bluuebunny/crossref_metadata_2025 huggingface dataset:
S‐matrix expansions in view of complex dilation theories
Authors: Alferova T. , Elander N.
Published: November 2002

In this article, we use the complex dilation formalism to compute S‐matrix residues for a number of complex Schrödinger‐type eigenvalues in a limited spectral region. These residues are then used as expansion parameters for the corresponding S‐matrix. The aim of this work is to find numerically stable algorithms that can be applied to problems based on realistic only numerically represented potentials. Two formalisms are described. In the first, we compute the Jost functions ℱ+(k) and ℱ−(k) as well as the derivative dℱ/dk numerically at the eigenvalue kν. Using the second method, we generalize a formula described by Newton [(Scattering Theory of Waves and Particles; McGraw‐Hill; New York, 1966) for bound states to resonant eigenvalues. Here, the S‐matrix residue is obtained by integrating the resonant eigenfunction in the complex coordinate space. Our formalism is tested on an exactly solvable problem (Bargmann, V. Phys Rev 1949, 75, 301–303) and a classic complex dilation potential (Bain, R. A. et al. J Phys B Atom Mol Phys 1974, 7, 2189–2202). © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Classical trajectory‐based approaches to solving the quantum Liouville equation
Authors: Donoso Arnaldo , Martens Craig C.
Published: November 2002

The time‐dependent quantum mechanics of heavy particles moving on a single potential energy surface can often be represented surprisingly well by the evolution of classical trajectory ensembles. However, manifestly quantum mechanical phenomena—such as transitions between coupled electronic states, electronic coherence and its decay, or quantum mechanical tunneling—require fundamental modification of the purely classical motion. We introduced and developed an approach to this problem that is based on solving the quantum Liouville equation using ensembles of classical trajectories. In this article, we describe the general approach and its application to the problems of nonadiabatic dynamics, coherent multistate electronic–nuclear dynamics, and tunneling through potential barriers. When viewed from the trajectory ensemble perspective, quantum effects arise as a breakdown of the statistical independence of the trajectories in the ensemble and a nonlocal entanglement of their collective evolution. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Symmetry anomaly in disubstituted benzenes
Authors: André J.‐M. , Brédas J. L. , Coropceanu V. , Silbey R. J.
Published: November 2002

A striking feature in disubstituted benzenes is that the well‐known degeneracy scheme of the π levels of the unperturbed benzene ring is conserved when donor and acceptor groups of the same strength are introduced in para positions (antisymmetrical substitution). This degeneracy is lifted when substituting with two identical donor or acceptor groups (symmetrical substitution). In the antisymmetrical

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substitution, even though the perturbation affects only one of the two degenerate π levels, a compensation effect has the result that the degeneracy of the π levels is not only conserved but their energies remain unchanged; thus, the perturbation only affects the energy of the lowest occupied π level and that of the highest unoccupied π level. The same feature is observed for other even annulenes. This symmetry anomaly is analyzed by various methods. The connection with Berry's phase problem is also discussed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Electron binding energies of nucleobases and nucleotides
Authors: Dolgounitcheva O. , Zakrzewski V. G. , Ortiz J. V.
Published: November 2002

Electron propagator theory is applied to the calculation and interpretation of electron binding energies of molecular fragments found in nucleic acids. This theory provides a systematic approach to correlation problems in quantum chemistry while retaining a one‐electron picture of electronic structure. Photoelectron spectra for the purine and pyrimidine bases found in nucleic acids have been assigned with the aid of calculations that employ an electron propagator approximation that has been developed for the study of large molecules. This method, the partial third‐order approximation (P3), has been shown to generate reliable electron binding energies for closed‐shell molecules and anions. Correlation corrections to canonical, Hartree–Fock orbital energies are necessary for assignment of cationic states. Electron detachment energies for H2PO also have been assigned successfully with the P3 method. These results indicate that the P3 method is a suitable procedure for predicting electron binding energies of nucleotide anions. Correlation effects are important in determining the ordering of final states with holes localized on the phosphate or the base regions in the nucleotide. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Using 1,3‐butadiene and 1,3,5‐hexatriene to model the cis‐trans isomerization of retinal, the chromophore in the visual pigment rhodopsin
Authors: Blomgren Fredrik , Larsson Sven
Published: November 2002

The short polyenes 1,3‐butadiene and 1,3,5‐hexatriene are used to model the cis‐trans isomerization of the protonated Schiff base of retinal (PSBR) in rhodopsin (Rh). We employed the complete active space self‐consistent field (CASSCF) method for calculation of the potential energy surfaces (PESs) in C2 symmetry. In the calculations, the central bond was twisted from 0 to 180° in the first singly excited singlet state (Sse), i.e., the state dominated by a configuration with one electron excited from HOMO to LUMO. It was found that the PES of 1,3‐butadiene has a maximum whereas the PES of 1,3,5‐hexatriene has a minimum for a twist angle of 90°. This is explained by a shift in border of single and double bonds in the Sse state. The first step in the cis‐trans isomerization of PSBR, which is the formation of the C6C7 (see Scheme 1 for numbering) twisted PSBR in the first excited singlet state (S1), inside the protein binding pocket of the visual pigment Rh is modeled using crystal coordinates and the calculations performed on 1,3‐butadiene and 1,3,5‐hexatriene. More specifically, a plausible approximate structure is calculated in a geometric way for the C6C7 90° twisted PSBR, which fits into the protein binding pocket in the best possible way. It has been shown earlier that PSBR has an energy minimum for this angle in S1. The CASSCF method was used to investigate the wave function of the calculated structure of PSBR. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Nonsymmetrical perturbation theory for improving coupled‐cluster wave functions
Authors: Surján Péter R. , Szabados Ágnes , Szekeres Zsolt
Published: November 2002

A general nonsymmetrical formulation of multireference perturbation theory (PT) is used to correct the energy and wave function obtained from limited coupled‐cluster (CC) calculations. Following the spirit of CC theory, we use the Hartree–Fock wave function in bras while the CC wave function is used as the ket reference. The resulting PT is compared to the symmetrical (Hermitean) formulation and to the systematic CC(n)PT(m) theory of Hirata et al. Numerical results up to the fifth order in PT are obtained in a determinantal formalism for a few sample molecules. The effect of partitioning is also studied. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Thermodynamics and kinetics of downhill protein folding investigated with a simple statistical mechanical model
Authors: Muñoz Victor
Published: November 2002

The possibility of downhill protein folding is one of the most intriguing predictions of the energy landscape approach. Finding examples of downhill folding has important practical implications because in the absence of a free energy barrier the mechanism of folding is amenable to experimental observation. Here, a simple statistical mechanical model of protein folding is used to analyze the thermodynamic and kinetic properties of downhill and two‐state folding. Folding free energy surfaces with and without a barrier separating denatured and native states can be generated with this model by simply modifying the curvature of the energy as a function of the order parameter, i.e., number of amino acids in incorrect conformation. Thermodynamic and kinetic analysis of surfaces with a barrier show the typical properties of two‐state folding: a first‐order equilibrium unfolding transition and exponential biphasic folding kinetics. In contrast, in downhill surfaces the unfolding process is noncooperative, and the apparent transition depends on the structural probe used to measure it. Therefore, this inherent behavior can be used as an experimental criterion for the identification of downhill folding. Surprisingly, the kinetics of downhill folding do not greatly deviate from exponential behavior unless the effective diffusion coefficient is assumed to decrese as folding progresses, exemplifying the increase in the roughness of the landscape. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Molecular relaxation and metalloenzyme active site modeling
Authors: Whittaker James W.
Published: November 2002

Metalloenzymes represent a broad class of important biomolecules containing an essential metal ion cofactor in their catalytic active sites, forming biologic metal complexes that perform a wide range of important functions: activation of small molecules (O2, N2, H2, CO), atom transfer chemistry, and the control of oxidation equivalents. The structures of many metalloenzyme active sites have been defined by X‐ray crystallography, revealing transition metal ions in unique low‐symmetry environments. These bioinorganic complexes present significant challenges for computational studies aimed at going beyond crystal structures to develop a detailed understanding of the catalytic mechanisms. Considerable progress has been made in the theoretical characterization of these sites in recent years, supported by the availability of efficient computational tools, in particular density functional methods. However, the ultimate success of a theoretical model depends on a number of factors independent of the specific computational method used, including the quality of the initial structural data, the identification of important environmental perturbations and constraints, and experimental validation of theoretical predictions. We explore these issues in detail and illustrate the effects of molecular relaxation in calculations of two metalloenzymes, manganese superoxide dismutase and galactose oxidase. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Chemical model for superconductivity
Authors: Larsson Sven
Published: November 2002

A “chemical” model based on the theory of mixed valence systems is successful in explaining a number of properties of superconductors. The model is formulated in configuration space but is consistent with Bardeen–Cooper–Schrieffer theory, and connects directly to chemical properties that may be calculated by quantum chemical methods. Crystal structure is important, in particular the difference in equilibrium geometry between different oxidation states. According to the model, high pressure causes less difference between the oxidation states and hence a lower, or possibly disappearing, activation barrier and increased conductivity. This agrees with the experiments. Mixed valence systems with nonequivalent sites or with a large structural difference between the oxidation states are not superconducting or even conducting. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Unique changes in synaptic morphology following tetanization under pharmacological blockade
Authors: Weeks Andrew C.W. , Ivanco Tammy L. , Leboutillier Janelle C. , Marrone Diano F. , Racine Ronald J. , Petit Ted L.
Published: November 2002

Long‐term potentiation (LTP) in the hippocampus has been associated with changes in synaptic morphology. Whether these changes are LTP‐dependent or simply a result of electrophysiological stimulation has not yet been fully determined. This study involved an examination of synaptic morphology in the rat dentate gyrus 24 h after electrophysiological stimulation sufficient to induce LTP. In one group, ketamine, a competitive NMDA antagonist, was injected prior to stimulation to block the formation of LTP. Synaptic morphological quantification included estimating the total number of synapses per neuron, determining synaptic curvature and the presence of synaptic perforations, and measuring the maximal PSD profile length of the synapses. The results indicated that most of the changes observed following the induction of LTP (increases in the proportion of concave‐shaped synapses, increases in perforated concave synapses, and a decrease in the length of nonperforated concave synapses) are not observed under ketamine blockade, suggesting that they are LTP‐specific and not simply the result of tetanic stimulation. Ketamine was associated, however, with several novel structural changes including a decrease in the length of the perforations in the concave perforated synapses, a reduction in the number of convex perforated synapses, and a nonlayer‐specific increase in synaptic length compared to controls. Based on previous research, this combination of morphological characteristics is potentially less efficacious, which suggests that synapses that are tetanized but not potentiated, due to pharmacological blockade, appear to undergo opposing, compensatory, or homeostatic changes. These results support the suggestion that synaptic morphology changes are both stimulation‐ and area‐specific, are highly complex, and depend on the specific local physiology. Synapse 47:77–86, 2003. © 2002 Wiley‐Liss, Inc.
Estimating the number of release sites and probability of firing within the nerve terminal by statistical analysis of synaptic charge
Authors: Viele Kert , Stromberg Arnold J. , Cooper Robin L.
Published: November 2002

Investigating the function of individual synapses is essential to understanding the mechanisms that influence the efficacy of chemical synaptic transmission. The known simplicity of the synaptic structure at the crayfish neuromuscular junction (NMJ) and its quantal nature of release allows an assessment of discrete synapses within the motor nerve terminals. Our goal in this article is to investigate the effect of the stimulation frequency on the number of active release sites (n) and the probability of release (p) at those active sites. Because methods based on direct counts often provide unstable joint estimates of (n) and (p), we base our analysis on mixture modeling. In particular, the mixture modeling approach is used to estimate (n) and (p) for stimulation frequencies of 1 Hz, 2 Hz, and 3 Hz. Our results indicate that as the stimulation frequency increases, new sites are recruited (thus increasing n) and the probability of release (p) increases. Synapse 47:15–25, 2003. © 2002 Wiley‐Liss, Inc.
The antihistamine fexofenadine does not affect IKr currents in a case report of drug‐induced cardiac arrhythmia
Authors: Scherer Constanze R , Lerche Christian , Decher Niels , Dennis Adrienne T , Maier Patrick , Ficker Eckhard , Busch Andreas E , Wollnik Bernd , Steinmeyer Klaus
Published: November 2002

The human HERG gene encodes the cardiac repolarizing K+ current IKr and is genetically inactivated in inherited long QT syndrome 2 (LQTS2). The antihistamine terfenadine blocks HERG channels, and can cause QT prolongation and torsades de pointes, whereas its carboxylate fexofenadine lacks HERG blocking activity.

In the present study the ability of fexofenadine to block the K897T HERG channel variant was investigated. The underlying single nucleotide polymorphism (SNP) A2960C was identified in a patient reported to develop fexofenadine‐associated LQTS.

K897T HERG channels produced wild‐type‐like currents in Xenopus oocytes. Even at a concentration of 100 μM, fexofenadine did not inhibit wild‐type or K897T HERG channels. Coexpression of wild‐type and K897T HERG with the ß‐subunit MiRP1, slightly changed current kinetics but did not change sensitivity to terfenadine and fexofenadine.

Western blot analysis and immunostaining of transiently transfected COS‐7 cells demonstrated that overall expression level, glycosylation pattern and subcellular localization of K897T HERG is indistinguishable from wild‐type HERG protein, and not altered in the presence of 1 μM fexofenadine.

We provide the first functional characterization of the K897T HERG variant. We demonstrated that K897T HERG is similar to wild‐type HERG, and is insensitive to fexofenadine. Although the polymorphism changes PKA and PKC phosphorylation sites, regulation of K897T HERG by these kinases is not altered.

Our results strongly indicate that QT lengthening and cardiac arrhythmia in the reported case of drug‐induced LQT are not due to the K897T exchange or to an inhibitory effect of fexofenadine on cardiac IKr currents.

British Journal of Pharmacology (2002) 137, 892–900. doi:10.1038/sj.bjp.0704873
Contractile responses to adenosine, R‐PIA and ovalbumen in passively sensitized guinea‐pig isolated airways
Authors: Martin Timothy J , Broadley Kenneth J
Published: November 2002

Responses to adenosine, R‐PIA and ovalbumen were examined in guinea‐pig isolated superfused tracheal spirals to determine the effects of passive sensitization by overnight incubation in serum from ovalbumen (OA)‐sensitized or non‐sensitized guinea‐pigs.

Tissues incubated with serum from non‐sensitized and OA‐sensitized guinea‐pigs contracted (0.07±0.02 and 0.04±0.01 g, respectively) to adenosine (300 μM) whereas non‐incubated or Krebs‐incubated tissues produced no contractions to adenosine or ovalbumen (10 μg). Ovalbumen caused substantial contractions (0.40±0.09 g) after OA‐sensitized serum incubation and significantly (P<0.05) smaller contractions (0.08±0.03 g) after non‐sensitized serum incubation. Tracheae from guinea‐pigs actively sensitized to ovalbumen 14–21 days beforehand also contracted to adenosine, R‐PIA (3 μM) and ovalbumen.

The A1/A2 adenosine receptor antagonist, 8‐phenyltheophylline (8‐PT, 3 μM), failed to antagonize these contractions, suggesting that A1/A2 adenosine receptors were not involved.

Unlike adenosine, R‐PIA (3 μM) produced contractions in non‐incubated (0.23±0.04 g) or Krebs‐incubated (0.15±0.04 g) tracheae, as well as after passive and active sensitization. None of these responses were blocked by 8‐PT.

The A3 receptor agonist, IB‐MECA, in the presence of 8‐PT produced small contractions in passively sensitized tracheae (10 μM, 0.02±0.003 g) and, in larger doses (100 μM and 1 mM), contracted actively sensitized tracheae.

In actively sensitized trachea, the A3 receptor antagonist, MRS‐1220 (100 nM), significantly (P<0.05) attenuated adenosine contractions in the presence of 8‐PT from 0.23±0.07 g to 0.07±0.03 g.

These results show that passive, like active sensitization, reveals bronchoconstrictions to adenosine of isolated tracheae. The insensitivity to 8‐PT blockade, the antagonism by MRS‐1220, and the fact that the A3 receptor agonist, IB‐MECA, mimics this response, suggest involvement of A3 receptors. R‐PIA, however, has a different profile of adenosine receptor activity.

British Journal of Pharmacology (2002) 137, 729–738. doi:10.1038/sj.bjp.0704902
Leptin potentiates IFN‐γ‐induced expression of nitric oxide synthase and cyclo‐oxygenase‐2 in murine macrophage J774A.1
Authors: Raso Giuseppina Mattace , Pacilio Maria , Esposito Emanuela , Coppola Anna , Di Carlo Raffaele , Meli Rosaria
Published: November 2002

Leptin, a pleiotropic hormone believed to regulate body weight, has recently been associated with inflammatory states and immune activity. Here we have studied the effect of leptin on expression of IFN‐γ‐induced nitric oxide synthase (iNOS) and cyclo‐oxygenase‐2 (COX‐2), both prominent markers of macrophage activation, using the murine macrophage J774A.1 cell line.

After 24 h of incubation, leptin (1–10 μg ml−1) potently synergized with IFN‐γ (100 U ml−1) in nitric oxide (NO) release, evaluated as nitrite and nitrate (NOx), and prostaglandin E2 (PGE2) production in culture medium.

The observed increase of NO and PGE2 was related to enhanced expression of the respective inducible enzyme isoforms, measured in mRNA and protein by RT–PCR and Western blot analysis, respectively.

When cells were stimulated only with leptin, a weak induction of NO and PGE2 release and of the expression of related inducible enzymes was observed.

Moreover IFN‐γ increased the expression of the functional form of leptin receptor (Ob‐Rb) and this effect was potentiated by leptin in a concentration‐dependent manner.

These data suggest that macrophages, among the peripheral immune cells, represent a target for leptin and confirm the relevance of this hormone in the pathophysiology of inflammation.

British Journal of Pharmacology (2002) 137, 799–804. doi:10.1038/sj.bjp.0704903
Cyclosporine A regulate oxidative stress‐induced apoptosis in cardiomyocytes: mechanisms via ROS generation, iNOS and Hsp70
Authors: Chen Huei‐Wen , Chien Chiang‐Ting , Yu Sung‐Liang , Lee Yuan‐Teh , Chen Wen‐Jone
Published: November 2002

Previous study suggested that cyclosporine A (CsA) could partially reduce ischaemia/reperfusion‐induced injury in isolated heart, but the mechanism was still unclear. In this study, the possible mechanisms of cyclosporine A in regulating oxidative stress‐induced cardiomyocyte apoptosis were examined.

Morphological (cell shrinkage, apoptotic body formation, and DNA fragmentation) and biochemical (annexin‐V staining for exposed phosphatidylserine residues) evidences showed that both hydrogen peroxide (H2O2) and hypoxia/reoxygenation could induce apoptotic change in the embryonal rat heart myoblast‐derived cells (H9c2). These effects were inhibited by pre‐treatment with CsA at concentration of 0.01–1.0 μM for 24 h, but were increased with 10.0 μM CsA.

While examining the mechanisms of CsA in protecting cardiomyocyte apoptosis, we found that the collapse of mitochondria membrane potential (ΔΨm) induced by oxidative stress was partially reversed by CsA (0.01–1.0 μM).

Compared to the control, CSA at the concentration of 0.1 and 10.0 μM significantly increased the level of intracellular reactive oxygen species (ROS) to 117.2±12.4% and 234.4±9.3%, respectively. Co‐incubating with the antioxidant, ascorbic acid (10.0 μM), could partially reduce the protective effect of CsA (0.01–1.0 μM) and the toxic effect of 10.0 μM CsA.

Pre‐treatment with CsA at concentration of 0.01–1.0 μM for 24 h produced up‐regulation of heat shock protein 70 (Hsp 70), inducible nitric oxide synthase (iNOS) and also induced NO production, indicating that these factors might be associated with the cell protective effects of CsA.

These results suggest that CsA could protect the oxidative stress‐induced cardiomyocyte apoptosis not only by preventing the loss of ΔΨm in mitochondria, but also through ROS generation, Hsp70, and iNOS up‐regulation.

British Journal of Pharmacology (2002) 137, 771–781. doi:10.1038/sj.bjp.0704908
Differential effects of organic calcium‐channel blockers on diastolic SR calcium‐handling in the frog heart
Authors: Subramani Sathya , Vijayanand Caroline , Tharion Elizabeth
Published: November 2002

Gradual loss of sarcoplasmic reticular (SR) calcium during a rest‐period is responsible for the rest‐induced decay (RID) of force in mammalian myocardium. Effect of verapamil and diltiazem on a similar RID in the frog myocardium suggests a new mechanism of action of these drugs.

Strips of frog‐ventricle were paced at 0.2 Hz and the rhythm was interrupted by varying rest‐periods ranging from 10 to 180 s. In control conditions, the amplitude of the post‐rest beat was significantly lower than that of the pre‐rest beat for rest‐periods more than 40 s (RID).

Verapamil and diltiazem (which are organic calcium‐channel blockers (OCCB)) changed the pattern of RID in the control solution to a ‘rest‐induced potentiation’ (RIP) in the same preparation while another OCCB nifedipine and the inorganic calcium‐channel blocker cadmium did not alter the post‐rest phenomenon.

We propose that verapamil and diltiazem produce an RIP due to either blockade of SR calcium‐leak during rest or enhancement of SR calcium‐uptake during rest.

British Journal of Pharmacology (2002) 137, 756–760. doi:10.1038/sj.bjp.0704921
Gingerols: a novel class of vanilloid receptor (VR1) agonists
Authors: Dedov Vadim N , Tran Van H , Duke Colin C , Connor Mark , Christie MacDonald J , Mandadi Sravan , Roufogalis Basil D
Published: November 2002

Gingerols, the pungent constituents of ginger, were synthesized and assessed as agonists of the capsaicin‐activated VR1 (vanilloid) receptor.

[6]‐Gingerol and [8]‐gingerol evoked capsaicin‐like intracellular Ca2+ transients and ion currents in cultured DRG neurones. These effects of gingerols were blocked by capsazepine, the VR1 receptor antagonist.

The potency of gingerols increased with increasing size of the side chain and with the overall hydrophobicity in the series.

We conclude that gingerols represent a novel class of naturally occurring VR1 receptor agonists that may contribute to the medicinal properties of ginger, which have been known for centuries. The gingerol structure may be used as a template for the development of drugs acting as moderately potent activators of the VR1 receptor.

British Journal of Pharmacology (2002) 137, 793–798. doi:10.1038/sj.bjp.0704925
Inhibitory mechanism of vascular endothelial growth factor (VEGF) by bucillamine
Authors: Koyama Shinji , Takagi Hitoshi , Otani Atsushi , Oh Hideyasu , Nishimura Kazuo , Honda Yoshihito
Published: November 2002

Vascular endothelial growth factor (VEGF) plays an important role in the neovascularization of ischaemic retinal diseases such as proliferative diabetic retinopathy. We determined that bucillamine, an anti‐rheumatic drug, inhibits the VEGF production induced by hypoxia in bovine retinal microcapillary endothelial cells (BREC). To further clarify the inhibitory mechanism, we investigated the possible mechanism by which bucillamine exerts this inhibitory effect.

Bucillamine (100 μM) decreased the hypoxia‐induced increase of VEGF mRNA by 54.5% (P<0.001). Bucillamine (100 μM) reduced the hypoxia‐induced VEGF content in culture media by 29.0% (P<0.001), while monosulfydryl drugs, N‐acetylcysteine and D‐penicillamine, did not.

Bucillamine (100 μM) did not affect VEGF mRNA half‐life (hypoxia, 4.3 h; hypoxia+bucillamine, 3.9 h; normoxia, 2.7 h; normoxia+bucillamine, 2.7 h).

Reporter gene studies revealed that bucillamine reduced transcriptional activity in the 5′‐flanking region of the VEGF gene by 74.0%. Hypoxia stimulated binding activity of BREC nuclear protein to a hypoxia responsive element (HRE), which was decreased by bucillamine.

Bucillamine inhibited hypoxic‐induction of HIF‐1α mRNA by 73.1% (P<0.001). Bucillamine also inhibited spontaneous VEGF mRNA expression by 26.6%. Furthermore, it inhibited activity of VEGF promoter and decreased binding activity to Sp1 and HRE, but did not alter AP1 and AP2 activity in normoxia.

These data suggest that bucillamine inhibits hypoxic induction of VEGF through inhibition of HIF‐1 induction and binding activity in BREC. Bucillamine also inhibits the spontaneous expression of VEGF mRNA by its effect on Sp1 and HRE binding.

British Journal of Pharmacology (2002) 137, 901–909. doi:10.1038/sj.bjp.0704929
Zebrafish M2 muscarinic acetylcholine receptor: cloning, pharmacological characterization, expression patterns and roles in embryonic bradycardia
Authors: Hsieh Dennis Jine‐Yuan , Liao Ching‐Fong
Published: November 2002

A zebrafish M2 muscarinic acetylcholine receptor (mAChR) gene was cloned. It encodes 495 amino acids in a single exon. The derived amino acid sequence is 73.5% identical to its human homologue.

Competitive binding studies of the zebrafish M2 receptor and [3H]‐NMS gave negative log dissociation constants (pKi) for each antagonist as follows: atropine (9.16)>himbacine (8.05)4‐DAMP (7.83)>AF‐DX 116 (7.26)pirenzepine (7.18)tropicamide (6.97)methoctramine (6.82)p‐F‐HHSiD (6.67)>carbachol (5.20). The antagonist affinity profile correlated with the profile of the human M2 receptor, except for pirenzepine.

Reverse transcription polymerase chain reaction and Southern blotting analysis demonstrated that the M2 mAChR mRNA levels increased during the segmentation period (12 h post‐fertilization; h.p.f.) in zebrafish. By whole‐mount in situ hybridization, the M2 mAChR was first detectable in the heart, vagus motor ganglion, and vagus sensory ganglion at 30, 48 and 60 h.p.f., respectively.

The muscarinic receptor that mediates carbachol (CCh)‐induced bradycardia was functionally mature at 72 h.p.f. The effect of CCh‐induced bradycardia was antagonized by several muscarinic receptor antagonists with the order of potency (pIC50 values): atropine (6.76)>methoctramine (6.47)>himbacine (6.10)>4‐DAMP (5.72)>AF‐DX 116 (4.77), however, not by pirenzepine, p‐F‐HHSiD, or tropicamide (<10 μM).

The effect of CCh‐induced bradycardia was abolished completely before 56 h.p.f. by M2 RNA interference, and the bradycardia effect gradually recovered after 72 h.p.f. The basal heart rate was increased in embryos injected with M2 mAChR morpholino antisense oligonucleotide (M2 MO) and the effect of CCh‐induced bradycardia was abolished by M2 MO in a dose‐dependent manner. In conclusion, the results suggest that the M2 mAChR inhibit basal heart rate in zebrafish embryo and the M2 mAChR mediates the CCh‐induced bradycardia.

British Journal of Pharmacology (2002) 137, 782–792. doi:10.1038/sj.bjp.0704930
Respiratory actions of vanilloid receptor agonists in the nucleus of the solitary tract: comparison of resiniferatoxin with non‐pungent agents and anandamide
Authors: Geraghty Dominic P , Mazzone Stuart B
Published: November 2002

Activation of vanilloid receptors on sensory nerve terminals in the commissural nucleus of the solitary tract (cNTS) of rats with capsaicin, produces respiratory slowing. In this study, we used microinjection techniques employing pungent and non‐pungent vanilloids to further characterize vanilloid receptors in the cNTS.

Microinjection of the pungent vanilloid, resiniferatoxin (RTX), into the cNTS of urethane‐anaesthetized rats, dose‐dependently reduced respiratory rate without affecting tidal volume. RTX was 20 fold more potent at slowing respiration (∼ED50, 100 pmol) than capsaicin (∼ED50, 2 nmol). Doses of RTX greater than 100 pmol caused either irregular (dyspnoeic) breathing or terminal apnoea (>250 pmol). The respiratory slowing response to RTX (75 pmol), was dose‐dependently attenuated by injecting RTX (but not vehicle) into the same site 60 min earlier.

The non‐pungent phorbol derivative of RTX, phorbol 12‐phenylacetete 13‐acetate 20‐homovanillate (PPAHV, 0.1–1 nmol), also slowed respiration (ED50, ∼1 nmol) and almost abolished response to RTX (75 pmol) injected into the same site 60 min later.

In contrast to RTX, PPAHV and capsaicin, the putative endogenous vanilloid receptor agonist, arachidonyl ethanolamide (AEA), and non‐pungent capsaicin derivative, olvanil, had no direct effect on respiration. However, both AEA and olvanil dose‐dependently reduced the respiratory response to injection of RTX (75 pmol) 60 min later into the same site (EC50s, for AEA and olvanil, ∼2 and 0.2 nmol, respectively).

These studies suggest that both pungent and non‐pungent vanilloids interact with vanilloid receptors in the cNTS. However, whereas RTX and PPAHV activate and subsequently desensitize vanilloid receptors on sensory nerve terminals in the cNTS, olvanil and AEA fail to activate despite readily desensitizing responses to RTX in this region.

British Journal of Pharmacology (2002) 137, 919–927. doi:10.1038/sj.bjp.0704931
Mechanism of lonidamine inhibition of the CFTR chloride channel
Authors: Gong Xiandi , Burbridge Susan M , Lewis Angie C , Wong Patrick Y D , Linsdell Paul
Published: November 2002

The cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel is blocked by a broad range of organic anionic compounds. Here we investigate the effects of the indazole compound lonidamine on CFTR channels expressed in mammalian cell lines using patch clamp recording.

Application of lonidamine to the intracellular face of excised membrane patches caused a voltage‐dependent block of CFTR currents, with an apparent Kd of 58 μM at −100 mV.

Block by lonidamine was apparently independent of channel gating but weakly sensitive to the extracellular Cl− concentration.

Intracellular lonidamine led to the introduction of brief interruptions in the single channel current at hyperpolarized voltages, leading to a reduction in channel mean open time. Lonidamine also introduced a new component of macroscopic current variance. Spectral analysis of this variance suggested a blocker on rate of 1.79 μM−1 s−1 and an off‐rate of 143 s−1.

Several point mutations within the sixth transmembrane region of CFTR (R334C, F337S, T338A and S341A) significantly weakened block of macroscopic CFTR current, suggesting that lonidamine enters deeply into the channel pore from its intracellular end.

These results identify and characterize lonidamine as a novel CFTR open channel blocker and provide important information concerning its molecular mechanism of action.

British Journal of Pharmacology (2002) 137, 928–936. doi:10.1038/sj.bjp.0704932
Hypoxia‐induced down‐regulation of CYP1A1/1A2 and up‐regulation of CYP3A6 involves serum mediators
Authors: Fradette Caroline , Bleau Anne‐Marie , Pichette Vincent , Chauret Nathalie , Du Souich Patrick
Published: November 2002

Acute moderate hypoxia modifies the catalytic activity and expression of certain isoenzymes of hepatic cytochrome P450 (P450). The aim of this study was to document whether hypoxia affects hepatic P450 directly or through the release of serum mediators.

Rabbits were subjected to a FiO2of 8% for 48 h, sacrificed, and serum and hepatocytes were isolated; hepatocytes from control and rabbits with hypoxia were incubated with serum from control and hypoxic rabbits for 4 and 24 h, and total P450 content, CYP1A1, 1A2 and 3A6 activities and expressions were assessed. Sera were fractionated by size exclusion chromatography and fractions tested for their ability to modify activity and amount of P450, and serum mediators were identified through neutralization experiments.

Total serum and fractions with proteins of 15–23 and 65–94 kDa of Mrreduced P450 content and expression of CYP1A1, 1A2 and 3A6, as well asCYP1A1,1A2and3A6mRNA. Total serum and the fraction with 32–44 kDa proteins increased CYP3A6 activity and protein and mRNA. The serum mediators implicated in the decrease in activity and expression of CYP1A1, 1A2 and 3A6 were interferon‐γ (IFN‐γ), interleukin‐1β (IL‐1β) and IL‐2. Erythropoietin (Epo) was partly responsible for the increase in P450 content and CYP3A6 expression.

In conclusion, acute moderate hypoxia diminishes the activity and expression of CYP1A1, 1A2 andCYP1A1,1A2mRNA, and increases CYP3A6 protein, activity andCYP3A6mRNA. Several mechanisms contribute to these changes in P450, among them the release of cytokines acting as serum mediators.

British Journal of Pharmacology(2002)137, 881–891. doi:10.1038/sj.bjp.0704933
Inhibitors of poly(ADP‐ribose) polymerase‐1 suppress transcriptional activation in lymphocytes and ameliorate autoimmune encephalomyelitis in rats
Authors: Chiarugi Alberto
Published: November 2002

In the presence of genotoxic stress poly(ADP‐ribose) polymerase‐1 (PARP‐1) leads to NAD+ and ATP depletion, participating in the pathogenesis of several disorders including inflammation. Accordingly, chemical inhibitors of PARP‐1 are efficacious anti‐inflammatories, albeit the underlying molecular mechanisms are still under debate.

This study investigated the effect of the PARP‐1 inhibitors 6(5H)‐phenanthridinone and benzamide as well as that of benzoic acid, an inactive analogue of benzamide, on development of experimental allergic encephalomyelitis (EAE) in rats. Both 6(5H)‐phenanthridinone and benzamide attenuated development of EAE, reducing clinical score, neuroimmune infiltration and expression of inflammatory mediators such as inducible nitric oxide synthase, interleukin‐1β and ‐2, cyclooxygenase‐2, tumour necrosis factor‐α and interferon‐γ in the spinal cord of myelin‐immunized rats. Importantly, no evidence of NAD+ and ATP depletion as well as poly(ADP‐ribose) formation was detected in the spinal cord.

By contrast, a robust formation of poly(ADP‐ribose) occurred in B‐ and T‐cell areas in lymph nodes of myelin‐immunized rats and was suppressed by the treatment with 6(5H)‐phenanthridinone and benzamide. In cultures of activated rat lymphocytes, 6(5H)‐phenanthridinone and benzamide reduced the DNA‐binding activity of NF‐κB and AP‐1 and transcription of pro‐inflammatory cytokines such as interleukin‐2, interferon‐γ and tumour necrosis factor‐α.

Notably, benzoic acid did not reproduce the in vivo and in vitro effects of its parent compound.

These findings indicate that PARP‐1 promotes transcriptional activation in lymphocytes and inhibitors of its enzymatic activity are useful for the treatment of autoimmune disorders of the central nervous system.

British Journal of Pharmacology (2002) 137, 761–770. doi:10.1038/sj.bjp.0704934
Selective inhibitors of cyclo‐oxygenase‐2 (COX‐2) induce hypoalgesia in a rat paw model of inflammation
Authors: Francischi J N , Chaves C T , Moura A C L , Lima A S , Rocha O A , Ferreira‐Alves D L , Bakhle Y S
Published: November 2002

It is well‐established that inhibitors of cyclo‐oxygenase (COX) and hence of prostaglandin (PG) biosynthesis reverse inflammatory hyperalgesia and oedema in both human and animal models of inflammatory pain.

Paw oedema and hyperalgesia in rats were induced by injecting carrageenan (250 μg paw−1) into a hindpaw. Both inflammatory responses were followed for 24 h after the injection, measuring hyperalgesia by decreased pain threshold in the paws and oedema by plethysmography.

Three selective inhibitors of cyclo‐oxygenase‐2 (COX‐2), celecoxib, rofecoxib and SC 236, given systemically in a range of doses, before the inflammatory stimulus, abolished carrageenan‐induced hyperalgesia with little reduction of oedema. These inhibitors also induced hypoalgesia, increasing nociceptive thresholds in the inflamed paw above normal, non‐inflamed levels. This hypoalgesia was lost at the higher doses of the selective inhibitors, although hyperalgesia was still prevented.

In paws injected with saline only, celecoxib, given at the dose inducing the maximum hypoalgesia after carrageenan, did not alter the nociceptive thresholds.

Two non‐selective inhibitors of COX‐2, indomethacin and piroxicam, abolished hyperalgesia and reduced oedema but did not induce hypoalgesia.

Celecoxib given locally into the paw also abolished inflammatory hyperalgesia and induced hypoalgesia without reducing oedema.

We conclude that hypoalgesia is expressed only over a critical range of COX‐2 inhibition and that concomitant inhibition of COX‐1 prevents expression of hypoalgesia, although hyperalgesia is still prevented.

Our results suggest a novel anti‐nociceptive pathway mediating hypoalgesia, involving COX‐2 selectively and having a clear peripheral component. This peripheral component can be further explored for therapeutic purposes.

British Journal of Pharmacology (2002) 137, 837–844. doi:10.1038/sj.bjp.0704937
The mechanisms for tachykinin‐induced contractions of the rabbit corpus cavernosum
Authors: Takahashi Ryosuke , Nishimura Junji , Hirano Katsuya , Naito Seiji , Kanaide Hideo
Published: November 2002

This study was designed to investigate the mechanisms for the contractions induced by tachykinins (substance P (SP), neurokinin A (NKA) and neurokinin B (NKB)) in the rabbit corpus cavernosum strips, using fura‐PE3 fluorimetry and α‐toxin permeabilization.

Tachykinins induced contractions in the rabbit corpus cavernosum in a concentration‐dependent manner. The potency order was SP>NKA>NKB.

The tachykinin‐induced contractions were enhanced by phosphoramidon (PPAD), an endopeptidase inhibitor, but not by Nω‐nitro‐L‐arginine methylester (L‐NAME).

The NK1 receptor selective antagonist, SR 140333 significantly inhibited the tachykinin‐induced contractions. Although the NK2 receptor selective antagonist, SR 48968 alone did not influence the effects of tachykinins, it potentiated the inhibitory effect of SR 140333. The NK3 receptor selective antagonist, SR142801 had no effect.

In the rabbit corpus cavernosum, tachykinins induced sustained increases in [Ca2+]i and tension in normal PSS, while only small transient increases in [Ca2+]i and tension were observed in Ca2+‐free solution.

In α‐toxin permeabilized preparations, tachykinins induced an additional force development at a constant [Ca2+]i.

These results indicated that in the rabbit corpus cavernosum: (1) Tachykinins induced contractions by increasing both the [Ca2+]i and myofilament Ca2+ sensitivity; (2) The tachykinin‐induced [Ca2+]i elevations were mainly due to the Ca2+ influx; (3) Tachykinin‐induced contractions were mainly mediated through the activation of NK1 receptor expressed in the rabbit corpus cavernosum smooth muscle, and affected by the endopeptidase activity and (4) Tachykinins may thus play a role in controlling the corpus cavernosum tone.

British Journal of Pharmacology (2002) 137, 845–854. doi:10.1038/sj.bjp.0704938
A novel phenoxazine derivative suppresses surface IgM expression in DT40 B cell line
Authors: Gao Sanyang , Takano Tomoko , Sada Kiyonao , He Jinsong , Noda Chiseko , Hori‐Tamura Naoko , Tomoda Akio , Yamamura Hirohei
Published: November 2002

2‐amino‐4, 4α‐dihydro‐4α, 7‐dimethyl‐3H‐phenoxazine‐3‐one (Phx) has been demonstrated to be an actinomycin D‐like phenoxazine, and to display anti‐tumour activity.

In this study, we report on the effect of Phx on B cell antigen receptor (BCR) and receptor‐mediated signalling in DT40 B cells.

Treatment of B cells with Phx for 12 h inhibited BCR‐stimulated tyrosine phosphorylation of cellular proteins.

B cells exposed to Phx exhibited down‐regulation of surface IgM which is part of BCR. In contracts with actinomycin D, Phx rapidly reduced the expression of IgM without decreasing the expression of other signalling molecules.

Analysis with confocal microscopy demonstrated that Phx treatment reduced IgM expression both at the cell surface and inside the cell.

Treatment of B cells with Phx resulted in the reduction of IgM secretion. Since MG‐132, a proteasomal inhibitor, restored IgM contents to the control levels, Phx has the specific effect of accelerating IgM degradation.

These results suggest that Phx down‐regulates the expression of IgM and inhibits BCR‐mediated signalling and IgM secretion. Phx may be useful as an immunosuppressive agent for therapeutic purposes.

British Journal of Pharmacology (2002) 137, 749–755. doi:10.1038/sj.bjp.0704939
Guanidinoethyl sulphonate is a glycine receptor antagonist in striatum
Authors: Sergeeva Olga A , Chepkova Aisa N , Haas Helmut L
Published: November 2002

Guanidinoethyl sulphonate (GES) is an analogue of taurine and an inhibitor of taurine transport. Interactions of GES with GABAA and glycine receptors are studied by whole cell recording and fast drug application in isolated striatal neurons of the mouse.

We confirm that GES is a weak agonist at GABAA receptors, and is able to antagonize GABA‐evoked responses. GES did not gate GlyR.

GES antagonized glycine responses in a concentration‐dependent and surmountable manner. Glycine dose–response curves were shifted to the right by GES (0.5 mM), yielding EC50s and Hill coefficients of 62 μM and 2.5 in control, 154 μM and 1.3 in the presence of GES.

GlyR‐mediated taurine responses were competitively antagonized by GES. Taurine dose–response curves, in contrast to the glycine dose–response curves were shifted by GES to the right in a parallel manner.

The GlyR‐block by GES was not voltage‐dependent.

In contrast to our findings in the mouse, in rat striatal neurons which lack expression of the α3 GlyR subunit, GES shifted the glycine dose–response curve to the right in a parallel way without affecting the maximal response. Subtype‐specificity of the GES action at GlyR must await further investigation in artificial expression systems.

We conclude that GES is a competitive antagonist at GlyR. The antagonistic action of GES at inhibitory ionotropic receptors can explain its epileptogenic action. Care must be taken with the interpretation of data on GES evoked taurine release.

British Journal of Pharmacology (2002) 137, 855–860. doi:10.1038/sj.bjp.0704940
Modulation of reflexly evoked vagal bradycardias by central 5‐HT1A receptors in anaesthetized rabbits
Authors: Skinner Matthew R , Ramage Andrew G , Jordan David
Published: November 2002

The role of central 5‐HT1A receptors in the control of the bradycardia and changes in central respiratory drive, renal nerve activity and blood pressure evoked by stimulating cardiopulmonary afferents with phenylbiguanide, baroreceptors by electrical stimulation of the aortic nerve and chemoreceptors by injections of sodium cyanide (NaCN) in atenolol‐pretreated anaesthetized rabbits were studied.

Buspirone (100 μg kg−1; i.c.) potentiated the bradycardia (increase in R‐R interval) and the changes in blood pressure and renal nerve activity evoked by all three reflexes. These effects could be attenuated by pretreatment with the 5‐HT1A receptor antagonist WAY‐100635 (100 μg kg−1); i.v.), which alone had no effect on these reflex‐evoked changes. However, WAY‐100635 (100 μg kg−1; i.c.) did attenuate these reflex‐evoked responses produced by activation of cardiopulmonary and aortic baroreceptors but not that caused by stimulation of chemoreceptors. When given i.v., buspirone was less effective in modulating the responses evoked by these three reflexes.

The present data are consistent with the view that central 5‐HT1A receptors play a role in the reflex activation of cardiac preganglionic vagal motoneurones. However, although antagonists of 5‐HT1A receptors affected the responses evoked by cardiopulmonary and aortic nerve afferents, they were not effective on chemoreceptor reflex‐evoked changes. This suggests that 5‐HT1A receptors play a different role in chemoreceptor pathways compared to that for the other reflexes. This may relate to the fact that the chemoreceptor afferents travel in the IXth (glossopharyngeal) nerve whilst the other afferents travel in the Xth (vagus) nerve and thus may use different central circuitry and neurotransmitters.

British Journal of Pharmacology (2002) 137, 861–873. doi:10.1038/sj.bjp.0704941