Browsing by Author "Gajski, Goran"
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- Application of the comet assay in human biomonitoring: an hCOMET perspectivePublication . Azqueta, Amaya; Ladeira, Carina; Giovannelli, Lisa; Boutet-Robinet, Elisa; Bonassi, Stefano; Neri, Monica; Gajski, Goran; Duthie, Susan; Del Bo’, Cristian; Riso, Patrizia; Koppen, Gudrun; Basaran, Nursen; Collins, Andrew; Møller, PeterThe comet assay is a well-accepted biomonitoring tool to examine the effect of dietary, lifestyle, environmental and occupational exposure on levels of DNA damage in human cells. With such a wide range of determinants for DNA damage levels, it becomes challenging to deal with confounding and certain factors are interrelated (e.g. poor nutritional intake may correlate with smoking status). This review describes the effect of intrinsic (i.e. sex, age, tobacco smoking, occupational exposure, and obesity) and extrinsic (season, environmental exposures, diet, physical activity, and alcohol consumption) factors on the level of DNA damage measured by the standard or enzyme-modified comet assay. Although each factor influences at least one comet assay endpoint, the collective evidence does not indicate single factors have a large impact. Thus, controlling for confounding may be necessary for a biomonitoring study, but none of the factors is strong enough to be regarded as a priori as a confounder. Controlling for confounding in the comet assay requires a case-by-case approach. Inter-laboratory variation in levels of DNA damage and to some extent also reproducibility in biomonitoring studies are issues that have haunted the users of the comet assay for years. Procedures to collect specimens, and their storage, are not standardized. Likewise, statistical issues related to both sample-size calculation (before sampling of specimens) and statistical analysis of the results vary between studies. This review gives guidance to statistical analysis of the typically complex exposure, co-variate, and effect relationships in human biomonitoring studies.
- Collection and storage of human white blood cells for analysis of DNA damage and repair activity using the comet assay in molecular epidemiology studiesPublication . Møller, Peter; Bankoglu, Ezgi Eyluel; Stopper, Helga; Giovannelli, Lisa; Ladeira, Carina; Koppen, Gudrun; Gajski, Goran; Collins, Andrew; Valdiglesias, Vanessa; Laffon, Blanca; Boutet-Robinet, Elisa; Perdry, Hervé; Del Bo’, Cristian; Langie, Sabine A S; Dusinska, Maria; Azqueta, AmayaDNA damage and repair activity are often assessed in blood samples from humans in different types of molecular epidemiology studies. However, it is not always feasible to analyze the samples on the day of collection without any type of storage. For instance, certain studies use repeated sampling of cells from the same subject or samples from different subjects collected at different time points, and it is desirable to analyze all these samples in the same comet assay experiment. In addition, flawless comet assay analyses on frozen samples open up the possibility of using this technique on biobank material. In this article, we discuss the use of cryopreserved peripheral blood mononuclear cells (PBMCs), buffy coat (BC), and whole blood (WB) for analysis of DNA damage and repair using the comet assay. The published literature and the authors' experiences indicate that various types of blood samples can be cryopreserved with only a minor effect on the basal level of DNA damage. There is evidence to suggest that WB and PBMCs can be cryopreserved for several years without much effect on the level of DNA damage. However, care should be taken when cryopreserving WB and BCs. It is possible to use either fresh or frozen samples of blood cells, but results from fresh and frozen cells should not be used in the same dataset. The article outlines detailed protocols for the cryopreservation of PBMCs, BCs, and WB samples.
- DNA damage in circulating leukocytes measured with the comet assay may predict the risk of deathPublication . Bonassi, Stefano; Ceppi, Marcello; Møller, Peter; Azqueta, Amaya; Milić, Mirta; Monica, Neri; Brunborg, Gunnar; Godschalk, Roger; Koppen, Gudrun; Langie, Sabine A. S.; Teixeira, João Paulo; Bruzzone, Marco; Da Silva, Juliana; Benedetti, Danieli; Cavallo, Delia; Ursini, Cinzia Lucia; Giovannelli, Lisa; Moretti, Silvia; Riso, Patrizia; Del Bo’, Cristian; Russo, Patrizia; Dobrzyńska, Malgorzata; Goroshinskaya, Irina A.; Surikova, Ekaterina I.; Staruchova, Marta; Barančokova, Magdalena; Volkovova, Katarina; Kažimirova, Alena; Smolkova, Bozena; Laffon, Blanca; Valdiglesias, Vanessa; Pastor, Susana; Marcos, Ricard; Hernández, Alba; Gajski, Goran; Spremo-Potparević, Biljana; Živković, Lada; Boutet-Robinet, Elisa; Perdry, Hervé; Lebailly, Pierre; Perez, Carlos L.; Basaran, Nursen; Nemeth, Zsuzsanna; Safar, Anna; Dusinska, Maria; Collins, Andrew; Anderson, Diana; Andrade, Vanessa; Pereira, Cristiana Costa; Costa, Solange; Gutzkow, Kristine B.; Ladeira, Carina; Moretti, Massimo; Costa, Carla; Orlow, Irene; Rojas, Emilio; Pourrut, Bertrand; Kruszewski, Marcin; Knasmueller, Siegfried; Shaposhnikov, Sergey; Žegura, Bojana; Stopper, HelgaThe comet assay or single cell gel electrophoresis is the most common method used to measure strand breaks and a variety of other DNA lesions in human populations. To estimate the risk of overall mortality, mortality by cause, and cancer incidence associated with DNA damage, a cohort of 2,403 healthy individuals (25,978 person-years) screened in 16 laboratories using the comet assay between 1996 and 2016 was followed-up. Kaplan–Meier analysis indicated a worse overall survival in the medium and high tertile of DNA damage (p < 0.001). The effect of DNA damage on survival was modeled according to Cox proportional hazard regression model. The adjusted hazard ratio (HR) was 1.42 (1.06–1.90) for overall mortality and 1.94 (1.04–3.59) for diseases of the circulatory system in subjects with the highest tertile of DNA damage. The findings of this study provide epidemiological evidence encouraging the implementation of the comet assay in preventive strategies for non-communicable diseases.
- Forgotten public health impacts of cancer: an overviewPublication . Viegas, Susana; Ladeira, Carina; Costa-Veiga, Ana; Perelman, Julian; Gajski, GoranCancer is one of the diseases of greatest concern in developed countries and much effort has been invested in discovering and developing therapeutics for curing cancer. Despite the improvements in antineoplastic therapeutics in the last decades, cancer is still one of the most harmful diseases worldwide. The global burden of cancer also implies financial costs: these can be direct costs, such as those related to treatment, care, and rehabilitation and indirect, which include the loss of economic output due to missed work (morbidity costs) and premature death (mortality costs). There are also hidden costs such as health insurance premiums and nonmedical expenses that are worth noting. This paper intends to present an overview of the generally forgotten impacts that the increasing number of cancer cases can have on the environment, workers who handle antineoplastic drugs, and health services. The knowledge available of each of the impacts will be addressed and discussed regarding the expected development. Overall, lessons learned reflect on the impact of cancer through aspects not commonly evidenced in the literature or even considered in the socio-economic analysis, in part due to the fact that these are difficult to contemplate in direct and indirect cancer costs already defined. Attention may be drawn to the need for continuous investment in prevention to reduce the negative impact on the environment and in the health of workers who handle antineoplastic drugs for patients’ treatment.
- Genotoxicity assessment of a selected cytostatic drug mixture in human lymphocytes: a study based on concentrations relevant for occupational exposurePublication . Gajski, Goran; Ladeira, Carina; Gerić, Marko; Garaj-Vrhovac, Vera; Viegas, SusanaCytostatic drugs are highly cytotoxic agents used in cancer treatment and although their benefit is unquestionable, they have been recognized as hazardous to healthcare professionals in occupational settings. In a working environment, simultaneous exposure to cytostatics may occur creating a higher risk than that of a single substance. Hence, the present study evaluated the combined cyto/genotoxicity of a mixture of selected cytostatics with different mechanisms of action (MoA; 5-fluorouracil, cyclophosphamide, and paclitaxel) towards human lymphocytes in vitro at a concentration range relevant for occupational as well as environmental exposure. The results suggest that the selected cytostatic drug mixture is potentially cyto/genotoxic and that it can induce cell and genome damage even at low concentrations. This indicates not only that such mixture may pose a risk to cell and genome integrity, but also that single compound toxicity data are not sufficient for the prediction of toxicity in a complex working environment. The presence of drugs in different amounts and with different MoA suggests the need to study the relationship between the presence of genotoxic components in the mixture and the resulting effects, taking into account the MoA of each component by itself. Therefore, this study provides new data sets necessary for scientifically-based risk assessments of cytostatic drug mixtures in occupational as well as environmental settings.
- Measuring DNA modifications with the comet assay: a compendium of protocolsPublication . Collins, Andrew; Møller, Peter; Gajski, Goran; Vodenková, Soňa; Abdulwahed, Abdulhadi; Anderson, Diana; Bankoglu, Ezgi Eyluel; Bonassi, Stefano; Boutet-Robinet, Elisa; Brunborg, Gunnar; Chao, Christy; Cooke, Marcus S.; Costa, Carla; Costa, Solange; Dhawan, Alok; de Lapuente, Joaquin; Bo’, Cristian Del; Dubus, Julien; Dusinska, Maria; Duthie, Susan J.; Yamani, Naouale El; Engelward, Bevin; Gaivão, Isabel; Giovannelli, Lisa; Godschalk, Roger; Guilherme, Sofia; Gutzkow, Kristine B.; Habas, Khaled; Hernández, Alba; Herrero, Oscar; Isidori, Marina; Jha, Awadhesh N.; Knasmüller, Siegfried; Kooter, Ingeborg M.; Koppen, Gudrun; Kruszewski, Marcin; Ladeira, Carina; Laffon, Blanca; Larramendy, Marcelo; Hégarat, Ludovic Le; Lewies, Angélique; Lewinska, Anna; Liwszyc, Guillermo E.; de Cerain, Adela López; Manjanatha, Mugimane; Marcos, Ricard; Milić, Mirta; de Andrade, Vanessa Moraes; Moretti, Massimo; Muruzabal, Damian; Novak, Matjaž; Oliveira, Rui; Olsen, Ann-Karin; Owiti, Norah; Pacheco, Mário; Pandey, Alok K.; Pfuhler, Stefan; Pourrut, Bertrand; Reisinger, Kerstin; Rojas, Emilio; Rundén-Pran, Elise; Sanz-Serrano, Julen; Shaposhnikov, Sergey; Sipinen, Ville; Smeets, Karen; Stopper, Helga; Teixeira, João Paulo; Valdiglesias, Vanessa; Valverde, Mahara; van Acker, Frederique; van Schooten, Frederik-Jan; Vasquez, Marie; Wentzel, Johannes F.; Wnuk, Maciej; Wouters, Annelies; Žegura, Bojana; Zikmund, Tomas; Langie, Sabine A. S.; Azqueta, AmayaThe comet assay is a versatile method to detect nuclear DNA damage in individual eukaryotic cells, from yeast to humans. The types of damage detected encompass DNA strand breaks and alkali-labile sites (e.g., apurinic/apyrimidinic sites), alkylated and oxidized nucleobases, DNA-DNA crosslinks, UV-induced cyclobutane pyrimidine dimers, some chemically induced DNA adducts. Depending on the specimen type, there are important modifications to the comet assay protocol to avoid the formation of additional DNA damage during the processing of samples and to ensure sufficient sensitivity to detect differences in damage levels between sample groups. Various applications of the comet assay have been validated by research groups in academia, industry, and regulatory agencies, and its strengths are highlighted by the adoption of the comet assay as an in vivo test for genotoxicity in animal organs by the Organisation for Economic Co-operation and Development. The present document includes a series of consensus protocols that describe the application of the comet assay to a wide variety of cell types, species, and types of DNA damage, thereby demonstrating its versatility.
- The comet assay as a tool in human biomonitoring studies of environmental and occupational exposure to chemicals: a systematic scoping reviewPublication . Ladeira, Carina; Møller, Peter; Giovannelli, Lisa; Gajski, Goran; Haveric, Anja; Bankoglu, Ezgi Eyluel; Azqueta, Amaya; Gerić, Marko; Stopper, Helga; Cabêda, José; Tonin, Fernanda; Collins, AndrewBiomonitoring of human populations exposed to chemical substances that can act as potential mutagens or carcinogens may enable the detection of damage and early disease prevention. In recent years, the comet assay has become an important tool for assessing DNA damage, both in environmental and occupational exposure contexts. To evidence the role of the comet assay in human biomonitoring, we have analysed original research studies of environmental or occupational exposure that used the comet assay in their assessments, following the PRISMA-ScR method (preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews). Groups of chemicals were designated according to a broad classification, and the results obtained from over 300 original studies (n = 123 on air pollutants, n = 14 on anaesthetics, n = 18 on antineoplastic drugs, n = 57 on heavy metals, n = 59 on pesticides, and n = 49 on solvents) showed overall higher values of DNA strand breaks in the exposed subjects in comparison with the unexposed. In summary, our systematic scoping review strengthens the relevance of the use of the comet assay in assessing DNA damage in human biomonitoring studies.
- The comet assay in animal models: from bugs to whales (Part 1: invertebrates)Publication . Gajski, Goran; Žegura, Bojana; Ladeira, Carina; Pourrut, Bertrand; Del Bo’, Cristian; Novak, Matjaž; Sramkova, Monika; Milić, Mirta; Gutzkow, Kristine Bjerve; Costa, Solange; Dusinska, Maria; Brunborg, Gunnar; Collins, AndrewThe comet assay, also called single cell gel electrophoresis, is a sensitive, rapid and low-cost technique for quantifying and analyzing DNA damage and repair at the level of individual cells. The assay itself can be applied on virtually any cell type derived from different organs and tissues of eukaryotic organisms. Although it is mainly used on human cells, the assay has applications also in the evaluation of DNA damage in yeast, plant and animal cells. Therefore, the purpose of this review is to give an extensive overview of the usage of the comet assay in animal models from invertebrates to vertebrates, covering both terrestrial and water biota. The comet assay is used in a variety of invertebrate species since they are regarded as interesting subjects in ecotoxicological research due to their significance in ecosystems. Hence, the first part of the review (Part 1) will discuss the application of the comet assay in invertebrates covering protozoans, platyhelminthes, planarians, cnidarians, mollusks, annelids, arthropods, and echinoderms. Besides a large number of animal species, the assay is also performed on a variety of cells, which includes haemolymph, gills, digestive gland, sperm and embryo cells. The mentioned cells have been used for the evaluation of a broad spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of invertebrate models and their role from an ecotoxicological point of view will also be discussed as well as the comparison of the use of the comet assay in invertebrate and human models. Since the comet assay is still developing, its increasing potential in assessing DNA damage in animal models is crucial especially in the field of ecotoxicology and biomonitoring at the level of different species, not only humans.
- The comet assay in animal models: from bugs to whales (Part 2: vertebrates)Publication . Gajski, Goran; Žegura, Bojana; Ladeira, Carina; Novak, Matjaž; Sramkova, Monika; Pourrut, Bertrand; Del Bo’, Cristian; Milić, Mirta; Gutzkow, Kristine Bjerve; Costa, Solange; Dusinska, Maria; Brunborg, Gunnar; Collins, AndrewThe comet assay has become one of the methods of choice for the evaluation and measurement of DNA damage. It is sensitive, quick to perform and relatively affordable for the evaluation of DNA damage and repair at the level of individual cells. The comet assay can be applied to virtually any cell type derived from different organs and tissues. Even though the comet assay is predominantly used on human cells, the application of the assay for the evaluation of DNA damage in yeast, plant and animal cells is also quite high, especially in terms of biomonitoring. The present extensive overview on the usage of the comet assay in animal models will cover both terrestrial and water environments. The first part of the review was focused on studies describing the comet assay applied in invertebrates. The second part of the review, (Part 2) will discuss the application of the comet assay in vertebrates covering cyclostomata, fishes, amphibians, reptiles, birds and mammals, in addition to chordates that are regarded as a transitional form towards vertebrates. Besides numerous vertebrate species, the assay is also performed on a range of cells, which includes blood, liver, kidney, brain, gill, bone marrow and sperm cells. These cells are readily used for the evaluation of a wide spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of vertebrate models and their role in environmental biomonitoring will also be discussed as well as the comparison of the use of the comet assay in vertebrate and human models in line with ethical principles. Although the comet assay in vertebrates is most commonly used in laboratory animals such as mice, rats, and lately zebrafish, this paper will only briefly review its use regarding laboratory animal models and rather give special emphasis to the increasing usage of the assay in domestic and wildlife animals as well as in various ecotoxicological studies.
- The genotoxicity of an organic solvent mixture: a human biomonitoring study and translation of a real-scenario exposure to in vitroPublication . Ladeira, Carina; Gajski, Goran; Meneses, Márcia; Gerić, Marko; Viegas, SusanaThis study aimed to evaluate occupational exposure to a styrene and xylene mixture through environmental exposure assessment and identify the potential genotoxic effects through biological monitoring. Secondly, we also exposed human peripheral blood cells in vitro to both xylene and styrene either alone or in a mixture at concentrations found in occupational settings in order to understand their mechanism of action. The results obtained by air monitoring were below the occupational exposure limits for both substances. All biomarkers of effect, except for nucleoplasmic bridges, had higher mean values in workers (N = 17) compared to the corresponding controls (N = 17). There were statistically significant associations between exposed individuals and the presence of nuclear buds and oxidative damage. As for in vitro results, there was no significant influence on primary DNA damage in blood cells as evaluated by the comet assay. On the contrary, we did observe a significant increase of micronuclei and nuclear buds, but not nucleoplasmic bridges upon in vitro exposure. Taken together, both styrene and xylene have the potential to induce genomic instability either alone or in combination, showing higher effects when combined. The obtained data suggested that thresholds for individual chemicals might be insufficient for ensuring the protection of human health.