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  • 1
    Publication Date: 2015-01-29
    Description: The purpose of this contribution is to set up a language to evaluate the results of concerted action among interdependent agents against predetermined properties that we can recognize as desirable from a deontic point of view. Unlike the standard view of logics to reason about coalitionally rational action, the capacity of a set of agents to take a rational decision will be restricted to what we will call agreements , which can be seen as solution concepts to a dependence structure present in a certain game. The language will identify those agreements that act accordingly or disaccordingly with the desirable properties arbitrarily set up in the beginning, and will reveal, by logical reasoning, a variety of structural properties of this type of collective action.
    Print ISSN: 0955-792X
    Electronic ISSN: 1465-363X
    Topics: Computer Science , Mathematics
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  • 2
    Publication Date: 2015-04-11
    Description: Background.  Bacillus Calmette-Guerin (BCG) vaccine is the most widely administered vaccine in the world, yet its mechanism of action remains unclear. We hypothesize that certain immune pathways are associated with reduced mycobacterial growth following BCG challenge in human volunteers. Methods.  We used samples from a mycobacterial challenge in which previously BCG-vaccinated or BCG-naive adults in the United Kingdom were challenged intradermally with a standard dose of BCG. Any remaining BCG was quantified in a skin biopsy specimen obtained 2 weeks after challenge and used as a measure of BCG growth and functional antimycobacterial immunity. We measured the immune response over the 2-week challenge, using DNA microarrays and flow cytometry, and correlated this with mycobacterial growth. Results.  The magnitude of the immune response to BCG is greater in previously vaccinated volunteers, and this correlates with reduced mycobacterial growth but increased scarring at the vaccination site. In particular, the interferon and interleukin 17 pathways are strongly induced in previously vaccinated volunteers and correlate with reduced mycobacterial growth in this population. Conclusion.  This study identifies pathways associated with control of mycobacterial growth in vivo in human volunteers and supports the use of BCG challenge as a tool for evaluating vaccine efficacy and identifying mechanisms of antimycobacterial immunity.
    Print ISSN: 0022-1899
    Electronic ISSN: 1537-6613
    Topics: Medicine
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  • 3
    Publication Date: 2015-10-14
    Description: Background: The risk of lymph node positivity (LN+) in rectal cancer is a parameter that impacts therapeutic recommendations. We aimed to quantify the effect of younger age on LN+ in rectal cancer. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, patients with rectal cancer diagnosed between 1988 and 2008 were identified. Patients were stage I-III, without preoperative radiotherapy, at least one lymph node examined, and a standard rectal cancer operation performed. The association of age and LN+ status was examined with logistic regression separately for each T stage, adjusting for multiple covariates. Poisson regression was used to evaluate age and number of positive lymph nodes (LNs). All statistical tests were two-sided. Results: Fifty-six thousand seventy-six patients were identified, including 1194 (2.1%) patients age 20 to 39 years at diagnosis and 4199 (7.5%) patients age 40 to 49 years (defined as young). For each T stage, LN+ was inversely associated with age (all P 〈 .001). For T1, T2, and T3, age remained predictive of LN+ status after adjustment for number of LNs examined and other covariates ( P 〈 .001 for each stage). Adjusted odds ratios (ORs) for LN+ for age 20 to 39 vs 60 to 69 were: T1: 1.97 (95% confidence interval [CI] = 1.36 to 2.86); T2: 1.48 (95% CI = 1.13 to 1.95); T3: 1.30 (95% CI = 1.10 to 1.53). Young age was a statistically significant predictor of an increased number of LNs positive for stage T2 ( P = .042) and T3 ( P = .002). Conclusion: In this large national dataset, young age at diagnosis is associated with an increased risk of LN+. This finding merits further investigation and may ultimately impact treatment decision-making for young early-stage patients.
    Electronic ISSN: 1460-2105
    Topics: Medicine
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  • 4
    Publication Date: 2014-10-29
    Description: Background Nonadherence to hormonal therapy is common and is associated with increased copayment amount. We investigated the change in adherence after the introduction of generic aromatase inhibitors (AIs) in 2010. Methods Using deidentified pharmacy and claims data from OptumInsight, we identified women older than 50 years on brand-name AIs (BAIs) and/or generic AIs (GAIs) for early breast cancer between January 1, 2007 and December 31, 2012. Clinical, demographic, and financial variables were evaluated. Adherence was defined as a medication possession ratio (MPR) 80% or greater. Results We identified 5511 women, 2815 (51.1%) on BAI, 1411 (25.6%) on GAI, and 1285 (23.3%) who switched from BAI to GAI. The median 30-day copayment was higher for BAI ($33.3) than for GAI ($9.04). In a multivariable Cox-proportional hazard analysis, women who took GAI were less likely to discontinue therapy (hazard ratio [HR] = 0.69, 95% confidence interval [CI] = 0.57 to 0.84) compared with BAI. Discontinuation was positively associated with a higher monthly copayment of $15 to $30 (HR = 1.21, 95% CI = 1.01 to 1.44) and more than $30 (HR = 1.49, 95% CI = 1.23 to 1.80) compared with less than $15. In a multivariable logistic regression analysis, adherence (medication possession ratio ≥ 80%) was positively associated with GAI use (odds ratio = 1.53, 95% CI = 1.22 to 1.91) compared with BAI and inversely associated with increased monthly copayment. In addition, adherence was associated with a high annual income of more than $100k/year (odds ratio = 1.58, 95% CI = 1.17 to 2.11). Conclusions Higher prescription copayment amount was associated with nonadherence and discontinuation of AIs. After controlling for copayment, discontinuation was higher and adherence was lower with Brand AIs. Because nonadherence is associated with worse survival, efforts should be directed towards reducing out-of-pocket costs for these life-saving medications.
    Electronic ISSN: 1460-2105
    Topics: Medicine
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  • 5
    Publication Date: 2015-08-27
    Description: In pancreatic β-cells, mitochondria play a central role in coupling glucose metabolism to insulin secretion. Chronic exposure of β-cells to metabolic stresses impairs their function and potentially induces apoptosis. Little is known on mitochondrial adaptation to metabolic stresses, i.e. high glucose, fatty acids or oxidative stress; being all highlighted in the pathogenesis of type 2 diabetes. Here, human islets were exposed for 3 days to 25 m m glucose, 0.4 m m palmitate, 0.4 m m oleate and transiently to H 2 O 2 . Culture at physiological 5.6 m m glucose served as no-stress control. Expression of mitochondrion-associated genes was quantified, including the transcriptome of mitochondrial inner membrane carriers. Targets of interest were further evaluated at the protein level. Three days after acute oxidative stress, no significant alteration in β-cell function or apoptosis was detected in human islets. Palmitate specifically increased expression of the pyruvate carriers MPC1 and MPC2, whereas the glutamate carrier GC1 and the aspartate/glutamate carrier AGC1 were down-regulated by palmitate and oleate, respectively. High glucose decreased mRNA levels of key transcription factors (HNF4A, IPF1, PPARA and TFAM) and energy-sensor SIRT1. High glucose also reduced expression of 11 mtDNA-encoded respiratory chain subunits. Interestingly, transcript levels of the carriers for aspartate/glutamate AGC2, malate DIC and malate/oxaloacetate/aspartate UCP2 were increased by high glucose, a profile suggesting important mitochondrial anaplerotic/cataplerotic activities and NADPH-generating shuttles. Chronic exposure to high glucose impaired glucose-stimulated insulin secretion, decreased insulin content, promoted caspase-3 cleavage and cell death, revealing glucotoxicity. Overall, expression profile of mitochondrion-associated genes was selectively modified by glucose, delineating a glucotoxic-specific signature.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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  • 6
    Publication Date: 2016-07-14
    Description: Beetles represent the largest insect order and they display extreme morphological, ecological and behavioral diversity, which makes them ideal models for evolutionary studies. Here, we present the draft genome of the scarab beetle Oryctes borbonicus , which has a more basal phylogenetic position than the two previously sequenced pest species Tribolium castaneum and Dendroctonus ponderosae providing the potential for sequence polarization. Oryctes borbonicus is endemic to La Réunion, an island located in the Indian Ocean, and is the host of the nematode Pristionchus pacificus , a well-established model organism for integrative evolutionary biology. At 518 Mb, the O. borbonicus genome is substantially larger and encodes more genes than T. castaneum and D. ponderosae . We found that only 25% of the predicted genes of O. borbonicus are conserved as single copy genes across the nine investigated insect genomes, suggesting substantial gene turnover within insects. Even within beetles, up to 21% of genes are restricted to only one species, whereas most other genes have undergone lineage-specific duplications and losses. We illustrate lineage-specific duplications using detailed phylogenetic analysis of two gene families. This study serves as a reference point for insect/coleopteran genomics, although its original motivation was to find evidence for potential horizontal gene transfer (HGT) between O. borbonicus and P. pacificus . The latter was previously shown to be the recipient of multiple horizontally transferred genes including some genes from insect donors. However, our study failed to provide any clear evidence for additional HGTs between the two species.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 7
    Publication Date: 2016-08-19
    Description: Understanding how new species form requires investigation of evolutionary forces that cause phenotypic and genotypic changes among populations. However, the mechanisms underlying speciation vary and little is known about whether genomes diversify in the same ways in parallel at the incipient scale. We address this using the nematode, Pristionchus pacificus , which resides at an interesting point on the speciation continuum (distinct evolutionary lineages without reproductive isolation), and inhabits heterogeneous environments subject to divergent environmental pressures. Using whole genome re-sequencing of 264 strains, we estimate F ST to identify outlier regions of extraordinary differentiation (~1.725 Mb of the 172.5 Mb genome). We find evidence for shared divergent genomic regions occurring at a higher frequency than expected by chance among populations of the same evolutionary lineage. We use allele frequency spectra to find that, among lineages, 53% of divergent regions are consistent with adaptive selection, whereas 24% and 23% of such regions suggest background selection and restricted gene flow, respectively. In contrast, among populations from the same lineage, similar proportions (34–48%) of divergent regions correspond to adaptive selection and restricted gene flow, whereas 13–22% suggest background selection. Because speciation often involves phenotypic and genomic divergence, we also evaluate phenotypic variation, focusing on pH tolerance, which we find is diverging in a manner corresponding to environmental differences among populations. Taking a genome-wide association approach, we functionally validate a significant genotype–phenotype association for this trait. Our results are consistent with P. pacificus undergoing heterogeneous genotypic and phenotypic diversification related to both evolutionary and environmental processes.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
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  • 8
    Publication Date: 2016-09-17
    Description: Small-molecule signaling in nematode dauer formation has emerged as a major model to study chemical communication in development and evolution. Developmental arrest as nonfeeding and stress-resistant dauer larvae represents the major survival and dispersal strategy. Detailed studies in Caenorhabditis elegans and Pristionchus pacificus revealed that small-molecule communication changes rapidly in evolution resulting in extreme structural diversity of small-molecule compounds. In C. elegans , a blend of ascarosides constitutes the dauer pheromone, whereas the P. pacificus dauer pheromone includes additional paratosides and integrates building blocks from diverse primary metabolic pathways. Despite this complexity of small-molecule structures and functions, little is known about the biosynthesis of small molecules in nematodes outside C. elegans . Here, we show that the genes encoding enzymes of the peroxisomal β-oxidation pathway involved in small-molecule biosynthesis evolve rapidly, including gene duplications and domain switching. The thiolase daf-22 , the most downstream factor in C. elegans peroxisomal β-oxidation, has duplicated in P. pacificus , resulting in Ppa-daf-22.1 , which still contains the sterol-carrier-protein (SCP) domain that was lost in C. elegans daf-22 , and Ppa-daf-22.2. Using the CRISPR/Cas9 system, we induced mutations in both P. pacificus daf-22 genes and identified an unexpected complexity of functional conservation and divergence. Under well-fed conditions, ascaroside biosynthesis proceeds exclusively via Ppa-daf-22.1 . In contrast, starvation conditions induce Ppa-daf-22.2 activity, resulting in the production of a specific subset of ascarosides. Gene expression studies indicate a reciprocal up-regulation of both Ppa-daf-22 genes, which is, however, independent of starvation. Thus, our study reveals an unexpected functional complexity of dauer development and evolution.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
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  • 9
    Publication Date: 2013-08-15
    Description: The hyperglycaemia seen in type 2 diabetes mellitus (DM2) is associated with increased oxidative stress and production of reactive oxygen species, both of which are factors that can provoke DNA damage. Notwithstanding, other factors, including medications and individual susceptibility, can also induce this type of DNA lesion. The objective of this study was, therefore, to investigate the influence of glycaemic control, oral antidiabetic drugs (metformin and glibenclamide) and polymorphisms of the XRCC1 and XRCC3 genes on the frequency of DNA damage in DM2 patients, which was accessed by the cytokinesis-block micronucleus cytome and the comet assays on the ex vivo mitogenically stimulated lymphocytes. The 53 people recruited to take part in the study were already on treatment with metformin and were followed for 5 months. Ten of these patients were put on combined treatment with the addition of glibenclamide. It was observed that the greater the plasma metformin concentration, the lower the frequency of micronuclei (MN) in the sample total ( P = 0.009) and also that the subset of patients using combined treatment including glibenclamide had a significantly higher MN rate 90 days after starting combined treatment ( P = 0.024). In the subset who only took metformin, the rate of MN was significantly higher among carriers of the 399Gln allele on the XRCC1 gene ( P = 0.008). In addition, homozygotes for the 241Thr allele exhibited a significant increase in MN in the combined treatment group ( P = 0.008). Our results suggest that different combinations of oral antidiabetic drugs and polymorphisms on genes involved in the DNA damage repair system could influence the frequency of this type of chromosome lesion, which can be a useful biomarker for assessing the risk of developing cancer.
    Print ISSN: 0267-8357
    Electronic ISSN: 1464-3804
    Topics: Biology , Medicine
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  • 10
    Publication Date: 2014-03-25
    Description: Background.  A new vaccine is urgently needed to combat tuberculosis. However, without a correlate of protection, selection of the vaccines to take forward into large-scale efficacy trials is difficult. Use of bacille Calmette-Guérin (BCG) as a surrogate for human Mycobacterium tuberculosis challenge is a novel model that could aid selection. Methods.  Healthy adults were assigned to groups A and B (BCG-naive) or groups C and D (BCG-vaccinated). Groups B and D received candidate tuberculosis vaccine MVA85A. Participants were challenged with intradermal BCG 4 weeks after those who received MVA85A. Skin biopsies of the challenge site were taken 2 weeks post challenge and BCG load quantified by culture and quantitative polymerase chain reaction (qPCR). Results.  Volunteers with a history of BCG showed some degree of protective immunity to challenge, having lower BCG loads compared with volunteers without prior BCG, regardless of MVA85A status. There was a significant inverse correlation between antimycobacterial immunity at peak response after MVA85A and BCG load detected by qPCR. Conclusion.  Our results support previous findings that this BCG challenge model is able to detect differences in antimycobacterial immunity induced by vaccination and could aid in the selection of candidate tuberculosis vaccines for field efficacy testing. Clinical Trials Registration  NCT01194180.
    Print ISSN: 0022-1899
    Electronic ISSN: 1537-6613
    Topics: Medicine
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