bluuebunny/crossref_metadata_2025 huggingface dataset:
Stochastic analyses and Monte Carlo simulations of nonergodic solute transport in three‐dimensional heterogeneous and statistically anisotropic aquifers
Authors: Zhang You‐Kuan , Seo Byong‐min
Published: May 2004

Stochastic analyses and Monte Carlo simulations were conducted for nonergodic transport of a nonreactive solute plume in three‐dimensional heterogeneous and statistically anisotropic aquifers under uniform mean flow along the x axis. The hydraulic conductivity, K(x), is modeled as a random field which is assumed to be lognormally distributed with an anisotropic exponential covariance. The simulation model is validated with good comparison of the simulated and theoretical variogram model of the log K field, small mass balance errors, and a large number of Monte Carlo (MC) runs. The ensemble averages of the second spatial moments of a solute plume about its center of mass, Zii, and the plume centroid variances, Rii, (i = 1, 2, 3) of 1600 MC runs were simulated for three degrees of heterogeneity and a line source of three different lengths along the y or z axis. At least 800 MC runs are needed to stabilize the simulated moments even for the mildly heterogeneous aquifers of σY2 ≤ 0.5, and the ergodic condition is far from reaching for a line source with the initial dimension of several integral scales of log K field. The first‐order theories predict well the longitudinal Z11 and R11 (thus the one‐particle displacement variance, X11 = Z11 + R11), significantly overestimate the horizontal transverse Z22 and R22 (thus X22), and overestimate the vertical transverse Z33 but underestimate R33.
Spatial scale of high‐speed flows in the plasma sheet observed by Cluster
Authors: Nakamura R. , Baumjohann W. , Mouikis C. , Kistler L. M. , Runov A. , Volwerk M. , Asano Y. , Vörös Z. , Zhang T. L. , Klecker B. , Rème H. , Balogh A.
Published: May 2004

Spatial gradients of high‐speed flows in the midtail plasma sheet are determined using multipoint observations from the Cluster spacecraft along the “dawn‐dusk” direction (perpendicular to the main flow and in the plane of the tail current sheet) and along the north‐south direction. If we take the average or median of the spatial gradients and assume that the flow channel has a linear gradient, these values suggest that the full width of the flow channel is 2–3 RE in the “dawn‐dusk” direction and 1.5–2 RE in the north‐south direction. The velocity gradient at the duskward edge of a flow tends to be sharper than that at the dawnward edge, possibly reflecting an asymmetry in the magnetosphere‐ionosphere coupling process associated with the flow.
The effect of growing season and summer greenness on northern forests
Authors: Kaufmann R. K. , D'Arrigo R. D. , Laskowski C. , Myneni R. B. , Zhou L. , Davi N. K.
Published: May 2004

We investigate the physiological effects of the elongation of the growing season and the increase in summer greenness on northern hemisphere forests by examining the relationship between NDVI and tree rings. These variables are correlated during June and July only. These results suggest that NDVI proxies the physiological status of trees and that the summer status of the canopy has a larger effect on tree vigor than the duration of the canopy.
Suppression of insulin signalling by a synthetic peptide KIFMK suggests the cytoplasmic linker between DIII‐S6 and DIV‐S1 as a local anaesthetic binding site on the sodium channel
Authors: Hirose Munetaka , Kuroda Yoshihiro , Sawa Shinichi , Nakagawa Terumichi , Hirata Masashi , Sakaguchi Masahiro , Tanaka Yoshifumi
Published: May 2004

Acetyl‐KIFMK‐amide (KIFMK) restores fast inactivation to mutant sodium channels having a defective inactivation gate. Its binding site with sodium channels could be considered to be the cytoplasmic linker (III–IV linker) connecting domains III and IV of the sodium channel α subunit. There is a close resemblance of the amino‐acid sequences between the III–IV linker and the activation loop of the insulin receptor (IR). This resemblance of the amino‐acid sequences suggests that KIFMK may also modulate insulin signalling. In order to test this assumption, we studied the effects of KIFMK and its related (KIYEK, KIQMK, and DIYET) and unrelated (LPFFD) peptides on tyrosine phosphorylation or dephosphorylation of IR in vitro.

Purified IR was phosphorylated in vitro with insulin in the presence of various synthetic peptides and lignocaine. The phosphorylation level of IR was then evaluated after SDS–PAGE separation, followed by Western blot analysis with antiphosphotyrosine antibody.

KIFMK and KIYEK inhibited insulin‐stimulated autophosphorylation of IR. Lignocaine showed similar effects, but at a higher order of concentration. KIYEK and DIYET, but not KIFMK, dephosphorylated the phosphorylated tyrosine residues. The structurally unrelated peptide LPFFD had no effect either on phosphorylation or dephosphorylation of IR.

These results indicate that KIFMK, KIYEK, and lignocaine bind with the autophosphorylation sites of IR.

The present findings also suggest that KIFMK and lignocaine bind with the III–IV linker of sodium channel α subunit.

British Journal of Pharmacology (2004) 142, 222–228. doi:10.1038/sj.bjp.0705575
Functional evidence of a role for two‐pore domain potassium channels in rat mesenteric and pulmonary arteries
Authors: Gardener M J , Johnson I T , Burnham M P , Edwards G , Heagerty A M , Weston A H
Published: May 2004

Experiments were performed to elucidate the mechanism by which alterations of extracellular pH (pHo) change membrane potential (EM) in rat mesenteric and pulmonary arteries.

Changing pHo from 7.4 to 6.4 or 8.4 produced a depolarisation or hyperpolarisation, respectively, in mesenteric and pulmonary arteries. Anandamide (10 μM) or bupivacaine (100 μM) reversed the hyperpolarisation associated with alkaline pHo, shifting the EM of both vessels to levels comparable to that at pH 6.4. In pulmonary arteries, clofilium (100 μM) caused a significant reversal of hyperpolarisation seen at pH 8.4 but was without effect at pH 7.4.

K+ channel blockade by 4‐aminopyridine (4‐AP) (5 mM), tetraethylammonium (TEA) (10 mM), Ba2+ (30 μM) and glibenclamide (10 μM) depolarised the pulmonary artery. However, shifts in EM with changes in pHo remained and were sensitive to anandamide (10 μM), bupivacaine (100 μM) or Zn2+ (200 μM).

Anandamide (0.3–60 μM) or bupivacaine (0.3–300 μM) caused a concentration‐dependent increase in basal tone in pulmonary arteries.

RT–PCR demonstrated the expression of TASK‐1, TASK‐2, THIK‐1, TRAAK, TREK‐1, TWIK‐1 and TWIK‐2 in mesenteric arteries and TASK‐1, TASK‐2, THIK‐1, TREK‐2 and TWIK‐2 in pulmonary arteries. TASK‐1, TASK‐2, TREK‐1 and TWIK‐2 protein was demonstrated in both arteries by immunostaining.

These experiments provide evidence for the presence of two‐pore domain K+ channels in rat mesenteric and pulmonary arteries. Collectively, they strongly suggest that modulation of TASK‐1 channels is most likely to have mediated the pH‐induced changes in membrane potential observed in these vessels, and that blockade of these channels by anandamide or bupivacaine generates a small increase in pulmonary artery tone.

British Journal of Pharmacology (2004) 142, 192–202. doi:10.1038/sj.bjp.0705691
If channel inhibitor ivabradine lowers heart rate in mice with enhanced sympathoadrenergic activities
Authors: Du Xiao‐Jun , Feng Xinheng , Gao Xiao‐Ming , Tan Tze Ping , Kiriazis Helen , Dart Anthony M
Published: May 2004

Ivabradine selectively reduces heart rate (HR) by inhibiting the cardiac pacemaker If current, thus prolonging the duration of spontaneous depolarization in the sinus node. The activity of ivabradine under conditions of enhanced sympathoadrenergic activity has been addressed by investigating the effects of repeated oral administration in mice with sympathoadrenergic activation due to either stress, cardiac‐restricted overexpression of β2‐adrenergic receptors (β2AR), or β‐agonist administration. HR and left ventricular fractional shortening (FS) were determined by echocardiography.

Initial experiments showed that the conscious restrained state was associated with stress‐mediated sympathetic activation, while sympathetic withdrawal occurred under anaesthetized conditions. In wild‐type mice, ivabradine reduced HR under both conscious and anaesthetized states, with a similar degree in absolute reduction under both states. FS was unchanged by the treatment.

Ivabradine was similarly effective in reducing HR in the β2AR transgenic mice. Further, ivabradine at 10 mg kg−1 day−1 reduced the maximal HR increase in response to the β‐agonist isoproterenol, without modifying the response of contractile parameters.

These data indicate that oral administration of ivabradine in mice reduces HR while ventricular performance is maintained. This specific HR‐reducing action of ivabradine is well preserved under conditions that are associated with significant activation of the sympathoadrenergic system.

British Journal of Pharmacology (2004) 142, 107–112. doi:10.1038/sj.bjp.0705696
Endocannabinoid‐mediated short‐term synaptic plasticity: depolarization‐induced suppression of inhibition (DSI) and depolarization‐induced suppression of excitation (DSE)
Authors: Diana Marco A , Marty Alain
Published: May 2004

Depolarization‐induced suppression of inhibition (DSI) and depolarization‐induced suppression of excitation (DSE) are two related forms of short‐term synaptic plasticity of GABAergic and glutamatergic transmission, respectively. They are induced by calcium concentration increases in postsynaptic cells and are mediated by the release of a retrograde messenger, which reversibly inhibits afferent synapses via presynaptic mechanisms.

We review here:

The evidence accumulated during the 1990s that has led to the conclusion that DSI/DSE rely on retrograde signaling.

The more recent research that has led to the identification of endocannabinoids as the retrograde messengers responsible for DSI/DSE.

The possible mechanisms by which presynaptic type 1 cannabinoid receptors reduce synaptic efficacy during DSI/DSE.

The possible modes of induction of DSI/DSE by physiological activity patterns, and the partially conflicting evaluations of the calcium concentration increases required for cannabinoid synthesis.

Finally, the relation between DSI/DSE and other forms of long‐ and short‐term synaptic inhibition, which were more recently associated with the production of endocannabinoids by postsynaptic cells.

British Journal of Pharmacology (2004) 142, 9–19. doi:10.1038/sj.bjp.0705726
Histamine H4 receptor mediates eosinophil chemotaxis with cell shape change and adhesion molecule upregulation
Authors: Ling Ping , Ngo Karen , Nguyen Steven , Thurmond Robin L , Edwards James P , Karlsson Lars , Fung‐Leung Wai‐Ping
Published: May 2004

During mast cell degranulation, histamine is released in large quantities. Human eosinophils were found to express histamine H4 but not H3 receptors. The possible effects of histamine on eosinophils and the receptor mediating these effects were investigated in our studies.

Histamine (0.01–30 μM) induced a rapid and transient cell shape change in human eosinophils, but had no effects on neutrophils. The maximal shape change was at 0.3 μM histamine with EC50 at 19 nM. After 60 min incubation with 1 μM histamine, eosinophils were desensitized and were refractory to shape change response upon histamine restimulation. Histamine (0.01–1 μM) also enhanced the eosinophil shape change induced by other chemokines.

Histamine‐induced eosinophil shape change was mediated by the H4 receptor. This effect was completely inhibited by H4 receptor‐specific antagonist JNJ 7777120 (IC50 0.3 μM) and H3/H4 receptor antagonist thioperamide (IC50 1.4 μM), but not by selective H1, H2 or H3 receptor antagonists. H4 receptor agonists imetit (EC50 25 nM) and clobenpropit (EC50 72 nM) could mimic histamine effect in inducing eosinophil shape change.

Histamine (0.01–100 μM) induced upregulation of adhesion molecules CD11b/CD18 (Mac‐1) and CD54 (ICAM‐1) on eosinophils. This effect was mediated by the H4 receptor and could be blocked by H4 receptor antagonists JNJ 7777120 and thioperamide.

Histamine (0.01–10 μM) induced eosinophil chemotaxis with an EC50 of 83 nM. This effect was mediated by the H4 receptor and could be blocked by H4 receptor antagonists JNJ 7777120 (IC50 86 nM) and thioperamide (IC50 519 nM). Histamine (0.5 μM) also enhanced the eosinophil shape change induced by other chemokines.

In conclusion, we have demonstrated a new mechanism of eosinophil recruitment driven by mast cells via the release of histamine. Using specific histamine receptor ligands, we have provided a definitive proof that the H4 receptor mediates eosinophil chemotaxis, cell shape change and upregulation of adhesion molecules. The effect of H4 receptor antagonists in blocking eosinophil infiltration could be valuable for the treatment of allergic diseases. The histamine‐induced shape change and upregulation of adhesion molecules on eosinophils can serve as biomarkers for clinical studies of H4 receptor antagonists.

British Journal of Pharmacology (2004) 142, 161–171. doi:10.1038/sj.bjp.0705729
The balloon catheter induces an increase in contralateral carotid artery reactivity to angiotensin II and phenylephrine
Authors: Accorsi‐Mendonça D , Corrêa F M A , Paiva T B , De Souza H P , Laurindo F R M , De Oliveira A M
Published: May 2004

The effects of balloon injury on the reactivity of ipsilateral and contralateral carotid arteries were compared to those observed in arteries from intact animals (control arteries).

Carotid arteries were obtained from Wistar rats 2, 4, 7, 15, 30 or 45 days after injury and mounted in an isolated organ bath. Reactivity to angiotensin II (Ang II), phenylephrine (Phe) and bradykinin (BK) was studied. Curves were constructed in the absence or presence of endothelium or after incubation with 10 μM indomethacin, 500 μM valeryl salicylate or 0.1 μM celecoxib.

Phe, Ang II and BK maximum effects (Emax) were decreased in ipsilateral arteries when compared to control arteries. No differences were observed among pD2 or Hill coefficient.

Emax to Phe (4 and 7 days) and to Ang II (15 and 30 days) increased in the contralateral artery. In addition, Phe or Ang II reactivity was not significantly different in aorta rings from control or carotid‐injured animals.

The increased responsiveness of contralateral artery was not due to changes in carotid blood flow or resting membrane potential. The endothelium‐dependent inhibitory component is not present in the contraction of contralateral arteries and it is not related to superoxide anion production.

Indomethacin decreased contralateral artery responsiveness to Phe and Ang II. Valeryl salicylate reduced the Ang II response in contralateral and control arteries. Celecoxib decreased the Phe Emax of contralateral artery.

In conclusion, decreased endothelium‐derived factors and increased prostanoids appear to be responsible for the increased reactivity of contralateral arteries after injury.

British Journal of Pharmacology (2004) 142, 79–88. doi:10.1038/sj.bjp.0705732
Vascular hyper‐reactivity following arterial balloon injury: distant and delayed effects
Authors: Wilson Andrew J
Published: May 2004

The adverse functional effects of balloon angioplasty include simple procedure failure, compromise of vessel lumen (rupture), and restenosis. A much less well‐defined repercussion of balloon injury to arteries is a paradoxical alteration in vascular reactivity at an anatomically distant site. The paper by Accorsi‐Mendonça in the current issue presents new data showing that, following balloon injury to the rat left common carotid artery, there is a delayed hyperreactivity to both phenylephrine and angiotensin II in the contralateral artery. The pharmacological basis of these effects is unknown, although the authors demonstrate that products of cyclooxygenase (COX) 1 or 2 are responsible for the hyperreactivity to angiotensin II and phenylephrine, respectively. The absence of delayed hyperreactivity to these agents in the aorta of injured rats would suggest that a humoral factor is not involved.

British Journal of Pharmacology (2004) 142, 3–4. doi:10.1038/sj.bjp.0705734
Comparison of functional profiles at human recombinant somatostatin sst2 receptor: simultaneous determination of intracellular Ca2+ and luciferase expression in CHO‐K1 cells
Authors: Nunn Caroline , Cervia Davide , Langenegger Daniel , Tenaillon Laurent , Bouhelal Rochdi , Hoyer Daniel
Published: May 2004

Somatostatin (somatotropin release inhibiting factor; SRIF) acts via five G protein‐coupled receptors (sst1–sst5) that modulate multiple cellular effectors. The aim of this study was to compare two functional effects of the human sst2 receptor stably expressed in CHO‐K1 cells in a single experiment using a duplex assay for intracellular calcium and serum response element (SRE)‐driven luciferase expression.

Intracellular calcium was measured using a fluorometric imaging plate reader II (FLIPR II). SRIF‐14 rapidly and transiently increased intracellular calcium with a pEC50 of 8.74±0.03 (n=52). At 5 h after FLIPR II measurements, luciferase expression was determined. SRIF‐14 concentration‐dependently increased luciferase expression (pEC50=9.06±0.03, n=52).

Natural and synthetic agonist/antagonist ligands for SRIF receptors were tested in the duplex assay. Correlation of agonist potencies and efficacies between the two responses were significant (r2=0.83 and 0.90, pEC50 and Emax, respectively).

Pertussis toxin pretreatment reduced SRIF‐14/octreotide‐mediated intracellular calcium increases by 45–47% and luciferase expression by 95–98%.

Thapsigargin pretreatment abolished the SRIF‐14/octreotide‐mediated intracellular calcium increase but had no effect on luciferase expression.

In conclusion, SRIF stimulates an increase in intracellular calcium and SRE‐luciferase expression via human sst2 receptors in CHO‐K1 cells. The increase in luciferase is mediated via Gi/Go while intracellular calcium increase is mediated by both Gi/Go proteins and pertussis toxin‐insensitive G proteins, and is mainly via release of calcium from intracellular stores. SRIF ligands display a similar recognition profile suggesting that the ligand/receptor/G protein/effector interaction is similar for the two parameters.

British Journal of Pharmacology (2004) 142, 150–160. doi:10.1038/sj.bjp.0705735
Raloxifene acutely suppresses ventricular myocyte contractility through inhibition of the L‐type calcium current
Authors: Liew Reginald , Stagg Mark A , MacLeod Kenneth T , Collins Peter
Published: May 2004

The selective oestrogen (ER) receptor modulator, raloxifene, is widely used in the treatment of postmenopausal osteoporosis, but may also possess cardioprotective properties. We investigated whether it directly suppresses myocyte contractility through Ca2+ channel antagonism in a similar way to 17β‐oestradiol.

Cell shortening and Ca2+ transients were measured in single guinea‐pig ventricular myocytes field‐stimulated (1 Hz, 37°C) in a superfusion chamber. Electrophysiological recordings were performed using single electrode voltage‐clamp.

Raloxifene decreased cell shortening (EC50 2.4 μM) and the Ca2+ transient amplitude (EC50 6.4 μM) in a concentration‐dependent manner. At a concentration of 1 μM, raloxifene produced a 33±2% (mean±s.e.m) and 24±2% reduction, respectively (P<0.001, n=14 for both parameters).

These inhibitory actions were not observed in myocytes that had been incubated with the specific antagonist, ICI 182,780 (10 μM) (n=11).

Raloxifene (1 μM) shortened action potential durations at 50 and 90% repolarisation (P<0.05 and <0.001, respectively; n=27) and decreased peak L‐type Ca2+ current by 45%, from −5.1±0.5 pA/pF to −2.8±0.3 pA/pF (P<0.001, n=18).

Raloxifene did not significantly alter sarcoplasmic reticulum Ca2+ content, as assessed by integrating the Na+/Ca2+ exchanger currents following rapid caffeine application.

The present study provides evidence for direct inhibitory actions of raloxifene on ventricular myocyte contractility, mediated through Ca2+ channel antagonism.

British Journal of Pharmacology (2004) 142, 89–96. doi:10.1038/sj.bjp.0705736
R‐citalopram functionally antagonises escitalopram in vivo and in vitro: evidence for kinetic interaction at the serotonin transporter
Authors: Stórustovu Signe í , Sánchez Connie , Pörzgen Peter , Brennum Lise T , Larsen Anna Kirstine , Pulis Monica , Ebert Bjarke
Published: May 2004

Clinical observations with the selective serotonin reuptake inhibitor (SSRI), S‐citalopram, indicate that S‐citalopram is more efficacious and produces earlier symptom relief than RS‐citalopram. Since R‐citalopram is at least 20‐fold weaker than S‐citalopram as inhibitor of the 5‐HT transporter (SERT) in preclinical studies, the clinical data suggest an unexpected antagonistic interaction between the two enantiomers. We therefore characterised the interaction of R‐ and S‐citalopram with the SERT in in vivo and in vitro assays.

In both behavioural (potentiation of 5‐hydroxytryptophan (5‐HTP)‐induced behaviour) and electrophysiological studies (inhibition of 5‐HT‐elicited ion currents in Xenopus oocytes expressing the human SERT (hSERT) R‐citalopram inhibited the effects of S‐citalopram in a dose‐dependent manner. With S‐citalopram : R‐citalopram ratios of 1 : 2 and 1 : 4, 5‐HTP potentiation was significantly smaller than with S‐citalopram alone.

emsp;R‐citalopram did not antagonise the effects of another SSRI (fluoxetine) in either behavioural or electrophysiological studies.

In oocytes, inhibition of hSERT‐mediated currents by R‐citalopram was almost completely reversible and characterised by fast on‐ and off‐sets of action. In contrast, the off‐set for S‐citalopram was 35‐fold slower than for R‐citalopram.

Kinetic analysis of the oocyte experiments suggests that S‐citalopram binding to SERT induces a long‐lasting, inhibited state of the transporter and that coapplication of R‐citalopram partially relieves SERT of this persistent inhibition.

We propose that the kinetic interaction of R‐ and S‐citalopram with SERT is a critical factor contributing to the antagonistic effects of R‐citalopram on S‐citalopram in vitro and in vivo.

British Journal of Pharmacology (2004) 142, 172–180. doi:10.1038/sj.bjp.0705738
Cardioprotective efficacy of zoniporide, a potent and selective inhibitor of Na+/H+ exchanger isoform 1, in an experimental model of cardiopulmonary bypass
Authors: Clements‐Jewery Hugh , Sutherland Fiona J , Allen Mary C , Tracey W Ross , Avkiran Metin
Published: May 2004

We determined (1) the inhibitory potency of zoniporide against the native Na+/H+ exchanger isoform 1 (NHE1) that is expressed in adult rat ventricular myocytes and platelets, and (2) the cardioprotective efficacy of zoniporide in isolated, blood‐perfused adult rat hearts subjected to cardioplegic arrest, hypothermic ischaemia (150 min at 25°C) and normothermic reperfusion (60 min at 37°C).

In isolated myocytes, in which NHE1 activity was determined directly by measurement of H+ efflux rate following intracellular acidification, zoniporide produced a dose‐dependent inhibition of such activity (IC50 73 nM at 25°C). A comparable NHE1‐inhibitory potency was retained at 37°C.

In platelets, in which the rate of cell swelling was used as a surrogate index of NHE1 activity, this was again inhibited by zoniporide (IC50 67 nM at 25°C).

In the isolated heart model, administration of zoniporide (loading bolus of 1 mg kg−1 i.v. plus continuous infusion at 1.98 mg kg−1 h−1 i.v.) to the support animal achieved a free plasma drug concentration of 1 μM. At this dose, zoniporide afforded significant cardioprotective benefit relative to vehicle treatment, with improved preservation of left ventricular end‐diastolic and developed pressures and coronary perfusion pressure during reperfusion. Myocardial myeloperoxidase activity was also attenuated by zoniporide treatment, indicating reduced neutrophil accumulation.

These data show that zoniporide (1) is a potent inhibitor of native NHE1 activity in ventricular myocytes and platelets, and (2) affords significant cardioprotective benefit during ischaemia and reperfusion in an experimental model that mimics several distinctive features of human cardioplegic arrest with cardiopulmonary bypass.

British Journal of Pharmacology (2004) 142, 57–66. doi:10.1038/sj.bjp.0705749
Markedly reduced effects of (−)‐isoprenaline but not of (−)‐CGP12177 and unchanged affinity of β‐blockers at Gly389‐β1‐adrenoceptors compared to Arg389‐β1‐adrenoceptors
Authors: Joseph S S , Lynham J A , Grace A A , Colledge W H , Kaumann A J
Published: May 2004

Substitution of arginine by glycine at position 389, a frequent β1‐adrenoceptor polymorphism, reduces adenylyl cyclase stimulation by (−)‐isoprenaline. β1‐Adrenoceptors mediate the effects of catecholamines and nonconventional partial agonists ((−)‐CGP12177) through different sites. We investigated the influence of the 389 polymorphism on β blocker affinity, as well as on the responses to (−)‐isoprenaline and the nonconventional partial agonist (−)‐CGP12177 on cyclic AMP levels in CHO cells expressing recombinant Arg389‐β1‐adrenoceptors (101 fmol mg−1 protein) or Gly389‐β1‐adrenoceptors (94 fmol mg−1).

The affinity of β‐blockers and partial agonists, estimated from competition binding with (−)‐[125I]‐cyanopindolol, was not different for Arg389‐β1‐adrenoceptors and Gly389‐β1‐adrenoceptors.

The maximum cAMP increases by (−)‐isoprenaline and (−)‐CGP12177 at Gly389‐β1‐adrenoceptors were reduced by 97 and 46%, but the potencies enhanced 2 and 0.5 log units, respectively, compared to Arg389‐β1‐adrenoceptors. The intrinsic activity of (−)‐CGP12177 with respect to the (−)‐isoprenaline was 0.057 at Arg389‐β1‐adrenoceptors and 1.05 at Gly389‐β1‐adrenoceptors.

We confirm in intact CHO cells that responses to (−)‐isoprenaline are markedly reduced at Gly389‐β1‐adrenoceptors compared to Arg389‐β1‐adrenoceptors. However, the 389 polymorphism reduces considerably less the agonist responses to (−)‐CGP12177, indicating that coupling to Gs protein is different for β1‐adrenoceptors activated by catecholamines than for receptors activated by nonconventional partial agonists. The affinity of β‐blockers is conserved across the Arg389Gly polymorphism.

British Journal of Pharmacology (2004) 142, 51–56. doi:10.1038/sj.bjp.0705753
Hydrogen sulfide (H2S) stimulates capsaicin‐sensitive primary afferent neurons in the rat urinary bladder
Authors: Patacchini Riccardo , Santicioli Paolo , Giuliani Sandro , Maggi Carlo Alberto
Published: May 2004

In the rat isolated urinary bladder, NaHS (30 μM–3 mM) and capsaicin (10 nM–3 μM) produced concentration‐dependent contractile responses (pEC50=3.5±0.02 and 7.1±0.02, respectively) undergoing dramatic tachyphylaxis. In preparations in which sensory nerves were rendered desensitized (defunctionalized) by high‐capsaicin (10 μM for 15 min) pretreatment, neither capsaicin itself nor NaHS produced any motor effect. NaHS‐induced contractile effects were totally prevented by the simultaneous incubation with tachykinin NK1 (GR 82334; 10 μM) and NK2 (nepadutant; 0.3 μM) receptor‐selective antagonists. Tetrodotoxin (1 μM) only partially reduced the response to NaHS. These results provide pharmacological evidence that H2S stimulates capsaicin‐sensitive primary afferent nerve terminals, from which tachykinins are released to produce the observed contraction by activating NK1 and NK2 receptors. While the molecular site of action of H2S remains to be investigated, our discovery may have important physiological significance since H2S concentrations capable of stimulating sensory nerves overlap those occurring in mammalian tissues under normal conditions.

British Journal of Pharmacology (2004) 142, 31–34. doi:10.1038/sj.bjp.0705764
Hydrogen sulphide: an endogenous stimulant of capsaicin‐sensitive primary afferent neurons?
Authors: Chahl L A
Published: May 2004

Hydrogen sulphide (H2S) is a gas best known for its rotten egg smell. The toxic effects of high concentrations of H2S have been extensively investigated. It is known that H2S is generated in mammalian systems, but little is known of its effects in physiological concentrations. In the present issue of this journal, Patacchini et al. present evidence that H2S stimulates capsaicin‐sensitive primary afferent neurons to release tachykinins in the rat urinary bladder. The possible significance of this finding is discussed in this commentary.

British Journal of Pharmacology (2004) 142, 1–2. doi:10.1038/sj.bjp.0705765
Metal/Al-doped ZnO ohmic contact for AlGaN/GaN high electron mobility transistor
Authors: Nishizono K. , Okada M. , Kamei M. , Kikuta D. , Tominaga K. , Ohno Y. , Ao J. P.
Published: May 2004

Ohmic property for AlGaN/GaN high electron mobility transistor was investigated by insetting a highly Al-doped ZnO between the metal and AlGaN/GaN structure. The Al-doped ZnO was deposited by dc magnetron sputtering method and Ti/Al/Ni/Au was deposited on the ZnO by evaporation. Prior to the ZnO deposition, the surface of the samples was treated by O2 plasma, HCl and NH4OH, respectively. Good ohmic performance was obtained with contact resistance of 2.7 Ω mm even without annealing. The lowest contact resistance was 2.0 Ω mm after being annealed at 300 °C for the sample with HCl treatment before ZnO deposition.
Atomic layer deposition of lanthanum aluminum oxide nano-laminates for electrical applications
Authors: Lim Booyong S. , Rahtu Antti , de Rouffignac Philippe , Gordon Roy G.
Published: May 2004

Lanthanum aluminum oxide thin films were grown by atomic layer deposition from a lanthanum precursor, tris(N,N′-diisopropylacetamidinato)lanthanum (La(iPrAMD)3), trimethylaluminum and water. Smooth, amorphous films having compositions La0.5Al1.5O3 and La0.9Al1.1O3 were deposited on HF-last silicon and characterized without postdeposition annealing. The films contained less than 1 at. % of carbon according to Rutherford backstattering spectrometry and secondary ion mass spectrometry. A thin (9.8 nm) film showed low leakage current (<5*10−8 A/cm2 at 1 V for an equivalent oxide thickness of 2.9 nm), flatband voltage of −0.1 V and low hysteresis (20 mV). Thicker films had even lower leakage currents (<10−8 A/cm2 at 2 MV/cm) but larger flatband shifts and more hysteresis. The permittivity of the films was 13 and the dielectric strength 4 MV/cm. Cross sectional high-resolution transmission electron microscopy showed a sharp interface between the film and the silicon substrate.
Optical near-field mapping of excitons and biexcitons in naturally occurring semiconductor quantum dots
Authors: Hohenester Ulrich , Goldoni Guido , Molinari Elisa
Published: May 2004

We calculate the near-field optical spectra of excitons and biexcitons in semiconductor quantum dots naturally occurring at interface fluctuations in GaAs-based quantum wells, using a nonlocal description of the response function to a spatially modulated electromagnetic field. The relative intensity of the lowest, far-field forbidden excitonic states is predicted; the spatial extension of the ground biexciton state is found, in agreement with recently published experiments.
Study of the temperature-dependent interaction of 4H–SiC and 6H–SiC surfaces with atomic hydrogen
Authors: Losurdo Maria , Bruno Giovanni , Brown April , Kim Tong-Ho
Published: May 2004

The interaction of 4H– and 6H–SiC (0001)Si surfaces with atomic hydrogen produced by a remote rf plasma source is investigated. The impact of the low temperature (200 °C) and high temperature (750 °C) interaction on chemical and morphological surface modifications is addressed with in situ real time monitoring using spectroscopic ellipsometry. It is found that the interaction of SiC surfaces with atomic hydrogen at 200 °C is suitable for producing clean, atomically ordered, smooth and terraced surfaces with a stoichiometry associated with a 3x3R30° reconstruction, ideal for GaN heteroepitaxy.
Electric-field-induced dynamics in radial liquid crystal droplets studied by multiphoton-excited fluorescence microscopy
Authors: Xie Aifang , Higgins Daniel A.
Published: May 2004

Time-resolved multiphoton-excited fluorescence microscopy is used to study electric-field-induced reorientation dynamics in single liquid crystal (LC) droplets within polymer-dispersed liquid crystal films. Films comprised of nematic LC dispersed in a poly(isobutyl methacrylate) matrix are characterized. An electric field is applied laterally across each droplet, using two parallel copper wires embedded in the film. Three-photon excited fluorescence images are recorded with 200 μs time resolution as the field is modulated on and off. Dramatic spatial variations in the time scales for orientational relaxation within individual droplets are observed. These effects are attributed to polymer/LC interfacial interactions and relaxation of the LC through a transient, metastable organizational state.
Four-probe charge transport measurements on individual vertically aligned carbon nanofibers
Authors: Zhang Lan , Austin Derek , Merkulov Vladimir I. , Meleshko Anatoli V. , Klein Kate L. , Guillorn Michael A. , Lowndes Douglas H. , Simpson Michael L.
Published: May 2004

We report four-probe I–V measurements on individual vertically aligned carbon nanofibers (VACNFs). These measurements were enabled by the fabrication of multiple Ti/Au ohmic contacts on individual fibers that exhibited resistance of only a few kilohms. These measurements demonstrate that VACNFs exhibit linear I–V behavior at room temperature, with a resistivity of approximately 4.2×10−3 Ω cm. Our measurements are consistent with a dominant transport mechanism of electrons traveling through intergraphitic planes in the VACNFs.
Multi-excitonic complexes in single InGaN quantum dots
Authors: Seguin R. , Rodt S. , Strittmatter A. , Reißmann L. , Bartel T. , Hoffmann A. , Bimberg D. , Hahn E. , Gerthsen D.
Published: May 2004

Cathodoluminescence spectra employing a shadow mask technique of InGaN layers grown by metalorganic chemical vapor deposition on Si(111) substrates are reported. Sharp lines originating from InGaN quantum dots are observed. Temperature dependent measurements reveal thermally induced carrier redistribution between the quantum dots. Spectral diffusion is observed and was used as a tool to correlate up to three lines that originate from the same quantum dot. Variation of excitation density leads to identification of exciton and biexciton. Binding and anti-binding complexes are discovered.
Dual structures in (1−x)Pb(Zn1/3Nb2/3)O3−xPbTiO3 ferroelectric relaxors
Authors: Xu Guangyong , Hiraka H. , Shirane G. , Ohwada K.
Published: May 2004

We performed x-ray diffraction studies on a series of (1−x)Pb(Zn1/3Nb2/3)O3−xPbTiO3 single crystals with different incident photon energies, and therefore different penetration depths. Our results show that outer layers of ∼10–50 μm thick are present in all samples. The structure of those outer layers is different from that of the inside of the crystals, by having much greater (rhombohedral) distortions. With increasing x, rhombohedral-type lattice distortions develop, both in the outer layer and on the inside.
Organic-metal-semiconductor transistor with high gain
Authors: Meruvia M. S. , Hümmelgen I. A. , Sartorelli M. L. , Pasa A. A. , Schwarzacher W.
Published: May 2004

We use evaporated C60 as the emitter in a vertical transistor structure with Au base and Si collector. The proportion of emitted electrons that overcome the barrier is measured as at least 0.99. Our metal-base transistor is easy to fabricate as it does not involve wafer bonding or require perfect semiconductor-on-metal growth.
Bulk metallic glass formation in the binary Cu–Zr system
Authors: Wang D. , Li Y. , Sun B. B. , Sui M. L. , Lu K. , Ma E.
Published: May 2004

Using the Cu–Zr model system, we demonstrate that bulk amorphous alloys can be obtained by copper mold casting even in a binary metallic system. The narrow, off-eutectic, bulk-glass-forming range was found to require composition pinpointing to <1 at. %. A phase selection diagram is used to explain the success of our microstructure-based approach to pinpoint the best glass former in a given system. The implications of discovering simple binary bulk amorphous alloys are discussed, in terms of its impact on understanding the formation and physics of bulk metallic glasses.
Conducting fluorocarbon coatings for organic light-emitting diodes
Authors: Tong S. W. , Lee C. S. , Lifshitz Y. , Gao D. Q. , Lee S. T.
Published: May 2004

Conducting fluorocarbon coatings (CFx) have recently been used as an anode buffer layer in organic light-emitting diode (OLEDs) for enhancement of stability and carrier injection. The effect of CFx on OLEDs was related to its conductivity. We found the resistivity of poorly conducting (about 1010 Ω cm) CFx coatings can be substantially decreased to 105 Ω cm by either near UV or Ar ion irradiation. OLEDs were prepared on untreated and treated CFx for performance comparison. The UV treatment of CFx improved the device performance, while the Ar ion treatment led to deterioration. X-ray photoelectron spectroscopy analysis showed the UV treatment created graphitic regions leading to the higher conductivity of the CFx layer but the underlying indium tin oxide (ITO) anode remained intact. In contrast, argon ion bombardment caused damage to the ITO anode which contributed to poor device performance, although the CFx conductivity was similarly increased.
GaInAs/GaAs quantum-well growth assisted by Sb surfactant: Toward 1.3 μm emission
Authors: Harmand J. C. , Li L. H. , Patriarche G. , Travers L.
Published: May 2004

The growth of highly strained GaInAs quantum wells on GaAs is investigated in the presence of Sb. Sb appears as an adequate isoelectronic surfactant: the lateral relaxation of strain is shown to be significantly delayed in comparison with a Sb-free growth. This effect is used to extend the emission wavelength of GaInAs quantum wells. We obtained a 9-nm-thick Ga0.59In0.41As0.986Sb0.008 quantum wells with smooth interfaces, emitting at 1.27 μm at room temperature.
Excimer laser nanostructuring of nickel thin films for the catalytic growth of carbon nanotubes
Authors: Henley S. J. , Poa C. H. P. , Adikaari A. A. D. T. , Giusca C. E. , Carey J. D. , Silva S. R. P.
Published: May 2004

Pulse laser ablation and subsequent laser nanostructuring at room temperature has been employed to produce nanostructured Ni on SiO2/Si substrates for catalytic growth of carbon nanotubes. The resultant nanostructured surface is seen to consist of nanometer sized hemispherical droplets whose mean diameter is controlled by the initial metal thickness, which in turn is readily controlled by the number of laser pulses. Vertically aligned multiwall carbon nanotube mats were then grown using conventional plasma enhanced chemical vapor deposition. We show that within a single processing technique it is possible to produce the initial metal-on-oxide thin film to a chosen thickness but also to be able to alter the morphology of the film to desired specifications at low macroscopic temperatures using the laser parameters. The influence of the underlying oxide is also explored to explain the mechanism of nanostructuring of the Ni catalyst.
Self-assembled magnetic nanostripes by organic patterning
Authors: Ma X. , Meyerheim H. L. , Barthel J. , Kirschner J. , Schmitt S. , Umbach E.
Published: May 2004

Selective adsorption of Fe deposited on the organic molecule 3,4,9,10-perylene-tetracarboxylic-3, 4,9,10-dianhydride (PTCDA) is used to prepare a self assembled magnetic nanostripe structure on a vicinal Ag surface. Scanning tunneling microscopy reveals that after PTCDA deposition on the Ag(10 8 7) surface a grating-like domain pattern is formed. It consists of alternating stripes of molecule-covered facets and uncovered (111) terraces. Fe adsorption takes place selectively on the molecule-covered stripes forming disk-shaped super-paramagnetic islands with a polar easy magnetization axis.
Measurement of guided light-mode intensity: An alternative waveguide sensing principle
Authors: Horváth Róbert , Skivesen Nina , Pedersen Henrik C.
Published: May 2004

An alternative transduction mechanism for planar optical waveguide sensors is reported. Based on a simple measurement of the mode intensity, the presented transduction is an interesting alternative to the conventional mode-angle transduction, because the expensive, high-precision angular rotation usually employed may be avoided.
Coherent control of intersubband optical bistability in quantum wells
Authors: Wijewardane H. O. , Ullrich C. A.
Published: May 2004

We present a study of the nonlinear intersubband (ISB) response of conduction electrons in a GaAs/Al0.3Ga0.7As quantum well to strong terahertz (THz) radiation, using a density-matrix approach combined with time-dependent density-functional theory. We demonstrate coherent control of ISB optical bistability, using THz control pulses to induce picosecond switching between the bistable states. The switching speed is determined by the ISB relaxation and decoherence times, T1 and T2.
Strong quantum-confinement effects in the conduction band of germanium nanocrystals
Authors: Bostedt C. , van Buuren T. , Willey T. M. , Franco N. , Terminello L. J. , Heske C. , Möller T.
Published: May 2004

Quantum-confinement effects in the conduction band of deposited germanium nanocrystals are measured to be greater than in similar-sized silicon nanocrystals. The germanium particles are condensed out of the gas phase and their electronic properties are determined with x-ray absorption spectroscopy. The conduction band edge shifts range from 0.2 eV for 2.7 nm particles up to 1.1 eV for 1.2 nm particles.
Surface effects in Mn L3,2 x-ray absorption spectra from (Ga,Mn)As
Authors: Edmonds K. W. , Farley N. R. S. , Campion R. P. , Foxon C. T. , Gallagher B. L. , Johal T. K. , van der Laan G. , MacKenzie M. , Chapman J. N. , Arenholz E.
Published: May 2004

We have identified a Mn-rich layer on the surface on (Ga,Mn)As thin films which significantly influences soft x-ray absorption measurements. The Mn L3,2 x-ray absorption spectra of the untreated films show a strong multiplet structure, consistent with earlier observations and characteristic of MnO. After removal of the surface layer, the multiplet structure is less pronounced and the spectrum is shifted to ∼0.5 eV lower photon energy. Comparison with calculated spectra imply a localized Mn ground state for the untreated sample and a hybridized ground state after etching. In addition, a large x-ray magnetic circular dichroism is observed at the Mn L3,2 edge in the etched film. These results may explain several peculiarities of previously reported x-ray absorption studies from (Ga,Mn)As.
Nonuniform twin-boundary motion in Ni–Mn–Ga single crystals
Authors: Marioni Miguel A. , Allen Samuel M. , O’Handley Robert C.
Published: May 2004

The twin-boundary motion in Ni–Mn–Ga single crystals has been studied with 620 μs magnetic-field pulses on samples of 5 mm×5 mm cross section and 10 mm in length. A sequence of pulses applied on a single variant induces an extension. It is close to linear with the pulse’s peak generated driving forces, for peaks in excess of 0.68×Ku, where Ku≃1.9×105 J/m3 is the magnetocrystalline anisotropy. The extension is caused by the motion of a few distinct twin boundaries, which exhibit differing driving-force thresholds for motion between 1.3 and 1.8×105 J/m3. Pulses applied without restoring the single-variant initial condition, cause discrete twin boundaries to expand in a stochastic manner consistent with the existence of obstacles to their motion. The number of obstacles is broadly distributed in pinning strengths, except for a peak near 0.56×Ku≃1.06×105 J/m3.
Longitudinal compression of short laser pulses in air
Authors: Alexeev I. , Ting A. , Gordon D. F. , Briscoe E. , Penano J. R. , Hubbard R. F. , Sprangle P.
Published: May 2004

We have performed laboratory experiments to study long distance propagation of large bandwidth ultrashort laser pulses in air. Initial pulse length, frequency chirping, and laser pulse energy were varied where the maximum propagation distance was up to 105 m. We have demonstrated the compression of initially negatively chirped low intensity laser pulses due to the linear group velocity dispersion of air. The characteristics of the compressed pulse such as pulse duration and spectral chirping were found to be significantly affected by the laser pulse intensity, with higher intensities corresponding to longer minimum compressed pulse duration.
High contrast polymer-dispersed liquid crystal in a 90° twisted cell
Authors: Lin Yi-Hsin , Ren Hongwen , Wu Shin-Tson
Published: May 2004

A polymer-dispersed liquid crystal confined in a 90° twisted cell (T-PDLC) is demonstrated. In comparison to a conventional PDLC, the T-PDLC is also polarization independent while exhibiting a higher contrast ratio. Potential applications of the T-PDLC are in polarizer-free reflective display and light switch. A black and white segmented-alphabet reflective display using a dye-doped T-PDLC is demonstrated.
Direct-write method for domain inversion patterns in LiNbO3
Authors: Dierolf V. , Sandmann C.
Published: May 2004

We have developed a technique to directly write stable ferroelectric domain patterns into lithium niobate crystals using visible light from an argon laser tightly focused to a diffraction limited spot in a confocal luminescence microscope. The patterns produced exhibit feature sizes down to 2 μm and show very little strain. The coercive field was reduced by as much as 30%. From the dynamics of the process, we attribute the reduction in coercive field to space charge fields produced by photoionization of defects. We have ruled out the possibility that the reduction in coercive field is simply a result of increased temperature by making local temperature measurements using the Stokes/anti-Stokes intensity ratio in confocal Raman measurements.
SU-8 for real three-dimensional subdiffraction-limit two-photon microfabrication
Authors: Teh W. H. , Dürig U. , Salis G. , Harbers R. , Drechsler U. , Mahrt R. F. , Smith C. G. , Güntherodt H.-J.
Published: May 2004

We report the inherent utility of two-photon-absorption (TPA) in the fabrication of real three-dimensional (3D) structures with subdiffraction-limit resolution, based on SU-8 as the threshold polymer media. We exploit the nonlinear velocity dependence of TPA photopolymerization as the shutter mechanism for disruptive 3D lithography. We show that low numerical aperture optics can be used for the rapid microfabrication of ultrahigh-aspect ratio photoplastic pillars, planes, and cage structures.
Influence of relative wafer rotation on the electrical properties of the bonded SiC/SiC interface
Authors: Yushin G. N. , Sitar Z.
Published: May 2004

Atomically clean SiC wafers with a root-mean-square roughness of 2 nm were bonded in ultrahigh vacuum at 20 MPa of applied uniaxial pressure at temperatures as low as 800 °C. Electrical measurements showed that azimuthal orientation of the bonded couple significantly influences the electrical character of the junction. A low-resistance ohmic interface can be created by high-temperature fusion of aligned 6H–SiC/6H–SiC wafers.
Raman characterization of 0.4 nm single-wall carbon nanotubes using the full-symmetry line group
Authors: Li Z. M. , Tang Z. K. , Siu G. G. , Bozovic I.
Published: May 2004

Raman spectra of single-wall carbon nanotubes produced in the channels of zeolite AFI single crystals have been analyzed in the light of the full symmetry group, the line group. The phonon dispersion curves of the tubes (5,0), (3,3), and (4,2) are calculated based on the lattice dynamical model and the phonon branches are assigned to their quantum numbers (irreducible representations). The structures of Raman spectra of different samples are reproduced well by the density of states of relevant Raman-active phonons. The result is useful to evaluate the contents of these tubes in real crystals where the contents are not well defined before.