bluuebunny/crossref_metadata_2025 huggingface dataset:
Decomposition of hair lichens (Alectoria Sarmentosa and Bryoria spp.) Under Snowpack in Montane Forest, Cariboo Mountains, British Columbia
Authors: Coxson Darwyn S. , Curteanu Medea
Published: January 2003

Montane old-growth forests on the windward slopes of interior mountain ranges in British Columbia support high loadings of arboreal lichens. These lichens represent a major source of readily labile plant material and potentially play an important role in ecosystem nutrient dynamics. Given the role of winter storms in scouring lichens from within the canopy and the extended length of winter snowpack, from November through to May or even early June, in these ecosystems, the decomposition of lichen litterfall should be heavily influenced by placement within the snowpack. We have examined this factor by placing litter bags containing samples of the hair lichens, Alectoria sarmentosa and Bryoria spp., on top of the winter snowpack in the Cariboo Mountains. Samples were set out in early- (8 Nov.) mid- (16 Jan.) and late- (22 Mar.) winter and subsequently retrieved on spring snow-melt (22 May). Lichen samples that were buried in the lower snowpack all winter long (196 days) lost two-thirds of their original mass. In contrast lichens placed on the snowpack in mid- (127 days) or late-winter (61 days) lost only 6-15% of their total mass, far less than would be predicted on the basis of time in snowpack alone. Spot measurements showed that the snowpack environment effectively buffers litter samples from extreme winter conditions. All lichen samples placed within the snowpack showed much higher C/N ratios on removal, indicating rapid leaching of readily soluble cellular constituents in the snowpack environment. These findings indicate that the snowpack environment plays a major role in decomposition processes in these high-elevation forests and reinforces our view that lichens are a readily labile nutrient source within these ecosystems.
Induction of differentiation rescues HL‐60 cells from Rana catesbeiana ribonuclease‐induced cell death
Authors: Wei Chyou-Wei , Hu Chih-Chi Andrew , Tang Chih-Hang Anthony , Lee Ming-Chieh , Wang Jaang-Jiun
Published: January 2003

Rana catesbeiana ribonuclease (RC‐RNase) exerted strong anti‐tumor activity and its cytotoxicity was shown to correlate with differentiation stages of three different hepatoma cell lines. In this study, we demonstrate different RC‐RNase cytotoxicity in undifferentiated HL‐60 cells and in those that had been induced to differentiate by retinoic acid or dimethylsulfoxide. RC‐RNase showed cytotoxicity in undifferentiated HL‐60 cells, but not in HL‐60 cells undergoing terminal differentiation. Furthermore, the caspase‐9/caspase‐3 pathway was activated when RC‐RNase induced death in undifferentiated HL‐60 cells and induction of differentiation led to a reversal of the caspase activation pathway.
New potent inhibitors of aquaporins: silver and gold compounds inhibit aquaporins of plant and human origin
Authors: Niemietz Christa M , Tyerman Stephen D
Published: January 2003

Silver and gold compounds were tested as potential inhibitors of aquaporins of plant‐ and human origin. Silver as AgNO3 or silver sulfadiazine inhibited with high potency (EC50 1–10 μM) the water permeability of the peribacteroid membrane from soybean (containing Nodulin 26), the water permeability of plasma membrane from roots (containing plasma membrane integral proteins), and the water permeability of human red cells (containing aquaporin 1). Gold as HAuCl4 was less effective but still inhibited peribacteroid membrane water permeability (EC50=10 μM). Silver and gold are more potent inhibitors of aquaporins than the presently widely used mercury containing compounds.
Heterologous expression of dihydroflavonol 4‐reductases from various plants
Authors: Martens Stefan , Teeri Teemu , Forkmann Gert
Published: January 2003

Dihydroflavonol 4‐reductases (DFR) catalyze the stereospecific reduction of dihydroflavonols to the respective flavan 3,4‐diols (leucoanthocyanidins) and might also be involved in the reduction of flavanones to flavan‐4‐ols, which are important intermediates in the 3‐deoxyflavonoid pathway. Several cDNA clones encoding DFR have been isolated from different plant species. Despite the important function of these enzymes in the flavonoid pathway, attempts at heterologous expression of cDNA clones in Escherichia coli have failed so far. Here, three well known heterologous expression systems for plant‐derived genes were tested to obtain the functional protein of DFR from Gerbera hybrids. Successful synthesis of an active DFR enzyme was achieved in eukaryotic cells, using either baker's yeast (Saccharomyces cerevisiae) or tobacco protoplasts (Nicotiana tabacum), transformed with expression vectors containing the open reading frame of Gerbera DFR. These expression systems provide useful and powerful tools for rapid biochemical characterization, in particular the substrate specificity, of the increasing number of cloned DFR sequences. Furthermore, this tool allows the stereospecific synthesis of 14C‐labeled leucoanthocyanidins in high quality and quantity, which is a prerequisite for detailed biochemical investigation of the less understood enzymatic reactions located downstream of DFR in anthocyanin, catechin and proanthocyanidin biosynthesis.
Matrix metalloproteinase 2 is involved in the regulation of the antimicrobial peptide parasin I production in catfish skin mucosa
Authors: Cho Ju Hyun , Park In Yup , Kim Mi Sun , Kim Sun Chang
Published: January 2003

A 19‐residue antimicrobial peptide parasin I is generated from histone H2A in the skin mucus of catfish by the action of cathepsin D activated by a procathepsin D‐processing enzyme induced upon epidermal injury. Here we report the isolation and characterization of the procathepsin D‐processing enzyme in the mucus of wounded catfish. Sequence analysis of the cDNA identified the purified procathepsin D‐processing enzyme as matrix metalloproteinase 2 (MMP 2). By acting as a procathepsin D convertase upon epidermal injury, MMP 2 is involved in the regulation of parasin I production in catfish skin mucosa.
Stimulation of IKK‐γ oligomerization by the human T‐cell leukemia virus oncoprotein Tax
Authors: Huang Guo-Jin , Zhang Zhi-Qing , Jin Dong-Yan
Published: January 2003

Human T‐cell leukemia virus type 1 oncoprotein Tax activates NF‐κB through direct binding to IKK‐γ, the regulatory component of the IκB kinase complex. Mechanisms by which IKK‐γ adapts the Tax signal to the IκB kinase are poorly understood. Here we demonstrate that IKK‐γ forms homodimer and homotrimer both in vitro and in yeast or mammalian cells through a C‐terminal domain comprising amino acids 251–419. In contrast, Tax protein targets a central region of IKK‐γ, which consists of amino acids 201–250. Interestingly, Tax stimulates the oligomerization of IKK‐γ, likely through direct binding. Taken together, our findings suggest a new model of Tax activation of NF‐κB, in which Tax interacts with IKK‐γ to stimulate its oligomerization.
Activated Gαq family members induce Rho GTPase activation and Rho‐dependent actin filament assembly
Authors: Dutt Parmesh , Kjoller Lars , Giel Maryann , Hall Alan , Toksoz Deniz
Published: January 2003

Rho GTPase is required for actin filament assembly and serum response element (SRE)‐dependent gene transcription. Certain G protein‐coupled receptors (GPCRs) induce Rho‐dependent responses, but the intermediary signaling steps are poorly understood. The heterotrimeric Gα12 family can induce Rho‐dependent responses. In contrast, there are conflicting reports on the role of the Gαq family in Rho signaling. We report that expression of activated Gαq members, or activation of endogenous Gαq via GPCR stimulation, induces SRE reporter activation via Rho, and increased GTP‐Rho levels. Moreover, microinjection of activated Gαq in fibroblasts induces actin stress fiber formation via Rho. Gαq functionally cooperates with Lbc Rho guanine nucleotide exchange factor. Overall, these findings indicate that Gαq family signals are sufficient to induce Rho‐dependent cellular responses.
Comparison of commonly used orthopaedic outcome measures using palm‐top computers and paper surveys
Authors: Saleh Khaled J. , Radosevich David M. , Kassim Rida A. , Moussa Mohamed , Dykes Darrell , Bottolfson Helena , Gioe Terence J. , Robinson Harry
Published: January 2003

Introduction: Measuring patient‐perceived outcomes following orthopaedic procedures have become an important component of clinical research and patient care. General and disease‐specific outcomes measures have been developed and applied in orthopaedics to assess the patients' perceived health status. Unfortunately, paper‐based, self‐administered instruments remain inefficient for collecting data because of: (a) missing data (b) respondent error, and (c) the costs to administer and enter data.

Objective: To study the comparability of palm‐top computer devices and paper‐pencil self‐administered questionnaires in the collection of health‐related quality of life (HRQL) information from patients.

Methods: The comparability of administering HRQL questionnaires using palm‐top computer and traditional paper‐based forms was tested in a sample of 96 patients with complaints of hip and/or knee pain. Each patient completed mailed versions of the Medical Outcomes Study (MOS), 36‐item Health Survey (SF‐36), and Western Ontario and McMasters University Arthritis Index (WOMAC) three weeks prior to presenting to clinic. At the clinic they were asked to complete the same outcomes measures using the palm‐top computer or a paper‐and‐pencil version.

Analysis: In the analysis, scale distributions, floor and ceiling effects, internal consistency and retest reliability of scales were compared across the two data collection methods. Because the baseline characteristics of the groups were not strictly comparable according to age, the data were analyzed for the entire sample and stratified according to age.

Results: Few statistically significant differences were found for the means, variances and intra‐class correlation coefficients between the methods of administration. While the scale distribution between the two methods was comparable, the internal consistency of the scales was dissimilar.

Conclusions: Administration of HRQL questionnaires using portable palm‐top computer devices has the potential advantage of decreased cost and convenience. These data lend some support for the comparability of palm‐top computers and paper surveys for outcomes measures widely used in the field of orthopaedic surgery. The present study identified the lack of reliability across modes of administration that requires further study in a randomized comparability trial. These mode effects are important for orthopaedic surgeons to appreciate before implementing innovative data‐capture technologies in their practices.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
The effects of blood glucose control upon fracture healing in the BB Wistar rat with diabetes mellitus
Authors: Beam Heather A. , Russell Parsons J. , Lin Sheldon S.
Published: January 2003

Several clinical series, analyzing fracture healing in patients with diabetes mellitus (DM), demonstrated significant incidence of delayed union, non‐union, and pseudarthrosis. In this study, analysis was performed to evaluate the effects of blood glucose (BG) control on fracture healing in the DM BB Wistar rat, a rat strain that represents a close homology to Type I DM in man. Our study showed decreased cell proliferation at the fracture site as well as decreased mechanical stiffness and bony content in the poorly controlled DM rats. To determine the effect of BG control, DM rats were treated with insulin sufficient to maintain physiologic BG levels throughout the course of the study. Values of cellular proliferation, biomechanical properties and callus bone content in tightly controlled DM animals were not significantly different from values of non‐DM control values. This study suggests that insulin treatment with resultant improved BG control will ameliorate the impaired early and late parameters of DM fracture healing.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Apoptosis in rotator cuff tendonopathy
Authors: Yuan Jun , Murrell George A. C. , Wei Ai‐Qun , Wang Min‐Xia
Published: January 2003

The aim of this study was to investigate the involvement of apoptosis (programmed cell death) in the pathogenesis of rotator cuff disorders. The edges of torn supraspinatus rotator cuff tendons were collected from patients with rotator cuff tear (n = 25). Samples of the intra‐articular portion of subscapularis tendons were collected from patients without rotator cuff tear as control (n = 6). To minimize individual variance, we also collected six pairs of supraspinatus tendon and subscapularis tendon from six patients with rotator cuff tears. Apoptosis was detected by in situ DNA end labelling assay and DNA laddering assay. Immunohistochemical staining was performed to identify cells undergoing apoptosis. Control subscapularis tendon had normal morphology. Tendon from torn supraspinatus rotator cuff showed significant mucoid degeneration. Within the areas of degeneration, there were large numbers of apoptotic cells. The percentage of apoptotic cells in the degenerative rotator cuff (34%) was significantly higher than that in controls (13%) (p < 0.001). The excessive apoptosis detected in degenerative rotator cuff tissue was confirmed by DNA laddering assays. This is the first report of excessive apoptosis in degenerating rotator cuff tendon. Cells undergoing apoptosis in rotator cuff were mainly fibroblast‐like cells. These finding indicate that apoptosis may play an important role in the pathogenesis of rotator cuff degeneration.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Social phobia in the community: relationship between diagnostic threshold and prevalence
Authors: Pélissolo A. , André C. , Moutard-Martin F. , Wittchen H.U. , Lépine J.P.
Published: January 2003

This paper investigates the prevalence of symptoms and various diagnostic criteria of DSM-IV social phobia in a French national representative population of 12,873 subjects, aged 15 or more. Respondents filled out a mailed questionnaire based on the social phobia section of the Munich-Composite International Diagnostic Interview (M-CIDI) in the year 1996. Response rate was 80.5%.

Sixty-seven point one percent of the sample acknowledge having at least once in their lifetime a strong fear of one or more of the six prototypical social fear situations that are used as the CIDI social phobia stem items. However, only a few fulfilled all DSM-IV diagnostic criteria for social phobia. Depending on the type of diagnostic algorithms used and the stringency in which these criteria are applied, the resulting prevalence varied between 1.9 and 7.3%. These findings provide some further evidence about the considerable effects of varying diagnostic criteria and thresholds on prevalence rates for social phobia, explaining why most recent surveys have reported considerably higher rates of social phobia than those in the early 1980s.
The impact of the gender composition of households on inequality and poverty: a comparison across Russia and Eastern Europe
Authors: Popova Daria
Published: January 2003

This study compares poverty and income distribution among gender subgroups in Russia and four East European countries—Bulgaria, Romania, Hungary and Poland—in 2000. Does the gender poverty gap exist in these countries and if yes, how big is it? How much does the level of gender inequality contribute to explaining the level of aggregate inequality and poverty within each country? To what extent may the differences emerging in cross-country comparisons of poverty and inequality be explained by differences in the gender composition of households, e.g., the prevalence of female-dominated households? These are the questions I seek to answer in this paper.

Equivalent expenditure is adopted as a measure of economic welfare of households with different gender ratios. The gender gap is defined as the degree of distance between the economic welfare of households dominated by women and households dominated by men. Headcount poverty and average poverty shortfalls are calculated using relative poverty lines. Inequality is measured by Gini and Theil L coefficients.
Fertility and childbearing practices among poor Gypsy women in Hungary: the intersections of class, race and gender
Authors: Durst Judit
Published: January 2003

This article explores changes in childbearing practices among Gypsy (Roma) women in a small village in Northern Hungary. The author benefited from several years of ethnographic field research and data collected in this village, where the proportion of the out-of-wedlock births and births to teenage—mostly Gypsy—mothers have increased by a factor of three in the past 10 years as the population of the village has become more and more impoverished and the opportunities for geographic or social mobility declined sharply for the ethnic minority. The author argues that bearing children early is a sign of passage to adulthood in this group of women, a function which had been assigned to other social institutions before 1989. Early childbearing at the same time exacerbates the problem of Gypsy women: this is the first study which documents the consequences of poverty on women's and children's health by showing an increase in low birth weight babies in the community since 1989.
Anomalous effect of anthracene‐9‐carboxylic acid on calcium‐activated chloride currents in rabbit pulmonary artery smooth muscle cells
Authors: Piper Angela S , Greenwood Iain A
Published: January 2003

Ca2+‐activated Cl− currents (ICl(Ca)) evoked by K+‐free pipette solutions containing 500 nM Ca2+ were recorded in rabbit pulmonary artery smooth muscle cells. A voltage step protocol in which the cells were stepped to +70 mV and then to −80 mV produced outward and inward Cl− currents respectively that exhibited distinctive voltage‐ and time‐dependent kinetics that remained consistent for the recording period.

Application of the Cl− channel inhibitor anthracene‐9‐carboxylic acid (A‐9‐C, 500 μM), produced a small inhibition of the maximum outward Cl− current at +70 mV (21±10%) but augmented the amplitude of the instantaneous inward relaxation at −80 mV by 321±34% (n=12).

The current recorded in the absence and presence of A‐9‐C reversed at the theoretical Cl− equilibrium potential and the reversal potential was shifted by about −40 mV upon replacement of external chloride ion by the more permeant anion thiocyanate. Currents in the absence and presence of A‐9‐C were similarly affected by 100 μM niflumic acid.

Augmentation of the inward current at −80 mV by A‐9‐C required prior depolarization, i.e. A‐9‐C did not simply activate a Cl− current at negative membrane potentials. Moreover the degree of augmentation was independent of the internal Ca2+ for concentrations between 100 nM and 1 μM Ca2+.

The data from the present study confirm previous observations that the inhibitory effect of Cl− channel blockers is modified when [Ca2+]i is maintained at higher than normal resting concentrations.

British Journal of Pharmacology (2003) 138, 31–38. doi:10.1038/sj.bjp.0705000
Nitric oxide enhances substance P‐induced itch‐associated responses in mice
Authors: Andoh Tsugunobu , Kuraishi Yasushi
Published: January 2003

Substance P (SP) elicits itch and itch‐associated responses in humans and mice, respectively. In mice, NK1 tachykinin receptors are involved in SP‐induced itch‐associated responses, scratching, and mast cells do not play a critical role. The present study was conducted to elucidate the role of nitric oxide (NO) on SP‐induced scratching in mice.

An intradermal injection of SP (100 nmol site−1) elicited scratching in mice, and it was suppressed by an intravenous injection of the NO synthase (NOS) inhibitor NG‐nitro‐L‐arginine methyl ester (L‐NAME), but not by its inactive enantiomer D‐NAME. Intradermal injections of L‐NAME (100 nmol site−1), another NOS inhibitor 7‐nitroindazole (10 nmol site−1) and the NO scavenger haemoglobin (0.01–10 nmol site−1) also inhibited SP‐induced scratching.

L‐NAME (100 nmol site−1) did not affect scratching induced by an intradermal injection of 5‐hydroxytryptamine (100 nmol site−1).

Intradermal injections of L‐arginine (300 nmol site−1) and the NO donor (±)‐(E)‐4‐ethyl‐2‐[(E)‐hydroxyimino]‐5‐nitro‐3‐hexenamide (NOR3; 100 nmol site−1) increased scratching induced by SP. Intradermal injections of L‐arginine (1–1000 nmol site−1) or NOR3 (1–100 nmol site−1) alone were without effects on scratching.

Intradermal injections of SP (10–100 nmol site−1) increased the intradermal concentration of NO in a dose‐dependent manner in mice. An increase in NO levels induced by SP was inhibited by L‐NAME and the NK1 tachykinin receptor antagonist L‐668,169, but not by the NK2 tachykinin receptor antagonist L‐659,877.

SP (1–10 μM) elicited NO production in cultured human keratinocytes and the SP‐induced NO production was inhibited by L‐NAME and L‐668,169.

We conclude that intradermal SP increases NO in the skin, possibly through the action on NK1 tachykinin receptors on the epidermal keratinocytes and that NO enhances SP‐induced itch‐associated responses.

British Journal of Pharmacology (2003) 138, 202–208. doi:10.1038/sj.bjp.0705004
Parathyroid hormone increases the sensitivity of inositol trisphosphate receptors by a mechanism that is independent of cyclic AMP
Authors: Tovey Stephen C , Goraya Tasmina A , Taylor Colin W
Published: January 2003

In fura 2‐loaded HEK‐293 cells stably expressing human type 1 parathyroid hormone (PTH) receptors, PTH potentiated the Ca2+ mobilization evoked by carbachol by >4 fold without itself increasing the intracellular [Ca2+].

PTH potentiated the Ca2+ release evoked by a cell‐permeant analogue of inositol 1,4,5‐trisphosphate (InsP3BM).

Prolonged incubation with InsP3BM emptied the Ca2+ stores as effectively as PTH in combination with a maximal concentration of carbachol, indicating that PTH did not increase the size of the InsP3‐sensitive Ca2+ pool.

Responses to PTH were unaffected by disruption of the cytoskeleton.

The EC50 for carbachol‐evoked Ca2+ release and InsP3 formation were indistinguishable (∼40 μM), consistent with even the highest concentrations of carbachol generating insufficient InsP3 to release the entire InsP3‐sensitive Ca2+ pool.

Inhibition of cyclic AMP‐dependent protein kinase A (PKA), using H89 or CMIQ, did not affect potentiation of carbachol‐evoked Ca2+ signals by PTH.

SQ22536 or DDA, inhibitors of adenylyl cyclase, inhibited PTH‐evoked cyclic AMP formation and IBMX, an inhibitor of cyclic nucleotide phosphodiesterase, increased the amount of cyclic AMP detected after stimulation by PTH. None of these drugs affected the potentiation of Ca2+ signals by maximal or submaximal concentrations of PTH.

We conclude that PTH potentiates the Ca2+ release evoked by receptors that stimulate InsP3 formation by sensitizing InsP3 receptors through a cyclic AMP‐independent mechanism.

British Journal of Pharmacology (2003) 138, 81–90. doi:10.1038/sj.bjp.0705011
α2 Adrenoceptor‐mediated vasoconstriction in porcine palmar lateral vein: role of phosphatidylinositol 3‐kinase and EGF receptor transactivation
Authors: Roberts R E
Published: January 2003

α2 Adrenoceptors cause vasoconstriction in the porcine palmar lateral vein through a mechanism involving the ERK signal transduction cascade, calcium influx, and a Src tyrosine kinase. The aim of the present study was to determine if phosphatidylinositol 3‐kinase (PI 3‐kinase) and/or epidermal growth factor (EGF) receptor transactivation are also involved.

α2 Adrenoceptor‐mediated vasoconstriction and ERK2 activation in the porcine palmar lateral vein was inhibited in the presence of either the PI 3‐kinase inhibitor LY294002, or the EGF receptor tyrosine kinase inhibitor AG1478 suggesting the involvement of both PI 3‐kinase and EGF receptor transactivation.

Akt phosphorylation was increased in segments of porcine palmar lateral vein contracted with UK14304 indicating an increase in Akt activation. This is a further indication that PI 3‐kinase is involved in α2 adrenoceptor‐mediated vasoconstriction. Akt activation was inhibited by the Src tyrosine kinase inhibitor PP2, and removal of extracellular calcium.

UK14304 (10 μM) stimulated an increase in intracellular calcium in segments of palmar lateral vein. This was inhibited by removal of extracellular calcium, but not by nifedipine suggesting the rise in calcium is due to influx of calcium through non‐L type calcium channels. The increase in calcium was also inhibited by LY294002 indicating that PI 3‐kinase is upstream of calcium influx.

These data indicate that α2 adrenoceptor‐mediated vasoconstriction in the porcine palmar lateral vein is dependent upon stimulation of PI 3‐kinase, leading to an influx of calcium. This results in activation of the EGF receptor tyrosine kinase, and finally activation of ERK–MAP kinase.

British Journal of Pharmacology (2003) 138, 107–116. doi:10.1038/sj.bjp.0705014
Effector mechanism of magnolol‐induced apoptosis in human lung squamous carcinoma CH27 cells
Authors: Yang Shu‐Er , Hsieh Ming‐Tsuen , Tsai Tung‐Hu , Hsu Shih‐Lan
Published: January 2003

Magnolol, an active component isolated from the root and stem bark of Magnolia officinalis, has been reported to exhibit antitumour effects, but little is known about its molecular mechanisms of action.

Magnolol inhibited proliferation of human lung squamous carcinoma CH27 cells at low concentrations (10–40 μM), and induced apoptosis at high concentrations (80–100 μM).

Treatment with 80 μM magnolol significantly increased the expression of Bad and Bcl‐XS proteins, whereas it decreased the expression of Bcl‐XL. Overexpression of Bcl‐2 protected CH27 cells against magnolol‐triggered apoptosis.

Magnolol treatment resulted in accumulation of cytosolic cytochrome c and activation of caspase‐9 and downstream caspases (caspase‐3 and ‐6). Pretreatment with z‐VAD‐fmk markedly inhibited magnolol‐induced cell death, but did not prevent cytosolic cytochrome c accumulation.

Magnolol induced a modest and persistent JNK activation and ERK inactivation in CH27 cells without evident changes in the protein levels. The responsiveness of JNK and ERK to magnolol suggests the involvement of these kinases in the initiation of the apoptosis process.

These results indicate that regulation of the Bcl‐2 family, accumulation of cytosolic cytochrome c, and activation of caspase‐9 and caspase‐3 may be the effector mechanisms of magnolol‐induced apoptosis.

British Journal of Pharmacology (2003) 138, 193–201. doi:10.1038/sj.bjp.0705024
Pharmacological characterization of 5‐HT1B receptor‐mediated inhibition of local excitatory synaptic transmission in the CA1 region of rat hippocampus
Authors: Mlinar Boris , Falsini Chiara , Corradetti Renato
Published: January 2003

In the hippocampus, axon collaterals of CA1 pyramidal cells project locally onto neighbouring CA1 pyramidal cells and interneurones, forming a local excitatory network which, in disinhibited conditions, feeds polysynaptic epscs (poly‐epscs). 5‐hydroxytryptamine (5‐HT) has been shown to inhibit poly‐epscs through activation of a presynaptic receptor. The aim of the present work was the pharmacological characterization of the 5‐HT receptor involved in this 5‐HT action.

Poly‐epscs, evoked by electrical stimulation of the stratum radiatum and recorded in whole‐cell voltage‐clamp from CA1 pyramidal neurones, were studied in mini‐slices of the CA1 region under pharmacological block of GABAA, GABAB, and 5‐HT1A receptors.

The 5‐HT1B receptor selective agonist 1,4‐dihydro‐3‐(1,2,3,6‐tetrahydro‐4‐pyridinyl)‐5H‐pyrrolo[3,2‐b]pyridin‐5‐one dihydrochloride (CP 93129) inhibited poly‐epscs (EC50=55 nM), an effect mimicked by the 5‐HT1B ligands 5‐carboxamidotryptamine (5‐CT; EC50=14 nM) and methylergometrine (EC50=78 nM), but not by 1‐(3‐chlorophenyl)piperazine dihydrochloride (mCPP; 10 μM) or 7‐trifluoromethyl‐4(4‐methyl‐1‐piperazinyl)‐pyrrolo[1,2‐a]quinoxaline dimaleate (CGS 12066B; 10 μM).

The effects of CP 93129 and 5‐CT were blocked by the selective 5‐HT1B receptor antagonist 3‐[3‐(dimethylamino)propyl]‐4‐hydroxy‐N‐[4‐(4‐pyridinyl)phenyl]benzamide dihydrochloride (GR 55562; KB∼100 nM) and by cyanopindolol (KB=6 nM); methiothepin (10 μM) and dihydroergotamine (1 μM). For both GR 55562 and methiothepin, application times of at least two hours were required in order to achieve their full antagonistic effects.

Our results demonstrate that 5‐HT1B receptors are responsible for the presynaptic inhibition of neurotransmission at CA1/CA1 local excitatory synapses exerted by 5‐HT.

British Journal of Pharmacology (2003) 138, 71–80. doi:10.1038/sj.bjp.0705026
Comparison of signalling mechanisms involved in rat mesenteric microvessel contraction by noradrenaline and sphingosylphosphorylcholine
Authors: Altmann Christoph , Steenpaß Veronika , Czyborra Peter , Hein Peter , Michel Martin C
Published: January 2003

We have compared the signalling mechanisms involved in the pertussis toxin‐sensitive and ‐insensitive contraction of rat isolated mesenteric microvessels elicited by sphingosylphosphorylcholine (SPC) and noradrenaline (NA), respectively.

The phospholipase D inhibitor butan‐1‐ol (0.3%), the store‐operated Ca2+ channel inhibitor SK>F 96,365 (10 μM), the tyrosine kinase inhibitor genistein (10 μM), and the src inhibitor PP2 (10 μM) as well as the negative controls (0.3% butan‐2‐ol and 10 μM diadzein and PP3) had only little effect against either agonist.

Inhibitors of phosphatidylinositol‐3‐kinase (wortmannin and LY 294,002, 10 μM each) or of mitogen‐activated protein kinase kinase (PD 98,059 and U 126, 10 μM each) did not consistently attenuate NA‐ and SPC‐induced contraction as compared to their vehicles or negative controls (LY 303,511 or U 124).

The phospholipase C inhibitor U 73,122 (10 μM) markedly inhibited the SPC‐ and NA‐induced contraction (70% and 88% inhibition of the response to the highest NA and SPC concentration, respectively), whereas its negative control U 73,343 (10 μM) caused only less than 30% inhibition.

The rho‐kinase inhibitors Y 27,632 (10 μM) and fasudil (30 μM) caused a rightward‐shift of the NA concentration‐response curve by 0.7–0.8 log units and reduced the response to 10 μM SPC by 88% and 83%, respectively.

These data suggest that SPC and NA, while acting on different receptors coupling to different G‐protein classes, elicit contraction of rat mesenteric microvessels by similar signalling pathways including phospholipase C and rho‐kinase.

British Journal of Pharmacology (2003) 138, 261–271. doi:10.1038/sj.bjp.0705028
Tachykinin NK3 and NK1 receptor activation elicits secretion from porcine airway submucosal glands
Authors: Phillips Jonathan E , Hey John A , Corboz Michel R
Published: January 2003

We presently characterized the tachykinin receptor subtypes, using tachykinin receptor agonists and selective antagonists, that induce submucosal gland fluid flux (JG) from porcine tracheal explants with the hillocks technique. We also investigated the effects of the tachykinin receptor agonists on the electrophysiologic parameters of the tracheal epithelium in Ussing chambers.

The NK1 tachykinin receptor agonist substance P (SP, 1 μM) and the NK3 tachykinin receptor agonist [MePhe7]neurokinin B ([MePhe7]NKB, 1 μM) induced gland fluid fluxes of 0.29±0.03 μl min−1 cm−2 (n=26) and 0.36±0.05 μl min−1 cm−2 (n=24), respectively; while the NK2 tachykinin receptor agonist [βAla8]neurokinin A (4‐10) ([βAla8]NKA (4‐10), 1 μM) had no effect on JG (n=10).

The NK1 receptor antagonist CP99994 (1 μM, n=9) blocked 93% of the SP‐induced JG, whereas the NK3 receptor antagonist SB223412 (1 μM, n=12) had no effect on the SP‐induced JG. However, SB223412 (1 μM, n=9) blocked 89% of the [MePhe7]NKB‐induced JG while CP99994 (1 μM, n=10) did not affect the [MePhe7]NKB‐induced JG. The NK2 receptor antagonist SR48968 (1 μM) did not block the JG induced by either the NK1 (n=4) or NK3 (n=13) receptor agonists.

The nicotinic ganglionic acetylcholine receptor antagonist hexamethonium (1 μM) and the muscarinic acetylcholine receptor antagonist atropine (1 μM) also decreased the NK3 receptor agonist‐induced JG by 67% (n=10) and 71% (n=12), respectively.

The potential difference (PD), short‐circuit current (ISC), and membrane resistance (RM) of the porcine tracheal epithelial membranes were not significantly affected by any of the neurokinin agonists or antagonists (1 μM, basolateral) used in this study, although SP and [βAla8]NKA (4‐10) induced a slight transient epithelial hyperpolarization.

These data suggest that NK1 and NK3 receptors induce porcine airway gland secretion by different mechanisms and that the NK3 receptor agonists induced secretion is likely due to activation of prejunctional NK3 receptors on parasympathetic nerves, resulting in acetylcholine‐release. We conclude that tachykinin receptor antagonists may have therapeutic potential in diseases with pathophysiological mucus hypersecretion such as asthma and chronic bronchitis.

British Journal of Pharmacology (2003) 138, 254–260. doi:10.1038/sj.bjp.0705029
Monovalent cation (MC) current in cardiac and smooth muscle cells: regulation by intracellular Mg2+ and inhibition by polycations
Authors: Zakharov Sergey I , Smani Tarik , Leno Endri , Macianskiene Regina , Mubagwa Kanigula , Bolotina Victoria M
Published: January 2003

Previously we have described a monovalent cation (MC) current that could be unmasked by the removal of extracellular divalent cations in vascular smooth muscle cells (SMC) and cardiac myocytes, but specific and potent inhibitors of MC current have not been found, and the mechanism of its intracellular regulation remains obscure.

Here we show that small MC current is present in intact cells and could be dramatically up‐regulated during cell dialysis. MC current in dialyzed cells strongly resembled monovalent cation current attributed to Ca2+ release‐activated Ca2+‐selective (CRAC) channels, but its activation did not require depletion of Ca2+ stores, and was observed when the cells were dialyzed with, or without BAPTA.

Intracellular free Mg2+ inhibits MC current with Kd=250 μM.

Extracellular (but not intracellular) spermine effectively blocked MC current with Kd =3–10 μM, while store‐operated cations (SOC) channels and capacitative Ca2+ influx were not affected.

Spermine effectively inhibited MC current‐induced SMC depolarization, and prevented Ca2+ paradox‐induced vascular contracture.

Both, MC and SOC currents were inhibited by 2‐aminoethoxydiphenyl borate (2‐APB).

It is concluded that MC current could be regulated by intracellular Mg2+, and low concentrations of extracellular spermine could be used to discriminate it from SOC current, and to assess its role in cellular function.

British Journal of Pharmacology (2003) 138, 234–244. doi:10.1038/sj.bjp.0705074
On the optimization of Gaussian basis sets
Authors: Petersson George A. , Zhong Shijun , Montgomery John A. , Frisch Michael J.
Published: January 2003

A new procedure for the optimization of the exponents, αj, of Gaussian basis functions, Ylm(ϑ,φ)rle−αjr2, is proposed and evaluated. The direct optimization of the exponents is hindered by the very strong coupling between these nonlinear variational parameters. However, expansion of the logarithms of the exponents in the orthonormal Legendre polynomials, Pk, of the index, j: ln αj=∑k=0kmaxAkPk((2j−2)/(Nprim−1)−1), yields a new set of well-conditioned parameters, Ak, and a complete sequence of well-conditioned exponent optimizations proceeding from the even-tempered basis set (kmax=1) to a fully optimized basis set (kmax=Nprim−1). The error relative to the exact numerical self-consistent field limit for a six-term expansion is consistently no more than 25% larger than the error for the completely optimized basis set. Thus, there is no need to optimize more than six well-conditioned variational parameters, even for the largest sets of Gaussian primitives.
Surface-induced dissociations and reactions of acetonitrile monomer, dimer and trimer ions
Authors: Mair C. , Herman Z. , Fedor J. , Lezius M. , Märk T. D.
Published: January 2003

Dissociations and reactions induced by impact of acetonitrile monomer ions (CH3CN+, CD3CN+), dimer ions [(CH3CN)2+, (CD3CN)2+] and trimer ions [(CD3CN)3+] on a hydrocarbon-covered stainless-steel surface were investigated over the projectile energy range of 3–70 eV. Both simple dissociations of the projectile ion and chemical reactions of H-atom transfer from the surface material (followed by dissociations of the protonated projectile ion formed) were observed for the monomer ions. Results obtained for the dimer ions (CD3CN)2+ indicate the formation of the protonated acetonitrile ions via surface-induced reactions in two ways: (i) an intracluster ion–molecule reaction followed by dissociation to form CD3CND+, and (b) a hydrogen pick-up reaction from the surface material during the interaction of the dimer ion with the surface leading to CD3CNH+. A simple model based on the Brauman double-well potential—suggested earlier to explain the occurrence of analogous reactions in acetone cluster ion/surface interactions—accounts well for the formation of both product ions. Moreover, in adition to these protonated species, considerable amounts of nondissociated dimer ions were observed after acetonitrile dimer cation/surface collisions with energies up to 25 eV. Similarly, both trimer ions (up to 20 eV) and dimer ions (up to 30 eV) were observed in acetonitrile trimer cation/surface interactions. This indicates that unimolecular dissociation kinetics governs the product formation for these cluster ion/surface interactions.
Calculation of frequency-dependent polarizabilities using the approximate coupled-cluster triples model CC3
Authors: Hald Kasper , Pawłowski Filip , Jørgensen Poul , Hättig Christof
Published: January 2003

The calculation of frequency-dependent polarizabilities is discussed for the iterative approximate coupled-cluster singles, doubles and triples model CC3. A new implementation of the linear response functions is reported, which has the same computational O(N7) scaling as CC3 ground state calculations and uses an explicitly spin-coupled excitation space. Sample calculations are presented for the static and frequency-dependent polarizabilities of Ne and ethylene, as well as for the static polarizabilities of HF. The largest calculation employs the t-aug-cc-pVTZ basis set for ethylene giving a total of 328 basis functions. The results obtained agree well with the experimental data.
A mode-selective quantum chemical method for tracking molecular vibrations applied to functionalized carbon nanotubes
Authors: Reiher Markus , Neugebauer Johannes
Published: January 2003

The theoretical investigation of mesoscopic objects requires new techniques which are particularly suited for the study of selected aspects of these systems. Vibrational spectroscopy is a main source for structural information on heterogeneous systems. We present an efficient quantum chemical method, which relies on a modified Davidson algorithm for targeting selected vibrations in infrared and Raman spectra. This approach is applied to the characteristic breathing modes of single-walled carbon nanotubes.
Time-resolved photoelectron spectra as probe of excited state dynamics: A full quantum study of the Na2F cluster
Authors: Heitz Marie-Catherine , Durand Gérard , Spiegelman Fernand , Meier Christoph
Published: January 2003

The excited state dynamics of the Na2F cluster initiated by a femtosecond laser pulse is studied by quantum wave packet propagation within a pump–probe setup. The probe pulse is supposed to ionize the system to yield a photoelectron spectrum that depends on the time delay between the pump- and probe pulse. It is shown that the time dependence of the photoelectron spectrum is an extremely sensitive tool to study intramolecular motion of the cluster like the energy flow between different internal modes. The potential energy surfaces involved in the photoinduced process are calculated from a pseudopotential model with repulsive and Coulomb potentials for the ions and a quantum description of the excess electron via electron-Na+ and electron-F− pseudopotentials, polarization of the ionic cores as well as electron-ion correlation being added perturbatively. The nuclear motion upon laser excitation is described by full-dimensional quantum wave packet propagation using realistic laser pulse parameters. We find that the pump–probe signal is essentially dominated by the bending motion of the cluster with a periodicity of 180 fs. In addition, we also report detailed structures in the photoelectron spectrum which can be attributed to the excitation of the stretching mode. The possibility of experimental observation of the predicted dynamical behavior is discussed.
Detailed atomistic Monte Carlo simulation of grafted polymer melts: II. Orientational order and nuclear magnetic resonance spectra
Authors: Daoulas Kostas Ch. , Mavrantzas Vlasis G. , Photinos Demetri J.
Published: January 2003

We present results on the profiles of the first- and second-rank bond-order parameters, 〈P1(cos θ)〉 and 〈P2(cos θ)〉, of the grafted polymer melts simulated in atomistic detail in Part I of this work, with the end-bridging Monte Carlo (EBMC) algorithm. The 〈P1(cos θ)〉 and 〈P2(cos θ)〉 profiles are discussed in terms of bond distance from the grafting surface and bond coordinate along chain contour. A methodology is also presented for calculating the deuterium (2H) nuclear magnetic resonance (NMR) spectrum of the simulated grafted melts by analyzing the atomistic configurations accumulated in the course of the EBMC simulations. The calculation of the deuterium NMR spectrum is found to be very sensitive to the details of the profile of the second-rank bond-order parameter. For the systems simulated in the present work (melts of linear C78 and C156 polyethylene melts at grafting densities σ ranging from 1.31 to 2.62 nm−2), calculated H2 NMR splittings are on the order of a few kilohertz, in agreement with experimentally measured values through deuterium NMR spectroscopy.
Density fluctuation of a van der Waals fluid in supercritical state
Authors: Nishikawa Keiko , Kusano Kouhei , Ayusawa Arai Asako , Morita Takeshi
Published: January 2003

Density fluctuation is one of the fundamental parameters which determine the various physicochemical properties of supercritical fluids. When the contour map of density fluctuation is drawn on the phase diagram, there exists a ridge which separates the supercritical region in two. In order to obtain a phenomenological picture with physical clearness, we formulate the density fluctuation and its ridge for the van der Waals fluid. They are expressed by fairly simple equations with reduced temperature (Tr=T/Tc) and number density (nr=n/nc). It is analytically ensured that the law of corresponding states is applicable to the density fluctuation and its ridge and the ridge is different from the critical isochore. The ridge is the locus of the points where the third derivatives of the Gibbs free energy become zero, and that drawn on a density–temperature phase diagram directly connects with the locus of the inflection points of the van der Waals isotherms in the unstable region. From the viewpoint of the valance of volumes occupied by molecules and void, the physical meaning of the ridge is also discussed. The consistent agreements are confirmed in the characteristics of the density fluctuation and the ridge for the van der Waals fluid and several real supercritical fluids.
Broadband absorption and ab initio results on the CF C 2Σ+–X 2Π system
Authors: Luque Jorge , Hudson Eric A. , Booth Jean-Paul , Petsalakis Ioannis D.
Published: January 2003

Broadband absorption spectra and ab initio calculations are combined to complete and reinterpret part of the vacuum ultraviolet spectra of the CF radical. We have found a new band at 190.8 nm which we have assigned to the CF C 2Σ+–X 2Π (1,0) transition. Ab initio calculations show that the band at 186.6 nm formerly assigned as CF C′ 2Σ+–X 2Π (0,0) by White et al. [J. Mol. Spectrosc. 75, 318 (1979)] corresponds to the CF C 2Σ+–X 2Π (2,0) band. The CF C 2Σ+ state is heavily perturbed by the A 2Σ+ state and by repulsive Σ+2 states. The observed predissociation pattern for the C 2Σ+ (v′=0,1,2) states is well reproduced by the calculations. Information on the CF C 2Σ+–X 2Π and D 2Π–X 2Π electronic transition moments and corresponding oscillator band strengths is also presented.
Equation-of-motion coupled cluster method with full inclusion of the connected triple excitations for ionized states: IP-EOM-CCSDT
Authors: Musiał Monika , Kucharski Stanisław A. , Bartlett Rodney J.
Published: January 2003

The equation-of-motion (EOM) coupled cluster (CC) method with full inclusion of the connected triple excitations for ionization energies has been formulated and implemented. Using proper factorization of the three- and four-body parts of the effective Hamiltonian, an efficient computational procedure has been proposed for IP-EOM-CCSDT which at the EOM level requires no-higher-than nocc3nvir4 scaling. The method is calibrated by the evaluation of the valence vertical ionization potentials for CO, N2, and F2 molecules for several basis sets up to 160 basis functions. At the basis set limit, errors vary from 0.0 to 0.2 eV, compared to “experimental” vertical ionization potentials.
Method for the ab initio calculation of intermolecular potentials of ionic clusters: Test on Rg–CO+, Rg=He, Ne, Ar
Authors: Lotrich Victor F. , van der Avoird Ad
Published: January 2003

The interaction energy of a cationic complex A–B+ can be computed as the sum of the interaction energy of the neutral complex A–B and the geometry dependent difference in the ionization potentials of the complex A–B and the molecule B, with ionization potentials calculated by the outer valence Green’s function method. We test this method by computing the intermolecular potential energy of the complexes He–CO+, Ne–CO+, and Ar–CO+ for linear and T-shaped geometries. One-dimensional potential energy cuts were analyzed with emphasis on the asymptotic behavior. Results obtained by this method have been compared to interaction energies of the A–B+ complex computed directly by the partially spin-restricted single and double excitation coupled cluster method with perturbative triples. For the weakly bound complexes He–CO+ and Ne–CO+ the differences are only a few percent at small intermolecular distances but become significant for separations around the equilibrium distance and larger. Scaling the long range induction coefficients to match accurately known values significantly improves the agreement: the resulting interaction potentials are accurate to within a few percent at all intermolecular separations. For the Ar–CO+ complex the method produces less accurate results for small intermolecular distances but the binding in Ar–CO+ is very strong and for small R this system cannot be considered a weakly bound complex anymore.