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Search Results: 1 - 10 of 221050 matches for " Alister C Ward "
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Evolution of Class I cytokine receptors
Clifford Liongue, Alister C Ward
BMC Evolutionary Biology , 2007, DOI: 10.1186/1471-2148-7-120
Abstract: Only two Class I receptors were identified in sea squirt, one with homology to the archetypal GP130 receptor, and the other with high conservation with the divergent orphan receptor CLF-3. In contrast, 36 Class I cytokine receptors were present in zebrafish, including representative members for each of the five structural groups found in mammals. This allowed the identification of 27 core receptors belonging to the last common ancestor of teleosts and mammals.This study suggests that the majority of diversification of this receptor family occurred after the divergence of urochordates and vertebrates approximately 794 million years ago (MYA), but before the divergence of ray-finned from lobe-finned fishes around 476 MYA. Since then, only relatively limited lineage-specific diversification within the different Class I receptor structural groups has occurred.Cytokines are a class of proteins that includes interleukins (ILs), interferons (IFNs), colony-stimulating factors (CSFs), and tumor necrosis factors (TNFs). These polypeptides are produced and secreted by cells in response to many stimuli and mediate their effects by binding to specific receptors on the surface of target cells [1,2]. Class I helical cytokines represent the largest group of cytokines and utilize a family of cell-surface receptors that are structurally divergent from those employed by other cytokines, such as the TNF receptor family and receptor tyrosine kinases [3]. The receptors for Class I helical cytokines consist of various receptor chains that associate in higher order homo- and heterotypic complexes. Signaling via these receptors has a myriad of roles, including a major influence on immunity and hematopoiesis [4-6]. There is considerable functional redundancy amongst Class I helical cytokine receptors. This is partially due to some cytokines binding to multiple receptor complexes, multiple cytokines binding to the same receptor complex, and the sharing of common signal transducing receptor ch
Evolution of JAK-STAT Pathway Components: Mechanisms and Role in Immune System Development
Clifford Liongue, Lynda A. O'Sullivan, Monique C. Trengove, Alister C. Ward
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0032777
Abstract: Background Lying downstream of a myriad of cytokine receptors, the Janus kinase (JAK) – Signal transducer and activator of transcription (STAT) pathway is pivotal for the development and function of the immune system, with additional important roles in other biological systems. To gain further insight into immune system evolution, we have performed a comprehensive bioinformatic analysis of the JAK-STAT pathway components, including the key negative regulators of this pathway, the SH2-domain containing tyrosine phosphatase (SHP), Protein inhibitors against Stats (PIAS), and Suppressor of cytokine signaling (SOCS) proteins across a diverse range of organisms. Results Our analysis has demonstrated significant expansion of JAK-STAT pathway components co-incident with the emergence of adaptive immunity, with whole genome duplication being the principal mechanism for generating this additional diversity. In contrast, expansion of upstream cytokine receptors appears to be a pivotal driver for the differential diversification of specific pathway components. Conclusion Diversification of JAK-STAT pathway components during early vertebrate development occurred concurrently with a major expansion of upstream cytokine receptors and two rounds of whole genome duplications. This produced an intricate cell-cell communication system that has made a significant contribution to the evolution of the immune system, particularly the emergence of adaptive immunity.
From transcriptome to biological function: environmental stress in an ectothermic vertebrate, the coral reef fish Pomacentrus moluccensis
Karin S Kassahn, Ross H Crozier, Alister C Ward, Glenn Stone, M Julian Caley
BMC Genomics , 2007, DOI: 10.1186/1471-2164-8-358
Abstract: We identified a series of gene functions that were involved in all stress responses examined here, suggesting some common effects of stress on biological function. These common responses were achieved by the regulation of largely independent sets of genes; the responses of individual genes varied greatly across different stress types. In response to heat exposure over five days, a total of 324 gene loci were differentially expressed. Many heat-responsive genes had functions associated with protein turnover, metabolism, and the response to oxidative stress. We were also able to identify groups of co-regulated genes, the genes within which shared similar functions.This is the first environmental genomic study to measure gene regulation in response to different environmental stressors in a natural population of a warm-adapted ectothermic vertebrate. We have shown that different types of environmental stress induce expression changes in genes with similar gene functions, but that the responses of individual genes vary between stress types. The functions of heat-responsive genes suggest that prolonged heat exposure leads to oxidative stress and protein damage, a challenge of the immune system, and the re-allocation of energy sources. This study hence offers insight into the effects of environmental stress on biological function and sheds light on the expected sensitivity of coral reef fishes to elevated temperatures in the future.Microarray technology provides a powerful tool for investigating gene regulation and its significance for biological function. However, our understanding of such relationships during environmental stress remains fragmentary, especially in vertebrates. In particular, the commonality, or otherwise, of the responses of vertebrates to different environmental stresses remain poorly understood. Recently, some understanding of responses to individual stresses, in particular those related to thermal stress in teleost fishes, has been gained. In these sp
The Potential Link between Gut Microbiota and IgE-Mediated Food Allergy in Early Life
John Molloy,Katrina Allen,Fiona Collier,Mimi L. K. Tang,Alister C. Ward,Peter Vuillermin
International Journal of Environmental Research and Public Health , 2013, DOI: 10.3390/ijerph10127235
Abstract: There has been a dramatic rise in the prevalence of IgE-mediated food allergy over recent decades, particularly among infants and young children. The cause of this increase is unknown but one putative factor is a change in the composition, richness and balance of the microbiota that colonize the human gut during early infancy. The coevolution of the human gastrointestinal tract and commensal microbiota has resulted in a symbiotic relationship in which gut microbiota play a vital role in early life immune development and function, as well as maintenance of gut wall epithelial integrity. Since IgE mediated food allergy is associated with immune dysregulation and impaired gut epithelial integrity there is substantial interest in the potential link between gut microbiota and food allergy. Although the exact link between gut microbiota and food allergy is yet to be established in humans, recent experimental evidence suggests that specific patterns of gut microbiota colonization may influence the risk and manifestations of food allergy. An understanding of the relationship between gut microbiota and food allergy has the potential to inform both the prevention and treatment of food allergy. In this paper we review the theory and evidence linking gut microbiota and IgE-mediated food allergy in early life. We then consider the implications and challenges for future research, including the techniques of measuring and analyzing gut microbiota, and the types of studies required to advance knowledge in the field.
Vulvar dystrophies: A long-term Brisbane study of 155 cases  [PDF]
Ian S. C. Jones, Alister Jones
Open Journal of Obstetrics and Gynecology (OJOG) , 2012, DOI: 10.4236/ojog.2012.23042
Abstract: Objective: To review the long-term outcomes for 155 women with a vulvar dystrophy (VD) who attended the Royal Brisbane Hospital Vulvar Clinic between 1976 and 1988. Methods: VD data from Vulvar Diseases Clinic were reviewed and analysed using the computer software Statistical package for the Social Sciences (SPSS) 11.0. Results: Of 155 patients 94 had Lichen Sclerosus (LS), 41 Lichen Simplex Chronicus (LSC) and 20 Mixed Dystrophy (MD). Three patients developed squamous cell carcinomas of the vulva between 10 and 26 years after presentation with a VD. To date only one of these three patients remains alive following treatment. Conclusion: The need for long term follow up is stressed and any of the three types of VD may become malignant. Time from diagnosis to malignant change is not predictive. VD treatments seem to go through phases with the application of potent steroid creams having stood the test of time.
Rainfall effect on dissipation and movement of diuron and simazine in a vineyard soil
Alister, C.;Kogan, M.;
Planta Daninha , 2010, DOI: 10.1590/S0100-83582010000500014
Abstract: from 2003 to 2007, a field study was performed in a vineyard in chile to investigate diuron and simazine soil behavior and the effect of additional rainfall. both herbicides were applied once a year at a rate of 2.0 kg ha-1 a.i. herbicide concentrations in soil were measured at 0, 10, 20, 40, 90 and 340 days after application, under two pluviometric conditions, natural rainfall and natural rainfall plus irrigation with 180 mm of simulated rainfall during the first 90 days after application. soil partition coefficient (kd) varied in the soil profile (0 to 90 cm deep) from 6.75 to 2.04 ml g-1 and from 1.4 to 0.66 ml g-1 and the maximum soil adsorption capacity was approximately 18.3 mg g-1 and 8.3 mg g-1 for diuron and simazine, respectively. diuron and simazine reached up to 90 and 120 cm of soil depth, with an average of 8.3% and 62.4% of herbicide moved below 15 cm in the soil, respectively. simazine soil half-life (dt50) was 38.1 days and 7.5 days, whereas the half life for diuron varied from 68.0 and 24.6 for natural rainfall and irrigated, respectively. the average of residual simazine remaining in the whole soil profile after 90 daa was 25.4% and 39.9% for diuron, with no effect of additional rainfall amount. at 340 daa the amount of simazine in the whole soil profile corresponded to 13.2% of the initial amount applied, being diuron more persistent with 21.5% of the initial herbicide applied. the high movement in soil of both herbicides could be due to a non-equilibrium sorption process explained by preferential flow, low kd and high desorption.
Inter-Instrument Comparison of Bioimpedance Spectroscopic Analysers
L.C. Ward
The Open Medical Devices Journal , 2009, DOI: 10.2174/1875181400901010003]
Abstract: Three commercially available bioimpedance spectroscopy analysers were compared for technical performance and for their design purpose of prediction of body composition. All three analysers were electronically stable, remaining in calibration over a year, and provided highly reproducible (coefficients of variation < 0.5%) and accurate (within 0.5% of component values) measurements of impedances of a test circuit. Whole body impedances in humans were highly correlated between all three instruments although significant biases between instruments were observed, particularly for the measurement of intracellular resistance. However, when the measured impedances, and using instrument-specific resistivity coefficients, were used to predict fat-free mass of the subjects, the difference between instruments was approximately 1.7 kg fat-free mass, a value comparable with that observed for the error associated with reference methods such as multi-compartment models of body composition. It is concluded that, with appropriate regard to standardisation of measurement protocol, all three analysers are suitable for their design purpose of estimating body composition in humans.
The role of causal criteria in causal inferences: Bradford Hill's "aspects of association"
Ward Andrew C
Epidemiologic Perspectives and Innovations , 2009, DOI: 10.1186/1742-5573-6-2
Abstract: As noted by Wesley Salmon and many others, causal concepts are ubiquitous in every branch of theoretical science, in the practical disciplines and in everyday life. In the theoretical and practical sciences especially, people often base claims about causal relations on applications of statistical methods to data. However, the source and type of data place important constraints on the choice of statistical methods as well as on the warrant attributed to the causal claims based on the use of such methods. For example, much of the data used by people interested in making causal claims come from non-experimental, observational studies in which random allocations to treatment and control groups are not present. Thus, one of the most important problems in the social and health sciences concerns making justified causal inferences using non-experimental, observational data. In this paper, I examine one method of justifying such inferences that is especially widespread in epidemiology and the health sciences generally – the use of causal criteria. I argue that while the use of causal criteria is not appropriate for either deductive or inductive inferences, they do have an important role to play in inferences to the best explanation. As such, causal criteria, exemplified by what Bradford Hill referred to as "aspects of [statistical] associations", have an indispensible part to play in the goal of making justified causal claims.
Screening for alcohol use disorders in HIV patients
C Ward,S Ahmad
Journal of the International AIDS Society , 2012, DOI: 10.7448/ias.15.6.18160
Abstract: Many chronic health conditions have been linked to alcohol consumption, as well as excess morbidity, mortality and an increased financial burden on the National Health Service (NHS). The British HIV Association (BHIVA) recommends that HIV patients be asked about alcohol due to its effect on adherence to antiretroviral therapy. National Institute of Health and Clinical Excellence (NICE) guidelines recommend screening for alcohol use disorders in patients attending genitourinary medicine (GUM) clinics. In this study we looked at the use of a screening tool for alcohol use disorders in HIV patients in a metropolitan city. We assessed HIV patients over a 6-month period for alcohol use disorders using the AUDIT-C questionnaire. Patients with a score >4 were identified as higher risk and provided with brief advice about alcohol and offered written information and support. Demographic data was collected along with hepatitis B and C status, information on sexually transmitted infection (STI) testing and diagnosis. 352 patients were reviewed with a mean age of 41. 297 (84.4%) patients were male, 235 (66.8%) were white British and 251 (71.3%) were men who have sex with men (MSM). 277 (78.7%) patients were on antiretroviral therapy with 254 (91.7%) of these having an undetectable viral load. Alcohol use disorders were assessed using the AUDIT-C score in 332 (94.3%) patients with no patient declining assessment. 166 (50%) patients had an AUDIT-C score >4 signifying higher risk. Alcohol advice was provided to 161 (97%) of these patients and a Drink Smart guide offering advice on alcohol self help offered to 103 (64%) patients and accepted by 45 (43.7%). An opportunistic STI screen was offered to 258 (73.3%) patients on that visit in line with best practice guidelines and was accepted by 83 (32.2%). 25 infections were found in 20 patients, of which 13 (65%) had AUDIT-C scores >4. There were 8 active hepatitis C co-infected patients of which 3 had an AUDIT-C score >4 and 12 chronic hepatitis B co-infected patients with 3 having an AUDIT-C score >4. Our results show that screening for alcohol use disorders using the AUDIT-C questionnaire has high acceptability among HIV patients; however the data is biased to Caucasian MSM. Alcohol use has been shown to exacerbate liver damage in patients with chronic hepatitis, increase the likelihood of STI acquisition and compromise immunity. It is therefore important to screen for and quantify alcohol use as part of routine HIV clinical practice.
Cyclic A_\infty Structures and Deligne's Conjecture
Benjamin C. Ward
Mathematics , 2011, DOI: 10.2140/agt.2012.12.1487
Abstract: First we describe a class of homotopy Frobenius algebras via cyclic operads which we call cyclic $A_\infty$ algebras. We then define a suitable new combinatorial operad which acts on the Hochschild cochains of such an algebra in a manner which encodes the homotopy BV structure. Moreover we show that this operad is equivalent to the cellular chains of a certain topological (quasi)-operad of CW complexes whose constituent spaces form a homotopy associative version of the Cacti operad of Voronov. These cellular chains thus constitute a chain model for the framed little disks operad, proving a cyclic $A_\infty$ version of Deligne's conjecture. This chain model contains the minimal operad of Kontsevich and Soibelman as a suboperad and restriction of the action to this suboperad recovers their results in the unframed case. Additionally this proof recovers the work of Kaufmann in the case of a strict Frobenius algebra. We then extend our results to cyclic $A_\infty$ categories, with an eye toward the homotopy BV structure present on the Hochschild cochains of the Fukaya category of a suitable symplectic manifold.
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