986 resultados para not odontogenic cyst


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It has frequently been argued that multinational companies are moving towards network forms whereby subsidiaries share different practices with the rest of the company. This paper presents large-scale empirical evidence concerning the extent to which subsidiaries input novel practices into the rest of the multinational. We investigate this in the field of human resources through analysis of a unique international data set in four host countries - Canada, Ireland, Spain and the UK - and address the question of how we can explain variation between subsidiaries in terms of whether they initiate the diffusion of practices to other subsidiaries. The data support the argument that multiple, rather than single, factor explanations are required to more effectively understand the factors promoting or retarding the diffusion of human resource practices within multinational companies. It emerges that national, corporate and functional contexts all matter. More specifically, actors at subsidiary level who seek to initiate diffusion appear to be differentially placed according to their national context, their place within corporate structures and the extent to which the human resource function is internationally networked.

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Stem cells are fundamental to the development of any tissue or organism via their ability to self-renew, which is aided by their unlimited proliferative capacity and their ability to produce fully differentiated offspring, often from multiple lineages. Stems cells are long lived and have the potential to accumulate mutations, including in response to radiation exposure. It is thought that stem cells have the potential to be induced into a cancer stem cell phenotype and that these may play an important role in resistance to radiotherapy. For radiation-induced carcinogenesis, the role of targeted and non-targeted effects is unclear with tissue or origin being important. Studies of genomic instability and bystander responses have shown consistent effects in haematopoietic models. Several models of radiation have predicted that stem cells play an important role in tumour initiation and that bystander responses could play a role in proliferation and self-renewal.

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Purpose: High digestible carbohydrate intakes can induce hyperglycemia and hyperinsulinemia and collectively have been implicated in colorectal tumor development. Our aim was to explore the association between aspects of dietary carbohydrate intake and risk of colorectal adenomas and hyperplastic polyps in a large case–control study.

Methods: Colorectal polyp cases (n = 1,315 adenomas only, n = 566 hyperplastic polyps only and n = 394 both) and controls (n = 3,184) undergoing colonoscopy were recruited between 2003 and 2010 in Nashville, Tennessee, USA. Dietary intakes were estimated by a 108-item food frequency questionnaire. Unconditional logistic regression analysis was applied to determine odds ratios (OR) and corresponding 95 % confidence intervals (CI) for colorectal polyps according to dietary carbohydrate intakes, after adjustment for potential confounders.

Results: No significant associations were detected for risk of colorectal adenomas when comparing the highest versus lowest quartiles of intake for total sugars (OR 1.03; 95 % CI 0.84–1.26), starch (OR 1.01; 95 % CI 0.81–1.26), total or available carbohydrate intakes. Similar null associations were observed between dietary carbohydrate intakes and risk of hyperplastic polyps, or concurrent adenomas and hyperplastic polyps.

Conclusion: In this US population, digestible carbohydrate intakes were not associated with risk of colorectal polyps, suggesting that dietary carbohydrate does not have an etiological role in the early stages of colorectal carcinogenesis.

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We describe the career of John Birks as a pioneering scientist who has, over a career spanning five decades, transformed palaeoecology from a largely descriptive to a rigorous quantitative science relevant to contemporary questions in ecology and environmental change. We review his influence on students and colleagues not only at Cambridge and Bergen Universities, his places of primary employment, but also on individuals and research groups in Europe and North America. We also introduce the collection of papers that we have assembled in his honour. The papers are written by his former students and close colleagues and span many of the areas of palaeoecology to which John himself has made major contributions. These include the relationship between ecology and palaeoecology, late-glacial and Holocene palaeoecology, ecological succession, climate change and vegetation history, the role of palaeoecological techniques in reconstructing and understanding the impact of human activity on terrestrial and freshwater ecosystems and numerical analysis of multivariate palaeoecological data.

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This article explores the contours of continued housing instability among a group of young people who are participants in a qualitative longitudinal study of youth homelessness in Dublin, Ireland, and considers the limitations of the ‘acculturation’ thesis in explaining long-term homelessness amongst the young. Baseline interviews were conducted with 40 young people, aged 14–23 years, in 2004, and follow-up interviews were conducted with 30 research participants successfully ‘tracked’ in 2005–06. By the time of follow-up, 17 of those interviewed had exited homelessness and 13 remained homeless. The article focuses on the latter group with the aim of exploring the processes and experiences associated with their continued homelessness. The findings presented demonstrate the adverse impact of their ongoing movement through emergency services targeting the under-18s, including their greater immersion in drug and criminal lifestyles. A majority had experienced one or more period of incarceration by the time of follow-up, and many were users of adult homeless services. Whilst some dimensions of young people's accounts are suggestive of a process of acculturation to street and hostel life, we argue that their continued homelessness is better explained as a consequence of their ongoing and unresolved transience and, in particular, their continued dependence on emergency hostel accommodation. The implications of the findings for policy and service provision for homeless young people are discussed.

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Ataxia telangiectasia (AT) is a recessive syndrome, including cerebellar degeneration, immunologic defects and cancer predisposition, attributed to mutations in the recently isolated ATM (ataxia telangiectasia, mutated) gene. AT is diagnosed in 1/40,000 to 1/100,000 live births, with carriers calculated to comprise approximately 1% of the population. Studies of AT families have suggested that female relatives presumed to be carriers have a 5 to 8-fold increased risk for developing breast cancer, raising the possibility that germline ATM mutations may account for approximately 5% of all breast cancer cases. The increased risk for breast cancer reported for AT family members has been most evident among younger women, leading to an age-specific relative risk model predicting that 8% of breast cancer in women under age 40 arises in AT carriers, compared with 2% of cases between 40-59 years. To test this hypothesis, we undertook a germ-line mutational analysis of the ATM gene in a population of women with early onset of breast cancer, using a protein truncation (PTT) assay to detect chain-terminating mutations, which account for 90% of mutations identified in children with AT. We detected a heterozygous ATM mutation in 2/202 (1%) controls, consistent with the frequency of AT carriers predicted from epidemiologic studies. ATM mutations were present in only 2/401 (0.5%) women with early onset of breast cancer (P = 0.6). We conclude that heterozygous ATM mutations do not confer genetic predisposition to early onset of breast cancer.

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Jellyfish are highly topical within studies of pelagic food-webs and there is a growing realisation that their role is more complex than once thought. Efforts being made to include jellyfish within fisheries and ecosystem models are an important step forward, but our present understanding of their underlying trophic ecology can lead to their oversimplification in these models. Gelatinous zooplankton represent a polyphyletic assemblage spanning >2,000 species that inhabit coastal seas to the deep-ocean and employ a wide variety of foraging strategies. Despite this diversity, many contemporary modelling approaches include jellyfish as a single functional group feeding at one or two trophic levels at most. Recent reviews have drawn attention to this issue and highlighted the need for improved communication between biologists and theoreticians if this problem is to be overcome. We used stable isotopes to investigate the trophic ecology of three co-occurring scyphozoan jellyfish species (Aurelia aurita, Cyanea lamarckii and C. capillata) within a temperate, coastal food-web in the NE Atlantic. Using information on individual size, time of year and ;delta C-13 and delta N-15 stable isotope values, we examined: (1) whether all jellyfish could be considered as a single functional group, or showed distinct inter-specific differences in trophic ecology; (2) Were size-based shifts in trophic position, found previously in A. aurita, a common trait across species?; (3) When considered collectively, did the trophic position of three sympatric species remain constant over time? Differences in delta N-15 (trophic position) were evident between all three species, with size-based and temporal shifts in delta N-15 apparent in A. aurita and C. capillata. The isotopic niche width for all species combined increased throughout the season, reflecting temporal shifts in trophic position and seasonal succession in these gelatinous species. Taken together, these findings support previous assertions that jellyfish require more robust inclusion in marine fisheries or ecosystem models.

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Environmental context Seaweeds hyperaccumulate the toxic metalloid arsenic, but seemingly achieve detoxification by transformation to arsenosugars. The edible seaweed hijiki is a notable exception because it contains high levels of toxic arsenate and arsenite. Terrestrial plants detoxify arsenic by forming arsenitephytochelatin complexes. The hypothesis that seaweeds also synthesise phytochelatins to bind arsenite as a means of detoxification before arsenosugar synthesis is tested in this investigation. Abstract Phytochelatins (PCs), generic structure [-Glu-Cys]n-Gly, are peptides synthesised by terrestrial plants to bind toxic metal(loid)s such as cadmium and arsenic. Seaweeds are arsenic hyperaccumulators, seemingly achieving detoxification via arsenosugar biosynthesis. Whether seaweeds synthesise PCs to aid detoxification during arsenic exposure is unknown. Hizikia fusiforme (hijiki) and Fucus spiralis were used as model seaweeds: the former is known for its large inorganic arsenic concentration, whereas the latter contains mainly arsenosugars. F. spiralis was exposed to 0, 1 and 10mgL -1 arsenate solutions for 24h, whereas hijiki was analysed fresh. All samples contained As III, glutathione and reduced PC 2, identified using HPLC-ICP-MS/ES-MS. Although hijiki contained no As IIIPC complexes, arsenate exposed F. spiralis generated traces of numerous arsenic compounds that might be As IIIGS or As IIIPC 2 complexes. As IIIPC complexes seem not to be a principal storage form for long-term arsenic storage within seaweeds. However, 40 times higher glutathione concentrations were found in hijiki than F. spiralis, which may explain how hijiki deals with its high inorganic arsenic burden. © 2011 CSIRO.

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OBJECTIVES: To survey the outcomes used in Cochrane Reviews, as part of our work within the Core Outcome Measures in Effectiveness Trials Initiative.

STUDY DESIGN AND SETTING: A descriptive survey of Cochrane Reviews, divided by Cochrane Review Group (CRG), published in full for the first time in 2007 and 2011. Outcomes specified in the methods section of each review and outcomes reported in the results section of each review were of interest, in this exploration of the common use of outcomes and core outcome sets (COS).

RESULTS: Seven hundred eighty-eight reviews, specifying 6,127 outcomes, were included. When we excluded specified outcomes from the 86 reviews that did not include any studies, we found that 1,996 (37%) specified outcomes were not reported. Of the 361 new reviews with studies from 2011, 113 (31%) had a "summary of findings" table (SoF). Fifteen broad outcome categories were identified and used to manage the outcome data. We found consistency in the use of these categories across CRGs but inconsistency in outcomes within these categories.

CONCLUSION: COS have been used rarely in Cochrane Reviews, but the introduction of SoF makes the development and application of COS timelier than ever.

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We investigated the role of the C1772T polymorphisms in exon 12 of the Hypoxia-inducible factor-1 alpha (HIF-1alpha) gene C1772T genotype in prostate cancer (PCa) and amplification of the hypoxic response. We identified the heterozygous germline CT genotype as an increased risk factor for clinically localised prostate cancer (Odds ratio = 6.2; p < 0.0001). While immunostaining intensity for HIF-1alpha and VEGF was significantly enhanced in 75% of PCa specimens when compared to matched benign specimens (p < 0.0001), the CT genotype did not modulate the kinetics of HIF-1alpha protein expression in hypoxia in vitro, and was not associated with enhanced expression of hypoxic biomarkers. This study provides the first evidence of an increased risk for clinically localised prostate cancer in men carrying the C1772T HIF-1alpha gene polymorphism. Although our results did not suggest an association between expression of hypoxic biomarkers and genotype status, the correlation may merit further investigation.

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Donor-type microchimerism, the presence of a minority population of donor-derived haematopoietic cells following solid organ transplantation, has been postulated as a mechanism for induction of donor-specific graft tolerance. The stability, frequency, and relevance of microchimerism with respect to long-term outcome, however, remains uncertain. Using a polymerase chain reaction (PCR)-based method of microsatellite analysis of highly polymorphic short tandem repeat sequences (STRs) to detect donor-type cells, DNA from 11 patients was analyzed prospectively at specific time points for 12 months following liver transplantation, and from a further six patients retrospectively 2 years after liver transplantation. Using a panel of STRs, transient peripheral blood donor microchimerism was detected in 2 of 11 patients at a single time-point following transplantation, but persistent evidence of donor-derived cells was not observed during the study period. Analysis of DNA extracted from skin and duodenum in two patients likewise failed to show donor-type cells at these sites. None of the six patients in the retrospective arm showed donor microchimerism, resulting in an overall detection rate of 1.58%. These results suggest that donor microchimerism following liver transplantation is an infrequent event, and that the generation of graft tolerance is independent of microchimerism.