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A simple and objective rapid method for assessing serum and plasma toxicity is proposed, based on registration of the frog cardiac contractions. The method permits assessment of disease severity and monitoring the time course of pathological process after surgery and plasmapheresis. The level of toxemia and disease severity did not correlate in 20% of cases. Causes of this disagreement are discussed.

It was shown in the culture of rat bone marrow cells in experimental polycythemia that the chalone activity of erythrocytic chalone considerably drops in the presence of phytohemagglutinin (PHA). The chalone inhibits the agglutinating activity of PHA with respect to bone marrow cells. Absorption of the chalone on the immobilized PHA leads to disappearance from it and of PAS-positive bands recorded electrophoretically and to a strong decrease in PAS-negative band intensity. Experiments with preliminary incubation of rat red cells before preparation of the chalone suggest that in the course of its preparation two polypeptides one of which is PAS-positive are released into the medium. It is suggested that the chalone includes superficial membrane proteins of red cells, possibly, in the form of a combination of PAS-positive and PAS-negative bands. Potential mechanisms of chalone release from the surface of cells and features of their action on the cells are discussed.

Under study was the intensity of the collagen synthesis by osteoblasts of the primordium of the rat's maxilla at different terms of embryogenesis. Autoradiographic method revealed that the greatest part of incorporated glycin was used for construction of collagenous molecules, and the least part--for the synthesis of other cytoplasmic proteins of osteoblast. Different intensity of the synthesis of de novo collagen was established at different stages of embryogenesis. The most intensive synthesis of collagen was found to begin from the 18th day of the maxillary bone primordium development.

It has been shown that erythrocytic chalone was bound to the surface of mouse myelokaryocytes after one minute, penetrated them after 30 minutes, disintegrated and excreted in the form of low-molecular mass compounds after 4 hours of incubation. The cells treated with erythrocytic chalone or trypsin are not capable to respond to the repeated action of chalone over 2 hours, which seems likely to be related to the lack of receptor resynthesis during the period under consideration.

In rats, administration of the diphtheric toxin and propranolol after acute hemorrhage decreased production of the erythrocyte chalone. In vitro, adrenalin or ephedrine addition to erythrocytes increased excretion of the erythrocyte chalone. There is a direct correlation between production of chalone and depression of the bone marrow mitotic activity. The mechanism of the chalone release under the effect of the sympathetic transmitters, is discussed.

Leucovorin and cobamamide administered alone and in combination potentiate the proliferative activity of the erythroid and myeloid cells of the bone marrow. There is lack in mutual potentiation of the drugs.

The effect of an erythrocytic inhibitor obtained from patients with second polycythaemia, on the synthesis of DNA in bone marrow cells has been studied in vitro. The erythrocytic inhibitor was shown to have a specific effect. The decrease of DNA synthesis under erythraemia occurred with the dose of the inhibitor 2-3 times higher than with the dose applied in norm or under anemia. According to the results of gel-filtration and disc-electrophoresis, the inhibitor in question is a component of fraction II of polycythaemia erythrolysate with a low molecular weight. The electrophoresis mobility of this fraction in respect to albumin lies between 0.5 and 0.7. It is supposed that the inhibitor is a physiological regulator (chalone) of the erythron's cell proliferation.

The chalone fraction of erythrocyte extracts is immunologically identical to albumin and not identical to hemoglobin. It differs from albumin and hemoglobin in biological properties and electrophoretic mobility. The immune antichalone serum permits evaluating erythropoiesis in posttransfusion polycythemia and acute blood loss.

The effect of the erythrocytic chalone on the beginning, middle and end of the G2-period of the mitotic cycle has been studied in the erythroblastic cells of the mouse bone marrow. The end of S(-) and the beginning of G2(-) periods have been demonstrated to be the most sensitive to the effect in question. The erythrocytic chalone inhibits mitotic activity by decreasing the amount of prophases and inhibits incorporation of radioactive glycine into the dividing erythroblastic cells. The mechanism inhibiting their mitotic activity is discussed.

It was shown that erythrocytic inhibitor (G2-cheilon) acted both on the proliferating and on differentiated cells of the erythroid series of the mouse bone marrow. The effect of cheilon was expressbd as soon as 3 hours after its administration and lasted for from 8 to 48 hours, depending on the extent of cell differentiation. In case of a single cheilon administration, despite significant erythropoiesis disturbances, erythrocyte count determined 8 to 12 days later persists within the control level. Repeated administration of cheilon was accompanied by a fall of the erythrocyte count at later periods of the experiment.