Oxidative stress and genotoxicity in Rhinella arenarum (Anura: Bufonidae) tadpoles after acute exposure to Ni-Al nanoceramics

The employ of nanomaterials (NMs) has exponentially grown due to the large number of technological advances in industrial, pharmaceutical and medical areas. That is the case of alumina (Al) nanoparticles which are extensively employed as support in heterogeneous catalysis processes. However, these NMs can cause great toxicity because of their ubiquitous properties, such as extremely small size and high specific surface area. So, it is required to assess the potential deleterious effects of these NMs on living organisms. In the present study, we analyze the oxidative stress and genotoxic potential of a nanoceramic catalyst Ni/<gamma>-Al₂O₃ (NC) and the NMs involved in their synthesis, <gamma>-Al₂O₃ support (SPC) and NiO/<gamma>-Al₂O₃ precursor (PC) on Rhinella arenarum larvae. Biomarkers of oxidative stress and genotoxic damage were measured in tadpoles exposed to 5 and 25 mg/L of each NMs for 96 h. The results indicated an inhibition of catalase activity in tadpoles exposed to both concentrations of PC and to 25 mg/L of SPC and NC. Moreover, both exposure concentrations of PC and NC significantly inhibited superoxide dismutase activity. Exposure to the three NMs caused inhibition of glutathione S-transferase activity, but there were no significant variations in reduced glutathione levels. Oxidative stress damage (lipid peroxidation) was observed in tadpoles treated with 25 mg/L PC, while the other treatments did not produce alterations. The MNs frequency significantly increased in larvae exposed to 25 mg/L PC indicating irreversible genotoxic damage. The results show that these NMs exert genotoxic effects and antioxidant defense system disruption in R. arenarum larvae.     

雷藤氯内酯和雷公藤内酯酮对大鼠骨髓细胞染色体与微核的影响

目的 :观察雷藤氯内酯 (T4)和雷公藤内酯酮 (T7)对SD雄性大鼠骨髓细胞染色体与微核的影响 ,了解其抗生育时的安全性。　方法 :雄性SD大鼠 ,随机分为用药组 (T4、T7)和阴性对照组 3组 ,每组 10只。用药组大鼠灌服抗生育剂量T4为 80 μg/ (kg·d)或T7为 317μg/ (kg·d) ,连续用药 10周后采用骨髓细胞染色体和微核制片方法进行分析 ,阴性对照组给等量的载体 (1%羧甲基纤维素钠 )。　结果 :用药组与对照组比较 ,3组之间骨髓细胞染色体畸变平均值差异无显著性 (P >0 .0 5 ) ;骨髓细胞微核出现率差异也无显著性 (P >0 .0 5 )。　结论 :提示抗生育剂量的T4和T7在对SD大鼠遗传学影响方面无明显的诱变作用。     

小鼠多染色性红细胞微核图象自动分析的研究

近１０年多年来，各种生物材料的微核实验（ＭｉｃｒｏｎｕｃｌｅｕｓＴｅｓｔ，ＭＮＴ）已得到广泛应用，而其中小鼠骨髓红细胞的ＭＮＴ应用最为广泛。为了提高一般常规方法的检测速度，减少主观误差，我们用图象分析系统对小鼠多染色性红细胞微核（Ｍｉｃｒｏｎｕｃｌｅｉ，ＭＮ）进行了自动化检测的研究。所编制的软件能将８９％的红细胞从图象中分割出来，其中约８８％含ＭＮ的红细胞能被正确识别。这个初步结果是令人满意的。     

SO2吸入对小鼠骨髓细胞微核的诱发效应

目的 探讨空气中SO2污染物遗传毒理效应。方法 采用SO2吸入染毒法，对SO2吸入诱发小鼠骨髓嗜多染红细胞（PCE）形成微核（MN）的效应进行研究。结果 （1）SO2吸入可引起小鼠骨髓PCE微核率和微核细胞率显著升高；（2）随着吸入的SO2浓度的增高，单微核细胞率、双微核细胞率均显著升高。结论 随SO2浓度增加，细胞遗传物质损伤加重，且有明确的剂量-效应关系，表明SO2空气污染物是染色体断裂剂和基因毒性因子。     

Effect of garlic on micronuclei frequency in peripheral blood lymphocytes of rats with N-methyl-N’nitro-N-nitrosoguanidine-induced gastric carcinoma and precancerous lesions

AIM: To investigate the effects of garlic on micronuclei frequency (MNF) in peripheral blood lymphocytes (PBLs) of Wistar rats with N-methyl-N’nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinoma (GC) and precancerous lesions (PLs).METHODS: Wistar rats were exposed to MNNG at 1.25 mg/5 mL per day for 10 mo to induce GC and PLs (MNNG group, n = 30); rats not exposed to MNNG served as unmodeled controls (control group, n = 16). The MNNG rats were randomly divided into a prevention treatment group (n = 30; receiving 10 mL of a 10% garlic solution per day) and an untreated model control group (n = 20; receiving tap water). MNF in PBLs were detected at experiment months 10 and 16 mo by the microculture technique.RESULTS: The MNNG group had similar MNF levels at months 10 and 16. Compared to the control group, the MNNG, prevention and untreated model control groups had remarkably higher MNF levels (P < 0.01). The level of PLs was significantly lower in the prevention treatment group than in the untreated model control group (P < 0.01). The prevention group showed significantly lower MNF than the MNNG group (P < 0.01), and the MNF level was reduced in month 16 compared to month 10 (P < 0.01). However, the difference in MNF levels in groups given prevention or treatment was not significant.CONCLUSION: MNNG exposure exerted continuous mutagenicity and carcinogenicity properties on PBLs, and garlic exerted a remarkable anti-mutagenic and anti-carcinogenic effect. MNF in PBL may be a novel marker of early-stage GC.     

Assessment of micronuclei and sister chromatid exchange frequency in the petroleum industry workers in province of Vojvodina,Republic of Serbia

Persons who work with petroleum and petroleum derivatives (PPD) are potentially at risk of developing cancer mostly due to the carcinogenity of benzene. Therefore, the aim of this study was to determine in which degree occupational exposure of workers to PPD causes damage to DNA by analysis of micronuclei (MN), sister chromatid exchanges (SCE) and proliferation index (PI). 30 workers of refinery in Novi Sad, participated in the study as exposed and 30 volunteers as control group. Workers exposed to PPD had significantly higher values of MN and SCE in comparison to controls. Exposition time to PPD and type of working place have also significantly effects to DNA damage. The influence of confounding factor such as smoking and age were also evaluated.     

Formaldehyde induces micronuclei in mouse erythropoietic cells and suppresses the expansion of human erythroid progenitor cells

Although formaldehyde (FA) has been classified as a human leukemogen, the mechanisms of leukemogenesis remain elusive. Previously, using colony-forming assays in semi-solid media, we showed that FA exposure in vivo and in vitro was toxic to human hematopoietic stem/progenitor cells. In the present study, we have applied new liquid in vitro erythroid expansion systems to further investigate the toxic effects of FA (0–150 μM) on cultured mouse and human hematopoietic stem/progenitor cells. We determined micronucleus (MN) levels in polychromatic erythrocytes (PCEs) differentiated from mouse bone marrow. We measured cell growth, cell cycle distribution, and chromosomal instability, in erythroid progenitor cells (EPCs) expanded from human peripheral blood mononuclear cells. FA significantly induced MN in mouse PCEs and suppressed human EPC expansion in a dose-dependent manner, compared with untreated controls. In the expanded human EPCs, FA slightly increased the proportion of cells in G2/M at 100 μM and aneuploidy frequency in chromosomes 7 and 8 at 50 μM. Our findings provide further evidence of the toxicity of FA to hematopoietic stem/progenitor cells and support the biological plausibility of FA-induced leukemogenesis.     

Genotoxicity of Aspartame

In the present study, the genotoxic effects of the low‐calorie sweetener aspartame (ASP), which is a dipeptide derivative, was investigated using chromosome aberration (CA) test, sister chromatid exchange (SCE) test, micronucleus test in human lymphocytes and also Ames/Salmonella/ microsome test. ASP induced CAs at all concentrations (500, 1000 and 2000 µg/ml) and treatment periods (24 and 48 h) dose‐dependently, while it did not induce SCEs. On the other hand, ASP decreased the replication index (RI) only at the highest concentration for 48 h treatment period. However, ASP decreased the mitotic index (MI) at all concentrations and treatment periods dose‐dependently. In addition, ASP induced micronuclei at the highest concentrations only. This induction was also dose‐dependent for 48 hours treatment period. ASP was not mutagenic for Salmonella typhimurium TA98 and TA100 strains in the absence and presence of S9 mix.     

The antigenotoxic effects of grapefruit juice on the damage induced by benzo(a)pyrene and evaluation of its interaction with hepatic and intestinal Cytochrome P450 (Cyp)1a1

We determined the capacity of grapefruit juice (GJ) to inhibit the rate of micronucleated polychromatic erythrocytes (MNPE) in mice treated with benzo(a)pyrene (BaP), an environmental contaminant that is biotransformed by Cyp1a1 and is a strong genotoxic agent. For this study, we administered 4.1, 20.8, and 41.6 μl/g body weight (b.w.) of GJ to BaP-treated mice (340 mg/kg). We found a significant decrease in the frequency of MNPE at 48 and 72 h compared to BaP-only treated animals. In turn, no prevention of the cytotoxic damage induced by BaP was found. We next explored whether GJ’s antigenotoxic mechanism of action was related to an inhibitory effect on the activity of the Cyp1a1 enzyme. A reduction in microsomal hepatic and intestinal ethoxyresorufin-O-deethylase (EROD) activity of 20% and 44%, respectively, was found in mice treated with BaP and GJ compared to BaP-only treated animals. Furthermore, when EROD inhibition was tested in vitro, we found a concentration-dependent EROD inhibition by GJ, which reached 85% of the maximum level. Together, these results suggest that the protective effect of GJ against the genotoxicity of BaP may be related to the inhibition of Cyp1a1 enzyme activity.     

Hematoporphyrin derivatives potentiate the radiosensitizing effects of 2-deoxy-D-glucose in cancer cells

PURPOSE: Two deoxy-D-glucose (2-DG), an inhibitor of glucose transport and glycolysis, has been shown to differentially inhibit the repair of radiation damage in cancer cells by reducing the flow of metabolic energy. Since hematoporphyrin derivatives (Hpd) inhibit certain enzymes of the respiratory metabolism, resulting in an increase in the glucose usage and glycolysis, Hpd could possibly enhance the energy-linked radiosensitizing effects of 2-DG in cancer cells. The purpose of the present work was to verify this suggestion. METHODS AND MATERIALS: Two human tumor cell lines (cerebral glioma, BMG-1 and squamous cell carcinoma, 4197) and a murine tumor cell line (Ehrlich ascites tumor [EAT], F-15) in vitro were investigated. A commercially available preparation of Hpd, Photosan-3 (PS-3) was used in the present studies. Cells incubated with 0-10 microg/ml PS-3 for 0-24 h before irradiation were exposed to 2.5 Gy of Co-60 gamma rays and maintained under liquid holding conditions for 1-4 h to facilitate repair. 2-DG (0-5 mM) added at the time of irradiation was present during the liquid holding. Radiation-induced cytogenetic damage (micronuclei formation) and cell death (macrocolony assay) were analyzed as parameters of radiation response. Effects of these radiosensitizers on glucose usage and glycolysis were also studied by measuring the glucose consumption and lactate production using enzymatic assays. RESULTS: The glucose consumption and lactate production of BMG-1 cells (0.83 and 1.43 pmole/cell/h) were twofold higher than in the 4197 cells (0.38 and 0.63 pmole/cell/h). Presence of PS-3 (10 microg/ml) enhanced the rate of glycolysis (glucose consumption and lactate production) in these cells by 35% to 65%, which was reduced by 20% to 40% in the presence of 5 mM 2-DG. In exponentially growing BMG-1 and EAT cells, presence of 2-DG (5 mM; equimolar with glucose) for 4 hours after irradiation increased the radiation-induced micronuclei formation and cell death by nearly 40%, whereas no significant effects could be observed in 4197 cells. In EAT cells, radiation was also observed to induce apoptotic death, which was significantly increased in the presence of the combination (PS-3 + 2-DG). The combination (PS-3 + 2-DG) enhanced the radiation damage in all three cell systems by 60-100%. Furthermore, the radiosensitizing effects of the combination (PS-3 + 2-DG) were higher at pH 6.7 as compared to pH 7. 4. In the plateau phase, presence of 2-DG alone did not significantly influence the radiation response of either BMG-1 or of 4197 cells, whereas in combination with PS-3, 2-DG enhanced the radiation damage in both these cell lines by 40% to 50%. Furthermore, in BMG-1 cells, the effects of 2-DG were observed to be reversible to a very great extent, while that of the combination were mostly irreversible. CONCLUSION: The hematoporphyrin derivative PS-3 enhances the radiosensitizing effects of 2-DG in cancer cells, possibly by further reducing the energy supply leading to an irreversible inhibition of DNA repair, and increased cytogenetic damage and cell death. Since both these compounds have been used in clinical practice, further studies to investigate their use in improving radiotherapy of tumors are warranted.