85 research outputs found
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What motivates New Brunswick employees to sue their employers, and does the law offer a relevant response?
Disputes between employers and employees often have damaging consequences, including employee claiming that leads to lengthy, expensive and time-intensive legal processes. It is questionable if employee-initiated legal claims always effectively respond to the concerns on which they are based. This study explores the motivations of individuals in New Brunswick, Canada in their decisions to consider legal action against their employers. It argues that more attention should be paid to the reasons why individuals elect to pursue legal remedies and to the exploration of means for avoiding litigation or addressing the resolution of such differences in more effective and efficient ways. Adopting a multiple operationism methodology, this study has explored the motives of New Brunswick employees who consider advancing legal claims against their employers and has considered the procedural and remedial capacity of the existing common law and statutory employment law system to effectively respond to those motives. In addition, the study has examined the responsiveness of alternate justice models to the employee concerns that frequently result in the initiation of legal claims
Mesenchymal Stem Cells Prevent the Rejection of Fully Allogenic Islet Grafts by the Immunosuppressive Activity of Matrix Metalloproteinase-2 and -9
OBJECTIVE Mesenchymal stem cells (MSCs) are known to be capable of suppressing immune responses, but the molecular mechanisms involved and the therapeutic potential of MSCs remain to be clarified.
RESEARCH DESIGN AND METHODS We investigated the molecular mechanisms underlying the immunosuppressive effects of MSCs in vitro and in vivo.
RESULTS Our results demonstrate that matrix metalloproteinases (MMPs) secreted by MSCs, in particular MMP-2 and MMP-9, play an important role in the suppressive activity of MSCs by reducing surface expression of CD25 on responding T-cells. Blocking the activity of MMP-2 and MMP-9 in vitro completely abolished the suppression of T-cell proliferation by MSCs and restored T-cell expression of CD25 as well as responsiveness to interleukin-2. In vivo, administration of MSCs significantly reduced delayed-type hypersensitivity responses to allogeneic antigen and profoundly prolonged the survival of fully allogeneic islet grafts in transplant recipients. Significantly, these MSC-mediated protective effects were completely reversed by in vivo inhibition of MMP-2 and MMP-9.
CONCLUSIONS We demonstrate that MSCs can prevent islet allograft rejection leading to stable, long-term normoglycemia. In addition, we provide a novel insight into the mechanism underlying the suppressive effects of MSCs on T-cell responses to alloantigen.</p
Determination of the Molecular Basis for a Limited Dimorphism, N417K, in the Plasmodium vivax Duffy-Binding Protein
Invasion of human red blood cells by Plasmodium merozoites is vital for replication and survival of the parasite and, as such, is an attractive target for therapeutic intervention. Merozoite invasion is mediated by specific interactions between parasite ligands and host erythrocyte receptors. The P. vivax Duffy-binding protein (PvDBP) is heavily dependent on the interaction with the human Duffy blood group antigen/receptor for chemokines (DARC) for invasion. Region II of PvDBP contains many allelic polymorphisms likely to have arisen by host immune selection. Successful vaccine development necessitates a deeper understanding of the role of these polymorphisms in both parasite function and evasion of host immunity. A 3D structure of the homologous P. knowlesi DBP predicts that most variant residues are surface-exposed, including N417K, which is a dimorphic residue change that has previously been shown to be part of a linked haplotype that alters DBP sensitivity to inhibitory antibody. In natural isolates only two residues are found at this site, asparagine (N) and lysine (K). Site-directed mutagenesis of residue 417 was used to create a panel of 20 amino acid variants that were then examined for their binding phenotype and response to immune sera. Our results suggest that the observed dimorphism likely arose due to both structural requirements and immune selection pressure. To our knowledge, this is the first exhaustive examination of this kind of the role of a single amino acid residue in antigenic character and binding ability. Our results demonstrate that a single amino acid substitution can dramatically alter both the ability of the PvDBP to bind to human erythrocytes and its antigenic character
Tumour necrosis factor gene polymorphism: a predictive factor for the development of post-transplant lymphoproliferative disease
Epstein–Barr virus-positive post-transplant lymphoproliferative disease (PTLD) is a potentially lethal complication of iatrogenic immunosupression after transplantation. Predicting the development of PTLD allowing early and effective intervention is therefore of importance. Polymorphisms within cytokine genes are implicated in susceptibility to, and progression of, disease however the published data are often conflicting. We undertook investigation of polymorphic alleles within cytokine genes in PTLD and non-PTLD transplant cohorts to determine risk factors for disease.
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Methods:
SSP-PCR was used to analyse single nucleotide polymorphism within tumour necrosis factor (TNF)-α, interleukin- 1, -6, -10 and lymphotoxin-α genes. The TNF-α levels were measured by standard enzyme-linked immuno-absorbant assay.
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Results:
We show an association between variant alleles within the TNF-α promoter (−1031C (<i>P</i>=0.005)); −863A (<i>P</i>=0.0001) and TNF receptor I promoter regions (−201T (<i>P</i>=0.02)); −1135C (<i>P</i>=0.03) with the development of PTLD. We also show an association with TNF-α promoter haplotypes with haplotype-3 significantly increased (<i>P</i>=0.0001) and haplotype-1 decreased (P=0.02) in PTLD patients compared to transplant controls. Furthermore, we show a significant increase (<i>P</i>=0.02) in the level of TNF-α in PTLD patient plasma (range 0–97.97 pg ml<sup>−1</sup>) compared to transplant controls (0–8.147 pg ml<sup>−1</sup>), with the highest levels found in individuals carrying the variant alleles.
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Conclusion:
We suggest that genetic variation within TNF-α loci and the level of plasma cytokine could be used as a predictive risk factor for the development of PTLD
Latency Associated Peptide Has In Vitro and In Vivo Immune Effects Independent of TGF-β1
Latency Associated Peptide (LAP) binds TGF-β1, forming a latent complex.
Currently, LAP is presumed to function only as a sequestering agent for active
TGF-β1. Previous work shows that LAP can induce epithelial cell
migration, but effects on leukocytes have not been reported. Because of the
multiplicity of immunologic processes in which TGF-β1 plays a role, we
hypothesized that LAP could function independently to modulate immune responses.
In separate experiments we found that LAP promoted chemotaxis of human monocytes
and blocked inflammation in vivo in a murine model of the
delayed-type hypersensitivity response (DTHR). These effects did not involve
TGF-β1 activity. Further studies revealed that disruption of specific
LAP-thrombospondin-1 (TSP-1) interactions prevented LAP-induced responses. The
effect of LAP on DTH inhibition depended on IL-10. These data support a novel
role for LAP in regulating monocyte trafficking and immune modulation
Development of a novel motivational interviewing (MI) informed peer-support intervention to support mothers to breastfeed for longer
Background: Many women in the UK stop breastfeeding before they would like to, and earlier than is recommended by the World Health Organization (WHO). Given the potential health benefits for mother and baby, new ways of supporting women to breastfeed for longer are required. The purpose of this study was to develop and characterise a novel Motivational Interviewing (MI) informed breastfeeding peer-support intervention. Methods: Qualitative interviews with health professionals and service providers (n=14), and focus groups with mothers (n=14), fathers (n=3), and breastfeeding peer-supporters (n=15) were carried out to understand experiences of breastfeeding peer-support and identify intervention options. Data were audio-recorded, transcribed, and analysed thematically. Consultation took place with a combined professional and lay Stakeholder Group (n=23). The Behaviour Change Wheel (BCW) guided intervention development process used the findings of the qualitative research and stakeholder consultation, alongside evidence from existing literature, to identify: the target behaviour to be changed; sources of this behaviour based on the Capability, Opportunity and Motivation (COM-B) model; intervention functions that could alter this behaviour; and; mode of delivery for the intervention. Behaviour change techniques included in the intervention were categorised using the Behaviour Change Technique Taxonomy Version 1 (BCTTv1). Results: Building knowledge, skills, confidence, and providing social support were perceived to be key functions of breastfeeding peer-support interventions that aim to decrease early discontinuation of breastfeeding. These features of breastfeeding peer-support mapped onto the BCW education, training, modelling and environmental restructuring intervention functions. Behaviour change techniques (BCTTv1) included social support, problem solving, and goal setting. The intervention included important inter-personal relational features (e.g. trust, honesty, kindness), and the BCTTv1 needed adaptation to incorporate this. Conclusions: The MI-informed breastfeeding peer-support intervention developed using this systematic and user-informed approach has a clear theoretical basis and well-described behaviour 3 change techniques. The process described could be useful in developing other complex interventions that incorporate peer-support and/or MI
Male circumcision and prevalence of genital human papillomavirus infection in men : a multinational study
Background: Accumulated evidence from epidemiological studies and more recently from randomized controlled trials suggests that male circumcision (MC) may substantially protect against genital HPV infection in men. The purpose of this study was to assess the association between MC and genital HPV infection in men in a large multinational study. Methods: A total of 4072 healthy men ages 18-70 years were enrolled in a study conducted in Brazil, Mexico, and the United States. Enrollment samples combining exfoliated cells from the coronal sulcus, glans penis, shaft, and scrotum were analyzed for the presence and genotyping of HPV DNA by PCR and linear array methods. Prevalence ratios (PR) were used to estimate associations between MC and HPV detection adjusting for potential confounders. Results: MC was not associated with overall prevalence of any HPV, oncogenic HPV types or unclassified HPV types. However, MC was negatively associated with non-oncogenic HPV infections (PR 0.85, 95% confident interval: 0.76-0.95), in particular for HPV types 11, 40, 61, 71, and 81. HPV 16, 51, 62, and 84 were the most frequently identified genotypes regardless of MC status. Conclusions: This study shows no overall association between MC and genital HPV infections in men, except for certain non-oncogenic HPV types for which a weak association was found. However, the lack of association with MC might be due to the lack of anatomic site specific HPV data, for example the glans penis, the area expected to be most likely protected by MC
Knockout of the dhfr-ts Gene in Trypanosoma cruzi Generates Attenuated Parasites Able to Confer Protection against a Virulent Challenge
Chagas disease is the clinical manifestation of the infection produced by the flagellate parasite Trypanosoma cruzi and currently there is no vaccine to prevent this disease. Therefore, different approaches or alternatives are urgently needed. Vaccination with live attenuated parasites has been used effectively in mice to reduce parasitemia and histological damage. However, the use of live parasites as inmunogens is controversial due to the risk of reversion to a virulent phenotype. In this work we genetically manipulated a naturally attenuated strain of T. cruzi in order to produce parasites with impaired replication and infectivity, using the mutation as a safety device against reversion to virulence. We show that genetically modified parasites display a lower proliferation rate in vitro and induced almost undetectable levels of T. cruzi specific CD8+ T cells when injected in mice. Furthermore, the immune response induced by these live mutant parasites confers protection against a subsequent virulent infection even a year after the original immunization
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