[75Se]selenite and [75Se]selenate fluctuations during the development of murine hepatoma

The distribution of selenate and selenite selenium in C57L/J mice during the progression of BW7756 murine hepatoma was investigated using intra-ocular injection with the oxyanions labeled with ⁷⁵Se radioisotope. Comparison is made with the normal distribution of selenium studied by the RIXRF method. The trace elemental profiles, TEP, for the two oxidation states are compared in healthy and disease states. It has been found that the presence of tumor significantly changes the level of tracer in various uninvolved organs. These changes are prominent in the early growth phase of the tumor. The two oxidation states show differences in the TEP for kidney, spleen, stomach and testes.     

Effect of low doses of internal irradiation resulting from the administration of 75Se- and 35S-labeled compounds on the cellular immune response

The administration to rats of radioactive preparations. 75Se- selenomethionine, 35S-methionine or sodium 75Se-selenite in the amounts creating the absorbed dose in the body of 0.5 Gy suppressed the delayed hypersensitivity reaction as was registered 1-12 months after the injection. The delayed hypersensitivity was tested in vitro by the method of inhibimacrophage spreding inhibition. The degree of suppression of the cellular immune response depended upon the type of the compound administered, of which the radionuclide was a component, and upon characteristics of radiation spectrum of the radionuclide.     

Late consequences of action of low doses of ionizing radiation on human enzymatic antioxidant system

Age-related changes in the activity of superoxide dismutase and glutathione peroxidase in the blood of participants of the Chernobyl accident liquidation were studied. According to our findings the people under 30 years old are the most sensitive to irratiation.     

The action of atomic radiation in low doses on the biota

The radiobiological studies carried out in conditions of lower and slightly increased natural radiation background have prompted an idea of "low doses" in radiobiology which is proposed for discussion. The author emphasizes that the difference between the leading molecular and cellular mechanisms that come into play under the effect of high- and low-level atomic radiation makes it incorrect to assess the risk from low radiation doses on the basis of the regularities obtained with high doses.     

Molecular-cellular mechanisms of the biological action of low x-ray doses on isolated mammalian cells

The colony-formation was stimulated by X-irradiation (0.03-0.30 Gy) of cultured Chinese hamster cells. The stimulation was only noted in the nonadhered cells which was perhaps associated with a change in their adhesive properties. It was shown that low-level radiation induced changes in the structural organization of the cell membrane.     

Proteolytic system in lungs upon inhalation exposure to low doses of lead salts

Changes in proteinase--antiproteinase activities in lungs as a result of short-term (for 1 week) inhalation of rats with 0.01% (CH3COO)2 Pb have wholly compensative patterns, but it have been found increased cathepsine B activity as a negative prognostic factor. Chronic (for 2 month) toxicant inhalation caused considerable activation of both trypsine and cathepsine B under decreasing alpha 1-antitrypsine and alpha 2-macroglobuline activities. Cathepsine L activity was not affected. Disorders in the proteolysis system were evaluated as desadaptation situation in lung tissue under chronic toxic influence.     

The action of high doses of oestradiol on implantation and decidual reaction in the rat

The action of high doses of oestradiol on ovum implantation and decidual reaction was studied in pseudo-pregnant rats. It is shown that anomalies of ovum implantation take place after the injection of 10 μg of oestradiol on the 4th day of pregnancy, in that the decidual reaction is inhibited as demonstrated by ponderal evolution, lower ³H uridine uptake, ultrastructural features and the ploidy level of stromal cell nuclei.     

5'-Nucleotidase and adenosine deaminase activity in the rat brain upon prolonged effect of low radiation doses

The effect of combined low radiation doses (0.2-50.8 cGy) on the 5'-nucleotidase and adenosine deaminase activities in the rat hypothalamus, hippocamp and cerebral cortex during 45, 120 and 365 days was examined. It has been shown that the changes in the 5'-nucleotidase activity of the hypothalamus and hippocamp have a phase character. The direction of the changes in enzyme activity of the hypothalamus and hippocamp adenosine forming was dependent on the zone stay period and had the exactly opposite character depending on the early and prolonged stay period in the zone. 5'-nucleotidase activity was changed under the influence of mean and lesser doses with an increase of the zone stay period. No changes in the 5'-nucleotidase activity of the cerebral cortex were noted. No changes in the hypothalamic adenosine deaminase activity of rats that stayed in a zone during 45 days were revealed; under the effect of mean dose during 120 days the activity decreased and also in case of a higher dosage during one year. The adenosine deaminase activity in animal hippocamp decreased in rats only under the influence of the lesser dose, for 45-day period. The decrease in adenosine deaminase activity of the cerebral cortex that was noted under the effect of all the three doses during 45 days, the higher and mean doses during 120 days disappeared in a year.     

The use of intermittent trunk flexion to alleviate low back pain during prolonged standing

The current study examined of the effect of intermittent, short-term periods of full trunk flexion on the development of low back pain (LBP) during two hours of standing. Sixteen participants completed two 2-h standing protocols, separated by one week. On one day, participants stood statically for 2 h (control day); on the other day participants bent forward to full spine flexion (termed flexion trials) to elicit the flexion relaxation (FR) phenomenon for 5 s every 15 min (experimental day). The order of the control and experimental day was randomized. During both protocols, participants reported LBP using a 100 mm visual analogue scale every 15 min. During the flexion trials, lumbar spine posture, erector spinae and gluteus medius muscle activation was monitored. Ultimately, intermittent trunk flexion reduced LBP by 36% (10 mm) at the end of a 2-h period of standing. Further, erector spinae and gluteus medius muscle quietening during FR was observed in 91% and 65% of the flexion trials respectively, indicating that periods of rest did occurred possibly contributing to the reduction in LBP observed. Since flexion periods do not require any aids, they can be performed in most workplaces thereby increasing applicability.     

Tissue respiration of rat internal organs and skin during prolonged exposure to high ambient temperature]

Oxygen consumption by tissues of various organs was studied in acute experiments on albino rats in Warburg apparatus at a temperature of 37 degrees C. High environmental temperature proved to decrease the tissue gas exchange level. Participation of different organs in the reduction of total metabolic level varied and depended on the number of actions of the thermal factor. A more active inclusion of the majority of the organs into the adaptive reactions of the organism to the high temperature occurred during the third week.