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Author: Andrew R Collins (111)


Dec
1969

Vitamin D deficiency is reportedly common, but we lack data from young adults. Such data are of interest because epidemiological data support vitamin D as a possible risk modulator for diabetes and cardiovascular ('cardiometabolic') disease. Our objectives were to assess vitamin D status (as plasma 25(OH)D concentration) and investigate associations between this and biomarkers of cardiometabolic disease risk in a group of still-healthy young adults in Hong Kong.

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Oct
2017

The human eye is relatively unexplored as a source of cells for investigating DNA damage. There have been some clinical studies, using cells from surgically removed tissues, and altered DNA bases as well as strand breaks have been measured using the comet assay. Tissues examined include corneal epithelium and endothelium, lens capsule, iris and retinal pigment epithelium.

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Oct
2017

Among several factors affecting radiation sensitivity, genome size has received limited attention during the last 50 years since research at Brookhaven National Laboratory (USA) and other locations demonstrated substantial differences in radiation sensitivities, e.g. between tree species with large (e.

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Jul
2017

Vitamin D deficiency (plasma 25-hydroxycholecalciferol (25(OH)D)70 % of participants were vitamin D deficient. No significant correlations and no biomarker differences across 25(OH)D quartiles or groups were seen except for total antioxidant status. A weak direct association (r 0·252, P<0·05) was observed between 25(OH)D and FRAP, and those in the lowest 25(OH)D quartile and group had significantly lower FRAP values.

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Dec
1969

The comet assay is a sensitive electrophoretic method for measuring DNA breaks at the level of single cells, used widely in genotoxicity experiments, in biomonitoring, and in fundamental research. Its sensitivity and range of application are increased by the incorporation of an extra step, after lysis of agarose-embedded cells, in which the DNA is digested with lesion-specific endonucleases (DNA repair enzymes of bacterial or phage origin). Enzymes with specificity for oxidized purines, oxidized pyrimidines, alkylated bases, UV-induced cyclobutane pyrimidine dimers, and misincorporated uracil have been employed.

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May
2017

The International Comet Assay Workshops are a series of scientific conferences dealing with practical and theoretical aspects of the Comet Assay (single-cell gel electrophoresis)-a simple method for detecting DNA strand breaks. The first paper describing such an assay was published over 30 years ago in 1984 by Swedish researchers O. Ostling and K.

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Dec
1969

There is serious concern about the potential harmful effects of certain nanomaterials (NMs), on account of their ability to penetrate cell membranes and the increased reactivity that results from their increased surface area compared with bulk chemicals. To assess the safety of NMs, reliable tests are needed. We have investigated the possible genotoxicity of four representative NMs, derived from titanium dioxide, zinc oxide, cerium oxide and silver, in two human cell lines, A549 alveolar epithelial cells and lymphoblastoid TK6 cells.

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Jan
2017

The aim of this study was to investigate the impact of dyes on DNA before and after enzymatic decolorization by acidic horseradish peroxidase (HRP-A). The comet assay is easy and feasible method widely used to measure DNA damage and repair. The medium-throughput comet assay was employed for assessment of genotoxic effects of 8 dyes in BEAS-2B cells.

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Dec
1969

Oxidation-induced damage to DNA can cause mutations, phenotypic changes and apoptosis. Agents that oppose such damage offer potential therapies for disease prevention. Vitamin D administration reportedly lowered DNA damage in type 2 diabetic mice, and higher DNA damage was reported in mononuclear cells of severely asthmatic patients who were vitamin D deficient.

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Dec
1969

With the growing numbers of nanomaterials (NMs), there is a great demand for rapid and reliable ways of testing NM safety-preferably using in vitro approaches, to avoid the ethical dilemmas associated with animal research. Data are needed for developing intelligent testing strategies for risk assessment of NMs, based on grouping and read-across approaches. The adoption of high throughput screening (HTS) and high content analysis (HCA) for NM toxicity testing allows the testing of numerous materials at different concentrations and on different types of cells, reduces the effect of inter-experimental variation, and makes substantial savings in time and cost.

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Dec
1969

In classic Hairy cell leukaemia (HCLc), a single case has thus far been interrogated by whole exome sequencing (WES) in a treatment naive patient, in which BRAF V(600)E was identified as an acquired somatic mutation and confirmed as occurring near-universally in this form of disease by conventional PCR-based cohort screens. It left open however the question whether other genome-wide mutations may also commonly occur at high frequency in presentation HCLc disease. To address this, we have carried out WES of 5 such typical HCLc cases, using highly purified splenic tumour cells paired with autologous T cells for germline.

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Dec
2015

Designing a broad-spectrum integrative approach for cancer prevention and treatment.

Semin Cancer Biol 2015 Dec;35 Suppl:S276-S304
Keith I Block, Charlotte Gyllenhaal, Leroy Lowe, Amedeo Amedei, A R M Ruhul Amin, Amr Amin, Katia Aquilano, Jack Arbiser, Alexandra Arreola, Alla Arzumanyan, S Salman Ashraf, Asfar S Azmi, Fabian Benencia, Dipita Bhakta, Alan Bilsland, Anupam Bishayee, Stacy W Blain, Penny B Block, Chandra S Boosani, Thomas E Carey, Amancio Carnero, Marianeve Carotenuto, Stephanie C Casey, Mrinmay Chakrabarti, Rupesh Chaturvedi, Georgia Zhuo Chen, Helen Chen, Sophie Chen, Yi Charlie Chen, Beom K Choi, Maria Rosa Ciriolo, Helen M Coley, Andrew R Collins, Marisa Connell, Sarah Crawford, Colleen S Curran, Charlotta Dabrosin, Giovanna Damia, Santanu Dasgupta, Ralph J DeBerardinis, William K Decker, Punita Dhawan, Anna Mae E Diehl, Jin-Tang Dong, Q Ping Dou, Janice E Drew, Eyad Elkord, Bassel El-Rayes, Mark A Feitelson, Dean W Felsher, Lynnette R Ferguson, Carmela Fimognari, Gary L Firestone, Christian Frezza, Hiromasa Fujii, Mark M Fuster, Daniele Generali, Alexandros G Georgakilas, Frank Gieseler, Michael Gilbertson, Michelle F Green, Brendan Grue, Gunjan Guha, Dorota Halicka, William G Helferich, Petr Heneberg, Patricia Hentosh, Matthew D Hirschey, Lorne J Hofseth, Randall F Holcombe, Kanya Honoki, Hsue-Yin Hsu, Gloria S Huang, Lasse D Jensen, Wen G Jiang, Lee W Jones, Phillip A Karpowicz, W Nicol Keith, Sid P Kerkar, Gazala N Khan, Mahin Khatami, Young H Ko, Omer Kucuk, Rob J Kulathinal, Nagi B Kumar, Byoung S Kwon, Anne Le, Michael A Lea, Ho-Young Lee, Terry Lichtor, Liang-Tzung Lin, Jason W Locasale, Bal L Lokeshwar, Valter D Longo, Costas A Lyssiotis, Karen L MacKenzie, Meenakshi Malhotra, Maria Marino, Maria L Martinez-Chantar, Ander Matheu, Christopher Maxwell, Eoin McDonnell, Alan K Meeker, Mahya Mehrmohamadi, Kapil Mehta, Gregory A Michelotti, Ramzi M Mohammad, Sulma I Mohammed, D James Morre, Vinayak Muralidhar, Irfana Muqbil, Michael P Murphy, Ganji Purnachandra Nagaraju, Rita Nahta, Elena Niccolai, Somaira Nowsheen, Carolina Panis, Francesco Pantano, Virginia R Parslow, Graham Pawelec, Peter L Pedersen, Brad Poore, Deepak Poudyal, Satya Prakash, Mark Prince, Lizzia Raffaghello, Jeffrey C Rathmell, W Kimryn Rathmell, Swapan K Ray, Jörg Reichrath, Sarallah Rezazadeh, Domenico Ribatti, Luigi Ricciardiello, R Brooks Robey, Francis Rodier, H P Vasantha Rupasinghe, Gian Luigi Russo, Elizabeth P Ryan, Abbas K Samadi, Isidro Sanchez-Garcia, Andrew J Sanders, Daniele Santini, Malancha Sarkar, Tetsuro Sasada, Neeraj K Saxena, Rodney E Shackelford, H M C Shantha Kumara, Dipali Sharma, Dong M Shin, David Sidransky, Markus David Siegelin, Emanuela Signori, Neetu Singh, Sharanya Sivanand, Daniel Sliva, Carl Smythe, Carmela Spagnuolo, Diana M Stafforini, John Stagg, Pochi R Subbarayan, Tabetha Sundin, Wamidh H Talib, Sarah K Thompson, Phuoc T Tran, Hendrik Ungefroren, Matthew G Vander Heiden, Vasundara Venkateswaran, Dass S Vinay, Panagiotis J Vlachostergios, Zongwei Wang, Kathryn E Wellen, Richard L Whelan, Eddy S Yang, Huanjie Yang, Xujuan Yang, Paul Yaswen, Clement Yedjou, Xin Yin, Jiyue Zhu, Massimo Zollo
Targeted therapies and the consequent adoption of "personalized" oncology have achieved notable successes in some cancers; however, significant problems remain with this approach. Many targeted therapies are highly toxic, costs are extremely high, and most patients experience relapse after a few disease-free months. Relapses arise from genetic heterogeneity in tumors, which harbor therapy-resistant immortalized cells that have adopted alternate and compensatory pathways (i.

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Jun
2015

Genome instability is a prerequisite for the development of cancer. It occurs when genome maintenance systems fail to safeguard the genome's integrity, whether as a consequence of inherited defects or induced via exposure to environmental agents (chemicals, biological agents and radiation). Thus, genome instability can be defined as an enhanced tendency for the genome to acquire mutations; ranging from changes to the nucleotide sequence to chromosomal gain, rearrangements or loss.

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Jun
2015

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead.

Carcinogenesis 2015 Jun;36 Suppl 1:S254-96
William H Goodson, Leroy Lowe, David O Carpenter, Michael Gilbertson, Abdul Manaf Ali, Adela Lopez de Cerain Salsamendi, Ahmed Lasfar, Amancio Carnero, Amaya Azqueta, Amedeo Amedei, Amelia K Charles, Andrew R Collins, Andrew Ward, Anna C Salzberg, Annamaria Colacci, Ann-Karin Olsen, Arthur Berg, Barry J Barclay, Binhua P Zhou, Carmen Blanco-Aparicio, Carolyn J Baglole, Chenfang Dong, Chiara Mondello, Chia-Wen Hsu, Christian C Naus, Clement Yedjou, Colleen S Curran, Dale W Laird, Daniel C Koch, Danielle J Carlin, Dean W Felsher, Debasish Roy, Dustin G Brown, Edward Ratovitski, Elizabeth P Ryan, Emanuela Corsini, Emilio Rojas, Eun-Yi Moon, Ezio Laconi, Fabio Marongiu, Fahd Al-Mulla, Ferdinando Chiaradonna, Firouz Darroudi, Francis L Martin, Frederik J Van Schooten, Gary S Goldberg, Gerard Wagemaker, Gladys N Nangami, Gloria M Calaf, Graeme Williams, Gregory T Wolf, Gudrun Koppen, Gunnar Brunborg, H Kim Lyerly, Harini Krishnan, Hasiah Ab Hamid, Hemad Yasaei, Hideko Sone, Hiroshi Kondoh, Hosni K Salem, Hsue-Yin Hsu, Hyun Ho Park, Igor Koturbash, Isabelle R Miousse, A Ivana Scovassi, James E Klaunig, Jan Vondráček, Jayadev Raju, Jesse Roman, John Pierce Wise, Jonathan R Whitfield, Jordan Woodrick, Joseph A Christopher, Josiah Ochieng, Juan Fernando Martinez-Leal, Judith Weisz, Julia Kravchenko, Jun Sun, Kalan R Prudhomme, Kannan Badri Narayanan, Karine A Cohen-Solal, Kim Moorwood, Laetitia Gonzalez, Laura Soucek, Le Jian, Leandro S D'Abronzo, Liang-Tzung Lin, Lin Li, Linda Gulliver, Lisa J McCawley, Lorenzo Memeo, Louis Vermeulen, Luc Leyns, Luoping Zhang, Mahara Valverde, Mahin Khatami, Maria Fiammetta Romano, Marion Chapellier, Marc A Williams, Mark Wade, Masoud H Manjili, Matilde E Lleonart, Menghang Xia, Michael J Gonzalez, Michalis V Karamouzis, Micheline Kirsch-Volders, Monica Vaccari, Nancy B Kuemmerle, Neetu Singh, Nichola Cruickshanks, Nicole Kleinstreuer, Nik van Larebeke, Nuzhat Ahmed, Olugbemiga Ogunkua, P K Krishnakumar, Pankaj Vadgama, Paola A Marignani, Paramita M Ghosh, Patricia Ostrosky-Wegman, Patricia A Thompson, Paul Dent, Petr Heneberg, Philippa Darbre, Po Sing Leung, Pratima Nangia-Makker, Qiang Shawn Cheng, R Brooks Robey, Rabeah Al-Temaimi, Rabindra Roy, Rafaela Andrade-Vieira, Ranjeet K Sinha, Rekha Mehta, Renza Vento, Riccardo Di Fiore, Richard Ponce-Cusi, Rita Dornetshuber-Fleiss, Rita Nahta, Robert C Castellino, Roberta Palorini, Roslida Abd Hamid, Sabine A S Langie, Sakina E Eltom, Samira A Brooks, Sandra Ryeom, Sandra S Wise, Sarah N Bay, Shelley A Harris, Silvana Papagerakis, Simona Romano, Sofia Pavanello, Staffan Eriksson, Stefano Forte, Stephanie C Casey, Sudjit Luanpitpong, Tae-Jin Lee, Takemi Otsuki, Tao Chen, Thierry Massfelder, Thomas Sanderson, Tiziana Guarnieri, Tove Hultman, Valérian Dormoy, Valerie Odero-Marah, Venkata Sabbisetti, Veronique Maguer-Satta, W Kimryn Rathmell, Wilhelm Engström, William K Decker, William H Bisson, Yon Rojanasakul, Yunus Luqmani, Zhenbang Chen, Zhiwei Hu
Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis.

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Jul
2015

Consumption of cruciferous vegetables may protect against colorectal cancer. Cruciferous vegetables are rich in a number of bioactive constituents including polyphenols, vitamins and glucosinolates. Before consumption, cruciferous vegetables often undergo some form of processing that reduces their content of bioactive constituents and may determine whether they exert protective effects.

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Sep
2015

In the context of reducing CO2 emissions to the atmosphere, chemical absorption with amines is emerging as the most advanced technology for post-combustion CO2 capture from exhaust gases of fossil fuel power plants. Despite amine solvent recycling during the capture process, degradation products are formed and released into the environment, among them aliphatic nitramines, for which the environmental impact is unknown. In this study, we determined the acute and chronic toxicity of two nitramines identified as important transformation products of amine-based carbon capture, dimethylnitramine and ethanolnitramine, using a multi-trophic suite of bioassays.

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May
2015

As a part of the 6th IWGT, an expert working group on the comet assay evaluated critical topics related to the use of the in vivo comet assay in regulatory genotoxicity testing. The areas covered were: identification of the domain of applicability and regulatory acceptance, identification of critical parameters of the protocol and attempts to standardize the assay, experience with combination and integration with other in vivo studies, demonstration of laboratory proficiency, sensitivity and power of the protocol used, use of different tissues, freezing of samples, and choice of appropriate measures of cytotoxicity. The standard protocol detects various types of DNA lesions but it does not detect all types of DNA damage.

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May
2015

Nanogenotoxicity is a crucial endpoint in safety testing of nanomaterials as it addresses potential mutagenicity, which has implications for risks of both genetic disease and carcinogenesis. Within the NanoTEST project, we investigated the genotoxic potential of well-characterised nanoparticles (NPs): titanium dioxide (TiO2) NPs of nominal size 20 nm, iron oxide (8 nm) both uncoated (U-Fe3O4) and oleic acid coated (OC-Fe3O4), rhodamine-labelled amorphous silica 25 (Fl-25 SiO2) and 50 nm (Fl-50 SiO) and polylactic glycolic acid polyethylene oxide polymeric NPs - as well as Endorem® as a negative control for detection of strand breaks and oxidised DNA lesions with the alkaline comet assay. Using primary cells and cell lines derived from blood (human lymphocytes and lymphoblastoid TK6 cells), vascular/central nervous system (human endothelial human cerebral endothelial cells), liver (rat hepatocytes and Kupffer cells), kidney (monkey Cos-1 and human HEK293 cells), lung (human bronchial 16HBE14o cells) and placenta (human BeWo b30), we were interested in which in vitro cell model is sufficient to detect positive (genotoxic) and negative (non-genotoxic) responses.

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Dec
2015

Genomic instability can initiate cancer, augment progression, and influence the overall prognosis of the affected patient. Genomic instability arises from many different pathways, such as telomere damage, centrosome amplification, epigenetic modifications, and DNA damage from endogenous and exogenous sources, and can be perpetuating, or limiting, through the induction of mutations or aneuploidy, both enabling and catastrophic. Many cancer treatments induce DNA damage to impair cell division on a global scale but it is accepted that personalized treatments, those that are tailored to the particular patient and type of cancer, must also be developed.

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Dec
1969

The DNA in eukaryotic cells is organized into loop domains that represent basic structural and functional units of chromatin packaging. The comet assay, a sensitive method for monitoring DNA damage and repair, involves electrophoresis of nucleoids comprising supercoiled DNA attached to the nuclear matrix. Breaks in the DNA relax the supercoiling and allow DNA loops to expand, and on electrophoresis to move towards the anode, giving the appearance of a comet tail.

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Mar
2015

Disturbed epigenetic mechanisms, which developmentally regulate gene expression via modifications to DNA, histone proteins, and chromatin, have been hypothesized to play a key role in many human diseases. Recently it was shown that engineered nanoparticles (NPs), that already have a wide range of applications in various fields including food production, could dramatically affect epigenetic processes, while their ability to induce diseases remains poorly understood. Besides the obvious benefits of the new technologies, it is critical to assess their health effects before proceeding with industrial production.

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Jan
2015

Green tea has many reported health benefits, including genoprotective and antioxidant effects, but green tea has pro-oxidant activity in vitro. A tea-induced pro-oxidant shift that triggers cytoprotective adaptations has been postulated, but human data are lacking. We investigated effects on oxidation-induced DNA damage and redox-linked cytoprotective factors, including 8-oxoguanine glycosylase (hOGG1) and heme oxygenase 1 (HMOX-1) in lymphocytes in a randomised, placebo-controlled, cross-over supplementation trial.

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Jan
2015

The comet assay is widely used to test the genotoxicity of engineered nanomaterials (ENMs) but outcomes may vary when results from different laboratories, or even within one laboratory, are compared. We address some basic methodological considerations, such as the importance of carrying out physico-chemical characterisation of the ENMs in test-medium, performing uptake and cytotoxicity tests, and testing several genotoxicity-related endpoints. In this commentary, we discuss the different ways in which concentration of ENMs can be expressed, and stress the need to include appropriate controls and reference standards to monitor variation and avoid interference.

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Jan
2015

The effects of low-dose radiation causing DNA damage continue to be subjects of interest. Problems with existing approaches to low-dose DNA damage are that single-strand breaks (the predominant radiation-induced lesion) are very rapidly repaired and that results using current methods for measuring DNA damage can be difficult to interpret. As a novel approach, we conducted studies using plants (rye grass and the model plant Arabidopsis) exposed to X-rays and used the alkaline comet assay to measure DNA damage and repair after exposures.

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Jan
2015

The contributions to this special issue of Mutagenesis have been selected to cover the main research areas served by the comet assay, namely genotoxicology, environmental toxicology, human biomonitoring and fundamental investigations into mechanisms of DNA damage and repair. Innovative methods are described, technical issues are explored, and guidelines are given for venturing into relatively new or unexploited areas of research. The popularity of the comet assay in a historical context is illustrated by a bibliometric survey.

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Mar
2015

The comet assay is a sensitive method to detect DNA strand breaks as well as oxidatively damaged DNA at the level of single cells. Today the assay is commonly used in nano-genotoxicology. In this review we critically discuss possible interactions between nanoparticles (NPs) and the comet assay.

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Dec
1969

The comet assay is a sensitive and versatile method for assessing DNA damage in cells. In the traditional version of the assay, there are many manual steps involved and few samples can be treated in one experiment. High throughput (HT) modifications have been developed during recent years, and they are reviewed and discussed.

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Dec
1969

Variability of the comet assay is a serious issue, whether it occurs from experiment to experiment in the same laboratory, or between different laboratories analysing identical samples. Do we have to live with high variability, just because the comet assay is a biological assay rather than analytical chemistry? Numerous attempts have been made to limit variability by standardizing the assay protocol, and the critical steps in the assay have been identified; agarose concentration, duration of alkaline incubation, and electrophoresis conditions (time, temperature, and voltage gradient) are particularly important. Even when these are controlled, variation seems to be inevitable.

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Jun
2014

Age‐related DNA damage is regarded as one of the possible explanations of aging. Although a generalized idea about the accumulation of DNA damage with age exists, results found in the literature are inconsistent. To better understand the question of age‐related DNA damage in humans and to identify possible moderator variables, a metaanalysis was conducted.

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Dec
1969

Thousands of DNA lesions are estimated to occur in each cell every day and almost all are recognized and repaired. DNA repair is an essential system that prevents accumulation of mutations which can lead to serious cellular malfunctions. Phenotypic evaluation of DNA repair activity of individuals is a relatively new approach.

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Jul
2014

This study investigated the levels of DNA strand breaks and formamidopyrimidine DNA glycosylase (FPG) sensitive sites, as assessed by the comet assay, in peripheral blood mononuclear cells (PBMC) from healthy women from five different countries in Europe. The laboratory in each country (referred to as 'centre') collected and cryopreserved PBMC samples from three donors, using a standardised cell isolation protocol. The samples were analysed in 13 different laboratories for DNA damage, which is measured by the comet assay.

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Apr
2014

The interplay between dietary habits and individual genetic make-up is assumed to influence risk of cancer, via modulation of DNA integrity. Our aim was to characterize internal and external factors that underlie inter-individual variability in DNA damage and repair and to identify dietary habits beneficial for maintaining DNA integrity. Habitual diet was estimated in 340 healthy individuals using a food frequency questionnaire and biomarkers of antioxidant status were quantified in fasting blood samples.

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Apr
2014

Preservation of human blood cells for DNA damage analysis with the comet assay conventionally involves the isolation of mononuclear cells by centrifugation, suspension in freezing medium and slow freezing to -80 °C-a laborious process. A recent publication (Al-Salmani et al. Free Rad Biol Med 2011; 51: 719-725) describes a simple method in which small volumes of whole blood are frozen to -20 or -80 °C; on subsequent thawing, the comet assay is performed, with no indication of elevated DNA strand breakage resulting from the rapid freezing.

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Nov
2013

There is an increasing demand for phenotyping assays in the field of human functional genetics. DNA repair activity is representative of this functional approach, being seen as a valuable biomarker related to cancer risk. Repair activity is evaluated by incubating a cell extract with a DNA substrate containing lesions specific for the DNA repair pathway of interest.

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May
2015

Therapeutic nanoparticles (NPs) are used in nanomedicine as drug carriers or imaging agents, providing increased selectivity/specificity for diseased tissues. The first NPs in nanomedicine were developed for increasing the efficacy of known drugs displaying dose-limiting toxicity and poor bioavailability and for enhancing disease detection. Nanotechnologies have gained much interest owing to their huge potential for applications in industry and medicine.

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Mar
2014

The aim of this study was to determine if the differences observed in the levels of DNA damage in a group of patients suffering from chronic renal failure are due to differences in the repair capability. DNA damage was initially measured with the comet assay in 106 hemodialysis patients. A selected group of 21 patients representing high (ten patients) and low (11 patients) levels of DNA damage were obtained for determination of base excision repair capacity.

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Sep
2013

The measurement of DNA-repair activity by extracts from cells or tissues by means of the single-cell gel electrophoresis (comet) assay has a high potential to become widely used in biomonitoring studies. We assessed the inter-laboratory variation in reported values of DNA-repair activity on substrate cells that had been incubated with Ro19-8022 plus light to generate oxidatively damaged DNA. Eight laboratories assessed the DNA-repair activity of three cell lines (i.

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Aug
2013

While oxidative damage owing to reactive oxygen species (ROS) often increases with advancing age and is associated with many age-related diseases, its causative role in ageing is controversial. In particular, studies that have attempted to modulate ROS-induced damage, either upwards or downwards, using antioxidant or genetic approaches, generally do not show a predictable effect on lifespan. Here, we investigated whether dietary supplementation with either vitamin E (α-tocopherol) or vitamin C (ascorbic acid) affected oxidative damage and lifespan in short-tailed field voles, Microtus agrestis.

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Jun
2013

The comet assay (single cell gel electrophoresis) is the most common method for measuring DNA damage in eukaryotic cells or disaggregated tissues. The assay depends on the relaxation of supercoiled DNA in agarose-embedded nucleoids (the residual bodies remaining after lysis of cells with detergent and high salt), which allows the DNA to be drawn out towards the anode under electrophoresis, forming comet-like images as seen under fluorescence microscopy. The relative amount of DNA in the comet tail indicates DNA break frequency.

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Jul
2013

DNA damage is commonly measured at the level of individual cells using the so-called comet assay (single-cell gel electrophoresis). As the frequency of DNA breaks increases, so does the fraction of the DNA extending towards the anode, forming the comet tail. Comets with almost all DNA in the tail are often referred to as 'hedgehog' comets and are widely assumed to represent apoptotic cells.

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Feb
2014

To distinguish between contributions to dementia made by homocysteine, folate, B12 and antioxidant micronutrients.
This is a follow-up study of a sample reported in 2002. Homocysteine was measured at baseline in 201 individuals born in 1921 and without dementia at age 77 years and followed up to age 88 years.

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Feb
2014

Measuring oxidative damage to DNA and its repair with the comet assay.

Biochim Biophys Acta 2014 Feb 22;1840(2):794-800. Epub 2013 Apr 22.
Andrew R Collins
Single cell gel electrophoresis, or the comet assay, was devised as a sensitive method for detecting DNA strand breaks, at the level of individual cells. A simple modification, incorporating a digestion of DNA with a lesion-specific endonuclease, makes it possible to measure oxidised bases.
With the inclusion of formamidopyrimidine DNA glycosylase to recognise oxidised purines, or Nth (endonuclease III) to detect oxidised pyrimidines, the comet assay has been used extensively in human biomonitoring to monitor oxidative stress, usually in peripheral blood mononuclear cells.

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Apr
2013

Dietary antioxidants, including vitamin C, may be in part responsible for the cancer-preventive effects of fruits and vegetables. Human intervention trials with clinical endpoints have failed to confirm their protective effects, and mechanistic studies have given inconsistent results. Our aim was to investigate antioxidant/ pro-oxidant effects of vitamin C at the cellular level.

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May
2013

The single-cell gel electrophoresis--the comet assay--has proved to be a sensitive and relatively simple method that is much used in research for the analysis of specific types of DNA damage, and its use in genotoxicity testing is increasing. The efficiency of the comet assay, in terms of number of samples processed per experiment, has been rather poor, and both research and toxicological testing should profit from an increased throughput. We have designed and validated a format involving 96 agarose minigels supported by a hydrophilic polyester film.

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Dec
1969

Kiwifruit are a rich source of vitamin C and other antioxidants. We have demonstrated the capacity of kiwifruit to protect cellular DNA against oxidative damage in single-dose human experiments and in longer term supplementation trials using the comet assay to measure both DNA-strand breaks and oxidized bases. Enhanced antioxidant status following a single large dose of kiwifruit is shown by an increased resistance of lymphocyte DNA to oxidation by H(2)O(2)in vitro.

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Jul
2013

O(6)-methylguanine (O(6)meG) is one of the most premutagenic, precarcinogenic, and precytotoxic DNA lesions formed by alkylating agents. Repair of this DNA damage is achieved by the protein MGMT, which transfers the alkyl groups from the O(6) position of guanine to a cysteine residue in its active center. Because O(6)meG repair by MGMT is a stoichiometric reaction that irreversibly inactivates MGMT, which is subsequently degraded, the repair capacity of O(6)meG lesions is dependent on existing active MGMT molecules.

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Mar
2013

A serious limitation of the conventional comet assay (single cell gel electrophoresis) is the restriction on the number of samples that can be processed in one experiment, imposed by the size of the electrophoresis platform. One approach to increasing throughput is to reduce the size of gels. We here compare the conventional system of two large gels on a microscope slide, with two recent developments, namely 12 minigels per slide, and a format with 96 minigels on GelBond® film.

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Nov
2013

DNA damage has been described in the human cataractous lens epithelium, and oxidative stress generated by UV radiation and endogenous metabolic processes has been suggested to play a significant role in the pathogenesis of cataract. In this study, the aim was to explore the quality and relative quantity of DNA damage in lens epithelium of cataract patients in vivo and after incubation in a cell culture system.
Capsulotomy specimens were analysed, before and after 1 week of ex vivo cultivation, using the comet assay to measure DNA strand breaks, oxidized purine and pyrimidine bases and UV-induced cyclobutane pyrimidine dimers.

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