Abstract
Purpose
To investigate the protective effect of oral Vitamin C on DNA double-strand breaks (DSBs) after abdominal contrast-enhanced CT examination.
Materials and methods
Sixty patients undergoing abdominal multiphase contrast-enhanced CT were divided into control group (n = 30) and prevention group (n = 30). Patients in the prevention group were orally administered 1 g Vitamin C 30–120 minutes prior to CT examination. Blood samples were obtained prior to and 5 min following CT examination for each subject. γ-H2AX foci representing DSBs in the nucleus of lymphocytes were marked by fluorescent markers. Change in γ-H2AX foci/cell was compared through Student t-tests or ANOVA testing. The relationship between physical parameters and increase in γ-H2AX foci was analyzed through Pearson or Spearman correlation analysis.
Results
The mean increase in γ-H2AX was 0.49 foci /cell in the control group and 0.19 foci/cell in the prevention group (p < 0.001), corresponding to a 61% reduction in the mean increase in γ-H2AX foci in the prevention group compared to the control group. In the prevention group, increase in γ-H2AX foci/cell positively correlated with dose length product and volume CT dose index (r = 0.449 and 0.403, respectively; both p < 0.05). No difference in the increase in γ-H2AX foci/cell was found between the different time interval subgroups of 30, 60, and 120 min between Vitamin C administration and CT examination (p > 0.05).
Conclusion
Oral Vitamin C can significantly reduce the level of DSBs after abdominal contrast-enhanced CT examination and is a simple and effective method to decrease DNA damage.
Introduction
Computed Tomography (CT) is a frequently used imaging modality in current medical practice, however, widespread use of CT technique contributes to an overall increase of medical radiation exposure. One study in the UK indicates that about 0.6% of the cumulative risk of cancer to age 75 years could be attributable to diagnostic X-rays, while in 13 other developed countries estimates that the attributable risk ranged from 0.6% to 1.8% [1]. Although elaborate techniques have been developed for CT to achieve radiation dose reduction, including low tube voltage and high pitch, prospective electrocardiogram (ECG) gating or iterative algorithms which have successfully resulted in a substantial reduction of radiation dose in chest and abdominal contrast-enhanced CT [[2], [3], [4]], the radiation exposure induced cancer risk still remains an issue of major concern due to the stochastic effect of X-ray-based radiation exposure.
In general, the radiation exposure associated with CT is widely monitored by various physical or chemical dosimeters [5,6]. However, these methods are limited in that they are only able to determine the radiation exposure at a reference position outside the body, and are unable to assess the actual radiation dose deposited in the body. This radiation exposure has the potential to induce many kinds of deoxyribonucleic acid (DNA) damage, among which DNA double strand breaks (DSBs) are the most serious consequence, and if not efficiently repaired may result in carcinogenesis [7,8]. DSBs are the most readily accessible and hence most frequently investigated DNA change used to gauge the biological effect of radiation exposure [[9], [10], [11]], with phosphorylation of the histone variant H2AX as one of the earliest steps in the cellular response following DSBs induction [12].
The protective effect of antioxidants against radiation damage has been previously postulated [[12], [13], [14]]. However, most of these published studies have been in vitro, and clinical studies evaluating the protective effect of antioxidants against CT radiation exposure are rare. Recently, one in vivo human study showed the protective effect of Vitamin C and N-acetylcysteine during cardiac intervention [15]. However, the patients included in this study were under x-ray-based cardiac DSA examinations in which the radiation dose was much higher than that of state-of-the-art CT examination. Further, this study relied on the intravenous infusion of antioxidants prior to cardiac intervention, which may be difficult to apply in the routine clinical practice, especially the outpatient setting. Thus, it is necessary to investigate a simpler and more effective method to obtain a similar efficacy. Oral Vitamin C has been used in clinical practice for the prevention of contrast-induced acute kidney injury and other conditions [16,17]; however, whether prophylactic use of oral Vitamin C demonstrates protective effects against CT radiation exposure remains unknown. Hence, the purpose of this study was to investigate the protective effect of oral Vitamin C on DSBs after abdominal contrast-enhanced CT.
Section snippets
Patient population
Patients were prospectively enrolled at Jinling Hospital and written informed consent was obtained from all patients. This study was approved by the institutional review board of Jinling Hospital. Sixty patients referred for abdominal multiphase contrast-enhanced CT were eligible from March 1 2017 to March 31, 2017. Avoiding food and water 6 h prior to CT examination was required. Exclusion criteria consisted of contraindications to iodinated contrast material, severe kidney disease (estimated
Patient characteristics and γ-H2AX foci baseline distribution
Sixty patients were included in this study; the detailed demographic characteristics of the patients are shown in Table 1. In the control group, the mean DLP was 1358.7 mGy*cm ± 330.6 (range, 636–2300 mGy*cm) and the mean CTDIvol was 30.5 mGy ± 7.3 (range, 14.4–48.3 mGy). In the prevention group, the mean DLP was 1423.1 mGy*cm ± 357.2 (range, 904.0–2220 mGy*cm) and the mean CTDIvol was 30.4 mGy ± 7.0 (range, 20.2–45.7 mGy). There was no significant difference in DLP and CTDIvol between two
Discussion
This study investigated the protective effect of orally administered Vitamin C on DNA double-strand breaks after abdominal contrast-enhanced CT. The results showed that oral administration of 1 g Vitamin C before CT examination has the potential to significantly reduce the increase DNA double-strand breaks levels in human peripheral blood lymphocyte, in our study this reduction was approximately 61%.
Our study did not show an optimal time interval between oral administration of Vitamin C and CT
Conflict of interest
All authors have no conflict of interest to disclose.
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source: https://www.sciencedirect.com/science/article/abs/pii/S0720048X19301986
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