bluuebunny/crossref_metadata_2025 huggingface dataset:
Vasotocin and vasopressin stimulation of the chloride secretion in the human bronchial epithelial cell line, 16HBE14o‐
Authors: Bernard Karen , Bogliolo Stéphanie , Ehrenfeld Jordi
Published: February 2005

Effects of neuropeptides of the vasopressin family on Cl− secretion have not yet been reported in lung. Using the 16HBE14o‐ bronchial epithelial cell line, we investigated their action on Cl− secretion.

In symmetrical Cl− solutions, basolateral application of arginine vasotocin (AVT), oxytocin or isotocin induced a transient Isc stimulation (Ipeak), whereas arginine vasopressin (AVP) did not. The effects of different Cl− channel blockers and of a protein kinase C (PKC) inhibitor suggest that CFTR is involved in Ipeak. The calcium‐activated K+ channel (SK4) and the Cl−/HCO−3 exchanger favor the driving force for AVT‐mediated Cl− secretion. The antagonists of V1a (SR49059)‐ and V1b (SSR149415)‐receptors blocked Ipeak, while SR121463B, a V2 receptor antagonist, did not. These results point to the stimulation of a V1‐like receptor mediating Ipeak and presenting an efficacy order, AVT>oxytocin>isotocin≫AVP.

When a serosal to mucosal Cl− gradient was applied, AVT and AVP both stimulated Isc according to a biphasic profile, Ipeak being followed by a plateau phase (Iplateau). The pharmacology of Iplateau suggests that CFTR channels are involved and that Na+/K+/2Cl− is the only transporter associated with Iplateau. dDAVP, a V2 receptor agonist‐induced Iplateau with the same potency as AVP, suggesting the involvement of V2 receptors in the AVP‐induced Iplateau. V2 receptors are present on both opposite membranes, while V1‐like receptors are mainly expressed on the basolateral membranes. RT–PCR experiments show the expression of V1a, V1b, V2 and vasopressin‐activated calcium‐mobilizing (VACM) receptors mRNAs.

British Journal of Pharmacology (2005) 144, 1037–1050. doi:10.1038/sj.bjp.0706103
A potential role for extracellular nitric oxide generation in cGMP‐independent inhibition of human platelet aggregation: biochemical and pharmacological considerations
Authors: Crane Michael S , Rossi Adriano G , Megson Ian L
Published: February 2005

Nitric oxide (NO) is a potent inhibitor of platelet activation, that inhibits the agonist‐induced increase in cytosolic Ca2+ concentration through both cGMP‐dependent and independent pathways. However, the NO‐related (NOx) species responsible for cGMP‐independent signalling in platelets is unclear. We tested the hypothesis that extracellular NO, but not NO+ or peroxynitrite, generated in the extracellular compartment is responsible for cGMP‐independent inhibition of platelet activation via inhibition of Ca2+ signalling.

Concentration–response curves for diethylamine diazeniumdiolate (DEA/NO; a spontaneous NO generator), S‐nitroso‐N‐valerylpenicillamine (SNVP; an S‐nitrosothiol) and 3‐morpholinosydnonomine (SIN‐1; a peroxynitrite generator) were generated in platelet‐rich plasma (PRP) and washed platelets (WP) in the presence and absence of a supramaximal concentration of the soluble guanylate cyclase inhibitor, ODQ (20 μM). All three NOx donors displayed cGMP‐independent inhibition of platelet aggregation in PRP, but only DEA/NO exhibited cGMP‐independent inhibition of aggregation in WP.

Analysis of NO generation using an isolated NO‐electrode revealed that cGMP‐independent effects coincided with the generation of substantial levels of extracellular NO (>40 nM) from the NOx donors.

Reconstitution of WP with plasma factors indicated that the copper‐containing plasma protein, caeruloplasmin (CP), catalysed the release of NO from SNVP, while Cu/Zn superoxide dismutase (SOD) unmasked NO generated from SIN‐1. The increased generation of extracellular NO correlated with a switch to cGMP‐independent effects with both NOx donors.

Analysis of Fura‐2 loaded WP revealed that only DEA/NO inhibited Ca2+ signalling in platelets via a cGMP‐independent mechanism. However, preincubation of SNVP and SIN‐1 with CP and SOD, respectively, induced cGMP‐independent inhibition of intraplatelet Ca2+ trafficking by the NOx donors.

Taken together, our data suggest that extracellular NO (>40 nM) is required for cGMP‐independent inhibition of platelet activation. Plasma constituents may play an important pharmacological role in activating cGMP‐independent signalling by S‐nitrosothiols or peroxynitrite generators.

British Journal of Pharmacology (2005) 144, 849–859. doi:10.1038/sj.bjp.0706110
Histamine receptors that influence blockage of the normal human nasal airway
Authors: Taylor‐Clark Thomas , Sodha Reena , Warner Ben , Foreman John
Published: February 2005

The aim of this study was to investigate the mechanisms by which histamine causes nasal blockage. Histamine, 40–800 μg, intranasally into each nostril, induced significant blockage of the nasal airway in normal human subjects, as measured by acoustic rhinometry.

Oral pretreatment with cetirizine, 5–30 mg, the H1 antagonist, failed to reverse completely the nasal blockage induced by histamine, 400 μg.

Dimaprit, 50–200 μg, the H2 agonist, intranasally, caused nasal blockage, which was reversed by oral pretreatment with ranitidine, 75 mg, the H2 antagonist.

A combination of cetirizine, 20 mg, and ranitidine, 75 mg, caused greater inhibition of the nasal blockage caused by histamine, 400 μg, than cetirizine alone. In the presence of both antagonists, there was residual histamine‐induced nasal blockage.

R‐α‐methylhistamine (R‐α‐MeH), 100–600 μg, the H3 agonist, intranasally, caused nasal blockage, which was not inhibited by either cetirizine or ranitidine.

Thioperamide, 700 μg, the H3 antagonist, intranasally, reversed the R‐α‐MeH‐induced nasal blockage. Thioperamide alone had no significant action on the nasal blockage induced by histamine, 400 and 1000 μg, but, in the presence of cetirizine, 20 mg, thioperamide further reduced the histamine‐induced nasal blockage.

Corynanthine, 2 mg, the α1‐adrenoceptor antagonist, administered intranasally, caused nasal blockage.

Corynanthine produced a greater increase in nasal blockage when in combination with bradykinin compared to its combination with R‐α‐MeH.

There appears to be a contribution of H1, H2 and H3 receptors to histamine‐induced nasal blockage in normal human subjects. The sympathetic nervous system actively maintains nasal patency and we suggest that activation of nasal H3 receptors may downregulate sympathetic activity.

British Journal of Pharmacology (2005) 144, 867–874. doi:10.1038/sj.bjp.0706118
Increased PKA activity and its influence on isoprenaline‐stimulated L‐type Ca2+ channels in the heart from ovariectomized rats
Authors: Kam Kenneth W L , Kravtsov Gennadi M , Liu Jing , Wong Tak Ming
Published: February 2005

We previously showed that oestrogen confers cardioprotection by downregulating the cardiac β1‐adrenoceptor (β1‐AR). The present study examined the effect of oestrogen on the post β1‐AR signalling cascade, with particular emphasis on the activity of protein kinase A (PKA) and its influence on the L‐type Ca2+ channel.

Three groups of adult female Sprague–Dawley rats were used: sham‐operated controls, bilaterally ovariectomized (Ovx) rats, and Ovx rats with oestrogen replacement (Ovx+E2), which restored the oestrogen concentration to normal.

The electrically induced intracellular Ca2+ transient (E[Ca2+]i), 45Ca2+‐uptake through cardiac L‐type Ca2+ channels (Ca2+ channels), heart rate and force of contraction in response to β‐AR stimulation with 10 nM isoprenaline (Iso) in hearts from Ovx rats were significantly greater than those of control and Ovx+E2 rats. The basal and Iso‐induced PKA activities were also higher in hearts from Ovx rats. KT5720, a selective PKA inhibitor, completely inhibited its potentiating effect on basal Ca2+ channel activity in the Ovx rat heart. On the other hand, expression of G proteins (Gαs and Gαi1−3), basal and forskolin‐stimulated cAMP accumulation, and responsiveness of PKA to cAMP, were not altered by Ovx.

Interestingly, the PKA inhibitor at the same concentration significantly reduced the increases in PKA activity and Ca2+ channel activity upon β‐AR stimulation in all three groups of rats and the inhibitions were significantly greater in the Ovx rat than in the other two groups of rats.

This study provides the first evidence that, in addition to downregulation of β1‐AR shown previously, suppression of PKA activity, which is partly responsible for the suppressed Ca2+ channel activity, also determines the E[Ca2+]i and cardiac contractility following β‐AR stimulation in the female rat.

British Journal of Pharmacology (2005) 144, 972–981. doi:10.1038/sj.bjp.0706123
Pharmacological characterisation of the adenosine receptor mediating increased ion transport in the mouse isolated trachea and the effect of allergen challenge
Authors: Kornerup Kristin N , Page Clive P , Moffatt James D
Published: February 2005

The effect of adenosine on transepithelial ion transport was investigated in isolated preparations of murine trachea mounted in Ussing chambers. The possible regulation of adenosine receptors in an established model of allergic airway inflammation was also investigated.

Mucosally applied adenosine caused increases in short‐circuit current (ISC) that corresponded to approximately 50% of the response to the most efficacious secretogogue, ATP (ΔISC 69.5±6.7 μA cm2). In contrast, submucosally applied adenosine caused only small (<20%) increases in ISC, which were not investigated further.

The A1‐selective (N6‐cyclopentyladenosine, CPA, 1 nM–10 μM), A2A‐selective (2‐p‐(2‐carboxyethyl)phenethylamino‐5′‐N‐ethylcarboxoamido adenosine; CGS 21680; 0.1–100 μM) and A3‐selective (1‐deoxy‐1‐[6‐[[(3‐iodophenyl)‐methyl]amino]‐9H‐purin‐9‐yl]‐N‐methyl‐β‐D‐ribofuranuronamide; IB‐MECA; 30 nM–100 μM) adenosine receptor agonists were either equipotent or less potent than adenosine, suggesting that these receptors do not mediate the response to adenosine.

The A1 receptor selective antagonist 8‐cyclopentyl‐1,3‐dipropylxanthine (DPCPX; 10 nM–1 μM) caused a rightward shift of the adenosine concentration–effect curve only at 1 μM. The mixed A2A/A2B receptor antagonist 4‐(2‐[7‐amino‐2‐(2‐furyl)[1,2,4]triazolo[2,3‐a][1,3,5]triazin‐5‐ylamino]ethyl)phenol (ZM 241385) also caused rightward shift of the adenosine concentration–effect curve, again only at micromolar concentrations, suggestive of the involvement of A2B receptors.

In preparations from animals sensitised to ovalbumin and challenged over 3 days with aerosol ovalbumin, a decrease in baseline ISC was observed and responses to ATP were diminished. Similarly, the amplitude of responses to adenosine were attenuated although there was no change in potency.

These results suggest that the A2B receptor mediates the ISC response to adenosine in the mouse trachea. This receptor does not appear to be regulated in a standard asthma model.

British Journal of Pharmacology (2005) 144, 1011–1016. doi:10.1038/sj.bjp.0706133
Antihyperalgesic activity of a novel nonpeptide bradykinin B1 receptor antagonist in transgenic mice expressing the human B1 receptor
Authors: Fox Alyson , Kaur Satbir , Li Bifang , Panesar Moh , Saha Uma , Davis Clare , Dragoni Ilaria , Colley Sian , Ritchie Tim , Bevan Stuart , Burgess Gillian , McIntyre Peter
Published: February 2005

We describe the properties of a novel nonpeptide kinin B1 receptor antagonist, NVP‐SAA164, and demonstrate its in vivo activity in models of inflammatory pain in transgenic mice expressing the human B1 receptor.

NVP‐SAA164 showed high affinity for the human B1 receptor expressed in HEK293 cells (Ki 8 nM), and inhibited increases in intracellular calcium induced by desArg10kallidin (desArg10KD) (IC50 33 nM). While a similar high affinity was observed in monkey fibroblasts (Ki 7.7 nM), NVP‐SAA164 showed no affinity for the rat B1 receptor expressed in Cos‐7 cells.

In transgenic mice in which the native B1 receptor was deleted and the gene encoding the human B1 receptor was inserted (hB1 knockin, hB1‐KI), hB1 receptor mRNA was induced in tissues following LPS treatment. No mRNA encoding the mouse or human B1 receptor was detected in mouse B1 receptor knockout (mB1‐KO) mice following LPS treatment.

Freund's complete adjuvant‐induced mechanical hyperalgesia was similar in wild‐type and hB1‐KI mice, but was significantly reduced in mB1‐KO animals. Mechanical hyperalgesia induced by injection of the B1 agonist desArg10KD into the contralateral paw 24 h following FCA injection was similar in wild‐type and hB1‐KI mice, but was absent in mB1‐KO animals.

Oral administration of NVP‐SAA164 produced a dose‐related reversal of FCA‐induced mechanical hyperalgesia and desArg10KD‐induced hyperalgesia in hB1‐KI mice, but was inactive against inflammatory pain in wild‐type mice.

These data demonstrate the use of transgenic technology to investigate the in vivo efficacy of species selective agents and show that NVP‐SAA164 is a novel orally active B1 receptor antagonist, providing further support for the utility of B1 receptor antagonists in inflammatory pain conditions in man.

British Journal of Pharmacology (2005) 144, 889–899. doi:10.1038/sj.bjp.0706139
Paramagnetic effect of magnetic field on superconductors with charge-density waves
Authors: Ekino T. , Gabovich A. M. , Voitenko A. I.
Published: February 2005

The limiting external magnetic field Hp that destroys paramagnetically the ordered state of spin-singlet superconductors with charge density waves (CDWs) with coexisting superconducting and dielectric order parameters is calculated self-consistently. It is shown that Hp always exceeds the Pauli limits for both pure superconducting and pure CDW phases. Relevant experimental data for inorganic and organic superconductors with high upper critical magnetic fields are analyzed and are shown to be in qualitative agreement with the proposed theory.
On the Regulatory Choice of Refunding Rules to Reconcile the ‘Polluter Pays Principle’ and Pigovian Taxation: An Application
Authors: Kampas Athanasios , Franckx Laurent
Published: February 2005

The ‘polluter pays principle’ (PPP) is one of the four principles that govern the European Union's environmental policy. Although PPP justifies Pigovian taxation as a legitimate policy means to internalise externalities, there is a potential contradiction between PPP and Pigovian taxation depending upon the definition of pollution control costs. We summarise this debate and focus on the lump-sum refunding of tax revenues in order to reconcile the PPP and Pigovian taxation. We propose equity as the guiding principle to select among various refunding schemes, and empirically examine a specific application.
A Regional Perspective on the Impact of the Privatisation of the UK Public Industrial Property Stock
Authors: Jones Colin
Published: February 2005

There has been a long tradition, dating back to the 1930s, of promoting regional development in the assisted areas of the United Kingdom through the provision of industrial units. At the end of the 1980s the government decided that the time was then ripe to sell off the publicly owned portfolio of industrial and commercial property, which was predominantly to be found in the peripheral regions of the United Kingdom. The author charts the privatisation process in England and Scotland. It had been envisaged that the sale would lead to higher rents and invigorate private sector investment. More than a decade on, the author seeks to assess whether this forecast/hypothesis proved correct. The Scottish experience is used as a case study of the UK privatisation programme operating in a peripheral region, and the impact is assessed at two levels: on the Scottish market as a whole; and in the postprivatisation experience of the former publicly owned industrial estates. The original forecasts of the Conservative government prove to be naïve. No evidence of a wide-scale rise in rents, or speculative development, was found, nor has there been an increase in institutional investment in industrial property; the public sector has begun to intervene again—albeit in a different guise.
Fiscal Decentralisation, the Size of the Public Sector, and Economic Growth in Turkey
Authors: Sagbas Isa , Sen Huseyin , Kar Muhsin
Published: February 2005

The aim of this study is to examine the impact of fiscal decentralisation on the size of the public sector and economic growth in Turkey. An empirical test of the Leviathan hypothesis by using recently developed econometrical tools shows that fiscal decentralisation does not curb the growth of central government. The finding is not compatible with explanations of the efficiency benefits of greater decentralisation. An investigation of the impacts of fiscal decentralisation on economic growth by utilising time series in a framework of the production function for the period 1982–2000 and cross-section analyses on sixty-seven provinces indicates that there is a negative relationship between fiscal decentralisation and economic growth.
Devolution—The Northern Ireland Way: An Exercise in ‘Creative Ambiguity’
Authors: Knox Colin , Carmichael Paul
Published: February 2005

Devolution in Northern Ireland followed directly from the 1998 Belfast (Good Friday) Agreement which provided, inter alia, for a democratically elected Assembly “inclusive in its membership, capable of exercising executive and legislative authority, and subject to safeguards to protect the rights and interests of all sides of the community”. More than six years on, the Northern Ireland Executive and Assembly are in suspension for the fourth time (the latest since October 2002). The conjunction of devolution and the implementation of the Agreement mean that the former is wholly dependent on the vagaries of the latter and, as a consequence, has devalued the potential of devolution to improve the governance of Northern Ireland.
Equalisation of Municipal Input Costs in England: Matters of Principle and Practice
Authors: Bailey Stephen J
Published: February 2005

The considerable academic literature on the assessment of municipal expenditure needs has generally paid much less attention to compensation for relatively high input costs. This is all the more surprising given that regional variations in input costs are a major cause of differences in municipalities' per capita expenditure needs. This paper considers the recent review and reform of the way in which account is taken of variations between English municipalities in the costs of their inputs. It discusses the arguments for and against equalisation of input costs and the advantages and disadvantages of the various possible ways in which to compensate municipalities for those input-cost differentials. Notwithstanding the recent reform, there remain a number of fundamental criticisms.
Annual clovers (Trifolium spp.) have different reproductive strategies to achieve persistence in Mediterranean-type climates
Authors: Norman Hayley C. , Cocks Philip S. , Galwey Nick W.
Published: February 2005

The aim of this work was to determine whether different species of annual clover (Trifolium spp.), obtained from the same environment, have different reproductive strategies (combinations of reproductive traits) to achieve ecological success. A better understanding of the traits that improve persistence should allow agronomists to narrow the selection criteria for new clover cultivars for ley-farming systems in southern Australia. Seeds of 18 annual clover species were obtained from 3 Australian and 6 Mediterranean sites and were subsequently grown in a common garden in Western Australia. Reproductive traits, including time of flowering, weight per seed, fecundity, pollen to ovule ratio, and pattern of seed softening, were observed.
Accessions of different clover species from the same site of collection had different reproductive strategies. Across a range of collection sites, accessions of the same species demonstrated the same broad reproductive strategy; however, some traits, e.g. the timing of flowering, varied within species across collection sites. Principal component analysis suggested that there are 3 broad reproductive strategies demonstrated by these clover species. At one extreme were the relatively large-seeded clovers (T. subterraneum, T. clypeatum, and T. stellatum). The associated cost of these large seeds is reduced fecundity. The large-seeded clovers do not have high long-term hardseededness (the predominant form of seed dormancy in clovers). The relatively small-seeded clovers were all characterised by high fecundity. Many of the small-seeded clovers have high levels of long-term hardseededness, which allow the risk of failure to be spread across seasons (T. spumosum, T. hirtum, T. lappaceum, T. angustifolium, and T. tomentosum). Some of the small-seeded clovers (T. glomeratum, T. nigrescens, T. campestre, T. cernuum, and T. suffocatum) are generalists, producing as many seeds as possible in each season, with very little hardseededness.
There are several possible explanations for the apparent success of such different reproductive strategies among clover accessions of different species at the same site. A plant may achieve the same goal by trading one reproductive trait for another. For example, it may either produce many small seeds to spread the risk of failure or produce fewer large seeds with an inherent competitive advantage. Alternatively, temporal and spatial variation may favour clovers with a number of different reproductive strategies. It is likely that a mixture of species with different reproductive strategies will maximise production and persistence of legume-based pastures in ley-farming systems.
Genetic analysis of embryo, cytoplasmic, and maternal effects and their environment interactions for protein content in Brassica napus L.
Authors: Wu J. G. , Shi C. H. , Zhang H. Z.
Published: February 2005

A genetic model for quantitative traits of seeds in diploid plants was applied to estimate the genetic main effects and genotype × environment (GE) interaction effects for protein content (PC) of rapeseed (Brassica napus L.) by using 2 years of experimental data with a diallel mating design of 8 parents. Results showed that PC of rapeseed was simultaneously controlled by genetic effects of embryo, cytoplasm, and maternal plant, of which the maternal genetic effects were most important, followed by embryo and cytoplasmic genetic effects. Therefore, improvement of PC of rapeseed would be more efficient when selection is based on maternal plants than that on single seeds. Since the GE interaction effects accounted for about 60.10% of total genetic effect, they were more important than the genetic main effects, and selection for PC might be influenced by environmental conditions. The total narrow-sense heritability for PC was 64.17%, of which the interaction heritability was larger than the general heritability. Selection for improving PC can therefore be conducted in early generations. Maternal heritability (41.59%) was most important for PC, followed by cytoplasmic heritability (17.62%) and then by embryo heritability (5.25%). Based on prediction of genetic effects, parent Youcai 601 was better than others for increasing PC in rapeseed breeding.
Modelling the effects of row configuration on sorghum yield reliability in north-eastern Australia
Authors: Whish Jeremy , Butler Giles , Castor Michael , Cawthray Shayne , Broad Ian , Carberry Peter , Hammer Graeme , McLean Greg , Routley Richard , Yeates Steven
Published: February 2005

In recent years, many sorghum producers in the more marginal (<600 mm annual rainfall) cropping areas of Queensland and northern New South Wales have used skip row configurations in an attempt to improve yield reliability and reduce sorghum production risk. This paper describes modifications made to the APSIM sorghum module to account for the difference in water usage and light interception between alternative crop planting configurations, and then demonstrates how this new model can be used to quantify the long-term benefits of skip sorghum production. Detailed measurements of light interception and water extraction from sorghum crops grown in solid, single and double skip row configurations were collected from on-farm experiments in southern Qld and northern NSW. These measurements underpinned changes to the APSIM-Sorghum model so that it accounted for the elliptical water uptake pattern below the crop row and the reduced total light interception associated with skip row configurations. Long-term simulation runs using long-term weather files for locations near the experimental sites were used to determine the value of skip row sorghum production as a means of maintaining yield reliability. These simulations showed a trade-off between long-term average production (profitability) and annual yield reliability (risk of failure this year). Over the long term, the production of sorghum in a solid configuration produced a higher average yield compared with sorghum produced in a skip configuration. This difference in average yield is a result of the solid configuration having a higher yield potential compared with the skip configurations. Skip configurations limit the yield potential as a safeguard against crop failure. To achieve the higher average yield in the solid configuration the producer suffers some total failures. Skip configurations reduce the chance of total failure by capping the yield potential, which in turn reduces the long-term average yield. The decision on what row configuration to use should be made tactically and requires consideration of the starting soil water, the soil’s plant-available water capacity (PAWC), and the farm family’s current attitude to risk.
Phosphorus export at the paddock, farm-section, and whole farm scale on an irrigated dairy farm in south-eastern Australia
Authors: Barlow K. , Nash D. , Grayson R. B.
Published: February 2005

Phosphorus (P) exported from agricultural land contributes to the eutrophication of inland water systems. Although P export has been extensively researched at the paddock scale, our understanding of farm-scale export is limited. This paper presents the results of a 3-year monitoring project that investigated P export at the paddock, farm-section, and whole farm scales on an irrigated dairy farm in south-eastern Australia. Annual average concentrations of 2.2–11 mg P/L, and annual loads of 2.5–23 kg P/ha were measured at the paddock and farm-section scale over the 3 years, with the quality of irrigation water applied having no significant effect on P export in surface runoff. At the farm scale, effective management of the water reuse system significantly reduced phosphorus export by up to 98%. During the 3-year period, P concentrations and loads exported in surface runoff consistently decreased between the paddock and farm-section scales (e.g. P-28 exported 13.8 kg P/ha, whereas S-4 exported 6.7 kg/ha in 2001), with the decrease in P export described using a scaling factor. Our results suggest that data on paddock-scale P export can rarely be proportionally assigned to predict section- or farm-scale export, at least on irrigated dairy farms in south-eastern Australia.
Neutral microepidemic evolution of bacterial pathogens
Authors: Fraser Christophe , Hanage William P. , Spratt Brian G.
Published: February 2005

Understanding bacterial population genetics is vital for interpreting the response of bacterial populations to selection pressures such as antibiotic treatment or vaccines targeted at only a subset of strains. The evolution of transmissible bacteria occurs by mutation and localized recombination and is influenced by epidemiological as well as molecular processes. We demonstrate that the observed population genetic structure of three important human pathogens,
Streptococcus pneumoniae
,
Neisseria meningitidis
, and
Staphylococcus aureus
, can be explained by using a simple evolutionary model that is based on neutral mutational drift, modulated by recombination, and which incorporates the impact of epidemic transmission in local populations. The predictions of this neutral “microepidemic” model are found to closely fit observed genetic relatedness distributions of bacteria sampled from their natural population, and it provides estimates of the relative rate of recombination that agree well with empirical estimates. The analysis suggests the emergence of neutral bacterial population structure from overlapping microepidemics within clustered host populations and provides insight into the nature and size distribution of these clusters. These findings challenge the assumption that strains of bacterial pathogens differ markedly in relative fitness.
Reconstitution of intramembrane proteolysis
in vitro
reveals that pure rhomboid is sufficient for catalysis and specificity
Authors: Urban Sinisa , Wolfe Michael S.
Published: February 2005

Intramembrane proteolysis is a new paradigm in biology that controls signaling events throughout evolution. Hydrolysis of peptide bonds is thought to occur within the normally hydrophobic membrane environment, but insights into this unusual activity have been lacking because of difficulty in recapitulating activity
in vitro
. We have reconstituted intramembrane proteolysis with a pure recombinant substrate and rhomboid proteins in both detergent micelles and artificial membrane environments. Rhomboid proteins from diverse organisms including two model bacteria, a pathogen, an extremophile, and an animal were robustly active in pure form, proving that rhomboids are a new class of enzymes and do not require cofactors to catalyze intramembrane proteolysis. Rhomboid proteins directly recognized their substrates
in vitro
by the top of the substrate transmembrane domain, displaying specificity apparently reciprocal to that of γ-secretase, the only other activity known to cleave type-I transmembrane domains. Rhomboid proteases represent a different evolutionary path to a serine protease mechanism and exhibited an inhibitor profile unlike other serine proteases. Intriguingly, activity was dramatically modulated by different membrane phospholipid environments, suggesting a mechanism for regulating these proteases. This analysis promises to help reveal the biochemical mechanisms and biological roles of this most widely conserved membrane protein family.
Fluid-flow-induced flutter of a flag
Authors: Argentina Médéric , Mahadevan L.
Published: February 2005

We give an explanation for the onset of fluid-flow-induced flutter in a flag. Our theory accounts for the various physical mechanisms at work: the finite length and the small but finite bending stiffness of the flag, the unsteadiness of the flow, the added mass effect, and vortex shedding from the trailing edge. Our analysis allows us to predict a critical speed for the onset of flapping as well as the frequency of flapping. We find that in a particular limit corresponding to a low-density fluid flowing over a soft high-density flag, the flapping instability is akin to a resonance between the mode of oscillation of a rigid pivoted airfoil in a flow and a hinged-free elastic plate vibrating in its lowest mode.
Computational insights into
Caenorhabditis elegans
vulval development
Authors: Fisher Jasmin , Piterman Nir , Hubbard E. Jane Albert , Stern Michael J. , Harel David
Published: February 2005

Studies of
Caenorhabditis elegans
vulval development provide a paradigm for pattern formation during animal development. The fates of the six vulval precursor cells are specified by the combined action of an inductive signal that activates the EGF receptor mitogen-activated PK signaling pathway (specifying a primary fate) and a lateral signal mediated by LIN-12/Notch (specifying a secondary fate). Here we use methods devised for the engineering of complex reactive systems to model a biological system. We have chosen the visual formalism of statecharts and use it to formalize Sternberg and Horvitz's 1989 model [Sternberg, P. W. & Horvitz, H. R. (1989)
Cell
58, 679–693], which forms the basis for our current understanding of the interaction between these two signaling pathways. The construction and execution of our model suggest that different levels of the inductive signal induce a temporally graded response of the EGF receptor mitogen-activated PK pathway and make explicit the importance of this temporal response. Our model also suggests the existence of an additional mechanism operating during lateral specification that prohibits neighboring vulval precursor cells from assuming the primary fate.
Attenuation of tobacco smoke-induced lung inflammation by treatment with a soluble epoxide hydrolase inhibitor
Authors: Smith Kevin R. , Pinkerton Kent E. , Watanabe Takaho , Pedersen Theresa L. , Ma Seung Jin , Hammock Bruce D.
Published: February 2005

Changes in the lungs due to smoking include inflammation, epithelial damage, and remodeling of the airways. Airway inflammation is likely to play a critical role in the genesis and progression of tobacco smoke-induced airway disease. Soluble epoxide hydrolase (sEH) is involved in the metabolism of endogenous chemical mediators that play an important role in inflammation. Epoxyeicosatrienoic acids (EETs) have demonstrated antiinflammatory properties, and hydrolysis of these epoxides by sEH is known to diminish this activity. To examine whether acute tobacco smoke-induced inflammation could be reduced by a sEH inhibitor, 12-(3-adamantane-1-yl-ureido)-dodecanoic acidn-butyl ester was given by daily s.c. injection to spontaneously hypertensive rats exposed to filtered air or tobacco smoke for a period of 3 days (6 h/day). Acute exposure to tobacco smoke significantly increased by 3.2-fold (P< 0.05) the number of cells recovered by bronchoalveolar lavage. The sEH inhibitor significantly decreased total bronchoalveolar lavage cell number by 37% in tobacco smoke-exposed rats with significant reductions noted in neutrophils, alveolar macrophages, and lymphocytes. A combination of sEH inhibitor and EETs was more significant in its ability to further reduce tobacco smoke-induced inflammation compared with the sEH inhibitor alone. The sEH inhibitor led to a shift in some plasma epoxides and diols that are consistent with the hypothetical action of these compounds. We conclude that an sEH inhibitor, in the presence or absence of EETs, can attenuate, in part, inflammation associated with acute exposure to tobacco smoke.
A monkey's tale: The origin of
Plasmodium vivax
as a human malaria parasite
Authors: Escalante Ananias A. , Cornejo Omar E. , Freeland Denise E. , Poe Amanda C. , Durrego Ester , Collins William E. , Lal Altaf A.
Published: February 2005

The high prevalence of Duffy negativity (lack of the Duffy blood group antigen) among human populations in sub-Saharan Africa has been used to argue that
Plasmodium vivax
originated on that continent. Here, we investigate the phylogenetic relationships among 10 species of
Plasmodium
that infect primates by using three genes, two nuclear (β-tubulin and cell division cycle 2) and a gene from the plastid genome (the elongation factor Tu). We find compelling evidence that
P. vivax
is derived from a species that inhabited macaques in Southeast Asia. Specifically, those phylogenies that include
P. vivax
as an ancient lineage from which all of the macaque parasites could originate are significantly less likely to explain the data. We estimate the time to the most recent common ancestor at four neutral gene loci from Asian and South American isolates (a minimum sample of seven isolates per locus). Our analysis estimates that the extant populations of
P. vivax
originated between 45,680 and 81,607 years ago. The phylogeny and the estimated time frame for the origination of current
P. vivax
populations are consistent with an “out of Asia” origin for
P. vivax
as hominoid parasite. The current debate regarding how the Duffy negative trait became fixed in Africa needs to be revisited, taking into account not only human genetic data but also the genetic diversity observed in the extant
P. vivax
populations and the phylogeny of the genus
Plasmodium
.
Liver receptor homolog 1 contributes to intestinal tumor formation through effects on cell cycle and inflammation
Authors: Schoonjans Kristina , Dubuquoy Laurent , Mebis Joseph , Fayard Elisabeth , Wendling Olivia , Haby Céline , Geboes Karel , Auwerx Johan
Published: February 2005

Liver receptor homolog 1 (LRH-1) is an orphan nuclear receptor that synergizes with β-catenin/T cell factor 4 signaling to stimulate intestinal crypt cell renewal. We evaluated here the impact of haploinsufficiency of LRH-1 on intestinal tumorigenesis by using two independent mouse models of human colon tumorigenesis. Haploinsufficiency of LRH-1 blunts intestinal tumorigenesis in the

Apc
Min/

+
mice, a genetic model of intestinal cancer. Likewise,
Lrh-1

+
/
–

mice are protected against the formation of aberrant crypt foci in the colon of mice exposed to the carcinogen azoxymethane. LRH-1 gene expression is reduced in tumors that express elevated levels of the proinflammatory cytokine TNF-α. Reciprocally, decreased LRH-1 expression in
Lrh-1

+
/
–

mice attenuates TNF-α expression. Compared with normal human colon, expression and subcellular localization of LRH-1 is significantly altered in neoplastic colon. In combination, these data suggest a role of LRH-1 in the initiation of intestinal tumorigenesis both by affecting cell cycle control as well as through its impact on inflammatory pathways.
Association of the
NuMA
region on chromosome 11q13 with breast cancer susceptibility
Authors: Kammerer Stefan , Roth Richard B. , Hoyal Carolyn R. , Reneland Richard , Marnellos George , Kiechle Marion , Schwarz-Boeger Ulrike , Griffiths Lyn R. , Ebner Florian , Rehbock Joachim , Cantor Charles R. , Nelson Matthew R. , Braun Andreas
Published: February 2005

The development of breast cancer is a complex process that involves multiple genes at many stages, from initial cell cycle dysregulation to disease progression. To identify genetic variations that influence this process, we conducted a large-scale association study using a collection of German cases and controls and >25,000 SNPs located within 16,000 genes. One of the loci identified was located on chromosome 11q13 [odds ratio (OR) = 1.85,
P
= 0.017]. The initial association was subsequently tested in two independent breast cancer collections. In both sample sets, the frequency of the susceptibility allele was increased in the cases (OR = 1.6,
P
= 0.01). The susceptibility allele was also associated with an increase in cancer family history (
P
= 0.1). Fine mapping showed that the region of association extends ≈300 kb and spans several genes, including the gene encoding the nuclear mitotic apparatus protein (
NuMA
). A nonsynonymous SNP (A794G) in
NuMA
was identified that showed a stronger association with breast cancer risk than the initial marker SNP (OR = 2.8,
P
= 0.005 initial sample; OR = 2.1,
P
= 0.002 combined). NuMA is a cell cycle-related protein essential for normal mitosis that is degraded in early apoptosis. NuMA-retinoic acid receptor α fusion proteins have been described in acute promyelocytic leukemia. Although the potential functional relevance of the A794G variation requires further biological validation, we conclude that variations in the
NuMA
gene are likely responsible for the observed increased breast cancer risk.
Influence of switch region length on immunoglobulin class switch recombination
Authors: Zarrin Ali A. , Tian Ming , Wang Jing , Borjeson Tiffany , Alt Frederick W.
Published: February 2005

The class and effector functions of antibodies are modulated through the process of Ig heavy chain class switch recombination (CSR). CSR occurs between switch (S) regions that lie upstream of the various Ig heavy chain constant region exons. Molecular analyses of S-region functions have been hampered by their large size and repetitive nature. To test potential relationships between S-region size and efficiency of CSR, we generated normal B lymphocytes in which the 12-kb S region flanking the Cγ1 exons (Sγ1) was replaced with synthetic or endogenous S regions of various lengths. Replacement of Sγ1 with 1- and 2-kb synthetic sequences representing the Sγ1 core repeats or a 4-kb portion of the core endogenous Sγ1 region supported CSR frequencies that directly correlated with S-region length. These findings indicate that S-region size is an important factor in determining endogenous CSR efficiency. Moreover, these results also will allow the development of a systematic system to test the function of various S-region motifs by replacing endogenous S regions with synthetic S regions controlled for size effects.
Composition and histone substrates of polycomb repressive group complexes change during cellular differentiation
Authors: Kuzmichev Andrei , Margueron Raphael , Vaquero Alejandro , Preissner Tanja S. , Scher Michael , Kirmizis Antonis , Ouyang Xuesong , Brockdorff Neil , Abate-Shen Cory , Farnham Peggy , Reinberg Danny
Published: February 2005

Changes in the substrate specificities of factors that irreversibly modify the histone components of chromatin are expected to have a profound effect on gene expression through epigenetics. Ezh2 is a histone-lysine methyltransferase with activity dependent on its association with other components of the Polycomb Repressive Complexes 2 and 3 (PRC2/3). Ezh2 levels are increasingly elevated during prostate cancer progression. Other PRC2/3 components also are elevated in cancer cells. Overexpression of Ezh2 in tissue culture promotes formation of a previously undescribed PRC complex, PRC4, that contains the NAD
+
-dependent histone deacetylase SirT1 and isoform 2 of the PRC component Eed. Eed2 is expressed in cancer and undifferentiated embryonic stem (ES) cells but is undetectable in normal and differentiated ES cells. The distinct PRCs exhibit differential histone substrate specificities. These findings suggest that formation of a transformation-specific PRC complex may have a major role in resetting patterns of gene expression by regulating chromatin structure.
Learning as peripheral participation in communities of practice: a reassessment of key concepts in workplace learning
Authors: Fuller Alison , Hodkinson Heather , Hodkinson Phil , Unwin Lorna
Published: February 2005

This article explores the strengths and weaknesses of Lave and Wenger's concept of ‘legitimate peripheral participation’ as a means of understanding workplace learning. It draws on recent ESRC‐funded research by the authors in contemporary workplace settings in the UK (manufacturing industry and secondary schools) to establish the extent to which Lave and Wenger's theories can adequately illuminate the nature and process of learning at work. The new research presented here, which was located in complex institutional settings, highlights the diverse nature of patterns and forms of participation. Case study evidence is used to identify individual and contextual factors which underpin and illuminate the ways in which employees learn. The paper argues that whilst Lave and Wenger's work continues to provide an important source of theoretical insight and inspiration for research in to learning at work, it has significant limitations. These limitations relate to the application of their perspective to contemporary workplaces in advanced industrial societies and to the institutional environments in which people work. These complex settings play a crucial role in the configuration of opportunities and barriers to learning that employees encounter.
Teachers' estimates of candidates' grades: Curriculum 2000 Advanced Level Qualifications
Authors: Dhillon Debra
Published: February 2005

In the UK, estimated grades have long been provided to higher education establishments as part of their entry procedures. Since 1994 they have also been routinely collected by awarding bodies to facilitate the grade‐awarding process. Analyses of required estimates to a British awarding body revealed that teachers' estimates of candidates' Curriculum 2000 A level grades in the first year of awarding demonstrated an unprecedented degree of accuracy. Estimates of AS level grades conversely showed relative imprecision. Accuracy of the A‐level estimates was most likely bolstered by feedback inherent to the modularisation of the examination while the weakness of AS level estimates may have been a consequence of the comparatively unfamiliar standard at which this qualification was set. As in previous research, and for both GCE qualifications, when estimates were inaccurate they were more commonly optimistic than pessimistic.
City-Visions: Visioning and Delivering Scotland's Economic Future
Authors: Peel Deborah , Lloyd Greg
Published: February 2005

The theme of this paper is the current practice of vision and visioning in land use planning in Scotland. The recent allocation of £90 million as part of the Building Better Cities Growth Fund required Scotland's six principal cities to prepare a city-vision. This was based on the perceived necessity of shared visions in providing a clear framework to guide development. The paper examines the contested concepts of visions and visioning and asks whether the prescriptive approach to the city-visions provides for inspirational or aspirational visions.
The Newcastle Employment Bond: Investing in Local Communities
Authors: Affleck Arthur , Mellor Mary
Published: February 2005

Concern with social exclusion and neighbourhood renewal has often focused on economic regeneration and new ways of stimulating employment or selfemployment in local economies. One recent initiative has been to raise private money through a bond with the social aim of creating local employment. This paper explores the Newcastle Employment Bond, its structure, the philosophy behind it and the motivations and expectations of the people and organisations who invested in it. The paper asks whether the Bond can be seen as a model of ‘Third Way’ thinking, providing an alternative to state funding of social exclusion and employment initiatives or reliance on purely profit-oriented economic regeneration.
Synergistic role of micronemal proteins in Toxoplasma gondii virulence
Authors: Cérède Odile , Dubremetz Jean François , Soête Martine , Deslée Didier , Vial Henri , Bout Daniel , Lebrun Maryse
Published: February 2005

Apicomplexan parasites invade cells by a unique mechanism involving discharge of secretory vesicles called micronemes. Microneme proteins (MICs) include transmembrane and soluble proteins expressing different adhesive domains. Although the transmembrane protein TRAP and its homologues are thought to bridge cell surface receptors and the parasite submembranous motor, little is known about the function of other MICs. We have addressed the role of MIC1 and MIC3, two soluble adhesins of Toxoplasma gondii, in invasion and virulence. Single deletion of the MIC1 gene decreased invasion in fibroblasts, whereas MIC3 deletion had no effect either alone or in the mic1KO context. Individual disruption of MIC1 or MIC3 genes slightly reduced virulence in the mouse, whereas doubly depleted parasites were severely impaired in virulence and conferred protection against subsequent challenge. Single substitution of two critical amino acids in the chitin binding–like (CBL) domain of MIC3 abolished MIC3 binding to cells and generated the attenuated virulence phenotype. Our findings identify the CBL domain of MIC3 as a key player in toxoplasmosis and reveal the synergistic role of MICs in virulence, supporting the idea that parasites have evolved multiple ligand–receptor interactions to ensure invasion of different cells types during the course of infection.
Histone variants: deviants?
Authors: Kamakaka Rohinton T. , Biggins Sue
Published: February 2005

Histones are a major component of chromatin, the protein-DNA complex fundamental to genome packaging, function, and regulation. A fraction of histones are nonallelic variants that have specific expression, localization, and species-distribution patterns. Here we discuss recent progress in understanding how histone variants lead to changes in chromatin structure and dynamics to carry out specific functions. In addition, we review histone variant assembly into chromatin, the structure of the variant chromatin, and post-translational modifications that occur on the variants.