Estudio comparativo de biomonitoreo citogenético en personal veterinario expuesto ocupacionalmente a radiaciones ionizantes mediante el ensayo de micronúcleos con bloqueo de la citocinesis

Introducción: las radiaciones ionizantes (RI) pueden inducir la formación de micronúcleos (MN). La frecuencia de MN se utiliza como biomarcador de daño genético inducido por (RI). Objetivo: evaluar el daño al ADN resultante de la exposición ocupacional a RI en personal de clínicas veterinarias o afines. Metodología: se utilizó el ensayo de micronúcleos con bloqueo de la citocinesis (MNBC) para comparar la frecuencia observada del biomarcador en 40 individuos expuestos ocupacionalmente a RI con respecto a un grupo control de 32 participantes, ambos grupos pertenecen a personal veterinario. Además, se registraron variables demográficas, de estilo de vida y ocupacionales que pudieran influir en la formación de MN. Resultados: el análisis univariado no registró diferencias significativas en la frecuencia de MN entre los grupos de estudio (p=0,118). Mediante análisis multivariado se obtuvo que aproximadamente un 27% (R2 ajustado= 0,269) de la variabilidad de la frecuencia de MN puede explicarse por la influencia conjunta de la edad, el sexo y el número de radiografías realizadas por el individuo. La edad es la variable de mayor importancia relativa (β = 0,504), seguida del sexo del participante (β = -0,316) y el número de radiografías realizadas por día (β = 0,214). Conclusiones: La frecuencia de MN tiende a aumentar en mujeres, a medida que aumenta la edad del participante y a mayor número de radiografías realizadas.

Introduction: Ionizing radiation (RI) can induce the formation of micronuclei (MN). The formation of MN is used as a biomarker of radiation-induced genetic damage. Objective: assess DNA damage resulting from occupational exposure to RI in veterinary personnel. Methodology: the cytokinesis-block micronucleus assay (MNBC) was used to compare the observed frequency of MN in 40 individuals occupationally exposed to ionizing radiation with respect to a control group of 32 participants, both groups belonging to veterinary personnel. In addition, demographic, lifestyle and occupational variables that could influence the formation of MN were recorded. Results: univariate analysis did not show significant differences in the frequency of MN between the study groups (p=0.118). Using multivariate analysis, it was found that approximately 27% (adjusted R2= 0.269) of the variability in the frequency of MN can be explained by the joint influence of age, sex and the number of radiographic images performed by the participant. Age is the variable with the greatest relative importance (β = 0.504), followed by the sex of the participant (β = -0.316) and the number of X-rays performed per day (β = 0.214). Conclusions: the frequency of MN tends to increase in women, as the participant's age increases and as the number of radiographic images performed increases.

Genotoxicity evaluation of Wentilactone A / 药学实践杂志

Objective To evaluate the genetic toxicity of Wentilactone A. Methods The classical genotoxicity test combination (Ames test, in vitro CHO cell chromosome aberration test and mouse bone marrow micronucleus test) was used to detect the genotoxicity of Wentilactone A. Results Ames test suggested that Wentilactone A was not mutagenic against Salmonella typhimurium with or without the metabolic activation system (S9) at five doses of 5 000, 500, 50, 5, and 0.5 μg/dish. CHO cell chromosome aberration test suggested that the CHO cells cultured in 4 h and 24 h did not induce chromosomal aberrations in three dose groups at the final concentration of 23.74, 47.48, 94.96 μg/ml, with and without S9. The mouse bone marrow micronucleus test showed no significant difference in the bone marrow micronucleus induction rate of cells at three doses of 100, 200, and 400 mg/kg treated for 24 h and at dose of 400 mg/kg treated for 48 h compared with the solvent control group (P>0.05). Conclusion These results indicated that Wentilactone A did not exhibit genetic toxicity based on the Ames test, CHO chromosomal aberration test and micronucleus assay. It was suggested that Wentilactone A had no genetic toxicity and potential carcinogenicity.

Investigations on remedial role of Rauwolfia serpentina root extract against carbofuran formulation induced genotoxicity in Channa punctatus

Aim: To investigate the remedial potential of Rauwolfia serpentina root extract against genotoxic alterations induced by exposure of carbofuran formulation in freshwater teleost, Channa punctatus. Methodology: Ten days acclimatized fish were categorized in three groups, Group 1 (control), Group 2 (0.09 mg l-1 carbofuran formulation) and group 3 (0.09 mg l-1 carbofuran formulation +10 ppm ethanolic extract of Rauwolfia serpentina). Genotoxic alterations were recorded in terms of single cell gel electrophoresis (SCGE) and micronucleus (MN) assay in blood cells. The variation in comet tail length and micronuclei frequencies were compared among Group 1, 2 and 3 after 24, 48, 72 and 96 hr. Results: A significant (p<0.05) increase was observed in comet tail length and micronuclei induction in carbofuran formulation exposed group. The longest comet length and peak of micronuclei frequencies were observed after 96 hr of carbofuran formulation exposure. However, an appreciable and gradual decline in both frequencies of micronuclei and comet tail length were observed in group 3 (combined Carbofuran formulation and Rauwolfia serpentina root extract) in comparison to group 2 (Carbofuran formulation). Interpretation: The study, thus, demonstrates ameliorative potential of Rauwolfia serpentina root extract against carbofuran formulation induced genotoxicity in fish.

Protective effect of luteolin on DNA damage of peripheral blood lymphocytes of isoproterenol-induced heart failure rats / 西安交通大学学报(医学版)

Objective: To explore the effects of luteolin on DNA damage of peripheral blood lymphocytes of isoproterenol-induced heart failure rats by using comet assay and micronucleus assay. Methods: Male SD rats aged 6-7 weeks were randomly divided into heart failure group (HF, n=10) and control group (Ctrl, n=10). The heart failure model was established through intraperitoneal injection of isoproterenol (50 mg/kg) for 10 consecutive days. Echocardiography was conducted to confirm HF model construction. Blood was taken from the abdominal aorta from rats in both groups using EDTA-anticoagulate tubes. Peripheral blood lymphocytes were separated bylymphocyte isolation kit within two hours after the blood was taken. Comet assay was carried out to test the short-run damage of DNA. Then those lymphocytes were treated with 5, 10, 20, and 50 μmol/L of luteolin and comet assay was carried out again after 30 min to test DNA damage. The lymphocytes were treated with 50 μmol/L of luteolin to culture new peripheral blood for micronucleus assay. Optic microscopy detected long-term DNA damage of the cells. Results: Compared with those in Ctrl group, the mean ejection fraction of left ventricle (EF%) of HF group was decreased; left ventricular fraction shortening, left ventricular end-systolic diameter, and left ventricular end-diastolic diameter significantly increased. These indicated that the heart failure model was established successfully. Compared with Ctrl group, the ratio of Tail DNA in HF group increased (P<0.05). Compared with that in HF group, Tail DNA decreased in 50 μmol/L luteolin-treated HF group (P<0.05). The micronuleus assay results were in accordance with comet assay results. Basically, the number of micronucleus in 1000 cells increased in HF group compared with Ctrl group, but decreased when treated with 50 μmol/L of luteolin. Conclusion: Luteolin can significantly reduce DNA damage on peripheral blood lymphocytes of HF rats.

Buccal Mucosal Dna Damage Following Radiotherapy In Patients With Head And Neck Cancer

Patients with head and neck cancer receiving radiotherapy in addition to antitumour effects also are exposed toionizing radiation which may also damage normal tissue located in the field of radiation. The study was done onbuccal scrapings in patients with head and neck cancer patients receiving radiotherapy at the hospital. Thepresent study aims at determining the changes in MN in the buccal smears in pre and post RT in patients withhead and neck cancer patients. The mean number of MN was significantly high in buccal scrapings of patientspost RT suggesting DNA damage following exposure to radiations during RT.

Reduction of doxorubicin-induced genotoxicity by Handroanthus impetiginosus in mouse bone marrow revealed by micronucleus assay / Redução da genotoxicidade induzida pela doxorrubicina por Handroanthus impetiginosus na medula óssea de camundongos revelada pelo ensaio do micronúcleo

Abstract Handroanthus impetiginosus has long been used in traditional medicine and various studies have determined the presence of bioactive chemical compounds and potential phytotherapeutics. In this study, the genotoxicity of the lyophilized tincture of H. impetiginosus bark (THI) was evaluated in mouse bone marrow using micronucleus assays. The interaction between THI and genotoxic effects induced by the chemotherapeutic agent, doxorubicin (DXR), was also analyzed. Experimental groups were evaluated 24 to 48 h after treatment with N-nitroso-N-ethylurea (NEU; 50 mg/kg), DXR (5 mg/kg), sodium chloride (NaCl; 150 mM), and THI (0.5-2 g/kg). Antigenotoxic assays were carried out using THI (0.5 g/kg) in combination with NEU or DXR. Analysis of the micronucleated polychromatic erythrocytes (MNPCEs) indicated no significant differences between treatment doses of THI (0.5-2 g/kg) and NaCl. Polychromatic erythrocyte (PCE) to normochromatic erythrocyte (NCE) ratios did not indicate any statistical differences between DXR and THI or NaCl, but there were differences between THI and NaCl. A significant reduction in MNPCEs and PCE/NCE ratios was observed when THI was administered in combination with DXR. This study suggested the absence of THI genotoxicity that was dose-, time-, and gender-independent and the presence of moderate systemic toxicity that was dose-independent, but time- and gender-dependent. The combination of THI and DXR also suggested antigenotoxic effects, indicating that THI reduced genotoxic effects induced by chemotherapeutic agents.

Resumo Handroanthus impetiginosus tem sido usada durante um longo período pela medicina tradicional e vários estudos têm demonstrados a presença de compostos químicos e potencial fitoterapêutico. Esta pesquisa avaliou a genotoxicidade da tintura da casca liofilizada de H. impetiginosus (THI) usando o ensaio do micronúcleo em medula óssea de camundongos. A interação entre THI e os efeitos genotóxicos induzidos pelo quimioterápico doxorrubicina (DXR) também foram analisados. Grupos experimentais foram analisados a 24-48 h após o tratamento com N-Nitroso-N-etiluréia (NEU; 50 mg/kg), DXR (5 mg/kg), NaCl (150 mM) e THI (0,5-2 g/kg). O ensaio antigenotóxico foi conduzido utilizando THI (0,5 g/kg) em combinação com NEU ou DXR. A análise de eritrócitos policromáticos micronucleados (EPCMNs) não mostrou diferenças significativas entre as doses de tratamento (0,5-2 g/kg) e NaCl. As proporções de eritrócitos policromáticos (EPC)/eritrócitos normocromáticos (ENC) não revelaram diferenças estatísticas entre DXR e THI ou NaCl, porém houve diferenças entre THI e NaCl. Uma redução significativa em EPCMNs e na razão EPC/ENC foi observada quando THI foi administrado em combinação com DXR. Essa pesquisa sugere ausência de genotoxicidade de THI, dose-, tempo- e sexo-independente, e moderada toxicidade sistêmica dose-independente, mas tempo- e sexo-dependente. A associação do THI e DXR também sugere efeitos antigenotóxicos. Por conseguinte, THI pode reduzir os efeitos genotóxicos induzidos pelo quimioterapêutico.

Cytotoxicity and genotoxicity of stilbene derivatives in CHO-K1 and HepG2 cell lines

Abstract The cytotoxicity and genotoxicity of the stilbenes (E)-methyl-4-(3-5-dimethoxystyryl)benzoate (ester), (E)-4-(3-5-dimethoxystyryl)aniline (amino), (Z)-1,3-dimethoxy-5-(4-methoxystyryl)benzene (cis-TMS) and (E)-1,3-dimethoxy-5-(4-methoxystyryl)benzene (trans-TMS) were investigated in this work. Structural modifications of resveratrol, a naturally occurring stilbene, have been previously performed, including the replacement of hydroxyl by different functional groups. Such modifications resulted in significant improvement of target-specific effects on cell death and antiproliferative responses. The parameters were evaluated using XTT assay, clonogenic survival assay and the cytokinesis-block micronucleus assay in CHO-K1 and HepG2 cell lines. The results showed that cis-TMS is approximately 250-fold more cytotoxic than the amino and ester, and 128-fold more cytotoxic than trans-TMS. When genotoxicity was evaluated, only the trans-TMS did not significantly increase the frequency of micronucleus (MN). While the cis-TMS induced a mean of 5.2 and 5.9 MN/100 cells at 0.5 μM in CHO-K1 and HepG2, respectively, the amino and ester induced 3.1 and 3.6 MN/100 cells at 10 μM in CHO-K1, respectively, and 3.5 and 3.8 in HepG2. Trans-TMS is genotoxic only in HepG2 cells. Based on these results, the cis-TMS was the most cytotoxic and genotoxic compound in both cell lines.

Reduction of doxorubicin-induced genotoxicity by Handroanthus impetiginosus in mouse bone marrow revealed by micronucleus assay

Abstract Handroanthus impetiginosus has long been used in traditional medicine and various studies have determined the presence of bioactive chemical compounds and potential phytotherapeutics. In this study, the genotoxicity of the lyophilized tincture of H. impetiginosus bark (THI) was evaluated in mouse bone marrow using micronucleus assays. The interaction between THI and genotoxic effects induced by the chemotherapeutic agent, doxorubicin (DXR), was also analyzed. Experimental groups were evaluated 24 to 48 h after treatment with N-nitroso-N-ethylurea (NEU; 50 mg/kg), DXR (5 mg/kg), sodium chloride (NaCl; 150 mM), and THI (0.5-2 g/kg). Antigenotoxic assays were carried out using THI (0.5 g/kg) in combination with NEU or DXR. Analysis of the micronucleated polychromatic erythrocytes (MNPCEs) indicated no significant differences between treatment doses of THI (0.5-2 g/kg) and NaCl. Polychromatic erythrocyte (PCE) to normochromatic erythrocyte (NCE) ratios did not indicate any statistical differences between DXR and THI or NaCl, but there were differences between THI and NaCl. A significant reduction in MNPCEs and PCE/NCE ratios was observed when THI was administered in combination with DXR. This study suggested the absence of THI genotoxicity that was dose-, time-, and gender-independent and the presence of moderate systemic toxicity that was dose-independent, but time- and gender-dependent. The combination of THI and DXR also suggested antigenotoxic effects, indicating that THI reduced genotoxic effects induced by chemotherapeutic agents.

Resumo Handroanthus impetiginosus tem sido usada durante um longo período pela medicina tradicional e vários estudos têm demonstrados a presença de compostos químicos e potencial fitoterapêutico. Esta pesquisa avaliou a genotoxicidade da tintura da casca liofilizada de H. impetiginosus (THI) usando o ensaio do micronúcleo em medula óssea de camundongos. A interação entre THI e os efeitos genotóxicos induzidos pelo quimioterápico doxorrubicina (DXR) também foram analisados. Grupos experimentais foram analisados a 24-48 h após o tratamento com N-Nitroso-N-etiluréia (NEU; 50 mg/kg), DXR (5 mg/kg), NaCl (150 mM) e THI (0,5-2 g/kg). O ensaio antigenotóxico foi conduzido utilizando THI (0,5 g/kg) em combinação com NEU ou DXR. A análise de eritrócitos policromáticos micronucleados (EPCMNs) não mostrou diferenças significativas entre as doses de tratamento (0,5-2 g/kg) e NaCl. As proporções de eritrócitos policromáticos (EPC)/eritrócitos normocromáticos (ENC) não revelaram diferenças estatísticas entre DXR e THI ou NaCl, porém houve diferenças entre THI e NaCl. Uma redução significativa em EPCMNs e na razão EPC/ENC foi observada quando THI foi administrado em combinação com DXR. Essa pesquisa sugere ausência de genotoxicidade de THI, dose-, tempo- e sexo-independente, e moderada toxicidade sistêmica dose-independente, mas tempo- e sexo-dependente. A associação do THI e DXR também sugere efeitos antigenotóxicos. Por conseguinte, THI pode reduzir os efeitos genotóxicos induzidos pelo quimioterapêutico.

Genotoxicity in lead treated human lymphocytes evaluated by micronucleus and comet assays.

Lead (Pb) which plays a significant role in modern industry is related to a broad range of physiological, biochemical, behavioural and genetical dysfunctions. Its exposure leads to an increased frequency of genetic aberrations in humans. Hence, this study was designed to assess the genotoxic effect of lead acetate at three dosage levels (10, 25 and 50 µg/mL) by employing: the Cytokinesis Block Micronucleus (CBMN) assay and the Comet assay in Peripheral Blood Lymphocyte Cultures. The results of this study revealed an increased level of DNA damage among treated groups. A significant increase in the tail length of comets and other indices was observed at 25 and 50 µg/mL concentrations comparatively. Thus, lead acetate induced single-strand breaks (SSB) and double strand breaks (DSB) in DNA, alkali-labile sites (ALS), oxidative DNA damage as well as DNA-DNA/DNA-protein/DNA-metal cross linking as evidenced by the Comet assay. The chromosome breakage, DNA misrepair, chromosome loss and telomere end fusion were determined by the Micronucleus assay. Micronucleus frequency in treated lymphocytes was significantly higher as compared to controls. Nucleoplasmic bridges increased significantly and Nuclear buds increased at higher two doses only in exposed cultures. Thus, these assays are better indices for lead induced genotoxicity and metal-nucleus interactions.

Genotoxicity evaluation of triptolide / 药学实践杂志

Objective To study the genotoxicity of triptolide ,an important active component of Tripterygium wilfordii Hook f .Methods Ames test ,in vitro chromosomal aberration test of CHO cell and in vivo micronucleus assay were per-formed to investigate the genotoxicity of triptolide .Results The Ames test showed that triptolide did not increase mutagenicity for TA97 ,TA98 ,TA100 ,TA102 and TA1535 strains at the dosage of 1 .6~1000 μg per plate with and without metabolic ac-tivation system S9 .Results of in vitro CHO cell chromosomal aberration test indicated that there was no statistical difference between the triptolide groups (doses of 0 .01 ,0 .02 and 0 .04 μg/ml) and the solvent control group with and without metabolic activation system S9 .However ,triptolide significantly increased polychromatophilic erythrocyte micronucleus formation at the dosage of 720 μg/kg in ICR mice .Conclusion Triptolide did not induce genetic toxicity based on the Ames test and chromo-somal aberration test ,but could increase micronucleus formation at the dosage of 720 μg/kg .These results indicated that trip-tolide may have potential genotoxicity on human health .

Mutagenicity evaluation of the hydrolysate of Meretrix meretrix Linnaeus soft tissue / 中国实验动物学报

Objective To evaluate the mutagenicity of hydrolysate of Meretrix meretrix Linnaeus soft tissue, so as to provide experimental basis for its exploitation.Methods Three mutagenicity tests were used to evaluate the mutagenic effects, including Ames test, CHL chromosome aberration assay and bone marrow micronucleus assay in mice.Results In Ames test, the revertant colonies numbers in each group were twice less than the numbers of spontaneous revertant colo-nies, five bacterial strains showed negative results with or without S9 activation, and the result of Ames test was negative. The CHL chromosome aberration assay and bone marrow micronucleus assay showed that the chromosome aberration rate and micronucleus rate of each dose group showed no significant difference compared with the negative control group, respec-tively ( P>0.05) .Conclusions Under this condition, the results show that all of the Ames test, chromosome aberration assay and bone marrow micronucleus assay are negative, and no mutagenicity is observed in the hydrolysate of Meretrix mer-etrix Linnaeus soft tissue.

Research progress of the methods and applications of micronucleus assay / 中国比较医学杂志

Micronucleus ( MN) assay as a routine examination for genotoxicity has been widely used.The testing specimens were taken from bone marrow and extended from blood and tissues.In addition to testing genotoxicity of drugs, it is also applied in disease diagnosis for genetic mutation, evaluation of curative effectiveness and disease prevention. Moreover, MN assay is also an important safety indicator for drugs and health foods registration.This review will discuss the staining method of MN test and its application in the field of diseases and virology.

Comparative evaluation of the mutagenicity and genotoxicity of smoke condensate derived from Korean cigarettes

OBJECTIVES: Cigarette smoking is associated with carcinogenesis owing to the mutagenic and genotoxic effects of cigarette smoke. The aim of this study was to evaluate the mutagenic and genotoxic effects of Korean cigarettes using in vitro assays. METHODS: We selected 2 types of cigarettes (TL and TW) as benchmark Korean cigarettes for this study, because they represent the greatest level of nicotine and tar contents among Korean cigarettes. Mutagenic potency was expressed as the number of revertants per μg of cigarette smoke condensate (CSC) total particulate matter whereas genotoxic potency was expressed as a concentration-dependent induction factor. The CSC was prepared by the International Organization for Standardization 3308 smoking method. CHO-K1 cells were used in vitro micronucleus (MNvit) and comet assays. Two strains of Salmonella typhimurium (Salmonella enterica subsp.enterica; TA98 and TA1537) were employed in Ames tests. RESULTS: All CSCs showed mutagenicity in the TA98 and TA1537 strains. In addition, DNA damage and micronuclei formation were observed in the comet and MNvit assays owing to CSC exposure. The CSC from the 3R4F Kentucky reference (3R4F) cigarette produced the most severe mutagenic and genotoxic potencies, followed by the CSC from the TL cigarette, whereas the CSC from the TW cigarette produced the least severe mutagenic and genotoxic potencies. CONCLUSIONS: The results of this study suggest that the mutagenic and genotoxic potencies of the TL and TW cigarettes were weaker than those of the 3R4F cigarette. Further study on standardized concepts of toxic equivalents for cigarettes needs to be conducted for more extensive use of in vitro tests.

Comparative evaluation of the mutagenicity and genotoxicity of smoke condensate derived from Korean cigarettes

OBJECTIVES: Cigarette smoking is associated with carcinogenesis owing to the mutagenic and genotoxic effects of cigarette smoke. The aim of this study was to evaluate the mutagenic and genotoxic effects of Korean cigarettes using in vitro assays. METHODS: We selected 2 types of cigarettes (TL and TW) as benchmark Korean cigarettes for this study, because they represent the greatest level of nicotine and tar contents among Korean cigarettes. Mutagenic potency was expressed as the number of revertants per μg of cigarette smoke condensate (CSC) total particulate matter whereas genotoxic potency was expressed as a concentration-dependent induction factor. The CSC was prepared by the International Organization for Standardization 3308 smoking method. CHO-K1 cells were used in vitro micronucleus (MNvit) and comet assays. Two strains of Salmonella typhimurium (Salmonella enterica subsp.enterica; TA98 and TA1537) were employed in Ames tests. RESULTS: All CSCs showed mutagenicity in the TA98 and TA1537 strains. In addition, DNA damage and micronuclei formation were observed in the comet and MNvit assays owing to CSC exposure. The CSC from the 3R4F Kentucky reference (3R4F) cigarette produced the most severe mutagenic and genotoxic potencies, followed by the CSC from the TL cigarette, whereas the CSC from the TW cigarette produced the least severe mutagenic and genotoxic potencies. CONCLUSIONS: The results of this study suggest that the mutagenic and genotoxic potencies of the TL and TW cigarettes were weaker than those of the 3R4F cigarette. Further study on standardized concepts of toxic equivalents for cigarettes needs to be conducted for more extensive use of in vitro tests.

Assessment of median lethal dose and anti-mutagenic effects of Glycyrrhiza glabra root extract against chemically induced micronucleus formation in Swiss albino mice.

Background: To assess the median lethal dose and evaluate the anti-chemotherapeutic effects of hydro-methanolic root extract of Glycyrrhiza glabra on the cyclophosphamide (CP) induced mutagenicity in bone marrow cells of Swiss albino mice. Methods: For the assessments of LD50, hydro-methanolic root extract of Glycyrrhiza glabra were intra-peritoneally administered at doses of 200, 400, 600, 800, 1000, and 1200 mg/kg body weight. For the mutagenicity study, bone marrow micronucleus test was used and the single i.p. of Glycyrrhiza glabra extract given at the dose of 300, 450, and 600 mg/kg body weight, 24 hrs prior the administration of CP (at the dose of 50 mg/kg body weight). Results: The present investigations revealed that, the median lethal dose/LD50 was observed at the dose of 833.3 mg/kg body weight. The results suggest that, the doses of 450 and 600 mg/kg body weight expressed signifi cant preventive potential against CP induced Micronucleus formation in student ‘t’ test at dose dependent manner in the bone marrow cells of Swiss albino mice. Glycyrrhiza glabra root extract alone has not induced micronucleus formation. Conclusion: Based on this study, it may be concluded that Glycyrrhiza glabra root extract possess anti-mutagenic behavior and this hydro-methanolic crude extract may be safe as per the LD50 was observed.

Genotoxic evaluation of ornidazole and secnidazole in albino mice: an experimental study.

Background: The present study was planned to explore the genotoxic potential of some commonly used antimicrobials like ornidazole and secnidazole in swiss albino mice. Methods: Therapeutic equivalent doses of ornidazole and secnidazole were given by intra peritoneal route. Single dose in individual groups of mice (n=5 in each) was administered for acute study. Doses were repeated every 24 hrs for 7 times in additional groups of mice (n=5 in each) for sub-acute study. Cyclophosphamide served as positive control while normal saline as negative control. After 24 hrs of single dose (acute study) and last dose of drug administration in sub-acute study, about 0.5 ml of blood was collected by retro orbital sinus for comet assay as described earlier (Rojas E et al, 1999) and later the mice were sacrificed to aspirate the femoral bone marrow for micronucleus test as described earlier by described by Schmid W (1975). In comet assay, the total comet length and head diameter was measured under microscope using ocular & stage micrometer to calculate comet tail length. In micronucleus assay, the stained bone marrow tissue smears were scored for the frequency of micronucleated polychromatic erythrocytes (MnPCE) and also the ratio between polychromatic erythrocytes (PCE) to normochromic erythrocytes (NCE) was obtained. Results: It was analyzed by one-way ANOVA followed by Dunnet’s multiple comparison tests. Significant (P< 0.01) increase in comet tail length and percentage of micronucleated polychromatic erythrocytes (% MnPCE) was observed in groups treated with single and multiple doses of Cyclophosphamide whereas ornidazole and secnidazole treated groups did not show any significant changes. Conclusions: The results indicate that Ornidazole and secnidazole are devoid of genotoxicity.

Genotoxicity Assessment of Erythritol by Using Short-term Assay

Erythritol is a sugar alcohol that is widely used as a natural sugar substitute. Thus, the safety of its usage is very important. In the present study, short-term genotoxicity assays were conducted to evaluate the potential genotoxic effects of erythritol. According to the OECD test guidelines, the maximum test dose was 5,000 microg/plate in bacterial reverse mutation tests, 5,000 microg/ml in cell-based assays, and 5,000 mg/kg for in vivo testing. An Ames test did not reveal any positive results. No clastogenicity was observed in a chromosomal aberration test with CHL cells or an in vitro micronucleus test with L5178Y tk +/- cells. Erythritol induced a marginal increase of DNA damage at two high doses by 24 hr of exposure in a comet assay using L5178Y tk +/- cells. Additionally, in vivo micronucleus tests clearly demonstrated that oral administration of erythritol did not induce micronuclei formation of the bone marrow cells of male ICR mice. Taken together, our results indicate that erythritol is not mutagenic to bacterial cells and does not cause chromosomal damage in mammalian cells either in vitro or in vivo.

Appropriate In Vitro Methods for Genotoxicity Testing of Silver Nanoparticles

OBJECTIVES: We investigated the genotoxic effects of 40-59 nm silver nanoparticles (Ag-NPs) by bacterial reverse mutation assay (Ames test), in vitro comet assay and micronucleus (MN) assay. In particular, we directly compared the effect of cytochalasin B (cytoB) and rat liver homogenate (S9 mix) in the formation of MN by Ag-NPs. METHODS: Before testing, we confirmed that Ag-NPs were completely dispersed in the experimental medium by sonication (three times in 1 minute) and filtration (0.2 microm pore size filter), and then we measured their size in a zeta potential analyzer. After that the genotoxicity were measured and especially, S9 mix and with and without cytoB were compared one another in MN assay. RESULTS: Ames test using Salmonella typhimurium TA98, TA100, TA1535 and TA1537 strains revealed that Ag-NPs with or without S9 mix did not display a mutagenic effect. The genotoxicity of Ag-NPs was also evaluated in a mammalian cell system using Chinese hamster ovary cells. The results revealed that Ag-NPs stimulated DNA breakage and MN formation with or without S9 mix in a dose-dependent manner (from 0.01 microg/mL to 10 microg/mL). In particular, MN induction was affected by cytoB. CONCLUSIONS: All of our findings, with the exception of the Ames test results, indicate that Ag-NPs show genotoxic effects in mammalian cell system. In addition, present study suggests the potential error due to use of cytoB in genotoxic test of nanoparticles.

Antihyperglycemic effect and genotoxicity of Psittacanthus calyculatus extract in streptozotocin-induced diabetic rats / Efecto antihiperglicemico y genotoxico de extractos de Psittacanthus calyculatus en ratas diabeticas inducidas con streptozotocina

Psittacanthus calyculatus (DC.) G. Don (Lorantaceae) is known as “ingerto”. The aerial parts are used in the treatment of diabetes and hypertension. Methanolic extract was tested with streptozotocin-induced diabetic rats. Dose of 200 mg/Kg body weight for acute experiments, as well as 200 and 400 mg/Kg for semi-chronic bioassay were used. In both experiments extract produced significant hypoglycemic activity in streptozotocin-induced rats when compared with diabetic control (p 0.05). To study possible clastogenic effects of methanolic extract a mouse micronucleus test was performed (as part of the genetic toxicology trial). CD-1 white mice were administered with 200 and 400 mg/Kg of methanolic extract of P. calyculatus dissolved in water by intraperitoneal injection. The cytotoxic activity polychromatic erythrocytes/normochromatic erythrocytes (PCE/NCE) and the induction of micronuclei in peripheral blood erythrocytes (MNPCE) was recorded with sampling times of 24, 48 and 72, h after an exposure without killing of mice. The frequency of MNPCE in the circulating blood obtained from the tail of the mouse was statistically not significant compared with its negative control animals (time zero) and the PCE/NCE ratio showed evidences of light cytotoxic activity compared with its negative control animals (time zero). Thus, in this test, the methanolic extract of Psittacanthus calyculatus dissolved in water did not induce chromosomal damage resulting in micronucleus formation in peripheral blood erythrocytes and showed light cytotoxic activity.

En la zona del bajío mexicano la planta Psittacanthus calyculatus (DC.) G. Don (Lorantaceae) es conocida popularmente como “ingerto”. Las partes aéreas de este vegetal se utilizan para tratar enfermedades como la diabetes y la hipertensión. Se realizaron experimentos agudos y semi-crónicos en ratas diabéticas inducidas con estreptozotocina. El efecto hipoglucemiante del extracto metanólico se evaluó a dosis de 200 y 400 mg/Kg de peso. En ambos experimentos, el extracto redujo significativamente (p < 0.05) la glucemia en las ratas diabéticas. Para determinar los posibles efectos clastogénicos del extracto metanólico se administraron por vía intraperitoneal a ratones cepa CD-1 las dosis que mostraron actividad hipoglucemiante disueltas en agua y se llevó a cabo el bioensayo de micronúcleos en sangre periférica de ratón. La actividad citotóxica se determinó mediante el cálculo de la relación entre los eritrocitos policromáticos y los eritrocitos normocromáticos (PCE/NCE). La inducción de micronúcleos en eritrocitos de sangre periférica (MNPCE) fue el indicador de gentotoxicidad los cuales se midieron a las 24, 48 y 72 horas después de la administración del extracto. La frecuencia de micronúcleos en eritrocitos policromáticos no fue estadísticamente significativa con relación al control negativo (al tiempo 0) por lo tanto, el extracto no induce daño cromosómico. Asimismo la relación PCE/NCE mostró que el extracto metanólico fue ligeramente citotóxico a la dosis de 400 mg/Kg y a las 48 h posteriores a la administración.

In vivo and in vitro genotoxicity studies of aqueous extract of Xanthium spinosum

The use of plants as a source of palliative or cure for pathological conditions is quite common worldwide. Xanthium spinosum (Asteraceae), popularly known in Brazil as 'espinho de carneiro', is an annual weed from South America, which has been used by empiric medicine to treat neoplasias. Owing to the extensive use of the above-mentioned plant and to the lack of reports about the real effects of its infusion, current study evaluated the genotoxic potential of its aqueous extract at concentrations 0.02 g L-1, 0.1 g L-1 and 0.2 g L-1 by fish micronucleus test and by comet human leukocytes assay. The micronucleus test featured at least 50 cells with micronuclei to every 2,000 cells scored, as a mutagenic parameter. The comet assay was used as a parameter for assessing the level of cell damage and the damage index. Since no significant changes in strain cells exposed to the aqueous extract in the comet and micronucleus assays were reported, it seems that no genotoxicity evidence is extant at the concentrations and in the assays performed.

Em diversos lugares do mundo a utilização de plantas como fonte paliativa ou de cura para determinadas condições patológicas é bastante comum. No Brasil, essa prática não se torna diferente devido à ampla biodiversidade da fauna e flora presentes no País. Nesse contexto, surge a Xanthium spinosum (Asteraceae), conhecida popularmente como "espinho-de-carneiro", um arbusto anual introduzido na América do Sul, o qual tem sido utilizado empiricamente no tratamento de neoplasias. Sabendo do extensivo uso dessa planta em contrapartida com nenhum estudo reportando os reais efeitos de sua infusão, o objetivo do estudo foi avaliar a genotoxicidade do extrato aquoso nas concentrações de 0,02 g L-1, 0,1 g L-1 e 0,2 g L-1, através do ensaio do micronúcleo písceo e do ensaio cometa em leucócitos de sangue humano. O ensaio do micronúcleo tem como parâmetro mutagênico a presença de no mínimo 50 células com micronúcleo em uma contagem de 2.000 células por amostra, enquanto o ensaio cometa utiliza como parâmetro o nível de dano e o índice de dano. Os resultados mostram que não foi possível observar mudanças significativas nas células expostas ao extrato aquoso, em ambos os testes, o que sugere não existir evidência de genotoxicidade nas concentrações utilizadas no ensaio.