bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear-induced platelet aggregation can be mediated by vWF released from platelets, as well as by exogenous large or unusually large vWF multimers, requires adenosine diphosphate, and is resistant to aspirin
Authors: Moake JL , Turner NA , Stathopoulos NA , Nolasco L , Hellums JD
Published: October 2019

Fluid shear stress in arteries and arterioles partially obstructed by atherosclerosis or spasm may exceed the normal time-average level of 20 dyne/cm2. In vitro, at fluid shear stresses of 30 to 60 dyne/cm2 applied for 30 seconds, platelet aggregation occurs. At these shear stresses, either large or unusually large von Willebrand factor (vWF) multimers in the suspending fluid exogenous to the platelets mediates aggregation. Adenosine diphosphate (ADP) is also required and, in these experiments, was released from the platelets subjected to shear stress. At 120 dyne/cm2, the release of endogenous platelet vWF multimers can substitute for exogenous large or unusually large vWF forms in mediating aggregation. Endogenous released platelet vWF forms, as well as exogenous large or unusually large vWF multimers, must bind to both glycoproteins Ib and the IIb/IIIa complex to produce aggregation. Shear- induced aggregation is the result of shear stress alteration of platelet surfaces, rather than of shear effects on vWF multimers. It is mediated by either large plasma-type vWF multimers, endogenous released platelet vWF forms, or unusually large vWF multimers derived from endothelial cells, requires ADP, and is not inhibited significantly by aspirin. This type of aggregation may be important in platelet thrombus formation within narrowed arterial vessels, and may explain the limited therapeutic utility of aspirin in arterial thrombosis.
Allogeneic marrow grafting with partially mismatched, unrelated marrow donors
Authors: Gingrich RD , Ginder GD , Goeken NE , Howe CW , Wen BC , Hussey DH , Fyfe MA
Published: October 2019

Forty patients with advanced hematologic malignancies or severe aplastic anemia received marrow grafts from partially mismatched, unrelated marrow donors. All patients were administered conventional prophylaxis for acute graft-v-host disease (GVHD) consisting of methotrexate and low-dose glucocorticoids. All but two patients who survived at least 30 days showed durable engraftment. Six patients survive 17+ to 36+ months following transplantation. Severe acute GVHD was seen in 47% of the patients; however, no direct correlation between GVHD and the degree of mismatching could be determined. Fatal infections were seen in 29 patients, and in the majority the infection occurred after the granulocyte count had risen to greater than 500 cells/microL. We conclude that the problems encountered in this pilot study can potentially be solved, and that further studies with this type of marrow grafting are warranted.
B19 parvovirus replicates in circulating cells of acutely infected patients
Authors: Kurtzman GJ , Gascon P , Caras M , Cohen B , Young NS
Published: October 2019

B19 parvovirus is the etiologic agent of fifth disease and transient aplastic crisis. In natural infections, B19 antigen and DNA have been detected in sera early in the course of aplastic crisis and only rarely in fifth disease. We have found B19 DNA in circulating cells of infected patients by DNA dot blot with a virus-specific probe: in four of four sickle cell patients with aplastic crisis, in one asymptomatic sibling, and in one normal adult with fifth disease. Only two of the sera showed B19 DNA. High-molecular weight intermediate forms were detected by Southern analysis of DNA extracted from cells, thus indicating active replication of virus in cells rather than passive adsorption to their surface membranes. Separation of cells into high- and low-density fractions resulted in a concentration of the virus DNA in the granulocytic fraction.
Fibrinogen-derived peptide B beta 1-42 is a multidomained neutrophil chemoattractant
Authors: Skogen WF , Senior RM , Griffin GL , Wilner GD
Published: October 2019

The formation and degradation of fibrin play a central role in hemostasis, but other activities have been associated with fibrin(ogen)- derived peptides, which suggests that products of fibrin(ogen) turnover may be involved in inflammation and wound healing. The present study was undertaken to determine whether the plasmic fibrinogen-derived peptide B beta 1–42 has effects on inflammatory cells and fibroblasts (FB). B beta 1–42 was found to be a potent chemotaxin for neutrophils (PMN) and FB, maximally stimulating PMN migration at 10(-9) mol/L peptide. Unlike the chemotactic factors f-Met-Leu-Phe and C5a, B beta 1– 42 did not induce the release of lysosomal hydrolases and superoxide anion from PMN, nor did it stimulate directed movement of monocytes (MN). These features of B beta 1–42 resemble the properties of human fibrinopeptide B (hFpB), the 14-reside, thrombin-cleaveable fragment that constitutes the amino terminus of B beta 1–42, and suggested that the chemotactic effects of B beta 1–42 are mediated through its hFpB domain. Against this conclusion, however, were observations that (a) desensitization of PMN with 10(-7) mol/L hFpB ablated chemotaxis to hFpB without affecting chemotaxis to B beta 1–42; (b) antiserum to hFpB, which recognizes the B beta 1–14 sequence both free and bound to larger fragments of the B beta chain, blocked hFpB chemotactic activity but did not affect B beta 1–42-mediated chemotaxis; (c) desensitization of PMN with equimolar amounts of hFpB and beta 15–42 (10(-7) mol/L), the isolated carboxyterminal sequence of B beta 1–42 remaining after the removal of hFpB, completely inhibited B beta 1–42-mediated chemotaxis; and (d) beta 15–42 itself was chemotactic for PMN. These data indicate that PMN recognize several independent domains within the amino terminal region of the human fibrinogen B beta chain and that these biologic effects extend to mesenchymal cells.
Molecular analysis of clonality and bcr rearrangements in Philadelphia chromosome-positive acute lymphoblastic leukemia
Authors: Turhan AG , Eaves CJ , Kalousek DK , Eaves AC , Humphries RK
Published: October 2019

Philadelphia chromosome (Ph1)-positive chronic myelogenous leukemia (CML) patients consistently show a rearrangement in a 5.8-kilobase length of chromosome 22, referred to as the breakpoint cluster region (bcr). In Ph1-positive acute lymphoblastic leukemia (ALL), the breakpoint in chromosome 22 is more heterogeneous and, in some instances, does not occur within this region. In such cases the cell of origin of the neoplastic clone and the relationship of the disease to CML has remained obscure. We have analyzed the bcr rearrangement in the malignant cells from three patients who presented with Ph1-positive ALL and who in cytogenetic studies had shown evidence of variable involvement of myeloid cells in the Ph1-positive clone. Rearrangements in bcr typical of most cases of CML were detected in purified granulocyte preparations from two of the ALL patients (nos. 1 and 2) and in the blasts from patient 3 at the time of her terminal relapse. In the same analysis the simultaneously obtained granulocytes from patient 3, however, did not show any evidence of bcr rearrangement. Patient 3 was also heterozygous for the BamHI polymorphism in the X- linked hypoxanthine phosphoribosyltransferase (HPRT) gene, thus permitting a different method of clonal analysis based on methylation differences in active and inactive alleles. When DNA from her granulocytes that had shown no bcr rearrangement was hybridized to an HPRT probe, a pattern typical of a polyclonal population was seen. A similar pattern was exhibited by her marrow fibroblasts. In marked contrast, her simultaneously isolated blasts showed an unambiguous monoclonal pattern. These findings demonstrate the origin of the disease in the first two patients in a cell with myelopoietic as well as lymphopoietic potential and confirm the restricted lymphoid cell origin of the neoplastic clone in the third Ph1-positive ALL patient. Furthermore, they indicate that different target cells for transformation within the hematopoietic system may be affected by very similar bcr rearrangements.
Anti-RH immunoglobulin therapy for human immunodeficiency virus-related immune thrombocytopenic purpura
Authors: Oksenhendler E , Bierling P , Brossard Y , Schenmetzler C , Girard PM , Seligmann M , Clauvel JP
Published: October 2019

The potential hazards of steroids in human immunodeficiency virus (HIV)- infected patients led us to evaluate the effectiveness and safety of anti-D and anti-c Ig in 17 adults with severe HIV-related immune thrombocytopenic purpura (platelet count less than 20 x 10(9)/L). The 14 Rh+ patients received 12 to 25 micrograms/kg of anti-D IgG intravenously on two consecutive days. A significant platelet rise above 50 x 10(9)/L was obtained in nine patients. Repeated boosters were performed in six cases and were effective in all cases. The 3 Rh- patients had a good response after they were given 20 mL x 2 of plasma containing potent anti-c antibodies. Therapy was well tolerated, and only one patient had significant hemolysis. These data suggest that anti-Rh IgG can be effective and safe in HIV-related thrombocytopenic purpura and that a specific interaction between the RBC antigens and the anti-Rh antibodies is required.
Ambiguous phenotypes and genotypes in 16 children with acute leukemia as characterized by multiparameter analysis
Authors: Ludwig WD , Bartram CR , Ritter J , Raghavachar A , Hiddemann W , Heil G , Harbott J , Seibt-Jung H , Teichmann JV , Riehm H
Published: October 2019

Ambiguous phenotypes and genotypes were observed in 16 children with acute leukemia. Surface marker, cytogenetic, molecular genetic, and DNA flow cytometric analyses as well as standard morphologic and cytochemical studies were used to divide the patients into three groups. The first group comprised five children with acute leukemia whose blast cells were morphologically lymphoid, while immunophenotyping disclosed simultaneous expression of early pre-B cell and myeloid features. Molecular genetic studies showed evidence of heavy-chain immunoglobulin (Ig) gene rearrangements in all patients. Cytogenetic data, available in three of these children, revealed t(4;11). In five of the 16 patients, morphologic and surface marker analyses indicated the coexistence of two separate cell populations, one with myeloid and the other with early pre-B cell features. Further evidence of B cell commitment in these patients was provided by demonstration of Ig heavy-chain gene rearrangements in all five patients. Surprisingly, one of the five patients showed oligoclonal Ig heavy-chain as well as monoclonal gene rearrangement for the beta chain of the T cell receptor (beta-TCR). The last group consisted of four cases with otherwise typical acute lymphoblastic leukemia (ALL), early pre-B cell phenotype, and coexpression of myeloid or T cell-associated antigens, and two children with unequivocal acute myeloid leukemia (AML) and coexpression of T cell antigens. Gene rearrangement of Ig heavy-chain could be demonstrated in five of six patients, additional Ig light-chain gene rearrangement in two children with ALL, and bigenotypic features (Ig heavy-chain and beta-TCR gene rearrangement) in one patient. In none of the 16 patients did flow cytometry disclose clonal abnormalities of leukemic cell DNA content. Based on these findings, we suggest that malignant transformation in the first and second group of patients took place at a stage ontogenetically close to the pluripotent stem cell, whereas ambiguous phenotypes in the third group resulted from aberrant gene expression or insufficient reagent specificity.
Methylthioadenosine phosphorylase deficiency in acute leukemia: pathologic, cytogenetic, and clinical features
Authors: Traweek ST , Riscoe MK , Ferro AJ , Braziel RM , Magenis RE , Fitchen JH
Published: October 2019

Blast cells from 100 cases of acute leukemia were evaluated for the presence of methylthioadenosine phosphorylase (MTAase), an enzyme important in polyamine metabolism. Ten cases (10%) had undetectable levels of MTAase activity. Of the 10, 5 had acute lymphoblastic leukemia (ALL), 3 had acute myeloblastic leukemia (AML) and 2 expressed mixed lineage markers as determined by immunophenotyping. A relatively high frequency (38%) of MTAase deficiency was seen in ALL of T-cell origin. Nonmalignant hematopoietic cells from three patients with MTAase-deficient leukemias had readily detectable enzyme activity. Chromosomal abnormalities were detected in four of the seven MTAase- deficient cases in which karyotypic analysis was performed. No consistent karyotypic defect was apparent, and only one case displayed changes in chromosome 9, the putative location of the MTAase structural gene. The clinical findings among the enzyme-deficient cases were unremarkable except that all patients were male (P less than .01). Only one patient had “lymphomatous” features. We conclude that MTAase deficiency occurs in a wide variety of acute leukemias, that the lack of enzyme activity is specific to the malignant cells, and that an increased incidence occurs in ALL of T-cell origin. Furthermore, no specific gross chromosomal abnormality is associated with the enzyme deficiency. The marked male predominance in patients with MTAase- deficient acute leukemias suggests involvement of the X chromosome in the loss of enzyme activity. The absence of MTAase in some leukemias may be therapeutically exploitable.
Activation and proliferation signals in murine macrophages: synergistic interactions between the hematopoietic growth factors and with phorbol ester for DNA synthesis
Authors: Hamilton JA , Vairo G , Nicola NA , Burgess A , Metcalf D , Lingelbach SR
Published: October 2019

There has been recent interest in the synergistic interactions between the growth factors involved in the in vitro control of hematopoiesis and other cell lineages. As a convenient model system, such interactions governing the DNA synthesis in murine bone marrow-derived macrophages (BMMs) were studied. By themselves, murine colony- stimulating factor-1 (CSF-1) and recombinant murine granulocyte- macrophage CSF (GM-CSF) were stimulators of DNA synthesis in quiescent or noncycling BMMs, whereas recombinant murine interleukin-3 (IL-3) and the phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), were weak mitogens. On the other hand, murine granulocyte CSF (G-CSF), concanavalin A (Con A), and lipopolysaccharide (LPS) were inactive on their own. When the quiescent BMMs were exposed to combinations of the CSFs, there were striking synergistic effects for both GM-CSF and IL-3 with suboptimal doses of CSF-1, with a smaller effect for GM-CSF with IL-3 and little or no effect for CSF-1 with G-CSF. CSF-1, GM-CSF, and IL-3 could also synergize with TPA; CSF-1 cooperated with 1-oleoyl-2- acetylglycerol (OAG), both sets of results pointing to an interaction with protein kinase C. LPS completely abolished the CSF-1-mediated stimulation of DNA synthesis. We propose that BMMs are suitable normal cells in which to examine in depth the various mechanistic possibilities for these interactions.
The Wistar Furth rat: an animal model of hereditary macrothrombocytopenia
Authors: Jackson CW , Hutson NK , Steward SA , Ashmun RA , Davis DS , Edwards HH , Rehg JE , Dockter ME
Published: October 2019

The mechanisms that determine and regulate platelet size are unknown. By phase microscopy, we observed that Wistar Furth (WF) rats had macrothrombocytopenia. In this study, we have characterized and compared platelets and megakaryocytes of WF rats with those of Wistar, Long-Evans hooded (LE), and Sprague-Dawley rats. In addition, we have examined the mode of inheritance of this WF rat platelet abnormality. The average platelet count of WF rats was only one-third that of the other three rat strains. In contrast, the mean platelet volume (MPV) of adult WF rats was twice that of the other rat strains; however, the average megakaryocyte diameter and DNA content distribution of WF rats were not significantly different from those of LE rats. The average megakaryocyte concentration was 30% lower in the WF strain compared with that of LE rats. Mazelike membrane formations were observed in WF platelets and megakaryocytes by electron microscopy. Reciprocal crosses of WF and LE rats resulted in offspring with MPVs and platelet counts like those of LE rats, indicating that the macrothrombocytopenic trait is recessive in its inheritance. Reciprocal marrow transplants between the WF and LE strains resulted in MPVs like those of the donor strain, demonstrating that the macrothrombocytopenia is an intrinsic marrow abnormality of the WF strain. Splenectomy did not alter the MPV of WF rats. The response of WF megakaryocytes and platelets to severe, acute thrombocytopenia was similar to that of LE rats except that the shift to higher megakaryocyte DNA contents was muted and platelet recovery was slower in the WF rats. In summary, the WF rat has a hereditary macrothrombocytopenia that is recessive in nature and not due to differences in megakaryocyte size or DNA content. These results suggest that the macrothrombocytopenia of WF rats results from the formation of fewer platelets per megakaryocyte, possibly resulting from a qualitative or quantitative defect in some component necessary for proper subdivision of megakaryocyte cytoplasm into platelets.
Mutation of Ki-ras and N-ras oncogenes in myelodysplastic syndromes
Authors: Lyons J , Janssen JW , Bartram C , Layton M , Mufti GJ
Published: October 2019

Somatic mutation of the N-ras oncogene occurs frequently in de novo acute myeloid leukemia (AML). By virtue of their relation to AML, myelodysplastic syndromes (MDS) provide an in vivo model of human leukemogenesis. By using a strategy for analysis of gene mutation based on in vitro amplification of target sequences by the polymerase chain reaction (PCR) and selective oligonucleotide hybridization we analyzed the mutational status of codons 12, 13, and 61 of Ha-ras, K-ras, and N- ras in peripheral blood (PB) and/or bone marrow (BM) in 34 cases of primary MDS. Mutations at codon 12 of Ki-ras or N-ras were detected in three cases (9%): one of six cases of refractory anemia with excess blasts (RAEB) and two of nine cases of chronic myelomonocytic leukemia (CMML). The nucleotide substitution differed in each. In all cases the mutant allele was detectable in PB cells. A sustained hematologic remission was achieved after low-dose cytarabine therapy in the case of RAEB. Neither case of CMML exhibited signs of disease progression during follow-up at 7 and 12 months. In contrast, four of 31 patients without the ras mutation underwent transformation to AML within 12 months of genetic analysis. We conclude that ras mutations in MDS are heterogeneous and may develop at an early stage during the evolution of MDS. Their detection in PB cells illustrates the potential utility of ras mutation as a clonal marker in myeloid malignancy.
K562 cells produce and respond to human erythroid-potentiating activity
Authors: Avalos BR , Kaufman SE , Tomonaga M , Williams RE , Golde DW , Gasson JC
Published: October 2019

Human erythroid-potentiating activity (EPA) is a 28,000 mol wt glycoprotein that stimulates the growth of erythroid progenitors in vitro and enhances colony formation by the K562 human erythroleukemia cell line. EPA has potent protease inhibitory activity, and is also referred to as tissue inhibitor of metalloproteinases (TIMP). We observed that colony formation by K562 cells in semi-solid medium containing reduced fetal calf serum (FCS) is not directly proportional to the number of cells plated, suggesting production of autostimulatory factors by K562 cells. Using radioimmunoprecipitation and a bioassay for EPA, medium conditioned by K562 cells was found to contain high levels of biologically active EPA; Northern hybridization analysis confirmed the expression of EPA mRNA. Radiolabeled EPA was used to identify cell surface receptors on K562 cells. Together, these results suggest that EPA may act as an autocrine growth factor for K562 cells.
Use of a sensitive bioimmunoabsorbent assay to isolate and characterize monoclonal antibodies to biologically active human erythropoietin
Authors: Wognum AW , Lansdorp PM , Eaves CJ , Krystal G
Published: October 2019

At present, one of the most sensitive assays for human erythropoietin (Ep) is a bioassay that measures the Ep-dependent proliferation of spleen cells from phenylhydrazine-treated mice after 24 hours in culture. We describe how this assay can be used as the basis of a very sensitive method for detecting mouse antibodies to biologically active human Ep. In this procedure, microtiter wells are first coated with goat anti-mouse Ig antibody, then treated with mouse antibodies (serum or hybridoma culture supernatants), and finally incubated with a fixed amount of pure human Ep. Specific binding of anti-Ep antibodies is detected by adding spleen cells from phenylhydrazine-treated mice to the wells and measuring the ability of the cells to incorporate 3H- thymidine 24 hours later. This bioimmunosorbent assay (BISA) revealed the presence of anti-EP antibodies in sera from mice immunized with either pure human urinary Ep or a synthetic dodecapeptide corresponding to the aminoterminal region of Ep and in the culture supernatants from three of eight stable anti-Ep antibody-producing hybridoma cell lines that we have isolated. The three monoclonal antibodies showed similar reactivities in the BISA, but showed different affinities for Ep, with Kd values of approximately 0.7, 8, and 240 nmol/L, respectively. Further studies showed that all antibodies were capable of neutralizing Ep bioactivity and of binding 125I-labeled Ep in a radioimmunosorbent assay (RIA) but were virtually unreactive to Ep adsorbed to the bottom of enzyme-linked immunosorbent assay (ELISA) wells. Our results suggest that the BISA strategy may be an important complement to conventional RIA and ELISA techniques for identification of monoclonal antibodies specific for biologically active growth factors.
Restriction of expression of an integrated recombinant retrovirus in primary but not immortalized murine hematopoietic stem cells
Authors: Williams DA , Lim B , Spooncer E , Longtine J , Dexter TM
Published: October 2019

A recombinant retrovirus (DHFR*-SVADA) in which human adenosine deaminase (ADA) cDNA is transcribed from an internal SV40 promoter was used to infect murine hematopoietic stem and progenitor cells. Human ADA enzyme was not expressed in infected primary murine pluripotent stem cell-derived spleen or progenitor colonies (CFU-GM, CFU-Mix, BFU- E). In contrast, human ADA enzyme activity was readily detected in progenitor colonies derived from immortalized multipotent factor- dependent cells. The level of human enzyme was near endogenous murine enzyme levels and was equivalent in undifferentiated stem cells and differentiated myeloid, erythroid, and mixed colonies. These results indicate that cellular properties other than the stage of differentiation are important in determining the expression of foreign sequences introduced by retroviruses. Cell lines that are immortalized but still capable of induced differentiation may contain factors that abrogate blocks to expression that are manifested in primary hematopoietic stem cells.
Detection of hemin release during hemoglobin S denaturation
Authors: Liu SC , Zhai S , Palek J
Published: October 2019

Sickle hemoglobin is relatively unstable upon oxidation or mechanical shaking. During denaturation, it generates oxygen radicals and hemichromes and ultimately precipitates in the form of micro-Heinz bodies. It is not clear, however, whether the degradation product hemin, which is a potent hemolytic agent and a potential perturbant to protein-protein interactions in the red cell membrane skeleton, is also generated during sickle hemoglobin denaturation. By specific absorption of hemin with Dowex AG 1-X8 anion-exchange resin at high-ionic strength conditions, we now separate hemin for quantitation from the bulk hemoglobin and its derivatives. We demonstrate that upon mechanical shaking oxyhemoglobin S denatures much faster than oxyhemoglobin A and that a considerably higher level of hemin is detected in the shaken hemoglobin S as compared with hemoglobin A. By using the same method to measure the hemin content in the hemolysate of fresh red cells from patients with sickle cell disease, we detect a three- to fivefold increase in the hemin content in these patients (0.4 to 0.75 mumol/L) as compared with normal individuals (0.1 to 0.15 mumol/L). These data suggest that the instability of sickle oxyhemoglobin leads to increased intracellular precipitation of hemoglobin and the release of hemin, which may play a role in the membrane lesion of sickle red cells.
Antigen presentation in an HLA-DR-restricted fashion by B-cell chronic lymphocytic leukemia cells
Authors: Yasukawa M , Shiroguchi T , Inatsuki A , Kobayashi Y
Published: October 2019

The ability of B-cell chronic lymphocytic leukemia (B-CLL) cells to present antigen to antigen-specific T cells was investigated. B-CLL cells present herpes simplex virus (HSV) antigen and purified protein derivative (PPD) to HSV- and PPD-specific, interleukin-2-dependent T- cell lines in an antigen-specific manner. Treatment of B-CLL cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) induced markedly increased levels of HLA-DR expression. TPA-treated B-CLL cells showed substantially more effective presentation, especially at low antigen concentrations, than did untreated B-CLL cells. By coculturing different allogeneic combinations of B-CLL cells and T cells and by adding anti-HLA-DR monoclonal antibody to cultures, it was found that antigen presentation by B-CLL cells was restricted by HLA-DR in the same way as for macrophages. We concluded from these experiments that B- CLL cells have a capacity to serve as antigen-presenting cells in an HLA class II-restricted fashion and that increasing the amount of HLA class II antigen and activation of B-CLL cells resulted in effective antigen presentation.
Contractile proteins participate in release of erythroid growth regulators from mononuclear cells
Authors: Dainiak N , Riordan MA , Strauss PR , Feldman L , Kreczko S
Published: October 2019

We have investigated the role of contractile proteins of circulating mononuclear cells in generation of membrane-associated, erythroid growth regulatory molecules. Lymphocytes and monocytes were incubated under serum-free conditions without and with cytochalasin B, cytochalasin D, or colchicine, and effects on positive and negative erythropoietic activities were determined in cell membranes and in surface membrane vesicle-rich pellets and supernatants of dialyzed medium conditioned by the cells. In serum-free cultures of human bone marrow, plasma membranes and exfoliated membrane-derived vesicles from cytochalasin-treated lymphocytes lost their capacity to support the formation of erythroid bursts, while monocyte membrane-associated inhibitory activity was abolished by preincubation with cytochalasin. In contrast, membrane-associated activities of colchicine-treated cells were unaffected. Cytochalasin-induced alterations of membrane regulatory molecules were observed in a dose-dependent fashion over a wide range of concentrations (1 to 100 micrograms/mL) tested. However, the capacity of membrane vesicle-free supernatants of medium conditioned by lymphocytes or monocytes was unaffected by cytochalasins, regardless of drug concentration used. Lysates of cytochalasin B-treated cells inhibited the activity of deoxyribonuclease I to a greater degree than did lysates of untreated cells, suggesting that the relative amount of monomeric actin is increased in the cytoplasm of treated cells. Furthermore, results of experiments with D-glucose and with cytochalasin D suggest that cytochalasin effects are independent of alterations in glucose metabolism. The data indicate that expression of plasma membrane- associated regulators is sensitive to agents that block polymerization of actin. They raise the possibility that changes in distribution of actin between unpolymerized and filamentous pools may influence the organization and/or function of mononuclear cell surface-associated erythroid regulatory molecules.
KRDS--a tetrapeptide derived from lactotransferrin--inhibits binding of monoclonal antibody against glycoprotein IIb-IIIa on ADP-stimulated platelets and megakaryocytes
Authors: Raha S , Dosquet C , Abgrall JF , Jolles P , Fiat AM , Caen JP
Published: October 2019

Short peptides isolated from fibrinogen and K-casein have been shown to inhibit platelet aggregation and fibrinogen binding to stimulated platelets. We studied the effects of synthetic peptides occurring in milk proteins (bovine K-casein, KNQDK, and human lactotransferrin, KRDS) and in fibrinogen (RGDS and L10) on subsequent binding of monoclonal antibodies (MoAb) against the glycoprotein (GP) IIb-IIIa complex (AP2 and P2) on adenosine diphosphate (ADP)-stimulated and unstimulated human platelets and megakaryocytes (MKs) by using an immunoperoxidase method to visualize antibody binding. Only KRDS (900 mumol/L) inhibited the binding of AP2 and P2 on ADP (5 mumol/L)- stimulated platelets, but not on unstimulated platelets. However, the binding of P2 was considerably more inhibited than that of AP2 as judged by immunoperoxidase intensity. Radiolabeled AP2 binding was inhibited by 30% with KRDS on ADP-stimulated platelets as compared with platelets incubated in the absence of ADP. KRDS did not inhibit the binding of MoAbs against GP IIIa (SZ 21), GP IIb (SZ 22), and GP Ib (SZ 2) on ADP-stimulated human platelets. Inhibition of P2 binding by KRDS was also observed in a section of MKs isolated from human bone marrow and stimulated by 15 or 20 micron ADP. A lower concentration of ADP (5 or 10 mumol/L) failed to produce any inhibition of binding. This indicates that MKs may not be equally responsive to agonists as platelets. Moreover, P2 binding inhibition was observed in a larger (P less than .001) percentage of mature MKs (29%) as compared with younger, maturing MKs (11%). The observations suggested that a functional ability possessed by platelets, namely, agonist-induced exposure of the site of interaction of KRDS, may occur at a late stage of MK development.
Plasma vitronectin polymorphism in normal subjects and patients with disseminated intravascular coagulation
Authors: Conlan MG , Tomasini BR , Schultz RL , Mosher DF
Published: October 2019

Vitronectin, also known as serum-spreading factor or S-protein, mediates cell adhesion and inhibits formation of the membrane-lytic complex of complement and the rapid inactivation of thrombin by antithrombin III in the presence of heparin. Vitronectin is normally present in plasma at a concentration of approximately 300 micrograms/mL. The investigators quantified plasma vitronectin with an enzyme-linked immunosorbent assay and visualized reduced and nonreduced vitronectin by immunoblotting after separation of plasma or serum by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The concentration of plasma vitronectin was markedly reduced in some patients with disseminated intravascular coagulation, especially in those with liver failure; it was near normal in patients with metastatic cancer and acute leukemia. Patients with vitronectin levels less than 40% normal invariably had low fibrinogen and antithrombin III and a prolonged prothrombin time. In both normal and patient plasmas there was heterogeneity in the ratio of the 75,000- and 65,000-mol wt polypeptides of reduced vitronectin: 18% had mostly the 75,000-mol wt polypeptide, 59% had roughly equal amounts of the two polypeptides, and 22% had mostly the 65,000-mol wt polypeptide. This polymorphism is inherited and appears to be due to two alleles that are present with approximately equal frequency. The blotting patterns of vitronectin in reduced and nonreduced plasmas were largely unaltered in plasma of patients with defibrination syndrome, fibrinolysis, liver failure, sepsis, metastatic cancer, and acute leukemia. There was no evidence of fragmentation of vitronectin or formation of the disulfide-bonded complex of vitronectin and thrombin-antithrombin III that is found when blood is clotted. Thus these results corroborate in vitro observations that the liver is the major source of plasma vitronectin, suggest that vitronectin may become depleted during disseminated intravascular coagulation, and define a genetic polymorphism of vitronectin.
Exposure of platelet fibrinogen receptors by a monoclonal antibody to CD9 antigen
Authors: Hato T , Ikeda K , Yasukawa M , Watanabe A , Kobayashi Y
Published: October 2019

We found that a monoclonal antibody to CD9 antigen, PMA2, induces fibrinogen binding to platelets and examined the mechanism for this. That PMA2 recognized the CD9 antigen was confirmed by its immunoblot- reactivity with a 24,000-dalton protein, reactivity with platelets and common acute lymphoblastic leukemia (ALL) cells, and competitive binding with the ALB6 antibody known as the CD9 antibody. At saturation, PMA2 bound to approximately 46,000 sites per platelet. The binding of 125I-fibrinogen to platelets occurred in a PMA2 concentration-dependent manner and was blocked by EDTA or an anti- glycoprotein (GP)IIb-IIIa monoclonal antibody. PMA2-stimulated platelets caused ATP secretion and thromboxane B2 synthesis under non- stirred conditions. The role of secreted ADP and thromboxane in fibrinogen-binding and subsequent platelet aggregation was studied using creatine phosphate/creatine phosphokinase (CP/CPK) and aspirin. CP/CPK or aspirin alone reduced fibrinogen binding to 20% to 30%; however, this binding was sufficient to support full platelet aggregation. Combined treatment with CP/CPK and aspirin abolished fibrinogen binding and aggregation. These results demonstrate that the binding of IgG molecules to the CD9 antigen exposes fibrinogen receptors through both secreted ADP and thromboxane and that either one of both can expose the receptors to an extent sufficient to aggregate platelets.
Acquired homozygosity of the rearranged bcr allele during the acute leukemic phase of a patient with Ph-negative chronic myeloid leukemia
Authors: Reeve AE , Morris CM , Fitzgerald PH
Published: October 2019

A 45-year-old male patient with Ph-negative chronic myeloid leukemia (CML) had rearranged bcr-3′ and bcr-5#x2032; gene regions in Southern blot studies when leukemia was diagnosed. During development of terminal blast crisis, successive blood samples showed a progressive decrease in the amount of germline bcr DNA and its complete loss by full blast crisis. There were also increased amounts of rearranged bcr DNA consistent with acquired homozygosity. A similar result was obtained with an IgV lambda probe and indicated homozygosity of a significant part of chromosome 22. The bcr-abl gene complex behaves as a somatic dominant in CML, and we suggest that its acquired homozygosity is a mechanism of bcr-abl amplification similar to duplication of the Ph chromosome commonly found in the blast crisis of CML.
An analysis of the multilineage production of human hematopoietic progenitors in long-term bone marrow culture: evidence that reactive oxygen intermediates derived from mature phagocytic cells have a role in limiting progenitor cell self-renewal
Authors: Meagher RC , Salvado AJ , Wright DG
Published: October 2019

To better understand the limited hematopoietic life span of human marrow “Dexter” cultures, we developed a miniaturized, two-stage culture system with which in vitro production of hematopoietic progenitors could be reproducibly detected and quantified. Light- density, gradient-separated human marrow cells were inoculated into Leighton slide tubes, and adherent (“stromal”) cell layers were allowed to develop on the removable coverslips within these tubes during an initial 4 weeks of culture. Once stromal cell layers were established, cultures were irradiated (800 cGy) to eliminate all residual hematopoietic progenitors. The cultures were then recharged with autologous, cryopreserved marrow cells (enriched for BFU-E and CFU-GM) to reconstitute stem cell populations and to initiate in vitro hematopoiesis. Most progenitor cells added to irradiated cultures were no longer detectable by clonal assays within one to four days after recharge. Nonetheless, stable populations of adherent BFU-E and CFU-GM became established in these cultures within 24 to 48 hours, and when the total numbers of progenitors (adherent and nonadherent) were measured at weekly intervals thereafter, it was evident that both BFU-E and CFU-GM were generated in vitro. However, progenitor cell production declined as neutrophils and macrophages accumulated in the cultures. Moreover, with this accumulation of mature myeloid cells, increasing levels of O2- and H2O2 could be detected in the cultures, and it was found that the addition of oxidant scavengers (catalase and mannitol) to culture media enhanced the weekly expansions of progenitor cell numbers that could be measured. These findings support the conclusion that reactive O2 intermediates generated by mature myeloid cells have a role in limiting the duration and extent of hematopoietic progenitor cell self-renewal in long-term “Dexter” cultures of human marrow.
Rapid deactivation of NADPH oxidase in neutrophils: continuous replacement by newly activated enzyme sustains the respiratory burst
Authors: Akard LP , English D , Gabig TG
Published: October 2019

The cell-free system for activation of the neutrophil NADPH oxidase allowed us to examine activation of the oxidase in the absence of its NADPH-dependent turnover. The covalent sulfhydryl-modifying reagent N- ethylmaleimide completely inhibited the activation step (Ki = 40 mumol/L) in the cell-free system but had no effect on turnover of the preactivated particulate NADPH oxidase (up to 1 mmol/L). When N- ethylmaleimide was added to intact neutrophils during the period of maximal O2 generation in response to stimuli that activate the respiratory burst (phorbol myristate acetate, f-Met-Leu-Phe, opsonized zymosan, arachidonic acid), O2- generation ceased within seconds. Study of components of the cell-free activation system indicated that the cytosolic cofactor was irreversibly inhibited by N-ethylmaleimide whereas the N-ethylmaleimide-treated, membrane-associated oxidase could be activated by arachidonate and control cytosolic cofactor. Likewise, the cell-free system prepared from intact neutrophils that had been briefly exposed to N-ethylmaleimide and then washed reflected the effects of N-ethylmaleimide on the isolated cell-free components: cytosolic cofactor activity was absent, but the membrane oxidase remained fully activatable. Thus inhibition of oxidase activation by N- ethylamaleimide unmasked a rapid deactivation step that was operative in intact neutrophils but not in isolated particulate NADPH oxidase preparations. The demonstrated specificity of N-ethylmaleimide for oxidase activation and lack of effect on turnover of the NADPH oxidase suggested that sustained O2- generation by intact neutrophils was a result of continued replenishment of a small pool of active oxidase. The existence of an inactive pool of NADPH oxidase molecules in particulate preparations from stimulated neutrophils was supported more directly by activating these preparations again in the cell-free system.
Antimalarial properties of orally active iron chelators
Authors: Heppner DG , Hallaway PE , Kontoghiorghes GJ , Eaton JW
Published: October 2019

The appearance of widespread multiple drug resistance in human malaria has intensified the search for new antimalarial compounds. Metal chelators, especially those with high affinity for iron, represent one presently unexploited class of antimalarials. Unfortunately the use of previously identified chelators as antimalarials has been precluded by their toxicity and, in the case of desferrioxamine, the necessity for parenteral administration. The investigators now report that a new class of orally active iron chelators, namely the derivatives of alpha- ketohydroxypyridines (KHPs), are potent antimalarials against cultured Plasmodium falciparum. The KHPs evidently exert this effect by sequestering iron because a preformed chelator:iron complex has no antimalarial action. The pool(s) of iron being sequestered by the chelators have not been identified but may not include serum transferrin. Preincubation of human serum with KHPs followed by removal of the drug results in the removal of greater than 97% of total serum iron. Nonetheless, this serum effectively supports the growth of P falciparum cultures. Therefore the KHPs may exert antimalarial effect through chelation of erythrocytic rather than serum iron pool(s). The investigators conclude that these powerful, orally active iron chelators may form the basis of a new class of antimalarial drugs.
Forssman glycosphingolipid as an immunohistochemical marker for mouse stromal macrophages in hematopoietic foci
Authors: Sadahira Y , Mori M , Awai M , Watarai S , Yasuda T
Published: October 2019

The immunohistochemical distribution of Forssman glycosphingolipid (GSL) in mouse hematopoietic tissue was examined by using light and electron microscopic immunoperoxidase methods with a highly specific rabbit anti-Forssman GSL antibody. Bone marrow, splenic red pulp, and thymic macrophages, which are closely associated with hematopoietic cells, were stained by the antibody, whereas hematopoietic cells, circulating cells, alveolar macrophages, Kupffer cells, peritoneal resident macrophages, and macrophages derived from granulocyte- macrophage colony-forming units cultured in the presence of L-cell- conditioned medium were not stained. In addition, thymic cortical epithelial cells, the framework of reticular cells of the cortical and medullary regions of the mesenteric lymph node and periarterial lymphoid sheath of the spleen, and some vessels of the tissues examined were also stained. After phlebotomy, the fine cytoplasmic processes of Forssman-positive splenic red pulp macrophages were distributed extensively throughout the erythroid colonies. On the other hand, after hypertransfusion, these macrophages retracted their processes, became round, and tended to aggregate. These results indicate that Forssman GSL can be used as an immunohistochemical marker for stromal macrophages in the hematopoietic foci of the bone marrow and splenic red pulp.
A second BamHI DNA polymorphism and haplotype association in the factor IX gene
Authors: Driscoll MC , Dispenzieri A , Tobias E , Miller CH , Aledort LM
Published: October 2019

A second BamHI DNA polymorphism has been identified in the factor IX gene in an American black population at an allelic frequency of 0.13. This site has been localized within 500 basepairs (bp) 5′ to the XmnI intron 3 polymorphic site and increases the heterozygosity of black females at the factor IX gene locus. In addition, haplotype analysis of factor IX genes at five polymorphic loci indicates that although there is conservation of sequences between the races, factor IX genes show more heterogeneity in an American black population and thus more heterozygosity is observed in black females compared with whites. This increased heterogeneity is due to DNA polymorphisms unique to black populations and to linkage equilibrium between the most 5′ and 3′ polymorphic sites in factor IX genes in blacks.
Beta thalassemia in Melanesia: association with malaria and characterization of a common variant (IVS-1 nt 5 G----C)
Authors: Hill AV , Bowden DK , O'Shaughnessy DF , Weatherall DJ , Clegg JB
Published: October 2019

Data on the distribution of beta thalassemia among over 6,000 Melanesians reveals a major difference in the carrier rates between populations in the malarious coastal regions of New Guinea and those living in the historically malaria-free Highlands. The island of Maewo in Vanuatu has a particularly high incidence of beta + thalassemia associated with a single restriction enzyme haplotype. Direct cloning into a plasmid vector and sequence analysis demonstrate that the mutation is a G to C transversion at position 5 of intron 1 of the beta- globin gene. Oligonucleotide probe surveys indicate that this variant accounted for all cases of beta thalassemia studied from Maewo. It is also common in coastal Papua New Guinea where haplotype and oligonucleotide probe data suggest that the molecular basis of beta thalassmia is more heterogeneous.
Use of all-trans retinoic acid in the treatment of acute promyelocytic leukemia
Authors: Huang ME , Ye YC , Chen SR , Chai JR , Lu JX , Zhoa L , Gu LJ , Wang ZY
Published: October 2019

Twenty-four patients with acute promyelocytic leukemia (APL) were treated with all-trans retinoic acid (45 to 100 mg/m2/day). Of these, eight cases had been either nonresponsive or resistant to previous chemotherapy; the other 16 cases were previously untreated. All patients attained complete remission without developing bone marrow hypoplasia. Bone marrow suspension cultures were studied in 15 of the 24 patients. Fourteen of these patients had morphological maturation in response to the retinoic acid (1 mumol/L). Chloroacetate esterase and alpha-naphthyl acetate esterase staining as well as electronmicroscopic examination confirmed that retinoic acid-induced cells differentiated to granulocytes with increased functional maturation (as measured by nitroblue tetrazolium reduction, NBT). The single nonresponder to retinoic acid in vitro was resistant to treatment with retinoic acid but attained complete remission after addition of low-dose cytosine arabinoside (ara-C). During the course of therapy, none of the patients showed any abnormalities in the coagulation parameters we measured, suggesting an absence of any subclinical disseminated intravascular coagulation. The only side effects consisted of mild dryness of the lips and skin, with occasional headaches and digestive symptoms. Eight patients have relapsed after 2 to 5 months of complete remission. The others remain in complete remission at 1+ to 11+ months and are still being followed up. We conclude that all-trans retinoic acid is an effective inducer for attaining complete remission in APL.
Cloning of glycoprotein IIIa cDNA from human erythroleukemia cells and localization of the gene to chromosome 17
Authors: Rosa JP , Bray PF , Gayet O , Johnston GI , Cook RG , Jackson KW , Shuman MA , McEver RP
Published: October 2019

Platelet aggregation requires the binding of adhesive proteins such as fibrinogen to the heterodimer of membrane glycoproteins IIb (GPIIb) and IIIa (GPIIIa). Human erythroleukemia (HEL) cells synthesize both GPIIb and GPIIIa. Using poly(A+) RNA purified from HEL cells, we constructed a cDNA library in the lambda gt10 phage vector. This library was screened with a 38mer oligonucleotide derived from a platelet GPIIIa peptide, and three overlapping cDNAs were isolated. The three inserts encompassed 3.5 kilobases (kb), including the entire coding region of mature GPIIIa (2,286 basepairs, bp) and 1.3 kb of 3′ untranslated sequence. All 222 residues determined directly from platelet GPIIIa tryptic peptides exactly matched the HEL cell-deduced amino acid sequence. The HEL cell sequence matched a previously reported endothelial cell cDNA sequence except for eight nucleotides. Five of these nucleotide differences were silent changes consistent with genetic polymorphisms. The other three differences resulted in changes in the deduced amino acid sequence of GPIIIa; reexamination of the endothelial cell cDNA sequence in these three areas revealed that it is actually identical to the HEL cell sequence. The virtual identity of the endothelial and HEL cell cDNA sequences provides direct evidence that GPIIIa is a subunit common to cell-adhesion receptors present in more than one cell type. We localized the gene for GPIIIa to chromosome 17, the same chromosome to which we had previously mapped the gene for GPIIb.