Stopping Exposure Research Articles

Changes in confidence among patients with chronic obstructive pulmonary disease after health education at Quang Ninh provincial general Hospital in 2023

Objectives: To assess changes in confidence among patients with chronic obstructive pulmonary disease (COPD) after health education at Quang Ninh General Hospital 2023. Methods and Paticipants: The outpatients with COPD at Quang Ninh General Hospital meet the inclusion criteria. Results: The status of confidence reached 2.24±0.3 points, 8.97% of the participants felt confident, the rest were not confident. After the health education intervention, the confidence rate increased from 8.97% to 75.21% after 4 weeks and to 85.9% after 12 weeks. Conclusion: It is necessary to conduct health education for patients on effective breathing exercises; Stop exposure to risk factors; Quit smoking and tobacco; Get vaccination against respiratory infections; Pulmonary rehabilitation to improve the confidence of outpatient patients with COPD.

Peningkatan Pengetahuan mengenai Bahaya dan Risiko Gangguan Pernapasan pada Pengemudi Ojek Online

Jakarta is listed as one of the cities in the world with the most polluted air quality, with an annual average PM 2.5 of 49.4 g/m³ in 2019. The sources of air pollution in Jakarta among others are the large number of motor vehicles that are not in accordance with the guidelines of safe vehicles for the environment. Not to mention air pollution from industries and factories fueled by coal or other fossils. Online motorcycle taxi drivers are a profession that is at risk of experiencing the effects of this air pollution. Respiratory disorders that can occur such as acute respiratory infections, chronic obstructive pulmonary disease (COPD), decreased lung function and lung malignancy. To reduce the risk of respiratory problems that can arise in online motorcycle taxi drivers, efforts are being made to prevent and stop exposure to air pollutants through counseling activities which carried out on November 12, 2023. This activity was attended by 42 online motorcycle taxi drivers. Participants' knowledge was assessed by pre-test and post-test using the Google form to assess participants' cognitive changes. From the results of the pre-test and post-test evaluation, it was found that there was an increase in knowledge about the risks and respiratory tract disorders that could arise, namely 25.5%, with an increasing percentage of correct answers of pre-test and post-test ranging from 4.8 % - 40.5%. It is hoped that this increased knowledge will change the behavior of online motorcycle taxi drivers to always pay attention of prevention and stop exposure to air pollutants.

Ferroptosis mediates decabromodiphenyl ether-induced liver damage and inflammation

Decabromodiphenyl ether (BDE-209) is an environmental toxin. Increasing evidence showed that BDE-209 exposure induced liver injury, but the mechanism still remains unknown. The present study explored the effect and mechanism of ferroptosis on hepatotoxicity triggered by BDE-209 in vivo and in vitro. In vivo experiment, ICR mice were exposed to BDE-209 for 50 days, and then recovered for 50 days; HepG2 and L02 cells were treated with BDE-209 or/and ferrostatin-1 (Fer-1) for establishing in vitro model. In vivo, the results showed that BDE-209 accumulated in liver and induced liver damage, increased Fe2+ and MDA contents, and blocked the activation of SLC7A11/GSH/GPX4 pathway in liver; BDE-209 also activated IKK/IκB/NF-κB pathway and elevated inflammatory cytokines levels in liver after exposure for 50 days. After BDE-209 stopping exposure 50 days, the severity of liver damage, ferroptosis and inflammatory response were still higher than the corresponding control group. In vitro, ferroptosis inhibitor Fer-1 rescued ferroptotic damage and attenuated cell death in BDE-209-treated HepG2 and L02 cells. In addition, Fer-1 reversed the activation of IKK/IκB/NF-κB pathway and the increase of pro-inflammatory cytokines levels in BDE-209-treated HepG2 and L02 cells. Together, the above results suggested that BDE-209 induced tissue damage and inflammatory response by activating ferroptosis through increasing iron-dependent lipid peroxidation and blocking the activation of SLC7A11/GSH/GPX4 pathway in liver, indicating that ferroptosis is a potential mechanism for BDE-209-induced hepatotoxicity.

Droplet microfluidic chip-ICP-MS-based single-cell analysis for study of cellular behavior of macrophages to thimerosal.

Thimerosal (THI) is widely used as an antimicrobial preservative, but can hydrolyze to ethylmercury, causing potentially neurotoxicity. In this work, a THP-1 cell line was used to investigate the biological behavior of THI. An on-line droplet microfluidic chip system combined with time-resolved inductively coupled plasma mass spectrometry was used to quantify Hg in single THP-1 cells. The cellular uptake and elimination behaviors of THI were studied, and the toxicity of THI in terms of redox balance was discussed. The results showed that a small number of cells (<5%) exhibited a high uptake content (>200 fg/cell) for THI, and most of the cells (68.8-85.8% for different exposure groups at 25h) exhibited a relatively low uptake content (<20 fg/cell). After stopping exposure to THI, the cells showed an elimination process for Hg, which was rapid in the first several hours and gradually slowed down. When the elimination time was 25h, 7.4-26.3% of the cells in different exposure groups still contained a detectable amount of Hg (>2 fg/cell), indicating Hg could not be eliminated completely, which may cause cumulative toxicity to macrophages. Moreover, it was found that exposure to THI even at 50ng/mL can cause cellular oxidative stress behavior, leading to an increase in reactive oxygen species level and a decrease in glutathione level. This trend would continue for a period of time after stopping THI exposure. With the elimination of Hg, the redox balance of cells showed a tendency to stabilize and restore, but cannot be restored to normal status, indicating a long-term chronic toxicity of THI to THP-1 cells.

Localized surface plasmon resonance sensing of SO2 and H2S using zeolitic imidazolate framework-8

A localized surface plasmon resonance (LSPR) sensor for SO2 and H2S has been developed by coating a Au nanopattern with zeolitic imidazolate framework-8 (ZIF-8), which is one of the most common metal–organic frameworks. SO2 and H2S were detected by the change in the absorbance at a certain wavelength in the LSPR spectrum. The sensitivity to SO2 and H2S was enhanced by ZIF-8 and with increasing relative humidity, and 0.1–20 ppm SO2 and 0.1–10 ppm H2S could be detected within 5 min at 70% relative humidity. The ZIF-8-coated sensor was more sensitive to SO2. The changes in the absorbance increased during exposure to SO2 and H2S, and only slightly decreased for SO2 and remained almost constant for H2S after stopping exposure. These responses indicate that the sensor can measure the integrated concentrations of SO2 and H2S. If the sensor was not exposed to ≥ 20 ppm SO2 or ≥ 10 ppm H2S, the sensitivity and LSPR spectrum of the sensor could be recovered approximately a dozen times by heating it at 200 °C in air. This study demonstrates the potential of metal–organic-framework-coated LSPR sensors for highly sensitive detection of SO2 and H2S.

A case report of Indium lung with progressive emphysema and fibrosis underwent lung unilateral transplantation 20 years after the end of the exposure

BackgroundIndium lung is characterized by interstitial pneumonia and/or emphysema which occurs in indium-tin oxide (ITO) workers. Indium lung is now known to progress after stopping exposure to ITO, but the long-term influences of ITO remain unclear.Case presentationForty seven years old, a never-smoker, who had been engaged in an ITO manufacturing process for 8 years. Emphysema was indicated by the medical check-up for ex-ITO workers, and he was diagnosed with indium lung. He underwent partial lung resections for pneumothorax two times, and obstructive pulmonary dysfunction had progressed through the years. He underwent right single lung transplant 20 years after ITO exposure. Pathologically, his lung showed severe distal acinar emphysema and honeycomb change. Fibrosis and destruction of the lung tissue significantly progressed compared to the previous partial resections. Scanning electron microscopy combined with energy dispersive spectroscopy revealed that the deposited particles contained indium and tin. After the transplantation, his respiratory function was improved.ConclusionsIn this case, ITO resided in the lung tissue for 20 years, and lung tissue destruction kept progressing. Careful medical follow-up is recommended for ITO-workers even if they are asymptomatic.

BDE-209 induced spermatogenesis disorder by inhibiting SETD8/H4K20me1 related histone methylation in mice

Past studies have observed that decabromodiphenyl ether (BDE-209) induces reproductive and developmental toxicity, but the specific mechanism remains unclear. Based on our previous work, male mice were orally given BDE-209 at 75 mg/kg/d via continuous exposure for one spermatozoon development period (50 days) and then stopping exposure for another 50 days. The mouse spermatocyte line GC-2spd was used to examine the toxic effects of BDE-209 on histone methylation and spermatogenesis. The findings indicated that BDE-209 damaged testis and epididymis structure, induced spermatogenic cell apoptosis, and decreased sperm quantity and quality after the 50-day exposure. Furthermore, BDE-209 lowered the levels of SETD8/H4K20me1 and activated the upstream signaling of DNA damage response (Mre11/Rad50/NBS1), thereby causing spermatogenic cell cycle arrest and apoptosis. Downregulation of meiotic promoter Stra8 was associated with a decrease in SETD8 after BDE-209 exposure. After stopping the exposure for 50 days, reproductive system damage and meiosis and cell cycle inhibition due to histone methylation did not improve. In vitro experiments revealed that Setd8 overexpression upregulated the histone methylation and Stra8 expression but did not promote the cell cycle in GC-2 cells. Therefore, BDE-209 exposure impaired spermatogenesis by affecting SETD8/H4K20me1-linked histone methylation and inhibiting meiosis initiation and cell cycle progression, thereby resulting in long-term male reproductive toxicity.

Protocolo diagnóstico y tratamiento de la neumonitis por hipersensibilidad

Hypersensitivity pneumonitis (HP) is an entity produced by the immune response of the pulmonary parenchyma to an inhaled antigen in a previously sensitized individual. Its clinical manifestations vary, although the most common are dyspnea and cough. It is important to take a proper medical history which includes possible exposures to causative agents in detail. The latest guidelines classify it as fibrotic and non-fibrotic HP instead of the previous classification of acute, subacute, and chronic. The diagnosis can be difficult given the clinical and radiological heterogeneity. Among the diagnostic tests are computed tomography, bronchoalveolar lavage, quantification of immunoglobulins, and, in some cases, taking biopsies. In regard to treatment, stopping exposure to the causative antigen, if known, and starting glucocorticoids are the keystones.

Mortality from bladder cancer in dyestuff workers exposed to aromatic amines: A 73-year follow-up.

Objective:To update the analysis of mortality of a cohort of dyestuff workers, in northern Italy, heavily exposed to carcinogenic aromatic amines.Methods:We updated to 2018 overall and cause-specific mortality in a cohort of 590 male workers heavily exposed to carcinogenic aromatic amines in a dyestuff factory from 1922 to 1972. Workers were censored at age 85. Expected cases for the period 1946-2018 were computed using Piedmont mortality rates and standardized mortality ratios (SMR) were computed.Results:Between 1946 and 2018, 470 deaths were reported. The overall SMR from all causes was 1.59 (95% confidence interval [CI] 1.45-1.74) and the SMR from all cancers was 2.05 (95% CI = 1.77-2.37); compared to a previous report, there were 4 additional deaths from bladder cancer, for a total of 60 deaths compared with 4.0 expected (SMR 14.86, 95% CI 11.34-19.12). The SMR for bladder cancer increased with younger age at first exposure and longer duration of exposure, while it decreased with time since last exposure, albeit it was still 3.5, 30, or more years since last exposure. An increased risk was observed among workers exposed to fuchsine or ortho-toluidine (SMR=16.3; 95% CI = 6.0-35.5).Conclusions:This 73-year follow-up confirms the results from previous analyses, with increased overall mortality, and increased mortality from all cancers and especially for bladder cancer. The excess risk of bladder cancer persisted several decades after stopping exposure.

Toxicity Assessment of Nano-ZnO Exposure on the Human Intestinal Microbiome, Metabolic Functions, and Resistome Using an In Vitro Colon Simulator.

Nano-ZnO, as a commonly used nanomaterial, has been found in drinking water, food, and medicine; therefore, it poses potential health risks via the digestion system. However, little is known about the toxicity of nano-ZnO on the human intestinal microbiome, which plays critical roles in human health. This study comprehensively investigated the impact of nano-ZnO on the human gut microbiome, metabolic functions, and resistome using an in vitro colon simulator. Nano-ZnO induced concentration-dependent decreases in the production of short-chain fatty acids (SCFAs). Metagenomic analysis revealed that nano-ZnO not only led to dose-dependent shifts in the composition and diversity of the gut microbiota but also changed the key functional pathways of the gut microbiome. Although the diversity of the gut microbiota basically recovered after stopping exposure to nano-ZnO, SCFAs still showed a concentration-dependent decrease. Furthermore, although a medium concentration of nano-ZnO (2.5 mg/L) reduced the abundance of many antibiotic resistance genes (ARGs) by inhibiting the growth of related host bacteria, a low concentration of nano-ZnO (0.1 mg/L) greatly enriched the abundance of tetracycline resistance genes. Our findings provide evidence that nano-ZnO can impact the diversity, metabolism, and functional pathways of the human gut microbiome, as well as the gut resistome, highlighting the potential health effects of nanoparticles.

Radiation tolerance of the PNI RM3100 magnetometer for a Europa lander mission

Abstract. The results of two radiation test campaigns on a low-cost commercial off-the-shelf magnetometer are presented. The test setup and the total ionization dose (TID) levels studied were designed to meet the requirements of a mission to land on Europa. Based on the Europa Lander Science Definition Team report, instruments inside an aluminum vault at the surface of Europa would need to withstand TID of up to 300 krad(SI). In order to evaluate the performance of the PNI RM3100 magnetometer, nine separate sensors were irradiated at two different facilities during two separate campaigns and under different configurations, including passive and active tests. Of the nine sensors, seven survived the TID of 300 krad(SI) while the other two sensors started presenting failures after reaching 150 krad(SI). Post-irradiation tests showed that eight of the nine sensors continued to work without appreciable degradation after stopping exposure, while one sensor stopped working altogether.

Bias in case-crossover studies of medications due to persistent use: A simulation study.

The case-crossover design is increasingly used to evaluate the effects of chronic medications; however, as traditionally implemented in pharmacoepidemiology, with referent period preceding the outcome, it may lead to bias in the presence of persistent exposures. We aimed to evaluate the extent and magnitude of bias in case-crossover analyses of chronic and persistent exposures, using simulations. We simulated cohorts with either 30-day, 180-day, or 2-year exposure duration; and with varying degrees of persistence (10%, 30%, 50%, 70%, or 90% of patients not stopping exposure). We evaluated all scenarios under the null and the scenario with 30% persistence under varying exposure effects (odds ratios of 0.25 to 4.0). Cohorts were analyzed using conditional logistic regression that compared the odds of exposure on the outcome day to the odds of exposure on a referent day 30 days prior to the outcome. We further implemented the case-time-control design to evaluate its ability to adjust for bias from persistence. Case-crossover analyses produced unbiased estimates across all scenarios without persistent users, regardless of exposure duration. In scenarios where some patients persisted on treatment, case-crossover analyses resulted in upward bias, which increased with increasing proportion of persistent users, but did not vary substantially in relation to the magnitude of the true effect. Case-time-control analyses removed bias in all scenarios. Investigators should be aware of bias due to treatment persistence in unidirectional case-crossover analyses of chronic medications, which can be remedied with a control group of similarly persistent noncases.

Effect of On/Off Aeration Time Ratio Under High Frequency On/Off Aeration on Performance of Nitrosated Granular Sludge

The inhibition of the on/off aeration time ratio on nitrite oxidizing bacteria (NOBs) in intermittent aeration is the key to accumulating nitrite. This study explores the stable operation of nitrosated granular sludge under the same frequency of aeration and different combinations of stop exposure time. At 25-28℃, aerobic granular sludge was inoculated into a sequencing batch reactor (SBR) (R0) and acclimatized to nitrosated granular sludge by intermittent aeration and dissolved oxygen (DO) restriction. The effects of different on/off aeration time ratios in one sub-aeration cycle (3 min:3 min; 4 min:2 min; 2 min:4 min) on the performance of nitrosated granular sludge were analyzed using three same sets of SBRs (R1, R2, and R3). Experiments showed that the nitrite accumulation rates of R1 and R2 were higher, with average nitrite accumulation rates of 89% and 95%, respectively. The nitrosation performance of R3 was poor, and the nitrite accumulation rate at the end of the operation cycle was only 57%. The results showed that when the off-aeration time was between 2 and 4 minutes, the longer the off-aeration time was, the more stable the granular sludge structure was; hence, a good nitrosation performance could be maintained. When the off aeration time was less than 2 minutes, the alternation of anaerobic and aerobic environment could not be fully realized, which resulted in the sludge tending to stay in an environment of continuous aeration. Thus, the environmental advantage of intermittent aeration was lost; the NOBs could not be inhibited, and the granular sludge was disintegrated thereby leading to the deterioration of the nitrosation performance. Additionally, the longer aeration time contributed to the development of irregularly shaped particles. The longer the off-aeration time was, the higher the PN/PS value was, which was beneficial to the enhancement of the hydrophobicity of the particle surface and the sludge settling performance.

P681 Surprise imaging findings in an asymptomatic patient with an ECG suggestive of apical hypertrophic cardiomyopathy

Abstract We present the case of a 55-year old woman with an unremarkable past medical history, allergic to eggs and cinnamon and without any clinical complaints, who presented for a routine ECG prior to a dental implant procedure. The ECG revealed signs of left ventricular (LV) hypertrophy with deep negative T waves in V2-V6 (Figure) suggesting apical hypertrophic cardiomyopathy. Her physical exam was unremarkable and a transthoracic echocardiography (TTE) was ordered. The TTE revealed normal LV dimensions, a normal global systolic function of both ventricles, but most remarkably, an isoechoic mass that occupied the whole apex and one third of the LV cavity (Figure), with a maximum thickness of 22 mm and a 2 mm hyperechogenic lining towards the LV, all these findings being suggestive of Loeffler endocarditis. The routine laboratory tests showed (apart from a slightly increased LDL-cholesterol and normal BNP values) hypereosinophilia: more than 10% of the white blood count. Chest X-Ray and the abdominal scan showed no signs of pulmonary or hepatic infiltration. Cardiac magnetic resonance imaging was scheduled, but the patient has claustrophobia and was unable to perform the exam. The aetiological workup included the investigation of allergic, hematologic, as well as parasitic causes of the hypereosinophilic syndrome. Consequently, serological tests for Coxiella, Chlamydia, Echinococcus and Toxocara were all performed. The IgG antibodies for Toxocara canii were found in a very high level, indicating a chronic parasitic infection as a possible cause of the hypereosinophilic syndrome. The hematologic exams were all within normal limits. The endomyocardial biopsy, the gold standard for diagnosis could not be performed for technical reasons. The first step in the management of hypereosinophilia (HE) is stopping exposure to the trigger, as well as specific treatment- albendazole. The patient received oral anticoagulant treatment in order to prevent thromboembolic complications, which are frequently reported in this clinical setting. Loeffler’s endocarditis is usually a late cardiac manifestation of the HE syndrome. This is a rare and surprising case of an incidental imaging diagnosis in a totally asymptomatic patient after a routine ECG that was suggestive of hypertrophic cardiomyopathy. The challenge consisted in finding the cause of HE in order to attempt an aetiological treatment. Although the allergic and parasitic causes were most likely, considering the patient’s history, a hematologic malignancy had to be excluded. HE associated with toxocariasis rarely causes cardiac manifestations, but it should not be excluded when the patient has a history of canine exposure. The most fearsome complication in this case is the embolization of the eosinophilic mass, but the prompt management and routine follow-up allow the prevention of a thromboembolic event. Abstract P681 Figure. ECG and TTE apical views

Comparison of dose values predicted by FLUKA to measured values using Luxel+ Ta type dosimeters

A 250 MeV electron linear accelerator was used to expose a beam stop to a high radiation field for several minutes. The beam stop was covered with a lattice pattern of Luxel+ Ta type dosimeters which were then sent to Landauer for reading. The deep dose equivalent values reported from Landauer were then compared to dose values predicted by the FLUKA Monte Carlo software. The four radiation weighting coefficient sets available in FLUKA from ICRP 74, for ambient dose, anterior-posterior irradiation, rotational irradiation geometry, and the worst possible geometry for irradiation were calculated and compared to the measured values. The best agreement for total dose were found to be the worst possible geometry for irradiation and anterior-posterior irradiation coefficients, however for separate photon and neutron dose scaling factors were needed for every dose weighting coefficient set.Synopsis: FLUKA Monte Carlo simulations of a 250 MeV electron LINAC beam stop exposure are scored for ICRP74 dose equivalent coefficient sets and are compared to the Landauer Luxel+ deep dose equivalent reports.

Pulmonary toxicity induced by exposure to phthalates, an experimental study

Background: A plasticizer product, di-(2-ethylhexyl) phthalate (DEHP), is widely used in many consumer products, such as food packages, personal care products, children` toys, and medical devices. Phthalates are known to be released into the biological fluids and redistributed into various tissues linked with multiple health problems.Aim: We aimed to study the possible toxic effect of phthalate exposure on the lung tissues.Methods: Thirty male Wister rats were randomly divided into three groups equally, received the following for two weeks once daily via gastric intubation: control group; received normal saline. The DEHP treated group received 2,85mg/kg per BW of DEHP dissolved in normal saline. The DEHP recovery group, received the same as the treated group, followed by two weeks without any treatment. For light microscopic study; the lung tissues were dissected, cut into small pieces, processed, embedded in paraffin wax, sectioned and stained with Hematoxylin and Eosin as well as Masson trichrome stains. For electron microscopic study; the lung tissues were fixed in glutaraldehyde, processed, embedded in epoxy, cut into ultrathin sections, and stained with uranyl acetate and lead citrate.Results: Compared to the control group, the alveolar tissues in the treated group showed a significant increase in collagen deposition and inflammatory cellular infiltration. The number of type-II pneumocytes and alveolar macrophages/field were also significantly increased. However, these pathological changes improved slightly after stopping exposure to DEHP.Conclusion: DEHP has a toxic effect on the lung tissues, which after its withdrawal did not improve completely.

Exposure to Aroclor 1254 persistently suppresses the functions of pancreatic β-cells and deteriorates glucose homeostasis in male mice

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that have been shown to be related to the occurrence of type 2 diabetes mellitus (T2DM). Nevertheless, it is necessary to further explore the development of T2DM caused by PCBs and its underlying mechanisms. In the present study, 21-day-old C57BL/6 male mice were orally treated with Aroclor 1254 (0.5, 5, 50 or 500 μg kg−1) once every three days. After exposure for 66 d, the mice showed impaired glucose tolerance, 13% and 14% increased fasting serum insulin levels (FSIL), and 63% and 69% increases of the pancreatic β-cell mass in the 50 and 500 μg kg−1 groups, respectively. After stopping exposure for 90 d, treated mice returned to normoglycemia and normal FSIL. After re-exposure of these recovered mice to Aroclor 1254 for 30 d, fasting plasma glucose showed 15%, 28% and 16% increase in the 5, 50 and 500 μg kg−1 treatments, FSIL exhibited 35%, 27%, 30% and 32% decrease in the 0.5, 5, 50 or 500 μg kg−1 groups respectively, and there was no change in pancreatic β-cell mass. Transcription of the pancreatic insulin gene (Ins2) was significantly down-regulated in the 50 and 500 μg kg−1 groups, while DNA-methylation levels were simultaneously increased in the Ins2 promoter during the course of exposure, recovery and re-exposure. Reduced insulin levels were initially rescued by a compensative increase in β-cell mass. However, β-cell mass eventually failed to make sufficient levels of insulin, resulting in significant increases in fasting blood glucose, and indicating the development of T2DM.

Effects of levofloxacin exposure on sequencing batch reactor (SBR) behavior and microbial community changes

The adaptation mechanisms of bacterial community for nitrogen removal performance exposed to fluctuated levels of levofloxacin (LVX) during wastewater treatment in SBRs were investigated. Although LVX is completely synthetic, the results of minimum inhibitory concentration (MIC, 32 mg-LVX/L) and minimum bactericidal concentration (MBC, 512 mg-LVX/L) of the sampled sludge showed that the LVX resistance/tolerance for bacterial growth has already existed in the actual wastewater treatment plants (WWTPs). The key bacteria, i.e. Nitrosomonas sp. (ammonia-oxidizing bacteria), Nitrospira sp. (nitrite-oxidizing bacteria) and Thauera sp. (the predominant denitrifiers), decreased with LVX exposure, and the recovery of biological process in the reactor was disturbed due to LVX exposure. However, after stopping exposure their population was quickly increased and thus the performance was recovered. The results of the non-metric multidimensional scaling and microbial community by sequencing showed the LVX concentration was a crucial factor to the change of bacterial communities and controlled the quantitative evolution of the communities in our systems. This effect was more pronounced as the LVX concentration was higher. The results suggested the removal of residual antibiotics to accomplish under no effect concentration before biological treatment is important to suppress emerging and increasing of the antibiotic resistant bacteria in WWTPs.

Effect of different surface functional groups of graphene on oxidative stress in &amp;lt;italic&amp;gt;Daphnia magna&amp;lt;/italic&amp;gt;

Graphene could be modified by functional groups through a series of transformation processes after being released into environment. Meanwhile, the properties of graphene, such as solubility and biotoxicity, could be altered by surface modification. It is important to investigate the aquatic toxicity of graphene and its surface functionalized derivatives for assessing their ecological risks. Oxidative stress is one of the main toxicity mechanisms of graphene nanomaterials, but the effect mechanism of different surface functional groups (amino and thiol) on the oxidative stress induced by graphene is still unclear. In order to illuminate the toxicity mechanism and evaluate the extent of oxidative stress, a series of graphene nanomaterials including unfunctionalized grapheme (u-G), carboxylated grapheme (G-COOH), aminated grapheme (G-NH2), hydroxylated grapheme (G-OH) and sulfydryl grapheme (G-SH) were selected to determine the levels of reactive oxygen species(ROS), antioxidant enzymes, antioxidant and lipid peroxidation in Daphnia magna induced by these graphene nanomaterials. Daphnia magna were exposed to graphene and its surface functionalized derivatives during 24 h period. Following treatment, the parameters reflecting oxidative stress such as ROS, superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde in Daphnia magna were measured. The results showed that malondialdehyde, a marker of lipid peroxidation in Daphnia magna , was significantly increased by u-G, G-COOH and G-OH, respectively. The level of malondialdehyde was significantly higher under u-G exposure than that under G-COOH or G-OH exposure. It is indicated that the degree of oxidative damage induced by u-G in Daphnia magna was more serious than that of G-COOH and G-OH. In addition, the three nanomaterials also caused the changes in ROS and glutathione (GSH) levels, and activities of superoxide dismutase (SOD) and catalase (CAT) were decreased by u-G and G-OH. However, G-SH and G-NH2 did not cause oxidative damage within 24 h exposure period. Marked inactivation of antioxidant enzymes in an ROS-independent manner was observed in response to G-SH, suggesting that G-SH may cause a structural change in enzymes, leading to functional inactivity. G-NH2 did not affect the levels of ROS, antioxidant enzymes, antioxidant and lipid peroxidation. At 24 h after stopping exposure, Daphnia magna can alleviate the oxidative damage induced by u-G, G-COOH and G-OH to a certain extent by its own regulation. The ability of graphene nanomaterials to cause oxidative stress in Daphnia magna is as follows: u-G>G-COOH≈G-OH>G-SH>G-NH2. The main reasons of oxidative stress in Daphnia Magna induced by u-G, G-COOH and G-OH were the generation of ROS, which led to the imbalance of antioxidant defense system and lipid peroxidation. G-SH mainly inhibited the activities of SOD and CAT antioxidant enzymes and affected the antioxidant defense system. However, there were no significant changes in ROS levels and antioxidant enzymes in Daphnia magna under G-NH2 exposure.

Exposure to tetracycline perturbs the microbiome of soil oligochaete Enchytraeus crypticus

Microbial symbiosis is essential for the normal development and growth of hosts. Past attention has mostly been paid to its effects on plants and vertebrates. The effects of environmental pressures such as antibiotics on the microbiome of soil fauna remain largely elusive. We used bacterial 16S rRNA gene high-throughput sequencing to examine the response of microbiome of soil invertebrate Enchytraeus crypticus to oral tetracycline exposure. After two-week exposure, tetracycline-free oat was used as food to monitor the restoration of E. crypticus microbiome. The results showed that Proteobacteria, Actinobacteria and Planctomycetes were the three dominant phyla in all samples, Rhizobiaceae and Kaistia were the most abundant family and genus in all samples, respectively. After 14 days tetracycline exposure, Planctomycetes declined dramatically from 33.05% to 3.28% (P = 0.016), but Actinobacteria elevated substantially from 2.47% to 23.65% (P = 0.004). The alpha-diversity of microbial community increased significantly after tetracycline exposure compared to the control (P = 0.014). Terminating tetracycline exposure led to the recovery of E. crypticus microbiome back to the background level within 14 days. Our results suggest that while tetracycline can disturb the microbiome in E. crypticus significantly, the effects of the antibiotic on E. crypticus microbiome may not be permanent but reversibly diminish after stopping exposure for a period of time. The results may contribute to extending our understanding of the effect of antibiotics on microbiome of soil invertebrates. CapsuleThe microbiome of E. crypticus exposed to tetracycline is perturbed and reversibly restored after terminating the exposure.