Relative fat oxidation is higher in children than adults

Background: Prepubescent children may oxidize fatty acids more readily than adults. Therefore, dietary fat needs would be higher for children compared with adults. The dietary fat recommendations are higher for children 4 to 18 yrs (i.e., 25 to 35% of energy) compared with adults (i.e., 20 to 35% of energy). Despite this, many parents and children restrict dietary fat for health reasons. Methods: This study assessed whether rates of fat oxidation are similar between prepubescent children and adults. Ten children (8.7 ± 1.4 yr, 33 ± 13 kg mean ± SD) in Tanner stage 1 and 10 adults (41.6 ± 8 yr, 74 ± 13 kg) were fed a weight maintenance diet for three days to maintain body weight and to establish a consistent background for metabolic rate measurements (all foods provided). Metabolic rate was measured on three separate occasions before and immediately after breakfast and for 9 hrs using a hood system (twice) or a room calorimeter (once) where continuous metabolic measurements were taken. Results: During all three sessions whole body fat oxidation was higher in children (lower RQ) compared to adults (mean RQ= 0.84 ± .016 for children and 0.87 ± .02, for adults, p < 0.02). Although, total grams of fat oxidized was similar in children (62.7 ± 20 g/24 hrs) compared to adults (51.4 ± 19 g/24 hrs), the grams of fat oxidized relative to calorie expenditure was higher in children (0.047 ± .01 g/kcal, compared to adults (0.032 ± .01 p < 0.02). Females oxidized more fat relative to calorie expenditure than males of a similar age. A two way ANOVA showed no interaction between gender and age in terms of fax oxidation. Conclusion: These data suggest that fat oxidation relative to total calorie expenditure is higher in prepubescent children than in adults. Consistent with current dietary guidelines, a moderate fat diet is appropriate for children within the context of a diet that meets their energy and nutrient needs. Originally published Nutrition Journal, Vol. 6, No. 19, Aug 200

Assessment of Soil Organic Carbon Stability in Agricultural Systems by Using Natural Abundance Signals of Stable Carbon and Nitrogen Isotopes

Information on the stability and age of soil organic matter (SOM) pools is of vital importance for assessing the impact of soil management and environmental factors on SOM, an important part of the global carbon (C) cycle. The terrestrial soil organic C pool, up to a depth of 1 m, contains about 1500 Pg C (Batjes, 1996). This is about 2.5 times more organic C than the vegetation (650 Pg C) and about twice as much as in the atmosphere (750 Pg C) (Batjes, 1998), but the assessment of the stability and age of SOM using 14C radio carbon technique are expensive. Conen et al. (2008) developed a model to estimate the SOM stability based on the isotopic discrimination of 15N natural abundance by soil micro-organisms and the change in C/N ratio during organic matter decomposition, for steady state, Alpine and permanent grasslands. In the framework of the IAEA funded coordinated research project (CRP) on Soil Quality and Nutrient Management for Sustainable Food Production in Mulch based Cropping Systems in sub-Saharan Africa, research was initiated to use this model in agricultural systems for developing a cost effective and affordable technique for Member States to determine the stability of SOM.status: publishe

Predicting soil organic matter stability in agricultural fields through carbon and nitrogen stable isotopes

In order to evaluate the sustainability and efficiency of soil carbon sequestration measures and the impact of different management and environmental factors, information on soil organic matter (SOM) stability and mean residence time (MRT) is required. However, this information on SOM stability and MRT is expensive to determine via radiocarbon dating, precluding a wide spread use of stability measurements in soil science. In this paper, we test an alternative method, first developed by Conen et al. (2008) for undisturbed Alpine grassland systems, using C and N stable isotope ratios in more frequently disturbed agricultural soils. Since only information on carbon and nitrogen concentrations and their stable isotope ratios is required, it is possible to estimate the SOM stability at greatly reduced costs compared to radiocarbon dating. Using four different experimental sites located in various climates and soil types, this research proved the effectiveness of using the C/N ratio and δ15N signature to determine the stability of mOM (mineral associated organic matter) relative to POM (particulate organic matter) in an intensively managed agro-ecological setting. Combining this approach with δ13C measurements allowed discriminating between different management (grassland vs cropland) and land use (till vs no till) systems. With increasing depth the stability of mOM relative to POM increases, but less so under tillage compared to no-till practises. Applying this approach to investigate SOM stability in different soil aggregate fractions, it corroborates the aggregate hierarchy theory as proposed by Six et al. (2004) and Segoli et al. (2013). The organic matter in the occluded micro-aggregate and silt & clay fractions is less degraded than the SOM in the free micro-aggregate and silt & clay fractions. The stable isotope approach can be particularly useful for soils with a history of burning and thus containing old charcoal particles, preventing the use of 14C to determine the SOM stability.publisher: Elsevier articletitle: Predicting soil organic matter stability in agricultural fields through carbon and nitrogen stable isotopes journaltitle: Soil Biology and Biochemistry articlelink: http://dx.doi.org/10.1016/j.soilbio.2015.05.011 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved.status: publishe

Wrap attack activates web-decorating behavior in Argiope spiders

Various orb-weaving spiders add extra silk structures--"web decorations"--to their webs. The adaptive value of these web decorations is still unclear, and the suite of functional hypotheses remains controversial. Spiders in the genus Argiope decorate their webs with densely woven zigzag ribbons made of fibrous aciniform silk. This type of silk is also used by the spiders for "wrap attacks" to immobilize the prey by wrapping it with a dense silk cover. Previous studies suggested that the spiders use accumulated excess silk for building web decorations due to a constant secretion in the aciniform glands. We test if this hypothesis holds for 3 species, which construct different types of web decorations: linear in Argiope bruennichi, irregular in Argiope sector, and cruciate in Argiope keyserlingi. We show that depletion of aciniform silk has a stimulating effect on web-decorating behavior in 3 species of Argiope. The aciniform glands apparently readily overcompensated experimentally induced silk losses, and so silk depletion may result in the activation of the according glands. We suggest that the aciniform gland activation might be an important mechanism for Argiope's wrap attack to ensure sufficient wrapping of silk under high prey density and repeated wrapping events. The web decorations might function as a mechanism to maintain high gland activity, thereby maximizing the efficiency of the wrap attack strategy of Argiope. Copyright 2008, Oxford University Press.

Safety and efficacy of rasagiline as an add-on therapy to riluzole in patients with amyotrophic lateral sclerosis: a randomised, double-blind, parallel-group, placebo-controlled, phase 2 trial

Background Rasagiline, a monoamine oxidase B inhibitor with neuroprotective potential in Parkinson's disease, has shown a disease-modifying effect in the SOD1-Gly93Ala low-expressing mouse model of amyotrophic lateral sclerosis, both alone and in combination with riluzole. We sought to test whether or not rasagiline 1 mg/day can prolong survival in patients with amyotrophic lateral sclerosis also receiving riluzole. Methods Patients with possible, probable, or definite amyotrophic lateral sclerosis were enrolled to our randomised, placebo-controlled, parallel-group, double-blind, phase 2 trial from 15 German network for motor neuron diseases (MND-NET) centres (university hospitals or clinics). Eligible patients were aged at least 18 years, had onset of progressive weakness within the 36 months before the study, had disease duration of more than 6 months and less than 3 years, and had a best-sitting slow vital capacity of at least 50%. After a 4-week screening period, eligible patients were randomly assigned (1:1) to receive either rasagiline (1 mg/day) or placebo in addition to riluzole (100 mg/day), after stratification for site of onset (bulbar or spinal) and study centre. Patients and all personnel assessing outcome parameters were masked to treatment allocation. Patients were followed up 2, 6, 12, and 18 months after randomisation. The primary endpoint was survival time, defined as the time to death or time to study cutoff date (ie, the last patient's last visit plus 14 days). Analyses of primary outcome and safety measures were done in all patients who received at least one dose of trial treatment (intention-to-treat population). The trial is registered with ClinicalTrials.gov, number NCT01879241. Findings Between July 2, 2013, and Nov 11, 2014, 273 patients were screened for eligibility, and 252 patients were randomly assigned to receive rasagiline (n=127) or placebo (n=125). 126 patients taking rasagiline and 125 taking placebo were included in the intention-to-treat analysis. For the primary outcome, the survival probability at the end of the study was 0.43 (95% CI 0.25-0.59) in the rasagiline group (n=126) and 0.53 (0.43-0.62) in the placebo group (n=125). The estimated effect size (hazard ratio) was 0.91 (one-sided 97.5% CI -infinity to 1.34; p=0.31). Rasagiline was well tolerated, and most adverse events were due to amyotrophic lateral sclerosis disease progression rather than treatment; the most frequent of these were dysphagia (32 [25%] taking rasagiline vs 24 [19%] taking placebo) and respiratory failure (25 [20%] vs 31 [25%]). Frequency of adverse events were comparable between both groups. Interpretation Rasagiline was safe in patients with amyotrophic lateral sclerosis. There was no difference between groups in the primary outcome of survival, although post-hoc analysis suggested that rasagiline might modify disease progression in patients with an initial slope of Amyotrophic Lateral Sclerosis Functional Rating Scale Revised greater than 0.5 points per month at baseline. This should be confirmed in another clinical trial. Copyright (C) 2018 Elsevier Ltd. All rights reserved