bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of platelet-von Willebrand factor binding to platelets by adhesion site peptides
Authors: Parker RI , Gralnick HR 
Published: October 2019

Abstract
Synthetic peptides containing the adhesion site recognition sequences present on the A alpha and gamma chains of fibrinogen were studied for their effect on the binding of endogenous platelet-von Willebrand factor (vWF) and exogenous plasma-vWf to thrombin-stimulated platelets. In agreement with previously reported data, the tetrapeptide consisting of the RGDS sequence was a more potent inhibitor of plasma-vWf binding to platelets than was the pentadecapeptide of the carboxy terminus of the fibrinogen gamma-chain (IC50 10.6 mumol/L for the RGDS tetrapeptide v 44.9 mumol/L for the gamma-chain pentadecapeptide). No apparent synergy in the inhibition of plasma-vWf binding was noted when the RGDS and gamma-chain peptides were used together (IC50 15.2 mumol/L). In contrast, the gamma-chain peptide was significantly more inhibitory than was the RGDS tetrapeptide on the binding of platelet-vWf to platelets (IC50 1.4 mumol/L for the gamma-chain pentadecapeptide v 4.5 mumol/L for the RGDS tetrapeptide, P less than .05), and there was significant synergy in the inhibition of platelet-vWf binding noted when the gamma-chain and RGDS peptides were used together (IC50 0.04 mumol/L). These results indicate that the binding of platelet-vWf to its receptor on the platelet glycoprotein IIb/IIIa complex involves both the RGDS and gamma-chain recognition sites. In contrast to the results with plasma-vWf binding, the gamma-chain recognition site appears to be more important than the RGDS recognition site in platelet- vWf binding to platelets.
Increased circulating CSF-1 (M-CSF) in myeloproliferative disease: association with myeloid metaplasia and peripheral bone marrow extension
Authors: Gilbert HS , Praloran V , Stanley ER 
Published: October 2019

Abstract
Myeloproliferative disease (MPD) is heterogeneous in phenotypic expression and may display features consistent with expansion and activation of the monocyte/macrophage population during its course. The role of colony-stimulating factor-1 (CSF-1) in the pathophysiology of MPD was investigated by measuring circulating CSF-1 levels and examining their relationship to disease phenotype. Serum CSF-1 concentrations, measured by radioimmunoassay, were elevated in all MPD phenotypes. CSF-1 levels differed significantly between groups of patients with essential thrombocythemia, polycythemia vera, and postpolycythemic or agnogenic myeloid metaplasia (in ascending order). CSF-1 serum levels were positively correlated with spleen size and the degree of peripheral bone marrow extension, determined by scintigraphy using a macrophage-seeking isotope. There was no correlation between CSF-1 concentration and circulating levels of erythrocytes, neutrophils or platelets, or the presence of bone marrow fibrosis. Elevated serum CSF-1 levels appear to be associated with an expanded monocyte/macrophage population in MPD. In view of the known cooperativity between CSF-1 and other growth factors in regulating hematopoiesis, the finding of increased serum CSF-1 concentrations and its association with myeloid metaplasia and bone marrow extension may indicate a pathophysiologic role for CSF-1 in determining the phenotypic expression of MPD.
Interleukin-6 is a potent thrombopoietic factor in vivo in mice
Authors: Ishibashi T , Kimura H , Shikama Y , Uchida T , Kariyone S , Hirano T , Kishimoto T , Takatsuki F , Akiyama Y 
Published: October 2019

Abstract
To determine the biologic activity of interleukin-6 (IL-6) on megakaryocytopoiesis and thrombocytopoiesis in vivo, the cytokine was administered intraperitoneally to mice every 12 hours at varying doses for five days or for varying time intervals, based on the kinetic analysis of IL-6 serum levels indicating the peak of 40 minutes following injection, with no detection at 150 minutes. A dose-response experiment showed that IL-6 increased platelet counts in a dose- dependent fashion at a plateau stimulation level of 5 micrograms. Administration of 5 micrograms of IL-6 reproducibly elevated platelet counts at five days by approximately 50% to 60% of increase. Moreover, a striking increase in megakaryocytic size in response to IL-6 was elicited by the treatment, but no change in megakaryocyte numbers; whereas IL-6 administration did not expand CFU-MK numbers. The in vivo studies in this manner had negligible effects on other hematologic parameters, with the minor exception of monocyte levels. These data show that IL-6 acts on maturational stages in megakaryocytopoiesis and promotes platelet production in vivo in mice, suggesting that IL-6 functions as thrombopoietin.
Changes in the plasma levels of type 1 and type 2 plasminogen activator inhibitors in normal pregnancy and in patients with severe preeclampsia
Authors: Estelles A , Gilabert J , Aznar J , Loskutoff DJ , Schleef RR 
Published: October 2019

Abstract
This report defines the nature of the molecules responsible for the increased plasma plasminogen activator inhibitor (PAI) activity in preeclamptic patients and the relationship of these inhibitors to the severity of placental damage in preeclampsia. Clinical groups consisting of pregnant women with either severe preeclampsia or chronic hypertension with superimposed severe preeclampsia, as well as normal pregnant and nonpregnant women, were analyzed in a panel of functional and immunologic assays for PAI-1 and PAI-2. Pure severe preeclamptic patients in their third trimester showed a significant increase in both antigenic (136 ng/mL) and functional (5.76 U/mL) type 1 PAI (PAI-1) as compared with normal third-trimester pregnant women (34.8 ng/mL and 2.57 U/mL, respectively). In contrast, antigenic (186 ng/mL) and functional (5.76 U/mL) levels of type 2 PAI (PAI-2) were significantly lower in the pure severe preeclampsia group as compared with the values of the normal pregnant group (269 ng/mL and 9.58 U/mL, respectively). The patients with chronic hypertension and superimposed severe preeclampsia exhibited PAI-2 levels comparable to those of the pure preeclamptic group, whereas their antigenic and functional PAI-1 levels were intermediate (94 ng/mL and 3.25 U/mL, respectively) between the normal pregnant and the pure preeclamptic groups. During early puerperium of both normal pregnant women and patients, plasma PAI-1 antigen and activity decreased within one day to approximately the levels detected in normal nonpregnant women, while PAI-2 levels remained elevated for over 11 days. Similar results were obtained in plasma samples obtained from citrated blood and blood collected with an anticoagulant/antiplatelet mixture, suggesting that increased PAI-1 levels in preeclamptic patients were not due to platelet activation in vitro. In preeclamptic patients, a positive correlation between birth weight and PAI-2 values was observed (r = .64, P less than .05), whereas birth weight was inversely correlated with both PAI-1 levels and total PAI activity (r = -.6, P less than .005 and r = -.76, P less than .005 respectively). Preeclamptic patients with extensive placental infarction exhibited higher plasma PAI activity (24.1 U/mL v 11.6 U/mL) and PAI-1 values (305 ng/mL v 80.9 ng/mL) than preeclamptic patients without extensive placental infarction. In contrast, PAI-2 levels were reduced in preeclamptic patients with infarction in comparison with those of patients without infarction (141 ng/mL v 212.9 ng/mL). Our data indicate that increases in the level of PAI-1 accounts for the high plasma PAI activity in severe preeclampsia as measured using single-chain t-PA.
Covalent modification of platelet proteins by palmitate
Authors: Muszbek L , Laposata M 
Published: October 2019

Abstract
Covalent attachment of fatty acid to proteins plays an important role in association of certain proteins with hydrophobic membrane structures. In platelets, the structure of many membrane glycoproteins (GPs) has been examined in detail, but the question of fatty acid acylation of platelet proteins has not been addressed. In this study, we wished to determine (a) whether platelet proteins could be fatty acid acylated; and, if so, (b) whether these modified proteins were present in isolated platelet membranes and cytoskeletal fractions; and (c) if the pattern of fatty acid acylated proteins changed on stimulation of the platelets with the agonist thrombin. We observed that in platelets allowed to incorporate 3H-palmitate, a small percentage (1.37%) of radioactivity incorporated into the cells became covalently bound to protein. Selective cleavage of thioester, thioester plus O-ester, and amide-linked 3H-fatty acids from proteins, and their subsequent analysis by high-performance liquid chromatography (HPLC) indicated that the greatest part of 3H-fatty acid covalently bound to protein was thioester-linked 3H-palmitate. By sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography, at least ten major radiolabeled proteins were detected. Activation of platelets by thrombin greatly increased the quantity of 3H- palmitoylated proteins associated with the cytoskeleton. Nearly all radiolabeled proteins were recovered in the membrane fraction, indicating that these proteins are either integral or peripheral membrane proteins or proteins tightly associated to membrane constituents. Components of the GPIIb-IIIa complex were not palmitoylated. Thus, platelet proteins are significantly modified posttranslationally by 3H-palmitate, and incorporation of palmitoylated proteins into the cytoskeleton is a prominent component of the platelet response to thrombin stimulation.
Distribution of integrins on human peripheral blood mononuclear cells
Authors: Klingemann HG , Dedhar S 
Published: October 2019

Abstract
The receptors for fibronectin (FN-R) and vitronectin (VN-R) belong to a family of integral membrane glycoproteins known to be involved in cell- extracellular matrix and cell-cell interactions named integrins (FN-R = beta 1 integrin and VN-R = beta 3 integrin). Adhesion studies using FN- coated plastic dishes and highly purified subpopulations of peripheral blood mononuclear cells (PBMCs) showed a strong binding of monocytes and T lymphocytes to FN but virtually no binding of B cells to FN. Binding of monocytes and T cells to FN could be partially inhibited by a hexapeptide (GRGDSP) containing the adhesive peptide sequence Arg-Gly- Asp (RGD) as well as by an anti-FN-R antibody. The distribution of beta 1 and beta 3 integrin complexes on PBMCs was characterized by immunoprecipitation of detergent extracts of 125I-labeled cells using polyclonal antibodies against these two receptors. Two surface polypeptides corresponding to the alpha and beta chains of FN-R and VN- R were found on all three cell types. To characterize these receptors further, monoclonal antibodies (MoAbs) against the very late antigens (VLAs) 1, 3, and 5 were used for immunoprecipitation studies. Monocytes and T cells reacted with VLA 5 that was previously identified as the human FN receptor, whereas no labeling with anti-VLA 5 could be shown for B cells. When cell populations were cultured in 10% human serum for 24 hours, an increase in beta 1-integrin+ monocytes and T cells was observed. The number of beta 3-integrin+ cells remained essentially unchanged. The presence of beta 1 and beta 3 integrins on monocytes as well as on T and B lymphocytes may be of significance in the ability of these cells to interact with each other and participate in hematopoiesis and certain immune reactions.
CML-T1: a cell line derived from T-lymphocyte acute phase of chronic myelogenous leukemia
Authors: Kuriyama K , Gale RP , Tomonaga M , Ikeda S , Yao E , Klisak I , Whelan K , Yakir H , Ichimaru M , Sparkes RS 
Published: October 2019

Abstract
Most data suggest that malignant transformation in chronic myelogenous leukemia (CML) occurs in hematopoietic stem cell that is the progenitor of myelopoiesis and of B but not T lymphopoiesis. We established a T- lymphoid cell line (CML-T1) from a person with Ph-chromosome-negative CML in acute phase. Evidence of its T-lymphocyte origin includes the pattern cytochemical reactivity, reactivity with anti-T-cell monoclonal antibodies (MoAbs), and rearrangement of the beta-T-cell receptor (TCRB) gene. CML-T1 cells have features of type IV thymocytes. Cytogenetic analyses indicate a 47,XX, del(11), t(6;7)(q23;q24), +mar karyotype. CML-T1 cells exhibit molecular changes typical of CML, including translocation of the ABL protooncogene from chromosome 9 to 22, rearrangement of the BCR gene, and transcription of a chimeric BCR- ABL messenger RNA (mRNA). The ABL insertion on chromosome 22 appears interstitial, similar to other cases of Ph-chromosome-negative CML. These data clearly indicate that T cells can be involved in acute-phase CML. CML-T1 should be useful in studying this process as well as that underlying Ph-chromosome-negative CML.
Leg ulcers in patients with sickle cell disease [see comments]
Authors: Koshy M , Entsuah R , Koranda A , Kraus AP , Johnson R , Bellvue R , Flournoy-Gill Z , Levy P 
Published: October 2019

Abstract
During the entry examination, leg ulcers were present in 2.5% of 2,075 patients 10 years of age and older with sickle cell disease who entered into the Cooperative Study of Sickle Cell Disease (CSSCD) between 1979 and 1986. Prevalence rates were highest among patients with sickle cell anemia and sickle cell anemia with thalassemia genotypes. Among sickle cell anemia patients free of ulcers at entry, the overall incidence was 5.73 per 100 person years in those having associated alpha-thalassemia and 9.97 for those without. Among sickle cell anemia patients with two alpha genes, the estimated incidence of leg ulcers is 2.38 per 100 person years and 6.12 per 100 person years among sickle cell anemia patients with three alpha genes (P less than .05). In both groups, the incidence was highest among those patients over 20 years of age and considerably higher among males than females (P less than .001). Leg ulcers were nonexistent in patients with sickle beta plus thalassemia and sickle hemoglobin C disease. Low steady-state hemoglobin is associated with a higher incidence of ulcer formation (P less than .0001) in sickle cell anemia patients. The protective effect of hemoglobin F is apparent at all levels of total hemoglobin among sickle cell anemia patients and those with associated alpha-thalassemia.
Antibody-mediated marrow failure after allogeneic bone marrow transplantation
Authors: Barge AJ , Johnson G , Witherspoon R , Torok-Storb B 
Published: October 2019

Abstract
Marrow graft failure observed in association with histocompatibility differences between donor and recipient is often attributed to rejection mediated by host-derived cytolytic T lymphocytes. The data presented in this report indicate that persistent host antibodies specific for donor antigen may also mediate graft failure, either by antibody-dependent cell-mediated cytotoxicity (ADCC), or complement- mediated cytotoxicity. In the case of HLA Class I disparity, where all donor cells express the target antigen, the presence of alpha-donor antibody was associated with complete graft failure and death. In the case of ABO blood group antigen disparity, the presence of alpha-donor antibody resulted in erythroid hypoplasia. The latter cases proved informative insofar as they established that host antibodies could persist for more than 18 months after chemoradiotherapy and impair marrow function.
Molecular characterization of human factor XSan Antonio
Authors: Reddy SV , Zhou ZQ , Rao KJ , Scott JP , Watzke H , High KA , Jagadeeswaran P 
Published: October 2019

Abstract
Enzymatic amplification technique was used to isolate all eight exons and sequences around the splice junctions, putative promoter, and polyadenylation sites of human factor X DNA from a patient with factor X deficiency. Two genetic changes in factor X have been observed in this patient. The patient is most likely a compound heterozygote since there is only 14% activity associated with factor X. A point mutation that resulted in the substitution of cysteine (TGC) for arginine (CGC) at amino acid 366 was found in exon VIII of one allele of the factor X gene. This mutation, which occurs in the catalytic domain, can affect the formation of a disulfide bridge and thus could result in a reduction in factor X activity. Sequencing all the regions revealed a second mutation: a deletion of one nucleotide (TCCT to TCT) in exon VII that would cause a frame shift at amino acid 272 followed by termination. We have also shown that the point mutation in exon VIII creates an ApaL1 restriction site and destroys the HinP1 site. Enzymatic DNA amplification followed by restriction digestion provides a quick, reliable, and sensitive method for carrier detection and antenatal diagnosis in affected kindreds. This is the first characterization of factor X deficiency at the molecular level. We propose to name this mutation Factor XSan Antonio.
Nuclear oncoprotein expression as a function of lineage, differentiation stage, and proliferative status of normal human hematopoietic cells
Authors: Kastan MB , Stone KD , Civin CI 
Published: October 2019

Abstract
Relative levels of the nuclear oncoproteins c-myb, c-myc, and c-fos were determined in selected subpopulations of normal human bone marrow (BM) cells using a flow cytometric assay which simultaneously detects a cell-surface antigen (as a marker of lineage and stage of maturation) and levels of an intracellular protein. At least two monoclonal antibodies directed against each oncoprotein and specific peptide inhibition controls were used for these determinations. Hematopoietic progenitor cells (CD34+) express the highest levels of c-myb and c-myc, whereas c-fos levels in CD34+ progenitor cells are similar to c-fos levels in mature monocytes and granulocytes. Granulocytes are the only hematopoietic cells examined which do not express detectable levels of c-myb and c-myc. The levels of these oncoproteins in these normal, unstimulated BM cell populations were more closely linked to lineage and maturation stage than to the proliferative status of the given population, as determined by either DNA staining or expression of the cell-cycle specific nuclear protein, Ki67. This flow cytometric assay helps in interpreting the significance of oncoprotein levels in leukemia cells by allowing direct comparisons of a leukemia with the phenotypically similar “normal counterpart control” cell population in normal BM.
Effects of interleukin-3 and erythropoietin on in vivo erythropoiesis and F-cell formation in primates
Authors: Umemura T , al-Khatti A , Donahue RE , Papayannopoulou T , Stamatoyannopoulos G 
Published: October 2019

Abstract
To test the in vivo cooperativity between interleukin-3 (IL-3) and erythropoietin (Epo) in stimulating erythropoiesis and hemoglobin F (HbF) production in primates, we administered recombinant human IL-3 and recombinant human Epo to baboons and macaques. The effect of these treatments was assessed by serial bone marrow cultures and by measuring HbF production in the progeny of bone marrow progenitors and in peripheral-blood reticulocytes. Administration of IL-3 alone to hematologically normal or anemic baboons produced an early increase in erythroid colony-forming units (CFUe) and erythroid clusters (e- clusters) with an increase in reticulocyte counts and a late increment in the relative frequency of erythroid burst-forming units (BFUe). In parallel to the increase in peripheral-blood reticulocytes, IL-3 increased the frequency of F reticulocytes in the normal and anemic animals. When administration of IL-3 was followed by administration of Epo, expansion in all classes of erythroid progenitors and increase in reticulocytes occurred, beyond the levels observed when the animals were treated with Epo alone. The combination of IL-3 and Epo, however, did not increase consistently the rate of F reticulocytes beyond the level induced by Epo alone. These results suggest that IL-3 enhances the effect of Epo on erythropoiesis, but the combination of the two growth factors does not lead to a preferential and significant enhancement of HbF production.
Autoantibodies against platelet membrane glycoproteins in children with acute and chronic immune thrombocytopenic purpura
Authors: Berchtold P , McMillan R , Tani P , Sommerville-Nielsen S , Blanchette VS 
Published: October 2019

Abstract
The autoimmune nature of chronic immune thrombocytopenic purpura (ITP) in adults is widely accepted. In contrast, the pathogenetic mechanism in acute and chronic ITP in children is not known. In this report, we studied 39 children with destructive thrombocytopenia, 15 patients with acute ITP and 24 patients with chronic ITP. Platelet autoantibodies to platelet glycoprotein IIb/IIIa were detected in 14 of 24 patients (58.3%) in the chronic ITP group and in four of 15 (26.7%) with acute ITP. Binding ratios (+/- SD) of positive patients were significantly greater (P = .01) in chronic ITP (8.0 +/- 9.1) when compared with those of acute ITP where the binding ratios were only slightly above the normal range (1.9 +/- 0.4). The results show that autoantibodies against platelet glycoproteins are present in the majority of children with chronic ITP confirming the autoimmune nature of this disorder. The minimal elevation seen in the positive children with acute ITP suggests a different pathogenetic mechanism. These data suggest that this approach may be useful in differentiating acute from chronic ITP patients.
Biosynthesis and assembly of platelet GPIIb-IIIa in human megakaryocytes: evidence that assembly between pro-GPIIb and GPIIIa is a prerequisite for expression of the complex on the cell surface
Authors: Duperray A , Troesch A , Berthier R , Chagnon E , Frachet P , Uzan G , Marguerie G 
Published: October 2019

Abstract
The platelet membrane glycoproteins GPIIb and GPIIIa form a calcium- dependent heterodimer that functions as a receptor for adhesive proteins on stimulated platelets. In this study, we have investigated the kinetics of the assembly reaction that result in GPIIb-IIIa dimerization. Pulse-chase experiments analysis performed on human megakaryocytes obtained from liquid cultures of chronic myelogenous leukemic patients with antibodies specific for GPIIIa or GPIIb demonstrated the existence of a pro-GPIIb-GPIIIa complex and of a large pool (60%) of unassociated GPIIIa; nearly all the GPIIb and the pro- GPIIb molecules were found associated with GPIIIa. This free GPIIIa was not exposed on the cell surface. Pulse-chase experiments on a subclone of the human megakaryocytic cell line LAMA-84 revealed that the cells from this subclone produced only the pro-GPIIb, which was neither processed into mature GPIIb nor expressed on the cell surface. The expression of GPIIIa in PMA treated cells resulted in the production of the mature GPIIb form and the expression of the GPIIb-IIIa complex on the cell surface. These results indicate that assembly between the early forms of pro-GPIIb and GPIIIa is an obligatory step for the maturation of the heterodimer and its expression on the cell surface.