Cell kinetics and cancer therapy: history, present status, and challenges.
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Biomedical subjects
Publications and source records attributed to S Perry.
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A population of lymphocytes, separable from the great majority by virtue of their larger size and their failure to exhibit the rosetting characteristics of thymus-dependent lymphocytes and bursa-equivalent cells, possess true pluripotentiality. On culture in vivo they proliferate and differentiate into erythrocytic, granulocytic, and megakaryocytic progeny. This may be the first clear demonstration of the primitive progenitor blood cell in man.
Leukocyte kinetic studies using chromium-51 were performed in four patients with acute myelocytic leukemia (AML). Intravascular leukocyte survival was prolonged in comparision with granulocyte survival in normal subjects. Significant splenic pooling occurred in three patients, none of whom had splenomegaly. In one patient studied, circulating leukemic cells were shown to return to the bone marrow. The prolongation of intravascular leukocyte survival in AML in relapse, as in chronic myelocytic leukemia, probably depends on several factors including the presence of immature leukemic cells and the recycling of these cells from the spleen and bone marrow.
The myeloblasts of 16 patients with untreated acute myelogenous leukemia were examined for specific glucocorticoid binding proteins. In only 3 of the 16 patients were such high affinity receptors found. The presence of glucocorticoid binding protein activity was positively correlated with inhibition of macromolecular synthesis of myeloblasts in vitro whereas absence of binding protein activity was associated with lack of glucocorticoid inhibition of the cells. Since glucocorticoids appear efficacious in only a small fraction of cases of acute myelogenous leukemia, determination of glucocorticoid binding protein activity may provide assistance in planning chemotherapeutic regimens.
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The first known step in steroid hormone action is the association of the steroid with specific cytoplasmic steroid-binding proteins (SBP). Using a competitive binding assay, we detected, quantified, and partially characterized such a SBP in cytosol from glucocorticoid-sensitive human lymphoblastic leukemic blasts. The affinity of steroids for the SBP was directly related to their known killing potency. For example, steroids without glucocorticoid effect such as androstenedione, etiocholanolone, and tetrahydrocortisol were unable to displace radiolabeled dexamethasone from the SBP in the binding reaction. The dose-response curve for in vitro inhibition of [(3)H]thymidine uptake in leukemic blasts correlated closely with the binding affinity of glucocorticoids to the SBP, providing additional support for an essential physiologic role for SBP in steroid action. SBP activity was either greatly diminished or absent in glucocorticoid-resistant cells. Six patients who intially had SBP in their blasts and were responsive to combinations of drugs including glucocorticoids no longer had SBP activity detectable at a time when they no longer responded to combinations of drugs including glucocorticoids. In vitro [(3)H]thymidine uptake was not inhibited by steroids in leukemic blast cells lacking SBP activity. Other patients who had received some antileukemic therapy including glucocorticoids and who still had SBP in their leukemic blasts, were still responsive to drug combinations that included glucocorticoids. This appears to be the first study demonstrating glucocorticoid receptors in a human tissue.
Human cyclic neutropenia is characterized by severe depression of blood neutrophil levels approximately every 21 days. To investigate the mechanism of cyclic neutropenia four patients were studied with daily complete blood counts, serial bone marrow examinations, marrow reserve testing, serum muramidase determinations, DF(22)P granulocytokinetic studies, and, in one patient, in vivo [(3)H]TdR labeling. Periodogram analysis of the serial blood counts in the latter patient and visual inspection of multiple cycles in the others revealed periodic fluctuations in the levels of blood neutrophils, monocytes, lymphocytes, reticulocytes, and platelets. Rhythmic changes in the morphologic and radioisotopic studies as well as the marrow reserve tests and muramidase measurements were consonant with a mechanism of periodic failure of marrow production rather than peripheral destruction. Human cyclic neutropenia is analogous to cyclic neutropenia in the grey collie dog and may be viewed as the consequence of cyclic hematopoiesis.
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