Comet Assay Parameters Research Articles

Hepatic oxidative stress, DNA damage and apoptosis in adult zebrafish following sub-chronic exposure to BDE-47 and BDE-153.

Polybrominated diphenyl ethers (PBDEs) are ubiquitous and prolific contaminant in both the abiotic and biotic environment because of the wide industrial applications of these chemicals. In the present study, the effects of 2,2',4,4'-tetrabrominateddiphenyl ether (BDE-47) and 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153) exposure on the induction of hepatic oxidative stress, DNA damage, and the expression of apoptosis-related genes in adult zebrafish were investigated. The activities of antioxidant enzymes, such as catalase and superoxide dimutase, significantly increased when adult zebrafish was exposed to various concentrations of BDE-47 and BDE-153 for 7 and 15 days. BDE-47 and BDE-153 elicited significant alterations in zebrafish 7-Ethoxyresorufin-O-deethylase activity at 3, 7, or 15 days of exposure. In addition, the significant increase in comet assay parameters of zebrafish hepatocytes in a concentration-dependent manner indicated BDE-47 and BDE-153 induced DNA damage, probably due to observed oxidative stress. Furthermore, a monotonically upregulation of p53 and Caspase3, which are apoptotic-regulated genes, and decreased expression ratio of the anti-apoptotic B-cell lymphoma/leukaemia-2 and Bcl2-associated X protein genes for all BDE-47 and BDE-153 treatments at 7 and 15 days indicated apoptosis induction in zebrafish liver. Our findings help elucidate the mechanisms of BDE-47- and BDE-153-induced toxicity in zebrafish hepatocytes.

Effects of extender and packaging method on morphological and functional characteristics of cryopreserved Ossimi ram semen

Objective: To test the effects of extenders and packaging methods on morphological and functional characteristics of frozen thawed Ossimi ram semen.Methods: Ram semen was pooled, diluted in 3 different extenders: Tris-egg yolk (TEY), Tris-soybean lecithin (TSBL), and Tris- butylatedhydroxytoluene (TBHT), equilibrated at 5 °C for 4 h, and packaged in straws or pellets for freezing. Semen was evaluated for sperm progressive motility, viability, abnormality, and membrane integrity after dilution, equilibration and thawing. The percentages of viable, early apoptotic, apoptotic, and necrotic spermatozoa as well as comet assay parameters were determined in post-thawed semen. Total antioxidants capacity, malondialdehyde and lactic dehydrogenase were assayed in thawed seminal plasma.Results: After equilibration, only sperm membrane integrity was significantly higher (P < 0.05) in TEY and TSBL than in TBHT. After thawing, TEY or TSBL in straws significantly improved sperm progressive motility and vitality (P < 0.05). In thawed seminal plasma, TBHT or TSBL in straws and TBHT in pellets significantly reduced malondialdehyde, and TBHT in pellets significantly increased lactic dehydrogenase (P < 0.05). TEY in straws increased viable sperm, while significantly decreased early apoptotic and apoptotic sperm (P < 0.05). DNA damage was significantly decreased (P < 0.05) in straws with TEY and TSBL, and tail moment decreased in straws with all extenders (P < 0.05).Conclusions: Despite the disadvantages of dilution of cryopreserved semen with egg yolk, ram semen cryopreserved with TEY gives the best physical, morphological and functional characteristics in straws compared with pellets, followed by semen diluted with TSBL. However, semen diluted with TBHT or TSBL, regardless of packaging method, showed the highest impact on antioxidant status of cyopreserved ram semen.

Influence of Polymorphisms of DNA Repair and GST Genes on Genotoxic Damage and Mutagen Sensitivity in Workers Occupationally Exposed to Very Low Doses of Ionizing Radiation

The study investigated the influence of genetic polymorphisms of the enzymes for DNA repair and detoxification of reactive intermediates on spontaneous and bleomycin-induced (BLM) genotoxic damage in 43 workers exposed to very low doses of ionizing radiation (IR) (mean cumulative dose 5.31 mSv) and 43 subjects with no occupational exposure to IR (controls). In all the subjects examined, the frequency of chromosome aberrations (CAs) and micronuclei (MN), both spontaneous and BLM-induced, the Comet assay parameters (tail intensity), the genotypic variants of the DNA repair enzymes XRCC1 (Arg194Trp, Arg280His, Arg399Gln), XRCC3 (Thr241Met), XPD (Lys751Gln), and of the detoxification enzymes GSTM1 and GSTT1 (null genotype) and BLMH (A1450G) were determined. Among the biomarkers considered, only the frequency of total CAs (p &lt; 0.05), and in particular of chromosome breaks (p &lt; 0.01), was found to be significantly higher in the exposed workers than the controls. The frequency of spontaneous MN was higher in subjects with at least one allelic variant in XRCC1 than in carriers of the wild-type, but again only in exposed workers (p = 0.046). Linear regression analysis showed a positive dependency of the frequency of spontaneous chromosome breaks on occupational exposure, and a dependency of the frequency of BLM-induced MN negative on occupational exposure and positive on alcohol consumption and the null GSTM1 genotype. In conclusion, the frequency of chromosome breaks seems to be a useful cytogenetic biomarker for exposure to very low doses of IR, while only the combined effect of different gene variants or genetic, occupational, and lifestyle habits factors seems to be able to modulate the genotoxic effect of very low doses of IR.

FTIR SPECTROSCOPIC TRENDS AND DNA DAMAGE IN RABBIT LENS DUE TO LONG RUN OF TAMOXIFEN TREATMENT

Objective: The aim of the present work is to evaluate the molecular structure changes of the lens of rabbits and DNA damage of epithelial cells due to tamoxifen administration.&#x0D; Methods: Twenty four healthy New Zealand white rabbits were divided into 2 main groups. The first group is served as control (n=12) kept untreated, second one is Tamoxifen administrative group (n=12) received orally daily dose of 15 mg/kg. Rabbits were decapitated after 2, 4, 6 and 8 mo, respectively. Using fourior transform infrared (FTIR) to study the molecular structure changes due to tamoxifen and comet assay analysis for discovering DNA damage.&#x0D; Results: FTIR data indicated that tamoxifen affects structural components in NHOH and fingerprint region. Increases of β-turns of the protein secondary structure while, reducing the content of both α-helix after 8 mo and Turns appeared for all periods of administrative tamoxifen were observed. On the other hand tamoxifen induced a statistically significant increase in comet assay parameters as tail moment compared to control animals that indicated DNA damage due to single or double strand break.&#x0D; Conclusion: Tamoxifen uses for more than 6 mo may lead to changes in the molecular structure of the lens and damage of DNA cells. An ophthalmic baseline examination prior to anti-cancer treatment may help detect any pre-existing ocular condition and lead to reduction of ocular side effects when predisposed patients are screened and examined regularly during and after chemotherapeutic therapy.

Comparative study between lutein and its liposomal form on cisplatin-induced retinal injury in rabbits

Aim: Lutein is a potent antioxidant that is found in ocular tissue. It protects retina against oxidative stress. We aimed to increase lutein efficiency by encapsulating it into liposome and testing its neuroprotective effect against cisplatin-induced retinal injury in rabbits.Materials and methods: Twenty-four male, New Zealand, rabbits weighing 1.5–2 kg were divided into four groups, as follows: group I as a control, group II received cisplatin, group III received free lutein + cisplatin and group IV received liposomal lutein + cisplatin. All treatments were administrated twice per week for 14 days. Electroretinogram (ERG) was recorded for all rabbits just before decapitation. Then, the retinae were subjected to histopathological evaluations and comet assay.Results: Results indicated significant decrease (p ˂ 0.01) in ERG waves, significant increase (p ˂ 0.01) in all parameters of comet assay (% tailed cells, tail length, DNA% in tail and tail moment), severe fragmentation in photoreceptors layer and changes in inner retina after the administration of cisplatin. There were some sort of improvement in ERG, comet assay and the histological results after the administration of lutein with cisplatin, whereas these tests yielded values comparable to control in the liposomal lutein group.Conclusions: Liposomal lutein administration could prevent the detrimental effects of cisplatin on the retina, while avoiding the use any artificial chemicals. The latter might be preferable but with possible highly toxic effects. Results were promising and worse further future investigations.

Apoptosis and oxidative stress as relevant mechanisms of antitumor activity and genotoxicity of ZnO-NPs alone and in combination with N-acetyl cysteine in tumor-bearing mice.

Background: Several in vitro studies have revealed that zinc oxide nanoparticles (ZnO-NPs) were able to target cancerous cells selectively with minimal damage to healthy cells.Purpose: In the current study, we aimed to evaluate the antitumor activity of ZnO-NPs in Ehrlich solid carcinoma (ESC) bearing mice by measuring their effect on the expression levels of P53, Bax and Bcl2 genes as indicators of apoptotic induction in tumor tissues. Also, we assessed the potential ameliorative or potentiation effect of 100 mg/kg N-acetyl cysteine (NAC) in combination with ZnO-NPs.Materials and methods: ESC bearing mice were gavaged with three different doses of ZnO-NPs (50, 300 and 500 mg/kg body weight) alone or in combination with NAC for seven consecutive days. In addition to measuring the tumor size, pathological changes, zinc content, oxidative stress biomarkers and DNA damage in ESC, normal muscle, liver and kidney tissues were assessed.Results: Data revealed a significant reduction in tumor size with a significant increase in p53 and Bax and decrease in Bcl2 expression levels in the tissues of ZnO-NPs treated ESC bearing mice. Moreover, a significant elevation of MDA accompanied with a significant reduction of CAT and GST. Also, a marked increase in all comet assay parameters was detected in ZnO-NPs treated groups. On the other hand, the combined treatment with ZnO-NPs and NAC significantly reduced reactive oxygen species production and DNA damage in liver and kidney tissues in all ZnO-NPs treated groups.Conclusion: ZnO-NPs exhibited a promising anticancer efficacy in ESC, this could serve as a foundation for developing new cancer therapeutics. Meanwhile, the combined treatment with ZnO-NPs and NAC could act as a protective method for the healthy normal tissue against ZnO-NPs toxicity, without affecting its antitumor activity.

Carbon load in airway macrophages, DNA damage and lung function in taxi drivers exposed to traffic-related air pollution.

To evaluate the potential applicability of carbon load in airway macrophages as a marker of exposure to traffic-related air pollution (TRAP) and its association with parameters of comet assay as a marker of DNA damage, and pulmonary function tests (PFTs) in the group of taxi drivers in Iran. One hundred four male taxi drivers with at least 1-year job history were randomly selected from registered drivers in the taxi union. Airway macrophages were obtained via sputum induction, and then the area of airway macrophages occupied by carbon was measured. DNA damage was determined by comet assay. PFTs were measured by the spirometer. Most of the participants (89.4%) were non-smoker. In this study, 52.7% of non-smoker participants were able to give a sample of sputum with macrophage. Carbon content of airway macrophages was 0.2μm2. There was no significant difference in pulmonary function and comet assay parameters in terms of smoking status. There was an inverse correlation between carbon load with each of comet assay and PFTs parameters, although not statistically significant. This study identified that long-term exposure to TRAP can be a risk factor for pulmonary disorders.

EVALUATION OF GENOTOXICITY PROFILE OF JASADA BHASMA (A ZINC-BASED MINERAL FORMULATION) IN SWISS ALBINO MICE

Objective: Genotoxicity is regarded as one of the potential risk factors for causing pathological diseases. It was confirmed that many chemicals have the mutagenic activity which leads to cancer. A compound which interacts with genetic material DNA and shows adverse effects by altering its structure or function is referred to as genotoxic.Methods: The present study involved 40 Swiss albino mice weighing between 25 and 30 g body weights categorized into four different groups. Group-I (normal control) received 0.5% carboxymethyl cellulose as vehicle. Group-II (toxicant control) received 40 mg/kg/body weight cyclophosphamide on the 28th day. Group-III and IV received test drug JB 15.6 mg/kg and 78 mg/kg, respectively, for 28 consecutive days. Blood samples were collected and processed for evaluating by comet assay. The animals were sacrificed and collected the bone marrow from both the femur for chromosomal aberration and micronuclei assay.Results: JB administered at two different dose levels did not show any significant changes in the comet assay parameters, no micronucleus was found and did not produce any chromosomal aberrations both numerically and structurally when compared to positive test control group.Conclusion: The genotoxicity evaluation of JB did not show any chromosomal aberrations and presence of micronucleus. Thus, the safety data will refine therapeutic utility of JB encouraging their rationale use and translate into greater and broader utilization of JB.

EVALUATION OF GENOTOXICITY PROFILE OF JASADA BHASMA (A ZINC-BASED MINERAL FORMULATION) IN SWISS ALBINO MICE

Objective: Genotoxicity is regarded as one of the potential risk factors for causing pathological diseases. It was confirmed that many chemicals have the mutagenic activity which leads to cancer. A compound which interacts with genetic material DNA and shows adverse effects by altering its structure or function is referred to as genotoxic.Methods: The present study involved 40 Swiss albino mice weighing between 25 and 30 g body weights categorized into four different groups. Group-I (normal control) received 0.5% carboxymethyl cellulose as vehicle. Group-II (toxicant control) received 40 mg/kg/body weight cyclophosphamide on the 28th day. Group-III and IV received test drug JB 15.6 mg/kg and 78 mg/kg, respectively, for 28 consecutive days. Blood samples were collected and processed for evaluating by comet assay. The animals were sacrificed and collected the bone marrow from both the femur for chromosomal aberration and micronuclei assay.Results: JB administered at two different dose levels did not show any significant changes in the comet assay parameters, no micronucleus was found and did not produce any chromosomal aberrations both numerically and structurally when compared to positive test control group.Conclusion: The genotoxicity evaluation of JB did not show any chromosomal aberrations and presence of micronucleus. Thus, the safety data will refine therapeutic utility of JB encouraging their rationale use and translate into greater and broader utilization of JB.

Evaluation of cell and DNA damage induced by panoramic radiography.

X-rays are potential mutagenic agents that can cause both the gene mutations and chromosomal aberrations. In this study, the micronucleus (MN) test and the comet assay methods are implemented in order to observe the damage that can occur in the cell nucleus and in the structure of DNA of the patients who underwent a panoramic examination. In our study, buccal mucosa swabs were obtained just before the radiography and 2 weeks after the radiography from 30 volunteer patients who had to take radiographs due to dental diagnosis. Changes in the nuclei of 1,000 cells of each swab sample had been counted under a light microscope and recorded. Besides, 100 cells of each other swab samples were analyzed by the comet assay. Comet assay parameters namely tail length and percentage of DNA in tail, which indicate the level of DNA damage were analyzed and compared in both groups. Statistical analysis was performed by using the Statistical Package for the Social Sciences (Version 21). In our study, the results of percentage of DNA in tail and tail length before and after X-ray exposure were statistically significant (P < 0.001). Likewise, increase in the MN frequency observed in buccal mucosa cells after X-ray exposure was found significant (P < 0.001). As a result, panoramic radiographs taken during dental diagnosis and treatment cause cytotoxicity and DNA damage in oral mucosal cells. Panoramic radiographs should be applied only when necessary, using an accurate radiographic technique and radioprotection criteria.

Biophysical study regarding the effect of hydrogen sulfide on molecular structure and DNA of mammalian cornea

Background: Humans are affected by both exogenous and endogenous sources of hydrogen sulphide gas (H2S). Its health effects depend on concentration and the duration of gas exposure. These hazards include-among many effects-eye irritation, tearing and inflammation.Objectives: Our study aimed to characterize the side effects induced in cornea due to H2S exposure by using by means of comet assay and Fourior Transformer Infrared Radiation (FTIR).Materials and methods: sixty chinchilla rabbits were randomly grouped into four groups. Group one served as control. Animals were exposed to hydrogen sulphide gas with concentrations of, 90, 250 and 500 ppm. After exposure, animals were decapitated, and the eyes were enucleated from the eye globe. Their corneas were obtained by sectioning through ora serrate. Corneas were then kept frozen at – 20° C for analysis by FTIR spectral and comet assay analysisResults: NH-OH region changes revealed unusual interface/binding mechanism that related to different surrounding environment as well as co-existence of different formations and conformations in the system after exposure to H2S gas. Moreover the exposure to H2S gas has no effect on the CH stretching region that arising from lipid. All parameters of comet assay significantly increase (p˂0.05) due to exposed doses. This increase is directly proportional to the increase in exposure level.Conclusion: Hydrogen sulfide is a very toxic gas to cornea which is considered as window of the eye .it has a serious effect on molecular structure and DNA of cornea. By better understanding its toxicity, we will be able to safely make use of its various benefits without the threat of harm looming over our heads.

COMET ASSAY PARAMETERS OF SPODOPTERA LITTORALIS (BOISD.) LARVAE RESISTANCE SYSTEM CELLS AS AFFECTED BY DIFFERENT COMPOUNDS EXPOSED TO GAMMA IRRADIATION

he Comet assay, called the single cell gel electrophoresis (SCGE) assay or microgel electrophoresis (MGE) assay, primarily measures DNA strand breakage in single cells according to the cell type in vitro and in vivo experiments. The main objective of this study is to assess the sensitivity of genotoxic to be considered in cotton leafworm, Spodoptera littoralis (Boisd.) larvae by causing depletion in cells responsible for functions of the resistance system of this pest to the pesticides as affected by three compounds; Bacillus thuringiensis, Kurs. (Bactericide); Metarhizium anisopltae, Metsch. (Fungicide) and chitosan (biopolymer) exposed to gamma irradiation at doses of 15, 30 and 60 Gy to increase the purpose of its activity on genotoxicity parameters of the cotton leaf worm, S. littoralis (Boisd.) treated as 4th instars larvae by LC50 ,s of compounds mentioned. B. thuringiensis exposed to gamma doses of 15, 30 & 60 Gy had potentiating efficacy on S. littoralis than B. thuringiensis used alone without exposing to gamma doses. While, M. anisopltae and chitosan had nearest results among tested compounds singly and the same compound exposed to gamma doses used. Different comet assay parameters; Cell numbers, comet length (μ), head diameter (μ), % DNA in the head, tail length (μ), % DNA in tail and % tail moment were affected by direct effect of compounds used on S. littoralis larvae lead to death the most of cells and it's DNA degradation or another effect by division increasing in DNA lead to increase the malformation cells or %DNA as well as examined nuclei numbers compared to normal S. littoralis larvae. Also, % DNA in examined nuclei had destruction grades according to the treatments used that ranged from 0-3 grades. In addition, the resistance system cells of S. littoralis that investigated by fluorescence microscopy had clearly injurious appeared in disruption; lost its roundness and cell wall; swelling or shrinking in the most investigated cells. It can be concluded that chitosan exposed to different gamma doses was the most genotoxicity compound affect on resistance system cells of S. littoralis larvae, followed by B. thuringiensis and M. anisopltae exposed to gamma doses.

DNA damage protection by bulk and nano forms of quercetin in lymphocytes of patients with chronic obstructive pulmonary disease exposed to the food mutagen 2-amino-3-methylimidazo [4,5-f]quinolone (IQ)

Chronic obstructive pulmonary disease (COPD) in humans, describes a group of lung conditions characterised by airflow limitation that is poorly reversible. The airflow limitation usually progresses slowly and is related to an abnormal inflammatory response of the lung to toxic particles. COPD is characterised by oxidative stress and an increased risk of lung carcinoma. The 2-amino-3-methylimidazo [4,5-f]quinoline (IQ) is one of a number of mutagenic/carcinogenic heterocyclic amines found mainly in well-cooked meats which are thus part of the regular diet. Antioxidants are very important in order to protect the cells against oxidative damage. The aim of the present study was to assess the effects of IQ on the level of DNA damage and susceptibility to a potent mutagen in peripheral blood cells of COPD patients. DNA damage and the frequency of micronuclei (MNi) were evaluated using the Comet and micronucleus assays, respectively. Differential expressions of both mRNA and protein of the endogenous antioxidant enzyme catalase were evaluated with quantitative polymerase chain reaction (qPCR) and Western blot analysis, respectively. Furthermore, the effect of bulk and nano forms of quercetin and their combination with IQ were examined. Results of the present study clearly demonstrated that MNi frequency in the peripheral blood lymphocytes exhibited a positive correlation with the DNA damage as evident from the different Comet assay parameters. Increase of the endogenous antioxidant catalase also showed there was a stimulation of this enzyme system by IQ. Whereas, the endogenous antioxidant quercetin significantly reduced oxidative stress in COPD patients and healthy individuals.

Exposure to non-ionizing electromagnetic fields emitted from mobile phones induced DNA damage in human ear canal hair follicle cells

ABSTRACTThe aim of this study was to investigate effect of radiofrequency radiation (RFR) emitted from mobile phones on DNA damage in follicle cells of hair in the ear canal. The study was carried out on 56 men (age range: 30–60 years old)in four treatment groups with n = 14 in each group. The groups were defined as follows: people who did not use a mobile phone (Control), people use mobile phones for 0–30 min/day (second group), people use mobile phones for 30–60 min/day (third group) and people use mobile phones for more than 60 min/day (fourth group). Ear canal hair follicle cells taken from the subjects were analyzed by the Comet Assay to determine DNA damages. The Comet Assay parameters measured were head length, tail length, comet length, percentage of head DNA, tail DNA percentage, tail moment, and Olive tail moment. Results of the study showed that DNA damage indicators were higher in the RFR exposure groups than in the control subjects. In addition, DNA damage increased with the daily duration of exposure. In conclusion, RFR emitted from mobile phones has a potential to produce DNA damage in follicle cells of hair in the ear canal. Therefore, mobile phone users have to pay more attention when using wireless phones.

Inorganic Hg toxicity in plants: A comparison of different genotoxic parameters

Inorganic Mercury (Hg) contamination persists an environmental problem, but its cyto- and genotoxicity in plants remains yet unquantified. To determine the extent of Hg-induced cyto- and genotoxicity, and assess most sensitive endpoints in plants, Pisum sativum L. seedlings were exposed for 14 days to different HgCl2 concentrations up to 100 μM. Shoots and roots from hydroponic exposure presented growth impairment and/or morphological disorders for doses >1 μM, being the roots more sensitive. Plant growth, ploidy changes, clastogenicity (HPCV), cell cycle dynamics (G1-S-G2), Comet-tail moment (TM), Comet-TD, Mitotic-index (MI) and cell proliferation index (CPI) were used to evaluate Hg-induced cyto/genotoxicity. Both leaf and root DNA-ploidy levels, assessed by flow cytometry (FCM), remained unaltered after exposure. Root cell cycle impairment occurred at lower doses (≥1 μM) than structural DNA damages (≥10 μM). Cytostatic effects depended on the Hg concentration, with delays during S-phase at lower doses, and arrests at G1 at higher ones. This arrest was paralleled with decreases of both mitotic index (MI) and cell proliferation index (CPI). DNA fragmentation, assessed by the Comet assay parameters of TD and TM, could be visualized for conditions ≥10 μM, while FCM-clastogenic parameter (FPCV) and micronuclei (MNC) were only altered in roots exposed to 100 μM. We demonstrate that inorganic-Hg induced cytostaticity is detectable even at 1 μM (a value found in contaminated sites), while structural DNA breaks/damage are only visualized in plants at concentrations ≥10 μM. We also demonstrate that among the different techniques tested for cyto- and genotoxicity, TD and TM Comet endpoints were more sensitive than FPCV or MNC. Regarding cytostatic effects, cell cycle analysis by FCM, including the difference in % cell cycle phases and CPI were more sensitive than MI or MNC frequency. Our data contribute to better understand Hg cyto- and genotoxicity in plants and to understand the information and sensitivity provided by each of the genotoxic techniques used.

Comet assay is not useful to predict normal tissue response after radiochemotherapy in cervical and larynx cancer patients.

Normal tissues reactions after radiotherapy vary considerably even between patients receiving the same treatment. The ability to predict the differences in radiosensitivity before radiotherapy would have important implication. Patients with squamous cell carcinoma of the: (i) cervix (38 patients) and (ii) larynx (19 patients) were studied. Control group consisted of 9 healthy women. To assess individual radiosensitivity/chemoradiosensitivity alkaline version of comet assay was performed using isolated peripheral blood lymphocytes from cancer patients and healthy donors. The level of endogenous (0Gy), initial (immediately after 6Gy irradiation) and residual (after irradiation and 1h of repair) DNA damage was investigated. The mean value of endogenous damage was similar in control and cervical cancer (CCU) groups and significantly lower than in larynx cancer patients. Cancer patients showed slower DNA repair. For CCU and larynx patients, comet assay parameters were not helpful for unequivocal prediction of appearance of acute and late radiation reaction effects. Comet assay seems to be unable to predict normal tissue reaction after radiochemotherapy. Therefore, there is still need for developing predictive assays, however, due to complicated mechanism of chemoradiosensitivity, only assays assessing not one but many molecular pathways might gives us reliable score.

Oxidative stress and DNA damage in the cord blood of preterm infants

Preterm birth infants are more susceptible to oxidative stress and aftermaths unwanted outcomes such as DNA damage due to hyperoxic stress.In this study, we compared the DNA strand breaks as one of the results of DNA oxidation in white blood cells, malondialdehyde (oxidative stress marker), catalase and superoxide dismutase activity, and total antioxidant capacity (markers of antioxidant defense) in a cord blood plasma of a group of preterm (n=25) and full term births (n=25).The primary DNA damage and plasma oxidative stress markers were significantly higher in a preterm group (p<0.05). Cord plasma activity of superoxide dismutase was significantly lower in preterm infants (p≤0.001). However, there were no significant differences in the cord blood total antioxidant capacity, catalase activity and malondialdehyde in preterm and term infants. Among the oxidative stress markers, the malondialdehyde concentration showed the strongest effect size (1.54; 95%CI: 0.9–2.17). For comet parameters, the most powerful effect size was observed for tail length (5.24; 95% CI: 4.05–6.42). However, tail DNA percent and tail moment were also significantly higher in cases compared to controls. Significant negative correlation was observed between comet assay parameters and birth weight and gestational age when all cases and controls entered into the analysis. There was no significant association between the levels of oxidative stress markers and early DNA damage in cord blood plasma with future nutritional tolerance in preterm infants.In the present study, the primary DNA damage and plasma oxidative stress markers significantly were increased in a preterm group. Preterm babies are more prone to the outcomes related to the early DNA damage. Tail DNA percent does not depend on experimental conditions as other parameters (tail length and thus also tail moment) and can be used for comparison with other studies.

Sleep duration is associated with sperm chromatin integrity among young men in Chongqing, China.

This study explores whether sleep duration is associated with sperm chromatin integrity. To do so, we conducted a three-phase panel study of 796 male volunteers from colleges in Chongqing (China) from 2013 to 2015. Sleep duration was measured using a modified Munich Chronotype Questionnaire. Sperm DNA integrity was examined via Sperm Chromatin Structure Assay and Comet assay. Setting 7-7.5hday-1 of sleep duration as a reference, either longer or shorter sleep duration was associated negatively with high DNA stainability (HDS) (P=0.009), which reflected the immaturity of sperm chromatin. The volunteers with >9.0hday-1 sleep and those with ≤6.5hday-1 sleep had 40.7 and 30.3% lower HDS than did volunteers with 7-7.5hday-1 sleep. No association was found between sleep duration and DNA fragmentation index or Comet assay parameters. This study suggests that sleep duration is associated with sperm chromatin integrity. Further studies are required to validate these findings and investigate the mechanism underlying this association.

Seasonal variations as predictive factors of the comet assay parameters: a retrospective study.

Since there are several predicting factors associated with the comet assay parameters, we have decided to assess the impact of seasonal variations on the comet assay results. A total of 162 volunteers were retrospectively studied, based on the date when blood donations were made. The groups (winter, spring, summer and autumn) were matched in terms of age, gender, smoking status, body mass index and medical diagnostic exposure in order to minimise the impact of other possible predictors. Means and medians of the comet assay parameters were higher when blood was sampled in the warmer period of the year, the values of parameters being the highest during summer. Correlation of meteorological data (air temperature, sun radiation and sun insolation) was observed when data were presented as the median per person. Using multivariate analysis, sampling season and exposure to medical radiation were proved to be the most influential predictors for the comet assay parameters. Taken together, seasonal variation is another variable that needs to be accounted for when conducting a cohort study. Further studies are needed in order to improve the statistical power of the results related to the impact of sun radiation, air temperature and sun insolation on the comet assay parameters.

Genotoxic potential of dental bulk-fill resin composites

ObjectiveTo investigate both genotoxicity and hardening of bulk-fill composite materials applied in 4-mm layer thickness and photo-activated for different exposure times. MethodsThree flowable bulk-fill materials and one conventional flowable composite were filled in molds (height: 4mm) and irradiated for 20 or 30s. The top (0mm) and bottom (4mm) specimen surface were mechanically scraped, and eluates (0.01g composite in 1.5ml RPMI 1640 cell culture media) prepared for each material, surface level and irradiation time. Genotoxicity was assessed in human leukocytes using both the alkaline comet assay and cytokinesis-blocked micronucleus assay, and Knoop hardness (KHN) was measured at the top and bottom specimen surface (n=8). ResultsAt both irradiation times, none of the bulk-fill composites significantly affected comet assay parameters used in primary DNA damage assessment or induced significant formation of any of the scored chromatin abnormalities (number of micronuclei, nuclear buds, nucleoplasmic bridges), whether eluates were obtained from the top or bottom surface. Furthermore, no decrease in KHN from the top to the bottom surface of the bulk-fill materials was observed. On the other hand, the conventional composite irradiated for 20s showed at 4-mm depth a significant increase in the percentage of DNA that migrated in the tail and a significant increase in the number of nuclear buds, as well as a significant decrease in KHN relative to the top surface. SignificanceBulk-fill resin composites, in contrast to conventional composite, applied in 4-mm thickness and photo-activated for at least 20s do not induce relevant genotoxic effects or mechanical instability.