bluuebunny/crossref_metadata_2025 huggingface dataset:
Purification of a neuroprotective component of Parawixia bistriata spider venom that enhances glutamate uptake
Authors: Fontana Andréia Cristina Karklin , Guizzo Renato , Beleboni Renê de Oliveira , Meirelles e Silva Antonio Renato , Coimbra Norberto Cysne , Amara Susan G , Santos Wagner Ferreira dos , Coutinho‐Netto Joaquim
Published: July 2003

In this study, we examined the effects of crude venom from the spider Parawixia bistriata on glutamate and GABA uptake into synaptosomes prepared from rat cerebral cortex. Addition of venom to cortical synaptosomes stimulated glutamate uptake and inhibited GABA uptake in a concentration‐dependent manner.

The venom was fractionated using reverse‐phase high‐performance liquid chromatography on a preparative column. The fraction that retained glutamate uptake‐stimulating activity was further purified on a reverse‐phase analytical column followed by ion‐exchange chromatography.

The active fraction, referred to as PbTx1.2.3, stimulated glutamate uptake in synaptosomes without changing the KM value, and did not affect GABA uptake. Additional experiments showed that the enhancement of glutamate uptake by PbTx1.2.3 occurs when ionotropic glutamate receptors or voltage‐gated sodium and calcium channels are completely inhibited or when GABA receptors and potassium channels are activated, indicating that the compound may have a direct action on the transporters.

In an experimental model for glaucoma in which rat retinas are subjected to ischemia followed by reperfusion, PbTx1.2.3 protected neurons from excitotoxic death in both outer and inner nuclear layers, and ganglion cell layers.

This active spider venom component may serve as a basis for designing therapeutic drugs that increase glutamate clearance and limit neurodegeneration.

British Journal of Pharmacology (2003) 139, 1297–1309. doi:10.1038/sj.bjp.0705352
Evidence that 5‐lipoxygenase and acetylated cyclooxygenase 2‐derived eicosanoids regulate leukocyte–endothelial adherence in response to aspirin
Authors: Fiorucci Stefano , Distrutti Eleonora , Mencarelli Andrea , Morelli Antonio , Laufor Stefan A , Cirino Giuseppe , Wallace John L
Published: July 2003

Unlike other nonsteroidal anti‐inflammatory drugs that inhibit formation of cyclooxygenase (COX)‐dependent eicosanoids, acetylation of COX‐2 by aspirin switches eicosanoid biosynthesis from prostaglandin E2 (PGE2) to 15‐epi‐lipoxin A4 (15‐epi‐LXA4 or aspirin‐triggered lipoxin, ATL). ATL formation by activated leukocytes (PMN) requires the intervention of 5‐lipoxygenase (5‐LOX), an enzyme that is involved in leukotriene B4 (LTB4) formation.

In the present study, we have examined the role of acetylated COX‐2 and 5‐LOX in modulating antiadhesive effects of aspirin on adhesion of PMN to endotoxin (LPS)‐primed human umbilical endothelial cells (HUVEC).

Treating PMN/HUVEC cocultures with aspirin resulted in a concentration‐dependent inhibition of cell‐to‐cell adhesion induced by LPS. Treating HUVEC with selective COX‐2 inhibitors, celecoxib and rofecoxib, caused an ∼70% reversion of antiadhesive effect of aspirin. In contrast, inhibition of neutrophil's 5‐LOX pathway with 1 μM ZD2138, a selective 5‐LOX inhibitor, 1 μM BAY‐X‐1005, a FLAP inhibitor, or 100 μM licofelone, a dual COX/5‐LOX inhibitor, did not affect antiadhesive properties of aspirin.

Exposure to celecoxib (100 μM) or rofecoxib (10 μM) completely suppressed ATL formation caused by aspirin without affecting LTB4 levels. ZD2138, licofelone and BAY‐X‐1005 inhibited ATL formation as well as LTB4 generation.

Treatment with LXA4 reduced PMN adhesion to HUVEC and counteracted the proadhesive effect of celecoxib. In contrast, exposure to Boc‐1, an LXA4 antagonist, counteracts the antiadhesive activities of aspirin. Exposure to U75302, an LTB4 receptor antagonist, enhances the antiadesive effect of aspirin.

Reversal of antiadhesive activities of aspirin by celecoxib was associated with increased expression of LFA‐1 on PMN and E‐selectin on HUVEC. Addition of LXA4, ZD2138 and U75302 inhibited these changes.

The present results support the notion that inhibition of ATL formation is mechanistically linked to the reversal of the antiadhesive activity of aspirin caused by selective COX‐1 inhibitors and suggests that the LTB4/ATL balance modulates pro‐ and antiadhesive activity of nonsteroidal anti‐inflammatory drugs at the leukocyte–endothelial cell interface.

British Journal of Pharmacology (2003) 139, 1351–1359. doi:10.1038/sj.bjp.0705356
Diadenosine‐5‐phosphate exerts A1‐Receptor‐mediated proarrhythmic effects in rabbit atrial myocardium
Authors: Brandts B , Borchard R , Dirkmann D , Wickenbrock I , Sievers B , van Bracht M , Prull M W , Trappe H ‐J
Published: July 2003

Diadenosine polyphosphates have been described to be present in the myocardium and exert purinergic‐ and nonreceptor‐mediated effects. Since the electrophysiological properties of atrial myocardium are effectively regulated by A1 receptors, we investigated the effect of diadenosine pentaphosphate (Ap5A) in rabbit myocardium.

Parameters of supraventricular electrophysiology and atrial vulnerability were measured in Langendorff‐perfused rabbit hearts. Muscarinic potassium current (IK(ACh/Ado)) and ATP‐sensitive potassium current (IK(ATP)) were measured by using the whole‐cell voltage clamp method.

Ap5A prolonged the cycle length of spontaneously beating Langendorff perfused hearts from 225±14 (control) to 1823±400 ms (Ap5A 50 μM; n=6; P<0.05). This effect was paralleled by higher degree of atrio‐ventricular block. Atrial effective refractory period (AERP) in control hearts was 84±14 ms (n=6). Ap5A1 μM reduced AERP (100 μM, 58±11 ms; n=6).

Extrastimuli delivered to hearts perfused with Ap5A‐ or adenosine ( μM)‐induced atrial fibrillation, the incidence of which correlated to the concentration added to the perfusate. The selective A1‐receptor antagonist CPX (20 μM) inhibited the Ap5A‐ and adenosine‐induced decrease of AERP. Atrial fibrillation was no longer observed in the presence of CPX.

The described Ap5A‐induced effects in the multicellular preparation were enhanced by dipyridamole (10 μM), which is a cellular adenosine uptake inhibitor. Dipyridamole‐induced enhancement was inhibited by CPX.

Ap5A (1 mM) did neither induce IK(Ado) nor IK(ATP). No effect on activated IK(Ado/ATP) was observed in myocytes superfused with Ap5A. However, effluents from Langendorff hearts perfused with Ap5A 100 μM activated IK(Ado) by using A1 receptors.

Ap5A did not activate A1 receptors in rabbit atrial myocytes. The Ap5A induced A1‐receptor‐mediated effects on supraventricular electrophysiology and vulnerability suggest that in the multicellular preparation Ap5A is hydrolyzed to yield adenosine, which acts via A1 receptors. An influence on atrial electrophysiology or a facilitation of atrial fibrillation under conditions resulting in increased interstitial Ap5A concentrations might be of physiological/pathophysiological relevance.

British Journal of Pharmacology (2003) 139, 1265–1272. doi:10.1038/sj.bjp.0705361
Protective effects of curcumin against amiodarone‐induced pulmonary fibrosis in rats
Authors: Punithavathi Durairaj , Venkatesan Narayanan , Babu Mary
Published: July 2003

We have studied whether curcumin prevents amiodarone‐induced lung fibrosis in rats. Intratracheal instillation of amiodarone (6.25 mg kg−1 on days 0 and 2, and then killed on day 3, day 5, week 1, week 3 and week 5 after amiodarone administration) induced increases in total protein and lactate dehydrogenase (LDH) activity on days 3 and 5 in bronchoalveolar lavage fluid (BALF). Total cell counts, alveolar macrophages, neutrophils and eosinophils recovered by BAL, and lung myeloperoxidase (MPO) activity were significantly higher in amiodarone rats.

Tumor necrosis factor‐α (TNF‐α) release after lipopolysaccharide (LPS) stimulation and superoxide anion generation after phorbol myristate acetate (PMA) stimulation were higher in the alveolar macrophages of amiodarone rats at 3 and 5 weeks postamiodarone instillation than in controls. Amiodarone also induced increases in transforming growth factor‐β1 (TGF‐β1) expression, collagen deposition, type I collagen expression and c‐Jun protein in lungs.

Curcumin (200 mg kg−1 body weight after first amiodarone instillation and daily thereafter for 5 weeks)‐treated amiodarone rats had reduced levels of protein, LDH activity, total cell numbers and differential cell counts in BALF. LPS‐stimulated TNF‐α release and PMA‐stimulated superoxide generation were significantly suppressed by curcumin. Furthermore, curcumin inhibited the increases in lung MPO activity, TGF‐β1 expression, lung hydroxyproline content, expression of type I collagen and c‐Jun protein in amiodarone rats. Our results have important implications for the treatment of amiodarone‐induced lung fibrosis.

British Journal of Pharmacology (2003) 139, 1342–1350. doi:10.1038/sj.bjp.0705362
Local anaesthetics block hyperpolarization‐activated inward current in rat small dorsal root ganglion neurones
Authors: Bischoff Ulrike , Bräu Michael E , Vogel Werner , Hempelmann Gunter , Olschewski Andrea
Published: July 2003

Hyperpolarizing voltage steps evoke slowly activating inward currents in a variety of neurones and in cardiac cells. This hyperpolarization‐activated inward current (Ih) is thought to play a significant role in cell excitability, firing frequency, or in setting of the resting membrane potential in these cells. We studied the effects of lidocaine, mepivacaine, QX‐314 and bupivacaine as well as its enantiomers on Ih in the membrane of dorsal root ganglion neurones (DRG).

The patch‐clamp technique was applied to small dorsal root ganglion neurones identified in 200 μM thin slices of young rat DRGs. Under voltage‐clamp conditions, the whole‐cell Ih current was recorded in the presence of different concentrations of the local anaesthetics. In current‐clamp mode the resting membrane potential and the voltage response of DRG neurones to injected current pulses were investigated.

Ih was reversibly blocked by bupivacaine, lidocaine and mepivacaine applied externally in clinically relevant concentrations. Concentration–response curves gave half‐maximum inhibiting concentrations of 55, 99 and 190 μM, respectively. Bupivacaine block of the Ih current was not stereoselective. No significant effect was observed when QX‐314 was applied to the external surface of the membrane.

In current‐clamp experiments 60 μM bupivacaine slightly hyperpolarized the membrane. The membrane stimulation by low‐amplitude current pulses in the presence of bupivacaine showed an increase of the hyperpolarizing responses.

Our findings suggest an important role of the Ih‐block by local anaesthetics in the complex mechanism of drug action during epidural and spinal anaesthesia.

British Journal of Pharmacology (2003) 139, 1273–1280. doi:10.1038/sj.bjp.0705363
Structural requisites of 2‐(p‐chlorophenoxy)propionic acid analogues for activity on native rat skeletal muscle chloride conductance and on heterologously expressed CLC‐1
Authors: Liantonio Antonella , De Luca Annamaria , Pierno Sabata , Didonna Maria Paola , Loiodice Fulvio , Fracchiolla Giuseppe , Tortorella Paolo , Laghezza Antonio , Bonerba Elisabetta , Traverso Sonia , Elia Laura , Picollo Alessandra , Pusch Michael , Camerino Diana Conte
Published: July 2003

The 2‐(p‐chlorophenoxy)propionic acid (CPP) modulates in a stereoselective manner the macroscopic chloride conductance (gCl), the electrical parameter sustained by the CLC‐1 channel, of skeletal muscle. In order to determine the structural requirements for modulating native gCl and to identify high‐affinity ligands, the effects of newly synthesised CPP analogues have been evaluated on gCl of rat EDL muscle fibres by means of the two‐microelectrode current‐clamp technique.

Each type of the following independent modification of CPP structure led to a three‐ to 10‐fold decrease or to a complete lack of gCl‐blocking activity: replacement of the electron‐attractive chlorine atom of the aromatic ring, substitution of the oxygen atom of the phenoxy group, modification at the chiral centre and substitution of the carboxylic function with a phosphonate one.

The analogues bearing a second chlorophenoxy group on the asymmetric carbon atom showed a significant gCl‐blocking activity. Similar to racemate CPP, the analogue with this group, spaced by an alkyl chain formed by three methylenic groups, blocked gCl by 45% at 100 μM.

These latter derivatives were tested on heterelogously expressed CLC‐1 performing inside‐out patch‐clamp recordings to further define how interaction between drug and channel protein could take place. Depending on the exact chemical nature of modification, these derivatives strongly blocked CLC‐1 with KD values at −140 mV ranging from about 4 to 180 μM.

In conclusion, we identified four molecular determinants pivotal for the interaction with the binding site on muscle CLC‐1 channels: (a) the carboxylic group that confers the optimal acidity and the negative charge; (b) the chlorophenoxy moiety that might interact with a hydrophobic pocket; (c) the chiral centre that allows the proper spatial disposition of the molecule; (d) an additional phenoxy group that remarkably stabilises the binding by interacting with a second hydrophobic pocket.

British Journal of Pharmacology (2003) 139, 1255–1264. doi:10.1038/sj.bjp.0705364
Vascular natriuretic peptide receptor‐linked particulate guanylate cyclases are modulated by nitric oxide–cyclic GMP signalling
Authors: Madhani Melanie , Scotland Ramona S , MacAllister Raymond J , Hobbs Adrian J
Published: July 2003

The sensitivity of the particulate guanylate cyclase–cyclic guanosine‐3′,5′‐monophosphate (cGMP) system to atrial (ANP) and C‐type (CNP) natriuretic peptides was investigated in aortae and mesenteric small arteries from wild‐type (WT) and endothelial nitric oxide synthase (eNOS) knockout (KO) mice.

ANP and CNP produced concentration‐dependent relaxations of mouse aorta that were significantly attenuated by the natriuretic peptide receptor (NPR)‐A/B antagonist HS‐142‐1 (10−5 M). Both ANP and CNP were more potent in aortae from eNOS KO mice compared to WT.

The potency of ANP and CNP in aortae from WT animals was increased in the presence of the NOS inhibitor, NG‐nitro‐L‐arginine (3 × 10−4 M) and the soluble guanylate cyclase inhibitor 1H‐[1,2,4]oxadiazolol[4,3,a]quinoxalin‐1‐one (5 × 10−6 M).

In contrast, the potency of ANP and CNP in aortae from eNOS KO animals was reduced following pretreatment of tissues with supramaximal concentrations of the NO‐donor, glyceryl trinitrate (3 × 10−5 M, 30 min) or ANP (10−7 M, 30 min).

Responses to acetylcholine in aortae from WT mice (dependent on the release of endothelium‐derived NO) were significantly reduced following pretreatment of tissues with GTN (3 × 10−5 M, 30 min) and ANP (10−7 M, 30 min).

CNP and the NO‐donor, spermine‐NONOate caused concentration‐dependent relaxations of mesenteric small arteries from WT animals that were significantly increased in eNOS KO mice compared to WT. ANP was unable to significantly relax mesenteric arteries from WT or eNOS KO animals.

In conclusion, both NPR‐A‐ and NPR‐B‐linked pGC pathways are modulated by NO–cGMP in murine aorta and mesenteric small arteries and crossdesensitisation occurs between NPR subtypes. The biological activity of endothelium‐derived NO is also influenced by the ambient concentration of NO and natriuretic peptides. Such an autoregulatory pathway may represent an important physiological homeostatic mechanism and link the paracrine activity of NO and CNP with the endocrine functions of ANP and BNP in the regulation of vascular tone and blood pressure.

British Journal of Pharmacology (2003) 139, 1289–1296. doi:10.1038/sj.bjp.0705365
Increased peripheral resistance in heart failure: new evidence suggests an alteration in vascular smooth muscle function
Authors: Ledoux Jonathan , Gee Daniel M , Leblanc Normand
Published: July 2003

Increased peripheral resistance is a hallmark of chronic heart failure and has been primarily attributed to neurohumoral pathways involving both the renin–angiotensin and sympathetic nervous systems. The increased resistance is thought to serve as a compensatory mechanism to help maintain perfusion to the vital organs by sustaining blood pressure in the fate of a failing heart. Local mechanisms, and in particular endothelial dysfunction, have also been shown to be important contributors in regulating arterial resistance and vascular remodeling in this disease. In this issue of the British Journal of Pharmacology, Gschwend et al. (2003) present new data suggesting that in the absence of a functional endothelium, myogenic constriction of small pressurized mesenteric arteries, an intrinsic property of vascular smooth muscle cells, is enhanced in a coronary artery ligation‐induced myocardial infarction model of congestive heart failure (CHF) in the rat. The increased myogenic tone appears to be tightly linked to angiotensin II type 1 receptors (AT1). The possibility that CHF‐induced stimulation of myogenic constriction is due to the local release of preformed angiotensin II or constitutive upregulation of the AT1 receptor signaling pathways are discussed along with other potential cellular and molecular mechanisms previously suggested to play a role in myogenic reactivity.

British Journal of Pharmacology (2003) 139, 1245–1248. doi:10.1038/sj.bjp.0705366
Myogenic constriction is increased in mesenteric resistance arteries from rats with chronic heart failure: instantaneous counteraction by acute AT1 receptor blockade
Authors: Gschwend S , Henning R H , Pinto Y M , de Zeeuw D , van Gilst W H , Buikema H
Published: July 2003

Increased vascular resistance in chronic heart failure (CHF) has been attributed to stimulated neurohumoral systems. However, local mechanisms may also importantly contribute to set arterial tone. Our aim, therefore, was to test whether pressure‐induced myogenic constriction of resistance arteries in vitro – devoid of acute effects of circulating factors – is increased in CHF and to explore underlying mechanisms.

At 12 weeks after coronary ligation‐induced myocardial infarction or SHAM‐operations in rats, we studied isolated mesenteric arteries for myogenic constriction, determined as the active constriction (% of passive diameter) in response to stepwise increase in intraluminal pressure (20 – 160 mmHg), in the absence and presence of inhibitors of potentially involved modulators of myogenic constriction.

We found that myogenic constriction in mesenteric arteries from CHF rats was markedly increased compared to SHAM over the whole pressure range, the difference being most pronounced at 60 mmHg (24±2 versus 4±3%, respectively, P<0.001).

Both removal of the endothelium as well as inhibition of NO production (L‐NG‐monomethylarginine, 100 μM) significantly increased myogenic constriction (+16 and +25%, respectively), the increase being similar in CHF‐ and SHAM‐arteries (P=NS). Neither endothelin type A (ETA)‐receptor blockade (BQ123, 1 μM) nor inhibition of perivascular (sympathetic) nerve conduction (tetrodotoxin, 100 nM) affected the myogenic response in either group.

Interestingly, increased myogenic constriction in CHF was fully reversed after angiotensin II type I (AT1)‐receptor blockade (candesartan, 100 nM; losartan, 10 μM), which was without effect in SHAM. In contrast, neither angiotensin‐converting enzyme (ACE) inhibition (lisinopril, 1 μM; captopril, 10 μM) or AT2‐receptor blockade (PD123319, 1 μM), nor inhibition of superoxide production (superoxide dismutase, 50 U ml−1), TXA2‐receptor blockade (SQ29,548, 1 μM) or inhibition of cyclooxygenase‐derived prostaglandins (indomethacin, 10 μM) affected myogenic constriction.

Sensitivity of mesenteric arteries to angiotensin II (10 nM – 100 μM) was increased (P<0.05) in CHF (pD2 7.1±0.4) compared to SHAM (pD2 6.2±0.3), while the sensitivity to KCl and phenylephrine was not different.

Our results demonstrate increased myogenic constriction in small mesenteric arteries of rats with CHF, potentially making it an important target for therapy in counteracting increased vascular resistance in CHF. Our results further suggest active and instantaneous participation of AT1‐receptors in increased myogenic constriction in CHF, involving increased sensitivity of AT1‐receptors rather than apparent ACE‐mediated local angiotensin II production.

British Journal of Pharmacology (2003) 139, 1317–1325. doi:10.1038/sj.bjp.0705367
Acute effects of oestrogen receptor subtype‐specific agonists on vascular contractility
Authors: Montgomery Sandra , Shaw Linda , Pantelides Nick , Taggart Michael , Austin Clare
Published: July 2003

This study shows for the first time that both the putatively selective oestrogen receptor α and oestrogen receptor β agonists PPT (4,4′,4″‐(4‐propyl‐[1H]‐pyrazole‐1,3,5‐triyl) tris‐phenol) and DPN (2,3‐bis(4‐hydroxyphenyl)‐propionitrile) can acutely relax precontracted isolated rat mesenteric arteries at pharmacological (i.e. μM) concentrations. When compared to responses observed to similar concentrations of 17β‐oestrogen obtained on the same tissues, PPT had a significantly greater vasodilatory effect, while DPN had a significantly smaller effect. All responses were rapid being complete within 5 min exposure time. Thus, both PPT and DPN can acutely relax isolated mesenteric arteries with the relative potency of PPT>17β‐oestrogen>DPN.

British Journal of Pharmacology (2003) 139, 1249–1253. doi:10.1038/sj.bjp.0705368
Development and characterization of a highly selective neuropeptide Y Y5 receptor agonist radioligand: [125I][hPP1–17, Ala31, Aib32]NPY
Authors: Dumont Yvan , Thakur Mira , Beck‐Sickinger Annette , Fournier Alain , Quirion Rémi
Published: July 2003

The existence of multiple classes of neuropeptide Y (NPY) receptors (Y1, Y2, Y4, Y5and y6) is now well established. However, one of the major difficulties in the study of these various receptor subtypes is the current lack of highly selective probes to investigate a single receptor class. Up to most recently, this was particularly true for the Y4and Y5subtypes.

[hPP1–17, Ala31, Aib32]NPY, the first highly selective Y5agonist, was iodinated using the chloramine T method and purified by high‐pressure liquid chromatography.

Binding performed in rat brain homogenates revealed that equilibrium was reached after 120 min (t1/2=21 min) and 60 min (t1/2=12 min) at 25 and 100 pM[125I][hPP1–17, Ala31, Aib32]NPY, respectively.

Isotherm saturation binding experiments demonstrated that [125I][hPP1–17, Ala31, Aib32]NPY binds to an apparent single population with high‐affinity (KDof 1.2 and 1.7 nM) and low‐capacity (Bmaxof 14±3 fmol/100,000 cells and 20±5 fmol/mg protein) sites in Y5receptor HEK293‐transfected cells and rat brain membrane homogenates, respectively. No specific [125I][hPP1–17, Ala31, Aib32]NPY binding sites could be detected in Y1, Y2or Y4receptors transfected HEK293 cells, demonstrating the high selectivity of this ligand for the Y5subtype.

Competition binding experiments performed in rat brain membrane homogenates and Y5‐receptor transfected HEK293 cells demonstrated that specific [125I][hPP1–17, Ala31, Aib32]NPY binding was competed with high affinity by Y5agonists and antagonists such as [Ala31, Aib32]NPY, [hPP1–17, Ala31, Aib32]NPY, hPP, CGP71683A and JCF109, but not by Y1(BIBP3226), Y2(BIIE0246) and Y1/Y4(GR231118) preferential ligands.

Taken together, these data demonstrate that [125I][hPP1–17, Ala31, Aib32]NPY is the first highly selective Y5radioligand to be developed. This new probe should prove most useful for further detailed studies of the molecular and pharmacological properties of this receptor subtype in brain and peripheral tissues.

British Journal of Pharmacology(2003)139, 1360–1368. doi:10.1038/sj.bjp.0705376
Mechanisms of action of CHF3381 in the forebrain
Authors: Barbieri Mario , Bregola Gianni , Buzzi Andrea , Marino Silvia , Zucchini Silvia , Stables James P , Bergamaschi Marco , Pietra Claudio , Villetti Gino , Simonato Michele
Published: July 2003

Aim of this study was to gain insight into the mechanism of action of CHF3381, a novel putative antiepileptic and neuroprotective drug.

CHF3381 blocked NMDA currents in primary cultures of cortical neurons: maximal effect was nearly −80% of the NMDA‐evoked current, with EC50 of approximately 5 μM. This effect was selective, reversible, use‐dependent and elicited at the concentrations reached in the rodent brain after peripheral administration of therapeutic doses.

CHF3381 also inhibited voltage‐gated Na+ currents in an apparently voltage‐dependent manner. However, this effect could be obtained only at relatively high concentrations (100 μM).

Consistent with the mild effects on voltage‐gated Na+ channels, CHF3381 (100 μM) failed to affect electrical stimulation‐evoked glutamate overflow in hippocampal slices. In contrast, the anti‐convulsant agent and Na+ channel blocker lamotrigine (100 μM) inhibited stimulation‐evoked glutamate overflow by approximately 50%.

CHF3381 reduced kindled seizure‐induced c‐fos mRNA levels within the same brain regions, and to a similar level, as the selective NMDA receptor antagonist MK801, providing circumstantial evidence to the idea that CHF3381 blocks NMDA receptors in vivo.

The present mechanistic studies suggest that the primary mechanism of action of CHF3381 in the forebrain is blockade of NMDA receptors. On this basis, this compound may have a potential use in other diseases caused by or associated with a pathologically high level of NMDA receptor activation.

British Journal of Pharmacology (2003) 139, 1333–1341. doi:10.1038/sj.bjp.0705381
Melatonin inhibits nitrate tolerance in isolated coronary arteries
Authors: O'Rourke Stephen T , Hammad Hana , Delagrange Philippe , Scalbert Elizabeth , Vanhoutte Paul M
Published: July 2003

The present study was designed to test the hypothesis that melatonin inhibits nitrate tolerance in coronary arteries.

Rings of porcine coronary arteries were suspended in organ chambers for isometric tension recording. Nitrate tolerance was induced by incubating the tissues with nitroglycerin (10−4 M) for 90 min, followed by repeated rinsing for 1 h. Control rings that had not been exposed previously to nitroglycerin, but were otherwise treated identically, were studied simultaneously. The rings were contracted with U46619 (1–3 × 10−9 M) and concentration–response curves to nitroglycerin (10−9–10−4 M) were obtained.

Nitrate tolerance was evident by a 15‐ to 20‐fold rightward shift in the concentration–response curve to nitroglycerin in rings with and without endothelium exposed previously to the drug for 90 min. Addition of melatonin (10−9–10−7 M) to the organ chamber during the 90‐min incubation period with nitroglycerin partially inhibited nitrate tolerance in coronary arteries with intact endothelium; however, melatonin had no effect on nitrate tolerance in coronary arteries without endothelium.

The effect of melatonin on nitrate tolerance in coronary arteries with endothelium was abolished by the melatonin receptor antagonist, S20928 (10−6 M). In contrast to melatonin, the selective MT3‐melatonin receptor agonist, 5‐MCA‐NAT (10−8–10−7 M), had no effect on nitrate tolerance in coronary arteries.

The results demonstrate that melatonin, acting via specific melatonin receptors, inhibits nitrate tolerance in coronary arteries and that this effect is dependent on the presence of the vascular endothelium.

British Journal of Pharmacology (2003) 139, 1326–1332. doi:10.1038/sj.bjp.0705383
Malondialdehyde inhibits cardiac contractile function in ventricular myocytes via a p38 mitogen‐activated protein kinase‐dependent mechanism
Authors: Folden David V , Gupta Akanksha , Sharma Avadhesh C , Li Shi‐Yan , Saari Jack T , Ren Jun
Published: July 2003

Increased oxidative stress plays a significant role in the etiology of cardiovascular disease. Lipid peroxidation, initiated in the presence of hydroxy radicals resulting in the production of malondialdehyde, directly produces oxidative stress. This study was designed to examine the direct impact of malondialdehyde on ventricular contractile function at the single cardiac myocyte level. Ventricular myocytes from adult rat hearts were stimulated to contract at 0.5 Hz, and mechanical and intracellular Ca2+ properties were evaluated using an IonOptix Myocam® system. Contractile properties analyzed included peak shortening amplitude (PS), time‐to‐PS (TPS), time‐to‐90% relengthening (TR90), maximal velocity of shortening/relengthening (±dLdt), and Ca2+‐induced intracellular Ca2+ fluorescence release (CICR) and intracellular Ca2+ decay (τ). p38 mitogen‐activated protein (MAP) kinase phosphorylation was assessed with Western blot.

Our results indicated that malondialdehyde directly depressed PS, ±dLdt and CICR in a concentration‐dependent manner and shortened TPS without affecting TR90 and τ. Interestingly, the malondialdehyde‐induced cardiac mechanical effect was abolished by both the p38 MAP kinase inhibitor SB203580 (1 and 10 μM) and the antioxidant vitamin C (100 μM). Western blot analysis confirmed direct phosphorylation of p38 MAP kinase by malondialdehyde.

These findings revealed a novel role of malondialdehyde and p38 MAP kinase in lipid peroxidation and oxidative stress‐associated cardiac dysfunction.

British Journal of Pharmacology (2003) 139, 1310–1316. doi:10.1038/sj.bjp.0705384
Allosteric effects mediate CHK2 phosphorylation of the p53 transactivation domain
Authors: Craig Ashley , Scott Mary , Burch Lindsay , Smith Graeme , Ball Kathryn , Hupp Ted
Published: August 2003

The tumour suppressor p53 is a tetrameric protein that is phosphorylated in its BOX‐I transactivation domain by checkpoint kinase 2 (CHK2) in response to DNA damage. CHK2 cannot phosphorylate small peptide fragments of p53 containing the BOX‐I motif, indicating that undefined determinants in the p53 tetramer mediate CHK2 recognition. Two peptides derived from the DNA‐binding domain of p53 bind to CHK2 and stimulate phosphorylation of full‐length p53 at Thr 18 and Ser 20, thus identifying CHK2‐docking sites. CHK2 can be fully activated in trans by the two p53 DNA‐binding‐domain peptides, and can phosphorylate BOX‐I transactivation‐domain fragments of p53 at Thr 18 and Ser 20. Although CHK2 has a basal Ser 20 kinase activity that is predominantly activated towards Thr 18, CHK1 has constitutive Thr 18 kinase activity that is predominantly activated in trans towards Ser 20. Cell division cycle 25C (CDC25C) phosphorylation by CHK2 is unaffected by the p53 DNA‐binding‐domain peptides. The CHK2‐docking site in the BOX‐V motif is the smallest of the two CHK2 binding sites, and mutating certain amino acids in the BOX‐V peptide prevents CHK2 activation. A database search identified a p53 BOX‐I‐homology motif in p21WAF1 and although CHK2 is inactive towards this protein, the p53 DNA‐binding‐domain peptides induce phosphorylation of p21WAF1 at Ser 146. This provides evidence that CHK2 can be activated allosterically towards some substrates by a novel docking interaction, and identify a potential regulatory switch that may channel CHK2 into distinct signalling pathways in vivo.
Mild to moderate Crohn's disease – defining the basis for a new treatment algorithm
Authors: Sandborn W. J. , Feagan B. G.
Published: August 2003

Previously, clinicians have had few choices in treating mild to moderate Crohn's disease. They currently treat these Crohn's disease patients with oral mesalamine and antibiotics. This treatment approach is based on the safety of these agents, and the perception that they are effective. This perception regarding efficacy may be influenced by publication bias.

This review examines the efficacy and safety data of the conventional corticosteroids, mesalamine, sulfasalazine, budesonide and antibiotics for inducing the remission of mild to moderate Crohn's disease from randomized controlled trials, and proposes an evidence‐based treatment approach.

Sulfasalazine has demonstrated modest efficacy when Crohn's disease is confined to the colon. Mesalamine has no clear benefit over placebo in treating active Crohn's disease. Conventional corticosteroids effectively induce remission but are associated with unwanted adverse effects. Budesonide has similar efficacy to conventional steroids with far fewer adverse effects. Antibiotics have not consistently demonstrated efficacy.

We propose a new evidence‐based approach which suggests inducing remission of mild to moderate Crohn's disease with budesonide 9 mg/day for patients with ileal and/or right colonic involvement; sulfasalazine for those with disease limited to the colon; and conventional steroids for high disease activity, those who failed budesonide and those with left‐sided disease who are allergic or intolerant to sulfasalazine.
Coping strategies, illness perception, anxiety and depression of patients with idiopathic constipation: a population‐based study
Authors: Cheng C. , Chan A. O. O. , Hui W. M. , Lam S. K.
Published: August 2003

Background: Functional constipation has important psychological elements.

Aim: To investigate the prevalence of functional constipation in an Asian population, and the interplay among functional constipation, anxiety/depression, perception and coping strategies.

Methods: An interview of 3282 patients was made by telephone survey. Constipation was diagnosed by Rome II criteria. Coping ability and anxiety/depression were assessed by validated questionnaires.

Results: Fourteen percent of the interviewees had constipation. Anxiety and depression scores were higher in constipated than in healthy subjects (P < 0.0001 and < 0.0001), and in female than male patients (P = 0.02 and < 0.0001). Patients who were aware of their symptoms perceived greater impact on their lives (P < 0.001). Frequent use of coping strategies associated with lower anxiety scores (P < 0.0001). Female were more frequently aware of the symptoms (P = 0.004), less frequently used coping strategies (P = 0.008). Regression analysis showed that female and high anxiety level were the independent factors for predicting the perception of constipation, whereas anxiety was the only independent factor for predicting the use of coping strategies.

Conclusion: Constipation associated with anxiety and depression is prevalent in the general Asian population. Female sex and anxiety are important aetiological factors in constipation, affecting perception and the use of coping strategies.
Meta‐analysis: the relationship between Helicobacter pylori infection and gastro‐oesophageal reflux disease
Authors: Cremonini F. , Di Caro S. , Delgado‐Aros S. , Sepulveda A. , Gasbarrini G. , Gasbarrini A. , Camilleri M.
Published: August 2003

Background: The relationship between Helicobacter pylori infection and its treatment and gastro‐oesophageal reflux disease (GERD) is controversial.

Aims: To establish if H. pylori infection is associated with the presence of GERD and if anti‐H. pylori treatment leads to de novo GERD or rebound/exacerbation of GERD.

Methods: A search of MEDLINE and EMBASE databases was made. Pooled odds ratios (OR) were calculated for de novo GERD and rebound/exacerbated GERD after anti‐H. pylori therapy in case‐control studies and in therapeutic trials.

Results: Fourteen case‐control studies and 10 clinical trials were included. Among case‐control studies, pooled OR for the association between H. pylori negative status and GERD was 1.34 [95% confidence interval (CI) 1.15–1.55]. Among therapeutic trials, pooled OR for the association anti‐H. pylori therapy – GERD was 2.54 (95% CI 1.92–3.37). The OR for de novo GERD was 3.25 (95% CI 2.09–5.33), and for rebound/exacerbated GERD was 2.39 (95% CI 1.75–3.34). Associations were higher among Asian studies than among North American and European studies.

Conclusions: This meta‐analysis shows significant association between absence of H. pylori infection and GERD symptoms, and a positive association between anti‐H. pylori therapy and occurrence of both de novo and rebound/exacerbated GERD. The significance of these associations appears to have been inflated by the effect of single trials and by geographical variations.
CCK‐1 receptor blockade for treatment of biliary colic: a pilot study
Authors: Malesci A. , Pezzilli R. , D'Amato M. , Rovati L.
Published: August 2003

Background: Loxiglumide is a potent and selective cholecystokinin‐1 (CCK‐1) receptor antagonist able to inhibit gall‐bladder contraction.

Aim: To assess the effect of CCK‐1 receptor blockade on the pain of patients with biliary colic.

Patients and methods: Fourteen patients with biliary colic but no suspicion for acute cholecystitis, were randomly and blindly assigned to loxiglumide (50 mg i.v.) or hyoscine‐N‐butyl bromide (20 mg i.v.) treatment. Pain intensity was monitored by a Visual Analogue Scale. Patients with less than 80% response at 30 min, were retreated with a second injection of the same compound.

Results: Reduction in pain score (mean ± S.E.M.) was faster and significantly greater in patients treated with loxiglumide (n = 7) than in controls (n = 7): 88 ± 7% vs. 47 ± 12% after 20 min, P < 0.05; 92 ± 6% vs. 49 ± 13%, after 30 min, P < 0.05. Only one of seven patients treated with loxiglumide needed a second injection at 30 min (vs. six of seven controls, P < 0.05). No adverse effect was observed after either treatment.

Conclusions: Loxiglumide is highly effective in obtaining pain relief in patients with biliary colic. The analgesic effect of CCK‐1 receptor blockade is superior to that of a conventional anticholinergic treatment.
Use of the bougie in simulated difficult intubation. 2. Comparison of single‐use bougie with multiple‐use bougie*
Authors: Marfin A. G. , Pandit J. J. , Hames K. C. , Popat M. T. , Yentis S. M.
Published: August 2003

Summary We studied the success rates for tracheal intubation in 32 healthy, anaesthetised patients during simulated grade IIIa laryngoscopy, randomised to either the multiple‐use or the single‐use bougie. Success rates (primary end‐point) and times taken (secondary end‐point) to achieve tracheal intubation were recorded. The multiple‐use bougie was more successful than the single‐use one (15/16 successful intubations vs. 9/16; p = 0.03). With either device, median [range] total tracheal intubation times for successful attempts were < 54 [24–84] s and there were no clinically important differences between these times. We conclude that the multiple‐use bougie is a more reliable aid to tracheal intubation than the single‐use introducer in grade IIIa laryngoscopy.
Out of our reach? Assessing the impact of introducing a critical care outreach service
Authors: Pittard A. J.
Published: August 2003

An outreach service was introduced in three surgical wards and the surgical high dependency unit in a large teaching hospital. A modified early warning score and callout algorithm were used to facilitate referrals to the team. Changes in unplanned admission rate to intensive care, length of stay, mortality rate and number of re‐admissions following the introduction of outreach were sought. Following the introduction of the outreach service the emergency admission rate to intensive care fell from 58% to 43% (p = 0.05). These emergency patients had shorter lengths of stay (4.8 days vs. 7.4 days) and had a lower mortality (28.6% vs. 23.5%, p = 0.05). The re‐admission rate also fell from 5.1% to 3.3% (p = 0.05). The outreach service had a significant impact on critical care utilisation.
Validation of a pre‐anaesthetic screening questionnaire
Authors: Hilditch W. G. , Asbury A. J. , Jack E. , McGrane S.
Published: August 2003

Summary We developed a screening questionnaire to be used by nurses to decide which patients should see an anaesthetist for further evaluation before the day of surgery. Our objective was to measure the accuracy of responses to the questionnaire. Agreement between questionnaire responses and the anaesthetist's assessment was assessed. For questions with a prevalence of 5 to 95%, the Kappa coefficient was used; percentage agreement was used for all other questions. Criterion validity was excellent/good for all questions with a prevalence between 5 and 95%, except for the question ‘Do you have kidney disease?’ For questions with prevalence < 5%, all demonstrated adequate criterion validity except the questions ‘Has anyone in your family had a problem following an anaesthetic?’ and ‘If you have been put to sleep for an operation were there any anaesthetic problems?’ Therefore, it is reasonable for nurses to use this questionnaire to determine which patients an anaesthetist should see before the day of surgery.
A prospective randomised controlled trial of capnography vs. bronchoscopy for Blue RhinoTM percutaneous tracheostomy
Authors: Mallick A. , Venkatanath D. , Elliot S. C. , Hollins T. , Nanda Kumar C. G.
Published: August 2003

Summary A crucial step for successful percutaneous tracheostomy is the introduction of the needle and guide wire into the trachea. Capnography has recently been proposed as one way to confirm tracheal needle placement. In this randomised controlled study, we used capnography in 26 patients and bronchoscopy in 29 patients to confirm needle placement for percutaneous tracheostomy using Blue Rhino™ kit. The operating times and the incidence of peri‐operative complications were similar for both groups. Capnography proved to be as effective as bronchoscopy in confirming correct needle placement.
Survey of abuse and violence by patients and relatives towards intensive care staff
Authors: Lynch J. , Appelboam R. , McQuillan P. J.
Published: August 2003

A postal survey of senior nurses in intensive care units in England and Wales was conducted. The aim was to ascertain the frequency of abusive and violent behaviour by patients and relatives towards intensive care staff, discover the perceived causes, effects and documentation of such behaviour and define the current and proposed security arrangements for intensive care units. Response rate was 94%. During the study period, verbal abuse of nurses by patients and by relatives occurred in 87% and 74% of intensive care units, respectively. The relevant figures for doctors were 65% and 59%, respectively. Nurses experienced physical abuse by patients and by relatives in at least 77% and 17% of intensive care units, respectively (doctors 38% and 8%). Illness was the main perceived cause of offences by patients whereas ‘distress’ (45%), alcohol (24%), sociopathic behaviour (27%) were the main putative causes amongst relatives. Whilst 43% of intensive care units have no security system at the door, staff awareness, training and communication skills may be the principle tools in reducing the frequency and consequences of violent and abusive behaviour. This survey probably underestimates the problem.
The effects of concurrent atorvastatin therapy on the pharmacokinetics of intravenous midazolam
Authors: Mc Donnell C. G. , Harte S. , O'Driscoll J. , O'Loughlin C. , Van Pelt F. D. , Shorten G. D.
Published: August 2003

Midazolam is a commonly used anaesthetic agent and is metabolised by the 3A4 isoform of the cytochrome P450 enzyme system. Atorvastatin is also metabolised by cytochrome P450 3A4 and, in vitro, atorvastatin inhibits the cytochrome P450 3A4‐mediated metabolism of mexazolam. We hypothesised that concurrent administration of atorvastatin and midazolam would result in altered midazolam pharmacokinetics. Fourteen patients scheduled to undergo general anaesthesia for elective surgery were recruited in a matched pair design to receive intravenous midazolam (0.15 mg.kg−1). Of these patients, seven were taking long‐term atorvastatin. Atorvastatin patients demonstrated a greater area under the curve (889.4 (standard deviation 388.6) ng‐h.ml−1) vs. control patients (629.1 (standard deviation 197.2) ng‐h.ml−1) (p < 0.05). Patients taking atorvastatin also demonstrated a decreased clearance (0.18 (standard deviation 0.08) l‐kg. h−1) vs. control patients (0.27 (standard deviation 0.08) l‐kg.h−1) (p < 0.05). This study suggests that chronically administered atorvastatin decreases the clearance of intravenously administered midazolam.
The contribution of bryophytes to the carbon exchange for a temperate rainforest
Authors: DeLucia Evan H. , Turnbull Matthew H. , Walcroft Adrian S. , Griffin Kevin L. , Tissue David T. , Glenny David , McSeveny Tony M. , Whitehead David
Published: July 2003

Bryophytes blanket the floor of temperate rainforests in New Zealand and may influence a number of important ecosystem processes, including carbon cycling. Their contribution to forest floor carbon exchange was determined in a mature, undisturbed podocarp‐broadleaved forest in New Zealand, dominated by 100–400‐year‐old rimu (Dacrydium cupressimum) trees. Eight species of mosses and 13 species of liverworts contributed to the 62% cover of the diverse forest floor community. The bryophyte community developed a relatively thin (depth <30 mm), but dense, canopy that experienced elevated CO2 partial pressures (median 46.6 Pa immediately below the bryophyte canopy) relative to the surrounding air (median 37.6 Pa at 100 mm above the canopy). Light‐saturated rates of net CO2 exchange from 14 microcosms collected from the forest floor were highly variable; the maximum rate of net uptake (bryophyte photosynthesis – whole‐plant respiration) per unit ground area at saturating irradiance was 1.9 μmol m−2 s−1 and in one microcosm, the net rate of CO2 exchange was negative (respiration). CO2 exchange for all microcosms was strongly dependent on water content. The average water content in the microcosms ranged from 1375% when fully saturated to 250% when air‐dried. Reduction in water content across this range resulted in an average decrease of 85% in net CO2 uptake per unit ground area.

The results from the microcosms were used in a model to estimate annual carbon exchange for the forest floor. This model incorporated hourly variability in average irradiance reaching the forest floor, water content of the bryophyte layer, and air and soil temperature. The annual net carbon uptake by forest floor bryophytes was 103 g m−2, compared to annual carbon efflux from the forest floor (bryophyte and soil respiration) of −1010 g m−2. To put this in perspective of the magnitude of the components of CO2 exchange for the forest floor, the bryophyte layer reclaimed an amount of CO2 equivalent to only about 10% of forest floor respiration (bryophyte plus soil) or ∼11% of soil respiration. The contribution of forest floor bryophytes to productivity in this temperate rainforest was much smaller than in boreal forests, possibly because of differences in species composition and environmental limitations to photosynthesis. Because of their close dependence on water table depth, the contribution of the bryophyte community to ecosystem CO2 exchange may be highly responsive to rapid changes in climate.