95 research outputs found

    Large scale motions of Neptune's bow shock: Evidence for control of the shock position by the rotation phase of Neptune's magnetic field

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    The Voyager 2 spacecraft observed high levels of Langmuir waves before the inbound crossing of Neptune's bow shock, thereby signifying magnetic connection of the bow shock. The Langmuir waves occurred in multiple bursts throughout two distinct periods separated by an 85 minute absence of wave activity. The times of onsets, peaks, and disappearances of the waves were used together with the magnetic field directions and spacecraft position, to perform a 'remote-sensing' analysis of the shape and location of Neptune's bow shock prior to the inbound bow shock crossing. The bow shock is assumed to have a parabolidal shape with a nose location and flaring parameter determined independently for each wave event. The remote-sensing analysis give a shock position consistent with the time of the inbound shock crossing. The flaring parameter of the shock remains approximately constant throughout each period of wave activity but differs by a factor of 10 between the two periods. The absence of waves between two periods of wave activity coincides with a large rotation of the magnetic field and a large increase in the solar wind ram pressure' both these effects lead to magnetic disconnection of the spacecraft from shock. The planetwards motion of the shock's nose from 38.5 R(sub N) to 34.5 R(sub N) during the second time period occurred while the solar wind ram pressure remained constant to within 15 percent. This second period of planetwards motion of the shock is therefore strong evidence for Neptune's bow shock moving in response to the rotation of Neptune's oblique, tilted magnetic dipole. Normalizing the ram pressure, the remotely-sensed shock moves sunwards during the first wave period and planetwards in the second wave period. The maximum standoff distance occurs while the dipole axis is close to being perpendicular to the Sun-Neptune direction. The remote-sensing analysis provides strong evidence that the location of Neptune's bow shock is controlled by Neptune's rotation phase

    Definitions of progression in chronic kidney disease-predictors and relationship to renal replacement therapy in a population cohort with a 6 year follow-up

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    Background. Chronic kidney disease (CKD) is common, important and associated with increased healthcare needs due to CKD progression. Definitions of renal disease progression are multiple, and not always comparable. A measure of 'progression' directly comparable with renal replacement therapy (RRT) initiation would identify 'progressors' in research and for healthcare planning.Methods. The Grampian Laboratory Outcomes Morbidity and Mortality Study (GLOMMS-I) is a community cohort with CKD from 2003, followed up to June 2009 for (i) RRT initiation and (ii) 'progression': sustained reduction in estimated glomerular filtration rate (eGFR) by 15 mL/min/1.73 m(2) (equivalent to CKD stage change), or to <10 mL/min/1.73 m(2), whichever occurs first. Predictors were baseline demographics and comorbidity. The use of the Kidney Disease: Improving Global Outcomes-2012 progression definition was also explored.Results. Two thousand two hundred and eighty-nine and 1044 had Stage 3 and 4 CKD, 44% were males. Overall, RRT initiation and progression rates were 0.97 and 3.50 per 100 patient-years (py). Females had significantly lower progression and RRT initiation rates. The progression rate was not dependent on CKD stage [incidence rate ratio (IRR) for Stage 4 (versus Stage 3) 0.9 (95% CI 0.8-1.2)], whereas the RRT initiation rate was [IRR 5.6 (95% CI 3.8-8.2)]. Increased proteinuria was associated with both greater RRT initiation and progression rates.Conclusions. Progression and RRT initiation rate ratios allow comparison of predictors of these outcomes. Higher rates of both in males suggest that greater RRT initiation rate is biological rather than due to preferential treatment. Similar progression but very different RRT initiation rates in Stage 3 and 4 CKD suggests that CKD stage effect on RRT initiation is a function of endpoint proximity rather than faster renal function deterioration.Background. Chronic kidney disease (CKD) is common, important and associated with increased healthcare needs due to CKD progression. Definitions of renal disease progression are multiple, and not always comparable. A measure of 'progression' directly comparable with renal replacement therapy (RRT) initiation would identify 'progressors' in research and for healthcare planning.Methods. The Grampian Laboratory Outcomes Morbidity and Mortality Study (GLOMMS-I) is a community cohort with CKD from 2003, followed up to June 2009 for (i) RRT initiation and (ii) 'progression': sustained reduction in estimated glomerular filtration rate (eGFR) by 15 mL/min/1.73 m(2) (equivalent to CKD stage change), or to <10 mL/min/1.73 m(2), whichever occurs first. Predictors were baseline demographics and comorbidity. The use of the Kidney Disease: Improving Global Outcomes-2012 progression definition was also explored.Results. Two thousand two hundred and eighty-nine and 1044 had Stage 3 and 4 CKD, 44% were males. Overall, RRT initiation and progression rates were 0.97 and 3.50 per 100 patient-years (py). Females had significantly lower progression and RRT initiation rates. The progression rate was not dependent on CKD stage [incidence rate ratio (IRR) for Stage 4 (versus Stage 3) 0.9 (95% CI 0.8-1.2)], whereas the RRT initiation rate was [IRR 5.6 (95% CI 3.8-8.2)]. Increased proteinuria was associated with both greater RRT initiation and progression rates.Conclusions. Progression and RRT initiation rate ratios allow comparison of predictors of these outcomes. Higher rates of both in males suggest that greater RRT initiation rate is biological rather than due to preferential treatment. Similar progression but very different RRT initiation rates in Stage 3 and 4 CKD suggests that CKD stage effect on RRT initiation is a function of endpoint proximity rather than faster renal function deterioration

    Hypertensive diseases of pregnancy and risk of hypertension and stroke in later life: results from cohort study

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    Objective: To examine the association between hypertensive diseases of pregnancy (gestational hypertension and pre-eclampsia) and the development of circulatory diseases in later life. Design: Cohort study of women who had pre-eclampsia during their first singleton pregnancy. Two comparison groups were matched for age and year of delivery, one with gestational hypertension and one with no history of raised blood pressure. Setting: Maternity services in the Grampian region of Scotland. Participants: Women selected from the Aberdeen maternity and neonatal databank who were resident in Aberdeen and who delivered a first, live singleton from 1951 to 1970. Main outcome measures: Current vital and cardiovascular health status ascertained through postal questionnaire survey, clinical examination, linkage to hospital discharge, and mortality data. Results: There were significant positive associations between pre-eclampsia/eclampsia or gestational hypertension and later hypertension in all measures. The adjusted relative risks varied from 1.13-3.72 for gestational hypertension and 1.40-3.98 for pre-eclampsia or eclampsia. The adjusted incident rate ratio for death from stroke for the pre-eclampsia/eclampsia group was 3.59 (95% confidence interval 1.04 to 12.4). Conclusions: Hypertensive diseases of pregnancy seem to be associated in later life with diseases related to hypertension. If greater awareness of this association leads to earlier diagnosis and improved management, there may be scope for reducing a proportion of the morbidity and mortality from such diseases

    Approaches to ascertaining comorbidity information: validation of routine hospital episode data with clinician-based case note review

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    Background In clinical practice, research, and increasingly health surveillance, planning and costing, there is a need for high quality information to determine comorbidity information about patients. Electronic, routinely collected healthcare data is capturing increasing amounts of clinical information as part of routine care. The aim of this study was to assess the validity of routine hospital administrative data to determine comorbidity, as compared with clinician-based case note review, in a large cohort of patients with chronic kidney disease. Methods A validation study using record linkage. Routine hospital administrative data were compared with clinician-based case note review comorbidity data in a cohort of 3219 patients with chronic kidney disease. To assess agreement, we calculated prevalence, kappa statistic, sensitivity, specificity, positive predictive value and negative predictive value. Subgroup analyses were also performed. Results Median age at index date was 76.3 years, 44% were male, 67% had stage 3 chronic kidney disease and 31% had at least three comorbidities. For most comorbidities, we found a higher prevalence recorded from case notes compared with administrative data. The best agreement was found for cerebrovascular disease (κ = 0.80) ischaemic heart disease (κ = 0.63) and diabetes (κ = 0.65). Hypertension, peripheral vascular disease and dementia showed only fair agreement (κ = 0.28, 0.39, 0.38 respectively) and smoking status was found to be poorly recorded in administrative data. The patterns of prevalence across subgroups were as expected and for most comorbidities, agreement between case note and administrative data was similar. Agreement was less, however, in older ages and for those with three or more comorbidities for some conditions. Conclusions This study demonstrates that hospital administrative comorbidity data compared moderately well with case note review data for cerebrovascular disease, ischaemic heart disease and diabetes, however there was significant under-recording of some other comorbid conditions, and particularly common risk factors

    Association of FADS1/2 Locus Variants and Polyunsaturated Fatty Acids With Aortic Stenosis.

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    IMPORTANCE: Aortic stenosis (AS) has no approved medical treatment. Identifying etiological pathways for AS could identify pharmacological targets. OBJECTIVE: To identify novel genetic loci and pathways associated with AS. DESIGN, SETTING, AND PARTICIPANTS: This genome-wide association study used a case-control design to evaluate 44 703 participants (3469 cases of AS) of self-reported European ancestry from the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort (from January 1, 1996, to December 31, 2015). Replication was performed in 7 other cohorts totaling 256 926 participants (5926 cases of AS), with additional analyses performed in 6942 participants from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. Follow-up biomarker analyses with aortic valve calcium (AVC) were also performed. Data were analyzed from May 1, 2017, to December 5, 2019. EXPOSURES: Genetic variants (615 643 variants) and polyunsaturated fatty acids (ω-6 and ω-3) measured in blood samples. MAIN OUTCOMES AND MEASURES: Aortic stenosis and aortic valve replacement defined by electronic health records, surgical records, or echocardiography and the presence of AVC measured by computed tomography. RESULTS: The mean (SD) age of the 44 703 GERA participants was 69.7 (8.4) years, and 22 019 (49.3%) were men. The rs174547 variant at the FADS1/2 locus was associated with AS (odds ratio [OR] per C allele, 0.88; 95% CI, 0.83-0.93; P = 3.0 × 10-6), with genome-wide significance after meta-analysis with 7 replication cohorts totaling 312 118 individuals (9395 cases of AS) (OR, 0.91; 95% CI, 0.88-0.94; P = 2.5 × 10-8). A consistent association with AVC was also observed (OR, 0.91; 95% CI, 0.83-0.99; P = .03). A higher ratio of arachidonic acid to linoleic acid was associated with AVC (OR per SD of the natural logarithm, 1.19; 95% CI, 1.09-1.30; P = 6.6 × 10-5). In mendelian randomization, increased FADS1 liver expression and arachidonic acid were associated with AS (OR per unit of normalized expression, 1.31 [95% CI, 1.17-1.48; P = 7.4 × 10-6]; OR per 5-percentage point increase in arachidonic acid for AVC, 1.23 [95% CI, 1.01-1.49; P = .04]; OR per 5-percentage point increase in arachidonic acid for AS, 1.08 [95% CI, 1.04-1.13; P = 4.1 × 10-4]). CONCLUSIONS AND RELEVANCE: Variation at the FADS1/2 locus was associated with AS and AVC. Findings from biomarker measurements and mendelian randomization appear to link ω-6 fatty acid biosynthesis to AS, which may represent a therapeutic target

    The lived experiences of experienced Vipassana Mahasi meditators: an interpretative phenomenological analysis.

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    Research into the effects and mechanisms of mindfulness training draws predominantly on quantitative research. There is a lack of understanding about the subjective experiences of experienced mindfulness meditators, which may provide additional insights into the effects, processes and context of mindfulness training. This qualitative study explored the lived experiences of a novel group of experienced mindfulness meditators who practise Vipassana Mahasi (VM) meditation. The study aimed to understand how experienced VM practitioners make sense of the effects of practice and what processes they ascribe to it. Participants attended semistructured interviews, and their responses were analysed using interpretative phenomenological analysis. Results yielded overarching themes including (a) improvements in hedonic and eudaimonic well-being; (b) insights into self, others and perception of reality; (c) attaining equanimity; and (d) physical and interpersonal difficulties. Participants perceived VM as a ‘cleansing’ process whereby maladaptive responses were eliminated through mindfulness, other supportive mental qualities, decentering and nonattachment. The findings revealed a complex and dynamic set of interdependent outcomes and processes, which are reinforced by Buddhist teachings and ethical practices. This study highlights the need for additional interdisciplinary research into topics such as insight generation and supportive mental qualities cultivated during VM, novel states of well-being informed by Buddhist constructs and interpersonal difficulties related to long-term practice. Findings also suggest that incorporating Buddhist teachings and ethics into mindfulness-based interventions may enhance practitioner understanding and implementation of meditation techniques.N/

    Erratum to: Methods for evaluating medical tests and biomarkers

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    [This corrects the article DOI: 10.1186/s41512-016-0001-y.]

    Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer's disease

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    We identified rare coding variants associated with Alzheimer’s disease (AD) in a 3-stage case-control study of 85,133 subjects. In stage 1, 34,174 samples were genotyped using a whole-exome microarray. In stage 2, we tested associated variants (P<1×10-4) in 35,962 independent samples using de novo genotyping and imputed genotypes. In stage 3, an additional 14,997 samples were used to test the most significant stage 2 associations (P<5×10-8) using imputed genotypes. We observed 3 novel genome-wide significant (GWS) AD associated non-synonymous variants; a protective variant in PLCG2 (rs72824905/p.P522R, P=5.38×10-10, OR=0.68, MAFcases=0.0059, MAFcontrols=0.0093), a risk variant in ABI3 (rs616338/p.S209F, P=4.56×10-10, OR=1.43, MAFcases=0.011, MAFcontrols=0.008), and a novel GWS variant in TREM2 (rs143332484/p.R62H, P=1.55×10-14, OR=1.67, MAFcases=0.0143, MAFcontrols=0.0089), a known AD susceptibility gene. These protein-coding changes are in genes highly expressed in microglia and highlight an immune-related protein-protein interaction network enriched for previously identified AD risk genes. These genetic findings provide additional evidence that the microglia-mediated innate immune response contributes directly to AD development
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