خيارات البحث
النتائج 3111 - 3120 من 4,308
The herbicides trifluralin and tebuthiuron have no genotoxic or mutagenic potential as evidenced by genetic tests النص الكامل
2017
Franco-Bernardes, Mariana Furio | Rocha, Otávio Pelegrino | Pereira, Lilian Cristina | Tasso, Maria Júlia | Meireles, Gabriela | Oliveira, Danielle Palma de | Dorta, Daniel Junqueira
Brazil has been the largest world consumer of pesticides since 2008, followed by the USA. The herbicides trifluralin and tebuthiuron have been widely applied in agriculture. These herbicides are selective for some plant species, and their use brings various benefits. However, the genotoxic and mutagenic effects of tebuthiuron on non-target organisms are poorly known, and in addition, the effects of trifluralin must be better investigated. Therefore, this study employed genetic tests including the comet assay and micronucleus test to evaluate the genotoxic effects of trifluralin and tebuthiuron on HepG2 cells. In addition, we have used the Ames test to assess the mutagenic effects of the herbicides on the TA97a, TA98, TA100, and TA1535 strains of Salmonella typhimurium. On the basis of the comet assay and the micronucleus test, trifluralin did not cause genetic damage to HepG2 cells. In addition, trifluralin did not impact the tested S. typhimurium strains. Regarding tebuthiuron, literature has shown that this herbicide damaged DNA in Oreochromis niloticus. Nevertheless, we have found that tebuthiuron was not genotoxic to either HepG2 cells or the S. typhimurium strains. Therefore, neither trifluralin nor tebuthiuron exerted genotoxic or mutagenic potential at the tested conditions.
اظهر المزيد [+] اقل [-]Perfluoroalkyl substances with isomer analysis in umbilical cord serum in China النص الكامل
2017
Zhang, Ya-Zhi | Zeng, Xiao-Wen | Qian, Zhengmin (Min) | Vaughn, Michael G. | Geiger, Sarah Dee | Hu, Liwen | Lu, Long | Fu, Chuanxi | Dong, Guang-Hui
Perfluoroalkyl substances (PFASs) are a class of widely used chemicals that have been detected in the environment and general population. However, the isomer patterns in human are poorly characterized. Previous studies observed the isomer-specific maternal-fetal transfer of PFASs in human. In our current study, we first examined the profile of PFASs and isomers, including 17 linear PFASs and 10 branched PFOS/PFOA isomers by using isotopic internal standards in umbilical cord serum samples from Guangzhou, China. We collected a total of 321 of cord blood serum samples from July to October in 2013, and analyzed the PFASs concentration with isomer-specific PFASs analysis method. The results showed that 9 out of 17 PFASs (linear PFASs) were detected (>50% detection rate). Perfluorohexane sulfonate (PFHxS, median 3.87 ng/mL) was the predominant, followed by total PFOS (median 2.99 ng/mL) and total PFOA (median 1.23 ng/mL) in cord serum. In addition, 1m-, iso-, ∑3+4+5m-PFOS and iso-PFOA were the branched PFASs detected in the current study. The proportion of linear PFOS (n-PFOS) was 75.16% of ∑PFOS which was similar to the proportion of electrochemical fluorination that produces ca. 70% linear PFOS and 30% branched. On the contrary, linear PFOA (n-PFOA) accounted for 98.69% ∑PFOA in cord serum samples. Our finding indicates distinct PFASs and PFOS/PFOA isomer profile in cord serum, suggesting there might be a different exposure pathway and metabolism of PFASs.
اظهر المزيد [+] اقل [-]The effect of corn distiller’s dried grains with solubles (DDGS) fortified with enzyme on growth performance of broiler النص الكامل
2017
Abudabos, AlaeldeinMahmood | Al-Atiyat, RaedMuhammad | Stanley, Dragons | Aljassim, Rafat | Albatshan, HamadAli
The objective of the current study was to investigate the effect of corn distiller’s dried grains with solubles (DDGS) and enzyme supplementation on growth performance and carcass yield in broiler chickens. The experiment was a 5 × 3 factorial design with 450 broiler chickens and with diets containing five levels of DDGS (0, 6, 12, 18, and 24%) and three levels of the enzymes (no supplementation, Rovabio® enzyme, and Tomoko® enzyme). Five pens with six chicks were fed an experimental diet from 0 to 35 days of age. Diets containing 12, 18, and 24% DDGS decreased performance (P < 0.05) at the start of the trial at 0–10 days. Inclusion of enzyme during 0–10 days improved body weight gain (BWG) and European production efficiency factor (EPEF) (P < 0.05). During the grower (11–24 days) and finisher (25–35 days) periods, chickens which had received 0, 6, or 12% DDGS converted feed to body weight more efficiently (P < 0.05). Enzyme supplementation improved feed conversion ratio (FCR) for the periods (11–24 and 25–35 days, respectively) (P < 0.05). The cumulative performance results (0 to 35 days of age) showed that Tomoko enzyme improved FCR as compared to no enzyme while Rovabio was intermediate (P < 0.05). Chickens which had received 0, 6, or 12% had better FCR (P < 0.05) compared to 18 or 24% DDGS. Chick’s performance was depressed at early age when the diet contained 12% DDGS but later, they were able to tolerate higher levels of DDGS. The study indicate that a maximum level of DDGS to use in the starter diets is 6% and it could be increased in the grower and finisher period to 12% and enzyme supplementation to diets containing DDGS can improve FCR and growth performance in broilers.
اظهر المزيد [+] اقل [-]Hydrochemical evaluation and identification of geochemical processes in the shallow and deep wells in the Ramganga Sub-Basin, India النص الكامل
2017
Rajmohan, Natarajan | Chowdhary, Neelam Patel | Singh, Gaurav | Amarasinghe, UpaliA.
Groundwater samples were collected from 44 wells in the Ramganga Sub-Basin (RSB), India, and analysed for major ions, nutrients and trace metals. The primary goal of this study is to evaluate the hydrochemistry and to identify the geochemical processes that govern the water chemistry in the shallow and deep tube wells in the study area using geochemical methods. The knowledge of changes in hydrochemistry of the aquifers is important for both groundwater recharge and use in the region. This study found that there are substantial differences of water chemistry between shallow and deep wells. In the shallow wells, the average concentrations of total dissolved solid (TDS), Na, K, Ca, Mg, HCO₃, Cl, SO₄, NO₃, PO₄, F, Cu, Mn, Fe and Cr are twofold higher than the deep wells. The concentrations of dissolved silica in the groundwater do not vary with the depth, which implies that the variation in the water chemistry is not due to mineral dissolution alone. Major ion ratios and saturation indices suggest that the water chemistry is predominantly controlled by dissolution of carbonate minerals, silicate weathering and ion exchange reactions. Thermodynamic evaluation (ion activity ratios and stability filed diagrams) indicates that the kaolinite and gibbsite controlled the water chemistry in the both shallow and deep wells. In addition, the groundwater chemistry in the shallow wells is affected by the vertical infiltration of contaminated water from surface contamination sources and nitrification process. In the deep wells, absence of NO₃ and low concentrations of Cl, SO₄, PO₄ and F imply the role of regional flow and denitrification in the groundwater. Results concluded that proper management plan is necessary to protect the shallow aquifer in the RSB since shallow aquifer pumping is less expensive than the deeper one.
اظهر المزيد [+] اقل [-]Evaluation of combined noxious effects of siduron and cadmium on the earthworm Eisenia fetida النص الكامل
2017
Uwizeyimana, Herman | Wang, Meie | Chen, Weiping
Environmental contaminants do not often occur as individual chemicals but rather in complex mixtures whose joint effects can create a strong toxicity to surrounding organisms. To determine the combined harmful effects of siduron (herbicide) and cadmium (heavy metal) toward Eisenia fetida earthworms, samples of worm’s coelomocytes were subjected to siduron and cadmium (Cd) at sublethal concentrations (lower than LC₅₀)-siduron 0, 0.8, 2.4, and 7.2 μg cm⁻² Cd 0, 0.4, 0.8, and 1.6 μg cm⁻² in filter paper contact assay, both as individual compounds and combinations. The CI-isobologram model was utilized to reveal the types of toxicological interactions between siduron and cadmium in inducing DNA damage toward earthworms. The results indicated that tail DNA percentage (TDNA %) at individual siduron and cadmium concentrations (with the exception of the lowest concentration of Cd 0.04 μgcm ⁻²) were highly significant compared to those of the control (p < 0.01). Tail moments (TM) at individual Cd concentrations (0.8 and 1.6 μg cm ⁻²) were highly significant compared to those of the control (p < 0.05), while the increase of TM for individual siduron was only significant (p < 0.05) at 7.2 μg cm ⁻² which is the highest dose/concentration of siduron used in this study. The combinations of siduron and Cd indicated a significant synergism (CI < 1) at the lower effect levels and a significant antagonism (CI > 1) at the higher effect levels. The synergistic effect for a particular combination of chemicals suggests that there might be a possible risk connected to the coincidence of these chemicals.
اظهر المزيد [+] اقل [-]Possible effects of melatonin against rat uterus exposure to bisphenol A during neonatal period النص الكامل
2017
Dernek, Damla | Ömeroğlu, Suna | Akçay, NeslihanCoşkun | Kartal, Bahar | Dizakar, SaadetÖzen Akarca | Türkoğlu, İsmail | Aydin, Vildan
The aim of this study was to investigate the possible effects of melatonin on rat uterine tissue against exposure with bisphenol A (BPA) in the neonatal period. Twenty-four female rats were divided into four groups, (n=6) per group. Group I was used as a control (sesame oil + ethanol), group II was injected daily with (100 mg/kg) BPA by subcutaneously (sc) daily postnatal days (PND 0–10), group III was injected daily with (10 mg/kg) melatonin by sc for 10 days (PND 20–30), and group IV was injected daily with (100 mg/kg) BPA (PND 0–10) and (10 mg/kg) melatonin (PND 20–30). All rats were sacrificed in the same day of metestrus cycle, approximately PND 70. Histological analyses, immunostaining of B cell lymphoma 2 (Bcl-2), and cytochrome c and TUNEL assays were performed. According to our results, neonatal exposure to BPA accelerates onset of puberty, causes degenerative and morphometric changes on rat uterus, and increases apoptotic reaction rates. The immunoreactivity of Bcl-2 was decreased after BPA administration. In addition, immunoreactivity of Bcl-2 showed an increase after melatonin treatment. However, cytochrome c immunoreactivity was decreased after melatonin administration. Our results suggest that melatonin may have positive effects against BPA-induced degenerative changes on rat uterus.
اظهر المزيد [+] اقل [-]The effect of vitamin E, L-carnitine, and ginger on production traits, immune response, and antioxidant status in two broiler strains exposed to chronic heat stress النص الكامل
2017
Zia-ur-Rehman, | Chand, Naila | Khan, RifatUllah
The present study was designed to find the effect of natural and synthetic antioxidants on the performance of two broiler strains under high ambient temperature. A total of 320 day-old chicks of Hubbard and Cobb were reared for a period for 21 days under the same nutritional and management systems. On day 21 onward, one subgroup was kept as control while other subgroups were provided with vitamin E (250 mg/kg), ginger (2 g/kg), and L-carnitine (500 mg/kg) in basal diets. Body weight and feed conversion ratio (FCR) were significantly (P < 0.05) high in vitamin E-supplemented birds, while feed intake was significantly (P < 0.05) higher in L-carnitine supplemented birds irrespective of the strain. Antibody titer against infectious bursal disease (IBD) and paraoxonase (PON1) was significantly (P < 0.05) higher in vitamin E-supplemented birds compared to the other treatments. The number of heterophils and toal oxidant status (TOS) were significantly (P < 0.05) lower in vitamin E-supplemented birds. Blood glucose was significantly (P < 0.05) lower in vitamin E-supplemented birds, while total protein was significantly (P < 0.05) higher in vitamin E-supplemented group. In conclusion, the supplementation of vitamin E at the rate of 250 mg/kg improved the antioxidant status and immune response in the two broiler strains. Further, the two strains perform similarly in terms of performance and other health status parameters with no significant difference.
اظهر المزيد [+] اقل [-]Dissipation and phytoremediation of polycyclic aromatic hydrocarbons in freshly spiked and long-term field-contaminated soils النص الكامل
2017
Wei, Ran | Ni, Jinzhi | Li, Xiaoyan | Chen, Weifeng | Yang Yusheng,
Pot experiments were used to compare the dissipation and phytoremediation effect of alfalfa (Medicago sativa L.) for polycyclic aromatic hydrocarbons (PAHs) in a freshly spiked soil and two field-contaminated soils with different soil organic carbon (SOC) contents (Anthrosols, 1.41% SOC; Phaeozems, 8.51% SOC). In spiked soils, the dissipation rates of phenanthrene and pyrene were greater than 99.5 and 94.3%, respectively, in planted treatments and 95.0 and 84.5%, respectively, in unplanted treatments. In field-contaminated Anthrosols, there were limited but significant reductions of 10.2 and 15.4% of total PAHs in unplanted and planted treatments, respectively. In field-contaminated Phaeozems, there were no significant reductions of total PAHs in either unplanted or planted treatments. A phytoremediation effect was observed for the spiked soils and the Anthrosols, but not for the Phaeozems. The results indicated that laboratory tests with spiked soils cannot reflect the real state of field-contaminated soils. Phytoremediation efficiency of PAHs in field-contaminated soils was mainly determined by the content of SOC. Phytoremediation alone has no effect on the removal of PAHs in field-contaminated soils with high SOC content.
اظهر المزيد [+] اقل [-]Magnetic cobalt ferrite composite as an efficient catalyst for photocatalytic oxidation of carbamazepine النص الكامل
2017
He, Yongzhen | Dai, Chaomeng | Zhou, Xuefei
A magnetic spinel cobalt ferrite nanoparticle composite (CFO) was prepared via an ultrasonication-assisted co-precipitation method. The morphological structure and surface composition of CFO before and after reaction were investigated by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, and Fourier transform infrared spectroscopy, indicating the consumption of iron oxide during photodegradation. X-ray photoelectron spectroscopy and vibrating sample magnetometry confirm the preparation of the ferrite nanoparticle composite and its magnetic properties. The prepared CFO was then used for the photocatalytic degradation of carbamazepine (CBZ) as an example of pharmaceuticals and personal care products (PPCPs) from aqueous solution. The effects of the nanocomposite dosage, contact time, and solution pH on the photodegradation process were investigated. More than 96% of the CBZ was degraded within 100 min at 0.2 g·L⁻¹ CFO in the presence of UV light. The reactive species for CBZ degradation in the CFO/UV system was identified as hydroxyl radicals by the methanol scavenging method. Combined with the detection of leached iron ions during the process, the CBZ degradation mechanism can be presumed to be heterogeneous and homogeneous photocatalytic degradation in the CFO/UV system. Furthermore, iminostilbene and acridine were detected as intermediate products by GC-MS.
اظهر المزيد [+] اقل [-]Low-dose combined exposure of nanoparticles and heavy metal compared with PM2.5 in human myocardial AC16 cells النص الكامل
2017
Feng, Lin | Yang, Xiaozhe | Asweto, Collins Otieno | Wu, Jing | Zhang, Yannan | Hu, Hejing | Shi, Yanfeng | Duan, Junchao | Sun, Zhiwei
The co-exposure toxicity mechanism of ultrafine particles and pollutants on human cardiovascular system are still unclear. In this study, the combined effects of silica nanoparticles (SiNPs) and/or carbon black nanoparticles (CBNPs) with Pb(AC)₂ compared with particulate matter (PM)₂.₅ were investigated in human myocardial cells (AC16). Our study detected three different combinations of SiNPs and Pb(AC)₂, CBNPs and Pb(AC)₂, and SiNPs and CBNPs compared with PM₂.₅ at low-dose exposure. Using PM₂.₅ as positive control, our results suggested that the combination of SiNPs and Pb(AC)₂/CBNPs could increase the production of reactive oxygen species (ROS), lactate dehydrogenase leakage (LDH), and malondialdehyde (MDA) and decrease the activities of superoxide dismutase (SOD) and glutathione (GSH); induce inflammation by the upregulation of protein CRP and TNF-α, and apoptosis by the upregulation of protein caspase-3, caspase-9, and Bax while the downregulation of protein Bcl-2; and trigger G2/M phase arrest by the upregulation of protein Chk2 and downregulation of protein Cdc2 and cyclin B1. In addition, the combination of CBNPs and Pb(AC)₂ induced a significant increase in MDA and reduced the activities of ROS, LDH, SOD, and GSH, with G1/S phase arrest via upregulation of Chk1 and downregulation of CDK6 and cyclin D1. Our data suggested that the additive interaction and synergistic interaction are the major interaction in co-exposure system, and PM₂.₅ could trigger more severe oxidative stress, G2/M arrest, and apoptosis than either co-exposure or single exposure.
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