139 research outputs found
Childhood obesity and adult cardiovascular disease risk factors: a systematic review with meta-analysis
Background
Overweight and obesity is a major public health concern that includes associations with the development of cardiovascular disease (CVD) risk factors during childhood and adolescence as well as premature mortality in adults. Despite the high prevalence of childhood and adolescent obesity as well as adult CVD, individual studies as well as previous systematic reviews examining the relationship between childhood obesity and adult CVD have yielded conflicting results. The purpose of this study was to use the aggregate data meta-analytic approach to address this gap. Methods
Studies were included if they met the following criteria: (1) longitudinal and cohort studies (including case-cohort), (2) childhood exposure and adult outcomes collected on the same individual over time, (3) childhood obesity, as defined by the original study authors, (4) English-language articles, (5) studies published up to June, 2015, (6) one or more of the following CVD risk factors [systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), non-high-density lipoprotein cholesterol (non-HDL), and triglycerides (TG)], (7) outcome(s) not self-reported, and (8) exposure measurements (childâs adiposity) assessed by health professionals, trained investigators, or self-reported. Studies were retrieved by searching three electronic databases as well as citation tracking. Fisherâs r to z score was calculated for each study for each outcome. Pooled effect sizes were calculated using random-effects models while risk of bias was assessed using the STROBE instrument. In order to try and identify sources of heterogeneity, random-effects meta-regression was also performed. Results
Of the 4840 citations reviewed, a total of 23 studies were included in the systematic review and 21 in the meta-analysis. The findings suggested that childhood obesity is significantly and positively associated with adult SBP (Zr = 0.11; 95% CI: 0.07, 0.14), DBP (Zr = 0.11; 95% CI: 0.07, 0.14), and TG (Zr =0.08; 95% CI: 0.03, 0.13), and significantly and inversely associated with adult HDL (Zr = â0.06; 95% CI: -0.10, â0.02). For those studies that adjusted for adult body mass index (BMI), associations were reversed, suggesting that adult BMI may be a potential mediator. Nine studies had more than 33% of items that placed them at an increased risk for bias. Conclusions
The results of this study suggest that childhood obesity may be a risk factor for selected adult CVD risk factors. However, a need exists for additional, higher-quality studies that include, but are not limited to, both unadjusted and adjusted measures such as BMI before any definitive conclusions can be reached. Systematic review and meta-analysis
PROSPERO 2015: CRD42015019763
Effect of Limb Lengthening on Internodal Length and Conduction Velocity of Peripheral Nerve
The influences of axon diameter, myelin thickness, and internodal length on the velocity of conduction of peripheral nerve action potentials are unclear. Previous studies have demonstrated a strong dependence of conduction velocity on internodal length. However, a theoretical analysis has suggested that this relationship may be lost above a nodal separation of âŒ0.6 mm. Here we measured nerve conduction velocities in a rabbit model of limb lengthening that produced compensatory increases in peripheral nerve growth. Divided tibial bones in one hindlimb were gradually lengthened at 0.7 mm per day using an external frame attached to the bone. This was associated with a significant increase (33%) of internodal length (0.95â1.3 mm) in axons of the tibial nerve that varied in proportion to the mechanical strain in the nerve of the lengthened limb. Axonal diameter, myelin thickness, and g-ratios were not significantly altered by limb lengthening. Despite the substantial increase in internodal length, no significant change was detected in conduction velocity (âŒ43 m/s) measured either in vivo or in isolated tibial nerves. The results demonstrate that the internode remains plastic in the adult but that increases in internodal length of myelinated adult nerve axons do not result in either deficiency or proportionate increases in their conduction velocity and support the view that the internodal lengths of nerves reach a plateau beyond which their conduction velocities are no longer sensitive to increases in internodal length
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Integrating Life Cycle and Impact Assessments to Map Food's Cumulative Environmental Footprint
Producing food exerts pressures on the environment. Understanding the location and magnitude of food production is key to reducing the impacts of these pressures on nature and people. In this Perspective, Kuempel et al. outline an approach for integrating life cycle assessment and cumulative impact mapping data and methodologies to map the cumulative environmental pressure of food systems. The approach enables quantification of current and potential future environmental pressures, which are needed to reduce the net impact of feeding humanity. © 2020 The AuthorsFeeding a growing, increasingly affluent population while limiting environmental pressures of food production is a central challenge for society. Understanding the location and magnitude of food production is key to addressing this challenge because pressures vary substantially across food production types. Applying data and models from life cycle assessment with the methodologies for mapping cumulative environmental impacts of human activities (hereafter cumulative impact mapping) provides a powerful approach to spatially map the cumulative environmental pressure of food production in a way that is consistent and comprehensive across food types. However, these methodologies have yet to be combined. By synthesizing life cycle assessment and cumulative impact mapping methodologies, we provide guidance for comprehensively and cumulatively mapping the environmental pressures (e.g., greenhouse gas emissions, spatial occupancy, and freshwater use) associated with food production systems. This spatial approach enables quantification of current and potential future environmental pressures, which is needed for decision makers to create more sustainable food policies and practices. © 2020 The Author
Sensitive and selective amplification of methylated DNA sequences using helper-dependent chain reaction in combination with a methylation-dependent restriction enzyme
We have developed a novel technique for specific
amplification of rare methylated DNA fragments in
a high background of unmethylated sequences that
avoids the need of bisulphite conversion. The
methylation-dependent restriction enzyme GlaI is
used to selectively cut methylated DNA. Then
targeted fragments are tagged using specially
designed âhelperâ oligonucleotides that are also
used to maintain selection in subsequent amplification
cycles in a process called âhelper-dependent
chain reactionâ. The process uses disabled primers
called âdriversâ that can only prime on each cycle if
the helpers recognize specific sequences within
the target amplicon. In this way, selection for the
sequence of interest is maintained throughout the
amplification, preventing amplification of unwanted
sequences. Here we show how the method can be
applied to methylated Septin 9, a promising biomarker
for early diagnosis of colorectal cancer.
The GlaI digestion and subsequent amplification
can all be done in a single tube. A detection sensitivity
of 0.1% methylated DNA in a background of
unmethylated DNA was achieved, which was
similar to the well-established Heavy Methyl
method that requires bisulphite-treated DNA.Funding for open access charge: Commonwealth Scientific
and Industrial Research Organisation (CSIRO), Australia.
National Health & Medical Research Counci
The GALAH survey: Co-orbiting stars and chemical tagging
We present a study using the second data release of the GALAH survey of
stellar parameters and elemental abundances of 15 pairs of stars identified by
Oh et al 2017. They identified these pairs as potentially co-moving pairs using
proper motions and parallaxes from Gaia DR1. We find that 11 very wide (>1.7
pc) pairs of stars do in fact have similar Galactic orbits, while a further
four claimed co-moving pairs are not truly co-orbiting. Eight of the 11
co-orbiting pairs have reliable stellar parameters and abundances, and we find
that three of those are quite similar in their abundance patterns, while five
have significant [Fe/H] differences. For the latter, this indicates that they
could be co-orbiting because of the general dynamical coldness of the thin
disc, or perhaps resonances induced by the Galaxy, rather than a shared
formation site. Stars such as these, wide binaries, debris of past star
formation episodes, and coincidental co-orbiters, are crucial for exploring the
limits of chemical tagging in the Milky Way.Comment: 14 pages, 9 figures, submitted to MNRAS. Updated for Gaia DR2 value
The GALAH survey: Co-orbiting stars and chemical tagging
We present a study using the second data release of the GALAH survey of
stellar parameters and elemental abundances of 15 pairs of stars identified by
Oh et al 2017. They identified these pairs as potentially co-moving pairs using
proper motions and parallaxes from Gaia DR1. We find that 11 very wide (>1.7
pc) pairs of stars do in fact have similar Galactic orbits, while a further
four claimed co-moving pairs are not truly co-orbiting. Eight of the 11
co-orbiting pairs have reliable stellar parameters and abundances, and we find
that three of those are quite similar in their abundance patterns, while five
have significant [Fe/H] differences. For the latter, this indicates that they
could be co-orbiting because of the general dynamical coldness of the thin
disc, or perhaps resonances induced by the Galaxy, rather than a shared
formation site. Stars such as these, wide binaries, debris of past star
formation episodes, and coincidental co-orbiters, are crucial for exploring the
limits of chemical tagging in the Milky Way.Comment: 14 pages, 9 figures, submitted to MNRAS. Updated for Gaia DR2 value
Extensive study of HD 25558, a long-period double-lined binary with two SPB components
We carried out an extensive observational study of the Slowly Pulsating B (SPB) star, HD 25558. The â2000 spectra obtained at different observatories, the ground-based and MOST satellite light curves revealed that this object is a double-lined spectroscopic binary with an orbital period of about nine years. The observations do not allow the inference of an orbital solution. We determined the physical parameters of the components, and found that both lie within the SPB instability strip. Accordingly, both show line-profile variations due to stellar pulsations. 11 independent frequencies were identified in the data. All the frequencies were attributed to one of the two components based on pixel-by-pixel variability analysis of the line profiles. Spectroscopic and photometric mode identification was also performed for the frequencies of both stars. These results suggest that the inclination and rotation of the two components are rather different. The primary is a slow rotator with â6 d period, seen at â60° inclination, while the secondary rotates fast with â1.2 d period, and is seen at â20° inclination. Spectropolarimetric measurements revealed that the secondary component has a magnetic field with at least a few hundred Gauss strength, while no magnetic field can be detected in the primary
The GALAH Survey: Stellar streams and how stellar velocity distributions vary with Galactic longitude, hemisphere and metallicity
Using GALAH survey data of nearby stars, we look at how structure in the
planar (u,v) velocity distribution depends on metallicity and on viewing
direction within the Galaxy. In nearby stars, with distance d < 1 kpc, the
Hercules stream is most strongly seen in higher metallicity stars [Fe/H] > 0.2.
The Hercules stream peak v value depends on viewed galactic longitude, which we
interpret as due to the gap between the stellar stream and more circular orbits
being associated with a specific angular momentum value of about 1640 km/s kpc.
The association of the gap with a particular angular momentum value supports a
bar resonant model for the Hercules stream.
Moving groups previously identified in Hipparcos observations are easiest to
see in stars nearer than 250 pc, and their visibility and peak velocities in
the velocity distributions depends on both viewing direction (galactic
longitude and hemisphere) and metallicity. We infer that there is fine
structure in local velocity distributions that varies over distances of a few
hundred pc in the Galaxy.Comment: accepted for publication in MNRA
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