117 research outputs found
Real-time detection of Fe·EDTA/H2O2-induced DNA cleavage by linear dichroism
The conditions for the measurement of linear dichroism (LD) can be adjusted so as to solely reflect the length and the flexibility of DNA. The real-time detection of the EDTA·Fe2+-induced oxidative cleavage of double-stranded native and synthetic DNAs was performed using LD. The decrease in the magnitude of the LD at 260 nm, which reflects an increase in the flexibility and a decrease in the length of the DNA, can be described by the sum of two or three exponential curves in relation to the EDTA·Fe2+ concentration. The fast component was assigned to the cleavage of one of the double strands, inducing an increase in the flexibility, while the other slower component was assigned to the cleavage of the double strand, resulting in the shortening of DNA. The decrease in the magnitude of the LD of poly[d(A-T)2] was similar to that of poly[d(I-C)2], while that of poly[d(G-C)2] was found to be the slowest, indicating that the resistance of poly[d(G-C)2] against the Fenton-type reagent was the strongest. This observation suggests that the amine group in the minor groove of the double helix may play an important role in slowing the EDTA·Fe2+-induced oxidative cleavage
Reactive Molecular Dynamics study on the first steps of DNA-damage by free hydroxyl radicals
We employ a large scale molecular simulation based on bond-order ReaxFF to
simulate the chemical reaction and study the damage to a large fragment of
DNA-molecule in the solution by ionizing radiation. We illustrate that the
randomly distributed clusters of diatomic OH-radicals that are primary products
of megavoltage ionizing radiation in water-based systems are the main source of
hydrogen-abstraction as well as formation of carbonyl- and hydroxyl-groups in
the sugar-moiety that create holes in the sugar-rings. These holes grow up
slowly between DNA-bases and DNA-backbone and the damage collectively propagate
to DNA single and double strand break.Comment: 6 pages and 8 figures. movies and simulations are available at:
http://qmsimulator.wordpress.com
The Efficacy of Energy-Restricted Diets in Achieving Preoperative Weight Loss for bariatric Pateints: A Systematic Review
The final publication is available at Springer via https://doi.org/10.1007/s11695-018-3451-1In bariatric practice, a preoperative weight loss of at least 5% is recommended. However, the hypocaloric diets prescribed vary
and no consensus exists. This study examined the efficacy of preoperative diets in achieving 5% weight loss. From a systematic
literature search, eight randomised controlled trials (n = 862) were identified. Half of the trials used a Bvery-low-calorie diet^
whilst the rest employed a Blow-calorie diet^. Only five diets achieved ≥ 5% weight loss over varying durations and energy
intakes. By inference, compliance with a 700–1050 kcal (2929–4393 kJ) diet, consisting of moderate carbohydrate, high protein
and low/moderate fat, for 3 weeks is likely to achieve 5% weight loss. A low-carbohydrate diet (< 20 g/day) may achieve this
target within a shorter duration. Additional research is required to validate these conclusions
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