bluuebunny/crossref_metadata_2025 huggingface dataset:
Actions of tramadol on micturition in awake, freely moving rats
Authors: Pandita Raj Kumar , Pehrson Rikard , Christoph Thomas , Friderichs Elmar , Andersson Karl‐Erik
Published: June 2003

(±)‐Tramadol, a widely used analgesic, is a racemate stimulating opioid receptors and inhibiting reuptake of noradrenaline and serotonin, that is, pharmacological principles previously shown to influence rat micturition.

We studied both (±)‐tramadol and its enantiomers in conscious Sprague–Dawley rats undergoing continuous cystometry. The effects of these agents were compared to those of morphine (μ‐opioid receptor agonist) and tested after pretreatment with naloxone (μ‐opioid receptor antagonist). Cystometries were evaluated before and after intravenous (i.v.), intraperitoneal (i.p.) and intrathecal (i.t.) drug administrations.

The most conspicuous effects of i.v. (±)‐tramadol (0.1–10 mg kg−1) was an increase in threshold pressure and an increase in micturition volume.

These effects were mimicked by (+)‐tramadol (0.1–5 mg kg−1 i.v.), whereas (−)‐tramadol (5 mg kg−1 i.v.) did not influence threshold pressure and micturition volume.

The effects of (±)‐tramadol 5 mg kg−1 on micturition volume were blocked by pretreatment with naloxone 0.3 mg kg−1. Morphine (0.3–10 mg kg−1 i.p.) increased threshold pressure but did not significantly increase micturition volume in doses not resulting in overflow incontinence.

(±)‐Tramadol 10 mg kg−1 increased urine production, an effect blocked by desmopressin 25 ng kg−1.

(±)‐Tramadol effectively inhibits micturition in conscious rats by stimulating μ‐opioid receptors. A synergy between opioid receptor stimulation and monoamine reuptake inhibition may contribute to the micturition effects.

British Journal of Pharmacology (2003) 139, 741–748. doi:10.1038/sj.bjp.0705297
Functional consequences of neuropeptide Y Y2 receptor knockout and Y2 antagonism in mouse and human colonic tissues
Authors: Hyland Niall P , Sjöberg Frida , Tough Iain R , Herzog Herbert , Cox Helen M
Published: June 2003

Neuropeptide Y (NPY), peptide YY (PYY) and pancreatic polypeptide (PP) differentially activate three Y receptors (Y1, Y2 and Y4) in mouse and human isolated colon.

The aim of this study was to characterise Y2 receptor‐mediated responses in colon mucosa and longitudinal smooth muscle preparations from wild type (Y2+/+) and knockout (Y2−/−) mice and to compare the former with human mucosal Y agonist responses. Inhibition of mucosal short‐circuit current and increases in muscle tone were monitored in colonic tissues from Y2+/+ and Y2−/− mice±Y1 ((R)‐N‐[[4‐(aminocarbonylaminomethyl)phenyl)methyl]‐N2‐(diphenylacetyl)‐argininamide‐trifluoroacetate (BIBO3304) or Y2 (S)‐N2‐[[1‐[2‐[4‐[(R,S)‐5,11‐dihydro‐6(6H)‐oxodibenz[b,e]azepin‐11‐yl]‐1‐piperazinyl]‐2‐oxoethyl]cyclopentyl]acetyl]‐N‐[2‐[1,2‐dihydro‐3,5(4H)‐dioxo‐1,2‐diphenyl‐3H‐1,2,4‐triazol‐4‐yl]ethyl]‐argininamide (BIIE0246) antagonists.

Predictably, Y2−/− tissues were insensitive to Y2‐preferred agonist PYY(3‐36) (100 nM), but unexpectedly Y4‐preferred PP responses were right‐shifted probably as a consequence of elevated circulating PP levels, particularly in male Y2−/− mice (Sainsbury et al., 2002).

BIBO3304 and BIIE0246 elevated mucosal ion transport, indicating blockade of inhibitory mucosal tone in Y2+/+ tissue. While BIBO3304 effects were unchanged, those to BIIE0246 were absent in Y2−/− mucosae. Neither antagonist altered muscle tone; however, BIIE0246 blocked NPY and PYY(3‐36) increases in Y2+/+ basal tone. BIBO3304 abolished residual Y1‐mediated NPY responses in Y2−/− smooth muscle.

Tetrodotoxin significantly reduced BIIE0246 and PYY(3‐36) effects in Y2+/+ mouse and human mucosae, but had no effect upon Y‐agonist contractile responses, indicating that Y2 receptors are located on submucosal, but not myenteric neurones.

Tonic activation of submucosal Y2 receptors by endogenous NPY, PYY or PYY(3‐36) could indirectly reduce mucosal ion transport in murine and human colon, while direct activation of Y2 receptors on longitudinal muscle results in contraction.

British Journal of Pharmacology (2003) 139, 863–871. doi:10.1038/sj.bjp.0705298
Neuromuscular effects of candoxin, a novel toxin from the venom of the Malayan krait (Bungarus candidus)
Authors: Nirthanan S , Charpantier E , Gopalakrishnakone P , Gwee M C E , Khoo H E , Cheah L S , Kini R M , Bertrand D
Published: June 2003

Candoxin (MW 7334.6), a novel toxin isolated from the venom of the Malayan krait Bungarus candidus, belongs to the poorly characterized subfamily of nonconventional three‐finger toxins present in Elapid venoms. The current study details the pharmacological effects of candoxin at the neuromuscular junction.

Candoxin produces a novel pattern of neuromuscular blockade in isolated nerve‐muscle preparations and the tibialis anterior muscle of anaesthetized rats. In contrast to the virtually irreversible postsynaptic neuromuscular blockade produced by curaremimetic α‐neurotoxins, the neuromuscular blockade produced by candoxin was rapidly and completely reversed by washing or by the addition of the anticholinesterase neostigmine.

Candoxin also produced significant train‐of‐four fade during the onset of and recovery from neuromuscular blockade, both, in vitro and in vivo. The fade phenomenon has been attributed to a blockade of putative presynaptic nicotinic acetylcholine receptors (nAChRs) that mediate a positive feedback mechanism and maintain adequate transmitter release during rapid repetitive stimulation. In this respect, candoxin closely resembles the neuromuscular blocking effects of d‐tubocurarine, and differs markedly from curaremimetic α‐neurotoxins that produce little or no fade.

Electrophysiological experiments confirmed that candoxin produced a readily reversible blockade (IC50∼10 nM) of oocyte‐expressed muscle (αβγδ) nAChRs. Like α‐conotoxin MI, well known for its preferential binding to the α/δ interface of the muscle (αβγδ) nAChR, candoxin also demonstrated a biphasic concentration–response inhibition curve with a high‐ (IC50∼2.2 nM) and a low‐ (IC50∼98 nM) affinity component, suggesting that it may exhibit differential affinities for the two binding sites on the muscle (αβγδ) receptor. In contrast, curaremimetic α‐neurotoxins have been reported to antagonize both binding sites with equal affinity.

British Journal of Pharmacology (2003) 139, 832–844. doi:10.1038/sj.bjp.0705299
NADH supplementation decreases pinacidil‐primed IK(ATP) in ventricular cardiomyocytes by increasing intracellular ATP
Authors: Pelzmann Brigitte , Hallström Seth , Schaffer Peter , Lang Petra , Nadlinger Karl , Birkmayer George D , Vrecko Karoline , Reibnegger Gilbert , Koidl Bernd
Published: June 2003

The aim of this study was to investigate the effect of nicotinamide‐adenine dinucleotide (NADH) supplementation on the metabolic condition of isolated guinea‐pig ventricular cardiomyocytes. The pinacidil‐primed ATP‐dependent potassium current IK(ATP) was used as an indicator of subsarcolemmal ATP concentration and intracellular adenine nucleotide contents were measured.

Membrane currents were studied using the patch‐clamp technique in the whole‐cell recording mode at 36–37°C. Adenine nucleotides were determined by HPLC.

Under physiological conditions (4.3 mM ATP in the pipette solution, ATPi) IK(ATP) did not contribute to basal electrical activity.

The ATP‐dependent potassium (K(ATP)) channel opener pinacidil activated IK(ATP) dependent on [ATP]i showing a significantly more pronounced activation at lower (1 mM) [ATP]i.

Supplementation of cardiomyocytes with 300 μg ml−1 NADH (4–6 h) resulted in a significantly reduced IK(ATP) activation by pinacidil compared to control cells. The current density was 13.8±3.78 (n=6) versus 28.9±3.38 pA pF−1 (n=19; P<0.05).

Equimolar amounts of the related compounds nicotinamide and NAD+ did not achieve a similar effect like NADH.

Measurement of adenine nucleotides by HPLC revealed a significant increase in intracellular ATP (NADH supplementation: 45.6±1.88 nmol mg−1 protein versus control: 35.4±2.57 nmol mg−1 protein, P<0.000005).

These data show that supplementation of guinea‐pig ventricular cardiomyocytes with NADH results in a decreased activation of IK(ATP) by pinacidil compared to control myocytes, indicating a higher subsarcolemmal ATP concentration.

Analysis of intracellular adenine nucleotides by HPLC confirmed the significant increase in ATP.

British Journal of Pharmacology (2003) 139, 749–754. doi:10.1038/sj.bjp.0705300
Anticonvulsant activity, teratogenicity and pharmacokinetics of novel valproyltaurinamide derivatives in mice
Authors: Isoherranen Nina , Yagen Boris , Spiegelstein Ofer , Finnell Richard H , Merriweather Michelle , Woodhead Jose H , Wlodarczyk Bogdan , White H Steve , Bialer Meir
Published: June 2003

The purpose of this study was to synthesize novel valproyltaurine (VTA) derivatives including valproyltaurinamide (VTD), N‐methyl‐valproyltaurinamide (M‐VTD), N,N‐dimethyl‐valproyltaurinamide (DM‐VTD) and N‐isopropyl‐valproyltaurinamide (I‐VTD) and evaluate their structure–pharmacokinetic–pharmacodynamic relationships with respect to anticonvulsant activity and teratogenic potential. However, their hepatotoxic potential could not be evaluated. The metabolism and pharmacokinetics of these derivatives in mice were also studied.

VTA lacked anticonvulsant activity, but VTD, DM‐VTD and I‐VTD possessed anticonvulsant activity in the Frings audiogenic seizure susceptible mice (ED50 values of 52, 134 and 126 mg kg−1, respectively).

VTA did not have any adverse effect on the reproductive outcome in the Swiss Vancouver/Fnn mice following a single i.p. injection of 600 mg kg−1 on gestational day (GD) 8.5. VTD (600 mg kg−1 at GD 8.5) produced an increase in embryolethality, but unlike valproic acid, it did not induce congenital malformations. DM‐VTD and I‐VTD (600 mg kg−1 at GD 8.5) produced a significant increase in the incidence of gross malformations. The incidence of birth defects increased when the length of the alkyl substituent or the degree of N‐alkylation increased.

In mice, N‐alkylated VTDs underwent metabolic N‐dealkylation to VTD. DM‐VTD was first biotransformed to M‐VTD and subsequently to VTD. I‐VTD's fraction metabolized to VTD was 29%. The observed metabolic pathways suggest that active metabolites may contribute to the anticonvulsant activity of the N‐alkylated VTDs and reactive intermediates may be formed during their metabolism. In mice, VTD had five to 10 times lower clearance (CL), and three times longer half‐life than I‐VTD and DM‐VTD, making it a more attractive compound than DM‐VTD and I‐VTD for further development. VTD's extent of brain penetration was only half that observed for the N‐alkylated taurinamides suggesting that it has a higher intrinsic activity that DM‐VTD and I‐VTD.

In conclusion, from this series of compounds, although VTD caused embryolethality, this compound emerged as the most promising new antiepileptic drug, having a preclinical spectrum characterized by the highest anticonvulsant potential, lowest potential for teratogenicity and favorable pharmacokinetics.

British Journal of Pharmacology (2003) 139, 755–764. doi:10.1038/sj.bjp.0705301
Intracarotid administration of short‐chain alkylglycerols for increased delivery of methotrexate to the rat brain
Authors: Erdlenbruch Bernhard , Schinkhof Claudia , Kugler Wilfried , Heinemann Dagmar E H , Herms Jochen , Eibl Hansjörg , Lakomek Max
Published: June 2003

The intracarotid administration of alkylglycerols has been reported previously by us to be a novel strategy for increased delivery of various chemotherapeutic drugs to the normal brain and brain tumors in rats.

Effectiveness and structure–activity relations of the most promising pentyl‐ and hexylglycerol derivatives have been elucidated in vivo by analyzing the transfer of methotrexate (MTX) across the blood–brain barrier (BBB) in normal rats. The effects were compared with BBB disruption using hypertonic mannitol or intracarotid infusion of bradykinin. Furthermore, toxicity of the alkylglycerols has been studied in long‐term experiments.

Apart from 1‐O‐pentyldiglycerol, all alkylglycerols induced a concentration‐dependent increase in MTX delivery to the brain varying from 1.1 to more than 300‐fold compared to intra‐arterial MTX alone. Enhanced barrier permeability rapidly approached baseline values within 5 and 120 min at the latest. Chemical structure, concentration, time schedule of injections and combination of different alkylglycerols were identified as instruments suited to regulate the MTX accumulation within a wide range. Mannitol 1.4 M resulted in very high MTX levels in the brain as observed using the highest concentrations of alkylglycerols. Intracarotid infusion of bradykinin had only a minor effect on the BBB. Using 1‐O‐pentylglycerol or 2‐O‐hexyldiglycerol, both cell culture experiments and long‐term in vivo analyses including clinical, laboratory and histopathological evaluations revealed no signs of toxicity.

In summary, intracarotid short‐chain alkylglycerols constitute a very effective and low toxic strategy for transient opening of the BBB to overcome the limited access of cytotoxic drugs to the brain.

British Journal of Pharmacology (2003) 139, 685–694. doi:10.1038/sj.bjp.0705302
Prevention of cultured rat stellate cell transformation and endothelin‐B receptor upregulation by retinoic acid
Authors: Chi Xuedong , Anselmi Kristin , Watkins Simon , Gandhi Chandrashekhar R
Published: June 2003

Physiologically, perisinusoidal hepatic stellate cells (HSC) are quiescent and store retinoids. During liver injury and in cell culture, HSC transform into proliferating myofibroblast‐like cells that express α‐smooth muscle actin (α‐sma) and produce excessive amounts of extracellular matrix. During transformation (also known as activation), HSC are depleted of the retinoid stores, and their expression of the endothelin‐1 (ET‐1) system is increased. ET‐1 causes contraction of transformed HSC and is implicated in their proliferation and fibrogenic activity. In order to understand the association between retinoids, ET‐1 and the activation of HSC, we investigated the effect of 13‐cis‐retinoic acid on the transformation of cultured HSC and the expression of ET‐1 system.

HSC derived from normal rat liver were maintained for 10–12 days in a medium supplemented with 5% serum and containing 2.5 μM retinoic acid without or with 50 nM ET‐1 (ETA+ETB agonist) or sarafotoxin S6c (ETB agonist). In another set of experiments, cells treated for 10–12 days with vehicle (ethanol) or retinoic acid were challenged with ET‐1 or sarafotoxin S6c, and various determinations were made at 24 h.

Retinoic acid inhibited transformation and proliferation of HSC as assessed by morphological characteristics, expression of α‐sma, bromodeoxyuridine incorporation and cell count. Retinoic acid also prevented upregulation of ETB receptors without affecting ET‐1 or ETA expression. Total protein synthesis ([3H]leucine incorporation), collagen α types I mRNA expression and collagen synthesis ([3H]proline incorporation) were lower in retinoic acid‐treated cells. Although ET‐1‐treated cells were morphologically similar to the control cells, their expression of α‐smooth muscle actin was significantly inhibited. The presence of retinoic acid in the medium during treatment with ET‐1 caused further reduction in the expression of α‐smooth muscle actin. ET‐1 and sarafotoxin S6c stimulated total protein synthesis in vehicle‐ and retinoic acid‐treated cells, but collagen synthesis only in the latter.

These results showing prevention of HSC activation and negative regulation of ETB receptor expression in them by retinoic acid may have important pathophysiologic implications.

British Journal of Pharmacology (2003) 139, 765–774. doi:10.1038/sj.bjp.0705303
Upregulation of cytochromes P450 2B in rat liver by orphenadrine
Authors: Murray Michael , Fiala‐Beer Eva , Sutton Dylan
Published: June 2003

The alkylamine drug orphenadrine (ORPH) is an inducer and inhibitor of the microsomal cytochrome P450 (CYP) system in mammals. This study evaluated the selectivity of CYP induction by ORPH in rat liver.

Immunoblot analysis indicated that ORPH was a selective inducer of the phenobarbitone (PB)‐inducible CYP2B in rat liver. CYP2B protein was increased to ∼14‐fold of levels in untreated rat liver. By comparison PB increased CYP2B expression 40‐fold. Corresponding increases in the activity of CYP2B‐dependent androstenedione 16β‐hydroxylation were measured in microsomes from ORPH and PB‐induced rats.

Northern analysis indicated that CYP2B1/2 mRNA was increased in ORPH‐induced rat liver. Consistent with this finding, ORPH was found to activate a PB‐responsive enhancer module in constitutive androstane receptor (CAR)‐transfected Hep G2 cells.

Other alkylamines like troleandomycin impair CYP turnover. We tested whether ORPH induction of CYP2B may include a post‐translational component. In PB‐pretreated animals ORPH administration delayed the loss of CYP2B after PB withdrawal, but no evidence for altered turnover was found.

These studies establish ORPH as a selective inducer of CYP2B in rat liver. Induction appears to be mediated pretranslationally by CAR activation of CYP2B gene transcription. Post‐translational stabilisation by an ORPH metabolite does not elicit induction. Induction of CYP2B may influence pharmacokinetic interactions involving ORPH.

British Journal of Pharmacology (2003) 139, 787–796. doi:10.1038/sj.bjp.0705305
Agonist‐ and antagonist‐induced sequestration/internalization of neuropeptide Y Y1 receptors in HEK293 cells
Authors: Pheng Leng Hong , Dumont Yvan , Fournier Alain , Chabot Jean‐Guy , Beaudet Alain , Quirion Rémi
Published: June 2003

Neuropeptide Y Y1 receptors are known to internalize following the binding of agonists. In the present study, a pseudopeptide Y1 receptor antagonist, homodimeric Ile‐Glu‐Pro‐Dpr‐Tyr‐Arg‐Leu‐Arg‐Tyr‐CONH2 (GR231118), also induced Y1 receptor internalization in human embryonic kidney (HEK293) cells.

We demonstrated first that both specifically bound radiolabeled antagonist ([125I]GR231118) and agonist ([125I][Leu31, Pro34]PYY) underwent receptor‐mediated sequestration/internalization in transfected HEK293 cells.

Agonist‐induced Y1 receptor internalization was dependent on clathrin‐coated pits and was regulated in part by Gi/o‐protein activation as revealed by pertussin toxin sensitivity. In contrast, antagonist‐induced sequestration of Y1 receptors was partly dependent on clathrin‐coated pits, but independent from Gi/o‐protein activation.

Exposure to high concentrations of agonist or antagonist caused a 50 and 75% loss of cell surface binding, respectively. The loss caused by the agonist rapidly recovered. This phenomenon was blocked by monensin, an inhibitor of endosome acidification, suggesting that cell surface receptor recovery is due to recycling. In contrast to the agonist, GR231118 induced a long‐lasting sequestration of Y1 receptors in HEK293 cells.

Immunofluorescence labeling indicated that following 40 min of incubation with either the agonist or the antagonist, Y1 receptors followed markedly different intercellular trafficking pathways.

Taken together, these findings provided evidence that a pseudopeptide Y1 receptor antagonist can induce long‐lasting disappearance of cell surface receptors through a pathway distinct from the classical endocytic/recycling pathway followed by stimulation with an agonist.

British Journal of Pharmacology (2003) 139, 695–704. doi:10.1038/sj.bjp.0705306
Role of redox state in modulation of ion channel function by fatty acids and phospholipids
Authors: Wang Zhiguo
Published: June 2003

British Journal of Pharmacology (2003) 139, 681–683. doi:10.1038/sj.bjp.0705307
Peroxidation of docosahexaenoic acid is responsible for its effects on ITO and ISS in rat ventricular myocytes
Authors: Judé S , Bedut S , Roger S , Pinault M , Champeroux P , White E , Le Guennec J‐Y
Published: June 2003

Exposure to docosahexaenoïc acid (DHA), a long‐chain polyunsaturated fatty acid, is known to block several ionic currents such as the transient outward current ITO. It has also been reported to activate certain potassium channels. It has been suggested that these effects, observed in single‐cell experiments, participate in the antiarrhythmic properties of these compounds in vivo.

DHA is highly prone to peroxidation. To investigate the influence peroxidation may have on the effects of DHA on ion channels, we studied ITO and the steady‐state outward current ISS in isolated rat ventricular myocytes under ruptured whole‐cell patch‐clamp conditions.

A measure of 10 μM DHA alone reduced ITO, evoked by a pulse to +70 mV, by 74.8±10.8% (n=7) and activated a delayed outward current with kinetic properties different from ISS.

When an antioxidant, alpha‐tocopherol (1 μM), was added together with DHA, the blockade of ITO was reduced to 38.5±7.7% (n=8) and the delayed outward current was not activated. α‐Tocopherol alone had no effect on these currents.

When an oxidant, hydrogen peroxide (1 μM), was applied together with DHA, the blockade of ITO was almost complete (98.4±1.0%, n=7) and a large delayed outward current was activated. A measure of 1 μM hydrogen peroxide alone had no effect on these currents.

Measurements of nonperoxidized DHA in experimental solutions confirmed the negative relation between DHA concentration and the effects on the currents.

We conclude that rather than DHA itself, it is the peroxidation products of DHA that block ITO and activate a delayed outward current in in vitro single‐cell experiments. These findings have important implications for the extrapolation of in vitro experimental findings to the antiarrhythmic effects of DHA in vivo because, in vivo, peroxidation of DHA is unlikely to occur.

British Journal of Pharmacology (2003) 139, 816–822. doi:10.1038/sj.bjp.0705308
Reactive oxygen species induce swelling and cytochrome c release but not transmembrane depolarization in isolated rat brain mitochondria
Authors: Galindo María F , Jordán Joaquín , González‐García Carmen , Ceña Valentín
Published: June 2003

In this study, we have used isolated brain mitochondria to investigate the effects of superoxide anions (O2−) on mitochondrial parameters related to apoptosis, such as swelling, potential, enzymatic activity, NAD(P)H, cytochrome c release, and caspase activity.

Addition of the reactive oxygen species (ROS) generator KO2 produced brain mitochondrial swelling, which was blocked by cyclosporin A (CSA), and which was Ca2+ independent.

Calcium induced mitochondrial swelling only at high concentrations and in the presence of succinate. This correlated with the increase in O2− production detected with hydroethidine in mitochondrial preparations exposed to Ca2+ and the fact that ROS were required for Ca2+‐induced mitochondrial swelling.

Superoxide anions, but not Ca2+, decreased citrate synthase and dehydrogenase enzymatic activities and dropped total mitochondrial NAD(P)H levels.

Calcium, but not O2−, triggered a rapid loss of mitochondrial potential. Calcium‐induced Δψm dissipation was inhibited by Ruthenium Red, but not by CSA.

Calcium‐ and superoxide‐induced mitochondrial swelling released cytochrome c and increased caspase activity from isolated mitochondria in a CS A‐sensitive manner.

In summary, superoxide potently triggers mitochondrial swelling and the release of proteins involved in activation of postmitochondrial apoptotic pathways in the absence of mitochondrial depolarization.

British Journal of Pharmacology (2003) 139, 797–804. doi:10.1038/sj.bjp.0705309
Retinoids as a potential treatment for experimental puromycin‐induced nephrosis
Authors: Moreno‐Manzano V , Mampaso F , Sepúlveda‐Muñoz J C , Alique M , Chen S , Ziyadeh F N , Iglesias‐de la Cruz M C , Rodríguez J , Nieto E , Orellana J M , Reyes P , Arribas I , Xu Q , Kitamura M , Lucio Cazana F J
Published: June 2003

Puromycin aminonucleoside (PAN)‐induced nephrosis is a model of human minimal change disease. In rats, PAN induces nephrotic‐range proteinuria, renal epithelial cell (podocyte) damage, infiltration of mononuclear leukocytes, and apoptosis of several renal cell types.

Retinoic acid (RA) modulates a wide range of biological processes, such as inflammation and apoptosis. Since renal damage by PAN is characterized by inflammatory infiltration and epithelial cell death, the effect of treatment with all‐trans RA (tRA) was examined in the PAN nephrosis model and in the cultured differentiated podocyte.

Treatment with tRA 4 days after PAN injection did not inhibit the proteinuria peak but reversed it significantly. However, treatment with tRA both before and 2 days after the injection of PAN protected the glomerular epithelial cells, diminishing the cellular edema and diffuseness of the foot process effacement. Preservation of the podocyte architecture correlated with the inhibition of proteinuria. The anti‐inflammatory effect of tRA was evidenced by the inhibition of PAN‐induced interstitial mononuclear cell infiltration and the decreased renal expression of two molecules involved in monocyte infiltration: fibronectin and monocyte chemoattractant protein‐1. TUNEL assays showed that tRA inhibited the PAN‐induced apoptosis of cultured differentiated mouse podocytes.

We conclude that tRA treatment may prevent proteinuria by protecting the podocytes from injury and diminishing the interstitial mononuclear infiltrate in the model of PAN nephrosis. Retinoids are a potential new treatment for kidney diseases characterized by proteinuria and mononuclear cell infiltration.

British Journal of Pharmacology (2003) 139, 823–831. doi:10.1038/sj.bjp.0705311
Anti‐inflammatory activity of creatine supplementation in endothelial cells in vitro
Authors: Nomura Akihiro , Zhang Minjie , Sakamoto Tohru , Ishii Yukio , Morishima Yuko , Mochizuki Mie , Kimura Toru , Uchida Yoshiyuki , Sekizawa Kiyohisa
Published: June 2003

Creatine (CR) supplementation augments muscle strength in skeletal muscle cells by increasing intracellular energy pools. However, the effect of CR supplementation on endothelial cells remains to be clarified.

In this study, we investigated whether CR supplementation had any anti‐inflammatory activity against human pulmonary endothelial cells in culture.

We confirmed that supplementation with 0.5 mM CR significantly increased both intracellular CR and phosphocreatine (PC) through a CR transporter while keeping intracellular ATP levels constant independent of CR supplementation and a CR transporter antagonist.

In the assay system of endothelial permeability, supplementation with 5 mM CR significantly suppressed the endothelial permeability induced by serotonin and H2O2.

In cell adhesion experiments, supplementation with 5 mM CR significantly suppressed neutrophil adhesion to endothelial cells.

In the measurement of adhesion molecules, CR supplementation with more than 0.5 mM CR significantly inhibited the expressions of ICAM‐1 and E‐selectin on endothelial cells, and the inhibition was significantly suppressed by an adenosine A2A receptor antagonist.

The present study suggests that CR supplementation has anti‐inflammatory activities against endothelial cells.

British Journal of Pharmacology (2003) 139, 715–720. doi:10.1038/sj.bjp.0705316
Evidence of an interaction between nifedipine and nafcillin in humans
Authors: Lang C. C. , Jamal S. K. , Mohamed Z. , Mustafa M. R. , Mustafa A. M. , Lee T. C.
Published: June 2003

Aims  Nafcillin (Wyeth Laboratories, Philadelphia, PA, USA) has been reported to induce the metabolism of cyclosporin and warfarin, which are known substrates of cytochrome P‐450 (CYP). However, there has not been any report to date on its possible interaction with nifedipine, an index substrate of the enzyme, CYP3A4.

Methods  Nine healthy normotensive subjects participated in this randomized placebo‐controlled two‐way crossover study examining the effects of 5 days’ pretreatment of nafcillin 500 mg or placebo four times daily on the pharmacokinetics of an oral dose of nifedipine 10 mg. Plasma nifedipine concentrations were measured by gas chromatography–mass spectro.

Results  The area under the plasma nifedipine concentration–time curve (AUC0–α) in nafcillin‐pretreated subjects (80.9 ± 32.9 µg l−1 h−1) was significantly decreased compared with subjects who received only nifedipine (216.4 ± 93.2 µg l−1 h−1) (P < 0.001). Total plasma clearance of nifedipine (CL/F) was significantly increased with nafcillin pretreatment (138.5 ± 42.0 l h−1vs 56.5 ± 32.0 l h−1) (P < 0.002).

Conclusions  The results show that nafcillin pretreatment markedly increased the clearance of nifedipine and suggest that nafcillin is a potent inducer of CYP enzyme.
Variability of heart rate correction methods for the QT interval
Authors: Desai Mehul , Li Lang , Desta Zeruesenay , Malik Marek , Flockhart David
Published: June 2003

Aims  To compare variability of heart rate‐corrected QT intervals (QTc) using three different methods in a study of low‐dose oral haloperidol.

Methods  In a randomized, double‐blind, placebo‐controlled, crossover trial, we studied QT interval pharmacodynamics of single doses of oral haloperidol (10 mg) in 16 healthy subjects. Heart rate correction of the QT interval was performed using Bazett’s, Fridericia's and subject‐specific correction methods. The subject‐specific correction was performed using linear mixed modelling of placebo period QT vs RR data from each study subject.

Results  The subject‐specific correction, in the form of QTc = QT/RRα, yielded a correction term α (slope of the log‐transformed QT vs RR relationship) that ranged from 0.23 to 0.38 in individual subjects, i.e. the fixed correction term α = 0.5 of Bazett's correction was outside and the fixed correction term α = 0.33 of Fridericia's correction inside the range of individual values. The mean absolute slope of the QTcvs RR regression line using the subject‐specific correction was significantly lower than the mean slopes obtained using either Bazett's or Fridericia's corrections. All three methods revealed a statistically significant greater mean QTc on haloperidol than on placebo at 10 h post‐drug administration. The mean QT (95% CI) was 421.6 (410.8, 432.4), and 408.4 (398.6, 417.8) on haliperidol and placebo, respectively, using the subject‐specific correction method (P = 0.0053). The mean QTc (95% CI) was 425.4 (414.3, 436.5) and 403.1 (394.3, 411.9) on haliperidol and placebo, respectively, using Bazett's correction (P = 1.7 × 10−5) and 423.1 (412.6, 433.6) and 408.2 (398.6, 417.8) on haliperidol and placebo, respectively, using Fridericia's correction (P = 7.7 × 10−4). Raw P‐values were calculated using a paired t‐test. Bonferroni‐corrected P‐values were calculated by multiplying the raw P‐values by 13.

Conclusion  Haloperidol caused a statistically significant mean QTc prolongation using the three correction methods. The QTc intervals were less dependent on RR intervals using the subject‐specific method, thus decreasing the possibility of over‐ or under‐correction. The interindividual QTc changes from baseline varied significantly depending on the method of correction used.
Effects of licence change on prescribing and poisons enquiries for antipsychotic agents in England and Scotland
Authors: Bateman D. N. , Good A. M. , Afshari R. , Kelly C. A.
Published: June 2003

Aims  To examine the effect of licence change for thioridazine at the end of 2000 on the prescription of antipsychotic drugs in England and Scotland, and investigate changes in poisons information inquiries and, for Edinburgh, poisons admissions.

Methods  Prescription data for antipsychotic drugs were obtained for England and Scotland and quarterly trends examined for 2000 and 2001. Accesses to the UK National Poisons Information Service website TOXBASE for antipsychotic products were examined for the same period. For Scotland telephone enquiry data, and admission data to the Edinburgh Poisons Unit were also evaluated. Trends in poisonings were compared with prescribing change.

Results  In England prescriptions for thioridazine fell rapidly in 2001 from approximately 35% of market share to less than 5%, and were replaced by risperidone, chlorpromazine and olanzapine. TOXBASE accesses fell from 39.3% of antipsychotics to 4.4%. Accesses for chlorpromazine, olanzapine and risperidone increased. In Scotland prescribing of thioridazine was similar to changes in England, but it was principally replaced by chlorpromazine. These changes were mirrored by TOXBASE accesses, telephone enquiries and in‐patient admissions. The ratio of TOXBASE accesses for thioridazine to prescription numbers for the drug increased after the licence change.

Conclusions  Licence change produced rapid change in prescribing behaviour within 3 months. Prescribing behaviour in England and Scotland was different. Changes in prescribing were mirrored by changes in accesses for poisons information in both England and Scotland, and in Edinburgh by hospital admissions. The increase in the ratio of TOXBASE accesses to prescriptions for thioridazine suggests doctors may have become more aware of its potential toxicity.
Evidence for an age and gender bias in the secondary prevention of ischaemic heart disease in primary care
Authors: Williams David , Bennett Kathleen , Feely John
Published: June 2003

Aims  To determine if a gender or age bias exists in the prescription of important secondary preventive therapies for ischaemic heart disease in primary care.

Methods  We identified 15 590 patients with ischaemic heart disease on the basis that they received a prescription for nitrate therapy over a 1‐year period (September 1999 to August 2000) from the Eastern Region of the General Medical Services scheme in Ireland (population of 334 031), which provides free health service to those eligible patients in primary care. Odds ratios (OR) for the prescription of aspirin, β‐blockers, statins, calcium channel antagonists and ACE inhibitors in women and in those aged> 65 years were determined.

Results  Female patients were less likely to receive a prescription for a β‐blocker [OR = 0.84, 95% confidence interval (CI) = 0.79, 0.89, P < 0.001], aspirin (OR = 0.72, 95% CI = 0.67, 0.78, P < 0.001), and ACE inhibitors (OR = 0.83, 95% CI = 0.78, 0.89, P < 0.001) compared with their male counterparts. However, women were more likely to receive anxiolytic benzodiazepines (OR = 1.71, 95% CI = 1.59, 1.85, P < 0.001) compared with their male counterparts. Elderly patients (aged> 65 years) were less likely to receive aspirin (OR = 0.92, 95% CI = 0.85, 0.99, P < 0.001), β‐blocker (OR = 0.66, 95% CI = 0.62, 0.71, P < 0.001) and a statin (OR = 0.5, 95% CI = 0.46, 0.53, P < 0.001).

Conclusions  An age and gender bias exists in the prescription of important secondary preventive therapies in primary care that may lead to increased mortality from ischaemic heart disease in these groups.
Disposition of debrisoquine and nortriptyline in Korean subjects in relation to CYP2D6 genotypes, and comparison with Caucasians
Authors: Dalén P. , Dahl M‐L. , Roh H.‐K. , Tybring G. , Eichelbaum M. , Wilkinson G. R. , Bertilsson L.
Published: June 2003

Aims  To study the influence of the CYP2D6*10 allele on the disposition of debrisoquine and nortriptyline.

Methods  The pharmacokinetics of debrisoquine and nortriptyline and their main metabolites were determined in ten Koreans with the CYP2D6*1/*1 (n = 5) and CYP2D6*1/*10 (n = 5) genotypes after single oral doses of 20 mg debrisoquine and 25 mg nortriptyline, respectively. The data were compared with previously published findings from 21 Caucasians with 0, one, two, three, four or 13 functional CYP2D6 genes.

Results  The AUC0−8 of 4‐hydroxydebrisoquine was significantly lower in Koreans with CYP2D6*1/*10 genotype compared with CYP2D6*1/*1[95% confidence interval (CI) for the ratio between means 1.17, 1.85]. No other genotype‐related differences were found in the plasma kinetics of nortriptyline and debrisoquine, or their hydroxy metabolites. The AUCnortriptyline/AUC10‐hydroxynortriptyline ratio did not differ between the *1/*1 and *1/*10 genotype groups (95% CI for the ratio of means 0.60, 1.26). Similarly, there was no difference between these genotypes with respect to the AUCdebrisoquine/AUC4‐hydroxydebrisoquine ratio (95% CI for the ratio of mean values 0.38, 1.46). Both Korean genotype groups had similar AUCs and parent compound/metabolite AUC ratios of debrisoquine and nortriptyline to Caucasians with two functional CYP2D6 genes.

Conclusions  Heterozygosity for CYP2D6*10 decreases the CYP2D6‐dependent elimination of nortriptyline and debrisoquine to only a limited degree. Further studies in subjects homozygous for CYP2D6*10 are required to elucidate fully the pharmacokinetic consequences of this CYP2D6 genotype in Orientals.
The effects of histamine and leukotriene receptor antagonism on nasal mannitol challenge in allergic rhinitis
Authors: Lee Daniel K. C. , Haggart Kay , Currie Graeme P. , Anderson Sandra D. , Lipworth Brian J.
Published: June 2003

Aims  It is unclear as to which mediators are involved in mediating the response to nasal mannitol challenge, a novel osmotic stimulus.

Methods  A double‐blind, randomized, placebo‐controlled, crossover design was employed. Nine patients with allergic rhinitis were randomized to receive a single‐dose of desloratadine 5 mg, montelukast 10 mg or placebo, and underwent nasal mannitol challenges with nasal peak inspiratory flow recordings over 60 min. The change in peak nasal inspiratory flow was calculated as percentage change from baseline as the peak response and area under the time–response curve (AUC).

Results  Desloratadine and montelukast conferred a significant degree of protection compared to placebo for peak and AUC response, but there were no significant differences between the two drugs. For the peak response as percentage fall, the mean difference (95% CI) vs placebo was 27.7 (8.0, 47.4)% for desloratadine and 17.6 (1.9, 33.3)% for montelukast.

Conclusions  Our results suggest that histamine and cysteinyl‐leukotrienes are involved in mediating the response to nasal mannitol in allergic rhinitis.
C‐peptide has no effect on forearm blood flow during local hyperinsulinaemia in healthy humans
Authors: Langenberger Herbert , Schaller Georg , Pleiner Johannes , Mittermayer Friedrich , Bayerle‐Eder Michaela , Wolzt Michael
Published: June 2003

Background  C‐peptide increases forearm blood flow (FBF) in patients with Type 1 diabetes, probably by interaction with insulin, but not in healthy subjects. It is unclear if the vasodilating effect is sealed at normal fasting insulin concentrations.

Methods  The effects of C‐peptide alone and during local hyperinsulinaemia were studied in healthy young men. Subjects received intra‐arterial insulin at 6 pmol min−1 (low dose) or placebo for 60 min with subsequent coinfusion of C‐peptide at increasing doses of 2–60 pmol min−1 in a double‐blind crossover study (n = 8). In control experiments insulin at 30 pmol min−1 (high dose) was coinfused with C‐peptide (n = 3). FBF was measured by strain‐gauge plethysmography.

Results  Placebo had no effect on FBF (mean percentage change from baseline at 50 min −3.1%, 95% confidence interval [CI]−14.9, + 8.7). Insulin infusion slightly enhanced FBF by + 10.2% (95% CI −6.8, + 27.2; low dose) and + 17.6% (95% CI −38.8, + 74.0; high dose), respectively. The mean individual difference of the change in FBF between low‐dose insulin and placebo was + 13.3% (95% CI −6.0, + 32.7; P = NS). Infusion of C‐peptide increased local C‐peptide concentrations from 1.8 ± 0.1 ng ml−1 to 6.1 ± 2.8 ng ml−1, but had no effect on FBF during placebo or hyperinsulinaemia (mean difference vs low dose insulin −16.0%, 95% CI −38.9, + 6.9).

Conclusion  The vasodilating effect of C‐peptide seen in Type 1 diabetes is not detectable during fasting or hyperinsulinaemia in the forearm vasculature of healthy subjects. This suggests saturation of its vasodilating potency at insulin concentrations within the normal or in the supraphysiological range.
The effect of motilin on the rectum in healthy volunteers
Authors: Kamerling I. M. C. , Burggraaf J. , Van Haarst A. D. , Oppenhuizen‐Duinker M. F. , Schoemaker H. C. , Biemond I. , Jones R. , Heinzerling H. , Cohen A. F. , Masclee A. A. M.
Published: June 2003

Aims  The role of motilin in the regulation of upper gastrointestinal (GI) motility is well defined. However, little is known about the effects on the distal GI tract. To investigate the effect of exogenous motilin on rectal function, barostat measurements in the rectum were performed and lower abdominal symptoms were scored.

Methods  Eight fasted, healthy volunteers were infused intravenously with synthetic motilin or placebo over 90 min in a double‐blind, randomized, cross‐over design. Rectum volume was measured with a barostat device during constant pressure and during isobaric distensions. Lower abdominal symptoms were scored by visual analogue scales. Plasma motilin concentrations were measured by radioimmunoassay.

Results  Baseline rectum volumes were similar between treatments: 185 ± 62 mL (motilin) and 136 ± 41 mL (placebo). During the constant pressure procedure, motilin increased rectum volume [area under the effect curve (AUEC)] by 6%[95% confidence interval (CI) −3, 16] of baseline, compared with placebo. During isobaric distensions motilin increased rectum volume (AUEC) by 43 mL (95% CI 0.4, 85; P < 0.05) and compliance by 10 mL mmHg−1 (95% CI 0.3, 20; P < 0.05) relative to placebo. Motilin did not induce changes in the sensation of rectal feelings.

Conclusion  Exogenous motilin increased rectal compliance in healthy volunteers, without affecting rectal sensations.
Increased leptin production in vivo and insulin cleavage by the omental adipose tissue of morbidly obese patients
Authors: Cuatrecasas G. , Granada M. L. , Formiguera X. , Rull M. , Alastrué A. , Remesar X. , Alemany M. , Foz M.
Published: June 2003

OBJECTIVE

The aim of this investigation was to assess the insulin cleavage capacity in obese humans. Increased insulin degradation by visceral adipose tissue has previously been demonstrated in obese rats and could be interpreted as a physiological response to hyperinsulinaemia. The recent characterization of leptin receptors in pancreatic β cells, liver and muscle suggests that leptin may influence insulin function and metabolism. Our study focuses on the possible relationship between leptin secretion and adipose tissue insulin‐degrading capacity.

DESIGN AND PATIENTS

Insulin and leptin were measured in arterial blood and in the epiploic vein of morbidly obese (n = 7) and non‐obese patients (n = 7) who were undergoing abdominal surgery. Arteriovenous insulin difference (AV insulin) was considered an in vivo marker of insulin degradation by the omental fat tissue. Statistical comparison between venous and arterial leptin was used to assess endogenous leptin production.

MEASUREMENTS

Insulin was measured using an oligoclonal IRMA and leptin levels were determined by using a specific radioimmunoassay.

RESULTS

Morbidly obese patients were hyperinsulinaemic compared to non‐obese patients according to arterial insulin levels (P = 0.049) but not to venous levels. Insulin cleavage capacity, nil in the control group, was clearly significant in the morbidly obese patients (P = 0.001). In the morbidly obese group, leptin levels in venous epiploic samples were significantly higher (P = 0.028) than in the arterial samples, confirming in situ the synthesis of leptin by human white adipose tissue. We also observed a correlation between insulin arterial levels and venous leptin concentrations (P = 0.009) which supports the chronic leptinogenic effect of insulin suggested in previous works. Finally, our results show that venous leptin levels are correlated with the extent of insulin cleavage by omental tissue (P = 0.033).

CONCLUSIONS

Morbidly obese patients have a higher white adipose tissue insulin cleavage capacity, which could partially diminish hyperinsulinaemia‐derived adverse effects. High leptin production, a consequence of high insulin levels, may act as a signal to the insulin‐degrading tissues in order to lower insulinaemia.
Carrier status for steroid 21‐hydroxylase deficiency is only one factor in the variable phenotype of acne
Authors: Ostlere Lucy S. , Rumsby Gillian , Holownia Peter , Jacobs Howard S. , Rustin Malcolm H. A. , Honour John W.
Published: June 2003

OBJECTIVE

Previous endocrine studies of women with acne have produced diverse results. This study was designed to seek evidence, from endocrine and genetic studies, for impaired steroid biosynthesis in patients with acne.

DESIGN

Adrenal stimulation tests with synthetic adrenocorticotrophic hormone (ACTH) were performed.

MEASUREMENTS

Steroid hormones were measured basally and 30 minutes after ACTH. The results were correlated with analysis of the steroid 21‐hydroxylase gene (CYP21).

PATIENTS

Fifty‐one consecutive female patients (mean age 27.1 years) referred with acne.

RESULTS

The median plasma 17‐hydroxyprogesterone (17‐OHP) before and 30 minutes after ACTH were 2.5 nmol/l (range 1.1–8.2) and 7.3 (2.1–17.8) nmol/l which were significantly above normal female controls (n = 11, mean age 25.6 years) at 1.5 (0.9–4.2) and 4.6 (2.6–8.4) nmol/l. Eighteen of 51 acne patients showed an abnormal 17‐OHP response. The 21‐hydroxylase gene (CYP21) was examined for major deletions and for three common point mutations in 31 of the patients (14 with exaggerated 17‐OHP response). One patient had a deletion of CYP21 on one allele consistent with carrier status for the classical congenital adrenal hyperplasia (CAH). Five patients, one of whom had a normal 17‐OHP response to Synacthen, were heterozygous for the val 281 leu mutation in exon 7 of the CYP21 and were therefore carriers for a mutation associated with late‐onset CAH. One patient with a raised 17‐OHP response was homozygous for the splice site mutation in intron 2 and one patient with a normal 17‐OHP response was heterozygous for the mutation. None of the patients had the ile 172 asn mutation. Eight of the 31 acne patients who had CYP21 gene analysis were carriers for mutations in the 21‐hydroxylase gene but only six would have been detected by an abnormal response of 17‐OHP on stimulation.

CONCLUSION

Although alterations of the CYP21 gene were more common in acne than in controls there is a poor correlation between these events and raised steroids and acne. Factors other than mild impairment of CYP21 contribute to the variability of the clinical phenotype in hyperandrogenic states including acne.