bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of CO2 exposure on free volumes in polystyrene studied by positron annihilation spectroscopy
Authors: Chen Hongmin , Cheng Mei‐Ling , Jean Y. C. , Lee L. James , Yang Jintao 
Published: December 2007

AbstractFree‐volume properties, size and distribution, in amorphous polystyrene exposed to CO2 gases have been measured as a function of pressure to 800 psi (5.5 MPa), of time, and of temperature using positron annihilation lifetime spectroscopy. The free volume increases significantly and its distribution broadens as a function of pressure. The free volume relaxes as a function of time with a characteristic time of 15 h, and 5.7 h for 400, and 800 psi, respectively, after depressurizing under vacuum. A portion of free volume created by CO2 exposure remains permanently in the polymer after CO2 exposure. The glass transition temperature decreases significantly as a function of CO2 pressure from the free‐volume data and is compared with the differential scanning calorimeter results. The observed free‐volume variations as a function of pressure, time, and temperature are discussed in terms of hole expansion, creation, free‐volume relaxation, plasticization, and hole filling in amorphous polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 388–405, 2008
Measurement Error Correction for Distributed Properties – Filter Cake Thickness Measurements
Authors: Koch Michael , Saleem Mahmood , Krammer Gernot 
Published: December 2007

AbstractThe measurement of a distributed property is frequently encountered in engineering applications. The impact of a possible measurement error on the measured distribution is described and two methods to account for such an error are detailed: A Fourier transform based deconvolution procedure and a moment based deconvolution approach via kernel estimators are presented. The deconvolution methods can be used in many particle characterization and process applications where particle features or properties are commonly presented in a distributed form. In the current instance, these methods are carefully explored by using artificially generated data and applied to experimental data obtained from filter cake thickness measurements.
From the Rainbow to the Structure of Atoms
Authors: Gouesbet Gérard 
Published: December 2007

AbstractThe optical rainbow is nowadays of much use, in the laboratory and in industry, in the field of optical characterization. However, the geometrical optics interpretation of the optical rainbow generates a caustic singularity which is a clue that something is wrong, and that a more fundamental theory (in practice, wave optics, or Maxwell's equations) is required to explain the optical rainbow and to accurately enough interpret experiments. There also exists a mechanical rainbow in classical mechanics, also leading to a singularity, implying that classical mechanics is wrong too. To smooth out this singularity, we have to turn to a wave mechanics. By lifting the Hamilton‐Jacobi formulation of classical mechanics to a wave mechanics and looking to a time evolution equation, we may reach Schrödinger's equation. We therefore establish a beautiful connection between the rainbow in the sky, and the structure of atoms, in the sky and on earth.
A Survey of Complementary Methods for the Characterization of Dense Colloidal Silica
Authors: Tourbin Mallorie , Frances Christine 
Published: December 2007

AbstractThe aim of this study is to enhance existing knowledge of different techniques developed for the characterization of stability and particle sizing of nanoparticles in dense dispersions subjected to interparticulate and hydrodynamic forces. Silica suspension, commercially known as Klebosol® 30R50 and consisting of a particle size of 80 nm on average, was investigated in the study over a wide range of concentrations. The investigations were carried out using different optical and acoustic techniques such as laser diffraction, multiple light scattering, photon correlation spectroscopy and acoustic spectroscopy. The study details the capabilities and limitations of these modern techniques based on the different physical principles behind the characterization of the size distribution of particles in suspensions. The results are presented in terms of particle size ranges, solid concentration and technological aspects such as online and offline analysis. An important finding is that many of these modern techniques need to be improved for applications at higher concentrations since the standard models become practically invalid because of the complex interaction of acoustic and optical waves with particles in suspensions of silica.
Genetic polymorphisms in CYP17, CYP3A4, CYP19A1, SRD5A2, IGF‐1, and IGFBP‐3 and prostate cancer risk in African‐American men: The Flint Men's Health Study
Authors: Sarma Aruna V. , Dunn Rodney L. , Lange Leslie A. , Ray Anna , Wang Yunfei , Lange Ethan M. , Cooney Kathleen A. 
Published: December 2007

AbstractBACKGROUNDAssociation studies have examined the significance of several candidate genes based on biological pathways relevant to prostate carcinogenesis, including both the androgen and insulin‐like growth factor pathways. Clinical and epidemiologic evidence suggest that androgens, specifically testosterone and dihydrotestosterone (DHT) are important not only in normal prostate growth but in the pathogenesis of prostate cancer. Similarly, the insulin‐like growth factor‐1 (IGF‐1) signaling pathway regulates both cellular proliferation and apoptosis. Therefore, genes involved in the biosynthesis, activation, metabolism and degradation of androgens and the stimulation of mitogenic and antiapoptotic activities of prostate epithelial cells represent important candidates for affecting the development and progression of prostate cancer.METHODSUsing resources from the Flint Men's Health Study, a population‐based case control study of African‐American men aged 40–79, we evaluated the associations between selected single‐nucleotide polymorphisms (SNPs) in the CYP17, CYP3A4, CYP19A1, SDR5A2, IGF1, and IGFBP3 genes and prostate cancer diagnosis in 473 men (131 prostate cancer cases and 342 disease‐free controls).RESULTSWe found a significant association between prostate cancer and selected CYP17 SNP genotypes, with the heterozygous genotype conferring decreased risk. Suggestive evidence for association between IGF1 SNPs and prostate cancer were also found. No significant associations were observed between SNPs in the other genes and prostate cancer.CONCLUSIONSThese findings suggest that variation in or around CYP17 and/or IGF1 may be associated with prostate cancer development in the African‐American population. Additional studies are needed to determine whether these polymorphisms are indeed associated with prostate cancer risk in African Americans. Prostate 68: 296–305, 2008. © 2007 Wiley‐Liss, Inc.
Glyphosate‐resistant weeds of South American cropping systems: an overview
Authors: Vila‐Aiub Martin M , Vidal Ribas A , Balbi Maria C , Gundel Pedro E , Trucco Frederico , Ghersa Claudio M 
Published: December 2007

AbstractHerbicide resistance is an evolutionary event resulting from intense herbicide selection over genetically diverse weed populations. In South America, orchard, cereal and legume cropping systems show a strong dependence on glyphosate to control weeds. The goal of this report is to review the current knowledge on cases of evolved glyphosate‐resistant weeds in South American agriculture. The first reports of glyphosate resistance include populations of highly diverse taxa (Lolium multiflorum Lam., Conyza bonariensis L., C. canadensis L.). In all instances, resistance evolution followed intense glyphosate use in fruit fields of Chile and Brazil. In fruit orchards from Colombia, Parthenium hysterophorus L. has shown the ability to withstand high glyphosate rates. The recent appearance of glyphosate‐resistant Sorghum halepense L. and Euphorbia heterophylla L. in glyphosate‐resistant soybean fields of Argentina and Brazil, respectively, is of major concern. The evolution of glyphosate resistance has clearly taken place in those agroecosystems where glyphosate exerts a strong and continuous selection pressure on weeds. The massive adoption of no‐till practices together with the utilization of glyphosate‐resistant soybean crops are factors encouraging increase in glyphosate use. This phenomenon has been more evident in Argentina and Brazil. The exclusive reliance on glyphosate as the main tool for weed management results in agroecosystems biologically more prone to glyphosate resistance evolution. Copyright © 2007 Society of Chemical Industry
Stream temperature dynamics within a New Zealand glacierized river basin
Authors: Cadbury S. L. , Hannah D. M. , Milner A. M. , Pearson C. P. , Brown L. E. 
Published: December 2007

AbstractKnowledge of river thermal dynamics for glacierized basins is limited, despite the high sensitivity of these systems to climatic change/variability. This study examined spatio‐temporal water column and streambed temperature dynamics within a New Zealand glacierized river basin over two melt seasons. Water column temperature was recorded at three sites along the mainstem channel and four hillslope/groundwater‐fed tributaries. Air temperature, precipitation and stream discharge were monitored to characterize hydroclimatological conditions. Streambed temperature was monitored at the upper and lower main river sites at 0.05, 0.2 and 0.4 m depth. Water column temperature rose on average 0.6°C km−1 along the glacier‐fed mainstem. Temperature was elevated during warmer periods but the downstream increase was reduced due to greater meltwater production (consequently a larger total stream flow volume for atmospheric heating) plus a proportional reduction in warmer groundwater contributions. Hillslope/groundwater‐fed tributaries yielded a range of temperature patterns, indicating variable sourcing (meltwater or rainfall) and residence times. In the upper basin, streambed temperature was warmer than the water column, suggesting groundwater upwelling; however, during high runoff events, water column and streambed temperature converged, indicating downwelling/heat advection by channel water. At the lower site, streambed temperature mirrored the water column, suggesting greater surface water/atmospheric influences. Key drivers of stream thermal regime were: (1) relative water source contributions, (2) prevailing hydroclimatological conditions, (3) distance from source, (4) total stream flow volume and (5) basin factors (specifically, valley/channel geomorphology and riparian forest). High magnitude precipitation events produced a contrasting stream thermal response to that reported elsewhere. In contrast to European alpine research, streams showed a reduced thermal range owing to the relatively mild, wet melt season climate. This New Zealand case study highlights the importance of understanding basin‐specific modification of energy and hydrological fluxes for accurate prediction of stream thermal dynamics/habitat and ecological response to climatic variability and change. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of the importance of roe deer fawns in the spring–summer diet of red foxes in southeastern Norway
Authors: Panzacchi Manuela , Linnell John D. C. , Serrao Giulia , Eie Sveinung , Odden Morten , Odden John , Andersen Reidar 
Published: December 2007

AbstractRed foxVulpes vulpespredation on roe deerCapreolus capreolusfawns has the potential to strongly affect prey population dynamics, but it is unclear whether this relationship is symmetrical or not. We analysed the spring–summer diet of adult foxes and of their cubs in a fragmented agricultural area of southeastern Norway, where a parallel study showed that the predator kills annually 25% of the radio‐monitored roe deer fawns. The overall diet was highly varied and was dominated by small mammals (33% volume), especiallyMicrotus agrestis, and medium‐large mammals (25%), largely represented by fawns. The frequency of occurrence (FO) of fawns in the diet of adult foxes was highest in early spring, thus, supporting previous studies showing that the predator started actively hunting for fawns from the very beginning of the birth season. During the summer, the FO of both fawns and small mammals markedly declined, while that of berries and invertebrates increased. As expected for central‐place foragers, cubs consumed a higher proportion of large prey items compared to adults. In particular, 25% of scats from cubs—versus 9% from adults—contained roe deer remains, suggesting a high profitability of fawns for vixens raising offspring. However, considering the wide food spectrum and the availability of several large prey items in our study area, it seems unlikely that the importance of fawns to the diet and population dynamics of red foxes could be as great as the impact of the predator on roe deer populations. This asymmetrical relationship implies that there are unlikely to be any stabilising feedback mechanisms in the predator–prey relationship.
Critical role for c‐FLIPL on Fas resistance in colon carcinoma cell line HT‐29
Authors: Zang Fenglin , Sun Baocun , Zhao Xiulan , Niu Ruifang , Zhang Shiwu , Yu Man , Wei Xiyin , Zhang Lin 
Published: December 2007

AbstractThe cellular Fas‐associated death domain‐like interleukin‐1β‐converting enzyme inhibitory protein‐long form (c‐FLIPL) is a key regulator of Fas signaling, although owing a dominant‐negative homologue of caspase‐8, the role of c‐FLIPL remains controversial. In the present study, two pairs of small interfering RNA (siRNA) directed against c‐FLIPL were used to assess the effect of c‐FLIPL on Fas‐mediated apoptosis of colon carcinoma in vitro. HT‐29 cell line was selected for overexpression of c‐FLIPL and Fas with RT—PCR and flow cytometry analyses. After electroporation, the mRNA level of c‐FLIPL was significantly decreased (control siRNA versus c‐FLIPL siRNA, 77.97 ± 5.61% versus 26.22 ± 3.79%) and the maximum interfering efficiency was around 66.49% using semi‐quantitative RT—PCR analysis. Knockdown of c‐FLIPL with the specific siRNA sensitized colon carcinoma cells to Fas‐mediated apoptosis (control siRNA versus c‐FLIPL siRNA, 5.68 ± 2.11% versus 29.50 ± 2.27%) using DNA content analysis and Annexin V—FITC analysis. In conclusion, our study indicated that c‐FLIPL might be a suppressor of Fas‐mediated apoptosis in Fas antigen expressing colon carcinoma and therefore a potential target for novel anticancer therapies.
Testosterone protects rat hearts against ischaemic insults by enhancing the effects of α1‐adrenoceptor stimulation
Authors: Tsang S , Wu S , Liu J , Wong T M 
Published: December 2007

Background and purpose:Testosterone alleviates symptoms in patients with ischaemic heart disease. Androgen receptors are present in the heart, and testosterone upregulates gene expression of cardiac β1‐adrenoceptors. We hypothesize that testosterone may confer cardioprotection by interacting with adrenoceptors.Experimental approach:In isolated perfused hearts and ventricular myocytes from orchidectomized rats without or with testosterone (200 μg/100 g) replacement, we first determined the effect of ischaemia/reperfusion in the presence of noradrenaline (10−7 M). Then we determined the contribution of interactions between testosterone and α1‐ or β1‐adrenoceptors in cardiac injury/protection (infarct size, release of lactate dehydrogenase, viability of myocytes, recovery of contractile function and incidence of arrhythmias) upon ischaemia/reperfusion by pharmacological manipulation using selective adrenoceptor agonists (α1‐adrenoceptor agonist: phenylephrine 10−6 M; non‐selective β‐adrenoceptor agonist: isoprenaline 10−7 M) and antagonists (α1: prazosin or benoxathian 10−6 M; β1: CGP 20712A 5 × 10−7 M). We also determined the expression of α1and β1‐adrenoceptor in the hearts from rats with and without testosterone.Key results:Testosterone reduced injury induced by ischaemia/reperfusion and noradrenaline. This was achieved by enhancing the beneficial effect of α1‐adrenoceptor stimulation, which was greater than the deleterious effect of β1‐adrenoceptor stimulation (also enhanced by testosterone). The effects of testosterone were abolished or attenuated by blockade of androgen receptors. Testosterone also enhanced the expression of α1Aand β1‐adrenoceptor.Conclusions and implications:Testosterone conferred cardioprotection by upregulating the cardiac α1‐adrenoceptor and enhancing the effects of stimulation of this adrenoceptor. The effect of testosterone was at least partly mediated by androgen receptors.British Journal of Pharmacology(2008)153, 693–709; doi:10.1038/sj.bjp.0707624; published online 24 December 2007
Experimental models, neurovascular mechanisms and translational issues in stroke research
Authors: Lo E H 
Published: December 2007

Numerous failures in clinical stroke trials have led to some pessimism in the field. This short review examines the following questions: Can experimental models of stroke be validated? How can combination stroke therapies be productively pursued? Can we achieve neuroprotection without reperfusion? And finally, can we move from a pure neurobiology view of stroke towards a more integrative approach targeting all cell types within the entire neurovascular unit? Emerging data from both experimental models and clinical findings suggest that neurovascular mechanisms may provide new opportunities for treating stroke. Ultimately, both bench‐to‐bedside and bedside‐back‐to‐bench interactions may be required to overcome the translational hurdles for this challenging disease.British Journal of Pharmacology (2008) 153, S396–S405; doi:10.1038/sj.bjp.0707626; published online 24 December 2007
Different mechanisms underlie the analgesic actions of paracetamol and dipyrone in a rat model of inflammatory pain
Authors: Rezende R M , França D S , Menezes G B , dos Reis W G P , Bakhle Y S , Francischi J N 
Published: December 2007

Background and purpose:The analgesics, paracetamol and dipyrone are weak inhibitors of the cyclooxygenase isoforms 1 or 2 (COX‐1, COX‐2) but more potent on COX‐3. Both are also weak anti‐inflammatory agents, relative to their analgesic and antipyretic activities. In a model of inflammatory pain mediated by prostaglandins, both compounds were analgesic. We have analysed this shared effect further in order to elucidate the underlying mechanisms.Experimental approach:Inflammation was induced in one hind paw of rats by intraplantar injection of 250 μg λ‐carrageenan (CG) and the contralateral paw injected with saline. Nociceptive thresholds to mechanical stimulation were measured immediately before and for 6 h after, injection of CG. The analgesics were s.c. or locally (intraplantar) injected either 30 min before or 2 h after CG. In some groups, naltrexone was injected (s.c. or intraplantar), 1 h before CG.Key results:Pretreatment with paracetamol or dipyrone (60–360 mg kg−1) reversed hyperalgesia induced by CG and increased nociceptive threshold in the inflamed paw above the basal level (hypoalgesia). Paracetamol, but not dipyrone, also raised nociceptive thresholds in the non‐inflamed paw. Subcutaneous, but not local, administration of naltrexone, a specific opioid antagonist, reversed the hypoalgesia induced by paracetamol, but similar naltrexone treatment had no effect on dipyrone‐induced analgesia.Conclusions and implications:Although both paracetamol and dipyrone are inhibitors of COX isoforms and thus of prostaglandin biosynthesis and were analgesic in our model, their analgesic actions were functionally and mechanistically different. Satisfactory mechanisms of action for these analgesics still remain to be established.British Journal of Pharmacology(2008)153, 760–768; doi:10.1038/sj.bjp.0707630; published online 24 December 2007
A study of antagonist affinities for the human histamine H2receptor
Authors: Baker J G 
Published: December 2007

Background and purpose:Ligand affinity has been a fundamental concept in the field of pharmacology and has traditionally been considered to be constant for a given receptor–ligand interaction. Recent studies have demonstrated that this is not true for all three members of the Gs‐coupled β‐adrenoceptor family. This study evaluated antagonist affinity measurements at a different Gs‐coupled receptor, the histamine H2receptor, to determine whether antagonist affinity measurements made at a different family of GPCRs were constant.Experimental approach:CHO cells stably expressing the human histamine H2receptor and a CRE‐SPAP reporter were used and antagonist affinity was assessed in short‐term cAMP assays and longer term CRE gene transcription assays.Key results:Nine agonists and seven antagonists, of sufficient potency at the H2receptor to examine in detail, were identified. Measurements of antagonist affinity were the same regardless of the efficacy of the competing agonist, time of agonist incubation, cellular response measured or presence of a PDE inhibitor.Conclusions and implications:Antagonist affinity at the Gs‐coupled histamine H2receptor obeys the accepted dogma for antagonism at GPCRs. This study further confirms that something unusual is indeed happening with the β‐adrenoceptors and is not an artefact related to the transfected cell system used. As the human histamine H2receptor does not behave in a similar manner to any of the human β‐adrenoceptors, it is clear that information gathered from one GPCR cannot be simply extrapolated to predict the behaviour of another GPCR. Each GPCR therefore requires careful and detailed evaluation on its own.British Journal of Pharmacology(2008)153, 1011–1021; doi:10.1038/sj.bjp.0707644; published online 24 December 2007
Skeletal muscle expresses the extracellular cyclic AMP–adenosine pathway
Authors: Chiavegatti T , Costa V L , Araújo M S , Godinho R O 
Published: December 2007

Background and purpose:cAMP is a key intracellular signalling molecule that regulates multiple processes of the vertebrate skeletal muscle. We have shown that cAMP can be actively pumped out from the skeletal muscle cell. Since in other tissues, cAMP efflux had been associated with extracellular generation of adenosine, in the present study we have assessed the fate of interstitial cAMP and the existence of an extracellular cAMP‐adenosine signalling pathway in skeletal muscle.Experimental approach:cAMP efflux and/or its extracellular degradation were analysed by incubating rat cultured skeletal muscle with exogenous cAMP, forskolin or isoprenaline. cAMP and its metabolites were quantified by radioassay or HPLC, respectively.Key results:Incubation of cells with exogenous cAMP was followed by interstitial accumulation of 5′‐AMP and adenosine, a phenomenon inhibited by selective inhibitors of ecto‐phosphodiesterase (DPSPX) and ecto‐nucleotidase (AMPCP). Activation of adenylyl cyclase (AC) in cultured cells with forskolin or isoprenaline increased cAMP efflux and extracellular generation of 5′‐AMP and adenosine. Extracellular cAMP‐adenosine pathway was also observed after direct and receptor‐dependent stimulation of AC in rat extensor muscleex vivo. These events were attenuated by probenecid, an inhibitor of ATP binding cassette family transporters.Conclusions and implications:Our results show the existence of an extracellular biochemical cascade that converts cAMP into adenosine. The functional relevance of this extracellular signalling system may involve a feedback modulation of cellular response initiated by several G protein‐coupled receptor ligands, amplifying cAMP influence to a paracrine mode, through its metabolite, adenosine.British Journal of Pharmacology(2008)153, 1331–1340; doi:10.1038/sj.bjp.0707648; published online 24 December 2007