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The detection of reproductive tract disease (RTD) 3 wk postpartum is important because of its effect on subsequent reproductive outcomes. Numerous methods for the diagnosis of RTD are described, some of which are more practical and instantaneous in terms of diagnosis. Two of these methods involve identification of purulent vaginal discharge (PVD) and evidence of ultrasonographic uterine changes indicative of endometritis (UE). The objectives of our retrospective observational study were (1) to assess the association of PVD or UE score at the prebreeding examination (PBE) with the hazard of pregnancy within the subsequent breeding season; (2) to determine the test sensitivity (Se) and specificity (Sp) at the point of sampling of both tests using a Bayesian latent class model; and (3) to determine the effect of varying positivity thresholds on test accuracy. To achieve these objectives, we analyzed an initial data set of 5,049 PBE from 2,460 spring-calved cows in 8 herds between 2014 and 2018. Each PBE was conducted once between 25 and 86 d in milk. At each PBE, vaginal discharge was obtained with a Metricheck device (Simcro) whereas uterine contents were assessed using transrectal ultrasonography. Purulent vaginal discharge was scored on a scale of 0 to 3 depending on discharge character, and UE was scored on a scale of 0 to 4 depending on the presence and consistency of intraluminal fluid. Cows with scores of ≥2 in either test had received treatment. Fertility data were available from 4,756 PBE after data exclusion. The association between PVD or UE score at the PBE and subsequent hazard of pregnancy was analyzed using a Cox proportional hazards model. Cows with a PVD score of 2 or 3 were less likely to conceive than cows with a PVD score 0 [score 2 hazard ratio (HR) = 0.74; 95% confidence interval (CI): 0.59-0.94; score 3 HR = 0.65; 95% CI: 0.51-0.84]. Cows with a UE score of 1, 2, 3, or 4 were less likely to conceive than cows with a UE score of 0 (score 1 HR = 0.82; 95% CI: 0.73-0.93; score 2 HR = 0.79; 95% CI: 0.62-1.00; score 3 HR = 0.43; 95% CI: 0.43-0.90; score 4 HR = 0.39; 95% CI: 0.26-0.58). To determine the Se and Sp of PVD or UE score for diagnosis of RTD at the time of PBE, a Bayesian latent class model was fitted on 2,460 individual cow PBE. Flat priors were used for the Se and Sp of UE, whereas informative priors were used for PVD Se (mode = 65%, 5th percentile = 45%) and Sp (mode = 90%, 5th percentile = 80%) and RTD prevalence (mode = 20%, 5th percentile = 10%). Posterior estimates (median and 95% Bayesian probability intervals; BPI) were obtained using 'rjags' (R Studio). The optimal test thresholds (PVD and UE score ≥1) were selected by assessing the effect of different thresholds on test estimates and using a misclassification cost analysis. Based on these, median (95% BPI) Se for PVD and UE score ≥1 were 44% (29-60%) and 67% (33-100%), respectively. Median Sp for PVD and UE score ≥1 were 90% (86-93%) and 91% (86-93%), respectively. Higher scores in both tests were associated with impaired fertility, and UE scoring with a threshold of ≥1 had the highest test Se and Sp estimates although test Se was conditional on days in milk when the PBE occurred.
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Doenças dos Bovinos , Endometrite , Descarga Vaginal , Animais , Teorema de Bayes , Bovinos , Doenças dos Bovinos/diagnóstico por imagem , Doenças dos Bovinos/epidemiologia , Testes Diagnósticos de Rotina , Endometrite/diagnóstico , Endometrite/epidemiologia , Endometrite/veterinária , Feminino , Período Pós-Parto , Gravidez , Reprodução , Descarga Vaginal/diagnóstico , Descarga Vaginal/veterináriaRESUMO
Paediatric major trauma is relatively uncommon (6% of all traumas) and therefore unfamiliar to many radiologists. The indications for and interpretation of imaging are different to those commonly encountered in adults. In a centre that rarely encounters paediatric trauma, there can be trepidation over the best way to image children due to concerns regarding radiation and the injury patterns that occur at various ages. Within paediatric trauma, as per the Royal College of Radiologists "paediatric trauma protocols" guidelines and National Institute for Health and Care Excellence (NICE) guidance, the main reliance is on computed tomography (CT) and plain radiographs. This review of paediatric trauma from a busy UK major trauma centre demonstrates the most appropriate use of different imaging techniques, the extent of imaging, and the types of injuries that occur in a selection of paediatric trauma patients with a variety of trauma mechanisms. Cases include trauma related to road traffic accidents, bicycle handlebar injuries, falls, and even stabbings. Important learning points highlighted include the use of targeted body part imaging in children, the significance of handlebar injuries, and the importance of assessing for underlying injury in paediatric rib fractures and abdominal bruising and tenderness. We hope these examples will help to support and guide radiologists when encountering paediatric trauma within their own centres.
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Radiografia/métodos , Centros de Traumatologia , Ferimentos não Penetrantes/diagnóstico por imagem , Ferimentos Penetrantes/diagnóstico por imagem , Adolescente , Criança , Pré-Escolar , Humanos , Lactente , Recém-Nascido , Tomografia Computadorizada por Raios X , Reino UnidoRESUMO
BACKGROUND: Although visual locomotion scoring is inexpensive and simplistic, it is also time consuming and subjective. Automated lameness detection methods have been developed to replace the visual locomotion scoring and aid in early and accurate detection. Several types of sensors are measuring traits such as activity, lying behavior or temperature. Previous studies on automatic lameness detection have been unable to achieve high accuracy in combination with practical implementation in a on farm commercial setting. The objective of our research was to develop a prediction model for lameness in dairy cattle using a combination of remote sensor technology and other animal records that will translate sensor data into easy to interpret classified locomotion information for the farmer. During an 11-month period, data from 164 Holstein-Friesian dairy cows were gathered, housed at an Irish research farm. A neck-mounted accelerometer was used to gather behavioral metrics, additional automatically recorded data consisted of milk production and live weight. Locomotion scoring data were manually recorded, using a one-to-five scale (1 = non-lame, 5 = severely lame). Locomotion scores where then used to label the cows as sound (locomotion score 1) or unsound (locomotion score ≥ 2). Four supervised classification models, using a gradient boosted decision tree machine learning algorithm, were constructed to investigate whether cows could be classified as sound or unsound. Data available for model building included behavioral metrics, milk production and animal characteristics. RESULTS: The resulting models were constructed using various combinations of the data sources. The accuracy of the models was then compared using confusion matrices, receiver-operator characteristic curves and calibration plots. The model which achieved the highest performance according to the accuracy measures, was the model combining all the available data, resulting in an area under the curve of 85% and a sensitivity and specificity of 78%. CONCLUSION: These results show that 85% of this model's predictions were correct in identifying cows as sound or unsound, showing that the use of a neck-mounted accelerometer, in combination with production and other animal data, has potential to replace visual locomotion scoring as lameness detection method in dairy cows.
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INTRODUCTION: More than 30 million adults are released from incarceration globally each year. Many experience complex physical and mental health problems, and are at markedly increased risk of preventable mortality. Despite this, evidence regarding the global epidemiology of mortality following release from incarceration is insufficient to inform the development of targeted, evidence-based responses. Many previous studies have suffered from inadequate power and poor precision, and even large studies have limited capacity to disaggregate data by specific causes of death, sub-populations or time since release to answer questions of clinical and public health relevance. OBJECTIVES: To comprehensively document the incidence, timing, causes and risk factors for mortality in adults released from prison. METHODS: We created the Mortality After Release from Incarceration Consortium (MARIC), a multi-disciplinary collaboration representing 29 cohorts of adults who have experienced incarceration from 11 countries. Findings across cohorts will be analysed using a two-step, individual participant data meta-analysis methodology. RESULTS: The combined sample includes 1,337,993 individuals (89% male), with 75,795 deaths recorded over 9,191,393 person-years of follow-up. CONCLUSIONS: The consortium represents an important advancement in the field, bringing international attention to this problem. It will provide internationally relevant evidence to guide policymakers and clinicians in reducing preventable deaths in this marginalized population. KEY WORDS: Mortality; incarceration; prison; release; individual participant data meta-analysis; consortium; cohort.
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The cow-side diagnosis of reproductive tract disease (RTD) involves identifying the presence of purulent vaginal discharge (PVD) and ultrasonographic endometritis (UE). The objectives of our study were to obtain prevalence estimates for RTD diagnosed by 2 methods (PVD and UE scoring) and to investigate the risk factors for increased probability of RTD if these methods are used in isolation or in combination. Our retrospective observational cohort study tested the hypothesis that RTD assessed by 2 methods would have similar risk factors, and that those would be mainly cow- and calving-related factors. We analyzed data from 5,049 pre-breeding examinations (PBE) from 2,460 spring-calved cows on 8 farms between 2014 and 2018. Cow-related details assessed were days in milk at PBE, breed, lactation number, dry period length, body condition score at calving and PBE, 305-d milk yield, predicted transmitting ability for production and fertility, the presence of a corpus luteum at PBE, and positive diagnosis the previous year. Calving details assessed were type of sire, calf sex, twinning, stillbirth, calving difficulty score, and retained fetal membranes. We conducted statistical analyses using 4 multivariable logistic regression models to identify the risk of RTD diagnosed by (1) PVD in isolation, (2) UE in isolation, (3) the presence of either PVD or UE; and (4) the presence of both PVD and UE. We accounted for herd, cow, and year as random effects in all 4 models. The overall prevalence of RTD in models 1, 2, 3, and 4 were 7.5, 6.7, 11.6, and 2.6%, respectively. Days in milk at PBE, the interaction between days in milk and retained fetal membranes, twinning, and the predicted transmitting ability for calving interval were consistently significant risk factors for positive scores in all 4 models. Considerable calving difficulty [adjusted odds ratio (AOR) = 13.64], Holstein Friesian dam breed (AOR = 2.58), first lactation (AOR = 2.39), and body condition score at PBE (AOR = 1.64) were risk factors for a positive PVD score but not for a positive UE score. Fifth lactation (AOR = 1.69), a beef-sired calf (AOR = 1.46), and the absence of a corpus luteum at PBE (AOR = 1.57) were risk factors for a positive UE score but not for a positive PVD score. These results support the hypothesis that most of the risk factors for PVD and UE are the same but some are distinctly different, implying that in some instances the 2 methods diagnose separate components of the RTD complex.
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Doenças dos Bovinos/diagnóstico , Endometrite/veterinária , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Estudos de Coortes , Endometrite/diagnóstico , Endometrite/epidemiologia , Feminino , Irlanda/epidemiologia , Lactação , Leite , Gravidez , Estudos Retrospectivos , Fatores de Risco , Estações do AnoRESUMO
The single most important cause of late mortality after lung transplantation is chronic lung allograft dysfunction (CLAD). However, the pathological development of CLAD was not as simple as previously presumed and subclassification phenotypes, bronchiolitis obliterans syndrome (BOS) and restrictive CLAD (rCLAD), have been introduced. We want to re-investigate how CLAD manifests in the murine orthotopic lung transplant model and investigate the role of interleukin 17A (IL-17A) within this model. Orthotopic LTx was performed in CB57BL/6, IL-17 WT and IL-17 KO mice. In a first experiment, CB57BL/6 mice receiving an isograft (CB57BL/6) or allograft (BALB/C) were compared. In a second experiment IL-17 WT and IL-17 KO mice (both CB57BL/6 background) received an allograft (BALB/C). Mice received daily immunosuppression with steroids and cyclosporine and were sacrificed 10weeks after transplantation for histopathological analysis by an experienced lung pathologist. After murine orthotopic lung transplantation, the allograft histopathologically presented features of human rCLAD (i.e. overt inflammation, pleural/parenchymal fibrosis and obliterative bronchiolitis). In the IL-17A KO group, less inflammation in the bronchovascular axis (p=0.03) was observed and a non-significant trend towards less bronchovascular fibrosis, pleural/septal inflammation and fibrosis, and parenchymal inflammation and fibrosis when compared to WT mice. The major mismatch orthotopic lung transplant model resembles features of human rCLAD. IL-17A mediated immunity is involved in the inflammatory component, but had little influence on the degree of fibrosis. Further mechanistic and therapeutic studies in this mouse model are needed to fully understand the mechanisms in rCLAD.
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Obstrução das Vias Respiratórias/imunologia , Bronquiolite Obliterante/imunologia , Rejeição de Enxerto/imunologia , Interleucina-17/imunologia , Transplante de Pulmão , Obstrução das Vias Respiratórias/tratamento farmacológico , Animais , Bronquiolite Obliterante/tratamento farmacológico , Doença Crônica , Ciclosporina/uso terapêutico , Modelos Animais de Doenças , Rejeição de Enxerto/tratamento farmacológico , Humanos , Interleucina-17/genética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Esteroides/uso terapêutico , Transplantados , Transplante HomólogoRESUMO
PURPOSE: The purpose of this study was to investigate the level of adherence to antipsychotic prescription medication in a well-defined homeless cohort over a 15-year period. We hypothesized that adherence would be well below the recommended threshold for clinical effectiveness (80 %), and that it would be strongly associated with modifiable risk factors in the social environment in which homeless people live. METHOD: Linked baseline data (including comprehensive population-level administrative prescription records) were examined in a subpopulation of participants from two pragmatic-randomized trials that investigated Housing First for homeless and mentally ill adults. Adherence to antipsychotic medication was operationalized using the medication possession ratio. Multivariable logistic regression was used to estimate effect sizes between socio-demographic, homelessness-related and illness factors, and medication possession ratio. RESULTS: Among the 290 participants who met inclusion criteria for the current analysis, adherence to antipsychotic prescription was significantly associated with: history of psychiatric hospitalization; receipt of primary medical services; long-acting injectable antipsychotic formulations; and duration of homelessness. Mean medication possession ratio in the pre-randomization period was 0.41. Socio-demographic characteristics previously correlated with antipsychotic non-adherence were not significantly related to medication possession ratio. CONCLUSIONS: This is the first study to quantify the very low level of adherence to antipsychotic medication among homeless people over an extended observation period of 15 years. Each of the four factors found to be significantly associated with adherence presents opportunities for intervention. Strategies to end homelessness for this population may represent the greatest opportunity to improve adherence to antipsychotic medication.
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Antipsicóticos/uso terapêutico , Pessoas Mal Alojadas/estatística & dados numéricos , Adesão à Medicação/estatística & dados numéricos , Transtornos Mentais/tratamento farmacológico , Pessoas Mentalmente Doentes/estatística & dados numéricos , Adulto , Colúmbia Britânica/epidemiologia , Feminino , Humanos , Masculino , Transtornos Mentais/epidemiologia , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
AIMS: A subset of people with co-occurring substance use and mental disorders require coordinated support from health, social welfare and justice agencies to achieve diversion from homelessness, criminal recidivism and further health and social harms. Integrated models of care are typically concentrated in large urban centres. The present study aimed to empirically measure the prevalence and distribution of complex co-occurring disorders (CCD) in a large geographic region that includes urban as well as rural and remote settings. METHODS: Linked data were examined in a population of roughly 3.7 million adults. Inclusion criteria for the CCD subpopulation were: physician diagnosed substance use and mental disorders; psychiatric hospitalisation; shelter assistance; and criminal convictions. Prevalence per 100 000 was calculated in 91 small areas representing urban, rural and remote settings. RESULTS: 2202 individuals met our inclusion criteria for CCD. Participants had high rates of hospitalisation (8.2 admissions), criminal convictions (8.6 sentences) and social assistance payments (over $36 000 CDN) in the past 5 years. There was wide variability in the geographic distribution of people with CCD, with high prevalence rates in rural and remote settings. CONCLUSIONS: People with CCD are not restricted to areas with large populations or to urban settings. The highest per capita rates of CCD were observed in relatively remote locations, where mental health and substance use services are typically in limited supply. Empirically supported interventions must be adapted to meet the needs of people living outside of urban settings with high rates of CCD.
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Transtornos Mentais/complicações , Transtornos Relacionados ao Uso de Substâncias/complicações , Adulto , Crime , Criminosos , Diagnóstico Duplo (Psiquiatria) , Pessoas Mal Alojadas , Hospitalização , Humanos , Prevalência , Seguridade SocialRESUMO
ZNF281 is a zinc-finger factor involved in the control of cellular stemness and epithelial-mesenchymal transition (EMT). Here, we report that ZNF281 expression increased after genotoxic stress caused by DNA-damaging drugs. Comet assays demonstrated that DNA repair was delayed in cells silenced for the expression of ZNF281 and treated with etoposide. Furthermore, the expression of 10 DNA damage response genes was downregulated in cells treated with etoposide and silenced for ZNF281. In line with this finding, XRCC2 and XRCC4, two genes that take part in homologous recombination and non-homologous end joining, respectively, were transcriptionally activated by ZNF281 through a DNA-binding-dependent mechanism, as demonstrated by luciferase assays and Chromatin crosslinking ImmunoPrecipitation experiments. c-Myc, which also binds to the promoters of XRCC2 and XRCC4, was unable to promote their transcription or to modify ZNF281 activity. Of interest, bioinformatic analysis of 1971 breast cancer patients disclosed a significant correlation between the expression of ZNF281 and that of XRCC2. In summary, our data highlight, for the first time, the involvement of ZNF281 in the cellular response to genotoxic stress through the control exercised on the expression of genes that act in different repair mechanisms.
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Dano ao DNA , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica , Transativadores/metabolismo , Animais , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Ciclina B1/genética , Reparo do DNA/genética , Feminino , Inativação Gênica , Humanos , Masculino , Camundongos , Fosfoproteínas/genética , Regiões Promotoras Genéticas/genética , Proteínas de Ligação a RNA/genética , Proteínas Repressoras , Transativadores/deficiência , Transativadores/genética , NucleolinaRESUMO
Prophylactic azithromycin treatment has been demonstrated to improve freedom from bronchiolitis obliterans syndrome (BOS) 2 years after lung transplantation (LTx). In the current study, we re-evaluated the long-term effects of this prophylactic approach in view of the updated classification system for chronic lung allograft dysfunction (CLAD). A retrospective, intention-to-treat analysis of a randomized controlled trial comparing prophylactic treatment with placebo (n = 43) versus azithromycin (n = 40) after LTx was performed. Graft dysfunction (CLAD), graft loss (retransplantation, mortality), evolution of pulmonary function and functional exercise capacity were analyzed 7 years after inclusion of the last study subject. Following LTx, 22/43 (51%) patients of the placebo group and 11/40 (28%) patients of the azithromycin group ever developed CLAD (p = 0.043). CLAD-free survival was significantly longer in the azithromycin group (p = 0.024). No difference was present in proportion of obstructive versus restrictive CLAD between both groups. Graft loss was similar in both groups: 23/43 (53%) versus 16/40 (40%) patients (p = 0.27). Long-term pulmonary function and functional exercise capacity were significantly better in the azithromycin group (p < 0.05). Prophylactic azithromycin therapy reduces long-term CLAD prevalence and improves CLAD-free survival, pulmonary function, and functional exercise capacity after LTx.
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Antibioticoprofilaxia , Azitromicina/uso terapêutico , Bacteriemia/tratamento farmacológico , Bronquiolite Obliterante/cirurgia , Rejeição de Enxerto/tratamento farmacológico , Transplante de Pulmão/efeitos adversos , Antibacterianos/uso terapêutico , Bacteriemia/microbiologia , Bronquiolite Obliterante/complicações , Estudos de Coortes , Método Duplo-Cego , Feminino , Seguimentos , Volume Expiratório Forçado , Rejeição de Enxerto/etiologia , Rejeição de Enxerto/patologia , Sobrevivência de Enxerto , Humanos , Masculino , Complicações Pós-Operatórias , Prognóstico , Fatores de Risco , Síndrome , Transplante HomólogoRESUMO
Repair of double-stranded DNA breaks (DSBs) in mammalian cells primarily occurs by the non-homologous end-joining (NHEJ) pathway, which requires seven core proteins (Ku70/Ku86, DNA-PKcs (DNA-dependent protein kinase catalytic subunit), Artemis, XRCC4-like factor (XLF), XRCC4 and DNA ligase IV). Here we show using combined affinity purification and mass spectrometry that DNA-PKcs co-purifies with all known core NHEJ factors. Furthermore, we have identified a novel evolutionary conserved protein associated with DNA-PKcs-c9orf142. Computer-based modelling of c9orf142 predicted a structure very similar to XRCC4, hence we have named c9orf142-XLS (XRCC4-like small protein). Depletion of c9orf142/XLS in cells impaired DSB repair consistent with a defect in NHEJ. Furthermore, c9orf142/XLS interacted with other core NHEJ factors. These results demonstrate the existence of a new component of the NHEJ DNA repair pathway in mammalian cells.
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Simulação por Computador , Quebras de DNA de Cadeia Dupla , Proteínas de Ligação a DNA/metabolismo , Linhagem Celular , Cromatografia de Afinidade , Reparo do DNA/genética , Reparo do DNA/fisiologia , Proteínas de Ligação a DNA/genética , Humanos , Immunoblotting , RNA Interferente Pequeno , Espectrometria de Massas em TandemRESUMO
Spark plasma sintering (SPS) is a rapidly developing method for densification of powders into compacts. It belongs to the so-called "field assisted sintering techniques" that enable rapid sintering at much lower temperatures than the classical approaches of pressureless sintering of green pellets or hot isostatic pressing. In this paper, we report the successful integration of a SPS device into a hermetic glovebox for the handling of highly radioactive material containing radioisotopes of U, Th, Pu, Np, and Am. The glovebox implantation has been facilitated by the replacement of the hydraulic system to apply pressure with a compact electromechanical unit. The facility has been successfully tested using UO2 powder. Pellets with 97% of the theoretical density were obtained at 1000 °C for 5 min, significantly lower than the â¼1600 °C for 5-10 h used in conventional pellet sintering.
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It is often assumed that the pattern of injury in children mirrors that of the adult population, but children have different anatomical proportions and the relative elasticity of their tissues results in different injury patterns. The authors of this review are members of the British Society of Paediatric Radiologists subgroup and developed the recently published(47) paediatric trauma protocols for imaging children involved in major blunt trauma. The following article has been written to bring these guidelines to the attention of the wider community of UK radiologists, and explain the rationale behind the recommendations.
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Diagnóstico por Imagem/métodos , Pediatria/normas , Guias de Prática Clínica como Assunto , Ferimentos não Penetrantes/diagnóstico , Criança , Pré-Escolar , Humanos , Imageamento por Ressonância Magnética/métodos , Tomografia Computadorizada por Raios X/métodos , Ultrassonografia/métodos , Reino UnidoRESUMO
BACKGROUND: As direct-to-consumer personal genome testing (DTC-PGT) is increasingly available in Australia, knowledge of Australians' perceptions and attitudes towards this technology is needed in order to assess the (potential) impact it might have on the Australian public and healthcare system. AIMS: To explore the knowledge and perceptions of DTC-PGT in an Australian sample. METHODS: An online survey asking about knowledge and perceptions of DTC-PGT, undertaken between October 2011 and April 2012, of 270 Australian residents. Results were analysed using SAS. RESULTS: Our study found limited consumer knowledge of, and interest in, pursuing DTC-PGT in Australia. Ninety-three per cent of respondents correctly identified DTC-PGT as available to consumers directly, but only 40% correctly identified its availability in Australia. When asked about the content and value of the information DTC-PGT provides, the majority of respondents indentified that DTC-PGT could provide information about one's health and/or ancestry (82% and 74%). Additionally, respondents indicated they believed this information to be equally important as non-genetic information about one's ancestry and health. CONCLUSION: While a minority of respondents expressed an intention to pursue DTC-PGT (27%), the majority of respondents, irrespective of whether they wished to pursue it or not, believed that genetic information was as important as non-genetic information in regards to their health and their ancestry. The value ascribed to genetic information suggests that genetics plays a role in people's lives, and that further qualitative research could explore the ways in which people might use and understand the genetic information provided by DTC-PGT.
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Testes Genéticos , Conhecimentos, Atitudes e Prática em Saúde , Autocuidado , Adolescente , Adulto , Austrália , Participação da Comunidade , Feminino , Predisposição Genética para Doença , Pesquisas sobre Atenção à Saúde , Acessibilidade aos Serviços de Saúde , Humanos , Internet , Masculino , Pessoa de Meia-Idade , Percepção , Medicina de Precisão , Adulto JovemRESUMO
A series of uranium carbide samples, prepared by arc melting with a C/U ratio ranging from 0.96 to 1.04, has been studied by X-ray diffraction (XRD), (13)C nuclear magnetic resonance (NMR), and extended X-ray absorption fine structure (EXAFS). XRD determines phase uniqueness and the increase of the lattice parameter versus the carbon content. In contrast, (13)C NMR detects the different carbon environments in the lattice and in this study, clearly identifies the presence of discrete peaks for carbon in the octahedral lattice site in UC and an additional peak associated with excess carbon in hyperstoichiometric samples. Two peaks associated with different levels of carbon deficiency are detected for all hypostoichiometric compositions. More than one carbon environment is always detected by (13)C NMR. This exemplifies the difficulty in obtaining a perfect stoichiometric uranium monocarbide UC(1.00). The (13)C MAS spectra of uranium carbides exhibit the effects resulting from the carbon content on both the broadening of the peaks and on the Knight shift. An abrupt spectral change occurs between hypo- and hyperstoichiometric samples. The results obtained by EXAFS highlight subtle differences between the different stoichiometries, and in the hyperstoichiometric samples, the EXAFS results are consistent with the excess carbon atoms being in the tetrahedral interstitial position.
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A concept to integrate a commercial high-resolution, magic angle spinning nuclear magnetic resonance (MAS-NMR) probe capable of very rapid rotation rates (70 kHz) in a hermetically sealed enclosure for the study of highly radiotoxic materials has been developed and successfully demonstrated. The concept centres on a conventional wide bore (89 mm) solid-state NMR magnet operating with industry standard 54 mm diameter probes designed for narrow bore magnets. Rotor insertion and probe tuning take place within a hermetically enclosed glovebox, which extends into the bore of the magnet, in the space between the probe and the magnet shim system. Oxygen-17 MAS-NMR measurements demonstrate the possibility of obtaining high quality spectra from small sample masses (~10 mg) of highly radiotoxic material and the need for high spinning speeds to improve the spectral resolution when working with actinides. The large paramagnetic susceptibility arising from actinide paramagnetism in (Th(1-x)U(x))O2 solid solutions gives rise to extensive spinning sidebands and poor resolution at 15 kHz, which is dramatically improved at 55 kHz. The first (17)O MAS-NMR measurements on NpO(2+x) samples spinning at 55 kHz are also reported. The glovebox approach developed here for radiotoxic materials can be easily adapted to work with other hazardous or even air sensitive materials.
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The electronical and structural properties of Th(0.80)Am(0.20)O(2-x) materials have been studied by the coupling of X-ray diffraction and X-ray absorption spectroscopy techniques. A substoichiometric fluorite Th(IV)(0.80)Am(III)(0.20)O(1.90) solid solution is found following sintering in moisturized Ar-H(2). In contrast, heating of this sample in air leads to a nondefective fluorite Th(IV)(0.80)Am(IV)(0.20)O(2.00) solid solution. The structures of these solid solution compounds were fully characterized by assessing the interatomic distances, the coordination numbers, and the structural disorder. The effect of the sintering atmosphere on these crystallographical parameters and on the cation valences has been determined and the capability of ThO(2) to accommodate tri- and tetravalent actinides in the fluorite structure assessed.
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AIM: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. MATERIALS AND METHODS: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. RESULTS: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. CONCLUSION: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.