Σάββατο 17 Ιουνίου 2017
Scholar : Journal of Otolaryngology and Ophthalmology of Shandong University, Year 2017, Issue 02 -New Issue Alert.
Scholar : Beijing Journal of Stomatology, Year 2017, Issue 02 -New Issue Alert.
|
Scholar : Stomatology, Year 2017, Issue 05 -New Issue Alert.
|
Scholar : Journal of Audiology and Speech Pathology, Year 2017, Issue 03 -New Issue Alert.
|
Unrevealing the effect of different dispersion agents on the properties of ethylene–propylene copolymer/halloysite nanocomposites
Publication date: 5 October 2017
Source:Materials & Design, Volume 131
Author(s): E. Bischoff, G.P.O. Gonçalves, D.A. Simon, H.S. Schrekker, M. Lavorgna, L. Ambrosio, S.A. Liberman, R.S. Mauler
The properties of polyolefin nanocomposites strongly depend on the dispersion level of the nanoparticles and the addition of dispersion agents contributes to improving their performance. In this study, the morphology and the mechanical properties of heterophasic ethylene-propylene copolymer/halloysite nanocomposites were tailored by using two hydrogenated hydrocarbon resins: 90% and 100% hydrogenated and two compatibilizing agents: poly(propylene-g-maleic anhydride) and poly(ethylene-octene-g-maleic anhydride). The transmission electron microscopy indicated that the best dispersion of the halloysite nanotubes was achieved when hydrogenated hydrocarbon resins and poly(propylene-g-maleic anhydride) were used simultaneously. All nanocomposites showed an increase in mechanical stiffness and the most pronounced increase of 46% in the Young modulus was achieved with the system containing halloysite, poly(propylene-g-maleic anhydride) and the hydrocarbon resin with the higher degree of hydrogenation. Poly(ethylene-octene-g-maleic anhydride) caused the halloysite nanoparticles to concentrate preferentially in the rubber domains, wherein these hindered the crystallization of polypropylene and polyethylene chains, as showed by atomic force microscopy. In this case, the composite exhibited both high stiffness and improved toughness. These results highlight the key role of dispersion agents in promoting a good balance in the mechanical properties of resulting nanocomposites based on halloysite particles and heterophasic ethylene-propylene copolymers.
Graphical abstract
http://ift.tt/2sLoYtu
Physiological and molecular responses of the earthworm Eisenia fetida to polychlorinated biphenyl contamination in soil
Abstract
Polychlorinated biphenyls (PCBs) are a class of man-made organic compounds ubiquitously present in the biosphere. In this study, we evaluated the toxic effects of different concentrations of PCBs in two natural soils (i.e. red soil and fluvo-aquic soil) on the earthworm Eisenia fetida. The parameters investigated included anti-oxidative response, genotoxic potential, weight variation and biochemical responses of the earthworm exposed to two different types of soils spiked with PCBs after 7 or 14 days of exposure. Earthworms had significantly lower weights in both soils after PCB exposure. PCBs significantly increased catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (POD) activity in earthworms exposed to either soil type for 7 or 14 days and decreased the malondialdehyde (MDA) content in earthworms exposed to red soil for 14 days. Of the enzymes examined, SOD activity was the most sensitive to PCB stress. In addition, PCB exposure triggered dose-dependent coelomocyte DNA damage, even at the lowest concentration tested. This response was relatively stable between different soils. Three-way analysis of variance (ANOVA) showed that the weight variation, anti-oxidant enzyme activities, and MDA contents were significantly correlated with exposure concentration or exposure duration (P < 0.01). Furthermore, weight variation, CAT activity, and SOD activity were significantly affected by soil type (P < 0.01). Therefore, the soil type and exposure time influence the toxic effects of PCBs, and these factors should be considered when selecting responsive biomarkers.
http://ift.tt/2tzUXK3
The potential effect of temperature-humidity index on productive and reproductive performance of buffaloes with different genotypes under hot conditions
Abstract
The current study was aimed to investigate the impact of THI on productive and reproductive indices of PE and F1 crosses (50% PE and 50% Italian buffaloes) and back crosses (BC) (75% PE and 25% Italian buffaloes) under hot conditions. In this study, 8385 records used PE (1914, 1518, and 1737), F1 (387, 447, and 657), and BC (495, 585, and 645) for low, medium, and high THI, respectively. The high THI reduced the conception rate after first insemination in PE, F1, and BC ((odds ratio, OR) = 1.187, P = 0.007; 2.361, <0.0001 and 1.603, <0.0001, respectively) when compared with low THI. But, stillbirth and calving condition were not significantly influenced by different THI levels in BC and F1. BC was more bearable to the harsh environment; they possessed the highest incidence of conception after first insemination (72.70, 72.60, and 62.40%), producing live calves (98.50, 100, and 99.40%) with easy calving condition (98.50, 100, and 99.40%) when compared to PE and F1 at different levels of THI, respectively. The average daily milk yield and peak of milk production were decreased in PE (4.02 and 5.12%), BC (13.33 and 10.95%), and F1 (25.29 and 12.20%) from low to high THI. However, BC revealed no significant changes in days open, dry period, calving interval, gestation length, service per conception, and the first service post-partum at different levels of THI when compared with PE and F1. Therefore, rearing BC is recommended for improving buffalo productive and reproductive performance under hot conditions.
http://ift.tt/2sCCQpj
Metal release from contaminated leaf litter and leachate toxicity for the freshwater crustacean Gammarus fossarum
Abstract
Industrialization has left large surfaces of contaminated soils, which may act as a source of pollution for contiguous ecosystems, either terrestrial or aquatic. When polluted sites are recolonized by plants, dispersion of leaf litter might represent a non-negligible source of contaminants, especially metals. To evaluate the risks associated to contaminated leaf litter dispersion in aquatic ecosystems, we first measured the dynamics of metal loss from leaf litter during a 48-h experimental leaching. We used aspen (Populus tremula L.), a common tree species on these polluted sites, and collected leaf litter on three polluted sites (settling pond of a former steel mill) and three control sites situated in the same geographic area. Then, toxicity tests were carried out on individuals of a key detritivore species widely used in ecotoxicology tests, Gammarus fossarum (Crustacea, Amphipoda), with uncontaminated and contaminated leaf litter leachates, using a battery of biomarkers selected for their sensitivity to metallic stress. Leaf litters collected on polluted sites exhibited not only significantly higher cadmium and zinc concentrations but also lower lignin contents. All leaf litters released high amounts of chemical elements during the leaching process, especially potassium and magnesium, and, in a lesser extent, phosphorus, calcium, and trace metals (copper, cadmium, and zinc but not lead). Toxicity tests revealed that the most important toxic effects measured on G. fossarum were due to leaf litter leachates by themselves, whatever the origin of litter (from polluted or control sites), confirming the toxicity of such substances, probably due to their high content in phenolic compounds. Small additional toxic effects of leachates from contaminated leaf litters were only evidenced on gammarid lipid peroxidation, indicating that contaminated leaf litter leachates might be slightly more toxic than uncontaminated ones, but in a very reduced manner. Further studies will be required to verify if these patterns are generalizable to other species and to investigate the effects of contaminated leaf litter ingestion by consumers on aquatic food webs. Nevertheless, our results do not permit to exclude potential chronic effects of an exposure to contaminated leaf litter leachates in aquatic ecosystems.
http://ift.tt/2tA7VHq
Impact of heavy metal contamination on oxidative stress of Eisenia andrei and bacterial community structure in Tunisian mine soil
Abstract
The aims of this work were firstly to study the effect of heavy metal-polluted soils from Tunisian mine on earthworm biochemical biomarkers and on bacterial communities and therefore to analyze the interaction between earth worms and bacterial communities in these contaminated soils. For this purpose, we had introduced earthworm Eisenia andrei in six soils: one from mine spoils and five from agricultural soils, establishing a gradient of contamination. The response of worms to the presence of heavy metal was analyzed at the biochemical and transcriptional levels. In a second time, the impact of worm on bacterial community structure was investigated using automated ribosomal intergenic spacer analysis (ARISA) fingerprinting. An impact of heavy metal-contaminated soils on the oxidative status of E. andrei was observed, but this effect was dependent of the level of heavy metal contamination. Moreover, our results demonstrate that the introduction of earthworms E. andrei has an impact on bacterial community; however, the major change was observed in the less contaminated site. Furthermore, a significant correlation between earthworm oxidative status biomarkers and bacterial community structure was observed, mainly in the mine spoils. Therefore, we contribute to a better understanding of the relationships between epigenic earthworms and bacterial communities in heavy metal-contaminated soils.
http://ift.tt/2sCkOUj
Lung Adenocarcinoma Survival in EGFR-Mutated African-Caribbean Patients: A Multicenter Study in the French West Indies
Abstract
Background
Lung cancer is the leading cause of cancer-related death worldwide. Shorter survival has been repeatedly reported for patients of African ancestry. Multivariate analysis demonstrated that this gap could be a consequence of socio-economic disparities instead of genetic specificities. However, those results were obtained in a pre-targeted therapies era and the effect of tyrosine kinase inhibitors targeting EGFR are not known in this population.
Objective
In this French West Indies study, we report overall survival (OS) in a frequently mutated population treated for lung adenocarcinoma within an equal-access healthcare system.
Patients and Methods
Clinical, demographic, survival, and treatment data have been retrospectively assessed for all patients diagnosed with lung adenocarcinoma in the islands of Martinique and Guadeloupe between 2013 and 2015.
Results
Two hundred and forty-one patients (82% African-Caribbean) were included. EGFR mutations were detected in 37% of all tumor specimens and were associated with non-smoker status in multivariate analysis. Median OS was 16.2 months. For patients with advanced disease, median OS was 11.5 months, depending on EGFR mutation (23 vs. 8.3 months for non-mutated patients, p = 0.0012). There was no difference in survival according to ethnicity or island. In multivariate analysis, performance status (PS) and EGFR mutation were the only independent prognostic factors.
Conclusions
Despite a higher frequency of EGFR mutations in African-Caribbean patients, ethnicity was not an independent factor of OS in lung adenocarcinoma. Lower initial PS in this mainly non-smoking African-Caribbean population may explain the absence of a difference in OS.
http://ift.tt/2sFBVp6
Targeting the PD-1/PD-L1 Immune Checkpoint in EGFR- Mutated or ALK- Translocated Non-Small-Cell Lung Cancer
Abstract
Immune checkpoint inhibitors, notably antibodies targeting programmed death–1 (PD-1) and programmed death ligand–1 (PD-L1), have modified the management of patients with locally advanced or metastatic non-small-cell lung cancer (NSCLC). Several PD-1/PD-L1 inhibitors have been approved by health authorities for this indication and others are in clinical development. However, only a subset of patients truly benefits from these agents. For patients with mutated EGFR or translocated ALK NSCLC, for whom an immune checkpoint inhibitor can be prescribed after progression on tyrosine kinase inhibitors and chemotherapy, information is scarce and sometimes contradictory. Phase III randomized clinical trials have evaluated different immune checkpoint inhibitors (nivolumab, pembrolizumab, atezolizumab) vs. chemotherapy as second- or subsequent-line therapy in NSCLC, but included very few patients with EGFR/ALK-positive disease. Subgroup analyses found that these patients did not benefit from immune checkpoint inhibitors. Retrospective data show progression-free survival lasting only 1.2–2.1 months. Preclinical data suggested a lower expression of PD-L1 in EGFR/ALK-positive patients compared to EGFR/ALK-negative patients. Our objective herein is to provide an up-to-date review of available data from the various publications on the impact of immune checkpoint inhibitors in patients with EGFR/ALK-positive NSCLC.
http://ift.tt/2sFBr2f
The effects of a desiccant agent in the treatment of chronic periodontitis: a randomized, controlled clinical trial
Abstract
Objective
Chemotherapeutic agents have been widely used as adjuncts for the treatment of chronic periodontitis (CP). This study investigated and compared a desiccant agent as an adjunct to scaling and root planing (SRP) versus SRP alone for the treatment of CP.
Materials and methods
Thirty-six patients with CP were studied. Using a split-mouth design, the maxillary right and left quadrants were randomly assigned to SRP plus desiccant (Hybenx® EPIEN Medical, Inc. St. Paul, MN, USA) or SRP alone. Patients were examined on a regular basis for clinical, microbiological, and inflammatory mediator changes over a 1-year period. Clinical attachment level (CAL) was the primary outcome variable. In addition, the red complex bacteria and gingival crevicular fluid (GCF) inflammatory mediators were monitored.
Results
Compared to baseline, both treatments demonstrated an improvement in periodontal parameters. Compared to SRP alone, SRP plus desiccant yielded a significant improvement in probing depth (PD) (SRP: 2.23 ± 0.31 mm vs. desiccant: 3.25 ± 0.57 mm, p < 0.05), CAL (SRP: 3.16 ± 0.29 mm vs. desiccant: 4.21 ± 0.34 mm, p < 0.05 mm) and bleeding on probing (BOP) (SRP: 4.56 ± 1.5% vs. desiccant: 34.23 ± 4.2%, p < 0.001) at 12 months. Similarly, in the SRP plus desiccant group, the bacteria of the red complex were significantly reduced (p < 0.05); and the level of inflammatory mediators was significantly reduced (p < 0.003) compared to SRP alone.
Conclusions
SRP plus the desiccant resulted in a greater reduction in clinical, microbial and inflammatory mediators compared to SRP alone.
Clinical relevance
Desiccant, when combined to SRP, was demonstrated as a significant approach to control the levels of certain periodontal pathogens, inflammatory mediators in patients with CP.
http://ift.tt/2rrVSey
Does static electric field from ultra-high voltage direct-current transmission lines affect male reproductive capacity? Evidence from a laboratory study on male mice
Abstract
With the development of ultra-high-voltage direct-current (UHVDC) transmission technology and increase in transmission voltage, the issue of environmental static electric field (SEF) pollution is standing out and its possible health effects have caused much public attention. In this study, the effects of chronic exposure to SEF on reproductive capacity of male mice were investigated. Twenty Institute of Cancer Research (ICR) mice were exposed to SEF (56.3 ± 1.4 kV/m, 49 days) generated by a high-voltage device. Several biological end points related to spermatogenesis and testicular function were evaluated, including reproductive organ coefficients, sperm motility and morphology, serum testosterone level, and testicular histology. No significant differences were found between the SEF-exposed and sham-exposed groups at the end of the exposure period. However, further observation through transmission electron microscopy revealed cristae losses in mitochondria of spermatogenic cells after SEF exposure. Nevertheless, the mitochondria injury did not affect sperm motility, which might be explained from the perspective of energy supply. That is, most of the energy required for sperm movement is generated by glycolysis which occurs in the cytoplasm rather than oxidative phosphorylation which occurs in mitochondria. In conclusion, this study indicates that exposure to SEF (56.3 ± 1.4 kV/m, 49 days) has limited effects on male reproductive capacity.
http://ift.tt/2rCV6zD
Hexabromocyclododecane diastereomers in fish and suspended particulate matter from selected European waters—trend monitoring and environmental quality standard compliance
Abstract
The brominated flame retardant hexabromocyclododecane (HBCD) was monitored in fish and sediment (from one lake) or suspended particulate matter (SPM; from five rivers) at European freshwater sites to study the effects of reduction measures implemented by HBCD producers and users in recent years. Bream (Abramis brama) were sampled annually between 2007 and 2013 in the rivers Götaälv/SE, Rhône/FR, Western Scheldt/NL, Mersey/UK, and Tees/UK and in Lake Belau/DE. Sediment/SPM was taken every second year between 2008 and 2014. HBCD was analyzed by LC/MS/MS allowing the determination of the alpha-, beta-, and gamma-diastereomers. For most sites, a decrease in ∑HBCD was observed in fish (e.g., in the Rhône and Western Scheldt by about 80 and 60%, respectively, with significantly decreasing trends, p < 0.01). In the Rhône, HBCD also decreased in SPM. At the sampling site in the Tees which was impacted by a former HBCD point source, fish HBCD levels decreased only after a major flood event in 2013. While fish data indicate a decline in environmental HBCD concentrations at most sites with diffuse emissions, SPM data were less conclusive. The European environmental quality standard for HBCD in fish of 167 μg kg−1 wet weight was met by all fish samples in 2013.
http://ift.tt/2sndWbf
Εγγραφή σε:
Αναρτήσεις (Atom)
-
Summary Insulinomas are rare neuroendocrine tumours that classically present with fasting hypoglycaemia. This case report discusses an un...
-
The online platform for Taylor & Francis Online content New for Canadian Journal of Remote Sen...
