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Selected AbstractsProposing magnetic nanoparticle hyperthermia in low-field MRICONCEPTS IN MAGNETIC RESONANCE, Issue 1 2010Pádraig Cantillon-Murphy Abstract This work examines feasibility, practical advantages, and disadvantages of a combined MRI/magnetic particle hyperthermia (MPH) system for cancerous tumor treatment in low perfusion tissue. Although combined MRI/hyperthermia systems have been proposed and constructed, the current proposal differs because the hyperthermia system would be specifically designed to interact with the magnetic nanoparticles injected at the tumor site. The proposal exploits the physical similarities between the magnetic nanoparticles currently employed for MPH and those used as superparamagnetic iron oxide (SPIO) contrast agents in MR imaging. The proposal involves the addition of a rotating magnetic field RF hyperthermia source perpendicular to the MRI B0 field which operates in a similar manner to the MRI RF excitation field, B1, but at significantly higher frequency and field strength such that the magnetic nanoparticles are forced to rotate in its presence. This rotation is the source of increases in temperature which are of therapeutic benefit in cancer therapy. For rotating magnetic fields with amplitudes much smaller than B0, the nanoparticles' suspension magnetization rapidly saturates with increasing B0. Therefore, the proposal is best suited to low-field MRI systems when magnetic saturation is incomplete. In addition, careful design of the RF hyperthermia source is required to ensure no physical or RF interference with the B1 field used for MRI excitation. Notwithstanding these caveats, the authors have shown that localized steady-state temperature rises in small spherical tumors of up to 10°C are conceivable with careful selection of the nanoparticle radius and concentration, RF hyperthermia field amplitude and frequency. © 2010 Wiley Periodicals, Inc. Concepts Magn Reson Part A 36A: 36,47, 2010. [source] InterGrid: a case for internetworking islands of GridsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 8 2008Marcos Dias de Assunção Abstract Over the last few years, several nations around the world have set up Grids to share resources such as computers, data, and instruments to enable collaborative science, engineering, and business applications. These Grids follow a restricted organizational model wherein a Virtual Organization (VO) is created for a specific collaboration and all interactions such as resource sharing are limited to within the VO. Therefore, dispersed Grid initiatives have led to the creation of disparate Grids with little or no interaction between them. In this paper, we propose a model that: (a) promotes interlinking of islands of Grids through peering arrangements to enable InterGrid resource sharing; (b) provides a scalable structure for Grids that allow them to interconnect with one another and grow in a sustainable way; (c) creates a global Cyberinfrastructure to support e-Science and e-Business applications. This work identifies and proposes architecture, mechanisms, and policies that allow the internetworking of Grids and allows Grids to grow in a similar manner as the Internet. We term the structure resulting from such internetworking between Grids as the InterGrid. The proposed InterGrid architecture is composed of InterGrid Gateways responsible for managing peering arrangements between Grids. We discuss the main components of the architecture and present a research agenda to enable the InterGrid vision. Copyright © 2007 John Wiley & Sons, Ltd. [source] Copeptin: A Biomarker of Cardiovascular and Renal FunctionCONGESTIVE HEART FAILURE, Issue 2010Nils G. Morgenthaler MD Congest Heart Fail. 2010;16(4)(suppl 1):S37,S44. ©2010 Wiley Periodicals, Inc. Arginine vasopressin (AVP or antidiuretic hormone) is one of the key hormones in the human body responsible for a variety of cardiovascular and renal functions. It has so far escaped introduction into the routine clinical laboratory due to technical difficulties and preanalytical errors. Copeptin, the C-terminal part of the AVP precursor peptide, was found to be a stable and sensitive surrogate marker for AVP release. Copeptin behaves in a similar manner to mature AVP in the circulation, with respect to osmotic stimuli and hypotension. During the past years, copeptin measurement has been shown to be of interest in a variety of clinical indications, including cardiovascular diseases such as heart failure, myocardial infarction, and stroke. This review summarizes the recent progress on the diagnostic use of copeptin in cardiovascular and renal diseases and discusses the potential use of copeptin measurement in the context of therapeutic interventions with vasopressin receptor antagonists. [source] Making White: Constructing Race in a South African High SchoolCURRICULUM INQUIRY, Issue 1 2002Nadine Dolby As a social and cultural phenomenon, race is continually remade within changing circumstances and is constructed and located, in part, in institutions' pedagogical practices and discourses. In this article I examine how the administration of a multiracial, working-class high school in Durban, South Africa produces "white" in an era of political and social transition. As the population of Fernwood High School (a pseudonym) shifts from majority white working class to black working class, the school administration strives to reposition the school as "white," despite its predominantly black student population. This whiteness is not only a carryover from the apartheid era, but is actively produced within a new set of circumstances. Using the discourses and practices of sports and standards, the school administration attempts to create a whiteness that separates the school from the newly democratic nation-state of South Africa. Despite students' and some staff's general complacency and outright resistance, rugby and athletics are heralded as critical nodes of the school's "white" identity, connecting the school to other, local white schools, and disconnecting it from black schools. Dress standards function in a similar manner, creating an imagined equivalence between Fernwood and other white schools in Durban (and elite schools around the world), and disassociating Fernwood from black schools in South Africa and the "third world" writ large. This pedagogy of whiteness forms the core of the administration's relationship with Fernwood students, and maps how race is remade within a changing national context. [source] Caenorhabditis elegans expresses three functional profilins in a tissue-specific mannerCYTOSKELETON, Issue 1 2006D. Polet Abstract Profilins are actin binding proteins, which also interact with polyphosphoinositides and proline-rich ligands. On the basis of the genome sequence, three diverse profilin homologues (PFN) are predicted to exist in Caenorhabditis elegans. We show that all three isoforms PFN-1, PFN-2, and PFN-3 are expressed in vivo and biochemical studies indicate they bind actin and influence actin dynamics in a similar manner. In addition, they bind poly(L -proline) and phosphatidylinositol 4,5-bisphosphate micelles. PFN-1 is essential whereas PFN-2 and PFN-3 are nonessential. Immunostainings revealed different expression patterns for the profilin isoforms. In embryos, PFN-1 localizes in the cytoplasm and to the cell,cell contacts at the early stages, and in the nerve ring during later stages. During late embryogenesis, expression of PFN-3 was specifically detected in body wall muscle cells. In adult worms, PFN-1 is expressed in the neurons, the vulva, and the somatic gonad, PFN-2 in the intestinal wall, the spermatheca, and the pharynx, and PFN-3 localizes in a striking dot-like fashion in body wall muscle. Thus the model organism Caenorhabditis elegans expresses three profilin isoforms and is the first invertebrate animal with tissue-specific profilin expression. Cell Motil. Cytoskeleton, 2006.© 2005 Wiley-Liss, Inc. [source] Atypical molecular profile for joint development in the avian costal jointDEVELOPMENTAL DYNAMICS, Issue 10 2010B.B. Winslow Abstract Development of synovial joints involves generation of cartilaginous anlagen, formation of interzones between cartilage anlagen, and cavitation of interzones to produce fluid filled cavities. Interzone development is not fully understood, but interzones are thought to develop from skeletogenic cells that are inhibited from further chondrogenic development by a cascade of gene expression including Wnt and Bmp family members. We examined the development of the rarely studied avian costal joint to better understand mechanisms of joint development. The costal joint is found within ribs, is morphologically similar to the metatarsophalangeal joint, and undergoes cavitation in a similar manner. In contrast to other interzones, Wnt14/9a, Gdf5, Chordin, Barx1, and Bapx1 are absent from the costal joint interzone, consistent with the absence of active ,-catenin and phosphorylated Smad 1/5/8. However Autotaxin and Noggin are expressed. The molecular profile of the costal joint suggests there are alternative mechanisms of interzone development. Developmental Dynamics 239:2547,2557, 2010. © 2010 Wiley-Liss, Inc. [source] Degradation in insulin sensitivity with increasing severity of the metabolic syndrome in obese postmenopausal womenDIABETES OBESITY & METABOLISM, Issue 3 2006A. D. Karelis Aim:, We investigated the relationship between insulin sensitivity and the graded increase in the number of features of the metabolic syndrome in a cross-sectional sample of obese postmenopausal women. We hypothesized that insulin sensitivity would deteriorate with an increased number of metabolic syndrome phenotypes. Methods:, Insulin sensitivity was measured in 75 obese postmenopausal women (age: 57.3 ± 5.3 years; BMI: 32.8 ± 4.5 kg/m2) by using both the hyperinsulinaemic,euglycaemic clamp and the homeostasis model assessment (HOMA-IR). Features of the metabolic syndrome included visceral fat (>130 cm2), HDL-cholesterol (<1.29 mmol/l), fasting triglycerides (,1.7 mmol/l), blood pressure (,130/,85 mmHg) and fasting glucose (,6.1 mmol/l). Participants were classified into three categories based on the presence of metabolic syndrome phenotypes: 0,1 vs. 2 vs. ,3 features of the metabolic syndrome. Results:, We found that insulin sensitivity decreased in a graded fashion (12.19 ± 3.2 vs. 11.80 ± 2.3 vs. 9.29 ± 2.6 mg/min/FFM) and HOMA-IR increased in a similar manner (2.95 ± 1.1 vs. 3.28 ± 1.3 vs. 4.65 ± 2.2), as the number of features of the metabolic syndrome increased from 0,1 to ,3. When insulin sensitivity was statistically adjusted for visceral fat (as measured by computed tomography) and plasma triglycerides, the differences among groups were abolished. Conclusions:, These findings suggest that a decreased insulin sensitivity is associated with increased features of the metabolic syndrome in obese postmenopausal women and that visceral fat as well as plasma triglyceride accumulation might be potential mediators of this relationship. [source] Randomized controlled trial of intrasphincteric botulinum toxin A injection versus balloon dilatation in treatment of achalasia cardiaDISEASES OF THE ESOPHAGUS, Issue 3-4 2001U. C. Ghoshal As the few randomized controlled trials available in the literature comparing botulinum toxin (BT) injection with established endoscopic treatment of achalasia cardia, i.e. pneumatic dilatation, showed conflicting results, we conducted a prospective randomized trial. Seventeen consecutive patients with achalasia cardia diagnosed during a period between December 1997 and February 2000 were randomized into two treatment groups [pneumatic dilatation by Rigiflex dilator (n=10), BT injection by sclerotherapy needle into four quadrants of lower esophageal sphincter (LES) (n=7) 80 units in five cases, 60 units in two cases] after dysphagia grading, endoscopy, barium esophagogram, and manometry, all of which were repeated 1 week after treatment. Patients were followed up clinically for 35.2 ± 14 weeks. Chi-squares, Wilcoxon rank-sum test, Kaplan,Meier method and log-rank tests were used for statistical analysis. After 1 week, 6/7 (86%) BT-treated vs. 8/10 (80%) dilatation-treated patients improved (P=NS). There was no difference in LES pressure and maximum esophageal diameter in the barium esophagogram in the two groups before therapy. Both therapies resulted in significant reduction in LES pressure. The cumulative dysphagia-free state using the Kaplan,Meier method decreased progressively in BT-treated compared with dilatation-treated patients (P=0.027). Two patients with tortuous megaesophagus, one of whom had failed dilatation complicated by perforation previously, improved after BT. One other patient in whom pneumatic dilatation had previously failed improved in a similar manner. BT is as good as pneumatic dilatation in achieving an initial improvement in dysphagia of achalasia cardia. It is also effective in patients with tortuous megaesophagus and previous failed pneumatic dilatation. However, dysphagia often recurs during 1-year follow up. [source] CNS response to a thermal stressor in human volunteers and rats may predict the clinical utility of analgesicsDRUG DEVELOPMENT RESEARCH, Issue 1 2007David Borsook Abstract fMRI was used to test the hypothesis that global brain activation following a stressor (a thermal stimulus) that activates multiple brain circuits in healthy subjects can predict which drugs have higher potential for clinical utility for neuropathic pain. The rationale is that a drug will modulate multiple neural circuits that are activated by the system-specific stressor (e.g., pain). In neuropathic pain, some brain circuits have altered function, but most brain systems are "normal." Thus, the manner in which a drug effect on neural circuits is modulated by the stressor may provide insight into the clinical utility based on the readout of brain activation in response to the stimulus. Six drugs with known clinical efficacy (or lack thereof) in treating neuropathic pain were selected and the CNS response to each drug in the presence or absence of a pain stimulus was examined. The present results suggest that it is possible to identify potentially effective drugs based on patterns of brain activation in healthy human subjects and indicate that CNS activity is a more sensitive measure of drug action than standard psychophysical measures of pain intensity. This approach was repeated in rats and showed that a similar fMRI paradigm segregates these drugs in a similar manner suggesting a potential "translational tool" in evaluating drug efficacy for neuropathic pain. The sensitivity of this paradigm using fMRI allows clinical screening in small groups of healthy subjects, suggesting it could become a useful tool for drug development as well as for elucidating the mechanisms of neuropathic disease and therapy. Drug Dev. Res. 68:23,41, 2007. © 2007 Wiley-Liss, Inc. [source] Anthropogenic disturbance affects the structure of bacterial communitiesENVIRONMENTAL MICROBIOLOGY, Issue 3 2010Duane Ager Summary Patterns of taxa abundance distributions are the result of the combined effects of historical and biological processes and as such are central to ecology. It is accepted that a taxa abundance distribution for a given community of animals or plants following a perturbation will typically change in structure from one of high evenness to increasing dominance. Subsequently, such changes in evenness have been used as indicators of biological integrity and environmental assessment. Here, using replicated experimental treehole microcosms perturbed with different concentrations of the pollutant pentachlorophenol, we investigated whether changes in bacterial community structure would reflect the effects of anthropogenic stress in a similar manner to larger organisms. Community structure was visualized using rank,abundance plots fitted with linear regression models. The slopes of the regression models were used as a descriptive statistic of changes in evenness over time. Our findings showed that bacterial community structure reflected the impact and the recovery from an anthropogenic disturbance. In addition, the intensity of impact and the rate of recovery to pre-perturbation structure were dose-dependent. These properties of bacterial community structures may potentially provide a metric for environmental assessment and regulation. [source] PRECLINICAL STUDY: Conditioned cues and yohimbine induce reinstatement of beer and near-beer seeking in Long-Evans ratsADDICTION BIOLOGY, Issue 2 2009Jemma K. Richards ABSTRACT Alcohol use disorders (AUDs) impact millions of individuals, yet there are few effective treatments. One major problem in treating AUDs is the high rate of relapse to drinking often induced by stress and/or anxiety states. Although beer accounts for over 81% of all alcohol consumed in hazardous amounts in the United States, the use of beer in pre-clinical research has been limited. It has been shown that rats will self-administer beer and near-beer using a standard operant self-administration paradigm; however, there have been few studies examining reinstatement of beer and near-beer seeking. We have determined that reward-associated cues and/or yohimbine will induce reinstatement of beer and near-beer seeking in a similar manner to that seen for 10% ethanol and sucrose seeking using standard operant self-administration and reinstatement paradigms. We show that rats will self-administer beer, near-beer and 4.5% ethanol using an operant self-administration paradigm and both conditioned cues, and yohimbine will induce reinstatement of beer, near-beer and 4.5% ethanol seeking in previously extinguished animals. This demonstrates that both environmental cues and yohimbine-stress will reinstate beer and near-beer seeking, as previously shown for both 10% ethanol and sucrose seeking. [source] Activation of histaminergic H3 receptors in the rat basolateral amygdala improves expression of fear memory and enhances acetylcholine releaseEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2002Iacopo Cangioli Abstract The basolateral amygdala (BLA) is involved in learning that certain environmental cues predict threatening events. Several studies have shown that manipulation of neurotransmission within the BLA affects the expression of memory after fear conditioning. We previously demonstrated that blockade of histaminergic H3 receptors decreased spontaneous release of acetylcholine (ACh) from the BLA of freely moving rats, and impaired retention of fear memory. In the present study, we examined the effect of activating H3 receptors within the BLA on both ACh release and expression of fear memory. Using the microdialysis technique in freely moving rats, we found that the histaminergic H3 agonists R-,-methylhistamine (RAMH) and immepip, directly administered into the BLA, augmented spontaneous release of ACh in a similar manner. Levels of ACh returned to baseline on perfusion with control medium. Rats receiving intra-BLA, bilateral injections of the H3 agonists at doses similar to those enhancing ACh spontaneous release, immediately after contextual fear conditioning, showed stronger memory for the context,footshock association, as demonstrated by longer freezing assessed at retention testing performed 72 h later. Post-training, bilateral injections of 15 ng oxotremorine also had a similar effect on memory retention, supporting the involvement of the cholinergic system. Thus, our results further support a physiological role for synaptically released histamine, that in addition to affecting cholinergic transmission in the amygdala, modulates consolidation of fear memories [source] Modulation of glycine responses by dihydropyridines and verapamil in rat spinal neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2001Dominique Chesnoy-Marchais Abstract Although glycine receptors (GlyRs) are responsible for the main spinal inhibitory responses in adult vertebrates, in the embryo they have been reported to mediate depolarizing responses, which can sometimes activate dihydropyridine-sensitive l -type calcium channels. However, these channels are not the only targets of dihydropyridines (DHPs), and we questioned whether GlyRs might be directly modulated by DHPs. By whole-cell recording of cultured spinal neurons, we investigated modulation of glycine responses by the calcium channel antagonists, nifedipine, nitrendipine, nicardipine and (R)-Bay K 8644, and by the calcium channel, agonist (S)-Bay K 8644. At concentrations between 1 and 10 µm, all these DHPs could block glycine responses, even in the absence of extracellular Ca2+. The block was stronger at higher glycine concentrations, and increased with time during each glycine application. Nicardipine blocked GABAA responses from the same neurons in a similar manner. In addition to their blocking effects, nitrendipine and nicardipine potentiated the peak responses to low glycine concentrations. Both effects of extracellular nitrendipine on glycine responses persisted when the drug was present in the intracellular solution. Thus, these modulations are related neither to calcium channel modulation nor to possible intracellular effects of DHPs. Another type of calcium antagonist, verapamil (10,50 µm), also blocked glycine responses. Our results suggest that some of the effects of calcium antagonists, including the neuroprotective and anticonvulsant effects of DHPs, might result partly from their interactions with ligand-gated chloride channels. [source] Development of Ketoside-Type Analogues of Trehalose by Using ,-Stereoselective O-Glycosidation of KetoseEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2007Rie Namme Abstract The stereoselective synthesis of ketoside-type analogues of trehalose is described. O-Glycosidation of hept-2-ulopyranose with trimethylsilyl ,-pyranoside promoted by trimethylsilyl trifluoromethanesulfonate afforded ,-ketopyranosyl ,-aldopyranosides exclusively. ,-Ketopyranosyl ,-aldooyranosides and ,-ketopyranosyl ,-ketopyranosides were also synthesized in a similar manner. The benzyl protecting groups of the hydroxy moieties were removed by hydrogenolysis to afford fully deprotected trehalose analogues.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Aminium Hexachloroantimonate Salts as Latent Sources of Antimony Pentachloride in Pinacolic Rearrangement of Vicinal DiolsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2005Francesco Ciminale, Luigi Lopez Abstract Rearrangements of various vicinal diols (1a,f) induced by hexachloroantimonate aminium salts A or B were found to occur in a similar manner when antimony pentachloride was used instead of aminium salts. Antimony pentachloride is proposed as the active catalytic species, possibly deriving from the oxidation of the hexachloroantimonate anion SbCl6, by the aminium counterpart. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Cardiovascular Response to Graded Lower Body Negative Pressure in Young and Elderly ManEXPERIMENTAL PHYSIOLOGY, Issue 3 2001R. van Hoeyweghen Lower body negative pressure (LBNP) reduces central venous pressure (CVP) and cardiac output. The elderly are reported to have a limited capacity to increase cardiac output by increasing heart rate (HR), are especially dependent on end diastolic volume to maintain stroke volume and therefore should be especially vulnerable to LBNP. The present study compared the effects of LBNP in the young and old. Stroke volume was assessed non-invasively as stroke distance (SD) by aortovelography. Two groups of healthy male volunteers were studied: eight young (29.7 ± 2.0 years, mean ± S.E.M.) and nine old (70.1 ± 0.9 years). LBNP was applied progressively at 17.5, 35 and 50 mmHg in 20 min steps, with measurements taken during each steady state. There were similar, significant, falls in CVP in both groups. SD fell significantly in both groups from respective control values of 24.8 ± 1.6 and 16.6 ± 0.9 cm to 12.5 ± 1.3 and 8.9 ± 0.4 cm at a LBNP of 50 mmHg. Although SD in the elderly was significantly lower than in the young, the LBNP-induced changes were not different between groups. Both groups produced similar significant increases in vascular resistance, HR, plasma vasopressin (AVP) and noradrenaline. Mean arterial blood pressure (MBP) and plasma adrenaline did not change significantly. Therefore healthy old men respond to LBNP in a similar manner to the young, although MBP and SD are regulated around different baselines in the two groups. [source] Thermodynamic characterization of substrate and inhibitor binding to Trypanosoma brucei 6-phosphogluconate dehydrogenaseFEBS JOURNAL, Issue 24 2007Katy Montin 6-Phosphogluconate dehydrogenase is a potential target for new drugs against African trypanosomiasis. Phosphorylated aldonic acids are strong inhibitors of 6-phosphogluconate dehydrogenase, and 4-phospho- d -erythronate (4PE) and 4-phospho- d -erythronohydroxamate are two of the strongest inhibitors of the Trypanosoma brucei enzyme. Binding of the substrate 6-phospho- d -gluconate (6PG), the inhibitors 5-phospho- d -ribonate (5PR) and 4PE, and the coenzymes NADP, NADPH and NADP analogue 3-amino-pyridine adenine dinucleotide phosphate to 6-phospho- d -gluconate dehydrogenase from T. brucei was studied using isothermal titration calorimetry. Binding of the substrate (Kd = 5 µm) and its analogues (Kd =1.3 µm and Kd = 2.8 µm for 5PR and 4PE, respectively) is entropy driven, whereas binding of the coenzymes is enthalpy driven. Oxidized coenzyme and its analogue, but not reduced coenzyme, display a half-site reactivity in the ternary complex with the substrate or inhibitors. Binding of 6PG and 5PR poorly affects the dissociation constant of the coenzymes, whereas binding of 4PE decreases the dissociation constant of the coenzymes by two orders of magnitude. In a similar manner, the Kd value of 4PE decreases by two orders of magnitude in the presence of the coenzymes. The results suggest that 5PR acts as a substrate analogue, whereas 4PE mimics the transition state of dehydrogenation. The stronger affinity of 4PE is interpreted on the basis of the mechanism of the enzyme, suggesting that the inhibitor forces the catalytic lysine 185 into the protonated state. [source] Importance of Cryphonectria parasitica stromata production and intermediate-pigmented isolates in spread of Cryphonectria hypovirus 1 on grafted American chestnut treesFOREST PATHOLOGY, Issue 5 2008E. P. Hogan Summary Large, surviving American chestnut trees, grafted in 1980, were inoculated in 1982 and 1983 with four ,white' European (French and Italian) hypovirulent strains of Cryphonectria parasitica infected with Cryphonectria hypovirus 1 (CHV1). Spread of Italian CHV1-Euro7, indicated by nucleotide sequence analysis of CHV1 isolates, and a high level of blight control, occurred on these trees for over 20 years. However, the means by which CHV1 spreads and the possible role of stromata production in that spread are unknown. In this study, 249 C. parasitica isolates were recovered from stromata excised from natural cankers on the grafted trees and plated on an agar medium; 5.2% of the stromata yielded white phenotype isolates, 9.2% yielded intermediate-pigmented isolates (30,70% pigmentation) and the remainder were normal-pigmented isolates. For comparison, cankers artificially established on blight-free, forest-clear-cut American chestnut trees, following inoculation with three Italian white hypovirulent strains, were evaluated in a similar manner. Of 241 C. parasitica isolates recovered from stromata, 66.4% had a white colony phenotype, 19.1% had an intermediate-pigmented phenotype and the remainder were normal-pigmented isolates. For single conidia collected from stromata and plated, nearly equal frequencies of only white and intermediate-pigmented colony phenotypes were obtained. Following dsRNA extraction and electrophoresis, 21 of 33 intermediate-pigmented isolates were positive for CHV1. Some normal pigmented isolates also were positive for CHV1. Single-sporing a CHV1-positve, normal-pigmented, natural-canker, stroma isolate (Str 1) from the grafts resulted in several deeply red-orange pigmented (JR) isolates as well as some white isolates. The dsRNA in the JR isolate was extracted and cDNAs made by reverse transcriptase-polymerase chain reaction (RT-PCR) for part of a region (p29) in ORF A. Nucleotide sequencing indicated 100% identity to CHV1 present in the inoculated Italian white strain, Ep 47. The results indicate that stromata production on the grafted trees may contribute to CHV1 spread, and the presence of CHV1 in intermediate-pigmented isolates and some normal pigmented isolates indicates these isolates, often overlooked, may be important in CHV1 spread and the high level of blight control on the grafted trees. [source] Structural basis of target recognition by Atg8/LC3 during selective autophagyGENES TO CELLS, Issue 12 2008Nobuo N. Noda Autophagy is a non-selective bulk degradation process in which isolation membranes enclose a portion of cytoplasm to form double-membrane vesicles, called autophagosomes, and deliver their inner constituents to the lytic compartments. Recent studies have also shed light on another mode of autophagy that selectively degrades various targets. Yeast Atg8 and its mammalian homologue LC3 are ubiquitin-like modifiers that are localized on isolation membranes and play crucial roles in the formation of autophagosomes. These proteins are also involved in selective incorporation of specific cargo molecules into autophagosomes, in which Atg8 and LC3 interact with Atg19 and p62, receptor proteins for vacuolar enzymes and disease-related protein aggregates, respectively. Using X-ray crystallography and NMR, we herein report the structural basis for Atg8,Atg19 and LC3,p62 interactions. Remarkably, Atg8 and LC3 were shown to interact with Atg19 and p62, respectively, in a quite similar manner: they recognized the side-chains of Trp and Leu in a four-amino acid motif, WXXL, in Atg19 and p62 using hydrophobic pockets conserved among Atg8 homologues. Together with mutational analyses, our results show the fundamental mechanism that allows Atg8 homologues, in association with WXXL-containing proteins, to capture specific cargo molecules, thereby endowing isolation membranes and/or their assembly machineries with target selectivity. [source] RMF inactivates ribosomes by covering the peptidyl transferase centre and entrance of peptide exit tunnelGENES TO CELLS, Issue 4 2004Hideji Yoshida In gram-negative bacteria such as Escherichia coli, protein synthesis is suppressed by the formation of 100S ribosomes under stress conditions. The 100S ribosome, a dimer of 70S ribosomes, is formed by ribosome modulation factor (RMF) binding to the 70S ribosomes. During the stationary phase, most of the 70S ribosomes turn to 100S ribosomes, which have lost translational activity. This 100S formation is called the hibernation process in the ribosome cycle of the stationary phase. If stationary phase cells are transferred to fresh medium, the 100S ribosomes immediately go back to active 70S ribosomes, showing that inactive 100S , active 70S interconversion is a major system regulating translation activity in stationary phase cells. To elucidate the mechanisms of translational inactivation, the binding sites of RMF on 23S rRNA in 100S ribosome of E. coli were examined by a chemical probing method using dimethyl sulphate (DMS). As the results, the nine bases in 23S rRNA were protected from DMS modifications and the modification of one base was enhanced. Interestingly A2451 is included among the protected bases, which is thought to be directly involved in peptidyl transferase activity. We conclude that RMF inactivates ribosomes by covering the peptidyl transferase (PTase) centre and the entrance of peptide exit tunnel. It is surprising that the cell itself produces a protein that seems to inhibit protein synthesis in a similar manner to antibiotics and that it can reversibly bind to and release from the ribosome in response to environmental conditions. [source] Oligo(triacetylene) Derivatives with Pendant Long Alkyl ChainsHELVETICA CHIMICA ACTA, Issue 6 2004Jean-François Nierengarten Substituted (E)-2-(ethynyl)but-2-ene and (E)-hex-3-ene-1,5-diyne derivatives 6 and 10, respectively, were prepared by dicyclohexylcarbodiimide(DCC)-mediated esterification of tris(dodecyloxy)benzoic acid (4) with (E)-2-[(triisopropylsilyl)ethynyl]but-2-ene-1,4-diol (3) and (E)-2,3-bis[(trimethylsilyl)ethynyl]but-2-ene-1,4-diol (8), respectively, followed by deprotection with Bu4NF in wet THF (Schemes,1 and 2). Oligomerization reactions of diyne derivative 10 were attempted by treatment with the Hay catalyst in the presence of mono-alkyne 6 as an end-capping reagent. Under these conditions, only compound 7 resulting from the homocoupling of 6 (Scheme,1), and polymers of 10 were obtained due to the difference in reactivity of the alkyne groups in 6 and 10. In contrast, when phenylacetylene was used as the stopper, the oligomerization of 10 afforded a mixture of end-capped oligomers, from which 11,13 were isolated by column chromatography (Scheme,3). The poly(triacetylenes) (PTA) 16,18 were prepared in a similar manner starting from diol 8 and stearic acid (Schemes,4 and 5). Whereas the end-capped monomers and dimers 11, 12, 16, and 17 with pendant long alkyl chains do not exhibit any liquid-crystalline behavior, the trimeric derivatives 13 and 18 show mesomorphic properties, thus demonstrating that the poly(triacetylene) backbone can behave as a mesogenic unit. [source] Influence of inherent anisotropy on mechanical behavior of granular materials based on DEM simulationsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2010Zafar Mahmood Abstract We study the influence of inherent anisotropy, i.e. bedding angle on stress,strain behavior and shear band formation in quasi-static granular media. Plane strain biaxial tests are carried out using two-dimensional distinct element method (DEM). Oval/elliptical-shaped particles are generated by overlapping the discrete circular elements. Particle assemblies with four different bedding angles are tested. Evolution of the microstructure inside and outside the shear band and effect of bedding angle on the microstructure are investigated. Influence of bedding angle on fabric and force anisotropy is studied. It is found that by using non-circular particles, generation of large voids and excess particle rotations inside the shear band are reproduced in a quite similar manner to those of the natural granular soils, which are difficult to produce with standard DEM simulations using circular particles. Copyright © 2009 John Wiley & Sons, Ltd. [source] Performance of Jacobi preconditioning in Krylov subspace solution of finite element equationsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 4 2002F.-H. Lee Abstract This paper examines the performance of the Jacobi preconditioner when used with two Krylov subspace iterative methods. The number of iterations needed for convergence was shown to be different for drained, undrained and consolidation problems, even for similar condition number. The differences were due to differences in the eigenvalue distribution, which cannot be completely described by the condition number alone. For drained problems involving large stiffness ratios between different material zones, ill-conditioning is caused by these large stiffness ratios. Since Jacobi preconditioning operates on degrees-of-freedom, it effectively homogenizes the different spatial sub-domains. The undrained problem, modelled as a nearly incompressible problem, is much more resistant to Jacobi preconditioning, because its ill-conditioning arises from the large stiffness ratios between volumetric and distortional deformational modes, many of which involve the similar spatial domains or sub-domains. The consolidation problem has two sets of degrees-of-freedom, namely displacement and pore pressure. Some of the eigenvalues are displacement dominated whereas others are excess pore pressure dominated. Jacobi preconditioning compresses the displacement-dominated eigenvalues in a similar manner as the drained problem, but pore-pressure-dominated eigenvalues are often over-scaled. Convergence can be accelerated if this over-scaling is recognized and corrected for. Copyright © 2002 John Wiley & Sons, Ltd. [source] The spatial and temporal behaviour of the lower stratospheric temperature over the Southern Hemisphere: the MSU view.INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2001Part I: data, methodology, temporal behaviour Abstract The lower stratosphere monthly temperature anomalies over the Southern Hemisphere derived from soundings made by the Microwave Sounding Unit (MSU) between 1979 and 1997 are analysed. Specifically MSU channel 4 temperature retrievals are considered. Principal component (PC) analysis with the S-mode approach is used in order to isolate grid points that covary in a similar manner and to determine the main features of their temporal behaviour. The first six PCs explain 81.3% of the variance and represent the different time variability patterns observed over the Southern Hemisphere for the ten area clusters determined by the method. The most important feature is common to all the PC score pattern,time series and corresponds to a negative linear trend present in almost all the Southern Hemisphere except over New Zealand and surrounding areas. The negative trend is largest over Antarctica. The remaining features of the temporal variability are different for each PC score and therefore for each cluster region over the Southern Hemisphere. The first PC score pattern shows the impact of the Chichón and Mt Pinatubo eruptions that each produced a 2-year warming over the tropical and sub-tropical lower stratosphere. This variability is orthogonal with the behaviour present over Antarctica. There are different anomalies between 1987 (El Niño) and 1988 (La Niña). This second PC does not show any evidence whatsoever of the volcanic eruptions. The semi-annual wave is present in the anomaly recurrence at mid to high latitudes. Over very low latitudes, close to the Equator, the Quasi-Biennial Oscillation (QBO) band of frequency is also present. Copyright © 2001 Royal Meteorological Society [source] Effect of physico-chemical and molecular mobility parameters on Staphylococcus aureus growthINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2003Elena Vittadini Summary The role played by water activity, ,mobility' and physico-chemical properties of the media in modulating microbial response has been the object of large debate in the scientific community. In this study, Staphylococcus aureus growth parameters (lag phase and cell density at 24 h) in brain heart infusion (BHI) and BHI:NaCl (1:1) were analysed in their correlation with physico-chemical/mobility parameters descriptive of the media [solid content, aw, kinematic viscosity, 17O NMR (R2, Pbw and )]. In these high moisture content, liquid and ,homogeneous' media S.aureus growth related to all the physico-chemical and molecular mobility parameters analysed in a similar manner and it was found to be influenced more significantly by added NaCl than by the physico-chemical and molecular mobility of the media. Staphylococcus aureus growth parameters correlated better with aw (relatively independent of NaCl concentration) than with any other parameter considered in this study. [source] The end of public housing as we know it: public housing policy, labor regulation and the US cityINTERNATIONAL JOURNAL OF URBAN AND REGIONAL RESEARCH, Issue 1 2003Jeff R. Crump In this article I argue that the US public housing policy, as codified by the Quality Housing and Work Responsibility Act of 1998 (QHWRA), is helping to reconfigure the racial and class structure of many inner cities. By promoting the demolition of public housing projects and replacement with mixed-income housing developments, public housing policy is producing a gentrified inner-city landscape designed to attract middle and upper-class people back to the inner city. The goals of public housing policy are also broadly consonant with those of welfare reform wherein the ,workfare' system helps to bolster and produce the emergence of contingent low-wage urban labor markets. In a similar manner, I argue that public housing demonstration programs, such as the ,Welfare-to-Work' initiative, encourage public housing residents to join the lowwage labor market. Although the rhetoric surrounding the demolition of public housing emphasizes the economic opportunities made available by residential mobility, I argue that former public housing residents are simply being relocated into private housing within urban ghettos. Such a spatial fix to the problems of unemployment and poverty will not solve the problems of inner-city poverty. Will it take another round of urban riots before we seriously address the legacy of racism and discrimination that has shaped the US city? Cet article démontre que la politique du logement public américaine, telle que la réglemente la Loi de 1998, Quality Housing and Work Responsibility Act, contribue à remodeler la structure par races et classes de nombreux quartiers déshérités des centres-villes. En favorisant la démolition d'ensembles de logements sociaux et leur remplacement par des complexes urbanisés à loyers variés, la politique publique génère un embourgeoisement des centres-villes destinéà y ramener les classes moyennes et supérieures. Les objectifs de la politique du logement rejoignent largement ceux de la réforme sociale où le système de ,l'allocation conditionnelle' facilite et nourrit la création de marchés contingents du travail à bas salaires. De même, les programmes expérimentaux de logements publics, telle l'initiative Welfare-to-Work (De l'aide sociale au travail) poussent les habitants des logements sociaux à rejoindre le marchéde la main d',uvre à bas salaires. Bien que les discours autour de la démolition des logements sociaux mettent en avant les ouvertures économiques créées par la mobilité résidentielle, leurs anciens habitants sont simplement en train d'être déplacés vers des logements privés situés dans des ghettos urbains. Ce genre de solution spatiale aux problèmes du chômage et de la pauvreté ne viendra pas à bout du dénuement des quartiers déshérités du centre. Faudra-t-il une autre série d'émeutes urbaines pour que l'on aborde sérieusement l'héritage de racisme et de discrimination qui a façonné les villes américaines? [source] Rejoinder: Alex Schwartz's critique of ,The end of public housing as we know it'INTERNATIONAL JOURNAL OF URBAN AND REGIONAL RESEARCH, Issue 1 2003Jeff R. Crump In this article I argue that the US public housing policy, as codified by the Quality Housing and Work Responsibility Act of 1998 (QHWRA), is helping to reconfigure the racial and class structure of many inner cities. By promoting the demolition of public housing projects and replacement with mixed-income housing developments, public housing policy is producing a gentrified inner-city landscape designed to attract middle and upper-class people back to the inner city. The goals of public housing policy are also broadly consonant with those of welfare reform wherein the ,workfare' system helps to bolster and produce the emergence of contingent low-wage urban labor markets. In a similar manner, I argue that public housing demonstration programs, such as the ,Welfare-to-Work' initiative, encourage public housing residents to join the lowwage labor market. Although the rhetoric surrounding the demolition of public housing emphasizes the economic opportunities made available by residential mobility, I argue that former public housing residents are simply being relocated into private housing within urban ghettos. Such a spatial fix to the problems of unemployment and poverty will not solve the problems of inner-city poverty. Will it take another round of urban riots before we seriously address the legacy of racism and discrimination that has shaped the US city? Cet article démontre que la politique du logement public américaine, telle que la réglemente la Loi de 1998, Quality Housing and Work Responsibility Act, contribue à remodeler la structure par races et classes de nombreux quartiers déshérités des centres-villes. En favorisant la démolition d'ensembles de logements sociaux et leur remplacement par des complexes urbanisés à loyers variés, la politique publique génère un embourgeoisement des centres-villes destinéà y ramener les classes moyennes et supérieures. Les objectifs de la politique du logement rejoignent largement ceux de la réforme sociale oú le système de ,l'allocation conditionnelle' facilite et nourrit la création de marchés contingents du travail à bas salaires. De même, les programmes expérimentaux de logements publics, telle l'initiative Welfare-to-Work (De l'aide sociale au travail) poussent les habitants des logements sociaux à rejoindre le marchéde la main d',uvre à bas salaires. Bien que les discours autour de la démolition des logements sociaux mettent en avant les ouvertures économiques créées par la mobilité résidentielle, leurs anciens habitants sont simplement en train d'être déplacés vers des logements privés situés dans des ghettos urbains. Ce genre de solution spatiale aux problèmes du chômage et de la pauvreté ne viendra pas à bout du dénuement des quartiers déshérités du centre. Faudra-t-il une autre série d'émeutes urbaines pour que l'on aborde sérieusement l'héritage de racisme et de discrimination qui a façonné les villes américaines? [source] The Persistence and Pricing of the Cash Component of EarningsJOURNAL OF ACCOUNTING RESEARCH, Issue 3 2008PATRICIA M. DECHOW ABSTRACT Prior research shows that the cash component of earnings is more persistent than the accrual component. We decompose the cash component into: (1) the change in the cash balance, (2) issuances/distributions to debt, and (3) issuances/distributions to equity. We find that the higher persistence of the cash component is entirely due to the subcomponent related to equity. The other subcomponents have persistence levels almost identical to accruals. We investigate whether investors understand the implications of the differential persistence of the three subcomponents. Our results suggest that investors correctly price debt and equity issuances/distributions but misprice the change in the cash balance in a similar manner to accruals. Our tests enable us to empirically distinguish the "accrual" and "external financing" anomalies with results implying that the accrual anomaly subsumes the external financing anomaly. Our results also suggest that naive fixation on earnings is unlikely to be a complete explanation for the accrual anomaly. Our findings are more consistent with investors misunderstanding diminishing returns to new investments. [source] Herbivore-induced plant volatiles as cues for habitat assessment by a foraging parasitoidJOURNAL OF ANIMAL ECOLOGY, Issue 1 2007CEDRIC TENTELIER Summary 1Animals usually require information about the current state of their habitat to optimize their behaviour. For this, they can use a learning process through which their estimate is continually updated according to the cues they perceive. Identifying these cues is a long-standing but still inveterate challenge for ecologists. 2The use of plant cues by aphid parasitoids for the assessment of habitat profitability and the adaptation of patch exploitation was studied. Grounding on predictions from optimal foraging theory, we tested whether parasitoids exploited host patches less intensively after visiting heavily infested plants than after visiting plants bearing fewer aphids. 3As predicted, after visiting heavily infested plants parasitoids reduced their residence time and attacked fewer hosts in the next patch. This was the case regardless of whether the aphids were actually present on the first plant, indicating that the cue came from the plant. Moreover, the level of infestation of a plant at some distance from the first plant visited affected parasitoid patch exploitation on the second plant in a similar manner, indicating that the cue was volatile. 4These results highlight a novel role of herbivore-induced volatiles in parasitoid foraging behaviour, different from the widely studied attraction at a distance. [source] Influence of phenolic acids on growth and inactivation of Oenococcus oeni and Lactobacillus hilgardiiJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2003F.M. Campos Abstract Aims: To determine the effect of several wine-associated, phenolic acids on the growth and viability of strains of Oenococcus oeni and Lactobacillus hilgardii. Methods and Results: Growth was monitored in ethanol-containing medium supplemented with varying concentrations of hydroxybenzoic acids (p -hydroxybenzoic, protocatechuic, gallic, vanillic and syringic acids) and hydroxycinnamic acids (p -coumaric, caffeic and ferulic acids). Progressive inactivation was monitored in ethanol-containing phosphate buffer supplemented in a similar manner to the growth experiments. Hydroxycinnamic acids proved to be more inhibitory to the growth of O. oeni than hydroxybenzoic acids. On the other hand, some acids showed a beneficial effect on growth of Lact. hilgardii. p- Coumaric acid showed the strongest inhibitory effect on growth and survival of both bacteria. Conclusions: Most phenolic acids had a negative effect on growth of O. oeni, for Lact. hilgardii this effect was only noted for p- coumaric acid. Generally, O. oeni was more sensitive to phenolic acid inactivation than Lact. hilgardii. Significance and Impact of the Study: Eight wine-derived, phenolic acids were compared for their effects on wine lactic acid bacteria. Results indicate that phenolic acids have the capacity to influence growth and survival parameters. The differences found between phenolic compounds could be related to their different chemical structures. [source] | ||||||||||||||||||||||||||||||||||||||||||||||