National Center of Radiobiology and Radiation Protection

" " 16-18 2022 170 3 2022 . () 01.07.2022 . 30.06.2023 . (https://www.iybssd2022.org/en/home/

The exposure to radon in buildings open to the public and at workplaces depends on many factors, for example, forms of utilization, construction conditions, time of exposure, heating, and ventilation conditions, etc. To evaluate the radon exposure in different working environments, continuous simultaneous measurements of radon (CRn), equilibrium equivalent (EEC), and potential alpha energy (PAEC) concentrations for 24 hours were performed using AlphaE for CRn and DOSEman PRO from SARAD GmbH for EEC and PAEC measurements. The study considered measurements at three locations in the radon-rich spa of Narechen, Asenovgrad, and at an old mine turned museum in the town of Pernik. A comparison was made between the average values of the concentrations relating to all-day and only working hours when the measurements were completed. The CRn increases during the working hours in the museum as well as in the bath of the spa, while it decreases in the spa’s treatment room. On the other hand, the EEC and PAEC are increasing at all locations. The concentrations increasing due to working hours, which are integrated into long-term measurements can cause underestimated radon exposures in radon reach working environment.

Natural radon (222Rn) is a radioactive noble gas that occurs as the immediate decay product of radium (226Ra), part of the 238U family, in the lithosphere. Radon is driven by advection and diffusion with soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. The aim of the present study is to do a review of the existing so far research activities in Bulgaria in connection with the observation and/or evaluation of the degree of water saturation of the near-surface layer, and on that base to distinguish the up-to-date achievements in regards to the radon potential in situ evaluation. Due to this review, the studies in Bulgaria concerning moisture dynamics in the near-surface layers can be divided mainly into two groups. The first one investigates the hydraulic characteristics (parameters) of soils in the vadose zone. Based on that, conclusions or computer simulations for the saturation degree estimation can be drawn. The other group includes in situ observations by sensors on the change of moisture with time. The results of these studies may serve as a base for more precise moisture dynamics assessment at sites with specific radon potential tendencies.

Background: There are data suggesting that low dose radiation induced inflammatory reactions and changes of the immune system could be responsible for late circulatory and other chronic diseases. Chronic low dose radiation of occupationally exposed persons requires careful examination of their immune status. The purpose of this survey was to study some immunological parameters and serum proteins as suitable markers for screening cardiovascular diseases and chronic inflammatory state in NPP personnel. Materials and Methods: Lymphocyte populations were determined using four parameters by flow cytometer. Plasma levels of interleukin IL6, CRP and INF were determined by ELISA. Results: The main T lymphocyte populations did not show any differences to controls but there were trends of increasing activated CD3 HLA, CD4+25+ and CD8+38+ T lymphocytes and CRP and IL6 markers. Higher, but not significant averages were recorded for regulatory T lymphocytes probably due to their role in preventing of atherosclerosis. No dependence was established of the studied parameters to cardiovascular or other chronic diseases, a weak correlation was only recorded for IL6 with autoimmune ones (p=0.042). The results show that the age, obesity, and other lifestyle factors, particularly cigarette smoking could be considered as cofounder for circulatory diseases.

Abstract This work aims to investigate the possible inhibitory action of β-hydroxybutyrate (βOHB) against hematological alterations and hepatic injury associated with oxidative stress caused by D-galactose or γ-irradiation in rats. Six groups of male rats were used as the control, irradiated group (5 Gy), D-galactose (150 mg/kg b.wt), β-hydroxybutyrate (72.8 mg/kg b.wt), γ-irradiation plus βOHB, and D-galactose plus βOHB. Complete blood count and glucose-6-phosphate-dehydrogenase (G6PD) activity were determined in whole-blood samples. In addition, the hepatic malondialdehyde (MDA), nitric oxide (NO), and glutathione (GSH) levels and the superoxide dismutase (SOD) activity were evaluated. Moreover, certain elements were measured in liver tissue (iron (Fe), copper (Cu), and zinc (Zn)). The G6PD activity significantly diminished post exposure to D-galactose or γ-irradiation. In the βOHB, D-galactose, or γ-irradiation groups, liver MDA levels and SOD activity were significantly increased. Meanwhile, NO and GSH levels were significantly increased relative to normal control levels in the γ-irradiation group. The findings showed that βOHB alleviated hematological alterations, enhanced the altered biochemical indices, and modulated the change in Cu, Fe, and Zn elements in D-galactose or γ-irradiation group. These results highlight the role of βOHB as a powerful protective agent against hematological alterations and liver impairment by reducing G6PD-mediated oxidative stress and controlling the measured elements.

Eighty-five uropathogen isolates were collected and differentiated on the basis of their Gram stain reaction. Among the collected isolates, 25 (29.4%) were Gram positive cocci and 60 (70.6%) were Gram negative bacilli. Antibiotic susceptibility profile towards 15 different antibiotics concluded that impenime (IMP), amikacin (AK) and Pipperacillin/tazobactam (TZP) were the most effective against Gram negative; while linezolid (LZD), and vancomycin (VA) were the most potent against Gram positive. The highly drug resistant isolates were identified as Pseudomonas aeruginosa and Klebsiella pneumoniae using 16srRNA; the two strains were subjected to different doses of gamma-radiation and the sub lethal dose of both strains was 5.0 kGy. The D10 values were recorded (1.2 and 1.1 kGy) for P. aeruginosa and K. pneumoniae), respectively. In addition, gamma-irradiation technique decreases the resistance of K. pneumoniae towards IMP and the resistance of P. aeruginosa towards more than one antibiotic (TZP, AZM and CIP). The results also, revealed that both of the tested strains had the ability to produce Extended Spectrum β-lactamase (ESBL) before and after gamma-radiation but only P. aeruginosa had the ability to produce Metallo β-lactamase (MBL), that is, ESBL and MBL co-production was detected in P. aeruginosa. So, these findings must be supported by other studies on the level of genes to prove the possibility for using gamma-irradiation technique to overcome microbial drug resistance problem. Key words: Urinary tract infection, antibiotic resistance, β-lactamases, gamma radiation.

The novelty of the present research is the synthesis of bismuth oxide nanoparticles (Bi2O3 NPs) loaded with the antifungal nystatin drug via gamma rays for increased synergistic antimicrobial potential against some pathogenic bacteria and Candida species. The full characterization of the synthesized Bi2O3 NPs-Nystatin was achieved by XRD, FT-IR, HR-TEM, and SEM/EDX mapping techniques in order to analyze the crystallinity, chemical functional groups, average particle size, morphology, and elemental structure, respectively. The antimicrobial activities of Bi2O3 NPs-Nystatin were examined against pathogenic bacteria and Candida species, including the zone of inhibition (ZOI), minimum inhibitory concentration (MIC), and antibiofilm activity. Additionally, the SEM/EDX method was performed to investigate the mode of action on the treated Candida cells. Our results revealed that Bi2O3 NPs-Nystatin possessed a well-crystallized semi-spherical shape with an average particle size of 27.97 nm. EDX elemental study of the synthesized Bi2O3 NPs-Nystatin indicated a high level of purity. Interestingly, the synthesized Bi2O3 NPs-Nystatin displayed encouraging antibacterial behavior against almost all the tested bacteria and a synergistic antifungal potential toward the investigated Candida species. Additionally, Bi2O3 NPs-Nystatin was found to be a promising antibiofilm agent, resulting in inhibition percentages of 94.15% and 84.85% against C. albicans (1) and E. coli, respectively. The present research provides a revolutionary nano-drug-based solution to address the increasing global resistance of pathogenic microbes at low concentrations, thus offering a new infectious disease treatment technique that is cost effective, eco-friendly, and works in an acceptable time frame.

Purpose:To evaluate early-stage prostate cancer (PCa) radiotherapy treatment patterns and outcomes among Ghanaian men (GM) compared with US men (USM).Materials and Methods:This retrospective study consists of 987 National Comprehensive Cancer Network low risk, favorable intermediate risk, and unfavorable intermediate risk PCa patient subgroups; GM (173) and USM (814). Differences in baseline covariates and clinical characteristics between GM and USM were analyzed using χ2 and Mann-Whitney test while Cox Proportional Hazards model was used to assess freedom from biochemical failure differences between the study groups.Results:Median follow-up for this study was 40 months. GM were diagnosed at a younger median age (64 vs. 68 y, P<0.001) with heavier unfavorable intermediate risk disease burden (32.4% vs. 19.2%) compared with USM. Significant differences were identified in median external beam radiotherapy dose (72.4 vs. 78 Gy, P<0.001); brachytherapy utilization (49.7% vs. 80.6%, P<0.001) and androgen deprivation therapy for intermediate risk disease (48.4% vs. 21.0%, P<0.001) between GM and USM, respectively. GM with low risk and favorable intermediate risk PCa were at increased risk of biochemical recurrence compared with USM with adjusted hazard ratio: 5.15 (1.27 to 20.7), P=0.02 and 4.64 (1.20 to 17.92), P=0.02, respectively.Conclusions:Compared with USM, GM with low and favorable intermediate risk PCa may experience less durable disease control following standard treatment recommendations. Results suggest differences in radiation treatment and possible inherent differences between the 2 populations. This data will aid in developing research strategies to improve treatment outcomes in GM.

In this study, temporal variations of indoor radon concentrations in Bulgaria were investigated. The radon concentrations were measured by nuclear track detectors as part of the Bulgarian National Survey, performed in the dwellings of 28 regional districts. The detectors were exposed through a year in two consecutive time periods of different lengths. For 2433 dwellings, measurements could be completed for both time periods, while for 345 dwellings they could only be completed for one of the periods. To estimate any missing radon concentrations, a temporal correction procedure was developed. This procedure, which included development of a linear correlation between the ln-transformed radon concentrations from the 9-month period [CRn(L)] and from the 3-month period [CRn(S)]. A normal distribution of the data, which is a condition for linear regression, was achieved when the ln-transformed radon concentrations were grouped by climate zone, then by regional districts, and finally by the presence/absence of a basement in the investigated building. The linear models obtained for each group showed reasonable coefficients of determination (R2 ≈ 0.50) and root mean square errors (RMSEs) of about 0.50. When these correlations were used to reconstruct radon concentrations in missing measurement periods, it turned out that the reconstructed data (for 345 dwellings) were within the 95% confidence interval of the measured data (for 2433 dwellings). The geometric means of CRn(L) and CRn(S) were 76Bq/m3 and 100Bq/m3, respectively, for 2433 dwellings, which are almost equal to those of 75Bq/m3 and 98Bq/m3, which represent the measured and reconstructed data together (for 2778 dwellings).