Effects of concomitant use of THC and irinotecan on tumour growth and biochemical markers in a syngeneic mouse model of colon cancer.

Clinical treatment with the antineoplastic drug irinotecan (IRI) is often hindered by side effects that significantly reduce the quality of life of treated patients. Due to the growing public support for products with Δ9-tetrahydrocannabinol (THC), even though relevant scientific literature does not provide clear evidence of their high antitumour potential, some cancer patients take unregistered preparations containing up to 80 % THC. This study was conducted on a syngeneic colorectal cancer mouse model to test the efficiency and safety of concomitant treatment with IRI and THC. Male BALB/c mice subcutaneously injected with CT26 cells were receiving 60 mg/kg of IRI intraperitoneally on day 1 and 5 of treatment and/or 7 mg/kg of THC by gavage a day for 7 days. Treatment responses were evaluated based on changes in body, brain, and liver weight, tumour growth, blood cholinesterase activity, and oxidative stress parameters. Irinotecan's systemic toxicity was evidenced by weight loss and high oxidative stress. The important finding of this study is that combining THC with IRI diminishes IRI efficiency in inhibiting tumour growth. However, further studies, focused on more subtle molecular methods in tumour tissue and analytical analysis of IRI and THC distribution in tumour-bearing mice, are needed to prove our observations.

The effects of ketamine on viability, primary DNA damage, and oxidative stress parameters in HepG2 and SH-SY5Y cells.

Ketamine is a dissociative anaesthetic used to induce general anaesthesia in humans and laboratory animals. Due to its hallucinogenic and dissociative effects, it is also used as a recreational drug. Anaesthetic agents can cause toxic effects at the cellular level and affect cell survival, induce DNA damage, and cause oxidant/antioxidant imbalance. The aim of this study was to explore these possible adverse effects of ketamine on hepatocellular HepG2 and neuroblastoma SH-SY5Y cells after 24-hour exposure to a concentration range covering concentrations used in analgesia, drug abuse, and anaesthesia (0.39, 1.56, and 6.25 µmol/L, respectively). At these concentrations ketamine had relatively low toxic outcomes, as it lowered HepG2 and SH-SY5Y cell viability up to 30 %, and low, potentially repairable DNA damage. Interestingly, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione (GSH) remained unchanged in both cell lines. On the other hand, oxidative stress markers [superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)] pointed to ketamine-induced oxidant/antioxidant imbalance.

Cytotoxic, genotoxic, and oxidative stress-related effects of lysergic acid diethylamide (LSD) and phencyclidine (PCP) in the human neuroblastoma SH-SY5Y cell line.

Lysergic acid diethylamide (LSD) is a classic hallucinogen, widely abused for decades, while phencyclidine (PCP) has increased in popularity in recent years, especially among the adolescents. Very little is known about the general toxicity of these compounds, especially about their possible neurotoxic effects at the cell level. The aim of this study was to address these gaps by assessing the toxic effects of 24-hour exposure to LSD and PCP in the concentration range of 0.39-100 µmol/L in the human neuroblastoma SH-SY5Y cell line. After cell viability was established, cells treated with concentrations that reduced their viability up to 30 % were further subjected to the alkaline comet assay and biochemical assays that enable estimation of oxidative stress-related effects. Treatment with LSD at 6.25 µmol/L and with PCP at 3.13 µmol/L resulted with 88.06±2.05 and 84.17±3.19 % of viable cells, respectively, and led to a significant increase in primary DNA damage compared to negative control. LSD also caused a significant increase in malondialdehyde level, reactive oxygen species (ROS) production, and glutathione (GSH) level, PCP significantly increased ROS but lowered GSH compared to control. Treatment with LSD significantly increased the activities of all antioxidant enzymes, while PCP treatment significantly increased superoxide dismutase (SOD) and glutathione peroxidase (GPx) but decreased catalase (CAT) activity compared to control. Our findings suggest that LSD has a greater DNA damaging potential and stronger oxidative activity than PCP in SH-SY5Y cells.

Oxidative stress, cholinesterase activity, and DNA damage in the liver, whole blood, and plasma of Wistar rats following a 28-day exposure to glyphosate.

In this 28 day-study, we evaluated the effects of herbicide glyphosate administered by gavage to Wistar rats at daily doses equivalent to 0.1 of the acceptable operator exposure level (AOEL), 0.5 of the consumer acceptable daily intake (ADI), 1.75 (corresponding to the chronic population-adjusted dose, cPAD), and 10 mg kg-1 body weight (bw) (corresponding to 100 times the AOEL). At the end of each treatment, the body and liver weights were measured and compared with their baseline values. DNA damage in leukocytes and liver tissue was estimated with the alkaline comet assay. Oxidative stress was evaluated using a battery of endpoints to establish lipid peroxidation via thiobarbituric reactive substances (TBARS) level, level of reactive oxygen species (ROS), glutathione (GSH) level, and the activity of glutathione peroxidase (GSH-Px). Total cholinesterase activity and the activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were also measured. The exposed animals gained less weight than control. Treatment resulted in significantly higher primary DNA damage in the liver cells and leukocytes. Glyphosate exposure significantly lowered TBARS in the liver of the AOEL, ADI, and cPAD groups, and in plasma in the AOEL and cPAD group. AChE was inhibited with all treatments, but the AOEL and ADI groups significantly differed from control. Total ChE and plasma/liver ROS/GSH levels did not significantly differ from control, except for the 35 % decrease in ChE in the AOEL and ADI groups and a significant drop in liver GSH in the cPAD and 100xAOEL groups. AOEL and ADI blood GSH-Px activity dropped significantly, but in the liver it significantly increased in the ADI, cPAD, and 100xAOEL groups vs. control. All these findings show that even exposure to low glyphosate levels can have serious adverse effects and points to a need to change the approach to risk assessment of low-level chronic/sub-chronic glyphosate exposure, where oxidative stress is not necessarily related to the genetic damage and AChE inhibition.

Effects of low doses of glyphosate on DNA damage, cell proliferation and oxidative stress in the HepG2 cell line.

We studied the toxic effects of glyphosate in vitro on HepG2 cells exposed for 4 and 24 h to low glyphosate concentrations likely to be encountered in occupational and residential exposures [the acceptable daily intake (ADI; 0.5 µg/mL), residential exposure level (REL; 2.91 µg/mL) and occupational exposure level (OEL; 3.5 µg/mL)]. The assessments were performed using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell proliferation, alkaline comet assay and cytokinesis-block micronucleus (CBMN) cytome assay. The results obtained indicated effects on cell proliferation, both at 4 and 24 h. The levels of primary DNA damage after 4-h exposure were lower in treated vs. control samples, but were not significantly changed after 24 h. Using the CBMN assay, we found a significantly higher number of MN and nuclear buds at ADI and REL after 4 h and a lower number of MN after 24 h. The obtained results revealed significant oxidative damage. Four-hour exposure resulted in significant decrease at ADI [lipid peroxidation and glutathione peroxidase (GSH-Px)] and OEL [lipid peroxidation and level of total antioxidant capacity (TAC)], and 24-h exposure in significant decrease at OEL (TAC and GSH-Px). No significant effects were observed for the level of reactive oxygen species (ROS) and glutathione (GSH) for both treatment, and for 24 h for lipid peroxidation. Taken together, the elevated levels of cytogenetic damage found by the CBMN assay and the mechanisms of primary DNA damage should be further clarified, considering that the comet assay results indicate possible cross-linking or DNA adduct formation.

Assessment of oxidative stress responses and the cytotoxic and genotoxic potential of the herbicide tembotrione in HepG2 cells.

Tembotrione is a triketone herbicide, usually used for post-emergence weed control in corn. Currently, there is little or no published data on its genotoxicity to human cells either in vitro or in vivo. This study evaluated the impact of acute (4 and 24 h) exposure to low concentrations of tembotrione [corresponding to the acceptable daily intake (0.17 µg/mL), residential exposure level (0.002 µg/mL) and acceptable operator exposure level (0.0012 µg/mL)] on human hepatocellular carcinoma cell line HepG2, using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell viability, alkaline comet assay, and cytokinesis-block micronucleus "cytome" assay. Tembotrione applied at concentrations likely to be encountered in occupational and residential exposures induced cytogenetic outcomes in non-target cells despite non-significant changes in the values of oxidative stress biomarkers. We assume that the observed effects were mainly the consequence of impaired metabolic pathways in HepG2 cells due to the inhibition of the enzyme 4-hydroxyphenyl-pyruvate-dioxygenase by tembotrione, which possibly caused a depletion of folate levels leading to excess formation of nuclear buds in the affected cells. Regardless of the fact that tembotrione was previously reported negative for mutations and chromosome aberrations in vitro, our findings call for more precaution in its use.

Effects of high sucrose diet, gemfibrozil, and their combination on plasma paraoxonase 1 activity and lipid levels in rats.

We investigated the influence of high sucrose diet (HSD) after 3 or 5 weeks of administration on paraoxonase 1 (PON1) activity in plasma of normolipidemic rats and the relationship between serum PON1 activity, triacylglycerides (TGs), HDL and total cholesterol vs. the control group of rats fed normal, control diet (CD). Because the data about the influence of gemfibrozil (GEM) on PON1 activity are controversial, we also investigated its effects (administration in the 4th and 5th week in rats on HSD and CD) on plasma PON1 activity and lipid levels in normolipidemic rats, and in rats with hypertriglyceridemia caused by HSD. Our results obtained in rats on HSD show a significant increase of plasma TGs levels by 47% (P<0.05) after 5 weeks of treatment, and PON1 activity by 32% and 23% (P<0.05) after 3 and 5 weeks, but without change in lipid levels vs. rats on CD. In the rats on CD and HSD, GEM caused a significant decrease of PON1 activity by 44% and 33%, while a significant decrease of TGs level by 38% (P<0.05) was measured only in rats on CD. The effects of GEM on total cholesterol, HDL and LDL in both groups of rats were typical for its action on lipoprotein metabolism. Because GEM in the rat liver stimulates proliferation of peroxisomes, ß oxidation, and production of H2O2, it is possible that the oxidative stress induced by GEM damages hepatocytes and lowers the synthesis of PON1.

In vivo experimental approach to treatment against tabun poisoning.

Organophosphorus compounds pose a potential threat to both military and civilian populations. Since post-exposure therapy has its limitations, our research was focused on the possibility of improving pretreatment in order to limit the toxic effects of tabun. We determined the protective index of various combinations of atropine, oximes (K074, K048, and TMB-4), and pyridostigmine given to mice before tabun intoxication. Although the tested oximes showed very good therapeutic efficacy in tabun-poisoned mice, the given pretreatments improved therapy against tabun poisoning. These regimens ensured survival of all animals up to 25.2 LD(50) of tabun. Our results indicate that even pretreatment with atropine alone is sufficiently effective in enhancing the survival of mice poisoned by multiple doses of tabun, if oxime therapy follows. K048 is our oxime of choice for future research, as it shows better protective and reactivating potency.

Qualitative GC-MS assessment of TCP and TAMORF elimination in rats.

Nerve agents are highly toxic organophosphorus (OP) compounds. They inhibit acetylcholinesterase (AChE), an enzyme that hydrolyses acetycholine (ACh) in the nervous system. Pathophysiological changes caused by OP poisonings are primarily the consequence of surplus ACh on cholinergic receptors and in the central nervous system. Standard treatment of OP poisoning includes combined administration of carbamates, atropine, oximes and anticonvulsants. In order to improve therapy, new compounds have been synthesised and tested. Tenocyclidine (TCP) and its adamantane derivative 1-[2-(2-thienyl)-2-adamantyl] morpholine (TAMORF) have shown interesting properties against soman poisoning. In this study, we developed a qualitative GC-MS method to measure elimination of TCP and TAMORF through rat urine in order to learn more about the mechanisms through which TCP protects an organism from OP poisoning and to determine the duration of this protective effect. GC-MS showed that six hours after treatment with TCP, rat urine contained only its metabolite 1-thienylcyclohexene, while urine of rats treated with TAMORF contained both TAMORF and its metabolites.

Effect of occupational exposure to multiple pesticides on translocation yield and chromosomal aberrations in lymphocytes of plant workers.

Employees handling pesticides are simultaneously exposed to different active substances. Occurring multiple chemical exposures may pose a higher risk than it could be deduced from studies evaluating the effect of a single substance. This study comprised 32 pesticide plantworkers exposed to carbofuran, chlorpyrifos, metalaxyl, and dodine and an equal number of control subjects. Groups were matched by age (43.8 +/- 10.16 vs 41.8 +/- 7.42, respectively), sex (14 females; 18 males), and smoking (11 smokers; 21 nonsmokers). Chromosome aberration and translocation frequencies were determined using a standard aberration assay and fluorescent in situ hybridization (FISH) by applying painting probes for chromosomes 1, 2, and 4. Although significant, an observed increase in chromatid breaks (5.2 +/- 2.49) compared to controls (2.1 +/- 0.87), p(PostHoc) = 0.000001 is biologically irrelevant. Genomic frequency of translocations was also significantly elevated (exposed 0.0165 +/- 0.0070; control 0.0051 +/- 0.0023, P(PostHoc) = 0.000004). The distribution of translocations among chromosomes 1, 2, and 4 did not differ from control subjects. It corresponded to the distribution of DNA content among selected chromosomes indicating randomness of DNA damage. A good translocation yield correlation within years spent in pesticide production indicates that multiple pesticide exposure may pose a risk to genome integrity. However, for more accurate health risk assessments, the use of probes for some other groups of chromosomes should be considered.

Irinotecan side effects relieved by the use of HI-6 oxime: in vivo experimental approach.

Some compounds, although not primarily designed as supportive drugs in chemotherapy, are promising candidates for clinical use. The ability of HI-6 oxime to relieve the side effects of irinotecan was recently determined in vitro. In this animal study, we investigated the efficacy of HI-6 in vivo, when given as a pre-treatment and concomitantly with irinotecan. We evaluated the cholinesterase (ChE)/acetylcholinesterase (AChE) activity, the levels of oxidative stress markers, DNA damage and the radical scavenging capacity of HI-6. Both HI-6 and irinotecan inhibited ChE/AChE activity but showed different levels of ChE inhibition in plasma and AChE inhibition in the liver and brain tissue. We also observed a weak antioxidant capacity of HI-6, undiscovered until now, and found an acceptable genotoxicity profile in three types of somatic cells in rats. The in vivo erythrocyte micronucleus assay showed that HI-6 did not significantly change either the frequency of micronuclei or the ratio of polychromatic and normorchromatic erythrocytes. Taken together, our results provide a good argument in favour of HI-6 as a promising molecule for further studies and eventual use in humans.

Evaluation of genome damage and its relation to oxidative stress induced by glyphosate in human lymphocytes in vitro.

In the present study we evaluated the genotoxic and oxidative potential of glyphosate on human lymphocytes at concentrations likely to be encountered in residential and occupational exposure. Testing was done with and without metabolic activation (S9). Ferric-reducing ability of plasma (FRAP), thiobarbituric acid reactive substances (TBARS) and the hOGG1 modified comet assay were used to measure glyphosate's oxidative potential and its impact on DNA. Genotoxicity was evaluated by alkaline comet and analysis of micronuclei and other nuclear instabilities applying centromere probes. The alkaline comet assay showed significantly increased tail length (20.39 microm) and intensity (2.19%) for 580 microg/ml, and increased tail intensity (1.88%) at 92.8 microg/ml, compared to control values of 18.15 mum for tail length and 1.14% for tail intensity. With S9, tail length was significantly increased for all concentrations tested: 3.5, 92.8, and 580 microg/ml. Using the hOGG1 comet assay, a significant increase in tail intensity was observed at 2.91 microg/ml with S9 and 580 microg/ml without S9. Without S9, the frequency of micronuclei, nuclear buds and nucleoplasmic bridges slightly increased at concentrations 3.5 microg/ml and higher. The presence of S9 significantly elevated the frequency of nuclear instabilities only for 580 microg/ml. FRAP values slightly increased only at 580 microg/ml regardless of metabolic activation, while TBARS values increased significantly. Since for any of the assays applied, no clear dose-dependent effect was observed, it indicates that glyphosate in concentrations relevant to human exposure do not pose significant health risk.

Evaluation of oxime k203 as antidote in tabun poisoning.

We studied bispyridinium oxime K203 [(E)-1-(4-carbamoylpyridinium)-4-(4-hydroxyiminomethylpyridinium)-but-2-ene dibromide] with tabun-inhibited human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in vitro, and its antidotal effect on tabun-poisoned mice and rats in vivo. We compared it with oximes K048 and TMB-4, which have proven the most efficient oxime antidotes in tabun poisoning by now. Tabun-inhibited AChE was completely reactivated by K203, with the overall reactivation rate constant of 1806 L mol(-1) min(-1). This means that K203 is a very potent reactivator of tabun-inhibited AChE. In addition, K203 reversibly inhibited AChE (Ki = 0.090 mmol L(-1)) and BChE (K(i) = 0.91 mmol L(-1)), and exhibited its protective effect against phosphorylation of AChE by tabun in vitro. In vivo, a quarter of the LD50 K203 dose insured survival of all mice after the application of as many as 8 LD50 doses of tabun, which is the highest dosage obtained compared to K048 and TMB-4. Moreover, K203 showed high therapeutic potency in tabun-poisoned rats, preserving cholinesterase activity in rat plasma up to 60 min after poisoning. This therapeutic improvement obtained by K203 in tabun-poisoning places this oxime in the spotlight for further development.

Cholinesterase-inhibiting and genotoxic effects of acute carbofuran intoxication in man: a case report.

Carbofuran belongs to the group of N-methylcarbamate insecticides used for the control of soil-dwelling and foliar-feeding insects in various crops; its consumption totals approximately 20,000 tonnes per year. Although the neurological effects on human beings have been well documented, little is known on its impact on the genome. A 38-year-old, healthy male worker employed in a carbofuran production facility accidentally inhaled the dust of the active ingredient carbofuran. Thirty minutes later, he experienced weakness, fatigue, perspiration, breathing difficulties, cephalalgia, disorientation, abdominal pain and vomiting. Blood samples were taken to measure cholinesterase activity, and to perform the alkaline comet assay and micronucleus assay combined with pancentromeric probes. Analyses were repeated 72 hr after intoxication and compared with the results obtained from regular monitoring conducted 10 days prior to the accident. Cholinesterase activity showed the highest correlation with the number of apoptotic cells, comet assay tail length, and number of long-tailed nuclei, suggesting that these are the genomic end-points primarily affected by carbofuran intake. Only a weak correlation was detected for the total number of micronuclei, centromere-containing micronuclei and nuclear buds. Since those end-points increased significantly 72 hr after the accident, they could be considered as late biomarkers of the effects of carbofuran intoxication. The results of this report suggest that, in the interests of higher standards in risk assessment and health hazard protection, periodical medical examination of carbamate-exposed populations should include genotoxicity testing in addition to the assessment of cholinesterase activity.

New bispyridinium oximes: in vitro and in vivo evaluation of their biological efficiency in soman and tabun poisoning.

Improving the efficacy of antidotal treatment of poisonings with nerve agents is still a challenge for the scientific community. This study investigated the interactions of four bispyridinium oximes with human erythrocyte acetylcholinesterase (AChE) and their effects on soman- and tabun-poisoned mice. Oximes HI-6 and TMB-4 were used for comparison. These oximes inhibited AchE with inhibitory potency (IC(50)) ranging from 0.02 to 1.0 mM. The best reactivating potency (%R) was obtained with K074, when AChE was inhibited by tabun. The protective potency (P(50)) of all oximes in human erythrocyte AChE inhibited by soman and tabun could not be determined. In tabun-poisoned mice very good antidotal efficacy was obtained with K027, K048, and K074, which makes them interesting for future investigation. The combination of HI-6 and atropine is the therapy of choice for soman poisoning.

Oximes: Reactivators of phosphorylated acetylcholinesterase and antidotes in therapy against tabun poisoning.

One of the therapeutic approaches to organophosphate poisoning is to reactivate AChE with site-directed nucleophiles such as oximes. However, pyridinium oximes 2-PAM, HI-6, TMB-4 and obidoxime, found as the most effective reactivators, have limiting reactivating potency in tabun poisoning. We tested oximes varying in the type of ring (pyridinium and/or imidazolium), the length and type of the linker between rings, and in the position of the oxime group on the ring to find more effective oximes to reactivate tabun-inhibited human erythrocyte AChE. Three of our tested pyridinium oximes K027, K048, K074, along with TMB-4, were the most promising for AChE reactivation. Promising oximes were further tested in vivo on tabun poisoned mice not only as antidotes in combination with atropine but also as pretreatment drug. Herein, we showed that a promising treatment in tabun poisoning by selected oximes and atropine could be improved if oximes are also used in pretreatment. Since the reactivating efficacy of the oximes in vitro corresponded to their therapeutic efficacy in vivo, it seems that pharmacological effect of these oximes is indeed primarily related to the reactivation of tabun-phosphorylated AChE.

Tenocyclidine treatment in soman-poisoned rats--intriguing results on genotoxicity versus protection.

This study aimed to evaluate the antidotal potency of tenocyclidine (TCP) that probably might protect acetylcholinesterase (AChE) in the case of organophosphate poisoning. TCP was tested alone as a pretreatment or in combination with atropine as a therapy in rats poisoned with (1/4) and (1/2) of LD(50) of soman. Possible genotoxic effects of TCP in white blood cells and brain tissue were also studied. Results were compared with previous findings on the adamantyl tenocyclidine derivative TAMORF. TCP given alone as pretreatment, 5 min before soman, seems to be superior in the protection of cholinesterase (ChE) catalytic activity in the plasma than in brain, especially after administration of the lower dose of soman. Plasma activities of the enzyme after a joint treatment with TCP and soman were significantly increased at 30 min (P<0.001) and 24 h (P=0.0043), as compared to soman alone. TCP and atropine, given as therapy, were more effective than TCP administered alone as a pretreatment. The above therapy significantly increased activities of the enzyme at 30 min (P=0.046) and 24 h (P<0.001), as compared to controls treated with (1/4) LD(50) of soman alone. Using the alkaline comet assay, acceptable genotoxicity of TCP was observed. However, the controversial role of TCP in brain protection of soman-poisoned rats should be studied further.

Evaluation of HI-6 oxime: potential use in protection of human acetylcholinesterase inhibited by antineoplastic drug irinotecan and its cyto/genotoxicity in vitro.

The function of acetylcholinesterase (AChE) is the rapid hydrolysis of the neurotransmitter acetylcholine (ACh), which is involved in the numerous cholinergic pathways in both the central and the peripheral nervous system. Therefore, AChE measurement is of high value for therapy management, especially during the course of intoxication with different chemicals or drugs that inhibit the enzyme. Pyridinium or bispyridinium aldoximes (oximes) are able to recover the activity of the inhibited enzyme. Since their adverse effects are not well elucidated, in this study the efficiency of HI-6 oxime in protection and/or reactivation of human erythrocyte AChE inhibited by the antineoplastic drug irinotecan as well as its cyto/genotoxicity in vitro were investigated. HI-6 was effective in protection of AChE and increased its activity up to 30%; the residual activity after irinotecan inhibition was 7%. Also, it reactivated the enzyme previously inhibited by 50% irinotecan (4.6 microg/ml) applied at 1/4 of the IC50 value. The tested concentrations of HI-6 exhibited acceptable genotoxicity towards white blood cells, as estimated by the alkaline comet assay, DNA diffusion assay and cytogenetic endpoints (structural chromosome aberrations and cytokinesis-block micronucleus assay). The results obtained warrant the further investigation of HI-6 in vivo, as well as its development for possible application in chemotherapy.

Comparative evaluation of acetylcholinesterase status and genome damage in blood cells of industrial workers exposed to carbofuran.

Literature data on carbofuran genotoxicity in vitro and in vivo are very scarce. There are few papers indicating that occupational exposure to this AChE inhibiting insecticide might be connected to increased risk of developing non-Hodgkin's lymphoma and lung cancer. Other authors showed its genotoxicity in vitro. We used comet and CBMN micronucleus assay combined with centromere probes to evaluate genome damage in lymphocytes of workers employed in carbofuran production. Also, the level of AChE activity in blood and plasma was measured. Only few workers exhibited AChE activity below 85%. Comet assay parameters were slightly but significantly elevated compared to control subjects, especially the long-tailed nuclei ratio. We found poor correlation between AChE activity and comet assay parameters, but significant effect of smoking and alcohol intake on the latest. In binucleated lymphocytes of workers significantly increased number of micronuclei, nuclear buds, and nucleoplasmic bridges was detected. Proportion of micronuclei with centromere, DAPI signal positive micronuclei was also elevated. Micronucleus assay parameters also appeared to be significantly influenced by duration of exposure to carbofuran. Together with published data on carbofuran's effect on health our results might indicate the need for further evaluations of its genotoxicity using a range of different cytogenetic techniques.

The involvement of oxidative stress in ochratoxin A and fumonisin B1 toxicity in rats.

The aim of this study was to find out whether very low doses of nephrotoxic and hepatotoxic mycotoxins ochratoxin A (OTA) and fumonisin B1 (FB1) induce oxidative stress in rat kidney and liver and whether their effect is synergistic. Rats were treated orally with OTA (5 ng/kg b.w. and 50 microg/kg b.w.) and FB1 (200 ng/kg b.w. and 50 microg/kg b.w.), or their combinations. Malondialdehyde (MDA) and protein carbonyls (PCs) concentration in kidney was affected with lower dose of OTA than in liver (p<0.05). FB1 did not affect MDA and PCs concentrations in the liver, while in the kidney both FB1 doses increased MDA concentration (p<0.05). The combination of the lower doses of OTA+FB1 increased the MDA and PCs concentration both in the liver and the kidney, compared to controls and animals treated with respective doses of mycotoxins (p<0.05). The combinations of mycotoxins reduced the catalase activity only in the kidney when compared to controls (p<0.05). In contrast to the increased kidney concentrations of MDA and PCs even with very low doses of OTA and FB1, the activity of catalase and SOD does not change. Combinations of OTA+FB1 affected almost all parameters, which indicates their potential to produce oxidative damage.