Homeostatic model assessment (HOMA) index cut-off values to identify the metabolic syndrome in children

The aim of the study was to establish the best cut-off value for the homeostatic model assessment (HOMA) index in identifying children and adolescents with the metabolic syndrome. The study included 72 non-obese and 68 obese children aged 7 to 16 years. Obesity is defined using the criteria proposed by Cole et al., being included as metabolic syndrome variables waist circumference, systolic blood pressure, diastolic blood pressure and seric values of glucose, uric acid, fasting insulin, leptin, triglycerides and HDL-cholesterol. Children were considered as having the metabolic syndrome when four or more characteristics showed abnormal values. The HOMA index was calculated as the product of the fasting plasma insulin level (microU/mL) and the fasting plasma glucose level (mmol/L), divided by 22.5. HOMA index cut-offs from the 5th to the 95th percentile were used. A receiver operating characteristic (ROC) curve was generated using the different HOMA cut-offs for the screening of the metabolic syndrome. The areas under the ROC curve, 95% confidence intervals, and the point to the ROC curve closest to 1, were calculated. The area under the ROC curve was 0.863 (95% C.I.: 0.797, 0.930). The point closest to 1 corresponds to the 60th percentile of the HOMA index distribution in our sample. HOMA index value at the 60th percentile was 2.28. Cut-off values corresponding to a range of HOMA index from the 50 to the 75 percentile, showed similar distances to 1. HOMA index values for percentiles 50 to 75 ranged from 2.07 to 2.83. In conclusion, HOMA index could be a useful tool to detect children and adolescents with the metabolic syndrome. HOMA cut-off values need to be defined in the paediatric population; however, values near to 3 seem to be adequate.     

Activation of IKK by TNFalpha requires site-specific ubiquitination of RIP1 and polyubiquitin binding by NEMO

The receptor interacting protein kinase 1 (RIP1) is essential for the activation of nuclear factor kappaB (NF-kappaB) by tumor necrosis factor alpha (TNFalpha). Here, we present evidence that TNFalpha induces the polyubiquitination of RIP1 at Lys-377 and that this polyubiquitination is required for the activation of IkappaB kinase (IKK) and NF-kappaB. A point mutation of RIP1 at Lys-377 (K377R) abolishes its polyubiquitination as well as its ability to restore IKK activation in a RIP1-deficient cell line. The K377R mutation of RIP1 also prevents the recruitment of TAK1 and IKK complexes to TNF receptor. Interestingly, polyubiquitinated RIP1 recruits IKK through the binding between the polyubiquitin chains and NEMO, a regulatory subunit of the IKK complex. Mutations of NEMO that disrupt its polyubiquitin binding also abolish IKK activation. These results reveal the biochemical mechanism underlying the essential signaling function of NEMO and provide direct evidence that signal-induced site-specific ubiquitination of RIP1 is required for IKK activation.     

Xanthine accumulation and vacuolization inChlamydomonas reinhardtii cells

Summary Utilization of xanthine as the sole nitrogen source for growth byChlamydomonas reinhardtii cells involved the formation of a transient, intracellular pool of xanthine. Up to 20% of the total xanthine supplied to the medium was not assimilated after uptake but stored in the cells at concentrations that exceeded xanthine solubility in water. At the subcellular level, a massive accumulation of starch grains in the chloroplast and the appearance of many vacuoles in the cytoplasm distinguished xanthine-grown from ammonium-grown cells. Starch accumulation, but not development of vacuoles, was also observed in N-starved cells. Uptake experiments with radio-labelled xanthine showed that this accumulates only in the cytoplasm, most probably inside vacuoles. The electron-dense material observed in vacuoles of xanthine-grown cells suggests that the intracellular xanthine is in part solid xanthine.     

Effects of a nucleopolyhedrovirus in mixtures with azadirachtin on Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) larvae and viral occlusion body production

Abstract

The combined and alone effects of azadirachtin (AZA) and Spodoptera frugiperda multicapsid nucleopolyhedrovirus (SfMNPV) on the mortality of S. frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) were evaluated in the laboratory. For this, diet surface contamination bioassays were performed on S. frugiperda in the third instar. LC₅₀ values for SfMNPV alone were determined to be 430 and 373 viral occlusion bodies (OBs)/mm² at 192 and 216 h after treatment, respectively. LC₅₀ values for AZA alone were estimated for two periods of continuous exposure (4 or 5 days). In this case, LC₅₀ values were 45.5 and 16.8 mg L^?1 at 216 h after treatment (4 or 5 days of larval exposition to insecticide, respectively). We observed that although the interaction of AZA with SfMNPV increased viral pathogenicity, such improvements were of greater magnitude and more consistent at the lower OB concentration used (177 OBs/mm²). Application of SfMNPV (430 OBs/mm²), AZA (26.4 mg L^?1) or SfMNPV–AZA mixtures resulted in a significant reduction in the mean weight of larvae treated in the third instar across the experiment, by 23–41%, 17–95% and 26–97%, respectively, compared to control. The duration of larval development during the third and fourth instars increased significantly in larvae exposed to SfMNPV–AZA mixtures and AZA alone compared to SfMNPV alone and control treatments. The yield of OBs/mg weight of larvae treated with SfMNPV alone was 1.8-fold higher than OB yields from insects inoculated with SfMNPV–AZA mixtures. We conclude that AZA + SfMNPV mixtures are unlikely to be useful for the mass production of this virus and laboratory observations on the value of AZA + SfMNPV mixtures as a potentiator of biological insecticides require validation in field studies under commercial growing conditions.     

Evaluation of several strategies to increase the residence time of Episyrphus balteatus (Diptera, Syrphidae) releases in sweet pepper greenhouses

We have investigated several factors affecting the augmentation of the aphidophagous syrphid Episyrphus balteatus in Mediterranean sweet pepper greenhouses. First, the effectiveness of releases has been assessed by recording the larva and pupa number. The abundance of E. balteatus varied between greenhouses, which was not observed to be a release effect. Second, two experiments were performed to assess the effect of three biological control management strategies on the release residence time. In the first experiment, the greenhouse ventilation was shown to have a significant influence on the adult population residence time, which was higher when the side walls were closed rather than open. The introduction of additional floral resources (sweet alyssum and coriander) did not have a significant effect on the release residence time. In the second experiment, the age of the released adults was assessed, and 2-day-old adults stayed longer in the greenhouse than 7-day-old adults, but the 7-day-old adults had more time to lay eggs. Although syrphids are effective aphid natural enemies, the release methodology of introducing pupae appears not to be effective in Mediterranean greenhouses. In this paper, we propose changing the methodology of releasing E. balteatus .     

Pattern diversity analysis of a clearing in a Quercus cerris wood

Linear transects were used to examine the spatial structure of the vegetation in a clearing in a Quercus cerris wood in Central Italy. A grassland-margin-shrubland-woodland gradient was identified.Multivariate classification and ordination methods and pattern diversity analysis were used to detect both floristic variation and spatial organization. One of the transects shows a clear gradient of variation as a function of space, crossing the floristically and structurally most heterogeneous part of the clearing. For the detailed analysis of this transect a sectorization is achieved. Each sector is characterized according to its floristic types and to the internal spatial organization.The pieces of information derived from the different analyses were concordant. In particular, the validity of the floristic types in the qualification of the different forms of spatial organization is confirmed.     

Synergistic and antagonistic effects of mixing monospecific soils on plant-soil feedbacks

Background and aims

Disturbance affects the ability of organisms to persist on a site, and disturbance history acts as a filter of community composition. This is true for vascular plants and morphological groups of biocrusts, which respond differently to disturbance. Although functioning arid ecosystems include both groups, filtering of morphological groups of biocrusts has not previously been compared simultaneously with the responses of vascular plants.

Methods

Using a chronosequence approach, cover of vascular plants and biocrusts was examined across chronic disturbance gradients related to invasion by exotic species and grazing by livestock, following the acute disturbance of fire using paired burned and unburned plots in Wyoming big sagebrush on 99 plots.

Results

Cover of vascular plants and biocrusts was related to disturbance more so than abiotic factors of precipitation following fire, soil chemistry, percent coarse fragment and heat load index. Over time since fire of 12–23 years, we saw recovery of early successional groups: short mosses, shallow-rooted perennial grasses and annual forbs. Cover of deep and shallow-rooted perennial grasses and annual forbs increased in cover with intermediate levels of disturbance. Perennial forbs lacked a clear relationship with disturbance. Biocrusts decreased in cover with less disturbance when compared with perennial herbaceous plants but differed in sensitivities. Tall mosses were less sensitive to disturbance compared with lichens. Short mosses increased with some disturbance.

Conclusions

Morphological groups of biocrusts and vascular plants are eliminated with increasing variability in the size of gaps between perennials represented by the standard deviation of gaps between perennials. The inclusion of both groups in assessments of ecosystem recovery following disturbance addresses the fact that recovery of either group does not happen in isolation from the other but with interacting contributions to ecosystem functions.

     

Trypanosomatid parasites rescue heme from endocytosed hemoglobin through lysosomal HRG transporters

Pathogenic trypanosomatid parasites are auxotrophic for heme and they must scavenge it from their human host. Trypanosoma brucei (responsible for sleeping sickness) and Leishmania (leishmaniasis) can fulfill heme requirement by receptor‐mediated endocytosis of host hemoglobin. However, the mechanism used to transfer hemoglobin‐derived heme from the lysosome to the cytosol remains unknown. Here we provide strong evidence that HRG transporters mediate this essential step. In bloodstream T. brucei, TbHRG localizes to the endolysosomal compartment where endocytosed hemoglobin is known to be trafficked. TbHRG overexpression increases cytosolic heme levels whereas its downregulation is lethal for the parasites unless they express the Leishmania orthologue LmHR1. LmHR1, known to be an essential plasma membrane protein responsible for the uptake of free heme in Leishmania, is also present in its acidic compartments which colocalize with endocytosed hemoglobin. Moreover, LmHR1 levels modulated by its overexpression or the abrogation of an LmHR1 allele correlate with the mitochondrial bioavailability of heme from lysosomal hemoglobin. In addition, using heme auxotrophic yeasts we show that TbHRG and LmHR1 transport hemoglobin‐derived heme from the digestive vacuole to the cytosol. Collectively, these results show that trypanosomatid parasites rescue heme from endocytosed hemoglobin through endolysosomal HRG transporters, which could constitute novel drug targets.