Spontaneous frequency of micronuclei in peripheral blood lymphocytes of Kiev residents]

The level of micronuclei in the peripheral blood lymphocytes of Kyiv residents and its dependence on age, sex and smoking status were studied. Analysis of lymphocytes of 102 healthy Kyiv residents showed that the spontaneous frequency of micronuclei in individuals at the age of 21 to 67 (mean age of 42.6) was 10.5 +/- 0.5@1000. The frequency of micronuclei depends on individual age and increases by 3% per year, and also depends on smoking habits (the micronucleus frequency in smokers was 1.3 times higher then nonsmokers). There is no dependence of the micronucleus frequency on the sex of persons.     

Induction of micronuclei by vinyl acetate in mouse bone marrow cells and cultured human lymphocytes

A dose-dependent increase in micronucleated polychromatic erythrocytes was observed in the bone marrow of male C57B1/6 mice 30 h after a single intraperitoneal injection of vinyl acetate (250, 500, 1000 or 2000 mg/kg b.wt.; (9-14 animals per group). The effect was statistically significant at 1000 mg/kg (1.33 +/- 0.29% vs. 0.6 +/- 0.10% in olive oil-treated controls) and at 2000 mg/kg (1.57 +/- 0.19%) of vinyl acetate. These doses were fatal to 6 (1000 mg/kg) and 8 (2000 mg/kg) out of 14 animals in both groups. The ratio of polychromatic to normochromatic cells decreased as a function of vinyl acetate dose. Cyclophosphamide (20 mg/kg), used as a positive control chemical, induced a clear increase in micronucleated polychromatic erythrocytes (2.07 +/- 0.20%). None of the treatments affected the number of micronuclei in normochromatic erythrocytes. In human whole-blood lymphocyte cultures, micronucleus induction by a 48-h treatment with vinyl acetate (0.125, 0.25, 0.5, 1 and 2 mM; 24 h after culture initiation) was studied in lymphocytes with preserved cytoplasm from smear slides prepared by a method involving the removal of erythrocytes at harvest by sodium cyanide treatment to improve preparation quality. The frequency of micronucleated lymphocytes reached a peak at 0.5 mM (3.2 +/- 1.0% vs. 0.9 +/- 0.1% in control cultures) and 1 mM (3.1 +/- 0.7%), with a decline at 2 mM probably because of a toxic effect resulting in mitotic inhibition.     

Radiation-induced micronucleus frequency in peripheral blood lymphocytes is correlated with normal tissue damage in patients with cervical carcinoma undergoing radiotherapy

In an effort to find a test to predict the response of normal tissue to radiotherapy, the lymphocyte micronucleus assay was used on blood samples from patients with cervical carcinoma. Peripheral blood samples from 55 patients with advanced-stage (II B-IV B) cervical carcinoma were obtained before radiotherapy. The patients were treated with external-beam radiotherapy followed by high-dose-rate brachytherapy. Acute and late normal tissue reactions were scored and correlated with the micronucleus frequency in lymphocytes after irradiation with 4 Gy in vitro. Great interindividual variability was observed in the radiation-induced lymphocyte micronucleus frequency, especially at 4 Gy. The mean number of micronuclei per 100 binucleated cells in cells irradiated with 4 Gy in vitro was significantly higher in samples from patients who suffered from acute and/or late normal tissue reactions than in those from patients with no reactions (51.0 +/- 17.7 and 29.6 +/- 10.1, respectively). A significant correlation was also found between the micronucleus frequency at 4 Gy and the severity of acute reactions and late reactions. However, the overlap between the micronucleus frequencies of patients with high-grade late normal tissue reactions and low-grade reactions is too great to recommend the micronucleus assay in its present form for routine clinical application.     

Mutagenicity studies on paracetamol in human volunteers. III. Cytokinesis block micronucleus method

As paracetamol (PC) affected the frequency of chromosome aberrations and unscheduled DNA synthesis in human volunteers, the genotoxic effects of PC were studied in a group of 12 healthy volunteers (9 females; 3 males, aged 37.8 +/- 8.7 years) using the cytokinesis block micronucleus method in human peripheral lymphocytes. As a positive control a group of elderly people was used, 20 females and 10 males, aged 79.9 +/- 9.5 years. PC was administered orally 3 times in a dose of 1000 mg during 8 h. Blood samples were taken at intervals of 0, 24, 72 and 168 h after the first dose of PC. Cytochalasin B was added to the cultures 44 h after the beginning of the 72-h cultivation at a concentration of 3.0 micrograms/ml. The frequency of cells with micronuclei in the group of volunteers was not significantly increased after PC administration. Using the cytokinesis block micronucleus method, the frequency of micronuclei was stable and the interindividual variability was low. The application of the micronucleus technique in genetic monitoring, e.g., for the occupational exposure to mutagens, is questioned.     

Abnormal Blood Levels of Trace Elements and Metals, DNA Damage, and Breast Cancer in the State of Kuwait

This study aims at investigating the blood level of Cu, Zn, Se, and Cd in breast cancer patients and the association between such level and the frequency of micronucleated lymphocytes. Fifty stage I breast cancer patients were recruited for this study at the time of diagnosis and before receiving any treatment or surgery. The control group consisted of 150 normal females matched to the patients for age (± 5 years). The whole blood level of Cu, Zn, Se, and Cd was determined using spectrophotometry. The frequency of micronucleated lymphocytes in the blood was determined using the cytokinesis-block micronucleus assay. The level of Cu, Zn, and Se was significantly lower (p?=?0.0006, <0.0001, and <0.0001, respectively) in breast cancer patients, as compared to controls. The level of Cd was significantly (p?<?0.0001) higher in the patients, as compared to controls. The frequency of lymphocytes with one micronucleus was significantly (p?<?0.0001) higher in the patients, as compared to controls. In breast cancer patients, the frequency of micronucleated lymphocytes showed different associations with different levels of these trace elements. High Cd, low Zn, low Se, and both high and low Cu levels were significantly associated with micronucleus formation in lymphocytes. A similar association was found in the normal control group only in relation to high Se and Cd levels. Breast cancer patients seem to have abnormal levels of Cu, Zn, Se, and Cd, and such abnormality is associated with micronucleus formation in lymphocytes.     

Micronucleus frequency in peripheral blood lymphocytes and exfoliated buccal cells of untreated cancer patients

Some genetic diseases may increase the cellular instability. Since most human tumors have some genetic base, this study was undertaken for the genetic instability in cancer patients by micronucleus analysis, a mutation-screening test, which is more practical and economic technique than metaphase analysis carried out for chromosomal aberrations. Genetic changes were assessed in untreated cancer patients (lung, stomach and colon cancer) by different genotoxical screening methods; the cytokinesis-block micronucleus test and the buccal mucosa cell micronucleus test. The evaluation of micronuclei number in peripheral blood lymphocytes and buccal cells showed a genomic instability in somatic cells. There was a significant increase in the number of micronuclei in cancer patients prior to the initiation of chemotherapy, and/or radiotherapy compared with healthy human subjects. Furthermore, there was no significant difference between smokers and non-smoking groups or male and female groups. These results suggest that cancer in humans is characterized by an increase of chromosomal damage and thus, the micronucleus assay carried out here may be useful in routine cytogenetic studies of cancer.     

Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c, DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.Abbreviations CP cyclophosphamide - MN micronuclei - MNCE micronucleated normochromatic erythrocytes - MNPCE micronucleated polychromatic erythrocytes - MNRBC micronucleated red blood cells - NCE normochromatic erythrocytes - PCE polychromatic erythrocytes     

Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.Abbreviations CP cyclophosphamide - MN micronuclei - MNCE micronucleated normochromatic erythrocytes - MNPCE micronucleated polychromatic erythrocytes - MNRBC micronucleated red blood cells - NCE normochromatic erythrocytes - PCE polychromatic erythrocytes     

In vitro genotoxicity of polycyclic musk fragrances in the micronucleus test

The synthetic polycyclic musk fragrance compounds galaxolide (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyrane), tonalide (7-acetyl-1,1,3,4,4,6-hexamerthyltetraline), celestolide (4-acetyl-1,1-dimethyl-6-tert-butylindane), phantolide (6-acetyl-1,1,2,3,3,5-hexamethylindane), cashmeran (6,7-dihydro-1,1,2,3,3-pentamethyl-4-(5H) indanone) and traseolide (5-acetyl-1,1,2,6-tetramethyl-3-isopropylindane) were examined for their genotoxicity in the micronucleus test (MNT) with human lymphocytes in vitro in the presence and absence of an exogenous metabolizing system containing rat liver S9 and the metabolically competent human hepatoma cell line Hep G2. Compound concentrations were employed up to cytotoxic doses. Galaxolide, tonalide, celestolide, phantolide, cashmeran and traseolide revealed no genotoxicity in the micronucleus test with human lymphocytes and with the human hepatoma cell line Hep G2.     

Activation status of the X chromosome in human micronucleated lymphocytes

The frequency of X chromosome aneuploidy in human female peripheral blood lymphocytes has been reported by several investigators to be significantly higher than expected based upon chance alone. Studies in our laboratory showed that 72% of the micronuclei in the peripheral blood of human females contained the X chromosome. Such a high frequency of X chromosome loss suggests that some unique mechanism may be responsible for this phenomenon. The present study was carried out to test the hypothesis that the lost or micronucleated chromsome is the inactive and not the active X. Blood samples were obtained from two unrelated females, 36 and 33 years of age, each with a different X; 9 reciprocal translocation. In each, the normal X chromosome is inactive and the translocated X is active. Isolated lymphocytes were cultured according to standard techniques and blocked with cytochalasin B. Using a modified micronucleus assay, we scored 10,000 binucleated cells from the 36 year old, while 9,500 binucleated cells were scored from the 33 year old. The slides were first labeled and the kinetochore status of each micronucleus was determined. This was followed by simultaneous hybridization with a 2.0 kilobase centromeric X chromosome-specific probe and a chromosome 9 specific whole chromosome painting probe. All micronucleated cells were relocated and scored for their probe status. A total of 217 micronuclei were scored from the two subjects, of which 96 (44.2%) contained the X chromosome. Of these 96 micronuclei, 80 (83.3%) contained the inactive X, based on the absence of chromosome 9 material in the micronucleus. These results support our hypothesis that the inactive X chromosome is preferentially included in the micronuclei, and suggest that the X chromosome hypoploidy observed at metaphase in aging women is a related phenomenon. Received: 5 May 1995 / Revised: 15 July 1995     

Aphidicolin and bleomycin induced chromosome damage as biomarker of mutagen sensitivity: a twin study

The induction of chromosome damage in cultured human lymphocytes by in vitro treatments with aphidicolin (APC) and bleomycin (BLM) has been proposed as test of sensitivity to mutagens. To assess their validity, we have investigated whether the individual expression of induced chromosome damage has a genetic rather than an environmental basis. Metaphase analysis for chromosomal aberrations (CA) and micronucleus (MN) assay in cytokinesis-blocked cells have been performed in peripheral blood lymphocytes from 19 healthy male twins (9 monozygotic and 10 dizygotic pairs), aged 70-78 years, after APC, BLM and APC+BLM treatments.Concordance between twins revealed a high genetic component in the sensitivity towards clastogenic action of APC both as percentages of CA and MN. The micronucleus assay demonstrated a genetic basis also in the expression of chromosome damage induced by BLM and APC+BLM treatments. Since twins were elderly people, to investigate the possible role of age, CA and MN frequencies were compared with those found in lymphocytes from 11 young male donors. Basal and APC-induced chromosome damage were clearly increased in the former. Following BLM and APC+BLM treatments, age significantly increased mitotic delay, as shown by the mitotic indexes (MI) and by the ratios between binucleated and mononucleated (B/M) cells.     

Investigating micronucleus assay applicability for prediction of normal tissue intrinsic radiosensitivity in gynecological cancer patients

BackgroundPelvic organs morbidity after irradiation of cancer patients remains a major problem although new technologies have been developed and implemented. A relatively simple and suitable method for routine clinical practice is needed for preliminary assessment of normal tissue intrinsic radiosensitivity. The micronucleus test (MNT) determines the frequency of the radiation induced micronuclei (MN) in peripheral blood lymphocytes, which could serve as an indicator of intrinsic cell radiosensitivity.AimTo investigate a possible use of the micronucleus test (MNT) for acute radiation morbidity prediction in gynecological cancer patients.Materials and methodsForty gynecological cancer patients received 50 Gy conventional external pelvic irradiation after radical surgery. A four-field “box” technique was applied with 2D planning. The control group included 10 healthy females.Acute normal tissue reactions were graded according to NCI CTCAE v.3.0. From all reaction scores, the highest score named “summarized clinical radiosensitivity” was selected for a statistical analysis.MNT was performed before and after in vitro irradiation with 1.5 Gy. The mean radiation induced frequency of micronuclei per 1000 binucleated cells (MN/1000) and lymphocytes containing micronuclei per 1000 binucleated cells (cells with MN/1000) were evaluated for both patients and controls.An arbitrary cut off value was created to pick up a radiosensitive individual: the mean value of spontaneous frequency of cells with MN/1000 ± 2SD, found in the control group.ResultsBoth mean spontaneous frequency of cells with MN/1000 and MN/1000 were registered to be significantly higher in cancer patients compared to the control group (t = 2.46, p = 0.02 and t = 2.51, p = 0.02). No statistical difference was registered when comparing radiation induced MN frequencies between those groups.Eighty percent (32) of patients developed grade 2 summarized clinical radiosensitivity, with great variations in MNT parameters. Only three patients with grade 2 “summarized clinical radiosensitivity” had values of cells with MN/1000 above the chosen radiosensitivity threshold.ConclusionThe present study was not able to confirm in vitro MNT applicability for radiosensitivity prediction in pelvic irradiation.     

Micronucleus frequency in peripheral blood lymphocytes and exfoliated buccal cells of untreated cancer patients

Some genetic diseases may increase the cellular instability. Since most human tumors have some genetic base, this study was undertaken for the genetic instability in cancer patients by micronucleus analysis, a mutation-screening test, which is more practical and economic technique than metaphase analysis carried out for chromosomal aberrations. Genetic changes were assessed in untreated cancer patients (lung, stomach and colon cancer) by different genotoxical screening methods: the cytokinesis-block micronucleus test and the buccal mucosa cell micronucleus test. The evaluation of micronuclei number in peripheral blood lymphocytes and buccal cells showed genomic instability in somatic cells. There was a significant increase in the number of micronuclei in cancer patients prior to the initiation of chemotherapy, and/or radiotherapy compared with healthy human subjects. Furthermore, there was no significant difference between smokers and non-smoking groups or male and female groups. These results suggest that cancer in humans is characterized by an increase of chromosomal damage and thus, the micronucleus assay carried out here may be useful in routine cytogenetic studies of cancer. The text was submitted by the authors in English.     

Lymphocyte ecto-5'-nucleotidase activity in infancy: increasing activity in peripheral blood B cells precedes their ability to synthesize IgG in vitro

Ecto-5'-nucleotidase activity was measured in peripheral blood lymphocytes isolated from serial specimens from nine healthy full-term infants and two premature infants at 0, 2, 4, and 6 mo of age. The postnatal nadir in activity was 7.1 +/- 2.0 nmol/hr/10(6) cells, which is the same as the activity in cord blood lymphocytes (7.0 +/- 2 nmol/hr/10(6) cells). The activity rose twofold to 13.2 +/- 3.8 nmol/hr/10(6) cells at 6 mo of age (p less than 0.001, paired t-test), which is similar to the activity in adult peripheral blood lymphocytes (14.1 +/- 6.3 nmol/hr/10(6) cells). This increased activity in total lymphocytes reflects increased activity in the B cell population. B cell ecto-5'-nucleotidase activity in two infants at 12 to 13 mo of age was 19.3 and 25.2 nmol/hr/10(6) cells, values that are four-to fivefold higher than for cord blood B cells (5.6 +/- 2.8 nmol/hr/10(6) cells) and within the normal range for adult B cells (27.9 +/- 12 nmol/hr/10(6) cells). In spite of a greatly expanded peripheral blood B cell population, studies of immunoglobulin biosynthesis in vitro demonstrated that infant peripheral blood B cells are functionally immature with no synthesis of IgG in response to Epstein Barr virus. Thus, the increase in peripheral blood B lymphocyte ecto-5'-nucleotidase activity in infants precedes their acquisition of a capacity for IgG synthesis in vitro. Data from a hypogammaglobulinemic infant revealed a persistently low ecto-5'-nucleotidase activity over a 10-mo period until at 14 mo of age the activity was 8.8 nmol/hr/10(6) cells in total lymphocytes and 13.0 nmol/hr/10(6) cells in B cells, which correlated with in vivo and in vitro evidence of delayed B cell maturation. Thus, ecto-5'-nucleotidase activity may be a useful cell surface marker in studies of human postnatal B cell maturation.     

Micronuclei in lymphocytes of young patients under antileukemic therapy.

The micronucleus test in peripheral blood lymphocytes was employed in the cytogenetic monitoring of children with acute lymphocytic leukemia (ALL), who had undergone chemotherapy and radiotherapy. Patients were treated with a variety of drugs, which included vincristine, methotrexate, daunomycin and prednisone; they also underwent cranial irradiation at the end of the first intensive phase of therapy. The first group under study consisted of 15 subjects on therapy, who showed a marked increase in micronucleated lymphocytes (mean: 19.96 +/- 12.96%) as a consequence of treatment compared with the control group (mean: 3.67 +/- 1.55%), while lower average values were obtained from 15 other subjects at the end of treatment (mean: 13.16 +/- 8.44%). A group of 6 patients was monitored during the entire period of therapy, namely at diagnosis, after 3 months of therapy, throughout maintenance therapy and at the end of it. The whole treatment lasted about 2 years. The results revealed a marked increase in basal micronucleus frequency, due to therapy: the micronucleated lymphocyte frequency remained significantly high throughout the treatment for almost all patients. These data clearly suggest the validity of the methodology in pointing out the role played by antileukemic agents in inducing somatic genetic damage.     

Genotoxic potential of cyfluthrin

Cyfluthrin (CAS no. 68359-37-5), a synthetic fluorinated pyrethroid insecticide, is widely used in the home environment and in agriculture because of its high activity against a broad spectrum of insect pests and its low animal toxicity. There are no adequate data on genotoxic effects of cyfluthrin. The aim of this study was to analyze the potential genotoxic effects of cyfluthrin. The genotoxicity of cyfluthrin was evaluated, in vitro, by assessing the ability of the insecticide to induce gene mutation (evaluated using the Ames/microsome test), chromosomal aberrations (CA), sister chromatid exchange (SCE) and micronucleus (MN) formation in cultured human peripheral blood lymphocytes. Additionally, CAs and cytotoxicity induced by cyfluthrin were investigated in rat (Rattus norvegicus var. Albinos) bone-marrow cells to assess in vivo genotoxicity of cyfluthrin. The counts of reverse mutations in Salmonella typhimurium were not significantly increased (P>0.05). The frequency of CAs in human lymphocytes, treated with any concentration of cyfluthrin (500, 1000 or 2000 microg/ml) for a 24-h period, was not significantly increased (P>0.05). In contrast, CA was significantly increased for the highest two concentrations (1000 and 2000 microg/ml) in the 48-h treatment group compared with the control group (dimethyl sulfoxide, DMSO). Micronucleus formation was significantly (P<0.05) increased for all doses after the 48-h treatment, although the frequency of SCE did not increase significantly (P>0.05). Mitotic index (MI), proliferation index (PI) and nuclear division index (NDI) decreased significantly (P<0.05) due to the potential cytotoxicity of cyfluthrin, especially after the 48-h treatment period. The frequency of chromosome aberrations in bone-marrow cells of rats treated with the test substance increased significantly (P<0.05) for all doses (250, 500 and 1000 mg/kg body weight) for the two treatment periods (12 and 24 h) and the two administration routes, viz. intraperitoneal injection (i.p.) and oral gavage (gvg). In vivo cytotoxicity of cyfluthrin was detected only after administration by gavage for the 24-h treatment period. All these findings were not dose-dependent.     

In vitro cytotoxic potential of newly synthesized furo[3,2-<Emphasis Type="Italic">c</Emphasis>]pyran-4-one derivatives in cultured human lymphocytes

The in vitro cytotoxic potentials of Furo[3,2-c]pyran-4-one derivatives in human lymphocytes were investigated. Blood samples were obtained from six healthy donors, non-smoking volunteers, which were incubated and exposed to increasing concentrations (0.05, 0.1, 0.5, 1 and 2 mg/mL) of Furo[3,2-c]pyran-4-one derivatives which are methyl 2-methoxy-7-(4-methylbenzoyl)-6-(4-methylphenyl)-4-oxo-4H-furo[3,2-c]pyran-3-carboxylate (1a) and methyl 2-methoxy-7-(4-methoxybenzoyl)-6-(4-methoxyphenyl)-4-oxo-4H-furo[3,2-c]pyran-3-carboxylate (1b). Compounds 1a and 1b induced micronucleus, mitotic and replication indexes in human lymphocytes (1 and 2 mg/mL). The increases of micronucleus, mitotic and replication indexes show that compounds at high concentrations may become cytotoxic, genotoxic and carcinogenic.     

复合生物杀菌剂F6-11的安全性毒理学研究

目的：为研究复合生物杀菌剂F6．11毒性,采用动物实验法进行毒理学评价。方法：对复合生物杀菌剂F6-11进行小鼠急性毒性试验、小鼠骨髓嗜多染红细胞微核试验、亚急性毒性试验、家兔多次完整皮肤刺激试验、急性眼刺激试验、豚鼠皮肤变态反应试验、鱼类延长毒性14天试验。结果：复合生物杀菌剂F6—11对小鼠急性毒性LD50〉5000mg／kg．bw,属于实际无毒级物质;小鼠微核试验该杀菌剂各剂量组与阴性对照组比较,微核率无显著性差异（P〉0．05）;亚急性毒性试验动物血常规、生化指标及各脏器均未发现异常;对家兔多次完整皮肤及眼刺激反应积分均为0,均属无刺激性;对豚鼠皮肤变态反应试验组动物与阴性对照组无可见不同．试验组动物皮肤致敏反应积分为0,无致敏作用;鱼类延长毒性14天试验无异常。结论：毒理学研究表明,复合生物杀菌剂F6．11具有良好的使用安全性。     

Comparative analysis of cytotoxic, genotoxic and antioxidant effects of 2,2,4,7-tetramethyl-1,2,3,4-tetrahydroquinoline and ethoxyquin on human lymphocytes

2,2,4,7-Tetramethyl-1,2,3,4-tetrahydroquinoline (THQ) is a new synthetic compound with potential antioxidant activity. In this study, cytotoxic, genotoxic and antioxidant activities of THQ were studied on human lymphocytes with the use of the trypan blue exclusion assay, the TUNEL method, the comet assay and the micronucleus test. The activities of THQ were compared with those of a structurally similar compound-ethoxyquin (1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline, EQ), which is used in animal feeds as a preservative. Cytotoxic effects of THQ were observed after 1-h treatment at the concentration of 500 microM and after 24-h treatments at the concentrations of 250-500 microM. Although the micronucleus test did not reveal a genotoxic effect of THQ, in the comet assay the statistically significant increase in DNA damage was observed as compared with the control. On the other hand, the protection of human lymphocytes against DNA damage induced by hydrogen peroxide suggests an antioxidant activity of THQ. The comparative analysis of THQ and EQ activities performed in these studies revealed that THQ was less cytotoxic and less genotoxic than EQ. Slightly lower antioxidant activity of THQ was also shown in the comet assay when it was used at the lower studied doses (1-5 microM), but for the highest one (10 microM) its efficiency was similar to that of EQ. In the micronucleus assay THQ was more effective than EQ in protecting the cultured lymphocytes from clastogenicity of H2O2. We believe that THQ is worthy of further detailed studies on its antioxidant properties to confirm its usefulness as a preservative.     

Frequency of micronuclei induced in peripheral lymphocytes by trimethyltin chloride

The clastogenicity of trimethyltin chloride was evaluated in human peripheral blood lymphocytes with micronucleus counts (MNC) as the endpoint. Two concentrations (0.5 micrograms and 1.0 microgram) of trimethyltin chloride were added to lymphocytes of healthy male and female subjects of different age groups, in mitogen-stimulated and serum-supplemented culture medium (RPMI 1640, Gibco) for 48 h at 37 degrees C. A significant increase in micronucleus counts was observed with both doses, which was more pronounced with the lower dose. ANOVA in male and female donors revealed significant differences between age groups (P less than 0.001), chemical concentrations (P less than 0.001) and for the interaction of these 2 factors (P less than 0.05 in females only). However, no regular increase or decrease in MNC frequencies was observed with the donor's age. Higher frequencies of MNC enhancement were observed in male individuals than in females.