Serum of 18 children and adolescents with chronic renal failure at the terminal stage of the kidney disease was fractionated on plates manufactured by Amicon Company and on Sephadex G-25. Uremic serum and ultrafiltrate with a molecular mass of 50,000 produced erythropoiesis inhibiting effect in polycythemic mice. However, the uremic serum and its fractions (50000--5000 and 3000--800) did not alter the number of microscopically visible colonies in the spleen of irradiated mice and their differentiation and proliferation compared to the mice that had received donor serum. Thus the inhibitory effect of serum and its fractions of patients with chronic renal failure is possible effected at the level of undifferentiated erythroid precursors producing no effect on the pluripotent stem cell.

The effect of the physiological concentration of cyclic adenosine-3' ,5'-monophosphate (cAMP) analogues on the proliferation of mouse bone marrow stem hemopoietic cells (CFUs) was examined. The stimulating effect was estimated from the decrease in CFUs expressed in the percentage derived from comparing the number of spleen colonies in the control and experimental groups treated with hydroxyurea 10(-3) M (incubation with hydroxyurea resuted in the cell death in S-phase). Cyclic AMP stimulted the proliferation of CFUs by 60%, while its analogues such as 8-(N-chloroacetylaminoethylamino)-cAMP, 1-(N-chloroacetylaminoethyoxy)-cAMP and 1-(N-(p-fluorosulfonyl)-benzoylaminoethoxy)-cAMP stimulated the proliferation by 39.2%, 32.4% and 21.9%, respectively. Therefore, the synthetic analogues of cAMP were not only far from inhibiting the proliferation of CFUs but, on the contrary, exerted a stimualting effect unlike most antineoplastic alkylating drugs that depress hemopoiesis up to its total aplasia.

An early decrease in the total cellularity and amount of bone marrow CFUs was recorded in (CBAxC57B)F1 adrenalectomized mice. This decrease was accompainied by a significant fall in the number of proliferating stem cells in the bone marrow and spleen, evaluated by the method of "thymidine suicide". After normalization of the total amount of CFUs followed by that of the bone marrow cellularity the level of cycling stem cells returned to initial.

Spleen colonies of syngenic bone marrow cells were grown in sublethally irradiated BALB/c mice. DNA contents of interphase nuclei of the colony cells have been measured using the Feulgen cytophotometry. The rates of appearance of cells with variations in chromosome number were calculated according to the following equation: (Formula: see text), where No - the total number of colonies, Nm - the number of mutant colonies, and n- the number of cells examined. The rate of genome mutations was found to be 7.7 +/- 0.6X X10(-2) per cell per generation. Binominal distribution of clones according to the number of mutant cells has been noticed. Cells with decreased numbers of chromosomes (hypodiploid mutants) were of a more frequent occurrence than cells with increased chromosome numbers (hyperdiploid mutants). It is concluded that the propagation of colony-forming bone marrow cells in irradiated animals is accompanied by almost the same increase in frequency of genome mutations as in the case of the cultivation of cells in monolayer cultures.

Age-dependent migration and differentiation of hematopoietic stem cells was studied in autoimmune mice (NZB chi chi NZW) F(1) of different age. It was shown that the migration rate of stem cells in old (NZB X NZW) F(1) mice decreases. Despite the age the granulopoietic differentia of stem cells was inhibited in these mice. It is suggested that (NZB x NZW) F(1) mice have either an impaired development of T lymphocyte subpopulation affecting the granulopoietic differentiation of stem cells or a genetic defect of the granulopoietic progenitors (CFU(c)).

Electron microscopic examinations of human renal carcinoma showed that both light and dark (granular) differentiated tumour cells may have ultrastructural features of the cells of any nephron segment. In the light of these results and concepts of the capacity of undifferentiated tumour cells for specific differentiation, the decisive importance in histogenesis (cytogenesis) of the renal carcinoma belongs not to the site of its origin in one or another nephron segment but to the level of differentiation of stem cells (polypotent or monopotent) undergoing malignization and to the direction of their further differentiation. The paper presents concrete ultrastructural differential diagnostic features of renal carcinoma cells.

Phentyrin toxicity depends to a large measure on the route of its administration. Adequately toxic doses of phentyrin intravenously are approximately ten times as less compared to peroral administration. High doses of the drug produce appetite loss, occasional vomiting, salivation, diarrhea, flabbiness and weight loss. ECG shows slow pulse, reduced voltage and changes in T wave. At early periods the animals' death ensues with phenomena of emaciation, a delayed death can be recorded only in some cases. Morbid anatomy shows atrophic changes in the lymphatic nodes, in the spleen, thyroid, in the gastrointestinal mucosa, and changes in the liver and kidneys. Phentyrin in tolerated doses exerts no adverse action on stem cells of bone marrow, but affects spleen cells. The drug alters the weight of some endocrine organs -- the thyroid, uterus and adrenals.

The horseradish peroxidase method was used to investigate the sources of direct and indirect connections to the caudate nucleus in the cat. It is shown that different cortical and subcortical areas contain cells projecting to the caudate nucleus. Labelled neurons after caudate injections were also found in the globus pallidus. Along with the intralaminar complex the ventral anterior and mediodorsal nuclei were found to be the most significant sources of thalamo-caudate projections. The most caudal projection to the caudate nucleus in the cat was demonstrated by finding labelled neurons in the locus coeruleus. The functional significance of the investigated afferent connections of the caudate nucleus is discussed.

By methods of analytical electrophoresis nuclear chromatin proteins of normal and leukaemic hemopoietic rat cells were studied. There were revealed 1--2 extra bands in the histones extracted from chromatin of leukaemic cells. These proteins appear to be identical to histones of H10 type. The majority of nonhistone proteins of nuclear chromatin from normal and leukaemic hemopoietic cells show similar electrophoretic characteristics, whereas there were also found components typical for chromatin of only normal or leukaemic hemopoietic cells.