bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fibrinogen binding to the integrin αIIbβ3 modulates store-mediated calcium entry in human platelets
Authors: Rosado Juan A. , Meijer Else M. Y. , Hamulyak Karly , Novakova Irena , Heemskerk Johan W. M. , Sage Stewart O. 
Published: July 2002

AbstractEffects of the occupation of integrin αIIbβ3 by fibrinogen on Ca++signaling in fura-2–loaded human platelets were investigated. Adding fibrinogen to washed platelet suspensions inhibited increases in cytosolic [Ca++] concentrations ([Ca++]i) evoked by adenosine diphosphate (ADP) and thrombin in a concentration-dependent manner in the presence of external Ca++ but not in the absence of external Ca++ or in the presence of the nonselective cation channel blocker SKF96365, indicating selective inhibition of Ca++entry. Fibrinogen also inhibited store-mediated Ca++ entry (SMCE) activated after Ca++ store depletion using thapsigargin. The inhibitory effect of fibrinogen was reversed if fibrinogen binding to αIIbβ3 was blocked using RDGS or abciximab and was absent in platelets from patients homozygous for Glanzmann thrombasthenia. Fibrinogen was without effect on SMCE once activated. Activation of SMCE in platelets occurs through conformational coupling between the intracellular stores and the plasma membrane and requires remodeling of the actin cytoskeleton. Fibrinogen inhibited actin polymerization evoked by ADP or thapsigargin in control cells and in cells loaded with the Ca++ chelator dimethyl BAPTA. It also inhibited the translocation of the tyrosine kinase p60src to the cytoskeleton. These results indicate that the binding of fibrinogen to integrin αIIbβ3 inhibits the activation of SMCE in platelets by a mechanism that may involve modulation of the reorganization of the actin cytoskeleton and the cytoskeletal association of p60src. This action may be important in intrinsic negative feedback to prevent the further activation of platelets subjected to low-level stimuli in vivo.
Signal-regulatory protein α (SIRPα) but not SIRPβ is involved in T-cell activation, binds to CD47 with high affinity, and is expressed on immature CD34+CD38−hematopoietic cells
Authors: Seiffert Martina , Brossart Peter , Cant Charles , Cella Marina , Colonna Marco , Brugger Wolfram , Kanz Lothar , Ullrich Axel , Bühring Hans-Jörg 
Published: July 2002

AbstractSignal-regulatory proteins (SIRPs) represent a new family of inhibitory/activating receptor pairs. They consist of 3 highly homologous immunoglobulin (Ig)–like domains in their extracellular regions, but differ in their cytoplasmic regions by the presence (SIRPα) or absence (SIRPβ) of immunoreceptor tyrosine-based inhibitory motifs (ITIMs). To analyze the differential expression on hematopoietic cells, function and ligand binding capacity of SIRPα and SIRPβ molecules, soluble fusion proteins consisting of the extracellular domains of SIRPα1, SIRPα2, and SIRPβ1, as well as SIRPα/β-specific and SIRPβ-specific monoclonal antibodies (MoAbs) were generated. In contrast to SIRPα1 and SIRPα2, no adhesion of SIRPβ1 to CD47 could be detected by cell attachment assays and flow cytometry. Using deletion constructs of SIRPα1, the epitope responsible for SIRPα1 binding to CD47 could be confined to the N-terminal Ig-like loop. Flow cytometry analysis with SIRPα/β- and SIRPβ-specific MoAbs revealed that SIRPα but not SIRPβ is expressed on CD34+CD38− hematopoietic cells. In addition, a strong SIRPα expression was also observed on primary myeloid dendritic cells (DCs) from peripheral blood as well as on in vitro generated DCs. Analysis of the T-cell stimulatory capacity of in vitro generated DCs in the presence of soluble SIRPα1 fusion proteins as well as SIRPα/β-specific and CD47-specific MoAbs revealed a significant reduction of T-cell proliferation in mixed lymphocyte reaction and inhibition of induction of primary T-cell responses under these conditions. In contrast, soluble SIRPα or SIRPβ-specific antibodies had no effect. The data suggest that the interaction of SIRPα with CD47 plays an important role during T-cell activation and induction of antigen-specific cytotoxic T-lymphocyte responses by DCs.
Molecular identification of Knops blood group polymorphisms found in long homologous region D of complement receptor 1
Authors: Moulds Joann M. , Zimmerman Peter A. , Doumbo Ogobara K. , Kassambara Lalla , Sagara Issaka , Diallo Dapa A. , Atkinson John P. , Krych-Goldberg Malgorzata , Hauhart Richard E. , Hourcade Dennis E. , McNamara David T. , Birmingham Daniel J. , Rowe J. Alexandra , Moulds John J. , Miller Louis H. 
Published: July 2002

AbstractComplement receptor 1 (CR1) has been implicated in rosetting of uninfected red blood cells to Plasmodium falciparum–infected cells, and rosette formation is associated with severe malaria. The Knops blood group (KN) is located on CR1 and some of these antigens, ie, McCoy (McC) and Swain-Langley (Sla), show marked frequency differences between Caucasians and Africans. Thus, defining the molecular basis of these antigens may provide new insight into the mechanisms of P falciparummalaria. Monoclonal antibody epitope mapping and serologic inhibition studies using CR1 deletion constructs localized McC and Slato long homologous repeat D of CR1. Direct DNA sequencing of selected donors identified several single nucleotide polymorphisms in exon 29 coding for complement control protein modules 24 and 25. Two of these appeared to be blood group specific: McC associated with K1590E and Sla with R1601G. These associations were confirmed by inhibition studies using allele-specific mutants. A sequence-specific oligonucleotide probe hybridization assay was developed to genotype several African populations and perform family inheritance studies. Concordance between the 1590 mutation and McC was 94%; that between Sla and 1601 was 88%. All but 2 samples exhibiting discrepancies between the genotype and phenotype were found to be due to low red cell CR1 copy numbers, low or absent expression of some alleles, or heterozygosity combined with low normal levels of CR1. These data further explain the variability observed in previous serologic studies of CR1 and show that DNA and protein-based genetic studies will be needed to clarify the role of the KN antigens in malaria.
Generation of definitive hematopoietic stem cells from murine early yolk sac and paraaortic splanchnopleures by aorta-gonad-mesonephros region–derived stromal cells
Authors: Matsuoka Sahoko , Tsuji Kohichiro , Hisakawa Hiroaki , Xu Ming-jiang , Ebihara Yasuhiro , Ishii Takefumi , Sugiyama Daisuke , Manabe Atsushi , Tanaka Ryuhei , Ikeda Yasuo , Asano Shigetaka , Nakahata Tatsutoshi 
Published: July 2002

AbstractThere is controversy as to whether murine definitive hematopoiesis originates from yolk sac (YS) or the intraembryonic region. This study reports the generation of definitive hematopoietic stem cells (HSCs) from both early YS and intraembryonic paraaortic splanchnopleures (P-Sp) on AGM-S3 stromal cells derived from the aorta-gonad-mesonephros (AGM) region at 10.5 days post coitum (dpc). YS and P-Sp cells at 8.5 dpc generated no definitive hematopoiesis-derived colony-forming cells in cocultures with AGM-S3 cells, but spleen colony-forming cells and HSCs capable of reconstituting definitive hematopoiesis in adult mice simultaneously appeared on day 4 of coculture. Precursors for definitive HSCs were present in YS and P-Sp at 8.0 dpc, a time when YS and embryo were not connected by blood vessels. It is proposed that precursors with the potential to generate definitive HSCs appear independently in YS and intraembryonic P-Sp and that the P-Sp or AGM region affords the microenvironment that facilitates generation of definitive hematopoiesis from precursors.
Rescue of the colony-stimulating factor 1 (CSF-1)–nullizygous mouse (Csf1op/Csf1op) phenotype with a CSF-1 transgene and identification of sites of local CSF-1 synthesis
Authors: Ryan Gregory R. , Dai Xu-Ming , Dominguez Melissa G. , Tong Wei , Chuan Fenchi , Chisholm Orin , Russell Robert G. , Pollard Jeffrey W. , Stanley E. Richard 
Published: July 2002

AbstractColony-stimulating factor 1 (CSF-1) regulates the survival, proliferation, and differentiation of mononuclear phagocytes. It is expressed as a secreted glycoprotein or proteoglycan found in the circulation or as a biologically active cell-surface glycoprotein. To investigate tissue CSF-1 regulation, CSF-1–nullCsf1op/Csf1opmice expressing transgenes encoding the full-length membrane-spanning CSF-1 precursor driven by 3.13 kilobases of the mouse CSF-1 promoter and first intron were characterized. Transgene expression corrected the gross osteopetrotic, neurologic, weight, tooth, and reproductive defects ofCsf1op/Csf1opmice. Detailed analysis of one transgenic line revealed that circulating CSF-1, tissue macrophage numbers, hematopoietic tissue cellularity, and hematopoietic parameters were normalized. Tissue CSF-1 levels were normal except for elevations in 4 secretory tissues. Skin fibroblasts from the transgenic mice secreted normal amounts of CSF-1 but also expressed some cell-surface CSF-1. Also, lacZ driven by the same promoter/first intron revealed β-galactosidase expression in hematopoietic, reproductive, and other tissue locations proximal to CSF-1 cellular targets, consistent with local regulation by CSF-1 at these sites. These studies indicate that the 3.13-kilobase promoter/first intron confers essentially normal CSF-1 expression. They also pinpoint new cellular sites of CSF-1 expression, including ovarian granulosa cells, mammary ductal epithelium, testicular Leydig cells, serous acinar cells of salivary gland, Paneth cells of the small intestine, as well as local sites in several other tissues.
The deubiquitinating enzyme DUB-2 prolongs cytokine-induced signal transducers and activators of transcription activation and suppresses apoptosis following cytokine withdrawal
Authors: Migone Thi-Sau , Humbert Martine , Rascle Anne , Sanden David , D'Andrea Alan , Johnston James A. 
Published: July 2002

AbstractCytokines, such as interleukin-2 (IL-2), activate intracellular signaling pathways via rapid tyrosine phosphorylation of their receptors, resulting in the activation of many genes involved in cell growth and survival. The deubiquitinating enzyme DUB-2 is induced in response to IL-2 but as yet its function has not been determined. The results of this study show that DUB-2 is expressed in human T-cell lymphotropic virus-I(HTLV-1)–transformed T cells that exhibit constitutive activation of the IL-2 JAK/STAT (signal transducers and activators of transcription) pathway, and when expressed in Ba/F3 cells DUB-2 markedly prolonged IL-2–induced STAT5 phosphorylation. Although DUB-2 did not enhance IL-2–mediated proliferation, when withdrawn from growth factor, cells expressing DUB-2 had sustained STAT5 phosphorylation and enhanced expression of IL-2–induced genescis and c-myc. Moreover, DUB-2 expression markedly inhibited apoptosis induced by cytokine withdrawal allowing cells to survive. Taken together these data suggest that DUB-2 can enhance signaling through the JAK/STAT pathway, prolong lymphocyte survival, and, when constitutively expressed, may contribute to the activation of the JAK/STAT pathway observed in some transformed cells.
A point mutation in the cysteine-rich domain of glycoprotein (GP) IIIa results in the expression of a GPIIb-IIIa (αIIbβ3) integrin receptor locked in a high-affinity state and a Glanzmann thrombasthenia–like phenotype
Authors: Ruiz Catherine , Liu Chao-Yan , Sun Qi-Hong , Sigaud-Fiks Marianne , Fressinaud Edith , Muller Jean-Yves , Nurden Paquita , Nurden Alan T. , Newman Peter J. , Valentin Nathalie 
Published: July 2002

AbstractThis article reports a Glanzmann thrombasthenia (GT) patient, N.M., with a point mutation in the third cysteine-rich repeat of β3-integrin or platelet glycoprotein (GP) IIIa, leading to the expression of a constitutively activated fibrinogen receptor. The diagnosis of GT was based on a severely reduced platelet-aggregation response to a series of agonists and approximately 20% of surface-expressed GPIIb-IIIa. The patient's GPIIb-IIIa constitutively expressed epitopes recognized by antibodies to ligand-induced binding sites (LIBS) and also spontaneously bound the fibrinogen-mimetic antibody, PAC-1. Furthermore, significant amounts of bound fibrinogen were detected on his platelets ex vivo. No signs of platelet activation were observed on sections of unstimulated platelets from N.M. by electron microscopy. Immunogold labeling highlighted the presence of surface-bound fibrinogen but revealed platelet heterogeneity with regard to the surface density. When the patient's platelets were stimulated by thrombin-receptor activating peptide, amounts of surface-expressed GPIIb-IIIa increased and the aggregation response improved, although it failed to normalize. Platelets from N.M. were able to adhere and spread on immobilized fibrinogen. Sequence analysis of genomic DNA from N.M. revealed a homozygous g1776T&gt;C mutation in GPIIIa, leading to a Cys560Arg amino acid substitution. A stable Chinese hamster ovary (CHO) cell line was prepared expressing surface GPIIb-Arg560IIIa. Like platelets from the patient, GPIIb-Arg560IIIa–transfected CHO cells constitutively bound LIBS antibodies and PAC-1. They also showed an enhanced ability to adhere on surface-bound fibrinogen. Overall, these data demonstrate that a gain-of-function mutation can still be associated with a thrombasthenic phenotype even though platelets show spontaneous fibrinogen binding.
An IRP-like protein from Plasmodium falciparum binds to a mammalian iron-responsive element
Authors: Loyevsky Mark , LaVaute Timothy , Allerson Charles R. , Stearman Robert , Kassim Olakunle O. , Cooperman Sharon , Gordeuk Victor R. , Rouault Tracey A. 
Published: July 2002

AbstractThis study cloned and sequenced the complementary DNA (cDNA) encoding of a putative malarial iron responsive element-binding protein (PfIRPa) and confirmed its identity to the previously identified iron-regulatory protein (IRP)–like cDNA from Plasmodium falciparum. Sequence alignment showed that the plasmodial sequence has 47% identity with human IRP1. Hemoglobin-free lysates obtained from erythrocyte-stage P falciparum contain a protein that binds a consensus mammalian iron-responsive element (IRE), indicating that a protein(s) with iron-regulatory activity was present in the lysates. IRE-binding activity was found to be iron regulated in the electrophoretic mobility shift assays. Western blot analysis showed a 2-fold increase in the level of PfIRPa in the desferrioxamine-treated cultures versus control or iron-supplemented cells. Malarial IRP was detected by anti-PfIRPa antibody in the IRE-protein complex fromP falciparum lysates. Immunofluorescence studies confirmed the presence of PfIRPa in the infected red blood cells. These findings demonstrate that erythrocyte P falciparum contains an iron-regulated IRP that binds a mammalian consensus IRE sequence, raising the possibility that the malaria parasite expresses transcripts that contain IREs and are iron-dependently regulated.
Activation of 5-lipoxygenase by cell stress is calcium independent in human polymorphonuclear leukocytes
Authors: Werz Oliver , Bürkert Eva , Samuelsson Bengt , Rådmark Olof , Steinhilber Dieter 
Published: July 2002

Abstract5-Lipoxygenase (5-LO) is the key enzyme in the biosynthesis of proinflammatory leukotrienes. This study showed that various forms of cell stress, such as chemical stress (sodium arsenite), osmotic stress, or heat shock lead to substantial formation of 5-LO products in freshly isolated human polymorphonuclear leukocytes (PMNLs), when exogenous arachidonic acid (10 μM) was present. In parallel, cell stress led to activation of p38 MAPK (mitogen-activated protein kinase) and mitogen-activated protein kinase-activated protein kinases (MAPKAPKs) kinases, which can phosphorylate 5-LO in vitro. Interestingly, arsenite also caused redistribution of 5-LO from the cytosol to the nuclear membrane. Only minor activation of extracellular signal-regulated kinases and c-jun NH2-terminal kinases was observed, implying that these MAPKs are less important for 5-LO product formation in stress-stimulated PMNLs. Stimulation of 5-LO product formation by Ca++-ionophore A23187 or thapsigargin depended on Ca++; almost no 5-LO product formation was observed in freshly isolated PMNLs when Ca++ was depleted by chelating agents. Also the response toN-formylmethionyl-leucyl-phenylalanine (fMLP) was clearly diminished, but some 5-LO product formation remained. In contrast, stress-induced product formation and translocation of 5-LO, as well as activation of p38 MAPK, occurred also after Ca++ depletion. Moreover, the p38 MAPK inhibitor SB203580 blocked stress-induced 5-LO product formation efficiently, whereas ionophore- or thapsigargin-induced formation of 5-LO products was less sensitive. These data show that cell stress can activate 5-LO in isolated PMNLs by a mechanism that does not involve Ca++ mobilization. This mechanism could function independently of Ca++-mediated 5-LO activation for stimulation of leukotriene biosynthesis under physiologic conditions as well as in inflammatory diseases.
Pathways for internalization and recycling of the chemokine receptor CCR5
Authors: Mueller Anja , Kelly Eamonn , Strange Philip G. 
Published: July 2002

AbstractM-tropic human immunodeficiency virus (HIV-1) strains enter the cell after interaction with their receptors, CD4 and the G-protein–coupled chemokine receptor CCR5. The number of cell surface CCR5 molecules is thought to be important in determining the infection rate for HIV. Cell surface CCR5 is dependent on the rate of receptor internalization and recycling. Internalization of G-protein–coupled receptors after agonist activation is thought to occur either through clathrin-coated pits or through caveolae. In this study, the role of these different pathways was investigated in Chinese hamster ovary cells expressing CCR5 using specific inhibitors. Internalization of CCR5 after chemokine treatment was inhibited by sucrose, indicating a role for the clathrin-coated pit pathway. Activation of CCR5 leads to arrestin-2 movement in the cells, providing further evidence for the involvement of clathrin-coated pits. Nystatin and filipin also affected the rate of internalization of CCR5, indicating a role for caveolae. Using inhibitors of vesicle transport in the cell, it was found that the CCR5 recycling pathway is independent of the Golgi apparatus and late endosomes. Protein synthesis is not involved in receptor recovery. It seems likely that after internalization, CCR5 is directed to early endosomes and subsequently recycled to the cell surface.
Adjuvant Therapy in Rectal Cancer: Analysis of Stage, Sex, and Local Control—Final Report of Intergroup 0114
Authors: Tepper J.E. , O’Connell M. , Niedzwiecki D. , Hollis D.R. , Benson A.B. , Cummings B. , Gunderson L.L. , Macdonald J.S. , Martenson J.A. , Mayer R.J. 
Published: July 2002

PURPOSE: The gastrointestinal Intergroup studied postoperative adjuvant chemotherapy and radiation therapy in patients with T3/4 and N+ rectal cancer after potentially curative surgery to try to improve chemotherapy and to determine the risk of systemic and local failure. PATIENTS AND METHODS: All patients had a potentially curative surgical resection and were treated with two cycles of chemotherapy followed by chemoradiation therapy and two additional cycles of chemotherapy. Chemotherapy regimens were bolus fluorouracil (5-FU), 5-FU and leucovorin, 5-FU and levamisole, and 5-FU, leucovorin, and levamisole. Pelvic irradiation was given to a dose of 45 Gy to the whole pelvis and a boost to 50.4 to 54 Gy. RESULTS: One thousand six hundred ninety-five patients were entered and fully assessable, with a median follow-up of 7.4 years. There was no difference in overall survival (OS) or disease-free survival (DFS) by drug regimen. DFS and OS decreased between years 5 and 7 (from 54% to 50% and 64% to 56%, respectively), although recurrence-free rates had only a small decrease. The local recurrence rate was 14% (9% in low-risk [T1 to N2+] and 18% in high-risk patients [T3N+, T4N]). Overall, 7-year survival rates were 70% and 45% for the low-risk and high-risk groups, respectively. Males had a poorer overall survival rate than females. CONCLUSION: There is no advantage to leucovorin- or levamisole-containing regimens over bolus 5-FU alone in the adjuvant treatment of rectal cancer when combined with irradiation. Local and distant recurrence rates are still high, especially in T3N+ and T4 patients, even with full adjuvant chemoradiation therapy.
Intraoperative Sentinel Lymph Node Mapping in Non–Small-Cell Lung Cancer Improves Detection of Micrometastases
Authors: Liptay Michael J. , Grondin Sean C. , Fry Willard A. , Pozdol Chris , Carson Doreine , Knop Carol , Masters Gregory A. , Perlman Reid M. , Watkin William 
Published: July 2002

PURPOSE: Lymph node metastases are the most significant prognostic factor in localized non–small-cell lung cancer (NSCLC). Nodal micrometastases may not be detected with current standard histologic methods. We performed intraoperative technetium-99m (99mTc) sentinel lymph node (SN) mapping in patients with resectable NSCLC. This study aimed to identify the first station of nodal drainage of operable lung cancers. Serial section histology and immunohistochemistry were used to validate the SN and to identify the presence of micrometastatic disease.PATIENTS AND METHODS: One hundred patients with potentially resectable suspected NSCLC were enrolled. At thoracotomy, the primary tumor was injected with 0.25 to 2 mCi99mTc. Intraoperative scintigraphic readings of both the primary tumor and lymph nodes were obtained with a hand-held gamma counter. Anatomic resection with a mediastinal node dissection was then performed.RESULTS: Nine of the 100 patients did not have NSCLC (seven benign lesions and two metastatic tumors) and were excluded. Seventy-eight (86%) of 91 patients had a SN identified and a complete resection. Sixty-nine (88.5%) out of the 78 SNs were classified as true-positive with no metastases found in other intrathoracic lymph nodes without concurrent SN involvement. In nine patients, the SN was the only positive node. In seven of these nine patients, the SN was found to harbor only micrometastatic disease.CONCLUSION: Intraoperative SN mapping with99mTc is an accurate way to identify the first site of lymphatic tumor drainage in NSCLC. This method may also improve the precision of pathologic staging.