Chemical Modification of Direct and Bystander Effects Induced by Radiation and Laser Light

In April 2006, 20 years have passed since the explosion of the fourth block fo the Chernoby nuclear power plant (CNPP). This accident affected millions of people, and large territories were contaminated by radionuclides. As a result, background radiation levels increased, and people from contaminated territories are living constantly in low dose radiation conditions. The aim of this study was to assess the direct and bystander effects from low level y-radiation and from serum samples from CNPP accident victims on human blood lymphocytes and keratinocytes in vitro. The possibility to modify these effects using radioprotective substances was also investigated. Bystander effects induced by laser radiation was also studied. The results have shown that melanin, melatonin and a-tocopherol were able to decrease direct and bystander radiation effects. Melatonin showed the best protective effect, whereas a-tocopheror showed the least proctection. Serum samples from people affected by the Chernobyl accident, even 20 years after the accident, could induce micronuclie formation and decrease the viability of human keratinocytes. A direct correlation was shown between the frequency of aberrations in human peripheral blood lymphocytes from victims of the Chernobyl accident and the level of bystander factors in their blood serum. The most affected group were the Chernobyl liquidators, who were exposed to the highest radiation doses. Radioprotective substances were not able to protect cells from these bystander factors. In general, the present study has aided in our understanding of the nature of bystander effects

СПЕКТРОМЕТР ДЛЯ ИЗМЕРЕНИЯ АКТИВНОСТИ ГАММА-ИЗЛУЧАЮЩИХ РАДИОНУКЛИДОВ В ЛЕГКИХ ВЗРОСЛОГО ЧЕЛОВЕКА. Часть 1. РЕЗУЛЬТАТЫ ЭКСПЕРИМЕНТАЛЬНЫХ И ТЕОРЕТИЧЕСКИХ ИССЛЕДОВАНИЙ

Description of whole body counter AT1316A (WBC) is presented. Main stages of experimental and theoretical researches of metrological parameters of the WBC and its results are presented. Possibility of using of the mathematical phantom of the adult human lungs for determination the WBC response function to gamma-emitting nuclides 51Cr, 54Mn, 59Fe, 58Co, 60Co, 65Zn, 95Nb, 95Zr, 103Ru, 110mAg, 124Sb, 141Ce and 144Ce is shown.Представлено описание спектрометра излучения человека СКГ-АТ1316А. Изложены основные результаты экспериментальных и теоретических исследований метрологических параметров спектрометра. Показана возможность использования математического фантома легких человека для определения функции отклика СКГАТ1316А к гамма-излучающим радионуклидам 51Cr, 54Mn, 59Fe, 58Co, 60Co, 65Zn, 95Nb, 95Zr, 103Ru, 110mAg, 124Sb, 141Ce и 144Ce

Health insurance for foreigners

Bakalářská práce se zaměřuje na zdravotní pojištění cizinců v České republice s důrazem na monopol PVZP v letech 2021-2023. Analýza hodnotí dopady tohoto monopolu na dostupnost a kvalitu zdravotního pojištění pro cizince. Hlavním cílem je zhodnotit účinnost a vliv monopolu na trhu zdravotního pojištění, s důrazem na poslední novely v legislativě. Výsledky naznačují, že i přes zavedení monopolu nebyly otázky týkající se pojištění cizinců úplně vyřešeny; nicméně, po novém legislativním zásahu se situace významně zlepšila.This bachelor's thesis focuses on the health insurance of foreigners in the Czech Republic, with an emphasis on the PVZP monopoly from 2021 to 2023. The analysis evaluates the impact of this monopoly on the accessibility and quality of health insurance for foreigners. The main objective is to assess the effectiveness and influence of the monopoly in the health insurance market, emphasizing recent legislative changes. The results suggest that despite the introduction of the monopoly, issues related to health insurance for foreigners were not fully resolved; however, the situation significantly improved after recent legislative interventions

Влияние плотности почвы и характера распределения радионуклидов ¹³⁴Cs и ¹³⁷Cs по профилю при in situ измерениях

Periodic radiation monitoring of soils today is a priority task not only for Belarus, but also for Japan, suffered by Fukushima nuclear power plant accident. Use of portable and light spectrometers with ability to perform in situ measurements makes it possible to quickly estimate specific activity of measured radionuclides with required accuracy in particular soil site. Basic information of a gamma radiation source (radionuclides content, effective radius of measurement area and thickness of contaminated layer) can be obtained directly during measurement. The purpose of this research is to test the feasibility of using algorithms for determination of specific activity and thickness of contaminated layer under conditions of soil measurement with variable density parameters and radiocesium distribution in soil. Monte-Carlo simulating allowed to estimate the degree of deviation of the shape of simulated spectra obtained with the use of Monte-Carlo soil model with uniformly distributed radionuclide in it, and for the case when the radionuclide distribution by soil profile can be described by an exponential function. For these cases of natural distribution of radiocesium, the pulse-amplitude spectrum is formed by an effective thickness of the contaminated site, which contains more than 90 % of radionuclides. The developed Monte-Carlo model of a probe and contaminated soil site allows to estimate the effect of the variability of soil density on the total count rate of the pulse-amplitude spectrum. As a result of theoretical estimations, the relationship between the effective radius of contaminated site is determined as a function of soil density. Analysis of the influence of radial zones of the cylindrical gamma source on in situ gamma-spectrometer showed that the main contribution to the total count rate of the pulse-amplitude spectrum is made by the radial zone with radius of up to 40 cm from the center of the probe, regardless of the thickness of the contaminated layer in geometry «Probe is located on the soil surface». A small site facilitates the selection of measurement area of land with a sufficiently flat surface, which is desirable during surveying the territories, especially with complex terrain

Влияние плотности почвы и характера распределения радионуклидов ¹³⁴Cs и ¹³⁷Cs по профилю при in situ измерениях

Periodic radiation monitoring of soils today is a priority task not only for Belarus, but also for Japan, suffered by Fukushima nuclear power plant accident. Use of portable and light spectrometers with ability to perform in situ measurements makes it possible to quickly estimate specific activity of measured radionuclides with required accuracy in particular soil site. Basic information of a gamma radiation source (radionuclides content, effective radius of measurement area and thickness of contaminated layer) can be obtained directly during measurement. The purpose of this research is to test the feasibility of using algorithms for determination of specific activity and thickness of contaminated layer under conditions of soil measurement with variable density parameters and radiocesium distribution in soil. Monte-Carlo simulating allowed to estimate the degree of deviation of the shape of simulated spectra obtained with the use of Monte-Carlo soil model with uniformly distributed radionuclide in it, and for the case when the radionuclide distribution by soil profile can be described by an exponential function. For these cases of natural distribution of radiocesium, the pulse-amplitude spectrum is formed by an effective thickness of the contaminated site, which contains more than 90 % of radionuclides. The developed Monte-Carlo model of a probe and contaminated soil site allows to estimate the effect of the variability of soil density on the total count rate of the pulse-amplitude spectrum. As a result of theoretical estimations, the relationship between the effective radius of contaminated site is determined as a function of soil density. Analysis of the influence of radial zones of the cylindrical gamma source on in situ gamma-spectrometer showed that the main contribution to the total count rate of the pulse-amplitude spectrum is made by the radial zone with radius of up to 40 cm from the center of the probe, regardless of the thickness of the contaminated layer in geometry «Probe is located on the soil surface». A small site facilitates the selection of measurement area of land with a sufficiently flat surface, which is desirable during surveying the territories, especially with complex terrain

The Bioavailability and Biological Activities of Phytosterols as Modulators of Cholesterol Metabolism

Phytosterols are natural sterols widely found in plants that have a variety of physiological functions, and their role in reducing cholesterol absorption has garnered much attention. Although the bioavailability of phytosterols is only 0.5–2%, they can still promote cholesterol balance in the body. A mechanism of phytosterols for lowering cholesterol has now been proposed. They not only reduce the uptake of cholesterol in the intestinal lumen and affect its transport, but also regulate the metabolism of cholesterol in the liver. In addition, phytosterols can significantly reduce the plasma concentration of total cholesterol, triglycerides, and low-density lipoprotein cholesterol (LDL-C), with a dose-response relationship. Ingestion of 3 g of phytosterols per day can reach the platform period, and this dose can reduce LDL-C by about 10.7%. On the other hand, phytosterols can also activate the liver X receptor α-CPY7A1 mediated bile acids excretion pathway and accelerate the transformation and metabolism of cholesterol. This article reviews the research progress of phytosterols as a molecular regulator of cholesterol and the mechanism of action for this pharmacological effect