161 research outputs found

    The evidence for histamine H3 receptor-mediated endothelium-dependent relaxation in isolated rat aorta

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    The presence of histamine H3 receptors was evaluated on the rat aorta endothelium. In the presence of pyrilamine (1 nM, 7 nM, 10 nM) or thioperamide (1 nM, 10 nM, 30 nM) the concentration–response curve for histamine-induced (0.1 nM − 0.01 mM) endothelium-dependent rat aorta relaxation was shifted to the right without significant change of the Emax indicating competitive antagonism by pyrilamine (pA2 = 9.33 ± 0.34, slope = 1.09 ± 0.36) or thioperamide (pA2 =9.31 ± 0.16, slope=0.94 ± 0.10). Cimetidine (1 μM) did not influence histamine-induced endothelium-dependent rat aorta relaxation. In the presence of thioperamide (1 nM, 10 nM, 30 nM) the concentration–response curve for (R)α-MeHA-induced (0.1 nM − 0.01 mM) endothelium-dependent relaxation was shifted to the right without significant change of Emax indicated competitive antagonism by thioperamide (pA2 = 9.21 ± 0.4, slope = 1.03 ± 0.35). Pyrilamine (100 nM) or cimetidine (1 μM) did not influence (R)α-MeHA-induced endothelium-dependent rat aorta relaxation. These results suggest the presence of a heterogenous population of histamine receptors, H1 and H3, on rat aorta endothelium

    Endothelium-dependent relaxation of rat aorta to a histamine H3 agonist is reduced by inhibitors of nitric oxide synthase, guanylate cyclase and Na+,K+-ATPase

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    The possible involvement of different effector systems (nitric oxide synthase, guanylate cyclase, β-adrenergic and muscarinic cholinergic receptors, cyclooxygenase and lipoxygenase, and Na+,K+-ATPase) was evaluated in a histamine H3 receptor agonist-induced ((R)α-methylhistamine, (R)α-MeHA) endothelium-dependent rat aorta relaxation assay. (R)α-MeHA (0.1 nM – 0.01 mM) relaxed endothelium-dependent rat aorta, with a pD2 value of 8.22 ± 0.06, compared with a pD2 value of 7.98 ± 0.02 caused by histamine (50% and 70% relaxation, respectively). The effect of (R)α-MeHA (0.1 nM – 0.01 mM) was competitively antagonized by thioperamide (1, 10 and 30 nM) (pA2 = 9.21 ± 0.40; slope = 1.03 ± 0.35) but it was unaffected by pyrilamine (100 nM), cimetidine (1 μM), atropine (10 μM), propranolol (1 μM), indomethacin (10 μM) or nordthydroguaiaretic acid (0.1 mM). Inhibitors of nitric oxide synthase, L-NG-monomethylarginine (L-NMMA, 10 μM) and NG-nitro-L-arginine methylester (L-NOARG, 10 μM) inhibited the relaxation effect of (R)α-MeHA, by approximately 52% and 70%, respectively). This inhibitory effect of L-NMMA was partially reversed by L-arginine (10 μM). Methylene blue (10 μM) and ouabain (10 μM) inhibited relaxation (R)α-MeHA-induced by approximately 50% and 90%, respectively. The products of cyclooxygenase and lipoxygenase are not involved in (R)α-MeHA-induced endothelium-dependent rat aorta relaxation nor are the muscarinic cholinergic and β-adrenergic receptors. The results also suggest the involvement of NO synthase, guanylate cyclase and Na+,K+-ATPase in (R)α-MeHA-induced endothelium-dependent rat aorta relaxation

    Isotope shift measurements in the 2s1/2 → 2p3/2 transition of Be+ and extraction of the nuclear charge radii for 7,10,11Be

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    We have performed isotope shift measurements in the 2s1/2 → 2p3/2 transition of Be+ ions using advanced collinear laser spectroscopy with two counter-propagating laser beams. Measurements involving a frequency comb for laser stabilization and absolute frequency determination allowed us to determine the isotope shifts with an accuracy of 2 MHz. From the isotope shifts between 9Be and 7, 10, 11Be, high-accuracy mass shift calculations and the charge radius of the reference isotope 9Be we determined nuclear charge radii for the isotopes 7, 10Be and the one-neutron halo nucleus 11Be. The results are compared to nuclear-structure calculations using the fermionic molecular dynamics model which reproduce well the general trend of the radii. Decreasing charge radii from 7Be to 10Be are explained by the cluster structure of the nuclei. The increase from 10Be to 11Be is mainly caused by the halo neutron by which the 10Be core moves relative to the center of mass. Polarization of the 10Be core has only a small influence on the charge radius. © 2010 IOP Publishing Ltd

    New contribution to the research of the theory of whole

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    Although a whole as a phenomenon was entertained by ancient Chinese wiesemen, it seems that this issue remains in the focus of the modern world too, and especially of social, and organizational sciences. However, any, even the science of organization and management has its theoretical basis. Without a theory that has been confirmed in practice, no science can get the title of science. Therefore, any contribution to the study of the theory of a whole has practical value, and if not, it is an utopia, something that is impossible and unattainable in the real world. The beliefs that in perspective the theory of a whole shall gain even greater importance are quite realistic, which is logical, because life, work and business keep getting more and more complex, with increased interdependence between relationships, and with increases of both speed and dynamics of life and work. The aim of this paper is to draw attention to new thoughts and ideas about the theory of a whole, and all for the purpose of its application in the design and management of organizational and other systems

    Nuclear Charge Radii of Be-7,9,10 and the one-neutron halo nucleus Be-11

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    Nuclear charge radii of 7,9,10,11^{7,9,10,11}Be have been determined by high-precision laser spectroscopy. On-line measurements were performed with collinear laser spectroscopy in the 2s1/22p1/22s_{1/2} \to 2p_{1/2} transition on a beam of Be+^{+} ions. Collinear and anticollinear laser beams were used simultaneously and the absolute frequency determination using a frequency comb yielded an accuracy in the isotope-shift measurements of about 1 MHz. Combination with accurate calculations of the mass-dependent isotope shifts yield nuclear charge radii. The charge radius decreases from 7^7Be to 10^{10}Be and then increases for the halo nucleus 11^{11}Be. When comparing our results with predictions of {\it ab initio} nuclear structure calculations we find good agreement. Additionally, the nuclear magnetic moment of 7^7Be was determined to be 1.3995(5)μN-1.3995(5)\mu_{\rm N} and that of 11^{11}Be from a previous β\beta-NMR measurement was confirmed.Comment: 4 pages, 2 figures calculated mass shift values have been re-evaluated with the latest mass values for the beryllium isotopes and the nuclear polarization contribution for Be-11, published by K. Pachucki et al. ater submission of our manuscript, is also included no

    Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

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    A newly constructed apparatus at the National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning trap along with a fast time-of-flight MCP detector capable of resolving the charge-state evolution of trapped ions. Holes in the two-magnet Penning trap ring electrode allow for optical and atomic beam access. Possible applications include spectroscopic studies of one-electron ions in Rydberg states, as well as highly charged ions of interest in atomic physics, metrology, astrophysics, and plasma diagnostics.Comment: Proceedings of CDAMOP-2011, 13-16 Dec 2011, Delhi, India. To be published by Springer Verla

    An AP-MS- and BioID-compatible MAC-tag enables comprehensive mapping of protein interactions and subcellular localizations

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    Protein-protein interactions govern almost all cellular functions. These complex networks of stable and transient associations can be mapped by affinity purification mass spectrometry (AP-MS) and complementary proximity-based labeling methods such as BioID. To exploit the advantages of both strategies, we here design and optimize an integrated approach combining AP-MS and BioID in a single construct, which we term MAC-tag. We systematically apply the MAC-tag approach to 18 subcellular and 3 sub-organelle localization markers, generating a molecular context database, which can be used to define a protein's molecular location. In addition, we show that combining the AP-MS and BioID results makes it possible to obtain interaction distances within a protein complex. Taken together, our integrated strategy enables the comprehensive mapping of the physical and functional interactions of proteins, defining their molecular context and improving our understanding of the cellular interactome.Peer reviewe
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