bluuebunny/crossref_metadata_2025_split huggingface dataset:
Signaling by ephrinB1 and Eph kinases in platelets promotes Rap1 activation, platelet adhesion, and aggregation via effector pathways that do not require phosphorylation of ephrinB1
Authors: Prévost Nicolas , Woulfe Donna S. , Tognolini Massimiliano , Tanaka Takako , Jian Wenying , Fortna Ryan R. , Jiang Hong , Brass Lawrence F. 
Published: October 2003

Abstract
We have previously shown that platelets express 2 receptor tyrosine kinases, EphA4 and EphB1, and the Eph kinase ligand, ephrinB1, and proposed that transcellular Eph/ephrin interactions made possible by the onset of platelet aggregation promote the further growth and stability of the hemostatic plug. The present study examines how this might occur. The results show that clustering of either ephrinB1 or EphA4 causes platelets to adhere to immobilized fibrinogen via αIIbβ3. Adhesion occurs more slowly than with adenosine diphosphate (ADP) and requires phosphatidylinositol 3 (PI3)–kinase and protein kinase C activity but not ephrinB1 phosphorylation. By itself, Eph and ephrin signaling is insufficient to cause aggregation or the binding of soluble fibrinogen, but it can potentiate aggregation initiated by a Ca++ ionophore or by agonists for thrombin and thromboxane receptors. It also enhances Rap1 activation without requiring ADP secretion, ephrinB1 phosphorylation, or the activation of PI3-kinase and Src. From this we conclude that (1) Eph/ephrin signaling enhances the ability of platelet agonists to cause aggregation provided that those agonists can increase cytosolic Ca++; (2) this is accomplished in part by activating Rap1; and (3) these effects require oligomerization of ephrinB1 but not phosphotyrosine-based interactions with the ephrinB1 cytoplasmic domain.
Raf-1 is not required for megakaryocytopoiesis or TPO-induced ERK phosphorylation
Authors: Kamata Tamihiro , Pritchard Catrin A. , Leavitt Andrew D. 
Published: October 2003

AbstractThrombopoietin stimulates extracellular signal-related kinase 1/2 (ERK1/2) phosphorylation in megakaryocytes, and the classic mitogen-activated protein (MAP) kinase (Raf/mitogen-induced extracellular kinase [MEK]/ERK) pathway has been implicated directly and indirectly to play a critical role in megakaryocytopoiesis. However, the involvement of specific Raf family members in megakaryocytopoiesis is unknown. raf-1-/- mice were therefore used to directly determine the role of Raf-1 in megakaryocytopoiesis. Surprisingly, raf-1-/- mice have a modestly higher platelet count than their raf-1+/+ littermates. Nonetheless, the absence of Raf-1 does not alter thrombopoietin-induced expansion of primary megakaryocyte-lineage cells, the development of apoptotic megakaryocytes in the presence or absence of thrombopoietin, or the development of megakaryocyte DNA ploidy distribution. Moreover, raf-1-/- megakaryocytes do not have a compensatory increase in A-Raf or B-Raf expression, and thrombopoietin-induced ERK1/2 phosphorylation is similar in raf-1-/- and raf-1+/+ megakaryocytes. These unexpected findings demonstrate that Raf-1 is dispensable for megakaryocytopoiesis, and for thrombopoietin-induced ERK1/2 activation in primary megakaryocyte-lineage cells.
Relative increase in leukemia-specific DNA in peripheral blood plasma from patients with acute myeloid leukemia and myelodysplasia
Authors: Rogers Anna , Joe Youngson , Manshouri Taghi , Dey Amanda , Jilani Iman , Giles Francis , Estey Elihu , Freireich Emil , Keating Michael , Kantarjian Hagop , Albitar Maher 
Published: October 2003

Abstract
Using loss of heterozygosity (LOH) and X-chromosome inactivation, we compared peripheral blood (PB) plasma with bone marrow (BM) cells in detecting genomic abnormalities in patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). We detected LOH in the PB plasma of all 45 patients who had cytogenetically documented chromosomal abnormalities (5q-, 7-, +8, 17-, or 20-). BM cells from the same patients showed LOH in 89% of patients with MDS and 70% of patients with AML. Posttherapy samples from 16 of these patients demonstrated complete concordance between LOH and cytogenetics in detecting residual disease in 15 samples. Of the 16 samples, 4 showed LOH in plasma with normal BM morphology. Using X-chromosome inactivation, clonality was detectable in 19 (73%) of 26 BM samples, whereas all PB plasma samples showed clonality. These data support the conclusion that PB plasma is enriched by tumor-specific DNA and can replace BM cells for studying genomic abnormalities. (Blood. 2004;103:2799-2801)
Antibody-induced intracellular signaling works in combination with radiation to eradicate lymphoma in radioimmunotherapy
Authors: Du Yong , Honeychurch Jamie , Cragg Mark S. , Bayne Mike , Glennie Martin J. , Johnson Peter W. M. , Illidge Tim M. 
Published: October 2003

AbstractRadioimmunotherapy (RIT) has emerged as an effective treatment for lymphoma, however the underlying mechanisms are poorly understood. We therefore investigated the relative contributions of antibody and targeted radiation to the clearance of tumor in vivo, using 2 different syngeneic murine B-cell lymphoma models. Although RIT with 131I–anti–major histocompatibility complex class II (MHCII) was effective in targeting radiation to tumor, no improvement in survival was seen by escalating the radiation dose alone and there were no long-term survivors. In contrast, using the combination of 131I anti-MHCII in the presence of unlabeled anti-idiotype (anti-Id), 100% prolonged disease-free survival was seen in both B-cell lymphoma models at the higher radiation dose. Using in vivo tracking we show that treatment with radiation plus anti-Id monoclonal antibody (mAb) results in a substantially greater reduction of splenic tumor cells than with either treatment alone. Prolonged survival could also be achieved using 131I anti-MHCII plus the signaling anti-CD19 mAb. Furthermore, the ability of these anti–B-cell mAbs to improve survival with targeted radiotherapy appeared to correlate with their ability to initiate intracellular signal transduction. Together these data illustrate that using 1 mAb to target radiation to tumor and a second to induce cell signaling is an effective new strategy in RIT.
Long-term outcome of hepatitis C infection after bone marrow transplantation
Authors: Peffault de Latour Régis , Lévy Vincent , Asselah Tarik , Marcellin Patrick , Scieux Catherine , Adès Lionel , Traineau Richard , Devergie Agnès , Ribaud Patricia , Espérou Hélène , Gluckman Eliane , Valla Dominique , Socié Gérard 
Published: October 2003

AbstractChronic hepatitis C is often asymptomatic, at least during the first decade following hematopoietic stem cell transplantation. Progression to advanced liver disease or cirrhosis in patients surviving more than 10 years is currently thought to be rare. Among 1078 patients who underwent an allogeneic transplantation between January 1973 and January 1995, 96 patients infected by hepatitis C virus (HCV) during the transplantation period were studied. Cumulative incidence and analysis of risk factors for cirrhosis were analyzed, and the rate and risk of cirrhosis in transplant recipients were compared with those of 158 HCV-infected controls who did not receive transplants. At a median follow-up of 15.7 years, 15 patients developed biopsy-proven cirrhosis, leading to a cumulative incidence of cirrhosis of 11% and 24% at 15 and 20 years, respectively. By multivariate analysis, extrahepatic HCV manifestations and HCV genotype 3 were associated with risk of cirrhosis. The median time to cirrhosis in transplant recipients was 18 years as compared with 40 years in the control population. The risk of cirrhosis in transplant recipients relative to controls was significantly higher by multivariate analysis (P = .0008). Roughly a quarter of long-term HCV-infected survivors with transplants progressed to cirrhosis that is much more rapid than in patients without transplants. Systematic detection of HCV infection, liver biopsy, and therapeutic intervention are therefore warranted in long-term marrow transplant recipients.
Prognosis at diagnosis: integrating molecular biologic insights into clinical practice for patients with CLL
Authors: Shanafelt Tait D. , Geyer Susan M. , Kay Neil E. 
Published: October 2003

Abstract
Heterogeneity in the clinical behavior of patients with chronic lymphocytic leukemia (CLL) makes it difficult for physicians to accurately identify which patients may benefit from an early or more aggressive treatment strategy and to provide patients with relevant prognostic information. Given the potential efficacy of newer therapies and the desire to treat patients at “optimum” times, it is more important than ever to develop sensitive stratification parameters to identify patients with poor prognosis. The evolution of risk stratification models has advanced from clinical staging and use of basic laboratory parameters to include relevant biologic and genetic features. This article will review the dramatic progress in prognostication for CLL and will propose statistical modeling techniques to evaluate the utility of these new measures in predictive models to help determine the optimal combination of markers to improve prognostication for individual patients. This discussion will also elaborate which markers and tools should be used in current clinical practice and evaluated in ongoing clinical trials.
Novel concatameric heparin-binding peptides reverse heparin and low-molecular-weight heparin anticoagulant activities in patient plasma in vitro and in rats in vivo
Authors: Schick Barbara P. , Maslow David , Moshinski Adrianna , Antonio James D. San 
Published: October 2003

AbstractPatients given unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) for prophylaxis or treatment of thrombosis sometimes suffer serious bleeding. We showed previously that peptides containing 3 or more tandem repeats of heparin-binding consensus sequences have high affinity for LMWH and neutralize LMWH (enoxaparin) in vivo in rats and in vitro in citrate. We have now modified the (ARKKAAKA)n tandem repeat peptides by cyclization or by inclusion of hydrophobic tails or cysteines to promote multimerization. These peptides exhibit high-affinity binding to LMWH (dissociation constant [Kd], ≈ 50 nM), similar potencies in neutralizing anti–Factor Xa activity of UFH and enoxaparin added to normal plasma in vitro, and efficacy equivalent to or greater than protamine. Peptide (ARKKAAKA)3VLVLVLVL was most effective in all plasmas from enoxaparin-treated patients, and was 4- to 20-fold more effective than protamine. Several other peptide structures were effective in some patients' plasmas. All high-affinity peptides reversed inhibition of thrombin-induced clot formation by UFH. These peptides (1 mg/300 g rat) neutralized 1 U/mL anti–Factor Xa activity of enoxaparin in rats within 1 to 2 minutes. Direct blood pressure and heart rate measurements showed little or no hemodynamic effect. These heparin-binding peptides, singly or in combination, are potential candidates for clinical reversal of UFH and LMWH in humans.
Ineffective hematopoiesis linked with a mitochondrial tRNA mutation (G3242A) in a patient with myelodysplastic syndrome
Authors: Gattermann Norbert , Wulfert Michael , Junge Bärbel , Germing Ulrich , Haas Rainer , Hofhaus Götz 
Published: October 2003

AbstractIn a patient with refractory anemia with excess blasts (RAEB), a somatic mutation of mitochondrial transfer RNALeu(UUR) was detected in bone marrow cells. Heteroduplex analysis indicated that 40% to 50% of mitochondrial DNA (mtDNA) molecules in the bone marrow (BM) carried the novel G3242A mutation. The proportion of mutant mtDNA was higher in CD34+ cells than in the unfractionated sample. Surprisingly, the mutation was not detectable by heteroduplex analysis in the peripheral blood (PB). However, PB CD34+ cells selected by immunomagnetic beads harbored the mutation with a proportion of approximately 50%. In hematopoietic colony assays, CD34+ cells from BM and PB yielded only colonies with wild-type mtDNA. These results indicate that the mtDNA mutation in CD34+ cells was associated with a maturation defect. Mitochondrial tRNA mutations impair mitochondrial protein synthesis, thereby causing dysfunction of the mitochondrial respiratory chain. We propose that this effect contributed to ineffective hematopoiesis in our patient.
DC-SIGN promotes exogenous MHC-I–restricted HIV-1 antigen presentation
Authors: Moris Arnaud , Nobile Cinzia , Buseyne Florence , Porrot Françoise , Abastado Jean-Pierre , Schwartz Olivier 
Published: October 2003

Abstract
Dendritic cells (DCs) facilitate HIV-1 spread in the host by capturing virions and transferring them to permissive lymphocytes in lymphoid organs. Lectins such as DC-specific ICAM-grabbing non-integrin (DC-SIGN) are involved in HIV-1 uptake by DCs, through high-affinity binding to viral envelope glycoproteins. We examined the role of DC-SIGN on the fate of incoming virions and on major histocompatibility complex class I (MHC-I)–restricted HIV-1 antigen presentation. We show that DC-SIGN expression in B-cell lines dramatically enhances viral internalization. In these cells, and also in primary DCs, most of the captured virions are rapidly degraded, likely in a lysosomal compartment. In addition, a fraction of incoming viral material is processed by the proteasome, leading to activation of anti–HIV-specific cytotoxic T lymphocytes (CTLs) by DC-SIGN–expressing cells. In DCs, DC-SIGN is not the only receptor involved, and redundant pathways of virus capture leading to antigen presentation likely coexist. Altogether, our results highlight new aspects of DC-SIGN interactions with HIV-1. The lectin does not significantly protect captured virions against degradation and promotes MHC-I exogenous presentation of HIV-1 antigens.
Specific inhibition of HIV-1 coreceptor activity by synthetic peptides corresponding to the predicted extracellular loops of CCR5
Authors: Agrawal Lokesh , VanHorn-Ali Zainab , Berger Edward A. , Alkhatib Ghalib 
Published: October 2003

Abstract
We used synthetic peptides to the extracellular loops (ECLs) of CCR5 to examine inhibitory effects on HIV infection/fusion with primary leukocytes and cells expressing recombinant CCR5. We show for the first time that peptides derived from the first, second, or third ECL caused dose-dependent inhibition of fusion and infection, although with varying potencies and specificities for envelope glycoproteins (Envs) from different strains. The first and third ECL peptides inhibited Envs from the R5 Ba-L strain and the R5X4 89.6 strain, whereas the second ECL peptide inhibited Ba-L but not 89.6 Env. None of the peptides affected fusion mediated by Env from the X4 LAV strain. Fusion mediated by Envs from several primary HIV-1 isolates was also inhibited by the peptides. These findings suggest that various HIV-1 strains use CCR5 domains in different ways. Experiments involving peptide pretreatment and washing, modulation of the expression levels of Env and CCR5, analysis of CCR5 peptide effects against different coreceptors, and inhibition of radiolabeled glycoprotein (gp) 120 binding to CCR5 suggested that the peptide-blocking activities reflect their interactions with gp120. The CCR5-derived ECL peptides thus provide a useful approach to analyze structure–function relationships involved in HIV-1 Env-coreceptor interactions and may have implications for the design of drugs that inhibit HIV infection.
Role of tissue factor and protease-activated receptors in a mouse model of endotoxemia
Authors: Pawlinski Rafal , Pedersen Brian , Schabbauer Gernot , Tencati Michael , Holscher Todd , Boisvert William , Andrade-Gordon Patricia , Frank Rolf Dario , Mackman Nigel 
Published: October 2003

Abstract
Sepsis is associated with a systemic activation of coagulation and an excessive inflammatory response. Anticoagulants have been shown to inhibit both coagulation and inflammation in sepsis. In this study, we used both genetic and pharmacologic approaches to analyze the role of tissue factor and protease-activated receptors in coagulation and inflammation in a mouse endotoxemia model. We used mice expressing low levels of the procoagulant molecule, tissue factor (TF), to analyze the effects of TF deficiency either in all tissues or selectively in hematopoietic cells. Low TF mice had reduced coagulation, inflammation, and mortality compared with control mice. Similarly, a deficiency of TF expression by hematopoietic cells reduced lipopolysaccharide (LPS)–induced coagulation, inflammation, and mortality. Inhibition of the down-stream coagulation protease, thrombin, reduced fibrin deposition and prolonged survival without affecting inflammation. Deficiency of either protease activated receptor-1 (PAR-1) or protease activated receptor-2 (PAR-2) alone did not affect inflammation or survival. However, a combination of thrombin inhibition and PAR-2 deficiency reduced inflammation and mortality. These data demonstrate that hematopoietic cells are the major pathologic site of TF expression during endotoxemia and suggest that multiple protease-activated receptors mediate crosstalk between coagulation and inflammation.
Deletion of the α-globin gene cluster as a cause of acquired α-thalassemia in myelodysplastic syndrome
Authors: Steensma David P. , Viprakasit Vip , Hendrick Alex , Goff David K. , Leach Joanne , Gibbons Richard J. , Higgs Douglas R. 
Published: October 2003

Abstract
Rarely, myelodysplastic syndrome (MDS) is complicated by an acquired form of α-thalassemia (α-thalassemia in myelodysplastic syndrome [ATMDS]) characterized by hypochromic, microcytic, anisopoikilocytic red blood cells with hemoglobin H (HbH) inclusions. Acquired mutations in ATRX, a chromatin remodeling gene, have recently been found in 12 patients with typical features of ATMDS, though they have not been detected in MDS patients with similar red blood cell findings but little HbH. The α-globin genes themselves have appeared normal in all ATMDS patients studied to date. Here we characterize the molecular defect in a unique MDS patient with rare HbH inclusions in which an abnormal clone lost a greater than 1.9-Mb segment of the telomeric region of the short arm of one allele of chromosome 16, including both α-globin genes. Red blood cell changes associated with this acquired somatic genotype (––/αα) are surprisingly severe, demonstrating that a minor globin chain imbalance may be unexpectedly deleterious during the abnormal erythropoiesis that occurs in the context of MDS.
Phenotypic and functional alterations of peripheral blood monocytes in neutrophil-specific granule deficiency
Authors: Shiohara Masaaki , Gombart Adrian F , Sekiguchi Yukio , Hidaka Eiko , Ito Susumu , Yamazaki Takashi , Koeffler H Phillip , Komiyama Atsushi 
Published: October 2003

AbstractNeutrophil-specific granule deficiency (SGD) is a rare, congenital disease characterized by atypical neutrophil structure and function, resulting in recurrent bacterial infections from early infancy. Homozygous recessive mutations in the CCAAT/enhancer-binding protein ɛ (C/EBPɛ) gene were described in two of five SGD patients, indicating loss of C/EBPɛ function as the primary genetic defect in this disease. C/EBPɛ is expressed in murine and human macrophages. Macrophages from the C/EBPɛ-deficient mice show impaired differentiation, phagocytic activity, and transcription of macrophage-specific genes. To determine if monocyte/macrophage cells are impacted in SGD, we analyzed phenotypic features of peripheral blood (PB) monocytes in a SGD individual lacking functional C/EBPɛ. Flow cytometric analysis of PB leukocytes revealed aberrant expression of CD45, CD11b, CD14, CD15, and CD16 on cells from the SGD individual. Also, the PB CD14+ cells from this individual, weakly stained for the monocyte-specific enzyme, nonspecific esterase, and electron microscopic examination, indicated morphologic differences between the SGD cells and those from normal controls. Serum interleukin (IL)-6 levels in the SGD individual during a severe bacterial infection were lower compared with levels in other non-SGD individuals with sepsis. In contrast, serum IL-8 levels were markedly elevated in the SGD individual compared with those of non-SGD individuals in sepsis. PB CD14+ cells from the SGD individual expressed higher IL-8 mRNA levels compared with normal controls in response to lipopolysaccharide and interferon-γ. These phenotypic and functional alterations of PB monocytes in the SGD individual suggest that C/EBPɛ plays a critical role in monocyte/macrophage development of humans and is consistent with observations in the murine system. This study implicates abnormalities in monocytes/macrophages and neutrophils in the onset and development of SGD.
Autocrine inhibitory influences of α-melanocyte-stimulating hormone in malignant pleural mesothelioma
Authors: Catania Anna , Colombo Gualtiero , Carlin Andrea , Garofalo Letizia , Gatti Stefano , Buffa Roberto , Carboni Nadia , Rosso Lorenzo , Santambrogio Luigi , Cantalamessa Luigi , Lipton James M 
Published: October 2003

AbstractMalignant pleural mesothelioma is a highly aggressive tumor arising from the mesothelial cells that line the pleural cavities. This tumor is resistant to most conventional anticancer treatments and appears to be very sensitive to growth-promoting influences of cytokines and growth factors. Identification of natural inhibitory pathways that control growth should aid discovery of novel therapeutic approaches. We hypothesized that α-melanocyte-stimulating hormone (α-MSH), which is produced by many cell types and antagonizes cytokines and growth factors, could be an endogenous inhibitory molecule in mesothelioma. Twelve mesothelioma cell lines were established from pleural effusions of patients with malignant mesothelioma. Mesothelioma cells were found to express mRNA for proopiomelanocortin and its processing enzymes; release α-MSH peptide into supernatants; and express melanocortin 1 receptor (MC1R), the high-affinity receptor for α-MSH. Immunoneutralization of MC1R in the cell lines enhanced expression of interleukin-8 (IL-8), IL-6, and transforming growth factor-β. These molecules promote mesothelioma proliferation and are considered therapeutic targets in this tumor. Coincubation of mesothelioma cells with synthetic α-MSH significantly reduced cell proliferation. The present research shows an autocrine-inhibitory circuit based on α-MSH and its receptor MC1R. Activation of MC1R by selective peptides or peptidomimetics might provide a novel strategy to reduce mesothelioma cell proliferation by taking advantage of this endogenous inhibitory circuit.