bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selection for sex in finite populations
Authors: Roze D. 
Published: March 2014

AbstractFinite population size generates interference between selected loci, which has been shown to favour increased rates of recombination. In this article, I present different analytical models exploring selection acting on a ‘sex modifier locus’ (that affects the relative investment into asexual and sexual reproduction) in a finite population. Two forms of selective forces act on the modifier: direct selection due to intrinsic costs associated with sexual reproduction and indirect selection generated by one or two other loci affecting fitness. The results show that indirect selective forces differ from those acting on a recombination modifier even in the case of a haploid population: in particular, a single selected locus generates indirect selection for sex, while two loci are required in the case of a recombination modifier. This effect stems from the fact that modifier alleles increasing sex escape more easily from low‐fitness genetic backgrounds than alleles coding for lower rates of sex. Extrapolating the results from three‐locus models to a large number of loci at mutation–selection balance indicates that in the parameter range where indirect selection is strong enough to outweigh a substantial cost of sex, interactions between selected loci have a stronger effect than the sum of individual effects of each selected locus. Comparisons with multilocus simulation results show that such extrapolations may provide correct predictions for the evolutionarily stable rate of sex, unless the cost of sex is high.
mTOR complex 1: a key player in neuroadaptations induced by drugs of abuse
Authors: Neasta Jeremie , Barak Segev , Hamida Sami Ben , Ron Dorit 
Published: March 2014

AbstractThe mammalian (or mechanistic) target of rapamycin (mTOR) complex 1 (mTORC1) is a serine and threonine kinase that regulates cell growth, survival, and proliferation. mTORC1 is a master controller of the translation of a subset of mRNAs. In the central nervous system mTORC1 plays a crucial role in mechanisms underlying learning and memory by controlling synaptic protein synthesis. Here, we review recent evidence suggesting that the mTORC1 signaling pathway promotes neuroadaptations following exposure to a diverse group of drugs of abuse including stimulants, cannabinoids, opiates, and alcohol. We further describe potential molecular mechanisms by which drug‐induced mTORC1 activation may alter brain functions. Finally, we propose that mTORC1 is a focal point shared by drugs of abuse to mediate drug‐related behaviors such as reward seeking and excessive drug intake, and offer future directions to decipher the contribution of the kinase to mechanisms underlying addiction.
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Recent studies suggesting that exposure to diverse classes of drugs of abuse as well as exposure to drug‐associated memories lead to mTORC1 kinase activation in the limbic system. In turn, mTORC1 controls the onset and the maintenance of pathological neuroadaptions that underlie several features of drug addiction such as drug seeking and relapse. Therefore, we propose that targeting mTORC1 and its effectors is a promising strategy to treat drug disorders.
Skin in the Game and Moral Hazard
Authors: CHEMLA GILLES , HENNESSY CHRISTOPHER A. 
Published: March 2014

ABSTRACTWhat determines securitization levels, and should they be regulated? To address these questions we develop a model where originators can exert unobservable effort to increase expected asset quality, subsequently having private information regarding quality when selling ABS to rational investors. Absent regulation, originators may signal positive information via junior retentions or commonly adopt low retentions if funding value and price informativeness are high. Effort incentives are below first‐best absent regulation. Optimal regulation promoting originator effort entails a menu of junior retentions or one junior retention with size decreasing in price informativeness. Zero retentions and opacity are optimal among regulations inducing zero effort.
Click or Call? Auction versus Search in the Over‐the‐Counter Market
Authors: HENDERSHOTT TERRENCE , MADHAVAN ANANTH 
Published: March 2014

ABSTRACTOver‐the‐counter (OTC) markets dominate trading in many asset classes. Will electronic trading displace traditional OTC “voice” trading? Can electronic and voice systems coexist? What types of securities and trades are best suited for electronic trading? We study these questions by focusing on an innovation in electronic trading technology that enables investors to simultaneously search many bond dealers. We show that periodic one‐sided electronic auctions are a viable and important source of liquidity even in inactively traded instruments. These mechanisms are a natural compromise between bilateral search in OTC markets and continuous double auctions in electronic limit order books.
Maternal hepatitis B and hepatitis C infection and neonatal neurological outcomes
Authors: Salemi J. L. , Whiteman V. E. , August E. M. , Chandler K. , Mbah A. K. , Salihu H. M. 
Published: March 2014

SummaryTo examine the associations between maternal hepatitis B (HBV) and hepatitis C (HCV) infection status and selected infant neurological outcomes diagnosed at birth, we conducted a population‐based, retrospective cohort study on singleton live births in Florida from 1998 to 2009. Primary exposures included maternal HBV and HCV monoinfection. The neurological outcomes included brachial plexus injury, cephalhematoma, foetal distress, feeding difficulties, intraventricular h aemorrhage and neonatal seizures. Multivariable logistic regression models were used to generate odds ratios (OR) and 95% confidence intervals (CI) that were adjusted for socio‐demographic characteristics, risky behaviours, pregnancy complications and pre‐existing medical conditions, and timing of delivery. The risk of an adverse neurological outcome was higher in infants born to mothers with hepatitis viral infection (7.2% for HCV, 5.0% for HBV), compared with infants of hepatitis virus‐free mothers (4.2%). After adjusting for potential confounders, women with HBV were twice as likely to have infants who suffered from brachial plexus injury (OR = 2.04, 95% CI = 1.15–3.60), while those with HCV had an elevated odds of having an infant with feeding difficulties (OR: 1.32, 95% CI = 1.06–1.64) and a borderline increased likelihood for neonatal seizures (OR = 1.74, 95% CI = 0.98–3.10). Additionally, HCV+ mothers had a 22% increased odds of having an infant with some type of adverse neurological outcome (OR: 1.22, 95% CI = 1.03–1.44). Our findings add to current understanding of the association between maternal HBV/HCV infections and infant neurological outcomes. Further research evaluating the role of maternal HBV and HCV infections (including viraemia, treatment) on pregnancy outcomes is warranted.
Non‐alcoholic steatohepatitis weakens the acute phase response to endotoxin in rats
Authors: Thomsen Karen L. , Hebbard Lionel , Glavind Emilie , Clouston Andrew , Vilstrup Hendrik , George Jacob , Grønbæk Henning 
Published: March 2014

AbstractBackground & AimsPatients with non‐alcoholic steatohepatitis (NASH) have increased mortality, including from infections. We, therefore, tested in a rodent model of steatohepatitis whether the hepatic acute phase response is intact.MethodsSteatohepatitis was induced in rats by feeding a high‐fat, high‐cholesterol diet for 4 (early) and 16 weeks (advanced NASH). 2 h after low‐dose LPS (0.5 mg/kg i.p.), we measured the serum concentrations of tumour necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6). We also measured liver mRNA's and the serum concentrations of acute phase proteins 24 h after LPS.ResultsNon‐alcoholic steatohepatitis in itself increased the liver mRNA levels of TNF‐α and IL‐6 and also the liver mRNA and serum levels of the acute phase proteins. The exposure to LPS increased serum TNF‐α in both early and advanced NASH and more so than in the control rats. However, the increases in acute phase protein genes in liver tissue and proteins in the blood were lower than in the control rats.ConclusionIn rats with early or advanced experimental NASH, LPS despite an increased interleukin release resulted in a blunted acute phase protein response. This tachyphylaxis may be part of the mechanism for the increased infection susceptibility of patients with NASH. We speculate that the steatosis‐related interleukin release desensitises the signalling pathway leading to acute phase protein synthesis.
Boceprevir in liver transplant recipients
Authors: Saab Sammy , Manne Vignan , Bau Sherona , Reynolds Justin A. , Allen Ruby , Goldstein Leonard , Durazo Francisco , El‐Kabany Mohammed , Han Steven , Busuttil Ronald W. 
Published: March 2014

AbstractBackgroundThere has been increasing interest in using protease inhibitors with pegylated interferon and ribavirin to treat recurrent hepatitis C (HCV) disease in liver transplant recipients.MethodsWe retrospectively evaluated the safety and efficacy in liver transplant recipients treated for recurrent hepatitis C genotype 1 with the combination of peginterferon, ribavirin and boceprevir.ResultsTwenty liver transplant recipients were treated for recurrent hepatitis C. Baseline alanine aminotransferase, total bilirubin and HCV RNA values (± SD) were 67.5 (±50.9) mg/dl, 1.78 (±1.99) U/L, and 16 955 510 (±21 620 675) IU/ml. Anaemia was a common adverse event requiring epoetin in 16 of 20 recipients and ribavirin dose reductions in 17 of 20 recipients. One‐third of recipients required a blood transfusion. Filgrastim was used in 11 of 20 patients (55%) and eltrombopag in two of 20 recipients (10%) over the course of treatment. Serum creatinine level increased significantly from a baseline value of 1.33 mg/dl to 1.59 mg/dl at week 20 of boceprevir (P < 0.005). The overall sustained viral response (SVR) was 50%. Of the 14 patients who had a viral load less than 1000 IU/ml at week 4 of boceprevir, the SVR was 71%. The SVR was 83% of the 11 patients who had undetectable viral levels at week 4 of boceprevir.ConclusionsAntiviral therapy utilizing boceprevir in liver transplant recipients requires close monitoring. Anaemia and neutropenia were common requiring growth factors in most recipients. On‐treatment viral responses appear promising but long‐term data are needed.
Phylogeography in continuous space: coupling species distribution models and circuit theory to assess the effect of contiguous migration at different climatic periods on genetic differentiation in Busseola fusca (Lepidoptera: Noctuidae)
Authors: Dupas S. , le Ru B. , Branca A. , Faure N. , Gigot G. , Campagne P. , Sezonlin M. , Ndemah R. , Ong'amo G. , Calatayud P.‐A. , Silvain J.‐F. 
Published: March 2014

AbstractCurrent population genetic models fail to cope with genetic differentiation for species with large, contiguous and heterogeneous distribution. We show that in such a case, genetic differentiation can be predicted at equilibrium by circuit theory, where conductance corresponds to abundance in species distribution models (SDMs). Circuit‐SDM approach was used for the phylogeographic study of the lepidopteran cereal stemborer Busseola fuscaFüller (Noctuidae) across sub‐Saharan Africa. Species abundance was surveyed across its distribution range. SDMs were optimized and selected by cross‐validation. Relationship between observed matrices of genetic differentiation between individuals, and between matrices of resistance distance was assessed through Mantel tests and redundancy discriminant analyses (RDAs). A total of 628 individuals from 130 localities in 17 countries were genotyped at seven microsatellite loci. Six population clusters were found based on a Bayesian analysis. The eastern margin of Dahomey gap between East and West Africa was the main factor of genetic differentiation. The SDM projections at present, last interglacial and last glacial maximum periods were used for the estimation of circuit resistance between locations of genotyped individuals. For all periods of time, when using either all individuals or only East African individuals, partial Mantel r and RDA conditioning on geographic distance were found significant. Under future projections (year 2080), partial r and RDA significance were different. From this study, it is concluded that analytical solutions provided by circuit theory are useful for the evolutionary management of populations and for phylogeographic analysis when coalescence times are not accessible by approximate Bayesian simulations.
Gene expression divergence between malaria vector sibling species Anopheles gambiae and An. coluzzii from rural and urban Yaoundé Cameroon
Authors: Cassone Bryan J. , Kamdem Colince , Cheng Changde , Tan John C. , Hahn Matthew W. , Costantini Carlo , Besansky Nora J. 
Published: March 2014

AbstractDivergent selection based on aquatic larval ecology is a likely factor in the recent isolation of two broadly sympatric and morphologically identical African mosquito species, the malaria vectors Anopheles gambiae and An. coluzzii. Population‐based genome scans have revealed numerous candidate regions of recent positive selection, but have provided few clues as to the genetic mechanisms underlying behavioural and physiological divergence between the two species, phenotypes which themselves remain obscure. To uncover possible genetic mechanisms, we compared global transcriptional profiles of natural and experimental populations using gene‐based microarrays. Larvae were sampled as second and fourth instars from natural populations in and around the city of Yaoundé, capital of Cameroon, where the two species segregate along a gradient of urbanization. Functional enrichment analysis of differentially expressed genes revealed that An. coluzzii – the species that breeds in more stable, biotically complex and potentially polluted urban water bodies – overexpresses genes implicated in detoxification and immunity relative to An. gambiae, which breeds in more ephemeral and relatively depauperate pools and puddles in suburbs and rural areas. Moreover, our data suggest that such overexpression by An. coluzzii is not a transient result of induction by xenobiotics in the larval habitat, but an inherent and presumably adaptive response to repeatedly encountered environmental stressors. Finally, we find no significant overlap between the differentially expressed loci and previously identified genomic regions of recent positive selection, suggesting that transcriptome divergence is regulated by trans‐acting factors rather than cis‐acting elements.
Epidemiology of asexuality induced by the endosymbioticWolbachiaacross phytophagous wasp species: host plant specialization matters
Authors: Boivin T. , Henri H. , Vavre F. , Gidoin C. , Veber P. , Candau J.‐N. , Magnoux E. , Roques A. , Auger‐Rozenberg M.‐A. 
Published: March 2014

AbstractAmong eukaryotes, sexual reproduction is by far the most predominant mode of reproduction. However, some systems maintaining sexuality appear particularly labile and raise intriguing questions on the evolutionary routes to asexuality. Thelytokous parthenogenesis is a form of spontaneous loss of sexuality leading to strong distortion of sex ratio towards females and resulting from mutation, hybridization or infection by bacterial endosymbionts. We investigated whether ecological specialization is a likely mechanism of spread of thelytoky within insect communities. Focusing on the highly specialized genusMegastigmus(Hymenoptera: Torymidae), we first performed a large literature survey to examine the distribution of thelytoky in these wasps across their respective obligate host plant families. Second, we tested for thelytoky caused by endosymbionts by screening in 15 arrhenotokous and 10 thelytokous species forWolbachia,Cardinium,ArsenophonusandRickettsiaendosymbionts and by performing antibiotic treatments. Finally, we performed phylogenetic reconstructions using multilocus sequence typing (MLST) to examine the evolution of endosymbiont‐mediated thelytoky inMegastigmusand its possible connections to host plant specialization. We demonstrate that thelytoky evolved from ancestral arrhenotoky through the horizontal transmission and the fixation of the parthenogenesis‐inducingWolbachia. We find that ecological specialization inWolbachia's hosts was probably a critical driving force forWolbachiainfection and spread of thelytoky, but also a constraint. Our work further reinforces the hypothesis that community structure of insects is a major driver of the epidemiology of endosymbionts and that competitive interactions among closely related species may facilitate their horizontal transmission.
Subcellular localization, interactions and dynamics of the phage‐shock protein‐like Lia response in Bacillus subtilis
Authors: Domínguez‐Escobar Julia , Wolf Diana , Fritz Georg , Höfler Carolin , Wedlich‐Söldner Roland , Mascher Thorsten 
Published: March 2014

SummaryThe liaIH operon of Bacillus subtilis is the main target of the envelope stress‐inducible two‐component system LiaRS. Here, we studied the localization, interaction and cellular dynamics of Lia proteins to gain insights into the physiological role of the Lia response. We demonstrate that LiaI serves as the membrane anchor for the phage‐shock protein A homologue LiaH. Under non‐inducing conditions, LiaI locates in highly motile membrane‐associated foci, while LiaH is dispersed throughout the cytoplasm. Under stress conditions, both proteins are strongly induced and colocalize in numerous distinct static spots at the cytoplasmic membrane. This behaviour is independent of MreB and does also not correlate with the stalling of the cell wall biosynthesis machinery upon antibiotic inhibition. It can be induced by antibiotics that interfere with the membrane‐anchored steps of cell wall biosynthesis, while compounds that inhibit the cytoplasmic or extracytoplasmic steps do not trigger this response. Taken together, our data are consistent with a model in which the Lia system scans the cytoplasmic membrane for envelope perturbations. Upon their detection, LiaS activates the cognate response regulator LiaR, which in turn strongly induces the liaIH operon. Simultaneously, LiaI recruits LiaH to the membrane, presumably to protect the envelope and counteract the antibiotic‐induced damage.
Comparative off‐host survival of larval Rocky Mountain Wood Ticks (Dermacentor andersoni) collected from ecologically distinct field populations
Authors: OWEN J. P. , VANDER VLIET A. , SCOLES G. A. 
Published: March 2014

AbstractDermacentor andersoni (Ixodida: Ixodidae) Stiles, also known as the Rocky Mountain Wood Tick (RMWT), is found throughout the western United States and transmits pathogens of importance to human and animal health. The distributions and activity patterns of RMWTs are shaped by regional climatic variation. However, it is unknown if responses to climatic variation differ across the tick's geographical range. The objective of this narrow study was to test the hypothesis that the responses of RMWTs to abiotic conditions [e.g. temperature and RH (relative humidity)] vary among populations. We collected RMWTs from ecologically distinct field sites in the states of Montana and Oregon (USA). In the laboratory, we tracked weekly survival of tick larvae under four combinations of RH (75% and 98%) and temperature (26 and 32 °C) that reflected the range of conditions observed in the source habitats during spring‐summer. For both populations, larval survival time decreased at the higher ambient temperature (50% mortality 1–2 weeks earlier). Differences in RH did not affect the survival time of larvae from Oregon. By contrast, the survival time of larvae from Montana decreased at the lower RH (50% mortality 1 week earlier). These data suggest that the tolerance limits for water stress may differ among populations of D. andersoni.
Tubular urinary biomarkers do not identify aetiology of acute kidney injury in kidney transplant recipients
Authors: Ramirez‐Sandoval Juan C , Barrera‐Chimal Jonatan , Simancas Perla E , Correa‐Rotter Ricardo , Bobadilla Norma A , Morales‐Buenrostro Luis E 
Published: March 2014

AbstractAimTo evaluate the performance of urinary neutrophil gelatinase‐associated lipocalin (uNGAL), kidney injury molecule, interleukin‐18 and heat shock protein 72 for differential diagnosis between causes of acute kidney injury in kidney transplant recipients, especially immunological rejection.Patients and MethodsWe measured these biomarkers in 67 kidney transplant recipients with acute kidney injury according to the RIFLE criteria.ResultsThere were no statistical differences in biomarkers between kidney transplant recipients with immunological rejection (n = 20), pre‐renal causes (n = 20) and other AKI causes (n = 27). Only the uNGAL level relative to urinary creatinine (uNGAL/uCr) for immunological rejection was different in comparison with others (P < 0.001); a cut‐off of 59 μg/g of uNGAL/uCr had a sensitivity and specificity of 60% and 58% respectively (area under the curve in receiver‐operating characteristic curve, 0.65). The other biomarkers were not useful in differentiating the causes of acute kidney injury.ConclusionThe biomarkers tested are not useful in identifying immunological rejection as cause of acute kidney injury in kidney transplant recipients.
Hepatitis C virus: a silent killer relevant to dentistry
Authors: Carrozzo M 
Published: March 2014

Around 25 years ago, hepatitis C virus (HCV) was identified, and following intense research and tremendous advancements, the infection is now potentially curable and even complete viral eradication is possible. It is also evident that HCV can be involved in some oral disorders, but more research is clearly warranted on oral health of HCV‐infected patients. Given the global estimates on HCV epidemic and its likely huge economic impact, primary prevention and secondary prevention are worldwide priorities. However, investments are still insufficient to achieve these goals.
Ultrasound‐Guided Venous Puncture in Electrophysiological Procedures: A Safe Method, Rapidly Learned
Authors: ERRAHMOUNI ABDELKARIM , BUN SOK‐SITHIKUN , LATCU DECEBAL GABRIEL , SAOUDI NADIR 
Published: March 2014

BackgroundWe sought to determine the feasibility and learning curve associated with systematic use of real‐time ultrasound‐guided venous puncture (UGVP) in patients undergoing electrophysiological (EP) procedures.MethodsFour operators performed UGVP in consecutive patients undergoing EP procedures (group I). Puncture time was defined as the time from ultrasound (US) visualization of the femoral vein to the insertion of all sheaths. A learning curve as defined by UGVP evolution over the time was established for each operator. This population was compared to an historical group of patients in whom venous puncture was performed without US (group II).ResultsA total of 150 patients per group were included. UGVP was successfully achieved in all patients. Mean time for 2.8 ± 0.7 sheaths per patient insertion was 280 ± 151 seconds in group I. There was one minor vascular complication (VC) out of 150 patients (0.66%) without major VC in group I as compared with group II (2% major VC and 4.6% minor VC; P < 0.05). UGVP time reached a plateau at the sixth patient‐case for each operator; thus, learning curve was estimated to six patients.ConclusionUGVP is a short learning curve technique, significantly associated with a low incidence of minor VCs. This study supports wide use of UGVP in patients undergoing EP procedures.