DNA damage in lymphocytes of Indian rickshaw pullers as measured by the alkaline Comet assay

Prevention of alcohol-induced DNA damage by a proprietary glycyrrhizin/D-mannitol product: A randomized, placebo-controlled, cross-over human study

OBJECTIVES

The purpose of the present study was to evaluate the ability of a proprietary combination of glycyrrhizin and D-mannitol to protect against oxidative damage to DNA associated with acute alcohol consumption by human subjects in a randomized, placebo-controlled cross-over designed study. Excessive alcohol consumption is associated with numerous diseases. Alcohol has been shown to generate reactive oxygen species that can result in DNA damage, leading to genetic and epigenetic changes.

METHODS

A total of 25 subjects (13 male and 12 female) were enrolled. Alcohol intake in the form of vodka (40% ethanol) was adjusted based on 1.275 g of 100% ethanol/kg body weight for men and 1.020 g/kg body weight for women, which was consumed with and without the study product. Blood samples were drawn at 2 h after alcohol consumption, lymphocytes were isolated, and were subjected to DNA comet electrophoresis on a blinded basis.

RESULTS

Acute alcohol consumption increased lymphocyte DNA damage by approximately 8.36%. Co-consumption of the glycyrrhizin/D-mannitol study product with alcohol reduced DNA damage to baseline levels. No adverse effects were associated with use of the study product, and no differences were observed in blood alcohol concentrations in the presence or absence of the study product in males and females.

CONCLUSIONS

Acute alcohol ingestion resulted in measurable increases in DNA damage, which were prevented by the addition of the proprietary glycyrrhizin/D-mannitol (NTX^®) study product to the alcohol, suggesting that the tissue-damaging effects of alcohol consumption can be ameliorated.

Is the oxidative DNA damage level of human lymphocyte correlated with the antioxidant capacity of serum or the base excision repair activity of lymphocyte?

A random screening of human blood samples from 24 individuals of nonsmoker was conducted to examine the correlation between the oxidative DNA damage level of lymphocytes and the antioxidant capacity of serum or the base excision repair (BER) activity of lymphocytes. The oxidative DNA damage level was measured with comet assay containing Fpg/Endo III cleavage, and the BER activity was estimated with a modified comet assay including nuclear extract of lymphocytes for enzymatic cleavage. Antioxidant capacity was determined with trolox equivalent antioxidant capacity assay. We found that though the endogenous DNA oxidation levels varied among the individuals, each individual level appeared to be steady for at least 1 month. Our results indicate that the oxidative DNA damage level is insignificantly or weakly correlated with antioxidant capacity or BER activity, respectively. However, lymphocytes from carriers of Helicobacter pylori (HP) or Hepatitis B virus (HBV) tend to give higher levels of oxidative DNA damage (P < 0.05). Though sera of this group of individuals show no particular tendency with reduced antioxidant capacity, the respective BER activities of lymphocytes are lower in average (P < 0.05). Thus, reduction of repair activity may be associated with the genotoxic effect of HP or HBV infection.

Traffic-related fine and ultrafine particle exposures of professional drivers and illness: an opportunity to better link exposure science and epidemiology to address an occupational hazard?

Exposures to traffic-related air pollution (TRAP) can be particularly high in transport microenvironments (i.e. in and around vehicles) despite the short durations typically spent there. There is a mounting body of evidence that suggests that this is especially true for fine (<2.5 µm) and ultrafine (<100 nm, UF) particles. Professional drivers, who spend extended periods of time in transport microenvironments due to their job, may incur exposures markedly higher than already elevated non-occupational exposures. Numerous epidemiological studies have shown a raised incidence of adverse health outcomes among professional drivers, and exposure to TRAP has been suggested as one of the possible causal factors. Despite this, data describing the range and determinants of occupational exposures to fine and UF particles are largely conspicuous in their absence. Such information could strengthen attempts to define the aetiology of professional drivers' illnesses as it relates to traffic combustion-derived particles. In this article, we suggest that the drivers' occupational fine and UF particle exposures are an exemplar case where opportunities exist to better link exposure science and epidemiology in addressing questions of causality. The nature of the hazard is first introduced, followed by an overview of the health effects attributable to exposures typical of transport microenvironments. Basic determinants of exposure and reduction strategies are also described, and finally the state of knowledge is briefly summarised along with an outline of the main unanswered questions in the topic area.

DNA damage in peripheral blood leukocytes of physically active individuals as measured by the alkaline single cell gel electrophoresis assay

DNA damage induced by physical activity and/or exercise has been reported under different conditions but not for individuals maintaining physical fitness by regular strenuous exercise. Therefore, we compared levels of DNA damage in blood leukocytes of 40 healthy individuals (35 males, 5 females) who regularly exercised in gymnasiums/health clubs and 15 healthy sedentary controls who had never exercised. The former group was selected (after informed consent) on the basis of how long they had been exercising on a regular basis as well as their exercise schedule and regimen. The length of time since starting a regular exercise regimen ranged from 2 months to 9 years, whereas the daily exercise duration ranged from 40 min to 3 hrs and warm-up sessions ranged from none to 90 min. The length of DNA migration (44.66 +/- 2.68 microm in males, 29.62 +/- 1.69 microm in females) and the percentage of cells with tails (79.86 +/-1.27% in males, 67.20 +/- 0.96% in females) in peripheral blood leukocytes of physically active individuals were increased significantly (P < 0.001) with respect to corresponding values in control males and females (18.85 +/- 1.79 microm, 23.37 +/- 3.94 microm; 24.50 +/- 1.98%, 33.00 +/- 4.44%, respectively). Highly significant differences for DNA damage were also observed between physically active males and females. These observations, in the absence of any other exposures, indicate a correlation between strenuous exercise to keep fit and increased levels of DNA damage. This finding may have relevance in terms of the ageing process, with diseases associated with aging, and with carcinogenesis.

Comet assay: a reliable tool for the assessment of DNA damage in different models

New chemicals are being added each year to the existing burden of toxic substances in the environment. This has led to increased pollution of ecosystems as well as deterioration of the air, water, and soil quality. Excessive agricultural and industrial activities adversely affect biodiversity, threatening the survival of species in a particular habitat as well as posing disease risks to humans. Some of the chemicals, e.g., pesticides and heavy metals, may be genotoxic to the sentinel species and/or to non-target species, causing deleterious effects in somatic or germ cells. Test systems which help in hazard prediction and risk assessment are important to assess the genotoxic potential of chemicals before their release into the environment or commercial use as well as DNA damage in flora and fauna affected by contaminated/polluted habitats. The Comet assay has been widely accepted as a simple, sensitive, and rapid tool for assessing DNA damage and repair in individual eukaryotic as well as some prokaryotic cells, and has increasingly found application in diverse fields ranging from genetic toxicology to human epidemiology. This review is an attempt to comprehensively encase the use of Comet assay in different models from bacteria to man, employing diverse cell types to assess the DNA-damaging potential of chemicals and/or environmental conditions. Sentinel species are the first to be affected by adverse changes in their environment. Determination of DNA damage using the Comet assay in these indicator organisms would thus provide information about the genotoxic potential of their habitat at an early stage. This would allow for intervention strategies to be implemented for prevention or reduction of deleterious health effects in the sentinel species as well as in humans.

In vitro induction of cytotoxicity and DNA strand breaks in CHO cells exposed to cypermethrin, pendimethalin and dichlorvos

The indiscriminate use of pesticides and herbicides to increase crop productivity has aroused a great concern among the environmental and health scientists due to their adverse effects in both target as well as non-target species. Although substantial information is available regarding their environmental and ecological impact, not much is known in regard to its toxicity in the mammalian system. Therefore a study was conducted for the assessment of cytotoxic and genotoxic effects of cypermethrin (Type II pyrethroid) dichlorvos (organophosphate) and pendimethalin (dinitroaniline herbicide) in Chinese hamster ovary (CHO) cells. CHO cells were exposed to 1 microM, 10 microM, 100 microM, 1000 microM, and 10,000 microM, cypermethrin, pendimethalin and dichlorvos for 3h and cytotoxicity was assessed by MTT assay. Their genotoxic potential was also evaluated by Comet assay. The results demonstrate that dichlorvos and pendimethalin exhibited higher extent of cytotoxicity as compared to cypermethrin. A significant (p<0.05) concentration dependent increase in DNA damage was observed with dichlorvos (0.01 microM and above) and pendimethalin (0.1 microM and above) as evident by Comet assay parameters viz., Olive tail moment (arbitrary units), tail DNA (%) and tail length (muM). Cypermethrin induced a significant (p<0.05) DNA damage only at higher concentrations (1000 and 5000 microM). Our data indicates that these chemicals produce cytotoxicity and DNA damage in mammalian cells and should be used with caution.

DNA damage induced in human peripheral blood lymphocytes by industrial solid waste and municipal sludge leachates

Exposure of humans to toxic compounds occurs mostly in the form of complex mixtures. Leachates, consisting of mixtures of many chemicals, are a potential risk to human health. In the present study, leachates of solid wastes from a polyfiber factory (PFL), an aeronautical plant (AEL), and a municipal sludge leachate (MSL) were assessed for their ability to induce DNA damage in human peripheral blood lymphocytes using the alkaline Comet assay. The leachates also were examined for their physical and chemical properties. Lymphocytes were incubated with 0.5-15.0% concentrations (pH range 7.1-7.4) of the test leachates for 3 hr at 37 degrees C, and treatment with 1 mM ethyl methanesulfonate served as a positive control. All three leachates induced significant (P < 0.05), concentration-dependent increases in DNA damage compared with the negative control, as measured by increases in Olive tail moment (arbitrary units), tail DNA (%), and tail length (mum). A comparison of these variables among the treatment groups indicated that the MSL induced the most DNA damage. Inductively coupled plasma emission spectrometry analysis of the leachates indicated that they contained high concentrations of heavy metals, viz. iron, manganese, nickel, zinc, cadmium, chromium, and lead. The individual, synergistic, or antagonistic effects of these chemicals in the leachates may be responsible for the DNA damage. Our data indicate that the ever-increasing amounts of leachates from waste landfill sites have the potential to induce DNA damage and suggest that the exposure of human populations to these leachates may lead to adverse health effects.