460 research outputs found

    10-year Weight Change and Biological Aging in a Random Sample of 3,059 U.S. Adults

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    Telomeres play a key role in the protection of chromosomes. A good index of biological aging is the length of telomeres. Telomeres gradually shorten over time. Hence, they are strongly related to chronological age. Lifestyle is also an important factor influencing telomere length. PURPOSE: This investigation was designed to study the relationship between 10-yr weight change and leukocyte telomere length (LTL) in a large sample of 3,059 randomly selected U.S. adults, 35-70 years old. METHODS: NHANES (National Health and Nutrition Examination Survey) data were used with a cross-sectional design to determine the relationship between percent weight change and LTL. Percent weight change was calculated by subtracting baseline body weight 10-yrs earlier from current body weight and then dividing by the individual’s baseline body weight. The quantitative polymerase chain reaction method was used to measure LTL relative to standard reference DNA (T/S ratio). Covariates included age, sex, race/ethnicity, year of assessment, economic status, intent to lose weight, BMI, smoking, total physical activity, and disease status, (i.e., having or not having diabetes, cardiovascular disease, and/or cancer). Multiple regression was used to determine the linear relationship between percent weight change and LTL. Potential mediating variables were controlled using partial correlation. Because women and men differed significantly in percent 10-yr weight change and also telomere length, the data were analyzed separately by sex. RESULTS: After adjusting for age, race, year of assessment, and economic status, the association between percent 10-yr weight change and LTL was significant in women (F=8.0, P=0.0085). Controlling for all the covariates weakened the relationship slightly (F=6.5, P=0.0163). With all the covariates controlled, for each 1 percentage point increase in weight over the 10-yrs, telomeres were 3.96 base pairs (bp) shorter, on average. Given each 1-yr increase in age was associated with telomeres that were 14.2 bp shorter in women, each 3.6 percentage point increase in weight over the 10-yrs was predictive of 1 yr greater biological aging. 10-yr weight change was not associated with LTL in men. CONCLUSION: 10-yr weight change is a significant predictor of biological aging in U.S. women, but not in men

    Abdominal Adiposity Indexed by the Sagittal Abdominal Diameter and Risk of Mortality in 14,119 U.S. Adults

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    The body mass index (BMI) is frequently used as a general measure of overweight and obesity. It is a good predictor of disease and premature death. However, research shows that indices of abdominal adiposity tend to be better predictors of disease risk and mortality than BMI. To date, the sagittal abdominal diameter (SAD), an index of abdominal adiposity, has never been evaluated as a predictor of mortality. PURPOSE: The present study was conducted to determine the extent that adults with different levels of SAD vary in their risk of all-cause mortality over an average follow-up of 6 years. METHODS: A total of 14,119 randomly selected adults, ages 20-79, from the National Health and Nutrition Examination Survey (NHANES), were included. SAD was measured by trained technicians during the years 2011-2016. The abdominal height of subjects was assessed in the supine position and a sliding-beam abdominal caliper with a built-in bubble was used to ensure a vertical measurement. Mortality data were acquired from the U.S. public-use linked mortality files (LMF), which are available for NHANES participants through 2018. Adjustments were made for 9 baseline potential confounding variables, including age, sex, race, BMI, cardiovascular disease, cancer, liver disease, smoking, and alcohol use. Subjects were divided into sex-specific quartiles based on their SAD values, and Cox proportional hazard ratios were calculated to determine risk of mortality over the follow-up period using SAS 9.4. RESULTS: With all the covariates controlled, hazard ratios showed a dose response relationship with all-cause mortality. Specifically, adults in Quartile 1 (Q1), those with the lowest sex-specific abdominal adiposity, had 0.45 (95% CI: 0.28-0.73) times the risk of mortality compared to those in Quartile 4 (Q4). Additionally, risk of mortality was 0.63 (95% CI: 0.42-0.95) for adults in Q2 vs Q4, and 0.67 (95% CI: 0.48-0.93) for Q3 vs Q4, each statistically significant. In the Q1 vs Q4 comparison, risk of mortality was 55% lower for those with the leanest SAD values. Overall, SAD was related to risk of all-cause mortality in a dose-response pattern. CONCLUSION: Epidemiologists and health care providers should seriously consider utilizing SAD as a screening tool within their programs. It is an excellent predictor of all-cause mortality

    Identification of valid reference genes for the normalization of RT qPCR gene expression data in human brain tissue

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    <p>Abstract</p> <p>Background</p> <p>Studies of gene expression in post mortem human brain can contribute to understanding of the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Quantitative real-time PCR (RT qPCR) is often used to analyse gene expression. The validity of results obtained using RT qPCR is reliant on accurate data normalization. Reference genes are generally used to normalize RT qPCR data. Given that expression of some commonly used reference genes is altered in certain conditions, this study aimed to establish which reference genes were stably expressed in post mortem brain tissue from individuals with AD, PD or DLB.</p> <p>Results</p> <p>The present study investigated the expression stability of 8 candidate reference genes, (ubiquitin C [UBC], tyrosine-3-monooxygenase [YWHAZ], RNA polymerase II polypeptide [RP II], hydroxymethylbilane synthase [HMBS], TATA box binding protein [TBP], β-2-microglobulin [B2M], glyceraldehyde-3-phosphate dehydrogenase [GAPDH], and succinate dehydrogenase complex-subunit A, [SDHA]) in cerebellum and medial temporal gyrus of 6 AD, 6 PD, 6 DLB subjects, along with 5 matched controls using RT qPCR (TaqMan<sup>® </sup>Gene Expression Assays). Gene expression stability was analysed using geNorm to rank the candidate genes in order of decreasing stability in each disease group. The optimal number of genes recommended for accurate data normalization in each disease state was determined by pairwise variation analysis.</p> <p>Conclusion</p> <p>This study identified validated sets of mRNAs which would be appropriate for the normalization of RT qPCR data when studying gene expression in brain tissue of AD, PD, DLB and control subjects.</p

    Numerical Study of the Stress Response of Two-Dimensional Dense Granular Packings

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    We investigate the Green function of two-dimensional dense random packings of grains in order to discriminate between the different theories of stress transmission in granular materials. Our computer simulations allow for a detailed quantitative investigation of the dynamics which is difficult to obtain experimentally. We show that both hyperbolic and parabolic models of stress transmission fail to predict the correct stress distribution in the studied region of the parameters space. We demonstrate that the compressional and shear components of the stress compare very well with the predictions of isotropic elasticity for a wide range of pressures and porosities and for both frictional and frictionless packings. However, the states used in this study do not include the critical isostatic point for frictional particles, so that our results do not preclude the fact that corrections to elasticity may appear at the critical point of jamming, or for other sample preparation protocols, as discussed in the main text. We show that the agreement holds in the bulk of the packings as well as at the boundaries and we validate the linear dependence of the stress profile width with depth.Comment: 7 pages, 5 figure

    Planned delivery to improve postpartum cardiac function in women with preterm pre-eclampsia: the PHOEBE mechanisms of action study within the PHOENIX RCT

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    Background Women whose pregnancies are affected by hypertensive disorders of pregnancy, in particular preterm pre-eclampsia, are at increased risk of long-term cardiovascular morbidity and mortality. Objectives To investigate the hypothesis that prolongation of a pregnancy affected by preterm pre-eclampsia managed by expectant management compared with planned early delivery would result in worse cardiovascular function 6 months postpartum. Design A randomised controlled trial. Setting 28 maternity hospitals in England and Wales. Participants Women who were eligible for the Pre-eclampsia in HOspital: Early iNductIon or eXpectant management (PHOENIX) study were approached and recruited for the PHOEBE study. The PHOENIX (Pre-eclampsia in HOspital: Early iNductIon or eXpectant management) study was a parallel-group, non-masked, multicentre, randomised controlled trial that was carried out in 46 maternity units across England and Wales. This study compared planned early delivery with expectant management (usual care) with individual randomisation in women with late preterm pre-eclampsia who were 34 weeks’ gestation to less than 37 weeks’ gestation and having a singleton or dichorionic diamniotic twin pregnancy. Interventions Postpartum follow-up included medical history, blood pressure assessment and echocardiography. All women had blood sampling performed on at least two time points from recruitment to the 6-month follow-up for assessment of cardiac necrosis markers. Main outcome measures Primary outcome was a composite of systolic and/or diastolic dysfunction (originally by 2009 guidelines then updated by 2016 guidelines, with an amended definition of diastolic dysfunction). Analyses were by intention to treat, together with a per-protocol analysis for the primary and secondary outcomes. Results Between 27 April 2016 and 30 November 2018, 623 women were found to be eligible, of whom 420 (67%) were recruited across 28 maternity units in England and Wales. A total of 133 women were allocated to planned delivery, 137 women were allocated to expectant management and a further 150 received non-randomised expectant management within usual care. The mean time from enrolment to delivery was 2.5 (standard deviation 1.9) days in the planned delivery group compared with 6.8 (standard deviation 5.3) days in the expectant management group. There were no differences in the primary outcome between women in the planned delivery group and those in the expectant management group using either the 2009 (risk ratio 1.06, 95% confidence interval 0.80 to 1.40) or the 2016 definition (risk ratio 0.78, 95% confidence interval 0.33 to 1.86). Overall, 10% (31/321) of women had a left ventricular ejection fraction &lt; 55% and 71% of the cohort remained hypertensive at 6 months postpartum. No differences were observed between groups in cardiorespiratory outcomes prior to discharge from hospital or in systolic or diastolic blood pressure measurements. Variables associated with the primary outcome (2009 definition) at 6 months postpartum were maternal body mass index (adjusted odds ratio 1.33 per 5 kg/m2, 95% confidence interval 1.12 to 1.59 per 5 kg/m2) and maternal age (adjusted odds ratio 2.16, 95% confidence interval 1.44 to 3.22 per 10 years). Limitations include changing definitions regarding systolic and/or diastolic dysfunction. Conclusions Preterm pre-eclampsia results in persistence of hypertension in the majority of women with late preterm pre-eclampsia at 6 months postpartum and systolic dysfunction in 10%. Pre-eclampsia should not be considered a self-limiting disease of pregnancy alone. Future work Interventions aimed at reducing cardiovascular dysfunction. Trial registration Current Controlled Trials ISRCTN01879376. Funding This project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council and National Institute for Health Research (NIHR) partnership. This will be published in full in Efficacy and Mechanism Evaluation; Vol. 8, No. 12. See the NIHR Journals Library website for further project information

    Moving lessons: teaching sociology through embodied learning in the HE classroom

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    This chapter outlines an approach to classroom teaching that makes use of physical movement alongside more traditional lecturing methods when delivering lessons on abstract theoretical material. It develops the notion of embodied learning as a 'physical metaphor', outlining some examples of this practice that we have used in our recent work with a class of first year undergraduates. We argue that conceptualising students as embodied subjects, whose capacity to learn extends through and beyond their physical selves, educators are able to enhance classroom delivery by diversifying teaching activities and creating opportunities for enjoyable and memorable learning experiences. We advocate the reflexive, contextually-sensitive and level- appropriate use of this method, arguing that despite some limitations it can animate students' understanding of academic ideas in uniquely personalised ways

    Enriching the values of micro and small business research projects: co-creation service provision as perceived by academic, business and student

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    This is an Accepted Manuscript of an article published by Taylor & Francis in Studies in Higher Education, first published online 3 September 2014, available online: http://www.tandfonline.com/doi/full/10.1080/03075079.2014.942273.The National Committee of Inquiry into Higher Education (1996) chaired by Lord Dearing envisioned a university sector central to the UK’s knowledge-based economy. With successive government support the university-business partnership ideology has been put into practice. Widening participation has increased in emphasis over recent years, providing key innovations and skills to support business growth. Yet business schools activities in business growth is marginal against other university schools. The paper reports on an empirical study analyzing the university/business values derived from one small business engagement project. Data collected through semi-structured interviews, observations, memos, and discussions were coupled with critical evaluation of work and action-based learning (ABL) literature. Analysis reveals evidence of multiple value adding factors; it emerged that the existence of knowledge, present or generated through blended learning techniques, was a key value adding element. The findings enabled the construction of a universal process model providing a project framework, detailing areas of collaborative efforts and associated recompenses; this included ease in project advancements and a noticeably advanced project outcome. The study highlights these values in terms of individual and organizational learning, originality and quality of outputs. Given the growing importance of Small to Medium-sized Enterprises (SMEs) to the UK economy, understanding the value co-created by collaborative projects in delivering both work-based and ABL for graduates/students, academics and enterprise management is important.Peer reviewedFinal Accepted Versio

    Stress in frictionless granular material: Adaptive Network Simulations

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    We present a minimalistic approach to simulations of force transmission through granular systems. We start from a configuration containing cohesive (tensile) contact forces and use an adaptive procedure to find the stable configuration with no tensile contact forces. The procedure works by sequentially removing and adding individual contacts between adjacent beads, while the bead positions are not modified. In a series of two-dimensional realizations, the resulting force networks are shown to satisfy a linear constraint among the three components of average stress, as anticipated by recent theories. The coefficients in the linear constraint remain nearly constant for a range of shear loadings up to about .6 of the normal loading. The spatial distribution of contact forces shows strong concentration along ``force chains". The probability of contact forces of magnitude f shows an exponential falloff with f. The response to a local perturbing force is concentrated along two characteristic rays directed downward and laterally.Comment: 8 pages, 8 figure

    Group work and the change of obstacles over time: The influence of learning style and group composition

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    It is through working in groups that students develop cooperative learning skills and experience. However, group work activity often leads students into a difficult experience, especially for first-year students who are not familiar with group work activities at university. This study explores obstacles faced by first-year students during their group work activities. It investigates whether a group of students with a similar learning style (homogeneous group) experience different obstacles compared to a group of students with a diverse learning style (heterogeneous group). In addition, to identify the difference, if any, between a group formed by a tutor and one where the students form the group themselves, tutor and self-allocated group allocations are explored. This study focuses on obstacles experienced by these students during group work activities. Using a sample of more than 200 students over a period of 3 years, the types and the changes of obstacles in different stages of group life are explored. The findings show that students experience obstacles which can be classified into personal and social, leadership and management, and task-related obstacles. Those obstacles were not static but increased over time. The study also investigates the impact of different methods of forming groups and whether this impacted on obstacles experienced. Overall, different interventions prompted different patterns of obstacle development
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