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[A mathematical model of the changes in bone marrow cellularity in radiation exposures].

The model is based on classical ideas about of hemopoiesis in normal conditions and under irradiation. It consists of only two equations characterizing stem and differentiated bone marrow cell dynamics. The systemic mechanisms of hemopoiesis regulation were roughly taken into account. The formulae suitable for calculations of equilibrium cell concentrations under prolonged irradiation were derived. The model was shown to be in agreement with experimental data on hemopoietic system changes under acute and prolonged irradiation of rodents and dogs. The model is intended for describing the extent of hemopoiesis disturbance under those modes of mammalian exposure when describing of general regularities is enough.

Animals↗

Increase of bone marrow cellularity during erythropoietin treatment in myeloma.

Treatment of myeloma-associated chronic anemia with recombinant human erythropoietin (rHuEPO) has been shown to be successful in the majority of patients. We have morphometrically investigated bone marrow sections from the iliac crest of 20 anemic myeloma patients prior to rHuEPO therapy. The 15 responding patients were re-examined after three months and, if possible, after 6 and 12 months of treatment. Significant differences were found between responders and nonresponders prior to therapy. Nonresponders presented with a pronounced shift to the right in their erythroid bone marrow cell compartment and partly with higher serum levels of endogenous erythropoietin. During rHuEPO therapy, responders showed increases in all subsets of erythropoiesis and in the total amount of hemopoietic tissue. Response was accompanied by a marked drop of serum ferritin levels, a rise in serum levels of transferrin receptors and the emptying of bone marrow iron stores; the World Health Organization performance status improved. Responders tended to present with less advanced disease stages and better performance status and showed significantly longer survival times. Loss of responsiveness to rHuEPO was observed in one patient during the terminal stage of the disease. In conclusion, morphometric examination of bone marrow biopsies during the course of rHuEPO therapy showed that the response achieved in hemoglobin values was clearly mirrored in equivalent increments of the erythroid bone marrow cell compartment.

Aged↗

[The problem of the radiosensitivity of bone marrow cellular elements and assessments of the postradiation kinetics of myelopoiesis (an analysis based on data on the sequelae of the accident at the Chernobyl Atomic Electric Power Station].

On the basis of the data obtained from 61 cases of accidental exposure (0.1-12.5 Gy) at the Chernobyl A.P.S. the kinetics of acute radiation bone-marrow syndrome was analyzed and radiosensitivity of the entire spectrum of human granulocytic compartment cells was estimated. The radiosensitivity estimates were made by a "functional" criterion, developed by the authors, which was based on the comparative ability of irradiated and nonirradiated bone marrow cells of different maturity to produce peripheral blood neutrophils. Changes were found in physiology of myeloid cells during their maturation: the maturation mechanism, for cells of the committed pool, was "attached" to the division process, whereas these processes were independent for cells of the dividing and maturing pool. It is once again confirmed that the transit time of a maturing myeloid cell, to begin with the primarily committed one and to end with a peripheral blood neutrophil, is not constant and lasts normally for 32 days.

Accidents↗

An immunotoxicological evaluation of 4,4'-thiobis-(6-t-butyl-m-cresol) in female B6C3F1 mice. 1. Body and organ weights, hematology, serum chemistries, bone marrow cellularity, and hepatic microsomal parameters.

Adult female B6C3F1 mice were gavaged with 4,4'-thiobis-(6-t-butyl-m-cresol) (TBBC) in corn oil at doses of 10, 100, or 200 mg/kg daily for 14 consecutive days. There was no overt toxicity, as manifested by grossly observable behavioral changes, decreased growth rate over the exposure period, or mortality. There were also no marked effects on serum chemistries or hematology, with the exception of a significant increase (41%) in the number of leukocytes at the highest dose. Absolute differential counts indicated that significant increases occurred in the number of lymphocytes (31%) and neutrophils (177%). Studies with bone marrow indicated a significant 30% increase in the number of cells/femur from animals treated with the highest dose of TBBC. The number of macrophage progenitors (CFU-M)/femur was significantly increased by 28%, while the number of granulocyte-monocyte progenitors (CFU-GM)/femur was nonsignificantly increased by 20% in the high dose animals. The weight of both the spleen and liver was increased in a dose-related fashion, although the histopathology of the spleen of TBBC-treated mice was not different from control. The livers of mice receiving the high dose showed mild focal hydropic degeneration, mild hepatitis, and a slight increase in the number of Kupffer cells. No other organs were affected. Liver microsomal protein and cytochrome P-450 levels were increased in a dose-related fashion. Enzyme activities of aminopyrine demethylase and aniline hydroxylase, but not arylhydrocarbon hydroxylase, were also increased in a dose-related fashion.

Animals↗

Pregnancy-induced pancytopenia with cellular bone marrow: distinctive hematologic features.

Three patients with pregnancy-induced pancytopenia also exhibited variable features of sideroblastic anemia and amegakaryocytic thrombocytopenia. Treatment with anti-thymocyte globulin proved highly effective in two cases and a spontaneous remission occurred in the third. This illness is distinct from the more commonly reported incidental association of pregnancy with classic aplastic anemia. Its differentiation from myelodysplasia is also emphasized.

Adult↗