Oxidative Stress-related DNA Damage Research Articles

Size-dependent toxicity of polystyrene microplastics on the gastrointestinal tract: Oxidative stress related-DNA damage and potential carcinogenicity

Microplastics (MPs) and nanoplastics (NPs) have been generally regarded as emerging pollutants and received worldwide attention in recent years. Water and food consumption are the primary pathways for human exposure to MPs/NPs, thus gastrointestinal tracts may be susceptible to their toxicity. Although the recent report has indicated the presence of MPs/NPs in multiple human organs, little is known about their gastric effects. Therefore, this study focused on the adverse effects of polystyrene microplastics (PS-MPs) on gastric epithelium in vivo and in vitro. Surface-enhanced Raman spectroscopy (SERS) revealed the distribution of PS-MPs was associated with their particle sizes, and predominantly concentrated in gastric tissues. Gastric barrier injury and mitochondrial damage were observed in rats after exposure to PS-MPs. Compared with the larger ones, polystyrene nanoplastics (PS-NPs) more significantly reduced the activity of antioxidant enzymes while enhancing the level of MDA, 8-OhdG and γ-H2AX. Meanwhile, PS-MPs caused upregulation of β-catenin/YAP through redox-dependent regulation of nucleoredoxin (NXN) and dishevelled (Dvl). These findings supported the size-dependent effects of PS-MPs on oxidative stress and DNA damage. Moreover, the redox-dependent activation of the β-catenin/YAP cascade suggested a novel toxic mechanism for PS-MPs and implied the potential carcinogenic effects.

Alleviative Effect of Lactoferrin Interventions Against the Hepatotoxicity Induced by Titanium Dioxide Nanoparticles.

The current study was designed to investigate the alleviative effect of lactoferrin interventions against the hepatotoxicity induced by titanium dioxide nanoparticles (TiO2-NPs). Thirty male Wistar rats were divided into six groups with 5 rats in each group. The first and second groups were intragastrically administered normal saline and TiO2-NPs (100 mg/kg body weight) as the negative control (NC) and TiO2-NP groups. The third, fourth, and fifth groups were intragastrically administered lactoferrin at concentrations of 100, 200, and 400 mg/kg body weight in addition to TiO2-NPs (100 mg/kg body weight). The sixth group was intragastrically administered Fuzheng Huayu (FZHY) capsules at a concentration of 4.6 g/kg body weight in addition to TiO2-NPs (100 mg/kg body weight) as the positive control group. After treatment for 4 weeks, the concentrations of lactoferrin were optimized based on the liver index and function results. Subsequently, the alleviative effects of lactoferrin interventions against TiO2-NP-induced hepatotoxicity in rat liver tissues, including the effects on histological damage, oxidative stress-related damage, inflammation, fibrosis, DNA damage, apoptosis, and gene expression, were investigated using histopathological, biochemical, and transcriptomic assays. The results showed that 200 mg/kg lactoferrin interventions for 4 weeks not only ameliorated the liver dysfunction and histopathological damage caused by TiO2-NP exposure but also inhibited the oxidative stress-related damage, inflammation, fibrosis, DNA damage, and apoptosis in the liver tissues of TiO2-NP-exposed rats. The transcriptomic results confirmed that the alleviative effect of lactoferrin interventions against the TiO2-NP exposure-induced hepatotoxicity was related to the activation of the PI3K/AKT signaling pathway.

Synergism of FAK and ROS1 inhibitors in the treatment of CDH1-deficient cancers mediated by FAK-YAP signaling.

CDH1 deficiency is common in diffuse gastric cancer and triple negative breast cancer patients, both of which still lack effective therapeutics. ROS1 inhibition results in synthetic lethality in CDH1-deficient cancers, but often leads to adaptive resistance. Here, we demonstrate that upregulation of the FAK activity accompanies the emergence of resistance to ROS1 inhibitor therapy in gastric and breast CDH1-deficient cancers. FAK inhibition, either by FAK inhibitors or by knocking down its expression, resulted in higher cytotoxicity potency of the ROS1 inhibitor in CDH1-deficient cancer cell lines. Co-treatment of mice with the FAK inhibitor and ROS1 inhibitors also showed synergistic effects against CDH1-deficient cancers. Mechanistically, ROS1 inhibitors induce the FAK-YAP-TRX signaling, decreasing oxidative stress-related DNA damage and consequently reducing their anti-cancer effects. The FAK inhibitor suppresses the aberrant FAK-YAP-TRX signaling, reinforcing ROS1 inhibitor's cytotoxicity towards cancer cells. These findings support the use of FAK and ROS1 inhibitors as a combination therapeutic strategy in CDH1-deficient triple negative breast cancer and diffuse gastric cancer patients.

Epoxiconazole caused oxidative stress related DNA damage and apoptosis in PC12 rat Pheochromocytoma

Epoxiconazole is among the most widely applied pesticides worldwide. The increased use of these products could cause toxic effects on human health which are mainly associated with its residues in food or occupational exposure in agriculture. The brain is the principal target of lipophilic compounds exposure, while the data of brain injury induced by Epoxiconazole remains unclear. The purpose of our investigation was to assess the cytotoxic and genotoxic effects of the epoxiconazole in rat Pheochromocytoma (PC 12). We found that epoxiconazole could reduce the viability and proliferation of PC12 cells, induce the DNA damage, nuclear condensation, cytoskeleton network disruption and enhance the apoptotic cell death. Intracellular biochemical assay proved that EPX induces the loss of mitochondrial membrane potential (ΔΨm) and activates caspase-3. Indeed, EPX instigated ROS generation in neuronal cells, which is accompanied by an increase of lipid peroxidation as confirmed by the high levels of MDA. Interestingly, Pre-treatment of PC12 cells with the ROS scavenger N-acetylcysteine mitigated EPX-provoked DNA fragmentation and enhancement of apoptosis. Our results demonstrate that the genotoxic and cytotoxic outcomes of EPX are mediated through a ROS-dependent pathway in PC12 cells.

Exposure to nivalenol declines mouse oocyte quality via inducing oxidative stress-related apoptosis and DNA damage†.

Mammalian oocyte quality is critical for fertilization and early embryo development. The type B trichothecene nivalenol (NIV) is a mycotoxin produced by Fusarium oxysporum, and it is commonly found with deoxynivalenol in contaminated food or feed. NIV has been shown to affect the immune system and female reproductive system, cause emesis and growth retardation. Here, we investigated the toxicity of NIV on mouse oocyte quality, as well as the protective effects of melatonin on the NIV-exposed oocytes. We found NIV exposure caused meiotic arrest and further induced the failure of polar body extrusion in mouse oocytes. Transcriptome analysis data showed that NIV exposure altered the expression of multiple pathway-related genes in oocytes, indicating its wide toxicity on oocyte maturation. Based on the RNA-seq data, we showed that NIV exposure induced oxidative stress and caused DNA damage in oocytes. Besides, autophagy, and early apoptosis were also found in NIV-exposed oocytes. Treatment with melatonin significantly ameliorated these defects through its effects on ROS level. Thus, our results demonstrated that exposure to NIV affected oocyte quality and melatonin treatment could reduce the defects caused by NIV in mouse oocytes.

O-192 Modulating hypoxia and oxidative stress in human ovarian tissue xenografts using adipose tissue-derived stem cells

Abstract Study question To investigate whether adipose tissue-derived stem cells (ASCs) modulate hypoxia and oxidative stress in human ovarian tissue transplants to reduce early follicle loss. Summary answer ASCs protect the follicle pool by mitigating the hypoxia-related response through HIF1↑ signaling in human xenografts and enhancing revascularization by ensuring faster tissue reperfusion. What is known already ASCs are known for their angiogenic potential and capacity to boost angiogenesis by secreting growth factors and differentiating into vessels in numerous models of wound healing in regenerative medicine. In a 2-step ovarian tissue xenotransplantation involving grafting inside a fibrin scaffold two weeks prior to transplantation, ASCs reduced follicle loss after short- and long-term grafting, as well as abnormal follicle activation, by increasing reoxygenation and revascularization in human xenografts. Study design, size, duration Prospective experimental study. Cryopreserved ovarian cortex from five adult women was transplanted to 30 nude mice, with or without ASCs (ASC group; OT group). Ovarian grafts were retrieved on days 3 (n = 5), 10 (n = 5) and 21 (n = 5). One piece of ovarian tissue per patient was fixed for analysis after thawing to serve as non-grafted controls. Participants/materials, setting, methods The 10 animals grafted for 21 days underwent in vivo microdialysis evaluation to investigate direct reactive oxygen species (ROS) kinetics. Analyses of ovarian grafts at all time points and non-grafted controls included immunolabeling for double CD34 (revascularization by host and graft components), immunofluorescence for HIF1α (hypoxia-related response), Nrf2 (oxidative stress-related response) and 8OHdG (oxidative stress-related DNA damage), and gene expression (RT-qPCR) for VEGF-A (neoangiogenesis), SOD2 (antioxidant activity) and Nrf1 (mitochondrial biogenesis). Main results and the role of chance ROS peaked sooner in the ASC group (day 2, p < 0.0001) than the OT group (day 10, p = 0.01) after grafting, indicating earlier tissue reperfusion. Total vascularization was stable in the ASC group at all time points, but lower in the OT group 3 days after grafting (p = 0.01) due to a drop in both host and graft vascular components. HIF1α expression, detected mainly in follicles, was significantly lower in primordial follicles in the ASC group than the OT group on days 3 (p = 0.008) and 10 (p = 0.01). VEGF gene expression rose significantly (around 40x) in both groups on day 3 and persisted significantly longer in the ASC group (10 days) than the OT group (3 days) (p = 0.04), emphasizing the role of ASCs as enhancers of proangiogenic factors. There was no upturn in the oxidative stress-related response (Nrf2 pathway) nor DNA damage (8OHdG) to follicles in any of the grafted groups over time, while a modest increase in both markers was observed only in the stroma after 21 days. Neither was there any major increase in SOD2 and Nrf1 gene expression, suggesting no significant activation of the Nrf2 pathway for cytoprotection from oxidative stress. Limitations, reasons for caution Although Nrf2 signaling activation was detected in human granulosa cell cultures in increasing ROS concentrations, our findings did not confirm its role in tissue damage modulation after ovarian tissue transplantation. Further studies may evidence the involvement of other pathways that modulate oxidative stress after transplantation. Wider implications of the findings The role of ASCs in protecting the follicle pool appears to be related to a decrease in hypoxia and faster ovarian graft revascularization and reperfusion, sustained by an increase in VEGF for a longer period after grafting. There was no evidence of oxidative stress-related damage, irrespective of the transplantation strategy. Trial registration number

Benomyl induced oxidative stress related DNA damage and apoptosis in H9c2 cardiomyoblast cells

Benomyl, benzimidazole group pesticide, has been prohibited in Europe and USA since 2003 due to its toxic effects and it has been still determined as food and environmental contaminant. In the present study, the toxic effect mechanisms of benomyl were evaluated in rat cardiomyoblast (H9c2) cells. Cytotoxicity was determined by MTT and NRU assay and, oxidative stress potential was evaluated by reactive oxygen species (ROS) production and glutathione levels. DNA damage was assessed by alkaline comet assay. Relative expressions of apoptosis related genes were evaluated; furthermore, NF-κB and JNK protein levels were determined. At 4 μM concentration (at which cell viability was >70%), benomyl increased 2-fold of ROS production level and 2-fold of apoptosis as well as DNA damage. Benomyl down-regulated miR21, TNF-α and Akt1 ≥ 48.75 and ≥ 97.90; respectively. PTEN, JNK and NF-κB expressions were upregulated. The dramatic changes in JNK and NF-κB expression levels were not observed in protein levels. These findings showed the oxidative stress related DNA damage and apoptosis in cardiomyoblast cells exposed to benomyl. However, further mechanistic and in vivo studies are needed to understand the cardiotoxic effects of benomyl and benzimidazol fungucides.

Effect of IMT-03, an Herbal Formulation in Cyclophosphamide-induced Immunosuppression in Mice

Abstract: Immumomodulatory actions of natural ingredients have been recognized from the time of early civilization. Though herbal medicines are equally used to treat deadly diseases, but till date there are lacks of evidences. In the present work, an herbal preparation IMT-03 was used to find out its immunostimulatory efficacy against chemotherapeutics. Although, most of the individual ingredients present in IMT-03 have been reported for their protective roles against chemotherapeutics, but there is no report in combination. Cyclophosphamide (300 mg/kg, intraperitoneally) induces immunosuppression through myelosuppression. Pretreatment with of IMT-03 at oral the dose of 100 mg/kg and 200 mg/kg in Cyclophosphamide induced immunosuppressive mice showed dose dependently and significantly (p<0.001) improvement in total WBC and absolute neutrophil counts. It also protect the general health of animals from chemotherapeutic induced serious adverse events like signs of sickness, lethargy, immobility, reducing food habit, infections in nostrils and pinna etc. Moreover, IMT-03 has the abilities to counter the macrophages surge during the LPS challenge. The test drug also showed safe up to the oral dose of 2 g/kg. In vitro studies revealed IMT-03 has polyphenols and also radical scavenging actions. There are several evidences that polyphenols can able to modulate cytokines and chemokines signaling pathways in immune cells. Therefore, it is assumed that polyphenols present in IMT-03 either modulate the inflammatory signaling pathways or protect from oxidative stress related DNA damage in myeloid tissues.

Cigarette smoke-inactivated SIRT1 promotes autophagy-dependent senescence of alveolar epithelial type 2 cells to induce pulmonary fibrosis

AimsThe senescence of alveolar epithelial type 2 (AT2) cells is implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Cigarette smoke (CS) is a strong risk factor for IPF and it is also a pro-senescent factor. Here we aimed to investigate whether and how CS induces AT2 cells senescence via a SIRT1/autophagy dependent pathway. Our results showed that CS extract (CSE) reduced autophagy and mitophagy and increased mitochondrial reactive oxygen species (mitoROS) in MLE-12 cells, an AT2 cell line. The autophagy inducer rapamycin (RAPA) and the mitochondria-targeted antioxidant mitoquinone (mitoQ) inhibited CSE-related senescence and decreased mitoROS. Next, we found that CSE promoted DNA damage, downregulated the nicotinamide adenine dinucleotide (NAD+)/nicotinamide adenine dinucleotide (NADH) ratio and suppressed SIRT1 activity. Activating SIRT1 with its activator SRT1720 attenuated senescence through an autophagy-dependent pathway. The NAD+ precursor nicotinamide mononucleotide and the poly ADP-ribose polymerase (PARP1) inhibitor olaparib also exerted anti-senescent effects by activating SIRT1. Moreover, the results showed that mitoQ and RAPA, in turn, elevated SIRT1 activity by inhibiting DNA damage. Consistent with these results, SRT1720 and mitoQ mitigated CS-induced AT2 cells senescence and lung fibrosis in vivo. Moreover, autophagy in AT2 cells was rescued by SRT1720. Taken together, our results suggested that CS-induced senescence of AT2 cells was due to decreased autophagy mediated by SIRT1 inactivation, which was attributed to competitive consumption of NAD+ caused by DNA damage-induced PARP1 activation. The reduction in autophagy, in turn, decreased SIRT1 activity by promoting mitochondrial oxidative stress-related DNA damage, thereby establishing a positive feedback loop between SIRT1 and autophagy in CS-induced AT2 cells senescence. Consequently, CS-inactivated SIRT1 promoted autophagy-dependent senescence of AT2 cells to induce pulmonary fibrosis.

Modulating hypoxia and oxidative stress in human xenografts using adipose tissue-derived stem cells

To investigate whether adipose tissue-derived stem cells (ASCs) modulate hypoxia and oxidative stress in human ovarian tissue transplants. Prospective experimental study SETTING: Gynecological research unit in a university hospital PATIENT(S): Cryopreserved ovarian cortex from 5 adult women. Thirty mice were grafted with frozen-thawed human ovarian tissue, with or without ASCs (2-step/ASCs+ovarian tissue [OT] group and OT group). The ovarian grafts were retrieved on days 3 (n = 5), 10 (n = 5), and 21 (n = 5). The 10 animals grafted for 21 days underwent invivo evaluations using microdialysis. One piece of ovarian tissue per patient was fixed for analysis after thawing (non-grafted controls). Direct reactive oxygen species were collected every second day after grafting by means of microdialysis. Analyses of ovarian fragments included immunolabeling for double CD34 (revascularization by host and graft components); immunofluorescence for hypoxia-inducible factor 1α (hypoxia-related response), nuclear factor erythroid 2-related factor 2 (oxidative stress-related response), and 8-hydroxy-deoxyguanosine (oxidative stress-related DNA damage); and gene expression (quantitative reverse transcription polymerase chain reaction) for vascular endothelial growth factor-A (neoangiogenesis), superoxide dismutase 2 (antioxidant activity), and nuclear respiratory factor 1 (mitochondrial biogenesis). Reactive oxygen species peaked earlier in the ASC group (day 2) compared with that in the OT group (day 10) after grafting. Total vascularization was stable in the ASC group at all time points, while it was lower in the OT group 3 days after grafting. Hypoxia-inducible factor 1α expression, also detected in non-grafted controls, was significantly lower in the ASC group than in the OT group on days 3 and 10. The increase in VEGF gene expression lasted significantly longer in the ASC group than in the OT group. There was no significant upturn in the oxidative stress-related response (nuclear factor erythroid 2-related factor 2 pathway) or oocyte DNA damage (8-hydroxy-deoxyguanosine) in any of the grafted groups. Use of ASCs allows faster ovarian graft reperfusion and mitigates the hypoxia-related response through rapid revascularization, sustained by prolonged increase in vascular endothelial growth factor after grafting. No evidence of oxidative stress-related damage was detected irrespective of the transplantation strategy.

Effect of Vitamin D supplementation on symmetric dimethyl arginine, asymmetric dimethyl arginine, homocysteine levels in rats being exposed to gamma radiation

Background: Radiation causes to damage on endothelial cells by increasing oxidative stress. Vitamin D is also a potent anti-oxidant that facilitates balanced mitochondrial activities, preventing oxidative stress-related protein oxidation, lipid peroxidation, and DNA damage.
 Aims and Objective: We aimed to investigate the potential effect of vitamin D supplementation on levels of Hcy (homocysteine), ADMA (Asymmetric Dimethyl Arginine), and SDMA (Symmetrical Dimethyl Arginine) which are admitted as endothelial dysfunction markers in rat models that are exposed to gamma radiation.
 Materials and Methods: Twentyfour female Wistar Albino rats were selected for the study. The mean weight of these rats were between 200 and 250 grams. Rats were fed with standard light (12 hours day light /12 hours dark), enough water (ad-libitum) at temperature (25ºC) for a total of 4 weeks. The rats were divided into 4 different groups and each group consisted of 6 rats. controlgroup (group I) did not receive any supplementation and not expose to gamma radiation), Group II was merely exposed to gamma radiation, Group III was exposed to gamma radiation and received vitamin D supplementation, and Group IV merely received vitamin D supplementation. Groups that are given vitamin D supplementation were fed by oral gavage at the same time and every day for one week. Finally, Group II and Group III were exposed to gammaradiation at the 8th day. After the completion of all processes, Vitamin D, ADMA, SDMA and Hcy levels were measured by HPLC (High-performance liquid chromatography) method.
 Results: When the results of Group II and Group III were compared with each other, we achieved merely statistical significance in vitamin D results (p=0.04) but did not other parameters (p>0.05).
 Conclusion: We observed that vitamin D supplementation did not any effect on SDMA, ADMA, and Hcy that accompany possible endothelial dysfunction after gamma radiation exposure.

Correlation of skin carotenoid levels with embryo development and pregnancy result of in vitro fertilization cycles for couples with unexplained infertility.

Oxidative stress‐related DNA damage is a significant pathology for male subfertility and unexplained infertility (UI). Antioxidant supplement by food or nutrition may benefit sperm function of UI couples. However, the role of antioxidant status on fertilization outcome and embryo development for UI couples is not clear. A total of 63 semen samples from UI couples undergoing in vitro fertilization (IVF) treatment (26 pregnant cycles and 37 nonpregnant cycles) were recruited for this prospective observational study. The reactive oxygen species (ROS) levels of sperm cells are detected by a chemiluminescence assay. Total antioxidant capacity (TAC) of seminal plasma is evaluated according to an antioxidant assay kit. The skin carotenoid status in the male partners of UI couples is measured by resonance Raman spectroscopy to determine the antioxidant potential from dietary supplement. The skin carotenoid status (23,115 ± 6,831 vs. 19,432 ± 5,242 Raman intensity, p = .0329 by Mann–Whitney U test) and day 3 good embryo rates (49.6 ± 27.1% vs. 26.8 ± 23.1%, p = .002 by Mann–Whitney U test) are higher in pregnant cycles compared to those in nonpregnant cycles. The local antioxidant capacity (seminal TAC) is closely correlated with fertilization rates (r = .35, p = .005). In contrast, skin carotenoid status is intimately associated with good embryo rates in IVF cycles (r = .34, p = .007). In conclusion, the skin carotenoid status of male partners of UI couples may benefit embryo development and the subsequent pregnancy outcome of IVF treatment. Further investigation about the effect and mechanism of nutritional supplement on embryo development in IVF cycles for UI couples is deserved.

Vitamin D Deficiency: Effects on Oxidative Stress, Epigenetics, Gene Regulation, and Aging.

Recent advances in vitamin D research indicate that this vitamin, a secosteroid hormone, has beneficial effects on several body systems other than the musculoskeletal system. Both 25 dihydroxy vitamin D [25(OH)2D] and its active hormonal form, 1,25-dihydroxyvitamin D [1,25(OH)2D] are essential for human physiological functions, including damping down inflammation and the excessive intracellular oxidative stresses. Vitamin D is one of the key controllers of systemic inflammation, oxidative stress and mitochondrial respiratory function, and thus, the aging process in humans. In turn, molecular and cellular actions form 1,25(OH)2D slow down oxidative stress, cell and tissue damage, and the aging process. On the other hand, hypovitaminosis D impairs mitochondrial functions, and enhances oxidative stress and systemic inflammation. The interaction of 1,25(OH)2D with its intracellular receptors modulates vitamin D–dependent gene transcription and activation of vitamin D-responsive elements, which triggers multiple second messenger systems. Thus, it is not surprising that hypovitaminosis D increases the incidence and severity of several age-related common diseases, such as metabolic disorders that are linked to oxidative stress. These include obesity, insulin resistance, type 2 diabetes, hypertension, pregnancy complications, memory disorders, osteoporosis, autoimmune diseases, certain cancers, and systemic inflammatory diseases. Vitamin D adequacy leads to less oxidative stress and improves mitochondrial and endocrine functions, reducing the risks of disorders, such as autoimmunity, infections, metabolic derangements, and impairment of DNA repair; all of this aids a healthy, graceful aging process. Vitamin D is also a potent anti-oxidant that facilitates balanced mitochondrial activities, preventing oxidative stress-related protein oxidation, lipid peroxidation, and DNA damage. New understandings of vitamin D-related advances in metabolomics, transcriptomics, epigenetics, in relation to its ability to control oxidative stress in conjunction with micronutrients, vitamins, and antioxidants, following normalization of serum 25(OH)D and tissue 1,25(OH)2D concentrations, likely to promise cost-effective better clinical outcomes in humans.

Oxidative stress and DNA damage in patients with migraine.

BackgroundOxidative stress is implicated in the pathogenesis of migraine, but no published studies have examined both oxidative stress levels and oxidative DNA damage on the same patient group.MethodsIn this study, total oxidant status (TOS); total antioxidant status (TAS); oxidative stress index (OSI); and 8-hydroxy-2′-deoxyguanosine (8-OHdG), which is an indicator of oxidative DNA damage, were measured in the plasma samples of 50 prophylactic unmediated migraineurs (11 with aura and 39 without aura) and 30 matched healthy volunteers.ResultsNo significant differences in TAS, TOS, and OSI values were observed between patients and controls. However, plasma 8-OHdG levels were found to be significantly higher in migraine patients than in the control group (p = 0.001); this increase in plasma 8-OHdG levels was more prominent in cases with migraine without aura than with aura (p = 0.001). Our results suggested an evidence of oxidative stress-related DNA damage in migraine.ConclusionDNA damage reflected by plasma 8-OHdG did not studied in migraine before. Therefore, further research on oxidative stress-related DNA damage and the extent of its clinical manifestations in migraine may provide additional data to our current knowledge.

Textile industrial effluent induces mutagenicity and oxidative DNA damage and exploits oxidative stress biomarkers in rats.

Exposure to complex mixtures like textile effluent poses risks to animal and human health such as mutations, genotoxicity and oxidative damage. Aim of the present study was to quantify metals in industrial effluent and to determine its mutagenic, genotoxic and cytotoxic potential and effects on oxidative stress biomarkers in effluent exposed rats. Metal analysis revealed presence of high amounts of zinc, copper, chromium, iron, arsenic and mercury in industrial effluent. Ames test with/without enzyme activation and MTT assay showed strong association of industrial effluent with mutagenicity and cytotoxicity respectively. In-vitro comet assay revealed evidence of high oxidative DNA damage. When Wistar rats were exposed to industrial effluent in different dilutions for 60 days, then activities of total superoxide dismutase and catalase and hydrogen peroxide concentration were found to be significantly lower in kidney, liver and blood/plasma of effluent exposed rats than control. Vitamin C in a dose of 50 mg/kg/day significantly reduced oxidative effects of effluent in rats. On the basis of this study it is concluded that industrial effluent may cause mutagenicity, in-vitro oxidative stress-related DNA damage and cytotoxicity and may be associated with oxidative stress in rats. Vitamin C may have ameliorating effect when exposed to effluent.

Blockade of metabotropic glutamate receptor 5 protects against DNA damage in a rotenone-induced Parkinson's disease model

Glutamate excitotoxicity contributes to the development of Parkinson's disease (PD) and pharmacological blockade of metabotropic glutamate receptor 5 (mGluR5) has beneficial anti-akinetic effects in animal models of PD; however, the mechanism by which these antagonists alleviate PD symptoms is largely unknown. In our study, the effects of mGluR5 inhibition on DNA damage were investigated in a rotenone-induced model of PD. We first found that the selective mGluR5 antagonist, 2-methyl-6- (phenylethynyl) pyridine, prevented rotenone-induced DNA damage in MN9D dopaminergic neurons through a mechanism involving the downregulation of intracellular calcium release which was associated with a reduction in endoplasmic reticulum stress and reactive oxygen species (ROS)-related mitochondrial dysfunction. Interestingly, the ROS-related mitochondrial dysfunction was accompanied by an increase in expression of the antioxidant protein, Trx2. Treatment of cells with the calcium chelating agent 1,2-bis-(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid or the ROS scavenger N-acetyl-L-cysteine, also reduced rotenone-induced DNA damage, while transfection of a dominant-negative form of Trx2 increased it. In addition, mGluR5 inhibition altered the expression profiles of proteins involved in DNA repair activity. Specifically, the expression of phosphorylated ERK (p-ERK) and CREB, as well as APE1 and Rad51 were elevated after rotenone stimulation and were subsequently downregulated following blockade of mGluR5. These findings were confirmed in vivo in a rotenone-induced rat model of PD. Inhibition of mGluR5 protected against neurotoxicity by mitigating oxidative stress-related DNA damage associated with 8-hydroxy-2′-deoxyguanosine production and also reduced p-ERK activity and Trx2 expression. These findings provide a novel link between mGluR5 and DNA damage in a model of PD, and reveal a potential mechanism by which mGluR5 mediates DNA damage in neurodegenerative diseases.

Oxidative stress-related DNA damage and homologous recombination repairing induced by N,N-dimethylformamide.

The intensified anthropogenic release of N,N-dimethylformamide (DMF) has been proven to have hepatotoxic effects. However, the potential mechanism for DMF-induced toxicity has rarely been investigated. Our research implicated that DMF induced a significantly dose-dependent increase in reactive oxygen species (ROS) in HL-7702 human liver cells. Moreover, oxidative stress-related DNA damage, marked as 8-hydroxy-2'-deoxyguanosine, was increased 1.5-fold at 100 mmol l(-1) . The most severe DNA lesion (double-strand break, DSB), measured as the formation of γH2AX foci, was increased at/above 6.4 mmol l(-1) , and approximately 50% of cells underwent DSB at the peak induction. Subsequently, the DNA repair system triggered by molecules of RAD50 and MRE11A induced the homologous recombination (HR) pathway by upregulation of both gene and protein levels of RAD50, RAD51, XRCC2 and XRCC3 at 16 mmol l(-1) and was attenuated at 40 mmol l(-1) . Consequently, cellular death observed at 40 mmol l(-1) was exaggerated compared with exposure at 16 mmol l(-1) . Although the exact mechanism relying on the DMF-induced hepatotoxicity needs further clarification, oxidative stress and DNA damage involved in DSBs partially explain the reason for DMF-induced liver injury. Oxidative stress-induced DNA damage should be first considered during risk assessment on liver-targeted chemicals. Copyright © 2015 John Wiley & Sons, Ltd.

Dexamethasone and 1,25-dihydroxyvitamin D3 reduce oxidative stress-related DNA damage in differentiating osteoblasts.

The process of osteoblast differentiation is regulated by several factors, including RUNX2. Recent reports suggest an involvement of RUNX2 in DNA damage response (DDR), which is important due to association of differentiation with oxidative stress. In the present work we explore the influence of two RUNX2 modifiers, dexamethasone (DEX) and 1,25-dihydroxyvitamin D3 (1,25-D3), in DDR in differentiating MC3T3-E1 preosteoblasts challenged by oxidative stress. The process of differentiation was associated with reactive oxygen species (ROS) production and tert-butyl hydroperoxide (TBH) reduced the rate of differentiation. The activity of alkaline phosphatase (ALP), a marker of the process of osteoblasts differentiation, increased in a time-dependent manner and TBH further increased this activity. This may indicate that additional oxidative stress, induced by TBH, may accelerate the differentiation process. The cells displayed changes in the sensitivity to TBH in the course of differentiation. DEX increased ALP activity, but 1,25-D3 had no effect on it. These results suggest that DEX might stimulate the process of preosteoblasts differentiation. Finally, we observed a protective effect of DEX and 1,25-D3 against DNA damage induced by TBH, except the day 24 of differentiation, when DEX increased the extent of TBH-induced DNA damage. We conclude that oxidative stress is associated with osteoblasts differentiation and induce DDR, which may be modulated by RUNX2-modifiers, DEX and 1,25-D3.

Islet amyloid with macrophage migration correlates with augmented β-cell deficits in type 2 diabetic patients

Aims: Islet amyloid is a hallmark in type 2 diabetic subjects, but its implication in clinical features and development of islet pathology is still unclear.Methods: From 118 autopsy cases with type 2 diabetes, 26 cases with islet amyloid deposition (DA+) were selected. Twenty diabetic subjects without obvious amyloid deposition (DA−) matched for the age and diabetes duration and 20 non-diabetic subjects (ND) served for comparison. We examined the severity of amyloid deposition and its relationships with population of endocrine cells, expression of cell damage markers or macrophage infiltration. Correlation of clinical profile with islet pathology was also sought on the subset of the investigated patients.Results: β-Cell volume density was nearly 40% less in DA+ and 20% less in DA− when compared to ND. Severity of amyloid deposition correlated with reduced volume densities of β-cell and α-cell, and increased body mass index (BMI), but not with duration of diabetes, age or HbA1c. Amyloid-rich islets contained an increased number of macrophages mixed with β-cells with oxidative stress-related DNA damage, characterized by γH2AX expression, and suppressed (pro)insulin mRNA expression.Conclusions: In Japanese type 2 diabetic patients, islet amyloid was more common with severe β-cell loss and high BMI, associated with macrophage infiltration.

Comparative toxicity of silver nanoparticles on oxidative stress and DNA damage in the nematode, Caenorhabditis elegans

This study examined the effects of polyvinylpyrrolidone (PVP) surface coating and size on the organismal and molecular toxicity of silver nanoparticles (AgNPs) on the nematode, Caenorhabditis elegans. The toxicity of bare AgNPs and 8 and 38nm PVP-coated AgNPs (PVP8-AgNPs, PVP38-AgNPs) were compared. The toxicity of AgNO3 was also tested because ion dissolution and particle-specific effects are often important characteristics determining Ag nanotoxicity. Comparative toxicity across AgNO3 and the three different types of AgNPs was first evaluated using a C. elegans mortality test by a direct comparison of the LC50 values. Subsequently, mutant screening followed by oxidative stress, mitochondrial toxicity and DNA damage assays were carried out at equitoxic (LC10 and LC50) concentrations to further assess the toxicity mechanism of AgNO3 and AgNPs. AgNO3 and bare AgNPs had similar toxicities, whereas PVP coating reduced the toxicity of the AgNPs significantly. Of the PVP-AgNPs, the smaller NPs were more toxic. Different groups of mutants responded differently to AgNO3 and AgNPs, which indicates that their toxicity mechanism might be different. AgNO3 and bare AgNPs induced mitochondrial membrane damage. None of the silver materials tested caused detectable polymerase-inhibiting DNA lesions in either the nucleus or mitochondria as measured by a quantitative PCR assay, but AgNO3, bare AgNPs and PVP8-AgNPs induced oxidative DNA damage. These results show that coatings on the AgNPs surface and the particle size make a clear contribution to the toxicity of the AgNPs, and oxidative stress-related mitochondrial and DNA damage appear to be potential mechanisms of toxicity.