992 resultados para RADIATION PROTECTION
Resumo:
Accumulating evidence suggests that polymorphisms in Toll-like receptors (TLRs) influence the pathogenesis of mycobacterial infections, including leprosy, a disease whose manifestations depend on host immune responses. Polymorphisms in TLR2 are associated with an increased risk of reversal reaction, but not susceptibility to leprosy itself. We examined whether polymorphisms in TLR4 are associated with susceptibility to leprosy in a cohort of 441 Ethiopian leprosy patients and 197 healthy controls. We found that two single nucleotide polymorphisms (SNPs) in TLR4 (896G>A [D299G] and 1196C>T [T399I]) were associated with a protective effect against the disease. The 896GG, GA and AA genotypes were found in 91.7, 7.8 and 0.5% of leprosy cases versus 79.9, 19.1 and 1.0% of controls, respectively (odds ratio [OR] = 0.34, 95% confidence interval [CI] 0.20-0.57, P < 0.001, additive model). Similarly, the 1196CC, CT and TT genotypes were found in 98.1, 1.9 and 0% of leprosy cases versus 91.8, 7.7 and 0.5% of controls, respectively (OR = 0.16, 95% CI 0.06--.40, P < 0.001, dominant model). We found that Mycobacterium leprae stimulation of monocytes partially inhibited their subsequent response to lipopolysaccharide (LPS) stimulation. Our data suggest that TLR4 polymorphisms are associated with susceptibility to leprosy and that this effect may be mediated at the cellular level by the modulation of TLR4 signalling by M. leprae.
Resumo:
Four standard radiation qualities (from RQA 3 to RQA 9) were used to compare the imaging performance of a computed radiography (CR) system (general purpose and high resolution phosphor plates of a Kodak CR 9000 system), a selenium-based direct flat panel detector (Kodak Direct View DR 9000), and a conventional screen-film system (Kodak T-MAT L/RA film with a 3M Trimax Regular screen of speed 400) in conventional radiography. Reference exposure levels were chosen according to the manufacturer's recommendations to be representative of clinical practice (exposure index of 1700 for digital systems and a film optical density of 1.4). With the exception of the RQA 3 beam quality, the exposure levels needed to produce a mean digital signal of 1700 were higher than those needed to obtain a mean film optical density of 1.4. In spite of intense developments in the field of digital detectors, screen-film systems are still very efficient detectors for most of the beam qualities used in radiology. An important outcome of this study is the behavior of the detective quantum efficiency of the digital radiography (DR) system as a function of beam energy. The practice of users to increase beam energy when switching from a screen-film system to a CR system, in order to improve the compromise between patient dose and image quality, might not be appropriate when switching from screen-film to selenium-based DR systems.
Resumo:
Starting in February 1994, 20 patients (pt) with a median age of 50 years(range 41-63) from 7 European centers have been included. Completedata were obtained in 16 patients so far. CPC were mobilized with chemo(Epirubicine 75 mg/m2 /d, 01 + 02) followed by G-CSF 5 p.gfkg/d for14 days. HD chemo consisted in 3 sequential courses of ICE regimen(UOs. 10 g/m2 , Carbo. 1200 mg/m2 and Etop. 1200 mg/m2 ) underCPC protection and G-CSF 5 p.g/kg/d. Out of the 16 pt, 12 completedfull program (3 cycles). One pt died of septic shock before receivingany ICE course. One pt died during the first ICE of renal insufficiency.Two pt had only 2 courses because of toxicity. Among the 16 pt, responserate (RR) was: 7 CR, 6 PR, 1 PO; 3 pt are not evaluable dueto early withdrawal (overall RR: 13/16 = 81 %). Thirty-nine cycles ofHD chemo were given with a median hematological recovery of 9 days(range 7-12) until neutro. counts> 1.0 x 109 /1 and 9 days (range 717)until thrombo. > 20 x 109 /1. No cumulative, hematological toxicitywas seen. Accrual of patients is still ongoing and updated results will bepresented.
Resumo:
Public providers have no financial incentive to respect their legal obligation to exempt the poor from user fees. Health Equity Funds (HEFs) aim to make exemptions effective by giving NGOs responsibility for assessing eligibility and compensating providers for lost revenue. We use the geographic spread of HEFs in Cambodia to identify their impact on out-of-pocket (OOP) payments. Among households with some OOP payment, HEFs reduce the amount by 29%, on average. The effect is larger for households that are poorer, mainly use public health care and live closer to a district hospital. HEFs are more effective in reducing OOP payments when they are operated by a NGO, rather than the government, and when they operate in conjunction with the contracting of public health services. HEFs reduce households' health-related debt by around 25%, on average. There is no significant impact on non-medical consumption and health care utilisation
Resumo:
RESUME : Actuellement la brachythérapie endovasculaire reste le seul traitement efficace pour la resténose intrastent. Malgré ceci, la limitation majeure de cette technique est la resténose aux extrémités du stent (effet de bord) due à une couverture incomplète par la source radioactive (geographical miss). Le ballon coupant et qui ne glisse pas pourrait limiter le barotraumatisme engendré par la dilatation et qui avec la diminution de la radiation aux extrémités de la source radioactive, est à la base du geographical miss. Cette étude prospective a pour but d'examiner l'efficacité du traitement de la resténose intrastent par la combinaison d'angioplastie avec cutting ballon et β - irradiation. Le registre « Radiation in Europe NOvoste » (RENO) inclut tous les patients traités par β - irradiation coronaire avec le système Beta-CathTM System (Novoste Corporation, Brussels, Belgium) n'ayant pas été inclus dans une autre étude randomisée. Un premier sous-groupe de ces patients (groupe 1, n=166), représente les patients traités par cutting ballon et β - irradiation intra coronaire. Ce groupe a été défini d'une manière prospective et les résultats cliniques à 6 mois ont été comparés par rapport aux autres patients qui ont reçu un traitement par dilatation coronaire conventionnelle et β - irradiation (groupe 2, n=712). A 6 mois de suivi, on a retrouvé une différence significative entre les 2 groupes par rapport à la nécessité d'une nouvelle revascularisation du vaisseau préalablement traité (10,2% de récidive dans le groupe 1 contre 16,6 % dans le groupe 2 , p=0,04). Le nombre d'événements cardiaques majeurs (mortalité, infarctus du myocarde et revascularisation) a également été diminué de manière significative (10,8% contre 19,2% ; />=0,01). Cette observation a été confirmée par une analyse multivariée qui indique un risque diminué pour les événements cardiaques majeurs à 6 mois, (rapport de côtes : 0,49 ; intervalle de confiance 0,27-0,88 ; p=0,02). Comparé à l'angioplastie coronarienne avec ballon conventionnel, l'utilisation de cutting ballon avant la β - irradiation dans le traitement de la resténose intrastent démontre une meilleure évolution clinique à 6 mois. ABSTRACT: At present, vascular brachytherapy is the only efficient therapy for in-stent restenosis. Nevertheless edge restenosis often relat¬ed to geographical miss has been identified as a major limitation of the technique. The non-slippery cutting balloon has the potential to limit vascular barotraumas which, together with low-dose irradiation at both ends of the radioactive source, are the prerequisite for geographical miss. This prospective study aimed to examine the efficacy of combining cut¬ting balloon angioplasty and brachytherapy for in-stent restenosis. The Radiation in Europe NOvoste (RENO) registry prospectively tracked all patients who had been treated by coronary β-radiation with the Beta-CathTM System (Novoste Corporation. Brussels, Belgium) but were not included in a randomized radiation trial, A subgroup of patients with in-stent restenosis treated by cutting balloon angioplasty and coronary β-radiation (group 1, n = 166) was prospectively defined, and clinical outcomes of patients at 6 months were compared with those of patients treated by conventional angioplasty and coronary β -radiation (group 2, n = 712). At 6-month follow-up, there was a significant difference between groups 1 and 2 in- target vessel revascularization (10.2% versus 16.6% respectively; p = 0.04) and in the incidence of major adverse clinical events (MACE) including, death, myocardial infarction, and revascularization (10.8% versus 19.2%; p= 0.01). This observation was confirmed by a multivariate analysis indicating a. lower risk for MACE at 6 months (odds ratio: 0.49; confidence intervals: 0.27-0.88; p = 0.02). Compared to conventional angioplasty, cutting balloon angio¬plasty prior to coronary beta-radiation with the Beta-CathTM System seems to improve the 6-month clinical outcome in patients with in-stent restenosis.
Resumo:
Partial cleavage of p120 RasGAP by caspase-3 in stressed cells generates an N-terminal fragment, called fragment N, which activates an anti-apoptotic Akt-dependent survival response. Akt regulates several effectors but which of these mediate fragment N-dependent cell protection has not been defined yet. Here we have investigated the role of mTORC1, Bad, and survivin in the capacity of fragment N to protect cells from apoptosis. Neither rapamycin, an inhibitor of mTORC1, nor silencing of raptor, a subunit of the mTORC1 complex, altered the ability of fragment N from inhibiting cisplatin- and Fas ligand-induced death. Cells lacking Bad, despite displaying a stronger resistance to apoptosis, were still protected by fragment N against cisplatin-induced death. Fragment N was also able to protect cells from Fas ligand-induced death in conditions where Bad plays no role in apoptosis regulation. Fragment N expression in cells did neither modulate survivin mRNA nor its protein expression. Moreover, the expression of cytoplasmic survivin, known to exert anti-apoptotic actions in cells, still occurred in UV-B-irradiated epidermis of mouse expressing a caspase-3-resistant RasGAP mutant that cannot produce fragment N. Additionally, survivin function in cell cycle progression was not affected by fragment N. These results indicate that, taken individually, mTOR, Bad, or Survivin are not required for fragment N to protect cells from cell death. We conclude that downstream targets of Akt other than mTORC1, Bad, or survivin mediate fragment N-induced protection or that several Akt effectors can compensate for each other to induce the pro-survival fragment N-dependent response.
Resumo:
Inflammasome-mediated IL-1beta production is central to the innate immune defects that give rise to certain autoinflammatory diseases and may also be associated with the generation of IL-17-producing CD4(+) T (Th17) cells that mediate autoimmunity. However, the role of the inflammasome in driving adaptive immunity to infection has not been addressed. In this article, we demonstrate that inflammasome-mediated IL-1beta plays a critical role in promoting Ag-specific Th17 cells and in generating protective immunity against Bordetella pertussis infection. Using a murine respiratory challenge model, we demonstrated that the course of B. pertussis infection was significantly exacerbated in IL-1R type I-defective (IL-1RI(-/-)) mice. We found that adenylate cyclase toxin (CyaA), a key virulence factor secreted by B. pertussis, induced robust IL-1beta production by dendritic cells through activation of caspase-1 and the NALP3-containing inflammasome complex. Using mutant toxins, we demonstrate that CyaA-mediated activation of caspase-1 was not dependent on adenylate cyclase enzyme activity but was dependent on the pore-forming capacity of CyaA. In addition, CyaA promoted the induction of Ag-specific Th17 cells in wild-type but not IL-1RI(-/-) mice. Furthermore, the bacterial load was enhanced in IL-17-defective mice. Our findings demonstrate that CyaA, a virulence factor from B. pertussis, promotes innate IL-1beta production via activation of the NALP3 inflammasome and, thereby, polarizes T cell responses toward the Th17 subtype. In addition to its known role in subverting host immunity, our findings suggest that CyaA can promote IL-1beta-mediated Th17 cells, which promote clearance of the bacteria from the respiratory tract.
Resumo:
ABSTRACT: BACKGROUND: Adaptive radiation is the process by which a single ancestral species diversifies into many descendants adapted to exploit a wide range of habitats. The appearance of ecological opportunities, or the colonisation or adaptation to novel ecological resources, has been documented to promote adaptive radiation in many classic examples. Mutualistic interactions allow species to access resources untapped by competitors, but evidence shows that the effect of mutualism on species diversification can greatly vary among mutualistic systems. Here, we test whether the development of obligate mutualism with sea anemones allowed the clownfishes to radiate adaptively across the Indian and western Pacific oceans reef habitats. RESULTS: We show that clownfishes morphological characters are linked with ecological niches associated with the sea anemones. This pattern is consistent with the ecological speciation hypothesis. Furthermore, the clownfishes show an increase in the rate of species diversification as well as rate of morphological evolution compared to their closest relatives without anemone mutualistic associations. CONCLUSIONS: The effect of mutualism on species diversification has only been studied in a limited number of groups. We present a case of adaptive radiation where mutualistic interaction is the likely key innovation, providing new insights into the mechanisms involved in the buildup of biodiversity. Due to a lack of barriers to dispersal, ecological speciation is rare in marine environments. Particular life-history characteristics of clownfishes likely reinforced reproductive isolation between populations, allowing rapid species diversification.
Resumo:
RESUME La radiothérapie est utilisée avec succès pour le traitement d'un grand nombre de pathologies tumorales (1). Cependant, les récidives post-actiniques sont associées à un risque accru de développer des métastases régionales et à distance (2, 3). La prise en charge de ce type de patients demeure insatisfaisante à l'heure actuelle, principalement parce que les mécanismes physio-pathologiques sous- sous-jacents restent mal compris. Etant donné le rôle primordial du stroma dans la progression tumorale (4) et l'importance des effets de la radiothérapie sur le micro-environnement des tumeurs (5), nous avons émis l'hypothèse que la radiothérapie pouvait engendrer des modifications stromales susceptibles de contribuer à l'émergence d'un phénotype tumoral plus agressif. Nous avons observé que l'exposition préalable d'un environnement tumoral à des radiations ionisantes engendre une inhibition locale et à long terme de l'angiogenèse. Cette inhibition conduit à la création d'un environnement tumoral hypoxique favorisant l'invasion et la métastatisation tumorale. Les mécanismes sous-jacents impliquent l'activation de gènes prométastatiques sous le contrôle du facteur de transcription HIF-1, ainsi que la sélection hypoxique de cellules hautement invasives et métastatiques. Par des analyses de profile d'expression génétique ainsi que par des analyses fonctionnelles, nous avons identifié la protéine matri-cellulaire CYR61 ainsi que ses partenaires d'interaction, les intégrines aVb5/aVb3, comme médiateurs importants de ces effets. De plus, une corrélation significative a également été trouvée entre le niveau d'expression de CYR61 et le taux d'hypoxie dans un grand nombre de carcinomes mammaires chez l'humain. Une association a aussi été observée entre le niveau d'expression de CYR61 et le pronostic de patientes souffrant d'un cancer du sein traité par chimiothérapie adjuvante. Globalement ces résultats identifient l'interaction entre la protéine CYR61 et ses récepteurs aVb5/aVb3 comme un mécanisme important du processus de métastatisation et en font une cible thérapeutique potentielle pour le traitement de patients souffrant d'une récidive tumorale après un traitement de radiothérapie. Finalement, bien que l'inhibition de l'angiogenèse soit locale dans ce cas particulier, nos résultats justifient une surveillance particulière des patients souffrant d'une pathologie tumorale et étant au bénéfice d'un traitement inhibiteur de l'angiogenèse. SUMMARY Radiotherapy is successfully used to treat a large variety of tumours (1 ). However, cancer patients experiencing local recurrent disease after radiation therapy are at increased risk of developing regional and distant metastasis (2, 3). The clinical management of this condition represents a difficult and challenging issue, mainly because the underlying physio-pathological mechanisms remain poorly understood. Given the well established role of the tumour stroma in promoting cancer progression (4) and since radiotherapy is known to persistently alter the tumour microenvironment (5), we hypothesized that ionising radiations may generate stromal modifications contributing to the metastatic spread of relapsing tumours. Here, we report that irradiation of the prospective tumour microenvironment promotes tumour invasion and metastasis through a mechanism of local and sustained impairment of angiogenesis leading to both HIF-1 dependent activation of pro-metastatic genes and hypoxia-mediated selection of highly metastatic tumour cell variants. Through gene expression profiling and functional experiments, we identified the matricellular signalling protein CYR61 and its interaction partners aVb5/ aVb3 integrins as critical mediators of these effects. Furthermore, we found a significant correlation between CYR61 expression and the hypoxic status of a large number of human mammary carcinomas. A positive correlation between increased levels of CYR61 expression and shorter relapse free survival was also identified in breast cancer patients treated with adjuvant chemotherapy. Together, these results identify CYR61 and aVb5/aVb3 integrins as critical mediators of metastasis and potential therapeutic targets to improve outcome in patients with post-radiation tumour recurrences. Finally, although inhibition of angiogenesis is local in this setting, our data warrant close monitoring of tumour progression in patients under anti-angiogenic therapy.
Resumo:
The Attorney General’s Consumer Protection Division receives hundreds of calls and consumer complaints every year. Follow these tips to avoid unexpected expense and disappointments. This record is about: "Credit Card Protection Plans" -- Paying for What You Can Do for Free?