Influence of fertilizing on the (137)Cs soil-plant transfer in a spruce forest of Southern Germany.

Fertilization with 2.5t/ha limestone: (83% CaCO(3), 8% MgO, 6% K(2)O, 3% P(2)O(5)) reduces the (137)Cs transfer from spruce forest soil into plants like fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus) by a factor of 2-5 during at least 11 years as measured by the aggregated transfer factor T(ag). In 1997 and 2006 these results were confirmed by additional measurements of the (137)Cs transfer factor TF, related to the root zone (O(h) horizon), which were explained by the selective sorption of (137)Cs in the root zone by measurements of the Radiocaesium Interception Potential (RIP) in fertilized (RIP>179meq/kg) and non-fertilized soils (RIP<74meq/kg).

Migration and bioavailability of (137)Cs in forest soil of southern Germany.

To give a quantitative description of the radiocaesium soil-plant transfer for fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus), physical and chemical properties of soils in spruce and mixed forest stands were investigated. Of special interest was the selective sorption of radiocaesium, which was determined by measuring the Radiocaesium Interception Potential (RIP). Forest soil and plants were taken at 10 locations of the Altdorfer Wald (5 sites in spruce forest and 5 sites in mixed forest). It was found that the bioavailability of radiocaesium in spruce forest was on average seven times higher than in mixed forest. It was shown that important factors determining the bioavailability of radiocaesium in forest soil were its exchangeability and the radiocaesium interception potential (RIP) of the soil. Low potassium concentration in soil solution of forest soils favors radiocaesium soil-plant transfer. Ammonium in forest soils plays an even more important role than potassium as a mobilizer of radiocaesium. The availability factor - a function of RIP, exchangeability and cationic composition of soil solution - characterized reliably the soil-plant transfer in both spruce and mixed forest. For highly organic soils in coniferous forest, radiocaesium sorption at regular exchange sites should be taken into account when its bioavailability is considered.

Bioavailability of radiostrontium in soil: experimental study and modeling.

Parameters related to 90Sr mobility in the soil-plant system are reported: exchangeable content, selectivity coefficient, and transfer factor. Large mobility of 90Sr in different soil types was shown. The fraction of exchangeable 90Sr varied between 70 and 90%. The selectivity coefficient K(C)(90Sr/Ca) values were in the range 1.3-2.5. The radionuclide transfer factors (TF) varied by a factor of 9.6 for barley seedlings and by a factor of 6.6 for lupine seedlings. The exchangeable Ca content was the determinant soil parameter responsible for differences in 90Sr biological availability. A static model was devised that describes 90Sr sorption from soil solution by soil and on the root surface. The parameter of 90Sr bioavailability (A) has been suggested. Parameter A was calculated from data on soil exchangeable Ca content and 90Sr mobility indicators--exchangeable fraction of the radionuclide and the selectivity coefficient K(C)(90Sr/Ca). A correlation was found between TF and parameter A.

[137Cs vertical migration in boggy soils in the long term after the Chernobyl accident]. / Vertikal'naia migratsiia 137Cs v volotnykh pochvakh v otdalenny period posle avarii na ChAES.

137Cs vertical migration in boggy soils has been studied 15 years after the Chernobyl accident. The rate of vertical migration of the radionuclide is shown to be dependent on the peculiarities of formation of peatbogs, their moistening regime and soil properties. 137Cs migration in a high-land peatbog is characterized by higher intensity then in lowland or transitional peatbogs. Differences in 137Cs vertical migration are to a large extent caused by the contents in soil of exhangeable and mobile radionuclide forms. The derived experimental data that describe 137Cs distribution over the profiles of peaty soils of different type are used for parameterization of two-component convective-diffusion model. Ecological and effective half-life periods of 137Cs content reduction in the soil root layer have been calculated. A long-term prediction is given of the dynamics of the radionuclide content in the root layer of peaty soils.

[Evaluation of cell membrane permeability for Ca2+ and adenylate cyclase in sheep peripheral blood cells, exposed to low doses of radiation]. / Otsenka pronitsaemosti plazmaticheskoi membrany dlia Ca2+ i aktivnosti adenilattsiklazy v kletkakh perifericheskoi krovi ovets, obluchennykh v malykh dozakh.

Chronic irradiation of sheep with doses of 2.6 and 12.9 mC.kg was characterized by the modification of the adenylatecyclase activity and Ca2+ permeability of plasma membrane in cells of the peripheric blood, with no changes in the clinical and hematological indicators. The observed effects are assumed to result from structural and dynamic variations in the lipids of membranes.

[Method of assessment of 137Cs biological availability in forest soil]. / Metod otsenki biologicheskoi dostupnosti 137Cs v lesnykh pochvakh.

A method for quantitative assessment of 137Cs availability to plants in forest ecosystems on the basis of soil properties has been developed. It is shown that the experimental dependencies of 137Cs soil-to-plant transfer factor (TFag) for fern and bilberry on the bioavailability factor calculated on the basis of soil characteristics of root layer: 137Cs exchangeability, exchangeable Ca, effective selectivity coefficient, were satisfactory described by linear function. The advantage of the proposed method is that the necessary soil characteristics can be taken from the reference literature, evaluated using empirical correlations or determined with standard agrochemical procedures.

Comparative study of 137Cs partitioning between solid and liquid phases in Lakes Constance, Lugano and Vorsee.

The methodology for estimating radiocaesium distribution between solid and liquid phases in lakes is applied for three prealpine lakes: Lake Constance (Germany), Lake Lugano (Switzerland) and Lake Vorsee (Germany). It is based on use of the exchangeable distribution coefficient and application of the exchangeable radiocaesium interception potential (RIPex). The methodology was tested against experimental data. Good agreement was found between estimated and measured 137Cs concentrations in Lake Constance and Lake Lugano, whereas for Lake Vorsee a discrepancy was found. Bottom sediments in Lake Vorsee are composed mainly of organic material and probably cannot be described in terms of the specific sorption characteristics attributed to illitic clay minerals.

[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.

[Total Ca contents in blood cells and plasma of the irradiated animals]. / Obshchee soderzhanie Ca v kletkakh krovi i plazme obluchennykh zhivotnykh.

It was found that the total Ca content in erythrocytes from irradiated sheep and horses increased by 10-40% from 1st till 5th days after irradiation, the intracellular Mg content being unchanged. More than 2-fold increase in total Ca content in lymphocytes during first 15 days was revealed, while in platelets only a trend for a growth in acute period of radiation disease was detected. On the contrary, no reliable changes in total Ca content in plasma after irradiation were observed. This fact indicates that Ca accumulation in blood cells after whole-body irradiation is due to disturbance in intracellular Ca(2+)-homeostasis.

[The content of immunoreactive calmodulin in the blood cells of irradiated animals]. / Soderzhanie immunoreaktivnogo kal'modulina v kletkakh krovi obluchennykh zhivotnykh.

The immunoreactive calmodulin content was shown to increase in the irradiated platelets of rats and cows. Total Ca content did not vary significantly in platelets of exposed animals although there was a tendency toward its increase. At the same time, total Ca content in lymphocytes of irradiated cows increased while the immunoreactive calmodulin level remained unchanged.

Changes in toxic and antitumor properties of ftorafur by induction or inhibition of the microsomal enzymes activity.

The inducers of microsomal drug-metabolizing enzymes phenobarbital (PB) and 20-methylcholanthrene (MC) inhibited the lethargic effect of high doses of ftorafur in C57BL/6j mice, but stimulated the animal mortality at days 4-8 after the drug administration. The opposite effect has been obtained by the combination of ftorafur with the inhibitor of the microsomal enzymes SKF 525A. Animal pretreatment with PB or with PB + MC markedly enhanced the antineoplastic activity of ftorafur in Rauscher leukemia-, leukemia La-, or hemangiopericytoma-bearing mice but seemed unlikely to afford any therapeutic advantage over this drug because the lethal toxicity of ftorafur was increased.

[Chloramphenicol and dextramycin, inhibitors of mammary carcinogenesis induced by 7,12-dimethylbenz(a)anthracene]. / Khloramfenikol i dekstramitsii: ingibitory kantserogeneza, vyzavannogo 7,12-dimetilbenz(a) antratsenom v molochnykh zhelezakh.

In noninbred rats chloramphenicol and its optical isomer dextramycin diminished the blastomogenic effect of 7,12-dimethylbenz(a)anthracene on mammary glands. The protective effect was shown by a decreased tumor incidence at all periods of observation and an increase in the life span of rats and in the case of dextramycin this action consisted in a prolongation of the latent period of tumor emergence.

[Change of toxic and antineoplastic properties of ftorafur by means of action on nonspecific microsomal oxidase]. / Izmenenie toksicheskikh i protivoopukholevykh svoistv ftorafura putem vozdeistviia na nespetsificheskie oksidazy mikrosom.

The inducers of microsomal hydroxylases, phenobarbitone and methylcholanthrene, inhibited the development of neurotoxic shock provoked by high doses of ftorafur in mice, but stimulated the animal mortality on the 4th-8th day after the drug administration. The opposite effect on both toxicity manifestations has been obtained under the action of the inhibitor SKF 525-A. Pretreatment of the animals with phenobarbitone or phenobarbitone-methylcholanthrene combination markedly increased the antineoplastic activity of ftorafur determined by a loss of the spleen weight in mice infected with Rauscher's leukemia.

[Protective effect of chloramphenicol and dextramycin following the adrenocorticolytic action of 7, 12-dimethylbenz(a)anthracene].

The influence of chloramphenicol (CAP) and dextramycine (DMC) on the adrenocorticolytic action of 7,12-dimethylbenz(a)anthracene (DMBA) was studied in rats. It appeared that CAP in doses of 1.0-0.1 mg/g and DMC in doses of 1.0-0.05 mg/g completely prevented the development of necroses of the adrenal glands in administration 1.5 hours before the carcinogen. With lower doses of CAP and DMC and also when they were administered 48 hours before or 1.5 hours after the carcinogen the protective effect was retained only partially. The toxic action of the carcinogen remained unchanged when CAP and DMC were administered 3, 6 or 24 hours after DMBA.

Dextramycine (the dextraisomer of chloramphenicol) as an inhibitor of the induction of lung adenomas in mice.

Dextramycine as well as leftrotating isomer (chloramphenicol--levomycetin) diminished the blastomogenic effect of urethane which is known to induce lung adenomas in mice.

[Effect of chloramphenicol on the toxic and therapeutic effect of N-nitrosomethylurea]. / Vliianie khloramfenikola na toksicheskii i lechebnyi éffekt N-nitrozometilmocheviny.

The influence of chloramphenical (CAP) on toxic and therapeutic effect of N-nitrosomethyl urea (MNU) in mice of CBA line was studied. It is shown that in injection of lethal doses of MNU--0.08--0.1 mg/g in intact animals CAP reduced LD100 to LD50 and LD50 to LD0. Also CAP increased an average survival of animals with ascites Ehrlich tumor when injected the lethal dose of MNU--0.1 mg/g. Therapeutic effect of MNU in a dose of 0.05--0.075 mg/g in the presence of CAP was not changed and sometimes was even increased. Under discussion is the significance of the obtained results for chemotherapy of malignant tumors in man.