Assessment of Agricultural Workers' Exposure Due to Crop Harvesting Operations Within the Areas Affected by Radioactive Contamination.

Implementation of field experiments took place in two sites located in the Bragin district of the Gomel region, Belarus, i.e. a field in the evacuation zone and a private plot of land in a residential area of thedistrict. The objective of the research was to study the levels of radioactive contamination of air due to the dust raised up during crop harvesting operations. Comparative dose assessment was done to assess external exposure and committed effective doses of internal exposure due to inhalation of (241)Am, (238,239+240)Pu, (137)Cs and (90)Sr by agricultural workers involved in dust-generating harvesting operations. According to the results, the dominant contributors (93-97%) to internal exposure of agricultural workers both on a private plot of land and in the area of evacuation, were the transuranic elements (241)Am and (238,239,240)Pu. In the context of the total doses received by the harvest-workers, the dominant contribution belonged to external exposure which was 2-3 orders of magnitude higher than the levels of internal exposure due to inhalation of radionuclides.

[State of hemostasis system at transurethral prostatic resection].

Hemostasis system was examined at 58 patients who underwent transurethral prostate resection due to benign prostatic hyperplasia. All the patients were divided into 2 groups: the study group where the surgery was performed under spinal anesthesia, and control - under intravenous anesthesia. The hemostasis system was examined before surgery and on 1st, 3rd and 5th day after it. It is revealed that the surgery under intravenous anesthesia is associated with increase of coagulation potential and decrease of fibrinolytic activity that is the most marked on 3rd and 5th day.

[The transfer of 90Sr and of 137Cs radionuclides in the chain of soil-fodder-animal products in the area contaminated as a consequence of the Chernobyl AES accident].

The database on 137Cs and or 90Sr transfer factors in the soil-fodder-animal products chain compiled in the framework of the project "Radioecological Consequences of the Chernobyl Accident" under the French-German Initiative was analyzed. The 137Cs transfer factors were determined into 10 fodder types for farm animals. The 137Cs and 90Sr transfer from daily diet to milk is practically independent from milk yield and season and is about 0.83% and 0.16%. 137Cs transfer factor into beef (adult animals) is about to 2.4% from the daily uptake with fodder per 1 kg meat.

[Evaluation of parameters of radionuclide transition from soil particles and plant components of the upper layer of turf to cow's milk under pasture conditions]. / Otsenka parametrov perekhoda radionuklidov iz pochvennykh chastits i rastitel'noi komponenty verkhnego sloia derniny v moloko krupnogo rogatogo skota v usloviiakh pastbishchnogo soderzhaniia.

An experiment was conducted on feeding lactating cows with soil and turf additives contaminated with both 137Cs and 90Sr of the Chernobyl origin. The radionuclides transfer coefficients (%) in the food chain were for soil additives: for 137Cs--0.02 +/- 0.006, for 90Sr--0.01 +/- 0.002; for turf additives: for 137Cs--0.02 +/- 0.005, for 90Sr--0.06 +/- 0.035. Regarding 90Sr, there is no significant tendency to higher transfer rate for the radionuclide from turf component compared to that for soil component. A contribution of soil component as well as turf component of soil was evaluated as an additional source of milk contamination while grazing cattle. It was concluded that the contribution is not pronounced at the remedial period after the accident (approximately 3% from total activity consumed with ration) and it can be rejected in cattle breeding practice. The results achieved can be used for prediction of radionuclides concentrations in milk produce in cattle breeding under industrial contamination of agricultural lands.

[Laser angioplasty technology]. / Tekhnologiia lazernoi angioplastiki.

The authors propose a laser angioplasty technology that differs in that pulse-periodic nitric N2-laser (wavelength, approximately 337 nm; power, 0.5 W; pulse energy, 5 mJ; repetition frequency, approximately 100 Hz) is used as a source of laser radiation. The technology has an environmental purity (a working nitrogen-helium mixture) and a vast resource (approximately 10(7) pulses). A conical-profile quartz fiber (focon) that can accumulate and transmit the bulk of laser energy is employed to transmit laser light.

[Evaluation of hormonal status indicators and adenylate cyclase activity in animals in the follow-up of the Chernobyl AES accident]. / Otsenka pokazatelei gormonal'nogo statusa i aktivnosti adenilattsiklazy u zhivotnykh v otdalennye sroki posle avarii na Chernobyl'skoi AES.

Enhancing stimulation effect of prostaglandin E1 on adenylate cyclase, decrease in basal activity of adenylate cyclase in platelets and reducing thyroxine concentration in cow plasma 5 years after radioiodine damage to thyroid gland with doses higher than 200 Gy were detected, whereas only decrease in adenylate cyclase activity in platelets from animals irradiated with 40 Gy to thyroid gland was observed. No changes in platelet adenylate cyclase in cows exposed to less than 1 Gy to thyroid gland after 5 years of maintenance on the territory with 137Cs contamination density lower than 0.37 MBq/m2 were found.

[Prognostication of the dose modifying factor in consecutive thermo-radiation exposure of yeast cells]. / Prognozirovanie faktora izmeneniia dozy pri posledovatel'nom termoradiatsionnom vozdeistvii na drozhzhevye kletki.

The dependence of dose modifying factor after the consecutive thermoradiation actions on dose rate and dose of ionizing radiation as well as on temperature and duration of its application was studied for yeast cells. The results obtained were described and interpreted by means of the mathematical model of synergism in accordance with which the synergism is expected to result from the additional lethal damage arising from the interaction of sublesions induced by both agents.

[The limit of the modifiability of cellular radiosensitivity in sequential exposure to ionizing radiation and physical factors of a nonionizing nature]. / Predel modifitsiruemosti radiochuvstvitel'nosti kletok pri posledovatel'nom vozdeistvii ioniziruiushchego izlucheniia i fizicheskikh faktorov neioniziruiushchei prirody.

The application of a mathematical model of synergism in describing the consecutive combined actions of ionizing radiation and other physical agents has been considered. Using various cell systems it has been shown that the model permits to predict the highest dose modifying factor and conditions in which it can be achieved.

[Mathematical description of the successive action of ionizing radiation and hyperthermia on mammalian cells]. / Matematicheskoe opisanie posledovatel'nogo deistviia ioniziruiushchego izlucheniia i gipertermii na kletki mlekopitaiushchikh.

A previously proposed mathematical model for the description of the effects of simultaneous action of hyperthermia and ionizing radiation was used to predict the successive treatment of these agents. The model suggests that the synergistic effect of combined action of ionizing radiation and hyperthermia is caused by additional lethal damages arising from the interaction of sublesions induced by both agents. These sublesions are not lethal after the action of these modalities, each taken alone. The model was tested against experimental data reported by other authors. The applicability of the proposed model was demonstrated to predict the dose modifying factor and the limited modification of mammalian cell radiosensitivity by hyperthermia as well as to reveal a more effective sequence of these agents.

Thiamine-binding protein from rat erythrocytes.

A protein with thiamine-binding activity (14 nmole/mg protein) was isolated from rat red cells by affinity chromatography. Adsorbent with varying degrees of hydrophobicity containing thiamine as ligand were used for the isolation. A 2300-fold purification in a 50% overall yield was attained. The purified thiamine-binding protein is homogeneous on polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate.

[Thiamine transport into rat erythrocytes]. / Transport tiamina v éritrotsity krys.

14C-thiamine transport across the membranes of erythrocytes obtained from blood of normal rats was studied. The active transport was observed at less than 0.5 microM thiamine concentration. An increase in the thiamine concentration resulted in a decrease in the active transport which was accompanied by increased diffusion. Thiamine analogs inhibited its transport into erythrocytes with different efficiency. The rate of thiamine phosphate esters formation in the course of incubation characterized the state of functional activity of the kinase and phosphatase systems. The data obtained suggest that transport and phosphorylation are independent processes in erythrocytes.

[Purification of thiamine binding protein from rat erythrocytes by affinity chromatography]. / Ochistka tiaminsviazyvaiushchego belka éritrotsitov krys affinnoi khromatografiei.

Protein with thiamine-binding activity (14 nmole/mg protein) was isolated from rat red cells by affinity chromatography. Adsorbents with varying degrees of hydrophoby containing thiamine as ligand were made use for isolation. A2300-fold purification with a 50% overall yield was attained. The protein preparation was found to be homogenous upon polyacrylamide gel electrophoresis. The role of pH of the medium, of ions of bivalent metals in vitamin B1 binding with the protein isolated has been shown.

[Blood transketolase activity and the TDP effect as indices of thiamine body allowance]. / Aktivnost' transketolazy krovi i TDF-éffekt kak pokazateli obespechennosti organizma tiaminom.

Protein-bound and free forms of thiamin diphosphate (TDP) (separated by dialysis and gel filtration) were found in rat erythrocytes. Content of TDP in blood did not correlate with the transketolase activity at the initial steps of B1 avitaminosis. Decrease of the DTP total amount in blood by more than 80% did not affect distinctly the transketolase activity. As shown by binding of 14C-TDP during the equilibrium dialysis and gel filtration, the apotransketolase did not occur in erythrocytes of thiamin-deficient rats. Activation of transketolase, which occurred after addition of 50 mg TDP into the whole blood lysates (TDP-effect), was characteristic for the later steps of the avitaminosis; it depended rather on leukocyte than on erythrocyte transketolase. Estimation of TDP concentration in blood was the most suitable assay for a body providing with thiamin at the early steps of the avitaminosis. The accuracy of the coenzyme estimation was decreased within 15-30 days of the avitaminosis due to its drastic lowering. In this case, determination of the transketolase activity was the most suitable criterion. The thiamin-binding protein, found in erythrocytes, appears to participate in transport of the vitamin across erythrocyte membranes.