On the search for an intelligible comet assay descriptor

Möller, Peter; Loft, Steffen; Ersson, Clara; Koppen, Gudrun; Dušinská, Maria; Collins, Andrew

doi:10.3389/fgene.2014.00217

Cited by 34 publications

(29 citation statements)

References 23 publications

(22 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Characteristics of the participants (sample size, age, and sex), the exercise protocol (distance and intensity), assayed biomarkers, and methods of DNA quantification used were extracted by one investigator. The outcome measure, DNA damage, was expressed using multiple descriptors, and with regard to the comet assay, these were: DNA in the tail (%); DNA migration (μm) (otherwise known as tail length); tail moment (also known as olive tail moment) which is the product of tail (%) and tail length [34]. The biomarker used was 8-OHdG.…”

Section: Data Extractionmentioning

confidence: 99%

DNA Damage Following Acute Aerobic Exercise: A Systematic Review and Meta-analysis

et al. 2019

View full text Add to dashboard Cite

Background Exercise is widely recognised for its health enhancing benefits. Despite this, an overproduction of reactive oxygen and nitrogen species (RONS), outstripping antioxidant defence mechanisms, can lead to a state of (chronic) oxidative stress. DNA is a vulnerable target of RONS attack and, if left unrepaired, DNA damage may cause genetic instability. Objective This meta-analysis aimed to systematically investigate and assess the overall effect of studies reporting DNA damage following acute aerobic exercise. Methods Web of Science, PubMed, MEDLINE, EMBASE, and Scopus were searched until April 2019. Outcomes included (1) multiple time-points (TPs) of measuring DNA damage post-exercise, (2) two different quantification methods (comet assay and 8-oxo-2′-deoxyguanosine; 8-OHdG), and (3) protocols of high intensity (≥ 75% of maximum rate of oxygen consumption; VO 2-max) and long distance (≥ 42 km). Results Literature search identified 4316 non-duplicate records of which 35 studies were included in the meta-analysis. The evidence was strong, showcasing an increase in DNA damage immediately following acute aerobic exercise with a large-effect size at TP 0 (0 h) (SMD = 0.875; 95% CI 0.5, 1.25; p < 0.05). When comparing between comet assay and 8-OHdG at TP 0, a significant difference was observed only when using the comet assay. Finally, when isolating protocols of long-distance and high-intensity exercise, increased DNA damage was only observed in the latter. (SMD = 0.48; 95% CI − 0.16, 1.03; p = 0.15 and SMD = 1.18; 95% CI 0.71, 1.65; p < 0.05 respectively). Conclusions A substantial increase in DNA damage occurs immediately following acute aerobic exercise. This increase remains significant between 2 h and 1 day, but not within 5-28 days post-exercise. Such an increase was not observed in protocols of a long-distance. The relationship between exercise and DNA damage may be explained through the hormesis theory, which is somewhat one-dimensional, and thus limited. The hormesis theory describes how exercise modulates any advantageous or harmful effects mediated through RONS, by increasing DNA oxidation between the two end-points of the curve: physical inactivity and overtraining. We propose a more intricate approach to explain this relationship: a multi-dimensional model, to develop a better understanding of the complexity of the relationship between DNA integrity and exercise.

show abstract

Section: Data Extractionmentioning

confidence: 99%

DNA Damage Following Acute Aerobic Exercise: A Systematic Review and Meta-analysis

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Image analysis, based on a variety of commercial or free software systems, computes mean % tail DNA, tail moment, tail length and other more abstruse properties; most commonly used are % tail DNA and tail moment. (The issue of which parameter to use is addressed in a separate article, by Møller et al, 2014 .) Image analysis systems can be manual (i.e., comets being selected by the operator for analysis) or automated.…”

Section: Discussionmentioning

confidence: 99%

Controlling variation in the comet assay

et al. 2014

View full text Add to dashboard Cite

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. It is helpful to include in experiments reference standards, i.e., cells with a known amount of specific damage to the DNA. They can be aliquots frozen from a single large batch of cells, either untreated (negative controls) or treated with, for example, H2O2 or X-rays to induce strand breaks (positive control for the basic assay), or photosensitiser plus light to oxidize guanine (positive control for Fpg- or OGG1-sensitive sites). Reference standards are especially valuable when performing a series of experiments over a long period—for example, analysing samples of white blood cells from a large human biomonitoring trial—to check that the assay is performing consistently, and to identify anomalous results necessitating a repeat experiment. The reference values of tail intensity can also be used to iron out small variations occurring from day to day. We present examples of the use of reference standards in human trials, both within one laboratory and between different laboratories, and describe procedures that can be used to control variation.

show abstract

“…The size of the tail shows the level of DNA damage associated with cell damage. The appearance of the tail can be induced by both necrosis and apoptosis [74,90], but a characteristic for the shape of a comet in apoptotic cells is that most of the DNA moves into the comet's tail [91]. Because the evaluation of these comets can be problematic, it is mostly performed using special software for the visual comet scoring [92].…”

Section: Comet Assaymentioning

confidence: 99%

An overview of apoptosis assays detecting DNA fragmentation

2018

View full text Add to dashboard Cite

Apoptosis has been recognized as a type of programmed cell death connected with characteristic morphological and biochemical changes in cells. This programmed cell death plays an important role in the genesis of a number of physiological and pathological processes. Thus, it can be very important to detect the signs of apoptosis in a study of cellular metabolism. The present paper provides an overview of methods often being used for detecting DNA fragmentation as one of the most specific findings in apoptosis. To date, three routine assays have been developed for detecting DNA fragmentation: DNA ladder assay, TUNEL assay, and comet assay. All these methods differ in their principles for detecting DNA fragmentation. DNA ladder assay detects the characteristic "DNA ladder" pattern formed during internucleosomal cleavage of DNA. Terminal deoxynUcleotidyl transferase Nick-End Labeling (TUNEL) assay detects DNA strand breaks using terminal deoxynucleotidyl transferase catalyzing attachment of modified deoxynucleotides on the DNA strand breaks. Comet assay can be used for detecting nucleus breakdown producing single/double-strand DNA breaks. The aim of this review is to describe the present knowledge on these three methods, including optimized approaches, techniques, and limitations.

show abstract

On the search for an intelligible comet assay descriptor

Cited by 34 publications

References 23 publications

DNA Damage Following Acute Aerobic Exercise: A Systematic Review and Meta-analysis

DNA Damage Following Acute Aerobic Exercise: A Systematic Review and Meta-analysis

Controlling variation in the comet assay

An overview of apoptosis assays detecting DNA fragmentation

Contact Info

Product

Resources

About