bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sialic acid prevents loss of large von Willebrand factor multimers by protecting against amino-terminal proteolytic cleavage
Authors: Berkowitz SD , Federici AB 
Published: October 2019

Abstract
Removal of sialic acid from the von Willebrand factor (vWF) subunit exposes additional cleavage sites in the amino-terminal region that are associated with loss of large multimers. The extent of large multimer loss was evaluated by examining the sites of subunit cleavage of native and carbohydrate-modified vWF after treatment with trypsin, chymotrypsin, or plasmin. In the presence of proteinase inhibitors, purified vWF was treated with neuraminidase alone to remove 90% to 95% of the sialic acid or with neuraminidase and beta-galactosidase to remove the sialic acid and 45% to 50% of the D-galactose, with little or no loss of large multimers observed. Digestion of native vWF with trypsin produced the greatest loss of large multimers, while chymotrypsin produced less and plasmin produced the least. Large multimer loss was more extensive with each enzyme after carbohydrate modification of vWF. The extent and approximate location of subunit cleavage was determined by immunoblotting and monoclonal antibody epitope mapping. Trypsin, chymotrypsin, and plasmin were shown to produce both amino- and carboxyl-terminal fragments. The number, location, and relative quantities of carboxyl-terminal fragments produced were unchanged after carbohydrate modification. However, digestion of the amino-terminal region was considerably more extensive after carbohydrate modification as judged by a marked decrease or absence of the larger fragments seen when native vWF was digested, and by the appearance of new smaller molecular mass species. Therefore, the greater loss of large multimers that occurs after carbohydrate modification is likely to be the result of cleavages in the amino- terminal region of the molecule. By protecting the vWF subunit against amino-terminal cleavage, sialic acid inhibits the loss of large multimers.
Structural integrity of the glycoprotein IIb and IIIa genes in Glanzmann thrombasthenia patients from Israel
Authors: Russell ME , Seligsohn U , Coller BS , Ginsberg MH , Skoglund P , Quertermous T 
Published: October 2019

Abstract
Glanzmann thrombasthenia is an autosomal recessive disorder of the platelet glycoproteins (GP) IIb and IIIa. These glycoproteins normally serve as receptors for other adhesive glycoproteins, including fibrinogen, von Willebrand factor, and fibronectin. Most patients affected by Glanzmann thrombasthenia have low levels of GPIIb and GPIIIa; however, the separate mechanisms responsible for the deficiency in each remain to be determined. cDNA clones coding for the GPIIb and GPIIIa have been recently isolated, and their corresponding genomic sequences have been colocalized to the long arm of chromosome 17. Since a deletional event involving one or both of these structural genes could explain the disease phenotype, we have studied the DNA of two previously well-characterized cohorts of Glanzmann thrombasthenia patients from Israel. We performed Southern analysis with near full- length cDNA probes on genomic DNA obtained from 20 individuals. Four restriction enzyme digests were completed on each DNA sample. The similarity of banding patterns among probands, family members, and controls indicated that there were no major insertions or deletions in either the GPIIb or GPIIIa genes. Thus, the genetic defect in these patients with Glanzmann thrombasthenia is most likely due to either a small change in the nucleotide sequence of the coding region or a defect in the regulatory region of one or both genes.
The enzymes of the glycolytic pathway in erythrocytes infected with Plasmodium falciparum malaria parasites
Authors: Roth EF Jr , Calvin MC , Max-Audit I , Rosa J , Rosa R 
Published: October 2019

Abstract
Enzymes of the glycolytic pathway as well as some ancillary enzymes were studied in normal red cells parasitized with Plasmodium falciparum in culture at varying parasitemias as well as in isolated parasites. The levels of all enzymes except diphosphoglycerate mutase, glucose-6- phosphate dehydrogenase, and adenylate kinase were elevated. Extreme elevations of hexokinase, aldolase, enolase, pyruvate kinase, and adenosine deaminase concentrations were noted. In most cases, electrophoretically distinct bands of enzyme activity were also seen. These findings partly explain the previously noted 50- to 100-fold increase in glucose consumption of infected red cells and suggest that further knowledge of these parasite enzymes and their genetic basis may aid both in designing new chemotherapy and in understanding the evolution of these parasites.
A molecular study of heterozygous protein 4.1 deficiency in hereditary elliptocytosis
Authors: Lambert S , Conboy J , Zail S 
Published: October 2019

Abstract
Genomic DNA from five kindreds and two individuals with hereditary elliptocytosis [HE(4.1+)] and a partial deficiency of protein 4.1 [HE(4.1+)] was extracted and probed with a cDNA for protein 4.1. When using a fragment of the cDNA that encompassed the coding region of the gene, two restriction fragment length polymorphisms segregating with protein 4.1 deficiency were found in one kindred when using the enzymes BgIII and PvuII but were not seen in the other HE(4.1+) subjects or in 20 random control individuals. DNA digested with three other enzymes (HindIII, EcoRI, TaqI) produced restriction patterns similar to controls. The unique BgIII and PvuII polymorphisms probably reflect a rearrangement of the coding region of the protein 4.1 gene as the underlying cause of the partial protein 4.1 deficiency in this family. A less likely possibility is that these polymorphisms represent coincidental single base changes unrelated to the primary gene defect.
Inhibition of leukemic HL60 cell growth by transferrin-gallium: effects on ribonucleotide reductase and demonstration of drug synergy with hydroxyurea [see comments]
Authors: Chitambar CR , Matthaeus WG , Antholine WE , Graff K , O'Brien WJ 
Published: October 2019

Abstract
Cellular requirements for iron during DNA synthesis are related to the increased activity of the iron-containing M2 subunit of ribonucleotide reductase, the enzyme responsible for the reduction of ribonucleotides to deoxyribonucleotides. We have previously shown that transferrin- gallium (Tf-Ga) inhibits cellular iron incorporation. In the present study, Tf-Ga-induced inhibition of HL60 cell growth and upregulation of Tf receptor density was reversed with hemin. Cells exposed to 2 mumol/L Tf-Ga for six hours or longer displayed a diminution in the electron spin resonance (ESR) spectroscopy signal of the tyrosyl radical of the M2 subunit of ribonucleotide reductase. The effect of Tf-Ga on the ESR signal was reversed by hemin. Tf-Ga decreased the incorporation of 14C- adenosine into DNA and decreased intracellular deoxyribonucleotide pools, with the maximum diminution seen in deoxyadenosine triphosphate (dATP) and deoxycytidine triphosphate (dCTP) pools. Exposure of cells to combinations of Tf-Ga and hydroxyurea (a known inhibitor of ribonucleotide reductase) resulted in a marked inhibition of cell growth that was consistent with drug synergy. Our studies suggest that Tf-Ga inhibits DNA synthesis through action on the M2 subunit of ribonucleotide reductase and that combinations of Ga and hydroxyurea should be further evaluated in in vivo tumor models.
Lymphokine-activated killer cells from normal and lymphoma subjects are cytotoxic for cells coated with antibody derivatives displaying human Fc gamma
Authors: Dearman RJ , Stevenson FK , Wrightham M , Hamblin TJ , Glennie MJ , Stevenson GT 
Published: October 2019

Abstract
Lymphokine-activated killer (LAK) cells were successfully generated in all cases from blood mononuclear cells obtained from six patients with lymphoma. The LAK cells from three of these patients and from five normal adult donors were tested for their effector abilities in antibody-dependent cellular cytotoxicity (ADCC) against guinea pig leukemic lymphocytes coated with various antiidiotype antibodies. Cells from all the donors behaved similarly. Mouse monoclonal antibodies of IgG1, IgG2a, and IgG2b isotypes invoked no ADCC. However, substantial ADCC was invoked by the chimeric antibody FabFc, in which Fab'gamma from mouse antiidiotype is thioether-bonded to human normal Fc gamma. Similar results were obtained on testing LAK cells from a normal donor against uncultured human lymphoma targets coated with native or chimeric antiidiotype. The ADCC invoked by the mouse-human chimeric antibodies appears to depend on the human Fc gamma they display and not on the univalency of the derivatives used. The findings imply that LAK technology could usefully augment serotherapy that uses antibody derivatives displaying human Fc gamma.
Down regulation of myelopoiesis by mediators inhibiting the production of macrophage-derived granulomonopoietic enhancing activity (GM-EA)
Authors: Wang SY , Ho CK , Chen LY , Wang RC , Huang MH , Castro-Malaspina H , Moore MA 
Published: October 2019

Abstract
Monocyte-derived lipid-containing macrophages (MDLMs) constitutively synthesize a granulomonopoietic enhancing activity (GM-EA) that potentiates the function of granulocyte-macrophage colony-stimulating activity (GM-CSA). In the study reported, we show that GM-EA is distinct from interleukin-1 (IL-1) in biochemical and functional properties and that its production is negatively regulated by several mediators. Thus, MDLM cultures pretreated with interferon-gamma (IFN- gamma, 3 to 900 U/mL), prostaglandin E2 (PGE2, 10(-13) to 10(-8) mol/L), or lactoferrin (LF, 10(-13) to 10(-8) mol/L) invariably produced less GM-EA than untreated controls. The relative potency of inhibition was in the order of IFN-gamma greater than or equal to PGE2 greater than LF. The extent of the inhibitory effects was proportional to dosage and the duration of treatment and could be observed following only a brief exposure (two hours) of the MDLMS to physiologic doses of the mediators. Under optimal conditions, IFN-gamma (300 U/mL for 24 to 48 hours) and PGE2 (10(-9) mol/L for 24 to 48 hours) could totally abrogate the ability of the MDLMs to produce GM-EA. However, the drug- inhibited MDLMs could be reactivated to produce GM-EA by treatment with zymosan (60 micrograms/mL). These results demonstrate that a mechanism for the control of myelopoiesis by mediators such as IFN-gamma, PGE2, and LF may involve the inhibition of GM-EA production. Furthermore, this negative feedback control is reversible and can be overridden when a proper stimulatory signal is given.
Usage of gamma chain variable regions in human acute lymphoblastic leukemias
Authors: Gonzalez-Sarmiento R , Greenberg JM , Kersey JH 
Published: October 2019

Abstract
The purpose of the present study was to evaluate the use of the variable regions of the T gamma rearranging gene of the second T cell receptor. Genomic DNA was extracted from leukemic cells of T and B precursor phenotypes and hybridized to probes that detect rearrangement of the V gamma regions. We present data showing that the V gamma use is nonrandom in acute lymphoblastic leukemias (ALLs). B precursor ALL rearranged the more 5′ variable regions. The results obtained suggest that the T precursor leukemias more frequently rearrange the 3′ V gamma regions. Two leukemias that expressed the gamma protein rearranged V gamma 8 and V gamma 9.
Putative involvement of protein kinase C in proliferation of human myeloid progenitor cells
Authors: Katayama N , Nishikawa M , Minami N , Shirakawa S 
Published: October 2019

Abstract
The effects of two different potent inhibitors of protein kinase C, 1- (5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) and staurosporine on human myeloid (CFU-C) and late erythroid progenitor cells (CFU-E) were studied using an in vitro clonal assay. Our objective was to determine whether protein kinase C has a role in signal transduction related to proliferation of these committed progenitor cells. The presence of H-7 or staurosporine led to an inhibition of colony formation stimulated by crude colony-stimulating factor (CSF), interleukin-3 (IL-3), granulocyte-macrophage CSF (GM-CSF), granulocyte CSF (G-CSF), or macrophage CSF (M-CSF) in a dose-dependent manner. N-(2-guanidinoethyl)- 5-isoquinolinesulfonamide (HA-1004), a weaker analog of H-7, did not inhibit proliferation of CFU-C. Neither H-7 nor staurosporine had any effect on CFU-E formation. H-7 and staurosporine dose-dependently inhibited the protein kinase C from K562 cells. The potential of these compounds to inhibit proliferation of CFU-C correlated well with the magnitude of their inhibition of protein kinase C from K562 cells. The inhibition of proliferation of CFU-C appears to relate to the potential of these compounds to inhibit protein kinase C. Thus, activation of protein kinase C is presumably involved in the proliferation of CFU-C, and the regulatory system of CFU-E appears to differ from that of CFU-C.
Expression of a fibrinogen fusion peptide in Escherichia coli: a model thrombin substrate for structure/function analysis
Authors: Lord ST , Fowlkes DM 
Published: October 2019

Abstract
The initial event in fibrin clot formation is the thrombin-catalyzed cleavage of the A alpha chain of human fibrinogen. Most of the information required for thrombin recognition and cleavage of the A alpha chain lies in the amino terminal 51 residue CNBr fragment. By selective modification of residues in this region, we probed the features that participate in thrombin interactions. We constructed a vector which expressed a tripartite protein (tribrid) consisting of amino acids 1 to 50 of the A alpha chain followed by 60 amino acids of chicken collagen and the beta-galactosidase protein from Escherichia coli. Cell lysates run on NaDodSO4-polyacrylamide gels contained the predicted band of molecular weight (mol wt) 125,000. The tribrid reacted with a monoclonal antibody, Mab-Y18, which recognizes the amino terminus of the A alpha chain. When cell lysates were incubated with thrombin, FPA was released. By including one heterogeneous oligonucleotide in the construction, we generated plasmids that encoded three specific amino acid substitutions. Surprisingly, changing Gly14 to Val did not alter thrombin cleavage, although recognition by Mab-Y18 was lost. Substitution of lie for Arg23 did not alter either thrombin cleavage or monoclonal recognition. Substitution of Leu for Arg 16 altered thrombin cleavage; unexpectedly, recognition by Mab-Y18 was not changed.
Abnormalities of cytoplasmic Ca2+ in platelets from patients with uremia
Authors: Ware JA , Clark BA , Smith M , Salzman EW 
Published: October 2019

Abstract
Uremic patients have a hemorrhagic tendency, often associated with prolonged bleeding times and decreased platelet function in vitro. Whether these defects result from abnormalities in plasma factors affecting platelet activity, platelet surface receptors, intracellular platelet mediators, or other aspects of platelet behavior is unknown. To examine the possibility that the abnormality in platelet function may result from aberrations in Ca2+ homeostasis, blood was obtained from 29 patients with severe uremia. The platelets were washed, loaded with the Ca2+ -sensitive probes indo-1 and aequorin, gel-filtered, and resuspended in either plasma or buffer. Of the 29 patients, seven had template bleeding times prolonged to 11 minutes or more, but platelet aggregation in plasma was not consistently impaired in these patients. However, in aequorin-loaded platelets from the patients with long bleeding times, the highest elevation of cytoplasmic calcium [( Ca2+]i) in response to the Ca2+ ionophore A23187, arachidonate, adenosine diphosphate (ADP), or epinephrine was lower than that seen in platelets from both uremic patients with less prolonged bleeding times and normal volunteers. The reduced [Ca2+]i response was associated with decreased aggregation of gel-filtered platelets suspended in buffer. Suspending washed aequorin-loaded uremic platelets in normal plasma for 20 minutes did not reverse the decreased agonist-induced rise in [Ca2+]i; platelets from a normal donor resuspended in uremic plasma aggregated and produced a normal increase in [Ca2+]i in response to agonists. We conclude that the platelet defect seen in some patients with uremia is associated with a decreased rise in platelet [Ca2+]i after stimulation and that this is a manifestation of an intrinsic platelet defect.
Isolation of Reed-Sternberg cells from lymph nodes of Hodgkin's disease patients
Authors: Sitar G , Brusamolino E , Bernasconi C , Ascari E 
Published: October 2019

Abstract
This study describes a simple and relatively rapid method of purifying Reed-Sternberg (R-S) cells and their morphologic variants from the lymph nodes of patients affected by Hodgkin's disease. Our initial studies defined the optimal procedure for a quantitative disaggregation of Hodgkin's lymph nodes and the densities of R-S cells in several donors. These preliminary steps were helpful in the development of strategies for selectively concentrating R-S cells by density gradient centrifugation. We layered a single-cell suspension over Percoll of appropriate density, centrifuged these samples for 15 minutes, and collected a fraction enriched in R-S cells. Most of the R-S cells were distributed between densities of 1.060 and 1.072, with a peak at approximately 1.066 g/mL. R-S cells are denser than many mononuclear cells present in the lymph nodes of Hodgkin's patients and lighter than reactive cells such as eosinophils, mast cells, and neutrophils. However, the ranges of densities of these cell types overlap, making purification of R-S cells by isopyknic centrifugation impossible. Nevertheless, when this enriched fraction is further processed by velocity sedimentation in order to take advantage of the larger size of R-S cells as compared with all other cells, a substantial purification is achieved. We used three different velocity-sedimentation chambers to find the optimal conditions for obtaining the highest purity with a high final yield. The cells isolated by this method are viable, appear to be morphologically normal, and have been further characterized biologically.
Chromosome 7 long arm deletion in myeloid disorders: a narrow breakpoint region in 7q22 defined by molecular mapping
Authors: Kere J , Ruutu T , Davies KA , Roninson IB , Watkins PC , Winqvist R , de la Chapelle A 
Published: October 2019

Abstract
The involvement of the erythropoietin (EPO), plasminogen activator inhibitor type I (PAI1), and multi-drug resistance (MDR2) genes located in chromosomal region 7q21–22 was studied in patients with myeloid disorders and with or without a chromosome 7 abnormality. Separated blood mononuclear cells and granulocytes from 21 patients were used in restriction fragment length polymorphism (RFLP) studies with gene- specific DNA probes. A marked weakness of one of the allelic bands was observed in granulocyte-derived DNA from heterozygous patients with monosomy 7. In four patients with a partial deletion of chromosome 7 long arm (7q-), marked weakness of an allelic band was observed in granulocyte-derived DNA with PAI1 probe (four heterozygous patients) and MDR2 probe (one heterozygous patient), implying deletion of these genes. In contrast, the EPO gene was not deleted in these patients, as demonstrated by the presence of two allelic bands of equal strength in granulocyte-derived DNA (two patients) or by gene dosage estimation (two patients). Two allelic bands of equal strength were also observed in three heterozygous patients with an arbitrary probe (pKV13) located in 7cen-q21.3. Unexpected hemizygosity or hybridization bands were not observed in any patient. We conclude that PAI1 and MDR2 are located distally of EPO in 7q22, and that none of these genes is commonly rearranged in myeloid disorders. The chromosome 7 long arm deletion breakpoint is located in a relatively narrow segment between the PAI1 and EPO genes in different patients. The deletion may involve a specific site in DNA, since the genetic distance between the PAI1 and EPO genes is only 3 cM.
Phenotypic heterogeneity of spontaneous lymphomas of CWD mice
Authors: Thomas CY , Buxton VK , Roberts JS , Boykin BJ , Innes D 
Published: October 2019

Abstract
Animals of the inbred mouse strain, CWD, express endogenous murine leukemia viruses early in life and have a high incidence of spontaneous neoplasms. We found that approximately one half of these animals died of malignant lymphoma by the age of 16 months. Splenic enlargement was seen in all mice, but thymic involvement was unusual. One half of the CWD tumors were diffuse lymphoblastic or immunoblastic lymphomas while the remainder were large cell, small cell, or mixed cell lymphomas. Analysis of DNAs from 12 tumors for immunoglobulin and T-cell receptor gene rearrangements revealed that all six of the lymphoblastic and immunoblastic lymphomas were of T-cell origin, as was one tumor of small cleaved cells. Four of the others were clonal B-cell lymphomas and one was of uncertain lineage. Assays of a limited number of tumors for the expression of the Thy 1.2 and IgM molecules confirmed the diversity in the cellular phenotype. The results indicate that CWD mice develop primarily splenic lymphomas with an unusual degree of heterogeneity in the tumor cell phenotypes as compared with the thymic lymphomas found in other high leukemia strains. The CWD strain is a useful new model for studies of retroviral leukemogenesis and the relationship between the histopathology and immunophenotype of malignant lymphomas.
Synergistic stimulation of macrophage proliferation by the monokines tumor necrosis factor-alpha and colony-stimulating factor 1
Authors: Branch DR , Turner AR , Guilbert LJ 
Published: October 2019

Abstract
The effects of pure recombinant human tumor necrosis factor-alpha (TNF) on the CSF-1-stimulated proliferation of well-defined populations of murine macrophages are examined. Primary bone marrow-derived macrophages (BMM) from endotoxin-resistant C3H/HeJ mice were characterized for homogeneity in comparison with a cloned, growth factor-dependent macrophage cell line (S1) also derived from C3H/HeJ bone marrow cells. The mitogenic effects of each factor, alone and in combination, on the proliferation of both macrophage populations over a two-day culture period were studied. In contrast to CSF-1, TNF alone only slightly stimulated macrophage proliferation. However, the combination of CSF-1 and TNF stimulated proliferation of both primary BMM and S1 cells 1.5- to 2-fold greater than the sum of their predicted individual contributions. Such synergy was observed even at very high (plateau) levels of factors. TNF was found to transiently down-regulate CSF-1 receptor levels on both populations. Down-regulation was maximal at one hour; however, receptor numbers returned to initial, or greater, levels after 24 hours of incubation. Thus, TNF, an inducible monokine, greatly enhances the maximal mitogenic effects of CSF-1, an inducer of TNF production. These observations suggest an autocrine rule for TNF that involves synergy with (and perhaps obligatory cooperation with) CSF-1 in the regulation of macrophage proliferation.