bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue Factor Is Internalized by Platelets Through Activation of RhoA and PI3-Kinase Promoting Reversible Cytoskeletal Assembly,
Authors: Escolar Gines , Lopez-Vilchez Irene , Galan Ana M , Roque Merce , White James G , Diaz-Ricart Maribel 
Published: October 2019

Abstract
Abstract 3264
TF associated with platelets may play a critical role in the development of ischemic complications at sites of vascular damage. Platelets can internalize and store tissue factor-rich microvesicles from human origin (hTF), a process that can be potentiated by serotonin (5-HT) (Galan et al, Thromb Haemost. 102:511, 2009). There is limited knowledge on the mechanisms involved in the uptake, redistribution and functional expression of TF by platelets. We have investigated the mechanisms implied in the uptake and traffic of hTF with especial attention to CD36 and the 5HT transporter receptor (SERT), but also to the involvement of PI3-kinase, small GTPases (RhoA) and modifications of cytoskeletal organization during vesicular trafficking. Isolated platelets were exposed to hTF for up to 10 min. Cytoskeletal assembly and activation of RhoA were analyzed by electrophoresis and ELISA, respectively. Aggregometry and ultrastructural microscopy were used to assess platelet activation and hTF uptake. Protein arrays were used to evaluate changes in signaling molecules induced by hTF. In addition, inhibitory strategies to block GPIIbIIIa (Reopro), the scavenger receptor GPIV (anti-CD36), the SERT (S-Citalopram, SCit), and PI3-kinase (Wortmannin, Wo) were applied to platelets prior exposure to hTF. Internalization of hTF resulted in reversible actin polymerization and association of contractile proteins (alpha-actinin, actin binding protein and myosin) to the cytoskeleton, being maximal at 1 min. Maximal activation of RhoA occurred at 1 min, decreasing gradually afterwards, while activation of PI3-kinase occurred later (at 5 min). Screening of signaling proteins revealed activation of Akt, ERK1/2, and SNAP-25, among others. All inhibitory strategies fully prevented platelet aggregation to hTF. Uptake of hTF was slightly prevented by Reopro, while both anti-CD36 and Wo partially inhibited hTF uptake and, interestingly, SCit was the most efficient. We conclude that uptake of hTF by platelets promotes activation of specific signaling molecules with reversible cytoskeletal assembly and membrane fusion. While it may be difficult to design specific strategies to prevent the activation of small GTPases, cytoskeletal arrangements or membrane fusion specifically for platelets, our results indicate that the CD36 scavenger receptor and the 5-HT transporter (SERT) may become realistic therapeutic targets to prevent or reduce the association of TF to platelets and hence its possible prothrombotic action.
Grants: SAF2009-10365, Red HERACLES RD06/0009/1003

Disclosures:
No relevant conflicts of interest to declare.
Activated Protein C Inhibits High Mobility Group Box 1 Signaling in Endothelial Cells,
Authors: Bae Jong-Sup , Rezaie Alireza R. 
Published: October 2019

Abstract
Abstract 3274
A pathogenic role for high mobility group box 1 (HMGB1) protein has been postulated in severe sepsis. Activated protein C (APC) is the only FDA-approved drug for severe sepsis, however, its effect on HMGB1 signaling has never been investigated. Here, we monitored the effect of APC on the LPS-mediated release of HMGB1 and the HMGB1-mediated modulation of pro-inflammatory signaling responses in human umbilical vein endothelial cells. APC potently inhibited the LPS-mediated release of HMGB1 and down-regulated the cell surface expression of VCAM-1, ICAM-1 and E-selectin as well as the adhesion of the monocytic cell line, THP-1, to HMGB1-activated endothelial cells. HMGB1 up-regulated pro-inflammatory responses by interacting with three pathogen-related pattern recognition receptors: toll-like receptors 2, 4 and the receptor for advanced glycation end products. APC not only inhibited the LPS-mediated HMGB1 release, but also down-regulated the cell surface expression of all three HMGB1 receptors on endothelial cells. The protective effects of APC were mediated through both EPCR and PAR-1, as evidenced by the function-blocking antibodies to either receptor abrogating the signaling function of APC. Interestingly, a thrombin derivative containing the Gla-domain of APC recapitulated all protective effects of APC with a 20–50-fold higher efficacy. These results suggest that the EPCR- and PAR-1-dependent protective effects of APC in severe sepsis may partially be mediated through the inhibition of HMGB1 signaling and that the chimeric thrombin mutant has potential therapeutic utility for severe sepsis.

Disclosures:
No relevant conflicts of interest to declare.
Predictors of Acquired Von Willebrand Syndrome in Patients with Aortic Stenosis,
Authors: Chen Dong , Thomas Colleen S , Blackshear Joseph L 
Published: October 2019

Abstract
Abstract 3318

Background:
Acquired von Willebrand syndrome (AVWS) due to loss of high molecular weight multimers (HMWM), is a frequent cause of bleeding in aortic stenosis (AS), and is reversed by valve replacement. The goal of this study was to explore predictors of AVWS in patients with AS.

Methods:
A total of 91 patients (59 men, median age 79 years) with AS (n=64) or heart valve replacement (n=27) were included. We recorded peripheral blood count, vital signs, mean gradient (MG), peak velocity (peak vel), aortic valve time velocity integral (AV-TVI), aortic valve area (AVA) and valve area index (AVAi), time velocity integral ratio (TVI ratio), VWF antigen (VWF:Ag), VWF activity by latex immunoturbidity assay (VWF:Lx), VWF multimer analysis, closure times of platelet function analyzer ADP and epinephrine cartridges (PFA-CADP and –CEPI). HMWM losses were graded as normal, mild or severe when compared to HMWM analyses of pooled plasma samples from normal donors. Potential predictors of HMWM loss were explored using logistic regression analysis.

Results:
Of the 91 patients, 42 (46%) had loss of HMWM (23 mild and 19 severe). In single variable logistic regression analysis, AVWS was associated with a low AVA (<1.0 cm2; OR=5.08, P<0.001), and low AVAi (<0.60 cm2/m2; OR=5.54, P<0.001), low TVI ratio (<0.25; OR=10.80, P<0.001), prolonged PFA-CADP (≥121 sec; OR=6.76, P<0.001), and low VWF:Lx/Ag (≤0.8; OR=8.06, P=0.008). Moderate peak vel (3–4 m/sec) and high peak vel (>4 m/sec) were associated with loss of HMWM (OR[vs. <3 m/sec]=5.80 and 37.70 respectively, P<0.001) as were moderate MG (25–40 mmHg) and high MG (>40 mmHg), (OR [vs. <25mmHg]=4.50 and 32.50 respectively, P<0.001). In exploratory multivariable analysis, mean gradient remained one of the strongest predictor of loss of HMWM. The estimated sensitivity of MG (≥25mmHg) in diagnosing AVWS was 83% (35/42, 95% CI: 69%-93%) and estimated specificity was 71% (35/49, 95% CI: 57%-83%). Considering the very strong correlation with mean gradient, we also considered the diagnostic utility of peak vel. Peak vel≥ 3 m/sec had a sensitivity of 89% (38/42, 95% CI: 77%-97%) and a specificity of 59% (29/49, 95% CI: 44%-73%) in detecting loss of HMWM.

Conclusion:
Our data suggest that mean gradient (>25 mmHg) and peak vel (≥ 3 m/sec), both derived from the Doppler aortic valve velocity envelope, are accurate predictors for AS-AVWS, and should be incorporated into algorithmic approaches to laboratory screening for AVWS.

Disclosures:
No relevant conflicts of interest to declare.
Rofecoxib Does Not Appear to Increase the Risk of Venous Thromboembolism: A Systematic Review of the Literature,
Authors: Goy Jennifer K , Paikin Jeremy , Crowther Mark A. 
Published: October 2019

Abstract
Abstract 3334
Rofecoxib, a selective cyclo-oxygenase-2 (COX-2) inhibitor, has been associated with increased arterial thrombosis. It is unknown whether it is associated with venous thromboembolism (VTE). We investigated, using a systematic review of the literature, the association between rofecoxib and venous thrombosis. A search strategy was developed with the assistance of a research librarian and was implemented in 2 electronic databases. We identified all English language studies in which rofecoxib was compared with placebo, irrespective of the primary outcome of the study. Only placebo controlled trials were included in the review as NSAIDs (the comparator in many rofecoxib studies) may have anti-thrombotic effects. We also limited studies to those with 3 or months of follow-up since we presume that the effects of rofecoxib on the coagulation system would take time to develop. Two reviewers assessed study eligibility, with disagreements resolved by consensus. Data was extracted from each of study in a standardized manner using RefMan software. Quality of the studies was assessed according to pre-established criteria: (1) randomization process (2) blinding, and (3) documentation of losses to follow up. Pooled incidence rates were calculated from the reported number of VTEs and total person years at risk. Confidence intervals and risk difference were calculated using a Poisson distribution. The search strategy identified 1339 papers. After review, a total of 15 studies in 14 populations met inclusion criteria. The majority of trials were short in duration (∼12 weeks). All studies met at least two of the three quality criteria. In 15160 (9217 person years follow up) patients allocated to rofecoxib there were 8 VTEs reported, compared with 9 VTEs in 13147 (9092 person years) patients allocated to placebo (relative risk 0.87, 95% CI 0.29–2.56, p = NS). The estimated incidence of VTE was 86.8 per 100,000 (95% CI 37.5 –171.2) person years with rofecoxib, and 99.1 per 100,000 person years with placebo (95%CI 45.3 – 188). This difference is statistically insignificant (p=0.78). Our findings are limited by the relatively small number of events, although the contributing sample size 28307 subjects (18309 person years) is reasonable. We are also unsure that all venous events were captured, although the fact that many of the contributing studies were performed in support of regulatory filings of rofecoxib suggests that events were unlikely to be missed. All included trials had processes for adjudication of VTE. Keeping these limitations in mind, our findings do suggest that there is no increase in the risk of VTE with rofecoxib use.

Disclosures:
Crowther: Various: Consultancy.
Cerebral Artery Velocity in Patients with β-Thalassemia Intermedia Compared to β-Thalassemia Major Using Transcranial Doppler Ultrasonography,
Authors: Karimi Mehran , Haghpanah Sezaneh , Shariat Abdolhamid , Ashjazadeh Nahid , Nazeri Masoume , Emami Sajad , Foroughi Amin Abolhasani , Petramfar Peyman , Yaghoubi Ehsan , Lak Manijeh 
Published: October 2019

Abstract
Abstract 3335

Introduction:
Patients with β-thalassemia, especially β-thalassemia intermedia (β-TI), are prone to hypercoagulable state and subsequently cerebral thromboembolic events. In this study we aimed to determine cerebral artery velocity as a determinant of stroke risk in patients with β-TI compared to β-thalassemia major (β-TM) and healthy subjects. Method: Sixty patients with β-TM and 64 β-TI were randomly selected in this cross sectional study. Sixty healthy adults comprised as a control group. The Time average Maximum Mean Velocity (TAMMV) was measured in large cerebral arteries using Transcranial Doppler (TCD) Ultrasonography. The TAMMVs in different arteries were compared between the patients with β-TI, β-TM and controls. Results: TAMMV in all arteries was significantly higher in β-TI patients than β-TM patients and controls (P< 0.001). Also β-TM patients had significantly higher TAMMVs than controls in all arteries except for the left and right posterior cerebral arteries (P< 0.001). In univariate analysis we found that the lack of transfusion, thrombocytosis, splenectomy, higher platelet counts and lower age could contribute to increase TAMMV (P< 0.05). However, in the multiple linear regression models the only important factors influencing TAMMV were the lack of transfusion in all evaluated arteries following with age only in some investigated arteries. Conclusion: We showed that patients with β-TI has a higher TAMMV in comparison with the healthy subjects as well as with the β-TM patients probably due to the lack of transfusion and chronic anemia. In addition, β-TI patients are more prone to thromboembolic events and subsequently cerebral infarction due to hypercoagulable state. We recommend MRI screening in β-TI patients for detection of silent lesions, in the presence of asymptomatic lesions, TCD would be beneficial. In patients with high cerebral artery velocity and silent lesion further evaluation, close observation and prophylactic treatment including regular blood transfusion and antiplatelet therapy should be considered. However further prospective studies are suggested to confirm the correlation between the stroke risk and high cerebral velocity as well as the protective effect of regular transfusion in β-TI patients.

Disclosures:
No relevant conflicts of interest to declare.
Progestin-Only Contraceptives and the Risk of Venous Thromboembolism: Systematic Review and Meta-Analysis,
Authors: Mantha Simon , Raghavan Vidya , Karp Rebecca , Terrin Norma , Bauer Kenneth A. , Zwicker Jeffrey 
Published: October 2019

Abstract
Abstract 3344

Background:
Combined oral contraceptives (COC) containing estrogens and progestins are associated with a 2 to 4-fold increased risk of venous thromboembolic events. Progestin-only contraceptives are commonly prescribed to women with a higher risk for thrombosis, although a lower thrombotic risk than COC has not been clearly established. We performed a systematic review and meta-analysis of published studies to estimate the risk ratio of venous thromboembolism (VTE) in women taking progesterone for the purpose of contraception.

Materials and methods:
We performed a literature search of cohort, case-control and randomized studies including women treated with progestin-only contraception compared with a no-hormone control group. All administration routes (oral, injectable and intra-uterine) were considered. The primary endpoint was the corrected risk ratio of VTE analyzed using a random effects model.

Results:
1150 references were retrieved; 7 studies were retained for analysis. The summary estimate of the adjusted risk ratio of VTE for women taking a progestin for contraception versus no hormone was 1.02 (95% CI=0.76–1.37, p=0.89). Heterogeneity between studies was minimal (Q-value=7.1, I2=15.49 and p=0.31). An analysis combining the unadjusted odds ratios of VTE gave a similar result (OR=1.24, 95% CI=0.93–1.66, p=0.14). Analysis by subgroup suggests a higher risk of thrombotic events for individuals using an injectable progestin, with an estimated risk ratio of VTE equal to 2.67 (95% CI=1.29–5.53, p=0.008), compared to 0.87 (95% CI=0.53–1.42, p=0.58) for oral administration.

Conclusions:
Progestin-only oral formulations used for contraception do not appear to increase the risk of venous thromboembolic disease, although injectable administration was associated with an increased incidence of VTE relative to women not taking hormones that is comparable to the risk associated with COC.
Estimated risk ratio of VTE for progestin versus no hormone, using adjusted values; A, all routes of administration for all studies; B, injectable progestins only, for studies where those results were reported.
This publication was supported by Grant Number UL1 RR025752 from the National Center for Research Resources. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NCRR.

Disclosures:
No relevant conflicts of interest to declare.
The ETS Protein ELF2 Contributes to a Novel TAL1/SCL-Containing DNA-Binding Complex That Positively Regulates Erythroid Gene Expression and Cell Differentiation,
Authors: Cai Ying , McCormack Matthew P. , Curtis David J. , Nagarajan Lalitha , Brandt Stephen J. 
Published: October 2019

Abstract
Abstract 3389
The TAL1/SCL gene, originally discovered from its involvement by a recurrent chromosomal translocation in T-cell acute lymphoblastic leukemia, is important for hematopoietic stem cell and erythroid, megakaryocyte, and macrophage progenitor function and is essential for hematopoietic and vascular development. Although Tal1 can bind DNA with one of its E protein DNA binding partners, its function in erythroid cells has been thought to be mediated by a larger complex recognizing an E box-GATA or GATA sequence motif. In independent lines of investigation, a novel DNA-binding motif for TAL1 comprised of an ETS site immediately adjacent to an E box was identified by site selection analysis in K562 cells, and multiple peptides derived from a single ETS protein, E74-like factor 2 (Elf2, also known as NERF), were identified by tandem mass spectrometry analysis of Tal1-containing protein complexes purified from murine erythroleukemia (MEL) cells. To determine whether Elf2, previously shown to interact with Tal1's interaction partner LMO2, recognized this sequence element, electrophoretic mobility shift analysis was carried out using MEL cell nuclear extracts. This revealed the existence of a novel multiprotein ETS-E box DNA-binding complex containing Tal1, Elf2, Lmo2, the LIM domain-binding protein Ldb1, and Ldb1-interacting single-stranded DNA binding proteins Ssbp2 and Ssbp3. Structure-function analysis of this DNA-binding activity, which increased with chemical induction of MEL cell differentiation, showed that both the E box and ETS site were required for ternary complex formation, that preference existed for specific ETS flanking sequences, and that precise spacing between the two transcription factor binding sites was critical for complex formation. Finally, a physiological target for this complex was identified in the Ssbp3 gene, with Tal1, Elf2, and Ldb1 found to specifically co-occupy the third intron of this gene by chromatin immunoprecipitation analysis but not a similar ETS-E box element in the 11th intron. In accord, Ssbp3 expression, ETS-E box DNA-binding activity, and hemoglobin concentration increased with enforced expression of Elf2 in MEL cells, while Ssbp3 protein abundance, ETS-E box DNA-binding activity, and cellular differentiation decreased with Elf2 knockdown. These studies identify a novel TAL1- and ELF2-containing DNA-binding complex in erythroid progenitors that positively regulates gene expression and differentiation. In addition, they reveal a previously unknown role for the ETS protein ELF2 in erythropoiesis.

Disclosures:
No relevant conflicts of interest to declare.
The Efficacy of Rabbit Antithymocyte Globulin (Thymoglobulin®) with Cyclosporin As First-Line Treatment in Aplastic Anemia,
Authors: Shin Seung-Hwan , Yahng Seung-Ah , Lee Sung-Eun , Cho Byung-Sik , Eom Ki-Seong , Kim Yoo-Jin , Kim Hee-je , Lee Seok , Min Chang-Ki , Cho Seok-Goo , Kim Dong-Wook , Min Woo-Sung , Park Chong-Won , Lee Jong-Wook 
Published: October 2019

Abstract
Abstract 3430

Background:
Antithymocyte globulin (ATG) is the drug of choice for immunosuppressive therapy (IST) in patients with aplastic anemia (AA) unsuitable for hematopoietic stem cell transplantation. The standard ATG preparation in AA had been horse ATG because of the larger experience and the results already reported with this preparation. Due to the unavailability of the horse ATG since 2006, rabbit ATG became the only available ATG preparation in Korea. But, there are only limited data about the therapeutic efficacy of rabbit ATG as first-line IST in AA.

Method:
We retrospectively investigated the outcome of 58 evaluable patients among 62 patients with AA treated with IST using rabbit ATG as front line between March 2006 and April 2010 at our institution. 70.7% of enrolled patients were very severe (n=18) or severe AA (n=23). All patients received rabbit ATG (Thymoglobulin®, 2.5mg/kg per day for 5 days) with methylprednisolone and cyclosporine A. Response rate (RR) was assessed at 3, 6, 9, 12 and 18 months after IST.

Results:
After IST, overall RR was 27.8%, 50.8%, 52.8%, 52.8% and 56.7% after 3, 6, 9, 12 and 18 months, respectively. Complete response (CR) rates were 0.8%, 1.8%, 5.6%, 9.6% and 21.2% after 3, 6, 9, 12 and 18 months, respectively. Median time to achieve partial response (PR) and CR were 93 (range; 12∼977 days) and 381 (range; 12–614) days. Among 31 responders, 10 patients (32.3%) relapsed. Median time between response and relapse were 396 days (range; 254∼681 days).
Estimated overall survival and failure free survival at 3 years from ATG treatment were 85.8% and 42.8%, respectively. Age (>45) at the use of ATG was an independent predictor of overall survival and overall response (p=0.033 and 0.027) in univariate analysis. Other factors such as disease severity, pre-ATG hematological parameters (absolute lymphocyte count and absolute reticulocyte count) were not associated with overall survival and failure free survival.

Conclusion:
These data indicate that rabbit ATG was as effective as horse ATG based on other recently published data. But, the response time of rabbit ATG treatment is longer than that of horse ATG treatment. Especially, more than half of patients who achieved CR required time over 1 year after ATG treatment. Rabbit ATG can be effective IST regimen comparable to horse ATG, but it takes longer time to achieve sufficient response.

Disclosures:
No relevant conflicts of interest to declare.