169 resultados para Swiss mice
Resumo:
Allergic contact dermatitis is the most frequent occupational disease in industrialized countries. It is caused by CD8(+) T cell-mediated contact hypersensitivity (CHS) reactions triggered at the site of contact by a variety of chemicals, also known as weak haptens, present in fragrances, dyes, metals, preservatives, and drugs. Despite the myriad of potentially allergenic substances that can penetrate the skin, sensitization is relatively rare and immune tolerance to the substance is often induced by as yet poorly understood mechanisms. Here we show, using the innocuous chemical 2,4-dinitrothiocyanobenzene (DNTB), that cutaneous immune tolerance in mice critically depends on epidermal Langerhans cells (LCs), which capture DNTB and migrate to lymph nodes for direct presentation to CD8(+) T cells. Depletion and adoptive transfer experiments revealed that LCs conferred protection from development of CHS by a mechanism involving both anergy and deletion of allergen-specific CD8(+) T cells and activation of a population of T cells identified as ICOS(+)CD4(+)Foxp3(+) Tregs. Our findings highlight the critical role of LCs in tolerance induction in mice to the prototype innocuous hapten DNTB and suggest that strategies targeting LCs might be valuable for prevention of cutaneous allergy.
Resumo:
This study defines a critical role for Btk in regulating TLR4-induced crosstalk between antigen presenting cells (APCs) and natural killer (NK) cells. Reduced levels of IL-12, IL-18 and IFN-? were observed in Btk-deficient mice and ex vivo generated macrophages and dendritic cells (DCs) following acute LPS administration, whilst enhanced IL-10 production was observed. In addition, upregulation of activation markers and antigen presentation molecules on APCs was also impaired in the absence of Btk. APCs, by virtue of their ability to produce IL-12 and IL-18, are strong inducers of NK-derived IFN-?. Co-culture experiments demonstrate that Btk-deficient DCs were unable to drive wild-type or Btk-deficient NK cells to induce IFN-? production, whereas these responses could be restored by exogenous administration of IL-12 and IL-18. Thus Btk is a critical regulator of APC-induced NK cell activation by virtue of its ability to regulate IL-12 and IL-18 production in response to acute LPS administration.
Resumo:
PURPOSE. This study was conducted to evaluate whether regions of the retinal neuropile become hypoxic during periods of high oxygen consumption and whether depletion of the outer retina reduces hypoxia and related changes in gene expression.
METHODS. Retinas from rhodopsin knockout (Rho(-/-)) mice were evaluated along with those of wild-type (WT) control animals. Retinas were also examined at the end of 12-hour dark or light periods, and a separate group was treated with L-cis-diltiazem at the beginning of a 12-hour dark period. Hypoxia was assessed by deposition of hypoxyprobe (HP) and HP-protein adducts were localized by immunohistochemistry and quantified using ELISA. Also, hypoxia-regulated gene expression and transcriptional activity were assessed alongside vascular density.
RESULTS. Hypoxia was observed in the inner nuclear and ganglion cell layers in WT retina and was significantly reduced in Rho (-/-) mice (P < 0.05). Retinal hypoxia was significantly increased during dark adaptation in WT mice (P < 0.05), whereas no change was observed in Rho(-/-) or with L-cis-diltiazem-treated WT mice. Hypoxia-inducible factor (HIF)-1 alpha DNA-binding and VEGF mRNA expression in Rho(-/-) retina was significantly reduced in unison with outer retinal depletion (P < 0.05). Retina from the Rho(-/-) mice displayed an extensive intraretinal vascular network after 6 months, although there was evidence that capillary density was depleted in comparison with that in WT retinas.
CONCLUSIONS. Relative hypoxia occurs in the inner retina especially during dark adaptation. Photoreceptor loss reduces retinal oxygen usage and hypoxia which corresponds with attenuation of the retinal microvasculature. These studies suggest that in normal physiological conditions and diurnal cycles the adult retina exists in a state of borderline hypoxia, making this tissue particularly susceptible to even subtle reductions in perfusion.
Resumo:
The effect of hypobaric hypoxia on the in vivo binding of misonidazole was investigated in normal mice and mice bearing T50/80 or CA NT mammary carcinomas. After the intraperitoneal injection of radiolabelled misonidazole, mice were randomised to breathe either room air or air at 0.5 atmospheres. The distribution of misonidazole in liver, kidney, heart, spleen and tumour tissue, 24 h later, was studied by scintillation counting and by autoradiography. Significantly higher misonidazole binding occurred in the livers (x2.5), kidneys (x2.4), spleens (x2.9) and hearts (x1.8) of hypoxic mice compared to controls. Hypobaric hypoxia was associated with a greater than four-fold increase in misonidazole binding within T50/80 tumours. However, significantly higher binding was not demonstrated within CA NT tumours after exposure of tumour-bearing animals to hypoxic conditions. In autoradiographs of hypoxic liver, labelling was intense in regions near to hepatic veins but sparse in areas surrounding portal tracts. This pattern was striking and consistent. In hypoxic kidney, labelling was most intense over tubular cells, less intense over glomeruli and sparse in the renal medulla. It is likely that the hepatic and renal cortical distributions of misonidazole binding reflect local oxygen gradients.
Resumo:
Arsenic is accumulated by free-living small mammals, but there is little information on the resultant concentrations in different tissues other than liver and kidney. Such information is important because the severity of toxicological effects may be related to the amount of arsenic accumulated in specific organs, and the availability of arsenic to predators is, in part, dependent on which tissues accumulate arsenic. The objective of this study was to quantify the arsenic concentrations and the percentage of the total body burden (%TBB) accumulated in different body tissues of free-living small mammals and to determine how these factors varied with severity of habitat contamination. Arsenic concentrations were measured in various tissues of wood mice (Apodemus sylvaticus) and bank voles (Clethrionomys glareolus) from a range of arsenic-contaminated sites in southwest Britain. Arsenic concentrations in the gastrointestinal (GI) tract (including contents), liver, kidneys, spleen, lung, femur, and fur of both species varied significantly between sites and were higher in mice and voles from heavily contaminated areas. Heart and brain arsenic concentrations did not vary with degree of environmental contamination. The GI tract and excised carcass contained roughly equal amounts of arsenic and, in sum, comprised 75-85% of the TBB on uncontaminated sites and 90-99% on contaminated sites. Although the excised carcass contains about half of the TBB, its importance in food-chain transfer of arsenic to predators may depend on the bioavailability of arsenic sequestered in fur. In contrast, the GI tract and its contents, provided that it is consumed, will always be a major transfer pathway for arsenic to predators, regardless of the severity of habitat contamination.
Resumo:
Arsenic can be highly toxic to mammals but there is relatively little information on its transfer to and uptake by free-living small mammals. The aim of this study was to determine whether intake and accumulation of arsenic by wild rodents living in arsenic-contaminated habitats reflected environmental levels of contamination and varied between species, sexes and age classes. Arsenic concentrations were measured in soil, litter, wood mice (Apodemus sylvaticus) and bank voles (Clethrionomys glareolus) from six sites which varied in the extent to which they were contaminated. Arsenic residues on the most contaminated sites were three and two orders of magnitude above background in soil and litter, respectively. Arsenic concentrations in the stomach contents, liver, kidney and whole body of small mammals reflected inter-site differences in environmental contamination. Wood mice and bank voles on the same sites had similar concentrations of arsenic in their stomach contents and accumulated comparable residues in the liver, kidney and whole body. Female bank voles, but not wood mice, had significantly higher stomach content and liver arsenic concentrations than males. Arsenic concentration in the stomach contents and body tissues did not vary with age class. The bioaccumulation factor (ratio of arsenic concentration in whole body to that in the diet) in wood mice was not significantly different to that in bank voles and was 0.69 for the two species combined, indicating that arsenic was not bioconcentrated in these rodents. Overall, this study has demonstrated that adult and juvenile wood mice and bank voles are exposed to and accumulate similar amounts of arsenic on arsenic-contaminated mine sites and that the extent of accumulation depends upon the level of habitat contamination.
Resumo:
A forest ecosystem was contaminated as a result of a fire involving 600 t of PVC. A wide range of 2,3,7,8-substituted dioxin and furan congeners were elevated (by up to 4-fold) on soil adjacent to the factory compared to a site 200 m from the factory perimeter. Livers of wood mice (Apodemus sylvaticus) caught on these areas were also analysed for dioxins and furans. Toxic equivalents (TEQs) were 9-fold higher in wood mice caught on the site 10 m from the factory perimeter compared with the site 200 m from the perimeter, with individual 2,3,7,8-substituted congeners being elevated by up to 30-fold. Wood mouse liver TEQs were found to be highly correlated with cadmium kidney concentrations, cadmium also being found at elevated concentrations at the accident site. There was also a significant positive correlation between wood mouse liver TEQs and relative liver weights (wet weights expressed as a percentage of total body weight). The results of this study are discussed in the wider context of dioxin contamination in the environment.
Resumo:
Using conjoint choice experiments, we surveyed 473 Swiss homeowners about their preferences for energy efficiency home renovations.We find that homeowners are responsive to the upfront costs of the renovation projects, governmentoffered rebates, savings in energy expenses, time horizon over which such savings would be realized, and thermal comfort improvement. The implicit discount rate is low, ranging from 1.5 to 3%, depending on model specification. This is consistent with Hassett and Metcalf (1993) and Metcalf and Rosenthal (1995), and with the fact that our scenarios contain no uncertainty. Respondents who feel completely uncertain about future energy prices are more likely to select the status quo (no renovations) in any given choice task and weight the costs of the investments more heavily than the financial gains (subsidies and savings on the energy bills). Renovations are more likely when respondents believe that climate change considerations are important determinants of home renovations. Copyright © 2013 by the IAEE. All rights reserved.
Resumo:
PURPOSE:
To investigate the role of the Fractalkine receptor CX3CR1 pathway in oxidative insults-mediated retinal degeneration and immune activation.
METHODS:
A prooxidant, paraquat (0.75 µM) was injected into the vitreous of C57BL/6J, CX3CR1(gpf/+), and CX3CR1(gfp/gfp) mice. Retinal lesions were investigated clinically by topic endoscopic fundus imaging and fluorescence angiography, and pathologically by light- and electron microscopy. Retinal immune gene expression was determined by real-time RT-PCR. Microglial activation and immune cell infiltration were examined by confocal microscopy of retinal flatmounts.
RESULTS:
Intravitreal injection of paraquat (0.75 µM) resulted in acute retinal capillary nonperfusion within 2 days, which improved from 4 days to 4 weeks postinjection (p.i.). Panretinal degeneration was observed at 4 days p.i. and progressed further at 4 weeks p.i. In the absence of CX3CR1, retinal degeneration was exaggerated and was accompanied by increased TNF-a, iNOS, IL-1ß, Ccl2, and Casp-1 gene expression. Confocal microscopy of retinal flatmounts revealed microglial activation and CD44(+)MHC-II(+) monocyte and GR1(+) neutrophil infiltration in paraquat-injected eyes. The number of activated microglia and infiltrating leukocytes was significantly higher in CX3CR1(gfp/gfp) mice than in CX3CR1(gfp/+) mice.
CONCLUSIONS:
Our results suggest that the CX3CR1 signaling pathway may play an important role in controlling retinal inflammation under oxidative and ischemia/reperfusion conditions. In the absence of CX3CR1, uncontrolled retinal inflammation results in exaggerated retinal degeneration.
Resumo:
A comparison of the clinicopathology of European bat lyssavirus (EBLV) types-1 and -2 and of rabies virus was undertaken. Following inoculation of mice at a peripheral site with these viruses, clinical signs of rabies and distribution of virus antigen in the mouse brain were examined. The appearance of clinical signs of disease varied both within and across the different virus species, with variation in incubation periods and weight loss throughout disease progression. The distribution of viral antigen throughout the regions of the brain examined was similar for each of the isolates during the different stages of disease progression, suggesting that antigen distribution was not associated with clinical presentation. However, specific regions of the brain including the cerebellum, caudal medulla, hypothalamus and thalamus, showed notable differences in the proportion of virus antigen positive cells present in comparison to other brain regions suggesting that these areas are important in disease development irrespective of virus species.
Resumo:
The potential therapeutic value of cell-based therapy with mesenchymal stem cells (MSC) has been reported in mouse models of polymicrobial peritoneal sepsis. However, the mechanisms responsible for the beneficial effects of MSC have not been well defined. Therefore, we tested the therapeutic effect of intravenous bone marrow-derived human MSC in peritoneal sepsis induced by gram-negative bacteria. At 48 h, survival was significantly increased in mice treated with intravenous MSC compared with control mice treated with intravenous fibroblasts (3T3) or intravenous PBS. There were no significant differences in the levels of TNF-a, macrophage inflammatory protein 2, or IL-10 in the plasma. However, there was a marked reduction in the number of bacterial colony-forming units of Pseudomonas aeruginosa in the blood of MSC-treated mice compared with the 3T3 and PBS control groups. In addition, phagocytic activity was increased in blood monocytes isolated from mice treated with MSC compared with the 3T3 and PBS groups. Furthermore, levels of C5a anaphylotoxin were elevated in the blood of mice treated with MSC, a finding that was associated with upregulation of the phagocytosis receptor CD11b on monocytes. The phagocytic activity of neutrophils was not different among the groups. There was also an increase in alternately activated monocytes/macrophages (CD163- and CD206-positive) in the spleen of the MSC-treated mice compared with the two controls. Thus intravenous MSC increased survival from gram-negative peritoneal sepsis, in part by a monocyte-dependent increase in bacterial phagocytosis.
Resumo:
Novel 3D plasmonic rolls are fabricated through strain-induced self-rolling of metallic nanopore sheets attached to elastomeric thin films, with optical properties tunable by varying the size and thickness of nanopores, and dynamically by light irradiation.