast-inactivating outward K+ current of rabbit CB chemoreceptor cells. The homogeneous distribution of the Kv4 subunits in chemoreceptor cells, along with their electrophysiological properties, suggest that Kv4.1, Kv4.3, or their heteromultimers, are the molecular correlate of the oxygen-sensitive K+ channel