bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain of environment explains variation in the strength of genotype × environment interaction
Authors: Rodríguez R. L.
Published: July 2012

Theory predicts that genetic variation in phenotypic plasticity (genotype × environment interaction or G × E) should be eroded by selection acting across environments. However, it appears that G × E is often maintained under selection, although not universally. This variation in the presence and strength of G × E requires explanation. Here I ask whether the explanation may lie in the grain of the environment at which G × E is expressed. The grain (or grain size) of the environment refers to the scale of environmental heterogeneity relative to generation time – that is, relative to the window of operation of selection – with higher rates of heterogeneity occurring in finer‐grained environments. The hypothesis that the grain of the environment explains variation in the expression of G × E encapsulates variation in the power of selection to shape reaction norms: selection should be able to erode G × E in fine‐grained environments but lose its power as the grain becomes coarser. I survey studies of G × E in sexual traits and demonstrate that the strength of G × E varies with the grain of the environment across which it is expressed, with G × E being stronger in coarser‐grained environments. This result elucidates when G × E is most likely to be sustained in the reaction norms of fitness‐related traits and when its evolutionary consequences will be most pronounced.
Expression of Concern: High glucose facilitates cell cycle arrest of rat bone marrow multipotent adult progenitor cells through transforming growth factor‐β1 and extracellular signal‐regulated kinase 1/2 signalling without changing Oct4 expression
Authors: Luo Min , Liu Zehao , Hao Hong , Lu Tiewei , Chen Minjie , Lei Minxiang , Verfaillie Catherine M , Liu Zhenguo
Published: July 2012

The transcription factor Oct4 is critical to the pluripotency, self‐renewal and differentiation of stem cells. The aim of the present study was to investigate the effects of high glucose (HG) on the cell cycle progression of bone marrow multipotent adult progenitor cells (MAPC) and Oct4 expression, as well as the underlying mechanisms.

Rat MAPC were cultured in normal (5.5 mmol/L d‐glucose) and HG (25.5 mmol/L d‐glucose) media for up to 14 days. l‐Glucose served as a high osmolarity control. Culture in HG media substantially increased the number of cells in the G0/G1 phase and decreased the number in the S phase without changing the cell population in the G2 phase. Expression of the cell cycle regulatory protein p21CIP/WAF‐1 (p21), but not that of p27KIP‐1 (p27), was significantly upregulated in cells cultured in HG media. Significant increases were seen in transforming growth factor (TGF)‐β1 levels in cells and MAPC‐conditioned medium in the presence of HG, and extracellular signal‐regulated kinase (ERK) 1/2 phosphorylation was enhanced in cells cultured in the presence of HG medium without any changes in Akt phosphorylation.

Neutralizing TGF‐β1 antibody effectively prevented HG‐induced increases in ERK1/2 phosphorylation, p21 expression and suppression of cell cycle progression of MAPC. Inhibiting ERK1/2 phosphorylation with PD98059 completely blocked HG‐induced p21 expression and markedly reversed HG‐induced inhibition of cell cycle progression in MAPC. The HG‐induced suppression of cell cycle progression was not accompanied by inhibition of cell proliferation or Oct4 expression in these cells.

The data indicate that HG facilitates cell cycle arrest of rat MAPC through TGF‐β1‐induced activation of ERK1/2 signalling and p21 expression, and that Oct4 expression in MAPC is independent of the cell cycle and/or TGF‐β1 or ERK1/2 signalling in HG medium.
Numerical modelling and experimental investigation on welding residual stresses in large‐scale tubular K‐joints
Authors: ACEVEDO C. , DREZET J. M. , NUSSBAUMER A.
Published: July 2012

This paper is devoted to the experimental and numerical assessment of residual stresses created by welding in the region surrounding the weld toe of tubular K‐shaped joints (i.e. region most sensitive to fatigue cracking). Neutron‐diffraction measurements were carried out on K‐joints cut from large‐scale truss beams previously subjected to high cycle fatigue. Tri‐axial residual stresses in the transverse, longitudinal and radial direction were obtained from the weld toe as a function of the depth in the thickness of the tube wall. In addition, thermomechanical analyses were performed in three‐dimensional using ABAQUS and MORFEO finite element codes. Experimental and numerical results show that, at and near the weld‐toe surface, the highest residual stresses are critically oriented perpendicularly to the weld direction, and combined with the highest externally applied stresses. Based on a systematic study on geometric parameters, analytical residual stress distribution equations with depth are proposed.
Culturing captures members of the soil rare biosphere
Authors: Shade Ashley , Hogan Clifford S. , Klimowicz Amy K. , Linske Matthew , McManus Patricia S. , Handelsman Jo
Published: July 2012

The ecological significance of rare microorganisms within microbial communities remains an important, unanswered question. Microorganisms of extremely low abundance (the ‘rare biosphere’) are believed to be largely inaccessible and unknown. To understand the structure of complex environmental microbial communities, including the representation of rare and prevalent community members, we coupled traditional cultivation with pyrosequencing. We compared cultured and uncultured bacterial members of the same agricultural soil, including eight locations within one apple orchard and four time points. Our analysis revealed that soil bacteria captured by culturing were in very low abundance or absent in the culture‐independent community, demonstrating unexpected accessibility of the rare biosphere by culturing.
An extensive investigation into the prevalence and the genetic and serological diversity of toxigenic Vibrio parahaemolyticus in Italian marine coastal waters
Authors: Ottaviani D. , Leoni F. , Rocchegiani E. , Mioni R. , Costa A. , Virgilio S. , Serracca L. , Bove D. , Canonico C. , Di Cesare A. , Masini L. , Potenziani S. , Caburlotto G. , Ghidini V. , Lleo M. M.
Published: July 2012

The relationship between Vibrio parahaemolyticus strains isolated from the aquatic environment and those isolated from cases of infection in humans is poorly understood due to the low prevalence of tdh‐ and/or trh‐positive strains in the environment. To address this concern, it would be useful to analyse the genetic relationships among environmental and food strains and with reference to clinical isolates, also applying molecular typing methods. The aim of this study was to evaluate the prevalence of toxigenic V. parahaemolyticus in Italian coastal waters and seafood, to examine intra‐species variability and to identify, using serotyping and pulsed‐field gel electrophoresis (PFGE), relationships among strains from different sources, geographical origin and period of isolation. Of the 192 V. parahaemolyticus strains isolated in different Italian areas and examined in this study, 25 (13.0%) proved to carry the trh gene while none of the strains proved positive to the search by PCR for tdh and Group‐Specific‐toxRS genes. The prevalence of toxigenic strains in the Tyrrhenian Sea was significantly lower than that calculated for the Ligurian coasts. Regarding the sources of isolation, the higher prevalence of trh‐positive V. parahaemolyticus was revealed in fish, followed by clams, plankton, oysters, mussels and lastly seawater. Within the toxigenic strains, 16 serotypes and 20 distinct PFGE patterns were identified. Two clusters, which included a total of 8 V. parahaemolyticus strains, were specifically associated with the North Adriatic Sea area and were stable over time. Our results demonstrate that trh‐positive V. parahaemolyticus strains circulated in Italy in the period 2002–2009 with a prevalence higher than that reported from other European and extra‐European countries, confirming that toxigenic V. parahaemolyticus is an emerging public health concern in Italy, regardless of its pandemic potential.
Accurate preoperative prediction of non‐organ‐confined bladder urothelial carcinoma at cystectomy
Authors: Green David A. , Rink Michael , Hansen Jens , Cha Eugene K. , Robinson Brian , Tian Zhe , Chun Felix K. , Tagawa Scott , Karakiewicz Pierre I. , Fisch Margit , Scherr Douglas S. , Shariat Shahrokh F.
Published: July 2012

What's known on the subject? and What does the study add?

Upstaging to non‐organ‐confined (NOC) disease is frequent at the time of radical cystectomy for urothelial carcinoma of the bladder (UCB). Pre‐surgical models that can accurately predict which patients are likely to have more extensive disease are sparse.

The present study developed an accurate nomogram for the prediction of NOC‐UCB based on a cohort of patients with clinically organ‐confined disease. Adoption of such a tool into daily clinical decision‐making may lead to more appropriate integration of perioperative chemotherapy, thereby potentially improving survival in patients with UCB.

Objective

To create an accurate pre‐cystectomy decision‐making tool that allows for the accurate identification of patients with clinically organ‐confined urothelial carcinoma of the bladder (UCB) who have non‐organ‐confined UCB (NOC‐UCB) at cystectomy, as identification of patients with UCB most likely to benefit from neoadjuvant chemotherapy (NACTx) is hampered by inaccurate clinical staging.

Patients and Methods

A prospectively maintained single‐institution database containing 201 patients who underwent cystectomy and pelvic lymph node (LN) dissection without NACTx for UCB was analysed.

Predictive variables for NOC‐UCB included, among others, age, gender, transurethral resection of bladder tumour (TURBT) findings (stage, grade, histology, size, presence of carcinoma in situ, lymphovascular invasion [LVI], multifocality), history of intravesical therapy, time from TURBT to cystectomy, and cross‐sectional imaging findings.

Results

Clinical stage distribution was 19 patients with Ta, 15 with Tis, 67 with T1, and 100 with T2.

At the time of cystectomy, NOC‐UCB and LN‐positive disease were found in 71 (35%) and 38 (19%) of patients, respectively; 81 (40%) of patients had NOC‐UCB (≥pT3/Nany or pTany/N+).

Tumour stage (P [trend] <0.001), presence of LVI (odds ratio [OR] 5.2; P = 0.02), and radiographic evidence of NOC‐UCB or hydronephrosis (OR 3.2; P = 0.01) were independently associated with ≥pT3 Nany UCB.

Tumour stage (P [trend] < 0.001) and presence of LVI (OR 6.64; P = 0.01) were independently associated with (≥pT3/Nany or pTany/N+) UCB.

A nomogram to predict (≥pT3/Nany or pTany/N+) based on all three variables was highly accurate (area under the curve 0.828) and well calibrated, deviating <8% from ideal prediction. Decision curve analysis showed net benefit across all threshold probabilities.

Conclusions

NOC‐UCB can be predicted with high accuracy by integrating standard clinicopathological factors with imaging information.

This model may help to identify patients with NOC‐UCB who may benefit from NACTx.
The Multiple Subfunctions of Attention: Differential Developmental Gateways to Literacy and Numeracy
Authors: Steele Ann , Karmiloff‐Smith Annette , Cornish Kim , Scerif Gaia
Published: July 2012

Attention is construed as multicomponential, but the roles of its distinct subfunctions in shaping the broader developing cognitive landscape are poorly understood. The current study assessed 3‐ to 6‐year‐olds (N = 83) to: (a) trace developmental trajectories of attentional processes and their structure in early childhood and (b) measure the impact of distinct attention subfunctions on concurrent and longitudinal abilities related to literacy and numeracy. Distinct trajectories across attention measures revealed the emergence of 2 attentional factors, encompassing “executive” and “sustained–selective” processes. Executive attention predicted concurrent abilities across domains at Time 1, whereas sustained–selective attention predicted basic numeracy 1 year later. These concurrent and longitudinal constraints cast a broader light on the unfolding relations between domain‐general and domain‐specific processes over early childhood.
From Privatised to Hybrid Corporatised Higher Education: A Global Financial Management Discourse
Authors: Parker Lee D.
Published: July 2012

Abstract:  This study addresses the emerging financial management focus of publicly and privately funded universities in the global marketplace, focusing on their financial management strategies. Despite regional and national differences, both public and private universities are found to exhibit a global trend towards operating as predominantly market funded commercial organisations. In many countries this reflects the insinuation of New Public Management philosophies into university missions and strategies. University objectives show signs of serving an underlying financial imperative often driven by constrained government funding of higher education and the expansion of private higher education institutions. Revenue expansion through mass education and engagement in the education export trade emerge as primary financial management strategies for a self‐generating profit oriented business model of higher education.
Guaranteeing Healthcare: What Does the Care Guarantee Do?
Authors: Nordgren Lars
Published: July 2012

Abstract:  According to the Swedish Health and Medical Services Act, healthcare is to be provided to the population according to need and on equal terms. It must also be accessible – a part of healthcare that has been criticized. In an effort to improve accessibility, the Swedish Association of Local Authorities and Regions and the government have both agreed to introduce a national care guarantee with effect from 01‐11‐2005. On 01‐07‐2010, the guarantee was incorporated into the Health and Medical Services Act. This paper considers, using the ideas of Foucault (discursive formation), Butler and Callon (performativity), how the idea of a care guarantee came to be influential during the formulation of Sweden's healthcare policies and on the management of services in hospitals. The concept of performativity is used to illustrate how the care guarantee becomes binding on the county council, as a promise to the patient.
The emergence of squirrelpox in Ireland
Authors: McInnes C. J. , Coulter L. , Dagleish M. P. , Deane D. , Gilray J. , Percival A. , Willoughby K. , Scantlebury M. , Marks N. , Graham D. , Everest D. J. , McGoldrick M. , Rochford J. , McKay F. , Sainsbury A. W.
Published: July 2012

The native red squirrel Sciurus vulgaris population in Britain has been on the decline for many years. A poxvirus associated with the introduced American grey squirrel S. carolinensis has been recognized as having a major role in the reduction of red squirrel numbers by causing a deleterious disease, known as squirrelpox, from which they seldom recover. In Ireland, red squirrel numbers have also been reducing while the grey squirrel population, first introduced in 1911, has been expanding. Until now, no poxvirus‐associated disease had been found in Irish red squirrels and therefore, the role of squirrelpox in the displacement of red squirrels by grey squirrels in Ireland has been questioned. Here we report, for the first time, confirmed squirrelpox disease in two populations of red squirrels in Northern Ireland. In addition, we present serological evidence of the extent of poxvirus infection in the grey squirrels from both the Republic of Ireland and Northern Ireland, including an apparent increase in the seroprevalence of antibodies against the virus in grey squirrels over the period of the study, and discuss the implications of our findings for the conservation tactics employed to protect red squirrels.
Quantitative genetics of basal metabolic rate and body mass in free‐living pied flycatchers
Authors: Bushuev A. V. , Husby A. , Sternberg H. , Grinkov V. G.
Published: July 2012

Despite basal metabolic rate (BMR) being one of the most commonly measured physiological traits and an important indicator of competitive ability, very little is known about its genetic basis and relation to other physiological traits. Here, we present the first attempt to estimate the multivariate basis of BMR using a natural population of pied flycatcher Ficedula hypoleuca breeding in the Tomsk Region, Western Siberia. We show relatively high and significant heritability of whole‐organism BMR, mass‐specific BMR and mass‐independent BMR (h
2 = 0.43, 0.55 and 0.52, respectively), which indicates the potential of these energetic traits to respond to direct selection. In contrast to some previous reports, we found that the genetic correlations between body mass and all three measures of BMR were not significantly different from zero. Independent evolution of body mass and BMR in this species should therefore be possible. Following a previous report, we also estimated the genetic correlations between the different BMR measures and show they are all close to unity, suggesting that they are, from a genetic point of view, a similar trait. Our results are in contrast with previous studies measuring the genetic basis of metabolic rates using aviary‐bred birds and highlight the importance of considering BMR in a natural setting.
Global perspective on early diagnosis and intervention for children with developmental delays and disabilities
Authors: SCHERZER ALFRED L , CHHAGAN MEERA , KAUCHALI SHUAIB , SUSSER EZRA
Published: July 2012

Low‐ and middle‐income countries are experiencing a significant reduction in mortality of children under 5 years of age. This reduction is bringing in its wake large numbers of surviving children with developmental delays and disabilities. Very little attention has been paid to these children, most of whom receive minimal or no support. Thus, there is an urgent need to recognize that improving the quality of life of the survivors must complement mortality reduction in healthcare practice and programs. The incorporation of early evaluation and intervention programs into routine pediatric care is likely to have the most impact on the quality of life of these children. We therefore call for leadership from practitioners, governments, and international organizations to prioritize regular childhood developmental surveillance for possible delays and disabilities, and to pursue early referral for intervention.
Natural history of pyridoxine‐dependent epilepsy: tools for prognostication
Authors: GOSPE SIDNEY M
Published: July 2012

This commentary is on the original article by Bok et al. on pages 849‐854 of this issue.
Neurodevelopmental disorders in low‐ and middle‐income countries
Authors: NEWTON CHARLES R
Published: July 2012

This commentary is on the review by Scherzer et al. on pages 1079–1084 of this issue.
Proteomic analysis of mouse brain cortex identifies metabolic down‐regulation as a general feature of ischemic pre‐conditioning
Authors: Scornavacca Giacomo , Gesuete Raffaella , Orsini Franca , Pastorelli Roberta , Fanelli Roberto , de Simoni Maria‐Grazia , Airoldi Luisa
Published: July 2012

J. Neurochem. (2012) 122, 1219–1229.

The molecular mechanisms that lead to ischemic pre‐conditioning are not completely understood, and proteins are important players. We compared the mouse brain cortex proteome from different ischemia sets: transient (7 min) middle cerebral artery occlusion (7′MCAo, pre‐conditioning stimulus), permanent MCAo (pMCAo, severe ischemia), and pMCAo 4 days after 7′MCAo (7′MCAo/pMCAo, pre‐conditioned model). Proteins were analyzed by two‐dimensional electrophoresis coupled to liquid chromatography–tandem mass spectrometry. Overall, 28 proteins were expressed differentially from sham controls, and identified. The ischemic pre‐conditioning stimulus alone up‐regulated the stress protein heat‐shock protein 70 (HSP70), possibly activated by the androgen receptor. Western blotting confirmed the increased expression of HSP70 and showed that androgen receptor expression paralleled that of HSP70. In the ischemic‐tolerant group (7′MCAo/pMCAo), a number of proteins over‐expressed after pMCAo returned to sham levels, seven proteins remained up‐regulated as in pMCAo, and five proteins mainly involved in energy metabolism and mitochondrial electron transport and unchanged in pMCAo were down‐regulated only in ischemic tolerance, suggesting a role in brain pre‐conditioning. Astrocytes participated in ischemic‐tolerance induction, as shown by the down‐regulation of glutamine synthetase in the 7′MCAo/pMCAo group. The results suggest that metabolic down‐regulation was a general feature of ischemic pre‐conditioning, playing a pivotal role in neuroprotection.
A new model of autism spectrum disorder assessment and diagnosis by multiagency community‐based teams in primary schools
Authors: Simpson Wendy , Brown Carolyn , Nisbet Nara , Metcalfe Ruth , Claisse Zoe , Watson Lorna
Published: July 2012

Background

National guidelines stress the importance of early diagnosis of autism spectrum disorder (ASD). This pilot investigated the feasibility and acceptability of assessing children in their community.

Method

The pilot study was carried out from August 2007 to January 2009, and the roll‐out of the programme started in 2010 and is currently underway. Workers undertook assessments and made a group decision about diagnosis; participant observation of these team meetings explored the decision‐making process. Semistructured interviews and focus groups explored the views of parents and professionals.

Results

Seventeen children took part in the study: six were diagnosed with ASD; three as not ASD, and eight were referred for further assessment. The model was found acceptable to parents and workers.

Conclusions

With detailed consideration of administration, information, communication and training requirements, this approach has the potential to increase early diagnosis of ASD and reduce demand for specialist assessment.
Are U.S. Multinational Corporations Becoming More Aggressive Income Shifters?
Authors: KLASSEN KENNETH J. , LAPLANTE STACIE K.
Published: July 2012

This paper examines income shifting of U.S. multinational companies over the past two decades. Domestic and foreign policy makers are increasingly concerned with the effect of income shifting on dwindling tax revenues, however, extant research on income shifting by U.S. multinational enterprises is mixed. We address the disconnect between the academic literature and the policy maker's perceptions by examining the extent of multijurisdictional income shifting by U.S. multinational companies. We directly address conflicting results in extant literature and show that using either multiperiod proxies or instrumental variables overcomes weaknesses of annual proxies in this setting. Our tests show that U.S. companies have become more active at shifting income out of the United States as the regulatory costs of shifting have changed. Holding tax rate differences between U.S. and foreign jurisdictions constant, our empirical estimates suggest that our sample of 380 corporations with low average foreign tax rates collectively shifts approximately $10 billion of additional income out of the United States annually during 2005–2009 relative to 1998–2002 due to varying regulatory costs of shifting.
The Information Content of Tax Expense for Firms Reporting Losses
Authors: DHALIWAL DAN S. , KAPLAN STEVEN E. , LAUX RICK C. , WEISBROD ERIC
Published: July 2012

We investigate whether management's decision regarding the recognition of the valuation allowance (VA) for deferred tax assets provides incremental information about the persistence of accounting losses. We introduce a classification scheme that assigns loss firm‐years into three categories based on whether management appears to have recognized a material change in the VA, and whether or not the firm has positive taxable income (e.g., a net operating loss). The results of our study show that our tax categories contain information about the persistence of accounting losses over the following three years beyond variables previously identified to predict loss persistence. This incremental information is consistent with management using private information about the firm's future prospects in setting the VA. Finally, we find that investors’ pricing of the VA varies with the saliency of the tax signal and the information environment of the firm.
Biofeedback Therapy for Pediatric Headache: Factors Associated With Response
Authors: Blume Heidi K. , Brockman Libby N. , Breuner Cora C.
Published: July 2012

Objectives.— The goal of this study was to measure the effect of biofeedback therapy on pediatric headache and to identify factors associated with response to biofeedback therapy.

Background.— In the United States, 17% of children have frequent or severe headaches. Biofeedback therapy (BFT) appears to be an effective treatment for headaches in adults and is often recommended for children with headaches, but there are few data in the pediatric population. It is also not clear which patients are most likely to benefit from biofeedback therapy.

Methods.— We examined the records of patients, aged 8 to 18 years old, who were referred to a pediatric BFT clinic for management of headache between 2004 and 2008. We extracted data regarding patient and headache characteristics, medication use, family history, and measures of depression, anxiety, and somatization. Chronic headache was defined as ≥4 headache days/week. Positive response to biofeedback was defined as a 50% reduction in number of headache days/week or hours/week, or ≥3‐point decrease in severity (0‐10 scale) between first and last visits. We analyzed the responder rate for those with episodic and chronic headaches and performed multivariable analysis to determine what factors were associated with headache response to biofeedback therapy.

Results.— We analyzed records from 132 children who attended ≥2 biofeedback sessions. Median headache frequency dropped from 3.5 to 2 headache days/week between the first and last visits. The response rate was 58% overall; 48% for chronic headaches and 73% episodic headaches. In multivariate analysis, ability to raise hand temperature by >3°F at the last visit and use of selective serotonin reuptake inhibitors (SSRIs) were associated with a positive response, and preventive medication use was associated with nonresponse. Anxiety, depression, and somatization were not significantly associated with response to biofeedback therapy.

Conclusions.— Biofeedback therapy appears to be an effective treatment for children and adolescents with both episodic and chronic headaches. Further study is warranted to compare biofeedback with other treatments for chronic pediatric headache. Use of SSRIs appears to be associated with a positive response to biofeedback therapy, but the reasons for this relationship are unclear and merit further study.
Multinational assessment of blood‐borne virus testing and transfusion safety on the African continent
Authors: Laperche Syria ,   Francophone African Group for Research in Blood Transfusion
Published: July 2012

BACKGROUND: Failures of blood screening due to low test quality or poor laboratory technique increase the risk of transfusion‐transmitted infections. For this reason, the World Health Organization has recommended a quality control (QC) system for African blood centers.

STUDY DESIGN AND METHODS: We conducted a cross‐sectional research assessment of test performance at 51 blood centers in 17 African countries. A blinded, standardized panel containing 25 samples positive for human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) and negative controls was tested by the centers using their operational infectious disease testing consisting of rapid tests, enzyme immunoassays (EIAs), or antigen‐antibody EIAs. Nucleic acid testing was not performed.

RESULTS: The overall performances of the 42 assays were the lowest for hepatitis B surface antigen (75.6% sensitivity, 94.5% specificity), then for HCV (80.0% sensitivity, 98.1% specificity) and for HIV (81.4% sensitivity, 99.6% specificity). Poor sensitivity was driven by the use of rapid tests, which had sensitivities of 47.4% for HBV, 63.7% for HCV, and 72.4% for HIV. From a blood screening point of view, 321 (5.6%) infected units would have been transfused due to false‐negative results. Assuming that those that were missed by rapid tests (84%) would have been detected by EIAs, 270 viral contaminations (92 HIV, 65 HCV, and 113 HBV) would have been avoided.

CONCLUSION: These results support the discontinuation of rapid tests and implementation of antigen‐antibody EIAs whenever possible in Africa. This successful QC program highlights the need for promoting such periodic external quality assessment studies.
Akt‐ and Erk‐mediated regulation of proliferation and differentiation during PDGFRβ‐induced MSC self‐renewal
Authors: Gharibi Borzo , Ghuman Mandeep S. , Hughes Francis J.
Published: July 2012

Understanding the mechanisms that direct mesenchymal stem cell (MSC) self‐renewal fate decisions is a key to most tissue regenerative approaches. The aim of this study here was to investigate the mechanisms of action of platelet‐derived growth factor receptor β (PDGFRβ) signalling on MSC proliferation and differentiation. MSC were cultured and stimulated with PDGF‐BB together with inhibitors of second messenger pathways. Cell proliferation was assessed using ethynyl‐2′‐deoxyuridine and phosphorylation status of signalling molecules assessed by Western Blots. To assess differentiation potentials, cells were transferred to adipogenic or osteogenic media, and differentiation assessed by expression of differentiation association genes by qRT‐PCR, and by long‐term culture assays. Our results showed that distinct pathways with opposing actions were activated by PDGF. PI3K/Akt signalling was the main contributor to MSC proliferation in response to activation of PDGFRβ. We also demonstrate a negative feedback mechanism between PI3K/Akt and PDGFR‐β expression. In addition, PI3K/Akt downstream signal cascades, mTOR and its associated proteins p70S6K and 4E‐BP1 were involved. These pathways induced the expression of cyclin D1, cyclin D3 and CDK6 to promote cell cycle progression and MSC proliferation. In contrast, activation of Erk by PDGFRβ signalling potently inhibited the adipocytic differentiation of MSCs by blocking PPARγ and CEBPα expression. The data suggest that PDGFRβ‐induced Akt and Erk pathways regulate opposing fate decisions of proliferation and differentiation to promote MSC self‐renewal. Thus, activation of multiple intracellular cascades is required for successful and sustainable MSC self‐renewal strategies.
Neddylation dysfunction in Alzheimer's disease
Authors: Chen Yuzhi , Neve Rachael L. , Liu Helena
Published: July 2012

Ubiquitin‐dependent proteolysis is a major mechanism that downregulates misfolded proteins or those that have finished a programmed task. In the last two decades, neddylation has emerged as a major regulatory pathway for ubiquitination. Central to the neddylation pathway is the amyloid precursor protein (APP)‐binding protein APP‐BP1, which together with Uba3, plays an analogous role to the ubiquitin‐activating enzyme E1 in nedd8 activation. Activated nedd8 covalently modifies and activates a major class of ubiquitin ligases called Cullin‐RING ligases (CRLs). New evidence suggests that neddylation also modifies Type‐1 transmembrane receptors such as APP. Here we review the functions of neddylation and summarize evidence suggesting that dysfunction of neddylation is involved in Alzheimer's disease.
High‐throughput olfactory conditioning and memory retention test show variation in Nasonia parasitic wasps
Authors: Hoedjes K. M. , Steidle J. L. M. , Werren J. H. , Vet L. E. M. , Smid H. M.
Published: July 2012

Most of our knowledge on learning and memory formation results from extensive studies on a small number of animal species. Although features and cellular pathways of learning and memory are highly similar in this diverse group of species, there are also subtle differences. Closely related species of parasitic wasps display substantial variation in memory dynamics and can be instrumental to understanding both the adaptive benefit of and mechanisms underlying this variation. Parasitic wasps of the genus Nasonia offer excellent opportunities for multidisciplinary research on this topic. Genetic and genomic resources available for Nasonia are unrivaled among parasitic wasps, providing tools for genetic dissection of mechanisms that cause differences in learning. This study presents a robust, high‐throughput method for olfactory conditioning of Nasonia using a host encounter as reward. A T‐maze olfactometer facilitates high‐throughput memory retention testing and employs standardized odors of equal detectability, as quantified by electroantennogram recordings. Using this setup, differences in memory retention between Nasonia species were shown. In both Nasonia vitripennis and Nasonia longicornis, memory was observed up to at least 5 days after a single conditioning trial, whereas Nasonia giraulti lost its memory after 2 days. This difference in learning may be an adaptation to species‐specific differences in ecological factors, for example, host preference. The high‐throughput methods for conditioning and memory retention testing are essential tools to study both ultimate and proximate factors that cause variation in learning and memory formation in Nasonia and other parasitic wasp species.
Equilibrium binding and kinetic characterization of putative tetracycline repressor family transcription regulator Fad35R from Mycobacterium tuberculosis
Authors: Anand Sushma , Singh Vijay , Singh Appu Kumar , Mittal Monica , Datt Manish , Subramani Bala , Kumaran Sangaralingam
Published: July 2012

Fatty acids play critical role in the survival and virulence of Mycobacterium tuberculosis (Mtb). Activation of fatty acids by acyl‐CoA synthetases (Fad) into fatty acyl‐CoA is the first and one of the crucial steps in fatty acid metabolism. Mtb possesses 36 fatty acyl‐CoA synthetases, unlike Escherichia coli, which has single enzyme. However, the mechanisms by which the expression of these multiple Fad genes is regulated remain uncharacterized. We characterized the DNA‐ and ligand‐binding properties of a putative tetracycline repressor family regulator, named Fad35R, located upstream of the Fad35 gene and ScoA‐citE operon. We identified a palindromic regulatory motif upstream of Fad35 and characterized the binding of Fad35R to this motif. Equilibrium binding studies show that Fad35R binds to this motif with high affinity (Kd∼ 0.033 μm) and the specificity of binding was confirmed by an electromobility gel shift assay. Kinetic studies indicate that faster association (ka,avg∼ 5.4 × 104 m−1·s−1) and slower dissociation rates (kd,avg∼ 5.84 × 10−4 s−1) confer higher affinity. The affinity for the promoter is maximum at 300 mm NaCl but decreases rapidly beyond this range. Ligand‐binding studies indicate that Fad35R binds specifically to tetracycline and also binds to fatty acid derivatives. The promoter‐binding affinity is decreased significantly in the presence of palmityl‐CoA, suggesting that Fad35R can sense the levels of activated fatty acids and alter its DNA‐binding activity. Our results suggest that Fad35R may be the functional homologue of FadR and controls the expression of genes in a metabolite‐dependent manner.

Structured digital abstract 

Fad35R binds to palindromic sequence shown by surface plasmon resonance

Fad35R binds to tetracycline and activated fatty acids as shown by fluorescence spectroscopy
N‐linked glycosylation of dimeric acetylcholinesterase in erythrocytes is essential for enzyme maturation and membrane targeting
Authors: Luk Wilson K. W. , Chen Vicky P. , Choi Roy C. Y. , Tsim Karl W. K.
Published: July 2012

Acetylcholinesterase (AChE) is well‐known for its cholinergic functions in the nervous system; however, this enzyme is also found in other tissues where its function is still not understood. AChE is synthesized through alternative splicing as splicing variants, with isoforms including read‐through (AChER), tailed (AChET) and hydrophobic (AChEH). In human erythrocytes, AChEH is a glycophosphatidylinositol‐linked dimer on the plasma membrane. Three N‐linked glycosylation sites have been identified in the catalytic domain of human AChE. Here, we investigate the roles of glycosylation in assembly and trafficking of human AChEH. In transfected fibroblasts, expression of AChEH was able to mimic the function of the dimeric form of AChE on the erythrocyte membrane. A glycan‐depleted form was constructed by site‐directed mutagenesis. By comparison with the wild‐type AChEH, the mutant had a much lower enzymatic activity and a much higher Km value. In addition, the mutant was dimerized in the endoplasmic reticulum, but was not trafficked to the Golgi apparatus. The results suggest that the glycosylation may affect AChEH enzymatic activity and trafficking, but not dimer formation. The present findings indicate the significance of N‐glycosylation in controlling the biosynthesis of the AChEH dimer form.

Structured digital abstract

 AChE‐H and GM130 colocalize by cosedimentation through density gradient (View interaction)

 AChE‐H and Calnexin colocalize by cosedimentation through density gradient (View interaction)
Influence of Seasonal Variations in Soil Water Availability on Gas Exchange of Tropical Canopy Trees
Authors: Stahl Clément , Burban Benoit , Wagner Fabien , Goret Jean‐Yves , Bompy Félix , Bonal Damien
Published: July 2012

Seasonal variations in environmental conditions influence the functioning of the whole ecosystem of tropical rain forests, but as yet little is known about how such variations directly influence the leaf gas exchange and transpiration of individual canopy tree species. We examined the influence of seasonal variations in relative extractable water in the upper soil layers on predawn leaf water potential, saturated net photosynthesis, leaf dark respiration, stomatal conductance, and tree transpiration of 13 tropical rain forest canopy trees (eight species) over 2 yr in French Guiana. The canopies were accessed by climbing ropes attached to the trees and to a tower. Our results indicate that a small proportion of the studied trees were unaffected by soil water depletion during seasonal dry periods, probably thanks to efficient deep root systems. The trees showing decreased tree water status (i.e., predawn leaf water potential) displayed a wide range of leaf gas exchange responses. Some trees strongly regulated photosynthesis and transpiration when relative extractable water decreased drastically. In contrast, other trees showed little variation, thus indicating good adaptation to soil drought conditions. These results have important applications to modeling approaches: indeed, precise evaluation and grouping of these response patterns are required before any tree‐based functional models can efficiently describe the response of tropical rain forest ecosystems to future changes in environmental conditions.
Purinergic signalling – a possible mechanism for KCNQ1 channel response to cell volume challenges
Authors: Hammami S. , Willumsen N. J. , Meinild A.‐K. , Klaerke D. A. , Novak I.
Published: July 2012

Aim

A number of K+ channels are regulated by small, fast changes in cell volume. The mechanisms underlying cell volume sensitivity are not known, but one possible mechanism could be purinergic signalling. Volume activated ATP release could trigger signalling pathways that subsequently lead to ion channel stimulation and cell volume back‐regulation. Our aim was to investigate whether volume sensitivity of the voltage‐gated K+ channel, KCNQ1, is dependent on ATP release and regulation by purinergic signalling.

Methods

We used Xenopus oocytes heterologously expressing human KCNQ1, KCNE1, water channels (AQP1) and P2Y2 receptors. ATP release was monitored by a luciferin–luciferase assay and ion channel conductance was recorded by two‐electrode voltage clamp.

Results

The luminescence assay showed that oocytes released ATP in response to mechanical, hypoosmotic stimuli and hyperosmotic stimuli. Basal ATP release was approx. three times higher in the KCNQ1 + AQP1 and KCNQ1 injected oocytes compared to the non‐injected ones. Exogenously added ATP (0.1 mm) did not have any substantial effect on volume‐induced KCNQ1 currents. Nevertheless, apyrase decreased all currents by about 50%. Suramin inhibited about 23% of the KCNQ1 volume sensitivity. Expression of P2Y2 receptors stimulated endogenous Cl− channels, but it also led to 68% inhibition of the KCNQ1 currents. Adenosine (0.1 mm) also inhibited the KCNQ1 currents by about 56%.

Conclusion

Xenopus oocytes release ATP in response to mechanical stimuli and cell volume changes. Purinergic P2 and P1 receptors confer some of the KCNQ1 channel volume sensitivity, although endogenous adenosine receptors and expressed P2Y2 receptors do so in the negative direction.
Sporicidal Effects of High‐Intensity 405 nm Visible Light on Endospore‐Forming Bacteria
Authors: Maclean Michelle , Murdoch Lynne E. , MacGregor Scott J. , Anderson John G.
Published: July 2012

Resistance of bacterial endospores to treatments, including biocides, heat and radiation is a persistent problem. This study investigates the susceptibility of Bacillus and Clostridium endospores to 405 nm visible light, wavelengths which have been shown to induce inactivation of vegetative bacterial cells. Suspensions of B. cereus endospores were exposed to high‐intensity 405 nm light generated from a light‐emitting diode array and results demonstrate the induction of a sporicidal effect. Up to a 4‐log10 CFU mL−1 reduction in spore population was achieved after exposure to a dose of 1.73 kJ cm−2. Similar inactivation kinetics were demonstrated with B. subtilis, B. megaterium and C. difficile endospores. The doses required for inactivation of endospores were significantly higher than those required for inactivation of B. cereus and C. difficile vegetative cells, where ca 4‐log10 CFU mL−1 reductions were achieved after exposure to doses of 108 and 48 J cm−2, respectively. The significant increase in dose required for inactivation of endospores compared with vegetative cells is unsurprising due to the notorious resilience of these microbial structures. However, the demonstration that visible light of 405 nm can induce a bactericidal effect against endospores is significant, and could have potential for incorporation into decontamination methods for the removal of bacterial contamination including endospores.
Hemodynamic, Echocardiographic, and Exercise‐Related Effects of the HeartWare Left Ventricular Assist Device in Advanced Heart Failure
Authors: McDiarmid Adam , Gordon Brian , Wrightson Neil , Robinson‐Smith Nicola , Pillay Thasee , Parry Gareth , Schueler Stephan , MacGowan Guy A.
Published: July 2012

©2012 Wiley Periodicals, Inc.

The aim of this study was to determine the effects of the HeartWare left ventricular assist device (HVAD) (HeartWare International, Inc, Framingham, MA) on hemodynamics, ventricular function, and exercise capacity. Between July 2009 and March 2011, 46 patients with advanced heart failure had implantation of the HVAD. Of these patients, 30 had subsequent assessments for transplantation and these patients formed the study cohort. Thirty patients had assessments at a mean of 201±86 days and 13 went on to have a second assessment at 351±86 days. There were marked improvements in hemodynamics and exercise capacity at both assessments, with significant decreases in right and left heart filling pressures; increases in cardiac index, New York Heart Association class, and peak exercise oxygen consumption; and reduction in pulmonary vascular resistance (all P<.05). Left ventricular end‐diastolic and end‐systolic dimensions were unchanged at the first assessment, although there was a significant reduction in end‐diastolic diameter at the second assessment (P<.01). There were no significant changes in a visual grade of right ventricular function. After up to 1 year of support, the HVAD system results in significant benefits in overall heart failure status, with improved hemodynamics and exercise capacity. This occurs in the absence of marked changes in left ventricular size or right ventricular function.
EvolMarkers: a database for mining exon and intron markers for evolution, ecology and conservation studies
Authors: LI CHENHONG , RIETHOVEN JEAN‐JACK M. , NAYLOR GAVIN J. P.
Published: July 2012

Recent innovations in next‐generation sequencing have lowered the cost of genome projects. Nevertheless, sequencing entire genomes for all representatives in a study remains expensive and unnecessary for most studies in ecology, evolution and conservation. It is still more cost‐effective and efficient to target and sequence single‐copy nuclear gene markers for such studies. Many tools have been developed for identifying nuclear markers, but most of these have focused on particular taxonomic groups. We have built a searchable database, EvolMarkers, for developing single‐copy coding sequence (CDS) and exon‐primed‐intron‐crossing (EPIC) markers that is designed to work across a broad range of phylogenetic divergences. The database is made up of single‐copy CDS derived from BLAST searches of a variety of metazoan genomes. Users can search the database for different types of markers (CDS or EPIC) that are common to different sets of input species with different divergence characteristics. EvolMarkers can be applied to any taxonomic group for which genome data are available for two or more species. We included 82 genomes in the first version of EvolMarkers and have found the methods to be effective across Placozoa, Cnidaria, Arthropod, Nematoda, Annelida, Mollusca, Echinodermata, Hemichordata, Chordata and plants. We demonstrate the effectiveness of searching for CDS markers within annelids and show how to find potentially useful intronic markers within the lizard Anolis.
Laminar Regulation of STAT1 and STAT3 in Black Walnut Extract and Carbohydrate Overload Induced Models of Laminitis
Authors: Leise B.S. , Watts M. , Tanhoff E. , Johnson P.J. , Black S.J. , Belknap J.K.
Published: July 2012

Background

STAT1 and STAT3 are important signaling molecules in disorders of systemic inflammation and are likely to be involved in laminitis, as laminar and systemic inflammation have been well documented in experimental models of laminitis.

Hypothesis

The STAT1 and STAT3 activation (via phosphorylation of tyrosine and serine moieties) is occurring in the laminar tissue during the developmental and onset of lameness time points in both the black walnut extract (BWE) and carbohydrate overload (CHO) models of laminitis.

Animals

Archived laminar tissue from horses.

Methods

Experimental studies of induced laminitis (BWE and CHO administration) in horses were conducted and laminar tissue samples archived. Western hybridization was performed to determine concentrations of Tyr‐ and Ser‐phosphorylated STAT1 and STAT3 from these archived samples. The RT‐qPCR was also performed to assess mRNA concentrations of target genes of STAT1 and STAT3.

Results

Increases (P < .05) in phosphorylation of tyrosine705 and serine727 of STAT3, demonstrated by band intensity ratios, are present in laminar tissue from both the BWE and CHO models at the DEV and OG1 time points. No change in phosphorylation of tyrosine701 or serine727 of STAT1 was present in the laminar tissue from either the BWE or the CHO models. The SOCS3 mRNA concentrations were increased at the onset of lameness in both the CHO and BWE models.

Conclusions and Clinical Relevance

The STAT3 activation likely plays a role in equine laminitis, similar to its reported involvement in organ injury/failure in human sepsis. Regulation of JAK‐STAT, through STAT3 inhibitors, might serve as potential therapeutic target for controlling the inflammatory response in the septic horse.