Radioprotective combination of α-tocopherol and ascorbic acid promotes apoptosis that is evident by release of low-molecular weight DNA fragments into circulation

Vitamins and Radioprotective Effect: A Review

The radioprotective effect ex vivo, in vitro and in vivo of vitamins was reviewed using PubMed and Embase and conducted according to the PRISMA statement. A total of 38 articles were included in this review, which includes the radioprotective effect of vitamins from ex vivo, in vitro and in vivo studies. Vitamins A, C, D and E were used alone, in combination or with other nutritional and non-nutritional compounds. The use of vitamins in natural form or supplementation can be useful to reduce the radiation effect in the body, organs and/or cells. Only four (A, C, D and E) out of thirteen vitamins have been detected with radioprotective properties being mainly vitamin E followed by vitamin C, A and D.

Saving normal tissues - a goal for the ages

Almost since the earliest utilization of ionizing radiation, many within the radiation community have worked toward either preventing (i.e. protecting) normal tissues from unwanted radiation injury or rescuing them from the downstream consequences of exposure. However, despite over a century of such investigations, only incremental gains have been made toward this goal and, with certainty, no outright panacea having been found. In celebration of the 60th anniversary of the International Journal of Radiation Biology and to chronicle the efforts that have been made to date, we undertook a non-rigorous survey of the articles published by normal tissue researchers in this area, using those that have appeared in the aforementioned journal as a road map. Three 'snapshots' of publications on normal tissue countermeasures were taken: the earliest (1959-1963) and most recent (2013-2018) 5-year of issues, as well as a 5-year intermediate span (1987-1991). Limiting the survey solely to articles appearing within International Journal of Radiation Biology likely reduced the number of translational studies interrogated given the basic science tenor of this particular publication. In addition, by taking 'snapshots' rather than considering the entire breadth of the journal's history in this field, important papers that were published during the interim periods were omitted, for which we apologize. Nonetheless, since the journal's inception, we observed that, during the chosen periods, the majority of studies undertaken in the field of normal tissue countermeasures, whether investigating radiation protectants, mitigators or treatments, have focused on agents that interfere with the physical, chemical and/or biological effects known to occur during the acute period following whole body/high single dose exposures. This relatively narrow approach to the reduction of normal tissue effects, especially those that can take months, if not years, to develop, seems to contradict our growing understanding of the progressive complexities of the microenvironmental disruption that follows the initial radiation injury. Given the analytical tools now at our disposal and the enormous benefits that may be reaped in terms of improving patient outcomes, as well as the potential for offering countermeasures to those affected by accidental or mass casualty exposures, it appears time to broaden our approaches to developing normal tissue countermeasures. We have no doubt that the contributors and readership of the International Journal of Radiation Biology will continue to contribute to this effort for the foreseeable future.

Cell-Free DNA Plasma Levels Differ in Age-Specific Pattern in Healthy Rats and Castrates with Testosterone-Induced Benign Prostatic Hyperplasia

The purpose of this work was to study changes in the level of cell-free DNA (cfDNA) in the blood of young and old rats in the normal state and with induced benign prostatic hyperplasia (BPH). Male Wistar rats were divided into 4 groups-young (3 months), old (20 months), intact, or with testosterone-induced BPH. Groups with BPH were subjected to surgical castration and administration of testosterone esters at a dose of 25 mg/kg for a total of 7 injections for 20 days. In intact animals, the level of cfDNA in old rats (2.00 ± 0.14 ng/μl) was significantly higher than that in the young (1.02 ± 0.30 ng/μl). The body and the prostate weights of old rats were 1.6 and 1.4 times larger than those of the young, without an increase in the prostate index (PI). The testosterone level in the blood of young rats was 1.6 times higher than that of old (6.20 ± 0.93 nmol/l vs. 3.77 ± 0.55 nmol/l; NS). In animals with BPH, the level of cfDNA in old rats (3.14 ± 0.76 ng/μl) was significantly higher than that in young rats (0.80 ± 0.14 ng/μl). The body and the prostate weights in old rats were 1.8 and 2.3 times larger, than those in young rats, with an increase in the PI. The level of testosterone in the blood of young (15.76 ± 0.51 nmol/l) and old (16.99 ± 1.1 nmol/l) rats was not significantly different. Morphological signs of BPH were observed in the prostate of both young and old rats. During the induction of BPH in the experiment, according to the level of cfDNA, cell death processes have not changed significantly in young rats but significantly increased in old rats. A similar trend was observed in the group of intact animals. The obtained data indicate that apoptosis processes are enhanced during the development of BPH despite the growth of tissues in the prostate itself.

The Effects of Low-Frequency Noise on Rats: Evidence of Chromosomal Aberrations in the Bone Marrow Cells and the Release of Low-Molecular-Weight DNA in the Blood Plasma

Objectives:

Evaluation of the effect of low-frequency noise (LFN) on the frequency of chromosomal aberrations in the bone marrow cells and on the content of low-molecular-weight DNA (lmwDNA) in the blood plasma of rats.

Materials and Methods:

A total of 96 male Wistar rats were exposed to either single (17 min session) or multiple (17 min session repeated five times a week for 13 weeks) LFN, with the maximum range below 250 Hz and the sound pressure levels (SPLs) at 120 and 150 dB, respectively. The rats in the control groups were not subjected to any impact. The frequency of chromosomal aberrations in the bone marrow cells and the levels of lmwDNA in the blood plasma were measured afterwards.

Results:

It has been detected that a single LFN exposure with either corresponding SPLs had a significant increase in the frequency of chromosomal aberrations (more than 10-fold) compared to the controls (0.9 ± 0.3%) and resulted in the appearance of dicentric chromosomes in the aberration spectrum, both of which are evident for the occurrence of deoxyribonucleic acid double strand breaks triggered by the exposure. Furthermore, the lmwDNA levels in the blood plasma measured the following day after a single LFN exposure were significantly higher (7.7- and 7.6-fold, respectively) than that in the control group (11.0 ± 5.4 ng/ml), and such levels were maintained higher (4.8- and 2.1-fold, respectively) in the week after a single LFN exposure for the SPL of 120 and 150 dB, respectively, compared to the control group (18.8 ± 1.6 ng/ml). Similar results were obtained from the group with multiple LFN exposures (36.4- and 22.4-fold, respectively) compared to the control (17.7 ± 1.7 ng/ml) and suggest the enhancement of cellular apoptosis as a result of the LFN impact.

Conclusion:

Presumably, the LFN may have possible mutagenic effects and cause massive cell death.

[Plasma low-molecular-weight DNA in patients with chronic obstructive pulmonary disease]

AIM

To determine plasma extracellular low-molecular-weight DNA (elmwDNA) as an indicator of apoptosis in patients with chronic obstructive pulmonary disease (COPD) in remission versus healthy donors, patients with chronic non-obstructive bronchitis (CNOB), and their first-degree relatives (FDRs).

SUBJECTS AND METHODS

The investigation recruited 110 participants, including 17 healthy donors, 31 patients with COPD, and 20 patients with CNOB in remission, 19 healthy FDRs of patients with COPD, and 23 healthy FDRs of those with SNOB. The plasma levels of elmwDNA were determined in the study participants. Nucleic acids were isolated by phenol/chloroform extraction, precipitated with ethanol, and treated with RNase; elmwDNA was analyzed by electrophoresis.

RESULTS

In patients with COPD, the mean level of elmwDNA was 7.8±2.0 ng/ml, which was 3.9 and 3.0 times statistically significantly lower than that in healthy donors and patients with SNOB, respectively; while the level of elmwDNA in the latter did not differ statistically significantly from that in healthy donors. In both the blood relatives of patients with COPD and FDRs of those with SNOB, the mean level of elmwDNA was not significantly different from that in healthy donors. The content of elmwDNA tended to increase in COPD patients aged 60-80 years as compared to those aged 45-59 years; that in both age groups was, however, significantly lower than in healthy donors of the same age.

CONCLUSION

The level of elmwDNA in plasma and, accordingly, apoptosis in the lung are reduced in patients with COPD in remission, whereas that is unchanged in those with SNOB. In patients with COPD, blood elmwDNA release is unrelated to heredity and varies little with age. The determination of elmwDNA is recommended for use in patients with COPD to assess apoptosis.

Comparative Analysis of Harmful Physical Factors Effect on the Cell Genome

Exposure to either to low-frequency noise or ionizing radiation causes an increase in the number of chromosomal aberrations in the bone marrow cells and the level of low-molecular-weight DNA in the blood plasma of experimental animals. The dynamics of the content of low-molecular-weight DNA increasing after exposure to low-frequency noise and ionizing radiation differs significantly. Both exposures are able to provide a direct damaging effect on DNA.