Environmental and human risk assessment of landfill leachate: an integrated approach with the use of cytotoxic and genotoxic stress indices in mussel and human cells

The present study investigates leachate hazardous effects on marine biota and human cells, with the use of a battery of assays, both under in vivo and in vitro conditions. According to the results, mussels exposed for 4 days to 0.01 and 0.1% (v/v) of leachate showed increased levels of DNA damage and micronuclei (MN) frequencies in their hemocytes. Similarly, enhanced levels of DNA damage were also observed in hemocytes treated in vitro with relevant concentrations of leachate, followed by a significant enhancement of both superoxide anions (O₂(-)) and lipid peroxidation products (malondialdehyde/MDA). On the other hand, human lymphocyte cultures treated with such a low concentrations of leachate (0.1, 0.2 and 1%, v/v), showed increased frequencies of MN formation and large MN size ratio, as well as decreased cell proliferation, as indicated by the use of the cytokinesis block micronucleus (CBMN) assay and Cytokinesis Block Proliferation Index (CBPI) respectively. These findings showed the clear-cut genotoxic and cytotoxic effects of leachate on both cellular types, as well as its potential aneugenic activity in human lymphocytes.

Chromosomal radiosensitivity in patients with multiple sclerosis

Multiple sclerosis is a clinically heterogeneous autoimmune disease leading to severe neurological disability. Although during the last years many disease-modifying agents as treatment options for multiple sclerosis have been made available, their mechanisms of action are still not fully determined. In the present study radiosensitivity in lymphocytes of patients with relapsing-remitting multiple sclerosis, secondary progressive multiple sclerosis and healthy controls was investigated. Whole blood cultures from multiple sclerosis patients and healthy controls were used to analyze the spontaneous and radiation-induced micronuclei in binucleated lymphocytes. A subgroup of patients with relapsing-remitting multiple sclerosis was treated with immunomodulatory agents, interferon β or glatiramer acetate. The secondary progressive multiple sclerosis patients group was not receiving any treatment. Our results reveal that the basal DNA damage was not different between relapsing-remitting and secondary progressive multiple sclerosis patients, and healthy controls. No differences between gamma-irradiation induced micronuclei frequencies in binucleated cells from relapsing-remitting and secondary progressive multiple sclerosis patients, and healthy controls were found either. Nevertheless, when we compared the radiation induced DNA damage in binucleated cells from healthy individuals with the whole group of patients, a reduction in the frequency of micronuclei was obtained in the patients group. Induced micronuclei yield was significantly lower in the irradiated samples from treated relapsing-remitting multiple sclerosis patients than in healthy controls and relapsing-remitting not treated patients. Intrinsic sensitivity of lymphocytes subpopulations to the apoptotic effect of immunomodulatory treatment could be responsible for this result.

Differential effects of methoxyamine on doxorubicin cytotoxicity and genotoxicity in MDA-MB-231 human breast cancer cells

Pharmacological inhibition of DNA repair is a promising approach to increase the effectiveness of anticancer drugs. The chemotherapeutic drug doxorubicin (Dox) may act, in part, by causing oxidative DNA damage. The base excision repair (BER) pathway effects the repair of many DNA lesions induced by reactive oxygen species (ROS). Methoxyamine (MX) is an indirect inhibitor of apurinic/apyrimidinic endonuclease 1 (APE1), a multifunctional BER protein. We have evaluated the effects of MX on the cytotoxicity and genotoxicity of Dox in MDA-MB-231 metastatic breast cancer cells. MX has little effects on the viability and proliferation of Dox-treated cells. However, as assessed by the cytokinesis-block micronucleus assay (CBMN), MX caused a significant 1.4-fold increase (P<0.05) in the frequency of micronucleated binucleated cells induced by Dox, and also altered the distribution of the numbers of micronuclei. The fluorescence probe dihydroethidium (DHE) indicated little production of ROS by Dox. Overall, our results suggest differential outcomes for the inhibition of APE1 activity in breast cancer cells exposed to Dox, with a sensitizing effect observed for genotoxicity but not for cytotoxicity.

Early biomarkers related to secondary primary cancer risk in radiotherapy treated prostate cancer patients: IMRT versus IMAT

PURPOSE

To investigate whether rotational techniques (Volumetric Modulated Arc Therapy - VMAT) are associated with a higher risk for secondary primary malignancies compared to step-and-shoot Intensity Modulated Radiation Therapy (ss-IMRT). To this end, radiation therapy (RT) induced DNA double-strand-breaks and the resulting chromosomal damage were assessed in peripheral blood T-lymphocytes of prostate cancer (PCa) patients applying γH2AX foci and G0 micronucleus (MN) assays.

METHODS AND MATERIALS

The study comprised 33PCa patients. A blood sample was taken before start of therapy and after the 1st and 3rd RT fraction to determine respectively the RT-induced γH2AX foci and MN. The equivalent total body dose (D(ETB)) was calculated based on treatment planning data.

RESULTS

A linear dose response was obtained for γH2AX foci yields versus D(ETB) while MN showed a linear-quadratic dose response. Patients treated with large volume (LV) VMAT show a significantly higher level of induced γH2AX foci and MN compared to IMRT and small volume (SV) VMAT (p<0.01). Assuming a linear-quadratic relationship, a satisfactory correlation was found between both endpoints (R(2) 0.86).

CONCLUSIONS

Biomarker responses were governed by dose and irradiated volume of normal tissues. No significant differences between IMRT and rotational therapy inherent to the technique itself were observed.

Localization and functional analysis of HmgB3p, a novel protein containing high-mobility-group-box domain from Tetrahymena thermophila

The high-mobility-group (HMG)-box domain represents a very versatile protein domain that mediates the DNA-binding of non-sequence-specific and sequence-specific proteins. HMG-box proteins are involved in various nuclear functions, including modulating chromatin structure and genomic stability. In this study, we identified the gene HMGB3 in Tetrahymena thermophila. The predicted HmgB3p contained a single HMG-box, an SK-rich-repeat domain and a neutral phosphorylated C-terminal. HMGB3 was expressed in the growth and starvation stages. Furthermore, HMGB3 showed a higher expression levels during the conjugation stage. HMGB3 knockout strains showed no obvious cytological defects, although initiation of HMGB3 knockout strain mating was delayed and maximum mating was decreased. HA-HmgB3p localized on the micronucleus (MIC) during the vegetative growth and starvation stages. Furthermore, HA-HmgB3p specially decorated the meiotic and mitotic functional MIC during the conjugation stage. Truncated HMGB3 lacking the HMG box domain disappeared from MICs and diffused in the cytoplasm. Overexpressed HmgB3p was abnormally maintained in newly developing macronuclei and affected the viability of progeny. Taken together, these results show that HmgB3p is a germline micronuclear-specific marker protein. It may bind to micronucleus-specific DNA sequences or structures and is likely to have some function specific to micronuclei of T. thermophila.

Health impact of air pollution to children

Health impact of air pollution to children was studied over the last twenty years in heavily polluted parts of the Czech Republic during. The research program (Teplice Program) analyzed these effects in the polluted district Teplice (North Bohemia) and control district Prachatice (Southern Bohemia). Study of pregnancy outcomes for newborns delivered between 1994 and 1998 demonstrated that increase in intrauterine growth retardation (IUGR) was associated with PM10 and c-PAHs exposure (carcinogenic polycyclic aromatic hydrocarbons) in the first month of gestation. Morbidity was followed in the cohort of newborns (N=1492) up to the age of 10years. Coal combustion in homes was associated with increased incidence of lower respiratory track illness and impaired early childhood skeletal growth up to the age of 3years. In preschool children, we observed the effect of increased concentrations of PM2.5 and PAHs on development of bronchitis. The Northern Moravia Region (Silesia) is characterized by high concentrations of c-PAHs due to industrial air pollution. Exposure to B[a]P (benzo[a]pyrene) in Ostrava-Radvanice is the highest in the EU. Children from this part of the city of Ostrava suffered higher incidence of acute respiratory diseases in the first year of life. Gene expression profiles in leukocytes of asthmatic children compared to children without asthma were evaluated in groups from Ostrava-Radvanice and Prachatice. The results suggest the distinct molecular phenotype of asthma bronchiale in children living in polluted Ostrava region compared to children living in Prachatice. The effect of exposure to air pollution to biomarkers in newborns was analyzed in Prague vs. Ceske Budejovice, two locations with different levels of pollution in winter season. B[a]P concentrations were higher in Ceske Budejovice. DNA adducts and micronuclei were also elevated in cord blood in Ceske Budejovice in comparison to Prague. Study of gene expression profiles in the cord blood showed differential expression of 104 genes. Specifically, biological processes related to immune and defense response were down-regulated in Ceske Budejovice. Our studies demonstrate that air pollution significantly affect child health. Especially noticeable is the increase of respiratory morbidity. With the development of molecular epidemiology, we can further evaluate the health risk of air pollution using biomarkers.

Bystander effects induced by direct and scattered radiation generated during penetration of medium inside a water phantom

BACKGROUND

The biological effects of ionizing radiation have long been thought to results from direct targeting of the nucleus leading to DNA damage. Over the years, a number of non-targeted or epigenetic effects of radiation exposure have been reported where genetic damage occurs in cells that are not directly irradiated but respond to signals transmitted from irradiated cells, a phenomenon termed the "bystander effects".

AIM

We compared the direct and bystander responses of human A 549, BEAS-2-B and NHDF cell lines exposed to both photon (6 MV) and electron (22 MeV) radiation inside a water phantom. The cultures were directly irradiated or exposed to scattered radiation 4 cm outside the field. In parallel, non-irradiated cells (termed bystander cells) were incubated in ICM (irradiation conditioned medium) collected from another pool of irradiated cells (termed donor cells).

MATERIALS AND METHODS

In directly irradiated cells as well as ICM-treated cells, the frequency of micronuclei and condensation of chromatin characteristic for the apoptotic process were estimated using the cytokinesis-block micronucleus test.

RESULTS

In all tested cell lines, radiation induced apoptosis and formation of micronuclei. A549 and BEAS-2B cells cultured in ICM showed increased levels of micronuclei and apoptosis, whereas normal human fibroblasts (NHDF line) were resistant to bystander response. In A549 and BEAS-2B cells placed outside the radiation field and exposed to scattered radiation the formation of micronuclei and induction of apoptosis were similar to that after ICM-treatment.

CONCLUSION

Results suggest that the genetic damage in cells exposed to scattered radiation is caused by factors released by irradiated cells into the medium rather than by DNA damage induced directly by X rays. It seems that bystander effects may have important clinical implications for health risk after low level radiation exposure of cells lying outside the radiation field during clinical treatment.

Micronuclei: An essential biomarker in oral exfoliated cells for grading of oral squamous cell carcinoma

BACKGROUND

Micronuclei in exfoliated oral epithelial cells have been shown in some studies to correlate with severity of this genotoxic damage. This severity can be measured in terms of grading of the lesions.

AIM

To correlate frequency of micronuclei (MN) in oral exfoliated cells in clinically diagnosed cases of oral squamous cell carcinoma (OSCC) followed by a histopathological grading.

MATERIALS AND METHODS

The study subjects consisted of clinically diagnosed cases of OSCC. Healthy subjects without any tobacco consumption habits formed the control group. The cytosmears from both groups were stained with rapid Papanicolaou stain. MN were identified according to the criteria given by Countryman and Heddle with some modifications.

RESULTS

The frequency of MN was three to four times higher in patients with OSCC as compared to patients in the control group and the difference was found to be highly significant. In 75% cases, the cytological grade as determined by the frequency of micronuclei correlated with the histopathological grade and this observation was statistically significant.

CONCLUSIONS

MN can be a candidate to serve as a biomarker for prediction of the grade of OSCC.

Protective effect of l-carnitine against acrylamide-induced DNA damage in somatic and germ cells of mice

Recent findings of acrylamide (AA) in many common foods have sparked renewed interest in assessing human health hazards. AA was evaluated by the International Agency for Research on Cancer as probably carcinogenic to humans. For this reason, the aim of this study is to evaluate the potential genotoxic effect of AA using chromosomal aberration analysis and micronucleus (MN) test in mouse bone-marrow cells and morphological sperm abnormalities. The result of the present work indicated that treatment with a single dose of 10, 20, or 30 mg/kg b.wt. of AA for 24 h and the repeated dose of 10 mg/kg b.wt. for 1and 2 weeks induced a statistically significant increase in the percentage of chromosomal aberrations and micronuclei in bone- marrow cells. These percentages reduced significantly in all groups treated with AA and the protective agent l-carnitine. Also the results indicated that the dose 10, 20 and 30 mg/kg b.wt. of AA induced a statistically significant percentage of morphological sperm abnormalities compared with the control group. Such effect reached its maximum (7.24 ± 0.61) with the highest tested dose which reduced to (4.02 ± 0.58) in the group treated with the same dose of AA and l-carnitine. In conclusion, the results confirm the protective role of LC against the mutagenicity of AA.

Effects of flaxseed(Linum usitatissimum) chutney on gamma-glutamyl transpeptidase and micronuclei profile in azoxymethane treated rats

Antioxidant property of flaxseed chutney was evident by decreasing lipid peroxidation (TBARS) and predictor enzyme γ-glutamyl transpeptidase profile and micronuclei formation in azoxymethane treated rats. After 10 weeks, rats fed with either fiber-free basal diet or Antioxidant diet exhibited over sevenfold increase in γ-glutamyl transpeptidase activity and nearly fourfold increase in micronuclei load in comparison to controls (p<0.001). A significant reduction in both γ-glutamyl transpeptidase level (52%) and micronuclei formation (47%) was observed in fiber-free basal diet/Antioxidant diet/flaxseed chutney diet fed rats. Relative to rats fed fiber-free basal diet, the profile of γ-glutamyl transpeptidase and micronuclei load was not significantly altered.