Intracellular Calcium And The Regulation Of Growth Hormone Release By Growth Hormone-releasing Factor And Somatostatin In Rat Somatotrophs

The release of growth hormone (GH) from the somatotrophs of the anterior pituitary is under the control of two hypothalamic peptides, GH-releasing factor (GRF) and somatostatin (SRIF), which stimulates and inhibits release respectively. The aim of this study was to explore the role of intracellular Ca{dollar}\sp{lcub}2+{rcub}{dollar} ( (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar}) in the regulation of GH release by GRF and SRIF in acutely dispersed purified rat somatotrophs.;The role of extracellular Ca{dollar}\sp{lcub}2+{rcub}{dollar} was studied by assessing the effect of Ca{dollar}\sp{lcub}2+{rcub}{dollar}-free medium and Ca{dollar}\sp{lcub}2+{rcub}{dollar} antagonists on GRF-induced GH release. The fluorescent dye indo-1 was used to measure (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar}. Ca{dollar}\sp{lcub}2+{rcub}{dollar} influx was evaluated by measuring {dollar}\sp{lcub}45{rcub}{dollar}Ca uptake.;GRF-stimulated GH release was inhibited in Ca{dollar}\sp{lcub}2+{rcub}{dollar}-free medium. The Ca{dollar}\sp{lcub}2+{rcub}{dollar} anatagonists nifedipine and diltiazem, inhibited basal, K{dollar}\sp{lcub}+{rcub}{dollar}- and GRF-induced GH release. GRF stimulated a triphasic increase in {dollar}\sp{lcub}45{rcub}{dollar}Ca uptake. GRF also stimulated a biphasic increase in (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar}, which was entirely dependent on Ca{dollar}\sp{lcub}2+{rcub}{dollar} influx. SRIF decreased {dollar}\sp{lcub}45{rcub}{dollar}Ca uptake in steady and non-steady states. It also inhibited the steady state GRF-induced increase in {dollar}\sp{lcub}45{rcub}{dollar}Ca uptake. SRIF lowered baseline (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar} and inhibited the increase in (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar} stimulated by GRF. To study the underlying mechanisms involved in the control of (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar} by GRF and SRIF, the effect of K{dollar}\sp{lcub}+{rcub}{dollar} depolarization, cAMP analogues and protein kinase C (PKC) activators on Ca{dollar}\sp{lcub}2+{rcub}{dollar} fluxes and (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar}, were examined. K{dollar}\sp{lcub}+{rcub}{dollar}-dependent depolarization stimulated a nifedipine-sensitive Ca{dollar}\sp{lcub}2+{rcub}{dollar} influx which was not inhibited by SRIF, and which resulted in an increase in (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar}. 8-(4-Chlorophenylthio)-cAMP raised (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar} by stimulating a nifedipine- and SRIF-sensitive Ca{dollar}\sp{lcub}2+{rcub}{dollar} influx. The PKC activators 1,2-dioctanoylglycerol and the phorbol 12-myristate 13-acetate raised (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar} by stimulating a nifedipine- and SRIF-sensitive Ca{dollar}\sp{lcub}2+{rcub}{dollar} influx.;The conclusions of this study are (a) Ca{dollar}\sp{lcub}2+{rcub}{dollar} is essential for GRF-induced GH release; (b) GRF stimulates Ca{dollar}\sp{lcub}2+{rcub}{dollar} influx which results in a biphasic increase in (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar}; (c) SRIF lowers (Ca{dollar}\sp{lcub}2+{rcub}{dollar}) {dollar}\sb{lcub}\rm i{rcub}{dollar} by inhibiting Ca{dollar}\sp{lcub}2+{rcub}{dollar} influx; (d) GRF could stimulate Ca{dollar}\sp{lcub}2+{rcub}{dollar} influx by depolarizing the cell or by increasing cAMP- and PKC-dependent phosphorylation

On the gap structure of UPt3_3: phases A and B

We have used thermal conduction and transverse sound attenuation to probe the anisotropy of the gap structure in two superconducting phases of UPt$_3$. For the low-temperature phase B, transverse sound has in the past provided strong evidence for a line node in the basal plane. Now, from the anisotropy of the thermal conductivity we further establish the presence of a node along the c-axis and provide information on its k-dependence. For the largely unexplored high-temperature phase A, our study of the attenuation for two directions of the polarization yields directional information on the quasiparticle spectrum, and the first clear indication of a different gap structure in the two phases.Comment: 10 pages, 3 figures, to appear in proceedings of SCES9

Validation d'un modèle simplifié pour estimer les chargements au dos

L'objectif de l'étude est de valider une approche basée sur l'orientation des segments des membres supérieurs et du dos et des forces mesurées aux mains pour estimer les chargements lombaires. Plusieurs méthodes d'estimation des chargements au bas du dos ont été documentées par la recherche avec des tâches simples et dans un environnement controlé de laboratoire. Cependant, aucune méthode n'a encore été proposée pour l'estimation de ces chargements dans un environnement réel de travail avec des manutentions plus complexes et sur des durées prolongées. C'est avec cet objectif à long terme qu'un modèle exploitant l'orientation des segments, plutôt que leurs position et orientation, mérite d'être validé. Ces orientations pourraient éventuellement être mesurées par des senseurs inertiels ambulatoires. Six femmes et 5 hommes ont manutentionné des charges de 7,7 kg et de 15,6 kg dans une série de levers et d'abaissements asymétriques et à 2 vitesses : une choisie et une de 25% plus rapide. Un modèle à segments liés du haut du corps a été utilisé pour calculer les chargements 3D à L5/S1. Ce modèle n'utilise que l'orientation des segments et les forces aux mains sont mesurées avec une caisse dynamométrique. Le modèle critère, quant à lui, utilise la cinématique du bas du corps avec l'orientation et la position des segments. Les forces au sol sont mesurées par 3 plateformes de forces formant une grande surface de travail. La validité du modèle a été quantifiée en calculant l'erreur quadratique moyenne (eRMS), les coefficients de détermination (r²), les erreurs maximales et les ratioshaut/bas (moment maximum du modele a valider divise par le moment maximum du modele critere, multiplie par 100). L'eRMS entre les 2 modeles sur le moment resultant a L5/S1 se situe entre 9,9 Nm et 25,4 Nm, le coefficient de determination entre 0,80 et 0,98, l'erreur maximale entre 29 Nm et 142 Nm et les ratios haut/bas sont en moyenne autour de 100%. De plus, l'augmentation de la vitesse moyenne de 22% augmente l'eRMS entre les 2 modèles de 12,7%. L'erreur de ce modèle du haut du corps n'utilisant que l'orientation des segments et les forces aux mains est tout à fait acceptable dans le cadre d'une future utilisation terrain. Dans le cadre d'étude requérant un niveau de précision supérieur, des modifications relativement simples mériteraient d'être investiguées afin d'améliorer la performance du modèle. Dans sa forme actuelle, sa polyvalence pourrait très certainement en faire un excellent outil d'évaluation clinique. Grâce à cette étude, il peut maintenant être envisagé d'estimer les chargements au dos à l'aide de senseurs inertiels pour mesurer les orientations des segments du corps, et donc de faire l'estimation des chargements au dos dans des environnements de travail variés et plus réels

Universal Heat Conduction in YBa_2Cu_3O_6.9

The thermal conductivity of YBa_2Cu_3O_6.9 was measured at low temperatures in untwinned single crystals with concentrations of Zn impurities from 0 to 3% of Cu. A linear term kappa_0/T = 0.19 mW/K^2.cm is clearly resolved as T -> 0, and found to be virtually independent of Zn concentration. The existence of this residual normal fluid strongly validates the basic theory of transport in unconventional superconductors. Moreover, the observed universal behavior is in quantitative agreement with calculations for a gap function of d-wave symmetry.Comment: Latex file, 4 pages, 3 EPS figures, to appear in Physical Review Letter

Integrin α8β1 regulates adhesion, migration and proliferation of human intestinal crypt cells via a predominant RhoA/ROCK-dependent mechanism

Background. Integrins are transmembrane αβ heterodimer receptors that function as structural and functional bridges between the cytoskeleton and ECM (extracellular matrix) molecules. The RGD (arginine-glycine-aspartate tripeptide motif)-dependent integrin α8β1 has been shown to be involved in various cell functions in neuronal and mesenchymal-derived cell types. Its role in epithelial cells remains unknown

Open Data from the Third Observing Run of LIGO, Virgo, KAGRA, and GEO

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages

Search for subsolar-mass black hole binaries in the second part of Advanced LIGO’s and Advanced Virgo’s third observing run

We describe a search for gravitational waves from compact binaries with at least one component with mass 0.2–1.0 M and mass ratio q ≥ 0.1 in Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo data collected between 2019 November 1, 15:00 UTC and 2020 March 27, 17:00 UTC. No signals were detected. The most significant candidate has a false alarm rate of 0.2 yr−1. We estimate the sensitivity of our search over the entirety of Advanced LIGO’s and Advanced Virgo’s third observing run, and present the most stringent limits to date on the merger rate of binary black holes with at least one subsolar-mass component. We use the upper limits to constrain two fiducial scenarios that could produce subsolar-mass black holes: primordial black holes (PBH) and a model of dissipative dark matter. The PBH model uses recent prescriptions for the merger rate of PBH binaries that include a rate suppression factor to effectively account for PBH early binary disruptions. If the PBHs are monochromatically distributed, we can exclude a dark matter fraction in PBHs fPBH 0.6 (at 90 per cent confidence) in the probed subsolar-mass range. However, if we allow for broad PBH mass distributions, we are unable to rule out fPBH = 1. For the dissipative model, where the dark matter has chemistry that allows a small fraction to cool and collapse into black holes, we find an upper bound fDBH < 10−5 on the fraction of atomic dark matter collapsed into black holes