Comparison of accelerometer measured levels of physical activity and sedentary time between obese and non-obese children and adolescents: a systematic review

Background: Obesity has been hypothesized to be associated with reduced moderate-to-vigorous physical activity (MVPA) and increased sedentary time (ST). It is important to assess whether, and the extent to which, levels of MVPA and ST are suboptimal among children and adolescents with obesity. The primary objective of this study was to examine accelerometer-measured time spent in MVPA and ST of children and adolescents with obesity, compared with MVPA recommendations, and with non-obese peers. Methods: An extensive search was carried out in Medline, Cochrane library, EMBASE, SPORTDiscus, and CINAHL, from 2000 to 2015. Study selection and appraisal: studies with accelerometer-measured MVPA and/or ST (at least 3 days and 6 h/day) in free-living obese children and adolescents (0 to 19 years) were included. Study quality was assessed formally. Meta-analyses were planned for all outcomes but were precluded due to the high levels of heterogeneity across studies. Therefore, narrative syntheses were employed for all the outcomes. Results: Out of 1503 records, 26 studies were eligible (n = 14,739 participants; n = 3523 with obesity); 6/26 studies involved children aged 0 to 9 years and 18/26 involved adolescents aged 10.1 to19 years. In the participants with obesity, the time spent in MVPA was consistently below the recommended 60 min/day and ST was generally high regardless of the participant’s age and gender. Comparison with controls suggested that the time spent in MVPA was significantly lower in children and adolescents with obesity, though differences were relatively small. Levels of MVPA in the obese and non-obese were consistently below recommendations. There were no marked differences in ST between obese and non-obese peers. Conclusions: MVPA in children and adolescents with obesity tends to be well below international recommendations. Substantial effort is likely to be required to achieve the recommended levels of MVPA among obese individuals in obesity treatment interventions

Generalized Background-Field Method

The graphical method discussed previously can be used to create new gauges not reachable by the path-integral formalism. By this means a new gauge is designed for more efficient two-loop QCD calculations. It is related to but simpler than the ordinary background-field gauge, in that even the triple-gluon vertices for internal lines contain only four terms, not the usual six. This reduction simplifies the calculation inspite of the necessity to include other vertices for compensation. Like the ordinary background-field gauge, this generalized background-field gauge also preserves gauge invariance of the external particles. As a check of the result and an illustration for the reduction in labour, an explicit calculation of the two-loop QCD $\beta$-function is carried out in this new gauge. It results in a saving of 45% of computation compared to the ordinary background-field gauge.Comment: 17 pages, Latex, 18 figures in Postscrip

Editorial: Hypoxia and Cardiorespiratory Control

To maintain adequate oxygen levels in the body, which is essential for a healthy life, the respiratory and cardiovascular systems play vitally important roles. When the oxygen content is insufficient, i.e., when hypoxia is loaded, respiratory and cardiovascular systems respond to restore, compensate, or adapt to hypoxia, e.g., by increasing ventilation and blood flow to maintain oxygen transport to vital organs. Traditionally, it has been thought that hypoxia is detected solely by carotid and aortic bodies, i.e., by peripheral chemoreceptors, and information from the peripheral chemoreceptors is transmitted to respiratory and cardiovascular centers in the brainstem whose respiratory and cardiovascular neural outputs are regulated. However, recent progress in neurophysiology has clarified that there are hypoxia-sensors not only in the periphery but also in the central nervous system. Hypoxia also affects the vascular system causing atherosclerosis and pulmonary hypertension and impairs blood glucose regulation that also facilitates atherosclerosis. The effects of hypoxia on vital organs and tissues vary depending on the modality of hypoxia exposure, i.e., acute, chronically sustained, or intermittent hypoxia. Although these issues have been vigorously investigated, the underlying mechanisms are yet to be unraveled. Likewise, long-range consequences for organ and tissue functions affected by hypoxia have not been fully elucidated. In the article collection of this Research Topic, a series of studies report the latest and most notable pathophysiological findings that are categorized into four areas: respiratory control, glucose metabolism, pulmonary hypertension, and sympathetic nervous system activation. The articles attempt to clarify many of the unsolved issues summarized below. (Introduction

Comparison of accelerometer measured levels of physical activity and sedentary time between obese and non-obese children and adolescents : a systematic review

Background: Obesity has been hypothesized to be associated with reduced moderate-to-vigorous physical activity (MVPA) and increased sedentary time (ST). It is important to assess whether, and the extent to which, levels of MVPA and ST are suboptimal among children and adolescents with obesity. The primary objective of this study was to examine accelerometer-measured time spent in MVPA and ST of children and adolescents with obesity, compared with MVPA recommendations, and with non-obese peers. Method: An extensive search was carried out in Medline, Cochrane library, EMBASE, SPORTDiscus, and CINAHL, from 2000-2015. Study selection and appraisal: studies with accelerometer-measured MVPA and/or ST (at least 3 days and 6 hours/day) in free-living obese children and adolescents (0-19 years) were included. Study quality was assessed formally. Meta-analyses were planned for all outcomes but were precluded due to the high levels of heterogeneity across studies. Therefore, narrative syntheses were employed for all the outcomes. Results: Out of 1503 records, 26 studies were eligible with a total (n =14739 participants; n =3523 with obesity); 6/26 studies involved children aged 0-9 years and 18/26 involved adolescents aged 10.1-19 years. In the participants with obesity, the time spent in MVPA was consistently below the recommended 60 minutes/day and ST was generally high regardless of the participant’s age and gender. Comparison with controls suggested that the time spent in MVPA was significantly lower in children and adolescents with obesity, though differences were relatively small. Levels of MVPA in the obese and non-obese were consistently below recommendations. There were no marked differences in ST between obese and non-obese peers. Conclusions: MVPA in children and adolescents with obesity tends to be well below international recommendations. Substantial effort is likely to be required to achieve the recommended levels of MVPA among obese individuals in obesity treatment interventions

Validity, practical utility, and reliability of the activPAL in preschool children

<p>Purpose: With the increasing global prevalence of childhood obesity, it is important to have appropriate measurement tools for investigating factors (e.g. sedentary time) contributing to positive energy balance in early childhood. For pre-school children, single unit monitors such as the activPALTM are promising. However, validation is required as activity patterns differ from adults.</p> <p>Methods: Thirty pre-school children participated in a validation study. Children were videoed for one hour undertaking usual nursery activity while wearing an activPALTM. Video (criterion method) was analyzed on a second-by-second basis to categorise posture and activity. This was compared with the corresponding activPALTM output. In a subsequent sub-study investigating practical utility and reliability, 20 children wore an activPALTM for seven consecutive 24-hour periods.</p> <p>Results: A total of 97,750 seconds of direct observation from 30 children were categorized as sit/lie (46%), stand (35%), walk (16%); with 3% of time in nonsit/lie/upright postures (e.g. crawl/crouch/kneel-up). Sensitivity for the overall total time matched seconds detected as activPALTM ‘sit/lie’ was 86.7%, specificity 97.1%, and positive predictive value (PPV) 96.3%. For individual children, the median (interquartile range) sensitivity for activPALTM sit/lie was 92.8% (76.1-97.4), specificity 97.3% (94.9-99.2), PPV 97.0% (91.5-99.1). The activPALTM underestimated total time spent sitting (mean difference -4.4%, p<0.01), and overestimated time standing (mean difference 7.1%, p<0.01). There was no difference in overall % time categorised as ‘walk’ (p=0.2). The monitors were well tolerated by children during a seven day period of free-living activity. In the reliability study, at least five days of monitoring were required to obtain an intraclass correlation coefficient of ≥0.8 for time spent sit/lie according to activPALTM output.</p> <p>Conclusion: The activPAL had acceptable validity, practical utility, and reliability for the measurement of posture and activity during freeliving activities in pre-school children.</p&gt

Influence of age on respiratory modulation of muscle sympathetic nerve activity, blood pressure and baroreflex function in humans

New Findings What is the central question of this study? Does ageing influence the respiratory‐related bursting of muscle sympathetic nerve activity (MSNA) and the association between the rhythmic fluctuations in MSNA and blood pressure (Traube–Hering waves) that occur with respiration? What is the main finding and its importance? Despite the age‐related elevation in MSNA, the cyclical inhibition of MSNA during respiration is similar between young and older individuals. Furthermore, central respiratory–sympathetic coupling plays a role in the generation of Traube–Hering waves in both young and older humans. Healthy ageing and alterations in respiratory–sympathetic coupling have been independently linked with heightened sympathetic neural vasoconstrictor activity. We investigated how age influences the respiratory‐related modulation of muscle sympathetic nerve activity (MSNA) and the association between the rhythmic fluctuations in MSNA and blood pressure that occur with respiration (Traube–Hering waves; THW). Ten young (22 ± 2 years; mean ± SD) and 10 older healthy men (58 ± 6 years) were studied while resting supine and breathing spontaneously. MSNA, blood pressure and respiration were recorded simultaneously. Resting values were ascertained and respiratory cycle‐triggered averaging of MSNA and blood pressure measurements performed. The MSNA burst incidence was higher in older individuals [22.7 ± 9.2 versus 42.2 ± 13.7 bursts (100 heart beats)−1, P < 0.05], and was reduced to a similar extent in the inspiratory to postinspiratory period in young and older subjects (by ∼25% compared with mid‐ to late expiration). A similar attenuation of MSNA burst frequency (in bursts per minute), amplitude and total activity (burst frequency × mean burst amplitude) was also observed in the inspiratory to postinspiratory period in both groups. A significant positive correlation between respiratory‐related MSNA and the magnitude of Traube–Hering waves was observed in all young (100%) and most older subjects (80%). These data suggest that the strength of the cyclical inhibition of MSNA during respiration is similar between young and older individuals; thus, alterations in respiratory–sympathetic coupling appear not to contribute to the age‐related elevation in MSNA. Furthermore, central respiratory–sympathetic coupling plays a role in the generation of Traube–Hering waves in both healthy young and older humans

Long interleukin-22 binding protein isoform-1 is an intracellular activator of the unfolded protein response

The human IL22RA2 gene co-produces three protein isoforms in dendritic cells [IL-22 binding protein isoform-1 (IL-22BPi1), IL-22BPi2, and IL-22BPi3]. Two of these, IL-22BPi2 and IL-22BPi3, are capable of neutralizing the biological activity of IL-22. The function of IL-22BPi1, which differs from IL-22BPi2 through an in-frame 32-amino acid insertion provided by an alternatively spliced exon, remains unknown. Using transfected human cell lines, we demonstrate that IL-22BPi1 is secreted detectably, but at much lower levels than IL-22BPi2, and unlike IL-22BPi2 and IL-22BPi3, is largely retained in the endoplasmic reticulum (ER). As opposed to IL-22BPi2 and IL-22BPi3, IL-22BPi1 is incapable of neutralizing or binding to IL-22 measured in bioassay or assembly-induced IL-22 co-folding assay. We performed interactome analysis to disclose the mechanism underlying the poor secretion of IL-22BPi1 and identified GRP78, GRP94, GRP170, and calnexin as main interactors. Structure-function analysis revealed that, like IL-22BPi2, IL-22BPi1 binds to the substrate-binding domain of GRP78 as well as to the middle domain of GRP94. Ectopic expression of wild-type GRP78 enhanced, and ATPase-defective GRP94 mutant decreased, secretion of both IL-22BPi1 and IL-22BPi2, while neither of both affected IL-22BPi3 secretion. Thus, IL-22BPi1 and IL-22BPi2 are bona fide clients of the ER chaperones GRP78 and GRP94. However, only IL-22BPi1 activates an unfolded protein response (UPR) resulting in increased protein levels of GRP78 and GRP94. Cloning of the IL22RA2 alternatively spliced exon into an unrelated cytokine, IL-2, bestowed similar characteristics on the resulting protein. We also found that CD14⁺⁺/CD16⁺ intermediate monocytes produced a higher level of IL22RA2 mRNA than classical and non-classical monocytes, but this difference disappeared in immature dendritic cells (moDC) derived thereof. Upon silencing of IL22RA2 expression in moDC, GRP78 levels were significantly reduced, suggesting that native IL22RA2 expression naturally contributes to upregulating GRP78 levels in these cells. The IL22RA2 alternatively spliced exon was reported to be recruited through a single mutation in the proto-splice site of a Long Terminal Repeat retrotransposon sequence in the ape lineage. Our work suggests that positive selection of IL-22BPi1 was not driven by IL-22 antagonism as in the case of IL-22BPi2 and IL-22BPi3, but by capacity for induction of an UPR response.Paloma Gómez-Fernández, Andoni Urtasun, Adrienne W. Paton, James C. Paton, Francisco Borrego, Devin Dersh, Yair Argon, Iraide Alloza and Koen Vandenbroec

Branching patterns in phylogenies cannot distinguish diversity-dependent diversification from time-dependent diversification

One of the primary goals of macroevolutionary biology has been to explain general trends in long‐term diversity patterns, including whether such patterns correspond to an upscaling of processes occurring at lower scales. Reconstructed phylogenies often show decelerated lineage accumulation over time. This pattern has often been interpreted as the result of diversity‐dependent (DD) diversification, where the accumulation of species causes diversification to decrease through niche filling. However, other processes can also produce such a slowdown, including time dependence without diversity dependence. To test whether phylogenetic branching patterns can be used to distinguish these two mechanisms, we formulated a time‐dependent, but diversity‐independent model that matches the expected diversity through time of a DD model. We simulated phylogenies under each model and studied how well likelihood methods could recover the true diversification mode. Standard model selection criteria always recovered diversity dependence, even when it was not present. We correct for this bias by using a bootstrap method and find that neither model is decisively supported. This implies that the branching pattern of reconstructed trees contains insufficient information to detect the presence or absence of diversity dependence. We advocate that tests encompassing additional data, for example, traits or range distributions, are needed to evaluate how diversity drives macroevolutionary trends

Direct exfoliation and dispersion of two-dimensional materials in pure water via temperature control

The high-volume synthesis of two-dimensional (2D) materials in the form of platelets is desirable for various applications. While water is considered an ideal dispersion medium, due to its abundance and low cost, the hydrophobicity of platelet surfaces has prohibited its widespread use. Here we exfoliate 2D materials directly in pure water without using any chemicals or surfactants. In order to exfoliate and disperse the materials in water, we elevate the temperature of the sonication bath, and introduce energy via the dissipation of sonic waves. Storage stability greater than one month is achieved through the maintenance of high temperatures, and through atomic and molecular level simulations, we further discover that good solubility in water is maintained due to the presence of platelet surface charges as a result of edge functionalization or intrinsic polarity. Finally, we demonstrate inkjet printing on hard and flexible substrates as a potential application of water-dispersed 2D materials.close1

Binary credal classification under sparsity constraints.

Binary classification is a well known problem in statistics. Besides classical methods, several techniques such as the naive credal classifier (for categorical data) and imprecise logistic regression (for continuous data) have been proposed to handle sparse data. However, a convincing approach to the classification problem in high dimensional problems (i.e., when the number of attributes is larger than the number of observations) is yet to be explored in the context of imprecise probability. In this article, we propose a sensitivity analysis based on penalised logistic regression scheme that works as binary classifier for high dimensional cases. We use an approach based on a set of likelihood functions (i.e. an imprecise likelihood, if you like), that assigns a set of weights to the attributes, to ensure a robust selection of the important attributes, whilst training the model at the same time, all in one fell swoop. We do a sensitivity analysis on the weights of the penalty term resulting in a set of sparse constraints which helps to identify imprecision in the dataset