Search

The in vitro (3H)thymidine-labeling index of bone marrow myeloblasts was determined in 8 hematologically normal individuals before and after the administration of Bacillus Calmette-Guerin twice weekly for 2 wk. The mean labeling indexes of myeloblasts were 30.5 and 45.2% respectively (P < 0.004). Further characterization of this stimulation of proliferation of bone marrow myeloblasts could provide some rationale for combining cytotoxic drugs and immunotherapy in cancer patients., SCOPUS: NotDefined.j, info:eu-repo/semantics/published

The sensitivities of hematopoietic colony-forming cells (CFC) to N-[4-(9-acridinylamino)-3-methoxyphenyl]-methanesulfonamide (NSC-249992) (m-AMSA) were measured with an in vitro clonogenic assay, a modification of the Robinson and Pike human marrow culture system. CFC derived from bone marrow and peripheral blood of normal subjects and patients with chronic myeloid leukemia (CML) were studied. Sensitivities to m-AMSA did not differ significantly between normal marrow and blood CFC, between normal and CML CFC, or between CML CFC obtained from patients with leukemias in chronic phase and blast transformation. Drug doses and exposure times producing in vitro hematopoietic inhibition were comparable to clinically employed drug dosages and schedules associated with hematopoietic toxicity., Comparative Study, Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

The in vitro [3 H]thymidine-labeling index of bone marrow myeloblasts and myelocytes was determined for 9 hematologically normal individuals and 20 Ph 1 -positive chronic myeloid leukemia (CML) patients in the chronic phase of their disease. The mean labeling index of myeloblasts from CML patients when the white blood cell (WBC) count was lower than 20,000/cu mm (42.4%) was not significantly different from that of normal myeloblasts (49.9). This index was found to be significantly (p < 0.05) decreased to an average of 20.9% when the WBC count was higher than 40,000/cu mm. The mean labeling index of CML myelocytes was not significantly influenced by the level of WBC. The data presented indicate that such variations in the labeling index of the leukemic myeloblasts represent changes of their proliferative activity related to the level of WBC. It is concluded that the proliferation of CML myeloblasts is sensitive, to a certain degree at least, to the size of the myeloid cell population in the body or a subclass of it. © 1976, American Association for Cancer Research. All rights reserved., SCOPUS: ar.j, SCOPUS: ar.j, info:eu-repo/semantics/published

We have compared in various clonogenic assays the in vitro sensitivity to etoposide (VP16) of 1) human leukemic precursors (leukemia colony-forming units; L-CFU), 2) normal erythroid progenitors (erythroid burst-forming units; BFU-E, and 3) normal committed myeloid progenitors (granulocyte-macrophage colony-forming units; CFU-GM and more primitive hemopoietic precursors (PPC) that adhere to cultured marrow stromal cells. Bone marrow samples were obtained from 15 normal subjects and 16 leukemic patients: 9 in the acute phase of acute nonlymphoblastic leukemia (ANLL) and 7 in complete remission. VP16 was tested at concentrations ranging from 10(-8) to 10(-3) M. The median recoveries at 10(-3) M VP16 were respectively 0%, 0.5%, 0%, and 0% for leukemic progenitors, CFU-GM from leukemic patients in complete remission, normal CFU-GM, and BFU-E, and 23% for PPC. This indicates that CFU-GM, BFU-E, and L-CFU are highly sensitive to VP16, whereas PPC, more primitive myeloid precursors, are spared. These results suggest that VP16 may be used as an "ex vivo" purging agent for autologous bone marrow., In Vitro, Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

The proliferative activity of bone marrow myeloblasts was studied by means of tritiated thymidine (3HTdR) and autoradiography. Twenty six patients in the active phase or in complete remission of acute myeloblastic leukemia (AML), 16 in relapse or in remission of chronic leukemia (CML) and 10 hematologically normal reference patients have been investigated. In AML, the 3HTdR labeling index of the myeloblasts returned and remained in the range of normal values during complete remission in the 6 patients examined. In CML, the 3HTdR labeling index of the myeloblasts but not of more mature myeloid cells was normal when the white blood count (WBC) was below 20000/mm3 but was found to decrease when the WBC increased above 20000/mm3. It is concluded that the low labeling indices of myeloblasts during active AML and CML is not an indication of the degree of malignancy of these cells but rather the expression of regulatory mechanisms probably operating on the normal myeloblast and persisting during leukemia., SCOPUS: NotDefined.j, info:eu-repo/semantics/published