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Biomedical subjects

Z Estrov

Publications and source records attributed to Z Estrov.

At least 145 records · Page 8Linked to original sources
PubMed1990

Congenital amegakaryocytic thrombocytopenia: an intrinsic hematopoietic stem cell defect.

Serial studies of bone marrow (BM) hematopoiesis using clonogenic assays were performed in an infant with congenital amegakaryocytic thrombocytopenia. Initially, when the only hematological abnormality was isolated thrombocytopenia, the number of clonogenic BM hematopoietic progenitors was comparable to controls, including the number of megakaryocyte precursors. As the disease evolved into aplastic anemia over an 11-month period, the peripheral blood counts declined, and colony numbers from four classes of BM progenitors--termed BFU-E, CFU-GM, CFU-Mix, and CFU-Meg--also declined in parallel. When added to the marrow cultures, patient's plasma was not inhibitory to either control or to patient's BM colony growth. Similarly, no cellular inhibition of hematopoiesis was observed when patient's BM was cultured after depleting the sample of T lymphocytes and after adding the T lymphocytes back. Furthermore, stromal cells established from short-term and long-term cultures of patient's BM showed normal proliferative activity and yielded a "fertile" marrow microenvironment for patient's and control BM colony growth. Our data suggest that the central problem in congenital amegakaryocytic thrombocytopenia is an intrinsic hematopoietic stem cell defect, rather than an abnormality of the marrow milieu. The findings are consistent with either a progressive, quantitative attrition of progenitors or their inability to proliferate into colonies in vitro and into differentiated, functional cells in vivo.

Blood Cell Count↗
PubMed1989

Circulating mononuclear cells from pure red cell aplasia of chronic lymphocytic leukemia suppress in vitro erythropoiesis.

In vitro studies were performed in a patient with B-cell chronic lymphocytic leukemia who developed pure red cell aplasia (CLL-PRCA). The patient's irradiated circulating mononuclear blood cells and supernatant markedly inhibited normal marrow erythroid (but not granulocyte-monocyte) progenitor colony proliferation. In contrast, irradiated peripheral blood mononuclear cells and supernatant obtained from a B-CLL patient (Rai stage III) and from a hematologically normal donor, did not affect hematopoietic progenitor colony growth. These findings suggest that the anemia of CLL-PRCA evolves different mechanisms of those causing anemia in CLL, and is mediated through cellular and secretory mechanisms.

Aged↗
PubMed1989

Diamond-Blackfan anemia: promotion of marrow erythropoiesis in vitro by recombinant interleukin-3.

To clarify the defective erythropoiesis in eight patients with Diamond-Blackfan anemia, we studied their bone marrow response in vitro to recombinant human interleukin-3 (IL-3) and recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF). In an erythropoietin-containing assay system, specimens from six of the eight patients yielded low numbers of erythroid colonies compared to control values, and in five of these no erythropoietin dose-response could be elicited. Addition of IL-3, GM-CSF or both to cultures from the six patients had no effect on CFU-E-derived colonies. In contrast, IL-3 but not GM-CSF induced a marked increase in the number (183%) and size of the BFU-E-derived colonies in five of the six cases and partially corrected the impaired dose-response to erythropoietin in four. Bone marrow from the other two patients yielded numbers of CFU-E and BFU-E colonies comparable to controls and manifested similar increments in colonies with increasing concentrations of erythropoietin. When IL-3 was added to these cultures, further increments were observed in the number and size of BFU-E colonies. We conclude that IL-3 enhanced the marrow erythropoiesis in most of the patients and exerted a corrective effect on the aberrant colony formation in the presence of erythropoietin. The data raise the possibility of IL-3 as a therapeutic agent in Diamond-Blackfan anemia.

Adolescent↗
PubMed1988

Growth requirements for human acute lymphoblastic leukemia cells: refinement of a clonogenic assay.

Since freshly obtained acute lymphoblastic leukemia (ALL) cells rarely replicate spontaneously in vitro in a sustained way, development of a useful clonogenic assay for ALL blast progenitors is dependent on identifying the cellular growth requirements. Thus, marrows from 25 ALL cases were cultured in methylcellulose to determine the optimal conditions for cell growth. Blast colonies were confirmed as leukemic by morphology, cytochemistry, surface markers, and cytogenetics. Irradiated (7000 rads) normal peripheral blood feeder cells were an absolute requirement and produced number-dependent increases in ALL colonies; added growth factors enhanced the feeder cell effect. ALL cell-feeder cell contact was essential since their physical separation in a two-layer culture system drastically interfered with colony growth. Feeder cells from various donors, including new and relapsed cases of ALL, yielded colony numbers that differed widely when tested on the same marrow with and without added growth factor; thus, identification of a "good" feeder cell donor was key to an optimal assay. Neither recombinant interleukin-2 nor recombinant GM-CSF had ALL growth-promoting properties when tested alone or in combination but in the presence of feeder cells they moderately enhanced the feeder cell effect. The most effective growth factors were derived from cells exposed to phytohemagglutinin (PHA) for 72 h. In order of magnitude for colony growth-promoting activity, PHA-T cell conditioned medium (CM) was more stimulatory than PHA-blast cell CM followed by PHA-leukocyte CM; removal of PHA from CM by affinity chromotography did not alter the results. The most potent PHA-TCM was prepared from T-cells from a phlebotomized hemochromatosis patient; PHA-TCM from transfused thalassemia patients and normal donors were less active. Concanavalin-A blast cell CM had modest colony promoting properties whereas CM prepared with other B-cell mitogens and supernatants from ALL blasts in liquid culture had none. Our studies illustrate the complex and fastidious growth needs of ALL cells. The data have allowed us to refine a clonogenic blast progenitor assay that should facilitate study of proliferative properties of B and T lineage leukemias. The assay could be adapted further for detection of residual leukemia cells in marrow samples used for autologous transplantation, and in patients during complete hematological "remission."

Adolescent↗
PubMed1988

Juvenile chronic myelogenous leukemia.

Juvenile chronic myelogenous leukemia (JCML) is a malignant hematopoietic disorder of monocyte-histiocyte lineage that affects children less than 4 years of age. Since the disease represents only 2% of all childhood leukemias, experience with it has been limited even in large centers. This review summarizes our 10 year institutional study of JCML as well as a comprehensive literature survey. The goal of the article is to underscore the cardinal features of juvenile chronic myelogenous leukemia that are useful for diagnosis, and to highlight recent advances in the understanding of the biology and treatment of the disease.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Synergistic antiproliferative effects on HL-60 cells: deferoxamine enhances cytosine arabinoside, methotrexate, and daunorubicin cytotoxicity.

Deferoxamine (DFO), a widely used therapeutic iron chelator, was found to inhibit proliferation of the promyelocytic leukemia cell line HL-60 in a dose-dependent fashion when tested in a clonogenic assay at concentrations ranging from 1.0 to 10.0 microM. Cytosine arabinoside, methotrexate, and daunorubicin also produced dose-dependent inhibition of HL-60 colony growth when tested singly in vitro. When DFO, 1.0 microM, was included with each agent in dose-response studies, a synergistic enhancement of the antiproliferative effects was observed. This synergism probably results from a DFO-induced decrease in intracellular levels of deoxyribonucleoside triphosphates and an inhibition of the cells at the early S-phase of cell cycle. Our data suggest that DFO has potential as an adjunctive antileukemic agent.

Antimetabolites, Antineoplastic↗
PubMed1988

Modulation of human marrow haematopoiesis by leucotrienes in vitro.

The influence of products derived from the arachidonic acid 5-lipoxygenase (5-LO) pathway on normal human marrow haematopoiesis was studied using clonogenic assays. The leucotrienes (LT) B4 and C4 caused a reduction in granulocyte-macrophage (CFU-GM) as well as erythroid (CFU-E and BFU-E) colony numbers in a dose-dependent manner. Conversely, nordihydroguaiaretic acid (NDGA), a LT synthesis inhibitor, promoted proliferation of these colonies. The inhibitory effect of LTC4 but not that of LTB4 was abolished by FPL-55712, a LT antagonist; the enhanced colony growth induced by NDGA was reversed by both LTB4 and LTC4. LTD4 had no significant effect on colony growth despite its structural similarity to LTC4, which implies that the haematopoietic suppression by LTB4 and LTC4 is specific for these compounds. Depletion of marrow T-cells or removal of adherent cells, or both, did not alter the response to LTB4 and LTC4, suggesting that LT action is exerted directly on progenitor cells and probably is not mediated by other cell populations. Our studies show that the 5-LO pathway is functional in these culture systems and yields products with inhibitory properties. The 5-LO pathway may have an important regulatory function in normal marrow haematopoiesis.

Adult↗
PubMed1987

The value of intensive combination chemotherapy for juvenile chronic myelogenous leukemia.

Nine children with juvenile chronic myelogenous leukemia (JCML) were diagnosed in an 8-year period from 1977 to 1984. The clinical courses and outcomes of five patients who received minimal or no chemotherapy were compared with that of four patients who were treated with intensive acute nonlymphoblastic leukemia (ANLL) combination chemotherapy. None of the five patients in the former group achieved clinical remission and their survivals were 1, 4, 4, 7, and 29 months, respectively. All four patients in the latter group achieved clinical remissions that lasted 11, 21, 21, and 27 + months, respectively. The durations of their survival (21, 26, 30, and 32 + months) were significantly better than the five patients who received minimal or no chemotherapy (P less than .05). Despite hospitalizations for chemotherapy and for treatment of chemotherapy-associated complications, the clinical status and quality of life of the children who achieved clinical remission were superior to those who remained in relapse. Although intensive chemotherapy induced lengthy remissions, three of the four patients have relapsed. Cytogenetic and cell culture data indicated that the monocytic-macrophage cells characteristic of JCML appeared to be suppressed during remission rather than totally eliminated. We recommend that ANLL-type combination chemotherapy be used as the initial treatment of JCML because of its promptness in effecting clinical remissions. Improved maintenance and consolidation protocols have to be developed to produce durable remissions and cures. Alternatively, bone marrow transplantation may be a useful option soon after remission is achieved with chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Recombinant human interferon alpha-2 and juvenile chronic myelogenous leukemia: cell receptor binding, enzymatic induction, and growth suppression in vitro.

Recombinant human leukocyte interferon (HuIFN alpha 2) was studied to determine its potential as a therapeutic agent for the lethal monocytic malignancy of infancy, juvenile chronic myelogenous leukemia (JCML). In sharp contrast to cell cultures of normal marrow, specimens from two patients with JCML yielded an excessive and rapid proliferation of monocyte-macrophage elements without growth factor in clonogenic assay and in liquid culture. Using IFN alpha 2 labeled with 125I, the characteristics of IFN binding to cultured JCML monocyte-macrophages and their receptor site numbers were determined. IFN binding to cells from both patients disclosed two components: a high-affinity of 120 and 430 sites/cell, and a lower affinity of 1230 and 2500 sites/cell, respectively. In control studies, normal blood mononuclear cells or tonsillar B-lymphocytes displayed only a high-affinity component. Brief exposure of JCML cells to IFN alpha 2 in vitro resulted in a sharp increase in the IFN-induced enzyme 2-5A synthetase, indicating the ability of JCML cells to respond metabolically. Dose-response studies performed in a clonogenic assay showed a dose-dependent growth inhibition of JCML monocyte-macrophage colonies using IFN alpha 2 at concentrations of 10(2)-10(5) U/ml. These studies provide new information on the biological characteristics of JCML malignant cells, and suggest that IFN may be useful for treatment of this disorder.

2',5'-Oligoadenylate Synthetase↗
PubMed1987

The regulatory role of interleukin 2-responsive T lymphocytes on human marrow granulopoiesis.

The effect of recombinant interleukin 2 (IL2) on marrow CFU-C colony formation was evaluated to define the role for T lymphocytes in human marrow granulopoiesis. The colony-stimulating factor (CSA) used in our experiments was found to contain IL2. IL2 depletion from CSA resulted in a reduction in CFU-C colony proliferation. Addition of exogenous IL2 caused an increase in CFU-C colony numbers in a dose-dependent manner. This increase could be prevented by anti-Tac, a monoclonal antibody (MoAb) to the IL2 receptor. Moreover, anti-Tac in the absence of exogenous IL2 resulted in an overall decrease in colony numbers. Depletion of either adherent cells or T lymphocytes abolished the effect of IL2 and anti-Tac on colony growth. In the presence of IL2, re-addition of T lymphocytes to the T-depleted marrow or adherent cells to adherent cell-depleted marrow resulted in a significant increase in CFU-C colony numbers, whereas no significant effect was found when IL2-depleted CSA was used. Although T lymphocytes were not themselves essential for CFU-C colony growth, our studies indicate that IL2 and IL2-responsive T cells can regulate in vitro granulopoiesis.

Antibodies, Monoclonal↗
PubMed1987

Effect of deferoxamine on DNA synthesis, DNA repair, cell proliferation, and differentiation of HL-60 cells.

The ribonucleotide reductase inhibitors deferoxamine and hydroxyurea induce monocyte-macrophage cell differentiation in the leukemic cell line HL-60 as judged by the expression of cell surface antigens, nonspecific esterase activity, and morphological changes. Treatment of HL-60 cells with deferoxamine results in inhibition of DNA synthesis and irreversible loss of colony-forming ability. In addition, both deferoxamine and hydroxyurea caused an increase in the number of DNA strand breaks in HL-60 cells. A DNA methylating agent, N-methyl-N'-nitro-N-nitrosoguanidine, also caused cellular differentiation in HL-60 cells associated with DNA strand breaks. These observations are consistent with a role for DNA damage or for inhibition of DNA synthesis and repair in the differentiation process of HL-60 cells.

Antigens, Surface↗
PubMed1987

Residual juvenile chronic myelogenous leukemia cells detected in peripheral blood during clinical remission.

At diagnosis peripheral blood (PB) or bone marrow from patients with juvenile chronic myelogenous leukemia (JCML) have shown two reproducible abnormalities when studied in cell culture: impaired growth of normal hematopoietic progenitors and excessive proliferation of malignant monocyte-macrophage elements. We used these findings to assess quality of treatment response by serially studying PB specimens from four JCML patients (patients 5, 7, 8, and 9) in complete chemotherapy-induced remission. PB readily yielded high numbers of monocyte-macrophage colonies in CFU-C and CFU-GEMM assays when cultured in early remission, and the colonies were cytogenetically proven to have arisen from a malignant clone in patient 9. When studied later in remission, the abnormal cell proliferation persisted in three of the four patients, but in patient 8 PB colony growth resembled controls. Similarly, when PB from patient 8 was studied in liquid culture without using added growth factor, cell proliferation declined identical to controls, whereas PB from the other three patients showed exuberant growth of monocyte-macrophage elements. Patient 8 successfully completed therapy and has been in a long-term, disease-free remission. The other three had recurrent, ultimately fatal disease. The cell cultures have allowed detection of residual abnormal cells that circulate in PB of JCML patients in remission. Although patient numbers were small because of the rarity of JCML, the data suggested that persistence of leukemia cells in these patients had a bearing on clinical outcome.

Antigens, Surface↗
PubMed1987

In vitro and in vivo effects of deferoxamine in neonatal acute leukemia.

A six week old infant with acute leukemia failed to attain remission with chemotherapy. Because we previously demonstrated that the iron chelator deferoxamine (DFO) has antiproliferative properties and modulatory effects on cell differentiation, a protocol was designed for in vitro study and for clinical use in the patient. At diagnosis, blast cells were morphologically undifferentiated, had nondiagnostic cytochemistry, showed an abnormal karyotype (t[4;11]), expressed markers of B cell lineage, and demonstrated C mu gene rearrangement. Tissue culture of marrow or blood cells yielded colonies of leukemic blasts. Increasing concentrations of DFO produced a dose-dependent suppression of patient's blast colony growth in vitro, and blasts within colonies showed a marked change in surface antigen expression from lymphoid to myelomonocytic markers, became monocytic in appearance, and developed intense staining for nonspecific esterase. When DFO was given intravenously to the patient as a single agent for 48 hours, blasts no longer expressed lymphoid antigens and became strongly positive for myelomonocytic markers, identical to the in vitro findings. Intravenous DFO halted rising peripheral blood blast cell numbers and allowed a several-fold increase in normal hematopoietic progenitor colony growth. When combined with low-dose cytosine arabinoside in the treatment protocol, DFO caused striking leukemic cytoreduction. Our findings indicate that DFO has antileukemic properties by virtue of its effects on proliferation and differentiation, and they prompt further experimental and clinical studies with this agent.

Antigens, Neoplasm↗
PubMed1986

Detection of residual acute lymphoblastic leukemia cells in cultures of bone marrow obtained during remission.

We used a semisolid culture assay to quantitate leukemia cells in the bone marrow of patients with childhood acute lymphoblastic leukemia (ALL). In bone marrow cultures from 40 patients with newly diagnosed disease, the colonies that developed in vitro consisted of lymphoblasts with the same surface markers and abnormal karyotype as the original diagnostic marrow specimens. We also studied marrow cultures from 13 patients in chemotherapy-induced remission; 6 of these, including 1 obtained from a patient during successful engraftment after marrow transplantation, also yielded lymphoblast colonies in culture, with the same immunologic phenotype or abnormal karyotype as the original leukemic marrow. Four of these patients, including the one who underwent marrow transplantation, relapsed within 2 to 30 months of the abnormal cultures; the other two are still in remission, one of them 30 months after diagnosis. Bone marrow cultures from eight normal controls and from the other seven patients in remission did not yield lymphoblast colonies; all seven of the latter are still in remission. This assay appears to allow detection of small numbers of residual leukemic cells. We conclude that the technique will be valuable in monitoring the efficacy of chemotherapy and allogeneic bone marrow transplantation in acute lymphoblastic leukemia, as well as in evaluating the quality of purged marrow for autologous marrow transplantation.

Antigens, Surface↗
PubMed1986

Clinical utility of marrow cell tissue cultures in acute leukemia of childhood.

To determine the clinical value of tissue culture techniques in the study of acute leukemia, marrows from 50 children (40 acute lymphoblastic [ALL], 10 acute myeloblastic [AML]) were cultured by the use of an AML blast colony assay and the CFU-GEMM assay. In the AML assay, AML marrow gave rise to high numbers of blast colonies within 24 to 48 hr; in sharp contrast, 37 of 40 ALL marrows did not yield colonies in this assay. In the CFU-GEMM assay, AML marrow produced excessive numbers of monocyte-macrophage CFU-C colonies, an obvious background of individual macrophages and clusters, and occasional blast colonies. ALL marrow yielded very low numbers of granulocytic CFU-C colonies, no background of macrophage cells, and no blast colonies. These clear-cut differences in cellular growth kinetics in vitro between ALL and AML marrows should allow confirmation of the type of acute leukemia within 24 to 48 hr. The colony assays may also be valuable in differentiating ALL from AML in difficult diagnoses when conventional approaches are nondiagnostic.

Acute Disease↗
PubMed1986

Selective protection of tubercidin toxicity by nitrobenzyl thioinosine in normal tissues but not in human neuroblastoma cells.

Tubercidin, an adenosine analogue, is toxic to human neuroblastoma cell lines, to peripheral blood mononuclear cells (PBMCs), and to myeloid colony-forming cells (CFU-C) as tested by a short-term labeled precursor uptake and by a clonogenic assay. When it was co-administered with a potent purine transport inhibitor, nitrobenzyl thioinosine (NBTI), the cytotoxic effect of tubercidin was abolished in PBMCs but not in neuroblastoma cells. Studies of nucleoside transport in neuroblastoma cells demonstrate that although [3H]NBTI binds to the plasma membrane of these cells, the transport of thymidine into the cells is only partially inhibited in the presence of excess NBTI. These data imply that neuroblastoma cells contain a nucleoside transport mechanism which is insensitive to NBTI. "Host protection" with a nucleoside transport inhibitor such as NBTI, may allow effective therapy with otherwise toxic dosages of tubercidin and other cytotoxic nucleosides in patients with neuroblastoma.

Biological Transport↗