bluuebunny/crossref_metadata_2025_split huggingface dataset:
A possible pharmacological explanation for quinacrine failure to treat prion diseases: pharmacokinetic investigations in a ovine model of scrapie
Authors: Gayrard Véronique , Picard‐Hagen Nicole , Viguié Catherine , Laroute Valerie , Andréoletti Olivier , Toutain Pierre‐Louis 
Published: January 2005

Quinacrine was reported to have a marked in vitro antiprion action in mouse neuroblastoma cells. On compassionate grounds, quinacrine was administered to Creutzfeldt–Jakob disease patients, despite the absence of preclinical in vivo studies to evaluate efficacy. Quinacrine failed to provide therapeutic benefit. The aim of the study was to investigate possible pharmacokinetic and/or pharmacodynamic explanations for the discrepancy between the proven action of quinacrine in vitro and its lack of clinical efficacy.
We conducted in vitro experiments reproducing the culture conditions in which antiprion effects had been previously observed and recalculated the EC50 by determining the actual extracellular (120 nM) and intracellular (6713 nM) quinacrine neuroblastoma concentrations with the reported quinacrine EC50 (300 nM).
A randomized clinical trial in scrapie‐affected ewes confirmed the absence of therapeutic benefit of quinacrine. The in vivo quinacrine exposure was evaluated in a pharmacokinetic investigation in healthy ewes. Cerebrospinal fluid concentrations (<10.6 and 55 nM after administration of therapeutic and toxic quinacrine doses, respectively) were much lower than the quinacrine extracellular neuroblastoma concentrations corresponding to the reported EC50. The total brain tissue concentrations (3556 nM) obtained after a repeated therapeutic dosage regimen were within the range of the intracellular neuroblastoma quinacrine concentrations.
In conclusion, in order to avoid in vivo trials for which failure can be predicted, the measurement in vitro of the antiprion EC50 in both intra‐ and extracellular biophases should be determined. It can then be established if these in vitro antiprion concentrations are achievable in vivo.

British Journal of Pharmacology (2005) 144, 386–393. doi:10.1038/sj.bjp.0706072
Role of basal extracellular Ca2+ entry during 5‐HT‐induced vasoconstriction of canine pulmonary arteries
Authors: Wilson Sean M , Mason Helen S , Ng Lih C , Montague Stephen , Johnston Louise , Nicholson Neil , Mansfield Sarah , Hume Joseph R 
Published: January 2005

Measurements of artery contraction, cytosolic [Ca2+], and Ca2+ permeability were made to examine contractile and cytosolic [Ca2+] responses of canine pulmonary arteries and isolated cells to 5‐hydroxytryptamine (5‐HT), and to determine the roles of intracellular Ca2+ release and extracellular Ca2+ entry in 5‐HT responses.
The EC50 for 5‐HT‐mediated contractions and cytosolic [Ca2+] increases was ∼10−7 M and responses were inhibited by ketanserin, a 5‐HT2A‐receptor antagonist.
5‐HT induced cytosolic [Ca2+] increases were blocked by 20 μM Xestospongin‐C and by 2‐APB (IC50=32 μM), inhibitors of InsP3 receptor activation.
5‐HT‐mediated contractions were reliant on release of InsP3 but not ryanodine‐sensitive Ca2+ stores.
5‐HT‐mediated contractions and cytosolic [Ca2+] increases were partially inhibited by 10 μM nisoldipine, a voltage‐dependent Ca2+ channel blocker.
Extracellular Ca2+ removal reduced 5‐HT‐mediated contractions further than nisoldipine and ablated cytosolic [Ca2+] increases and [Ca2+] oscillations. Similar to Ca2+ removal, Ni2+ reduced cytosolic [Ca2+] and [Ca2+] oscillations.
Mn2+ quench of fura‐2 and voltage‐clamp experiments showed that 5‐HT failed to activate any significant voltage‐independent Ca2+ entry pathways, including store‐operated and receptor‐activated nonselective cation channels. Ni2+ but not nisoldipine or Gd3+ blocked basal Mn2+ entry.
Voltage‐clamp experiments showed that simultaneous depletion of both InsP3 and ryanodine‐sensitive intracellular Ca2+ stores activates a current with linear voltage dependence and a reversal potential consistent with it being a nonselective cation channel. 5‐HT did not activate this current.
Basal Ca2+ entry, rather than CCE, is important to maintain 5‐HT‐induced cytosolic [Ca2+] responses and contraction in canine pulmonary artery.

British Journal of Pharmacology (2005) 144, 252–264. doi:10.1038/sj.bjp.0706077
Preclinical pharmacology of lumiracoxib: a novel selective inhibitor of cyclooxygenase‐2
Authors: Esser Ronald , Berry Carol , Du Zhengming , Dawson Janet , Fox Alyson , Fujimoto Roger A , Haston William , Kimble Earl F , Koehler Julie , Peppard Jane , Quadros Elizabeth , Quintavalla Joseph , Toscano Karen , Urban Laszlo , van Duzer John , Zhang Xiaoli , Zhou Siyuan , Marshall Paul J 
Published: January 2005

This manuscript presents the preclinical profile of lumiracoxib, a novel cyclooxygenase‐2 (COX‐2) selective inhibitor.
Lumiracoxib inhibited purified COX‐1 and COX‐2 with Ki values of 3 and 0.06 μM, respectively. In cellular assays, lumiracoxib had an IC50 of 0.14 μM in COX‐2‐expressing dermal fibroblasts, but caused no inhibition of COX‐1 at concentrations up to 30 μM (HEK 293 cells transfected with human COX‐1).
In a human whole blood assay, IC50 values for lumiracoxib were 0.13 μM for COX‐2 and 67 μM for COX‐1 (COX‐1/COX‐2 selectivity ratio 515).
Lumiracoxib was rapidly absorbed following oral administration in rats with peak plasma levels being reached between 0.5 and 1 h.
Ex vivo, lumiracoxib inhibited COX‐1‐derived thromboxane B2 (TxB2) generation with an ID50 of 33 mg kg−1, whereas COX‐2‐derived production of prostaglandin E2 (PGE2) in the lipopolysaccharide‐stimulated rat air pouch was inhibited with an ID50 value of 0.24 mg kg−1.
Efficacy of lumiracoxib in rat models of hyperalgesia, oedema, pyresis and arthritis was dose‐dependent and similar to diclofenac. However, consistent with its low COX‐1 inhibitory activity, lumiracoxib at a dose of 100 mg kg−1 orally caused no ulcers and was significantly less ulcerogenic than diclofenac (P<0.05).
Lumiracoxib is a highly selective COX‐2 inhibitor with anti‐inflammatory, analgesic and antipyretic activities comparable with diclofenac, the reference NSAID, but with much improved gastrointestinal safety.

British Journal of Pharmacology (2005) 144, 538–550. doi:10.1038/sj.bjp.0706078
Effects of minocycline on Fas‐mediated fulminant hepatitis in mice
Authors: Chu Heng‐Cheng , Lin Yi‐Ling , Sytwu Huey‐Kang , Lin Shin‐Hua , Liao Ching‐Len , Chao You‐Chen 
Published: January 2005

Minocycline has anti‐inflammatory and antiapoptotic effects on cartilage, neurons and periodontal tissues, and both properties are central to the pharmaceutical treatment of liver diseases. We investigated the effects of minocycline on fulminant hepatitis in C57BL/6J mice induced by lethal challenge of the activating anti‐Fas antibody, Jo2.
Intraperitoneal injection of Jo2 (0.6 μg g−1) to mice resulted in fulminant hepatitis, as evidenced by increase of serum alanine/aspartate transaminase activities and histopathological alterations in liver sections, as well as animal death. Nevertheless, mice pretreated with three doses of minocycline (5 mg kg−1) resisted this lethal effect significantly. Minocycline treatment improved the survival kinetics, although to a lesser extent, when mice were challenged simultaneously with Jo2 or even treated 30 min after the lethal challenge.
Jo2‐induced activation of caspase‐3 or ‐9 in liver tissues was inhibited by minocycline pretreatment, and yet the direct addition of minocycline to liver extracts from Jo2‐challenged mice failed to block caspase activation in vitro. Moreover, minocycline efficiently suppressed the release of cytochrome c from mitochondria of the liver tissues from Jo2‐challenged mice. In contrast, caspase‐8 activation and Bid truncation triggered by Jo2 were not diminished by minocycline pretreatment in mouse livers.
Our results suggest that easing of Fas‐triggered fulminant hepatitis by minocycline may involve a mitochondrial apoptotic pathway, probably through preventing cytochrome c release and thereby blocking downstream caspase activation.

British Journal of Pharmacology (2005) 144, 275–282. doi:10.1038/sj.bjp.0706079
TNF regulates leukocyte–endothelial cell interactions and microvascular dysfunction during immune complex‐mediated inflammation
Authors: Norman M Ursula , Lister Karyn J , Yang Yuan H , Issekutz Andrew , Hickey Michael J 
Published: January 2005

The aim of this study was to assess directly the role of TNF in immune complex‐induced leukocyte–endothelial cell interactions and microvascular dysfunction.
Intravital microscopy was used to examine immune complex‐induced leukocyte rolling, adhesion and emigration and microvascular permeability in cremasteric postcapillary venules in wild‐type and TNF−/− mice. The reverse passive Arthus (RPA) reaction was used to localize immune complex formation to the cremaster muscle.
In wild‐type mice, immune complex deposition induced a reduction in leukocyte rolling velocity and increases in leukocyte adhesion and emigration. In TNF−/− mice, the immune complex‐induced reduction in leukocyte rolling velocity was significantly attenuated, and leukocyte adhesion and emigration were also significantly reduced relative to responses in wild‐type mice.
The alterations in TNF−/− mice were associated with decreased expression of endothelial P‐selectin and VCAM‐1, and an absence of E‐selectin‐dependent rolling normally seen in wild‐type mice at the peak of the response. In addition, the level of immune complex‐induced microvascular permeability was attenuated in TNF−/− mice.
These findings demonstrate that in immune complex‐induced inflammation, TNF promotes leukocyte rolling and adhesive interactions, and entry of leukocytes into sites of immune complex deposition, in part via the increased expression and/or function of endothelial P‐selectin, E‐selectin and VCAM‐1. In addition, this increase in leukocyte recruitment mediated by TNF correlates directly with an increase in microvascular injury.

British Journal of Pharmacology (2005) 144, 265–274. doi:10.1038/sj.bjp.0706081
Blockade of glutamatergic and GABAergic receptor channels by trimethyltin chloride
Authors: Krüger Katharina , Diepgrond Victoria , Ahnefeld Maria , Wackerbeck Christina , Madeja Michael , Binding Norbert , Musshoff Ulrich 
Published: January 2005

Organotin compounds such as trimethyltin chloride (TMT) are among the most toxic of the organometallics. As their main target for toxicity is the central nervous system, the aim of the present study was to investigate the effects of TMT on receptor channels involved in various processes of synaptic transmission.
The Xenopus oocyte expression system was chosen for direct assessment of TMT effects on voltage‐operated potassium channels and glutamatergic and GABAergic receptors, and hippocampal slices from rat brain for analyzing TMT effects on identified synaptic sites.
TMT was found to be ineffective, at 100 μmol l−1, against several potassium‐ and sodium‐operated ion channel functions as well as the metabotropic glutamate receptor.
The functions of the ionotropic glutamate and the GABAA receptor channels were inhibited by TMT in micromolar concentrations. Thus, at a maximum concentration of 100 μmol l−1, around 20–30% of the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid and GABAA receptor‐mediated ion currents and 35% of the N‐methyl‐D‐aspartate receptor‐mediated ion currents were blocked.
In the hippocampal slice model, the inhibitory effects of TMT were much stronger than expected from the results on the ion channels. Bath application of TMT significantly reduced the amplitudes of evoked excitatory postsynaptic field potentials in a concentration‐dependent and nonreversible manner.
Induction of long‐term potentiation, recorded from the CA1 dendritic region, was inhibited by TMT and failed completely at a concentration of 10 μmol l−1.
In general, TMT affects the excitatory and inhibitory synaptic processes in a receptor specific manner and is able to disturb the activity within a neuronal network.

British Journal of Pharmacology (2005) 144, 283–292. doi:10.1038/sj.bjp.0706083
Dextromethorphan differentially affects opioid antinociception in rats
Authors: Chen Shiou‐Lan , Huang Eagle Yi‐Kung , Chow Lok‐Hi , Tao Pao‐Luh 
Published: January 2005

Opioid drugs such as morphine and meperidine are widely used in clinical pain management, although they can cause some adverse effects. A number of studies indicate that N‐methyl‐D‐aspartate (NMDA) receptors may play a role in the mechanism of morphine analgesia, tolerance and dependence. Being an antitussive with NMDA antagonist properties, dextromethorphan (DM) may have some therapeutic benefits when coadministered with morphine. In the present study, we investigated the effects of DM on the antinociceptive effects of different opioids. We also investigated the possible pharmacokinetic mechanisms involved.
The antinociceptive effects of the μ‐opioid receptor agonists morphine (5 mg kg−1, s.c.), meperidine (25 mg kg−1, s.c.) and codeine (25 mg kg−1, s.c.), and the κ‐opioid agonists nalbuphine (8 mg kg−1, s.c.) and U‐50,488H (20 mg kg−1, s.c.) were studied using the tail‐flick test in male Sprague–Dawley rats. Coadministration of DM (20 mg kg−1, i.p.) with these opioids was also performed and investigated.
The pharmacokinetic effects of DM on morphine and codeine were examined, and the free concentration of morphine or codeine in serum was determined by HPLC.
It was found that DM potentiated the antinociceptive effects of some μ‐opioid agonists but not codeine or κ‐opioid agonists in rats. DM potentiated morphine's antinociceptive effect, and acutely increased the serum concentration of morphine. In contrast, DM attenuated the antinociceptive effect of codeine and decreased the serum concentration of its active metabolite (morphine).
The pharmacokinetic interactions between DM and opioids may partially explain the differential effects of DM on the antinociception caused by opioids.

British Journal of Pharmacology (2005) 144, 400–404. doi:10.1038/sj.bjp.0706086
Piglet saphenous vein contains multiple relaxatory prostanoid receptors: evidence for EP4, EP2, DP and IP receptor subtypes
Authors: Wilson Richard J , Giles Heather 
Published: January 2005

Prostaglandin E2 produced endothelium‐independent relaxation of phenylephrine‐ and 5‐HT‐contracted piglet saphenous vein (PSV; pEC50=8.6±0.2; n=6).
The prostanoid EP4 receptor antagonist GW627368X (30–300 nM) produced parallel rightward displacement of PGE2 concentration–effect (E/[A]) curves (pKb=9.2±0.2; slope=1). Higher concentrations of GW627368X did not produce further rightward shifts, revealing the presence of non‐EP4 prostanoid receptors.
In all, 18 other prostanoid receptor agonists relaxed PSV in a concentration‐related manner. Relative potencies of agonists most sensitive to 10 μM GW627368X (and therefore predominantly activating EP4 receptors) correlated well with those at human recombinant EP4 receptors in human embryonic kidney (HEK‐293) cells (r2=0.74).
In the presence of 10 μM GW627368X, the rank order of agonist relative potency matched that of the human recombinant EP2 receptor in Chinese hamster ovary cells (r2=0.72).
Iloprost, cicaprost and PGI2 relaxed PSV maximally and were antagonised by 10 μM GW627368X, demonstrating that they were full EP4 receptor agonists. Residual responses to these compounds in the presence of GW627368X suggested the presence of IP receptors.
BW245C relaxed PSV maximally (pEC50=6.8±0.1). In the presence of 10 μM GW627368X, BW245C produced biphasic E/[A] curves (phase one pEC50=6.6; α=24%; phase two pEC50=5.1; α=112%). Phase two was antagonised by the DP receptor antagonist BW A868C (1 μM), demonstrating that BW245C is an agonist at DP and EP4 receptors.
We conclude that PSV contains EP4, EP2, DP and IP receptors; IP receptor agonists are also porcine EP4 receptor agonists.

British Journal of Pharmacology (2005) 144, 405–415. doi:10.1038/sj.bjp.0706088
Insights into the functional roles of α1‐adrenoceptor subtypes in mouse carotid arteries using knockout mice
Authors: Deighan Clare , Methven Laura , Naghadeh Mustafa M , Wokoma Alexis , Macmillan Joyce , Daly Craig J , Tanoue Akito , Tsujimoto Gozoh , McGrath John C 
Published: January 2005

α1‐Adrenoceptor (AR) subtypes in mouse carotid arteries were characterised using a combination of agonist/antagonist pharmacology and knockout (KO) mice.
Phenylephrine (PE) was most potent in the α1B‐KO (pEC50=6.9±0.2) followed by control (pEC50=6.3±0.06) and α1D‐KO (pEC50=5.5±0.07). Both N‐[5‐(4,5‐dihydro‐1H‐imidazol‐2yl)‐2‐hydroxy‐5,6,7,8‐tetrahydronaphthalen‐1‐yl] methanesulphonamide hydrobromide (A‐61603) and 5‐hydroxytryptamine (5‐HT) were more potent in the α1D‐KO (pEC50=7.4±0.27 and 7.4±0.05, respectively) than the control (pEC50=6.9±0.09 and 6.9±0.08, respectively) and equipotent with the control in the α1B‐KO (pEC50=6.7±0.07 and 6.8±0.04). Maximum responses to PE and A‐61603 were reduced in the α1D‐KO compared to control; there was no difference in maximum responses to 5‐HT.
In control arteries, prazosin and 5‐methylurapidil acted competitively with pA2 of 9.6 and 7.5, respectively. BMY7378 produced antagonism only at the highest concentration used (100 nM; pKB 8.3).
Prazosin, 5‐methylurapidil and BMY7378 acted competitively in α1B‐KO carotid arteries with pA2 of 10.3, 7.6 and 9.6, respectively.
In the α1D‐KO, against PE, 5‐methylurapidil produced a pA2 of 8.1. pKB values were calculated for prazosin (10.6) and BMY7378 (7.0). Against A‐61603, 5‐methylurapidil had a pA2 of 8.5, prazosin 8.6, while BMY7378 had no effect.
In conclusion, the α1B‐KO mediates contraction solely through α1D‐ARs and the α1D‐KO through α1A‐ARs. Extrapolating back to the control from the knockout data suggests that all three subtypes could be involved in the responses, but we propose that the α1D‐AR causes the contractile response and that the role of the α1B‐AR is mainly regulatory.

British Journal of Pharmacology (2005) 144, 558–565. doi:10.1038/sj.bjp.0706089
An investigation of whether agonist‐selective receptor conformations occur with respect to M2 and M4 muscarinic acetylcholine receptor signalling via Gi/o and Gs proteins
Authors: Mistry Rajendra , Dowling Mark R , Challiss R A John 
Published: January 2005

A range of muscarinic acetylcholine (mACh) receptor agonists (methacholine (MCh), oxotremorine‐M (OXO‐M), oxotremorine (OXO), arecoline (AREC), bethanechol (BETH), pilocarpine (PILO)) have been investigated with respect to their binding to, and activation of, M2 and M4 mACh receptors, recombinantly expressed in Chinese hamster ovary cells, to explore the possibility that these agonists may differentially affect mACh receptor–Gi/o and ‐Gs coupling.
M2/M4 mACh receptor coupling to the adenylyl cyclase/cyclic AMP signalling pathway has been explored in intact cells. Gi/o‐mediated negative coupling to adenylyl cyclase was explored functionally by assessing the ability of the mACh receptor agonists to inhibit forskolin‐stimulated enzymic activity. Following pertussis toxin treatment (100 ng ml−1, 18–20 h) to inactivate Gi/o proteins, each agonist caused a Gs‐mediated enhancement of forskolin‐stimulated adenylyl cyclase activity.
At both M2 and M4 mACh receptors, all agonists tested were more potent in mediating Gi/o‐ versus Gs‐coupled responses. This difference (determined as the pIC50 (Gi/o coupling) minus pEC50 (Gs coupling) value) was greatest for AREC (65–75‐fold) and least for BETH and PILO (10‐fold).
Using apparent binding affinities (pKB), and potency (EC50/IC50) and responsiveness (Emax/Imax) estimates, relative efficacy (erel) values for each agonist with respect to M2 and M4 mACh receptor coupling to Gi/o‐ and Gs‐mediated signalling were also calculated. While the erel values obtained for MCh and OXO‐M in CHO‐m2 cells were similar, OXO‐M behaved as a ‘super‐agonist’ at the M4 mACh receptor giving greater erel values for both Gi/o and Gs coupling relative to MCh.
The experimental data indicate that while interesting differences between agonists with respect to M2/M4 mACh receptor activation and receptor–Gi/o and ‐Gs coupling can be discerned, no clear examples of agonist trafficking of signal have emerged.

British Journal of Pharmacology (2005) 144, 566–575. doi:10.1038/sj.bjp.0706090
Reciprocal changes in endothelium‐derived hyperpolarizing factor‐ and nitric oxide‐system in the mesenteric artery of adult female rats following ovariectomy
Authors: Nawate Satoshi , Fukao Mitsuhiro , Sakuma Ichiro , Soma Takamitsu , Nagai Kazuhiko , Takikawa Osamu , Miwa Soichi , Kitabatake Akira 
Published: January 2005

To explore the effects of estrogen on arterial functions, we examined endothelium‐derived hyperpolarizing factor (EDHF)‐ and NO‐mediated responses in isolated mesenteric arteries of female rats, 4 weeks after sham‐operation (CON), ovariectomy (OVX) and OVX plus chronic estrogen treatment (OVX+E2). Tissue levels of connexins‐40, 43 (major components of gap junction), inducible NOS (iNOS), endothelial NOS (eNOS) and eNOS regulator proteins such as calmodulin, heat shock protein 90 (hsp90) and caveolin‐1 were also examined using Western blot.
In OVX, acetylcholine (ACh)‐induced EDHF‐mediated relaxation and membrane hyperpolarization of arterial smooth muscles were reduced, whereas ACh‐induced NO‐mediated relaxation was enhanced, leading to no change in ACh‐induced relaxation.
In OVX, connexin‐40 and 43 were decreased. Tissue levels of eNOS and its positive regulators (calmodulin and hsp90) were unchanged, but that of its negative regulator, caveolin‐1, was decreased. The levels of iNOS in mesenteric artery and aorta and plasma levels of NO metabolites and cholesterol were elevated.
In OVX, contraction of the artery by phenylephrine was reduced, but augmented by nonspecific inhibitor of NOS to the comparable level as that in CON group. The contraction in OVX group unlike that in CON group was augmented by specific iNOS inhibitor, and the difference between contractions in the presence of nonspecific and specific inhibitor as an index of eNOS activity was increased.
In OVX+E2, all these changes were recovered.
In all groups, EDHF‐mediated relaxation was suppressed by 18β‐glycyrrhetinic acid, an inhibitor of gap junction.
These results indicate that estrogen deficiency does not change the diameter of mesenteric artery: it reduces EDHF‐mediated relaxation by decreasing gap junction, whereas it augments NO‐mediated relaxation via an increase in NO release. Increased NO result from increased activity of eNOS subsequent to a decrease in caveolin‐1 and from induction of iNOS. However, excessive NO generation with elevated plasma cholesterol would raise a risk for atherosclerosis.

British Journal of Pharmacology (2005) 144, 178–189. doi:10.1038/sj.bjp.0706091