bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of thrombosis in melanoma allografts in mice by endogenous mast cell heparin
Authors: Corwin Mark , Yu Hon , Wang Jun , Nalcioglu Orhan , Su Min-Ying , Samoszuk Michael 
Published: July 2003

SummaryAn unexplained paradox of malignant melanoma is the apparent failure of the blood within the tumor to clot despite the presence of multiple factors that should promote blood clotting. Here we present histochemical evidence that human and murine melanomas are extensively infiltrated by abundant mast cells. Because mast cells contain the natural anticoagulant heparin, the present studies were aimed at defining the role of mast cell heparin in preventing the blood from clotting within B16 melanoma grafts in C57BL/6 J mice. Mice bearing B16 melanoma grafts were treated with non-specific or specific inhibitors of mast cell heparin (protamine or heparinase, respectively). After the drug treatment there was histologic and functional evidence of selective thrombosis of the blood vessels within the protamine and heparinase treated melanoma grafts. A similar, high degree of thrombosis was also observed in B16 tumors grown in transgenic NDST-2 knockout mice bearing a targeted disruption in the gene coding for mast cell heparin synthesis. The tumors grown in the protamine-treated animals were significantly smaller than the tumors from control (untreated mice). By contrast, the tumors treated with heparinase or grown in the NDST-2 knockout mice were significantly larger than the tumors from control (untreated) mice. We conclude that the intrinsic procoagulant properties of malignant melanoma are neutralized in vivo by the anticoagulant properties of endogenous heparin produced by mast cells that naturally infiltrate the tumor. Our results also suggest that thrombosis and hemostasis within melanoma may play a complex role in modulating the growth of the tumor.
The role of PAR4 in thrombin-induced thromboxane production in human platelets
Authors: Wu Chin-Chung , Hwang Tsong-Long , Liao Chang-Hui , Kuo Sheng-Chu , Lee Fang-Yu , Teng Che-Ming 
Published: July 2003

SummaryThere are two protease-activated receptors (PARs), PAR1 and PAR4, in human platelets. It has been suggested that PAR1 mediates platelet responses to low concentrations of thrombin, whereas PAR4 mediates signaling only at high concentrations. In the present study, we used a selective PAR4 blocker, YD-3, to investigate the role of PAR4 in thrombin-induced thromboxane formation in human platelets. YD-3 completely prevented thromboxane production by either a low concentration of thrombin (0.1 U/ml) or the PAR4 agonist peptide GYPGKF. In contrast, YD-3 did not affect thromboxane production caused by the PAR1 agonist peptide SFLLRN, collagen or arachidonic acid. YD-3 also decreased [3H]arachidonic acid release from thrombin-stimulated platelets. Moreover, desensitization of platelets with GYPGKF prevented low thrombin-induced thromboxane formation. The decreased thromboxane production by YD-3 is linked to inhibition of calcium influx in thrombin-stimulated platelets. These results suggest that PAR4 plays an important role in the regulation of thromboxane formation in platelets responding to thrombin through prolonged elevation of [Ca2+]i and activation of phospholipase A2. These data also indicate that PAR4 can be activated by relatively low concentrations of thrombin in human platelets. The selective inhibition of thrombin-induced thromboxane production by YD-3 may be of therapeutic benefit for thrombotic diseases.
Enhanced TNFα and oxidative stress in patients with heart failure: effect of TNFα on platelet O2
- production
Authors: Biase Luciano De , Pignatelli Pasquale , Lenti Luisa , Tocci Giuliano , Piccioni Fabiana , Riondino Silvia , Pulcinelli Fabio M. , Rubattu Speranza , Volpe Massimo , Violi Francesco 
Published: July 2003

SummaryExperimental studies have suggested that TNFα, a pro-inflammatory cytokine, may contribute to the deterioration of cardiovascular function through various mechanisms, including the generation of reactive oxygen species. It has not yet been demonstrated whether TNFα has prooxidant activity in patients with heart failure, and what the mechanism eventually resulting in this effect are.We analyzed 42 patients (38 men and 4 women, aged 26 to 74 years) with heart failure, secondary to idiopathic dilated car-diomyopathy (n=21), coronary artery disease (n=15), and valve disease (n=6), and 20 controls (18 men and 2 women, aged 49 to 67 years). Ten patients were in class I,9 in class II,15 in class III and 8 in class IV according to NYHA Classification. Blood samples were obtained from each patient to evaluate basal and collagen-induced platelet O2
- production, and plasma TNFα.
In vivo results showed increased platelet O2
- production and plasma TNFα levels in NYHA class III-IV compared with that in controls or in NYHA I-II (p<0,001); platelet O2
- production correlated significantly (R=0,6; p<0,01) with TNFα plasma levels. In vitro studies showed TNFα dose-dependently (5-40 pg/ml) induced platelet O2
- production, and that this effect was significantly inhibited by its specific inhibitor, WP9QY (1 μM); aspirin (100 μM), AACOCF3, a specific PLA2 inhibitor (14 μM), and DPI, an inhibitor of NADPH oxidase, significantly inhibited TNFα-mediated platelet O2
- production.This study suggests that in patients with heart failure, enhanced platelet O2
- production is mediated by TNFα via activation of arachidonic acid and NADPH oxidase pathways.
Prevention of thrombosis following deep arterial injury in rats by bovine activated protein C requiring co-administration of bovine protein S
Authors: Dahlbäck Björn , Arnljots Björn , Malm Karl 
Published: July 2003

SummaryThe antithrombotic effect of bovine activated protein C (bAPC) given with or without bovine protein S (bPS) was investigated in a rat model of deep arterial injury. A segment of the left common carotid artery was isolated between vascular clamps and opened longitudinally. An endarterectomy was performed and the arteriotomy was closed with a running suture, whereafter the vessel was reperfused by removing the clamps. The antithrombotic effect (vascular patency rates 31 minutes after reperfusion) and the arteriotomy bleeding were measured. Ten treatment groups each containing 10 rats and a control group of 20 animals were in a blind random fashion given intravenous bolus injections of increasing doses of activated protein C, with or without co-administration of protein S. The groups received either bAPC alone (0.8, 0.4, 0.2 or 0.1 mg/kg), bAPC (0.8, 0.4, 0.2, 0.1 or 0.05 mg/kg) combined with bPS (0.6 mg/kg), or bPS alone (0.6 mg/kg) whereas the control group received vehicle only. Administered alone, bAPC or bPS had no antithrombotic effect, regardless of dosage. In contrast, all groups that were treated with bAPC in combination with bPS demonstrated a significant antithrombotic effect, as compared to controls. Neither bAPC, bPS, nor the combination of bAPC and bPS increased the arteriotomy bleeding significantly compared to controls. In vitro clotting assays using bAPC or bPS alone yielded only minor prolongation of clotting time, whereas bAPC combined with bPS prolonged the clotting time considerably, demonstrating the dependence on the APC-cofactor activity of bPS for expression of anticoagulant activity by bAPC. In conclusion, our study shows the in vivo significance of protein S as a cofactor to activated protein C, and that potent anti-thrombotic effect can be achieved by low doses of bAPC combined with bPS, without producing hemorrhagic side effects.
Lymphangiogenic growth factors, receptors and therapies
Authors: Lohela Marja , Saaristo Anne , Veikkola Tanja , Alitalo Kari 
Published: July 2003

SummaryThe lymphatic vasculature is essential for the maintenance of normal fluid balance and for the immune responses, but it is also involved in a variety of diseases. Hypoplasia or dysfuction of the lymphatic vessels can lead to lymphedema, whereas hyperplasia or abnormal growth of these vessels are associated with lymphangiomas and lymphangiosarcomas. Lymphatic vessels are also involved in lymph node and systemic metastasis of cancer cells. Recent novel findings on the molecular mechanisms involved in lymphatic vessel development and regulation allow the modulation of the lymphangiogenic process and specific targeting of the lymphatic endothelium.Recent results show that the homeodomain transcription factor Prox-1 is an important lymphatic endothelial cell (LEC) fate-determining factor which can induce LEC-specific gene transcription even in blood vascular endothelial cells (BECs). This suggests that the distinct phenotypes of cells in the adult vascular endothelium are plastic and sensitive to transcriptional reprogramming, which might be useful for future therapeutic applications involving endothelial cellsVascular endothelial growth factor-C (VEGF-C) and VEGF-D are peptide growth factors capable of inducing the growth of new lymphatic vessels in vivo in a process called lymphangiogenesis. They belong to the larger family which also includes VEGF, placenta growth factor (PlGF) and VEGF-B. VEGF-C and VEGF-D are ligands for the endothelial cell specific tyrosine kinase receptors VEGFR-2 and VEGFR-3. In adult human as well as mouse tissues VEGFR-3 is expressed predominantly in lymphatic endothelial cells which line the inner surface of lymphatic vessels. While VEGFR-2 is thought to be the main mediator of angiogenesis, VEGFR-3 signaling is crucial for the development of the lymphatic vessels. Heterozygous inactivation of the VEGFR-3 tyrosine kinase leads to primary lymphedema due to defective lymphatic drainage in the limbs. Other factors that seem to be involved in lymphangiogenesis include the Tie/angiopoietin system, neuropilin-2 and integrin α9.VEGF-C induces lymphatic vessel growth, but high levels of VEGF-C also resulted in blood vessel leakiness and growth. The VEGFR-3-specific mutant form of VEGF-C called VEGF-C156S lacks blood vascular side effects but is sufficient for therapeutic lymphangiogenesis in a mouse model of lymphedema. As VEGF-C156S is a specific lymphatic endothelial growth factor in the skin, it provides an attractive molecule for pro-lymphangiogenic therapy.This publication was partially financed by Serono. Part of this paper was originally presented at the 2nd International Workshop on New Therapeutic Targets in Vascular Biology, which took place in Geneva, Switzerland from February 6-9, 2003.
Chlamydia pneumoniaeBinds to Platelets and Triggers P-Selectin Expression and Aggregation
Authors: Kälvegren Hanna , Majeed Meytham , Bengtsson Torbjörn 
Published: July 2003

Objective—Evidence linkingChlamydia pneumoniaeto atherosclerotic cardiovascular disease is expanding. Platelets are considered to play an essential role in cardiovascular diseases; however, so far platelets have not been associated with an infectious cause of atherosclerosis. This study aims to clarify the interaction betweenC pneumoniaeand platelets and possibly present a novel mechanism in the pathogenesis of atherosclerosis.Methods and Results—The effects ofC pneumoniaeon platelet aggregation and secretion were assessed with lumiaggregometry, and the ability ofC pneumoniaeto bind to platelets and stimulate expression of P-selectin was analyzed with flow cytometry. We found thatC pneumoniae, at a chlamydia:platelet ratio of 1:15, adheres to platelets and triggers P-selectin expression after 1 minute and causes an extensive aggregation and ATP secretion after 20 minutes of incubation. Inhibition of glycoprotein IIb/IIIa with Arg-Gly-Asp-Ser or abciximab markedly reducedC pneumoniae-induced platelet aggregation. Exposure ofC pneumoniaeto polymyxin B, but not elevated temperature, abolished the stimulatory effects on platelet activation, suggesting that chlamydial lipopolysaccharide has an active role. In contrast, other tested bacteria had no or only moderate effects on platelet functions.Conclusion—Our findings demonstrate a new concept of howC pneumoniaeactivates platelets and thereby may cause atherosclerosis and thrombotic vascular occlusion.
VLDL Induces Adipocyte Differentiation in ApoE-Dependent Manner
Authors: Chiba Tsuyoshi , Nakazawa Toru , Yui Katsumasa , Kaneko Eiji , Shimokado Kentaro 
Published: July 2003

Objective—To clarify the role of very low density lipoprotein (VLDL) and apolipoprotein E (apoE) in adipogenesis, we studied newly developed hyperlipidemic obese (ob/ob;apoE−/−) mice. Because hydrolysis of VLDL is believed to be the major source of adipogenic free fatty acids, a higher plasma level of VLDL in these mice should exaggerate obesity.Methods and Results—When fed a high-fat, high-cholesterol diet,ob/ob;apoE−/−mice did not show increased body weight or an increased amount of adipose tissue in spite of increased plasma VLDL levels, whereasob/obmice showed an increased body weight and amount of adipose tissue, suggesting that there is a novel apoE-dependent pathway for adipogenesis. In vitro experiments using bone marrow stromal cells and 3T3-L1 cells confirmed this notion. ApoE-deficient VLDL did not induce adipogenesis, whereas normal VLDL induced adipogenesis in these cells. The incubation of apoE-deficient VLDL with recombinant human apoE restored its adipogenic activity. Tetrahydrolipstatin, a lipoprotein lipase inhibitor, did not affect the adipogenic activity of VLDL, suggesting that hydrolysis of VLDL did not play a major role in its effects. In fact, lipid components of VLDL or free fatty acids induced only partial adipogenesis.Conclusions—Our findings indicate that VLDL induces adipogenesis in an apoE-dependent manner both in vitro and in vivo.
Eliciting Causal Beliefs about Heart Attacks: A Comparison of Implicit and Explicit Methods
Authors: French David P. , Marteau Theresa M. , Senior Victoria , Weinman John A. 
Published: July 2003

Objective To compare beliefs about the importance of different factors in causing heart attacks, elicited by explicit questionnaire ratings and an implicit vignette task. Method In two separate studies: (1) 107 adults (aged 40-60 years); and (2) 134 students completed two tasks: (a) a questionnaire in which they explicitly rated the importance of a number of causes of heart attacks; and (b) a vignette task in which they implicitly used risk factor information to estimate a hypothetical man’s likelihood of a heart attack. Results In both studies, family history was rated as a significantly less important cause than smoking or stress on the explicit questionnaire; in the implicit task, smoking and family history exerted a much greater influence on estimates of risk than did stress. Discussion The causal beliefs elicited by the two methods differ in important respects. The predictive validity of each measure, alone and in combination with other nonquestionnaire-based measures, needs to be determined.
Thioguanine offers no advantage over mercaptopurine in maintenance treatment of childhood ALL: results of the randomized trial COALL-92
Authors: Harms Dörthe O. , Göbel Ulrich , Spaar Hans J. , Graubner Ulrike B. , Jorch Norbert , Gutjahr Peter , Janka-Schaub Gritta E. ,   for the COALL Study Group
Published: July 2003

AbstractThe German cooperative study group for childhood acute lymphoblastic leukemia (COALL-92) was designed to examine the clinical effectiveness of thioguanine (TG) versus mercaptopurine (MP) in maintenance treatment of childhood acute lymphoblastic leukemia (ALL) in a randomized multicenter trial. TG and MP are prodrugs and have to be converted intracellularly to 6-thioguanine nucleotides (TGNs) for cytostatic activity. TG is converted into TGN in fewer steps and has been shown to be more cytotoxic in equimolar doses in vitro compared with 6-MP. Therefore, a higher effectiveness of TG in maintenance treatment was postulated. Of 521 patients enrolled into the protocol, 474 were randomized to receive either MP or TG during maintenance therapy in a daily oral dose. After a median observation time of 6.6 years, the probability of event-free survival was 79% ± 3% for the MP group (238 children) and 78% ± 3% in the TG group (236 patients). In spite of TGN levels, exceeding those of the MP group 7 times, treatment with TG did not improve the outcome but was more complicated to handle due to a specific toxicity profile of prolonged myelosuppression with marked thrombocytopenia. Therefore, MP should remain the preferred drug for maintenance treatment of ALL, unless other studies demonstrate superiority of TG in larger trials or selected patient groups.
A phase 2 clinical study of SU5416 in patients with refractory acute myeloid leukemia
Authors: Fiedler Walter , Mesters Rolf , Tinnefeld Heike , Loges Sonja , Staib Peter , Dührsen Ulrich , Flasshove Michael , Ottmann Oliver G. , Jung Wolfram , Cavalli Franco , Kuse Rolf , Thomalla Joerg , Serve Hubert , O'Farrell Anne M. , Jacobs Mark , Brega Nicoletta M. , Scigalla Paul , Hossfeld Dieter K. , Berdel Wolfgang E. 
Published: July 2003

Abstract
Neoangiogenesis has been shown to play an important role in the pathogenesis of acute myeloid leukemia (AML). Autocrine and paracrine secretion of angiogenic and hematopoietic growth factors such as vascular endothelial growth factor (VEGF) and stem cell factor (SCF) in the bone marrow microenvironment may promote proliferation and survival of leukemic blasts. This concept represented the rationale for the initiation of a multicenter phase 2 trial of SU5416, a small molecule inhibitor of phosphorylation of VEGF receptors 1 and 2, c-kit, the SCF receptor, and fms-like tyrosine kinase-3 (FLT3) in patients with advanced AML. Entered into the study were 43 patients with refractory AML or elderly patients not judged medically fit for intensive induction chemotherapy; 42 patients received at least one dose of study drug. Treatment was generally well tolerated, with nausea, headache, and bone pain the most frequent treatment-related side effects. One patient had a morphologic remission (French-American-British [FAB] criteria of complete response without normalization of blood neutrophil and platelet counts) lasting for 2 months. There were 7 patients who achieved a partial response (reduction of blasts by at least 50% in bone marrow and peripheral blood) lasting 1 to 5 months. Patients with AML blasts expressing high levels of VEGF mRNA by quantitative polymerase chain reaction (PCR) had a significantly higher response rate and reduction of bone marrow microvessel density than patients with low VEGF expression consistent with the antiangiogenic effects of SU5416.
Generation of autologous cytotoxic and helper T-cell responses against the B-cell leukemia–associated antigen HB-1: relevance for precursor B-ALL–specific immunotherapy
Authors: de Rijke Björn , Fredrix Hanny , Zoetbrood Agnes , Scherpen Frank , Witteveen Henry , de Witte Theo , van de Wiel-van Kemenade Elly , Dolstra Harry 
Published: July 2003

AbstractTumor relapses in patients with precursor B-cell acute lymphoblastic leukemia (BALL) occur frequently after primary treatment. Therefore, development of additional treatment modalities to eliminate residual tumor cells is needed. Active immunotherapy using dendritic cells (DCs) loaded with tumor-associated antigens is a promising approach to induce specific T-cell immunity in patients with cancer. In previous studies, we described HB-1 as a B-cell lineage-specific antigen that is recognized by donor-derived cytotoxic T lymphocytes (CTLs) on allogeneic B-ALL tumor cells. Here, we investigated the potential use of the HB-1 antigen as an autologous T-cell vaccine target. To determine whether HB-1–specific CTL precursors are present within the T-cell repertoire, we induced expansion of CD8+ T cells using mature monocyte-derived DCs pulsed with the previously identified HB-1.B44 antigenic peptide. In 6 of 8 donors, CD8+ CTL lines have been generated that exert cytotoxicity against target cells exogenously pulsed with peptide or endogenously expressing the HB-1 antigen. From one of these HB-1–specific T-cell lines, we isolated a CD8+ CTL that produces interferon-γ on stimulation with B-ALL tumor cells. Interestingly, the HB-1 antigen also induced CD4+ T-helper responses on activation with protein-loaded mature monocyte-derived DCs. We identified 2 novel epitopes recognized in the context of HLA-DR4 and HLA-DR11 with the use of HB-1–specific CD4+ T-cell clones generated from different donors. These present data, that HB-1 induces both helper and cytotoxic T-cell responses, indicate that the HB-1 antigen is a candidate target to induce T-cell–mediated antitumor immunity in patients.
The scavenger receptor MARCO mediates cytoskeleton rearrangements in dendritic cells and microglia
Authors: Granucci Francesca , Petralia Filippo , Urbano Matteo , Citterio Stefania , Di Tota Francesco , Santambrogio Laura , Ricciardi-Castagnoli Paola 
Published: July 2003

AbstractMacrophage receptor with collagenous structure (MARCO) is a scavenger receptor expressed in peritoneal macrophages and in a subpopulation of macrophages in the marginal zone of the spleen and in the medullary cord of lymph nodes. By global gene expression analysis, it has been found that the MARCO mRNA was one of the most up-regulated in splenic dendritic cells (DCs) following lipopolysaccharide or bacterial activation and in granulocyte-macrophage colony-stimulating factor (GM-CSF)–treated microglial cells. Here we show that MARCO is expressed on splenic DCs at late time points after activation and that its expression correlates with profound changes in actin cytoskeleton organization in DCs and microglia. During maturation, DCs undergo profound rearrangements of actin cytoskeleton. Immature DCs are adherent with visible actin cables, while fully mature, MARCO-expressing, splenic DCs are nonadherent, round in shape, and have an actin cytoskeleton with a punctate distribution. The simple expression of MARCO was sufficient to induce these cytoskeleton modifications in DCs. MARCO-transfected immature DCs acquired a typical morphology of mature DCs and did not rearrange the actin cytoskeleton following activation. Moreover, DCs in which MARCO was knocked down did not reach the mature phenotype and maintained the typical morphology of transitional DCs. MARCO expression in DCs and microglial cells was also associated with a decrease of antigen internalization capacity. Thus, the MARCO receptor is important for actin cytoskeleton rearrangements and the down-regulation of antigen uptake function during DC and microglial cell maturation.