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Sample records for bkca channel alpha

  1. MITOCHONDRIAL BKCa CHANNEL

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    Enrique eBalderas

    2015-03-01

    Full Text Available Since its discovery in a glioma cell line 15 years ago, mitochondrial BKCa channel (mitoBKCa has been studied in brain cells and cardiomyocytes sharing general biophysical properties such as high K+ conductance (~300 pS, voltage-dependency and Ca2+-sensitivity. Main advances in deciphering the molecular composition of mitoBKCa have included establishing that it is encoded by the Kcnma1 gene, that a C-terminal splice insert confers mitoBKCa ability to be targeted to cardiac mitochondria, and evidence for its potential coassembly with β subunits. Notoriously, β1 subunit directly interacts with cytochrome c oxidase and mitoBKCa can be modulated by substrates of the respiratory chain. mitoBKCa channel has a central role in protecting the heart from ischemia, where pharmacological activation of the channel impacts the generation of reactive oxygen species and mitochondrial Ca2+ preventing cell death likely by impeding uncontrolled opening of the mitochondrial transition pore. Supporting this view, inhibition of mitoBKCa with Iberiotoxin, enhances cytochrome c release from glioma mitochondria. Many tantalizing questions remain. Some of them are: how is mitoBKCa coupled to the respiratory chain? Does mitoBKCa play non-conduction roles in mitochondria physiology? Which are the functional partners of mitoBKCa? What are the roles of mitoBKCa in other cell types? Answers to these questions are essential to define the impact of mitoBKCa channel in mitochondria biology and disease.

  2. BKCa-Channel Structure and Function

    Science.gov (United States)

    Cox, Daniel H.

    Among ion channels, the large-conductance Ca2+-activated K+ channel (BKCa channel) is in many ways unique. It has a very large single-channel conductance—ten times that of most vertebrate K+ channels—and yet it maintains strict K+ selectivity. It senses as little as 200 nM Ca2+, but it contains no consensus Ca2+-binding motifs, and it is the only channel to be activated by both intracellular Ca2+ and membrane voltage. In fact, there is a synergy between these stimuli such that the higher the internal Ca2+ concentration ([Ca2+]), the smaller the depolarization needed to activate the channel. Furthermore, the BKCa channel has its own brand of auxiliary subunits that profoundly affect gating. In this chapter, I will discuss what is understood about the origins of these properties in terms of allosteric models and channel structure. At the outset, however, I should say that there is not yet a crystal structure of the BKCa channel or any of its components, so much of the current thinking about BKCa-channel structure relies on analogy to other channels.

  3. Molecular investigations of BK(Ca) channels and the modulatory beta-subunits in porcine basilar and middle cerebral arteries

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    Johansson, Helle Wulf; Hay-Schmidt, Anders; Poulsen, Asser Nyander

    2009-01-01

    arteries using reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR. Western blotting was used to detect immunoreactivity for the porcine BK(Ca) channel alpha-subunit and beta-subunit proteins. The BK(Ca) channel alpha-subunit RNA and protein distribution patterns were......Large conductance calcium-activated potassium (BK(Ca)) channels are fundamental in the regulation of cerebral vascular basal tone. We investigated the expression of the mRNA transcripts for the BK(Ca) channel and its modulatory beta-subunits (beta1-beta4) in porcine basilar and middle cerebral...... visualized using in situ hybridization and immunofluorescence studies, respectively. The study verified that the BK(Ca) channel alpha-subunit is located to smooth muscle cells of porcine basilar and middle cerebral arteries. The mRNA transcript for beta1-, beta2- and beta4-subunit were shown by RT...

  4. Modes of Operation of the BKCa Channel β2 Subunit

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    Savalli, Nicoletta; Kondratiev, Andrei; de Quintana, Sarah Buxton; Toro, Ligia; Olcese, Riccardo

    2007-01-01

    The β2 subunit of the large conductance Ca2+- and voltage-activated K+ channel (BKCa) modulates a number of channel functions, such as the apparent Ca2+/voltage sensitivity, pharmacological and kinetic properties of the channel. In addition, the N terminus of the β2 subunit acts as an inactivating particle that produces a relatively fast inactivation of the ionic conductance. Applying voltage clamp fluorometry to fluorescently labeled human BKCa channels (hSlo), we have investigated the mechanisms of operation of the β2 subunit. We found that the leftward shift on the voltage axis of channel activation curves (G(V)) produced by coexpression with β2 subunits is associated with a shift in the same direction of the fluorescence vs. voltage curves (F(V)), which are reporting the voltage dependence of the main voltage-sensing region of hSlo (S4-transmembrane domain). In addition, we investigated the inactivating mechanism of the β2 subunits by comparing its properties with the ones of the typical N-type inactivation process of Shaker channel. While fluorescence recordings from the inactivated Shaker channels revealed the immobilization of the S4 segments in the active conformation, we did not observe a similar feature in BKCa channels coexpressed with the β2 subunit. The experimental observations are consistent with the view that the β2 subunit of BKCa channels facilitates channel activation by changing the voltage sensor equilibrium and that the β2-induced inactivation process does not follow a typical N-type mechanism. PMID:17591990

  5. Modes of operation of the BKCa channel beta2 subunit.

    Science.gov (United States)

    Savalli, Nicoletta; Kondratiev, Andrei; de Quintana, Sarah Buxton; Toro, Ligia; Olcese, Riccardo

    2007-07-01

    The beta(2) subunit of the large conductance Ca(2+)- and voltage-activated K(+) channel (BK(Ca)) modulates a number of channel functions, such as the apparent Ca(2+)/voltage sensitivity, pharmacological and kinetic properties of the channel. In addition, the N terminus of the beta(2) subunit acts as an inactivating particle that produces a relatively fast inactivation of the ionic conductance. Applying voltage clamp fluorometry to fluorescently labeled human BK(Ca) channels (hSlo), we have investigated the mechanisms of operation of the beta(2) subunit. We found that the leftward shift on the voltage axis of channel activation curves (G(V)) produced by coexpression with beta(2) subunits is associated with a shift in the same direction of the fluorescence vs. voltage curves (F(V)), which are reporting the voltage dependence of the main voltage-sensing region of hSlo (S4-transmembrane domain). In addition, we investigated the inactivating mechanism of the beta(2) subunits by comparing its properties with the ones of the typical N-type inactivation process of Shaker channel. While fluorescence recordings from the inactivated Shaker channels revealed the immobilization of the S4 segments in the active conformation, we did not observe a similar feature in BK(Ca) channels coexpressed with the beta(2) subunit. The experimental observations are consistent with the view that the beta(2) subunit of BK(Ca) channels facilitates channel activation by changing the voltage sensor equilibrium and that the beta(2)-induced inactivation process does not follow a typical N-type mechanism.

  6. Putative Structural and Functional Coupling of the Mitochondrial BKCa Channel to the Respiratory Chain.

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    Piotr Bednarczyk

    Full Text Available Potassium channels have been found in the inner mitochondrial membranes of various cells. These channels regulate the mitochondrial membrane potential, the matrix volume and respiration. The activation of these channels is cytoprotective. In our study, the single-channel activity of a large-conductance Ca(2+-regulated potassium channel (mitoBKCa channel was measured by patch-clamping mitoplasts isolated from the human astrocytoma (glioblastoma U-87 MG cell line. A potassium-selective current was recorded with a mean conductance of 290 pS in symmetrical 150 mM KCl solution. The channel was activated by Ca(2+ at micromolar concentrations and by the potassium channel opener NS1619. The channel was inhibited by paxilline and iberiotoxin, known inhibitors of BKCa channels. Western blot analysis, immuno-gold electron microscopy, high-resolution immunofluorescence assays and polymerase chain reaction demonstrated the presence of the BKCa channel β4 subunit in the inner mitochondrial membrane of the human astrocytoma cells. We showed that substrates of the respiratory chain, such as NADH, succinate, and glutamate/malate, decrease the activity of the channel at positive voltages. This effect was abolished by rotenone, antimycin and cyanide, inhibitors of the respiratory chain. The putative interaction of the β4 subunit of mitoBKCa with cytochrome c oxidase was demonstrated using blue native electrophoresis. Our findings indicate possible structural and functional coupling of the mitoBKCa channel with the mitochondrial respiratory chain in human astrocytoma U-87 MG cells.

  7. Molecular studies of BKCa channels in intracranial arteries: presence and localization

    DEFF Research Database (Denmark)

    Johansson, Helle Wulf; Hay-Schmidt, Anders; Poulsen, Asser Nyander

    2008-01-01

    of the BK(Ca) channel in rat basilar, middle cerebral, and middle meningeal arteries by reverse transcription polymerase chain reaction (RT-PCR), quantitative real-time PCR, and Western blotting. Distribution patterns were investigated using in situ hybridization and immunofluorescence studies. RT......-PCR and quantitative real-time PCR detected the expression of the BK(Ca) channel mRNA transcript in rat basilar, middle cerebral, and middle meningeal arteries, with the transcript being expressed more abundantly in rat basilar arteries than in middle cerebral and middle meningeal arteries. Western blotting detected...... and localization of both mRNA and protein expression of the BK(Ca) channel in the smooth muscle cell layer in rat basilar, middle cerebral, and middle meningeal arteries....

  8. Fenamates block gap junction coupling and potentiate BKCa channels in guinea pig arteriolar cells

    Science.gov (United States)

    Li, Xin-Zhi; Ma, Ke-Tao; Guan, Bing-Cai; Li, Li; Zhao, Lei; Zhang, Zhong-Shuang; Si, Jun-Qiang; Jiang, Zhi-Gen

    2013-01-01

    We determined the actions of the fenamates, flufenamic acid (FFA) and niflumic acid (NFA), on gap junction-mediated intercellular coupling between vascular smooth muscle cells (VSMC) in situ of acutely isolated arteriole segments from the three vascular beds: the spiral modiolar artery (SMA), anterior inferior cerebellar artery (AICA) and mesenteric artery (MA), and on non-junctional membrane channels in dispersed VSMCs. Conventional whole-cell recording methods were used. FFA reversibly suppressed the input conductance (Ginput) or increased the input resistance (Rinput) in a concentration dependent manner, with slightly different IC50s for the SMA, AICA and MA segments (26, 33 and 56 μM respectively, P>0.05). Complete electrical isolation of the recorded VSMC was normally reached at ≥300 μM. NFA had a similar effect on gap junction among VSMCs with an IC50 of 40, 48 and 62 μM in SMA, AICA and MA segments, respectively. In dispersed VSMCs, FFA and NFA increased outward rectifier K+-current mediated by the big conductance calcium-activated potassium channel (BKCa) in a concentration-dependent manner, with a similar EC50 of ~300 μM for both FFA and NFA in the three vessels. Iberiotoxin, a selective blocker of the BKCa, suppressed the enhancement of the BKCa by FFA and NFA. The KV blocker 4-AP had no effect on the fenamates-induced K+-current enhancement. We conclude that FFA and NFA blocked the vascular gap junction mediated electrical couplings uniformly in arterioles of the three vascular beds, and complete electrical isolation of the recorded VSMC is obtained at ≧300 μM; FFA and NFA also activate BKCa channels in the arteriolar smooth muscle cells in addition to their known inhibitory effects on chloride channels. PMID:23420003

  9. Activation of BK(Ca channels in zoledronic acid-induced apoptosis of MDA-MB-231 breast cancer cells.

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    Yu-Guang Ma

    Full Text Available BACKGROUND: Zoledronic acid, one of the most potent nitrogen-containing biphosphonates, has been demonstrated to have direct anti-tumor and anti-metastatic properties in breast cancer in vitro and in vivo. In particular, tumor-cell apoptosis has been recognized to play an important role in the treatment of metastatic breast cancer with zoledronic acid. However, the precise mechanisms remain less clear. In the present study, we investigated the specific role of large conductance Ca(2+-activated potassium (BK(Ca channel in zoledronic acid-induced apoptosis of estrogen receptor (ER-negative MDA-MB-231 breast cancer cells. METHODOLOGY/PRINCIPAL FINDINGS: The action of zoledronic acid on BK(Ca channel was investigated by whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry, analysis of fragmented DNA by agarose gel electrophoresis, and flow cytometry assays. Cell proliferation was investigated by MTT test and immunocytochemistry. In addition, such findings were further confirmed with human embryonic kidney 293 (HEK293 cells which were transfected with functional BK(Ca α-subunit (hSloα. Our results clearly indicated that zoledronic acid directly increased the activities of BK(Ca channels, and then activation of BK(Ca channel by zoledronic acid contributed to induce apoptosis in MDA-MB-231 cells. The possible mechanisms were associated with the elevated level of intracellular Ca(2+ and a concomitant depolarization of mitochondrial membrane potential (Δψm in MDA-MB-231 cells. CONCLUSIONS: Activation of BK(Ca channel was here shown to be a novel molecular pathway involved in zoledronic acid-induced apoptosis of MDA-MB-231 cells in vitro.

  10. β3-Adrenoceptor-mediated relaxation of rat and human urinary bladder : roles of BKCa channels and Rho kinase

    NARCIS (Netherlands)

    Cernecka, Hana; Kersten, Kim; Maarsingh, Harm; Elzinga, Carolina R.; de Jong, Igle Jan; Korstanje, Cees; Michel, Martin C.; Schmidt, Martina

    Previous studies suggest that the large-conductance Ca2+-activated K+ (BKCa) channel and Rho-kinase play major roles in the control of urinary bladder tone. Here, we investigated their involvement in beta-adrenoceptor (AR)-mediated relaxation of rat and human bladder. Concentration-response curves

  11. Molecular and functional identification of cyclic AMP-sensitive BKCa potassium channels (ZERO variant) and L-type voltage-dependent calcium channels in single rat juxtaglomerular cells

    DEFF Research Database (Denmark)

    Friis, Ulla G; Jørgensen, Finn; Andreasen, Ditte

    2003-01-01

    This study aimed at identifying the type and functional significance of potassium channels and voltage-dependent calcium channels (Ca(v)) in single rat JG cells using whole-cell patch clamp. Single JG cells displayed outward rectification at positive membrane potentials and limited net currents......, respectively. Double immunofluorescence confirmed the presence of BKCa and renin in the same cell. cAMP increased the outward current by 1.6-fold, and this was inhibited by 74% with iberiotoxin. Expression of the cAMP-sensitive splice variant (ZERO) of BKCa was confirmed in single-sampled JG cells by RT...... no effect. We conclude that JG cells express functional cAMP-sensitive BKCa channels (the ZERO splice variant) and voltage-dependent L-type Ca2+ channels....

  12. Propofol causes vasodilation in vivo via TRPA1 ion channels: role of nitric oxide and BKCa channels.

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    Sinha, Sayantani; Sinharoy, Pritam; Bratz, Ian N; Damron, Derek S

    2015-01-01

    Transient receptor potential (TRP) ion channels of the A1 (TRPA1) and V1 (TRPV1) subtypes are key regulators of vasomotor tone. Propofol is an intravenous anesthetic known to cause vasorelaxation. Our objectives were to examine the extent to which TRPA1 and/or TRPV1 ion channels mediate propofol-induced depressor responses in vivo and to delineate the signaling pathway(s) involved. Mice were subjected to surgery under 1.5-2.5% sevoflurane gas with supplemental oxygen. After a stable baseline in mean arterial pressure (MAP) was achieved propofol (2.5, 5.0, 10.0 mg/kg/min) was administered to assess the hemodynamic actions of the intravenous anesthetic. The effect of nitric oxide synthase (NOS) inhibition with L-NAME and/or calcium-gated K+ channel (BKCa) inhibition with Penetrim A (Pen A), alone and in combination, on propofol-induced decreases in mean arterial pressure were assessed in control C57Bl/6J, TRPA1-/-, TRPV1-/- and double-knockout mice (TRPAV-/-). Propofol decreased MAP in control mice and this effect was markedly attenuated in TRPA1-/- and TRPAV-/- mice but unaffected in TRPV1-/-mice. Moreover, pretreatment with L-NAME or Pen A attenuated the decrease in MAP in control and TRPV1-/- mice, and combined inhibition abolished the depressor response. In contrast, the markedly attenuated propofol-induced depressor response observed in TRPA1-/- and TRPAV-/- mice was unaffected by pre-treatment with Pen A or L-NAME when used either alone or in combination. These data demonstrate for the first time that propofol-induced depressor responses in vivo are predominantly mediated by TRPA1 ion channels with no involvement of TRPV1 ion channels and includes activation of both NOS and BKCa channels.

  13. In Vitro Contractile Response of Rabbit Myometrium to BKCa and KATP Potassium Channel Openers

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    Soňa Fraňová

    2009-01-01

    Full Text Available The aim of the study was to evaluate the participation of ligand-sensitive potassium large conductance calcium-activated channels (BKCa and ATP-sensitive potassium channels in uterine smooth muscle reactivity during different stages of the experimentally induced proliferatory and secretory phase in the sexual cycle in ovariectomised rabbits in vitro. The myometrial reactivity to oxytocin (10-6 mol l-1 was investigated by an in vitro method in female rabbits 14 days after ovariectomy treated with 17β-estradiol - 1 mg/kg/day i.m. for 7 days, or with a combination of progesterone 2 mg/kg/day s.c. for 7 days and 17β-estradiol - 0.2 mg/ kg/day (day 3–7. The strips of myometrial smooth muscle were incubated with a specific opener (NS 1619 and an antagonist (TEA of potassium large conductance calcium-activated channel, or with a specific opener (pinacidil and an antagonist (glybenclamide of ATP-sensitive potassium channels before the administration of oxytocin. NS1619 produced more potent inhibition of the oxytocin-induced contraction during the gestagen dominance (experimental secretory phase than the one observed during the oestrogen dominance (experimental proliferatory phase. TEA antagonized the NS1619 induced inhibition of the myometrial contraction. In the matter of KATP potassium channels, after the administration of pinacidil we observed a similar situation in the changes of myometrial contractility. Pinacidil produced more pronounced inhibition of oxytocin-induced contraction during the secretory phase, and its effect was abolished by the selective inhibitor glybenclamide. Our experimental results indicate that both potassium large conductance calcium-activated channels and ATP-sensitive potassium channels significantly participate in the regulation of myometrial oxytocin-induced contractions and the activity of these channels is probably influenced by the levels of oestrogens and gestagens.

  14. Importance of large conductance calcium-activated potassium channels (BKCa) in interleukin-1b-induced adhesion of monocytes to endothelial cells.

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    Burgazli, K M; Venker, C J; Mericliler, M; Atmaca, N; Parahuleva, M; Erdogan, A

    2014-01-01

    The present study investigated the role of the large conductance calcium-activated potassium channels (BKCa) in interleukin-1b (IL-1b) induced inflammation. Human umbilical vein endothelial cells (HUVECs) were isolated and cultured. Endothelial cell membrane potential measurements were accomplished using the fluorescent dye DiBAC4(3). The role of BKCa was assessed using iberiotoxin, a highly selective BKCa inhibitor. Changes in the calcium intracellular calcium were investigated using Fura-2-AM imaging. Fluorescent dyes DCF-AM and DAF-AM were further used in order to measure the formation of reactive oxygen species (ROS) and nitric oxide (NO) synthesis, respectively. Endothelial cell adhesion tests were conducted with BCECF-AM adhesion assay and tritium thymidine uptake using human monocytic cells (U937). Expression of cellular adhesion molecules (ICAM-1, VCAM-1) was determined by flow cytometer. Interleukin-1b induced a BKCa dependent hyperpolarization of HUVECs. This was followed by an increase in the intracellular calcium concentration. Furthermore, IL-1b significantly increased the synthesis of NO and ROS. The increase of intracellular calcium, radicals and NO resulted in a BKCa dependent adhesion of monocytes to HUVECs. Endothelial cells treated with IL-1b expressed both ICAM-1 and VCAM-1 in significantly higher amounts as when compared to controls. It was further shown that the cellular adhesion molecules ICAM-1 and VCAM-1 were responsible for the BKCa-dependent increase in cellular adhesion. Additionally, inhibition of the NADPH oxidase with DPI led to a significant downregulation of IL-1b-induced expression of ICAM and VCAM, as well as inhibition of eNOS by L-NMMA, and intracellular calcium by BAPTA. Activation of the endothelial BKCa plays an important role in the IL-1b-induced monocyte adhesion to endothelial cells.

  15. Activation of TRPV2 and BKCa channels by the LL-37 enantiomers stimulates calcium entry and migration of cancer cells.

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    Gambade, Audrey; Zreika, Sami; Guéguinou, Maxime; Chourpa, Igor; Fromont, Gaëlle; Bouchet, Ana Maria; Burlaud-Gaillard, Julien; Potier-Cartereau, Marie; Roger, Sébastien; Aucagne, Vincent; Chevalier, Stéphan; Vandier, Christophe; Goupille, Caroline; Weber, Günther

    2016-04-26

    Expression of the antimicrobial peptide hCAP18/LL-37 is associated to malignancy in various cancer forms, stimulating cell migration and metastasis. We report that LL-37 induces migration of three cancer cell lines by activating the TRPV2 calcium-permeable channel and recruiting it to pseudopodia through activation of the PI3K/AKT pathway. Ca2+ entry through TRPV2 cooperated with a K+ efflux through the BKCa channel. In a panel of human breast tumors, the expression of TRPV2 and LL-37 was found to be positively correlated. The D-enantiomer of LL-37 showed identical effects as the L-peptide, suggesting that no binding to a specific receptor was involved. LL-37 attached to caveolae and pseudopodia membranes and decreased membrane fluidity, suggesting that a modification of the physical properties of the lipid membrane bilayer was the underlying mechanism of its effects.

  16. The levosimendan metabolite OR-1896 elicits vasodilation by activating the KATP and BKCa channels in rat isolated arterioles

    Science.gov (United States)

    Erdei, Nóra; Papp, Zoltán; Pollesello, Piero; Édes, István; Bagi, Zsolt

    2006-01-01

    We characterized the vasoactive effects of OR-1896, the long-lived metabolite of the inodilator levosimendan, in coronary and skeletal muscle microvessels. The effect of OR-1896 on isolated, pressurized (80 mmHg) rat coronary and gracilis muscle arteriole (∼150 μm) diameters was investigated by videomicroscopy. OR-1896 elicited concentration-dependent (1 nM–10 μM) dilations in coronary (maximal dilation: 66±6%, relative to that in Ca2+-free solutions; pD2: 7.16±0.42) and gracilis muscle arterioles (maximal dilation: 73±4%; pD2: 6.71±0.42), these dilations proving comparable to those induced by levosimendan (1 nM–10 μM) in coronary (maximal dilation: 83±6%; pD2: 7.06±0.14) and gracilis muscle arterioles (maximal dilation: 73±12%; pD2: 7.05±0.1). The maximal dilations in response to OR-1896 were significantly (P<0.05) attenuated by the nonselective K+ channel inhibitor tetraethylammonium (1 mM) in coronary (to 34±9%) and gracilis muscle arterioles (to 28±6%). Glibenclamide (5 or 10 μM), a selective ATP-sensitive K+ channel (KATP) blocker, elicited a greater reduction of OR-1896-induced dilations in skeletal muscle arterioles than in coronary microvessels. Conversely, the selective inhibition of the large conductance Ca2+-activated K+ channels (BKCa) with iberiotoxin (100 nM) significantly reduced the OR-1896-induced maximal dilation in coronary arterioles (to 21±6%), but was ineffective in skeletal muscle arterioles (72±8%). Accordingly, OR-1896 elicits a substantial vasodilation in coronary and skeletal muscle arterioles, by activating primarily BKCa and KATP channels, respectively, and it is suggested that OR-1896 contributes to the long-term hemodynamic effects of levosimendan. PMID:16715115

  17. Kaempferol stimulates large conductance Ca2+-activated K+ (BKCa) channels in human umbilical vein endothelial cells via a cAMP/PKA-dependent pathway

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    Xu, Y C; Leung, G P H; Wong, P Y D; Vanhoutte, P M; Man, R Y K

    2008-01-01

    Background and purpose: Kaempferol has been shown to possess a vasodilator effect but its mechanism of action remains unclear. In this study, experiments were carried out to study the effect of kaempferol on K+ channels in endothelial cells. Experimental approach: K+ channel activities in human umbilical vein endothelial cells (HUVECs) were studied by conventional whole cell and cell-attached patch-clamp electrophysiology. Key results: Kaempferol stimulated an outward-rectifying current in HUVECs in a dose-dependent manner with an EC50 value of 2.5±0.02 μM. This kaempferol-induced current was abolished by large conductance Ca2+-activated K+ (BKCa) channel blockers, such as iberiotoxin (IbTX) and charybdotoxin (ChTX), whereas the small conductance Ca2+-activated K+ (SKCa) channel blocker, apamin, and the voltage-dependent K+ (KV) channel blocker, 4-aminopyridine, had no effect. Cell-attached patches demonstrated that kaempferol increased the open probability of BkCa channels in HUVECs. Clamping intracellular Ca2+ did not prevent kaempferol-induced increases in outward current. In addition, the kaempferol-induced current was diminished by the adenylyl cyclase inhibitor SQ22536, the cAMP antagonist Rp-8-Br-cAMP and the PKA inhibitor KT5720, but was not affected by the guanylyl cyclase inhibitor ODQ, the cGMP antagonist Rp-8-Br-cGMP and the PKG inhibitor KT5823. The activation of BKCa channels by kaempferol caused membrane hyperpolarization of HUVECs. Conclusion and implications: These results demonstrate that kaempferol activates the opening of BKCa channels in HUVECs via a cAMP/PKA-dependent pathway, resulting in membrane hyperpolarization. This mechanism may partly account for the vasodilator effects of kaempferol. PMID:18493242

  18. Melatonin mediates vasodilation through both direct and indirect activation of BKCa channels.

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    Zhao, T; Zhang, H; Jin, C; Qiu, F; Wu, Y; Shi, L

    2017-10-01

    Melatonin, synthesized primarily by the pineal gland, is a neuroendocrine hormone with high membrane permeability. The vascular effects of melatonin, including vasoconstriction and vasodilation, have been demonstrated in numerous studies. However, the mechanisms underlying these effects are not fully understood. Large-conductance Ca 2+ -activated K + (BK Ca ) channels are expressed broadly on smooth muscle cells and play an important role in vascular tone regulation. This study explored the mechanisms of myocyte BK Ca channels and endothelial factors underlying the action of melatonin on the mesenteric arteries (MAs). Vascular contractility and patch-clamp studies were performed on myocytes of MAs from Wistar rats. Melatonin induced significant vasodilation on MAs. In the presence of N ω -nitro-l-arginine methyl ester (l-NAME), a potent endothelial oxide synthase (eNOS) inhibitor, melatonin elicited concentration-dependent relaxation, with lowered pIC 50 The effect of melatonin was significantly attenuated in the presence of BK Ca channel blocker iberiotoxin or MT1/MT2 receptor antagonist luzindole in both (+) l-NAME and (-) l-NAME groups. In the (+) l-NAME group, iberiotoxin caused a parallel rightward shift of the melatonin concentration-relaxation curve, with pIC 50 lower than that of luzindole. Both inside-out and cell-attached patch-clamp recordings showed that melatonin significantly increased the open probability, mean open time and voltage sensitivity of BK Ca channels. In a cell-attached patch-clamp configuration, the melatonin-induced enhancement of BK Ca channel activity was significantly suppressed by luzindole. These findings indicate that in addition to the activation of eNOS, melatonin-induced vasorelaxation of MAs is partially attributable to its direct (passing through the cell membrane) and indirect (via MT1/MT2 receptors) activation of the BK Ca channels on mesenteric arterial myocytes. © 2017 Society for Endocrinology.

  19. Mitochondrial BKCa channels contribute to protection of cardiomyocytes isolated from chronically hypoxic rats

    Czech Academy of Sciences Publication Activity Database

    Borchert, Gudrun H.; Yang, Ch.; Kolář, František

    2011-01-01

    Roč. 300, č. 2 (2011), H507-H513 ISSN 0363-6135 R&D Projects: GA ČR(CZ) GA305/07/1008; GA AV ČR IAA500110804 Keywords : chronic hypoxia * ventricular myocytes * metabolic inhibition * cell viability * potassium channels Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 3.708, year: 2011

  20. Pharmacological activation of mitochondrial BKCa channels protects isolated cardiomyocytes against simulated reperfusion-induced injury

    Czech Academy of Sciences Publication Activity Database

    Borchert, Gudrun H.; Hlaváčková, Markéta; Kolář, František

    2013-01-01

    Roč. 238, č. 2 (2013), s. 233-241 ISSN 1535-3702 R&D Projects: GA AV ČR(CZ) IAA500110804; GA ČR(CZ) GAP303/12/1162 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : potassium channels * cardiomyocytes * mitochondria * ischemia/ reperfusion * cytoprotection * reactive oxygen species Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 2.226, year: 2013

  1. The levosimendan metabolite OR-1896 elicits vasodilation by activating the K(ATP) and BK(Ca) channels in rat isolated arterioles.

    Science.gov (United States)

    Erdei, Nóra; Papp, Zoltán; Pollesello, Piero; Edes, István; Bagi, Zsolt

    2006-07-01

    1. We characterized the vasoactive effects of OR-1896, the long-lived metabolite of the inodilator levosimendan, in coronary and skeletal muscle microvessels. 2. The effect of OR-1896 on isolated, pressurized (80 mmHg) rat coronary and gracilis muscle arteriole (approximately 150 microm) diameters was investigated by videomicroscopy. 3. OR-1896 elicited concentration-dependent (1 nM-10 microM) dilations in coronary (maximal dilation: 66+/-6%, relative to that in Ca2+-free solutions; pD2: 7.16+/-0.42) and gracilis muscle arterioles (maximal dilation: 73+/-4%; pD2: 6.71+/-0.42), these dilations proving comparable to those induced by levosimendan (1 nM-10 microM) in coronary (maximal dilation: 83+/-6%; pD2: 7.06+/-0.14) and gracilis muscle arterioles (maximal dilation: 73+/-12%; pD2: 7.05+/-0.1). 4. The maximal dilations in response to OR-1896 were significantly (P<0.05) attenuated by the nonselective K+ channel inhibitor tetraethylammonium (1 mM) in coronary (to 34+/-9%) and gracilis muscle arterioles (to 28+/-6%). 5. Glibenclamide (5 or 10 microM), a selective ATP-sensitive K+ channel (KATP) blocker, elicited a greater reduction of OR-1896-induced dilations in skeletal muscle arterioles than in coronary microvessels. 6. Conversely, the selective inhibition of the large conductance Ca2+-activated K+ channels (BK(Ca)) with iberiotoxin (100 nM) significantly reduced the OR-1896-induced maximal dilation in coronary arterioles (to 21+/-6%), but was ineffective in skeletal muscle arterioles (72+/-8%). 7. Accordingly, OR-1896 elicits a substantial vasodilation in coronary and skeletal muscle arterioles, by activating primarily BK(Ca) and K(ATP) channels, respectively, and it is suggested that OR-1896 contributes to the long-term hemodynamic effects of levosimendan.

  2. Involvement of BKCa and KV potassium channels in cAMP-induced vasodilation: their insufficient function in genetic hypertension

    Czech Academy of Sciences Publication Activity Database

    Pintérová, Mária; Behuliak, Michal; Kuneš, Jaroslav; Zicha, Josef

    2014-01-01

    Roč. 63, č. 3 (2014), s. 275-285 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA305/09/0336; GA ČR(CZ) GAP304/12/0259; GA MŠk(CZ) 1M0510 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : isoprenaline * cAMP * potassium channels * calcium channels Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 1.293, year: 2014

  3. Brief Daily Episode of Normoxia Inhibits Cardioprotection Conferred by Chronic Continuous Hypoxia. Role of Oxidative Stress and BKCa Channels

    Czech Academy of Sciences Publication Activity Database

    Neckář, Jan; Borchert, Gudrun H.; Hloušková, P.; Míčová, P.; Nováková, O.; Novák, F.; Hroch, M.; Papoušek, František; Ošťádal, Bohuslav; Kolář, František

    2013-01-01

    Roč. 19, č. 39 (2013), s. 6880-6889 ISSN 1381-6128 R&D Projects: GA AV ČR(CZ) IAAX01110901; GA ČR(CZ) GA305/07/0875; GA ČR(CZ) GAP303/12/1162 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : chronic continuous hypoxia * reoxygenation * ischemia/reperfusion * myocardial infarction * potassium channels * oxidative stress Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 3.288, year: 2013

  4. Calycosin and Formononetin Induce Endothelium-Dependent Vasodilation by the Activation of Large-Conductance Ca2+-Activated K+ Channels (BKCa

    Directory of Open Access Journals (Sweden)

    Hisa Hui Ling Tseng

    2016-01-01

    Full Text Available Calycosin and formononetin are two structurally similar isoflavonoids that have been shown to induce vasodilation in aorta and conduit arteries, but study of their actions on endothelial functions is lacking. Here, we demonstrated that both isoflavonoids relaxed rat mesenteric resistance arteries in a concentration-dependent manner, which was reduced by endothelial disruption and nitric oxide synthase (NOS inhibition, indicating the involvement of both endothelium and vascular smooth muscle. In addition, the endothelium-dependent vasodilation, but not the endothelium-independent vasodilation, was blocked by BKCa inhibitor iberiotoxin (IbTX. Using human umbilical vein endothelial cells (HUVECs as a model, we showed calycosin and formononetin induced dose-dependent outwardly rectifying K+ currents using whole cell patch clamp. These currents were blocked by tetraethylammonium chloride (TEACl, charybdotoxin (ChTX, or IbTX, but not apamin. We further demonstrated that both isoflavonoids significantly increased nitric oxide (NO production and upregulated the activities and expressions of endothelial NOS (eNOS and neuronal NOS (nNOS. These results suggested that calycosin and formononetin act as endothelial BKCa activators for mediating endothelium-dependent vasodilation through enhancing endothelium hyperpolarization and NO production. Since activation of BKCa plays a role in improving behavioral and cognitive disorders, we suggested that these two isoflavonoids could provide beneficial effects to cognitive disorders through vascular regulation.

  5. [β-estradiol activates BK(Ca) in mesenteric artery smooth muscle cells of post-menopause women].

    Science.gov (United States)

    Cheng, Jun; Zeng, Xiao-Rong; Li, Peng-Yun; Lu, Ting-Ting; Tan, Xiao-Qiu; Wen, Jing; Yang, Yan

    2012-04-25

    The aim of the present study was to study the effect of β-estradiol (β-E(2)) on the large-conductance Ca(2+)-activated potassium (BK(Ca)) channel in mesenteric artery smooth muscle cells (SMCs). The mesenteric arteries were obtained from post-menopause female patients with abdominal surgery, and the SMCs were isolated from the arteries using an enzymatic disassociation. According to the sources, the SMCs were divided into non-hypertension (NH) and essential hypertension (EH) groups. Single channel patch clamp technique was used to investigate the effect of β-E(2) and ICI 182780 (a specific blocker of estrogen receptor) on BK(Ca) in the SMCs. The results showed the opening of BK(Ca) in the SMCs was voltage and calcium dependent, and could be blocked by IbTX. β-E(2) (100 μmol/L) significantly increased open probability (Po) of BK(Ca) in both NH and EH groups. After β-E(2) treatment, NH group showed higher Po of BK(Ca) compared with EH group. ICI 182780 could inhibit the activating effect of β-E(2) on BK(Ca) in no matter NH or EH groups. These results suggest β-E(2) activates BK(Ca) in mesenteric artery SMCs from post-menopause women via estrogen receptor, but hypertension may decline the activating effect of β-E(2) on BK(Ca).

  6. Resveratrol attenuates cortical neuron activity: roles of large conductance calcium-activated potassium channels and voltage-gated sodium channels.

    Science.gov (United States)

    Wang, Ya-Jean; Chan, Ming-Huan; Chen, Linyi; Wu, Sheng-Nan; Chen, Hwei-Hisen

    2016-05-21

    Resveratrol, a phytoalexin found in grapes and red wine, exhibits diverse pharmacological activities. However, relatively little is known about whether resveratrol modulates the ion channels in cortical neurons. The large-conductance calcium-activated potassium channels (BKCa) and voltage-gated sodium channels were expressed in cortical neurons and play important roles in regulation of neuronal excitability. The present study aimed to determine the effects of resveratrol on BKCa currents and voltage-gated sodium currents in cortical neurons. Resveratrol concentration-dependently increased the current amplitude and the opening activity of BKCa channels, but suppressed the amplitude of voltage-gated sodium currents. Similar to the BKCa channel opener NS1619, resveratrol decreased the firing rate of action potentials. In addition, the enhancing effects of BKCa channel blockers tetraethylammonium (TEA) and paxilline on action potential firing were sensitive to resveratrol. Our results indicated that the attenuation of action potential firing rate by resveratrol might be mediated through opening the BKCa channels and closing the voltage-gated sodium channels. As BKCa channels and sodium channels are critical molecular determinants for seizure generation, our findings suggest that regulation of these two channels in cortical neurons probably makes a considerable contribution to the antiseizure activity of resveratrol.

  7. Preliminary Studies of Acute Cadmium Administration Effects on the Calcium-Activated Potassium (SKCa and BKCa) Channels and Na+/K+-ATPase Activity in Isolated Aortic Rings of Rats.

    Science.gov (United States)

    Vassallo, Dalton V; Almenara, Camila C P; Broseghini-Filho, Gilson Brás; Teixeira, Ariane Calazans; da Silva, David Chaves F; Angeli, Jhuli K; Padilha, Alessandra S

    2017-09-13

    Cadmium is an environmental pollutant closely linked with cardiovascular diseases that seems to involve endothelium dysfunction and reduced nitric oxide (NO) bioavailability. Knowing that NO causes dilatation through the activation of potassium channels and Na + /K + -ATPase, we aimed to determine whether acute cadmium administration (10 μM) alters the participation of K + channels, voltage-activated calcium channel, and Na + /K + -ATPase activity in vascular function of isolated aortic rings of rats. Cadmium did not modify the acetylcholine-induced relaxation. After L-NAME addition, the relaxation induced by acetylcholine was abolished in presence or absence of cadmium, suggesting that acutely, this metal did not change NO release. However, tetraethylammonium (a nonselective K + channels blocker) reduced acetylcholine-induced relaxation but this effect was lower in the preparations with cadmium, suggesting a decrease of K + channels function in acetylcholine response after cadmium incubation. Apamin (a selective blocker of small Ca 2+ -activated K + channels-SK Ca ), iberiotoxin (a selective blocker of large-conductance Ca 2+ -activated K + channels-BK Ca ), and verapamil (a blocker of calcium channel) reduced the endothelium-dependent relaxation only in the absence of cadmium. Finally, cadmium decreases Na + /K + -ATPase activity. Our results provide evidence that the cadmium acute incubation unaffected the calcium-activated potassium channels (SK Ca and BK Ca ) and voltage-calcium channels on the acetylcholine vasodilatation. In addition, acute cadmium incubation seems to reduce the Na + /K + -ATPase activity.

  8. Opening of calcium-activated potassium channels improves long-term left-ventricular function after coronary artery occlusion in mice

    NARCIS (Netherlands)

    Behmenburg, Friederike; Hölscher, Nina; Flögel, Ulrich; Hollmann, Markus W.; Heinen, André; Huhn, Ragnar

    2017-01-01

    Background: Opening of mitochondrial calcium-activated potassium channels (BKCa) reduces infarct size after myocardial ischemia/reperfusion injury (I/R). It is unknown if targeting BKCa-channels improves cardiac performance in the long-term after I/R. Methods: Experiments were conducted in

  9. Localization of large conductance calcium-activated potassium channels and their effect on calcitonin gene-related peptide release in the rat trigemino-neuronal pathway

    DEFF Research Database (Denmark)

    Wulf-Johansson, H.; Amrutkar, D.V.; Hay-Schmidt, Anders

    2010-01-01

    Large conductance calcium-activated potassium (BK(Ca)) channels are membrane proteins contributing to electrical propagation through neurons. Calcitonin gene-related peptide (CGRP) is a neuropeptide found in the trigeminovascular system (TGVS). Both BK(Ca) channels and CGRP are involved in migrai...

  10. Direct effect of chronic hypoxia in suppressing large conductance Ca(2+)-activated K(+) channel activity in ovine uterine arteries via increasing oxidative stress.

    Science.gov (United States)

    Hu, Xiang-Qun; Huang, Xiaohui; Xiao, Daliao; Zhang, Lubo

    2016-01-15

    Chronic hypoxia has a direct effect in down-regulating the BKCa channel β1 subunit and inhibiting the BKCa channel activity in uterine arteries of pregnant sheep. Oxidative stress plays a causal role in hypoxia-mediated suppression of BKCa channel function. The steroid hormone-induced effect on BKCa channels is a target of hypoxia-mediated oxidative stress. Inhibition of oxidative stress ameliorates the adverse effect of hypoxia both ex vivo and in vivo in pregnant sheep exposed to long-term high-altitude hypoxia. Our findings provide novel evidence of a causative role of oxidative stress in hypoxia-mediated inhibition of the BKCa channel activity in uterine arteries and new insights in understanding and alleviating pregnancy complications associated with gestational hypoxia such as pre-eclampsia and fetal growth restriction. Uterine arteries of pregnant sheep acclimatized to long-term high-altitude hypoxia were associated with a decrease in large-conductance Ca(2+)-activated K(+) (BKCa) channel activity. The present study tested the hypothesis that prolonged hypoxia has a direct effect in suppressing BKCa channel activity by increasing oxidative stress. Uterine arteries were isolated from non-pregnant and near-term (∼142 days) pregnant sheep, and were treated ex vivo with 21.0 or 10.5% O2 for 48 h. The hypoxia treatment significantly increased the production of reactive oxygen species in uterine arteries, which was blocked by N-acetylcysteine. In uterine arteries of pregnant sheep, hypoxia significantly inhibited BKCa channel current density, decreased NS1619-induced relaxations and increased pressure-dependent tone, which were annulled by N-acetylcysteine. In accordance, hypoxia resulted in down-regulation of BKCa channel β1 subunit, which was restored in the presence of N-acetylcysteine. In addition, the N-acetylcysteine treatment significantly increased BKCa channel β1 subunit abundance and BKCa channel current density in uterine arteries from pregnant

  11. Probing the structure-function relationship of alpha-latrotoxin-formed channels with antibodies and pronase.

    Science.gov (United States)

    Chanturiya, A N; Nikolaenko, A N; Shatursky OYa; Lishko, V K

    1996-10-01

    The major toxic component of black widow spider (Latrodectus mactans tredecimguttatus) venom, alpha-latrotoxin, is known to form ionic channels in different membranes. In order to probe the extramembrane domains of alpha-latrotoxin molecule, alpha-latrotoxin channels in planar lipid membrane were treated with antibodies to latrotoxin or with pronase added to different sides of the membrane. It was found that antibody addition to the same side as the toxin (cis) decreased channel conductance only at positive potentials across the membrane. In contrast, trans side addition of antibodies changed the channel conductance at both positive and negative potentials: at positive potential conductance first slightly increased then decreased by more then 50%; at negative potential it decreased much more quickly, to only about 20% of the initial value. No dependence on membrane potential was found for pronase treatment of incorporated channels. For both cis and trans application of pronase, channel selectivity for Ca2+, Mg2+, Ba2+ and K+, Na+, Li+ ions did not change significantly but Cd2+ block was decreased. Trans pronase treatment also resulted in some rectification of I/V curves and an increase in channel conductance. We interpret these findings as evidence that alpha-latrotoxin channel has protruding parts on both sides of the membrane and that its conformation in the membrane depends on membrane potential.

  12. Effects of large conductance Ca(2+)-activated K(+) channels on nitroglycerin-mediated vasorelaxation in humans

    DEFF Research Database (Denmark)

    Gruhn, Nicolai; Boesgaard, Søren; Eiberg, Jonas

    2002-01-01

    Nitric oxide (NO)-induced vasorelaxation and the regulation of endothelial superoxide anion levels is partly mediated by vascular large conductance Ca(2+)-activated K(+) (BK(Ca)) channels. Nitroglycerin acts through the release of NO and its effect is modulated by changes in endothelial superoxide...... levels. This study examines the effect of BK(Ca) channel blockade on nitroglycerin-induced vasorelaxation in human arterial and venous vascular segments and whether responses to BK(Ca) channel blockade are influenced by the development of venous nitroglycerin tolerance. Dose-relaxation curves...... in human venous nitroglycerin tolerance development....

  13. Coupled channel alpha decay theory for even- and odd-mass light and heavy nuclei

    International Nuclear Information System (INIS)

    Rauscher, E.A.

    1978-02-01

    Four major approaches to the theoretical calculation of alpha decay widths were examined for light and heavy, even- and odd-mass nuclei. Application of the microscopic shell model rate theory as well as macroscopic models utilizing the coupled-channel formalism were studied. Use of the R-matrix and S-matrix theories have been applied in order to overcome problems involving dependency on the connection radius and nuclear potential parameters of the relative and absolute alpha decay widths. 105 references

  14. Feasibility Studies of Alpha-Channeling in Mirror Machines

    International Nuclear Information System (INIS)

    Zhmoginov, A.I.; Fisch, N.J.

    2010-01-01

    The linear magnetic trap is an attractive concept both for fusion reactors and for other plasma applications due to its relative engineering simplicity and high-beta operation. Applying the α-channeling technique to linear traps, such as mirror machines, can benefit this concept by efficiently redirecting α particle energy to fuel ion heating or by otherwise sustaining plasma confinement, thus increasing the effective fusion reactivity. To identify waves suitable for α-channeling a rough optimization of the energy extraction rate with respect to the wave parameters is performed. After the optimal regime is identified, a systematic search for modes with similar parameters in mirror plasmas is performed, assuming quasi-longitudinal or quasi-transverse wave propagation. Several modes suitable for α particle energy extraction are identified for both reactor designs and for proof- of-principle experiments.

  15. Developmental regulation of expression of the alpha 1 and alpha 2 subunits mRNAs of the voltage-dependent calcium channel in a differentiating myogenic cell line.

    Science.gov (United States)

    Varadi, G; Orlowski, J; Schwartz, A

    1989-07-03

    The voltage-dependent calcium channel (VDCC) in skeletal muscle probably plays a key role in transducing membrane charge movement to the calcium release channel. We report here that the expression of VDCC alpha 1 and alpha 2 mRNAs is developmentally regulated in differentiating C2C12 myogenic cells. The alpha 1 mRNA is not detectable in the myoblast form of C2C12 cells while its expression is induced 20-fold in differentiated myotubes. In contrast, the alpha 2 mRNA is weakly expressed in myoblasts but is also induced upon myogenic differentiation.

  16. Effects of large conductance Ca(2+)-activated K(+) channels on nitroglycerin-mediated vasorelaxation in humans

    DEFF Research Database (Denmark)

    Gruhn, Nicolai; Boesgaard, Søren; Eiberg, Jonas

    2002-01-01

    Nitric oxide (NO)-induced vasorelaxation and the regulation of endothelial superoxide anion levels is partly mediated by vascular large conductance Ca(2+)-activated K(+) (BK(Ca)) channels. Nitroglycerin acts through the release of NO and its effect is modulated by changes in endothelial superoxide...... levels. This study examines the effect of BK(Ca) channel blockade on nitroglycerin-induced vasorelaxation in human arterial and venous vascular segments and whether responses to BK(Ca) channel blockade are influenced by the development of venous nitroglycerin tolerance. Dose-relaxation curves...... to nitroglycerin (10(-10)-10(-4) M) were obtained in segments of the saphenous vein and the left mammary artery. Studies were performed with and without pre-incubation with the BK(Ca) channel blocker iberiotoxin (10(-7) M) and venous tolerance to nitroglycerin were induced by a 24-h i.v. infusion (0.5 microg...

  17. Beneficial Effect of Intermedin 1-53 in Septic Shock Rats: Contributions of Rho Kinase and BKCA Pathway-Mediated Improvement in Cardiac Function.

    Science.gov (United States)

    Zhu, Yu; Wu, Huiling; Wu, Yue; Zhang, Jie; Peng, Xiaoyong; Zang, Jiatao; Xiang, Xinming; Liu, Liangming; Li, Tao

    2016-11-01

    Intermedin (IMD) is a calcitonin gene-related peptide shown to have a protective effect on myocardial function in ischemia-reperfusion injury. Whether IMD has beneficial effect in severe sepsis and septic shock (and its underlying mechanisms) is not known. We induced septic shock using cecal ligation and puncture (CLP). We focused on the potential beneficial effect of IMD1-53 on cardiac papillary muscle and cardiomyocytes against septic shock and its relationship with the protection of cardiac function. Early (immediately after CLP) and late (12 h after CLP) administration of IMD1-53 (0.5 μg/kg) improved animal survival significantly, increased cardiac contractility and function, and improved tissue perfusion and oxygen delivery. The effect of early administration of IMD1-53 was better than that of late administration. The Rho kinase/TnI and BKCa pathways participated in the protective effect of IMD1-53 on cardiac function in septic rats. An inhibitor of Rho kinase (Y-27632) or a BKCa opener (NS1619) abolished the protective effect of IMD1-53 on cardiac function. IMD1-53 increased expression of Rho kinase in cardiac muscle and inhibited TnI phosphorylation. IMD1-53 inhibited currents in BKCa channels and intracellular calcium concentration in cardiomyocytes. IMD1-53 is beneficial against severe sepsis/septic shock. IMD1-53 can improve cardiac contractility and cardiac function significantly, and then improve tissue perfusion and oxygen delivery. Rho kinase and the BKCa pathways have important roles in these effects. These findings provide a new treatment strategy for severe sepsis with cardiac dysfunction.

  18. Coupled channel folding model description of {alpha} scattering from {sup 9}Be

    Energy Technology Data Exchange (ETDEWEB)

    Roy, S.; Chatterjee, J.M.; Majumdar, H. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700064 (India); Datta, S.K. [Nuclear Science Centre, P.O.10502, New Delhi 110067 (India); Banerjee, S.R. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Calcutta 700064 (India); Chintalapudi, S.N. [Inter-University Consortium, Department of Atomic Energy Facilities, Bidhannagar, Calcutta 700064 (India)

    1995-09-01

    Alpha scattering from {sup 9}Be at {ital E}{sub {alpha}}= 65 MeV is described in the coupled channel framework with phenomenological as well as folded potentials. The multipole components of the deformed density of {sup 9}Be are derived from Nilsson model wave functions. Reasonably good agreements are obtained for the angular distributions of 3/2{sup {minus}}(g.s.) and 5/2{sup {minus}}(2.43 MeV) states of the ground state band with folded potentials. The deformation predicted by the model corroborates with that derived from the phenomenological analysis with potentials of different geometries.

  19. Structure of functional Staphylococcus aureus alpha-hemolysin channels in tethered bilayer lipid membranes.

    Science.gov (United States)

    McGillivray, Duncan J; Valincius, Gintaras; Heinrich, Frank; Robertson, Joseph W F; Vanderah, David J; Febo-Ayala, Wilma; Ignatjev, Ilja; Lösche, Mathias; Kasianowicz, John J

    2009-02-18

    We demonstrate a method for simultaneous structure and function determination of integral membrane proteins. Electrical impedance spectroscopy shows that Staphylococcus aureus alpha-hemolysin channels in membranes tethered to gold have the same properties as those formed in free-standing bilayer lipid membranes. Neutron reflectometry provides high-resolution structural information on the interaction between the channel and the disordered membrane, validating predictions based on the channel's x-ray crystal structure. The robust nature of the membrane enabled the precise localization of the protein within 1.1 A. The channel's extramembranous cap domain affects the lipid headgroup region and the alkyl chains in the outer membrane leaflet and significantly dehydrates the headgroups. The results suggest that this technique could be used to elucidate molecular details of the association of other proteins with membranes and may provide structural information on domain organization and stimuli-responsive reorganization for transmembrane proteins in membrane mimics.

  20. CANALPH-3: a portable three-channel alpha spectrometer for measuring the daughter products of radon and thoron

    International Nuclear Information System (INIS)

    Carson, D.W.

    1979-07-01

    A portable three-channel alpha spectrometer for the measurment of radon and thoron daughters in uranium mines or homes is described. The computer programs for analysing the data to give the working levels of radon and thoron by both the alpha spectrometric and modified Kusnetz methods are included along with some typical results

  1. Gating at the mouth of the acetylcholine receptor channel: energetic consequences of mutations in the alphaM2-cap.

    Directory of Open Access Journals (Sweden)

    Pallavi A Bafna

    2008-06-01

    Full Text Available Gating of nicotinic acetylcholine receptors from a C(losed to an O(pen conformation is the initial event in the postsynaptic signaling cascade at the vertebrate nerve-muscle junction. Studies of receptor structure and function show that many residues in this large, five-subunit membrane protein contribute to the energy difference between C and O. Of special interest are amino acids located at the two transmitter binding sites and in the narrow region of the channel, where CO gating motions generate a lowhigh change in the affinity for agonists and in the ionic conductance, respectively. We have measured the energy changes and relative timing of gating movements for residues that lie between these two locations, in the C-terminus of the pore-lining M2 helix of the alpha subunit ('alphaM2-cap'. This region contains a binding site for non-competitive inhibitors and a charged ring that influences the conductance of the open pore. alphaM2-cap mutations have large effects on gating but much smaller effects on agonist binding, channel conductance, channel block and desensitization. Three alphaM2-cap residues (alphaI260, alphaP265 and alphaS268 appear to move at the outset of channel-opening, about at the same time as those at the transmitter binding site. The results suggest that the alphaM2-cap changes its secondary structure to link gating motions in the extracellular domain with those in the channel that regulate ionic conductance.

  2. Direct and remote modulation of L-channels in chromaffin cells: distinct actions on alpha1C and alpha1D subunits?

    Science.gov (United States)

    Baldelli, Pietro; Hernández-Guijo, Jesus Miguel; Carabelli, Valentina; Novara, Monica; Cesetti, Tiziana; Andrés-Mateos, Eva; Montiel, Carmen; Carbone, Emilio

    2004-02-01

    Understanding precisely the functioning of voltage-gated Ca2+ channels and their modulation by signaling molecules will help clarifying the Ca(2+)-dependent mechanisms controlling exocytosis in chromaffin cells. In recent years, we have learned more about the various pathways through which Ca2+ channels can be up- or down-modulated by hormones and neurotransmitters and how these changes may condition chromaffin cell activity and catecolamine release. Recently, the attention has been focused on the modulation of L-channels (CaV 1), which represent the major Ca2+ current component in rat and human chromaffin cells. L-channels are effectively inhibited by the released content of secretory granules or by applying mixtures of exogenous ATP, opioids, and adrenaline through the activation of receptor-coupled G proteins. This unusual inhibition persists in a wide range of potentials and results from a direct (membrane-delimited) interaction of G protein subunits with the L-channels co-localized in membrane microareas. Inhibition of L-channels can be reversed when the cAMP/PKA pathway is activated by membrane permeable cAMP analog or when cells are exposed to isoprenaline (remote action), suggesting the existence of parallel and opposite effects on L-channel gating by distinctly activated membrane autoreceptors. Here, the authors review the molecular components underlying these two opposing signaling pathways and present new evidence supporting the presence of two L-channel types in rat chromaffin cells (alpha1C and alpha1D), which open new interesting issues concerning Ca(2+)-channel modulation. In light of recent findings on the regulation of exocytosis by Ca(2+)-channel modulation, the authors explore the possible role of L-channels in the autocontrol of catecholamine release.

  3. Identification and characterization of Ca2+-activated K+ channels in granulosa cells of the human ovary

    Directory of Open Access Journals (Sweden)

    Berg Ulrike

    2009-04-01

    Full Text Available Abstract Background Granulosa cells (GCs represent a major endocrine compartment of the ovary producing sex steroid hormones. Recently, we identified in human GCs a Ca2+-activated K+ channel (KCa of big conductance (BKCa, which is involved in steroidogenesis. This channel is activated by intraovarian signalling molecules (e.g. acetylcholine via raised intracellular Ca2+ levels. In this study, we aimed at characterizing 1. expression and functions of KCa channels (including BKCa beta-subunits, and 2. biophysical properties of BKCa channels. Methods GCs were obtained from in vitro-fertilization patients and cultured. Expression of mRNA was determined by standard RT-PCR and protein expression in human ovarian slices was detected by immunohistochemistry. Progesterone production was measured in cell culture supernatants using ELISAs. Single channels were recorded in the inside-out configuration of the patch-clamp technique. Results We identified two KCa types in human GCs, the intermediate- (IK and the small-conductance KCa (SK. Their functionality was concluded from attenuation of human chorionic gonadotropin-stimulated progesterone production by KCa blockers (TRAM-34, apamin. Functional IK channels were also demonstrated by electrophysiological recording of single KCa channels with distinctive features. Both, IK and BKCa channels were found to be simultaneously active in individual GCs. In agreement with functional data, we identified mRNAs encoding IK, SK1, SK2 and SK3 in human GCs and proteins of IK and SK2 in corresponding human ovarian cells. Molecular characterization of the BKCa channel revealed the presence of mRNAs encoding several BKCa beta-subunits (beta2, beta3, beta4 in human GCs. The multitude of beta-subunits detected might contribute to variations in Ca2+ dependence of individual BKCa channels which we observed in electrophysiological recordings. Conclusion Functional and molecular studies indicate the presence of active IK and SK

  4. Orientation of the calcium channel beta relative to the alpha(12.2 subunit is critical for its regulation of channel activity.

    Directory of Open Access Journals (Sweden)

    Iuliia Vitko

    Full Text Available BACKGROUND: The Ca(vbeta subunits of high voltage-activated Ca(2+ channels control the trafficking and biophysical properties of the alpha(1 subunit. The Ca(vbeta-alpha(1 interaction site has been mapped by crystallographic studies. Nevertheless, how this interaction leads to channel regulation has not been determined. One hypothesis is that betas regulate channel gating by modulating movements of IS6. A key requirement for this direct-coupling model is that the linker connecting IS6 to the alpha-interaction domain (AID be a rigid structure. METHODOLOGY/PRINCIPAL FINDINGS: The present study tests this hypothesis by altering the flexibility and orientation of this region in alpha(12.2, then testing for Ca(vbeta regulation using whole cell patch clamp electrophysiology. Flexibility was induced by replacement of the middle six amino acids of the IS6-AID linker with glycine (PG6. This mutation abolished beta2a and beta3 subunits ability to shift the voltage dependence of activation and inactivation, and the ability of beta2a to produce non-inactivating currents. Orientation of Ca(vbeta with respect to alpha(12.2 was altered by deletion of 1, 2, or 3 amino acids from the IS6-AID linker (Bdel1, Bdel2, Bdel3, respectively. Again, the ability of Ca(vbeta subunits to regulate these biophysical properties were totally abolished in the Bdel1 and Bdel3 mutants. Functional regulation by Ca(vbeta subunits was rescued in the Bdel2 mutant, indicating that this part of the linker forms beta-sheet. The orientation of beta with respect to alpha was confirmed by the bimolecular fluorescence complementation assay. CONCLUSIONS/SIGNIFICANCE: These results show that the orientation of the Ca(vbeta subunit relative to the alpha(12.2 subunit is critical, and suggests additional points of contact between these subunits are required for Ca(vbeta to regulate channel activity.

  5. Alpha-helical hydrophobic polypeptides form proton-selective channels in lipid bilayers

    Science.gov (United States)

    Oliver, A. E.; Deamer, D. W.

    1994-01-01

    Proton translocation is important in membrane-mediated processes such as ATP-dependent proton pumps, ATP synthesis, bacteriorhodopsin, and cytochrome oxidase function. The fundamental mechanism, however, is poorly understood. To test the theoretical possibility that bundles of hydrophobic alpha-helices could provide a low energy pathway for ion translocation through the lipid bilayer, polyamino acids were incorporated into extruded liposomes and planar lipid membranes, and proton translocation was measured. Liposomes with incorporated long-chain poly-L-alanine or poly-L-leucine were found to have proton permeability coefficients 5 to 7 times greater than control liposomes, whereas short-chain polyamino acids had relatively little effect. Potassium permeability was not increased markedly by any of the polyamino acids tested. Analytical thin layer chromatography measurements of lipid content and a fluorescamine assay for amino acids showed that there were approximately 135 polyleucine or 65 polyalanine molecules associated with each liposome. Fourier transform infrared spectroscopy indicated that a major fraction of the long-chain hydrophobic peptides existed in an alpha-helical conformation. Single-channel recording in both 0.1 N HCl and 0.1 M KCl was also used to determine whether proton-conducting channels formed in planar lipid membranes (phosphatidylcholine/phosphatidylethanolamine, 1:1). Poly-L-leucine and poly-L-alanine in HCl caused a 10- to 30-fold increase in frequency of conductive events compared to that seen in KCl or by the other polyamino acids in either solution. This finding correlates well with the liposome observations in which these two polyamino acids caused the largest increase in membrane proton permeability but had little effect on potassium permeability. Poly-L-leucine was considerably more conductive than poly-L-alanine due primarily to larger event amplitudes and, to a lesser extent, a higher event frequency. Poly-L-leucine caused two

  6. Glycosylation of alpha(2)delta(1) subunit: a sweet talk with Ca(v)1.2 channels

    Czech Academy of Sciences Publication Activity Database

    Lazniewska, Joanna; Weiss, Norbert

    2016-01-01

    Roč. 35, č. 3 (2016), s. 239-242 ISSN 0231-5882 R&D Projects: GA ČR GA15-13556S; GA MŠk 7AMB15FR015 Institutional support: RVO:61388963 Keywords : calcium channel * Ca(v)1.2 channel * ancillary subunit * alpha(2)delta(1) subunit * glycosylation * trafficking Subject RIV: CE - Biochemistry Impact factor: 1.170, year: 2016

  7. Inactivation of gating currents of L-type calcium channels. Specific role of the alpha 2 delta subunit.

    Science.gov (United States)

    Shirokov, R; Ferreira, G; Yi, J; Ríos, E

    1998-06-01

    In studies of gating currents of rabbit cardiac Ca channels expressed as alpha 1C/beta 2a or alpha 1C/beta 2a/alpha 2 delta subunit combinations in tsA201 cells, we found that long-lasting depolarization shifted the distribution of mobile charge to very negative potentials. The phenomenon has been termed charge interconversion in native skeletal muscle (Brum, G., and E. Ríos. 1987. J. Physiol. (Camb.). 387:489-517) and cardiac Ca channels (Shirokov, R., R. Levis, N. Shirokova, and E. Ríos. 1992. J. Gen. Physiol. 99:863-895). Charge 1 (voltage of half-maximal transfer, V1/2 approximately 0 mV) gates noninactivated channels, while charge 2 (V1/2 approximately -90 mV) is generated in inactivated channels. In alpha 1C/beta 2a cells, the available charge 1 decreased upon inactivating depolarization with a time constant tau approximately 8, while the available charge 2 decreased upon recovery from inactivation (at -200 mV) with tau approximately 0.3 s. These processes therefore are much slower than charge movement, which takes charge movement and that of changes in their availability, which was even wider in the presence of alpha 2 delta, implies that charges 1 and 2 originate from separate channel modes. Because clear modal separation characterizes slow (C-type) inactivation of Na and K channels, this observation establishes the nature of voltage-dependent inactivation of L-type Ca channels as slow or C-type. The presence of the alpha 2 delta subunit did not change the V1/2 of charge 2, but sped up the reduction of charge 1 upon inactivation at 40 mV (to tau approximately 2 s), while slowing the reduction of charge 2 upon recovery (tau approximately 2 s). The observations were well simulated with a model that describes activation as continuous electrodiffusion (Levitt, D. 1989. Biophys. J. 55:489-498) and inactivation as discrete modal change. The effects of alpha 2 delta are reproduced assuming that the subunit lowers the free energy of the inactivated mode.

  8. Cloning, chromosomal localization, and functional expression of the alpha 1 subunit of the L-type voltage-dependent calcium channel from normal human heart

    NARCIS (Netherlands)

    Schultz, D; Mikala, G; Yatani, A; Engle, D B; Iles, D E; Segers, B; Sinke, R J; Weghuis, D O; Klöckner, U; Wakamori, M

    1993-01-01

    A unique structural variant of the cardiac L-type voltage-dependent calcium channel alpha 1 subunit cDNA was isolated from libraries derived from normal human heart mRNA. The deduced amino acid sequence shows significant homology to other calcium channel alpha 1 subunits. However, differences from

  9. The potassium channel Kir4.1 associates with the dystrophin-glycoprotein complex via alpha-syntrophin in glia.

    Science.gov (United States)

    Connors, Nathan C; Adams, Marvin E; Froehner, Stanley C; Kofuji, Paulo

    2004-07-02

    One of the major physiological roles of potassium channels in glial cells is to promote "potassium spatial buffering" in the central nervous system, a process necessary to maintain an optimal potassium concentration in the extracellular environment. This process requires the precise distribution of potassium channels accumulated at high density in discrete subdomains of glial cell membranes. To obtain a better understanding of how glial cells selectively target potassium channels to discrete membrane subdomains, we addressed the question of whether the glial inwardly rectifying potassium channel Kir4.1 associates with the dystrophin-glycoprotein complex (DGC). Immunoprecipitation experiments revealed that Kir4.1 is associated with the DGC in mouse brain and cultured cortical astrocytes. In vitro immunoprecipitation and pull-down assays demonstrated that Kir4.1 can bind directly to alpha-syntrophin, requiring the presence of the last three amino acids of the channel (SNV), a consensus PDZ domain-binding motif. Furthermore, Kir4.1 failed to associate with the DGC in brains from alpha-syntrophin knockout mice. These results suggest that Kir4.1 is localized in glial cells by its association with the DGC through a PDZ domain-mediated interaction with alpha-syntrophin and suggest an important role for the DGC in central nervous system physiology.

  10. Site of covalent labeling by a photoreactive batrachotoxin derivative near transmembrane segment IS6 of the sodium channel alpha subunit.

    Science.gov (United States)

    Trainer, V L; Brown, G B; Catterall, W A

    1996-05-10

    The binding site for batrachotoxin, a lipid-soluble neurotoxin acting at Na+ channel receptor site 2, was localized using a photoreactive radiolabeled batrachotoxin derivative to covalently label purified and reconstituted rat brain Na+ channels. In the presence of the brevetoxin 1 from Ptychodiscus brevis and the pyrethroid RU51049, positive allosteric enhancers of batrachotoxin binding, a protein with an apparent molecular mass of 240 kDa corresponding to the Na+ channel alpha subunit was specifically covalently labeled. The region of the alpha subunit specifically photolabeled by the photoreactive batrachotoxin derivative was identified by antibody mapping of proteolytic fragments. Even after extensive trypsinization, and anti-peptide antibody recognizing an amino acid sequence adjacent to Na+ channel transmembrane segment IS6 was able to immunoprecipitate up to 70% of the labeled peptides. Analysis of a more complete digestion with trypsin or V8 protease indicated that the batrachotoxin receptor site is formed in part by a portion of domain I. The identification of a specifically immunoprecipitated photolabeled 7.3-kDa peptide containing transmembrane segment S6 from domain I restricted the site of labeling to residues Asn-388 to Glu-429 if V8 protease digestion was complete or Leu-380 to Glu-429 if digestion was incomplete. These results implicate the S6 transmembrane region of domain I of the Na+ channel alpha subunit as an important component of the batrachotoxin receptor site.

  11. Importance of the alphaC-helix in the cyclic nucleotide binding domain for the stable channel regulation and function of cyclic nucleotide gated ion channels in Arabidopsis.

    Science.gov (United States)

    Chin, Kimberley; Moeder, Wolfgang; Abdel-Hamid, Huda; Shahinas, Dea; Gupta, Deepali; Yoshioka, Keiko

    2010-05-01

    The involvement of cyclic nucleotide gated ion channels (CNGCs) in the signal transduction of animal light and odorant perception is well documented. Although plant CNGCs have recently been revealed to mediate multiple stress responses and developmental pathways, studies that aim to elucidate their structural and regulatory properties are still very much in their infancy. The structure-function relationship of plant CNGCs was investigated here by using the chimeric Arabidopsis AtCNGC11/12 gene that induces multiple defence responses in the Arabidopsis mutant constitutive expresser of PR genes 22 (cpr22) for the identification of functionally essential residues. A genetic screen for mutants that suppress cpr22-conferred phenotypes identified over 20 novel mutant alleles in AtCNGC11/12. One of these mutants, suppressor S58 possesses a single amino acid substitution, arginine 557 to cysteine, in the alphaC-helix of the cyclic nucleotide-binding domain (CNBD). The suppressor S58 lost all cpr22 related phenotypes, such as spontaneous cell death formation under ambient temperature conditions. However, these phenotypes were recovered at 16 degrees C suggesting that the stability of channel function is affected by temperature. In silico modelling and site-directed mutagenesis analyses suggest that arginine 557 in the alphaC-helix of the CNBD is important for channel regulation, but not for basic function. Furthermore, another suppressor mutant, S136 that lacks the entire alphaC-helix due to a premature stop codon, lost channel function completely. Our data presented here indicate that the alphaC-helix is functionally important in plant CNGCs.

  12. Molecular studies of BKCa channels in intracranial arteries

    DEFF Research Database (Denmark)

    Wulf, Helle; Hay-Schmidt, Anders; Poulsen, Asser Nyander

    2008-01-01

    expression of the BK(Ca) channel in rat basilar, middle cerebral, and middle meningeal arteries by reverse transcription polymerase chain reaction (RT-PCR), quantitative real-time PCR, and Western blotting. Distribution patterns were investigated using in situ hybridization and immunofluorescence studies. RT......-PCR and quantitative real-time PCR detected the expression of the BK(Ca) channel mRNA transcript in rat basilar, middle cerebral, and middle meningeal arteries, with the transcript being expressed more abundantly in rat basilar arteries than in middle cerebral and middle meningeal arteries. Western blotting detected...... and localization of both mRNA and protein expression of the BK(Ca) channel in the smooth muscle cell layer in rat basilar, middle cerebral, and middle meningeal arteries....

  13. Apelin-13 inhibits large-conductance Ca2+-activated K+ channels in cerebral artery smooth muscle cells via a PI3-kinase dependent mechanism.

    Directory of Open Access Journals (Sweden)

    Amit Modgil

    Full Text Available Apelin-13 causes vasoconstriction by acting directly on APJ receptors in vascular smooth muscle (VSM cells; however, the ionic mechanisms underlying this action at the cellular level remain unclear. Large-conductance Ca(2+-activated K(+ (BKCa channels in VSM cells are critical regulators of membrane potential and vascular tone. In the present study, we examined the effect of apelin-13 on BK(Ca channel activity in VSM cells, freshly isolated from rat middle cerebral arteries. In whole-cell patch clamp mode, apelin-13 (0.001-1 μM caused concentration-dependent inhibition of BK(Ca in VSM cells. Apelin-13 (0.1 µM significantly decreased BK(Ca current density from 71.25 ± 8.14 pA/pF to 44.52 ± 7.10 pA/pF (n=14 cells, P<0.05. This inhibitory effect of apelin-13 was confirmed by single channel recording in cell-attached patches, in which extracellular application of apelin-13 (0.1 µM decreased the open-state probability (NPo of BK(Ca channels in freshly isolated VSM cells. However, in inside-out patches, extracellular application of apelin-13 (0.1 µM did not alter the NPo of BK(Ca channels, suggesting that the inhibitory effect of apelin-13 on BKCa is not mediated by a direct action on BK(Ca. In whole cell patches, pretreatment of VSM cells with LY-294002, a PI3-kinase inhibitor, markedly attenuated the apelin-13-induced decrease in BK(Ca current density. In addition, treatment of arteries with apelin-13 (0.1 µM significantly increased the ratio of phosphorylated-Akt/total Akt, indicating that apelin-13 significantly increases PI3-kinase activity. Taken together, the data suggest that apelin-13 inhibits BK(Ca channel via a PI3-kinase-dependent signaling pathway in cerebral artery VSM cells, which may contribute to its regulatory action in the control of vascular tone.

  14. Pertussis toxin-sensitive alpha-adrenergic modulation of voltage - dependent calcium channels in spontaneously hypertensive rats (SHR)

    Czech Academy of Sciences Publication Activity Database

    Zicha, Josef; Pintérová, Mária; Dobešová, Zdenka; Líšková, Silvia; Kuneš, Jaroslav

    2006-01-01

    Roč. 24, č. S6 (2006), s. 34-34 ISSN 0263-6352. [Scientific Meeting of the International Society of Hypertension /21./. 15.10.2006-19.10.2006, Fukuoka] R&D Projects: GA MZd(CZ) NR7786 Institutional research plan: CEZ:AV0Z50110509 Keywords : pertussis toxin * alpha adrenergic vasoconstriction * voltage-dependent calcium channels * SHR rat Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  15. Hydralazine-induced vasodilation involves opening of high conductance Ca2+-activated K+ channels

    DEFF Research Database (Denmark)

    Bang, Lone; Nielsen-Kudsk, J E; Gruhn, N

    1998-01-01

    The purpose of this study was to investigate whether high conductance Ca2+-activated K+ channels (BK(Ca)) are mediating the vasodilator action of hydralazine. In isolated porcine coronary arteries, hydralazine (1-300 microM), like the K+ channel opener levcromakalim, preferentially relaxed...

  16. Inhibitory actions by ibandronate sodium, a nitrogen-containing bisphosphonate, on calcium-activated potassium channels in Madin–Darby canine kidney cells

    Directory of Open Access Journals (Sweden)

    Sheng-Nan Wu

    2015-01-01

    Full Text Available The nitrogen-containing bisphosphonates used for management of the patients with osteoporosis were reported to influence the function of renal tubular cells. However, how nitrogen-containing bisphosphates exert any effects on ion currents remains controversial. The effects of ibandronate (Iban, a nitrogen-containing bisphosphonate, on ionic channels, including two types of Ca2+-activated K+ (KCa channels, namely, large-conductance KCa (BKCa and intermediate-conductance KCa (IKCa channels, were investigated in Madin–Darby canine kidney (MDCK cells. In whole-cell current recordings, Iban suppressed the amplitude of voltage-gated K+ current elicited by long ramp pulse. Addition of Iban caused a reduction of BKCa channels accompanied by a right shift in the activation curve of BKCa channels, despite no change in single-channel conductance. Ca2+ sensitivity of these channels was modified in the presence of this compound; however, the magnitude of Iban-mediated decrease in BKCa-channel activity under membrane stretch with different negative pressure remained unchanged. Iban suppressed the probability of BKCa-channel openings linked primarily to a shortening in the slow component of mean open time in these channels. The dissociation constant needed for Iban-mediated suppression of mean open time in MDCK cells was 12.2 μM. Additionally, cell exposure to Iban suppressed the activity of IKCa channels, and DC-EBIO or 9-phenanthrol effectively reversed its suppression. Under current-clamp configuration, Iban depolarized the cells and DC-EBIO or PF573228 reversed its depolarizing effect. Taken together, the inhibitory action of Iban on KCa-channel activity may contribute to the underlying mechanism of pharmacological or toxicological actions of Iban and its structurally similar bisphosphonates on renal tubular cells occurring in vivo.

  17. Tyrosine phosphatases epsilon and alpha perform specific and overlapping functions in regulation of voltage-gated potassium channels in Schwann cells

    DEFF Research Database (Denmark)

    Tiran, Zohar; Peretz, Asher; Sines, Tal

    2006-01-01

    Tyrosine phosphatases (PTPs) epsilon and alpha are closely related and share several molecular functions, such as regulation of Src family kinases and voltage-gated potassium (Kv) channels. Functional interrelationships between PTPepsilon and PTPalpha and the mechanisms by which they regulate K......+ channels and Src were analyzed in vivo in mice lacking either or both PTPs. Lack of either PTP increases Kv channel activity and phosphorylation in Schwann cells, indicating these PTPs inhibit Kv current amplitude in vivo. Open probability and unitary conductance of Kv channels are unchanged, suggesting...... an effect on channel number or organization. PTPalpha inhibits Kv channels more strongly than PTPepsilon; this correlates with constitutive association of PTPalpha with Kv2.1, driven by membranal localization of PTPalpha. PTPalpha, but not PTPepsilon, activates Src in sciatic nerve extracts, suggesting Src...

  18. Boosting of synaptic potentials and spine Ca transients by the peptide toxin SNX-482 requires alpha-1E-encoded voltage-gated Ca channels.

    Science.gov (United States)

    Giessel, Andrew J; Sabatini, Bernardo L

    2011-01-01

    The majority of glutamatergic synapses formed onto principal neurons of the mammalian central nervous system are associated with dendritic spines. Spines are tiny protuberances that house the proteins that mediate the response of the postsynaptic cell to the presynaptic release of glutamate. Postsynaptic signals are regulated by an ion channel signaling cascade that is active in individual dendritic spines and involves voltage-gated calcium (Ca) channels, small conductance (SK)-type Ca-activated potassium channels, and NMDA-type glutamate receptors. Pharmacological studies using the toxin SNX-482 indicated that the voltage-gated Ca channels that signal within spines to open SK channels belong to the class Ca(V)2.3, which is encoded by the Alpha-1E pore-forming subunit. In order to specifically test this conclusion, we examined the effects of SNX-482 on synaptic signals in acute hippocampal slices from knock-out mice lacking the Alpha-1E gene. We find that in these mice, application of SNX-482 has no effect on glutamate-uncaging evoked synaptic potentials and Ca influx, indicating that that SNX-482 indeed acts via the Alpha-1E-encoded Ca(V)2.3 channel.

  19. Boosting of synaptic potentials and spine Ca transients by the peptide toxin SNX-482 requires alpha-1E-encoded voltage-gated Ca channels.

    Directory of Open Access Journals (Sweden)

    Andrew J Giessel

    Full Text Available The majority of glutamatergic synapses formed onto principal neurons of the mammalian central nervous system are associated with dendritic spines. Spines are tiny protuberances that house the proteins that mediate the response of the postsynaptic cell to the presynaptic release of glutamate. Postsynaptic signals are regulated by an ion channel signaling cascade that is active in individual dendritic spines and involves voltage-gated calcium (Ca channels, small conductance (SK-type Ca-activated potassium channels, and NMDA-type glutamate receptors. Pharmacological studies using the toxin SNX-482 indicated that the voltage-gated Ca channels that signal within spines to open SK channels belong to the class Ca(V2.3, which is encoded by the Alpha-1E pore-forming subunit. In order to specifically test this conclusion, we examined the effects of SNX-482 on synaptic signals in acute hippocampal slices from knock-out mice lacking the Alpha-1E gene. We find that in these mice, application of SNX-482 has no effect on glutamate-uncaging evoked synaptic potentials and Ca influx, indicating that that SNX-482 indeed acts via the Alpha-1E-encoded Ca(V2.3 channel.

  20. Calcium-Activated Potassium Channels in Ischemia Reperfusion: A Brief Update

    Directory of Open Access Journals (Sweden)

    Jean-Yves eTano

    2014-10-01

    Full Text Available Ischemia and reperfusion (IR injury constitutes one of the major causes of cardiovascular morbidity and mortality. The discovery of new therapies to block/mediate the effects of IR is therefore an important goal in the biomedical sciences. Dysfunction associated with IR involves modification of calcium-activated potassium channels (KCa through different mechanisms, which are still under study. Respectively, the KCa family, major contributors to plasma membrane calcium influx in cells and essential players in the regulation of the vascular tone are interesting candidates. This family is divided into two groups including the large conductance (BKCa and the small/intermediate conductance (SKCa/IKCa K+ channels. In the heart and brain, these channels have been described to offer protection against IR injury. BKCa and SKCa channels deserve special attention since new data demonstrate that these channels are also expressed in mitochondria. More studies are however needed to fully determine their potential use as therapeutic targets.

  1. Dynamics of energy distribution in three channel alpha helix protein based on Davydov’s ansatz

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Faozan; Alatas, Husin [Theoretical Physics Division, Department of Physics, Faculty of Mathematics and Sciences Bogor Agricultural University, Bogor, Indonesia, 16680 faozan@ipb.ac.id (Indonesia)

    2015-04-16

    An important aspect of many biological processes at molecular level is the transfer and storage mechanism of bioenergy released in the reaction of the hydrolysis of Adenosinetriphosphate (ATP) by biomacromolecule especially protein. Model of Soliton Davydov is a new break-through that could describe that mechanism. Here we have reformulated quantum mechanical the Davydov theory, using least action principle. Dynamical aspect of the model is analyzed by numerical calculation. We found two dynamical cases: the traveling and pinning soliton that we suggest they are related to the energy transfer and storage mechanism in the protein. Traveling and pinning soliton can be controlled by strength of coupling. In 3- channel approach, we found the breather phenomena in which its frequency is determined by interchannel coupling parameter.

  2. Fluorescence resonance energy transfer on the voltage-dependent sodium channel. Spatial relationship and site coupling between the batrachotoxin and Leiurus quinquestriatus quinquestriatus alpha-scorpion toxin receptors.

    Science.gov (United States)

    Angelides, K J; Brown, G B

    1984-05-25

    A fluorescent N- methylanthraniloyl derivative of the potent depolarizing agent batrachotoxin has been used to probe the structural and conformational properties of the neurotoxin receptor site on the voltage-dependent sodium channel. Batrachotoxin A 20-alpha-N- methylanthranilate (BTX-NMA) retains high affinity for its receptor site on the synaptosomal sodium channel with a Kd between 78 and 91 nM and an average site capacity of 2 pmol/mg of synaptosomal protein in the presence of Leiurus quinquestriatus quinquestriatus alpha-scorpion toxin. The fluorescence emission of BTX-NMA upon binding to synaptosomes indicates a hydrophobic environment. Toxin V from L. quinquestriatus, an allosteric activator, effects a 20-nm red shift in the spectrum of bound BTX-NMA and a 4-fold enhancement in the fluorescence quantum yield disclosing a conformational change into a hydrophilic environment. Fluorescence resonance energy transfer measurements show that the distance separating the receptor sites is 37 +/- 10 A. Thus, the binding of alpha-scorpion toxin must involve conformational changes that extend over large distances from the batrachotoxin-binding locus. This information together with the distance measurements between the tetrodotoxin and alpha-scorpion toxin receptors and the conformational transition associated with this distance upon batrachotoxin addition indicate a conformationally flexible channel with coupling of sites through the polyatomic framework of individual subunits or through extensive alterations in subunit/subunit interactions.

  3. Bupivacaine inhibits large conductance, voltage- and Ca2+- activated K+ channels in human umbilical artery smooth muscle cells

    Science.gov (United States)

    Martín, Pedro; Enrique, Nicolás; Palomo, Ana R. Roldán; Rebolledo, Alejandro; Milesi, Veronica

    2012-01-01

    Bupivacaine is a local anesthetic compound belonging to the amino amide group. Its anesthetic effect is commonly related to its inhibitory effect on voltage-gated sodium channels. However, several studies have shown that this drug can also inhibit voltage-operated K+ channels by a different blocking mechanism. This could explain the observed contractile effects of bupivacaine on blood vessels. Up to now, there were no previous reports in the literature about bupivacaine effects on large conductance voltage- and Ca2+-activated K+ channels (BKCa). Using the patch-clamp technique, it is shown that bupivacaine inhibits single-channel and whole-cell K+ currents carried by BKCa channels in smooth muscle cells isolated from human umbilical artery (HUA). At the single-channel level bupivacaine produced, in a concentration- and voltage-dependent manner (IC50 324 µM at +80 mV), a reduction of single-channel current amplitude and induced a flickery mode of the open channel state. Bupivacaine (300 µM) can also block whole-cell K+ currents (~45% blockage) in which, under our working conditions, BKCa is the main component. This study presents a new inhibitory effect of bupivacaine on an ion channel involved in different cell functions. Hence, the inhibitory effect of bupivacaine on BKCa channel activity could affect different physiological functions where these channels are involved. Since bupivacaine is commonly used during labor and delivery, its effects on umbilical arteries, where this channel is highly expressed, should be taken into account. PMID:22688134

  4. delta-Atracotoxins from australian funnel-web spiders compete with scorpion alpha-toxin binding but differentially modulate alkaloid toxin activation of voltage-gated sodium channels.

    Science.gov (United States)

    Little, M J; Zappia, C; Gilles, N; Connor, M; Tyler, M I; Martin-Eauclaire, M F; Gordon, D; Nicholson, G M

    1998-10-16

    delta-Atracotoxins from the venom of Australian funnel-web spiders are a unique group of peptide toxins that slow sodium current inactivation in a manner similar to scorpion alpha-toxins. To analyze their interaction with known sodium channel neurotoxin receptor sites, we studied their effect on [3H]batrachotoxin and 125I-Lqh II (where Lqh is alpha-toxin II from the venom of the scorpion Leiurus quinquestriatus hebraeus) binding and on alkaloid toxin-stimulated 22Na+ uptake in rat brain synaptosomes. delta-Atracotoxins significantly increased [3H]batrachotoxin binding yet decreased maximal batrachotoxin-activated 22Na+ uptake by 70-80%, the latter in marked contrast to the effect of scorpion alpha-toxins. Unlike the inhibition of batrachotoxin-activated 22Na+ uptake, delta-atracotoxins increased veratridine-stimulated 22Na+ uptake by converting veratridine from a partial to a full agonist, analogous to scorpion alpha-toxins. Hence, delta-atracotoxins are able to differentiate between the open state of the sodium channel stabilized by batrachotoxin and veratridine and suggest a distinct sub-conductance state stabilized by delta-atracotoxins. Despite these actions, low concentrations of delta-atracotoxins completely inhibited the binding of the scorpion alpha-toxin, 125I-Lqh II, indicating that they bind to similar, or partially overlapping, receptor sites. The apparent uncoupling between the increase in binding but inhibition of the effect of batrachotoxin induced by delta-atracotoxins suggests that the binding and action of certain alkaloid toxins may represent at least two distinguishable steps. These results further contribute to the understanding of the complex dynamic interactions between neurotoxin receptor site areas related to sodium channel gating.

  5. Design and calibration of a two-channel low-noise heterodyne receiver for use in a CO2 laser Thomson scattering alpha particle diagnostic

    Science.gov (United States)

    Bennett, C. A.; Richards, R. K.; Hutchinson, D. P.

    1988-03-01

    A dual channel low noise heterodyne receiver has been constructed as part of a development effort to build a carbon dioxide laser based Thomson scattering alpha particle diagnostic for a burning plasma experiment. The receiver employs two wide bandwidth (greater than 1 GHz) HgCdTe photovoltaic mixers followed by low noise IF amplifiers. A noise equivalent power of less than 3.0 times 10 to the 20th power WHz has been demonstrated. Design details and calibration methods are described.

  6. Congenital heart block: identification of autoantibody binding site on the extracellular loop (domain I, S5-S6) of alpha(1D) L-type Ca channel.

    Science.gov (United States)

    Karnabi, Eddy; Qu, Yongxia; Wadgaonkar, Raj; Mancarella, Salvatore; Yue, Yuankun; Chahine, Mohamed; Clancy, Robert M; Buyon, Jill P; Boutjdir, Mohamed

    2010-03-01

    Congenital heart block (CHB) is an autoimmune disease associated with autoantibodies against intracellular ribonucleoproteins SSB/La and SSA/Ro. The hallmark of CHB is complete atrioventricular block. We have recently established that anti-SSA/Ro -SSB/La autoantibodies inhibit alpha(1D) L-type Ca current, I(Ca-L), and cross-react with the alpha(1D) Ca channel protein. This study aims at identifying the possible binding sites on alpha(1D) protein for autoantibodies from sera of mothers with CHB children. GST fusion proteins of the extracellular regions between the transmembrane segments (S5-S6) of each of the four alpha(1D) Ca channel protein domains I-IV were prepared and tested for reactivity with sera from mothers with CHB children and controls using ELISA. Sera containing anti-Ro/La autoantibodies from 118 mothers with CHB children and from 15 mothers with anti-Ro/La autoantibodies but have healthy children, and from 28 healthy mothers without anti-Ro/La autoantibodies and healthy children were evaluated. Seventeen of 118 (14.4%) sera from mothers with CHB children reacted with the extracellular loop of domain I S5-S6 region (E1). In contrast, only 2 of 28 (7%) of sera from healthy mothers (-anti-Ro/La) and healthy children reacted with E1 loop and none (0 of 15) of sera from healthy mothers (+anti-Ro/La) and healthy children reacted with the E1 loop. Preincubation of E1 loop with the positive sera decreased the O.D reading establishing the specificity of the response. Electrophysiological characterization of the ELISA positive sera and purified IgG showed inhibition (44.1% and 49.8%, respectively) of the alpha(1D) I(Ca-L) expressed in tsA201 cells. The inhibition was abolished when the sera were pre-incubated with E1 fusion protein. The results identified the extracellular loop of domain I S5-S6 of L-type Ca channel alpha(1D) subunit as a target for autoantibodies from a subset of mothers with CHB children. This novel finding provides insights into the

  7. Voltage-dependent conformational changes in human Ca2+- and voltage-activated K+ channel, revealed by voltage-clamp fluorometry

    Science.gov (United States)

    Savalli, Nicoletta; Kondratiev, Andrei; Toro, Ligia; Olcese, Riccardo

    2006-01-01

    Large conductance voltage- and Ca2+-activated K+ (BKCa) channels regulate important physiological processes such as neurotransmitter release and vascular tone. BKCa channels possess a voltage sensor mainly represented by the S4 transmembrane domain. Changes in membrane potential displace the voltage sensor, producing a conformational change that leads to channel opening. By site-directed fluorescent labeling of residues in the S3–S4 region and by using voltage clamp fluorometry, we have resolved the conformational changes the channel undergoes during activation. The voltage dependence of these conformational changes (detected as changes in fluorescence emission, fluorescence vs. voltage curves) always preceded the channel activation curves, as expected for protein rearrangements associated to the movement of the voltage sensor. Extremely slow conformational changes were revealed by fluorescent labeling of position 202, elicited by a mutual interaction of the fluorophore with the adjacent tryptophan 203. PMID:16895996

  8. Voltage-dependent conformational changes in human Ca(2+)- and voltage-activated K(+) channel, revealed by voltage-clamp fluorometry.

    Science.gov (United States)

    Savalli, Nicoletta; Kondratiev, Andrei; Toro, Ligia; Olcese, Riccardo

    2006-08-15

    Large conductance voltage- and Ca(2+)-activated K(+) (BK(Ca)) channels regulate important physiological processes such as neurotransmitter release and vascular tone. BK(Ca) channels possess a voltage sensor mainly represented by the S4 transmembrane domain. Changes in membrane potential displace the voltage sensor, producing a conformational change that leads to channel opening. By site-directed fluorescent labeling of residues in the S3-S4 region and by using voltage clamp fluorometry, we have resolved the conformational changes the channel undergoes during activation. The voltage dependence of these conformational changes (detected as changes in fluorescence emission, fluorescence vs. voltage curves) always preceded the channel activation curves, as expected for protein rearrangements associated to the movement of the voltage sensor. Extremely slow conformational changes were revealed by fluorescent labeling of position 202, elicited by a mutual interaction of the fluorophore with the adjacent tryptophan 203.

  9. Autoradiographic localization of voltage-dependent sodium channels on the mouse neuromuscular junction using 125I-alpha scorpion toxin. I. Preferential labeling of glial cells on the presynaptic side

    International Nuclear Information System (INIS)

    Boudier, J.L.; Jover, E.; Cau, P.

    1988-01-01

    Alpha-scorpion toxins bind specifically to the voltage-sensitive sodium channel in excitable membranes, and binding is potential-dependent. The radioiodinated toxin II from the scorpion Androctonus australis Hector (alpha ScTx) was used to localize voltage-sensitive sodium channels on the presynaptic side of mouse neuromuscular junctions (NMJ) by autoradiography using both light and electron microscopy. Silver grain localization was analyzed by the cross-fire method. At the light-microscopic level, grain density over NMJ appeared 6-8x higher than over nonjunctional muscle membrane. The specificity of labeling was verified by competition/displacement with an excess of native alpha ScTx. Labeling was also inhibited by incubation in depolarizing conditions, showing its potential-dependence. At the electron-microscopic level, analysis showed that voltage-sensitive sodium channels labeled with alpha ScTx were almost exclusively localized on membranes, as expected. Due to washout after incubation, appreciable numbers of binding sites were not found on the postsynaptic membranes. However, on the presynaptic side, alpha ScTx-labeled voltage-sensitive sodium channels were localized on the membrane of non-myelin-forming Schwann cells covering NMJ. The axonal presynaptic membrane was not labeled. These results show that voltage-sensitive sodium channels are present on glial cells in vivo, as already demonstrated in vitro. It is proposed that these glial channels could be indirectly involved in the ionic homeostasis of the axonal environment

  10. Heterogeneity of L-type calcium channel alpha 1 subunits: stereoselective discrimination of different populations by the novel 1,4-dihydropyridine B 874-67.

    Science.gov (United States)

    Lakitsch, M; Knaus, H G; Topar, G; Romanin, C; Boer, R; Flockerzi, D; Striessnig, J; Schindler, H; Hoeltje, H D; Glossmann, H

    1993-02-01

    The basic (pKa = 8.49) 1,4-dihydropyridine B 874-67 [[3-(C1R,2S)- 2-methylamino-1-phenylpropyl]-5-methyl-1,4-dihydro-2,6-dimethyl-(4R)-4-( 3-nitrophenyl)pyridine-3,5-dicarboxylate hydrochloride] has unique properties; it can discriminate two populations of alpha 1 subunits in 1,4-dihydropyridine-sensitive calcium channels labeled with the neutral 1,4-dihydropyridine (+)-[3H]PN 200-110. The two populations, which occur in proportions of approximately 2:1 in rabbit skeletal muscle membranes and highly purified calcium channel preparations, differ approximately 20-fold in their affinity. The corresponding diastereomer, B 874-66, and other 1,4-dihydropyridines (neutral, basic, or permanently charged) do not share this property. The two populations were observed at 2 degrees, 22 degrees, and 37 degrees in similar proportions. Heterogeneity was also observed for guinea pig heart membrane calcium channels labeled with (+)-[3H]PN 200-110. Heterotropic allosteric regulators, Ca2+, and Mg2+, but not Ba2+ and Ni2+, abolished the discriminatory activity of B 874-67 at 2 degrees and 22 degrees, regardless of whether binding of the neutral 1,4-dihydropyridine was stimulated or inhibited. It is proposed that the two alpha 1 subunit populations differ with respect to their 1,4-dihydropyridine binding domain. The structural basis for the two populations is unclear but may relate to the functional heterogeneity of membrane-bound and highly purified calcium channel preparations previously observed by others.

  11. Comparative study of the distribution of the alpha-subunits of voltage-gated sodium channels in normal and axotomized rat dorsal root ganglion neurons.

    Science.gov (United States)

    Fukuoka, Tetsuo; Kobayashi, Kimiko; Yamanaka, Hiroki; Obata, Koichi; Dai, Yi; Noguchi, Koichi

    2008-09-10

    We compared the distribution of the alpha-subunit mRNAs of voltage-gated sodium channels Nav1.1-1.3 and Nav1.6-1.9 and a related channel, Nax, in histochemically identified neuronal subpopulations of the rat dorsal root ganglia (DRG). In the naïve DRG, the expression of Nav1.1 and Nav1.6 was restricted to A-fiber neurons, and they were preferentially expressed by TrkC neurons, suggesting that proprioceptive neurons possess these channels. Nav1.7, -1.8, and -1.9 mRNAs were more abundant in C-fiber neurons compared with A-fiber ones. Nax was evenly expressed in both populations. Although Nav1.8 and -1.9 were preferentially expressed by TrkA neurons, other alpha-subunits were expressed independently of TrkA expression. Actually, all IB4(+) neurons expressed both Nav1.8 and -1.9, and relatively limited subpopulations of IB4(+) neurons (3% and 12%, respectively) expressed Nav1.1 and/or Nav1.6. These findings provide useful information in interpreting the electrophysiological characteristics of some neuronal subpopulations of naïve DRG. After L5 spinal nerve ligation, Nav1.3 mRNA was up-regulated mainly in A-fiber neurons in the ipsilateral L5 DRG. Although previous studies demonstrated that nerve growth factor (NGF) and glial cell-derived neurotrophic factor (GDNF) reversed this up-regulation, the Nav1.3 induction was independent of either TrkA or GFRalpha1 expression, suggesting that the induction of Nav1.3 may be one of the common responses of axotomized DRG neurons without a direct relationship to NGF/GDNF supply. (c) 2008 Wiley-Liss, Inc.

  12. Intracellular ion channels and cancer

    Directory of Open Access Journals (Sweden)

    Luigi eLeanza

    2013-09-01

    Full Text Available Several types of channels play a role in the maintenance of ion homeostasis in subcellular organelles including endoplasmatic reticulum, nucleus, lysosome, endosome and mitochondria. Here we give a brief overview of the contribution of various mitochondrial and other organellar channels to cancer cell proliferation or death. Much attention is focused on channels involved in intracellular calcium signaling and on ion fluxes in the ATP-producing organelle mitochondria. Mitochondrial K+ channels (Ca2+-dependent BKCa and IKCa, ATP-dependent KATP, Kv1.3, two-pore TWIK-related Acid-Sensitive K+ channel-3 (TASK-3, Ca2+ uniporter MCU, Mg2+-permeable Mrs2, anion channels (voltage-dependent chloride channel VDAC, intracellular chloride channel CLIC and the Permeability Transition Pore (MPTP contribute importantly to the regulation of function in this organelle. Since mitochondria play a central role in apoptosis, modulation of their ion channels by pharmacological means may lead to death of cancer cells. The nuclear potassium channel Kv10.1 and the nuclear chloride channel CLIC4 as well as the endoplasmatic reticulum (ER-located inositol 1,4,5-trisphosphate (IP3 receptor, the ER-located Ca2+ depletion sensor STIM1 (stromal interaction molecule 1, a component of the store-operated Ca2+ channel and the ER-resident TRPM8 are also mentioned. Furthermore, pharmacological tools affecting organellar channels and modulating cancer cell survival are discussed. The channels described in this review are summarized on Figure 1. Overall, the view is emerging that intracellular ion channels may represent a promising target for cancer treatment.

  13. The alpha(1S) subunit of the L-type calcium channel is not a predisposition gene for thyrotoxic periodic paralysis.

    Science.gov (United States)

    Tang, Nelson L S; Chow, C C; Ko, Gary T C; Tai, Morris H L; Kwok, Rachel; Yao, X Q; Cockram, Clive S

    2007-02-01

    Thyrotoxic periodic paralysis (TTP) has been associated with genetic variations in the gene encoding the alpha 1 subunit of the L-type calcium channel (CACNA1S). Mutations in CACNA1S are known to account for the majority of cases of familial hypokalaemic periodic paralysis (HOKPP). In this study we have examined 48 genetic polymorphisms in the CACNA1S gene and genotyped a tagging set of representative polymorphisms to determine the role of this gene in TPP. A genetic association study was carried out with 98 TPP patients and 162 male thyrotoxic controls. Among 47 polymorphisms evaluated for linkage disequilibrium (LD) and the spectrum of haplotypes in the Chinese population, 31 were selected as tagging single-nucleotide polymorphisms (SNPs) for genotyping the whole sample. A new genotyping protocol was used to analyse an insertion/deletion (I/D) polymorphism. We studied the LD among 47 polymorphisms in the CACNA1S gene, which comprised a set of high-density markers with an average of one SNP every 2 kb. Subsequently, 31 tagSNPs were genotyped for all the samples. The gene is composed of three LD blocks. With this block structure, we were confident that variations of the gene were comprehensively covered by the tagSNPs. No significant association was found between the polymorphisms and TPP. We established the LD structure of this calcium channel subunit gene (CACNA1S) for the first time. However, its genetic variations are not associated with TPP in Chinese patients.

  14. K+ channels of Müller glial cells in retinal disorders.

    Science.gov (United States)

    Gao, Feng; Xu, Linjie; Zhao, Yuan; Sun, Xinghuai; Wang, Zhongfeng

    2018-02-01

    Müller cell is the major type glial cell in the vertebrate retina. Müller cells express various types of K+ channels, such as inwardly rectifying K+ (Kir) channels, big conductance Ca2+-activated K+ (BKCa) channels, delayed rectifier K+ channels (KDR), and transient A-type K+ channels. These K+ channels play important roles in maintaining physiological functions of Müller cells. Under some retinal pathological conditions, the changed expression and functions of K+ channels may contribute to retinal pathogenesis. In this article, we reviewed the physiological properties of K+ channels in retinal Müller cells and the functional changes of these channels in retinal disorders. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  15. Altered expression of the voltage-gated calcium channel subunit alpha(2)delta-1: A comparison between two experimental models of epilepsy and a sensory nerve ligation model of neuropathic pain

    Czech Academy of Sciences Publication Activity Database

    Nieto-Rostro, M.; Sandhu, G.; Bauer, C. S.; Jiruška, Přemysl; Jefferys, J. G. R.; Dolphin, A. C.

    2014-01-01

    Roč. 283, Dec (2014), s. 124-137 ISSN 0306-4522 R&D Projects: GA MZd(CZ) NT14489 Institutional support: RVO:67985823 Keywords : calcium channel * dorsal root ganglion (DRG) * alpha2delta subunit * epilepsy * neuropathic pain * reactive gliosis Subject RIV: FH - Neurology Impact factor: 3.357, year: 2014

  16. The structures of the human calcium channel {alpha}{sub 1} subunit (CACNL1A2) and {beta} subunit (CACNLB3) genes

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yuichiro; Masuda, Kazuhiro; Li, Qing [Kyoto Univ. Faculty of Medicine (Japan)] [and others

    1995-05-20

    Calcium influx in pancreatic {beta}-cells is regulated mainly by L-type voltage-dependent calcium channels (VDCCs) and triggers insulin secretion. The {alpha}{sub 1} subunit (CACN4) and the {beta} subunit ({beta}{sub 3}) of VDCCs, both of which are expressed in pancreatic islets, are major components for the VDCC activity, and so they may play a critical role in the regulation of insulin secretion. The authors have determined the structures of the human CACN4 (CACNL1A2) and the human {beta}{sub 3} (CACNLB3) genes. The CACNL1A2 gene spans more than 155 kb and has 49 exons. Most of the positions interrupted by introns are well conserved between the CACNL1A2 gene and the previously reported L-type VDCC {alpha}{sub 1} subunit, CACNL1A1, gene. On the other hand, the CACNLB3 gene distributes in {approximately} 8 kb and comprises 13 exons, most of which are located together within {approximately} 5 kb. Comparisons of the genomic sequences of CACNL1A2 with the previously reported cDNA sequences indicate that there are a number of polymorphisms in the human CACNL1A2 gene. In addition, the PCR-SSCP procedure of exon 1 of CACNL1A2 revealed a change from 7 to 8 ATG trinucleotide repeats in a patient with noninsulin-dependent diabetes mellitus (NIDDM), resulting in an addition of methionine at the amino-terminus of CACN4. The determination of the structures of the human CACNL1A2 and CACNLB3 genes should facilitate study of the role of these genes in the development of NIDDM and also other genetic diseases such as long QT syndrome. 39 refs., 3 figs., 3 tabs.

  17. Vascular ATP-sensitive potassium channels are over-expressed and partially regulated by nitric oxide in experimental septic shock.

    Science.gov (United States)

    Collin, Solène; Sennoun, Nacira; Dron, Anne-Gaëlle; de la Bourdonnaye, Mathilde; Montemont, Chantal; Asfar, Pierre; Lacolley, Patrick; Meziani, Ferhat; Levy, Bruno

    2011-05-01

    To study the activation and expression of vascular (aorta and small mesenteric arteries) potassium channels during septic shock with or without modulation of the NO pathway. Septic shock was induced in rats by peritonitis. Selective inhibitors of vascular K(ATP) (PNU-37883A) or BK(Ca) [iberiotoxin (IbTX)] channels were used to demonstrate their involvement in vascular hyporeactivity. Vascular response to phenylephrine was measured on aorta and small mesenteric arteries mounted on a wire myograph. Vascular expression of potassium channels was studied by PCR and Western blot, in the presence or absence of 1400W, an inducible NO synthase (iNOS) inhibitor. Aortic activation of the transcriptional factor nuclear factor-kappaB (NF-κB) was assessed by electrophoretic mobility shift assay. Arterial pressure as well as in vivo and ex vivo vascular reactivity were reduced by sepsis and improved by PNU-37883A but not by IbTX. Sepsis was associated with an up-regulation of mRNA and protein expression of vascular K(ATP) channels, while expression of vascular BK(Ca) channels remained unchanged. Selective iNOS inhibition blunted the sepsis-induced increase in aortic NO, decreased NF-κB activation, and down-regulated vascular K(ATP) channel expression. Vascular K(ATP) but not BK(Ca) channels are activated, over-expressed, and partially regulated by NO via NF-κB activation during septic shock. Their selective inhibition restores arterial pressure and vascular reactivity and decreases lactate concentration. The present data suggest that selective vascular K(ATP) channel inhibitors offer potential therapeutic perspectives for septic shock.

  18. A new sodium channel {alpha}-subunit gene (Scn9a) from Schwann cells maps to the Scn1a, Scn2a, Scn3a cluster of mouse chromosome 2

    Energy Technology Data Exchange (ETDEWEB)

    Beckers, M.C.; Ernst, E.; Gros, P. [McGill Univ., Montreal (Canada)

    1996-08-15

    We have used a total of 27 AXB/BXA recombinant inbred mouse strains to determine the chromosomal location of a newly identified gene encoding an {alpha}-subunit isoform of the sodium channel from Schwann cells, Scn9a. Linkage analysis established that Scn9a mapped to the proximal segment of mouse chromosome 2. The segregation of restriction fragment length polymorphisms in 145 progeny from a Mus spretus x C57BL/6J backcross indicates that Scn9a is very tightly linked to Scn1a (gene encoding the type I sodium channel {alpha}-subunit of the brain) and forms part of a cluster of four Scna genes located on mouse chromosome 2. 17 refs., 1 fig., 3 tabs.

  19. Calcium channel alpha-2-delta-1 protein upregulation in dorsal spinal cord mediates spinal cord injury-induced neuropathic pain states.

    Science.gov (United States)

    Boroujerdi, Amin; Zeng, Jun; Sharp, Kelli; Kim, Donghyun; Steward, Oswald; Luo, Z David

    2011-03-01

    Spinal cord injury (SCI) commonly results in the development of neuropathic pain, which can dramatically impair the quality of life for SCI patients. SCI-induced neuropathic pain can be manifested as both tactile allodynia (a painful sensation to a non-noxious stimulus) and hyperalgesia (an enhanced sensation to a painful stimulus). The mechanisms underlying these pain states are poorly understood. Clinical studies have shown that gabapentin, a drug that binds to the voltage-gated calcium channel alpha-2-delta-1 subunit (Ca(v)α2δ-1) proteins is effective in the management of SCI-induced neuropathic pain. Accordingly, we hypothesized that tactile allodynia post SCI is mediated by an upregulation of Ca(v)α2δ-1 in dorsal spinal cord. To test this hypothesis, we examined whether SCI-induced dysregulation of spinal Ca(v)α2δ-1 plays a contributory role in below-level allodynia development in a rat spinal T9 contusion injury model. We found that Ca(v)α2δ-1 expression levels were significantly increased in L4-6 dorsal, but not ventral, spinal cord of SCI rats that correlated with tactile allodynia development in the hind paw plantar surface. Furthermore, both intrathecal gabapentin treatment and blocking SCI-induced Ca(v)α2δ-1 protein upregulation by intrathecal Ca(v)α2δ-1 antisense oligodeoxynucleotides could reverse tactile allodynia in SCI rats. These findings support that SCI-induced Ca(v)α2δ-1 upregulation in spinal dorsal horn is a key component in mediating below-level neuropathic pain states, and selectively targeting this pathway may provide effective pain relief for SCI patients. Spinal cord contusion injury caused increased calcium channel Ca(v)α2δ-1 subunit expression in dorsal spinal cord that contributes to neuropathic pain states. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  20. Blockade of ATP-sensitive potassium channels prevents the attenuation of the exercise pressor reflex by tempol in rats with ligated femoral arteries.

    Science.gov (United States)

    Yamauchi, Katsuya; Stone, Audrey J; Stocker, Sean D; Kaufman, Marc P

    2012-08-01

    We reported previously that tempol attenuated the exercise pressor and muscle mechanoreceptor reflexes in rats whose femoral arteries were ligated, whereas tempol did not attenuate these reflexes in rats whose femoral arteries were freely perfused. Although the mechanism whereby tempol attenuated these reflexes in rats whose femoral artery was ligated was independent of its ability to scavenge reactive oxygen species, its nature remains unclear. An alternative explanation for the tempol-induced attenuation of these reflexes involves ATP-sensitive potassium channels (K(ATP)) and calcium-activated potassium channels (BK(Ca)), both of which are opened by tempol. We tested the likelihood of this explanation by measuring the effects of either glibenclamide (0.1 mg/kg), which blocks K(ATP) channels, or iberiotoxin (20 or 40 μg/kg), which blocks BK(Ca) channels, on the tempol-induced attenuation of the exercise pressor and muscle mechanoreceptor reflexes in decerebrated rats whose femoral arteries were ligated. We found that glibenclamide prevented the tempol-induced attenuation of both reflexes, whereas iberiotoxin did not. We also found that the amount of protein comprising the pore of the K(ATP) channel in the dorsal root ganglia innervating hindlimbs whose femoral artery was ligated was significantly greater than that in the dorsal root ganglia innervating hindlimbs whose femoral arteries were freely perfused. In contrast, the amounts of protein comprising the BK(Ca) channel in the dorsal root ganglia innervating the ligated and freely perfused hindlimbs were not different. We conclude that tempol attenuated both reflexes by opening K(ATP) channels, an effect that hyperpolarized muscle afferents stimulated by static contraction or tendon stretch.

  1. Upregulation of calcium channel alpha-2-delta-1 subunit in dorsal horn contributes to spinal cord injury-induced tactile allodynia.

    Science.gov (United States)

    Kusuyama, Kazuki; Tachibana, Toshiya; Yamanaka, Hiroki; Okubo, Masamichi; Yoshiya, Shinichi; Noguchi, Koichi

    2018-01-31

    Spinal cord injury (SCI) commonly results not only in motor paralysis but also in the emergence of neuropathic pain (NeuP), both of which can impair the quality of life for patients with SCI. In the clinical field, it is well known that pregabalin, which binds to the voltage-gated calcium channel alpha-2-delta-1 (α 2 δ-1) subunit has therapeutic effects on NeuP after SCI. A previous study has demonstrated that SCI increased α 2 δ-1 in the L4-L6 dorsal spinal cord of SCI rats by Western blot analysis and that the increase of α 2 δ-1 was correlated with tactile allodynia of the hind paw. However, the detailed feature of an increase in α 2 δ-1 protein in the spinal dorsal horn and the mechanism of pregabalin effect on SCI-induced NeuP have not been fully examined. This study aimed to examine the detailed distribution of α 2 δ-1 expression in the lumbar spinal cord after thoracic SCI in rats and the correlation of the therapeutic effect of pregabalin in SCI rats. Male Sprague-Dawley rats underwent thoracic (T10) spinal cord contusion injury using the IH impactor device. Spinal cord injury rats received pregabalin (30 mg/kg) once a day for 2 weeks over a 4-week period after SCI. The mechanical threshold in the rat hind paw was measured over 4 weeks. Alpha-2-delta-1 expression in the lumbar spinal cord and in the dorsal root ganglion (DRG) was analyzed using immunohistochemistry and in situ hybridization histochemistry. A significant reduction of the withdrawal threshold of mechanical stimuli to the hind paw was observed for 2 weeks and continued at least 4 weeks after SCI. In the control rats, expression of α 2 δ-1 immunoreactivity was detected mainly in laminae I and II in the lumbar dorsal horn. Thoracic SCI significantly increased α 2 δ-1 immunoreactivity in laminae I and II in the lumbar dorsal horn 4 weeks after SCI; however, thoracic SCI did not affect the expression of α 2 δ-1 mRNA in the L4 and L5 DRGs. Meanwhile, the signal intensity of α 2

  2. Structure-function of proteins interacting with the alpha1 pore-forming subunit of high voltage-activated calcium channel

    Directory of Open Access Journals (Sweden)

    Alan eNeely

    2014-06-01

    Full Text Available Openings of high-voltage-activated calcium channels lead to a transient increase in calcium concentration that in turn activate a plethora of cellular functions, including muscle contraction, secretion and gene transcription. To coordinate all these responses calcium channels form supramolecular assemblies containing effectors and regulatory proteins that couple calcium influx to the downstream signal cascades and to feedback elements. According to the original biochemical characterization of skeletal muscle Dihydropyridine receptors, high-voltage-activated calcium channels are multi-subunit protein complexes consisting of a pore-forming subunit (α1 associated with four additional polypeptide chains β, α2, δ and γ, often referred to as accessory subunits. Twenty-five years after the first purification of a high-voltage calcium channel, the concept of a flexible stoichiometry to expand the repertoire of mechanisms that regulate calcium channel influx has emerged. Several other proteins have been identified that associate directly with the α1-subunit, including calmodulin and multiple members of the small and large GTPase family. Some of these proteins only interact with a subset of α1-subunits and during specific stages of biogenesis. More strikingly, most of the α1-subunit interacting proteins, such as the β-subunit and small GTPases, regulate both gating and trafficking through a variety of mechanisms. Modulation of channel activity covers almost all biophysical properties of the channel. Likewise, regulation of the number of channels in the plasma membrane is performed by altering the release of the α1-subunit from the endoplasmic reticulum, by reducing its degradation or enhancing its recycling back to the cell surface. In this review, we discuss the structural basis, interplay and functional role of selected proteins that interact with the central pore-forming subunit of high-voltage-activated calcium channels.

  3. Relative contribution of the hydrogen 2S two-photon decay and Lyman-alpha escape channels during the epoch of cosmological recombination

    OpenAIRE

    Rubino-Martin, J. A.; Sunyaev, R. A.

    2017-01-01

    We discuss the evolution of the ratio in number of recombinations due to 2s two photon escape and due to the escape of Lyman-$\\alpha$ photons from the resonance during the epoch of cosmological recombination, within the width of the last scattering surface and near its boundaries. We discuss how this ratio evolves in time, and how it defines the profile of the Lyman-$\\alpha$ line in the spectrum of CMB. One of the key reasons for explaining its time dependence is the strong overpopulation of ...

  4. THE EFFECT OF SOME ALPHA-ADRENOCEPTOR ANTAGONISTS ON SPONTANEOUS MYOGENIC ACTIVITY IN THE RAT PORTAL-VEIN AND THE PUTATIVE INVOLVEMENT OF ATP-SENSITIVE K+ CHANNELS

    NARCIS (Netherlands)

    SCHWIETERT, R; WILHELM, D; WILFFERT, B; VANZWIETEN, PA

    1992-01-01

    In the present study we showed that the alpha-adrenoceptor antagonists phentolamine, yohimbine, prazosin, corynanthine and idazoxan, when cumulatively applied in high concentrations (1-100-mu-mol/l), can increase spontaneous myogenic activity in the rat portal vein. 5-Methyl-urapidil and rauwolscine

  5. Genotypic to expression profiling of bovine calcium channel, voltage-dependent, alpha-2/delta subunit 1 gene, and their association with bovine mastitis among Frieswal (HFX Sahiwal) crossbred cattle of Indian origin.

    Science.gov (United States)

    Deb, Rajib; Singh, Umesh; Kumar, Sushil; Kumar, Arun; Singh, Rani; Sengar, Gyanendra; Mann, Sandeep; Sharma, Arjava

    2014-04-03

    Calcium channel, voltage-dependent, alpha-2/delta subunit 1 (CACNA2D1) gene is considered to be an important noncytokine candidate gene influencing mastitis. Scanty of reports are available until today regarding the role play of CACNA2D1 gene on the susceptibility of bovine mastitis. We interrogated the CACNA2D1 G519663A [A>G] SNP by PCR-RFLP among two hundreds Frieswal (HF X Sahiwal) crossbred cattle of Indian origin. Genotypic frequency of AA (51.5, n=101) was comparatively higher than AG (35, n=70) and GG (14.5, n=29). Association of Somatic cell score (SCS) with genotypes revealed that, GG genotypes showing lesser count (less susceptible to mastitis) compare to AA and AG. Relative expression of CACNA2D1 transcript (in milk samples) was significantly higher among GG than AG and AA. Further we have also isolated blood sample from the all groups and PBMCs were cultured from each blood sample as per the standard protocol. They were treated with Calcium channel blocker and the expression level of the CACNA2D1 gene was evaluated by Real Time PCR. Results show that expression level decline in each genotypic group after treatment and expression level of GG are again significantly higher than AA and AG. Thus, it may be concluded that GG genotypic animals are favorable for selecting disease resistant breeds.

  6. Anti-tumor Necrosis Factor Alpha (Infliximab) Attenuates Apoptosis, Oxidative Stress, and Calcium Ion Entry Through Modulation of Cation Channels in Neutrophils of Patients with Ankylosing Spondylitis.

    Science.gov (United States)

    Ugan, Yunus; Nazıroğlu, Mustafa; Şahin, Mehmet; Aykur, Mehmet

    2016-08-01

    Ankylosing Spondylitis (AS) is known to be associated with increased neutrophil activation and oxidative stress, however, the mechanism of neutrophil activation is still unclear. We have hypothesized that the antioxidant and anti-tumor necrosis factor properties of infliximab may affect intracellular Ca(2+) concentration in the neutrophils of AS patients. The objective of this study was to investigate the effects of infliximab on calcium signaling, oxidative stress, and apoptosis in neutrophils of AS patients. Neutrophils collected from ten patients with AS and ten healthy controls were used in the study. In a cell viability test, the ideal non-toxic dose and incubation time of infliximab were found as 100 μM and 1 h, respectively. In some experiments, the neutrophils were incubated with the voltage-gated calcium channel (VGCC) blockers verapamil + diltiazem (V + D) and the TRPM2 channel blocker 2-aminoethyl diphenylborinate (2-APB). Intracellular Ca(2+) concentration, lipid peroxidation, apoptosis, caspase 3, and caspase 9 values were high in neutrophils of AS patients and were reduced with infliximab treatment. Reduced glutathione level and glutathione peroxidase activity were low in the patients and increased with infliximab treatment. The intracellular Ca(2+) concentrations were low in 2-APB and V + D groups. In conclusion, the current study suggests that infliximab is useful against apoptotic cell death and oxidative stress in neutrophils of patients with AS, which seem to be dependent on increased levels of intracellular Ca(2+) through activation of TRPM2 and VGCC.

  7. Proteolytic processing of the L-type Ca2+ channel alpha11.2 subunit in neurons [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Olivia R. Buonarati

    2017-07-01

    Full Text Available Background: The L-type Ca2+ channel Cav1.2 is a prominent regulator of neuronal excitability, synaptic plasticity, and gene expression. The central element of Cav1.2 is the pore-forming α11.2 subunit. It exists in two major size forms, whose molecular masses have proven difficult to precisely determine. Recent work suggests that α11.2 is proteolytically cleaved between the second and third of its four pore-forming domains (Michailidis et al,. 2014. Methods: To better determine the apparent molecular masses (MRof the α11.2 size forms, extensive systematic immunoblotting of brain tissue as well as full length and C-terminally truncated α11.2 expressed in HEK293 cells was conducted using six different region–specific antibodies against α11.2. Results: The full length form of α11.2 migrated, as expected, with an apparent MR of ~250 kDa. A shorter form of comparable prevalence with an apparent MR of ~210 kDa could only be detected in immunoblots probed with antibodies recognizing α11.2 at an epitope 400 or more residues upstream of the C-terminus. Conclusions: The main two size forms of α11.2 are the full length form and a shorter form, which lacks ~350 distal C-terminal residues. Midchannel cleavage as suggested by Michailidis et al. (2014 is at best minimal in brain tissue.

  8. Nerve injury-induced calcium channel alpha-2-delta-1 protein dysregulation leads to increased pre-synaptic excitatory input into deep dorsal horn neurons and neuropathic allodynia

    Science.gov (United States)

    Zhou, Chunyi; Luo, Z. David

    2015-01-01

    Background Upregulation of voltage-gated-calcium-channel α2δ1 subunit post spinal nerve ligation injury (SNL) or in α2δ1-overexpressing transgenic (Tg) mice correlates with tactile allodynia, a pain state mediated mainly by Aβ sensory fibers forming synaptic connections with deep dorsal horn neurons. It is not clear however whether dysregulated α2δ1 alters deep dorsal horn synaptic neurotransmission that underlies tactile allodynia development post nerve injury. Methods Tactile allodynia was tested in the SNL and α2δ1 Tg models. Miniature excitatory/inhibitory postsynaptic currents were recorded in deep dorsal horn (DDH) neurons from these animal models using whole cell patch clamp slice recording techniques.. Results There was a significant increase in the frequency, but not amplitude, of miniature excitatory postsynaptic currents (mEPSC) in DDH neurons that correlated with tactile allodynia in SNL and α2δ1 Tg mice. Gabapentin, an α2δ1 ligand that is known to block tactile allodynia in these models, also normalized mEPSC frequency dose-dependently in DDH neurons from SNL and α2δ1 Tg mice. In contrast, neither frequency nor amplitude of miniature inhibitory postsynaptic currents (mIPSC) was altered in DDH neurons from SNL and α2δ1 Tg mice. Conclusion Our data suggest that α2δ1 dysregulation is highly likely contributing to tactile allodynia through a pre-synaptic mechanism involving facilitation of excitatory synaptic neurotransmission in deep dorsal horn of spinal cord. PMID:25691360

  9. High salt loading induces urinary storage dysfunction via upregulation of epithelial sodium channel alpha in the bladder epithelium in Dahl salt-sensitive rats

    Directory of Open Access Journals (Sweden)

    Seiji Yamamoto

    2017-11-01

    Full Text Available We aimed to investigate whether high salt intake affects bladder function via epithelial sodium channel (ENaC by using Dahl salt-resistant (DR and salt-sensitive (DS rats. Bladder weight of DR + high-salt diet (HS, 8% NaCl and DS + HS groups were significantly higher than those of DR + normal-salt diet (NS, 0.3% NaCl and DS + NS groups after one week treatment. We thereafter used only DR + HS and DS + HS group. Systolic and diastolic blood pressures were significantly higher in DS + HS group than in DR + HS group after the treatment period. Cystometrogram showed the intercontraction intervals (ICI were significantly shorter in DS + HS group than in DR + HS group during infusion of saline. Subsequent infusion of amiloride significantly prolonged ICI in DS + HS group, while no intra-group difference in ICI was observed in DR + HS group. No intra- or inter-group differences in maximum intravesical pressure were observed. Protein expression levels of ENaCα in the bladder were significantly higher in DS + HS group than in DR + HS group. ENaCα protein was localized at bladder epithelium in both groups. In conclusion, high salt intake is considered to cause urinary storage dysfunction via upregulation of ENaC in the bladder epithelium with salt-sensitive hypertension, suggesting that ENaC might be a candidate for therapeutic target for urinary storage dysfunction.

  10. High salt loading induces urinary storage dysfunction via upregulation of epithelial sodium channel alpha in the bladder epithelium in Dahl salt-sensitive rats.

    Science.gov (United States)

    Yamamoto, Seiji; Hotta, Yuji; Maeda, Kotomi; Kataoka, Tomoya; Maeda, Yasuhiro; Hamakawa, Takashi; Shibata, Yasuhiro; Sasaki, Shoichi; Ugawa, Shinya; Yasui, Takahiro; Kimura, Kazunori

    2017-11-01

    We aimed to investigate whether high salt intake affects bladder function via epithelial sodium channel (ENaC) by using Dahl salt-resistant (DR) and salt-sensitive (DS) rats. Bladder weight of DR + high-salt diet (HS, 8% NaCl) and DS + HS groups were significantly higher than those of DR + normal-salt diet (NS, 0.3% NaCl) and DS + NS groups after one week treatment. We thereafter used only DR + HS and DS + HS group. Systolic and diastolic blood pressures were significantly higher in DS + HS group than in DR + HS group after the treatment period. Cystometrogram showed the intercontraction intervals (ICI) were significantly shorter in DS + HS group than in DR + HS group during infusion of saline. Subsequent infusion of amiloride significantly prolonged ICI in DS + HS group, while no intra-group difference in ICI was observed in DR + HS group. No intra- or inter-group differences in maximum intravesical pressure were observed. Protein expression levels of ENaCα in the bladder were significantly higher in DS + HS group than in DR + HS group. ENaCα protein was localized at bladder epithelium in both groups. In conclusion, high salt intake is considered to cause urinary storage dysfunction via upregulation of ENaC in the bladder epithelium with salt-sensitive hypertension, suggesting that ENaC might be a candidate for therapeutic target for urinary storage dysfunction. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  11. A Novel Mechanism in Regulating the Alpha-Subunit of the Epithelial Sodium Channel (α ENaC by the Alternatively Spliced Form α ENaC-b

    Directory of Open Access Journals (Sweden)

    Marlene F. Shehata

    2009-01-01

    Full Text Available Introduction: In Dahl rats’ kidney cortex, the alternatively spliced form of the epithelial sodium channel α subunit (α ENaC-b is the most abundant mRNA transcript (32+/-3 fold α ENaC-wt as was investigated by quantitative RT-PCR analysis. α ENaC-b mRNA levels were significantly higher in Dahl R versus S rats, and were further augmented by high salt diet.Objectives: In the present study, we described the molecular cloning and searched for a possible role of α ENaC-b by testing its potential expression in COS7 cells as well as its impact on α ENaC-wt expression levels when co-expressed in COS7 cells in a dose-dependent manner.Methods: Using RT-PCR strategy, the full-length wildtype α ENaC transcript and the alternatively spliced form α ENaC-b were amplified, sequenced, cloned, subcloned into PCMV-sport6 expression vector, expressed and co-expressed into COS7 cells in a dose-dependent manner. A combination of denaturing and native western blotting techniques was employed to examine the expression of α ENaC-b in vitro, and to determine if an interaction between α ENaC-b and α ENaC-wt occurs in vitro, and finally to demonstrate if degradation of α ENaC-wt protein does occur.Results: α ENaC-b is translated in COS7 cells. Co-expression of α ENaC-b together with α ENaC-wt reduced α ENaC-wt levels in a dose-dependent manner. α ENaC-wt and α ENaC-b appear to form a complex that enhances the degradation of α ENaC-wt.Conclusions: Western blots suggest a novel mechanism in α ENaC regulation whereby α ENaC-b exerts a dominant negative effect on α ENaC-wt expression. This is potentially by sequestering α ENaC-wt, enhancing its proteolytic degradation, and possibly explaining the mechanism of salt-resistance in Dahl R rats.

  12. Identification of the Arg1086His mutation in the alpha subunit of the voltage-dependent calcium channel (CACNA1S) in a North American family with malignant hyperthermia.

    Science.gov (United States)

    Stewart, S L; Hogan, K; Rosenberg, H; Fletcher, J E

    2001-03-01

    Individuals from a large North American population were screened for the presence of the mutation in the alpha1 subunit of the voltage-dependent calcium channel (CACNA1S) that has recently been associated with malignant hyperthermia (MH). This Arg1086His mutation was screened for in 154 MH normal (MHN) individuals and 112 MH susceptible (MHS) individuals, who were diagnosed by the North American protocol of the in vitro contracture test. PCR and restriction enzyme analysis was used to test for the mutation. The Arg1086His mutation in the CACNA1S was not found in any of the MHN individuals. In contrast, two related individuals (grandfather and grandson, father and son of the MH proband) among the MHS group exhibited this mutation. However, a third MHS individual in the same family (granddaughter, cousin of the grandson) did not exhibit this mutation. These results indicate that this mutation may be associated with MH in this family. Genetic alterations in the CACNA1S associated with MH are present in approximately 1% of this North American MHS population.

  13. Microtubule Regulation of Kv7 Channels Orchestrates cAMP-Mediated Vasorelaxations in Rat Arterial Smooth Muscle

    DEFF Research Database (Denmark)

    Lindman, Johanna; Khammy, Makhala M; Lundegaard, Pia R

    2018-01-01

    of this pathway in vascular smooth muscle cells, we investigated the role of microtubule stability on β-adrenoceptor signaling in rat renal and mesenteric arteries. In isometric tension experiments, incubation with the microtubule inhibitors colchicine and nocodazole enhanced isoprenaline-mediated relaxations...... of renal and mesenteric arteries that the microtubule stabilizer, paclitaxel, prevented. Sharp microelectrode experiments showed that colchicine treatment caused increased hyperpolarization of mesenteric artery segments in response to isoprenaline. Application of the Kv7 channel blocker, XE991, attenuated...... the effect of colchicine on isoprenaline relaxations, whereas iberiotoxin-a BKCa channel blocker-had no effect. In addition, colchicine improved the relaxations to the Kv7.2 to 7.5 activator, S-1, in both renal and mesenteric artery segments compared with dimethyl sulfoxide incubation. We determined...

  14. Channelling and channelling radiation

    International Nuclear Information System (INIS)

    Soerensen, A.H.; Uggerhoej, E.

    1987-01-01

    The study of channelling phenomena has developed rapidly since the early 1960s and today channelling has found many applications. The radiation emitted by channelled megaelectronvolt and gigaelectronvolt electrons and positrons has been investigated extensively and the possibility of, for example, constructing intense tunable X- and γ-ray sources is being explored. Multi-gigaelectronvolt radiation and pair-creation processes in single crystals show similarities with strong-field effects and are of particular interest because of high production rates that persist far beyond the channelling regime. (author)

  15. Buffett's Alpha

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Kabiller, David; Heje Pedersen, Lasse

    Berkshire Hathaway has realized a Sharpe ratio of 0.76, higher than any other stock or mutual fund with a history of more than 30 years, and Berkshire has a significant alpha to traditional risk factors. However, we find that the alpha becomes insignificant when controlling for exposures to Betting-Against-Beta...... in publicly traded stocks versus wholly-owned private companies, we find that the former performs the best, suggesting that Buffett's returns are more due to stock selection than to his effect on management. These results have broad implications for market efficiency and the implementability of academic...

  16. A remarkably stable TipE gene cluster: evolution of insect Para sodium channel auxiliary subunits

    Directory of Open Access Journals (Sweden)

    Li Jia

    2011-11-01

    Full Text Available Abstract Background First identified in fruit flies with temperature-sensitive paralysis phenotypes, the Drosophila melanogaster TipE locus encodes four voltage-gated sodium (NaV channel auxiliary subunits. This cluster of TipE-like genes on chromosome 3L, and a fifth family member on chromosome 3R, are important for the optional expression and functionality of the Para NaV channel but appear quite distinct from auxiliary subunits in vertebrates. Here, we exploited available arthropod genomic resources to trace the origin of TipE-like genes by mapping their evolutionary histories and examining their genomic architectures. Results We identified a remarkably conserved synteny block of TipE-like orthologues with well-maintained local gene arrangements from 21 insect species. Homologues in the water flea, Daphnia pulex, suggest an ancestral pancrustacean repertoire of four TipE-like genes; a subsequent gene duplication may have generated functional redundancy allowing gene losses in the silk moth and mosquitoes. Intronic nesting of the insect TipE gene cluster probably occurred following the divergence from crustaceans, but in the flour beetle and silk moth genomes the clusters apparently escaped from nesting. Across Pancrustacea, TipE gene family members have experienced intronic nesting, escape from nesting, retrotransposition, translocation, and gene loss events while generally maintaining their local gene neighbourhoods. D. melanogaster TipE-like genes exhibit coordinated spatial and temporal regulation of expression distinct from their host gene but well-correlated with their regulatory target, the Para NaV channel, suggesting that functional constraints may preserve the TipE gene cluster. We identified homology between TipE-like NaV channel regulators and vertebrate Slo-beta auxiliary subunits of big-conductance calcium-activated potassium (BKCa channels, which suggests that ion channel regulatory partners have evolved distinct lineage

  17. ([alpha]S,Z,1R,3R)-[4'4''-[sup 3]H]cyhalothrin and -[4'',6'-[sup 3]H]4'-fluorocyhalothrin: synthesis of candidate pyrethroid radioligands for the sodium channel

    Energy Technology Data Exchange (ETDEWEB)

    Latli, Bachir; Greenfield, L.J.; Casida, J.E. (California Univ., Berkeley, CA (United States). Dept. of Entomological Sciences)

    1993-07-01

    ([alpha]S, Z, 1R, 3R)-Cyhalothrin (1) and ([alpha]S, Z, 1R, 3R)-4'-fluoro-cyhalothrin (2), highly potent insecticides, were selected as candidate radioligands for studies on pyrethroid-sodium channel interactions. This report describes the synthesis of dihalo derivatives of 1 and 2 and their reductive dehalogenation to the corresponding deuterium- and tritium-labelled pyrethroids. Thus, reduction of 4'', 6' -dibromo-2 with deuterium gas, platinum oxide and potassium carbonate in ethyl acetate went quantitatively to [4'', 6'-[sup 2]H]-2; however, the use of tritium instead of deuterium failed to yield [4'', 6'-[sup 3]H]-2 giving instead decomposed materials. Fortunately the use of the iodo compounds 4'', 4' -diiodo-1 and 4'', 6' -diiodo-2 with tritium gas and palladium on carbon in absolute ethanol gave [4'', 4' -[sup 3]H]-2 in near quantitative yields at 55 Ci/mmol. (Author).

  18. Coulomb correction to elastic. alpha. -. alpha. scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bera, P.K.; Jana, A.K.; Haque, N.; Talukdar, B. (Department of Physics, Visva-Bharati University, Santiniketan-731235, West Bengal, India (IN))

    1991-02-01

    The elastic {alpha}-{alpha} scattering is treated within the framework of a generalized phase-function method (GPFM). This generalization consists in absorbing the effect of Coulomb interaction in the comparison functions for developing the phase equation. Based on values of scattering phase shifts computed by the present method, it is concluded that the GPFM provides an uncomplicated approach to rigorous Coulomb correction in the {alpha}-{alpha} scattering.

  19. Intrahepatic expression of interferon alpha & interferon alpha ...

    African Journals Online (AJOL)

    kemrilib

    Alpha m-RNA while 30% only expressed Interferon Alpha Receptor m-RNA. Responders and non-responders to Interferon therapy ... expression of IFN Alpha Receptor mRNA. Regardless of the response to interferon, histological .... generation reverse hybridisation, line probe assay. (Inno-LiPA HCV II; Innogenetics, Ghent,.

  20. Antillatoxin is a sodium channel activator that displays unique efficacy in heterologously expressed rNav1.2, rNav1.4 and rNav1.5 alpha subunits

    Directory of Open Access Journals (Sweden)

    Gerwick William H

    2010-12-01

    Full Text Available Abstract Background Antillatoxin (ATX is a structurally unique lipopeptide produced by the marine cyanobacterium Lyngbya majuscula. ATX activates voltage-gated sodium channel α-subunits at an undefined recognition site and stimulates sodium influx in neurons. However, the pharmacological properties and selectivity of ATX on the sodium channel α-subunits were not fully characterized. Results In this study, we characterized the pharmacological properties and selectivity of ATX in cells heterologously expressing rNav1.2, rNav1.4 or rNav1.5 α-subunits by using the Na+ selective fluorescent dye, sodium-binding benzofuran isophthalate. ATX produced sodium influx in cells expressing each sodium channel α-subunit, whereas two other sodium channel activators, veratridine and brevetoxin-2, were without effect. The ATX potency at rNav1.2, rNav1.4 and rNav1.5 did not differ significantly. Similarly, there were no significant differences in the efficacy for ATX-induced sodium influx between rNav1.2, rNav1.4 and rNav1.5 α-subunits. ATX also produced robust Ca2+ influx relative to other sodium channel activators in the calcium-permeable DEAA mutant of rNav1.4 α-subunit. Finally, we demonstrated that the 8-demethyl-8,9-dihydro-antillatoxin analog was less efficacious and less potent in stimulating sodium influx. Conclusions ATX displayed a unique efficacy with respect to stimulation of sodium influx in cells expressing rNav1.2, rNav1.4 and rNav1.5 α-subunits. The efficacy of ATX was distinctive inasmuch as it was not shared by activators of neurotoxin sites 2 and 5 on VGSC α-subunits. Given the unique pharmacological properties of ATX interaction with sodium channel α-subunits, decoding the molecular determinants and mechanism of action of antillatoxin may provide further insight into sodium channel gating mechanisms.

  1. Insulin induces relaxation and decreases hydrogen peroxide-induced vasoconstriction in human placental vascular bed in a mechanism mediated by calcium-activated potassium channels and L-arginine/nitric oxide pathways.

    Directory of Open Access Journals (Sweden)

    Lissette Cabrera

    2016-11-01

    Full Text Available Insulin induces relaxation in umbilical veins, increasing the expression of human amino acid transporter 1 (hCAT-1 and nitric oxide synthesis (NO in human umbilical vein endothelial cells (HUVECs. Short-term effects of insulin on vasculature have been reported in healthy subjects and cell cultures; however, its mechanisms remain unknown. The aim of this study was to characterize the effect of acute incubation with insulin on the regulation of vascular tone of placental vasculature. HUVECs and chorionic vein rings were isolated from normal pregnancies. The effect of insulin on NO synthesis, L-arginine transport and hCAT-1 abundance was measured in HUVECs. Isometric tension induced by U46619 (thromboxane A2 analogue or hydrogen peroxide (H2O2 were measured in vessels previously incubated 30 min with insulin and/or the following pharmacological inhibitors: tetraethylammonium (KCa channels, iberiotoxin (BKCa channels, genistein (tyrosine kinases and wortmannin (phosphatidylinositol 3-kinase. Insulin increases L-arginine transport and NO synthesis in HUVECs. In the placenta, this hormone caused relaxation of the chorionic vein and reduced perfusion pressure in placental cotyledons. In vessels pre-incubated with insulin, the constriction evoked by H2O2 and U46619 was attenuated and the effect on H2O2-induced constriction was blocked with tetraethylammonium and iberiotoxin, but not with genistein or wortmannin. Insulin rapidly dilates the placental vasculature through a mechanism involving activity of BKCa channels and L-arginine/NO pathway in endothelial cells. This phenomenon is related to quick increases of hCAT-1 abundance and higher capacity of endothelial cells to take up L-arginine and generate NO.

  2. Vascular smooth muscle cells express the alpha(1A) subunit of a P-/Q-type voltage-dependent Ca(2+)Channel, and It is functionally important in renal afferent arterioles

    DEFF Research Database (Denmark)

    Hansen, Pernille B. Lærkegaard; Jensen, Boye L.; Andreasen, D

    2000-01-01

    in rat aorta, brain, aortic smooth muscle cells (A7r5), VSMCs, and mesangial cells. Immunolabeling with an anti-alpha(1A) antibody was positive in acid-macerated, microdissected preglomerular vessels and in A7r5 cells. Patch-clamp experiments on aortic A7r5 cells showed 22+/-4% (n=6) inhibition of inward...... Ca(2+) current by omega-Agatoxin IVA (10(-8) mol/L), which in this concentration is a specific inhibitor of P-type VDCCs. Measurements of intracellular Ca(2+) in afferent arterioles with fluorescence-imaging microscopy showed 32+/-9% (n=10) inhibition of the K(+)-induced rise in Ca(2......+) in the presence of 10(-8) mol/L omega-Agatoxin IVA. In microperfused rabbit afferent arterioles, omega-Agatoxin IVA inhibited depolarization-mediated contraction with an EC(50) of 10(-17) mol/L and complete blockade at 10(-14) mol/L. We conclude that the alpha(1A) subunit is expressed in VSMCs from renal...

  3. Ion channeling

    International Nuclear Information System (INIS)

    Erramli, H.; Blondiaux, G.

    1994-01-01

    Channeling phenomenon was predicted, many years ago, by stark. The first channeling experiments were performed in 1963 by Davies and his coworkers. Parallely Robinson and Oen have investigated this process by simulating trajectories of ions in monocrystals. This technique has been combined with many methods like Rutherford Backscattering Spectrometry (R.B.S.), Particles Induced X-rays Emission (P.I.X.E) and online Nuclear Reaction (N.R.A.) to localize trace elements in the crystal or to determine crystalline quality. To use channeling for material characterization we need data about the stopping power of the incident particle in the channeled direction. The ratios of channeled to random stopping powers of silicon for irradiation in the direction have been investigated and compared to the available theoretical results. We describe few applications of ion channeling in the field of materials characterization. Special attention is given to ion channeling combined with Charged Particle Activation Analysis (C.P.A.A.) for studying the behaviour of oxygen atoms in Czochralski silicon lattices under the influence of internal gettering and in different gaseous atmospheres. Association between ion channeling and C.P.A.A was also utilised for studying the influence of the growing conditions on concentration and position of carbon atoms at trace levels in the MOVPE Ga sub (1-x) Al sub x lattice. 6 figs., 1 tab., 32 refs. (author)

  4. Non stochastic distribution of single channels in planar lipid bilayers.

    Science.gov (United States)

    Krasilnikov, O V; Merzliak, P G; Yuldasheva, L N; Nogueira, R A; Rodrigues, C G

    1995-02-15

    The selectivity of the planar lipid bilayers modified by two channel-forming proteins (alpha-toxin S. aureus and colicin Ia) was examined. It was established that in all cases the value of zero current potential depended on the amount of open ion channels and increased with the number of channels (from one to about 5-7). These facts point out both the interactions among ion channels and their non stochastic distribution on the membrane surface.

  5. The determination of $\\alpha_s$ by the ALPHA collaboration

    CERN Document Server

    Bruno, Mattia

    2016-01-01

    We review the ALPHA collaboration strategy for obtaining the QCD coupling at high scale. In the three-flavor effective theory it avoids the use of perturbation theory at $\\alpha > 0.2$ and at the same time has the physical scales small compared to the cutoff $1/a$ in all stages of the computation. The result $\\Lambda_\\overline{MS}^{(3)}=332(14)$~MeV is translated to $\\alpha_\\overline{MS}(m_Z)=0.1179(10)(2)$ by use of (high order) perturbative relations between the effective theory couplings at the charm and beauty quark "thresholds". The error of this perturbative step is discussed and estimated as $0.0002$.

  6. Nicotine enhances expression of the alpha 3, alpha 4, alpha 5, and alpha 7 nicotinic receptors modulating calcium metabolism and regulating adhesion and motility of respiratory epithelial cells.

    Science.gov (United States)

    Zia, S; Ndoye, A; Nguyen, V T; Grando, S A

    1997-09-01

    The purpose of this study was to investigate the possibility of direct toxic effects of nicotine (Nic) on human bronchial epithelial cells (BEC) suggested by our previous findings of functional nicotinic acetylcholine receptors (nAChRs) in the epithelial cells lining mucocutaneous membranes. We now demonstrate for the first time that human and murine BEC both in vivo and in vitro express functional nAChRs, and that classic alpha 3, alpha 4, alpha 5 and alpha 7 subunits can contribute to formation of these acetylcholine-gated ion channels. In human bronchial and mouse lung tissues, and in cultures of human BEC, the nAChRs were visualized by subunit-specific antibodies on the cell membranes, particularly at the sites of cell-to-cell contacts. The epithelial cells of submucosal glands abundantly expressed alpha 7 nAChRs. Smoking significantly (p epithelial nAChRs apparently involve regulation of cell-to-cell communications, adhesion and motility, because Mec caused rapid and profound changes in these cell functions which were reversible by Nic. An over exposure of BEC to Nic, however, produced an antagonist-like effect, suggesting that the pathobiological effects of Nic toxicity might result from both activation of nAChR channels and nAChR desensitization. We conclude that medical consequences of smoking can be mediated by direct toxic effects of inhaled Nic on the respiratory tissues wherein Nic specifically binds to and activates the nicotinic ion channels present on the cell surfaces of BEC. We believe that outside the neural system Nic interferes with functioning of non-neuronal cholinergic networks by displacing from nAChR its natural ligand acetylcholine which acts as a local hormone or cytokine in a variety of non-neuronal locations.

  7. Lyman Alpha Control

    CERN Document Server

    Nielsen, Daniel Stefaniak

    2015-01-01

    This document gives an overview of how to operate the Lyman Alpha Control application written in LabVIEW along with things to watch out for. Overview of the LabVIEW code itself as well as the physical wiring of and connections from/to the NI PCI-6229 DAQ box is also included. The Lyman Alpha Control application is the interface between the ALPHA sequencer and the HighFinesse Wavelength Meter as well as the Lyman Alpha laser setup. The application measures the wavelength of the output light from the Lyman Alpha cavity through the Wavelength Meter. The application can use the Wavelength Meter’s PID capabilities to stabilize the Lyman Alpha laser output as well as switch between up to three frequencies.

  8. New ALPHA-2 magnet

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    On 21 June, members of the ALPHA collaboration celebrated the handover of the first solenoid designed for the ALPHA-2 experiment. The magnet has since been successfully installed and is working well.   Khalid Mansoor, Sumera Yamin and Jeffrey Hangst in front of the new ALPHA-2 solenoid. “This was the first of three identical solenoids that will be installed between now and September, as the rest of the ALPHA-2 device is installed and commissioned,” explains ALPHA spokesperson Jeffrey Hangst. “These magnets are designed to allow us to transfer particles - antiprotons, electrons and positrons - between various parts of the new ALPHA-2 device by controlling the transverse size of the particle bunch that is being transferred.” Sumera Yamin and Khalid Mansoor, two Pakistani scientists from the National Centre for Physics in Islamabad, came to CERN in February specifically to design and manufacture these magnets. “We had the chance to work on act...

  9. Alpha Shapes and Proteins

    DEFF Research Database (Denmark)

    Winter, Pawel; Sterner, Henrik; Sterner, Peter

    2009-01-01

    We provide a unified description of (weighted) alpha shapes, beta shapes and the corresponding simplicialcomplexes. We discuss their applicability to various protein-related problems. We also discuss filtrations of alpha shapes and touch upon related persistence issues.We claim that the full...... potential of alpha-shapes and related geometrical constructs in protein-related problems yet remains to be realized and verified. We suggest parallel algorithms for (weighted) alpha shapes, and we argue that future use of filtrations and kinetic variants for larger proteins will need such implementation....

  10. MARKETING CHANNELS

    Directory of Open Access Journals (Sweden)

    Ljiljana Stošić Mihajlović

    2014-07-01

    Full Text Available Marketing channel is a set of entities and institutions, completion of distribution and marketing activities, attend the efficient and effective networking of producers and consumers. Marketing channels include the total flows of goods, money and information taking place between the institutions in the system of marketing, establishing a connection between them. The functions of the exchange, the physical supply and service activities, inherent in the system of marketing and trade. They represent paths which products and services are moving after the production, which will ultimately end up buying and eating by the user.

  11. Targeted Alpha Therapy: From Alpha to Omega

    International Nuclear Information System (INIS)

    Allen, Barry J; Clarke, Raymond; Huang Chenyu

    2013-01-01

    This review covers the broad spectrum of Targeted Alpha Therapy (TAT) research in Australia; from in vitro and in vivo studies to clinical trials. The principle of tumour anti-vascular alpha therapy (TAVAT) is discussed in terms of its validation by Monte Carlo calculations of vascular models and the potential role of biological dosimetry is examined. Summmary of this review is as follows: 1. The essence of TAT 2. Therapeutic objectives 3. TAVAT and Monte Carlo microdosimetry 4. Biological dosimetry 5. Preclinical studies 6. Clinical trials 7. What next? 8. Obstacles. (author)

  12. Alpha1-antitrypsin deficiency

    DEFF Research Database (Denmark)

    Stolk, Jan; Seersholm, Niels; Kalsheker, Noor

    2006-01-01

    The Alpha One International Registry (AIR), a multinational research program focused on alpha1-antitrypsin (AAT) deficiency, was formed in response to a World Health Organization recommendation. Each of the nearly 20 participating countries maintains a national registry of patients with AAT defic...... epidemiology, inflammatory and signalling processes, therapeutic advances, and lung imaging techniques....

  13. Alpha clustering in nuclei

    International Nuclear Information System (INIS)

    Hodgson, P.E.

    1990-01-01

    The effects of nucleon clustering in nuclei are described, with reference to both nuclear structure and nuclear reactions, and the advantages of using the cluster formalism to describe a range of phenomena are discussed. It is shown that bound and scattering alpha-particle states can be described in a unified way using an energy-dependent alpha-nucleus potential. (author)

  14. Fermi Liquid Instabilities in the Spin Channel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Congjun; /Santa Barbara, KITP; Sun, Kai; Fradkin, Eduardo; /Illinois U., Urbana; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-16

    We study the Fermi surface instabilities of the Pomeranchuk type in the spin triplet channel with high orbital partial waves (F{sub l}{sup a} (l > 0)). The ordered phases are classified into two classes, dubbed the {alpha} and {beta}-phases by analogy to the superfluid {sup 3}He-A and B-phases. The Fermi surfaces in the {alpha}-phases exhibit spontaneous anisotropic distortions, while those in the {beta}-phases remain circular or spherical with topologically non-trivial spin configurations in momentum space. In the {alpha}-phase, the Goldstone modes in the density channel exhibit anisotropic overdamping. The Goldstone modes in the spin channel have nearly isotropic underdamped dispersion relation at small propagating wavevectors. Due to the coupling to the Goldstone modes, the spin wave spectrum develops resonance peaks in both the {alpha} and {beta}-phases, which can be detected in inelastic neutron scattering experiments. In the p-wave channel {beta}-phase, a chiral ground state inhomogeneity is spontaneously generated due to a Lifshitz-like instability in the originally nonchiral systems. Possible experiments to detect these phases are discussed.

  15. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

  16. Diagnostics for PLX-alpha

    Science.gov (United States)

    Gilmore, Mark; Hsu, Scott

    2015-11-01

    The goal of the Plasma Liner eXperiment PLX-alpha at Los Alamos National Laboratory is to establish the viability of creating a spherically imploding plasma liner for MIF and HED applications, using a spherical array of supersonic plasma jets launched by innovative contoured-gap coaxial plasma guns. PLX- α experiments will focus in particular on establishing the ram pressure and uniformity scalings of partial and fully spherical plasma liners. In order to characterize these parameters experimentally, a suite of diagnostics is planned, including multi-camera fast imaging, a 16-channel visible interferometer (upgraded from 8 channels) with reconfigurable, fiber-coupled front end, and visible and VUV high-resolution and survey spectroscopy. Tomographic reconstruction and data fusion techniques will be used in conjunction with interferometry, imaging, and synthetic diagnostics from modeling to characterize liner uniformity in 3D. Diagnostic and data analysis design, implementation, and status will be presented. Supported by the Advanced Research Projects Agency - Energy - U.S. Department of Energy.

  17. [alpha-Latrotoxin as an instrument for studying neurosecretions].

    Science.gov (United States)

    Himmel'reĭkh, N H

    2000-01-01

    alpha-Latrotoxin, a presynaptic toxin from black widow spider venom Latrodectus mactans tredecimguttatus, triggers exocytosis in a variety of neurosecretory cells both in the presence and absence of calcium in the medium. The toxin interacts with two types of membrane the receptors which belong to different families of neuronal proteins and have different structures. Calcium-dependent receptor of alpha-latrotoxin is identified as neurexin I alpha and belongs to the family of neurexins. This family is selectively expressed in nerve tissue. The calcium-independent receptor of alpha-latrotoxin belongs to the family of G-protein-coupled receptors and proteins which homologous to it are found in heart, lung, kidney and spleen tissues. As a result of alpha-latrotoxin interaction with membrane receptor in the calcium medium the toxin forms the ionic channels in plasmalemma and enhances its calcium permeability. The effects of alpha-latrotoxin on exocytosis in the calcium and calcium-free media and question concerning coupling of channel-forming and secretogenic properties of alpha-latrotoxin are discussed.

  18. Genetics Home Reference: alpha thalassemia

    Science.gov (United States)

    ... Facebook Twitter Home Health Conditions Alpha thalassemia Alpha thalassemia Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Alpha thalassemia is a blood disorder that reduces the production ...

  19. Starburst Channels

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1 Translucent carbon dioxide ice covers the polar regions of Mars seasonally. It is warmed and sublimates (evaporates) from below, and escaping gas carves a numerous channel morphologies. In this example (figure 1) the channels form a 'starburst' pattern, radiating out into feathery extensions. The center of the pattern is being buried with dust and new darker dust fans ring the outer edges. This may be an example of an expanding morphology, where new channels are formed as the older ones fill and are no longer efficiently channeling the subliming gas out. Observation Geometry Image PSP_003443_0980 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 21-Apr-2007. The complete image is centered at -81.8 degrees latitude, 76.2 degrees East longitude. The range to the target site was 247.1 km (154.4 miles). At this distance the image scale is 24.7 cm/pixel (with 1 x 1 binning) so objects 74 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel. The image was taken at a local Mars time of 04:52 PM and the scene is illuminated from the west with a solar incidence angle of 71 degrees, thus the sun was about 19 degrees above the horizon. At a solar longitude of 223.4 degrees, the season on Mars is Northern Autumn.

  20. Excitation functions for alpha-particle-induced reactions with natural antimony

    Energy Technology Data Exchange (ETDEWEB)

    Singh, N. L.; Shah, D. J.; Mukherjee, S.; Chintalapudi, S. N. [Vadodara, M. S. Univ. of Baroda (India). Fac. of Science. Dept. of Physics

    1997-07-01

    Stacked-foil activation technique and {gamma} - rays spectroscopy were used for the determination of the excitation functions of the {sup 121}Sb [({alpha}, n); ({alpha}, 2n); ({alpha},4 n); ({alpha}, p3n); ({alpha}, {alpha}n)]; and Sb [({alpha}, 3n); ({alpha}, 4n); ({alpha}, {alpha}3n)] reactions. The excitation functions for the production of {sup 124}I, {sup 123}I, {sup 121}I, {sup 121}Te and {sup 120}Sb were reported up to 50 MeV. The reactions {sup 121} Sb ({alpha}, {alpha}n) + {sup 123} Sb ({alpha}, {alpha}3n) are measured for the first time. Since natural antimony used as the target has two odd mass stable isotopes of abundances 57.3 % ({sup 121}Sb), their activation in some cases gives the same product nucleus through different reaction channels but with very different Q-values. In such cases, the individual reaction cross-sections are separated with the help of theoretical cross-sections. The experimental cross-sections were compared with the predictions based on hybrid model of Blann. The high-energy part of the excitation functions are dominated by the pre-equilibrium reaction mechanism and the initial exciton number n{sub 0} = 4 (4 p 0 h) gives fairly good agreement with presently measured results.

  1. Alpha Thalassemia (For Parents)

    Science.gov (United States)

    ... the body has a problem producing alpha globin Beta thalassemia : when the body has a problem producing beta ... Transfusion Blood Test: Hemoglobin Electrophoresis Sickle Cell Disease Beta Thalassemia Blood All About Genetics Prenatal Genetic Counseling Genetic ...

  2. ALPHA-2: the sequel

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    While many experiments are methodically planning for intense works over the long shutdown, there is one experiment that is already working at full steam: ALPHA-2. Its final components arrived last month and will completely replace the previous ALPHA set-up. Unlike its predecessor, this next generation experiment has been specifically designed to measure the properties of antimatter.   The ALPHA team lower the new superconducting solenoid magnet into place. The ALPHA collaboration is working at full speed to complete the ALPHA-2 set-up for mid-November – this will give them a few weeks of running before the AD shutdown on 17 December. “We really want to get some experience with this device this year so that, if we need to make any changes, we will have time during the long shutdown in which to make them,” says Jeffrey Hangst, ALPHA spokesperson. “Rather than starting the 2014 run in the commissioning stage, we will be up and running from the get go.&...

  3. Expression of triplicated and quadruplicated alpha globin genes in sheep.

    Science.gov (United States)

    Vestri, R; Pieragostini, E; Yang, F; di Gregorio, P; Rando, A; Masina, P

    1991-01-01

    In the sheep alpha alpha alpha globin gene haplotype, the three genes display from the 5' to the 3' end the percentage efficiencies of about 30:14:6, as indicated by the amounts of the three types of alpha chain produced in the alpha alpha alpha/alpha alpha alpha homozygotes. The 3' gene in the alpha alpha alpha alpha haplotype appears to have an efficiency around 1%, as suggested by analysis of one quadruple alpha homozygote. Moreover, the total outputs of the alpha alpha alpha as well as of the alpha alpha alpha alpha haplotypes do not substantially differ from that of the common alpha alpha haplotype.

  4. Polyunsaturated fatty acids modify the gating of Kv channels

    Directory of Open Access Journals (Sweden)

    Cristina eMoreno

    2012-09-01

    Full Text Available Polyunsaturated fatty acids (PUFAs have been reported to exhibit antiarrhythmic properties, which are attributed to their capability to modulate ion channels. This PUFAs ability has been reported to be due to their effects on the gating properties of ion channels. In the present review, we will focus on the role of PUFAs on the gating of two Kv channels, Kv1.5 and Kv11.1. Kv1.5 channels are blocked by n-3 PUFAs of marine (docosahexaenoic and eicosapentaenoic acid, DHA and EPA and plant origin (alpha-linolenic acid, ALA at physiological concentrations. The blockade of Kv1.5 channels by PUFAs steeply increased in the range of membrane potentials coinciding with those of Kv1.5 channel activation, suggesting that PUFAs-channel binding may derive a significant fraction of its voltage sensitivity through the coupling to channel gating. A similar shift in the activation voltage was noted for the effects of arachidonic acid (AA and DHA on Kv1.1, Kv1.2, and Kv11.1 channels. PUFAs-Kv1.5 channel interaction is time-dependent, producing a fast decay of the current upon depolarization. Thus, Kv1.5 channel opening is a prerequisite for the PUFA-channel interaction. Similar to the Kv1.5 channels, the blockade of Kv11.1 channels by AA and DHA steeply increased in the range of membrane potentials that coincided with the range of Kv11.1 channel activation, suggesting that the PUFAs-Kv channel interactions are also coupled to channel gating. Furthermore, AA regulates the inactivation process in other Kv channels, introducing a fast voltage-dependent inactivation in non-inactivating Kv channels. These results have been explained within the framework that AA closes voltage-dependent potassium channels by inducing conformational changes in the selectivity filter, suggesting that Kv channel gating is lipid dependent.

  5. Evidence for the Inhibition by Temozolomide, an Imidazotetrazine Family Alkylator, of Intermediate-Conductance Ca2+-Activated K+ Channels in Glioma Cells

    Directory of Open Access Journals (Sweden)

    Poh-Shiow Yeh

    2016-05-01

    Full Text Available Background: Temozolomide (TMZ, an oral alkylator of the imidazotetrazine family, is used to treat glioma. Whether this drug has any ionic effects in glioma cells remains largely unclear. Methods: With the aid of patch-clamp technology, we investigated the effects of TMZ on the ionic currents in U373 glioma cells. The mRNA expression of KCNN4 (KCa3.1 in U373 glioma cells and TMZ's effect on K+ currents in these KCNN4 siRNA-transfected U373 cells were investigated. Results: In whole-cell recordings, TMZ decreased the amplitude of voltage-dependent K+ currents (IK in U373 cells. TMZ-induced IK inhibition was reversed by ionomycin or 1-ethyl-2-benzimidazolinone (1-EBIO. In cell-attached configuration, TMZ concentration-dependently reduced the activity of intermediate-conductance Ca2+-activated K+ (IKCa channels with an IC50 value of 9.2 µM. Chlorzoxazone or 1-EBIO counteracted the TMZ-induced inhibition of IKCa channels. Although TMZ was unable to modify single-channel conductance, its inhibition of IKCa channels was weakly voltage-dependent and accompanied by a significant prolongation in the slow component of mean closed time. However, neitherlarge-conductance Ca2+-activated (BKCa nor inwardly rectifying K+ (Kir channels were affected by TMZ. In current-clamp mode, TMZ depolarized the cell membrane and 1-EBIO reversed TMZ-induced depolarization. TMZ had no effect on IK in KCNN4 siRNA-transfected U373 cells. Conclusion: In addition to the DNA damage it does, its inhibitory effect on IKCa channels accompanied by membrane depolarization could be an important mechanism underlying TMZ-induced antineoplastic actions.

  6. Differential expression of gill Na+,K+-ATPase alpha- and beta-subunits, Na+,K+,2Cl- cotransporter and CFTR anion channel in juvenile anadromous and landlocked Atlantic salmon Salmo salar

    DEFF Research Database (Denmark)

    Nilsen, Tom O.; Ebbesson, Lars O. E.; Madsen, Steffen S.

    2007-01-01

    June, whereas alpha1a levels in landlocked salmon, after an initial decrease in April, remained significantly higher than those of the anadromous smolts in May and June. Following SW transfer, gill NKA-alpha1b and NKCC mRNA increased in both strains, whereas NKA-alpha1a decreased. Both strains......) and NKCC mRNA levels in anadromous salmon increased transiently, reaching peak levels in smolts in April/May, whereas no similar smolt-related upregulation of these transcripts occurred in juvenile landlocked salmon. Gill NKA-alpha1a mRNA decreased significantly in anadromous salmon from February through...... exhibited a transient increase in gill NKA alpha-protein abundance, with peak levels in May. Gill alpha-protein abundance was lower in SW than corresponding FW values in June. Gill NKCC protein abundance increased transiently in anadromous fish, with peak levels in May, whereas a slight increase...

  7. Monte Carlo alpha calculation

    Energy Technology Data Exchange (ETDEWEB)

    Brockway, D.; Soran, P.; Whalen, P.

    1985-01-01

    A Monte Carlo algorithm to efficiently calculate static alpha eigenvalues, N = ne/sup ..cap alpha..t/, for supercritical systems has been developed and tested. A direct Monte Carlo approach to calculating a static alpha is to simply follow the buildup in time of neutrons in a supercritical system and evaluate the logarithmic derivative of the neutron population with respect to time. This procedure is expensive, and the solution is very noisy and almost useless for a system near critical. The modified approach is to convert the time-dependent problem to a static ..cap alpha../sup -/eigenvalue problem and regress ..cap alpha.. on solutions of a/sup -/ k/sup -/eigenvalue problem. In practice, this procedure is much more efficient than the direct calculation, and produces much more accurate results. Because the Monte Carlo codes are intrinsically three-dimensional and use elaborate continuous-energy cross sections, this technique is now used as a standard for evaluating other calculational techniques in odd geometries or with group cross sections.

  8. Monte Carlo alpha deposition

    International Nuclear Information System (INIS)

    Talley, T.L.; Evans, F.

    1988-01-01

    Prior work demonstrated the importance of nuclear scattering to fusion product energy deposition in hot plasmas. This suggests careful examination of nuclear physics details in burning plasma simulations. An existing Monte Carlo fast ion transport code is being expanded to be a test bed for this examination. An initial extension, the energy deposition of fast alpha particles in a hot deuterium plasma, is reported. The deposition times and deposition ranges are modified by allowing nuclear scattering. Up to 10% of the initial alpha particle energy is carried to greater ranges and times by the more mobile recoil deuterons. 4 refs., 5 figs., 2 tabs

  9. Buffett’s Alpha

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Kabiller, David; Heje Pedersen, Lasse

    Berkshire Hathaway has realized a Sharpe ratio of 0.76, higher than any other stock or mutual fund with a history of more than 30 years, and Berkshire has a significant alpha to traditional risk factors. However, we find that the alpha becomes insignificant when controlling for exposures to Betting......-Against-Beta and Quality-Minus-Junk factors. Further, we estimate that Buffett’s leverage is about 1.6-to-1 on average. Buffett’s returns appear to be neither luck nor magic, but, rather, reward for the use of leverage combined with a focus on cheap, safe, quality stocks. Decomposing Berkshires’ portfolio into ownership...

  10. Dynamic Channel Allocation

    Science.gov (United States)

    2003-09-01

    21 9. Beowulf Ethernet Channel Bonding.................................................22 F. SUMMARY...on demand, hybrid channel allocation in wireless networks, and 3 Beowulf Ethernet channel bonding. The background information presented in this...channels are available for dynamic allocation [Ref 32]. 9. Beowulf Ethernet Channel Bonding A by-product of using older computers in a NASA research lab

  11. Case Study - Alpha

    Directory of Open Access Journals (Sweden)

    Stephen Leybourne

    2016-11-01

    Full Text Available This case study was developed from an actual scenario by Dr. Steve Leybourne of Boston University.  The case documents the historical evolution of an organization, and has been used successfully in courses dealing with organizational and cultural change, and the utilization of ‘soft skills’ in project-based management. This is a short case, ideal for classroom use and discussion.  The issues are easily accessible to students, and there is a single wide ranging question that allows for the inclusion of many issues surrounding strategic decision-making, and behavioural and cultural change. Alpha was one of the earlier companies in the USA to invest in large, edge-of-town superstores, with plentiful free vehicle parking, selling food and related household products. Alpha was created in the 1950s as a subsidiary of a major publicly quoted retail group.  It started business by opening a string of very large discount stores in converted industrial and warehouse premises in the south of the United States. In the early days shoppers were offered a limited range of very competitively priced products. When Alpha went public in 1981 it was the fourth largest food retailer in the US, selling an ever-widening range of food and non-food products.  Its success continued to be based on high volume, low margins and good value for money, under the slogan of ‘Alpha Price.’

  12. Alpha-mannosidosis

    DEFF Research Database (Denmark)

    Borgwardt, Line; Stensland, Hilde Monica Frostad Riise; Olsen, Klaus Juul

    2015-01-01

    of the three subgroups of genotype/subcellular localisation and the clinical and biochemical data were done to investigate the potential relationship between genotype and phenotype in alpha-mannosidosis. Statistical analyses were performed using the SPSS software. Analyses of covariance were performed...

  13. Efficient alpha-(alkylthio)alkyl-type radical formation in (*)OH-induced oxidation of alpha-(methylthio)acetamide.

    Science.gov (United States)

    Wisniowski, Pawel B; Hug, Gordon L; Pogocki, Dariusz; Bobrowski, Krzysztof

    2010-01-14

    Pulse radiolysis with UV-vis/ESR detection and steady-state gamma-radiolysis, combined with chromatographic techniques, were used to investigate the detailed mechanism of the (*)OH-induced oxidation of alpha-(methylthio)acetamide (alpha-MTA) in aqueous solution. The main pathway involves the formation of hydroxysulfuranyl radicals alpha-MTA-(>S(*)-OH) and alpha-(alkylthio)alkyl radicals H(3)C-S-(*)CH-C( horizontal lineO)-NH(2) (lambda(max) effect of both substituents in terms of the captodative effect. At low pH, alpha-MTA-(>S(*)-OH) radicals undergo efficient conversion to intermolecularly three-electron-bonded dimeric radical cations of alpha-MTA-(>S thereforeSS(*)-OH) radicals decompose via the elimination of water, formed through intramolecular hydrogen (attached to the nitrogen atom) transfer to the hydroxysulfuranyl moiety within a six-membered structure. This process leads to the formation of the imine radical H(3)C-S-CH(2)-C( horizontal lineO)(*)NH, which subsequently decays in three independent channels. The first decay channel begins with a beta-scission followed by hydrolysis and a subsequent Hofmann rearrangement. One of the end products of this first decay channel is CO(2), which was detected. The second decay channel involves an intramolecular hydrogen transfer from the deltaC carbon atom to the radical imine site producing the alpha-(alkylthio)alkyl radical H(2)C(*)-S-CH(2)-C( horizontal lineO)-NH(2). In the third decay channel there is a 1,3-hydrogen shift in the imine radical which forms the radical H(3)C-S-(*)CH-C( horizontal lineO)-NH(2). The presence of the amide group induces more complex radical chemistry that leads unexpectedly to the degradation of the CH(3)SCH(2)CONH(2) molecule into gaseous products, CO(2) and NH(3). These features of the mechanism of the (*)OH-induced oxidation of alpha-MTA are quite different from those seen in other organic sulfides in neutral solutions.

  14. The geometry of the ionic chànnel lumen formed by alpha-latroinsectotoxin from black widow spider venom in the bilayer lipid membranes.

    Science.gov (United States)

    Shatursky, Oleg Ya; Volkova, Tatyana M; Himmelreich, Nina H; Grishin, Eugene V

    2007-11-01

    The dependence of single channel conductance formed by alpha-latroinsectotoxin (alpha-LIT) from black widow spider venom in the planar phospholipid membrane on the hydrodynamic radii of different nonelectrolytes allowed to determine the geometry of alpha-LIT water lumen. It was found that the cis- and trans-entrances of alpha-LIT channel had the same effective radii of 0.55-0.58 nm. Relatively small conductance of alpha-LIT channel (23.5+3.7 pS) in a symmetrical membrane bathing solution of 100 mM KCl (pH 7.4) may result from the constriction inside the channel with apparent radius of 0.37 nm located 32.5% of channel length away from the cis-entrance.

  15. Demystifying AlphaGo Zero as AlphaGo GAN

    OpenAIRE

    Dong, Xiao; Wu, Jiasong; Zhou, Ling

    2017-01-01

    The astonishing success of AlphaGo Zero\\cite{Silver_AlphaGo} invokes a worldwide discussion of the future of our human society with a mixed mood of hope, anxiousness, excitement and fear. We try to dymystify AlphaGo Zero by a qualitative analysis to indicate that AlphaGo Zero can be understood as a specially structured GAN system which is expected to possess an inherent good convergence property. Thus we deduct the success of AlphaGo Zero may not be a sign of a new generation of AI.

  16. $\\alpha$-Representation for QCD

    OpenAIRE

    Tuan, Richard Hong

    1998-01-01

    An $\\alpha$-parameter representation is derived for gauge field theories.It involves, relative to a scalar field theory, only constants and derivatives with respect to the $\\alpha$-parameters. Simple rules are given to obtain the $\\alpha$-representation for a Feynman graph with an arbitrary number of loops in gauge theories in the Feynman gauge.

  17. Alpha Theta Meditation: Phenomenological, neurophysiologic ...

    African Journals Online (AJOL)

    Alpha Theta Meditation: Phenomenological, neurophysiologic, mindfulness, mood, health and sport implications. ... the single alpha theta meditation was associated with elevated alpha and theta activity, as well as decrease in negative mood perceptions, especially with regard to anxiety, sadness and confusion scores.

  18. Alpha scintillation radon counting

    International Nuclear Information System (INIS)

    Lucas, H.F. Jr.

    1977-01-01

    Radon counting chambers which utilize the alpha-scintillation properties of silver activated zinc sulfide are simple to construct, have a high efficiency, and, with proper design, may be relatively insensitive to variations in the pressure or purity of the counter filling. Chambers which were constructed from glass, metal, or plastic in a wide variety of shapes and sizes were evaluated for the accuracy and the precision of the radon counting. The principles affecting the alpha-scintillation radon counting chamber design and an analytic system suitable for a large scale study of the 222 Rn and 226 Ra content of either air or other environmental samples are described. Particular note is taken of those factors which affect the accuracy and the precision of the method for monitoring radioactivity around uranium mines

  19. Combining Alphas via Bounded Regression

    Directory of Open Access Journals (Sweden)

    Zura Kakushadze

    2015-11-01

    Full Text Available We give an explicit algorithm and source code for combining alpha streams via bounded regression. In practical applications, typically, there is insufficient history to compute a sample covariance matrix (SCM for a large number of alphas. To compute alpha allocation weights, one then resorts to (weighted regression over SCM principal components. Regression often produces alpha weights with insufficient diversification and/or skewed distribution against, e.g., turnover. This can be rectified by imposing bounds on alpha weights within the regression procedure. Bounded regression can also be applied to stock and other asset portfolio construction. We discuss illustrative examples.

  20. A 16-detector alpha spectrometer using 1 multichannel analyzer

    International Nuclear Information System (INIS)

    Phillips, W.G.

    1978-01-01

    An alpha spectrometer containing 16 independent detectors and utilizing one 4096-channel multichannel analyzer (MCA) was constructed from commerically available modules. The spectrometer was designed specifically for the counting of low levels of radioactivity in environmental samples. Gated analog routing allows spectral data acquisition into 256 channel regions of the MCA memory as if each region were an independent 256-channel MCA. External live-time clocks and 50-Mhz analog-to-digital converters control timing and acquisition on each unit of eight detectors. Spectral data output is to magnetic tape in units of 256 channels each with a unique tagword. These tapes are then read and processed, and final reports are generated, by a large Control Data 6000 series computer

  1. Na+K+-ATPase activity and K+ channels differently contribute to vascular relaxation in male and female rats.

    Directory of Open Access Journals (Sweden)

    Fernanda Moura Vargas Dias

    Full Text Available Gender associated differences in vascular reactivity regulation might contribute to the low incidence of cardiovascular disease in women. Cardiovascular protection is suggested to depend on female sex hormones' effects on endothelial function and vascular tone regulation. We tested the hypothesis that potassium (K+ channels and Na+K+-ATPase may be involved in the gender-based vascular reactivity differences. Aortic rings from female and male rats were used to examine the involvement of K+ channels and Na+K+-ATPase in vascular reactivity. Acetylcholine (ACh-induced relaxation was analyzed in the presence of L-NAME (100 µM and the following K+ channels blockers: tetraethylammonium (TEA, 2 mM, 4-aminopyridine (4-AP, 5 mM, iberiotoxin (IbTX, 30 nM, apamin (0.5 µM and charybdotoxin (ChTX, 0.1 µM. The ACh-induced relaxation sensitivity was greater in the female group. After incubation with 4-AP the ACh-dependent relaxation was reduced in both groups. However, the dAUC was greater in males, suggesting that the voltage-dependent K+ channel (Kv participates more in males. Inhibition of the three types of Ca2+-activated K+ channels induced a greater reduction in Rmax in females than in males. The functional activity of the Na+K+-ATPase was evaluated by KCl-induced relaxation after L-NAME and OUA incubation. OUA reduced K+-induced relaxation in female and male groups, however, it was greater in males, suggesting a greater Na+K+-ATPase functional activity. L-NAME reduced K+-induced relaxation only in the female group, suggesting that nitric oxide (NO participates more in their functional Na+K+-ATPase activity. These results suggest that the K+ channels involved in the gender-based vascular relaxation differences are the large conductance Ca2+-activated K+ channels (BKCa in females and Kv in males and in the K+-induced relaxation and the Na+K+-ATPase vascular functional activity is greater in males.

  2. Search for entrance channel effects in compound nuclear formation

    CERN Document Server

    Maj, A; Herskind, B; Bracco, A; Camera, F; Hagemann, G; Varmette, P

    1999-01-01

    The entrance channel effect was studied for the decay of sup 1 sup 7 sup 0 W formed in fusion reactions with different beam-target combinations. The average number of emitted neutrons suggest a lower effective excitation energy in the (alpha,xn) decay channel when more mass-symmetric reaction is used, especially at the highest angular momenta. The results are in qualitative agreement with predictions of the dissipative fusion model.

  3. Molecular determinants of desensitization and assembly of the chimeric GABA(A) receptor subunits (alpha1/gamma2) and (gamma2/alpha1) in combinations with beta2 and gamma2

    DEFF Research Database (Denmark)

    Elster, L; Kristiansen, U; Pickering, D S

    2001-01-01

    Two gamma-aminobutyric acid(A) (GABA(A)) receptor chimeras were designed in order to elucidate the structural requirements for GABA(A) receptor desensitization and assembly. The (alpha1/gamma2) and (gamma2/alpha1) chimeric subunits representing the extracellular N-terminal domain of alpha1 or gam...... receptor with respect to the direct activation by pentobarbital. This suggests differences in the mechanism of channel activation for pentobarbital and GABA....

  4. Peripheral nerve injury induces trans-synaptic modification of channels, receptors and signal pathways in rat dorsal spinal cord.

    Science.gov (United States)

    Yang, Liang; Zhang, Fang-Xiong; Huang, Fen; Lu, Yin-Jing; Li, Guo-Dong; Bao, Lan; Xiao, Hua-Sheng; Zhang, Xu

    2004-02-01

    Peripheral tissue injury-induced central sensitization may result from the altered biochemical properties of spinal dorsal horn. However, peripheral nerve injury-induced modification of genes in the dorsal horn remains largely unknown. Here we identified strong changes of 14 channels, 25 receptors and 42 signal transduction related molecules in Sprague-Dawley rat dorsal spinal cord 14 days after peripheral axotomy by cDNA microarray. Twenty-nine genes were further confirmed by semiquantitative RT-PCR, Northern blotting, in situ hybridization and immunohistochemistry. These regulated genes included Ca2+ channel alpha1E and alpha2/delta1 subunits, alpha subunits for Na+ channel 1 and 6, Na+ channel beta subunit, AMAP receptor GluR3 and 4, GABAA receptor alpha5 subunit, nicotinic acetylcholine receptor alpha5 and beta2 subunits, PKC alpha, betaI and delta isozymes, JNK1-3, ERK2-3, p38 MAPK and BatK and Lyn tyrosine-protein kinases, indicating that several signal transduction pathways were activated in dorsal spinal cord by peripheral nerve injury. These results demonstrate that peripheral nerve injury causes phenotypic changes in spinal dorsal horn. Increases in Ca2+ channel alpha2/delta1 subunit, GABAA receptor alpha5 subunit, Na+ channels and nicotinic acetylcholine receptors in both dorsal spinal cord and dorsal root ganglia indicate their potential roles in neuropathic pain control.

  5. Automated multispectra alpha spectrometer and data reduction system

    International Nuclear Information System (INIS)

    Hochel, R.C.

    1975-12-01

    A complete hardware and software package for the accumulation and rapid analysis of multiple alpha pulse height spectra has been developed. The system utilizes a 4096-channel analyzer capable of accepting up to sixteen inputs from solid-state surface barrier detectors via mixer-router modules. The analyzer is interfaced to a desk-top programmable calculator and thermal line printer. A chained software package including spectrum printout, peak analysis, plutonium-238 and plutonium-239 data reduction, and automatic energy calibration routines was written. With the chained program a complete printout, peak analysis, and plutonium data reduction of a 512-channel alpha spectrum are obtained in about three minutes with an accuracy within five percent of hand analyses

  6. Treatment of alpha bearing wastes

    International Nuclear Information System (INIS)

    1988-01-01

    This report deals with the current state of the art of alpha waste treatment, which is an integral part of the overall nuclear waste management system. The International Atomic Energy Agency (IAEA) defines alpha bearing waste as 'waste containing one or more alpha emitting radionuclides, usually actinides, in quantities above acceptable limits'. The limits are established by national regulatory bodies. The limits above which wastes are considered as alpha contaminated refer to the concentrations of alpha emitters that need special consideration for occupational exposures and/or potential safety, health, or environmental impact during one or more steps from generation through disposal. Owing to the widespread use of waste segregation by source - that is, based upon the 'suspect origin' of the material - significant volumes of waste are being handled as alpha contaminated which, in fact, do not require such consideration by reason of risk or environmental concern. The quantification of de minimis concepts by national regulatory bodies could largely contribute to the safe reduction of waste volumes and associated costs. Other factors which could significantly contribute to the reduction of alpha waste arisings are an increased application of assaying and sorting, instrumentation and the use of feedback mechanisms to control or modify the processes which generate these wastes. Alpha bearing wastes are generated during fabrication and reprocessing of nuclear fuels, decommissioning of alpha contaminated facilities, and other activities. Most alpha wastes are contact handled, but a small portion may require shielding or remote handling because of high levels of neutron (n), beta (β), or gamma (γ) emissions associated with the waste material. This report describes the sources and characteristics of alpha wastes and strategies for alpha waste management. General descriptions of treatment processes for solid and liquid alpha wastes are included. 71 refs, 14 figs, 9 tabs

  7. The alpha effect

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    Much of the recent interest in RAM system reliability stems from concern over alpha particle soft error rates reported for the initial 64 k RAMs. With increasing memory density likely in the next few years the problem of soft errors is rearing its head again. A few years ago ITT carried out experiments on 16k RAMs and found no significant problems. However, recent tests have shown a raise in the number of soft errors with 64k RAMs, and the launch of 256k and 512k memories is likely to make the problem acute

  8. Alpha-mannosidosis

    Directory of Open Access Journals (Sweden)

    Nilssen Øivind

    2008-07-01

    Full Text Available Abstract Alpha-mannosidosis is an inherited lysosomal storage disorder characterized by immune deficiency, facial and skeletal abnormalities, hearing impairment, and intellectual disability. It occurs in approximately 1 of 500,000 live births. The children are often born apparently normal, and their condition worsens progressively. Some children are born with ankle equinus or develop hydrocephalus in the first year of life. Main features are immune deficiency (manifested by recurrent infections, especially in the first decade of life, skeletal abnormalities (mild-to-moderate dysostosis multiplex, scoliosis and deformation of the sternum, hearing impairment (moderate-to-severe sensorineural hearing loss, gradual impairment of mental functions and speech, and often, periods of psychosis. Associated motor function disturbances include muscular weakness, joint abnormalities and ataxia. The facial trait include large head with prominent forehead, rounded eyebrows, flattened nasal bridge, macroglossia, widely spaced teeth, and prognathism. Slight strabismus is common. The clinical variability is significant, representing a continuum in severity. The disorder is caused by lysosomal alpha-mannosidase deficiency. Alpha-mannosidosis is inherited in an autosomal recessive fashion and is caused by mutations in the MAN2B1 gene located on chromosome 19 (19 p13.2-q12. Diagnosis is made by measuring acid alpha-mannosidase activity in leukocytes or other nucleated cells and can be confirmed by genetic testing. Elevated urinary secretion of mannose-rich oligosaccharides is suggestive, but not diagnostic. Differential diagnoses are mainly the other lysosomal storage diseases like the mucopolysaccharidoses. Genetic counseling should be given to explain the nature of the disease and to detect carriers. Antenatal diagnosis is possible, based on both biochemical and genetic methods. The management should be pro-active, preventing complications and treating

  9. Inhibition of large conductance calcium-dependent potassium ...

    African Journals Online (AJOL)

    Furthermore, in the presence of Y-27632, addition of active Rho-kinase had no effect on PKG-stimulated BKCa channel activity. Taken together, our data suggest that Rho-kinase negatively regulates BKCa channels, thus providing a novel mechanism though which Rho-kinase increases smooth muscle contraction.

  10. New Channels, New Possibilities

    DEFF Research Database (Denmark)

    Pieterson, Willem; Ebbers, Wolfgang; Østergaard Madsen, Christian

    2017-01-01

    In this contribution we discuss the characteristics of what we call the fourth generation of public sector service channels: social robots. Based on a review of relevant literature we discuss their characteristics and place into multi-channel models of service delivery. We argue that social robots...... is not one homogenous type of channels, but rather breaks down in different (sub)types of channels, each with different characteristics and possibilities to supplement and/or replace existing channels. Given the variety of channels, we foresee challenges in incorporating these new channels in multi-channel...... models of service delivery. This is especially relevant given the current lack of evaluations of such models, the broad range of channels available, and their different stages of deployment at governments around the world. Nevertheless, social robots offer an potentially very relevant addition...

  11. Alpha activity measurement with lsc

    International Nuclear Information System (INIS)

    Dobrin, R. I.; Dulama, C. N.; Ciocirlan, C. N.; Toma, A.; Stoica, S. M.; Valeca, M.

    2013-01-01

    Recently, we showed that the alpha activity in liquid samples can be measured using a liquid scintillation analyzer without alpha/beta discrimination capability. The purpose of this work was to evaluate the performances of the method and to optimize the procedure of the sample preparation. A series of tests was performed to validate the procedure of alpha emitting radionuclides extraction in aqueous samples with Actinide Resin, especially regarding to the contact time required to extract all alpha nuclides. The main conclusions were that a minimum 18 hours stirring time is needed to achieve a percent recovery of the alpha nuclides grater than 90% and that the counting efficiency of alphas measurements with LSC is nearly 100%. (authors)

  12. Single Na+ channels activated by veratridine and batrachotoxin

    Science.gov (United States)

    1987-01-01

    Voltage-sensitive Na+ channels from rat skeletal muscle plasma membrane vesicles were inserted into planar lipid bilayers in the presence of either of the alkaloid toxins veratridine (VT) or batrachotoxin (BTX). Both of these toxins are known to cause persistent activation of Na+ channels. With BTX as the channel activator, single channels remain open nearly all the time. Channels activated with VT open and close on a time scale of 1-10 s. Increasing the VT concentration enhances the probability of channel opening, primarily by increasing the rate constant of opening. The kinetics and voltage dependence of channel block by 21-sulfo-11-alpha-hydroxysaxitoxin are identical for VT and BTX, as is the ionic selectivity sequence determined by bi-ionic reversal potential (Na+ approximately Li+ greater than K+ greater than Rb+ greater than Cs+). However, there are striking quantitative differences in open channel conduction for channels in the presence of the two activators. Under symmetrical solution conditions, the single channel conductance for Na+ is about twice as high with BTX as with VT. Furthermore, the symmetrical solution single channel conductances show a different selectivity for BTX (Na+ greater than Li+ greater than K+) than for VT (Na+ greater than K+ greater than Li+). Open channel current-voltage curves in symmetrical Na+ and Li+ are roughly linear, while those in symmetrical K+ are inwardly rectifying. Na+ currents are blocked asymmetrically by K+ with both BTX and VT, but the voltage dependence of K+ block is stronger with BTX than with VT. The results show that the alkaloid neurotoxins not only alter the gating process of the Na+ channel, but also affect the structure of the open channel. We further conclude that the rate-determining step for conduction by Na+ does not occur at the channel's "selectivity filter," where poorly permeating ions like K+ are excluded. PMID:2435846

  13. Hadamard quantum broadcast channels

    Science.gov (United States)

    Wang, Qingle; Das, Siddhartha; Wilde, Mark M.

    2017-10-01

    We consider three different communication tasks for quantum broadcast channels, and we determine the capacity region of a Hadamard broadcast channel for these various tasks. We define a Hadamard broadcast channel to be such that the channel from the sender to one of the receivers is entanglement-breaking and the channel from the sender to the other receiver is complementary to this one. As such, this channel is a quantum generalization of a degraded broadcast channel, which is well known in classical information theory. The first communication task we consider is classical communication to both receivers, the second is quantum communication to the stronger receiver and classical communication to other, and the third is entanglement-assisted classical communication to the stronger receiver and unassisted classical communication to the other. The structure of a Hadamard broadcast channel plays a critical role in our analysis: The channel to the weaker receiver can be simulated by performing a measurement channel on the stronger receiver's system, followed by a preparation channel. As such, we can incorporate the classical output of the measurement channel as an auxiliary variable and solve all three of the above capacities for Hadamard broadcast channels, in this way avoiding known difficulties associated with quantum auxiliary variables.

  14. Molecular characterization of alpha 1- and alpha 2-adrenoceptors.

    Science.gov (United States)

    Harrison, J K; Pearson, W R; Lynch, K R

    1991-02-01

    Three 'alpha 1-adrenoceptors' and three 'alpha 2-adrenoceptors' have now been cloned. How closely do these receptors match the native receptors that have been identified pharmacologically? What are the properties of these receptors, and how do they relate to other members of the cationic amine receptor family? Kevin Lynch and his colleagues discuss these questions in this review.

  15. KCNE regulation of K+ channel trafficking – a Sisyphean task?

    Directory of Open Access Journals (Sweden)

    Vikram Anmol Kanda

    2012-06-01

    Full Text Available Voltage-gated potassium (Kv channels shape the action potentials of excitable cells and regulate membrane potential and ion homeostasis in excitable and nonexcitable cells. With forty known members in the human genome and a variety of homomeric and heteromeric pore-forming alpha subunit interactions, post-translational modifications, cellular locations and expression patterns, the functional repertoire of the Kv alpha subunit family is monumental. This versatility is amplified by a host of interacting proteins, including the single membrane-spanning KCNE ancillary subunits. Here, examining both the secretory and the endocytic pathways, we review recent findings illustrating the surprising virtuosity of the KCNE proteins in orchestrating not just the function, but also the composition, diaspora and retrieval of channels formed by their Kv alpha subunit partners.

  16. Calcium Channel Blockers

    Science.gov (United States)

    ... conditions, such as Raynaud's disease For people of African heritage and older people, calcium channel blockers might ... high-blood-pressure/in-depth/calcium-channel-blockers/ART-20047605 . Mayo Clinic Footer Legal Conditions and Terms ...

  17. Development of the MICROMEGAS Detector for Measuring the Energy Spectrum of Alpha Particles by using a 241-Am Source

    CERN Document Server

    Kim, Do Yoon; Shin, Jae Won; Park, Tae-Sun; Hong, Seung-Woo; Andriamonje, Samuel; Kadi, Yacine; Tenreiro, Claudio

    2016-01-01

    We have developed MICROMEGAS (MICRO MEsh GASeous) detectors for detecting {\\alpha} particles emitted from an 241-Am standard source. The voltage applied to the ionization region of the detector is optimized for stable operation at room temperature and atmospheric pressure. The energy of {\\alpha} particles from the 241-Am source can be varied by changing the flight path of the {\\alpha} particle from the 241 Am source. The channel numbers of the experimentally-measured pulse peak positions for different energies of the {\\alpha} particles are associated with the energies deposited by the alpha particles in the ionization region of the detector as calculated by using GEANT4 simulations; thus, the energy calibration of the MICROMEGAS detector for {\\alpha} particles is done. For the energy calibration, the thickness of the ionization region is adjusted so that {\\alpha} particles may completely stop in the ionization region and their kinetic energies are fully deposited in the region. The efficiency of our MICROMEGA...

  18. Alpha wastes treatment

    International Nuclear Information System (INIS)

    Thouvenot, P.

    2000-01-01

    Alter 2004, the alpha wastes issued from the Commissariat a l'Energie Atomique installations will be sent to the CEDRA plant. The aims of this installation are decontamination and wastes storage. Because of recent environmental regulations concerning ozone layer depletion, the use of CFC 113 in the decontamination unit, as previously planned, is impossible. Two alternatives processes are studied: the AVD process and an aqueous process including surfactants. Best formulations for both processes are defined issuing degreasing kinetics. It is observed that a good degreasing efficiency is linked to a good decontamination efficiency. Best results are obtained with the aqueous process. Furthermore, from the point of view of an existing waste treatment unit, the aqueous process turns out to be more suitable than the AVD process. (author)

  19. New miniaturized alpha/beta spectrometric system for the surface contamination monitoring and radon personal dosimeter

    International Nuclear Information System (INIS)

    Streil, T.; Oeser, V.; Holfeld, G.

    1998-01-01

    The heart of the new miniaturized alpha/beta spectroscopic system is a Smart Card MCA having a 12 bit resolution and a 32 bit memory for each channel with the size of a cheque card. The system consists of a single or up to 12 alpha spectrometers in a battery powered casing with connectors for direct detector/amplifier module plugging. Surface contamination in the order of 1 Bq/cm 2 of 239 Pu can be measured. (M.D.)

  20. KV7 potassium channels

    DEFF Research Database (Denmark)

    Stott, Jennifer B; Jepps, Thomas Andrew; Greenwood, Iain A

    2014-01-01

    Potassium channels are key regulators of smooth muscle tone, with increases in activity resulting in hyperpolarisation of the cell membrane, which acts to oppose vasoconstriction. Several potassium channels exist within smooth muscle, but the KV7 family of voltage-gated potassium channels have been...

  1. Quantum Channels With Memory

    International Nuclear Information System (INIS)

    Rybar, T.

    2012-01-01

    Quantum memory channels represent a very general, yet simple and comprehensible model for causal processes. As such they have attracted considerable research interest, mostly aimed on their transfer capabilities and structure properties. Most notably it was shown that memory channels can be implemented via physically naturally motivated collision models. We also define the concept of repeatable channels and show that only unital channels can be implemented repeat ably with pure memory channels. In the special case of qubit channels we also show that every unital qubit channel has a repeatable implementation. We also briefly explore the possibilities of stroboscopical simulation of channels and show that all random unitary channels can be stroboscopically simulated. Particularly in qubit case, all indivisible qubit channels are also random unitary, hence for qubit all indivisible channels can be stroboscopically simulated. Memory channels also naturally capture the framework of correlated experiments. We develop methods to gather and interpret data obtained in such setting and in detail examine the two qubit case. We also show that for control unitary interactions the measured data will never contradict a simple unitary evolution. Thus no memory effects can be spotted then. (author)

  2. Channel morphology [Chapter 5

    Science.gov (United States)

    Jonathan W. Long; Alvin L. Medina; Daniel G. Neary

    2012-01-01

    Channel morphology has become an increasingly important subject for analyzing the health of rivers and associated fish populations, particularly since the popularization of channel classification and assessment methods. Morphological data can help to evaluate the flows of sediment and water that influence aquatic and riparian habitat. Channel classification systems,...

  3. Mind Your p's and Alphas.

    Science.gov (United States)

    Stallings, William M.

    In the educational research literature alpha, the a priori level of significance, and p, the a posteriori probability of obtaining a test statistic of at least a certain value when the null hypothesis is true, are often confused. Explanations for this confusion are offered. Paradoxically, alpha retains a prominent place in textbook discussions of…

  4. Summary of Alpha Particle Transport

    Energy Technology Data Exchange (ETDEWEB)

    Medley, S.S.; White, R.B.; Zweben, S.J.

    1998-08-19

    This paper summarizes the talks on alpha particle transport which were presented at the 5th International Atomic Energy Agency's Technical Committee Meeting on "Alpha Particles in Fusion Research" held at the Joint European Torus, England in September 1997.

  5. Overexpression of SK2 channels enhances efferent suppression of cochlear responses without enhancing noise resistance.

    Science.gov (United States)

    Maison, Stéphane F; Parker, Lisan L; Young, Lucy; Adelman, John P; Zuo, Jian; Liberman, M Charles

    2007-04-01

    Cochlear hair cells express SK2, a small-conductance Ca(2+)-activated K(+) channel thought to act in concert with Ca(2+)-permeable nicotinic acetylcholine receptors (nAChRs) alpha9 and alpha10 in mediating suppressive effects of the olivocochlear efferent innervation. To probe the in vivo role of SK2 channels in hearing, we examined gene expression, cochlear function, efferent suppression, and noise vulnerability in mice overexpressing SK2 channels. Cochlear thresholds, as measured by auditory brain stem responses and otoacoustic emissions, were normal in overexpressers as was overall cochlear morphology and the size, number, and distribution of efferent terminals on outer hair cells. Cochlear expression levels of SK2 channels were elevated eightfold without striking changes in other SK channels or in the alpha9/alpha10 nAChRs. Shock-evoked efferent suppression of cochlear responses was significantly enhanced in overexpresser mice as seen previously in alpha9 overexpresser mice; however, in contrast to alpha9 overexpressers, SK2 overexpressers were not protected from acoustic injury. Results suggest that efferent-mediated cochlear protection is mediated by other downstream effects of ACh-mediated Ca(2+) entry different from those involving SK2-mediated hyperpolarization and the associated reduction in outer hair cell electromotility.

  6. Proteinaceous alpha-araylase inhibitors

    DEFF Research Database (Denmark)

    Svensson, Birte; Fukuda, Kenji; Nielsen, P.K.

    2004-01-01

    Proteins that inhibit alpha-amylases have been isolated from plants and microorganisms. These inhibitors can have natural roles in the control of endogenous a-amylase activity or in defence against pathogens and pests; certain inhibitors are reported to be antinutritional factors. The alpha-amylase...... inhibitors belong to seven different protein structural families, most of which also contain evolutionary related proteins without inhibitory activity. Two families include bifunctional inhibitors acting both on alpha-amylases and proteases. High-resolution structures are available of target alpha-amylases...... in complex with inhibitors from five families. These structures indicate major diversity but also some similarity in the structural basis of alpha-amylase inhibition. Mutational analysis of the mechanism of inhibition was performed in a few cases and various protein engineering and biotechnological...

  7. Limits of Reliable Communication with Low Probability of Detection on AWGN Channels

    OpenAIRE

    Bash, Boulat A.; Goeckel, Dennis; Towsley, Don

    2012-01-01

    We present a square root limit on the amount of information transmitted reliably and with low probability of detection (LPD) over additive white Gaussian noise (AWGN) channels. Specifically, if the transmitter has AWGN channels to an intended receiver and a warden, both with non-zero noise power, we prove that $o(\\sqrt{n})$ bits can be sent from the transmitter to the receiver in $n$ channel uses while lower-bounding $\\alpha+\\beta\\geq1-\\epsilon$ for any $\\epsilon>0$, where $\\alpha$ and $\\beta...

  8. Increased transient receptor potential vanilloid type 1 (TRPV1) channel expression in hypertrophic heart

    DEFF Research Database (Denmark)

    Thilo, Florian; Liu, Ying; Schulz, Nico

    2010-01-01

    The aim of this study was to compare the expression of transient receptor potential vanilloid type 1 (TRPV1) channels in hypertrophic hearts from transgenic mice showing overexpression of the catalytic subunit alpha of protein phosphatase 2A alpha (PP2Ac alpha) with wild-type mice and with TRPV1-...... alpha transgenic mice compared to wild-type mice and TRPV1-/- mice (8.6±1.3mg/g; 5.4±0.3mg/g; and 5.4±0.4mg/g; respectively; p...

  9. ALPHA freezes antiprotons

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Laboratories like CERN can routinely produce many different types of antiparticles. In 1995, the PS210 experiment formed the first antihydrogen atoms and a few years later, in 2002, ATRAP and ATHENA were already able to produce several thousand of them. However, no experiment in the world has succeeded in ‘trapping’ these anti-atoms in order to study them. This is the goal of the ALPHA experiment, which has recently managed to cool down the antiprotons to just a few Kelvin. This represents a major step towards trapping the anti-atom, thus opening a new avenue into the investigation of antimatter properties.   Members of the ALPHA collaboration working on the apparatus in the Antiproton Decelerator experimental hall at CERN. Just like the atom, the anti-atom is neutral. Unlike the atom, the anti-atom is made up of antiprotons (as opposed to protons in the atom) and positrons (as opposed to electrons). In order to thoroughly study the properties of the anti-atoms, scien...

  10. Alpha-1-antitrypsin deficiency.

    Science.gov (United States)

    Bals, Robert

    2010-10-01

    Alpha-1-antitrypsin deficiency (AATD) is a rare genetic disorder associated with the development of liver and lung disease. AAT is a 52-kD glycoprotein, produced mainly by hepatocytes and secreted into the blood. Agglomeration of the AAT-protein in hepatocytes can result in liver disease. Exposure to smoke is the major risk factor for the development of lung disease characterised as early chronic obstructive lung disease (COPD). Diagnosis is based on the analysis of the AAT genotype and phenotype. The measurement of the AAT serum level is useful as screening test. Liver biopsy is not necessary to establish the diagnosis. Therapy for AAT-related liver disease is supportive, a specific therapy is not available. AATD is a rare condition (1:5000-10000) and, as a consequence, data and information on diagnosis and treatment are not easily accessible. This chapter provides a comprehensive overview on AATD, covering basic biology, diagnostic and therapeutic approaches. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Measurement of $\\alpha_{s}$ with Radiative Hadronic Events

    CERN Document Server

    Abbiendi, G; Åkesson, P F; Alexander, G; Anagnostou, G; Anderson, K J; Asai, S; Axen, D; Bailey, I; Barberio, E; Barillari, T; Barlow, R J; Batley, R J; Bechtle, P; Behnke, T; Bell, K W; Bell, P J; Bella, G; Bellerive, A; Benelli, G; Bethke, S; Biebel, O; Boeriu, O; Bock, P; Boutemeur, M; Braibant, S; Brown, R M; Burckhart, H J; Campana, S; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Ciocca, C; Csilling, A; Cuffiani, M; Dado, S; Dallavalle, M; de Roeck, A; De Wolf, E A; Desch, K; Dienes, B; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Etzion, E; Fabbri, F; Ferrari, P; Fiedler, F; Fleck, I; Ford, M; Frey, A; Gagnon, P; Gary, J W; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Giunta, M; Goldberg, J; Gross, E; Grunhaus, J; Gruwé, M; Sen-Gupta, A; Hajdu, C; Hamann, M; Hanson, G G; Harel, A; Hauschild, M; Hawkes, C M; Hawkings, R; Herten, G; Heuer, R D; Hill, J C; Horváth, D; Igo-Kemenes, P; Ishii, K; Jeremie, H; Jovanovic, P; Junk, T R; Kanzaki, J; Karlen, D; Kawagoe, K; Kawamoto, T; Keeler, R K; Kellogg, R G; Kennedy, B W; Kluth, S; Kobayashi, T; Kobel, M; Komamiya, S; Kramer, T; Krasznahorkays, A Jr; Krieger, P; Von Krogh, J; Kühl, T; Kupper, M; Lafferty, G D; Landsman, H; Lanske, D; Lellouch, D; Letts, J; Levinson, L; Lillich, J; Lloyd, S L; Loebinger, F K; Lü, J; Ludwig, A; Ludwig, J; Mader, W; Marcellini, S; Martin, A J; Mashimo, T; Mättig, P; McKenna, J; McPherson, R A; Meijers, F; Menges, W; Merritt, F S; Mes, H; Meyer, N; Michelini, A; Mihara, S; Mikenberg, G; Miller, D J; Mohr, W; Mori, T; Mutter, A; Nagai, K; Nakamura, I; Nanjo, H; Neal, H A; O'Neale, S W; Oh, A; Oreglia, M J; Orito, S; Pahl, C; Pásztor, G; Pater, J R; Pilcher, J E; Pinfold, J L; Plane, D E; Pooth, O; Przybycien, M; Quadt, A; Rabbertz, K; Rembser, C; Renkel, P; Roney, J M; Rossi, A M; Rozen, Y; Runge, K; Sachs, K; Saeki, T; Sarkisyan-Grinbaum, E; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schiecks, J; Schörner-Sadenius, T; Schröder, M; Schumacher, M; Seuster, R; Shears, T G; Shen, B C; Sherwood, P; Skuja, A; Smith, A M; Sobie, R J; Söldner-Rembold, S; Spanó, F; Stahl, A; Strom, D; Ströhmer, R; Tarem, S; Tasevsky, M; Teuscher, R; Thomson, M A; Torrence, E; Toya, D; Trigger, I; Trócsányi, Z L; Tsur, E; Turner-Watson, M F; Ueda, I; Ujvári, B; Vollmer, C F; Vannerem, P; Vertesi, R; Verzocchi, M; Voss, H; Vossebeld, J; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wengler, T; Wermes, N; Wilson, G W; Wilson, J A; Wolf, G; Wyatt, T R; Yamashita, S; Zer-Zion, D; Zivkovic, L

    2008-01-01

    Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around the mass of the Z0 boson with the OPAL detector at LEP. The strong coupling alpha S is extracted by comparing data and QCD predictions for event shape observables at average reduced centre-of-mass energies ranging from 24 GeV to 78 GeV, and the energy dependence of alpha S is studied. Our results are consistent with the running of alpha S as predicted by QCD and show that within the uncertainties of our analysis event shapes in hadronic Z0 decays with hard and isolated photon radiation can be described by QCD at reduced centre-of-mass energies. Combining all values from different event shape observables and energies gives alpha S (Mz)=0.1182 pm 0.0015(stat.) pm 0.0101(syst.).

  12. What Powers Lyman alpha Blobs?

    OpenAIRE

    Ao, Y.; Matsuda, Y.; Beelen, A.; Henkel, C.; Cen, R.; De Breuck, C.; Francis, P.; Kovacs, A.; Lagache, G.; Lehnert, M.; Mao, M.; Menten, K. M.; Norris, R.; Omont, A.; Tatemastu, K.

    2015-01-01

    Lyman alpha blobs (LABs) are spatially extended lyman alpha nebulae seen at high redshift. The origin of Lyman alpha emission in the LABs is still unclear and under debate. To study their heating mechanism(s), we present Australia Telescope Compact Array (ATCA) observations of the 20 cm radio emission and Herschel PACS and SPIRE measurements of the far-infrared (FIR) emission towards the four LABs in the protocluster J2143-4423 at z=2.38. Among the four LABs, B6 and B7 are detected in the rad...

  13. Alpha heating in toroidal devices

    Energy Technology Data Exchange (ETDEWEB)

    Miley, G.H.

    1978-01-01

    Ignition (or near-ignition) by alpha heating is a key objective for the achievement of economic fusion reactors. While good confinement of high-energy alphas appears possible in larger reactors, near-term tokamak-type ignition experiments as well as some concepts for small reactors (e.g., the Field-Reversed Mirror or FRM) potentially face marginal situations. Consequently, there is a strong motivation to develop methods to evaluate alpha losses and heating profiles in some detail. Such studies for a TFTR-size tokamak and for a small FRM are described here.

  14. HIPPI and Fibre Channel

    International Nuclear Information System (INIS)

    Tolmie, D.E.

    1992-01-01

    The High-Performance Parallel Interface (HIPPI) and Fibre Channel are near-gigabit per second data communications interfaces being developed in ANSI standards Task Group X3T9.3. HIPPI is the current interface of choice in the high-end and supercomputer arena, and Fibre Channel is a follow-on effort. HIPPI came from a local area network background, and Fibre Channel came from a mainframe to peripheral interface background

  15. Vitamin B1 thiazole derivative reduces transmembrane current through ionic channels formed by toxins from black widow spider venom and sea anemone in planar phospholipid membranes.

    Science.gov (United States)

    Shatursky, Oleg Ya; Volkova, Tatyana M; Romanenko, Olexander V; Himmelreich, Nina H; Grishin, Eugene V

    2007-02-01

    The vitamin B1 (thiamine) structural analogue 3-decyloxycarbonylmethyl-4-methyl-5-(beta-hydroxyethyl) thiazole chloride (DMHT) (0.1 mM) reversibly reduced transmembrane currents in CaCl2 and KCl solutions via ionic channels produced by latrotoxins (alpha-latrotoxin (alpha-LT) and alpha-latroinsectotoxin (alpha-LIT)) from black widow spider venom and sea anemone toxin (RTX) in the bilayer lipid membranes (BLMs). Introduction of DMHT from the cis-side of BLM bathed in 10 mM CaCl2 inhibited transmembrane current by 31.6+/-3% and by 61.8+/-3% from the trans-side of BLM for alpha-LT channels. Application of DMHT in the solution of 10 mM CaCl2 to the cis-side of BLM decreased the current through the alpha-LIT and RTX channels by 52+/-4% and 50+/-5%, respectively. Addition of Cd2+ (1 mM) to the cis- or trans-side of the membrane after the DMHT-induced depression of Ca2+-current across the alpha-LT channels caused its further decrease by 85+/-5% that coincides favorably with the intensity of Cd2+ blocking in control experiments without DMHT. These data suggest that DMHT inhibiting is not specific for latrotoxin channels only and DMHT may exert its action on alpha-LT channels without considerable influence on the ionogenic groups of Ca2+-selective site inside the channel cavity. The binding kinetics of DMHT with the alpha-LT channel shows no cooperativity and allows to expect that the DMHT binding site of the toxin is formed by one ionogenic group as the slopes of inhibition rate determined in log-log coordinates are 1.25 on the trans-side and 0.68 on the cis-side. Similar pK of binding (5.4 on the trans-side and 5.7 on the cis-side) also suggest that DMHT may interact with the same high affinity site of alpha-LT channel on either side of the BLM. The comparative analysis of effective radii measured for alpha-LT, alpha-LIT and RTX channels on the cis-side (0.9 nm, 0.53 nm and 0.55 nm, correspondingly) and for alpha-LT channel on the trans-side (0.28+/-0.18 nm) with the

  16. Ion Channels in Leukocytes

    Science.gov (United States)

    1991-07-01

    be fitted to a Hodgkin - conductance. K (1.0) > Rb (0.77) > NH4 (0.10) > Cs Huxley type n4j model (17, 38). However, the rate of K0 (0.02) > Na (ɘ.01...15, 25 activated) T- and B-cells, murine B-cells? SCG, single-channel conductance under physiological ionic gradient- tfor ructif~ y ig ehannel, largest...the channel induces a confor- kat T-cell line (52). Fina:! y , single-channel recordings of mational change that ina.-tix ates the channel rather human T

  17. A channel profile analyser

    International Nuclear Information System (INIS)

    Gobbur, S.G.

    1983-01-01

    It is well understood that due to the wide band noise present in a nuclear analog-to-digital converter, events at the boundaries of adjacent channels are shared. It is a difficult and laborious process to exactly find out the shape of the channels at the boundaries. A simple scheme has been developed for the direct display of channel shape of any type of ADC on a cathode ray oscilliscope display. This has been accomplished by sequentially incrementing the reference voltage of a precision pulse generator by a fraction of a channel and storing ADC data in alternative memory locations of a multichannel pulse height analyser. Alternative channels are needed due to the sharing at the boundaries of channels. In the flat region of the profile alternate memory locations are channels with zero counts and channels with the full scale counts. At the boundaries all memory locations will have counts. The shape of this is a direct display of the channel boundaries. (orig.)

  18. Negative regulation of opioid receptor-G protein-Ca2+ channel pathway by the nootropic nefiracetam.

    Science.gov (United States)

    Yoshii, Mitsunobu; Furukawa, Taiji; Ogihara, Yoshiyasu; Watabe, Shigeo; Shiotani, Tadashi; Ishikawa, Yasuro; Nishimura, Masao; Nukada, Toshihide

    2004-10-01

    It has recently been reported that nefiracetam, a nootropic agent, is capable of attenuating the development of morphine dependence and tolerance in mice. The mechanism of this antimorphine action is not clear. The present study was designed to address this issue using Xenopus oocytes expressing delta-opioid receptors, G proteins (G(i3alpha) or G(o1alpha)), and N-type (alpha1B) Ca2+ channels. Membrane currents through Ca2+ channels were recorded from the oocytes under voltage-clamp conditions. The Ca2+ channel currents were reduced reversibly by 40-60% in the presence of 1 microM leucine-enkephalin (Leu-Enk). The Leu-Enk-induced current inhibition was recovered promptly by nefiracetam (1 microM), while control currents in the absence of Leu-Enk were not influenced by nefiracetam. A binding assay revealed that 3H-nefiracetam preferentially bound to the membrane fraction of oocytes expressing G(i3alpha). When delta-opioid receptors were coexpressed, the binding was significantly increased. However, an additional expression of alpha1B Ca2+ channels decreased the binding. The results suggest that nefiracetam preferentially binds to G(i3alpha) associated with delta-opioid receptors, thereby inhibiting the association of G proteins with Ca2+ channels. In conclusion, nefiracetam negatively regulates the inhibitory pathway of opioid receptor-G protein-Ca2+ channel.

  19. A linearization of quantum channels

    Science.gov (United States)

    Crowder, Tanner

    2015-06-01

    Because the quantum channels form a compact, convex set, we can express any quantum channel as a convex combination of extremal channels. We give a Euclidean representation for the channels whose inverses are also valid channels; these are a subset of the extreme points. They form a compact, connected Lie group, and we calculate its Lie algebra. Lastly, we calculate a maximal torus for the group and provide a constructive approach to decomposing any invertible channel into a product of elementary channels.

  20. Modulation of tumor necrosis factor-alpha production with anti-hypertensive drugs.

    Science.gov (United States)

    Fukuzawa, M; Satoh, J; Ohta, S; Takahashi, K; Miyaguchi, S; Qiang, X; Sakata, Y; Nakazawa, T; Takizawa, Y; Toyota, T

    2000-06-01

    It is well known that some anti-hypertensive drugs affect insulin sensitivity and that tumor necrosis factor-alpha (TNF-alpha) is a mediator of obesity-associated insulin resistance. In this study, we have investigated the effect of anti-hypertensive drugs, calcium (Ca) channel blockers (amlodipine, manidipine and nicardipine), an alpha(1)-blocker (doxazosin), a beta(1)-blocker (metoprolol), and a thiazide diuretic (hydrochlorothiazide), on lipopolysaccharide (LPS)-induced TNF-alpha production. TNF-alpha production, measured with a bioassay and an immunoassay, was evaluated both in vivo and in vitro, by utilizing mice and a human peripheral blood mononuclear cell culture, respectively. Nicardipine, or amlodipine, manidipine and doxazosin significantly inhibited TNF-alpha production in mice at doses more than one or ten times higher than those used clinically, respectively. On the other hand, metoprolol increased TNF-alpha production at doses of more than 10 times those used clinically, whereas hydrochlorothiazide did not alter production of the cytokine. The in vivo effects of these drugs were not necessary parallel to the in vitro effects. Because high doses of these drugs in mice correspond to clinical doses and effects in human, these actions may be related to beneficial and/or harmful effects of these drugs on TNF-alpha mediated diseases, including insulin resistance.

  1. Survey of Gross Alpha Radioactivity in Bore Hole and Well Water in ...

    African Journals Online (AJOL)

    A survey of the gross alpha radioactivity in drinking water from wells and bore holes in Sokoto city was carried out. Forty samples were drawn at random from locally dug wells and bore holes in Sokoto city, Northern Nigeria. The samples were analyzed using the Eurysis system- eight channel gas filled proportional counter.

  2. Survey Of Gross Alpha And Beta Radioactivity In Well Water From ...

    African Journals Online (AJOL)

    Thirty –two samples of well water were drawn at random from wells in and aound Zaria Township, Kaduna State. Two drops of concentrated nitric acid were added in two liters of the sampled water for preservation. The samples were later evaporated and counted for gross alpha and beta in an eight-channel-gas-filled ...

  3. Channelopathies in Cav1.1, Cav1.3, and Cav1.4 voltage-gated L-type Ca2+ channels.

    Science.gov (United States)

    Striessnig, Jörg; Bolz, Hanno Jörn; Koschak, Alexandra

    2010-07-01

    Voltage-gated Ca2+ channels couple membrane depolarization to Ca2+-dependent intracellular signaling events. This is achieved by mediating Ca2+ ion influx or by direct conformational coupling to intracellular Ca2+ release channels. The family of Cav1 channels, also termed L-type Ca2+ channels (LTCCs), is uniquely sensitive to organic Ca2+ channel blockers and expressed in many electrically excitable tissues. In this review, we summarize the role of LTCCs for human diseases caused by genetic Ca2+ channel defects (channelopathies). LTCC dysfunction can result from structural aberrations within their pore-forming alpha1 subunits causing hypokalemic periodic paralysis and malignant hyperthermia sensitivity (Cav1.1 alpha1), incomplete congenital stationary night blindness (CSNB2; Cav1.4 alpha1), and Timothy syndrome (Cav1.2 alpha1; reviewed separately in this issue). Cav1.3 alpha1 mutations have not been reported yet in humans, but channel loss of function would likely affect sinoatrial node function and hearing. Studies in mice revealed that LTCCs indirectly also contribute to neurological symptoms in Ca2+ channelopathies affecting non-LTCCs, such as Cav2.1 alpha1 in tottering mice. Ca2+ channelopathies provide exciting disease-related molecular detail that led to important novel insight not only into disease pathophysiology but also to mechanisms of channel function.

  4. Classification of alpha 1-adrenoceptor subtypes

    NARCIS (Netherlands)

    Michel, M. C.; Kenny, B.; Schwinn, D. A.

    1995-01-01

    Two alpha 1-adrenoceptor subtypes (alpha 1A and alpha 1B) have been detected in various tissues by pharmacological techniques, and three distinct cDNAs encoding alpha 1-adrenoceptor subtypes have been cloned. The profile of an increasing number of subtype-selective compounds at cloned and endogenous

  5. DESIGN OF PARABOLIC CHANNELS

    Directory of Open Access Journals (Sweden)

    A. K. Alibekov

    2015-01-01

    Full Text Available The dependence of the apparent location of the hydraulic parameters of parabolic channels in earthen channel and volume of dredging required in their design and construction, on the basis of conditions to ensure the stability of the slope at the maximum water flow rate. 

  6. Calcium channel blocker overdose

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002580.htm Calcium-channel blocker overdose To use the sharing features on this ... vary. However, the main ingredient is called a calcium-channel antagonist. It helps decrease the heart's pumping strength, which ...

  7. CHANNEL ESTIMATION TECHNIQUE

    DEFF Research Database (Denmark)

    2015-01-01

    the communication channel. The method further includes determining a sequence of second coefficient estimates of the communication channel based on a decomposition of the first coefficient estimates in a dictionary matrix and a sparse vector of the second coefficient estimates, the dictionary matrix including...

  8. Conductance of Ion Channels - Theory vs. Experiment

    Science.gov (United States)

    Pohorille, Andrew; Wilson, Michael; Mijajlovic, Milan

    2013-01-01

    Transmembrane ion channels mediate a number of essential physiological processes in a cell ranging from regulating osmotic pressure to transmission of neural signals. Kinetics and selectivity of ion transport is of critical importance to a cell and, not surprisingly, it is a subject of numerous experimental and theoretical studies. In this presentation we will analyze in detail computer simulations of two simple channels from fungi - antiamoebin and trichotoxin. Each of these channels is made of an alpha-helical bundle of small, nongenomically synthesized peptides containing a number of rare amino acids and exhibits strong antimicrobial activity. We will focus on calculating ionic conductance defined as the ratio of ionic current through the channel to applied voltage. From molecular dynamics simulations, conductance can be calculated in at least two ways, each involving different approximations. Specifically, the current, given as the number of charges transferred through the channel per unit of time, can be obtained from the number of events in which ions cross the channel during the simulation. This method works well for large currents (high conductance values and/or applied voltages). If the number of crossing events is small, reliable estimates of current are difficult to achieve. Alternatively, conductance can be estimated assuming that ion transport can be well approximated as diffusion in the external potential given by the free energy profile. Then, the current can be calculated by solving the one-dimensional diffusion equation in this external potential and applied voltage (the generalized Nernst-Planck equation). To do so three ingredients are needed: the free energy profile, the position-dependent diffusion coefficient and the diffusive flux of ions into the channel. All these quantities can be obtained from molecular dynamics simulations. An important advantage of this method is that it can be used equally well to estimating large and small currents

  9. Triplication of alpha-globin genes is responsible for unusual alpha 113Leu/alpha 113His-globin chain ratios in sheep.

    Science.gov (United States)

    Vestri, R; Masina, P; Rando, A; Testa, A; Di Gregorio, P

    1987-10-01

    By investigations at the DNA and protein level, it has been shown that in sheep a previously detected, presumed quantitative allele of the II alpha 113His gene, displaying a reduced efficiency (called the II alpha 113His decreases gene), is carried by a chromosome bearing three alpha-globin loci. In particular, five sheep having an alpha 113Leu/alpha 113His-chain ratio of about 13:1 (13:1 phenotype) possessed the -I alpha 113Leu-II alpha 113Leu-/-I alpha 113Leu-II alpha 113Leu-III alpha 113His decreases genotype. One sheep showing a alpha 113Leu/alpha 113His-chain ratio of about 3:1 (3:1 phenotype) had the -I alpha 113Leu-II alpha 113His-/-I alpha 113Leu-II alpha 113Leu-III alpha 113His decreases genotype, while one sheep having a chain ratio of about 6:1 (6:1 phenotype) carried the -I alpha 113Leu-II alpha 113Leu-II alpha 113His decreases-/-I alpha 113Leu-II alpha 113Leu-III alpha 113His decreases genotype. Nineteen sheep, displaying the common phenotypes, all possessed the alpha alpha/alpha alpha gene arrangement. Furthermore, the possible location of the gene with reduced efficiency and the expression of the three genes in the triple alpha-globin loci chromosome are discussed.

  10. Pharmacological characterisation of strychnine and brucine analogues at glycine and alpha7 nicotinic acetylcholine receptors

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Gharagozloo, Parviz; Birdsall, Nigel J M

    2006-01-01

    Strychnine and brucine from the plant Strychnos nux vomica have been shown to have interesting pharmacological effects on several neurotransmitter receptors, including some members of the superfamily of ligand-gated ion channels. In this study, we have characterised the pharmacological properties...... of tertiary and quaternary analogues as well as bisquaternary dimers of strychnine and brucine at human alpha1 and alpha1beta glycine receptors and at a chimera consisting of the amino-terminal domain of the alpha7 nicotinic receptor (containing the orthosteric ligand binding site) and the ion channel domain...... of the 5-HT3A serotonin receptor. Although the majority of the analogues displayed significantly increased Ki values at the glycine receptors compared to strychnine and brucine, a few retained the high antagonist potencies of the parent compounds. However, mirroring the pharmacological profiles...

  11. Athermalized channeled spectropolarimeter enhancement.

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Julia Craven; Way, Brandyn Michael; Mercier, Jeffrey Alan; Hunt, Jeffery P.

    2013-09-01

    Channeled spectropolarimetry can measure the complete polarization state of light as a function of wavelength. Typically, a channeled spectropolarimeter uses high order retarders made of uniaxial crystal to amplitude modulate the measured spectrum with the spectrally-dependent Stokes polarization information. A primary limitation of conventional channeled spectropolarimeters is related to the thermal variability of the retarders. Thermal variation often forces frequent system recalibration, particularly for field deployed systems. However, implementing thermally stable retarders, made of biaxial crystal, results in an athermal channeled spectropolarimeter that relieves the need for frequent recalibration. This report presents experimental results for an anthermalized channeled spectropolarimeter prototype produced using potassium titanyl phosphate. The results of this prototype are compared to the current thermal stabilization state of the art. Finally, the application of the technique to the thermal infrared is studied, and the athermalization concept is applied to an infrared imaging spectropolarimeter design.

  12. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter

    2014-01-01

    . The underlying posttranscriptional and posttranslational remodeling of the individual K(+) channels changes their activity and significance relative to each other, and they must be viewed together to understand their role in keeping a stable heart rhythm, also under menacing conditions like attacks of reentry......About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...... that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K(+) channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure...

  13. Muon cooling channels

    CERN Document Server

    Eberhard-K-Kei

    2003-01-01

    A procedure uses the equations that govern ionization cooling, and leads to the most important parameters of a muon cooling channel that achieves assumed performance parameters. First, purely transverse cooling is considered, followed by both transverse and longitudinal cooling in quadrupole and solenoid channels. Similarities and differences in the results are discussed in detail, and a common notation is developed. Procedure and notation are applied to a few published cooling channels. The parameters of the cooling channels are derived step by step, starting from assumed values of the initial, final and equilibrium emittances, both transverse and longitudinal, the length of the cooling channel, and the material properties of the absorber. The results obtained include cooling lengths and partition numbers, amplitude functions and limits on the dispersion at the absorber, length, aperture and spacing of the absorber, parameters of the RF system that achieve the longitudinal amplitude function and bucket area ...

  14. ALPHA (Adjustable Long Pulse High-Field Apparatus)

    Science.gov (United States)

    Birmingham, W. J.; Bates, E. M.; Romero-Talamas, C. A.; Rivera, W. F.

    2017-10-01

    The Dusty Plasma Laboratory (DPL) at the University of Maryland, Baltimore County (UMBC) is now finalizing the design and fabricating components for ALPHA, a high-field Bitter-type electromagnet to be used for magnetized dusty plasma experiments. When the system is complete, ALPHA will be programmable to dynamically increase or decrease fields of up to 10 T for nominally 10 seconds and up to several minutes. The magnet dimensions as well as power and cooling requirements were optimized according to a genetic algorithm developed in the DPL. The cooling channel pattern design was obtained using an analytic methodology also developed in the DPL. The final design parameters as well as the predicted performance characteristics of the magnetic core, the water cooling shell, and the DC power source are presented.

  15. Control channels in the brain and their influence on brain executive functions

    Science.gov (United States)

    Meng, Qinglei; Choa, Fow-Sen; Hong, Elliot; Wang, Zhiguang; Islam, Mohammad

    2014-05-01

    In a computer network there are distinct data channels and control channels where massive amount of visual information are transported through data channels but the information streams are routed and controlled by intelligent algorithm through "control channels". Recent studies on cognition and consciousness have shown that the brain control channels are closely related to the brainwave beta (14-40 Hz) and alpha (7-13 Hz) oscillations. The high-beta wave is used by brain to synchronize local neural activities and the alpha oscillation is for desynchronization. When two sensory inputs are simultaneously presented to a person, the high-beta is used to select one of the inputs and the alpha is used to deselect the other so that only one input will get the attention. In this work we demonstrated that we can scan a person's brain using binaural beats technique and identify the individual's preferred control channels. The identified control channels can then be used to influence the subject's brain executive functions. In the experiment, an EEG measurement system was used to record and identify a subject's control channels. After these channels were identified, the subject was asked to do Stroop tests. Binaural beats was again used to produce these control-channel frequencies on the subject's brain when we recorded the completion time of each test. We found that the high-beta signal indeed speeded up the subject's executive function performance and reduced the time to complete incongruent tests, while the alpha signal didn't seem to be able to slow down the executive function performance.

  16. Contribution to the study of the alpha-alpha interaction

    International Nuclear Information System (INIS)

    Darriulat, Pierre

    1965-01-01

    The new variable energy cyclotron at Berkeley that can accelerate an alpha beam up to an energy of 130 MeV and the mass production of lithium diffused junctions have enabled us to perform 2 series of measurement, in the first one we use alpha beams with an energy ranging between 50 and 120 MeV to study alpha-alpha forces in the second one we use the flexibility of the variable energy cyclotron the resonances around 40 MeV, region that can not yet be reached by tandem accelerators. This work is divided into 6 chapters. The first chapter is dedicated to the formalism of partial wave analysis and the theory of the compound nucleus. In the second chapter the author presents the 88 cyclotron at Berkeley and the diffusion chamber, the alpha detectors are lithium diffused junctions made of silicon. The third chapter deals with the experimental methods used and the issue of the reduction of the volume of data. In the fourth chapter the results obtained in the upper part of the energy range are described in terms of complex shifts that allow the description of the α-α interaction at high energy. The very low impact parameter has enabled us to find 2 new components (l=6 and l=8) of the rotational spectrum and to define a more accurate phenomenological potential. The fifth chapter is dedicated to the narrow resonances we have found between 12 and 27 MeV. We present in the last chapter a calculation of the binding energy of C 12 in which we have considered the 12 C nucleus as formed by 3 alpha particles interacting with each other through the phenomenological potential defined above

  17. Workshop on Precision Measurements of $\\alpha_s$

    Energy Technology Data Exchange (ETDEWEB)

    Bethke, Siegfried; /Munich, Max Planck Inst.; Hoang, Andre H.; /Vienna U.; Kluth, Stefan; /Munich, Max Planck Inst.; Schieck, Jochen; /Munich U.; Stewart, Iain W.; Aoki, S.; Beneke, M.; Bethke, S.; Blumlein, J.; Brambilla, N.; Brodsky, S.; /MIT, LNS

    2011-10-01

    These are the proceedings of the Workshop on Precision Measurements of {alpha}{sub s} held at the Max-Planck-Institute for Physics, Munich, February 9-11, 2011. The workshop explored in depth the determination of {alpha}{sub s}(m{sub Z}) in the {ovr MS} scheme from the key categories where high precision measurements are currently being made, including DIS and global PDF fits, {tau}-decays, electro-weak precision observables and Z-decays, event-shapes, and lattice QCD. These proceedings contain a short summary contribution from the speakers, as well as the lists of authors, conveners, participants, and talks.

  18. Changes in ion channel geometry resolved to sub-angstroem precision via single molecule mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Joseph W F; Kasianowicz, John J; Reiner, Joseph E [Semiconductor Electronics Division, Electronics and Electrical Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

    2010-11-17

    The ion channel formed by Staphylococcus aureus alpha-hemolysin switches between multiple open conducting states. We describe a method for precisely estimating the changes in the ion channel geometry that correspond to these different states. Experimentally, we observed that the permeability of a single channel to differently sized poly(ethylene glycol) molecules depends on the magnitude of the open state conductance. A simple theory is proposed for determining changes in channel length of 4.2% and in cross-sectional area of - 0.4%.

  19. Coherifying quantum channels

    Science.gov (United States)

    Korzekwa, Kamil; Czachórski, Stanisław; Puchała, Zbigniew; Życzkowski, Karol

    2018-04-01

    Is it always possible to explain random stochastic transitions between states of a finite-dimensional system as arising from the deterministic quantum evolution of the system? If not, then what is the minimal amount of randomness required by quantum theory to explain a given stochastic process? Here, we address this problem by studying possible coherifications of a quantum channel Φ, i.e., we look for channels {{{Φ }}}{ \\mathcal C } that induce the same classical transitions T, but are ‘more coherent’. To quantify the coherence of a channel Φ we measure the coherence of the corresponding Jamiołkowski state J Φ. We show that the classical transition matrix T can be coherified to reversible unitary dynamics if and only if T is unistochastic. Otherwise the Jamiołkowski state {J}{{Φ }}{ \\mathcal C } of the optimally coherified channel is mixed, and the dynamics must necessarily be irreversible. To assess the extent to which an optimal process {{{Φ }}}{ \\mathcal C } is indeterministic we find explicit bounds on the entropy and purity of {J}{{Φ }}{ \\mathcal C }, and relate the latter to the unitarity of {{{Φ }}}{ \\mathcal C }. We also find optimal coherifications for several classes of channels, including all one-qubit channels. Finally, we provide a non-optimal coherification procedure that works for an arbitrary channel Φ and reduces its rank (the minimal number of required Kraus operators) from {d}2 to d.

  20. Iterative inversion of gamma or alpha spectrometry data

    International Nuclear Information System (INIS)

    Nordemann, D.J.R.

    1985-12-01

    Gamma - and alpha ray spectrometry data are processed by an iterative regression method (Wolberg, 1967) to obtain the activities or yields of radionuclides. This method, applied to Nuclear Geophysics Research, permits the use of either selected energy bands or of all the channels one by one. It may be easily programmed in popular microcomputers and offers many advantages such as the use of mixtures of radionuclides for the calibrations and the treatment of the uncertainties on the measurements and results. Several conclusions about the method and options of nuclear data processing are presented. (Author) [pt

  1. Evaluation channel performance in multichannel environments

    NARCIS (Netherlands)

    Gensler, S.; Dekimpe, M.; Skiera, B.

    2007-01-01

    Evaluating channel performance is crucial for actively managing multiple sales channels, and requires understanding the customers' channel preferences. Two key components of channel performance are (i) the existing customers' intrinsic loyalty to a particular channel and (ii) the channel's ability

  2. Random numbers spring from alpha decay

    International Nuclear Information System (INIS)

    Frigerio, N.A.; Sanathanan, L.P.; Morley, M.; Clark, N.A.; Tyler, S.A.

    1980-05-01

    Congruential random number generators, which are widely used in Monte Carlo simulations, are deficient in that the number they generate are concentrated in a relatively small number of hyperplanes. While this deficiency may not be a limitation in small Monte Carlo studies involving a few variables, it introduces a significant bias in large simulations requiring high resolution. This bias was recognized and assessed during preparations for an accident analysis study of nuclear power plants. This report describes a random number device based on the radioactive decay of alpha particles from a 235 U source in a high-resolution gas proportional counter. The signals were fed to a 4096-channel analyzer and for each channel the frequency of signals registered in a 20,000-microsecond interval was recorded. The parity bits of these frequency counts (0 for an even count and 1 for an odd count) were then assembled in sequence to form 31-bit binary random numbers and transcribed to a magnetic tape. This cycle was repeated as many times as were necessary to create 3 million random numbers. The frequency distribution of counts from the present device conforms to the Brockwell-Moyal distribution, which takes into account the dead time of the counter (both the dead time and decay constant of the underlying Poisson process were estimated). Analysis of the count data and tests of randomness on a sample set of the 31-bit binary numbers indicate that this random number device is a highly reliable source of truly random numbers. Its use is, therefore, recommended in Monte Carlo simulations for which the congruential pseudorandom number generators are found to be inadequate. 6 figures, 5 tables

  3. Conditioning of alpha bearing wastes

    International Nuclear Information System (INIS)

    1991-01-01

    Alpha bearing wastes are generated during the reprocessing of spent fuel, mixed oxide fuel fabrication, decommissioning and other activities. The safe and effective management of these wastes is of particular importance owing to the radiotoxicity and long lived characteristics of certain transuranic (TRU) elements. The management of alpha bearing wastes involves a number of stages which include collection, characterization, segregation, treatment, conditioning, transport, storage and disposal. This report describes the currently available matrices and technologies for the conditioning of alpha wastes and relates them to their compatibility with the other stages of the waste management process. The selection of a specific immobilization process is dependent on the waste treatment state and the subsequent handling, transport, storage and disposal requirements. The overall objectives of immobilization are similar for all waste producers and processors, which are to produce: (a) Waste forms with sufficient mechanical, physical and chemical stability to satisfy all stages of handling, transport and storage (referred to as the short term requirements), and (b) Waste forms which will satisfy disposal requirements and inhibit the release of radionuclides to the biosphere (referred to as the long term requirements). Cement and bitumen processes have already been successfully applied to alpha waste conditioning on the industrial scale in many of the IAEA Member States. Cement systems based on BFS and pozzolanic cements have emerged as the principal encapsulation matrices for the full range of alpha bearing wastes. Alternative technologies, such as polymers and ceramics, are being developed for specific waste streams but are unlikely to meet widespread application owing to cost and process complexity. The merits of alpha waste conditioning are improved performance in transport, storage and disposal combined with enhanced public perception of waste management operations. These

  4. Fractional channel multichannel analyzer

    Science.gov (United States)

    Brackenbush, L.W.; Anderson, G.A.

    1994-08-23

    A multichannel analyzer incorporating the features of the present invention obtains the effect of fractional channels thus greatly reducing the number of actual channels necessary to record complex line spectra. This is accomplished by using an analog-to-digital converter in the asynchronous mode, i.e., the gate pulse from the pulse height-to-pulse width converter is not synchronized with the signal from a clock oscillator. This saves power and reduces the number of components required on the board to achieve the effect of radically expanding the number of channels without changing the circuit board. 9 figs.

  5. Cl- channels in apoptosis

    DEFF Research Database (Denmark)

    Wanitchakool, Podchanart; Ousingsawat, Jiraporn; Sirianant, Lalida

    2016-01-01

    A remarkable feature of apoptosis is the initial massive cell shrinkage, which requires opening of ion channels to allow release of K(+), Cl(-), and organic osmolytes to drive osmotic water movement and cell shrinkage. This article focuses on the role of the Cl(-) channels LRRC8, TMEM16/anoctamin......, and cystic fibrosis transmembrane conductance regulator (CFTR) in cellular apoptosis. LRRC8A-E has been identified as a volume-regulated anion channel expressed in many cell types. It was shown to be required for regulatory and apoptotic volume decrease (RVD, AVD) in cultured cell lines. Its presence also...

  6. Direct channel problems and phenomena

    International Nuclear Information System (INIS)

    Cutkosky, R.E.

    1975-01-01

    Direct channel problems and phenomena are considered covering the need for precision hadron spectroscopy, the data base for precision hadron spectroscopy, some relations between direct-channel and cross-channel effects, and spin rotation phenomena

  7. Fitting of alpha-efficiency versus quenching parameter by exponential functions in liquid scintillation counting

    International Nuclear Information System (INIS)

    Sosa, M.; Manjón, G.; Mantero, J.; García-Tenorio, R.

    2014-01-01

    The objective of this work is to propose an exponential fit for the low alpha-counting efficiency as a function of a sample quenching parameter using a Quantulus liquid scintillation counter. The sample quenching parameter in a Quantulus is the Spectral Quench Parameter of the External Standard (SQP(E)), which is defined as the number of channel under which lies the 99% of Compton spectrum generated by a gamma emitter ( 152 Eu). Although in the literature one usually finds a polynomial fitting of the alpha counting efficiency, it is shown here that an exponential function is a better description. - Highlights: • We have studied the quenching in alpha measurement by liquid scintillation counting. • We have reviewed typical fitting of alpha counting efficiency versus quenching parameter. • Exponential fitting of data is proposed as better fitting. • We consider exponential fitting has a physical basis

  8. Fitting of alpha-efficiency versus quenching parameter by exponential functions in liquid scintillation counting

    Energy Technology Data Exchange (ETDEWEB)

    Sosa, M. [Departamento de Ingeniería Física, Campus León, Universidad de Guanajuato, 37150 León, Guanajuato (Mexico); Universidad de Sevilla, Departamento de Física Aplicada II, E.T.S. Arquitectura, Av. Reina Mercedes, 2, 41012 Sevilla (Spain); Manjón, G., E-mail: manjon@us.es [Universidad de Sevilla, Departamento de Física Aplicada II, E.T.S. Arquitectura, Av. Reina Mercedes, 2, 41012 Sevilla (Spain); Mantero, J.; García-Tenorio, R. [Universidad de Sevilla, Departamento de Física Aplicada II, E.T.S. Arquitectura, Av. Reina Mercedes, 2, 41012 Sevilla (Spain)

    2014-05-01

    The objective of this work is to propose an exponential fit for the low alpha-counting efficiency as a function of a sample quenching parameter using a Quantulus liquid scintillation counter. The sample quenching parameter in a Quantulus is the Spectral Quench Parameter of the External Standard (SQP(E)), which is defined as the number of channel under which lies the 99% of Compton spectrum generated by a gamma emitter ({sup 152}Eu). Although in the literature one usually finds a polynomial fitting of the alpha counting efficiency, it is shown here that an exponential function is a better description. - Highlights: • We have studied the quenching in alpha measurement by liquid scintillation counting. • We have reviewed typical fitting of alpha counting efficiency versus quenching parameter. • Exponential fitting of data is proposed as better fitting. • We consider exponential fitting has a physical basis.

  9. Channel Choice: A Literature Review

    DEFF Research Database (Denmark)

    Østergaard Madsen, Christian; Kræmmergaard, Pernille

    2015-01-01

    The channel choice branch of e-government studies citizens’ and businesses’ choice of channels for interacting with government, and how government organizations can integrate channels and migrate users towards the most cost-efficient channels. In spite of the valuable contributions offered no sys...... no systematic overview exist of channel choice. We present a literature review of channel choice studies in government to citizen context identifying authors, countries, methods, concepts, units of analysis, and theories, and offer suggestionsfor future studies....

  10. alpha-Hemolysin, gamma-hemolysin, and leukocidin from Staphylococcus aureus: distant in sequence but similar in structure.

    OpenAIRE

    Gouaux, E.; Hobaugh, M.; Song, L.

    1997-01-01

    alpha-Hemolysin from Staphylococcus aureus assembles from a water-soluble, monomeric species to a membrane-bound heptamer on the surface of target cells, creating water-filled channels that lead to cell death and lysis. Staphylococcus aureus also produces the gamma-hemolysin and leukocidin toxins, which function as two component toxins in the disruption and lysis of erythrocytes and leukocytes. Analysis of the aligned sequences of alpha-hemolysin, gamma-hemolysin, and leukocidin in the contex...

  11. Kvbeta2 inhibits the Kvbeta1-mediated inactivation of K+ channels in transfected mammalian cells.

    Science.gov (United States)

    Xu, J; Li, M

    1997-05-02

    Cloned auxiliary beta-subunits (e.g. Kvbeta1) modulate the kinetic properties of the pore-forming alpha-subunits of a subset of Shaker-like potassium channels. Coexpression of the alpha-subunit and Kvbeta2, however, induces little change in channel properties. Since more than one beta-subunit has been found in individual K+ channel complexes and expression patterns of different beta-subunits overlap in vivo, it is important to test the possible physical and/or functional interaction(s) between different beta-subunits. In this report, we show that both Kvbeta2 and Kvbeta1 recognize the same region on the pore-forming alpha-subunits of the Kv1 Shaker-like potassium channels. In the absence of alpha-subunits the Kvbeta2 polypeptide interacts with additional beta-subunit(s) to form either a homomultimer with Kvbeta2 or a heteromultimer with Kvbeta1. When coexpressing alpha-subunits and Kvbeta1 in the presence of Kvbeta2, we find that Kvbeta2 is capable of inhibiting the Kvbeta1-mediated inactivation. Using deletion analysis, we have localized the minimal interaction region that is sufficient for Kvbeta2 to associate with both alpha-subunits and Kvbeta1. This mapped minimal interaction region is necessary and sufficient for inhibiting the Kvbeta1-mediated inactivation, consistent with the notion that the inhibitory activity of Kvbeta2 results from the coassembly of Kvbeta2 with compatible alpha-subunits and possibly with Kvbeta1. Together, these results provide biochemical evidence that Kvbeta2 may profoundly alter the inactivation activity of another beta-subunit by either differential subunit assembly or by competing for binding sites on alpha-subunits, which indicates that Kvbeta2 is capable of serving as an important determinant in regulating the kinetic properties of K+ currents.

  12. Analysis of Maxi-K alpha subunit splice variants in human myometrium

    Directory of Open Access Journals (Sweden)

    Morrison John J

    2004-09-01

    Full Text Available Abstract Background Large-conductance, calcium-activated potassium (Maxi-K channels are implicated in the modulation of human uterine contractions and myometrial Ca2+ homeostasis. However, the regulatory mechanism(s governing the expression of Maxi-K channels with decreased calcium sensitivity at parturition are unclear. The objectives of this study were to investigate mRNA expression of the Maxi-K alpha subunit, and that of its splice variants, in human non-pregnant and pregnant myometrium, prior to and after labour onset, to determine whether altered expression of these splice variants is associated with decreased calcium sensitivity observed at labour onset. Methods Myometrial biopsies were obtained at hysterectomy (non-pregnant, NP, and at Caesarean section, at elective (pregnant not-in-labour, PNL and intrapartum (pregnant in-labour, PL procedures. RNA was extracted from all biopsies and quantitative real-time RT-PCR was used to investigate for possible differential expression of the Maxi-K alpha subunit, and that of its splice variants, between these functionally-distinct myometrial tissue sets. Results RT-PCR analysis identified the presence of a 132 bp and an 87 bp spliced exon of the Maxi-K alpha subunit in all three myometrial tissue sets. Quantitative real-time PCR indicated a decrease in the expression of the Maxi-K alpha subunit with labour onset. While there was no change in the proportion of Maxi-K alpha subunits expressing the 87 bp spliced exon, the proportion of alpha subunits expressing the 132 bp spliced exon was significantly increased with labour onset, compared to both non-pregnant and pregnant not-in-labour tissues. An increased proportion of 132 bp exon-containing alpha subunit variants with labour onset is of interest, as channels expressing this spliced exon have decreased calcium and voltage sensitivities. Conclusions Our findings suggest that decreased Maxi-K alpha subunit mRNA expression in human myometrium at

  13. Molecular model of the action potential sodium channel.

    OpenAIRE

    Guy, H R; Seetharamulu, P

    1986-01-01

    Secondary and tertiary structural models of sodium channel transmembrane segments were developed from its recently determined primary sequence in Electrophorus electricus. The model has four homologous domains, and each domain has eight homologous transmembrane segments, S1 through S8. Each domain contains three relatively apolar segments (S1, S2 and S3) and two very apolar segments (S5 and S8), all postulated to be transmembrane alpha-helices. S4 segments have positively charged residues, ma...

  14. Volume Regulated Channels

    DEFF Research Database (Denmark)

    Klausen, Thomas Kjær

    , controlled cell death and cellular migration. Volume regulatory mechanisms has long been in focus for regulating cellular proliferation and my thesis work have been focusing on the role of Cl- channels in proliferation with specific emphasis on ICl, swell. Pharmacological blockage of the ubiquitously...... but are also essential for a number of physiological processes such as proliferation, controlled cell death, migration and endocrinology. The thesis have been focusing on two Channels, namely the swelling activated Cl- channel (ICl, swell) and the transient receptor potential Vanilloid (TRPV4) channel. I: Cl...... understood. Potential agonist binding sites have been proposed in transmembrane domains 3 and 4, in congruence with agonist binding sites of TRPV1. However, the functional relationship between TRPV4 and agonist binding is not yet understood. In this thesis is further elaborate the structure...

  15. Sensing with Ion Channels

    CERN Document Server

    Martinac, Boris

    2008-01-01

    All living cells are able to detect and translate environmental stimuli into biologically meaningful signals. Sensations of touch, hearing, sight, taste, smell or pain are essential to the survival of all living organisms. The importance of sensory input for the existence of life thus justifies the effort made to understand its molecular origins. Sensing with Ion Channels focuses on ion channels as key molecules enabling biological systems to sense and process the physical and chemical stimuli that act upon cells in their living environment. Its aim is to serve as a reference to ion channel specialists and as a source of new information to non specialists who want to learn about the structural and functional diversity of ion channels and their role in sensory physiology.

  16. Calcium channel blocker poisoning

    Directory of Open Access Journals (Sweden)

    Miran Brvar

    2005-04-01

    Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

  17. Coding for optical channels

    CERN Document Server

    Djordjevic, Ivan; Vasic, Bane

    2010-01-01

    This unique book provides a coherent and comprehensive introduction to the fundamentals of optical communications, signal processing and coding for optical channels. It is the first to integrate the fundamentals of coding theory and optical communication.

  18. Tritium in the Channel

    International Nuclear Information System (INIS)

    Masson, M.; Fievet, B.; Bailly-Du-Bois, P.; Olivier, A.; Tenailleau, L.

    2009-01-01

    After having recalled that sea waters entering the Channel exhibit a natural concentration of tritium, the authors outline that spent nuclear fuel reprocessing plants are now the main sources of tritium for marine ecosystems as some oceanographic campaigns showed it. If data about the presence of tritium in water are numerous, data concerning the presence of tritiated water and of organically bound tritium in organisms are much less frequent. However, some surveys have been performed along the Channel French coasts

  19. Channelling versus inversion

    DEFF Research Database (Denmark)

    Gale, A.S.; Surlyk, Finn; Anderskouv, Kresten

    2013-01-01

    Evidence from regional stratigraphical patterns in Santonian−Campanian chalk is used to infer the presence of a very broad channel system (5 km across) with a depth of at least 50 m, running NNW−SSE across the eastern Isle of Wight; only the western part of the channel wall and fill is exposed. W......−Campanian chalks in the eastern Isle of Wight, involving penecontemporaneous tectonic inversion of the underlying basement structure, are rejected....

  20. Improved Alpha Testing Using Hashed Sampling.

    Science.gov (United States)

    Wyman, Chris; McGuire, Morgan

    2017-08-14

    We further describe and analyze the idea of hashed alpha testing from Wyman and McGuire [1], which builds on stochastic alpha testing and simplifies stochastic transparency. Typically, alpha testing provides a simple mechanism to mask out complex silhouettes using simple proxy geometry with applied alpha textures. While widely used, alpha testing has a long-standing problem: geometry can disappear entirely as alpha mapped polygons recede with distance. As foveated rendering for virtual reality spreads, this problem worsens as peripheral minification and prefiltering introduce this problem on nearby objects.

  1. Course on Ionic Channels

    CERN Document Server

    1986-01-01

    This book is based on a series of lectures for a course on ionic channels held in Santiago, Chile, on November 17-20, 1984. It is intended as a tutorial guide on the properties, function, modulation, and reconstitution of ionic channels, and it should be accessible to graduate students taking their first steps in this field. In the presentation there has been a deliberate emphasis on the spe­ cific methodologies used toward the understanding of the workings and function of channels. Thus, in the first section, we learn to "read" single­ channel records: how to interpret them in the theoretical frame of kinetic models, which information can be extracted from gating currents in re­ lation to the closing and opening processes, and how ion transport through an open channel can be explained in terms of fluctuating energy barriers. The importance of assessing unequivocally the origin and purity of mem­ brane preparations and the use of membrane vesicles and optical tech­ niques in the stUGY of ionic channels a...

  2. ALPHA,·ANTITRYPSIN DEFICIENCY*

    African Journals Online (AJOL)

    1971-02-06

    Feb 6, 1971 ... Lieberman," in fact, found that 15·2% of 66 patients hospitalized with pulmonary emphysema had heterozygous alpha,-antitrypsin deficiency. The over-all incidence of the deficiency was 25'8% in this group. Of patients under the age of 50 years, 47·8% had deficient levels. If such observations are confirmed ...

  3. Alpha sources deposit by sublimation

    International Nuclear Information System (INIS)

    Amoudry, F.; Eloy, J.F.

    1983-09-01

    We studied and realized a device able to perform some very thin substracts used for alpha spectrometry measurements. Sources are prepared by sublimation of the sample in a vacuum container. The energy required for this sublimation is furnished by a laser beam [fr

  4. Nootropic alpha7 nicotinic receptor allosteric modulator derived from GABAA receptor modulators.

    Science.gov (United States)

    Ng, Herman J; Whittemore, Edward R; Tran, Minhtam B; Hogenkamp, Derk J; Broide, Ron S; Johnstone, Timothy B; Zheng, Lijun; Stevens, Karen E; Gee, Kelvin W

    2007-05-08

    Activation of brain alpha7 nicotinic acetylcholine receptors (alpha7 nAChRs) has broad therapeutic potential in CNS diseases related to cognitive dysfunction, including Alzheimer's disease and schizophrenia. In contrast to direct agonist activation, positive allosteric modulation of alpha7 nAChRs would deliver the clinically validated benefits of allosterism to these indications. We have generated a selective alpha7 nAChR-positive allosteric modulator (PAM) from a library of GABAA receptor PAMs. Compound 6 (N-(4-chlorophenyl)-alpha-[[(4-chloro-phenyl)amino]methylene]-3-methyl-5-isoxazoleacet-amide) evokes robust positive modulation of agonist-induced currents at alpha7 nAChRs, while preserving the rapid native characteristics of desensitization, and has little to no efficacy at other ligand-gated ion channels. In rodent models, it corrects sensory-gating deficits and improves working memory, effects consistent with cognitive enhancement. Compound 6 represents a chemotype for allosteric activation of alpha7 nAChRs, with therapeutic potential in CNS diseases with cognitive dysfunction.

  5. Association of transient receptor potential canonical type 3 (TRPC3) channel transcripts with proinflammatory cytokines

    DEFF Research Database (Denmark)

    Thilo, Florian; Scholze, Alexandra; Liu, Dao Yan

    2008-01-01

    necrosis factor-alpha (TNF-alpha) in monocytes from 15 patients with essential hypertension and 16 age- and sex-matched normotensive control subjects. We observed an approximately 8-fold increase of TRPC3 transcripts in monocytes from patients with essential hypertension compared to normotensive control......We investigated whether expression of non-selective cation channels of the transient receptor potential canonical (TRPC) channel family are associated with proinflammatory cytokines in monocytes. Using quantitative RT-PCR we studied the expression of TRPC3, interleukin-1beta (IL-1beta), and tumor...

  6. adequacy of drainage channels f drainage channels in a small

    African Journals Online (AJOL)

    eobe

    carried out and data obtain from drainage channels. The time of concentratio version of version of Kirpich equation (new equation of time new equation of time from the drainage channels were determined using results showed that most of the drainage channels h. All the drainage channels of basin A had velocities ra.

  7. Ion channelling in diamond

    International Nuclear Information System (INIS)

    Derry, T.E.

    1978-06-01

    Diamond is one of the most extreme cases from a channelling point of view, having the smallest thermal vibration amplitude and the lowest atomic number of commonly-encountered crystals. These are the two parameters most important for determining channelling behaviour. It is of consiberable interest therefore to see how well the theories explaining and predicting the channeling properties of other substance, succeed with diamond. Natural diamond, although the best available form for these experiments, is rather variable in its physical properties. Part of the project was devoted to considering and solving the problem of obtaining reproducible results representative of the ideal crystal. Channelling studies were performed on several good crystals, using the Rutherford backscattering method. Critical angles for proton channelling were measured for incident energies from 0.6 to 4.5 MeV, in the three most open axes and three most open planes of the diamond structure, and for α-particle channelling at 0.7 and 1.0 MeV (He + ) in the same axes and planes. For 1.0 MeV protons, the crystal temperature was varied from 20 degrees Celsius to 700 degrees Celsius. The results are presented as curves of backscattered yield versus angle in the region of each axis or plane, and summarised in the form of tables and graphs. Generally the critical angles, axial minimum yields, and temperature dependence are well predicted by the accepted theories. The most valuable overall conclusion is that the mean thermal vibration amplitude of the atoms in a crytical determines the critical approach distance to the channel walls at which an ion can remain channelled, even when this distance is much smaller than the Thomas-Fermi screening distance of the atomic potential, as is the case in diamond. A brief study was made of the radiation damage caused by α-particle bombardment, via its effect on the channelling phenomenon. It was possible to hold damage down to negligible levels during the

  8. The Earliest Ion Channels in Protocellular Membranes

    Science.gov (United States)

    Mijajlovic, Milan; Pohorille, Andrew; Wilson, Michael; Wei, Chenyu

    2010-01-01

    indicates that their structures are unique and stable. In addition, it is also believed that the trichotoxin channel displays some selectivity between potassium and chloride ions. This makes trichotoxin and antiamoebin ideal models of the earliest ion channels that could provide insight into the origins of ion conductance and selectivity. In the absence of crystal structure of the trichotoxin and antiamoebin channels, we propose their molecular models based on experimentally determined number of monomers forming the bundles. We use molecular dynamics simulations to validate the models in terms of their conductance and selectivity. On the basis of our simulations we show that the emergence of channels built of small, alpha-helical peptides was protobiologically plausible and did not require highly specific amino acid sequences, which is a convenient evolutionary trait. Despite their simple structure, such channels could possess properties that, at the first sight, appear to require markedly larger complexity. To this end, we will discuss how the amino acid sequence and structure of primitive channels give rise to the phenomena of ionic conductance and selectivity across the earliest cell walls, which were essential functions for the emergence and early evolution of protocells. Furthermore, we will argue that even though architectures of membrane proteins are not nearly as diverse as those of water-soluble proteins, they are sufficiently flexible to adapt readily to the functional demands arising during evolution.

  9. The effect of a metalloproteinase inhibitor (GI5402) on tumor necrosis factor-alpha (TNF-alpha) and TNF-alpha receptors during human endotoxemia

    NARCIS (Netherlands)

    Dekkers, P. E.; Lauw, F. N.; ten Hove, T.; te Velde, A. A.; Lumley, P.; Becherer, D.; van Deventer, S. J.; van der Poll, T.

    1999-01-01

    Tumor necrosis factor-alpha (TNF-alpha) is released from the cell surface by cleavage of pro-TNF-alpha by metalloproteinases (MPs). In cell cultures, inhibition of MPs has been found not only to reduce the release of TNF-alpha, but also to enhance the surface expression of TNF-alpha and TNF-alpha

  10. Functional characterisation of the human alpha1 glycine receptor in a fluorescence-based membrane potential assay

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Kristiansen, Uffe

    2004-01-01

    screening assay. In the patch-clamp assay, the alpha1 GlyR exhibited the properties expected from a strychnine-sensitive glycine-gated chloride channel. In the FMP assay exposure of the cell line to GlyR agonists elicited a concentration-dependent increase in fluorescent intensity, a signal that could...... and RU 5135>strychnine>brucine>PMBA=picrotoxin>atropine for the antagonists. The actions of three allosteric modulators at the alpha1 GlyR cell line were also characterised in the FMP assay. Micromolar concentrations of Zn2+ inhibited alpha1 GlyR signalling but in contrast to previous reports the metal...

  11. Calibration of sources for alpha spectroscopy systems

    International Nuclear Information System (INIS)

    Freitas, I.S.M.; Goncalez, O.L.

    1992-01-01

    This paper describes the calibration methodology for measuring the total alpha activity of plane and thin sources with the Alpha Spectrometer for Silicon Detector in the Nuclear Measures and Dosimetry laboratory at IEAv/CTA. (author)

  12. Channel identification machines.

    Science.gov (United States)

    Lazar, Aurel A; Slutskiy, Yevgeniy B

    2012-01-01

    We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s) onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS) with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits.

  13. Channel Identification Machines

    Directory of Open Access Journals (Sweden)

    Aurel A. Lazar

    2012-01-01

    Full Text Available We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits.

  14. Facilitation by the beta2a subunit of pore openings in cardiac Ca2+ channels.

    Science.gov (United States)

    Costantin, J; Noceti, F; Qin, N; Wei, X; Birnbaumer, L; Stefani, E

    1998-02-15

    1. Single channel recordings were performed on the cardiac calcium channel (alpha1C) in order to study the effect of coexpression of the accessory beta2a subunit. On-cell patch clamp recordings were performed after expression of these channels in Xenopus oocytes. 2. The alpha1C subunit, when expressed alone, had similar single channel properties to native cardiac channels. Slow transitions between low and high open probability (Po) gating modes were found as well as fast gating transitions between the open and closed states. 3. Coexpression of the beta2a subunit caused changes in the fast gating during high Po mode. In this mode, open time distributions reveal at least three open states and the beta2a subunit favours the occupancy of the longest, 10-15 ms open state. No effect of the beta2a subunit was found when the channel was gating in the low Po mode. 4. Slow gating transitions were also affected by the beta2a subunit. The high Po mode was maintained for the duration of the depolarizing pulse in the presence of the beta2a subunit; while the alpha1C channel when expressed alone, frequently switched into and out of the high Po mode during the course of a sweep. 5. The beta2a subunit also affected mode switching that occurred between sweeps. Runs analysis revealed that the alpha1C subunit has a tendency toward non-random mode switching. The beta2a subunit increased this tendency. A chi2 analysis of contingency tables indicated that the beta2a subunit caused the alpha1C channel to gain 'intrinsic memory', meaning that the mode of a given sweep can be non-independent of the mode of the previous sweep. 6. We conclude that the beta2a subunit causes changes to the alpha1C channel in both its fast and slow gating behaviour. The beta2a subunit alters fast gating by facilitating movement of the channel into an existing open state. Additionally, the beta2a subunit decreases the slow switching between low and high Po modes.

  15. Measurements of the CKM Angle Alpha at BaBar

    Energy Technology Data Exchange (ETDEWEB)

    Stracka, Simone; /Milan U. /INFN, Milan

    2012-04-04

    The authors present improved measurements of the branching fractions and CP-asymmetries fin the B{sup 0} {yields} {pi}{sup +}{pi}{sup -}, B{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}, and B{sup +} {yields} {rho}{sup +}{rho}{sup 0} decays, which impact the determination of {alpha}. The combined branching fractions of B {yields} K{sub 1}(1270){pi} and B {yields} K{sub 1}(1400){pi} decays are measured for the first time and allow a novel determination of {alpha} in the B{sup 0} {yields} {alpha}{sub 1}(1260){sup {+-}}{pi}{sup {-+}} decay channel. These measurements are performed using the final dataset collected by the BaBar detector at the PEP-II B-factory. The primary goal of the experiments based at the B factories is to test the Cabibbo-Kobayashi-Maskawa (CKM) picture of CP violation in the standard model of electroweak interactions. This can be achieved by measuring the angles and sides of the Unitarity Triangle in a redundant way.

  16. Enzyme replacement therapy for alpha-mannosidosis

    DEFF Research Database (Denmark)

    Borgwardt, Line Gutte; Dali, Christine I.; Fogh, J

    2013-01-01

    Alpha-mannosidosis (OMIM 248500) is a rare lysosomal storage disease (LSD) caused by alpha-mannosidase deficiency. Manifestations include intellectual disabilities, facial characteristics and hearing impairment. A recombinant human alpha-mannosidase (rhLAMAN) has been developed for weekly intrave...... intravenous enzyme replacement therapy (ERT). We present the preliminary data after 12 months of treatment....

  17. THE ALPHA/BETA-HYDROLASE FOLD

    NARCIS (Netherlands)

    OLLIS, DL; CHEAH, E; CYGLER, M; FROLOW, F; FRANKEN, SM; HAREL, M; REMINGTON, SJ; SILMAN, [No Value; SCHRAG, J; SUSSMAN, JL; VERSCHUEREN, KHG; GOLDMAN, A

    We have identified a new protein fold-the alpha/beta-hydrolase fold-that is common to several hydrolytic enzymes of widely differing phylogenetic origin and catalytic function. The core of each enzyme is similar: an alpha/beta-sheet, not barrel, of eight beta-sheets connected by alpha-helices. These

  18. Channel plate for DNA sequencing

    Science.gov (United States)

    Douthart, Richard J.; Crowell, Shannon L.

    1998-01-01

    This invention is a channel plate that facilitates data compaction in DNA sequencing. The channel plate has a length, a width and a thickness, and further has a plurality of channels that are parallel. Each channel has a depth partially through the thickness of the channel plate. Additionally an interface edge permits electrical communication across an interface through a buffer to a deposition membrane surface.

  19. Nature of the pygmy dipole resonance in Ce-140 studied in (alpha, alpha 'gamma) experiments

    NARCIS (Netherlands)

    Savran, D.; Babilon, M.; van den Berg, A.M.; Harakeh, M.N.; Hasper, J.; Matic, A.; Wörtche, H.J.; Zilges, A.

    2006-01-01

    A concentration of electric-dipole excitations below the particle threshold, which is frequently denoted as the pygmy dipole resonance, has been studied in the semimagic nucleus Ce-140 in (alpha, alpha(')gamma) experiments at E-alpha=136 MeV. The technique of alpha-gamma coincidence experiments

  20. Nanoscale Vacuum Channel Transistor.

    Science.gov (United States)

    Han, Jin-Woo; Moon, Dong-Il; Meyyappan, M

    2017-04-12

    Vacuum tubes that sparked the electronics era had given way to semiconductor transistors. Despite their faster operation and better immunity to noise and radiation compared to the transistors, the vacuum device technology became extinct due to the high power consumption, integration difficulties, and short lifetime of the vacuum tubes. We combine the best of vacuum tubes and modern silicon nanofabrication technology here. The surround gate nanoscale vacuum channel transistor consists of sharp source and drain electrodes separated by sub-50 nm vacuum channel with a source to gate distance of 10 nm. This transistor performs at a low voltage (3 microamperes). The nanoscale vacuum channel transistor can be a possible alternative to semiconductor transistors beyond Moore's law.

  1. Chaos in quantum channels

    Science.gov (United States)

    Hosur, Pavan; Qi, Xiao-Liang; Roberts, Daniel A.; Yoshida, Beni

    2016-02-01

    We study chaos and scrambling in unitary channels by considering their entanglement properties as states. Using out-of-time-order correlation functions to diagnose chaos, we characterize the ability of a channel to process quantum information. We show that the generic decay of such correlators implies that any input subsystem must have near vanishing mutual information with almost all partitions of the output. Additionally, we propose the negativity of the tripartite information of the channel as a general diagnostic of scrambling. This measures the delocalization of information and is closely related to the decay of out-of-time-order correlators. We back up our results with numerics in two non-integrable models and analytic results in a perfect tensor network model of chaotic time evolution. These results show that the butterfly effect in quantum systems implies the information-theoretic definition of scrambling.

  2. CANDU fuel channels

    International Nuclear Information System (INIS)

    Coleman, C.E.; Cheadle, B.A.

    1997-01-01

    The service life of CANDU fuel channels is determined by the component that has to withstand the most severe conditions, the Zr-2.5Nb pressure tube. The latest fuel channels are expected to have a lifetime of over 30 years. The properties that control service life are fracture and deformation. For fracture, a defence-in-depth approach is used - preventing crack initiation and invoking leak-before-break. Confidence in the serviceability of fuel channels is based on current knowledge of the state of health of the components evaluated by surveillance. Degradation of properties with service is slow, allowing sufficient time to judge and act when end-of-life is reached. Methods for improving the properties of components are outlined. (author)

  3. Alternative splicing of T cell receptor (TCR) alpha chain transcripts containing V alpha 1 or V alpha 14 elements.

    Science.gov (United States)

    Mahotka, C; Hansen-Hagge, T E; Bartram, C R

    1995-10-01

    Human acute lymphoblastic leukemia cell lines represent valuable tools to investigate distinct steps of the complex regulatory pathways underlying T cell receptor recombination and expression. A case in point are V delta 2D delta 3 and subsequent V delta 2D delta 3J alpha rearrangements observed in human leukemic pre-B cells as well as in normal lymphopoiesis. The functional expression of these unusual (VD) delta (JC) alpha hybrids is almost exclusively prevented by alternative splicing events. In this report we show that alternative splicing at cryptic splice donor sites within V elements is not a unique feature of hybrid TCR delta/alpha transcripts. Among seven V alpha families analyzed by RT-PCR, alternatively spliced products were observed in TCR alpha recombinations containing V alpha 1 or V alpha 14 elements. In contrast to normal peripheral blood cells and thymocytes, the leukemia cell line JM expressing functional V alpha 1J alpha 3C alpha transcripts lacked evidence of aberrant TCR alpha RNA species.

  4. Modification of cloned brain Na+ channels by batrachotoxin.

    Science.gov (United States)

    Wang, G K; Wang, S Y

    1994-06-01

    The effects of batrachotoxin (BTX) on cloned alpha-subunit Na+ channels were examined in CHO-K1 cells (a chinese hamster ovary cell line) transfected with rat brain NaIIA cDNA. Under whole-cell patch clamp conditions, BTX shifted the voltage dependence of the activation process by about 45 mV towards the hyperpolarizing direction and eliminated the inactivating phase of Na+ currents. Repetitive depolarizations greatly facilitated the binding of BTX with NaIIA channels while the membrane was held at -100 mV. In chloramine-T-pretreated cells, the association rate of BTX binding with the NaIIA channel was 6.5-fold faster than that in untreated cells. The estimated association rate constant for BTX binding with the open form of NaIIA channel was 1.11 x 10(6) mol-1.s-1 at room temperature. BTX-modified NaIIA channels were blocked by tetrodotoxin (TTX) in a complicated manner. First, the TTX binding to the closed state of BTX-modified NaIIA channels was not voltage dependent. The KD value of TTX was measured at 8.9 nM, which was similar to that of unmodified channels (KD = 14.2 nM). Second, the block of the open state of BTX-modified NaIIA channels by TTX was voltage dependent; depolarization reduced the potency of TTX block between -20 mV to +50 mV. Below -30 mV, the TTX affinity began to level off, probably because of the increased presence of the closed state. Unexpectedly, steady-state inactivation of BTX-modified NaIIA channels was minimal as measured by the two-pulse protocol, a phenomenon distinctly different from that found in GH3 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Activation of alpha6-containing GABAA receptors by pentobarbital occurs through a different mechanism than activation by GABA.

    Science.gov (United States)

    Fisher, Matthew T; Fisher, Janet L

    2010-03-08

    The GABA(A) receptors are ligand-gated chloride channels which are the targets for many clinically used sedatives, including the barbiturates. The barbiturate pentobarbital acts through multiple sites on the GABA(A) receptor. At low concentrations (muM), it acts as a positive allosteric modulator while at higher concentrations it can directly activate the receptor. This agonist action is influenced by the subunit composition of the receptor, and pentobarbital is a more effective agonist than GABA only at receptors containing an alpha6 subunit. The conformational change that translates GABA binding into channel opening is known to involve a lysine residue located in an extracellular domain between the 2nd and 3rd transmembrane domains. Mutations of this residue disrupt activation of the channel by GABA and have been linked to inherited epilepsy. Pentobarbital binds to the receptor at a different agonist site than GABA, but could use a common signal transduction mechanism to gate the channel. To address this question, we compared the effect of a mutating the homologous lysine residue in the alpha1 or alpha6 subunits (K278 or K277, respectively) to methionine on direct activation of recombinant GABA(A) receptors by GABA or pentobarbital. We found that this mutation reduced GABA sensitivity for both alpha1 and alpha6 subunits, but affected pentobarbital sensitivity only for the alpha1 subunit. This suggests that pentobarbital acts through a distinct signal transduction pathway at the alpha6 subunit, which may account for its greater efficacy compared to GABA at receptors containing this subunit.

  6. Alpha particles detection in nitrocellulose

    International Nuclear Information System (INIS)

    Romero C, M.

    1976-01-01

    The method for the manufacturing of the detection films follows these steps: preparation of the mass which includes nitrocellulose in the form of cotton as raw material ethyl acetate, cellosolve acetate, isopropyl and butyl alcohols as solvents and dioctyl phtalate as plasticiser; dilution of the paste; pouring of the diluted mass; and drying of the detection films. The results obtained experimentally are: The determination of the development times of the different thicknesses of the manufactured films. Response linearity of the detectors, variation of the number of tracks according to the distance of the source to the detector. Sizes of the diameter of the tracks depending of the distance detector-alpha emmission source. As a conclusion we can say the the nitrocellulose detectors are specific for alpha radiation; the more effective thicknesses in uranium prospecting works were those of 60 microns, since for the laboratory works the thicknesses of 30 to 40 microns were the ideal; the development technique of the detection films is simple and cheap and can be realized even in another place than the laboratory; this way of the manufacturing of nitrocellulose detection film sensitive to alpha nuclear radiation is open to future research. (author)

  7. Verapamil inhibits L-type calcium channel mediated apoptosis in human colon cancer cells.

    Science.gov (United States)

    Zawadzki, Antoni; Liu, Qing; Wang, Yusheng; Melander, Arne; Jeppsson, Bengt; Thorlacius, Henrik

    2008-11-01

    Treatment with calcium channel blockers have been associated with increased colon cancer mortality in epidemiologic studies. We examined the potential expression and function of calcium channels in two human colon cancer cell lines. Both primary (collected at operation) and commercially-available human colon cancer cell lines were used. The colon cancer cells were incubated with a calcium channel blocker (verapamil) and a calcium channel agonist (BayK 8644) at clinically relevant concentrations. L-type calcium channel mRNA was determined by reverse-transcription polymerase chain reaction. Intracellular calcium ion levels were measured with fluorometry and apoptosis with flow cytometry. Both types of cells expressed L-type calcium channel mRNA, comprising an alpha-1D and a beta-3 subunit, whereas the cells were negative for N-type and P-type channels. The selective calcium channel agonist (BayK 8644), dose-dependently increased intracellular calcium ion levels and the level of apoptosis in primary human colon cancer cells. Pretreatment with verapamil completely abolished both calcium channel agonist-induced influx of calcium and apoptosis in these cells. These data demonstrate that human colon cancer cells express L-type calcium channels that mediate calcium influx and apoptosis, which warrants further studies to determine whether calcium channel blockers may promote colon cancer growth.

  8. Measurement and analysis of $\\alpha$ particle induced reactions on yttrium

    CERN Document Server

    Singh, N L; Chintalapudi, S N

    2000-01-01

    Excitation functions for /sup 89/Y[( alpha ,3n); ( alpha ,4n); ( alpha , p3n); ( alpha , alpha n); ( alpha , alpha 2n)] reactions were measured up to 50 MeV using stacked foil activation technique and HPGe gamma ray spectroscopy method. The experimental data were compared with calculations considering equilibrium as well as preequilibrium reactions according to the hybrid model of Blann (ALICE/90). For ( alpha , xnyp) type of reactions, the precompound contributions are described by the model. There seems to be indications of direct inelastic scattering effects in ( alpha , alpha xn) type of reactions. To the best of our knowledge, the excitation functions for ( alpha ,4n), ( alpha , p3n), ( alpha , alpha n) and ( alpha , alpha 2n) reactions were measured for the first time. (23 refs).

  9. Measurement and analysis of alpha particle induced reactions on yttrium

    Energy Technology Data Exchange (ETDEWEB)

    Singh, N.L.; Gadkari, M.S. [Baroda Univ. (India). Dept. of Physics; Chintalapudi, S.N. [IUC-DAEF Calcutta Centre, Calcutta (India)

    2000-05-01

    Excitation functions for {sup 89}Y[({alpha},3n);({alpha},4n);({alpha},p3n);({alpha},{alpha}n);({alpha},{alpha}2n)] reactions were measured up to 50 MeV using stacked foil activation technique and HPGe gamma ray spectroscopy method. The experimental data were compared with calculations considering equilibrium as well as preequilibrium reactions according to the hybrid model of Blann (ALICE/90). For ({alpha},xnyp) type of reactions, the precompound contributions are described by the model. There seems to be indications of direct inelastic scattering effects in ({alpha},{alpha}xn) type of reactions. To the best of our knowledge, the excitation functions for ({alpha},4n), ({alpha},p3n), ({alpha},{alpha}n) and ({alpha},{alpha}2n) reactions were measured for the first time. (orig.)

  10. Interferon Alpha in Systemic Lupus Erythematosus

    Directory of Open Access Journals (Sweden)

    Timothy B. Niewold

    2010-01-01

    Full Text Available The pleiotropic cytokine interferon alpha is involved in multiple aspects of lupus etiology and pathogenesis. Interferon alpha is important under normal circumstances for antiviral responses and immune activation. However, heightened levels of serum interferon alpha and expression of interferon response genes are common in lupus patients. Lupus-associated autoantibodies can drive the production of interferon alpha and heightened levels of interferon interfere with immune regulation. Several genes in the pathways leading to interferon production or signaling are associated with risk for lupus. Clinical and cellular manifestations of excess interferon alpha in lupus combined with the genetic risk factors associated with interferon make this cytokine a rare bridge between genetic risk and phenotypic effects. Interferon alpha influences the clinical picture of lupus and may represent a therapeutic target. This paper provides an overview of the cellular, genetic, and clinical aspects of interferon alpha in lupus.

  11. Novel alpha-mannosidase inhibitors; Nye alfa-mannosidaseinhibitorer

    Energy Technology Data Exchange (ETDEWEB)

    Farr, R.A.; Kang, M.S.; Peet, N.P.; Sunkara, S.P.

    1997-05-20

    [4S-(4{alpha}, 4a{beta}, 6{alpha}, 7{alpha}, 7a{alpha})]-Octahydro-1H-1-pyridine-4,5,6,7-tetrols and [4R-(4{alpha}, 4a{alpha}, 5{alpha}, 6{beta}, 7{beta}, 7a{beta})]-octahydro-1H-1-pyridine-4,5,6,7-tetrols are useful inhibitors of alpha-mannosidase and are useful immunostimulants, chemoprotective and radioprotective agents and antimetastatic agents.

  12. Channels of Propaganda.

    Science.gov (United States)

    Sproule, J. Michael

    Defining propaganda as "efforts by special interests to win over the public covertly by infiltrating messages into various channels of public expression ordinarily viewed as politically neutral," this book argues that propaganda has become pervasive in American life. Pointing out that the 1990s society is inundated with propaganda from…

  13. Chemistry in Microfluidic Channels

    Science.gov (United States)

    Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

    2011-01-01

    General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

  14. Calcium influx through hyperpolarization-activated cation channels (I(h) channels) contributes to activity-evoked neuronal secretion.

    Science.gov (United States)

    Yu, Xiao; Duan, Kai-Lai; Shang, Chun-Feng; Yu, Han-Gang; Zhou, Zhuan

    2004-01-27

    The hyperpolarization-activated cation channels (I(h)) play a distinct role in rhythmic activities in a variety of tissues, including neurons and cardiac cells. In the present study, we investigated whether Ca(2+) can permeate through the hyperpolarization-activated pacemaker channels (HCN) expressed in HEK293 cells and I(h) channels in dorsal root ganglion (DRG) neurons. Using combined measurements of whole-cell currents and fura-2 Ca(2+) imaging, we found that there is a Ca(2+) influx in proportion to I(h) induced by hyperpolarization in HEK293 cells. The I(h) channel blockers Cs(+) and ZD7288 inhibit both HCN current and Ca(2+) influx. Measurements of the fractional Ca(2+) current showed that it constitutes 0.60 +/- 0.02% of the net inward current through HCN4 at -120 mV. This fractional current is similar to that of the low Ca(2+)-permeable AMPA-R (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor) channels in Purkinje neurons. In DRG neurons, activation of I(h) for 30 s also resulted in a Ca(2+) influx and an elevated action potential-induced secretion, as assayed by the increase in membrane capacitance. These results suggest a functional significance for I(h) channels in modulating neuronal secretion by permitting Ca(2+) influx at negative membrane potentials.

  15. Channeling through Bent Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mack, Stephanie; /Ottawa U. /SLAC

    2012-09-07

    Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal placed at the edge of a particle beam, part of the fringe of the beam can be deflected away towards a detector or beam dump, thus helping collimate the beam. There is currently FORTRAN code by Igor Yazynin that has been used to model the passage of particles through a bent crystal. Using this code, the effects mentioned were explored for beam energy that would be seen at the Facility for Advanced Accelerator Experimental Tests (FACET) at a range of crystal orientations with respect to the incoming beam. After propagating 5 meters in vacuum space past the crystal the channeled particles were observed to separate from most of the beam with some noise due to dechanneled particles. Progressively smaller bending radii, with corresponding shorter crystal lengths, were compared and it was seen that multiple scattering decreases with the length of the crystal therefore allowing for cleaner detection of the channeled particles. The input beam was then modified and only a portion of the beam sent through the crystal. With the majority of the beam not affected by the crystal, most particles were not deflected and after propagation the channeled particles were seen to be deflected approximately 5mm. After a portion of the beam travels through the crystal, the entire beam was then sent through a quadrupole magnet, which increased the separation of the channeled particles from the remainder of the beam to a distance of around 20mm. A different code, which was developed at SLAC, was used to

  16. Monitoring alpha oscillations and pupil dilation across the performance-intensity function

    Directory of Open Access Journals (Sweden)

    Catherine M McMahon

    2016-05-01

    Full Text Available Listening to degraded speech can be challenging and requires a continuous investment of cognitive resources, which is more challenging for those with hearing loss. However, while alpha power (8-12 Hz and pupil dilation have been suggested as objective correlates of listening effort, it is not clear whether they assess the same cognitive processes involved, or other sensory and/or neurophysiological mechanisms that are associated with the task. Therefore, the aim of this study is to compare alpha power and pupil dilation during a sentence recognition task in 15 randomized levels of noise (-7dB to +7dB SNR using highly intelligible (16 channel vocoded and moderately intelligible (6 channel vocoded speech. Twenty young normal hearing adults participated in the study; however, due to extraneous noise, data from 16 (10 females, 6 males; aged 19-28 years was used in the EEG analysis and 10 in the pupil analysis. Behavioral testing of perceived effort and speech performance was assessed at 3 fixed SNRs per participant and was comparable to sentence recognition performance assessed in the physiological test session for both 16- and 6-channel vocoded sentences. Results showed a significant interaction between channel vocoding for both the alpha power and the pupil size changes. While both measures significantly decreased with more positive SNRs for the 16-channel vocoding, this was not observed with the 6-channel vocoding. The results of this study suggest that these measures may encode different processes involved in speech perception, which show similar trends for highly intelligible speech, but diverge for more spectrally degraded speech. The results to date suggest that these objective correlates of listening effort, and the cognitive processes involved in listening effort, are not yet sufficiently well understood to be used within a clinical setting.

  17. Identification of Small-Molecule Frequent Hitters from AlphaScreen High-Throughput Screens.

    Science.gov (United States)

    Schorpp, Kenji; Rothenaigner, Ina; Salmina, Elena; Reinshagen, Jeanette; Low, Terence; Brenke, Jara K; Gopalakrishnan, Jay; Tetko, Igor V; Gul, Sheraz; Hadian, Kamyar

    2014-06-01

    Although small-molecule drug discovery efforts have focused largely on enzyme, receptor, and ion-channel targets, there has been an increase in such activities to search for protein-protein interaction (PPI) disruptors by applying high-throughout screening (HTS)-compatible protein-binding assays. However, a disadvantage of these assays is that many primary hits are frequent hitters regardless of the PPI being investigated. We have used the AlphaScreen technology to screen four different robust PPI assays each against 25,000 compounds. These activities led to the identification of 137 compounds that demonstrated repeated activity in all PPI assays. These compounds were subsequently evaluated in two AlphaScreen counter assays, leading to classification of compounds that either interfered with the AlphaScreen chemistry (60 compounds) or prevented the binding of the protein His-tag moiety to nickel chelate (Ni(2+)-NTA) beads of the AlphaScreen detection system (77 compounds). To further triage the 137 frequent hitters, we subsequently confirmed by a time-resolved fluorescence resonance energy transfer assay that most of these compounds were only frequent hitters in AlphaScreen assays. A chemoinformatics analysis of the apparent hits provided details of the compounds that can be flagged as frequent hitters of the AlphaScreen technology, and these data have broad applicability for users of these detection technologies. © 2013 Society for Laboratory Automation and Screening.

  18. Activator protein 2alpha mediates parathyroid TGF-alpha self-induction in secondary hyperparathyroidism.

    Science.gov (United States)

    Arcidiacono, Maria Vittoria; Cozzolino, Mario; Spiegel, Noah; Tokumoto, Masanori; Yang, Jing; Lu, Yan; Sato, Tetsuhiko; Lomonte, Carlo; Basile, Carlo; Slatopolsky, Eduardo; Dusso, Adriana S

    2008-10-01

    In secondary hyperparathyroidism, enhanced expression of TGF-alpha in the parathyroid leads to its own upregulation, generating a feed-forward loop for TGF-alpha activation of its receptor, EGFR receptor (EGFR), which promotes parathyroid hyperplasia. These studies examined the role of activator protein 2alpha (AP2), an inducer of TGF-alpha gene transcription, in the upregulation of parathyroid TGF-alpha in secondary hyperparathyroidism. In rat and human secondary hyperparathyroidism, parathyroid AP2 expression strongly correlated with TGF-alpha levels and with the rate of parathyroid growth, as expected. Furthermore, the increases in rat parathyroid content of AP2 and its binding to a consensus AP2 DNA sequence preceded the increase in TGF-alpha induced by high dietary phosphate. More significant, in A431 cells, which provide a model of enhanced TGF-alpha and TGF-alpha self-induction, mutating the core AP2 site of the human TGF-alpha promoter markedly impaired promoter activity induced by endogenous or exogenous TGF-alpha. Important for therapy, in five-sixths nephrectomized rats fed high-phosphate diets, inhibition of parathyroid TGF-alpha self-induction using erlotinib, a highly specific inhibitor of TGF-alpha/EGFR-driven signals, reduced AP2 expression dosage dependently. This suggests that the increases in parathyroid AP2 occur downstream of EGFR activation by TGF-alpha and are required for TGF-alpha self-induction. Indeed, in A431 cells, erlotinib inhibition of TGF-alpha self-induction caused parallel reductions in AP2 expression and nuclear localization, as well as TGF-alpha mRNA and protein levels. In summary, increased AP2 expression and transcriptional activity at the TGF-alpha promoter determine the severity of the hyperplasia driven by parathyroid TGF-alpha self-upregulation in secondary hyperparathyroidism.

  19. Morphology of. alpha. phse transforming from. beta. prime phase in Cu-41. 7% Zn alloys by lower temperature annealing. beta. prime tanso Cu-41. 7 wt% Zn gokin no teion yakinamashi de seiseisuru. alpha. so no keitai

    Energy Technology Data Exchange (ETDEWEB)

    Tada, S.; Matsuda, K. (Toyama Univ., Toyama (Japan). Faculty of Engineering); Aoki, M. (Toyama Univ., Toyama (Japan). Graduate Shool); Uetani, Y. (Toyama Preface College of Techlogy, Toyama (Japan)); Ikeno, S. (Toyama Univ., Toyama (Japan). Center for Cooperative Research)

    1992-02-15

    The characteristics of {alpha} phase seems to be clarified better and basic data which elucidate the formation and growth process may be acquired if the shape of {alpha} phase in the early stage of formation is observed. The crystal orientation is measured in advance by SEM-ECP (scanning electron microscope-electron channeling pattern) method to select crystal grains of {beta} {prime} matrix having specific orientation, and the shape of the {alpha} phase formed by low temperature annealing is investigated. The embossed {alpha} phase at (011) {beta} {prime} matrix plane can be divided into two groups in shape as triangles and bent bars. The embossed {alpha} phase in (011) {beta} {prime} matrix plane is found to stand straight if tilted by 32{degree} to become parallel to the direction of observation, and to become vertical if tilted by 45{degree}. At (111) {beta}{prime} matrix plane, it is made clear that the {alpha} phase consists of a pair of two {alpha} plates. It becomes clear that such a pair of {alpha} plates are combined with other pairs to build up more complex forms. 11 refs., 8 figs.

  20. cPLA2alpha-evoked formation of arachidonic acid and lysophospholipids is required for exocytosis in mouse pancreatic beta-cells

    DEFF Research Database (Denmark)

    Juhl, Kirstine; Høy, Marianne; Olsen, Hervør L

    2003-01-01

    Using capacitance measurements, we investigated the effects of intracellularly applied recombinant human cytosolic phospholipase A2 (cPLA2alpha) and its lipolytic products arachidonic acid and lysophosphatidylcholine on Ca2+-dependent exocytosis in single mouse pancreatic beta-cells. cPLA2alpha...... from 70-80 to 280-300. cPLA2alpha-stimulated exocytosis was antagonized by the specific cPLA2 inhibitor AACOCF3. Ca2+-evoked exocytosis was reduced by 40% in cells treated with AACOCF3 or an antisense oligonucleotide against cPLA2alpha. The action of cPLA2alpha was mimicked by a combination...... of arachidonic acid and lysophosphatidylcholine (470% stimulation) in which each compound alone doubled the exocytotic response. Priming of insulin-containing secretory granules has been reported to involve Cl- uptake through ClC-3 Cl- channels. Accordingly, the stimulatory action of cPLA2alpha was inhibited...

  1. Characterization of a series of anabaseine-derived compounds reveals that the 3-(4)-dimethylaminocinnamylidine derivative is a selective agonist at neuronal nicotinic alpha 7/125I-alpha-bungarotoxin receptor subtypes.

    Science.gov (United States)

    de Fiebre, C M; Meyer, E M; Henry, J C; Muraskin, S I; Kem, W R; Papke, R L

    1995-01-01

    Investigation of the naturally occurring, nicotinic agonist anabaseine and novel derivatives has shown that these compounds have cytoprotective and memory-enhancing effects. The hypothesis that these arise at least in part through actions on brain nicotinic receptors was evaluated by examining the ability of these compounds to displace the binding of nicotinic ligands and to affect the function of the alpha 4 beta 2 and alpha 7 receptor subtypes expressed in Xenopus oocytes. The derivative 3-(4)-dimethylaminocinnamylidine anabaseine (DMAC) was found to be a selective alpha 7 receptor agonist; it was more potent than nicotine, acetylcholine, anabaseine, and other derivatives at activating the alpha 7 receptor subtype, while displaying little agonist activity at alpha 4 beta 2 and other receptor subtypes. Compared with anabaseine and the other derivatives, DMAC was the most potent at displacing 125I-alpha-bungarotoxin binding (putative alpha 7) and the least potent at displacing [3H]cytisine binding (putative alpha 4 beta 2) to brain membranes. Independently of agonist activities, all of the novel compounds displayed secondary inhibitory activity at both receptor subtypes. At the alpha 4 beta 2 receptor subtype, inhibition by the 3-(2,4)-dimethoxybenzylidene derivative was enhanced by coapplication of acetylcholine, suggesting a noncompetitive form of inhibition. Anabaseine and nicotine prolonged the time course of activation of alpha 4 beta 2 receptors, compared with acetylcholine, suggesting sequential channel-blocking activity. As selective agonists, anabaseine derivatives such as DMAC may be useful for elucidating the function of alpha 7 nicotinic receptors, including their potential role(s) in the cytoprotective and memory-enhancing effects of nicotinic agents.

  2. Distribution and function of sodium channel subtypes in human atrial myocardium

    NARCIS (Netherlands)

    Kaufmann, Susann G.; Westenbroek, Ruth E.; Maass, Alexander H.; Lange, Volkmar; Renner, Andre; Wischmeyer, Erhard; Bonz, Andreas; Muck, Jenny; Ertl, Georg; Catterall, William A.; Scheuer, Todd; Maier, Sebastian K. G.

    Voltage-gated sodium channels composed of a pore-forming alpha subunit and auxiliary beta subunits are responsible for the upstroke of the action potential in cardiac muscle. However, their localization and expression patterns in human myocardium have not yet been clearly defined. We used

  3. Use of Large Surface MicroChannel Plates for the Tagging of Intermediate Energy Exotic Beams

    International Nuclear Information System (INIS)

    Lombardo, I.; Amorini, F.; Cardella, G.; Cavallaro, S.; De Filippo, E.; Geraci, E.; Grassi, L.; La Guidara, E.; Lanzalone, G.; Pagano, A.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Rizzo, F.; Russotto, P.; Verde, G.; Vigilante, M.

    2011-01-01

    We show the properties of the tagging system for exotic beams coupled to the CHIMERA detector. In particular, the characteristics of a newly developed large surface MicroChannel Plate will be discussed. Timing and efficiency of this instrument have been investigated. Preliminary results of tests performed with radioactive beams and alpha sources are presented.

  4. Alpha particle studies during JET DT experiments

    International Nuclear Information System (INIS)

    1999-01-01

    The 1997 DT experiment (DTE1) at the Joint European Torus included studies of the behaviour of alpha particles in high temperature plasmas. Clear alpha particle heating was observed in a series of otherwise similar 10MW hot-ion H-modes by scanning the DT mixture from 0%T to 93%T. Maxima in central temperature and energy content were obtained which corresponded with the maximum in fusion yield. Alfven Eigenmodes (AEs) have been detected in JET, driven by NBI or ICRH fast ions. However, in agreement with theory, no AE activity was observed in DT plasmas which could be attributed to alpha particle drive, except in the afterglow of some Optimised Shear pulses. Ion Cyclotron Emission (ICE) was detected at harmonics of the alpha particle cyclotron frequency at the outer edge of the plasma. The ICE is interpreted as being close to magnetoacoustic cyclotron instability, driven by inverted alpha distributions at the plasma edge. The high-energy neutral particle spectra showed features, which are ascribed to a mixture of alphas, neutralised by helium-like impurities, and deuterons, born from elastic collisions with alpha particles and neutralised by hydrogen-like impurities. The results of all these studies are consistent with classical alpha particle trapping and slowing-down. Future DT experiments will aim to increase alpha particle pressure, so interactions with plasma instabilities can be studied. The measurement of knock-on neutral triton spectra offers a clean way to determine confined alpha densities in these future experiments. (author)

  5. Alpha particle studies during JET DT experiments

    International Nuclear Information System (INIS)

    2001-01-01

    The 1997 DT experiment (DTE1) at the Joint European Torus included studies of the behaviour of alpha particles in high temperature plasmas. Clear alpha particle heating was observed in a series of otherwise similar 10MW hot-ion H-modes by scanning the DT mixture from 0%T to 93%T. Maxima in central temperature and energy content were obtained which corresponded with the maximum in fusion yield. Alfven Eigenmodes (AEs) have been detected in JET, driven by NBI or ICRH fast ions. However, in agreement with theory, no AE activity was observed in DT plasmas which could be attributed to alpha particle drive, except in the afterglow of some Optimised Shear pulses. Ion Cyclotron Emission (ICE) was detected at harmonics of the alpha particle cyclotron frequency at the outer edge of the plasma. The ICE is interpreted as being close to magnetoacoustic cyclotron instability, driven by inverted alpha distributions at the plasma edge. The high-energy neutral particle spectra showed features, which are ascribed to a mixture of alphas, neutralised by helium-like impurities, and deuterons, born from elastic collisions with alpha particles and neutralised by hydrogen-like impurities. The results of all these studies are consistent with classical alpha particle trapping and slowing-down. Future DT experiments will aim to increase alpha particle pressure, so interactions with plasma instabilities can be studied. The measurement of knock-on neutral triton spectra offers a clean way to determine confined alpha densities in these future experiments. (author)

  6. The Alpha Magnetic Spectrometer (AMS)

    CERN Document Server

    Alcaraz, J; Ambrosi, G; Anderhub, H; Ao, L; Arefev, A; Azzarello, P; Babucci, E; Baldini, L; Basile, M; Barancourt, D; Barão, F; Barbier, G; Barreira, G; Battiston, R; Becker, R; Becker, U; Bellagamba, L; Bene, P; Berdugo, J; Berges, P; Bertucci, B; Biland, A; Bizzaglia, S; Blasko, S; Bölla, G; Boschini, M; Bourquin, Maurice; Brocco, L; Bruni, G; Buénerd, M; Burger, J D; Burger, W J; Cai, X D; Camps, C; Cannarsa, P; Capell, M; Casadei, D; Casaus, J; Castellini, G; Cecchi, C; Chang, Y H; Chen, H F; Chen, H S; Chen, Z G; Chernoplekov, N A; Tzi Hong Chiueh; Chuang, Y L; Cindolo, F; Commichau, V; Contin, A; Crespo, P; Cristinziani, M; Cunha, J P D; Dai, T S; Deus, J D; Dinu, N; Djambazov, L; Dantone, I; Dong, Z R; Emonet, P; Engelberg, J; Eppling, F J; Eronen, T; Esposito, G; Extermann, P; Favier, Jean; Fiandrini, E; Fisher, P H; Flügge, G; Fouque, N; Galaktionov, Yu; Gervasi, M; Giusti, P; Grandi, D; Grimm, O; Gu, W Q; Hangarter, K; Hasan, A; Hermel, V; Hofer, H; Huang, M A; Hungerford, W; Ionica, M; Ionica, R; Jongmanns, M; Karlamaa, K; Karpinski, W; Kenney, G; Kenny, J; Kim, W; Klimentov, A; Kossakowski, R; Koutsenko, V F; Kraeber, M; Laborie, G; Laitinen, T; Lamanna, G; Laurenti, G; Lebedev, A; Lee, S C; Levi, G; Levchenko, P M; Liu, C L; Liu, H T; Lopes, I; Lu, G; Lü, Y S; Lübelsmeyer, K; Luckey, D; Lustermann, W; Maña, C; Margotti, A; Mayet, F; McNeil, R R; Meillon, B; Menichelli, M; Mihul, A; Mourao, A; Mujunen, A; Palmonari, F; Papi, A; Park, I H; Pauluzzi, M; Pauss, Felicitas; Perrin, E; Pesci, A; Pevsner, A; Pimenta, M; Plyaskin, V; Pozhidaev, V; Postolache, V; Produit, N; Rancoita, P G; Rapin, D; Raupach, F; Ren, D; Ren, Z; Ribordy, M; Richeux, J P; Riihonen, E; Ritakari, J; Röser, U; Roissin, C; Sagdeev, R; Sartorelli, G; Schwering, G; Scolieri, G; Seo, E S; Shoutko, V; Shoumilov, E; Siedling, R; Son, D; Song, T; Steuer, M; Sun, G S; Suter, H; Tang, X W; Ting, Samuel C C; Ting, S M; Tornikoski, M; Torsti, J; Ulbricht, J; Urpo, S; Usoskin, I; Valtonen, E; Vandenhirtz, J; Velcea, F; Velikhov, E P; Verlaat, B; Vetlitskii, I; Vezzu, F; Vialle, J P; Viertel, Gert M; Vitè, Davide F; Gunten, H V; Wallraff, W; Wang, B C; Wang, J Z; Wang, Y H; Wiik, K; Williams, C; Wu, S X; Xia, P C; Yan, J L; Yan, L G; Yang, C G; Yang, M; Ye, S W; Yeh, P; Xu, Z Z; Zhang, H Y; Zhang, Z P; Zhao, D X; Zhu, G Y; Zhu, W Z; Zhuang, H L; Zichichi, A; Zimmermann, B

    2002-01-01

    The Alpha Magnetic Spectrometer (AMS) is a large acceptance (0.65 sr m sup 2) detector designed to operate in the International Space Station (ISS) for three years. The purposes of the experiment are to search for cosmic antimatter and dark matter and to study the composition and energy spectrum of the primary cosmic rays. A 'scaled-down' version has been flown on the Space Shuttle Discovery for 10 days in June 1998. The complete AMS is programmed for installation on the ISS in October 2003 for an operational period of 3 yr. This contribution reports on the experimental configuration that will be installed on the ISS.

  7. Targeted alpha therapy for cancer

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Barry J [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Raja, Chand [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Rizvi, Syed [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Li Yong [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Tsui, Wendy [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Zhang, David [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Song, Emma [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Qu, C F [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Kearsley, John [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Graham, Peter [Centre for Experimental Radiation Oncology, St George Cancer Care Centre, Gray St, Kogarah 2217, NSW (Australia); Thompson, John [Sydney Melanoma Unit, Royal Prince Alfred Hospital, Camperdown 2050 NSW (Australia)

    2004-08-21

    Targeted alpha therapy (TAT) offers the potential to inhibit the growth of micrometastases by selectively killing isolated and preangiogenic clusters of cancer cells. The practicality and efficacy of TAT is tested by in vitro and in vivo studies in melanoma, leukaemia, colorectal, breast and prostate cancers, and by a phase 1 trial of intralesional TAT for melanoma. The alpha-emitting radioisotope used is Bi-213, which is eluted from the Ac-225 generator and chelated to a cancer specific monoclonal antibody (mab) or protein (e.g. plasminogen activator inhibitor-2 PAI2) to form the alpha-conjugate (AC). Stable alpha-ACs have been produced which have been tested for specificity and cytotoxicity in vitro against melanoma (9.2.27 mab), leukaemia (WM60), colorectal (C30.6), breast (PAI2, herceptin), ovarian (PAI2, herceptin, C595), prostate (PAI2, J591) and pancreatic (PAI2, C595) cancers. Subcutaneous inoculation of 1-1.5 million human cancer cells into the flanks of nude mice causes tumours to grow in all mice. Tumour growth is compared for untreated controls, nonspecific AC and specific AC, for local (subcutaneous) and systemic (tail vein or intraperitoneal) injection models. The {sup 213}Bi-9.2.27 AC is injected into secondary skin melanomas in stage 4 patients in a dose escalation study to determine the effective tolerance dose, and to measure kinematics to obtain the equivalent dose to organs. In vitro studies show that TAT is one to two orders of magnitude more cytotoxic to targeted cells than non-specific ACs, specific beta emitting conjugates or free isotopes. In vivo local TAT at 2 days post-inoculation completely prevents tumour formation for all cancers tested so far. Intra-lesional TAT can completely regress advanced sc melanoma but is less successful for breast and prostate cancers. Systemic TAT inhibits the growth of sc melanoma xenografts and gives almost complete control of breast and prostate cancer tumour growth. Intralesional doses up to 450 {mu

  8. The Alpha Magnetic Spectrometer (ams)

    Science.gov (United States)

    Ionica, Maria

    2004-01-01

    The Alpha Magnetic Spectrometer (AMS), once installed on the International Space Station will provide precise measurements of the cosmic ray spectra up to TeV energy range, and will search for cosmological antimatter and missing matter. A prototype version of the detector was operated successfully on the space shuttle Discovery in June 1998 (STS-91). Here we briefly report on the design of the AMS apparatus and present the results of the measurements of the fluxes of proton, electron, positron and helium from the STS-91 flight.

  9. Crossing symmetry in Alpha space

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    The conformal bootstrap program aims to catalog all conformal field theories (second-order phase transitions) in D dimensions. Despite its ambitious scope much progress has been made over the past decade, e.g. in computing critical exponents for the 3D O(N) models to high precision. At this stage, analytic methods to explore the CFT landscape are not as well developed. In this talk I will describe a new mathematical framework for the bootstrap known as "alpha space", which reduces crossing symmetry to a set of integral equations. Based on arXiv:1702.08471 (with Balt van Rees) and arXiv:1703.08159.

  10. The Alpha Magnetic Spectrometer (AMS)

    International Nuclear Information System (INIS)

    Alcaraz, J.; Alpat, B.; Ambrosi, G.; Anderhub, H.; Ao, L.; Arefiev, A.; Azzarello, P.; Babucci, E.; Baldini, L.; Basile, M.; Barancourt, D.; Barao, F.; Barbier, G.; Barreira, G.; Battiston, R.; Becker, R.; Becker, U.; Bellagamba, L.; Bene, P.; Berdugo, J.; Berges, P.; Bertucci, B.; Biland, A.; Bizzaglia, S.; Blasko, S.; Boella, G.; Boschini, M.; Bourquin, M.; Brocco, L.; Bruni, G.; Buenerd, M.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Camps, C.; Cannarsa, P.; Capell, M.; Casadei, D.; Casaus, J.; Castellini, G.; Cecchi, C.; Chang, Y.H.; Chen, H.F.; Chen, H.S.; Chen, Z.G.; Chernoplekov, N.A.; Chiueh, T.H.; Chuang, Y.L.; Cindolo, F.; Commichau, V.; Contin, A.; Crespo, P.; Cristinziani, M.; Cunha, J.P. da; Dai, T.S.; Deus, J.D.; Dinu, N.; Djambazov, L.; DAntone, I.; Dong, Z.R.; Emonet, P.; Engelberg, J.; Eppling, F.J.; Eronen, T.; Esposito, G.; Extermann, P.; Favier, J.; Fiandrini, E.; Fisher, P.H.; Fluegge, G.; Fouque, N.; Galaktionov, Yu.; Gervasi, M.; Giusti, P.; Grandi, D.; Grimm, O.; Gu, W.Q.; Hangarter, K.; Hasan, A.; Hermel, V.; Hofer, H.; Huang, M.A.; Hungerford, W.; Ionica, M.; Ionica, R.; Jongmanns, M.; Karlamaa, K.; Karpinski, W.; Kenney, G.; Kenny, J.; Kim, W.; Klimentov, A.; Kossakowski, R.; Koutsenko, V.; Kraeber, M.; Laborie, G.; Laitinen, T.; Lamanna, G.; Laurenti, G.; Lebedev, A.; Lee, S.C.; Levi, G.; Levtchenko, P.; Liu, C.L.; Liu, H.T.; Lopes, I.; Lu, G.; Lu, Y.S.; Luebelsmeyer, K.; Luckey, D.; Lustermann, W.; Mana, C.; Margotti, A.; Mayet, F.; McNeil, R.R.; Meillon, B.; Menichelli, M.; Mihul, A.; Mourao, A.; Mujunen, A.; Palmonari, F.; Papi, A.; Park, I.H.; Pauluzzi, M.; Pauss, F.; Perrin, E.; Pesci, A.; Pevsner, A.; Pimenta, M.; Plyaskin, V.; Pojidaev, V.; Postolache, V.; Produit, N.; Rancoita, P.G.; Rapin, D.; Raupach, F.; Ren, D.; Ren, Z.; Ribordy, M.; Richeux, J.P.; Riihonen, E.; Ritakari, J.; Roeser, U.; Roissin, C.; Sagdeev, R.; Sartorelli, G.; Schultz von Dratzig, A.; Schwering, G.; Scolieri, G.; Seo, E.S.; Shoutko, V.; Shoumilov, E.; Siedling, R.; Son, D.; Song, T.; Steuer, M.; Sun, G.S.; Suter, H.; Tang, X.W.; Ting, S.C.C.Samuel C.C.; Ting, S.M.; Tornikoski, M.; Torsti, J.; Tr umper, J.; Ulbricht, J.; Urpo, S.; Usoskin, I.; Valtonen, E.; Vandenhirtz, J.; Velcea, F.; Velikhov, E.; Verlaat, B.; Vetlitsky, I.; Vezzu, F.; Vialle, J.P.; Viertel, G.; Vite, D.; Gunten, H. Von; Wicki, S.W.S. Waldmeier; Wallraff, W.; Wang, B.C.; Wang, J.Z.; Wang, Y.H.; Wiik, K.; Williams, C.; Wu, S.X.; Xia, P.C.; Yan, J.L.; Yan, L.G.; Yang, C.G.; Yang, M.; Ye, S.W.; Yeh, P.; Xu, Z.Z.; Zhang, H.Y.; Zhang, Z.P.; Zhao, D.X.; Zhu, G.Y.; Zhu, W.Z.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.

    2002-01-01

    The Alpha Magnetic Spectrometer (AMS) is a large acceptance (0.65 sr m 2 ) detector designed to operate in the International Space Station (ISS) for three years. The purposes of the experiment are to search for cosmic antimatter and dark matter and to study the composition and energy spectrum of the primary cosmic rays. A 'scaled-down' version has been flown on the Space Shuttle Discovery for 10 days in June 1998. The complete AMS is programmed for installation on the ISS in October 2003 for an operational period of 3 yr. This contribution reports on the experimental configuration that will be installed on the ISS

  11. Application of the lattice Boltzmann method to transition in oscillatory channel flow

    CERN Document Server

    Cosgrove, J A; Tonge, S J; Munro, C G; Greated, C A; Campbell, D M

    2003-01-01

    In this study the applicability of the lattice Boltzmann method to oscillatory channel flow with a zero mean velocity has been evaluated. The model has been compared to exact analytical solutions in the laminar case (Re subdelta < 100, where Re subdelta is the Reynolds number based on the Stokes layer) for the Womersley parameter 1 < alpha < 31. In this regime, there was good agreement between numerical and exact analytical solutions. The model was then applied to study the primary instability of oscillatory channel flow with a zero mean velocity. For these transitionary flows the parameters were varied in the range 400 < Re subdelta < 1000 and 4 < alpha < 16. Disturbances superimposed on the numerical solution triggered the two-dimensional primary instability. This phenomenon has not been numerically evaluated over the range of alpha or Re subdelta currently investigated. The results are consistent with quasi-steady linear stability theories and previous numerical investigations.

  12. Quantum communication under channel uncertainty

    International Nuclear Information System (INIS)

    Noetzel, Janis Christian Gregor

    2012-01-01

    This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

  13. Learning Channels and Verbal Behavior

    Science.gov (United States)

    Lin, Fan-Yu; Kubina, Richard M., Jr.

    2004-01-01

    This article reviews the basics of learning channels and how specification of stimuli can help enhance verbal behavior. This article will define learning channels and the role of the ability matrix in training verbal behavior.

  14. Molecular and functional expression of high conductance Ca 2+ activated K+ channels in the eel intestinal epithelium

    DEFF Research Database (Denmark)

    Lionetto, Maria G; Rizzello, Antonia; Giordano, Maria E

    2008-01-01

    Several types of K(+) channels have been identified in epithelial cells. Among them high conductance Ca(2+)-activated K(+) channels (BK channels) are of relevant importance for their involvement in regulatory volume decrease (RVD) response following hypotonic stress. The aim of the present work...... was to investigate the functional and molecular expression of BK in the eel intestine, which is a useful experimental model for cell volume regulation research. In the present paper using rat BK channel-specific primer, a RT-PCR signal of 696 pb cDNA was detected in eel intestine, whole nucleotide sequence showed...... high similarity (83%) to the alpha subunit of BK channel family. BK channel protein expression was verified by immunoblotting and confocal microscopy, while the functional role of BK channels in epithelial ion transport mechanisms and cell volume regulation was examined by electrophysiological...

  15. The KCNQ1 potassium channel is down-regulated by ubiquitylating enzymes of the Nedd4/Nedd4-like family

    DEFF Research Database (Denmark)

    Jespersen, Thomas; Membrez, Mathieu; Nicolas, Céline S

    2007-01-01

    OBJECTIVE: The voltage-gated KCNQ1 potassium channel regulates key physiological functions in a number of tissues. In the heart, KCNQ1 alpha-subunits assemble with KCNE1 beta-subunits forming a channel complex constituting the delayed rectifier current I(Ks). In epithelia, KCNQ1 channels...... that KCNQ1 internalization and stability is physiologically regulated by its Nedd4/Nedd4-like-dependent ubiquitylation. This mechanism may thereby be important in regulating the surface density of the KCNQ1 channels in cardiomyocytes and other cell types....

  16. Changes in ion channel geometry resolved to sub-ångström precision via single molecule mass spectrometry

    Science.gov (United States)

    Robertson, Joseph W. F.; Kasianowicz, John J.; Reiner, Joseph E.

    2010-11-01

    The ion channel formed by Staphylococcus aureus alpha-hemolysin switches between multiple open conducting states. We describe a method for precisely estimating the changes in the ion channel geometry that correspond to these different states. Experimentally, we observed that the permeability of a single channel to differently sized poly(ethylene glycol) molecules depends on the magnitude of the open state conductance. A simple theory is proposed for determining changes in channel length of 4.2% and in cross-sectional area of - 0.4%.

  17. ``Just Another Distribution Channel?''

    Science.gov (United States)

    Lemstra, Wolter; de Leeuw, Gerd-Jan; van de Kar, Els; Brand, Paul

    The telecommunications-centric business model of mobile operators is under attack due to technological convergence in the communication and content industries. This has resulted in a plethora of academic contributions on the design of new business models and service platform architectures. However, a discussion of the challenges that operators are facing in adopting these models is lacking. We assess these challenges by considering the mobile network as part of the value system of the content industry. We will argue that from the perspective of a content provider the mobile network is ‘just another’ distribution channel. Strategic options available for the mobile communication operators are to deliver an excellent distribution channel for content delivery or to move upwards in the value chain by becoming a content aggregator. To become a mobile content aggregator operators will have to develop or acquire complementary resources and capabilities. Whether this strategic option is sustainable remains open.

  18. Geysering in boiling channels

    Energy Technology Data Exchange (ETDEWEB)

    Aritomi, Masanori; Takemoto, Takatoshi [Tokyo Institute of Technology, Tokyo (Japan); Chiang, Jing-Hsien [Japan NUS Corp. Ltd., Toyko (Japan)] [and others

    1995-09-01

    A concept of natural circulation BWRs such as the SBWR has been proposed and seems to be promising in that the primary cooling system can be simplified. The authors have been investigating thermo-hydraulic instabilities which may appear during the start-up in natural circulation BWRs. In our previous works, geysering was investigated in parallel boiling channels for both natural and forced circulations, and its driving mechanism and the effect of system pressure on geysering occurrence were made clear. In this paper, geysering is investigated in a vertical column and a U-shaped vertical column heated in the lower parts. It is clarified from the results that the occurrence mechanism of geysering and the dependence of system pressure on geysering occurrence coincide between parallel boiling channels in circulation systems and vertical columns in non-circulation systems.

  19. Sepsis causes presynaptic histamine H3 and alpha2-adrenergic dysfunction in canine myocardium.

    Science.gov (United States)

    Cheng, Zao-Qin; Bose, Deepak; Jacobs, Han; Light, R Bruce; Mink, Steven N

    2002-11-01

    Histamine H3 receptors and alpha2-adrenoceptors are presynaptic receptors that modulate norepinephrine (NE) release from sympathetic nerves innervating the cardiovascular system. We previously showed that cardiac H3 receptors are activated in sepsis, and that this activation leads to a decrease in the adrenergic response (AR) [J. Appl. Physiol. 85 (1998) 1693-1701] H3-receptors and alpha2-receptors appear to be coupled to GTP binding regulatory proteins (G) that modulate transmitter release by reducing calcium current into the nerve terminals through neuronal calcium channels. There may also be interaction between H3-receptors and alpha2-receptors on AR that may occur either at the receptor or a more downstream level. In the present study, we examined the effect of septic plasma on AR in a canine ventricular preparation in which field stimulation was used to produce AR. We determined whether there was interaction between H(3)-receptors and alpha2-adrenoceptors and tested whether H3 activation would attenuate the alpha2-agonist and alpha2-antagonist effects of clonidine and yohimbine, respectively. We also determined whether the mechanism by which septic plasma decreases the adrenergic response involves inactivation of an inhibitory G protein and used pertussis toxin (PTX) to assess this effect. We found that septic plasma attenuated AR produced by field stimulation, and that this decrease was mediated by a PTX sensitive inhibitory G protein. H3 activation also attenuated the alpha2-agonist and alpha2-antagonist effects on adrenergic activation as compared with nonseptic plasma. We conclude that presynaptic sympathetic dysfunction may contribute to cardiovascular collapse in sepsis.

  20. Advanced computer-controlled automatic alpha-beta air sample counter

    International Nuclear Information System (INIS)

    Howell, W.P.; Bruinekool, D.J.; Stapleton, E.E.

    1983-01-01

    An improved computer controlled automatic alpha-beta air sample counter was developed, based upon an earlier automatic air sample counter design. The system consists of an automatic sample changer, an electronic counting system utilizing a large silicon diode detector, a small desk-type microcomputer, a high speed matrix printer, and the necessary data interfaces. The system is operated by commands from the keyboard and programs stored on magnetic tape cassettes. The programs provide for background counting, Chi 2 test, radon subtraction, and sample counting for sample periods of one day to one week. Output data are printed by the matrix printer on standard multifold paper. The data output includes gross beta, gross alpha, and plutonium results. Data are automatically corrected for background, counter efficiency, and in the gross alpha and plutonium channels, for the presence of radon

  1. An advanced computer-controlled automatic alpha-beta air sample counter

    International Nuclear Information System (INIS)

    Howell, W.P.; Bruinekool, D.J.; Stapleton, E.E.

    1984-01-01

    An improved computer-controlled automatic alpha-beta air sample counter was developed, based upon an earlier automatic air sample counter design. The system consists of an automatic sample changer, an electronic counting system utilizing a large silicon diode detector, a small desk-type microcomputer, a high-speed matrix printer and the necessary data interfaces. The system is operated by commands from the keyboard and programs stored on magnetic tape cassettes. The programs provide for background counting, Chi 2 test, radon subtraction and sample counting for sample periods of one day to one week. Output data are printed by the matrix printer on standard multifold paper. The data output includes gross beta, gross alpha and plutonium results. Data are automatically corrected for background, counter efficiency, and in the gross alpha and plutonium channels, for the presence of radon

  2. Radar channel balancing with commutation

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-02-01

    When multiple channels are employed in a pulse-Doppler radar, achieving and maintaining balance between the channels is problematic. In some circumstances the channels may be commutated to achieve adequate balance. Commutation is the switching, trading, toggling, or multiplexing of the channels between signal paths. Commutation allows modulating the imbalance energy away from the balanced energy in Doppler, where it can be mitigated with filtering.

  3. Nuclear reactor coolant channels

    International Nuclear Information System (INIS)

    Macbeth, R.V.

    1978-01-01

    A nuclear reactor coolant channel is described that is suitable for sub-cooled reactors as in pressurised water reactors as well as for bulk boiling, as in boiling water reactors and steam generating nuclear reactors. The arrangement aims to improve heat transfer between the fuel elements and the coolant. Full constructional details are given. See also other similar patents by the author. (U.K.)

  4. Channel box compression device

    International Nuclear Information System (INIS)

    Nakamizo, Hiroshi; Tanaka, Yuki.

    1996-01-01

    The device of the present invention reduces the volume of spent fuel channel boxes of power plant facilities to eliminate secondary wastes, suppress generation of radiation sources and improve storage space efficiency. The device has a box-like shape. A support frame is disposed on the lateral side of the box for supporting spent channel boxes. A horizontal transferring unit and a vertical transferring compression unit driven by a driving mechanism are disposed in the support frame. Further, the compression unit may have a rotational compression roller so as to move freely in the transferring unit. In addition, the transferring unit and the driving mechanism may be disposed outside of pool water. With such a constitution, since spent channel boxes are compressed and bent by horizontal movement of the transferring unit and the vertical movement of the compression unit, no cut pieces or cut powders are generated. Further, if the transferring unit and the driving mechanism are disposed outside of the pool water, it is not necessary to make them waterproof, which facilitates the maintenance. (I.S.)

  5. Ion channeling revisited

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, Barney Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Corona, Aldo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nguyen, Anh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    A MS Excel program has been written that calculates accidental, or unintentional, ion channeling in cubic bcc, fcc and diamond lattice crystals or polycrystalline materials. This becomes an important issue when simulating the creation by energetic neutrons of point displacement damage and extended defects using beams of ions. All of the tables and graphs in the three Ion Beam Analysis Handbooks that previously had to be manually looked up and read from were programed into Excel in handy lookup tables, or parameterized, for the case of the graphs, using rather simple exponential functions with different powers of the argument. The program then offers an extremely convenient way to calculate axial and planar half-angles and minimum yield or dechanneling probabilities, effects on half-angles of amorphous overlayers, accidental channeling probabilities for randomly oriented crystals or crystallites, and finally a way to automatically generate stereographic projections of axial and planar channeling half-angles. The program can generate these projections and calculate these probabilities for axes and [hkl] planes up to (555).

  6. Inhibition of large conductance calcium-dependent potassium ...

    African Journals Online (AJOL)

    conductance, calcium and voltage- dependent potassium (BKCa) channels thereby promoting vasoconstriction. Our results show that the Rho-kinase inhibitor, Y-27632, induced concentration-dependent relaxation in rat mesenteric artery.

  7. TRP channels in kidney disease.

    NARCIS (Netherlands)

    Hsu, Y.J.; Hoenderop, J.G.J.; Bindels, R.J.M.

    2007-01-01

    Mammalian TRP channel proteins form six-transmembrane cation-permeable channels that may be grouped into six subfamilies on the basis of amino acid sequence homology (TRPC, TRPV, TRPM, TRPA, TRPP, and TRPML). Recent studies of TRP channels indicate that they are involved in numerous fundamental cell

  8. Inhibition of K+ permeability diminishes alpha 2-adrenoceptor mediated effects on norepinephrine release

    International Nuclear Information System (INIS)

    Zimanyi, I.; Folly, G.; Vizi, E.S.

    1988-01-01

    The effect of two different potassium channel blockers, 4-aminopyridine (4-AP) and quinine, on the alpha 2-adrenoceptor mediated modulation of norepinephrine (NE) release was investigated. Pairs of mouse vasa deferentia were loaded with 3 H-norepinephrine ( 3 H-NE), superfused continuously, and stimulated electrically. 4-AP (5.3 x 10(-4) M), and quinine (10(-5) M) enhanced the stimulation-evoked release of tritium significantly. The electrically induced release of radioactivity was reduced by alpha 2-adrenoceptor agonists (1-NE and xylazine) and enhanced by the alpha 2-adrenoceptor antagonist yohimbine. Both effects were affected markedly by 4-AP or quinine: the depressant action of 1-NA and xylazine was partially antagonized and the facilitatory effect of yohimbine was completely abolished during the blockade of the potassium channels. It is suggested that the blockade of the potassium permeability counteracts negative feedback modulation; therefore, it seems likely that the stimulation of alpha 2-adrenoceptors leads to an enhanced potassium permeability and hyperpolarization of varicose axon terminals

  9. ATP Release from Human Airway Epithelial Cells Exposed to Staphylococcus aureus Alpha-Toxin

    Directory of Open Access Journals (Sweden)

    Romina Baaske

    2016-12-01

    Full Text Available Airway epithelial cells reduce cytosolic ATP content in response to treatment with S. aureus alpha-toxin (hemolysin A, Hla. This study was undertaken to investigate whether this is due to attenuated ATP generation or to release of ATP from the cytosol and extracellular ATP degradation by ecto-enzymes. Exposure of cells to rHla did result in mitochondrial calcium uptake and a moderate decline in mitochondrial membrane potential, indicating that ATP regeneration may have been attenuated. In addition, ATP may have left the cells through transmembrane pores formed by the toxin or through endogenous release channels (e.g., pannexins activated by cellular stress imposed on the cells by toxin exposure. Exposure of cells to an alpha-toxin mutant (H35L, which attaches to the host cell membrane but does not form transmembrane pores, did not induce ATP release from the cells. The Hla-mediated ATP-release was completely blocked by IB201, a cyclodextrin-inhibitor of the alpha-toxin pore, but was not at all affected by inhibitors of pannexin channels. These results indicate that, while exposure of cells to rHla may somewhat reduce ATP production and cellular ATP content, a portion of the remaining ATP is released to the extracellular space and degraded by ecto-enzymes. The release of ATP from the cells may occur directly through the transmembrane pores formed by alpha-toxin.

  10. Quantum Estimates of Alpha Emitter Life Time

    Directory of Open Access Journals (Sweden)

    B. Santoso

    2006-01-01

    Full Text Available Quantum estimates of several alpha radioactive life time have been made using the probability of quantum tunneling through the nuclear potential barrier. It is assumed that for a given nucleus with mass number A and isotopic number Z, there exists an alpha particle moving freely back and forth in the nucleus with mass and isotopic numbers A -4 and Z-2. If the probability of penetrating the nuclear potential barrier is Τ, then after N times (N=1/Τ hitting the barrier an alpha particle is emitted. To obtain the elapsed time for emitting an alpha particle requires N times τ0, where τ0 is the time travel for alpha across the nuclear diameter, which is dependent on alpha energy. It is assumed here that this kinetic energy is the same as the emitted energy. The emitting alpha kinetic energies here are calculated by the difference of the masses of the parent and daughter nuclei and the alpha particles. They are in closed agreement with the experimental observations. While the alpha radioactive life time are not the same order of magnitudes but give the same linearity on the logarithmic scale as function of the inverse square root of energy.

  11. Sterically hindered C(alpha, alpha)-disubstituted alpha-amino acids: synthesis from alpha-nitroacetate and incorporation into peptides.

    Science.gov (United States)

    Fu, Y; Hammarström, L G; Miller, T J; Fronczek, F R; McLaughlin, M L; Hammer, R P

    2001-10-19

    The preparation of sterically hindered and polyfunctional C(alpha,alpha)-disubstituted alpha-amino acids (alpha alpha AAs) via alkylation of ethyl nitroacetate and transformation into derivatives ready for incorporation into peptides are described. Treatment of ethyl nitroacetate with N,N-diisopropylethylamine (DIEA) in the presence of a catalytic amount of tetraalkylammonium salt, followed by the addition of an activated alkyl halide or Michael acceptor, gives the doubly C-alkylated product in good to excellent yields. Selective nitro reduction with Zn in acetic acid or hydrogen over Raney Ni gives the corresponding amino ester that, upon saponification, can be protected with the fluorenylmethyloxycarbonyl (Fmoc) group. The first synthesis of an orthogonally protected, tetrafunctional C(alpha,alpha)-disubstituted analogue of aspartic acid, 2,2-bis(tert-butylcarboxymethyl)glycine (Bcmg), is described. Also, the sterically demanding C(alpha,alpha)-dibenzylglycine (Dbg) has been incorporated into a peptide using solid-phase synthesis. It was found that once sterically congested Dbg is at the peptide N-terminus, further chain extension becomes very difficult using uronium or phosphonium salts (PyAOP, PyAOP/HOAt, HATU). However, preformed amino acid symmetrical anhydride couples to N-terminal Dbg in almost quantitative yield in nonpolar solvent (dichloroethane-DMF, 9:1).

  12. Planar channeling observed by radiography

    International Nuclear Information System (INIS)

    Delsarte, Guy

    1970-06-01

    Radiographies of crystals by means of channeled particles exhibit channeling patterns. The origin of these patterns is studied, The role played by planar channeling is demonstrated. It is shown that these patterns are local amplifications of the process generating the images of a crystal on the radiography. It is deduced that planar channeling plays a determining role in the formation of these images. An orientation chamber using transmitted planar channels is described. The orientation of very small grains in a polycrystal can be very easily obtained, (author) [fr

  13. Intermittent 20-HZ-photic stimulation leads to a uniform reduction of alpha-global field power in healthy volunteers.

    Science.gov (United States)

    Rau, R; Raschka, C; Koch, H J

    2001-01-01

    19-channel-EEGs were recorded from scalp surface of 30 healthy subjects (16m, 14f, mean age: 34 ys, SD: 11.7 ys) at rest and under IPS (Intermittent Photic Stimulation) at rates of 5, 10 and 20 Hertz (Hz). Digitalized data underwent spectral analysis with fast fourier transfomation (FFT) yielding the basis for the computation of global field power (GFP). For quantification GFP values in the frequency ranges of 5, 10 and 20 Hz at rest were divided by the corresponding data gained under IPS. While ratios from PDE data showed no stable parameter due to high interindividual variability, ratios of alpha-power turned out to be uniform in all subjects: IPS at 20 Hz always led to a suppression of alpha-power. Dividing alpha-GFP at rest by alpha-GFP under 20-Hz IPS thus resulted in a ratio paradigma.

  14. Pulsar H(alpha) Bowshocks probe Neutron Star Physics

    Science.gov (United States)

    Romani, Roger W.

    2014-08-01

    We propose a KOALA/AAOmega study of southern pulsar bow shocks. These rare, Balmer-dominated, non-radiative shocks provide an ideal laboratory to study the interaction of the relativistic pulsar wind with the ISM. We will cover H(alpha) at high spectral resolution to measure the kinematics of the upstream ISM and the post-shock flow, while the blue channel measures the Balmer decrement and probes for a faint cooling component. These data, with MHD models, allow us to extract the 3D flow geometry and the orientation and asymmetry of the pulsar wind. These data can also measure the pulsar spindown power, thus estimating the neutron star moment of inertia and effecting a fundamental test of dense matter physics.

  15. Hypothalamic PGC-1 alpha Protects Against High-Fat Diet Exposure by Regulating ER alpha

    NARCIS (Netherlands)

    Morselli, Eugenia; Fuente-Martin, Esther; Finan, Brian; Kim, Min; Frank, Aaron; Garcia-Caceres, Cristina; Navas, Carlos Rodriguez; Gordillo, Ruth; Neinast, Michael; Kalainayakan, Sarada P.; Li, Dan L.; Gao, Yuanqing; Yi, Chun-Xia; Hahner, Lisa; Palmer, Biff F.; Tschöp, Matthias H.; Clegg, Deborah J.

    2014-01-01

    High-fat diets (HFDs) lead to obesity and inflammation in the central nervous system (CNS). Estrogens and estrogen receptor alpha (ER alpha) protect premenopausal females from the metabolic complications of inflammation and obesity-related disease. Here, we demonstrate that hypothalamic PGC-1 alpha

  16. Tumor necrosis factor alpha (TNF alpha) in human skin : A comparison of different antibodies for immunohistochemistry

    NARCIS (Netherlands)

    van der Laan, N; de Leij, LFMH; Buurman, W; Timens, W; ten Duis, HJ

    Conflicting results have been reported regarding the localization and presence of TNF alpha in normal human skin, To study TNF alpha expression, we tested a panel of antibodies directed against human TNF alpha, First, antibodies were tested for immunoreactivity on cytospots of isolated

  17. Study of the pygmy dipole resonance in Mo-94 using the (alpha, alpha ' gamma) coincidence technique

    NARCIS (Netherlands)

    Derya, V.; Endres, J.; Elvers, M.; Harakeh, M. N.; Pietralla, N.; Romig, C.; Savran, D.; Scheck, M.; Siebenhuehner, F.; Stoica, V. I.; Wortche, H. J.; Zilges, A.

    2013-01-01

    The (alpha, alpha' gamma) reaction at E-alpha = 136 MeV was used to study the electric dipole response in the open-shell vibrational nucleus Mo-94 below the neutron-separation threshold. The coincidence experiment has been performed at the Kernfysisch Versneller Instituut in Groningen, The

  18. Radiosynthesis and in vitro validation of 3H-NS14492 as a novel high affinity alpha7 nicotinic receptor radioligand

    DEFF Research Database (Denmark)

    Magnussen, Janus H.; Ettrup, Anders; Donat, Cornelius K.

    2015-01-01

    The neuronal alpha 7 nicotinic acetylcholine receptor is a homo-pentameric ligand-gated ion channel that is a promising drug target for cognitive deficits in Alzheimer's disease and schizophrenia. We have previously described 11C-NS14492 as a suitable agonist radioligand for in vivo positron......, these findings show that 3H-NS14492 is a useful new in vitro radioligand for the pig alpha 7 nicotinic receptor. © 2015 Elsevier B.V. All rights reserved....

  19. Effects of 2,3-butanedione monoxime (BDM) on calcium channels expressed in Xenopus oocytes.

    Science.gov (United States)

    Allen, T J; Mikala, G; Wu, X; Dolphin, A C

    1998-04-01

    1. We examine the actions of a chemical phosphatase, 2,3-butanedione monoxime (BDM), on endogenous and expressed Ca2+ channel currents in Xenopus oocytes. In previous studies on L-type Ca2+ channel currents in cardiomyocytes and dorsal root ganglia, the inhibitory effects of BDM were attenuated by activation of protein kinase A. 2. Ba2+ currents (IBa) through a human wild-type L-type Ca2+ channel complex (i.e. halpha1C, alpha2-deltaa and hbeta1b) are inhibited by BDM with an IC50 of 16 mM, with 10 mM producing a 36.1 +/- 2.2 % inhibition. IBa through endogenous oocyte N-type Ca2+ channels, upregulated by exogenous alpha2-deltaa and hbeta1b subunits, are inhibited to a similar degree by BDM. 3. To examine whether the action of BDM is dependent on PKA-dependent phosphorylation, a clone of halpha1C deficient in all five serine PKA consensus sites (halpha1C-SA5) was co-expressed with alpha2-deltaa and the human cardiac hbeta3 subunit, which naturally lacks PKA consensus sites. This complex exhibited a sensitivity to BDM that was similar to the wild-type complex, with 10 mM BDM producing 31.6 +/- 1.5 % inhibition. 4. As limited proteolysis upregulates Ca2+ channels in cardiomyocytes and renders them less sensitive to BDM, experiments were performed with a carboxyl terminus deletion mutant, halpha1C-Delta1633. IBa through this subunit showed a sensitivity to BDM that was similar to the wild-type complex, with 10 mM BDM producing 31.3 +/- 1.4 % inhibition. However, co-expression with alpha2-deltaa and hbeta3 subunits reduced potency, and is reflected by an increased IC50 of 22.7 mM. 5. The actions of BDM were examined on a rat brain rbA-1 Ca2+ channel clone, alpha1A, co-expressed with alpha2-deltab and beta1b subunit homologues from rat brain. BDM inhibited the current through this channel complex to a similar degree to that seen for cardiac wild-type channels, with 10 mM BDM causing a 33.1 +/- 3.5 % inhibition. 6. The effects of BDM were compared at two holding

  20. Down-regulation of voltage-dependent sodium channels initiated by sodium influx in developing neurons

    Energy Technology Data Exchange (ETDEWEB)

    Dargent, B.; Couraud, F. (Centre National de la Recherche Scientifique, Marseille (France))

    1990-08-01

    To address the issue of whether regulatory feedback exists between the electrical activity of a neuron and ion-channel density, the authors investigated the effect of Na{sup +}-channel activators (scorpion {alpha} toxin, batrachotoxin, and veratridine) on the density of Na{sup +} channels in fetal rat brain neurons in vitro. A partial but rapid (t{sub 1/2}, 15 min) disappearance of surface Na{sup +} channels was observed as measured by a decrease in the specific binding of ({sup 3}H)saxitoxin and {sup 125}I-labeled scorpion {beta} toxin and a decrease in specific {sup 22}Na{sup +} uptake. Moreover, the increase in the number of Na{sup +} channels that normally occurs during neuronal maturation in vitro was inhibited by chronic channel activator treatment. The induced disappearance of Na{sup +} channels was abolished by tetrodotoxin, was found to be dependent on the external Na{sup +} concentration, and was prevented when either choline (a nonpermeant ion) or Li{sup +} (a permeant ion) was substituted for Na{sup +}. Amphotericin B, a Na{sup +} ionophore, and monensin were able to mimick the effect of Na{sup +}-channel activators, while a KCl depolarization failed to do this. This feedback regulation seems to be a neuronal property since Na{sup +}-channel density in cultured astrocytes was not affected by channel activator treatment or by amphotericin B. The present evidence suggests that an increase in intracellular Na{sup +} concentration, whether elicited by Na{sup +}-channel activators or mediated by a Na{sup +} ionophore, can induce a decrease in surface Na{sup +} channels and therefore is involved in down-regulation of Na{sup +}-channel density in fetal rat brain neurons in vitro.

  1. Psychiatric Symptoms in Alpha-Mannosidosis

    Science.gov (United States)

    Malm, D.; Pantel, J.; Linaker, O. M.

    2005-01-01

    Alpha-mannosidosis is characterized by mild to moderate intellectual disability (ID), moderate to severe neurosensory hearing loss, frequent infections, psychomotor disturbances and skeletal dysmorphism. For the first time, a panel of nine alpha-mannosidosis patients with psychiatric symptoms is presented. The clinical picture has several…

  2. Coefficient Alpha Bootstrap Confidence Interval under Nonnormality

    Science.gov (United States)

    Padilla, Miguel A.; Divers, Jasmin; Newton, Matthew

    2012-01-01

    Three different bootstrap methods for estimating confidence intervals (CIs) for coefficient alpha were investigated. In addition, the bootstrap methods were compared with the most promising coefficient alpha CI estimation methods reported in the literature. The CI methods were assessed through a Monte Carlo simulation utilizing conditions…

  3. Alpha Shape Topology of the Cosmic Web

    NARCIS (Netherlands)

    Weygaert, Rien van de; Platen, Erwin; Vegter, Gert; Eldering, Bob; Kruithof, Nico

    2010-01-01

    We study the topology of the Megaparsec Cosmic Web on the basis of the Alpha Shapes of the galaxy distribution. The simplicial complexes of the alpha shapes are used to determine the set of Betti numbers (βk, k = 1, . . . , D), which represent a complete characterization of the topology of a

  4. Central and peripheral alpha-adrenoceptors

    NARCIS (Netherlands)

    van Zwieten, P A; van Meel, J. C. A.; de Jonge, A; Wilffert, B; Timmermans, P B

    1982-01-01

    The recent interest in the characterization and functional, role of alpha-adrenoceptors has prompted us to study the following different, although interdigitated, lines of research: (a) The functional role of calcium ions in the process of vasoconstriction, induced by alpha 2-adrenoceptor

  5. Producing alpha-olefins using polyketide synthases

    Energy Technology Data Exchange (ETDEWEB)

    Fortman, Jeffrey L.; Katz, Leonard; Steen, Eric J.; Keasling, Jay D.

    2018-01-02

    The present invention provides for a polyketide synthase (PKS) capable of synthesizing an .alpha.-olefin, such as 1-hexene or butadiene. The present invention also provides for a host cell comprising the PKS and when cultured produces the .alpha.-olefin.

  6. Bayesian Meta-Analysis of Coefficient Alpha

    Science.gov (United States)

    Brannick, Michael T.; Zhang, Nanhua

    2013-01-01

    The current paper describes and illustrates a Bayesian approach to the meta-analysis of coefficient alpha. Alpha is the most commonly used estimate of the reliability or consistency (freedom from measurement error) for educational and psychological measures. The conventional approach to meta-analysis uses inverse variance weights to combine…

  7. ALPHA experiment facility and Prof. Jeffrey Hangst.

    CERN Multimedia

    Maximilien Brice

    2010-01-01

    Picture 01-07: General views of the ALPHA experiment Picture 5: Andrea Gutierrez, a PhD student from UBC, transfers liquid helium from a storage dewar into the cryostat containing the superconducting magnetic trap used by the ALPHA experiment.Picture 08-11: Jeffery Hangst, spokesperson for ALPHA Picture 12: The ALPHA silicon detector, which surrounds the trapping resion and is used for imaging antiproton annihilations (Credit University of Liverpool) Picture 13: Untrapped antihydrogen atoms annihilating on the inner surface of the ALPHA trap. These are measured by the ALPHA annihilation detector. The events are concentrated at the electrode radius of about 22.3 mm. The coordinates are defined in the Nature article, Figure 1b. Picture 14: The electrodes (gold) for the ALPHA Penning trap being inserted into the vacuum chamber and cryostat assembly. This is the trap used to combine or "mix" positrons and antiprotons to make antihydrogen. (Credit: Niels Madsen ALPHA/Swansea.) Picture 15: Top, a diagram of the...

  8. Alpha-1 Antitrypsin Deficiency (Inherited Emphysema)

    Science.gov (United States)

    ... antitrypsin inactivates elastase once it has finished its job. Without alpha 1 antitrypsin, elastase can destroy the air sacs of the lung. How is the diagnosis made? Because Alpha-1 related disease is COPD, the diagnosis is made by the same methods. Your doctor may have you do a number ...

  9. Instability of the ion hybrid wave in the presence of superthermal alpha-particles

    Science.gov (United States)

    Lashmore-Davies, C. N.; Russell, D. A.

    1997-02-01

    The stability of the ion hybrid wave in a plasma containing two thermal ion species present in comparable proportions and a low density population of superthermal alpha-particles is analyzed. A simple, model distribution function consisting of a ring distribution in the perpendicular velocity and a Maxwellian in the parallel velocity is used for the superthermal alpha-particles. This distribution function is relevant to the core plasma of a tokamak in the immediate post-birth phase before the alpha-particles have had time to relax collisionally and is therefore of interest to the alpha-channelling question. It has also been used to interpret ion cyclotron emission from fusion products in the edge plasma of large tokamaks. An approximate dispersion relation is derived which allows the conditions for instability to be explored and an analytic expression for the growth rate to be obtained. It is found that the ion hybrid wave can be unstable for v⊥0/cA≪1 where v⊥0 is the alpha-particle ring speed and cA is Alfvén speed for a plasma with two ion species. The instability conditions obtained from the analytic approximation are used to guide the solution of the exact dispersion relation. Numerical solutions for the specific cases of deuterium-tritium core and edge plasmas in the Tokamak Fusion Test Reactor (TFTR) [K. M. Young et al., Plasma Phys. Controlled Fusion 26, 11 (1984)] are given.

  10. A stable lipid-induced aggregate of alpha-synuclein

    NARCIS (Netherlands)

    Drescher, Malte; van Rooijen, Bart D; Veldhuis, Gertjan; Subramaniam, Vinod; Huber, Martina

    2010-01-01

    The Parkinson's disease-related protein alpha-Synuclein (alphaS) is a 140 residue intrinsically disordered protein. Its membrane-binding properties are thought to be relevant for its physiological or pathologic activity. Here, the interaction of alphaS with POPG

  11. New binding site on common molecular scaffold provides HERG channel specificity of scorpion toxin BeKm-1

    DEFF Research Database (Denmark)

    Korolkova, Yuliya V; Bocharov, Eduard V; Angelo, Kamilla

    2002-01-01

    The scorpion toxin BeKm-1 is unique among a variety of known short scorpion toxins affecting potassium channels in its selective action on ether-a-go-go-related gene (ERG)-type channels. BeKm-1 shares the common molecular scaffold with other short scorpion toxins. The toxin spatial structure...... resolved by NMR consists of a short alpha-helix and a triple-stranded antiparallel beta-sheet. By toxin mutagenesis study we identified the residues that are important for the binding of BeKm-1 to the human ERG K+ (HERG) channel. The most critical residues (Tyr-11, Lys-18, Arg-20, Lys-23) are located...... in the alpha-helix and following loop whereas the "traditional" functional site of other short scorpion toxins is formed by residues from the beta-sheet. Thus the unique location of the binding site of BeKm-1 provides its specificity toward the HERG channel....

  12. Channels in tokamak reactor shields

    International Nuclear Information System (INIS)

    Shchipakin, O.L.

    1981-01-01

    The results of calculations of neutron transport through the channels in the tokamak reactor radiation shields, obtained by the Monte Carlo method and by the method of discrete ordinates, are considered. The given data show that the structural materials of the channel and that of the blanket and shields in the regions close to it are subjected to almost the same irradiation as the first wall and therefore they should satisfy the technical requirements. The radiation energy release in the injector channel wall, caused by neutron shooting, substantially depends on the channel dimensions. At the channel large diameter (0.7-10 m) this dependence noticeably decreases. The investigation of the effect of the injector channel cross section form on the neutron flux density through the channel, testifies to weak dependence of shooting radiation intensity on the form of the channel cross section. It is concluded that measures to decrease unfavourable effect of the channels on the safety of the power tokamak reactor operation and maintenance cause substantial changes in reactor design due to which the channel protection must be developed at first stages. The Monte Carlo method is recommended to be used for variant calculations and when calculating the neutron flux functionals in specific points of the system the discrete ordinate method is preferred [ru

  13. Channel Wall Landslides

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] The multiple landslides in this VIS image occur along a steep channel wall. Note the large impact crater in the context image. The formation of the crater may have initially weakened that area of the surface prior to channel formation. Image information: VIS instrument. Latitude -2.7, Longitude 324.8 East (35.2 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. Improved peak shape fitting in alpha spectra.

    Science.gov (United States)

    Pommé, S; Caro Marroyo, B

    2015-02-01

    Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Technical Basis for the Use of Alpha Absorption Corrections on RCF Gross Alpha Data

    International Nuclear Information System (INIS)

    Ceffalo, G.M.

    1999-01-01

    This document provides the supporting data and rationale for making absorption corrections to gross alpha data to correct alpha data for loss due to absorption in the sample matrix. For some time there has been concern that the gross alpha data produced by the Environmental Restoration Contractor Radiological Counting Facility, particularly gross alpha analysis on soils, has been biased toward low results, as no correction for self-absorption was applied to the counting data. The process was investigated, and a new methodology for alpha self-absorption has been developed

  16. Elimination of alpha-gal xenoreactive epitope: alpha-galactosidase treatment of porcine heart valves.

    Science.gov (United States)

    Choi, Sun-Young; Jeong, Hee-Jin; Lim, Hong-Gook; Park, Seong-Sik; Kim, Soo-Hwan; Kim, Yong Jin

    2012-05-01

    Porcine heart valves are among the most widely used tissue valves in clinical heart valve implantation. However, immunologic responses have been implicated as potential causes of the limited durability of xenograft heart valves. The study aim was to determine the effectiveness of alpha-galactosidase treatment used to degrade the major xenoreactive antigens found in xenograft heart valves. Fresh porcine heart valves and pericardium treated with alpha-galactosidase were studied to evaluate the xenoreactive galactose (alpha1,3) galactose (alpha-gal) antigen. Removal of the alpha-gal epitope from the porcine heart valve was monitored via 3,3'-diaminobenzidine staining intensity, while the removal of alpha-gal from N-glycans on porcine heart valves treated with recombinant alpha-galactosidase was determined either qualitatively or quantitatively by mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The porcine pericardium was used for monitoring the change in mechanical properties after alpha-galactosidase treatment. In addition, the biomechanical modification property of collagen fiber rearrangement on tissue was assessed using transmission electron microscopy (TEM). Following a 24-h incubation at pH 7.2, 4 degrees C, employing 0.1 U/ml of Bacteroides thetaiotaomicron-derived recombinant alpha-galactosidase, the enzyme effectively removed the alpha-gal epitopes expressed on porcine heart valves. The identification type of alpha-gal N-glycan on fresh aortic valve, aortic wall, pulmonary valve, and pulmonary wall was 7.1%, 10.3%, 6% and 8%, respectively. In the presence of alpha-galactosidase treatment, alpha-gal-containing N-glycans were converted into alpha-gal-negative N-glycans. Likewise, alpha-gal-containing N-glycans were not detected when MALDI-TOF MS quantitative analysis was used. Furthermore, no significant difference was observed in the mechanical properties and findings from TEM in alpha

  17. A Micromechanical RF Channelizer

    Science.gov (United States)

    Akgul, Mehmet

    The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency. This dissertation focuses on the degree to which capacitive-gap transduced micromechanical resonators can achieve the aforementioned RF channel-selecting filters. It aims to first show theoretically that with appropriate scaling capacitive-gap transducers are strong enough to meet the needed coupling requirements; and second, to fully detail an architecture and design procedure needed to realize said filters. Finally, this dissertation provides an actual experimentally demonstrated RF channel-select filter designed using the developed procedures and confirming theoretical predictions. Specifically, this dissertation introduces four methods that make possible the design and fabrication of RF channel-select filters. The first of these introduces a small-signal equivalent circuit for parallel-plate capacitive-gap transduced micromechanical resonators that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates the analysis of micromechanical circuits loaded with arbitrary electrical impedances. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive-gap transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for

  18. Determination of alpha_s using jet cross section parameterizations at hadron colliders

    CERN Document Server

    Stenzel, H

    2001-01-01

    Precise measurements of the single inclusive jet cross section have been performed by the TEVATRON experiments and will be provided by the LHC experiments extending to larger values of transverse energy. Theoretical predictions of this observable at NLO in perturbative QCD depend both on the PDF parameterization set and on the value of the strong coupling constant alpha_s. In this paper the dependence of the jet cross section on alpha_s is investigated. A method is presented to extract alpha_s(E_T) from a cross section measurement based on a parameterization of the alpha_s dependence. Systematic uncertainties and the E_T-range of applicability are discussed. A comparative study is performed between the case of ppbar at sqrt{s}=1.8 TeV (TEVATRON) and pp scattering at sqrt{s}=14 TeV (LHC).

  19. Alpha1 and Alpha2 Integrins Mediate Invasive Activity of Mouse Mammary Carcinoma Cells through Regulation of Stromelysin-1 Expression

    Energy Technology Data Exchange (ETDEWEB)

    Lochter, Andre; Navre, Marc; Werb, Zena; Bissell, Mina J

    1998-06-29

    Tumor cell invasion relies on cell migration and extracellular matrix proteolysis. We investigated the contribution of different integrins to the invasive activity of mouse mammary carcinoma cells. Antibodies against integrin subunits {alpha}6 and {beta}1, but not against {alpha}1 and {alpha}2, inhibited cell locomotion on a reconstituted basement membrane in two-dimensional cell migration assays, whereas antibodies against {beta}1, but not against a6 or {alpha}2, interfered with cell adhesion to basement membrane constituents. Blocking antibodies against {alpha}1 integrins impaired only cell adhesion to type IV collagen. Antibodies against {alpha}1, {alpha}2, {alpha}6, and {beta}1, but not {alpha}5, integrin subunits reduced invasion of a reconstituted basement membrane. Integrins {alpha}1 and {alpha}2, which contributed only marginally to motility and adhesion, regulated proteinase production. Antibodies against {alpha}1 and {alpha}2, but not {alpha}6 and {beta}1, integrin subunits inhibited both transcription and protein expression of the matrix metalloproteinase stromelysin-1. Inhibition of tumor cell invasion by antibodies against {alpha}1 and {alpha}2 was reversed by addition of recombinant stromelysin-1. In contrast, stromelysin-1 could not rescue invasion inhibited by anti-{alpha}6 antibodies. Our data indicate that {alpha}1 and {alpha}2 integrins confer invasive behavior by regulating stromelysin-1 expression, whereas {alpha}6 integrins regulate cell motility. These results provide new insights into the specific functions of integrins during tumor cell invasion.

  20. A transient receptor potential channel expressed in taste receptor cells.

    Science.gov (United States)

    Pérez, Cristian A; Huang, Liquan; Rong, Minqing; Kozak, J Ashot; Preuss, Axel K; Zhang, Hailin; Max, Marianna; Margolskee, Robert F

    2002-11-01

    We used differential screening of cDNAs from individual taste receptor cells to identify candidate taste transduction elements in mice. Among the differentially expressed clones, one encoded Trpm5, a member of the mammalian family of transient receptor potential (TRP) channels. We found Trpm5 to be expressed in a restricted manner, with particularly high levels in taste tissue. In taste cells, Trpm5 was coexpressed with taste-signaling molecules such as alpha-gustducin, Ggamma13, phospholipase C-beta2 (PLC-beta2) and inositol 1,4,5-trisphosphate receptor type III (IP3R3). Our heterologous expression studies of Trpm5 indicate that it functions as a cationic channel that is gated when internal calcium stores are depleted. Trpm5 may be responsible for capacitative calcium entry in taste receptor cells that respond to bitter and/or sweet compounds.

  1. The Channel Tunnel

    Science.gov (United States)

    2006-01-01

    The Channel Tunnel is a 50.5 km-long rail tunnel beneath the English Channel at the Straits of Dover. It connects Dover, Kent in England with Calais, northern France. The undersea section of the tunnel is unsurpassed in length in the world. A proposal for a Channel tunnel was first put forward by a French engineer in 1802. In 1881, a first attempt was made at boring a tunnel from the English side; the work was halted after 800 m. Again in 1922, English workers started boring a tunnel, and advanced 120 m before it too was halted for political reasons. The most recent attempt was begun in 1987, and the tunnel was officially opened in 1994. At completion it was estimated that the project cost around $18 billion. It has been operating at a significant loss since its opening, despite trips by over 7 million passengers per year on the Eurostar train, and over 3 million vehicles per year. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance. The

  2. Mapping High-Velocity H-alpha and Lyman-alpha Emission from Supernova 1987A

    Science.gov (United States)

    France, Kevin; McCray, Richard; Fransson, Claes; Larsson, Josefin; Frank, Kari A.; Burrows, David N.; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger A.; Garnavich, Peter; hide

    2015-01-01

    We present new Hubble Space Telescope images of high-velocity H-alpha and Lyman-alpha emission in the outer debris of SN 1987A. The H-alpha images are dominated by emission from hydrogen atoms crossing the reverse shock. For the first time we observe emission from the reverse shock surface well above and below the equatorial ring, suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H-alpha imaging, we measure the mass flux of hydrogen atoms crossing the reverse shock front, in the velocity intervals (-7,500 < V(sub obs) < -2,800 km/s) and (1,000 < V(sub obs) < 7,500 km/s), ?M(sub H) = 1.2 × 10(exp -3) M/ y. We also present the first Lyman-alpha imaging of the whole remnant and new Chandra X-ray observations. Comparing the spatial distribution of the Lyman-alpha and X-ray emission, we observe that the majority of the high-velocity Lyman-alpha emission originates interior to the equatorial ring. The observed Lyman-alpha/H-alpha photon ratio, R(L-alpha/H-alpha) approx. = 17, is significantly higher than the theoretically predicted ratio of approx. = 5 for neutral atoms crossing the reverse shock front. We attribute this excess to Lyman-alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Lyman-alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Lyman-alpha production mechanism in SN 1987A at this phase in its evolution.

  3. UPSO three channel fast photometer

    Science.gov (United States)

    Gupta, S. K.; Sagar, R.; Joshi, S.; Ashoka, B. N.; Babu, V. C.; Seetha, S.; Girish, V.

    2001-09-01

    The design and performance of a modular portable three channel fast photometer is described. It can be disassembled as single individual channels such that the system can also be used as a single channel photometer. The instrument is put into operation since November 1999 on the 1-m UPSO telescope at Nainital. Since then, it is used extensively for the survey of roAp stars in the northern sky at UPSO. The discoveries made using this new photometer are also mentioned.

  4. Upgrading a marketing channels role

    Directory of Open Access Journals (Sweden)

    Tišma-Borota Ankica

    2002-01-01

    Full Text Available As one of the marketing mix instruments, marketing channels were usually behind other instruments (product, price and promotion. Many companies regarded marketing channels as something that was 'left' after more important strategies of price, product and promotion were created. In recent past, things have changed and marketing channels became more interesting for research. This change came as a result of change in global market functioning especially in competitive advantage, distributors' strength and increasing technology.

  5. Pull Promotions and Channel Coordination

    OpenAIRE

    Eitan Gerstner; James D. Hess

    1995-01-01

    This paper recommends that manufacturers consider a pull price promotion as a coordination device in an independent channel of distribution. Uncoordinated decisions of both manufacturer and retailer to charge high prices can break down the effort to expand the market, resulting in losses to the channel as a whole. We show that manufacturers can enhance channel price coordination by designing pull price discounts that target price-conscious consumers. The increased price coordination improves ...

  6. Single-channel kinetics of BK (Slo1 channels

    Directory of Open Access Journals (Sweden)

    Yanyan eGeng

    2015-01-01

    Full Text Available Single-channel kinetics has proven a powerful tool to reveal information about the gating mechanisms that control the opening and closing of ion channels. This introductory review focuses on the gating of large conductance Ca2+- and voltage-activated K+ (BK or Slo1 channels at the single-channel level. It starts with single-channel current records and progresses to presentation and analysis of single-channel data and the development of gating mechanisms in terms of discrete state Markov (DSM models. The DSM models are formulated in terms of the tetrameric modular structure of BK channels, consisting of a central transmembrane pore-gate domain (PGD attached to four surrounding transmembrane voltage sensing domains (VSD and a large intracellular cytosolic domain (CTD, also referred to as the gating ring. The modular structure and data analysis shows that the Ca2+ and voltage dependent gating considered separately can each be approximated by 10-state two-tiered models with 5 closed states on the upper tier and 5 open states on the lower tier. The modular structure and joint Ca2+ and voltage dependent gating are consistent with a 50 state two-tiered model with 25 closed states on the upper tier and 25 open states on the lower tier. Adding an additional tier of brief closed (flicker states to the 10-state or 50-state models improved the description of the gating. For fixed experimental conditions a channel would gate in only a subset of the potential number of states. The detected number of states and the correlations between adjacent interval durations are consistent with the tiered models. The examined models can account for the single-channel kinetics and the bursting behavior of gating. Ca2+ and voltage activate BK channels by predominantly increasing the effective opening rate of the channel with a smaller decrease in the effective closing rate. Ca2+ and depolarization thus activate by mainly destabilizing the closed states.

  7. LLU-alpha, an endogenous metabolite of gamma-tocopherol, is more effective against metal nephrotoxicity in rats than gamma-tocopherol.

    Science.gov (United States)

    Appenroth, D; Karge, E; Kiessling, G; Wechter, W J; Winnefeld, K; Fleck, C

    2001-07-06

    Antioxidants of the vitamin E family have protective effects against metal toxicity. We examined the protective effect of racemic LLU-alpha [2,7,8-trimethyl-2-(carboxyethyl)-6-hydroxychroman] a metabolite of gamma-tocopherol, in comparison to the effect of alpha- and gamma-tocopherol in rats treated with sodium dichromate (Cr) or thallium sulfate (Tl). We measured metal nephrotoxicity based on urinary protein excretion and discussed it with respect to the metal concentration in renal tissue. The ranking of antioxidant activity (iron stimulated lipid peroxidation, luminol and lucigenin amplified chemiluminescence) was determined in the following order: alpha-tocopherolthallium-induced proteinuria, a lower concentration of Tl in the renal medulla, and higher urinary Tl excretion. Unlike LLU-alpha, which has been shown to inhibit K(+) channels in the apical membrane of the thick ascending limb of Henle's loop, we found that gamma-tocopherol did not. This finding reaffirmed the similarity between K(+) and Tl(+) and also explained the significantly decreased Tl concentration in the renal medulla in rats treated with LLU-alpha. We speculate that the protective effect of LLU-alpha against Tl nephrotoxicity is caused both by its antioxidant effect and, at least in part, by its ability to decrease Tl concentration as a consequence of inhibited Tl(+) uptake through K(+) channels. This finding confirmed the similarity between K(+) and Tl(+) and also explained the significantly decreased Tl concentration in the renal medulla in rats treated with LLU-alpha.

  8. UMTS Common Channel Sensitivity Analysis

    DEFF Research Database (Denmark)

    Pratas, Nuno; Rodrigues, António; Santos, Frederico

    2006-01-01

    and as such it is necessary that both channels be available across the cell radius. This requirement makes the choice of the transmission parameters a fundamental one. This paper presents a sensitivity analysis regarding the transmission parameters of two UMTS common channels: RACH and FACH. Optimization of these channels...... is performed and values for the key transmission parameters in both common channels are obtained. On RACH these parameters are the message to preamble offset, the initial SIR target and the preamble power step while on FACH it is the transmission power offset....

  9. Direct binding of syndecan-4 cytoplasmic domain to the catalytic domain of protein kinase C alpha (PKC alpha) increases focal adhesion localization of PKC alpha

    DEFF Research Database (Denmark)

    Lim, Ssang-Taek; Longley, Robert L; Couchman, John R

    2003-01-01

    alpha. Full-length PKC alpha weakly interacted with 4V by yeast two-hybrid assays, but PKC alpha constructs that lack the pseudosubstrate region or constructs of the whole catalytic domain interacted more strongly. A mutated 4V sequence (4V(YF): LGKKPIFKK) did not interact with PKC alpha, indicating...

  10. Increased virulence and competitive advantage of a/alpha over a/a or alpha/alpha offspring conserves the mating system of Candida albicans.

    Science.gov (United States)

    Lockhart, Shawn R; Wu, Wei; Radke, Joshua B; Zhao, Rui; Soll, David R

    2005-04-01

    The majority of Candida albicans strains in nature are a/alpha and must undergo homozygosis to a/a or alpha/alpha to mate. Here we have used a mouse model for systemic infection to test the hypothesis that a/alpha strains predominate in nature because they have a competitive advantage over a/a and alpha/alpha offspring in colonizing hosts. Single-strain injection experiments revealed that a/alpha strains were far more virulent than either their a/a or alpha/alpha offspring. When equal numbers of parent a/alpha and offspring a/a or alpha/alpha cells were co-injected, a/alpha always exhibited a competitive advantage at the time of extreme host morbidity or death. When equal numbers of an engineered a/a/alpha2 strain and its isogenic a/a parent strain were co-injected, the a/a/alpha2 strain exhibited a competitive advantage at the time of host morbidity or death, suggesting that the genotype of the mating-type (MTL) locus, not associated genes on chromosome 5, provides a competitive advantage. We therefore propose that heterozygosity at the MTL locus not only represses white-opaque switching and genes involved in the mating process, but also affects virulence, providing a competitive advantage to the a/alpha genotype that conserves the mating system of C. albicans in nature.

  11. [(3)H]chlorpromazine photolabeling of the torpedo nicotinic acetylcholine receptor identifies two state-dependent binding sites in the ion channel.

    Science.gov (United States)

    Chiara, David C; Hamouda, Ayman K; Ziebell, Michael R; Mejia, Luis A; Garcia, Galo; Cohen, Jonathan B

    2009-10-27

    Chlorpromazine (CPZ), a potent nicotinic acetylcholine receptor (nAChR) noncompetitive antagonist, binds with higher affinity in the ion channel in the desensitized state than in the closed channel state and with low affinity to additional sites in nAChR-rich membranes. For nAChR equilibrated with agonist, we confirm previous reports that [(3)H]CPZ occupies a site near the cytoplasmic end of the M2 ion channel domain, photolabeling positions M2-2, M2-6, and/or M2-9 in each subunit. We find that [(3)H]CPZ also binds at the extracellular end of the channel, photolabeling amino acids at positions M2-16 (alpha,gamma), M2-17 (alpha,beta,delta), and M2-20 (alpha,beta,delta). The photolabeling at the cytoplasmic end of the channel is fully inhibitable by phencyclidine or proadifen, whereas neither drug inhibits [(3)H]CPZ photolabeling at the extracellular end, establishing that positively charged drugs can bind simultaneously at the cytoplasmic and extracellular ends of the ion channel. [(3)H]CPZ photolabeling is not detected in the transmembrane domain outside the ion channel, but it photolabels alphaMet-386 and alphaSer-393 in the cytoplasmic alphaMA helix. In the nAChR equilibrated with alpha-bungarotoxin to stabilize the nAChR in a closed state, [(3)H]CPZ photolabels amino acids at M2-5 (alpha), M2-6 (alpha,beta,delta), and M2-9 (beta,delta), with no labeling at M2-2. These results provide novel information about the modes of drug binding within the nAChR ion channel and indicate that within the nAChR transmembrane domain, the binding of cationic aromatic amine antagonists can be restricted to the ion channel domain, in contrast to the uncharged, allosteric potentiators and inhibitors that also bind within the delta subunit helix bundle and at subunit interfaces.

  12. Alpha intrusion on ovenight polysomnogram

    Directory of Open Access Journals (Sweden)

    Nahapetian R

    2014-06-01

    Full Text Available No abstract available. Article truncated after 150 words. A 30 year-old Army veteran with a past medical history significant for chronic lumbar back pain stemming from a fall-from-height injury sustained in 2006 was referred to the sleep laboratory for evaluation of chronic fatigue and excessive daytime hypersomnolence. His Epworth sleepiness scale score was 16. He denied a history of snoring and witnessed apnea. Body Mass Index (BMI was 25.7 kg/m2. His main sleep related complaints were frequent nocturnal arousals, poor sleep quality, un-refreshing sleep, prolonged latency to sleep onset, and nightmares. An In-lab attended diagnostic polysomnogram was performed. Sleep efficiency was reduced (73% and overall arousal index was not significantly elevated (3.2 events/hour. The sleep study showed rapid eye movement (REM related sleep disordered breathing that did not meet diagnostic criteria for sleep apnea. There was no evidence for period limb movement disorder. However, the study was significant for alpha wave intrusion in stage N2 non-REM and stage ...

  13. Diabetes and alpha lipoic acid

    Directory of Open Access Journals (Sweden)

    Issy eLaher

    2011-11-01

    Full Text Available Diabetes mellitus is a multi-faceted metabolic disorder where there is increased oxidative stress that contributes to the pathogenesis of this debilitating disease. This has prompted several investigations into the use of antioxidants as a complementary therapeutic approach. Alpha lipoic acid, a naturally occurring dithiol compound which plays an essential role in mitochondrial bioenergetic reactions, has gained considerable attention as an antioxidant for use in managing diabetic complications. Lipoic acid quenches reactive oxygen species, chelates metal ions, and reduces the oxidized forms of other antioxidants such as vitamin C, vitamin E and glutathione. It also boosts antioxidant defense system through Nrf2-mediated antioxidant gene expression and by modulation of peroxisome proliferator activated receptors-regulated genes. ALA inhibits nuclear factor kappa B and activates AMPK in skeletal muscles, which in turn have a plethora of metabolic consequences. These diverse actions suggest that a lipoic acid acts by multiple mechanisms, many of which have only been uncovered recently. In this review we briefly summarize the known biochemical properties of lipoic acid and then discussed the oxidative mechanisms implicated in diabetic complications and the mechanisms by which lipoic acid may ameliorate these reactions. The findings of some of the clinical trials in which lipoic acid administration has been tested in diabetic patients during the last 10 years are summarized. It appears that the clearest benefit of lipoic acid supplementation is in patients with diabetic neuropathy.

  14. Effects of alpha particles on zebrafish embryos

    International Nuclear Information System (INIS)

    Yum, E.H.W.; Choi, V.W.Y.; Yu, K.N.; Li, V.W.T.; Cheng, S.H.

    2008-01-01

    Full text: Ionizing radiation such as X-ray and alpha particles can damage cellular macromolecules, which can lead to DNA single- and double-strand breaks. In the present work, we studied the effects of alpha particles on dechorionated zebrafish embryos. Thin polyallyldiglycol carbonate (PADC) films with a thickness of 16 μm were prepared from commercially available PADC films (with thickness of 100 μm) by chemical etching and used as support substrates for holding zebrafish embryos for alpha-particle irradiation. These films recorded alpha-particle hit positions, quantified the number and energy of alpha particles actually incident on the embryo cells, and thus enabled the calculation of the dose absorbed by the embryo cells. Irradiation was made at 1.25 hours post fertilization (hpf) with various absorbed dose. TdT-mediated dUTP Nick-End Labeling (TUNEL) assay was performed on the embryos at different time stages after irradiation. Marked apoptosis was detected only in embryos at earlier time stages. The results showed that DNA double-strand break during zebrafish embryogenesis can be induced by alpha-particle irradiation, which suggests that zebrafish is a potential model for assessing the effects of alpha-particle radiation

  15. Cortical Alpha Activity in Schizoaffective Patients

    Directory of Open Access Journals (Sweden)

    Mahdi Moeini

    2017-02-01

    Full Text Available Objective: Electrophysiological studies have identified abnormal oscillatory activities in the cerebral cortex in schizophrenia and mood disorders. Biological and pathophysiological evidence suggests specific deficits in serotonin (5-HT receptor function in schizoaffective disorder (SA, a clinical syndrome with characteristics of both schizophrenia and bipolar disorder. This study investigated alpha oscillations in patients with SA.Method: Electroencephalography was used to measure ongoing and evoked alpha oscillations in 38 adults meeting Diagnostic and Statistical Manual of Mental Disorders–Fourth Edition (DSM–IV criteria for SA, and in 39 healthy controls.Results: Spontaneous alpha power of the participants with SA was significantly lower than that of healthy participants [F (1, 75 = 8.81, P < 0.01]. Evoked alpha activity was also decreased in SA compared to controls [F (1, 75 = 5.67, P = 0.025].Conclusion: A strong reduction of alpha power in the posterior regions may reflect abnormality in the thalamocortical circuits. It is shown that hypoxia and reduced cerebral blood flow is associated with reduced alpha activity among different regions of the brain. Therefore, it can be concluded that greatly decreased alpha activity, particularly in centro-parietal and occipital regions, is related to SA symptoms such as hallucinations.

  16. Negative particle planar and axial channeling and channeling collimation

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, Richard A., Jr.; /Fermilab

    2009-12-01

    While information exists on high energy negative particle channeling there has been little study of the challenges of negative particle bending and channeling collimation. Partly this is because negative dechanneling lengths are relatively much shorter. Electrons are not particularly useful for investigating negative particle channeling effects because their material interactions are dominated by channeling radiation. Another important factor is that the current central challenge in channeling collimation is the proton-proton Large Hadron Collider (LHC) where both beams are positive. On the other hand in the future the collimation question might reemerge for electon-positron or muon colliders. Dechanneling lengths increase at higher energies so that part of the negative particle experimental challenge diminishes. In the article different approaches to determining negative dechanneling lengths are reviewed. The more complicated case for axial channeling is also discussed. Muon channeling as a tool to investigate dechanneling is also discussed. While it is now possible to study muon channeling it will probably not illuminate the study of negative dechanneling.

  17. Lucid dreaming and alpha activity: a preliminary report.

    Science.gov (United States)

    Ogilvie, R D; Hunt, H T; Tyson, P D; Lucescu, M L; Jeakins, D B

    1982-12-01

    10 good dream recallers spent 2 nights in the sleep lab during which they were awakened 4 times per night from REM sleep, twice during their highest alpha activity in REM, and twice during low REM alpha. 5 were given alpha feedback training prior to sleep onset. Arousals from high alpha REM sleep yielded significantly higher lucidity ratings. Alpha feedback had no effect upon lucidity or REM alpha levels. Similarities between lucid dreams and meditative phenomena are discussed.

  18. Topographic distribution of EEG alpha attractor correlation dimension values in wake and drowsy states in humans.

    Science.gov (United States)

    Kalauzi, Aleksandar; Vuckovic, Aleksandra; Bojić, Tijana

    2015-03-01

    Organization of resting state cortical networks is of fundamental importance for the phenomenon of awareness, which is altered in the first part of hypnagogic period (Hori stages 1-4). Our aim was to investigate the change in brain topography pattern of EEG alpha attractor correlation dimension (CD) in the period of transition from Hori stage 1 to 4. EEG of ten healthy adult individuals was recorded in the wake and drowsy states, using a 14 channel average reference montage, from which 91 bipolar channels were derived and filtered in the wider alpha (6-14 Hz) range. Sixty 1s long epochs of each state and individual were subjected to CD calculation according to the Grassberger-Procaccia method. For such a collection of signals, two embedding dimensions, d={5, 10}, and 22 time delays τ=2-23 samples were explored. Optimal values were d=10 and τ=18, where both saturation and second zero crossing of the autocorrelation function occurred. Bipolar channel CD underwent a significant decrease during the transition and showed a positive linear correlation with electrode distance, stronger in the wake individuals. Topographic distribution of bipolar channels with above median CD changed from longitudinal anterior-posterior pattern (awake) to a more diagonal pattern, with localization in posterior regions (drowsiness). Our data are in line with the literature reporting functional segregation of neuronal assemblies in anterior and posterior regions during this transition. Our results should contribute to understanding of complex reorganization of the cortical part of alpha generators during the wake/drowsy transition. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. ZnO-channel thin-film transistors: Channel mobility

    International Nuclear Information System (INIS)

    Hoffman, R.L.

    2004-01-01

    ZnO-channel thin-film transistor (TFT) test structures are fabricated using a bottom-gate structure on thermally oxidized Si; ZnO is deposited via RF sputtering from an oxide target, with an unheated substrate. Electrical characteristics are evaluated, with particular attention given to the extraction and interpretation of transistor channel mobility. ZnO-channel TFT mobility exhibits severe deviation from that assumed by ideal TFT models; mobility extraction methodology must accordingly be recast so as to provide useful insight into device operation. Two mobility metrics, μ avg and μ inc , are developed and proposed as relevant tools in the characterization of nonideal TFTs. These mobility metrics are employed to characterize the ZnO-channel TFTs reported herein; values for μ inc as high as 25 cm2/V s are measured, comprising a substantial increase in ZnO-channel TFT mobility as compared to previously reported performance for such devices

  20. Four-channel ZnS scintillator measurements of escaping tritons in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Zweben, S.J.

    1988-10-01

    A four-channel scintillation detector capable of measuring tritons, protons, and alphas escaping from a tokamak plasma was operated during the 1986 run period of the Tokamak Fusion Test Reactor (TFTR). Signals consistent with the expected 1 MeV triton behavior have been observed during deuterium operation. Backgrounds associated with neutrons, gammas, and soft x-rays have been evaluated in situ. Such a detector should be capable of measuring escaping alphas during the D/T phase of TFTR. 16 refs., 10 figs.

  1. Four-channel ZnS scintillator measurements of escaping tritons in TFTR

    International Nuclear Information System (INIS)

    Zweben, S.J.

    1988-10-01

    A four-channel scintillation detector capable of measuring tritons, protons, and alphas escaping from a tokamak plasma was operated during the 1986 run period of the Tokamak Fusion Test Reactor (TFTR). Signals consistent with the expected 1 MeV triton behavior have been observed during deuterium operation. Backgrounds associated with neutrons, gammas, and soft x-rays have been evaluated in situ. Such a detector should be capable of measuring escaping alphas during the D/T phase of TFTR. 16 refs., 10 figs

  2. Anomalous atomic volume of alpha-Pu

    DEFF Research Database (Denmark)

    Kollar, J.; Vitos, Levente; Skriver, Hans Lomholt

    1997-01-01

    We have performed full charge-density calculations for the equilibrium atomic volumes of the alpha-phase light actinide metals using the local density approximation (LDA) and the generalized gradient approximation (GGA). The average deviation between the experimental and the GGA atomic radii is 1.......3%. The comparison between the LDA and GGA results show that the anomalously large atomic volume of alpha-Pu relative to alpha-Np can be ascribed to exchange-correlation effects connected with the presence of low coordinated sites in the structure where the f electrons are close to the onset of localization...

  3. Alpha spectral analysis via artificial neural networks

    International Nuclear Information System (INIS)

    Kangas, L.J.; Hashem, S.; Keller, P.E.; Kouzes, R.T.; Troyer, G.L.

    1994-10-01

    An artificial neural network system that assigns quality factors to alpha particle energy spectra is discussed. The alpha energy spectra are used to detect plutonium contamination in the work environment. The quality factors represent the levels of spectral degradation caused by miscalibration and foreign matter affecting the instruments. A set of spectra was labeled with a quality factor by an expert and used in training the artificial neural network expert system. The investigation shows that the expert knowledge of alpha spectra quality factors can be transferred to an ANN system

  4. Production of alpha 1-proteinase inhibitor (human).

    Science.gov (United States)

    Hein, R H; Van Beveren, S M; Shearer, M A; Coan, M H; Brockway, W J

    1990-03-01

    A method for large scale isolation of alpha 1-proteinase inhibitor (alpha 1-PI) is described. This method employs waste Cohn Fraction IV-1 as the starting material and involves fractional precipitation with polyethylene glycol followed by ion exchange chromatography on diethylaminoethanol (DEAE)-Sepharose. The process also incorporates a ten hour, at 60 degrees C, heat-treatment step to reduce or eliminate the risk of transmission of viral disease. The final product, having a purity of approximately 60%, is freeze-dried. This preparation behaves almost identically to the alpha 1-PI in plasma and is suitable for replacement therapy in hereditary emphysema.

  5. Measurements of $\\alpha_s$ in $pp$ Collisions at the LHC

    CERN Document Server

    Warburton, Andreas; The ATLAS collaboration

    2015-01-01

    The coupling of the strong force, $\\alpha_s$, is deemed to be a fundamental parameter of Nature, and, beyond the quark masses, constitutes the only free parameter in the QCD Lagrangian. Provided is an overview of CERN Large Hadron Collider (LHC) measurements of $\\alpha_s(M_Z)$ evaluated at the $Z$-boson mass and of the running of $\\alpha_s(Q)$ as a function of energy-momentum transfer $Q$. The measurements were performed by the ATLAS and CMS Collaborations using proton-proton ($pp$) collisions with centre-of-mass energies of 7 TeV and data samples with time-integrated luminosities of up to 5 fb$^{-1}$. Four different categories of observable were used in the described extractions of $\\alpha_s$: inclusive jet cross sections, 3-jet to 2-jet inclusive cross-section ratios, 3-jet mass cross sections, and top-quark pair production cross sections. These results, which include the first NNLO measurement of $\\alpha_s$ at a hadron collider and the first determinations of $\\alpha_s$ at energy scales above 1 TeV, are co...

  6. A Quantitative Electrochemiluminescence Assay for Clostridium perfringens alpha toxin

    National Research Council Canada - National Science Library

    Merrill, Gerald A; Rivera, Victor R; Neal, Dwayne D; Young, Charles; Poli, Mark A

    2006-01-01

    .... Biotinylated antibodies to C. perfringens alpha toxin bound to streptavidin paramagnetic beads specifically immunoadsorbed soluble sample alpha toxin which subsequently selectively immunoadsorbed ruthenium (Ru...

  7. One-sided asymptotically mean stationary channels

    OpenAIRE

    Simon, Francois

    2014-01-01

    This paper proposes an analysis of asymptotically mean stationary (AMS) communication channels. A hierarchy based on stability properties (stationarity, quasi-stationarity, recurrence and asymptotically mean stationarity) of channels is identified. Stationary channels are a subclass of quasi-stationary channels which are a subclass of recurrent AMS channels which are a subclass of AMS channels. These classes are proved to be stable under Markovian composition of channels (e.g., the cascade of...

  8. Making sense with TRP channels: store-operated calcium entry and the ion channel Trpm5 in taste receptor cells.

    Science.gov (United States)

    Pérez, Cristian A; Margolskee, Robert F; Kinnamon, Sue C; Ogura, Tatsuya

    2003-01-01

    The sense of taste plays a critical role in the life and nutritional status of organisms. During the last decade, several molecules involved in taste detection and transduction have been identified, providing a better understanding of the molecular physiology of taste receptor cells. However, a comprehensive catalogue of the taste receptor cell signaling machinery is still unavailable. We have recently described the occurrence of calcium signaling mechanisms in taste receptor cells via apparent store-operated channels and identified Trpm5, a novel candidate taste transduction element belonging to the mammalian family of transient receptor potential channels. Trpm5 is expressed in a tissue-restricted manner, with high levels in gustatory tissue. In taste cells, Trpm5 is co-expressed with taste-signaling molecules such as alpha-gustducin, Ggamma(13), phospholipase C beta(2) and inositol 1,4,5-trisphosphate receptor type III. Biophysical studies of Trpm5 heterologously expressed in Xenopus oocytes and mammalian CHO-K1 cells indicate that it functions as a store-operated channel that mediates capacitative calcium entry. The role of store-operated channels and Trpm5 in capacitative calcium entry in taste receptor cells in response to bitter compounds is discussed.

  9. An improved channel assessment scheme

    KAUST Repository

    Bader, Ahmed

    2014-05-01

    A source node in a multihop network determines whether to transmit in a channel based on whether the channel is occupied by a packet transmission with a large number of relays; whether the source node is in the data tones back-off zone; and the source node is in the busy tone back-off zone.

  10. Perceived quality of channel zapping

    NARCIS (Netherlands)

    Kooij, R.E.; Ahmed, K.; Brunnström, K.

    2006-01-01

    The end user experience of service quality is critical to the success of a service provider's IPTV deployment program. A key element involved in validating IPTV quality of experience (QoE) is how quickly and reliably users can change TV channels, often referred to as channel zapping. Currently there

  11. Channel Communication and Reconfigurable Hardware

    NARCIS (Netherlands)

    Bos, M.; Havinga, Paul J.M.; Smit, Gerardus Johannes Maria; Karelse, F.

    2000-01-01

    Many applications can be structured as a set of processes or threads that communicate via channels. These threads can be executed on various platforms (e.g. general purpose CPU, DSP, FPGA, etc). In our research we apply channels as a basic communication mechanism between threads in a reconfigurable

  12. Hydraulic jumps in a channel

    DEFF Research Database (Denmark)

    Bonn, D.; Andersen, Anders Peter; Bohr, Tomas

    2009-01-01

    We present a study of hydraulic jumps with flow predominantly in one direction, created either by confining the flow to a narrow channel with parallel walls or by providing an inflow in the form of a narrow sheet. In the channel flow, we find a linear height profile upstream of the jump as expected...

  13. Defect Distributions in Channeling Experiments

    DEFF Research Database (Denmark)

    Andersen, Hans Henrik; Sigmund, P.

    1965-01-01

    A simple collision model allows to calculate energy losses of perfectly channeled particles. The maximum energy loss is related in a simple way to the displacement energy of lattice atoms perpendicular to the channel. From that, one obtains rather definite predictions on the possibility...

  14. Neutron-induced alpha radiography

    International Nuclear Information System (INIS)

    Pereira, Marco Antonio Stanojev

    2008-01-01

    A new radiography technique to inspect thin samples was developed. Low energy alpha particles, generated by a boron based screen under thermal neutron irradiation, are used as penetrating radiation. The solid state nuclear track detector CR-39 has been used to register the image. The interaction of the α - particles with the CR-39 gives rise to damages which under an adequate chemical etching became tracks the basic units forming the image. A digital system was developed for data acquisition and data analysis as well as for image processing. The irradiation and etching conditions to obtain the best radiography are 1,3 hours and 25 minutes at 70 deg C respectively. For such conditions samples having 10 μm in thickness can be inspected with a spatial resolution of 32 μm. The use of the digital system has reduced the time spent for data acquisition and data analysis and has improved the radiography image visualization. Furthermore, by using the digital system, it was possible to study several new parameters regarding the tracks which are very important to understand and study the image formation theory in solid state nuclear track detectors, the one used in this thesis. Some radiography images are also shown which demonstrate the potential of the proposed radiography technique. When compared with the other radiography techniques already in use to inspect thin samples, the present one developed in the present paper allows a smaller time to obtain the image, it is not necessary to handle liquid radioactive substances, the detector is insensitive to β, γ, X-ray and visible light. (author)

  15. Liquid scintillation alpha particle spectrometry. Progress report

    International Nuclear Information System (INIS)

    Bell, L.L.; Hakooz, S.A.; Johnson, L.O.; Nieschmidt, E.B.; Meikrantz, D.H.

    1979-12-01

    Objective to develop a technique whereby Pu may be put into solution, extracted by solvent extraction into a suitable extractive scintillant and subsequently counted. Presented here are results of attempts to separate beta and alpha activities through pulse shape discrimination. A qualitative discussion is given which yields alpha particle peak widths, resolution and response. The detection efficiency for alpha particles in a liquid scintillant is 100%. Present detection sensitivities of the equipment being used are: 4.5 x 10 -6 μCi (100 s), 1.2 x 10 -6 μCi (1000 s), and 4.0 x 10 -7 μCi (10,000 s) at the 3 sigma level. The detectability of a particular alpha-emitting species is strongly dependent upon the population of other species. The ability to discriminate depends upon the system resolution. 14 figures, 2 tables

  16. NEW APPROACHES TO CONFINED ALPHA DIAGNOSTICS

    Energy Technology Data Exchange (ETDEWEB)

    FISHER,R.K

    2004-04-01

    Three new approaches to obtain information on the confined fast alphas in International Thermonuclear Experimental Reactor (ITER) are proposed. The first technique measures the energetic charge exchange (CX) neutrals that result from the alpha collision-induced knock-on fuel ion tails undergoing electron capture on the MeV D neutral beams planned for heating and current drive. The second technique measures the energetic knock-on neutron tail due to alphas using the lengths of the proton recoil tracks produced by neutron collisions in nuclear emulsions. The range of the 14 to 20 MeV recoil protons increases by {approx}140 microns per MeV. The third approach would measure the CX helium neutrals resulting from confined alphas capturing two electrons in the ablation cloud surrounding a dense gas jet that has been proposed for disruption mitigation in ITER.

  17. NEW APPROACHES TO CONFINED ALPHA DIAGNOSTICS

    International Nuclear Information System (INIS)

    FISHER, R.K.

    2004-01-01

    Three new approaches to obtain information on the confined fast alphas in International Thermonuclear Experimental Reactor (ITER) are proposed. The first technique measures the energetic charge exchange (CX) neutrals that result from the alpha collision-induced knock-on fuel ion tails undergoing electron capture on the MeV D neutral beams planned for heating and current drive. The second technique measures the energetic knock-on neutron tail due to alphas using the lengths of the proton recoil tracks produced by neutron collisions in nuclear emulsions. The range of the 14 to 20 MeV recoil protons increases by ∼140 microns per MeV. The third approach would measure the CX helium neutrals resulting from confined alphas capturing two electrons in the ablation cloud surrounding a dense gas jet that has been proposed for disruption mitigation in ITER

  18. Strichartz estimates on $alpha$-modulation spaces

    Directory of Open Access Journals (Sweden)

    Weichao Guo

    2013-05-01

    Full Text Available In this article, we consider some dispersive equations, including Schrodinger equations, nonelliptic Schrodinger equations, and wave equations. We develop some Strichartz estimates in the frame of alpha-modulation spaces.

  19. Targeted alpha therapy: Applications and current status

    Energy Technology Data Exchange (ETDEWEB)

    Bruchertseifer, Frank, E-mail: frank.bruchertseifer@ec.europa.eu [European Commission, Joint Research Centre, Karlsruhe (Germany)

    2017-07-01

    Full text: The field of targeted alpha therapy has been developed rapidly in the last decade. Besides {sup 223}Ra, {sup 211}At and {sup 212}Pb/{sup 212}Bi the alpha emitters {sup 225}Ac and {sup 213}Bi are promising therapeutic radionuclides for application in targeted alpha therapy of cancer and infectious diseases. The presentation will give a short overview about the current clinical treatments with alpha emitting radionuclides and will place an emphasis on the most promising clinical testing of peptides and antibodies labelled with {sup 225}Ac and {sup 213}Bi for treatment of metastatic castration-resistant prostate cancer patients with glioma and glioblastoma multiform, PSMA-positive tumor phenotype and bladder carcinoma in situ. (author)

  20. Calibration of alpha surface contamination monitor

    International Nuclear Information System (INIS)

    Freitas, I.S.M. de; Goncalez, O.L.

    1990-01-01

    In this work, the results, as well as the methodology, of the calibration of an alpha surface contamination monitor are presented. The calibration factors are obtained by least-squares fitting with effective variance. (author)

  1. Solar Imagery - Chromosphere - H-Alpha

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of H-alpha photographic datasets contributed by a number of national and private solar observatories located worldwide. Solar...

  2. Energy dependence of event shapes and of $\\alpha_s$ at LEP 2

    CERN Document Server

    Abreu, P; Adye, T; Adzic, P; Albrecht, Z; Alderweireld, T; Alekseev, G D; Alemany, R; Allmendinger, T; Allport, P P; Almehed, S; Amaldi, Ugo; Amapane, N; Amato, S; Anassontzis, E G; Andersson, P; Andreazza, A; Andringa, S; Antilogus, P; Apel, W D; Arnoud, Y; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barbiellini, Guido; Barbier, R; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Beillière, P; Belokopytov, Yu A; Belous, K S; Benekos, N C; Benvenuti, Alberto C; Bérat, C; Berggren, M; Bertini, D; Bertrand, D; Besançon, M; Bianchi, F; Bigi, M; Bilenky, S M; Bizouard, M A; Bloch, D; Blom, H M; Bonesini, M; Bonivento, W; Boonekamp, M; Booth, P S L; Borgland, A W; Borisov, G; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Boyko, I; Bozovic, I; Bozzo, M; Branchini, P; Brenke, T; Brenner, R A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschbeck, Brigitte; Buschmann, P; Cabrera, S; Caccia, M; Calvi, M; Camporesi, T; Canale, V; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Chapkin, M M; Charpentier, P; Chaussard, L; Checchia, P; Chelkov, G A; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Chudoba, J; Cieslik, K; Collins, P; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Cowell, J H; Crawley, H B; Crennell, D J; Crépé, S; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Davenport, Martyn; Da Silva, W; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Min, A; De Paula, L S; Dijkstra, H; Di Ciaccio, Lucia; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Dris, M; Duperrin, A; Durand, J D; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Ellert, M; Elsing, M; Engel, J P; Erzen, B; Espirito-Santo, M C; Falk, E; Fanourakis, G K; Fassouliotis, D; Fayot, J; Feindt, Michael; Fenyuk, A; Ferrari, P; Ferrer, A; Ferrer-Ribas, E; Ferro, F; Fichet, S; Firestone, A; Flagmeyer, U; Föth, H; Fokitis, E; Fontanelli, F; Franek, B J; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gamblin, S; Gandelman, M; García, C; Gaspar, C; Gaspar, M; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Ghodbane, N; Gil, I; Glege, F; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; González-Caballero, I; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Grahl, J; Graziani, E; Green, C; Grimm, H J; Gris, P; Grosdidier, G; Grzelak, K; Günther, M; Guy, J; Hahn, F; Hahn, S; Haider, S; Hallgren, A; Hamacher, K; Hansen, J; Harris, F J; Hedberg, V; Heising, S; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Heuser, J M; Higón, E; Holmgren, S O; Holt, P J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hughes, G J; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, P E; Joram, C; Juillot, P; Kapusta, F; Karafasoulis, K; Katsanevas, S; Katsoufis, E C; Keränen, R; Kersevan, Borut P; Khomenko, B A; Khovanskii, N N; Kiiskinen, A P; King, B J; Kinvig, A; Kjaer, N J; Klapp, O; Klein, H; Kluit, P M; Kokkinias, P; Koratzinos, M; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Krammer, Manfred; Kriznic, E; Krstic, J; Krumshtein, Z; Kubinec, P; Kurowska, J; Kurvinen, K L; Lamsa, J; Lane, D W; Langefeld, P; Lapin, V; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Leinonen, L; Leisos, A; Leitner, R; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Lethuillier, M; Libby, J; Liko, D; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; Lopes, J H; López, J M; López-Fernandez, R; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Mahon, J R; Maio, A; Malek, A; Malmgren, T G M; Maltezos, S; Malychev, V; Mandl, F; Marco, J; Marco, R P; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Masik, J; Mazzucato, F; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; McPherson, G; Meroni, C; Meyer, W T; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Moch, M; Møller, R; Mönig, K; Monge, M R; Moreau, X; Morettini, P; Morton, G A; Müller, U; Münich, K; Mulders, M; Mulet-Marquis, C; Muresan, R; Murray, W J; Muryn, B; Myatt, Gerald; Myklebust, T; Naraghi, F; Nassiakou, M; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Némécek, S; Neufeld, N; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nikolenko, M; Nomokonov, V P; Normand, Ainsley; Nygren, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Orazi, G; Österberg, K; Ouraou, A; Paganoni, M; Paiano, S; Pain, R; Paiva, R; Palacios, J; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Pegoraro, M; Peralta, L; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Phillips, H T; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Ratoff, P N; Read, A L; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Reinhardt, R; Renton, P B; Resvanis, L K; Richard, F; Rídky, J; Rinaudo, G; Røhne, O M; Romero, A; Ronchese, P; Rosenberg, E I; Rosinsky, P; Roudeau, Patrick; Rovelli, T; Royon, C; Ruhlmann-Kleider, V; Ruiz, A; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sajot, G; Salt, J; Sampsonidis, D; Sannino, M; Schneider, H; Schwemling, P; Schwering, B; Schwickerath, U; Schyns, M A E; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Sekulin, R L; Shellard, R C; Sheridan, A; Siebel, M; Simard, L C; Simonetto, F; Sissakian, A N; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sopczak, André; Sosnowski, R; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stanescu, C; Stanic, S; Stevenson, K; Stocchi, A; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tegenfeldt, F; Terranova, F; Thomas, J; Timmermans, J; Tinti, N; Tkatchev, L G; Todorova-Nová, S; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tzamarias, S; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; Van der Velde, C; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Van Lysebetten, A; Van Vulpen, I B; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Verzi, V; Vilanova, D; Vitale, L; Vlasov, E; Vodopyanov, A S; Vollmer, C F; Voulgaris, G; Vrba, V; Wahlen, H; Walck, C; Weiser, C; Wicke, D; Wickens, J H; Wilkinson, G R; Winter, M; Witek, M; Wolf, G; Yi, J; Yushchenko, O P; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zucchelli, G C; Zumerle, G

    1999-01-01

    Infrared and collinear safe event shape distributions and their mean values are determined using the data taken at ve di erent centre of mass energies above $M_Z$ with the DELPHI detector at LEP. From the event shapes, the strong coupling $\\alpha_s$ is extracted in $O(\\alpha^2_s)$, NLLA and a combined scheme using hadronisation corrections evaluated with fragmentation model generators as well as using an analytical power ansatz. Comparing these measurements to those obtained at MZ, the energy dependence (running) of $\\alpha_s$ is accessible. The logarithmic energy slope of the inverse strong coupling is measured to be $d\\alpha_{s}^{-1}/d log(E_{cm}) = 1.39 \\pm 0.34(stat) \\pm 0.17(syst)$, in good agreement with the QCD expectation of 1.27.

  3. Influence of fast alpha diffusion and thermal alpha buildup on tokamak reactor performance

    International Nuclear Information System (INIS)

    Uckan, N.A.; Tolliver, J.S.; Houlberg, W.A.; Attenberger, S.E.

    1988-01-01

    The effect of fast alpha diffusion and thermal alpha accumulation on the confinement capability of a candidate Engineering Test Reactor plasma (Tokamak Ignition/Burn Experimental Reactor) in achieving ignition and steady-state driven operation has been assessed using both global and 1-1/2-dimensional transport models. Estimates are made of the threshold for radial diffusion of fast alphas and thermal alpha buildup. It is shown that a relatively low level of radial transport, when combined with large gradients in the fast alpha density, leads to a significant radial flow with a deleterious effect on plasma performance. Similarly, modest levels of thermal alpha concentration significantly influence the ignition and steady-state burn capability

  4. Voltage-gated Proton Channels

    Science.gov (United States)

    DeCoursey, Thomas E.

    2014-01-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

  5. Measurement of the angle alpha at BABAR

    Energy Technology Data Exchange (ETDEWEB)

    Perez, A.; /Orsay, LAL

    2009-06-25

    The authors present recent measurements of the CKM angle {alpha} using data collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory, operating at the {Upsilon}(4S) resonance. They present constraints on {alpha} from B {yields} {pi}{pi}, B {yields} {rho}{rho} and B {yields} {rho}{pi} decays.

  6. Improved peak shape fitting in alpha spectra

    OpenAIRE

    POMME Stefaan; CARO MARROYO BELEN

    2014-01-01

    Peak overlap is a recurrent issue ina lpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown...

  7. Conceptual design report for alpha waste incinerator

    International Nuclear Information System (INIS)

    1979-04-01

    The Alpha Waste Incinerator, a new facility in the SRP H-Area, will process transuranic or alpha-contaminated combustible solid wastes. It will seal the radioactive ash and scrubbing salt residues in cans for interim storage in drums on site burial ground pads. This report includes objectives, project estimate, schedule, standards and criteria, excluded costs, safety evaluation, energy consumption, environmental assessment, and key drawings

  8. Beteigeuze (Alpha Orionis) und Mintaka (Delta Orionis)

    Science.gov (United States)

    Vollmann, Wolfgang

    2013-02-01

    Magnitude measures transformed to Johnson V of Alpha Orionis (Betelgeuse) and Delta Orionis with a wide-angle lens and DSLR are presented and discussed. Alpha Orionis light changes are shown clearly. The primary and secondary eclipses of Delta Orionis with amplitudes of 0.12 and 0.05 mag respectively are clearly recorded. They occur near phase 0.00 and 0.50 respectively of current elements from VSX (2).

  9. Considering the determination of an alpha value

    International Nuclear Information System (INIS)

    Lorenz, B.

    1987-01-01

    Following an outline of the most important international methods of evaluating an alpha value (the monetary equivalent of one man-sievert) and an approach deemed suitable for use in the GDR, it is recommended that alpha be taken as 30,000 Mark per man-sievert in national cost-benefit analyses. This value should be revisited every five to ten years. (author)

  10. Alpha-root Processes for Derivatives pricing

    OpenAIRE

    Balakrishna, BS

    2010-01-01

    A class of mean reverting positive stochastic processes driven by alpha-stable distributions, referred to here as alpha-root processes in analogy to the square root process (Cox-Ingersoll-Ross process), is a subclass of affine processes, in particular continuous state branching processes with immigration (CBI processes). Being affine, they provide semi-analytical results for the implied term structures as well as for the characteristic exponents for their associated distributions. Their use h...

  11. Self-assembling, dynamic alphaPNAs

    DEFF Research Database (Denmark)

    Nielsen, Peter E

    2009-01-01

    In the recent report published in Science, Ghadiri and coworkers describe dynamic tPNAs, alphaPNA derivatives with a nucleobase attached via a thioester bond that are a step forward toward self-repairing and replicating molecules.......In the recent report published in Science, Ghadiri and coworkers describe dynamic tPNAs, alphaPNA derivatives with a nucleobase attached via a thioester bond that are a step forward toward self-repairing and replicating molecules....

  12. Alpha-emitters for medical therapy workshop

    International Nuclear Information System (INIS)

    Feinendegen, L.E.; McClure, J.J.

    1996-01-01

    A workshop on ''Alpha-Emitters for Medical Therapy'' was held May 30-31, 1996 in Denver Colorado to identify research goals and potential clinical needs for applying alpha-particle emitters and to provide DOE with sufficient information for future planning. The workshop was attended by 36 participants representing radiooncology, nuclear medicine, immunotherapy, radiobiology, molecular biology, biochemistry, radiopharmaceutical chemistry, dosimetry, and physics. This report provides a summary of the key points and recommendations arrived at during the conference

  13. Alpha-Tocopheryl succinate causes mitochondrial permeabilization by preferential formation of Bak channels

    Czech Academy of Sciences Publication Activity Database

    Procházka, L.; Dong, L.F.; Vališ, Karel; Freeman, R.; Ralph, S.J.; Turánek, J.; Neužil, Jiří

    2010-01-01

    Roč. 15, č. 7 (2010), s. 782-794 ISSN 1360-8185 R&D Projects: GA AV ČR(CZ) KAN200520703; GA AV ČR(CZ) IAA500520702; GA AV ČR(CZ) IAA500520602 Institutional research plan: CEZ:AV0Z50520701 Keywords : Vitamin E succinate * apoptosis * Noxa-Bak Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.397, year: 2010

  14. Robust blind identification of room acoustic channels in symmetric alpha-stable distributed noise environments.

    Science.gov (United States)

    He, Hongsen; Lu, Jing; Chen, Jingdong; Qiu, Xiaojun; Benesty, Jacob

    2014-08-01

    Blind multichannel identification is generally sensitive to background noise. Although there have been some efforts in the literature devoted to improving the robustness of blind multichannel identification with respect to noise, most of those works assume that the noise is Gaussian distributed, which is often not valid in real room acoustic environments. This paper deals with the more practical scenario where the noise is not Gaussian. To improve the robustness of blind multichannel identification to non-Gaussian noise, a robust normalized multichannel frequency-domain least-mean M-estimate algorithm is developed. Unlike the traditional approaches that use the squared error as the cost function, the proposed algorithm uses an M-estimator to form the cost function, which is shown to be immune to non-Gaussian noise with a symmetric α-stable distribution. Experiments based on the identification of a single-input/multiple-output acoustic system demonstrate the robustness of the proposed algorithm.

  15. Cytokine vaccination: neutralising IL-1alpha autoantibodies induced by immunisation with homologous IL-1alpha

    DEFF Research Database (Denmark)

    Svenson, M; Hansen, M B; Thomsen, Allan Randrup

    2000-01-01

    High-affinity IgG autoantibodies (aAb) to IL-1alpha are among the most frequently found aAb to cytokines in humans. To establish an animal model with aAb to IL-1alpha, we immunised mice with recombinant murine IL-1alpha. Unprimed and Bacille Calmette-Guérin (BCG)-primed BALB/cA mice were vaccinat...

  16. Amazon floodplain channels regulate channel-floodplain water exchange

    Science.gov (United States)

    Bates, P. D.; Baugh, C.; Trigg, M.

    2017-12-01

    We examine the role of floodplain channels in regulating the exchange of water between the Amazon main stem and its extensive floodplains using a combination of field survey, remote sensing and numerical modelling for a 30,000 km2 area around the confluence of the Solimões and Purus rivers. From Landsat imagery we identified 1762 individual floodplain channel reaches with total length of nearly 9300 line km that range in width from 900m to 20m. Using a boat survey we measured width and depth along 509 line km of floodplain channels in 45 separate reaches and used these data to develop geomorphic relationships between width and depth. This enabled reconstruction of the depth of all other channels in the Landsat survey to an RMSE of 2.5m. We then constructed a 2D hydraulic model of this site which included all 9300km of floodplain channels as sub-grid scale features using a recently developed version of the LISFLOOD-FP code. The DEM for the model was derived from a version of the SRTM Digital Elevation Model that was processed to remove vegetation artefacts. The model was run at 270m resolution over the entire 30,000 km2 domain for the period from 2002-2009. Simulations were run with and without floodplain channels to examine the impact of these features on floodplain flow dynamics and storage. Simulated floodplain channel hydraulics were validated against a combination of in-situ and remotely sensed data. Our results show that approximately 100 km3 of water is exchanged between the channel and the floodplain during a typical annual cycle, and 8.5±2.1% of mainstem flows is routed through the floodplain. The overall effect of floodplains channels was to increase the duration of connections between the Amazon River and the floodplain. Inclusion of floodplain channels in the model increased inundation volume by 7.3% - 11.3% at high water, and decreased it at low water by 4.0% - 16.6%, with the range in these estimates due to potential errors in floodplain channel

  17. Liquid-scintillation alpha-detection techniques

    International Nuclear Information System (INIS)

    McKlveen, J.W.; McDowell, W.J.

    1983-01-01

    Accurate, quantitative determinations of alpha-emitting nuclides by conventional plate-counting methods are difficult because of sample self-absorption problems in counting and because of non-reproducible losses in conventional sample separation methods. Liquid scintillation alpha spectrometry offers an attractive with no sample self-absorption or geometry problems and with 100% counting efficiency. Sample preparation may include extraction of the alpha emitter of interest by a specific organic-phase-soluble compound directly into the liquid scintillation counting medium. Detection electronics use energy and pulse-shape discrimination to yield alpha spectra without beta and gamma background interference. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium, and polonium assay. Possibilities for a large number of other applications exist. Accuracy and reproducibility are typically in the 1% range. Backgrounds on the order of 0.01 cpm are readily achievable. The paper will present an overview of liquid scintillation alpha counting techniques and some of the results achieved for specific applications

  18. Structures of G [alpha [superscript i1

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Christopher A.; Willard, Francis S.; Jezyk, Mark R.; Fredericks, Zoey; Bodor, Erik T.; Jones, Miller B.; Blaesius, Rainer; Watts, Val J.; Harden, T. Kendall; Sondek, John; Ramer, J. Kevin; Siderovski, David P. (Karo Bio); (UNC); (Purdue)

    2010-07-19

    Heterotrimeric G proteins are molecular switches that regulate numerous signaling pathways involved in cellular physiology. This characteristic is achieved by the adoption of two principal states: an inactive, GDP bound state and an active, GTP bound state. Under basal conditions, G proteins exist in the inactive, GDP bound state; thus, nucleotide exchange is crucial to the onset of signaling. Despite our understanding of G protein signaling pathways, the mechanism of nucleotide exchange remains elusive. We employed phage display technology to identify nucleotide state-dependent G{alpha} binding peptides. Herein, we report a GDP-selective G{alpha} binding peptide, KB-752, that enhances spontaneous nucleotide exchange of G{alpha}{sub i} subunits. Structural determination of the G{alpha}{sub i1}/peptide complex reveals unique changes in the G{alpha} switch regions predicted to enhance nucleotide exchange by creating a GDP dissociation route. Our results cast light onto a potential mechanism by which G{alpha} subunits adopt a conformation suitable for nucleotide exchange.

  19. Current status and perspectives in alpha radioimmunotherapy.

    Science.gov (United States)

    Chérel, M; Davodeau, F; Kraeber-Bodéré, F; Chatal, J F

    2006-12-01

    Systemic administration of radiolabeled antibody directed against tumor antigens in radioimmunotherapy (RIT) enables to specifically target the cancer cells and to destroy them. So far, this strategy has proven its efficiency in the treatment of some hematological cancers with antibodies labeled with beta emitting radionuclides. In the last 2 decades, availability of short half life alpha emitters prompted to consider their use in RIT. Contrary to beta particles, alpha particles have a short path length and display a high lineic energy transfer. Those physical characteristics open new fields of clinical applications complementary to beta-RIT. To date, alpha-RIT is still at a preclinical stage of development: the radiolabeling methods need to be optimized to ensure in vivo stability of the radiopharmaceuticals. Some radionuclides have complex decay schemes with daughters emitting further alpha particles whose toxicity needs to be investigated. The modalities of administration of radiolabeled antibodies in animal models require also to be improved for delivering higher doses to tumor targets. A comprehensive analysis of the specific events occurring at cell or tissue level in response to alpha irradiation would be of great interest in order to define the best therapeutic association for residual disease or consolidation treatments. This approach has been proven to be efficient in increasing antitumor response either by using high doses with organ protection (kidney, bone marrow) or by a synergistic effect between alpha-RIT and associated treatments, such as chemotherapy.

  20. Systemic Targeted Alpha Radiotherapy for Cancer

    Directory of Open Access Journals (Sweden)

    Allan B. J.

    2013-09-01

    Full Text Available Background: The fundamental principles of internal targeted alpha therapy for cancer were established many decades ago.The high linear energy transfer (LET of alpha radiation to the targeted cancer cellscauses double strand breaks in DNA. At the same time, the short range radiation spares adjacent normal tissues. This targeted approach complements conventional external beam radiotherapy and chemotherapy. Such therapies fail on several fronts, such as lack of control of some primary cancers (e.g.glioblastoma multiformeand to inhibit the development of lethal metastatic cancer after successful treatment of the primary cancer. Objective: This review charts the developing role of systemic high LET, internal radiation therapy. Method: Targeted alpha therapy is a rapidly advancing experimental therapy that holds promise to deliver high cytotoxicity to targeted cancer cells. Initially thought to be indicated for leukemia and micrometastases, there is now evidence that solid tumors can also be regressed. Results: Alpha therapy may be molecular or physiological in its targeting. Alpha emitting radioisotopes such as Bi-212, Bi-213, At-211 and Ac-225 are used to label monoclonal antibodies or proteins that target specifc cancer cells. Alternatively, Radium-233 is used for palliative therapy of breast and prostate cancers because of its bone seeking properties. Conclusion: Preclinical studies and clinical trials of alpha therapy are discussed for leukemia, lymphoma, melanoma, glioblastoma multiforme, bone metastases, ovarian cancer, pancreatic cancer and other cancers.

  1. Structure and inhibition of the SARS coronavirus envelope protein ion channel.

    Directory of Open Access Journals (Sweden)

    Konstantin Pervushin

    2009-07-01

    Full Text Available The envelope (E protein from coronaviruses is a small polypeptide that contains at least one alpha-helical transmembrane domain. Absence, or inactivation, of E protein results in attenuated viruses, due to alterations in either virion morphology or tropism. Apart from its morphogenetic properties, protein E has been reported to have membrane permeabilizing activity. Further, the drug hexamethylene amiloride (HMA, but not amiloride, inhibited in vitro ion channel activity of some synthetic coronavirus E proteins, and also viral replication. We have previously shown for the coronavirus species responsible for severe acute respiratory syndrome (SARS-CoV that the transmembrane domain of E protein (ETM forms pentameric alpha-helical bundles that are likely responsible for the observed channel activity. Herein, using solution NMR in dodecylphosphatidylcholine micelles and energy minimization, we have obtained a model of this channel which features regular alpha-helices that form a pentameric left-handed parallel bundle. The drug HMA was found to bind inside the lumen of the channel, at both the C-terminal and the N-terminal openings, and, in contrast to amiloride, induced additional chemical shifts in ETM. Full length SARS-CoV E displayed channel activity when transiently expressed in human embryonic kidney 293 (HEK-293 cells in a whole-cell patch clamp set-up. This activity was significantly reduced by hexamethylene amiloride (HMA, but not by amiloride. The channel structure presented herein provides a possible rationale for inhibition, and a platform for future structure-based drug design of this potential pharmacological target.

  2. Nonequivalence of alpha-bungarotoxin binding sites in the native nicotinic receptor molecule

    International Nuclear Information System (INIS)

    Conti-Tronconi, B.M.; Tang, F.; Walgrave, S.; Gallagher, W.

    1990-01-01

    In the native, membrane-bound form of the nicotinic acetylcholine receptor (M-AcChR) the two sites for the cholinergic antagonist alpha-bungarotoxin (alpha-BGT) have different binding properties. One site has high affinity, and the M-AcChR/alpha-BGT complexes thus formed dissociate very slowly, similar to the complexes formed with detergent-solubilized AcChR (S-AcChR). The second site has much lower affinity (KD approximately 59 +/- 35 nM) and forms quickly reversible complexes. The nondenaturing detergent Triton X-100 is known to solubilize the AcChR in a form unable, upon binding of cholinergic ligands, to open the ion channel and to become desensitized. Solubilization of the AcChR in Triton X-100 affects the binding properties of this second site and converts it to a high-affinity, slowly reversible site. Prolonged incubation of M-AcChR at 4 degrees C converts the low-affinity site to a high-affinity site similar to those observed in the presence of Triton X-100. Although the two sites have similar properties when the AcChR is solubilized in Triton X-100, their nonequivalence can be demonstrated by the effect on alpha-BGT binding of concanavalin A, which strongly reduces the association rate of one site only. The Bmax of alpha-BGT to either Triton-solubilized AcChR or M-AcChR is not affected by the presence of concanavalin A. Occupancy of the high-affinity, slowly reversible site in M-AcChR inhibits the Triton X-100 induced conversion to irreversibility of the second site. At difference with alpha-BGT, the long alpha-neurotoxin from Naja naja siamensis venom (alpha-NTX) binds with high affinity and in a very slowly reversible fashion to two sites in the M-AcChR. We confirm here that Triton-solubilized AcChR or M-AcChR binds in a very slowly reversible fashion the same amount of alpha-NTX

  3. NALCN ion channels have alternative selectivity filters resembling calcium channels or sodium channels

    NARCIS (Netherlands)

    Senatore, A.; Monteil, A.; van Minnen, J.; Smit, A.B.; Spafford, J.D.

    2013-01-01

    NALCN is a member of the family of ion channels with four homologous, repeat domains that include voltage-gated calcium and sodium channels. NALCN is a highly conserved gene from simple, extant multicellular organisms without nervous systems such as sponges and placozoans and mostly remains a single

  4. Alpha band cortico-muscular coherence occurs in healthy individuals during mechanically-induced tremor.

    Directory of Open Access Journals (Sweden)

    Francesco Budini

    Full Text Available The present work aimed at investigating the effects of mechanically amplified tremor on cortico-muscular coherence (CMC in the alpha band. The study of CMC in this specific band is of particular interest because this coherence is usually absent in healthy individuals and it is an aberrant feature in patients affected by pathological tremors; understanding its mechanisms is therefore important. Thirteen healthy volunteers (23±4 years performed elbow flexor sustained contractions both against a spring load and in isometric conditions at 20% of maximal voluntary isometric contraction (MVC. Spring stiffness was selected to induce instability in the stretch reflex servo loop. 64 EEG channels, surface EMG from the biceps brachii muscle and force were simultaneously recorded. Contractions against the spring resulted in greater fluctuations of the force signal and EMG amplitude compared to isometric conditions (p<.05. During isometric contractions CMC was systematically found in the beta band and sporadically observed in the alpha band. However, during the contractions against the spring load, CMC in the alpha band was observed in 12 out of 13 volunteers. Partial directed coherence (PDC revealed an increased information flow in the EMG to EEG direction in the alpha band (p<.05. Therefore, coherence in the alpha band between the sensory-motor cortex and the biceps brachii muscle can be systematically induced in healthy individuals by mechanically amplifying tremor. The increased information flow in the EMG to EEG direction may reflect enhanced afferent activity from the muscle spindles. These results may contribute to the understanding of the presence of alpha band CMC in tremor related pathologies by suggesting that the origin of this phenomenon may not only be at cortical level but may also be affected by spinal circuit loops.

  5. Cytokine vaccination: neutralising IL-1alpha autoantibodies induced by immunisation with homologous IL-1alpha

    DEFF Research Database (Denmark)

    Svenson, M; Hansen, M B; Thomsen, Allan Randrup

    2000-01-01

    High-affinity IgG autoantibodies (aAb) to IL-1alpha are among the most frequently found aAb to cytokines in humans. To establish an animal model with aAb to IL-1alpha, we immunised mice with recombinant murine IL-1alpha. Unprimed and Bacille Calmette-Guérin (BCG)-primed BALB/cA mice were vaccinated...... in mice by vaccination with recombinant murine IL-1alpha conjugated to PPD. Studies of the effects of IL-1alpha aAb in such animals may help clarify the importance of naturally occurring IL-1alpha aAb in humans and permit the evaluation of future therapies with cytokine aAb in patients...... with IL-1alpha coupled to purified protein derivative of tuberculin (PPD). Both unprimed and primed animals developed IgG aAb to IL-1alpha. These aAb persisted at high levels more than 100 days after vaccination and did not cross-react with murine IL-1beta. The induced anti-IL-1alpha aAb inhibited binding...

  6. Alpha 1-blockers vs 5 alpha-reductase inhibitors in benign prostatic hyperplasia. A comparative review

    DEFF Research Database (Denmark)

    Andersen, J T

    1995-01-01

    During recent years, pharmacological treatment of symptomatic benign prostatic hyperplasia (BPH) has become the primary treatment choice for an increasing number of patients. The 2 principal drug classes employed are alpha 1-blockers and 5 alpha-reductase inhibitors. Current information from...... of patients who will respond well to alpha 1-blockers have yet to be identified, and data concerning the long term effects of these drugs are not yet available. 5 alpha-Reductase inhibitors have a slow onset of effect, but treatment leads to improvement in symptoms, reduction of the size of the prostate gland...... or unwilling to undergo surgical resection of the prostate will benefit from such therapy....

  7. Substrate channeling in proline metabolism

    Science.gov (United States)

    Arentson, Benjamin W.; Sanyal, Nikhilesh; Becker, Donald F.

    2012-01-01

    Proline metabolism is an important pathway that has relevance in several cellular functions such as redox balance, apoptosis, and cell survival. Results from different groups have indicated that substrate channeling of proline metabolic intermediates may be a critical mechanism. One intermediate is pyrroline-5-carboxylate (P5C), which upon hydrolysis opens to glutamic semialdehyde (GSA). Recent structural and kinetic evidence indicate substrate channeling of P5C/GSA occurs in the proline catabolic pathway between the proline dehydrogenase and P5C dehydrogenase active sites of bifunctional proline utilization A (PutA). Substrate channeling in PutA is proposed to facilitate the hydrolysis of P5C to GSA which is unfavorable at physiological pH. The second intermediate, gamma-glutamyl phosphate, is part of the proline biosynthetic pathway and is extremely labile. Substrate channeling of gamma-glutamyl phosphate is thought to be necessary to protect it from bulk solvent. Because of the unfavorable equilibrium of P5C/GSA and the reactivity of gamma-glutamyl phosphate, substrate channeling likely improves the efficiency of proline metabolism. Here, we outline general strategies for testing substrate channeling and review the evidence for channeling in proline metabolism. PMID:22201749

  8. Selectivity of the imidazoline alpha-adrenoceptor agonists (oxymetazoline and cirazoline) for human cloned alpha 1-adrenoceptor subtypes.

    Science.gov (United States)

    Horie, K.; Obika, K.; Foglar, R.; Tsujimoto, G.

    1995-01-01

    1. To investigate the structure-activity relationships of alpha-adrenoceptor agonists for the alpha 1-adrenoceptor subtypes, we have compared the imidazoline class of compounds, oxymetazoline and cirazoline, with the phenethylamine, noradrenaline, in their affinities and also in their intrinsic activities in Chinese hamster ovary (CHO) cells stably expressing the cloned human alpha 1-adrenoceptor subtypes (alpha 1a-, alpha 1b-, and alpha 1d-subtypes). 2. Radioligand binding studies with [125I]-HEAT showed that cirazoline and oxymetazoline had higher affinities at alpha 1a-subtype than at alpha 1b- and alpha 1d-subtypes, while noradrenaline had higher affinity at the alpha 1d-subtype than at alpha 1a- and alpha 1b-subtypes. 3. In functional studies, cirazoline caused transients of cytosolic Ca2+ concentrations ([Ca2+]i response) in a concentration-dependent manner and developed a maximal response similar to that to noradrenaline in CHO cells expressing the alpha 1a-subtype, while it acted as a partial agonist at alpha 1b- and alpha 1d-adrenoceptors. Oxymetazoline, on the other hand, was a weak agonist at alpha 1a-adrenoceptors, and has no intrinsic activity at the other subtypes. 4. Using the phenoxybenzamine inactivation method, the relationships between receptor occupancy and noradrenaline-induced [Ca2+]i response for alpha 1a- and alpha 1d-subtypes were found to be linear, whereas it was moderately hyperbolic for the alpha 1b-subtype, indicating the absence of receptor reserves in CHO cells expressing alpha 1a- and alpha 1d-subtypes while there exists a small receptor reserve for CHO cells expressing the alpha 1b-subtype.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8564227

  9. Melt Channel Formation in Paraffin With Applications to Lava Channels

    Science.gov (United States)

    Whitehead, J. A.; Mills, C. J.

    2005-12-01

    We present the results from laboratory experiments designed to explore channel formation caused by instabilities in fluid flow, and to provide a simple experimental basis to facilitate the extension of lava channel theory. Kelemen et. al. [1995] reported on a series of experiments that explored channel formation resulting from fluid instabilities caused by the ``reactive infiltration instability'' (RII). However, the material used in portions of their experiments was undesirable because of a poorly suited rheology. Therefore, our experiments were initiated as an extension of those earlier experiments, using instead a material with more robust rheological properties. The material chosen for this series of experiments is a paraffin with a freezing temperature of 4°C, which is transparent when liquid and opaque-white when frozen. The paraffin is pumped at a constant and controlled rate into a narrow gap between two circular plates, both with a diameter of ~51cm. The gap is open along the circumference of the plates, allowing the paraffin to flow out of the gap once it reaches the edge of the plate. The upper plate is constructed of Plexiglas to allow observation of the wax below, and it has a hole in the center through which the paraffin is pumped. The lower plate is constructed of aluminum, painted black, and kept at -5°C by circulating coolant through a reservoir below the it. As the paraffin, which is kept at 20°C before being pumped into the gap, flows over the cold lower plate, it begins to freeze and eventually fills up the gap between the plates. A single channel then forms, surrounded by solid paraffin, and the liquid being pumped in is transported via this channel to the edge of the plate. This is a stable state for all but the lowest flow rates attempted and verifies the results from the earlier work exploring the RII. We conducted experiments at different flows rates from 270mL/min to <30mL/min, and recorded the dimensions of the steady state channel

  10. Anti-IL-1alpha autoantibodies in early rheumatoid arthritis

    DEFF Research Database (Denmark)

    Forslind, K; Svensson, Birte; Svenson, M

    2001-01-01

    To investigate the potential predictive value of autoantibodies against IL1-alpha (anti-IL-1alpha) in patients with early rheumatoid arthritis (RA).......To investigate the potential predictive value of autoantibodies against IL1-alpha (anti-IL-1alpha) in patients with early rheumatoid arthritis (RA)....

  11. The nitric oxide-donating pravastatin derivative, NCX 6550 [(1S-[1alpha(betaS*, deltaS*), 2alpha, 6alpha, 8beta-(R*), 8a alpha

    Science.gov (United States)

    Dever, G; Spickett, C M; Kennedy, S; Rush, C; Tennant, G; Monopoli, A; Wainwright, C L

    2007-01-01

    Statins possess anti-inflammatory effects that may contribute to their ability to slow atherogenesis, whereas nitric oxide (NO) also influences inflammatory cell adhesion. This study aimed to determine whether a novel NO-donating pravastatin derivative, NCX 6550 [(1S-[1alpha(betaS*,deltaS*),2alpha,6alpha,8beta-(R*),8a alpha

  12. ACE Strategy with Virtual Channels

    Directory of Open Access Journals (Sweden)

    T. Tichy

    2008-12-01

    Full Text Available Cochlear implant is an electronic device, which can mediate hearing sensations to profoundly deaf people. Contemporary cochlear implants are sophisticated electronic devices; however, their performance could still be improved. This paper describes an experiment we made in that direction: additional 21 virtual channels were implemented by sequential stimulation of adjacent intracochlear electrodes, and the ACE strategy with virtual channels (ACEv, Advanced Combination Encoder strategy with virtual channels for the Nucleus® 24 Cochlear Implant System was created and verified in a clinical test with four patients.

  13. Measurement of radium micro-precipitates using alpha spectrometry and total alpha counting methods

    International Nuclear Information System (INIS)

    Hosseini, T.; Fathivand, A.A.

    2004-01-01

    Background: This study consists of two parts. The first part deals with both qualitative and quantitative analysis of 226 Ra suing alpha spectrometry measurement method. In the second part, the percentage of radioactive equilibrium between 226 Radium and its daughter products were determined by alpha spectrometry and total alpha measurement system after elapsed time of 15 days from precipitation. Materials and methods: Twelve 226 Radium samples as Barium-Radium Sulfate in form of micro-precipitates on millipore and What man 42 filters were prepared. An alpha spectrometer with surface barrier detector and a total alpha measurement system consists of scintillation crystal assembly Zinc Silver were used for counting. Results: The minimum detection limit of alpha spectrometry and total alpha counting for 226 Radium measurements in samples for counting time equal to 10000 seconds, were found to be 3.7 mBq and 15.8 mBq respectively. Results from total alpha counting showed that radioactive equilibrium between 226 Radium and its daughter products reached to about 92%± 3.5, where as, in the case of alpha spectrometry radioactive equilibrium, it was destroyed due to vacuum during counting the sample. Also in case of alpha spectrometry, the optimum sample to detector distance, was found to be 0.5 centimeter. Conclusion: From this study it was concluded that micro-precipitation can be used as a proper method for sample preparation and alpha spectrometry due to its lower detection limit to measure low concentration of 224 Radium and 226 Radium in these precipitates, prepared from different samples. Besides it is not time consuming and sources can be measured immediately after sample preparation

  14. Alpha-particle fluence in radiobiological experiments.

    Science.gov (United States)

    Nikezic, Dragoslav; Yu, Kwan Ngok

    2017-03-01

    Two methods were proposed for determining alpha-particle fluence for radiobiological experiments. The first involved calculating the probabilities of hitting the target for alpha particles emitted from a source through Monte Carlo simulations, which when multiplied by the activity of the source gave the fluence at the target. The second relied on the number of chemically etched alpha-particle tracks developed on a solid-state nuclear track detector (SSNTD) that was irradiated by an alpha-particle source. The etching efficiencies (defined as percentages of latent tracks created by alpha particles from the source that could develop to become visible tracks upon chemical etching) were computed through Monte Carlo simulations, which when multiplied by the experimentally counted number of visible tracks would also give the fluence at the target. We studied alpha particles with an energy of 5.486 MeV emitted from an 241Am source, and considered the alpha-particle tracks developed on polyallyldiglycol carbonate film, which is a common SSNTD. Our results showed that the etching efficiencies were equal to one for source-film distances of from 0.6 to 3.5 cm for a circular film of radius of 1 cm, and for source-film distances of from 1 to 3 cm for circular film of radius of 2 cm. For circular film with a radius of 3 cm, the etching efficiencies never reached 1. On the other hand, the hit probability decreased monotonically with increase in the source-target distance, and fell to zero when the source-target distance was larger than the particle range in air. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  15. Cancer radioimmunotherapy with alpha-emitting nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Couturier, Olivier [INSERM U 601, Nantes (France); Place Alexis Ricordeau, Department of Nuclear Medicine, Nantes, Cedex (France); Supiot, Stephane; Degraef-Mougin, Marie; Faivre-Chauvet, Alain; Carlier, Thomas; Chatal, Jean-Francois; Davodeau, Francois; Cherel, Michel [INSERM U 601, Nantes (France)

    2005-04-01

    In lymphoid malignancies and in certain solid cancers such as medullary thyroid carcinoma, somewhat mixed success has been achieved when applying radioimmunotherapy (RIT) with {beta}-emitters for the treatment of refractory cases. The development of novel RIT with {alpha}-emitters has created new opportunities and theoretical advantages due to the high linear energy transfer (LET) and the short path length in biological tissue of {alpha}-particles. These physical properties offer the prospect of achieving selective tumoural cell killing. Thus, RIT with {alpha}-emitters appears particularly suited for the elimination of circulating single cells or cell clusters or for the treatment of micrometastases at an early stage. However, to avoid non-specific irradiation of healthy tissues, it is necessary to identify accessible tumoural targets easily and rapidly. For this purpose, a small number of {alpha}-emitters have been investigated, among which only a few have been used for in vivo preclinical studies. Another problem is the availability and cost of these radionuclides; for instance, the low cost and the development of a reliable actinium-225/bismuth-213 generator were probably determining elements in the choice of bismuth-213 in the only human trial of RIT with an {alpha}-emitter. This article reviews the literature concerning monoclonal antibodies radiolabelled with {alpha}-emitters that have been developed for possible RIT in cancer patients. The principal radio-immunoconjugates are considered, starting with physical and chemical properties of {alpha}-emitters, their mode of production, the possibilities and difficulties of labelling, in vitro studies and finally, when available, in vivo preclinical and clinical studies. (orig.)

  16. Cancer radioimmunotherapy with alpha-emitting nuclides.

    Science.gov (United States)

    Couturier, Olivier; Supiot, Stéphane; Degraef-Mougin, Marie; Faivre-Chauvet, Alain; Carlier, Thomas; Chatal, Jean-François; Davodeau, François; Cherel, Michel

    2005-05-01

    In lymphoid malignancies and in certain solid cancers such as medullary thyroid carcinoma, somewhat mixed success has been achieved when applying radioimmunotherapy (RIT) with beta-emitters for the treatment of refractory cases. The development of novel RIT with alpha-emitters has created new opportunities and theoretical advantages due to the high linear energy transfer (LET) and the short path length in biological tissue of alpha-particles. These physical properties offer the prospect of achieving selective tumoural cell killing. Thus, RIT with alpha-emitters appears particularly suited for the elimination of circulating single cells or cell clusters or for the treatment of micrometastases at an early stage. However, to avoid non-specific irradiation of healthy tissues, it is necessary to identify accessible tumoural targets easily and rapidly. For this purpose, a small number of alpha-emitters have been investigated, among which only a few have been used for in vivo preclinical studies. Another problem is the availability and cost of these radionuclides; for instance, the low cost and the development of a reliable actinium-225/bismuth-213 generator were probably determining elements in the choice of bismuth-213 in the only human trial of RIT with an alpha-emitter. This article reviews the literature concerning monoclonal antibodies radiolabelled with alpha-emitters that have been developed for possible RIT in cancer patients. The principal radio-immunoconjugates are considered, starting with physical and chemical properties of alpha-emitters, their mode of production, the possibilities and difficulties of labelling, in vitro studies and finally, when available, in vivo preclinical and clinical studies.

  17. Pharmacologic specificity of alpha-2 adrenergic receptor subtypes

    Energy Technology Data Exchange (ETDEWEB)

    Petrash, A.; Bylund, D.

    1986-03-01

    The authors have defined alpha-2 adrenergic receptor subtypes in human and rat tissues using prazosin as a subtype selective drug. Prazosin has a lower affinity (250 nM) at alpha-2A receptor and a higher affinity (5 nM) at alpha-2B receptors. In order to determine if other adrenergic drugs are selective for one or the other subtypes, the authors performed (/sup 3/H)yohimbine inhibition experiments with various adrenergic drugs in tissues containing alpha-2A, alpha-2B or both subtypes. Oxymetazoline, WB4101 and yohimbine were found to be 80-, 20- and 10-fold more potent at alpha-2A receptors than at alpha-2B receptors. Phentolamine, adazoxan, (+)- and (-)-mianserin, clonidine, (+)-butaclamol, (-)- and (+)-norepinephrine, epinephrine, dopamine and thioridazine were found to have equal affinities for the two subtypes. These results further validate the subdivision of alpha-2 adrenergic receptors into alpha-2A and alpha-2B subtypes.

  18. The modulation of vascular ATP-sensitive K+ channel function via the phosphatidylinositol 3-kinase-Akt pathway activated by phenylephrine.

    Science.gov (United States)

    Haba, Masanori; Hatakeyama, Noboru; Kinoshita, Hiroyuki; Teramae, Hiroki; Azma, Toshiharu; Hatano, Yoshio; Matsuda, Naoyuki

    2010-08-01

    The present study examined the modulator role of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway activated by the alpha-1 adrenoceptor agonist phenylephrine in ATP-sensitive K(+) channel function in intact vascular smooth muscle. We evaluated the ATP-sensitive K(+) channel function and the activity of the PI3K-Akt pathway in the rat thoracic aorta without endothelium. The PI3K inhibitor 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride (LY294002) (10(-5) M) augmented relaxation in response to the ATP-sensitive K(+) channel opener levcromakalim (10(-8) to 3 x 10(-6) M) in aortic rings contracted with phenylephrine (3 x 10(-7) M) but not with 9,11-dideoxy-11alpha,9alpha-epoxy-methanoprostaglandin F(2alpha) (U46619; 3 x 10(-8) M), although those agents induced similar contraction. ATP-sensitive K(+) channel currents induced by levcromakalim (10(-6) M) in the presence of phenylephrine (3 x 10(-7) M) were enhanced by the nonselective alpha-adrenoceptor antagonist phentolamine (10(-7) M) and LY294002 (10(-5) M). Levels of the regulatory subunits of PI3K p85-alpha and p55-gamma increased in the membrane fraction from aortas without endothelium treated with phenylephrine (3 x 10(-7) M) but not with U46619 (3 x 10(-8) M). Phenylephrine simultaneously augmented Akt phosphorylation at Ser473 and Thr308. Therefore, activation of the PI3K-Akt pathway seems to play a role in the impairment of ATP-sensitive K(+) channel function in vascular smooth muscle exposed to alpha-1 adrenergic stimuli.

  19. Sodium channels in planar lipid bilayers. Channel gating kinetics of purified sodium channels modified by batrachotoxin

    Science.gov (United States)

    1986-01-01

    Single channel currents of sodium channels purified from rat brain and reconstituted into planar lipid bilayers were recorded. The kinetics of channel gating were investigated in the presence of batrachotoxin to eliminate inactivation and an analysis was conducted on membranes with a single active channel at any given time. Channel opening is favored by depolarization and is strongly voltage dependent. Probability density analysis of dwell times in the closed and open states of the channel indicates the occurrence of one open state and several distinct closed states in the voltage (V) range-120 mV less than or equal to V less than or equal to +120 mV. For V less than or equal to 0, the transition rates between stages are exponentially dependent on the applied voltage, as described in mouse neuroblastoma cells (Huang, L. M., N. Moran, and G. Ehrenstein. 1984. Biophysical Journal. 45:313- 322). In contrast, for V greater than or equal to 0, the transition rates are virtually voltage independent. Autocorrelation analysis (Labarca, P., J. Rice, D. Fredkin, and M. Montal. 1985. Biophysical Journal. 47:469-478) shows that there is no correlation in the durations of successive open or closing events. Several kinetic schemes that are consistent with the experimental data are considered. This approach may provide information about the mechanism underlying the voltage dependence of channel activation. PMID:2426388

  20. Multi-channel Kondo necklace

    International Nuclear Information System (INIS)

    Fazekas, P.; Kee Haeyoung.

    1993-06-01

    A multi-channel generalization of Doniach's Kondo necklace model is formulated, and its phase diagram studied in the mean-field approximation. Our intention is to introduce the possible simplest model which displays some of the features expected from the overscreened Kondo lattice. The N conduction electron channels are represented by N sets of pseudospins τ J , j = 1 1,..., N which are all antiferromagnetically coupled to a periodic array of modul S = 1/2 spins. Exploiting permutation symmetry in the channel index j allows us to write down the self-consistency equation for general N. For N > 2, we find that the critical temperature is rising with increasing Kondo interaction; we interpret this effect by pointing out that the Kondo coupling creates the composite pseudospin objects which undergo an ordering transition. The relevance of our findings to the underlying fermionic multi-channel problem is discussed. (author). 33 refs, 1 fig

  1. FMCG companies specific distribution channels

    Directory of Open Access Journals (Sweden)

    Ioana Barin

    2009-12-01

    Full Text Available Distribution includes all activities undertaken by the producer, alone or in cooperation, since the end of the final finished products or services until they are in possession of consumers. The distribution consists of the following major components: distribution channels or marketing channels, which together form a distribution network; logistics o rphysical distribution. In order to effective achieve, distribution of goods requires an amount of activities and operational processes related to transit of goods from producer to consumer, the best conditions, using existing distribution channels and logistics system. One of the essential functions of a distribution is performing acts of sale, through which, with the actual movement of goods, their change of ownership takes place, that the successive transfer of ownership from producer to consumer. This is an itinerary in the economic cycle of goods, called the distribution channel.

  2. Potassium Channels in Neurofbromatosis-1

    National Research Council Canada - National Science Library

    Chen, Mingkui

    2006-01-01

    .... We were the first to investigate potential mechanisms of cognitive impairment in NF-1 at the molecular level involving potassium channels, and demonstrated a possible mechanism for the learning deficits seen in NF1...

  3. Alpha 1 B- but not alpha 1 A-adrenoceptors mediate inositol phosphate generation

    NARCIS (Netherlands)

    Michel, M. C.; Hanft, G.; Gross, G.

    1990-01-01

    We used novel highly subtype-selective antagonists to study whether alpha 1A- and/or alpha 1B-adrenoceptors mediate the stimulation of inositol phosphate generation by noradrenaline in rat cerebral cortex. Phentolamine (10 microM) and prazosin (100 nM) completely abolished the stimulated inositol

  4. Role of macrophage inflammatory protein-1 alpha (MIP-1 alpha) in acute lung injury in rats

    DEFF Research Database (Denmark)

    Shanley, T P; Schmal, H; Friedl, H P

    1995-01-01

    The role of macrophage inflammatory protein-1 alpha (MIP-1 alpha) in the pathogenesis of acute lung injury in rats after intrapulmonary deposition of IgG immune complexes or intratracheal administration of LPS has been assessed. Critical to these studies was the cloning and functional expression...

  5. Alpha-in-air monitor for continuous monitoring based on alpha to beta ratio

    International Nuclear Information System (INIS)

    Somayaji, K.S.; Venkataramani, R.; Swaminathan, N.; Pushparaja

    1997-01-01

    Measurement of long-lived alpha activity collected on a filter paper in continuous air monitoring of ambient working environment is difficult due to interference from much larger concentrations of short-lived alpha emitting daughter products of 222 Rn and 220 Rn. However, the ratio between the natural alpha and beta activity is approximately constant and this constancy of the ratio is used to discriminate against short-lived natural radioactivity in continuous air monitoring. Detection system was specially designed for the purpose of simultaneous counting of alpha and beta activity deposited on the filter paper during continuous monitoring. The activity ratios were calculated and plotted against the monitoring duration up to about six hours. Monitoring was carried out in three facilities with different ventilation conditions. Presence of any long-lived alpha contamination on the filter paper results in increase in the alpha to beta ratio. Long-lived 239 Pu contamination of about 16 DAC.h could be detected after about 45 minutes of commencement of the sampling. The experimental results using prototype units have shown that the approach of using alpha to beta activity ratio method to detect long-lived alpha activity in the presence of short-lived natural activity is satisfactory. (author)

  6. PLE CATALYZED HYDROLYZES OF ALPHA-SUBSTITUTED ALPHA-HYDROXY ESTERS - THE INFLUENCE OF THE SUBSTITUENTS

    NARCIS (Netherlands)

    MOORLAG, H; KELLOGG, RM

    1991-01-01

    The enzymatic hydrolyses of a variety of alpha-substituted mandelic and lactic esters using pig liver esterase (PLE) have been investigated. High to moderate enantioselectivity was found for various alpha-substituted mandelic esters, whereas PLE showed low to no enantioselectivity for

  7. Increased voluntary exercise in mice deficient for tumour necrosis factor-alpha and lymphotoxin-alpha.

    NARCIS (Netherlands)

    Netea, M.G.; Kullberg, B.J.; Vonk, A.G.; Verschueren, I.; Joosten, L.A.B.; Meer, J.W.M. van der

    2007-01-01

    BACKGROUND: The endogenous mediators playing a role in the sensing of fatigue and cessation of exercise are yet to be characterized. We hypothesized that proinflammatory cytokines, in particular tumour necrosis factor-alpha (TNFalpha) and lymphotoxin-alpha (LT) transmit signals leading to fatigue.

  8. Alpha-particle elastic scattering on [sup 16]O in the four [alpha]-particle model

    Energy Technology Data Exchange (ETDEWEB)

    Li Qingrun (CCAST (World Lab.), Beijing (China) Inst. of High Energy Physics, Academia Sinica, Beijing (China)); Yang Yongxu (Dept. of Physics, Guangxi Normal Univ., Guilin (China))

    1993-08-23

    A folding potential describing the alpha-particle scattering on [sup 16]O is constructed based on the four [alpha]-particle model of the nucleus [sup 16]O. This folding potential provides a good description of the experimental data covering a broad energy range. (orig.)

  9. Consistent Measurements of $\\alpha_{s}$ from Precise Oriented Event Shape Distributions

    CERN Document Server

    Abreu, P.; Adye, T.; Adzic, P.; Albrecht, Z.; Alderweireld, T.; Alekseev, G.D.; Alemany, R.; Allmendinger, T.; Allport, P.P.; Almehed, S.; Amaldi, U.; Amapane, N.; Amato, S.; Anassontzis, E.G.; Andersson, P.; Andreazza, A.; Andringa, S.; Antilogus, P.; Apel, W.D.; Arnoud, Y.; Asman, B.; Augustin, J.E.; Augustinus, A.; Baillon, P.; Bambade, P.; Barao, F.; Barbiellini, G.; Barbier, R.; Bardin, D.Yu.; Barker, G.J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.H.; Begalli, M.; Behrmann, A.; Beilliere, P.; Belokopytov, Yu.; Benekos, N.C.; Benvenuti, A.C.; Berat, C.; Berggren, M.; Bertini, D.; Bertrand, D.; Besancon, M.; Bigi, M.; Bilenky, Mikhail S.; Bizouard, M.A.; Bloch, D.; Blom, H.M.; Bonesini, M.; Bonivento, W.; Boonekamp, M.; Booth, P.S.L.; Borgland, A.W.; Borisov, G.; Bosio, C.; Botner, O.; Boudinov, E.; Bouquet, B.; Bourdarios, C.; Bowcock, T.J.V.; Boyko, I.; Bozovic, I.; Bozzo, M.; Branchini, P.; Brenke, T.; Brenner, R.A.; Bruckman, P.; Brunet, J.M.; Bugge, L.; Buran, T.; Burgsmuller, T.; Buschbeck, B.; Buschmann, P.; Cabrera, S.; Caccia, M.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Carroll, L.; Caso, C.; Castillo Gimenez, M.V.; Cattai, A.; Cavallo, F.R.; Chabaud, V.; Charpentier, P.; Chaussard, L.; Checchia, P.; Chelkov, G.A.; Chierici, R.; Chochula, P.; Chorowicz, V.; Chudoba, J.; Cieslik, K.; Collins, P.; Contri, R.; Cortina, E.; Cosme, G.; Cossutti, F.; Cowell, J.H.; Crawley, H.B.; Crennell, D.; Crepe-Renaudin, Sabine; Crosetti, G.; Cuevas Maestro, J.; Czellar, S.; Davenport, M.; Da Silva, W.; Deghorain, A.; Della Ricca, G.; Delpierre, P.; Demaria, N.; De Angelis, A.; De Boer, W.; De Clercq, C.; De Lotto, B.; De Min, A.; De Paula, L.; Dijkstra, H.; Di Ciaccio, L.; Dolbeau, J.; Doroba, K.; Dracos, M.; Drees, J.; Dris, M.; Duperrin, A.; Durand, J.D.; Eigen, G.; Ekelof, T.; Ekspong, G.; Ellert, M.; Elsing, M.; Engel, J.P.; Erzen, B.; Espirito Santo, M.C.; Fanourakis, G.; Fassouliotis, D.; Fayot, J.; Feindt, M.; Ferrari, P.; Ferrer, A.; Ferrer-Ribas, E.; Ferro, F.; Fichet, S.; Firestone, A.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fontanelli, F.; Franek, B.; Frodesen, A.G.; Fruhwirth, R.; Fulda-Quenzer, F.; Fuster, J.; Galloni, A.; Gamba, D.; Gamblin, S.; Gandelman, M.; Garcia, C.; Gaspar, C.; Gaspar, M.; Gasparini, U.; Gavillet, P.; Gazis, Evangelos; Gele, D.; Ghodbane, N.; Gil Botella, Ines; Glege, F.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Gonzalez Caballero, I.; Gopal, G.; Gorn, L.; Gracco, V.; Grahl, J.; Graziani, E.; Green, C.; Grimm, H.J.; Gris, P.; Grosdidier, G.; Grzelak, K.; Gunther, M.; Guy, J.; Hahn, F.; Hahn, S.; Haider, S.; Hallgren, A.; Hamacher, K.; Hansen, J.; Harris, F.J.; Hedberg, V.; Heising, S.; Hernandez, J.J.; Herquet, P.; Herr, H.; Hessing, T.L.; Heuser, J.M.; Higon, E.; Holmgren, S.O.; Holt, P.J.; Hoorelbeke, S.; Houlden, M.; Hrubec, J.; Huet, K.; Hughes, G.J.; Hultqvist, K.; Jackson, John Neil; Jacobsson, R.; Jalocha, P.; Janik, R.; Jarlskog, C.; Jarlskog, G.; Jarry, P.; Jean-Marie, B.; Johansson, Erik Karl; Jonsson, P.; Joram, C.; Juillot, P.; Kapusta, Frederic; Karafasoulis, K.; Katsanevas, S.; Katsoufis, E.C.; Keranen, R.; Kersevan, B.P.; Khomenko, B.A.; Khovansky, N.N.; Kiiskinen, A.; King, B.; Kinvig, A.; Kjaer, N.J.; Klapp, O.; Klein, Hansjorg; Kluit, P.; Kokkinias, P.; Koratzinos, M.; Kourkoumelis, C.; Kuznetsov, O.; Krammer, M.; Kriznic, E.; Krumshtein, Z.; Kubinec, P.; Kurowska, J.; Kurvinen, K.; Lamsa, J.W.; Lane, D.W.; Langefeld, P.; Laugier, J.P.; Lauhakangas, R.; Leder, G.; Ledroit, Fabienne; Lefebure, V.; Leinonen, L.; Leisos, A.; Leitner, R.; Lemonne, J.; Lenzen, G.; Lepeltier, V.; Lesiak, T.; Lethuillier, M.; Libby, J.; Liko, D.; Lipniacka, A.; Lippi, I.; Lorstad, B.; Loken, J.G.; Lopes, J.H.; Lopez, J.M.; Lopez-Fernandez, R.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Mahon, J.R.; Maio, A.; Malek, A.; Malmgren, T.G.M.; Maltezos, S.; Malychev, V.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Martinez-Vidal, F.; Marti i Garcia, S.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Matthiae, G.; Mazzucato, F.; Mazzucato, M.; McCubbin, M.; McKay, R.; McNulty, R.; McPherson, G.; Meroni, C.; Meyer, W.T.; Migliore, E.; Mirabito, L.; Mitaroff, W.A.; Mjornmark, U.; Moa, T.; Moch, M.; Moller, Rasmus; Monig, Klaus; Monge, M.R.; Moreau, X.; Morettini, P.; Morton, G.; Muller, U.; Munich, K.; Mulders, M.; Mulet-Marquis, C.; Muresan, R.; Murray, W.J.; Muryn, B.; Myatt, G.; Myklebust, T.; Naraghi, F.; Nassiakou, M.; Navarria, F.L.; Navas, Sergio; Nawrocki, K.; Negri, P.; Nemecek, S.; Neufeld, N.; Nicolaidou, R.; Nielsen, B.S.; Niezurawski, P.; Nikolenko, M.; Nomokonov, V.; Normand, A.; Nygren, A.; Olshevsky, A.G.; Onofre, A.; Orava, R.; Orazi, G.; Osterberg, K.; Ouraou, A.; Paganoni, M.; Paiano, S.; Pain, R.; Paiva, R.; Palacios, J.; Palka, H.; Papadopoulou, T.D.; Papageorgiou, K.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Pegoraro, M.; Peralta, L.; Pernicka, M.; Perrotta, A.; Petridou, C.; Petrolini, A.; Phillips, H.T.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Pol, M.E.; Polok, G.; Poropat, P.; Pozdnyakov, V.; Privitera, P.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Ragazzi, S.; Rahmani, H.; Ratoff, P.N.; Read, Alexander L.; Rebecchi, P.; Redaelli, Nicola Giuseppe; Regler, M.; Reid, D.; Reinhardt, R.; Renton, P.B.; Resvanis, L.K.; Richard, F.; Ridky, J.; Rinaudo, G.; Rodrigo, German; Rohne, O.; Romero, A.; Ronchese, P.; Rosenberg, E.I.; Rosinsky, P.; Roudeau, P.; Rovelli, T.; Royon, C.; Ruhlmann-Kleider, V.; Ruiz, A.; Saarikko, H.; Sacquin, Y.; Sadovsky, A.; Sajot, G.; Salt, J.; Sampsonidis, D.; Sannino, M.; Schneider, H.; Schwemling, P.; Schwering, B.; Schwickerath, U.; Schyns, M.A.E.; Scuri, Fabrizio; Seager, P.; Sedykh, Yu.; Segar, A.M.; Sekulin, R.; Shellard, R.C.; Sheridan, A.; Siebel, M.; Simard, L.; Simonetto, F.; Sisakian, A.N.; Smadja, G.; Smirnova, O.; Smith, G.R.; Sopczak, A.; Sosnowski, R.; Spassoff, T.; Spiriti, E.; Sponholz, P.; Squarcia, S.; Stanescu, C.; Stanic, S.; Stevenson, K.; Stocchi, A.; Strauss, J.; Strub, R.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Tabarelli, T.; Tegenfeldt, F.; Terranova, F.; Thomas, J.; Timmermans, Jan; Tinti, N.; Tkachev, L.G.; Todorova, S.; Tomaradze, A.; Tome, B.; Tonazzo, A.; Tortora, L.; Transtromer, G.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Tsirou, A.; Turluer, M.L.; Tyapkin, I.A.; Tzamarias, S.; Ullaland, O.; Valenti, G.; Vallazza, E.; Vander Velde, C.; Van Apeldoorn, G.W.; Van Dam, Piet; Van Doninck, Walter; Van Eldik, J.; Van Lysebetten, A.; Van Remortel, N.; Van Vulpen, I.; Vassilopoulos, N.; Vegni, G.; Ventura, L.; Venus, W.; Verbeure, F.; Verlato, M.; Vertogradov, L.S.; Verzi, V.; Vilanova, D.; Vitale, L.; Vodopianov, A.S.; Vollmer, C.; Voulgaris, G.; Vrba, V.; Wahlen, H.; Walck, C.; Weiser, C.; Wicke, D.; Wickens, J.H.; Wilkinson, G.R.; Winter, M.; Witek, M.; Wolf, G.; Yi, J.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zevgolatakos, E.; Zimine, N.I.; Zucchelli, G.C.; Zumerle, G.

    2000-01-01

    An updated analysis using about 1.5 million events recorded at $\\sqrt{s} =M_Z$ with the DELPHI detector in 1994 is presented. Eighteen infrared and collinear safe event shape observables are measured as a function of the polar angle of the thrust axis. The data are compared to theoretical calculations in${\\cal O} (\\alpha_s^2)$ including the event orientation. A combined fit of $\\alpha_s$ and of the renormalization scale $x_{\\mu}$ in $\\cal O(\\alpha_s^2$)yields an excellent description of the high statistics data. The weighted average from 18 observables including quark mass effects and correlations is $\\alpha_s(M_Z^2) = 0.1174 \\pm 0.0026$. The final result, derived from the jet cone energy fraction, the observable with the smallest theoretical and experimental uncertainty, is $\\alpha_s(M_Z^2) = =0:1180 0:0006(exp:) 0:0013(hadr:) 0:0008(scale) 0:0007(mass). Further studies include an s determination using theoretical predictions in the next-to-leading log approximation (NLLA), matched NLLA and O(\\alpha^{2}_{s})...

  10. Computational Structural Pharmacology and Toxicology of Voltage-Gated Sodium Channels.

    Science.gov (United States)

    Zhorov, B S; Tikhonov, D B

    2016-01-01

    Voltage-gated sodium channels are targets for many toxins and medically important drugs. Despite decades of intensive studies in industry and academia, atomic mechanisms of action are still not completely understood. The major cause is a lack of high-resolution structures of eukaryotic channels and their complexes with ligands. In these circumstances a useful approach is homology modeling that employs as templates X-ray structures of potassium channels and prokaryotic sodium channels. On one hand, due to inherent limitations of this approach, results should be treated with caution. In particular, models should be tested against relevant experimental data. On the other hand, docking of drugs and toxins in homology models provides a unique possibility to integrate diverse experimental data provided by mutational analysis, electrophysiology, and studies of structure-activity relations. Here we describe how homology modeling advanced our understanding of mechanisms of several classes of ligands. These include tetrodotoxins and mu-conotoxins that block the outer pore, local anesthetics that block of the inner pore, batrachotoxin that binds in the inner pore but, paradoxically, activates the channel, pyrethroid insecticides that activate the channel by binding at lipid-exposed repeat interfaces, and scorpion alpha and beta-toxins, which bind between the pore and voltage-sensing domains and modify the channel gating. We emphasize importance of experimental data for elaborating the models. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Marketing channel behaviour and performance

    OpenAIRE

    Duarte, Margarida

    2000-01-01

    Thesis submitted to University of Manchester for the degree of Doctor of Philosophy in the Faculty of Business Administration. A major aim of this study is to offer a relatively comprehensive picture of marketing channel behaviour and performance. Given the statistical difficulties in testing a very large, comprehensive model to achieve this aim, two separate but overlapping models are proposed. One model specifically addresses behaviour in marketing channels, while the other integrates k...

  12. Learning the MMSE Channel Estimator

    OpenAIRE

    Neumann, David; Wiese, Thomas; Utschick, Wolfgang

    2017-01-01

    We present a method for estimating conditionally Gaussian random vectors with random covariance matrices, which uses techniques from the field of machine learning. Such models are typical in communication systems, where the covariance matrix of the channel vector depends on random parameters, e.g., angles of propagation paths. If the covariance matrices exhibit certain Toeplitz and shift-invariance structures, the complexity of the MMSE channel estimator can be reduced to O(M log M) floating ...

  13. Eight channel telephone telemetry system

    Science.gov (United States)

    Smith, R. E.

    1973-01-01

    A portable, indirectly coupled telephone system is reported which transmits/to a central receiving site eight channels of EEG data of sufficient fidelity for screening and/or limited diagnostic use. The system requires no electrical connection to the telephone at the transmitter or at the receiver and is compatible with common EEG recording practice for real-time recording. It accepts 8 input channels simultaneously with one telephone transmitter and one telephone receiver operates from standard power sources.

  14. Activity monitoring of alpha-bearing wastes

    International Nuclear Information System (INIS)

    Birkhoff, G.; Bondar, L.

    1980-01-01

    The paper aims at the survey on the actual situation in activity monitoring of alpha-bearing wastes. Homogeneous materials such as liquid-, gaseous- and homogeneous solid wastes are amenable to destructive analyses of representative samples. Available destructive analyses methods are sensitive and precise enough to cope with all requirements in alpha-waste monitoring. The more difficult problems are encountered with alpha-contaminated solids, when representative sampling is not practicable. Non-destructive analysis techniques are applied for monitoring this category of solid wastes. The techniques for nondestructive analysis of alpha-bearing wastes are based on the detection of gamma and/or neutron-emission of actinides. Principles and a theory of non-destructive radiometric assay of plutonium contaminated solid waste streams are explained. Guidelines for the calibration of instruments and interpretation of experimental data are given. Current theoretical and experimental development work in this problem area is reviewed. Evaluations concerning capabilities and limitations of monitoring systems for alpha-bearing solid wastes are very complex and out of the scope of this paper

  15. Role of Frontal Alpha Oscillations in Creativity

    Science.gov (United States)

    Lustenberger, Caroline; Boyle, Michael R.; Foulser, A. Alban; Mellin, Juliann M.; Fröhlich, Flavio

    2015-01-01

    Creativity, the ability to produce innovative ideas, is a key higher-order cognitive function that is poorly understood. At the level of macroscopic cortical network dynamics, recent EEG data suggests that cortical oscillations in the alpha frequency band (8 – 12 Hz) are correlated with creative thinking. However, whether alpha oscillations play a fundamental role in creativity has remained unknown. Here we show that creativity is increased by enhancing alpha power using 10 Hz transcranial alternating current stimulation (10Hz-tACS) of the frontal cortex. In a study of 20 healthy participants with a randomized, balanced cross-over design, we found a significant improvement of 7.4% in the Creativity Index measured by the Torrance Test of Creative Thinking, a comprehensive and most frequently used assay of creative potential and strengths. In a second similar study with 20 subjects, 40Hz-tACS was used in instead of 10Hz-tACS to rule out a general “electrical stimulation” effect. No significant change in the Creativity Index was found for such frontal gamma stimulation. Our results suggest that alpha activity in frontal brain areas is selectively involved in creativity; this enhancement represents the first demonstration of specific neuronal dynamics that drive creativity and can be modulated by non-invasive brain stimulation. Our findings agree with the model that alpha recruitment increases with internal processing demands and is involved in inhibitory top-down control, which is an important requirement for creative ideation. PMID:25913062

  16. Evidence that 17alpha-estradiol is biologically active in the uterine tissue: Antiuterotonic and antiuterotrophic action

    Directory of Open Access Journals (Sweden)

    Navarrete Erika

    2005-07-01

    -estradiol-induced relaxation and calcium contractions in depolarized tissues were markedly prevented by 17alpha-estradiol, implying a reduction of extracellular calcium influx through voltage-operated calcium channels (VOCCs. Uterotrophic assay detected significant increase in uterine weight using 17alpha-estradiol, which was significantly minor as compared with 17beta-estradiol. 17alpha-Estradiol, at all doses ratios, significantly antagonized the hypertrophic response of 17beta-estradiol. Conclusion 17alpha-Estradiol induces a relaxing effect, which may be independent of the classical estrogen receptor, nongenomic action, apparently mediated by inactivation of VOCCs. 17alpha-Estradiol is also a weak estrogen agonist (uterotrophic response; likewise, 17alpha-estradiol may act as an antiestrogen (antiuterotrophic response. The overall data document a nongenomic relaxing action and a novel antiestrogenic action of 17alpha-estradiol, which are relevant in estrogen-mediated uterine physiology.

  17. Electrophysiological characterisation of KCNQ channel modulators

    DEFF Research Database (Denmark)

    Schrøder, R.L

    Potassium (K+) ion channels are ubiquitously expressed in mammalian cells, and each channel serves a precise physiological role due to its specific biophysical characteristics and expression pattern. A few K+ channels are targets for certain drugs, and in this thesis it is suggested that the KCNQ K......+ channels may be targets for neuroprotective, anti-epileptic and anti-nociceptive compounds. The importance of these channels is underscored by the fact that four out of five KCNQ channel subtypes are involved in severe human diseases. However, the pharmacology of the KCNQ channels is yet poorly understood...... as these channels were identified only recently. Therefore, there is a need for understanding the biophysical behavior and pharmacology of these ion channels. KCNQ channels belong to the group of voltage-activated K+ channels. The subfamily consists of KCNQ1-5, which is primarily expressed in the CNS, heart, ear...

  18. Purification and characterization of alpha-amylase from rat pancreatic acinar carcinoma. Comparison with pancreatic alpha-amylase.

    OpenAIRE

    Reddy, M K; Heda, G D; Reddy, J K

    1987-01-01

    alpha-Amylase was purified to apparent homogeneity from normal pancreas and a transplantable pancreatic acinar carcinoma of the rat by affinity chromatography on alpha-glucohydrolase inhibitor (alpha-GHI) bound to aminohexyl-Sepharose 4B. Recovery was 95-100% for both pancreas and tumour alpha-amylases. They were monomeric proteins, with Mr approx. 54000 on SDS/polyacrylamide-gel electrophoresis. Isoelectric focusing of both normal and tumour alpha-amylases resolved each into two major isoenz...

  19. Hydraulic study of parallel channels coupled to recirculation loops

    International Nuclear Information System (INIS)

    Campos G, R. M.; Cecenas F, M.

    2009-10-01

    In this work is integrated a model of recirculation loops that allows to characterize each loop for separate and with which is possible to analyze events as shot of recirculation bombs or its transfer of high to low speed. The recirculation pattern is integrated to a model of 36 channels in parallel that represents the core of a BWR. Because the core reactor is conformed by fuel assemblies physically prepared in a parallel arrangement, it is natural to obtain a parallel application of complete pattern, where are have 36 channels tasks more other two tasks that calculates recirculation and punctual kinetics, respectively. As initial test of system, which even it is found in development, was analyzed a discharge of both recirculation pumps. In this test transitory it is only verified the hydraulic behavior, the power is imposed artificially as frontier condition that is function of flow in the calculated core by the recirculation pattern. The pattern of thermal hydraulics channel and the recirculation loops are programmed in language C, the neutronic pattern is programmed in Fortran 77. For the simulations was used a work station Alpha Station DS20E with operative system Unix and the communication system Parallel Virtual Machine, that allows to a heterogeneous collection of computers in net to work like a virtual computer in parallel. (Author)

  20. Opposing actions of the progesterone metabolites, 5alpha-dihydroprogesterone (5alphaP) and 3alpha-dihydroprogesterone (3alphaHP) on mitosis, apoptosis, and expression of Bcl-2, Bax and p21 in human breast cell lines.

    Science.gov (United States)

    Wiebe, John P; Beausoleil, Michel; Zhang, Guihua; Cialacu, Valentin

    2010-01-01

    Previous studies have shown that breast tissues and breast cell lines convert progesterone (P) to 5alpha-dihydroprogesterone (5alphaP) and 3alpha-dihydroprogesterone (3alphaHP) and that 3alphaHP suppresses, whereas 5alphaP promotes, cell proliferation and detachment. The objectives of the current studies were to determine if the 5alphaP- and 3alphaHP-induced changes in cell numbers are due to altered rates of mitosis and/or apoptosis, and if 3alphaHP and 5alphaP act on tumorigenic and non-tumorigenic cells, regardless of estrogen (E) and P receptor status. The studies were conducted on tumorigenic (MCF-7, MDA-MB-231, T47D) and non-tumorigenic (MCF-10A) human breast cell lines, employing several methods to assess the effects of the hormones on cell proliferation, mitosis, apoptosis and expression of Bcl-2, Bax and p21. In all four cell lines, 5alphaP increased, whereas 3alphaHP decreased cell numbers, [(3)H]thymidine uptake and mitotic index. Apoptosis was stimulated by 3alphaHP and suppressed by 5alphaP. 5alphaP resulted in increases in Bcl-2/Bax ratio, indicating decreased apoptosis; 3alphaHP resulted in decreases in Bcl-2/Bax ratio, indicating increased apoptosis. The effects of either 3alphaHP or 5alphaP on cell numbers, [(3)H]thymidine uptake, mitosis, apoptosis, and Bcl-2/Bax ratio, were abrogated when cells were treated simultaneously with both hormones. The expression of p21 was increased by 3alphaHP, and was unaffected by 5alphaP. The results provide the first evidence that 5alphaP stimulates mitosis and suppresses apoptosis, whereas 3alphaHP inhibits mitosis and stimulates apoptosis. The opposing effects of 5alphaP and 3alphaHP were observed in all four breast cell lines examined and the data suggest that all breast cancers (estrogen-responsive and unresponsive) might be suppressed by blocking 5alphaP formation and/or increasing 3alphaHP. The findings further support the hypothesis that progesterone metabolites are key regulatory hormones and that changes

  1. Low energy alphas in the drift detector

    International Nuclear Information System (INIS)

    Snowden-Ifft, D.P.; Lawson, T.; Spooner, N.J.C.; Villaume, N.

    2004-01-01

    The Directional Recoil Identification From Tracks project is a US-UK endeavor to build and operate a low pressure negative ion TPC (NITPC) to search for weakly interacting massive particles (WIMPs) thought to make up the dark matter in our Galaxy. Low energy (∼10 keV) alpha events from U and Th decays within the walls and wires of the detector can enter the active volume of the detector and be confused for WIMP interactions. This paper presents data on and a model of low energy alphas in a NITPC operated at 40 Torr CS 2 with the aim of understanding and removing this potentially serious background. A comparison of the data to this model reveals good agreement with range predictions of SRIM2000 and allows us to calculate the energy dissipation per ion pair, W=19.0±0.5 eV for low energy alphas in CS 2

  2. Liver replacement for alpha1-antitrypsin deficiency

    Science.gov (United States)

    Putnam, Charles W.; Porter, Kendrick A.; Peters, Robert L.; Ashcavai, Mary; Redeker, Allan G.; Starzl, Thomas E.

    2010-01-01

    A 16-year-old girl with advanced cirrhosis and severe alpha1-antitrypsin deficiency of the homozygous PiZZ phenotype was treated by orthotopic liver transplantation. After replacement of the liver with a homograft from a donor with the normal PiMM phenotype, the alpha1-antitrypsin concentration in the recipient’s serum rose to normal; it had the PiMM phenotype. Two and a third years later, chronic rejection necessitated retransplantation. Insertion of a homograft from a heterozygous PiMZ donar was followed by the identification of that phenotype in the recipient’s serum. Neither liver graft developed the alpha1-antitrypsin glycoprotein deposits seen with the deficiency state. These observations confirm that this hepatic- based inborn error metabolism is metabolically cured by liver replacement. PMID:320694

  3. NALCN ion channels have alternative selectivity filters resembling calcium channels or sodium channels.

    Directory of Open Access Journals (Sweden)

    Adriano Senatore

    Full Text Available NALCN is a member of the family of ion channels with four homologous, repeat domains that include voltage-gated calcium and sodium channels. NALCN is a highly conserved gene from simple, extant multicellular organisms without nervous systems such as sponges and placozoans and mostly remains a single gene compared to the calcium and sodium channels which diversified into twenty genes in humans. The single NALCN gene has alternatively-spliced exons at exons 15 or exon 31 that splices in novel selectivity filter residues that resemble calcium channels (EEEE or sodium channels (EKEE or EEKE. NALCN channels with alternative calcium, (EEEE and sodium, (EKEE or EEKE -selective pores are conserved in simple bilaterally symmetrical animals like flatworms to non-chordate deuterostomes. The single NALCN gene is limited as a sodium channel with a lysine (K-containing pore in vertebrates, but originally NALCN was a calcium-like channel, and evolved to operate as both a calcium channel and sodium channel for different roles in many invertebrates. Expression patterns of NALCN-EKEE in pond snail, Lymnaea stagnalis suggest roles for NALCN in secretion, with an abundant expression in brain, and an up-regulation in secretory organs of sexually-mature adults such as albumen gland and prostate. NALCN-EEEE is equally abundant as NALCN-EKEE in snails, but is greater expressed in heart and other muscle tissue, and 50% less expressed in the brain than NALCN-EKEE. Transfected snail NALCN-EEEE and NALCN-EKEE channel isoforms express in HEK-293T cells. We were not able to distinguish potential NALCN currents from background, non-selective leak conductances in HEK293T cells. Native leak currents without expressing NALCN genes in HEK-293T cells are NMDG(+ impermeant and blockable with 10 µM Gd(3+ ions and are indistinguishable from the hallmark currents ascribed to mammalian NALCN currents expressed in vitro by Lu et al. in Cell. 2007 Apr 20;129(2:371-83.

  4. Advances in alpha air monitoring instrumentation

    International Nuclear Information System (INIS)

    Valentine, A.M.

    1979-01-01

    Early detection of airborne radioactive material is important for effective protection of workers, particularly at facilities handling high toxicity alpha-emitting radionuclides such as 238 Pu and 239 Pu. Variable levels of ever present and naturally occurring alpha-emitting radon daughters made gross alpha air monitoring systems unreliable for live-time monitoring of airborne plutonium. Hence, good live-time monitoring was not possible until an improved alpha air monitoring instrument capable of monitoring select plutonium radionuclides of concern was developed and marketed by nuclear instrumentation companies in the USA during the late 1960s and early 1970s. This monitoring instrument utilized a solid-state silicon-diffused junction type of detector and pulse-height analyser system to achieve a radon-daughter rejection capability. This rejection capability has resulted in an improved sensitivity for specific alpha-emitting radionuclides such as 238 Pu, 239 Pu and 241 Am. Current models of this instrument are capable of detecting 40 dis/min (0.65 Bq) of plutonium alpha activity. This activity is about equal to the integrated activity workers would be exposed to if they worked for eight hours in an airborne concentration equal to the maximum permissible concentration for transportable 239 Pu. The Los Alamos Scientific Laboratory began using these instruments in its plutonium research laboratories when they became available in the early 1970s. Approximately 300 are currently in service, and their use has resulted in much improved protection of plutonium workers because accidental airborne releases can now be detected soon after they occur. General design features of these instruments are discussed together with actual operational experience and field calibration procedures. (author)

  5. Doppler spectroscopy and D-alpha emission diagnostics for the C-2 FRC plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Deepak K.; Paganini, E.; Bonelli, L.; Deng, B. H.; Gornostaeva, O.; Hayashi, R.; Knapp, K.; McKenzie, M.; Pousa-Hijos, R.; Primavera, S.; Schroeder, J.; Tuszewski, M. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); Balvis, A.; Giammanco, F.; Marsili, P. [Department of Physics, University of Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy)

    2010-10-15

    Two Doppler spectroscopy diagnostics with complementary capabilities are developed to measure the ion temperatures and velocities of FRC plasmas in the C-2 device. First, the multichord ion doppler diagnostic can simultaneously measure 15 chords of the plasma using an image intensified camera. Second, a single-chord fast-response ion Doppler diagnostic provides much higher faster time response by using a 16-channel photo-multiplier tube array. To study the neutral density of deuterium under different wall and plasma conditions, a highly sensitive eight-channel D-alpha diagnostic has been developed and calibrated for absolute radiance measurements. These spectroscopic diagnostics capabilities, combined with other plasma diagnostics, are helping to understand and improve the field reversed configuration plasmas in the C-2 device.

  6. Parallel Genetic Algorithm for Alpha Spectra Fitting

    Science.gov (United States)

    García-Orellana, Carlos J.; Rubio-Montero, Pilar; González-Velasco, Horacio

    2005-01-01

    We present a performance study of alpha-particle spectra fitting using parallel Genetic Algorithm (GA). The method uses a two-step approach. In the first step we run parallel GA to find an initial solution for the second step, in which we use Levenberg-Marquardt (LM) method for a precise final fit. GA is a high resources-demanding method, so we use a Beowulf cluster for parallel simulation. The relationship between simulation time (and parallel efficiency) and processors number is studied using several alpha spectra, with the aim of obtaining a method to estimate the optimal processors number that must be used in a simulation.

  7. Enteric alpha defensins in norm and pathology

    Directory of Open Access Journals (Sweden)

    Lisitsyn Nikolai A

    2012-01-01

    Full Text Available Abstract Microbes living in the mammalian gut exist in constant contact with immunity system that prevents infection and maintains homeostasis. Enteric alpha defensins play an important role in regulation of bacterial colonization of the gut, as well as in activation of pro- and anti-inflammatory responses of the adaptive immune system cells in lamina propria. This review summarizes currently available data on functions of mammalian enteric alpha defensins in the immune defense and changes in their secretion in intestinal inflammatory diseases and cancer.

  8. Clustering of Lyman-Alpha Emitters galaxies

    Science.gov (United States)

    Francke, Harold

    2009-06-01

    Galaxy clustering properties have been studied for decades to constrain cosmological parameters and have today, with large datasets of high-redshift sources piling up, become a powerful tool to discriminate and characterize primeval galaxies. In the last years, several Lyman-Alpha Emitter (LAE) galaxy samples have been gathered, which are big, uniform and compact enough to allow clustering analysis. Here we present a summary of the discussion session on the clustering properties of LAEs at the "Understanding Lyman-Alpha Emitters" conference.

  9. Diffusion of cobalt in alpha zirconium

    International Nuclear Information System (INIS)

    Ghosh, U.; Pruthi, D.D.; Anand, M.S.

    1979-01-01

    The diffusion of 60 Co in alpha zirconium has been studied in the temperature range of 873-1123 K using the sectioning technique. The diffusion parameters obey the following Arrhenius equation:- D = (1.132 +- 0.22)10 -4 exp((-136.43 +- 3.50 KJ)/RT)m 2 s -1 . The diffusivity in this phase is as high as that observed in β-phase. It is also about five orders of magnitude higher when compared to the self diffusion values. The high diffusivity of cobalt in alpha zirconium has been explained on the basis of an interstitial mechanism. (auth.)

  10. Radiological hazards of alpha-contaminated waste

    International Nuclear Information System (INIS)

    Rodgers, J.C.

    1982-01-01

    The radiological hazards of alpha-contaminated wastes are discussed in this overview in terms of two components of hazard: radiobiological hazard, and radioecological hazard. Radiobiological hazard refers to human uptake of alpha-emitters by inhalation and ingestion, and the resultant dose to critical organs of the body. Radioecological hazard refers to the processes of release from buried wastes, transport in the environment, and translocation to man through the food chain. Besides detailing the sources and magnitude of hazards, this brief review identifies the uncertainties in their estimation, and implications for the regulatory process

  11. The murine alpha B-crystallin/small heat shock protein enhancer: identification of alpha BE-1, alpha BE-2, alpha BE-3, and MRF control elements.

    OpenAIRE

    Gopal-Srivastava, R; Piatigorsky, J

    1993-01-01

    The murine alpha B-crystallin gene (a member of the small heat shock protein family) is expressed constitutively at high levels in the lens and at lower levels in many other tissues, including skeletal muscle. We have previously used the herpes simplex virus thymidine kinase promoter fused to the human growth hormone gene to identify an alpha B-crystallin enhancer at positions -427 to -259 that has high activity in muscle and low activity in lens cell lines. In the study reported here, we per...

  12. Fan-less long range alpha detector

    Science.gov (United States)

    MacArthur, Duncan W.; Bounds, John A.

    1994-01-01

    A fan-less long range alpha detector which operates by using an electrical field between a signal plane and the surface or substance to be monitored for air ions created by collisions with alpha radiation. Without a fan, the detector can operate without the possibility of spreading dust and potential contamination into the atmosphere. A guard plane between the signal plane and the electrically conductive enclosure and maintained at the same voltage as the signal plane, reduces leakage currents. The detector can easily monitor soil, or other solid or liquid surfaces.

  13. Planar channeling in superlattices: Theory

    International Nuclear Information System (INIS)

    Ellison, J.A.; Picraux, S.T.; Allen, W.R.; Chu, W.K.

    1988-01-01

    The well-known continuum model theory for planar channeled energetic particles in perfect crystals is extended to layered crystalline structures and applied to superlattices. In a strained-layer structure, the planar channels with normals which are not perpendicular to the growth direction change their direction at each interface, and this dramatically influences the channeling behavior. The governing equation of motion for a planar channeled ion in a strained-layer superlattice with equal layer thicknesses is a one degree of freedom nonlinear oscillator which is periodically forced with a sequence of δ functions. These δ functions, which are of equal spacing and amplitude with alternating sign, represent the tilts at each of the interfaces. Thus upon matching an effective channeled particle wavelength, corresponding to a natural period of the nonlinear oscillator, to the period of the strained-layer superlattice, corresponding to the periodic forcing, strong resonance effects are expected. The condition of one effective wavelength per period corresponds to a rapid dechanneling at a well-defined depth (catastrophic dechanneling), whereas two wavelengths per period corresponds to no enhanced dechanneling after the first one or two layers (resonance channeling). A phase plane analysis is used to characterize the channeled particle motion. Detailed calculations using the Moliere continuum potential are compared with our previously described modified harmonic model, and new results are presented for the phase plane evolution, as well as the dechanneling as a function of depth, incident angle, energy, and layer thickness. General scaling laws are developed and nearly universal curves are obtained for the dechanneling versus depth under catastrophic dechanneling

  14. Recoil-alpha-fission and recoil-alpha-alpha-fission events observed in the reaction Ca-48 + Am-243

    NARCIS (Netherlands)

    Forsberg, U.; Rudolph, D.; Andersson, L. -L.; Nitto, A. Di; Düllmann, Ch E.; Gates, J. M.; Golubev, P.; Gregorich, K. E.; Gross, C. J.; Herzberg, R. -D.; Hessberger, F. P.; Khuyagbaatar, J.; Kratz, J. V.; Rykaczewski, K.; Sarmiento, L. G.; Schädel, M.; Yakushev, A.; Åberg, S.; Ackermann, D.; Block, M.; Brand, H.; Carlsson, B. G.; Cox, D.; Derkx, X.; Dobaczewski, J.; Eberhardt, K.; Even, J.; Fahlander, C.; Gerl, J.; Jäger, E.; Kindler, B.; Krier, J.; Kojouharov, I.; Kurz, N.; Lommel, B.; Mistry, A.; Mokry, C.; Nazarewicz, W.; Nitsche, H.; Omtvedt, J. P.; Papadakis, P.; Ragnarsson, I.; Runke, J.; Schaffner, H.; Schausten, B.; Shi, Y.; Thörle-Pospiech, P.; Torres, T.; Traut, T.; Trautmann, N.; Türler, A.; Ward, A.; Ward, D. E.; Wiehl, N.

    2016-01-01

    Products of the fusion-evaporation reaction Ca-48 + Am-243 were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum f\\"ur Schwerionenforschung. Amongst the detected thirty correlated alpha-decay chains associated with the production of element Z=115, two

  15. Alpha 1-adrenoceptor subtypes in the rat ventricular muscle.

    Science.gov (United States)

    Kinami, J; Tsuchihashi, H; Baba, S; Mano, F; Maruyama, K; Nagatomo, T

    1992-02-01

    Scatchard analyses of [3H]prazosin binding in rat ventricular muscle membranes showed biphasic curves, which identified alpha 1High- and alpha 1Low-affinity sites. The alpha 1High-affinity site was completely inhibited by 1 microM phenoxybenzamine. The displacement potencies of alpha 1-adrenergic antagonists were characterized by [3H]prazosin binding to alpha 1High- and alpha 1Low-affinity sites in the absence and presence of 1 microM phenoxybenzamine. The affinities of most chemicals for alpha 1Low-affinity sites were significantly lower than those for alpha 1High-affinity sites, but WB-4101 (2-(2,6-dimethoxy-phenoxyethyl)aminomethyl-1,4-benzodioxane), arotinolol, cinanserin, nifedipine, and p-aminoclonidine had the same affinities for both alpha 1Low- and alpha 1High-affinity sites. These results show that two alpha 1-adrenoceptor subtypes, alpha 1High- and alpha 1Low-affinity, are present in the rat heart, and that there are physical variations in alpha 1-adrenoceptor binding sites, based on their selectivity to antagonists.

  16. Volume of the space of qubit-qubit channels and state transformations under random quantum channels

    OpenAIRE

    Lovas, Attila; Andai, Attila

    2017-01-01

    The simplest building blocks for quantum computations are the qubit-qubit quantum channels. In this paper, we analyze the structure of these channels via their Choi representation. The restriction of a quantum channel to the space of classical states (i.e. probability distributions) is called the underlying classical channel. The structure of quantum channels over a fixed classical channel is studied, the volume of general and unital qubit channels with respect to the Lebesgue measure is comp...

  17. Six HLA-D region alpha-chain genes on human chromosome 6: polymorphisms and associations of DC alpha-related sequences with DR types.

    OpenAIRE

    Spielman, R S; Lee, J; Bodmer, W F; Bodmer, J G; Trowsdale, J

    1984-01-01

    Analysis of cosmid clones containing genes related to the HLA-DR alpha chain calls for at least six HLA-D region alpha-chain coding sequences in man; namely, DR alpha, DC alpha, DX alpha (very closely related to DC alpha), SB alpha 1, SB alpha 2 (two closely linked genes on the same cosmid clones), and DZ alpha. The first four genes have been described previously. SB alpha 2 and DZ alpha are recently identified genes, characterized by their unique and, from a limited study, nonpolymorphic ban...

  18. 47 CFR 76.57 - Channel positioning.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Channel positioning. 76.57 Section 76.57... CABLE TELEVISION SERVICE Carriage of Television Broadcast Signals § 76.57 Channel positioning. (a) At... choice of channel position when it requests carriage. Channel positioning requests from local commercial...

  19. Lithofacies characterization and channel development in the ...

    African Journals Online (AJOL)

    ... and multistory channel complex. The different stages of channel development can be considered in terms of low efficiency and high efficiency flows, which are related to slope equilibrium. Keywords: Outcrop, slope, channel development, channel architecture, process model, lowstand. Journal of Mining and Geology Vol.

  20. Information transfer through quantum channels

    International Nuclear Information System (INIS)

    Kretschmann, D.

    2007-01-01

    This PhD thesis represents work done between Aug. 2003 and Dec. 2006 in Reinhard F. Werner's quantum information theory group at Technische Universitaet Braunschweig, and Artur Ekert's Centre for Quantum Computation at the University of Cambridge. My thesis falls into the field of abstract quantum information theory. This work investigates both fundamental properties of quantum channels and their asymptotic capacities for classical as well as quantum information transfer. Stinespring's theorem is the basic structure theorem for quantum channels. It implies that every quantum channel can be represented as a unitary evolution on an enlarged system. In Ch. 3 we present a continuity theorem for Stinespring's representation: two quantum channels are similar if and only if it is possible to find unitary implementations that are likewise similar, with dimension-independent norm bounds. The continuity theorem allows to derive a formulation of the information-disturbance tradeoff in terms of quantum channels, and a continuity estimate for the no-broadcasting principle. In Ch. 4 we then apply the continuity theorem to give a strengthened no-go proof for quantum bit commitment, an important cryptographic primitive. This result also provides a natural characterization of those protocols that fall outside the standard setting of unconditional security, and thus may allow secure bit commitment. We present a new such protocol whose security relies on decoherence in the receiver's lab. Ch. 5 reviews the capacities of quantum channels for the transfer of both classical and quantum information, and investigates several variations in the notion of channel capacity. Memory effects are then investigated in detail in Ch. 6. We advertise a model which is sufficiently general to encompass all causal automata: every quantum process in which the outputs up to any given time t do not depend on the inputs at times t'>t can be represented as a concatenated memory channel. We then explain how

  1. Information transfer through quantum channels

    Energy Technology Data Exchange (ETDEWEB)

    Kretschmann, D.

    2007-03-12

    This PhD thesis represents work done between Aug. 2003 and Dec. 2006 in Reinhard F. Werner's quantum information theory group at Technische Universitaet Braunschweig, and Artur Ekert's Centre for Quantum Computation at the University of Cambridge. My thesis falls into the field of abstract quantum information theory. This work investigates both fundamental properties of quantum channels and their asymptotic capacities for classical as well as quantum information transfer. Stinespring's theorem is the basic structure theorem for quantum channels. It implies that every quantum channel can be represented as a unitary evolution on an enlarged system. In Ch. 3 we present a continuity theorem for Stinespring's representation: two quantum channels are similar if and only if it is possible to find unitary implementations that are likewise similar, with dimension-independent norm bounds. The continuity theorem allows to derive a formulation of the information-disturbance tradeoff in terms of quantum channels, and a continuity estimate for the no-broadcasting principle. In Ch. 4 we then apply the continuity theorem to give a strengthened no-go proof for quantum bit commitment, an important cryptographic primitive. This result also provides a natural characterization of those protocols that fall outside the standard setting of unconditional security, and thus may allow secure bit commitment. We present a new such protocol whose security relies on decoherence in the receiver's lab. Ch. 5 reviews the capacities of quantum channels for the transfer of both classical and quantum information, and investigates several variations in the notion of channel capacity. Memory effects are then investigated in detail in Ch. 6. We advertise a model which is sufficiently general to encompass all causal automata: every quantum process in which the outputs up to any given time t do not depend on the inputs at times t'>t can be represented as a concatenated memory

  2. Alpha band cortico-muscular coherence occurs in healthy individuals during mechanically-induced tremor.

    Science.gov (United States)

    Budini, Francesco; McManus, Lara M; Berchicci, Marika; Menotti, Federica; Macaluso, Andrea; Di Russo, Francesco; Lowery, Madeleine M; De Vito, Giuseppe

    2014-01-01

    The present work aimed at investigating the effects of mechanically amplified tremor on cortico-muscular coherence (CMC) in the alpha band. The study of CMC in this specific band is of particular interest because this coherence is usually absent in healthy individuals and it is an aberrant feature in patients affected by pathological tremors; understanding its mechanisms is therefore important. Thirteen healthy volunteers (23±4 years) performed elbow flexor sustained contractions both against a spring load and in isometric conditions at 20% of maximal voluntary isometric contraction (MVC). Spring stiffness was selected to induce instability in the stretch reflex servo loop. 64 EEG channels, surface EMG from the biceps brachii muscle and force were simultaneously recorded. Contractions against the spring resulted in greater fluctuations of the force signal and EMG amplitude compared to isometric conditions (pspring load, CMC in the alpha band was observed in 12 out of 13 volunteers. Partial directed coherence (PDC) revealed an increased information flow in the EMG to EEG direction in the alpha band (p<.05). Therefore, coherence in the alpha band between the sensory-motor cortex and the biceps brachii muscle can be systematically induced in healthy individuals by mechanically amplifying tremor. The increased information flow in the EMG to EEG direction may reflect enhanced afferent activity from the muscle spindles. These results may contribute to the understanding of the presence of alpha band CMC in tremor related pathologies by suggesting that the origin of this phenomenon may not only be at cortical level but may also be affected by spinal circuit loops.

  3. Alpha reactivity to first names differs in subjects with high and low dream recall frequency

    Directory of Open Access Journals (Sweden)

    Perrine Marie RUBY

    2013-08-01

    Full Text Available Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption, creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF. These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG. We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names during wakefulness and sleep (intensity, 50 dB above the subject’s hearing level. Subjects were selected as High-recallers (HR, DRF = 4.4 ± 1.1 dream recalls per week and Low-recallers (LR, DRF = 0.25 ± 0.1 using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects’ quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000-1200ms during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs 14 ± 4 min. As a whole our results support the hypothesis of neurophysiological trait differences in

  4. Alpha reactivity to first names differs in subjects with high and low dream recall frequency.

    Science.gov (United States)

    Ruby, Perrine; Blochet, Camille; Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Bidet-Caulet, Aurélie

    2013-01-01

    Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000-1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high and

  5. Phenomenological Alpha-Alpha Interactions and its Application on 16O Nucleus

    International Nuclear Information System (INIS)

    Qandil, O.S.A.A.

    2013-01-01

    The thesis includes the study of alpha-alpha interactions and apply them to the nucleus of the 16 O by using Hartree-Fock method for bosons. The used potentials are Ali-Bodmer potential, Modified Woods- Saxon potential, Fish-Bone I (FB-I) and Fish-Bone II (FB-II) potential. Also, the properties of nuclear structure of 16 O nucleus are calculated such as binding energy, form factor and root mean square radius. The results we have obtained were compared with previous results in the same field of research topic. This work requires knowledge of different kinds of potentials and the difference between the phenomenological and microscopic interactions and research in Hartree-Fock method and nuclear models, especially shell model. The content of the present thesis can be summarized as the following: The first Chapter, (Introduction), presents detailed informations about the nuclear structure, clustering, alpha clustering and nuclear models especially the shell model. Also, a review of previous researches in the research topic ( phenomenological alpha- alpha interactions). The second chapter, (Alpha-Alpha interactions), many types of phenomenological alpha-alpha interactions and its various forms are displayed, including what has been used in the thesis.The third chapter, (Derivation of Hartree-Fock Method for Bosons), illustrates the theoretical calculations which have been used in the thesis, the derivation of the Hartree-Fock method for bosons, the variational method and the derivation of binding energy, form factor and root mean square radius equations. the fourth chapter, (Numerical Results and Discussion), includes the present theoretical results of the nuclear structure of 16 O nucleus using the previous four potentials, and comparing our present results with the experimental and previous theoretical ones.

  6. Thermochemical Stability of alpha-Amino-alpha-carbonylmethyl Radicals and Their Resonance As Measured by ESR.

    Science.gov (United States)

    Welle, Frank M.; Beckhaus, Hans-Dieter; Rüchardt, Christoph

    1997-02-07

    ESR spectra of the captodative alpha-amino-alpha-carbonylmethyl radicals 8 have been recorded. No coalescence temperature for the rotation of the two NMe groups was found at temperatures below the decomposition temperature of the radicals. From known coalescence temperatures and rotational barriers of substituted methyl radicals the rotational barrier of >/=17 kcal mol(-)(1) was estimated for the (*)C-N bond in the radicals 8. Enthalpies DeltaH(diss) and entropies DeltaS(diss) of the homolytic dissociation of 7a,c,d into 8a,c,d have been obtained from equilibrium measurements by ESR. By correcting for substituent interaction enthalpies in 7 (steric and geminal), a radical stabilization enthalpy RSE = -20.7 +/- 1.0 kcal mol(-)(1) was obtained for 8. By addition of the known RSEs of dialkylamino- and carbonyl groups, a RSE = -9.9 kcal mol(-)(1) is predicted for 8. The difference between the experimental and predicted values of 10.8 kcal mol(-)(1) is attributed to a synergistic captodative substituent effect. A linear correlation between the radical stabilization enthalpies of the radicals 8 and of other mono- and disubstituted alkyl radicals and their ESR aH(alpha) coupling constants was found. According to this correlation the reduction of aH(alpha) by 1 G corresponds to an increase in RSE of 1.57 kcal mol(-)(1). The large resonance of the captodative alpha-amino-alpha-carbonylmethyl radicals 3, expressed by their high RSE, their small aH(alpha) coupling constant, and their high rotational barrier, can be rationalized by a strong interaction between the alpha-amino and the alpha-carbonyl groups similar to that in amides and expressed in the resonance structures 6.

  7. Optimality of private quantum channels

    International Nuclear Information System (INIS)

    Bouda, Jan; Ziman, Mario

    2007-01-01

    We addressed the question of optimality of private quantum channels. We have shown that the Shannon entropy of the classical key necessary to securely transfer the quantum information is lower bounded by the entropy exchange of the private quantum channel E and the von Neumann entropy of the ciphertext state ρ (0) . Based on these bounds we have shown that decomposition of private quantum channels into orthogonal unitaries (if they exist) optimizes the entropy. For non-ancillary single-qubit PQC we have derived the optimal entropy for the arbitrary set of plaintexts. In particular, we have shown that except when the (closure of the) set of plaintexts contains all states, one bit key is sufficient. We characterized and analysed all the possible single-qubit private quantum channels for an arbitrary set of plaintexts. For the set of plaintexts consisting of all qubit states we have characterized all possible approximate private quantum channels and we have derived the relation between the security parameter and the corresponding minimal entropy

  8. The minimum yield in channeling

    International Nuclear Information System (INIS)

    Uguzzoni, A.; Gaertner, K.; Lulli, G.; Andersen, J.U.

    2000-01-01

    A first estimate of the minimum yield was obtained from Lindhard's theory, with the assumption of a statistical equilibrium in the transverse phase-space of channeled particles guided by a continuum axial potential. However, computer simulations have shown that this estimate should be corrected by a fairly large factor, C (approximately equal to 2.5), called the Barrett factor. We have shown earlier that the concept of a statistical equilibrium can be applied to understand this result, with the introduction of a constraint in phase-space due to planar channeling of axially channeled particles. Here we present an extended test of these ideas on the basis of computer simulation of the trajectories of 2 MeV α particles in Si. In particular, the gradual trend towards a full statistical equilibrium is studied. We also discuss the introduction of this modification of standard channeling theory into descriptions of the multiple scattering of channeled particles (dechanneling) by a master equation and show that the calculated minimum yields are in very good agreement with the results of a full computer simulation

  9. Charged and Neutral Particles Channeling Phenomena Channeling 2008

    Science.gov (United States)

    Dabagov, Sultan B.; Palumbo, Luigi

    2010-04-01

    On the discovery of coherent Bremsstrahlung in a single crystal at the Frascati National Laboratories / C. Barbiellini, G. P. Murtas and S. B. Dabagov -- Advances in coherent Bremsstrahlung and LPM-effect studies (to the lOOth anniversary from the birth of L. D. Landau) / N. F. Shul'ga -- Spectra of radiation and created particles at intermediate energy in oriented crystal taking into account energy loss / V. N. Baier and V. M. Katkov -- The coherent Bremsstrahlung beam at MAX-lab facility / K. Fissum ... [et al.] -- Radiation from thin, structured targets (CERN NA63) / A. Dizdar -- Hard incoherent radiation in thick crystals / N. F. Shul'ga, V. V. Syshchenko and A. I. Tarnovsky -- Coherent Bremsstrahlung in periodically deformed crystals with a complex base / A. R. Mkrtchyan, A. A. Saharian and V. V. Parazian -- Induction of coherent x-ray Bremsstrahlung in crystals under the influence of acoustic waves / A. R. Mkrtchyan and V. V. Parazian -- Coherent processes in bent single crystals / V. A. Maisheev -- Experimental and theoretical investigation of complete transfer phenomenon for media with various heat exchange coefficients / A. R. Mkrtchyan, A. E. Movsisyan and V. R. Kocharyan -- Coherent pair production in crystals / A. R. Mkrtchyan, A. A. Saharian and V. V. Parazian -- Negative particle planar and axial channeling and channeling collimation / R. A. Carrigan, Jr. -- CERN crystal-based collimation in modern hadron colliders / W. Scandale -- Studies and application of bent crystals for beam steering at 70 GeV IHEP accelerator / A. G. Afonin ... [et al.] -- Crystal collimation studies at the Tevatron (T-980) / N. V. Mokhov ... [et al.] -- Fabrication of crystals for channeling of particles in accellerators / A. Mazzolari ... [et al.] -- New possibilities to facilitate collimation of both positively and negatively charged particle beams by crystals / V. Guidi, A. Mazzolari and V. V. Tikhomirov -- Increase of probability of particle capture into the channeling

  10. Production of pi /sup 0/ at large transverse momentum in alpha alpha and alpha p collisions at the CERN Intersecting Storage Rings

    CERN Document Server

    Karabarbounis, A; Fields, T; Filippas-Tassos, A; Fokitis, E; Goldberg, M; Kourkoumelis, C; Lissauer, D; Mannelli, I; Molzon, W; Mouzourakis, P; Palmer, R B; Rahm, David Charles; Rehak, P; Resvanis, L K; Stumer, I; Trakkas, C; Willis, W

    1981-01-01

    Inclusive pi /sup 0/ production has been measured at the CERN Intersecting Storage Rings in alpha alpha and alpha p collisions near 90 degrees , for p/sub T/ between 2 and 5 GeV/c. The differential cross sections show a slower exponential fall-off with p/sub T/ than has been observed in pp collisions at the corresponding nucleon- nucleon centre-of-mass energies at large p/sub T/. The ratio of the pi /sup 0/ production cross sections for alpha alpha collisions to those for pp collisions is observed to be larger than 16. (8 refs).

  11. A survey of the alpha-nucleon interaction

    International Nuclear Information System (INIS)

    Ali, S.; Ahmad, A.A.Z.; Ferdous, N.

    1984-10-01

    A survey of the alpha-nucleon interaction is made. The experimental work on angular distributions of differential scattering cross-sections and polarizations in proton-alpha and neutron-alpha scattering is described. The phenomenological approach which includes the study of both local and non-local potentials reproducing the experimental alpha-nucleon scattering data, is discussed. Basic studies of the alpha-nucleon interaction attempting to build an interaction between an alpha particle and a nucleon from first principles are then described. A critical discussion of the results with some concluding remarks suggesting the direction for further investigation is made. (author)

  12. Production of {alpha}-glucosidases by Bacillus sp. strains

    Energy Technology Data Exchange (ETDEWEB)

    Castro, G.R. [Univ. Nacional de Tucuman, Facultad de Bioquimica, Quimica y Farmacia, Catedra de Microbiologia Superior, PROIMI-MIRCEN, Tucuman (Argentina); Baigori, M.D. [Univ. Nacional de Tucuman, Facultad de Bioquimica, Quimica y Farmacia, Catedra de Microbiologia Superior, PROIMI-MIRCEN, Tucuman (Argentina); Sineriz, F. [Univ. Nacional de Tucuman, Facultad de Bioquimica, Quimica y Farmacia, Catedra de Microbiologia Superior, PROIMI-MIRCEN, Tucuman (Argentina)

    1995-12-31

    {alpha}-Glucosidase was detected in four wild-type amylolytic production strains belonging to the Bacillus genus. The strains showed {alpha}-glucosidase activity in extracellular and membrane-bound fractions. Kinetic studies of the {alpha}-glucosidase synthesis in the batch cultures of four strains of the Bacillus genus showed two profiles: partially and totally growth-linked synthesis. The presence of different activities and production profiles of {alpha}-glucosidase in the strains at high or low glucose concentrations in the medium would indicate that {alpha}-glucosidase may have a role in the regulation of the metabolism of {alpha}-polysaccharides. (orig.)

  13. Remarks on tilde g_{alpha}-irresolute maps

    Directory of Open Access Journals (Sweden)

    Nirmala Rebecca Paul

    2011-12-01

    Full Text Available Only a few of the class of generalized closed sets form a topology. The class of tilde g_{alpha}-closed sets is one among them. The aim of this paper is to introduce the different notions of irresolute function using tilde g_{alpha}-closed sets and study some of their basic properties.We also study the relation between strongly tilde g_{alpha}- continuous and perfectly eg-continuous functions. We also introduce tilde g_{alpha}-compact and ilde g_{alpha}-connectedspaces and study their properties using tilde g_{alpha}-continuous and eg-irresolute functions.

  14. Modelling the electrical activity of pancreatic alpha-cells based on experimental data from intact mouse islets

    DEFF Research Database (Denmark)

    Diderichsen, Paul Matthias; Gopel, S.O.

    2006-01-01

    + current, a KATP conductance, and an unspecific leak current. Tolbutamide closes KATP channels in the alpha-cell, leading to a reduction of the resting conductance from 1.1 nS to 0.4 nS. This causes the alpha-cell to depolarise from -76 mV to 33 mV. When the basal membrane potential passes the range...... between -60 and -35 mV, the alpha-cell generates action potentials. At higher voltages, the alpha-cell enters a stable depolarised state and the electrical activity ceases. The effects of tolbutamide are simulated by gradually reducing the KATP conductance (g (K,ATP) ) from 500 pS to 0 pS. When g (K......,ATP) is between 72 nS and 303 nS, the model generates action potentials in the same voltage range as the alpha-cell. When g (K,ATP) is lower than 72 nS, the model enters a stable depolarised state, and firing of action potentials is inhibited due to voltage-dependent inactivation of the Na+ and T-type Ca2...

  15. Neuropsychiatric Complications Associated with Interferon - Alpha ...

    African Journals Online (AJOL)

    Several adverse effects have been associated with interferon alpha 2b treatment and neuropsychiatric effects have also been commonly reported. Psychosis and mood disorders have been described in the literature. This case report is of a 30 year old man with malignant melanoma stage 3a who was receiving adjuvant ...

  16. Alpha -2b treatment of Malignant Melanoma

    African Journals Online (AJOL)

    Introduction. Interferon preparations such as interferon alpha are widely used in the treatment of a number of non malignant and malignant conditions including malignant melanoma where it used. Mania has been observed in patients undergoing interferon treatment especially after significant dose- reduction or treatment ...

  17. Laboratory system for alpha particle spectroscopy

    International Nuclear Information System (INIS)

    Dean, J.R.; Chiu, N.W.

    1987-03-01

    An automated alpha particle spectroscopy system has beeen designed and fabricated. It consists of two major components, the automatic sample changer and the controller/data acquisition unit. It is capable of unattended analysis of ten samples for up to 65,000 seconds per sample

  18. Biomarkers of Alpha Particle Radiation Exposure

    Science.gov (United States)

    2014-04-01

    work towards the identification of gene-based biomarkers of alpha-particle radiation exposure. Peripheral blood mononuclear cells (PBMN) isolated from...manipulation et l’exposition au rayonnement ionisant chez les humains . CSSP-2012-CD-1117 and CSSP-2012-CD-1114 iii Table of contents...19 Acknowledgements This work was supported by the Centre for

  19. Superparamagnetic relaxation in alpha-Fe particles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Pedersen, Michael Stanley

    1998-01-01

    The superparamagnetic relaxation time of carbon-supported alpha-Fe particles with an average size of 3.0 Mm has been studied over a large temperature range by the use of Mossbauer spectroscopy combined with AC and DC magnetization measurements. It is found that the relaxation time varies with tem...

  20. Extraction of molybdenum VI by alpha benzoinoxime

    International Nuclear Information System (INIS)

    Achache, M.; Meklati, M.

    1990-06-01

    The concentration of molybdenum, was studied using alpha benzoinoxime dissolved in chloroform. Several acids and salt at different levels of concentration were investigated as well as other parameters such as (mixing time, extractant to metal ratio, temperature etc.) The molybdenum stippling was also studied in alkaline medium with the subsequent recovery of the extractant and solvent

  1. Syndecan-4 associates with alpha-actinin

    DEFF Research Database (Denmark)

    Greene, Daniel K; Tumova, Sarka; Couchman, John R

    2002-01-01

    during the formation of focal adhesions. To date, a direct link between syndecan-4 and the cytoskeleton has remained elusive. We now demonstrate by Triton X-100 extraction immunoprecipitation and in vitro binding assays that the focal adhesion component alpha-actinin interacts with syndecan-4 in a beta...

  2. Genetics Home Reference: alpha-1 antitrypsin deficiency

    Science.gov (United States)

    ... rapid heartbeat upon standing. Affected individuals often develop emphysema, which is a lung disease caused by damage to the small air ... exposure to tobacco smoke accelerates the appearance of emphysema symptoms and damage to the lungs. About 10 percent of infants with alpha-1 ...

  3. Diagnosis of foetal membrane ruptures: Placental alpha ...

    African Journals Online (AJOL)

    AbstRACt. Context: Pre‑labour rupture of membranes (PROM) is a common obstetric complication which presents a diagnostic challenge, especially in equivocal cases. Standard methods of diagnosis are limited by high false positives and negatives. This study compared the accuracy of a biomarker placental alpha ...

  4. Evaluation of microcrystalline cellulose modifed from alpha ...

    African Journals Online (AJOL)

    Alpha cellulose was obtained from Costus afer and part of it was modified to microcrystalline cellulose (CAMCC). The physicochemical properties of the microcrystalline cellulose were determined and compared with those of commercial microcrystalline cellulose (Avicel 101). The swelling capacity, hydration capacity, loss ...

  5. Physicochemical and powder properties of alpha- and ...

    African Journals Online (AJOL)

    Cob alpha-celluloses (CAC) was extracted from maize cobs by defibering, delignification and bleaching; then subjected to acid hydrolysis to obtain Cob- microcrystalline-cellulose (CMCC). Their physicochemical properties were evaluated and compared with those of Avicel®, a commercial variety of microcrystalline ...

  6. Interaction of alpha-latroinsectotoxin from Latrodectus mactans venom with bilayer lipid membranes.

    Science.gov (United States)

    Shatursky OYa; Pashkov, V N; Bulgacov, O V; Grishin, E V

    1995-01-26

    alpha-Latroinsectotoxin (LIT) from Latrodectus mactans venom increased the conductance of bilayer lipid membranes (BLM) by inducing channel like activity. The channels formed had a maximal single channel conductance of 5 pS in 10 mM CaCl2 solution. This process occurred more rapidly in symmetrical 10 mM CaCl2 solution than in equimolar KCl or NaCl. The LIT induced conductance showed pronounced rectification, that was dependent upon the face of the BLM to which the LIT was applied. This suggests that the LIT molecules incorporate into the bilayer lipid membrane in an oriented manner. The ion channels formed in bilayer phospholipid membrane by LIT are cation selective. The permeability of divalent cations decreased in the order Ba2+ > Ca2+ > Mg2+ > Cd2+ > Zn2+ (Zn2+ and Cd2+ blocked effectively LIT channels with the ratio of Ca2+trans and Cd2+cis or Zn2+cis of 1:1). Selectivity of LIT to monovalent cations was not high and was Ca2+ sensitive. Our data suggest that LIT has at least two Ca(2+)-binding sites, a high affinity site and low one (pK of binding is 2.4). As a result, the binding kinetics of Ca2+ with the toxin shows a high positive cooperativity (Hill coefficient, (h) = 5.95) and that dimerization might be a prerequisite to channel formation. Temperature dependence of conductance of LIT treated lipid bilayers in 100 mM KCl and 10 mM CaCl2 solutions was also determined: 18.9 +/- 2.11 kJ/mol and 28.537 +/- 1.678 kJ/mol, respectively.

  7. Channels of Monetary Transmission in the CIS

    OpenAIRE

    Jamilov, Rustam

    2012-01-01

    Twenty years have passed since the breakdown of the Soviet Union, and it is time to draw a concluding line for monetary policy efficiency in the Commonwealth of Independent States (CIS). We propose a comprehensive treatment of the subject for nine members of the CIS for the period of 2000-2009. Four transmission channels are investigated: interest rate channel, exchange rate channel, bank lending channel, and monetary channel. First, we design a VAR framework for each CIS member-state and inv...

  8. Modification of single Na+ channels by batrachotoxin.

    OpenAIRE

    Quandt, F N; Narahashi, T

    1982-01-01

    The modifications in the properties of voltage-gated Na+ channels caused by batrachotoxin were studied by using the patch clamp method for measuring single channel currents from excised membranes of N1E-115 neuroblastoma cells. The toxin-modified open state of the Na+ channel has a decreased conductance in comparison to that of normal Na+ channels. The lifetime of the modified open state is drastically prolonged, and channels now continue to open during a maintained depolarization so that the...

  9. Insect sodium channels and insecticide resistance

    OpenAIRE

    Dong, Ke

    2007-01-01

    Voltage-gated sodium channels are essential for the generation and propagation of action potentials (i.e., electrical impulses) in excitable cells. Although most of our knowledge about sodium channels is derived from decades of studies of mammalian isoforms, research on insect sodium channels is revealing both common and unique aspects of sodium channel biology. In particular, our understanding of the molecular dynamics and pharmacology of insect sodium channels has advanced greatly in recent...

  10. Pharmacological modulation of SK3 channels

    DEFF Research Database (Denmark)

    Grunnet, M; Jespersen, Thomas; Angelo, K

    2001-01-01

    Small-conductance, calcium-activated K+ channels (SK channels) are voltage-insensitive channels that have been identified molecularly within the last few years. As SK channels play a fundamental role in most excitable cells and participate in afterhyperpolarization (AHP) and spike-frequency adapt...... at concentrations of 3 microM and above. Amitriptyline, a tricyclic antidepressive widely used clinically, inhibits SK3 channels with an IC50 of 39.1 +/- 10 microM (n=6)....

  11. Axial channeling of uttrarelativistic electrons

    Energy Technology Data Exchange (ETDEWEB)

    Telegin, V.I.; Khokonov, M.Kh. (Moskovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Yadernoj Fiziki)

    1982-07-01

    The dynamics of motion of ultrarelativistic electrons under axial channeling conditions is investigated. The analysis is based on the solution of the kinetic equation obtained recently by Beloshitsky and Kumakhov. The particle dechanneling function is investigated as depending on the type of a crystal, particle energy and angle of entrance into the single crystal. It is found that for most of the beam the major diffusion mechanism is scattering by electrons. It is shown that an optimal depth range exists for which the fraction of channeled particles sharply increases at the expense of the quasi-channeled particles. In a number of cases the dechanneling length for crystals with high atomic numbers may be greater than that of light elements.

  12. Axial channeling of uttrarelativistic electrons

    International Nuclear Information System (INIS)

    Telegin, V.I.; Khokonov, M.Kh.

    1982-01-01

    The dynamics of motion of ultrarelativistic electrons under axial channeling conditions is investigated. The analysis is based on the solution of the kinetic equation obtained recently by Beloshitsky and Kumakhov. The particle dechanneling function is investigated as depending on the type of a crystal, particle energy and angle of entrance into the single crystal. It is found that for most of the beam the major diffusion mechanism is scattering by electrons. It is shown that an optimal depth range exists for which the fraction of channeled particles sharply increases at the expense of the quasi-channeled particles. In a number of cases the dechanneling length for crystals with high atomic numbers may be greater than that of light elements

  13. Evaluate interference in digital channels

    Science.gov (United States)

    Davarian, F.; Sumida, J.

    1985-01-01

    Any future mobile satellite service (MSS) which is to provide simultaneous mobile communications for a large number of users will have to make very efficient use of the spectrum. As the spectrum available for an MSS is limited, the system's channels should be packed as closely together as possible, with minimum-width guard bands. In addition the employment of frequency reuse schemes is an important factor. Difficulties regarding these solutions are related to the introduction of interference in the link. A balance must be achieved between the competing aims of spectrum conservation and low interference. While the interference phenomenon in narrowband FM voice channels is reasonably well understood, very little effort, however, has been devoted to the problem in digital radios. Attention is given to work, which illuminates the effects of cochannel and adjacent channel interference on digital FM (FSK) radios.

  14. Pannexin-1 channels in epilepsy.

    Science.gov (United States)

    Aquilino, Mark S; Whyte-Fagundes, Paige; Zoidl, Georg; Carlen, Peter L

    2017-09-05

    Pannexin-1 (Panx1) expression is raised in several animal seizure models and in resected human epileptic brain tissue, suggesting relevance to epilepsy. Multiple factors that are characteristic of seizures are thought to regulate Panx1 channel opening, including elevated levels of extracellular K + . Panx1, when open, 1) releases ATP, glutamate, and other metabolites into the extracellular medium, and 2) may depolarize the membrane due to a channel reversal potential around 0mV. Resultant ATP release from stimulated Panx1 can activate purinergic receptors, including P2X7 receptors. Glutamate and other signaling molecules released by Panx1 opening may have both excitatory and inhibitory actions on seizure generation. This review examines the critical and complex roles of Panx1 channels in epilepsy, which could provide a basis for future therapeutics. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Comparison of alpha decay and alpha transfer reactions in the lead region. [R matrix theory, absolute alpha widths, cross sections, 93 MeV

    Energy Technology Data Exchange (ETDEWEB)

    DeVries, R.M.

    1978-01-01

    Data were taken for five transitions in the lead region allowing a quantitative comparison with corresponding alpha-decay data via R-matrix theory using the same target + alpha nuclear potential. Good agreement between the absolute reduced widths determined from the two sets of data suggests that in transfer reactions, as in alpha decay, an alpha particle in its ground state is transferred in a one-step process. In a separate analysis, elastic and total reaction cross sections for the systems ..cap alpha.. + /sup 208/Pb, /sup 209/Bi were analyzed to obtain a limited set of potentials which, in turn, were used to calculate absolute alpha widths. Existing shell model calculations give ..gamma../sub ..cap alpha..//sup 2/ values three orders of magnitude smaller.

  16. Involvement of the clock gene Rev-erb alpha in the regulation of glucagon secretion in pancreatic alpha-cells.

    Directory of Open Access Journals (Sweden)

    Elaine Vieira

    Full Text Available Disruption of pancreatic clock genes impairs pancreatic beta-cell function, leading to the onset of diabetes. Despite the importance of pancreatic alpha-cells in the regulation of glucose homeostasis and in diabetes pathophysiology, nothing is known about the role of clock genes in these cells. Here, we identify the clock gene Rev-erb alpha as a new intracellular regulator of glucagon secretion. Rev-erb alpha down-regulation by siRNA (60-70% inhibition in alphaTC1-9 cells inhibited low-glucose induced glucagon secretion (p<0.05 and led to a decrease in key genes of the exocytotic machinery. The Rev-erb alpha agonist GSK4112 increased glucagon secretion (1.6 fold and intracellular calcium signals in alphaTC1-9 cells and mouse primary alpha-cells, whereas the Rev-erb alpha antagonist SR8278 produced the opposite effect. At 0.5 mM glucose, alphaTC1-9 cells exhibited intrinsic circadian Rev-erb alpha expression oscillations that were inhibited by 11 mM glucose. In mouse primary alpha-cells, glucose induced similar effects (p<0.001. High glucose inhibited key genes controlled by AMPK such as Nampt, Sirt1 and PGC-1 alpha in alphaTC1-9 cells (p<0.05. AMPK activation by metformin completely reversed the inhibitory effect of glucose on Nampt-Sirt1-PGC-1 alpha and Rev-erb alpha. Nampt inhibition decreased Sirt1, PGC-1 alpha and Rev-erb alpha mRNA expression (p<0.01 and glucagon release (p<0.05. These findings identify Rev-erb alpha as a new intracellular regulator of glucagon secretion via AMPK/Nampt/Sirt1 pathway.

  17. Chromaticity separation and the alpha response.

    Science.gov (United States)

    Haigh, S M; Cooper, N R; Wilkins, A J

    2018-01-08

    Chromatic gratings can be uncomfortable to view and can evoke a large haemodynamic response. Both the discomfort and the amplitude of the haemodynamic response increase monotonically with the perceptual difference in the colour of the component bars of the grating, as registered by the separation in their chromaticity in the CIE 1976 UCS diagram. Individuals with photosensitive epilepsy exhibit epileptiform EEG activity in response to flickering light of alternate colours. The probability of the epileptiform response again increases monotonically with the separation of the colours in the CIE UCS diagram. We investigated whether alpha power, which is known to reflect the excitation of large populations of neurons, is similarly affected by the separation in chromaticity. Chromatic square-wave gratings with bars that differed in CIE UCS chromaticity were presented, together with a central fixation cross. In 18 non-clinical participants, alpha responses were recorded over the visual cortex (O1, Oz, O2, PO3, POz, PO4, P1, P2) and compared to responses in prefrontal cortex (F1, F2). Gratings comprised bars of two alternate colours that either had a small difference in chromaticity (mean CIE UCS separation of 0.03), a medium difference (mean separation of 0.19), or a large difference (mean separation of 0.43). The colour pairs had chromaticities that lay on the red-green, red-blue, or blue-green borders of the screen gamut. Regardless of the hue, the larger the separation in chromaticity, the greater the alpha desynchronization and the lower the alpha power (p = 0.004), but only in posterior electrodes (p < 0.001). Together this indicates that differences in colour evoke a cortical excitation that increases monotonically with the colour difference. In this respect the alpha response resembles the haemodynamic response. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Antenna for Ultrawideband Channel Sounding

    DEFF Research Database (Denmark)

    Zhekov, Stanislav Stefanov; Tatomirescu, Alexandru; Pedersen, Gert F.

    2016-01-01

    A novel compact antenna for ultrawideband channel sounding is presented. The antenna is composed of a symmetrical biconical antenna modified by adding a cylinder and a ring to each cone. A feeding coaxial cable is employed during the simulations in order to evaluate and reduce its impact on the a......A novel compact antenna for ultrawideband channel sounding is presented. The antenna is composed of a symmetrical biconical antenna modified by adding a cylinder and a ring to each cone. A feeding coaxial cable is employed during the simulations in order to evaluate and reduce its impact...

  19. The Orange Juice Distribution Channels

    African Journals Online (AJOL)

    the agents in the European marketing channels of the FCOJ, focusing on the final juice consumers, retailing, food ... Marketing channels are defined as “a set of interdependent organisations involved in the process of making a .... Mexico - 8.0 8.0 8.3 8.0 8.0 - -. Venezuela - 7.9 8.0 7.5 7.3 7.1 - -. Taiwan - 4.4 4.9 6.2 6.6 7.0 - -.

  20. The measurement of $\\alpha_s$ from event shapes with the DELPHI detector at the highest LEP energies

    CERN Document Server

    Abdallah, J; Adam, W; Adzic, P; Albrecht, T; Alderweireld, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Amaldi, Ugo; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W D; Arnoud, Y; Ask, S; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Ballestrero, A; Bambade, P; Barbier, R; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Ben-Haim, E; Benekos, N C; Benvenuti, Alberto C; Bérat, C; Berggren, M; Berntzon, L; Bertrand, D; Besançon, M; Besson, N; Bloch, D; Blom, M; Bluj, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Brenner, R; Brodet, E; Brückman, P; Brunet, J M; Bugge, L; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F R; Chapkin, M M; Charpentier, P; Checchia, P; Chierici, R; Shlyapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crennell, D J; Cuevas-Maestro, J; D'Hondt, J; Dalmau, J; Da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; De Paula, L S; Di Ciaccio, Lucia; Di Simone, A; Doroba, K; Drees, J; Dris, M; Eigen, G; Ekelöf, T J C; Ellert, M; Elsing, M; Espirito-Santo, M C; Fanourakis, G K; Fassouliotis, D; Feindt, M; Fernández, J; Ferrer, A; Ferro, F; Flagmeyer, U; Föth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J A; Gandelman, M; García, C; Gavillet, P; Gazis, E N; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Herr, H; Hoffman, J; Holmgren, S O; Holt, P J; Houlden, M A; Hultqvist, K; Jackson, J N; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Johansson, P D; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Katsanevas, S; Katsoufis, E C; Kernel, G; Kersevan, Borut P; Kerzel, U; Kiiskinen, A P; King, B T; Kjaer, N J; Kluit, P; Kokkinias, P; Kourkoumelis, C; Kuznetsov, O; Krumshtein, Z; Kucharczyk, M; Lamsa, J; Leder, G; Ledroit, F; Leinonen, L; Leitner, R; Lemonne, J; Lepeltier, V; Lesiak, T; Liebig, W; Liko, D; Lipniacka, A; Lopes, J H; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; McNulty, R; Meroni, C; Migliore, E; Mitaroff, W A; Mjörnmark, U; Moa, T; Moch, M; Mönig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Müller, U; Münich, K; Mulders, M; Mundim, L M; Murray, W; Muryn, B; Myatt, Gerald; Myklebust, T; Nassiakou, M; Navarria, Francesco Luigi; Nawrocki, K; Nicolaidou, R; Nikolenko, M; Oblakowska-Mucha, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Österberg, K; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Palacios, J P; Palka, H; Papadopoulou, T D; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V F; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Pukhaeva, N; Pullia, Antonio; Rames, J; Ramler, L; Read, A; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P B; Richard, F; Rídky, J; Rivero, M; Rodríguez, D; Romero, A; Ronchese, P; Roudeau, Patrick; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovskii, A; Salmi, L; Salt, J; Savoy-Navarro, A; Schwickerath, U; Segar, A; Sekulin, R L; Siebel, M; Sissakian, A N; Smadja, G; Smirnova, O G; Sokolov, A; Sopczak, A; Sosnowski, R; Spassoff, Tz; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Tabarelli de Fatis, T; Taffard, A C; Tegenfeldt, F; Timmermans, J; Tkatchev, L G; Tobin, M; Todorovova, S; Tomé, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tzamarias, S; Uvarov, V; Valenti, G; van Dam, P; Van Eldik, J; Van Lysebetten, A; Van Remortel, N; Van Vulpen, I B; Vegni, G; Veloso, F; Venus, W A; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weiser, C; Wicke, D; Wickens, J H; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O P; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zinchenko, A I; Zupan, M

    2004-01-01

    Hadronic event shape distributions are determined from data in e+e- collisions between 183 and 207 GeV. From these the strong coupling alpha_s is extracted in O(alpha_s^2), NLLA and matched O(alpha_s^2)+NLLA theory. Hadronisation corrections evaluated with fragmentation model generators as well as an analytical power ansatz are applied. Comparing these measurements to those obtained at and around M_Z allows a combined measurement of alpha_s from all DELPHI data and a test of the energy dependence of the strong coupling.

  1. Muramidase, alpha-1 antitrypsin, alpha-1 antichymotrypsin, and S-100 protein immunoreactivity in giant cell lesions.

    Science.gov (United States)

    Regezi, J A; Zarbo, R J; Lloyd, R V

    1987-01-01

    A spectrum of giant cell lesions was evaluated for muramidase, alpha-1 antitrypsin, alpha-1 antichymotrypsin, and S-100 protein immunoreactivity using an avidin-biotin-complex immunoperoxidase method. Peripheral giant cell granuloma, central giant cell granuloma, giant cell tumor, osteitis fibrosa cystica, cherubism, and giant cell tumor of tendon sheath showed similar patterns of reactivity. Granulomatous inflammatory lesions stained more intensely for muramidase than did noninflammatory lesions. Alpha-1-antichymotrypsin was a slightly better marker of giant cell lesions than was alpha-1-antitrypsin. Positive S-100 protein staining in half the lesions was thought to be due to the presence of Langerhans cells. The results supported the belief that giant cell lesions of bone and tendon sheath are differentiated toward cells of the mononuclear-phagocyte system and that multinucleated giant cells are derived from macrophages.

  2. Measurement of total alpha activity in water; Messung der Gesamt-Alpha-Aktivitaet in Wasser

    Energy Technology Data Exchange (ETDEWEB)

    Eikenberg, Jost [Paul Scherrer Institut (PSI), Villigen (Switzerland). Abt. fuer Strahlenschutz und Sicherheit; Florschuetz, Bernd [Hessisches Landesamt fuer Umwelt und Geologie, Kassel (Germany). Dezernat 15 - Strahlenschutz; Salvamoser, Josef [Institut fuer Angewandte Isotopen-, Gas- und Umweltuntersuchungen, Woerthsee (Germany); Steinkopff, Thomas [Deutscher Wetterdienst, Offenbach am Main (Germany); Wilhelm, Christoph [Karlsruher Institut fuer Technologie (KIT), Eggenstein-Leopoldshafen (Germany). Sicherheitsmanagement - Analytische Labore; Wisser, Sascha [FCI, Mainz (Germany)

    2014-04-01

    The article describes the measurement of the total alpha activity in an (evaporated) liquid sample, and the various sample preparation methods for measurements with proportional counters or LSC. (orig.)

  3. Residues in Na(+) channel D3-S6 segment modulate both batrachotoxin and local anesthetic affinities.

    Science.gov (United States)

    Wang, S Y; Nau, C; Wang, G K

    2000-09-01

    Batrachotoxin (BTX) alters the gating of voltage-gated Na(+) channels and causes these channels to open persistently, whereas local anesthetics (LAs) block Na(+) conductance. The BTX and LA receptors have been mapped to several common residues in D1-S6 and D4-S6 segments of the Na(+) channel alpha-subunit. We substituted individual residues with lysine in homologous segment D3-S6 of the rat muscle mu1 Na(+) channel from F1274 to N1281 to determine whether additional residues are involved in BTX and LA binding. Two mutant channels, mu1-S1276K and mu1-L1280K, when expressed in mammalian cells, become completely resistant to 5 microM BTX during repetitive pulses. The activation and/or fast inactivation gating of these mutants is substantially different from that of wild type. These mutants also display approximately 10-20-fold reduction in bupivacaine affinity toward their inactivated state but show only approximately twofold affinity changes toward their resting state. These results demonstrate that residues mu1-S1276 and mu1-L1280 in D3-S6 are critical for both BTX and LA binding interactions. We propose that LAs interact readily with these residues from D3-S6 along with those from D1-S6 and D4-S6 in close proximity when the Na(+) channel is in its inactivated state. Implications of this state-dependent binding model for the S6 alignment are discussed.

  4. Coupling of voltage sensors to the channel pore: a comparative view

    Directory of Open Access Journals (Sweden)

    Vitya eVardanyan

    2012-07-01

    Full Text Available The activation of voltage-dependent ion channels is initiated by potential-induced conformational rearrangements in the voltage-sensor domains that propagates to the pore domain and finally opens the ion conduction pathway. In potassium channels voltage-sensors are covalently linked to the pore via S4-S5 linkers at the cytoplasmic site of the pore domain. Transformation of membrane electric energy into the mechanical work required for the opening or closing of the channel pore is achieved through an electromechanical coupling mechanism, which involves local interaction between residues in S4-S5 linker and pore-forming alpha helices.In this review we discuss present knowledge and open questions related to the electromechanical coupling mechanism in most intensively studied voltage-gated Shaker potassium channel and compare structure-functional aspects of coupling with those observed in distantly-related ion channels. We focus particularly on the role of electromechanical coupling in modulation of the constitutive conductance of ion channels.

  5. Synthesis and coupling reactions of alpha,alpha-dialkylated amino acids with nucleobase side chains.

    OpenAIRE

    Azumaya, I; Aebi, R; Kubik, S; Rebek, J

    1995-01-01

    Several di- and tripeptides containing protected purine (adenine) and pyrimidine (thymine) residues on their side chains were synthesized. The parent amino acids alpha, alpha-dialkylated in a symmetrical manner. An effective coupling procedure was developed for these sterically hindered amino acids: the fluoren-9-ylmethyloxycarbonyl-protected amino acid was dehydrated to its oxazolinone form, which was coupled in good yields with amino esters in hot tetrachloroethane.

  6. Catalytic enantioselective Michael addition reactions of alpha-nitroesters to alpha,beta-unsaturated ketones

    NARCIS (Netherlands)

    Keller, E; Veldman, N; Spek, AL; Feringa, BL

    1997-01-01

    Enantioselective Michael additions of alpha-nitroesters 2a-d with alpha,beta-unsaturated ketones were carried out in the presence of a catalytic amount of chiral Al-Li-(R,R')-2,2'-dihydroxy-1,1'-binaphthyl ('AlLiBINOL') complex prepared in situ from LiAlH4 and 2.45 equiv. of (R,R')-BINOL. The

  7. Antillatoxin is a marine cyanobacterial toxin that potently activates voltage-gated sodium channels.

    Science.gov (United States)

    Li, W I; Berman, F W; Okino, T; Yokokawa, F; Shioiri, T; Gerwick, W H; Murray, T F

    2001-06-19

    Antillatoxin (ATX) is a lipopeptide derived from the pantropical marine cyanobacterium Lyngbya majuscula. ATX is neurotoxic in primary cultures of rat cerebellar granule cells, and this neuronal death is prevented by either N-methyl-d-aspartate (NMDA) receptor antagonists or tetrodotoxin. To further explore the potential interaction of ATX with voltage-gated sodium channels, we assessed the influence of tetrodotoxin on ATX-induced Ca2+ influx in cerebellar granule cells. The rapid increase in intracellular Ca2+ produced by ATX (100 nM) was antagonized in a concentration-dependent manner by tetrodotoxin. Additional, more direct, evidence for an interaction with voltage-gated sodium channels was derived from the ATX-induced allosteric enhancement of [3H]batrachotoxin binding to neurotoxin site 2 of the alpha subunit of the sodium channel. ATX, moreover, produced a strong synergistic stimulation of [3H]batrachotoxin binding in combination with brevetoxin, which is a ligand for neurotoxin site 5 on the voltage-gated sodium channel. Positive allosteric interactions were not observed between ATX and either alpha-scorpion toxin or the pyrethroid deltamethrin. That ATX interaction with voltage-gated sodium channels produces a gain of function was demonstrated by the concentration-dependent and tetrodotoxin-sensitive stimulation of 22Na+ influx in cerebellar granule cells exposed to ATX. Together these results demonstrate that the lipopeptide ATX is an activator of voltage-gated sodium channels. The neurotoxic actions of ATX therefore resemble those of brevetoxins that produce neural insult through depolarization-evoked Na+ load, glutamate release, relief of Mg2+ block of NMDA receptors, and Ca2+ influx.

  8. CAMEX-4 NOAA LYMAN-ALPHA HYGROMETER V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The CAMEX-4 NOAA Lyman-Alpha Hygrometer dataset was collected by the NOAA Lyman-alpha Total Water Hygrometer, which was flown during the fourth field campaign in the...

  9. Alpha-(trifluoromethyl)amine derivatives via nucleophilic trifluoromethylation of nitrones.

    Science.gov (United States)

    Nelson, D W; Owens, J; Hiraldo, D

    2001-04-20

    (Trifluoromethyl)trimethylsilane (TMSCF(3)) reacts with nitrones to afford alpha-(trifluoromethyl)hydroxylamines protected as O-trimethylsilyl ethers. Potassium t-butoxide initiates the nucleophilic trifluoromethylation. The reaction works best with alpha,N-diaryl nitrones, and the conditions are compatible with a range of substituents on the aryl groups. Acidic deprotection of the nitrone/TMSCF(3) adducts generates alpha-(trifluoromethyl)hydroxylamines. Catalytic hydrogenation of the adducts produces alpha-(trifluoromethyl)amines. Nitrone/TMSCF(3) adducts with strong electron-withdrawing groups on the alpha-aryl ring or heterocyclic alpha-aryl groups undergo an elimination/addition sequence to generate alpha,alpha-bis(trifluoromethyl)amines. Nitrones with alkyl groups bound directly to the 1,3-dipolar moiety fail to react with TMSCF(3), but trifluoromethylation of beta,gamma-unsaturated nitrones followed by reduction of the double bond can circumvent this limitation.

  10. Plasma Ubiquinone, Alpha-Tocopherol and Cholesterol in Man

    DEFF Research Database (Denmark)

    Karlsson, Jan; Diamant, Bertil; Edlund, Per Olof

    1992-01-01

    Farmakologi, Coenzyme Q10, free cholesterol, vitamin E, antioxidants, Alpha-Tocopherol, vitamin Q, plasma, LDL-particle......Farmakologi, Coenzyme Q10, free cholesterol, vitamin E, antioxidants, Alpha-Tocopherol, vitamin Q, plasma, LDL-particle...

  11. Estimation of Time-Varying Autoregressive Symmetric Alpha Stable

    Data.gov (United States)

    National Aeronautics and Space Administration — In the last decade alpha-stable distributions have become a standard model for impulsive data. Especially the linear symmetric alpha-stable processes have found...

  12. Ligands of histamine receptors modulate acid-sensing ion channels.

    Science.gov (United States)

    Shteinikov, V Y; Korosteleva, A S; Tikhonova, T B; Potapieva, N N; Tikhonov, D B

    2017-09-02

    Recently we found that synthetic compounds containing amino group linked to hydrophobic or aromatic moiety are potent modulators of the proton-gated channels (ASICs). These structures have clear similarity with ligands of histamine receptors. We have also demonstrated that histamine potentiates homomeric ASIC1a by shifting its activation dependence to less acidic conditions. In the present work the action of a series of histamine receptors ligands on recombinant ASIC1a and ASIC2a was characterized. Two types of action were found for ASIC1a. 1-methylhistamine, N-alpha-methylhistamine, dimaprit and thioperamide caused significant potentiation, which was pH-dependent and voltage-independent. The H4R antagonist A943931 caused inhibition, which is likely due to voltage-dependent pore block. ASIC2a were virtually insensitive to the drugs tested. We conclude that ligands of histamine receptors should also be considered as ASIC modulators. Copyright © 2017. Published by Elsevier Inc.

  13. Interferon alpha for chronic hepatitis D.

    Science.gov (United States)

    Abbas, Zaigham; Khan, Muhammad Arsalan; Salih, Mohammad; Jafri, Wasim

    2011-12-07

    Hepatitis D virus is a small defective RNA virus that requires the presence of hepatitis B virus infection to infect a person. Hepatitis D is a difficult-to-treat infection. Several clinical trials have been published on the efficacy of interferon alpha for hepatitis D virus (HDV) infection. However, there are few randomised trials evaluating the effects of interferon alpha, and it is difficult to judge any benefit of this intervention from the individual trials. To evaluate the beneficial and harmful effects of interferon alpha for patients with chronic hepatitis D. We identified relevant for the review randomised clinical trials by electronic searches in the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until May 2011. We also checked the bibliographic references of identified randomised trials, textbooks, and review articles in order to find randomised trials not identified by the electronic searches. Randomised clinical trials evaluating interferon alpha versus placebo or no intervention for patients with chronic hepatitis D infection. Two authors assessed the trials and extracted data on mortality, virologic, biochemical, and histological response as well as adverse events at end of treatment and six months or more after completing treatment. The analyses were performed using the intention-to-treat principle including all randomised participants irrespective of follow-up. Drop-outs, withdrawals, and non-compliance were considered as treatment failures. Data were analysed with fixed- and random-effects models. Reported results were based on fixed-effect model except in cases where statistical significance varied between the two models. Six randomised trials fulfilled the inclusion criteria. Two hundred and one randomised participants (male = 174) were included. The risk of bias in all the included trials was high

  14. Visualizing multi-channel networks

    DEFF Research Database (Denmark)

    Antemijczuk, Paweł; Magiera, Marta; Jørgensen, Sune Lehmann

    2014-01-01

    In this paper, we propose a visualization to illustrate social interactions, built from multiple distinct channels of communication. The visualization displays a summary of dense personal information in a compact graphical notation. The starting point is an abstract drawing of a spider’s web. Below...

  15. Sorting out river channel patterns

    NARCIS (Netherlands)

    Kleinhans, M.G.

    2010-01-01

    Rivers self-organize their pattern/planform through feedbacks between bars, channels, floodplain and vegetation, which emerge as a result of the basic spatial sorting process of wash load sediment and bed sediment. The balance between floodplain formation and destruction determines the width and

  16. Sales promotion and channel coordination

    NARCIS (Netherlands)

    Wierenga, B.; Soethoudt, J.M.

    2010-01-01

    Consumer sales promotions are usually the result of the decisions of two marketing channel parties, the manufacturer and the retailer. In making these decisions, each party normally follows its own interest: i.e. maximizes its own profit. Unfortunately, this results in a suboptimal outcome for the

  17. Single top t-channel

    CERN Document Server

    Faltermann, Nils

    2017-01-01

    The production of single top quarks allows to study the interplay of top quark physics and the electroweak sector of the standard model. Deviations from predictions can be a hint for physics beyond the standard model. The t-channel is the dominant production mode for single top quarks at the LHC. This talk presents the latest measurements from the ATLAS and CMS collaborations.

  18. Improved Ion-Channel Biosensors

    Science.gov (United States)

    Nadeau, Jay; White, Victor; Dougherty, Dennis; Maurer, Joshua

    2004-01-01

    An effort is underway to develop improved biosensors of a type based on ion channels in biomimetic membranes. These sensors are microfabricated from silicon and other materials compatible with silicon. As described, these sensors offer a number of advantages over prior sensors of this type.

  19. Silicon vertex detector upgrade in the ALPHA experiment

    CERN Document Server

    Amole, C; Ashkezari, M.D; Baquero-Ruiz, M; Bertsche, W; Burrows, C; Butler, E; Capra, A; Cesar, C.L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M.C; Gill, D.R; Gutierrez, A; Hangst, J.S; Hardy, W.N; Hayden, M.E; Humphries, A.J; Isaac, C.A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J.T.K; Menary, S; Napoli, S.C; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Rasmussen, C.Ø; Robicheaux, F; Sacramento, R.L; Sampson, J.A; Sarid, E; Seddon, D; Silveira, D.M; So, C; Stracka, S; Tharp, T; Thompson, R.I; Thornhill, J; Tooley, M.P; Van Der Werf, D.P; Wells, D

    2013-01-01

    The Silicon Vertex Detector (SVD) is the main diagnostic tool in the ALPHA-experiment. It provides precise spatial and timing information of antiproton (antihydrogen) annihilation events (vertices), and most importantly, the SVD is capable of directly identifying and analysing single annihilation events, thereby forming the basis of ALPHA ' s analysis. This paper describes the ALPHA SVD and its upgrade, installed in the ALPHA ' s new neutral atom trap.

  20. Expression of alpha-amylase in Bacillus licheniformis.

    OpenAIRE

    Rothstein, D M; Devlin, P E; Cate, R L

    1986-01-01

    In Bacillus licheniformis, alpha-amylase production varied more than 100-fold depending on the presence or absence of a catabolite-repressing carbon source in the growth medium. alpha-Amylase was produced during the growth phase and not at the onset of the stationary phase. Induction of alpha-amylase correlated with synthesis of mRNA initiating at the promoter of the alpha-amylase gene.