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Procedural recommendations are made for a radiation safety assessment of the environment as well as the results of their approval based on monitoring of the radiation situation for nuclear facilities are presented. Changes in the radioecological situation are identified and assessed in relation to the existing radiation background and the biota irradiation dose rate and control levels of radionuclides in the natural environment, determined on the basis of environmental criteria, are given. An integral assessment of the radioecological situation is performed using a generalized metric that takes into account the spatial scale, duration, and intensity of the radiation exposure. The proposed metrics can be considered as basic for making assessments of the environmental radiation risk of nuclear facilities and standardizing the quality of the environment based on the level of the activity of radionuclides.

Methodology for the ecological regulation of environmental quality by radioactivity levels is presented. Reference levels of radionuclides in surface waters and soil are determined to ensure the radiation safety of ecosystems. The developed criteria were tested using the data of long-term (2000-2018) radiation monitoring in the observation areas of nuclear power facilities like radiochemical plants, nuclear power plants with VVER, RBMK, and BN reactors. It is shown that the activity of the considered nuclear power facilities did not lead to the exceeding of ecologically safe levels of radionuclides in environmental components during the study period.

The emissions from Russian NPP in 2011–2017, which, on the whole, taking the specifics of nuclear reactors into consideration, correspond to the global emissions, are analyzed. The public irradiation dose due to NPP emissions is estimated to be 0.01–0.1% of the dose due to natural background radiation. It is shown that the location of fixed stations for monitoring the radioactivity of the surface air layer and atmospheric fallout near NPP meets the requirements of Russian regulatory documents and IAEA recommendations. The volume activity of 137Cs, 60Co, and other technogenic radionuclides in the surface air layer in the NPP observation zones are 104–108 times lower than the volumetric activity admissible for the public. To improve the monitoring of the radiation conditions, the 14C and 3H present in the emissions from NPP must be monitored, and collection of atmospheric fallout at fixed observation stations near NPP must be more efficient.

The aim of the study was to conduct a radioecological assessment of the Leningrad NPP marine cooling reservoir – Koporye Bay of the Gulf of Finland. According to the international basic safety standards, accepted at the IAEA General Conference, this issue is of particular relevance due to the need to justify protection from technogenic radiation exposure both to humans and the environment. The assessment was based on the long-term radioecological monitoring data (1973–2019) within the Leningrad NPP observation area: radionuclides concentration in seawater, bottom sediments, and hydrobionts. The reference levels of radionuclides content in seawater and bottom sediments were used as indicators of the radiation state of the marine environment; their calculation procedure is defined in the Recommendations R 52.18.852-2016 and R 52.18.873-2018, issued by the Federal Service for Hydrometeorology and Environmental Monitoring (the Ministry of Natural Resources and Environment of the Russian Federation). These recommendations, developed by RPA “Typhoon” specialists, contain a methodology for assessing the radioecological state of the marine environment by the level of radionuclides activity, based on the principles, ensuring the maintenance of favorable environment, safety of marine hydrobionts, and radiation protection of humans. In the presence of various radionuclides in the marine environment, the sum of technogenic radionuclide activity ratios in seawater (bottom sediments) to the corresponding reference levels shall be below 1. According to monitoring data in the early period of NPP operation (1973–1985), a wide spectrum of technogenic radionuclides was observed in the marine ecosystem components. Along with 137Cs, significant contributors to the contamination of seawater and bottom sediments were 54Mn and 60Co. In contrast to reference levels for 137Cs, reference levels for 54Mn and 60Co in seawater are determined by an environmental criterion, not a radiation-hygienic one. The presence of technogenic radionuclides in algae was registered at distances, exceeding 10 km from the NPP. Biogenic transfer of corrosion radionuclides (54Mn, 60Co, and 65Zn) by fish into rivers, flowing into the Koporye Bay, was noted. The Chernobyl disaster led to a noticeable increase in the pollution of the Koporye Bay with technogenic radionuclides. In May – December 1986, the sum of technogenic radionuclide activity ratios in seawater to the reference levels exceeded the pre-accidental level by 100 times, and in bottom sediments – by 30 times. In 1986, 137Cs and 134Cs were the main contributors to the marine ecosystem radioactive contamination. Currently, the technogenic radioactivity of seawater and bottom sediments of the Koporye Bay is mainly determined by 137Cs; its level is relatively constant, which indicates the stability of the radioecological situation in the Leningrad NPP marine cooling reservoir.

Quantitative environmental criteria for the radiation protection of aquatic ecosystems, namely, reference concentrations of radionuclides in water are developed. If activity concentrations of radionuclides do not exceed these levels, aquatic biota can be considered completely protected from the negative effects of ionizing radiation. Reference concentrations of radionuclides in environmental objects can be compared directly with the measurement data on radioactive contamination parameters that allows using them for the monitoring data interpretation. Reference concentrations of anthropogenic radionuclides in the sea and fresh water are calculated using the environmental criteria and are compared to the values of reference concentrations computed using the hygienic criterion. It is demonstrated that the current levels of concentration of 90Sr, 137Cs, and tritium in the seas, rivers, and lakes of Russia are considerably lower than the values of reference concentrations of these radionuclides calculated using the environmental criterion.

Original data on radionuclide activities in air emissions of Russian NPPs are presented based on direct on-site measurements in vent stacks of NPPs during an extensive survey in 2017–2018. For the first time, the detailed inventories of radionuclides in the air releases were directly measured for all types of nuclear reactors, employed in the Russian NPPs. Based on the results of measurements, annual doses for local populations around the Russian NPPs were estimated. The technogenic radionuclides, detected in the air emissions, were ranked according to their contribution in the annual dose. 14C is the major contributor for the annual dose from the atmospheric releases of LWGR reactors – almost 98% for Bilibino NPP's EGP-6 reactor, and up to 86% for RBMK-1000 reactors (Smolensk NPP). For PWR reactors (VVER) contribution to the annual dose from atmospheric releases is formed mostly by tritium, 14C and noble gases. Estimated annual doses for local populations in the vicinity of the Russian NPPs do not exceed 10−5 Sv/year. Atmospheric releases of 60Co, 134Cs, 137Cs and other aerosols, involved in the routine monitoring programs of Russian NPPs, do not contribute significantly to the annual dose. Based on these results, 14C and tritium will be included in the monitoring programs of atmospheric release control at all Russian NPPs; maximal permissible levels of annual releases for 14C and tritium will be established since 2019.

Presented in the article is a review of the literature, analysing principles of conservative therapy of patients with obliterating diseases of lower limb arteries and most commonly used drugs to treat them, followed by discussing the mechanisms of action and efficacy of such pharmacological agents as pentoxyphyllin, cilostazol, naphthidrofuryl, aktovegin, sulodexide. Described in details are subtle mechanisms of action of sulodexide as an endothelioprotector, its clinical efficacy in intermittent claudication.

The review analyses the role of serotonin in the development of pathological processes in angiological patients, showing its negative role in aggravating chronic and acute ischaemia of various organs (brain, myocardium, extremities) both at the expense of vasoconstriction and due to an increase in blood platelet aggregation of blood platelets and erythrocytes, followed by analysis of clinical efficacy of naftidrofuryl) - serotonin 5-HT2 receptor antagonist. Results of numerous randomized trials confirmed its efficacy and safety in treatment of angiological patients, being superior to other vasotropic drugs (cilostazol, pentoxyphyllin, nicotinic acid).

Presented in the article are the results of studying antiaggregate activity of acetylsalicylic acid and clopidogrel in a total of 36 patients suffering from various-severity chronic arterial insufficiency of lower limbs on the background of atherosclerosis obliterans. The study was conducted prior to treatment for correct selection of a particular antiplatelet agent. The obtained results showed that clopidogrel was not always more efficient than acetylsalicylic acid, since there is individual sensitivity of each patients to a particular antiplatelet agent. Therefore, an individual approach is necessary to conservative therapy of arterial insufficiency of lower limbs. For some patients it is preferable to administer clopidogrel, for others - acetylsalicylic acid. In a series of cases combined treatment is justified, while some patients having low sensitivity to both acetylsalicylic acid and clopidogrel require careful selection of alternative agents influencing other thrombocyte receptors.

Presented herein are the results of treating a total of sixty patients suffering from atherosclerosis obliterans of the lower limbs with degree IV chronic ischaemia according to the Fontain-Pokrovsky classification and accompanied by pyonecrotic alterations. The patients were subdivided into two clinically matching groups, each comprising 30 subjects. All patients after two-week conservative preparation underwent various reconstructive surgical operations performed on major arteries of the lower limbs. The local preoperative treatment was of two different types, i. e. consisting of Levomecol ointment used in the control group patients and Metrogyl 1% topical gel applied in the study group patients. Sampled before treatment, inoculations of the wound discharge demonstrated predominantly anaerobic flora in all patients, with the number of bacterial strains having dramatically decreased once Metrogyl gel 1% had been used, whereas application of Levomecol did not significantly influence the structure of the microbial profile. Following surgical treatment we had to perform high amputation of the lower limb in 5 patients of the control group, whereas in the study group patients only one patient required amputation at the foot level. Hence, prior to carrying out reconstructive vascular interventions in patients presenting with pyonecrotic lesions of lower extremities it is preferable to perform debridement of the necrotic foci using topical antibacterial agents, one of which may be Metrogyl 1% gel.

The study comprised a total of 107 patients (all men) after endured femoropopliteal bypass grafting above the genicular fissure with a synthetic stent graft manufactured by the Gore Company for stage IIB and III chronic arterial insufficiency of the lower extremities according to the Fontain-Pokrovsky classification. Group One I (control group) was composed of fifty-four patients permanently taking in the postoperative period at the out-patient stage pentoxiphylline (trental 400 mg 1 tablet 3 times daily) and xantinol nicotinate at a dose of 150 mg one tablet thrice daily. Group Two (Study Group) consisted of fifty-three patients taking after reconstructive vascular surgery at the out-patient stage in addition to pentoxiphylline and xantinol nicotinate acetylsalicylic acid (cardiomagnil 75 mg 1 tablet once daily). The Control Group patients within 3 to 6 months of follow up were found to have a considerable progressing improvement of the functional abilities of the microcirculatory bed requiring in 44 (81.5%) cases hospitalization to the Surgical Department for intensive vascular therapy. Despite this fact four (7.4%) patients within the time frame from 6 to 9 months after surgery developed thrombosis of the vascular implant requiring a repeat surgical intervention. In the Study Group patients, the degree of functional capabilities of the microcirculatory bed in the postoperative period was less considerable, reaching the maximum after 10-12 months of follow up, with eighteen (34.0%) patients requiring hospitalization for additional vascular therapy to perform. There were no cases of implants' thrombosis in the Study Group patients. Pathological alterations in the functional state of the peripheral vascular bed correlated with viscosimetric indices and activity of blood platelet aggregation. The addition of antithrombocytic agents to conservative postoperative therapy considerably improved the outcomes of surgical treatment.

The present literature review pays primary attention to the pathophysiblogical and immunological grounds of the process of restenoses of vascular anastomoses after reconstructive interventions in patients with atherosclerosis obliterans. On the molecular, cellular and tissue levels, analysed herein are alterations leading to restenosis, also presenting the data concerning currently available methods of diagnosis of this pathological condition. In addition, methods aimed at preventing and treating restenoses are discussed.