Individual variation of 90Sr deposition and its variability depending on the genotypic homogeneity of the sample

Individual peculiarities of 90Sr skeleton deposition in CBA mice were investigated. Differences in the radionuclide accumulation were not more than two times. Sex features in 90Sr deposition were not revealed. The range of individual variability of 90Sr deposition was analyzed in inbred mice in comparison with outbred stock and voles from natural population; it was found that variability in the radionuclide accumulation increased with sample genotypic heterogeneity.     

The optimization of the soil acidity of agrocenosis contaminated 137Cs and 90Sr: threshold parameters

During the field researches were determined the differences between agrochemical optimum of the acidity of the Sod-podzol loamy sand soil, which provides high productivity of the crops and the pH-value, which provides the minimal accumulation of 137Cs and of 90Sr by the biomass (the ecological optimum). On the average for the majority of the agricultural plants the minimal accumulations of 137Cs and of 90Sr are noticed under pHKCl 6.7, which is higher than agrochemical optimum on 0.7. The efficiency of liming under the discrimination of 137Cs and of 90Sr is much higher in soils with low values of pH. On the average, in crop rotation due to decreasing of the acidity in the soil from 4.9 to 5.9 pHKCl, the crop yield has grown on 9%, 137Cs contents has decreased on 16.7%, 90Sr--on 23.7%. The further decreasing of the soil acidity (from 5.9 to 6.8 pHKCl) was poorly effective: the productivity didn't change essentially. The transfer of 137Cs decreased on 8.9% and of 90Sr on 8.4%.     

The effect of internal exposure to 90Sr on hematopoietic stem cells in CBA mice

After acute intake of 90Sr the changes of d-9 CFUs number in mice (CBA) bone marrow, spleen and peripheral blood were investigated. The obtained results indicated similar quantitative changes in bone marrow and spleen CFUs on exposure to the 90Sr when radiation doses did not cause the decrease in life-time (1.11 kBq/g). Sarcomogeneous doses of 90Sr (29.6 kBq/g) resulted in drastic changes of hemopoietic system: spleen haematopoiesis activation and suppression of bone marrow functions. On the first day after 90Sr injection (29.6 kBq/g) the increase in number of peripheral blood CFUs (circulating pool) was observed.     

Soil-to-grain transfer of fallout 90Sr for 28 winter wheat cultivars

In order to identify wheat cultivars with minimum soil-to-grain transfer of fallout ⁹⁰Sr, 28 winter wheat cultivars were investigated at three different sites with different soil types in Upper Bavaria. Each cultivar was grown on an area of 10 m² and harvested in August 1999. Mean soil-to-grain concentration ratios (C _r) were 0.151 ± 0.029, 0.205 ± 0.035 and 0.060 ± 0.012, respectively. The C _r values obtained varied by factors of up to 2.6 for the different cultivars at a given site, and by factors of up to 5.0 for the different sites and a given cultivar. Site-averaged normalized concentration ratios (SANC_r) ranged from 0.666 ± 0.062 to 1.503 ± 0.161. The cultivars Convent, Ludwig, and Semper, showed the lowest uptake of ⁹⁰Sr compared to the mean of all cultivars at each site. A cultivar that shows both minimum uptake of ⁹⁰Sr and ¹³⁷Cs could not be identified. The results suggest that ⁹⁰Sr rather than ¹³⁷Cs might be the limiting radionuclide concerning the use of contaminated land for wheat production. Thus, more efforts might be necessary identifying wheat cultivars with minimum ⁹⁰Sr uptake.     

The effect of pesticides on the development in rats of osteosarcomas induced by 90Sr]

In experiments with rats the authors have assessed the development of remote effects of radiation (90Sr) combined with chronic exposure to chlorophos and lindane within a wide range of doses. It has been shown that chronically administered chlorophos and lindane have no carcinogenic and cocarcinogenic effects.     

Haematological studies on90Sr-90Y-toxicity: II. Femoral CFU-s kinetics and mitogen response of spleen cells

Summary Ferrokinetic perturbances in peripheral blood of mice treated with⁹⁰Sr-⁹⁰Y were demonstrated previously. This paper deals with the effects of⁹⁰Sr-⁹⁰Y treatment (2.5, 5, and 10 µCi/mouse), on the haemopoietic stem cell compartment and on the immune-status. The frequency and kinetics of haemopoietic stem cells in femoral marrow (determined as colony forming units in spleen, CFU-s) and their haemopoietic efficiency (as gauged by⁵⁹Fe-and¹²⁵IUdR-uptake) were estimated. The responsiveness of splenic lymphocytes of the same animals to mitogens (Con A, PHA, and LPS) were also measured. In all assays striking dose-dependent changes marked either by depressions or overshoots were observed during the first week post-incorporation. These are correlated with the pattern of deposition (primary and secondary) of the radionuclides⁹⁰Sr-⁹⁰Y. Towards the end of the period of observation and presumably thereafter, the dependence on dose disappeared and the values remained subnormal. An exception to this was the response of splenic lymphocytes to mitogens. Much higher reactivity was recorded up to the end. This higher reactivity is attributed to augmented cellular turnover, the newly recruited lymphocytes (in accord with their extreme radiosensitivity), being probably more reactive.     

An analytical model for determining two-dimensional receptor-ligand kinetics

Cell-cell adhesive interactions play a pivotal role in major pathophysiological vascular processes, such as inflammation, infection, thrombosis, and cancer metastasis, and are regulated by hemodynamic forces generated by blood flow. Cell adhesion is mediated by the binding of receptors to ligands, which are both anchored on two-dimensional (2-D) membranes of apposing cells. Biophysical assays have been developed to determine the unstressed (no-force) 2-D affinity but fail to disclose its dependence on force. Here we develop an analytical model to estimate the 2-D kinetics of diverse receptor-ligand pairs as a function of force, including antibody-antigen, vascular selectin-ligand, and bacterial adhesin-ligand interactions. The model can account for multiple bond interactions necessary to mediate adhesion and resist detachment amid high hemodynamic forces. Using this model, we provide a generalized biophysical interpretation of the counterintuitive force-induced stabilization of cell rolling observed by a select subset of receptor-ligand pairs with specific intrinsic kinetic properties. This study enables us to understand how single-molecule and multibond biophysics modulate the macroscopic cell behavior in diverse pathophysiological processes.     

The accumulation of radionuclides 137Cs and 90Sr by different kinds and grades legumes crops

The decision of protein problem on contaminated by radionuclides territories as a result of the accident on Chernobyl NPP is not possible without increase of the sowing areas legumes crops (peas, lupine, soybean). Introduction in agricultural manufacture of grades with a low level of accumulation radionuclides (peas--Aist, Polesskay, Gomelskay Agat; soybean--Severnaya zvezda, Mageva) will allow to receive agricultural production adequate "Republican allowable levels of the contents of 137Cs and 90Sr in agricultural raw material and forages" on arable lands at their higher density of radioactive contamination: 137Cs--1300-1480 kBq/m2 (35.0-40.0 Ci/km2): 90Sr--18.5-37.0 kBq/m2 (0.50-1.00 Ci/km2).     

The division of labor: genotypic versus phenotypic specialization

A model of the division of labor in simple evolving systems is explored to compare two strategies evident in natural populations: phenotypic specialization (such as differentiation by regulated gene expression) and genotypic specialization (such as co-infection by complementary covirus populations). While genotypic specialization is vulnerable to the chance extinction of an essential specialist type and to parasitism, phenotypic specialization is able to overcome these hurdles. When simple spatial effects are included, phenotypic specialization has further benefits, protecting against destructive dynamic patterns. Many of the advantages of phenotypic specialization, however, can only be realized when a high degree of relatedness within groups is ensured.