The Therapeutic Role of Glutathione in Oxidative Stress and Oxidative DNA Damage Caused by Hexavalent Chromium

Vitamin E alleviates pyraclostrobin-induced toxicity in zebrafish (Danio rerio) and its potential mechanisms

Strobilurin fungicides (SFs) are commonly used in agriculture worldwide and frequently detected in aquatic environments. High toxicity of SFs to aquatic organisms has caused great concerns. To explore whether vitamin E (VE) can relieve the toxicity caused by pyraclostrobin (PY), zebrafish were exposed to PY with or without VE supplementation. When co-exposure with VE (20 μM), the 96 h-LC50 values of PY to zebrafish embryos, adult, and the 24 h-LC50 value of PY to larvae increased from 43.94, 58.36 and 38.16 μg/L to 64.72, 108.62 and 72.78 μg/L, respectively, indicating that VE significantly decreased the toxicity of PY to zebrafish at different life stages. In addition, VE alleviated the deformity symptoms (pericardial edema and brain damage), reduced speed and movement distance, and decreased heart rate caused by 40 μg/L PY in zebrafish larvae. Co-exposure of PY with VE significantly reduced PY-caused larval oxidative stress and immunotoxicity via increasing the activities of superoxide dismutase, catalase and level of glutathione, as well as reducing the malondialdehyde production and the expression levels of Nrf2, Ucp2, IL-8, IFN and CXCL-C1C. Meanwhile, the expression levels of gria4a and cacng4b genes, which were inhibited by PY, were significantly up-regulated after co-exposure of PY with VE. Moreover, co-exposure with VE significantly reversed the increased mitochondrial DNA copies and reduced ATP content caused by PY in larvae, but had no effect on the expression of cox4i1l and activity of complex III that reduced by PY, suggesting VE can partially improve PY-induced mitochondrial dysfunction. In conclusion, the potential mechanisms of VE alleviating PY-induced toxicity may be ascribed to decreasing the oxidative stress level, restoring the functions of heart and nervous system, and improving the immunity and mitochondrial function in zebrafish.

Unveiling the inhibitory mechanisms of chromium exposure on microbial reductive dechlorination: Kinetics and microbial responses

Chromium and organochlorine solvents, particularly trichloroethene (TCE), are pervasive co-existing contaminants in subsurface aquifers due to their extensive industrial use and improper disposal practices. In this study, we investigated the microbial dechlorination kinetics under different TCE-Cr(Ⅲ/VI) composite pollution conditions and elucidated microbial response mechanisms based on community shift patterns and metagenomic analysis. Our results revealed that the reductive dechlorinating consortium had high resistance to Cr(III) but extreme sensitivity to Cr(VI) disturbance, resulting in a persistent inhibitory effect on subsequent dechlorination. Interestingly, the vinyl chloride-respiring organohalide-respiring bacteria (OHRB) was notably more susceptible to Cr(III/VI) exposure than the trichloroethene-respiring one, possibly due to inferior competition for growth substrates, such as electron donors. In terms of synergistic non-OHRB populations, Cr(III/VI) exposure had limited impacts on lactate fermentation but significantly interfered with H2-producing acetogenesis, leading to inhibited microbial dechlorination due to electron donor deficiencies. However, this inhibition can be effectively mitigated by the amendment of exogenous H2 supply. Furthermore, being the predominant OHRB, Dehalococcoides have inherent Cr(VI) resistance defects and collaborate with synergistic non-OHRB populations to achieve concurrent bio-detoxication of Cr(VI) and TCE. Our findings expand the understanding of the response patterns of different functional populations towards Cr(III/VI) stress, and provide valuable insights for the development of in situ bioremediation strategies for sites co-contaminated with chloroethene and chromium.

Effects of the SEMA4B gene on hexavalent chromium [Cr(VI)]-induced malignant transformation of human bronchial epithelial cells

Our previous study identified the potential of SEMA4B methylation level as a biomarker for hexavalent chromium [Cr(VI)] exposure. This study aimed to investigate the role of the SEMA4B gene in Cr(VI)-mediated malignant transformation of human bronchial epithelial (BEAS-2B) cells. In our population survey of workers, the geometric mean [95% confidence intervals (CIs)] of Cr in blood was 3.80 (0.42, 26.56) μg/L. Following treatment with various doses of Cr(VI), it was found that 0.5 μM had negligible effects on the cell viability of BEAS-2B cells. The expression of SEMA4B was observed to decrease in BEAS-2B cells after 7 days of treatment with 0.5 μM Cr(VI), and this downregulation continued with increasing passages of Cr(VI) treatment. Chronic exposure to 0.5 μM Cr(VI) enhanced the anchorage-independent growth ability of BEAS-2B cells. Furthermore, the use of a methylation inhibitor suppressed the Cr(VI)-mediated anchorage-independent growth in BEAS-2B cells. Considering that Cr levels exceeding 0.5 μM can be found in human blood due to occupational exposure, the results suggested a potential carcinogenic risk associated with occupational Cr(VI) exposure through the promotion of malignant transformation. The in vitro study further demonstrated that Cr(VI) exposure might inhibit the expression of the SEMA4B gene to promote the malignant transformation of BEAS-2B cells.

Attenuating effects of selenium and zinc against hexavalent chromium-induced oxidative stress, hormonal instability, and placenta damage in preimplanted rats

As a toxic metal, hexavalent chromium (CrVI) has effects on both the reproductive and endocrine systems. This study aimed to evaluate the protective effects of selenium (Se) and zinc (Zn) against the toxicity of chromium on the placenta in pregnant Wistar albino rats. Thirty pregnant Wistar rats were divided into control and four treated groups, receiving subcutaneously (s.c) on the 3rd day of pregnancy, K₂Cr₂O₇ (10 mg/kg body weight (bw)) alone, or in association with Se (0.3 mg/kg bw), ZnCl₂ (20 mg/kg bw), or both of them simultaneously. Plasma steroid hormones, placenta histoarchitecture, oxidative stress profile, and developmental parameters were investigated. These results showed that K₂Cr₂O₇ exposure induced a significant increase in the levels of both plasma estradiol (E₂) and placenta malondialdehyde (MDA), the number of fetal resorptions, and percent of post-implantation loss. On the other hand, K₂Cr₂O₇ significantly reduced developmental parameters, maternal body and placenta weight, and plasma progesterone (P) and chorionic gonadotropin hormone (β HCG) levels. However, K₂Cr₂O₇ significantly decreased the placenta activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), reduced glutathione (GSH), and nonprotein sulfhydryl (NPSH). These changes have been reinforced by histopathological evaluation of the placenta. Se and/or ZnCl₂ supplementation provoked a significant improvement in most indices. These results suggest that the co-treatment with Se or ZnCl₂ strongly opposes the placenta cytotoxicity induced by K₂Cr₂O₇ through its antioxidant action.

Recent advances in soil remediation technology for heavy metal contaminated sites: A critical review

With the increasing development of industry and urbanization, heavy metal contaminated sites have become progressively conspicuous, particularly by unreasonable emissions from electroplating, nonferrous metals smelting, mine tailing, etc. In recent years, soil remediation technologies for heavy metal contaminated sites have developed rapidly. New and effective remediation technologies have emerged successively, and more successful practical applications have appeared. Therefore, systematical summarization of the current progress is essential. As a result, in this paper, some mainstream soil remediation technologies for heavy metal contaminated sites, including physical remediation (soil thermal desorption and soil replacement), bioremediation (phytoremediation and microbial remediation), chemical remediation (chemical leaching, chemical stabilization, electrokinetic remediation-permeable reactive barrier, and chemical oxidation/reduction), as well as various combined remediation are comprehensively reviewed. The influencing factors, advantages, disadvantages, remediation mechanism, and practical applications are also deeply discussed. Besides, the corresponding remediation strategies are put forward for the remediation of heavily polluted sites such as the chemical industry, smelting, and tailing areas. Overall, this review will be beneficial for the in-depth understanding and provide references for the reasonable selection and development of soil remediation technology for heavy metal contaminated sites.

Mechanism of chromium-induced toxicity in lungs, liver, and kidney and their ameliorative agents

Heavy metal Chromium (Cr), can adversely affect humans and their health if accumulated in organs of the body, such as the lungs, liver, and kidneys. Cr (VI) is highly toxic and has a higher solubility in water than Cr (III). One of the most common routes for Cr exposure is through inhalation and is associated with liver, lung, kidney damage, widespread dermatitis, GI tract damage, human lung cancer, cardiomyopathies, and cardiovascular disease. The increase in ROS production has been attributed to most of the damage caused by Cr toxicity. Cr-induced ROS-mediated oxidative stress has been seen to cause a redox imbalance affecting the antioxidant system balance in the body. The Nrf2 pathway dysregulation has been implicated in the same. Deregulation of histone acetylation and methylation has been observed, together with gene methylation in genes such as p16, MGMT, APC, hMLH1, and also miR-143 repression. Several ultra-structural changes have been observed following Cr (VI)-toxicity, including rough ER dilation, alteration in the mitochondrial membrane and nuclear membrane, pycnotic nuclei formation, and cytoplasm vacuolization. A significant change was observed in the metabolism of lipid, glucose, and the metabolism of protein after exposure to Cr. Cr-toxicity also leads to immune system dysregulations with changes seen in the expression of IL-8, IL-4, IgM, lymphocytes, and leukocytes among others. P53, as well as pro-and anti-apoptotic proteins, are involved in apoptosis. These Cr-induced damages can be alleviated via agents that restore antioxidant balance, regulate Nrf-2 levels, or increase anti-apoptotic proteins while decreasing pro-apoptotic proteins.

Hair, serum and urine chromium levels in children with cognitive defects: A systematic review and meta-analysis of case control studies

Environmental chromium exposure may cause impaired development of children. We conducted a systematic review and meta-analysis. Electronic databases including PubMed, Embase, Web of Science and CINAHL were searched to identify case-control studies that reported childhood Cr exposure and cognitive development. The Newcastle-Ottawa Scale (NOS) was used to ensure the quality of the included studies. Cr levels were compared in cases and controls, and a random effect meta-analysis was performed using Stata version 16. Twelve of 61 studies identified in the literature search were eligible for this analysis. Hair, serum and urine Cr measurements were reported by seven, two and one studies, respectively. In addition, one study reported both serum and hair Cr exposure and another reported urine and hair Cr exposure. The pooled standard mean differences (SMD) showed that hair Cr levels were non-significantly lower among children with cognitive defects (-0.01 μg/g, 95% CI: -0.04, 00, p = 0.27). In serum and urine, the pooled SMD was higher in children with cognitive deficits compared with healthy control children (0.32 μg/g, 95% CI: -0.78, 1.42, p = 0.56 and 0.64 μg/g, CI: -0.07,1.36, p = 0.08; respectively). In summary, this systematic review found no significant differences in hair, serum and urine Cr levels between children with cognitive deficits and healthy control children when all study data were pooled in the meta-analysis. Larger studies using standardized criteria and longitudinal assessment of cognitive development are needed to determine whether there is a dose response effect of childhood Cr exposure on cognitive development of children.

Redox sensitive miR-27a/b/Nrf2 signaling in Cr(VI)-induced carcinogenesis

Hexavalent chromium [Cr(VI)] is a well-known carcinogen that can cause several types of cancer including lung cancer. NF-E2-related factor 2 (Nrf2), the redox sensitive transcription factor, can protect normal cells from a variety of toxicants and carcinogens by inducing the expression of cellular protective genes and maintaining redox balance. However, Nrf2 also protects cancer cells from radio- and chemo-therapies and facilitates cancer progression. Although Cr(VI) treatment has been demonstrated to upregulate Nrf2 expression, the mechanisms for Nrf2 regulation upon chronic Cr(VI) exposure remain to be elucidated. We found that Nrf2 was upregulated in BEAS-2B cells exposed to Cr(VI) from 1 to 5 months, and also in Cr(VI)-induced transformed (Cr-T) cells with Cr(VI) treatment for 6 months. We showed that KEAP1, the classic negative regulator of Nrf2, was downregulated after Cr(VI) exposure for 4 months, suggesting that Nrf2 induction by Cr(VI) treatment is through KEAP1 decrease at late stage. To further decipher the mechanisms of Nrf2 upregulation at early stage of Cr(VI) exposure, we demonstrated that miR-27a and miR-27b were redox sensitive miRNAs, since reactive oxygen species (ROS) scavengers induced miR-27a/b expression. After Cr(VI) exposure for 1 month, the expression levels of miR-27a/b was dramatically decreased. The changes of miR-27a/b and their target Nrf2 were confirmed in vivo by mouse model intranasally exposed to Cr(VI) for 12 weeks. Nrf2 was a direct target of miR-27a/b, which acted as tumor suppressors in vitro and in vivo to inhibit tumorigenesis and cancer development of Cr-T cells. The results suggested that the inhibition of miR-27a/b was responsible for Nrf2 upregulation at both early stage and late stage of Cr(VI) exposure. This novel regulation of Nrf2 upon chronic Cr(VI) exposure through redox-regulated miR-27a/b will provide potential targets for preventing and treating Cr(VI)-induced carcinogenesis in the future.

Melatonin Attenuates Chromium (VI)-Induced Spermatogonial Stem Cell/Progenitor Mitophagy by Restoration of METTL3-Mediated RNA N6-Methyladenosine Modification

Spermatogonial stem cells (SSCs) are the basis of spermatogenesis, and any damage to SSCs may result in spermatogenic disorder and male infertility. Chromium (Cr) (VI) is a proven toxin, mutagen, and carcinogen, perpetually detrimental to environmental organisms due to its intricate and enduring detoxification process in vivo. Despite this, the deleterious effects of Cr (VI) on SSCs and the underlying mechanisms remain poorly understood. In this study, we identified that Cr (VI) impaired male reproductive system in mouse testes and induced mitochondrial dynamic imbalance and mitophagy in SSCs/progenitors. Cr (VI) also downregulated the RNA N⁶-methyladenosine (m⁶A) modification levels in mitochondrial dynamic balance and mitophagy genes in SSCs/progenitors. Inspiringly, the toxic effects of Cr (VI) could be relieved by melatonin pretreatment. Melatonin alleviated Cr (VI)-induced damage to male reproductive system and autophagy in mouse testes. Melatonin also attenuated Cr (VI)-induced cell viability loss and reactive oxygen species (ROS) generation, as well as mitochondrial dynamic disorders and mitophagy in SSCs/progenitors. The protective roles of melatonin against Cr (VI)-induced mitophagy were exerted by restoration of METTL3-mediated RNA m⁶A modification and activation of mitochondrial fusion proteins MFN2 and OPA1, as well as inhibition of the mitophagy BNIP3/NIX receptor pathway. Thus, our study provides novel insights into the molecular mechanisms for RNA m⁶A modification underlying the gene regulatory network responsible for mitochondrial dynamic balance, and also lays new experimental groundwork for treatment of Cr (VI)-induced damage to male fertility.

Flexible and reusable carbon dot decorated natural microcline membrane: a futuristic probe for multiple heavy metal induced carcinogen detection

A flexible nano-engineered natural mineral (carbon dot doped natural microcline) based membrane (MCPV) has been developed, which can efficiently detect the presence of hexavalent chromium (Cr⁶⁺) and trivalent iron (Fe³⁺) ions in water by altering its fluorescence emission. Detailed characterization of the membrane was carried out using XRD, FT-IR spectroscopy, FESEM, TEM, and UV-Vis spectroscopy. Mechanical and temperature stabilities were also investigated. This new-generation sensor membrane is designed in such a way that it does not dissolve in water, keeping the water quality unaffected. The fluorescence studies were conducted at 414 nm and "turn-off" response was observed specifically for Fe³⁺ at 489 nm. A prominent red shift (530 nm) of the fluorescence maxima takes place when it comes to Cr⁶⁺. Figures of merit, such as LOD (8.7 μM for Cr⁶⁺ and 18.4 μM for Fe³⁺) and LOQ (29.1 μM for Cr⁶⁺ and 61.6 μM for Fe³⁺), were evaluated from the linear range (0-60 μM for Cr⁶⁺ and 0-30 μM for Fe³⁺) of the calibration curve (Stern-Volmer plots) showing high sensitivity of this sensing probe toward Cr⁶⁺ and Fe³⁺. Recovery and RSD calculations were done in various real-life water samples on intraday-interday basis to determine the accuracy of the sensor. This work validates the fact that the synthesized sensor membrane is capable of detecting these heavy metals in glutathione environment as well, which could be beneficial for early-stage carcinogen detection in living cells.

Treatment of oxidative stress, apoptosis, and DNA injury with N-acetylcysteine at simulative pesticide toxicity in fish

Pesticide toxicities are common in aquatic ecosystems and affects aquatic livings negative. Therefore, it is important to strengthen the antioxidant system in aquatic organisms and to protect the organisms against these toxic chemicals. In this study, the simulative toxicity was established to the fish then the healing process was followed. For this purpose, rainbow trout Oncorhynchus mykiss exposed to cypermethrin and left to the recovery process with either N-acetyl cysteine (an antioxidant, 0.5 mM-1.0 mM concentrations) or no intervention (self-healing) for 96 h. In this context, paraoxonase (PON), arylesterase (AR), myeloperoxidase (MPO), antioxidant enzymes (SOD, CAT, GPx), acetylcholinesterase (AChE) activities as well as MDA, caspase-3 and 8-OHdG levels were measured in fish gills, liver and kidney tissues. In addition, trace element tests were performed in the tissues sampled for each group. At the result of pesticide exposure, SOD, CAT, GPx, PON, AR and AChE activities were increased but MDA, MPO, caspase-3 and 8-OHdG levels were decreased in N-acetyl cysteine (NAC) treated groups in all tissues compared to self-healing group (p < 0.05). When the element analysis of the samples was examined, tissue-based differences were observed significantly in all application groups (p < 0.05). Considering the results of the study, it was found that NAC administration at high concentration (1.0 Mm NAC) was more effective on pesticide toxicity. It was concluded that the most sensitive tissue was the kidney.

In Situ-Grown Cdot-Wrapped Boehmite Nanoparticles for Cr(VI) Sensing in Wastewater and a Theoretical Probe for Chromium-Induced Carcinogen Detection

In modern society, massive industrialization escalates environmental degradation by liberating various contaminants into the environment. Hexavalent chromium is a heavy metal that is being discharged from tannery and other industries, resulting in various carcinogenic diseases. This study reports a carbon dot (cdot)-based fluorometric probe for detecting hexavalent chromium in water. This is the very first time that cdots are tailored over the boehmite nanoparticle's surface using an in situ approach. Validation of formation of the nanocomposite has been discussed in detail employing the Rietveld refinement-based X-ray crystallography method. Vibrational spectroscopy and electron microscopy of the sample authenticate the nucleation process and the growth mechanism. The Stern-Volmer approach and time-resolved fluorescence measurements justify the sensitivity of the sensor (∼58 nM), and selectivity is analyzed by exposing the material to different ionic environments. Density functional theory (DFT) is applied herein to analyze the origin of fluorescence and the sensing mechanism of the probe, which shows that photoinduced electron transfer is responsible for the turn-off-based sensing of Cr(VI). The molecular docking simulation is carried out to ensure the binding of cdots to the binding pocket of the glutathione enzyme, which is responsible for treating reactive oxygen species-mediated DNA damage due to elements such as hexavalent chromium. Time-dependent density functional calculations show that the fluorometric probe is capable of detecting Cr(VI) in living cells making it an early stage chromium-mediated carcinogen detector.

Ethanol leaf extract of Psychotria microphylla rich in quercetin restores heavy metal induced redox imbalance in rats

Psychotria microphylla is a plant found in Africa and many parts of the world where the leaves are locally used in folk medicine for the treatment of toxicity related liver diseases. We investigated the antioxidant potentials of ethanol leaf extract of Psychotria microphylla (ELE-PM) in restoring hepatic redox dysregulations in rats exposed to heavy metals. HPLC was used in quantifying the bioactive compounds in ELE-PM. DPPH (1,1-diphenyl-2 picrylhydrazyl), FRAP (Ferric reducing antioxidant power) and NO (Nitric Oxide) assays were used for in vitro studies. The in vivo studies involved 30 rats randomly divided into 5 groups (n = 6). Group 1 received normal saline (2 mg/kg), group 2, 3, 4 and 5 received a combined solution of Pb(NO3)2 (11.25 mg/kg) and HgCl2 (0.4 mg/kg) respectively. After 7 days of heavy metal exposure, groups 3, 4 and 5 received a daily bolus administration of 200, 400 and 600 mg/kg body weight of EE-PM respectively through oral intubation for 28 days. HPLC quantification revealed a high amount of quercetin (27.43 ± 0.04 mg/100g), lower amounts of gallic acid (7.60 ± 0.06 mg/100g) and rutin (0.38 ± 0.009 mg/100g). Additionally, ELE-PM demonstrated strong inhibitory potentials against free radical scavenging activity generated in vitro. More interestingly, administration of ELE-PM significantly ameliorated hepatic redox dysregulations elicited by the exposure of the rats to heavy metals in a dose dependent pattern. ELE-PM is highly rich in flavonoid compound quercetin and perhaps this may be responsible for the strong antioxidant potentials exhibited in this investigation.

Characteristics of iron status, oxidation response, and DNA methylation profile in response to occupational iron oxide nanoparticles exposure

Although the growing development and application of iron oxide nanoparticles (IONPs) may pose exposure risk and adverse health outcomes, biological changes due to occupational exposure remain unexplored. This cross-sectional study recruited 23 workers at a plant that manufactures IONPs and 23 age- and sex-matched controls without metal-rich occupational hazards exposure. Exposure metrics at worksites were monitored, and iron status, oxidation markers, and methylation profiles of genomic DNA in peripheral blood were measured using corresponding enzyme-linked immunosorbent assays and methylation-specific polymerase chain reaction (PCR), respectively. The mass concentration, number counting, and surface area concentration of airborne particles at the worksite significantly increased during the work process of manufacturing/handling IONPs. Overall, compared to controls, workers exhibited increased 5-hydroxymethylcytosine (5hmC) levels without changes in 5-methylcytosine (5mC), hepcidin methylation, iron, soluble transferrin receptor (sTfR), ferritin, hepcidin, 8-hydroxydeoxyguanosine, and glutathione. A positive correlation was found between 5hmC and IONP exposure year with adjustment for age, sex, and cotinine using partial correlation analyses ( r = 0.521, p < 0.001). After stratification of INOPs exposure and 5hmC levels, the univariate general linear model with adjustment for age, sex, and cotinine found that the estimated mean levels of 5mC and sTfR in subjects with low and high 5hmC levels among controls were 11% and 14.4% ( p ≤ 0.01) and 80.9 nM and 70.3 nM ( p < 0.05), respectively. The estimated mean levels of sTfR in workers and controls with low 5hmC levels were 88.3 nM and 68.7 nM ( p ≤ 0.01). Multivariate linear regression analyses suggested an association between sTfR and 5hmC (standardized β = −0.420, p = 0.014) and female sex (standardized β = 0.672, p < 0.001) for subjects with low 5hmC levels. These findings suggest that increased 5hmC could be differentially employed to monitor an epigenetic signature with steady iron homeostasis for occupational IONP-exposed individuals who are likely to experience early but specific decreased sTfR, especially for females concurrent with the onset of increment in 5hmC at low level.

High-throughput serum metabolomics analysis of gouty arthritis rat treated by total saponins of Rhizoma Dioscoreae Makino by UPLC-Q/TOF-MS

Rhizoma Dioscoreae Makino (RDM) is effective in treating gouty arthritis (GA) and hyperuricacidemia, especially in promoting uric acid excretion and reducing the inflammatory reaction. Bioactive constituents in RDM are mainly steroidal saponins such as dioscin, trillin, protodioscin and protogracillin. However, the mechanism of its anti-GA action is still unclear, owing to the complex pathological and physiological characteristics of GA, and integration of RDM with multiple components, multiple targets and multiple pathways. Herein, a GA rat model was induced with monosodium urate (MSU), and RDM reduced inflammation of rat synovium tissue. Through metabolomics analysis, 35 potential biomarkers with significant changes involved in the pathogenesis of GA induced by MSU were identified, and perturbations were restored after RDM treatment. The most correlated pathways involved in d-galactose, d-mannose, d-glucose, myoinositol, Phosphatidylcholine (PC) (16:0/16:0), LysoPC (15:0), phosphatidic acid (PA) [18:1(9Z)/18:1(11Z)] and glutathione induced by MSU were galactose metabolism, inositol phosphate metabolism, glycerophospholipid metabolism and glutathione metabolism, and the derivations of all those biomarkers could be regulated by RDM treatment. RDM has a therapeutic effect on GA by intervening in changes in endogenous metabolisms and the related metabolic pathways.

Childhood chromium exposure and neuropsychological development in children living in two polluted areas in southern Spain

This study aimed to assess the association between exposure to chromium and neuropsychological development among children. A cross-sectional study was conducted with 393 children aged 6-11 years old randomly selected from State-funded schools in two provinces in Southern Spain (Almeria and Huelva), in 2010 and 2012. Chromium levels in urine and hair samples were analyzed by inductively coupled plasma mass spectrometry with an octopole reaction system. Neuropsychological development was evaluated using the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) and three computerized tests from the Behavioural Assessment and Research System (BARS): Reaction Time Test (RTT), Continuous Performance Test (CPT) and Selective Attention Test (SAT). Multivariable linear regression models adjusted for potential confounders, including heavy metals, were applied to examine the association between chromium levels and neuropsychological outcomes. A 10-fold increase in urine chromium levels was associated with a decrease of 5.99 points on the WISC-IV Full-Scale IQ (95% CI: 11.98 to -0.02). Likewise, a 10-fold increase in urine chromium levels in boys was associated with a decrease of 0.03 points in the percentage of omissions (95% CI: 0.0 to 0.05) in the SAT, with an increase of 68.35 points in latency (95% CI: 6.60 to 130.12) in the RTT, and with an increase in the number of trials with latencies > 1000 ms (β = 37.92; 95% CI: 2.73 to 73.12) in the RTT. An inverse significant association was detected between chromium levels in hair and latency in the SAT in boys (β = -50.53; 95% CI: 86.86 to -14.22) and girls (β = -55.95; 95% CI: 78.93 to -32.97). Excluding trials with latencies >1000 ms in the RTT increased latency scores by 29.36 points in boys (95% CI: 0.17 to 58.57), and 39.91 points in girls (95% CI: 21.25 to 58.59). This study is the first to show the detrimental effects of postnatal chromium exposure on neuropsychological development in school-aged children.

Therapeutic effect of N- acetyl cysteine as an antioxidant on rainbow trout's brain in cypermethrin toxicity

The aim of this study was to investigate the therapeutic effect of N-acetylcystein (NAC) against oxidative stress induced by Cypermethrin pesticide in rainbow trout (Oncorhynchus mykiss). The experiment was designed as 5 groups (A, B, C, D, and E). Group A was organized as control group and had no treatment. The other groups were treated with Cypermethrin for 14 days. At the end of this period, Groups B (1.0 mM NAC) and D (0.5 mM NAC) was performed with NAC for 96 h. Group C was not administered NAC, the recovery process was evaluated with this group. Group E was exposed to cypermethrin during 14 days and sampled. Acetylcholinesterase (AChE), malondialdehyde (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), paraoxonase (PON), arylesterase (AR), myeloperoxidase (MPO) activities, oxidative DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG)), caspase-3 levels, and trace elements contents analyses were performed in all fish brains. According to the results, MDA, MPO, 8-OHdG and caspase-3 levels were significantly decreased compared to the other groups (pesticide and recovery) (p < 0.05), AChE, SOD, CAT, GPx, PON, and AR activities increased (p < 0.05). In brain tissue, no statistically significant difference was observed in trace element analysis of all application groups. According to the obtained data, the positive effect of N-acetylcysteine on protein synthesis, detoxification, and diverse metabolic functions against cypermethrin toxicity has been more effective in 1.0 mM NAC. NAC has important therapeutic effect on pesticide-induced neurotoxicity for fish in terms of all data. It was concluded that NAC has an antioxidant effect against pesticide-induced oxidative stress and the selected biochemical markers are useful for such studies.

Protective Effect of Curcuma Against Chromium Hepatotoxicity in Rats

This study was carried out to investigate the antioxidant effects of curcuma against chromium-induced alterations in hepatic indices and dysfunctions in the antioxidant system. Forty male Wistar rats were randomly divided into four groups and were treated for 30 consecutive days. The control group (0-0) received per os mineral water and normal diet. The second group (0-Cur) received mineral water and an experimental diet containing 2% of curcuma powder, whereas the third group (Cr-0) was orally fed (per os) with 15 mg/kg body weight/day of potassium dichromate and normal diet. The last group (Cr-Cur) received per os 15 mg/kg of potassium dichromate and a diet with 2% of curcuma. The treatment by chromium was found to elicit a perturbation in biochemical parameters producing a significant increase in glycemia, triglycerides, cholesterol, ALP, ALT, AST, and LDH levels. On the contrary, a significant reduction was observed in the oxidative stress-related parameters (GSH, GPx, CAT, and GST). Moreover, we noticed that liver sections of rats intoxicated with chromium showed a disrupted architecture. However, the administration of curcuma revealed an intense reduction in the oxidative stress induced by chromium, ameliorating the levels of the majority of the previous parameters. The data of this study revealed the potent antioxidant effects of curcuma in reducing oxidative stress damage induced by the hexavalent chromium.

Evaluation of water quality and human risk assessment due to heavy metals in groundwater around Muledane area of Vhembe District, Limpopo Province, South Africa

Groundwater is considered as good alternative to potable water because of its low turbidity and perceived low contamination. The study assessed the physio-chemical and heavy metals concentrations in eight randomly selected boreholes water at Muledane village in Limpopo Province of South Africa and the results were compared with South African National standard permissible limit. The impacts of heavy metals on human health was further determined by performing quantitative risk assessment through ingestion and dermal adsorption of heavy metals separately for adults and children in order to estimate the magnitude of heavy metals in the borehole samples. Parameters such as turbidity, nitrate, iron, manganese and chromium in some investigated boreholes did not comply with standard limits sets for domestic water use. Multivariate analyses using principal component analysis and hierarchical cluster analysis revealed natural and anthropogenic activities as sources of heavy metal contamination in the borehole water samples. The calculated non-carcinogenic effects using hazard quotient toxicity potential, cumulative hazard index and chronic daily intake of groundwater through ingestion and dermal adsorption pathways were less than a unity, which showed that consumption of the water could pose little or no significant health risk. However, maximum estimated values for an individual exceeded the risk limit of 10^-6 and 10^-4 with the highest estimated carcinogenic exposure risk (CR_ing) for Cr and Pb in the groundwater. This could pose potential health risk to both adults and children in the investigated area. Therefore, precaution needs to be taken to avoid potential CR_ing of people in Muledane area especially, children using the borehole water.

Redox imbalance correlates with high Nugent score in bacterial vaginosis

AIM

The main goal of this work was to highlight the significance of redox imbalance in the pathophysiology of bacterial vaginosis (BV). We studied the pro-oxidant (malondialdehyde) and antioxidants (glutathione, total antioxidant capacity) in the vaginal fluids of women and compared them on the basis of their Nugent score (NS).

METHODS

Women were clinically screened using Amsel criteria (≥2 were regarded as positive) and were further screened for NS on the basis of microscopic examination. Subjects were classified into one of three groups - healthy controls, intermediate, and BV - on the basis of NS (0-3, 4-6, and 7-10, respectively). High vaginal swabs were collected from the study participants in order to estimate the levels of pro and antioxidants in the vaginal fluids.

RESULTS

Our results indicated that levels of both pro- and antioxidants were elevated in high vaginal swabs of women in the intermediate (NS: 4-6) and BV (NS: 7-10) groups as compared to those of healthy control women. The difference in mean values for total antioxidant capacity and glutathione was found to be statistically significant. Furthermore, in the BV group (NS: ≥7) both antioxidants (glutathione and total antioxidant capacity) and the pro-oxidant, malondialdehyde, were found to be negatively correlated to NS. Interestingly, the correlation between NS and malondialdehyde was statistically significant.

CONCLUSION

Our results suggest a significant correlation between redox imbalance and NS, which signifies changes in vaginal ecology from normal flora (Lactobacillus spp.) towards a more mixed bacterial population representing BV.

Carcinogenicity of chromium and chemoprevention: a brief update

Chromium has two main valence states: hexavalent chromium (Cr[VI]) and trivalent chromium (Cr[III]). Cr(VI), a well-established human carcinogen, can enter cells by way of a sulfate/phosphate anion-transport system, and then be reduced to lower-valence intermediates consisting of pentavalent chromium (Cr[V]), tetravalent chromium (Cr[IV]) or Cr(III) via cellular reductants. These intermediates may directly or indirectly result in DNA damage or DNA–protein cross-links. Although Cr(III) complexes cannot pass easily through cell membranes, they have the ability to accumulate around cells to induce cell-surface morphological alteration and result in cell-membrane lipid injuries via disruption of cellular functions and integrity, and finally to cause DNA damage. In recent years, more research, including in vitro, in vivo, and epidemiological studies, has been conducted to evaluate the genotoxicity/carcinogenicity induced by Cr(VI) and/or Cr(III) compounds. At the same time, various therapeutic agents, especially antioxidants, have been explored through in vitro and in vivo studies for preventing chromium-induced genotoxicity/carcinogenesis. This review aims to provide a brief update on the carcinogenicity of Cr(VI) and Cr(III) and chemoprevention with different antioxidants.

Selenium Administration Alleviates Toxicity of Chromium(VI) in the Chicken Brain

Selenium (Se) can play a protective role against heavy metal toxicity. This experiment aims to evaluate the effect of Se supplementation at different doses on the chicken brains. Oxidative stress was induced in the chicken brains by chromium(VI). A total of 105 Hyland brown male chickens were randomly divided into seven groups, including the control group, poisoned group [6%LD₅₀ K₂Cr₂O₇ body weight (B.W.)], and detoxification groups K₂Cr₂O₇ (6%LD₅₀) + Se (0.31, 0.63, 1.25, 2.50, and 5.00 Na₂SeO₃ mg/kg B.W.) orally in water for 42 days. The chickens were detected by the activities of mitochondrial membrane potential, 2'-benzoyloxycinnamaldehyde, superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), and Ca²⁺-ATPase. Cr(VI) administration caused histopathological damage. In addition, changes in oxidative stress indicators were observed in the chicken's brains. Se supplement increased the levels of GSH, mitochondrial membrane potential (MMP), and Ca²⁺-ATPase and reduced MDA activity in the detoxification groups. However, the high-dose Se supplementation groups of 2.50 and 5.00 mg/kg reduced the activities of GSH, MMP, and Ca²⁺-ATPase; increased the brain-body ratio; and increased SOD activity. In conclusion, Cr(VI) exposure caused oxidative stress. Se exerted a remission effect on toxic responses in the chicken brains. However, a high Se concentration was synergistic to the toxic effect of Cr(VI).