Micronuclei In Bone Marrow Erythrocytes Research Articles

More efficient induction of genotoxicity by high-LET Fe-particle radiation than low-LET X-ray radiation at low doses

ObjectiveTo understand differential effects on induction of genotoxicity and genomic instability (GI) by high-LET particle radiation and low-LET photon radiation, based on ground-based experiments using total body irradiation (TBI) of mice with Fe-particle radiation and X-ray radiation. MethodsTBI was delivered to C57BL/6J Jms strain female mice of 8 weeks old at a dose ranging from 0.1 to 3.0 Gy of Fe-particle radiation or at a dose ranging from 0.1 to 5.0 Gy of X-ray radiation. Induction of genotoxicity and GI by TBI was determined respectively at 1 and 2 months after exposure using frequency of micronuclei in bone marrow erythrocytes as the endpoint. Inhibition of bone marrow cell proliferation by TBI was measured as reduced erythropoiesis. Physiological conditions were also investigated. ResultsTBI, regardless of the type of radiation, caused statistically significant increase in genotoxicity at 1 month after exposure, but did not induce GI at 2 months after exposure even at higher doses (>1.0 Gy). The dose-response curve for the frequency of micronucleated polychromatic erythrocytes induced by Fe-particle radiation and X-ray radiation was y ​= ​0.7798 ​+ ​1.7889x– 0.5978x2 (R2 = 0.8109) and y ​= ​0.7421 ​+ ​1.3792x – 0.2588 x2 (R2 = 0.8081), respectively. The dose-response curve for the frequency of micronucleated normochromatic erythrocytes induced by Fe-particle radiation and X-ray radiation was y ​= ​0.7191 ​+ ​1.4545x – 0.4978x2 (R2 = 0.7047) and y ​= ​0.658 ​+ ​1.344x – 0.2531x2 (R2 = 0.7853), respectively. In general, high-LET Fe-particle radiation was more efficient in inducing genotoxicity than low-LET X-ray radiation at lower doses (<0.5 Gy). ConclusionsThese results further confirm that exposure to TBI, even at higher doses and regardless the type of radiation, does not induce GI in C57BL/6J strain mice measured as increased micronuclei in bone marrow erythrocytes. These findings indicate that radiation-induced GI is mouse strain dependent and suggest that more comprehensive studies should be done to explore the late health consequences from exposure to high-LET radiation at low doses.

Safety and toxicological evaluation of NXT15906F6 (TamaFlex®)

NXT15906F6 (TamaFlex®) is a food-derived herbal composition with synergistic anti-inflammatory properties and the potential to improve muscle–skeletal function in healthy populations. NXT15906F6 contains standardized ethanol/aqueous extracts of Tamarindus indica seeds and an ethanol extract of Curcuma longa rhizome in a 2:1 ratio. The present study was conducted to evaluate the broad-spectrum safety of NXT15906F6. All studies were conducted in compliance with good laboratory practice requirements and followed Organization for Economic Cooperation and Development Guidelines for Testing of Chemicals. The acute oral and acute dermal lethal dose of NXT15906F6 was greater than 2000 mg/kg body weight in Wistar rats. NXT15906F6 was classified as nonirritating to the skin and as a mild irritant to the eyes of New Zealand white rabbits. A repeated-dose 90-day subchronic study in Wistar rats was conducted. Groups of animals ( n = 20, 10 male and 10 female) were orally supplemented with 0, 250, 500, and 1000 mg/kg/day of NXT15906F6 for 90 days. In parallel, two separate groups of animals ( n = 10, five male and five female) were gavaged with 0 and 1000 mg/kg body weight of NXT15906F6 for 90 days and observed for another 28 days. No morbidity, mortality, or significant adverse events were observed during the study or the follow-up phase. The no observed adverse effect level for NXT15906F6 was 1000 mg/kg/day in both male and female rats. A bacterial reverse mutation test and an in vivo mouse bone marrow erythrocyte micronucleus test showed that the NXT15906F6 herbal blend is nonmutagenic and nongenotoxic. In summary, the safety studies conducted in various models demonstrate the broad-spectrum safety of NXT15906F6.

Genotoxic and inflammatory effects of nanofibrillated cellulose in murine lungs.

Nanofibrillated cellulose (NFC) is a sustainable and renewable nanomaterial, with diverse potential applications in the paper and medical industries. As NFC consists of long fibres of high aspect ratio, we examined here whether TEMPO-(2,2,6,6-tetramethyl-piperidin-1-oxyl) oxidised NFC (length 300-1000nm, thickness 10-25nm), administrated by a single pharyngeal aspiration, could be genotoxic to mice, locally in the lungs or systemically in the bone marrow. Female C57Bl/6 mice were treated with four different doses of NFC (10, 40, 80 and 200 µg/mouse), and samples were collected 24h later. DNA damage was assessed by the comet assay in bronchoalveolar lavage (BAL) and lung cells, and chromosome damage by the bone marrow erythrocyte micronucleus assay. Inflammation was evaluated by BAL cell counts and analysis of cytokines and histopathological alterations in the lungs. A significant induction of DNA damage was observed at the two lower doses of NFC in lung cells, whereas no increase was seen in BAL cells. No effect was detected in the bone marrow micronucleus assay, either. NFC increased the recruitment of inflammatory cells to the lungs, together with a dose-dependent increase in mRNA expression of tumour necrosis factor α, interleukins 1β and 6, and chemokine (C-X-C motif) ligand 5, although there was no effect on the levels of the respective proteins. The histological analysis showed a dose-related accumulation of NFC in the bronchi, the alveoli and some in the cytoplasm of macrophages. In addition, neutrophilic accumulation in the alveolar lung space was observed with increasing dose. Our findings showed that NFC administered by pharyngeal aspiration caused an acute inflammatory response and DNA damage in the lungs, but no systemic genotoxic effect in the bone marrow. The present experimental design did not, however, allow us to determine whether the responses were transient or could persist for a longer time.

Potent radioprotective effect of herbal immunomodulator drug (IMOD) on mouse bone marrow erythrocytes as assayed with the micronucleus test

Background : Although numerous natural or synthec drugs have been tested for their radioprotecve capacity, yet no suitable drug has been introduced for roune clinical use. In this study the radioprotecve effect of new herbal commercially known as IMOD, specifically made to decrease the side effects of HIV virus, was invesgated on mouse bone marrow cells. Materials and Methods : Female NMRI mice (in a group of five) were exposed to 2 Gy gamma radiaon following three days of intravenously injecon (IV) of IMOD at various doses. Mice were sacrificed 48 and 72 h a1er irradiaon. Bone marrow was flushed and slides for bone marrow smears were prepared according to standard method. A1er st aining slides in May Grunwald and Giemsa, polychromac erythrocytes (PCE) and normochromac erythrocytes (NCE) were scored for presence of micronucleus (MN). Results: The results showed that gamma irradiaon increased the frequency of micronuclei dramacally and excreted cytotoxic effect of cell proliferaon. Injecon of various dos es of IMOD before irradiaon however, led to a considerable reducon in the frequency of micronuclei in bone marrow erythrocytes as well as cellular toxicity. Conclusion: Results indicated radioprotecve capability of IMOD with a dose reducon factor (DRF) of about 2.3 at a dose of 20 mg/kg body weight. The considerably high DRF might be indicave that IMOD besides being an immunomodulator might also posses' anoxidant property.

Further investigations into the genotoxicity of quinoxaline-di-N-oxides and their primary metabolites

Quinoxaline-di-N-oxides (QdNOs) are potential antibacterial agents with a wide range of biological properties. Quinocetone (QCT), carbadox (CBX), olaquindox (OLA), mequindox (MEQ) and cyadox (CYA) are classical QdNOs. Though the genotoxicity of parent drugs has been evaluated, the genotoxicity of their primary N → O reduced metabolites remains unclear. In the present study, a battery of four different short-term tests, mouse lymphoma assay (MLA), Ames test, chromosomal aberration assay in vitro and bone marrow erythrocyte micronucleus assay in vivo was carried out to investigate the genotoxicity of the six primary N → O reduced metabolites. Additionally, the genotoxicity of five parent drugs was evaluated by the MLA. Strong genotoxicity of N1-MEQ, B-MEQ and B-CBX was found in three of the assays but not in the Ames assay, and the rank order was N1-MEQ>B-MEQ>B-CBX that is consistent with prototype QdNOs. Negative results for the five QdNOs were noted in the MLA. We present for the first time a comparison of the genotoxicity of primary N → O reduced metabolites, and evaluate the ability of five QdNOs to cause mutations in the MLA. The present study demonstrates that metabolites are involved in genetic toxicity mediated by QdNOs, and improve the prudent use of QdNOs for public health.

Safety assessment of aditoprim acute, subchronic toxicity and mutagenicity studies.

Aditoprim (ADP), a new developed dihydrofolate reductase (DHFR) inhibitor, has great potential in clinical veterinary medicine because of its greater pharmacokinetic properties than structural analogs. Preclinical toxicology studies were performed to assess the safety of ADP including an acute oral toxicity test, a subchronic toxicity test and five mutagenicity tests. In the acute oral toxicity test, ADP was administered singly by oral gavage to Wistar rats and Kunming mice. The LD50 calculated was 1400 mg kg(-1) body weight (BW) day(-1) in rats and 1130 mg kg(-1) BW day(-1) in mice. In a subchronic study, Wistar rats were administered ADP at dose levels of 0, 20, 100 and 1000 mg kg(-1) diet for 90 days. Significant decreases were observed on body weight and food efficiency in the high-dose group. Treatment-related changes in clinical serum biochemistry were found in the medium- and high-dose groups. Significant increases in the relative weights of livers and kidneys in females and testis in males in the 1000 mg kg(-1) diet, and significant decrease in relative weights of livers in males in the 100 mg kg(-1) diet were noted. Histopathological observations revealed that the 1000 mg kg(-1) ADP diet could induce lymphocytic infiltration and hepatocytic necrosis near the hepatic portal area. The genotoxicity of ADP was negative in tests, such as the bacterial reverse mutation assay, mice bone marrow erythrocyte micronucleus assay, in vitro chromosomal aberration test, in vitro cho/hgprt mammalian cell mutagenesis assay and mice testicle cells chromosome aberration. Based on the subchronic study, the no-observed-adverse-effect level for ADP was a 20 mg kg(-1) diet, which is about 1.44-1.53 mg kg(-1) BW day(-1) in rats.

Evaluation Of The Protective Activity Of Phythanthis Fruit Extract On Adriamycin Induced Micronuclei In Bone Marrow Erythrocytes Of Mice

Ariamycin (Doxorubin) is a potent antitumor agent used worldwide for the treatment of many cancers. It has been demonstrated to have a potential for initiating genetic events in non tumor cells in human and in animal models. Due to the importance of adriamycin in chemotherapy for the treatment of cancer, it is important to reduce its toxicity in normal cells. This objective can be achieved by concurrent administration of free radical scavenging agent such as antioxidants Phythanthus emblica fruit extract was used to evaluate its ability to reduce the induction of genetic damage (MNPCEs) by anticancer drug in bone marrow cells of male mice. Two experiments wee conducted. In the first experiment the animals were fed with 100, 250 and 500 mg/kg of PFE for two weeks to analyse the antimutagenicity of fruit extract on micronuclei incidence. In the second experiment Group I were given only saline, G – II animals were administred with single dose of 16 mg/kg adriamycin and G – III the animals were fed with 500 mg/kg PFE for two weeks G – IV were administered with 500 mg/kg for two weeks and adriamycin 16 mg/kg as single dose, one day before the last treatment. Results indicated that the treatment with PFE, co-concurrent administration with adriamycin reduced in the percentage of MNPCEs. No significant difference was observed with treated group of animals. Treatment of mice with PFE did not induce any significant variation in the incidence of MNPCEs as compared to control values. Therefore it is concluded that PFE may act as positive modulators of cytotoxic anticancer agents.

Potential chemoprotective effects of green propolis, L-lysine and celecoxib on bone marrow cells and peripheral blood lymphocytes of Wistar rats subjected to bladder chemical carcinogenesis

To evaluate the genotoxicity of propolis and L-lysine, as well as their effects on the possible cellular damage in erythroblasts (bone marrow) and leukocytes (peripheral blood) caused by the carcinogen BBN (n - butyl - n {4 - hydroxybutyl} nitrosamine) in rats subjected to bladder carcinogenesis and treated with green propolis and L-lysine. One hundred and twenty five rats were distributed into the following groups: I, IIA, IIB, III, K, L M N, X, XI, XII and XIII. Groups I to X received BBN in drinking water for 14 weeks (wks). Group I was treated with intragastric (ig) propolis at 150 mg/kg body weight, for 44 wks, beginning 30 days before start of BBN. Groups IIA and III were treated with propolis (150 mg/kg), for 40 wks, subcutaneous (sc) and ig, respectively, beginning simultaneously with BBN. On the 32nd wk, the animals of groups L, M and N were treated ig with L-lysine (300 mg/kg), celecoxib (30 mg/kg) and propolis (300 mg/kg), respectively, up to the 40th wk. The groups that received only BBN (IIB and K) were treated with water, sc and orally, respectively, for 40 wks. Groups XI, XII and XIII received respectively propolis (150 mg/kg), L-lysine (150 mg/kg) and water ig for 40 wks. After 40 wks, the surviving animals were anesthetized and subjected to femoral bone marrow aspiration and blood collection from the aorta, for CA and MNT, respectively, for investigation of genotoxicity. Groups IIB and K, which received only BBN and water, showed the greatest DNA damage in peripheral leukocytes (CA) and largest number of micronuclei in bone marrow erythrocytes (MNT) in relation to all other groups that received BBN and lysine and/or propolis (p<0.001). Both propolis and L-lysine are effective in protecting against genotoxicity, as well not being genotoxic themselves toward the cells evaluated, at the doses and times administered and according to the two tests utilized.

Genotoxic potential of pirimiphos-methyl organophosphate pesticide using the mouse bone marrow erythrocyte micronucleus and the sperm morphology assay

Background: Pirimiphos-methyl is a potent organophosphate (OP) pesticide used worldwide for the control of pests in stored grains and various insects in domestic, public, agricultural, commercial and industrial settings. However, its pervasive use and broad-spectrum nature could have adverse effects on non-target organisms and the environment which require constant monitoring and assessment. Materials and Methods: In this study, the acute toxicity of pirimiphos-methyl, injected intraperitoneally at concentrations of 833.33, 416.67, 166.67 and 83.33 mg/kg was evaluated. Also, the genotoxic and mutagenic potentials of pirimiphos-methyl were assessed using two eukaryotic assays: The micronucleus and sperm morphology assays in mice, at concentrations of 83.33, 41.67, 20.83, and 8.33 mg/kg. Results: Administration of 416.67 mg/kg pirimiphos-methyl caused 100% mortality in exposed mice under 24 h. Fifty percent mortality resulted from the administration of 166.67 mg/kg dose. There were dose dependent significant increases (P < 0.05) in bone-marrow micronucleated polychromatic and normochromatic erythrocytes as well as aberrant sperms (wrong angle hook, amorphous, banana, no-hook heads, double-tailed and folded sperms) equivalent to the cyclophosphamide induced aberrations. Conclusion: These results indicate that pirimiphos-methyl induced genotoxic damage in exposed mice with consequences for environmental health and safety. These erythropoietic and reproductive changes could be used as biomarkers for monitoring OP pesticide exposed environment.

Safety evaluation of meso-zeaxanthin

Meso-zeaxanthin is a xanthophyll family member of carotenoids. Having closely related structures, meso-zeaxanthin, zeaxanthin and lutein have high concentration in macula and are believed to play a major role in protecting retinal constituents from free radicals. Due to the current technical difficulties in measurement, the presence of meso-zeaxanthin in human blood or tissues has not been reported except in human eyes, which has promoted scientists' interest in exploring potential health benefits of meso-zeaxanthin. Herein, we report a complete toxicological safety assessment of meso-zeaxanthin for use as an ingredient in food, dietary and nutritional supplements, as well as medical food. Assays of acute toxicity, genetic toxicity (Ames test, mice bone marrow erythrocyte micronucleus and mice sperm abnormality) and 90-day sub-chronic toxicity were performed. In the acute oral toxicity tests, maximum tolerable dose was more than 10.0 g/kg bw in SD rats and ICR mice, and showed no toxicological signs during the period of the study. The testing results for three terms of hereditary toxicity (Ames test, mice bone marrow erythrocyte micronucleus and mice sperm abnormality) were all negative. For 90-day feeding of meso-zeaxanthin at the dosage of 300 mg/kg/d in both male and female SD rats, there is no noticeable toxicological effects observed. Therefore, meso-zeaxanthin has no acute toxicity and no genotoxicity and the use of meso-zeaxanthin is safe at dose of 300 mg/kg bw/day in rats from a 90-day feeding study. After the application of a 100-fold safety factor, we obtained the ADI (acceptable daily intake) value of 3 mg/kg body weight per day.

Toxicological Evaluation of Chicken-Breast Meat with High-Dose Irradiation

In this paper, toxicity and safety of high-dose irradiated chicken-breast meat were evaluated. For assays of acute toxicity, genetic toxicity, and sub-chronic toxicity, ames test, mice bone marrow erythrocyte micronucleus, and mice sperm abnormality were performed. The results showed that, in the acute oral toxicity tests, median lethal dose (more than 10 000 mg kg−1) in male and female ICR mice showed no toxicological signs. For subacute 30-d oral toxicology of irradiated chicken-breast meat with dose of 10, 15 and 25 kGy in both male and female SD rats, no noticeable toxicological effects were observed. It is concluded that chicken-breast meat with high-dose irradiation has no acute toxicity and no genotoxicity, nor harmful effects on the animal body at the tested dosage range. Therefore, high-dose irradiated chicken-breast meat is safe for pet consumption.

Genotoxicity assessment of ethylenediamine dinitrate (EDDN) and diethylenetriamine trinitrate (DETN)

Ethylenediamine dinitrate (EDDN) and diethylenetriamine trinitrate (DETN) are relatively insensitive explosive compounds that are being explored as safe alternatives to other more sensitive compounds. When used in combination with other high explosives they are an improvement and may provide additional safety during storage and use. The genetic toxicity of these compounds was evaluated to predict the potential adverse human health effects from exposure by using a standard genetic toxicity test battery which included: a gene mutation test in bacteria (Ames), an in vitro Chinese Hamster Ovary (CHO) cell chromosome aberration test and an in vivo mouse micronucleus test. The results of the Ames test showed that EDDN increased the mean number of revertants per plate with strain TA100, without activation, at 5000μg/plate compared to the solvent control, which indicated a positive result. No positive results were observed with the other tester strains with or without activation in Salmonella typhimurium strains TA98, TA1535, TA1537, and Escherichia coli strain WP2 uvrA. DETN was negative for all Salmonella tester strains and E. coli up to 5000μg/plate both with and without metabolic activation. The CHO cell chromosome aberration assay was performed using EDDN and DETN at concentrations up to 5000μg/mL. The results indicate that these compounds did not induce structural chromosomal aberrations at all tested concentrations in CHO cells, with or without metabolic activation. EDDN and DETN, when tested in vivo in the CD-1 mouse at doses up to 2000mg/kg, did not induce any significant increase in the number of micronuclei in bone marrow erythrocytes. These studies demonstrate that EDDN is mutagenic in one strain of Salmonella (TA100) but was negative in other strains, for in vitro induction of chromosomal aberrations in CHO cells, and for micronuclei in the in vivo mouse micronucleus assay. DETN was not genotoxic in all in vitro and in vivo tests. These results show the in vitro and in vivo genotoxicity potential of these chemicals.

Genotoxicity assessment of two hypergolic energetic propellant compounds

Recognition of the occupational hazards from exposure to the propellants hydrazine and monomethylhydrazine (MMH) has led to research into less toxic alternatives. Two hypergolic compounds, dimethylamino-2-ethylazide (DMAZ) and N,N,N′,N′-tetramethylethanediamine (TMEDA), have been identified as possible replacements for MMH. We have obtained genotoxicity data for these compounds from in vitro and in vivo studies. DMAZ did not produce any mutagenic effects at concentrations up to 5 mg/plate in the TA98 and TA1537 strains of Salmonella typhimurium and in an Escherichia coli (WP2 uvrA) strain, with or without metabolic activation, but did produce a positive response in the TA100 and TA1535 strains, both with and without metabolic activation. TMEDA was found not to be mutagenic in any of the bacterial strains tested ( Salmonella TA98, TA100, TA1535, TA1537 and E. coli, WP2 uvrA), with or without metabolic activation. DMAZ did not induce structural chromosomal aberrations at levels up to 5 mg/mL in Chinese hamster ovary (CHO) cells, with or without metabolic activation. TMEDA produced a positive response in this system, with or without metabolic activation, but only at the highest concentration, 5 mg/mL. However, according to the OECD guideline TG 473, the compound is considered to be negative in the CHO chromosomal aberration assay, since the compound was not clastogenic at 0.01 M (1.140 mg/mL). DMAZ and TMEDA, when tested in vivo in the CD-1 mouse at doses up to 500 and 250 mg/kg, respectively, did not induce micronuclei in bone marrow erythrocytes. These studies demonstrate that DMAZ is mutagenic in specific strains of Salmonella. However, both compounds were negative for induction of chromosomal aberrations in CHO cells in vitro and in the in vivo mouse micronucleus assay.

Safety Pharmacology and Genotoxicity Evaluation of AVI-4658

Duchenne muscular dystrophy (DMD) is caused by dystrophin gene mutations. Restoration of dystrophin by exon skipping was demonstrated with the phosphorodiamidate morpholino oligomers (PMO) class of splice-switching oligomers, in both mouse and dog disease models. The authors report the results of Good Laboratory Practice-compliant safety pharmacology and genotoxicity evaluations of AVI-4658, a PMO under clinical evaluation for DMD. In cynomolgus monkeys, no test article-related effects were seen on cardiovascular, respiratory, global neurological, renal, or liver parameters at the maximum feasible dose (320 mg/kg). Genotoxicity battery showed that AVI-4658 has no genotoxic potential at up to 5000 microg/mL in an in vitro mammalian chromosome aberration test and a bacterial reverse mutation assay. In the mouse bone marrow erythrocyte micronucleus test, a single intravenous injection up to 2000 mg/kg was generally well tolerated and resulted in no mutagenic potential. These results allowed initiation of systemic clinical trials in DMD patients in the United Kingdom.

Modulation of doxorubicin-induced genotoxicity by squalene in Balb/c mice

The present study aims to evaluate the protective effect of squalene against the genotoxicity of the chemotherapeutic agent doxorubicin (Dox) using two genotoxicity assays, the micronucleus assay and the comet assay. Different groups of mice were fed squalene at the doses of 1 and 4 mmol g(-1) body weight (100 or 400 μl as squalene oil) either at 4 h before or 1 h after Dox (20 mg kg(-1)) treatment. 24 h after the Dox treatment, bone marrow erythrocytes were evaluated for the incidence of micronuclei, and the induced DNA strand breaks were examined in heart tissue by the alkaline comet assay. As expected, Dox significantly induced micronuclei in polychromatic (immature) erythrocytes, as well as in total erythrocytes. The frequency of Dox-induced micronucleated erythrocytes was significantly reduced in the mice treated with squalene both before and after Dox administration. Squalene itself obviously did not induce any micronuclei in bone marrow erythrocytes. The comet assay also demonstrated a significant increase in DNA damage, especially DNA single strand breaks in the Dox-treated group of mice as compared to the control. The Dox-induced DNA damage was also effectively reduced by squalene when it was administered either before or after the Dox treatment. Squalene did not induce any significant DNA damage by itself. Compared to the pre-treatment of squalene, post treatment gave rise to more effective prevention against Dox-induced DNA damage. The data suggest that the complimentary use of squalene with Dox will be beneficial to reduce the adverse effect of Dox in cancer chemotherapy, such as the increased incidence of undesirable mutagenic side effects.

Genotoxic effects of the antileishmanial drug glucantime®

Leishmaniasis is caused by species of the protozoan parasite Leishmania. It is the third most important vector-borne disease and is widely distributed throughout the world. The World Health Organization recommends pentavalent antimonials as drugs of first choice in its treatment. Although Glucantime has traditionally been used to treat leishmaniasis, there are still many questions about its structure, mechanisms of action and ability to induce damage in DNA. In this study, the genotoxic activity of this drug was evaluated in vitro using human lymphocytes treated for 3 and 24 h (comet assay) and 48 h (apoptosis assay) with 3.25, 7.5 and 15 mg/ml of Glucantime, respectively, corresponding to 1.06, 2.12 and 4.25 mg/ml of pentavalent antimony. In the in vivo tests, Swiss mice received acute treatment with three doses (212.5, 425 and 850 mg/kg) of pentavalent antimony. All the treatments were administered intraperitoneally in the volumes of 0.1 ml/10 g of body weight, adapting human exposure to murine conditions. The animals were treated for 3 h in the comet assay using resident peritoneal exudate macrophages, for 24 h in the comet assay using peripheral blood leukocytes and for 24 h in the bone marrow erythrocyte micronucleus test. While no genotoxic effect was observed in the in vitro tests, the in vivo tests showed that Glucantime induces DNA damage. These findings indicate that Glucantime is a promutagenic compound that causes damage to DNA after reduction of pentavalent antimony (SbV) into the more toxic trivalent antimony (SbIII) in the antimonial drug meglumine antimoniate.

Induction of micronuclei in rat bone marrow after chronic exposure to lead acetate trihydrate

Lead increasingly contributes to pollution of the environment and may play a role in the development of adverse effects in the human and animal body. Data concerning its mutagenic, clastogenic, and carcinogenic properties have been conflicting. In this study, we evaluated the frequency of micronuclei in bone marrow erythrocytes of rats treated with lead acetate trihydrate. Outbred Wistar rats were exposed to a daily dose of 100 mg/L drinking water for 125 days. The mean value of the total number of micronuclei observed in polychromatic erythrocytes of female rats was significantly higher than that found in the control group (13.375 +/- 2.722 against 9.625 +/- 3.204 micronuclei/1000 cells; P = 0.024 in ANOVA). In exposed female animals, no significant reduction of the ratio of polychromatic to normochromatic erythrocytes was observed (0.990 +/- 0.228 against 1.208 +/- 0.195; P = 0.060 in ANOVA). The effects of lead acetate trihydrate in male rats are both cytotoxic and genotoxic because of a decrease in ratio of polychromatic to normochromatic erythrocytes (0.715 +/- 0.431 against 1.343 +/- 0.306; P = 0.023, ANOVA followed by Tukey test) and an increase in frequency of micronucleated polychromatic erythrocytes (24.167 +/- 7.859 against 4.0 +/- 4.528 micronuclei/1000 cells; P < or = 0.001, ANOVA followed by Tukey test), respectively.

Preliminary safety evaluation of the putative cancer chemopreventive agent tricin, a naturally occurring flavone

Naturally occurring flavonoids such as quercetin and genistein possess cancer chemopreventive properties in experimental models. However, adverse effects such as their mutagenicity confound their potential clinical usefulness. Furthermore in leukaemia cells some flavonoids cleave the breakpoint cluster region of the mixed lineage leukaemia (MLL) gene as a consequence of inhibition of topoisomerase II. The choice of flavonoids to be developed as cancer chemopreventive agents depends crucially on their safety. Here, we explored safety aspects of the novel flavone tricin, a constituent of rice bran and other grass species, which has recently been found to interfere with murine gastrointestinal carcinogenesis. Evidence of pathological or morphological changes in liver, lung, heart, spleen, kidney, adrenal gland, pancreas or thymus tissues was studied in mice which received tricin, genistein or quercetin 1,000 mg/kg daily by the oral route on five consecutive days. The ability of tricin (50 microM) to cleave the MLL gene was studied in human leukaemia cells by Southern blotting, and its effect on human topoisomerase II activity was investigated in incubations with supercoiled DNA. The mutagenicity of tricin was assessed in the Salmonella/Escherichia coli assay, and its clastogenicity was adjudged by chromosomal aberrations in Chinese hamster ovary cells and occurrence of micronuclei in bone marrow erythrocytes in Swiss-Webster mice. Neither tricin, quercetin, or genistein caused pathological or morphological changes in any of the murine tissues studied. Tricin (50 microM) failed to cause MLL gene breakage, and it inhibited topoisomerase II only at 500 microM, but not at 10, 50 or 100 microM. Tricin lacked genotoxic properties in the systems studied here. The results tentatively suggest that tricin may be considered safe enough for clinical development as a cancer chemopreventive agent.

Orthovanadate increased the frequency of aneuploid mouse sperm without micronucleus induction in mouse bone marrow erythrocytes at the same dose level

The objective of the current study was to investigate the ability of orthovanadate to induce aneuploidy in mouse sperm and micronuclei in mouse bone marrow cells at the same dose levels. The BrdU-incorporation assay was performed to test if the chemical treatment altered the duration of the meiotic divisions. It was found that orthovanadate (25mg/kg bw) treatment did not cause meiotic delay. To determine the frequencies of hyperhaploid and diploid sperm, male mice were treated by intraperitoneal (i.p.) injection with 5, 15 or 25mg/kg bw orthovanadate and sperm were sampled from the Caudae epididymes 22 days later. Fluorescence in situ hybridization (FISH) was performed with DNA-probes for chromosomes 8, X or Y. Significant increases in the frequencies of total hyperhaploid sperm (p<0.01) were found with 15 and 25mg/kg bw orthovanadate, indicating induced non-disjunction during male meiosis. The dose-response was described best by a linear equation. Orthovanadate did not significantly increase the frequencies of diploid sperm at any of the three doses tested, indicating that no complete meiotic arrest occurred. Orthovanadate was investigated also by the micronucleus test at i.p. doses of 1, 5, 15 or 25mg/kg bw, followed by bone marrow sampling 24h after treatment. None of the orthovanadate doses caused a significant increase in the rates of micronuclei (MN). Since the results show that orthovanadate induced non-disjunction during male meiosis without an accompanying induction of MN in bone marrow erythrocytes under the present experimental conditions and doses, it is concluded that male germ cells (meiosis) are more sensitive to the aneugenic effects of orthovanadate than somatic cells (mitosis). However, induction of micronuclei was reported in the literature with orthovanadate, vanadylsulfate and ammonium metavanadate, which contradicts the notion that vanadium compounds might be unique germ cell aneugens.

Black bean ( Phaseolus vulgaris L.) as a protective agent against DNA damage in mice

This study was designed to evaluate the toxicogenetic or protective effect of cooked and dehydrated black beans ( Phaseolus vulgaris L.) in bone marrow and peripheral blood cells of exposed mice. The frequency of micronuclei detected using the bone marrow erythrocyte micronucleus test and level of DNA lesions detected by the comet assay were chosen as end-points reflecting mutagenic and genotoxic damage, respectively. Initially, Swiss male mice were fed with a 20% black bean diet in order to detect mutagenic and genotoxic activity. However, no increase in the frequency of bone marrow micronucleated polychromatic erythrocytes (MN PCEs) or DNA lesion in leukocytes was observed. In contrast, received diets containing 1, 10 or 20% of black beans, a clear, but not dose-dependent reduction in the frequency of MN PCEs were observed in animals simultaneously treated with cyclophosphamide, an indirect acting mutagen. Similar results were observed in leukocytes by the comet assay. Commercial anthocyanin was also tested in an attempt to identify the bean components responsible for this protective effect. However, instead of being protective, the flavonoid, at the highest dose administered (50 mg/kg bw), induced primary DNA lesion, as detected by the comet assay. These data indicate the importance of food components in preventing genetic damage induced by chemical mutagens, and also reinforce the role of toxicogenetic techniques in protecting human health.