Effect of N-acetylcysteine on (12)C(6+) ion irradiation-induced lymphocytes DNA damages and immunity changes in mice

Novel Indications for Commonly Used Medications as Radiation Protectants in Spaceflight

BACKGROUND

In the space environment, the traditional radioprotective principles of time, distance, and shielding become difficult to implement. Additionally, the complex radiation environment inherent in space, the chronic exposure timeframe, and the presence of numerous confounding variables complicate the process of creating appropriate risk models for astronaut exposure. Pharmaceutical options hold tremendous promise to attenuate acute and late effects of radiation exposure in the astronaut population. Pharmaceuticals currently approved for other indications may also offer radiation protection, modulation, or mitigation properties along with a well-established safety profile. Currently there are only three agents which have been clinically approved to be employed for radiation exposure, and these only for very narrow indications. This review identifies a number of agents currently approved by the U.S. Food and Drug Administration (FDA) which could warrant further investigation for use in astronauts. Specifically, we examine preclinical and clinical evidence for statins, nonsteroidal anti-inflammatory drugs (NSAIDs), angiotensin converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), metformin, calcium channel blockers, β adrenergic receptor blockers, fingolimod, N-acetylcysteine, and pentoxifylline as potential radiation countermeasures.McLaughlin MF, Donoviel DB, Jones JA. Novel indications for commonly used medications as radiation protectants in spaceflight. Aerosp Med Hum Perform. 2017; 88(7):665-676.

Effects of carbon-ion beam or X-ray irradiation on anti-apoptosis ΔNp73 expression in HeLa cells

ΔNp73 has emerged as an interesting novel factor in cancer research. Here, we report the effect of carbon-ion beams on ΔNp73 expression in human cervix carcinoma HeLa cells in contrast to the effect of X-rays. Cellular sensitivities were determined by colony formation. Radiation-induced cell cycle arrest was investigated with flow cytometry. Additionally, radiation-induced apoptosis was analyzed with flow cytometry and Hoechst staining. Furthermore, ΔNp73 expression was examined by semi-quantitative reverse transcription-PCR (semi-quantitative RT-PCR) as well as by Western blot analysis. Following irradiation, stronger G2/M phase arrest, more significant increase in apoptosis and more pronounced ΔNp73 degradation were observed after exposure to high-LET carbon beams in comparison with X-rays at 4 Gy doses. These observations indicate that there is a differential ΔNp73 expression in response to different LET radiations, and down-regulated ΔNp73 expression might play a critical role in promoting cycle arrest and apoptosis in cancer cells. This study highlights the potential of ΔNp73 in radiotherapy.

N-acetyl-cysteine improves anastomotic wound healing after radiotherapy in rats

AIM

This study was designed to determine the effects of intraperitoneally or orally administered N-acetylcysteine (NAC) on anastomotic healing of irradiated rats.

METHODS

Thirty-two male Wistar albino rats were randomized into four groups containing 8 rats each: I; standard resection plus anastomosis, II; radiation plus standard resection plus anastomosis, III; radiation plus standard resection plus anastomosis plus oral NAC, IV; radiation plus standard resection plus anastomosis plus intraperitoneal NAC. Four types of assessment were performed: bursting pressure, hydroxiproline (OHP) content, histopathology, and biochemical evaluation, including serum malondialdehyde (MDA), advanced oxidation protein products (AOPP), reduced glutathione (GSH) and superoxide dismutase (SOD) activities.

RESULTS

Group comparisons demonstrated that bursting pressure was significantly higher in NAC treated rats. The mean tissue OHP concentration in the anastomotic tissue was significantly lower in irradiated rats (group II) than in the other groups. NAC treatment caused increased activity of SOD and GSH. In contrast, MDA levels were found to be decreased in groups III and IV. Histopathological analysis revealed that NAC administration, either orally or intraperitoneally, leads to a better anastomotic healing in terms of reepithelialization, perianastomotic fibrosis, ischemic necrosis, and muscle layer destruction.

CONCLUSION

The present study supports the hypothesis that NAC administration alleviates the negative effects of radiotherapy on anastomotic healing. Nevertheless, the underlying mechanisms responsible for this protective effect is unknown today.

Heavy ions, radioprotectors and genomic instability: implications for human space exploration

The risk associated with space radiation exposure is unique from terrestrial radiation exposures due to differences in radiation quality, including linear energy transfer (LET). Both high- and low-LET radiations are capable of inducing genomic instability in mammalian cells, and this instability is thought to be a driving force underlying radiation carcinogenesis. Unfortunately, during space exploration, flight crews cannot entirely avoid radiation exposure. As a result, chemical and biological countermeasures will be an important component of successful extended missions such as the exploration of Mars. There are currently several radioprotective agents (radioprotectors) in use; however, scientists continue to search for ideal radioprotective compounds-safe to use and effective in preventing and/or reducing acute and delayed effects of irradiation. This review discusses the agents that are currently available or being evaluated for their potential as radioprotectors. Further, this review discusses some implications of radioprotection for the induction and/or propagation of genomic instability in the progeny of irradiated cells.