bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hematopoietic Stem Cell Engraftment in Bone Marrow Is Dependent upon Gsα.
Authors: Adams Gregor B. , Alley Ian R. , Chabner Karissa T. , Chung Ung-il , Marsters Emily S. , Weinstein Lee S. , Kronenberg Henry M. , Scadden David T. 
Published: April 2020

Abstract
During development, hematopoietic stem cells (HSCs) translocate from the fetal liver to the bone marrow, which remains the site of hematopoiesis throughout adulthood. In the bone marrow the HSCs are located at the endosteal surface, where the osteoblasts are a key component of the stem cell niche. The exogenous signals that specifically direct HSCs to the bone marrow have been thought to include stimulation of the chemokine receptor CXCR4 by its cognate ligand stromal derived factor-1α (SDF-1α or CXCL12). However, experiments in which CXCR4−/− fetal liver hematopoietic cells were transplanted into wild-type hosts demonstrated efficient engraftment of the HSCs in the bone marrow. In addition, treatment of HSCs with inhibitors of Gαi-coupled signaling, which blocks transmigration towards SDF-1αin vitro, does not affect bone marrow homing and engraftment in vivo. Therefore, we examined whether Gsα-coupled mechanisms play a key role in the engraftment of the HSCs in the bone marrow environment. Utilizing an inducible-conditional knockout of Gsα, we found that deletion of the gene in hematopoietic bone marrow cells did not affect their ability to perform in the in vitro primitive CFU-C or LTC-IC assay systems. However, Gsα−/− cells were unable to establish effective hematopoiesis in the bone marrow microenvironment in vivo in a competitive repopulation assay (41.1% contribution from wild-type cells versus 1.4% from knockout cells). These effects were not due to an inability of the cells to function in the bone marrow in vivo as deletion of Gsα following establishment of hematopoiesis had no effects on the HSCs. Examining the ability of the HSCs to home to the bone marrow, though, demonstrated that deletion of Gsα resulted in a marked impairment of the ability of the stem cells to localize to the marrow space (approximately 9-fold reduction in the level of primitive cell homing). Furthermore, treatment of BM MNCs with an activator of Gsα augmented the cells homing and thus engraftment potential. These studies demonstrate that Gsα is critical to the localization of HSCs to the bone marrow. Which receptors utilize this pathway in this context remains unknown. However, Gsα represents a previously unrecognized signaling pathway for homing and engraftment of HSCs to bone marrow. Pharmacologic activation of Gsα in HSC ex vivo prior to transplantation offers a potential method for enhancing stem cell engraftment efficiency.
Suspension of Vitamin K Antagonists Is Not Required for Cataract Surgery: A Prospective Study in a Cohort of 135 Consecutive Patients on Long-Term Anticoagulant Therapy.
Authors: Pollio Berardino , Demarie Giuseppe A. , Ocello Patrizia , Delios Grazia , Tucciarone Marco , Aitoro Gabriele , Perna Rossella , D’Ardia Stefano , Ladetto Marco , Bauchiero Luigi , Girotto Mauro 
Published: April 2020

Abstract
The perioperative management of oral anticoagulant therapy (OAT) often arouses controversy between surgeons and internists.
In geriatric patients, cataract surgery for those who are taking vitamin K antagonists is a common clinical procedure. Phacoemulsification requires a 3 mm incision involving a tissue devoid of blood vessels. This study reports the experience of an Italian Anticoagulation Management Service (AMS) with 135 anticoagulated patients on long-term anticoagulant therapy who underwent phacoemulsification performed by the same ophthalmologist team from January 2001 to December 2005. The patients received either topical (30%) or peribulbar (70%) anaesthesia. Data were collected by physicians with specialized software, but the dosage of oral anticoagulant was manual. Two oral vitamin K antagonisists are available in Italy: acenocumarol and warfarin. We prepared all patients in accordance with the following standardized protocol :
the scheduled dose was always omitted the day before surgery an INR measurement was provided 3–5 days before the invasive procedure; if the patient’s INR was below 3, we simply omitted the scheduled dose of the day before cataract surgery if the patient’s INR was above 3, we withheld two or more scheduled doses to allow the INR to fall to 2.5 or less 1 hour before cataract surgery, INR was measured if the patient’s INR was below 2.5, phacoemulsification was performed
Results: This standardized procedural protocol allowed the surgeon to carry out phacoemulsification with INR always below 2.5. We observed only one peribulbar bleeding (0.7%) during peribulbar anaesthesia before the corneal incision was made. No thromboembolic complications were registered during three months of follow up. We compared our results with the data of an earlier cohort of 7014 conventional patients who underwent this eye surgery in the same ophthalmologic institute. We did not observe statistical differences between the two groups with regard to hemorragic complications.
Conclusions: The risk of thromboembolism when antithrombotic therapy is interrupted is a well-grounded concern, particularly for patients with mechanical heart valves. Low molecular weight heparin bridging is a valid but more complicated alternative. Our study demonstrates the feasibility and safety of this simple standardized protocol which avoids OAT interruption. Therefore, we conclude that in patients receiving OAT, it is not necessary for the anticoagulant effect to wear off before cataract surgery is performed.
rNAPc2, a Novel Inhibitor of Tissue Factor/Factor VIIa Complex, Suppresses Lung Metastasis and Synergizes with 5-FU or Bevacizumab in Mouse Models of Colorectal Cancer.
Authors: Zhao Jingsong , Aguilar Gerard , Deitcher Steven R. , Funk Walter , Abo Arie 
Published: April 2020

Abstract
Recombinant nematode anticoagulant protein c2 (rNAPc2) is a specific inhibitor of tissue factor (TF)/factor VIIa complex with novel anti-metastasis, anti-angiogenesis, and anti-thrombosis activities. rNAPc2 has been previously shown to inhibit both the primary growth and metastasis of murine B16 melanoma and Lewis lung carcinoma in mice. TF is highly expressed in human colorectal tumors and the level of TF expression positively correlates with the progression of malignancy. To explore the therapeutic potential of rNAPc2 during tumor growth and progression, we tested rNAPc2 efficacy in experimental colorectal cancer in mice. Both primary and metastatic colorectal tumor models were used in the current study and rNAPc2 was given to mice via daily intraperitoneal injections. Administration of rNAPc2 inhibited pulmonary metastasis in mice systemically disseminated with CT26 murine colon carcinoma cells in a dose-dependent fashion, as measured by either number of lung surface metastases or lung mass. While rNAPc2 treatment alone moderately reduced primary tumor growth, combining rNAPc2 with the cytotoxic agent 5-fluorouracil (5-FU) resulted in synergistic growth inhibition of HCT116 human colorectal tumor xenografts in nude mice. Likewise, rNAPc2 further reduced tumor growth in HCT116 human colorectal tumor xenograft-bearing mice receiving bevacizumab (humanized anti-vascular endothelial growth factor monoclonal antibody). The doses and dosing regimens of rNAPc2 used in these murine models of colorectal cancer were well tolerated by recipient mice without major complications of hemorrhage or any other adverse effects. In conclusion, the synergistic tumor inhibitory activity of rNAPc2 in pre-clinical colorectal cancer models suggests that rNAPc2 may be an effective anti-tumor agent in human colorectal cancer patients to potentiate chemo- or anti-angiogenic therapies.
Safe Interruption of Ongoing Thrombosis by the Protein C Activator Thrombin Analog, W215A/E217A; a Comparison to Enoxaparin in Primates.
Authors: Marzec Ulla M. , Bush Leslie , Tucker Erik , Gruber Andras , Hanson Stephen R. , Di Cera Enrico 
Published: April 2020

Abstract
Antithrombotic agents are effective but pose significant bleeding risk, thus safer new agents are needed. Since the infused double mutant human thrombin (W215A/E217A; WE) binds endothelial thrombomodulin, activates protein C locally in the intraluminal boundary layer, and prevents thrombus formation without hemostasis impairment, we investigated whether WE could also interrupt the growth of existing thrombi. WE was compared to standard interventional doses of the low molecular weight heparin, enoxaparin (Sanofi) in awake baboons. Thrombosis was initiated by interposing a two part device consisting of a 2 cm, 4 mm ID polyethylene terephthalate vascular graft (DVG) followed by a 2 cm silicone rubber expansion chamber, 9 mmID. Upon initiation of blood flow at 100 mL/min, wall shear rate of 265 sec-1 in the 4 mm ID segment (arterial type flow) and 29 sec-1 in the expansion chamber (venous type flow), platelet thrombus was monitored by gamma camera imaging of autologous 111In-labelled platelets for 60 min or 90 min. Fibrin accumulation was quantified by homologous 125I-labelled fibrinogen. Hemostasis was assessed as template bleeding time prolongation. APTT was also monitored. Treatments started 25 min after the initiation of thrombosis by enoxaparin, 0.5 mg/kg (LD) and 1 mg/kg (HD) IV bolus or WE, 7.5 μg/kg/hr (LD) and 15 μg/kg/hr (HD) infusion (1/3 dose given as a bolus followed by IV infusion over 60min) and compared to saline infused controls. All interventions were given systemically, downstream from the device and 5–6 studies comprised each study group. Treatment with enoxaparin at 25 min after initiation of thrombus growth resulted in a reduction of platelet deposition of 19 % with the LD and 76 % with the HD after 35 min of therapy in the expanded venous type segment. WE reduced venous thrombosis by 45 % and 65 % at the two doses studied and was further reduced to 65 % and 80 % following 65 min of WE infusion as compared to controls. Arterial type thrombosis was reduced by WE by 34 % and 39 % respectively for the two doses studied. HD enoxaparin reduced arterial type thrombosis by 37 %. Fibrin accumulation paralleled the platelet deposition. APTT was prolonged 1.57- and 1.87-fold respectively for the WE doses without any bleeding time prolongation. Enoxaparin prolonged the APTT 1.4- and 1.75-fold, similar to WE but with a 1.13- and 1.75-fold prolongation of the bleeding time. In conclusion, the double mutant human thrombin, WE, effectively interrupted both venous and arterial type growing thrombi at very low doses without detectable compromise to hemostasis. Likewise, enoxaparin at the doses tested had similar efficacy but with a significantly prolonged bleeding time at the 1 mg/kg bolus dose. WE might provide a safer alternative to heparins in the treatment of acute progressive thrombosis.
Pediatric Experience with Fondaparinux in Deep Venous Thrombosis.
Authors: Grabowski Eric F. , Bussel James B. 
Published: April 2020

Abstract
Over the past two years we have employed daily SC fondaparinux as longterm anticoaguation in five pediatric patients who presented with deep venous thrombosis (DVT; 3 cases) or DVT combined with heparin-induced thrombocytopenia (HIT) confirmed by ELISA for HIT antibody ( 2 cases). The Table summarizes characteristics of the patients. In all cases, anti-factor Xa levels were obtained 3–4 hrs after the third dose and were in the range of 0.5 to 1.2 IU/ml, calibrated to fondaparinux. Indications for fondaparinux were outpatient treatment of HIT or suspected HIT (2 cases), a desire for true once-daily outpatient dosing of a SC agent (3 cases), or a desire to minimize volume of agent given SC (2 cases). Dosing for Pt 1 was based upon a calculated enhanced renal excretion of fondaparinux in very young children, assuming drug metabolism to vary as (body mass}0.75 rather than as body mass. Pt 5 had previously required 10,000 IU of a low MW heparin SC bid, in view of her heterozygous ATIII deficiency, and suffered recurrent hematomas at the injection sites. These almost entirely resolved with use of fondaparinux and a consequent 60% reduction in the daily injected volume of anticoagulant. There have been no episodes of recurrent thrombosis and no bleeding complications after a mean pt follow-up of 8.5 months. Thus, fondaparinux can be employed safely and effectively in both young children and adolescents, with and without HIT.
Patient Characteristics Pt Number Age HIT Risk factors Mo on fondaparinux 1 13 mo present anticardiolipin antibody 8 2 14 yrs suspected anticardiolipin antibody 4.5 3 17 yrs absent FV Leiden, May-Thurner Syndrome, elevated Lp(a), BCPs 18 4 17 yrs absent cervicle rib (subclavian vein thrombosis) 10 5 18 yrs absent ATIII deficiency, atretic IVC, elevated Lp(a), BCPs 2
Effects of the Factor Xa Inhibitor Apixaban on Venous Thrombosis and Hemostasis in Rabbits.
Authors: Wong Pancras C. , Watson Carol A. , Crain Earl J. , Luettgen Joseph M. , Ogletree Martin L. , Wexler Ruth R. , Lam Patrick Y.S. , Pinto Donald J. , Knabb Robert M. 
Published: April 2020

Abstract
Apixaban is a small-molecule, potent, reversible and direct inhibitor of human coagulation factor Xa (FXa) (Ki = 0.08 nM) with greater than 30000-fold selectivity over other coagulation proteases. It is orally bioavailable in rats, dogs, chimpanzees and humans, and is currently in clinical development for prevention and treatment of thromboembolic diseases. The objective of this study was to compare antithrombotic and bleeding time effects of apixaban and warfarin in rabbits. We selected rabbits as the animal model because apixaban has similar potency in inhibiting human and rabbit FXa, but is less potent in inhibiting rat and dog FXa (Ki (nM): 0.16, rabbit; 1.3, rat; 1.8, dog). We induced the formation of venous thrombus by placing threads in the vena cava, and bleeding by the incision of cuticles in anesthetized rabbits. Apixaban was infused IV 60 min before the initiation of thrombosis. Warfarin was administered orally for 4 days before the study. Thrombus weight averaged 73±5 mg and bleeding time averaged 183±7 s in the vehicle group (n=6 per group). Apixaban and warfarin inhibited the formation of venous thrombus in a dose-dependent manner. The estimated IC50 for apixaban was 0.16±0.04 μM. At antithrombotic doses studied, apixaban did not alter blood pressure and heart rate, suggesting hemodynamic effects are not likely to be involved in its antithrombotic activity. At the antithrombotic ID80, apixaban and warfarin increased bleeding time by 9±4% and 516±24%, respectively (n=6 per group). At this dose, apixaban increased ex vivo activated partial thromboplastin time and prothrombin time to 1.4±0.1 and 1.7±0.1 times control, respectively, and warfarin increased prothrombin time to 4.5±0.1 times control. Apixaban at antithrombotic doses selectively inhibited ex vivo FXa but not thrombin activity. In summary, these findings demonstrate potent activity of apixaban as a selective FXa inhibitor exhibiting potential strong efficacy in prevention of venous thrombosis at doses that preserve hemostasis and produce less increases in systemic anticoagulation than warfarin.
Induction of the NKG2D Ligands Expression by Histone Deacetylase Inhibitor and Its Impact on the Susceptibility of Leukemic Cells to the Cytolytic Activity of NKG2D-Expressing Cells.
Authors: Kato Naoko , Tanaka Junji , Sugita Junichi , Toubai Tomomi , Miura Yoko , Ibata Makoto , Shono Yusuke , Ota Shuichi , Kondo Takeshi , Asaka Masahiro , Imamura Masahiro 
Published: April 2020

Abstract
Innate immune cells such as natural killer (NK) cells play a crucial rule in antitumor immune responses. NK cells have functionally opposite receptors for activating and inhibiting signals to exert cytotoxicity. NKG2D is a C-type lectin-like activating receptor and is expressed in various immune cells, including NK cells, NKT cells, CD8+α/β+T cells, and γ/δ+T cells. NKG2D recognizes its ligands, MHC class I-related chain A and B (MICA, MICB). NKG2D ligands are not present on normal cells but are induced by various stresses such as viral infection. Moreover NKG2D ligands are expressed in many malignant cells including hematological malignancies. It has been suggested that involvement of NKG2D in NK or CD8+Tcell-mediated cytotoxicity correlates with the expression levels of ligands on target cells. Therefore induction of NKG2D ligands may lead to enhance the sensitivity to NKG2D-mediated cytotoxicity. In this study, we could enhance expression levels of MICA and MICB by treatment with the histone deacetylase inhibitor trichostatin A (TsA) in lymphoid leukemic cell line BALL1 and some primary patients’ lymphoid leukemic cells. Treatment of BALL1 and patients’ leukemic cells with TsA for 12 hr increased MICA and MICB mRNA expression at least by more than 2 fold by Real-time PCR. Treatment of BALL1 with TsA for 12 hr increased MICA and MICB protein expression on the cell surface by more than 2 fold by flow cytometry analysis. These results suggested that expression of MICA and MICB is partly regulated by histone acetylation. Chromatin immunoprecipitation assay revealed that treatment with TsA resulted in increased acetylation of histone H3 and decreased association with the counteracting enzymes of histone acetyltransferases HDAC1 at the MICA and MICB promoter in BALL1 cell and patients’ leukemic cells. To examine the impact of the cytolytic activity of NKG2D-expressing cells on leukemic cells in which expression of NKG2D ligands was induced by TsA treatment, we performed standard 4 hr 51Cr release assays using BALL1 cells and patients’ leukemic cells. Up-regulation of NKG2D ligands by TsA treatment led to enhance the susceptibility of BALL1 and patients’ leukemic cells by 2 or 3 times to the cytolytic activity of NKG2D-expressing cells. Blocking experiment using specific antibodies for MICA and MICB inhibited the NKG2D-expressing cell-mediated cytolytic activity against BALL1 cells. Our results suggest that regulation of NKG2D ligands expression by treatment with chromatin-remodeling drugs may be an effective strategy to enhance the susceptibility of leukemic cells to the cytolytic activity of NKG2D-expressing cells for immunotherapy.
Platelet Factor 4 (PF4) Antigenic Complexes on the Macrophage Surface: Implications for the Pathogenesis of Heparin Induced Thrombocytopenia (HIT).
Authors: Rauova Lubica , Cines Douglas B. , Poncz Mortimer 
Published: April 2020

Abstract
HIT is the most frequent antibody-mediated drug-induced thrombocytopenia and is unique in the associated prevalence of thrombosis. HIT is caused by antibodies to a normal host protein, PF4, complexed to heparin or cellular glycosaminoglycans (GAGs). We have shown that binding of HIT antibodies and a monoclonal HIT-like antibody KKO to platelet surface chondroitin sulfate (CS) follows a bell-shaped curve with respect to PF4 concentration. At external PF4 concentrations below the peak value of &lt;50 μg/mL, heparin dissociates PF4 and thereby decreases surface antigenicity, whereas at PF4 concentrations &gt;50 μg/mL, heparin initially increases antigenicity. Surface GAGs on macrophages differ from those on platelets in several ways, including having a higher affinity for PF4. In addition, the binding of HIT-IgG elicits the elaboration of tissue factor. Therefore, we characterized the binding of HIT IgG antibody to macrophages exposed to different concentrations of PF4. Binding of PF4 to the surface of human/murine macrophages also followed a bell-shaped curve with peak antigenicity at the same PF4 concentration as seen on platelets. However, HIT antigenticity persisted at lower PF4 concentrations. For example at a PF4 concentration of 6 μg/mL, six times as much KKO bound to macrophages as to platelets. PF4-coated monocytes were also more resistant to the abrogation of KKO binding by heparin. At therapeutic concentrations of heparin, HIT antigenicity actually increased on macrophages exposed to optimal concentrations of PF4, while platelet surface antigenicity was nearly eliminated. Enzymatic removal of surface GAGs showed that unlike platelet surfaces, where CS is the major GAG involved in HIT antigenicity, a more complex pattern was seen on macrophages that included heparan sulfates, CS and likely dermatan sulfates. Thus, these studies show that expression of surface HIT antigenic complexes on macrophages develop at much lower concentrations of PF4 than platelets and that these complexes are more resistant to removal by heparin. The enhanced avidity of macrophages for PF4/GAG complexes may also contribute to the persistent risk of thrombosis for at least several days after heparin exposure has been stopped. Whether measurement of antigenic complexes on macrophages would identity patients at higher risk of thrombosis and whether reduction in the risk of thrombosis requires measures directed at the integrity of these complexes in addition to use of direct thrombin inhibitors are under investigation.
Assessment of the Clinical Benefit of Prophylactic Platelet Transfusion in Thrombocytopenia Using Novel Methodology To Measure Thrombus Formation and Thrombin Generation.
Authors: Cauwenberghs Sandra , Feijge Marion A.H. , Heemskerk Johan W.M. , van Pampus Elisabeth , Curvers Joyce 
Published: April 2020

Abstract
Patients developing severe thrombocytopenia during chemotherapy treatment are prophylactically transfused with platelets. Two novel methods were developed for measuring improved hemostasis in thrombocytopenic patients and to identify patients with aberrant responsiveness. In whole blood, platelet adhesion and thrombus formation on collagen was measured under flow. In platelet-rich plasma, platelet-dependent coagulation was assayed by automated measurement of thrombin generation. Thirty-eight thrombocytopenic patients were transfused with platelets stored in plasma or synthetic medium (PASII), and the transfusion effect on hemostatic activity was evaluated. Experimental conditions were established, where the outcome of flow and thrombin generation tests linearly increased with the platelet concentration (R2=0.98, p=0.001 and R2=0.98, p=0.008 respectively), and informed on the activation properties of platelets. In 35 out of 38 patients, transfusion with platelets in plasma or synthetic medium resulted in increased adhesion and thrombus formation under flow, and in increased platelet-dependent coagulation. The increase in platelet count after transfusion predicted 57% (P=0.001) of the improvement in function. Transfusion with platelets in plasma or synthetic medium increased the hemostatic activity with 0.63±0.30% and 0.68±0.48%, as determined with either platelet function test, with subtle differences between the two storage media. In acute graft-versus-host-disease, platelet-dependent coagulation was higher than in other patients, while thrombus formation was normal. In conclusion, altered thrombus formation and/or aberrant coagulation at low platelet counts can be detected with these novel developed and validated techniques.