George Brecher

Reticulocyte Size and Erythropoietic Stimulation

Summary The size distribution of peripheral red blood cells of rats recovering from phenylhydrazine anemia is reported. Reticulocytes produced during the first burst of active erythroid regeneration are as much as twice the normal size; degree of macrocytosis is related to the severity of the anemia. The initial crop of oversized cells is replaced by successive crops of reticulocytes of more normal size. It is suggested that separation of reticulocytes by centrifugation depends on their density, which is determined primarily by the MCHC.

Humoral Regulation of Erythropoiesis V. Relationship of Plasma Erythropoietine Level to Bone Marrow Activity

Summary Data have been presented on rate of appearance and disappearance of erythropoietine. Plasma level of erythropoietine rises promptly in response to hypoxia but on continued exposure declines. In rats with radiation-induced hypoplasia, this fall in erythropoietine titer was modified. Accordingly, it is suggested that the marrow utilizes erythropoietine and the clinical implications are discussed.

Effect of endotoxin on the kinetics of hemopoietic colony-forming cells in irradiated mice.

Hemopoietic recovery in irradiated animals is hastened by the action of bacterial endotoxin given as a single injection either before or shortly after irradiation (1). Bone marrow cellularity, peripheral blood granulocyte, erythrocyte, platelet, and lymphocyte concentrations, and survival are favorably affected and, in the mouse, the number of endogenous spleen colonies is increased (2-4). The fact that endotoxin is effective when given after irradiation rules out several modes of action. These include chemical protection, hypoxia, increased numbers of stem cells at the time of irradiation, and decreased sensitivity of the stem cells to the immediate killing action of radiation. Among the possibilities remaining are recovery of cells that otherwise would die on the resumption of mitosis, early resumption of mitosis, and shortening of the cell cycle. Means of exploring such possibilities are provided by the technique for enumerating colony-forming units (CFU) developed by Till and McCulloch (5-7). Suspensions containing hemopoietic cells are injected into recipient mice whose endogenous spleen colony formation has been suppressed by lethal irradiation and the resulting spleen colonies are counted 10 days later. The transplanted colonyforming units have many of the characteristics of stem cells (8), and in the present experiments we assume that their enumeration provides an assay of stem cells. The experiments presented here concern population changes in colony-forming units in spleen and femoral marrow resulting from an injection of Salmonella typhosa endotoxin 24 hours before or a few minutes after irradiation with 400 rads.

Effects of Bacterial Endotoxin on the Occurrence of Spleen Colonies in Irradiated Mice

It is generally agreed that survival in the midlethal radiation dose range depends principally on hemopoietic recovery. Administration of endotoxin as a single injection either before or shortly after irradiation in the mouse hastens recovery of granulocytes, erythrocytes, platelets, and lymphocytes (1, 2), increases resistance to infection (3), and reduces mortality (4). In contrast, multiple injections given before irradiation cause no advance in leukocyte recovery or increase in survival (4, 5), even though such injections in nonirradiated mice cause greater increases in spleen weight and resistance to bacterial challenge than a single injection. Till and McCulloch have observed that nodules seen in the spleen 10 days after irradiation are erythroid, granulocytic, megakaryocytic, or mixed (6) and that their number is related to radiation dose and survival (7, 8). The present experiments show that a single injection of endotoxin increases splenic nodules as well as granulocyte count and survival. In contrast, the multiple injections increase the number of splenic nodules (though to a lesser extent) without promoting marrow recovery or survival.

Toxicity of Tritiated Thymidine to Bone Marrow Transplants

Damage in the precursors of blood cells due to incorporation of tritiated thymidine was evaluated in vivo. The parameter measured was the speed of recovery of peripheral blood cells after isologous marrow transplantation in irradiated mice. Donor animals received a total of either 20 or 40 mu C of H/ sup 3/-thymidine per gm of body weight. A delay in recovery was demonstrable only with small inocula, even after the very large doses of triated thymidine were administered. (auth)

KINETICS OF COLCHICINE-INDUCED HEMOPOIETIC RECOVERY IN IRRADIATED MICE.

The recovery of bone marrow and splenic hemopoiesis was studied in irradiated mice given colchicine either 2 days before or shortly after wholebody irradiation. The preirradiation treatment accelerates both marrow and splenic regeneration, with resulting increased survival due to early recovery of normal granulocyte levels. Postirradiation treatment accelerates splenic erythropoietic regeneration, but fails to improve marrow regeneration, resulting in persistent granulocytopenia and in death rates similar to that found in the controls. Colony-forming units, as assayed by Till and McCullochs method, responded similarly. They recovered earlier in the marrow of the pretreated animals, but failed to do so in the marrow of mice that received colchicine after irradiation. In contrast, the time of recovery of splenic CFU was advanced with postirradiation treatment as well as with treatment given 2 days before irradiation. The observations presented add to the mounting evidence that either committed and noncommi...

Humoral regulation of erythropoiesis. IV. Relative heat stability of erythropoietine

Summary and Conclusions Stimulation of erythropoiesis in the sublethally irradiated or hypophysectomized rats was demonstrable following injection of a 3-fold concentrated acidified boiled extract of plasma from either rats exposed to simulated altitude or rabbits with phenylhydrazine-induced anemia. No relationship could be established between activity and coexisting liver disease in phenyl-hydrazine-treated animals. It was estimated that 70-90% of the erythropoietic activity was destroyed by heating acidified plasma at 100° for 10 minutes. Heating for 60 minutes did not further reduce activity. It is suggested that the small fraction of residual activity present after prolonged boiling does not warrant the designation of erythropoietine as a heat stable material nor does it necessitate the assumption of a separate heat stable component, although it does not entirely exclude this possibility.

In vitro effects of chlorpromazine and meprobamate on blast transformation and chromosomes.

Summary The effects of chlorpromazine and meprobamate on chromosomes, blast transformation, and mitotic index were investigated in primary cultures of normal human leukocytes. Neither chlorpromazine nor meprobamate raised the rate of chromosome abberrations, when added at different times and in various concentrations. 2 × 10-5 M of CPZ decrease the number of blast cells but increased the mitotic index in 72-hour cultures if added during the first 18 hr. The increase in the mitotic index is apparently due to metaphase arrest (C-mitosis).

Systemic lupus erythematosus.

Lupus is a serious, potentially life-threatening disease. Its natural history is to culminate in a crescendo of autoimmunity and organ involvement. Difficulty arriving at the diagnosis may delay institution of therapy, which although helpful brings new problems. The fundamental understanding of this disease has made major strides. There is no consensus on the likely etiological agent(s), though evidence implicates Epstein-Barr virus, and the genetic approach to understanding etiology is in its infancy. Nevertheless, efficacious treatments are anticipated in the plethora of new biologics likely to have therapeutic effects in lupus, essentially a disease of immune dysregulation.This document relates to methods and materials involved in diagnosing SLE. For example, this document provides arrays for detecting polypeptides that can be used to diagnose SLE in a mammal. In addition, methods and materials for assessing SLE activity, determining the likelihood of experiencing active SLE, and detecting SLE treatment effectiveness are provided herein.

Glutathione in Radiation Injury

Publisher Summary Protection against radiation by preradiation measures for a wide spectrum of living things is now an accomplished fact. The administration of sulfhydryl compounds and the induction of severe hypoxia seem to be the most effective means of reducing the effectiveness of radiation. Chemcial protection against ionizing radiation can be done by (1) protection by cysteine and glutathione and (2) chronological development of information about sulfhydryl protection. The chapter also explains the experiments to investigate comparative effects of para-aminopropio-phenone (PAPP) and glutathione (GSH) as protective agents against radiation injury. It also discusses the experiments designed to investigate primary destruction and regenerative ability in nontreated and glutathione-pretreated mice.