Julia Davis | City University of New York School of Law (original) (raw)

Papers by Julia Davis

Arteriosclerosis, Thrombosis, and Vascular Biology, May 1, 2017

Tissue factor (TF) is a procoagulant and transmembrane receptor for FVII(a) that is upregulated i... more Tissue factor (TF) is a procoagulant and transmembrane receptor for FVII(a) that is upregulated in pathological conditions. We recently demonstrated that perivascular TF is downregulated around angiogenic vessels near a cutaneous wound. The goal of this study was to identify mechanisms that mediate TF loss. Primary cultures of human pericytes express high levels of TF. TF expression was lost during culture with phorbol-12 myristate 13-acetate (PMA) for 8 hours, and was maintained for 24 hours. This model recapitulates the pattern of downregulation observed in vivo . Using qRT-PCR we assessed changes in TF gene expression in response to PMA. TF mRNA decreased 4- and 6-fold at 8 and 12 hours after treatment (p&amp;lt;0.01), and remained 2-fold lower in treated cells after 24 hours (p&amp;lt;0.05). Inhibiting de novo transcription with actinomycin D showed that degradation of TF mRNA was similar in PMA- and vehicle-treated groups (p=ns). Thus, downregulation of TF mRNA occurs primarily through inhibition of its synthesis. We next identified a physiologic mediator of TF downregulation using specific inhibitors against PMA-responsive signaling proteins. Two different inhibitors against Protein Kinase C (PKC) were used: Go6983, which inhibits isoforms α, β, δ, ε, μ, and ζ, and GFX, which inhibits α, β, ε, and γ. Both inhibitors significantly attenuated PMA-mediated transcriptional downregulation (p&amp;lt;0.001). Based on overlap of inhibited isoforms, this suggests a minimal role for ζ, μ, δ, and γ, while one or more of the α, β, and ε isoforms appear to be critical mediators of TF mRNA synthesis inhibition. Since the timing of TF protein loss is not fully explained by transcriptional inhibition, we investigated the role of protein degradation in TF loss. When protein synthesis was inhibited by cyclohexamide, addition of PMA shortened the half-life of pericyte TF from 11 hours to 5 hours (p&amp;lt;0.001). This indicates that increased protein degradation contributes to PMA-induced loss of TF expression. Both Go6983 and GFX significantly attenuated TF protein degradation also. Taken together, our data show that TF downregulation is mediated by transcriptional inhibition and protein degradation, and PKC α, β, and ε have emerged as potential mediators of both mechanisms.

Proceedings of the American Association for Cancer Research Annual Meeting, May 18, 1987

Blood, Nov 19, 2010

Abstract 1133 Introduction: Platelet surface activity plays an important role in the efficacy of ... more Abstract 1133 Introduction: Platelet surface activity plays an important role in the efficacy of FVIIa as a bypassing agent in hemophilia. An analog of FVIIa with increased tissue factor (TF) independent activity, NN1731, has been produced by introducing three amino acid changes in the protease domain: V158D, E296V, and M298Q. Modeling suggests that Gln in position 298 and Asp in position 158 form a hydrogen bond network with a water molecule that stabilizes the proteolytically active conformation of the molecule. The Val introduced at position 296 avoids electrostatic repulsion between a native Glu residue and the introduced Asp at 158. These changes result in a FVIIa variant that partially mimics the conformation of TF-bound FVIIa. However, in the presence of TF the activity of the wild type FVIIa and NN1731 are indistinguishable. Previous studies suggested that the increased intrinsic activity of NN1731 was not directly reflected in the level of activity on the platelet surface. The goal of the current work was to compare the platelet binding and platelet surface activity of NN1731 and wild type FVIIa. Methods: Mutant FVIIa molecules were prepared as described previously (PNAS 98:13583-8, 2001). We assessed binding to purified human platelets by flow cytometry and activity by measuring FXa generation. Results: FVIIa and NN1731 had identical binding to phospholipid vesicles designed to have lipid composition similar to platelets. However, the two exhibited different binding to platelets. At all concentrations, more NN1731 bound to thrombin or thrombin-plus-convulxin activated platelets. This was primarily because NN1731 bound to a greater number of sites per platelet. It appears that NN1731 and FVIIa bind similarly to a higher affinity site, but NN1731 binds to an additional low-affinity site. Removal of the Gla domain abolished binding. Thus, the protease domain of NN1731 was insufficient to mediate binding to the low affinity site. Two additional FVIIa mutants were tested: the single M298Q (“Q”) variant, and the double E296V and M298Q (“VQ”) variant. These variants bound to platelets identically to FVIIa. Conclusion: While the Gla domain is essential for FVIIa binding to platelets, the three amino acid changes in the protease domain in NN1731 enhance platelet binding as well as proteolytic activity. Since NN1731 and FVIIa bind similarly to phospholipid vesicles, characteristics in addition to lipid composition likely contribute to platelet binding. The platelet surface components that contribute to NN1731 binding remain to be defined. Disclosures: Hoffman: Novo Nordisk: Research Funding. Persson:Novo Nordisk: Employment. Ezban:Novo Nordisk: Employment. Monroe:Novo Nordisk: Research Funding.

Blood, Nov 18, 2011

Abstract 541 Bleeding occurs in from 10 – 16% of warfarin-treated patients. Having a PT-INR in th... more Abstract 541 Bleeding occurs in from 10 – 16% of warfarin-treated patients. Having a PT-INR in the target range is associated with better outcomes. However, even patients with an INR in the target range of 2–3 can suffer bleeding, suggesting that INR does not perfectly reflect the therapeutic effect of warfarin. The goal of our studies was to determine whether the level of specific coagulation factors could predict the risk of bleeding while the INR was in the target range. We modeled warfarin anticoagulation in our previously published in vitro cell based-model by adjusting the levels of vitamin K-dependent factors to those of patients with an INR of 2–3. We then examined the effect of variations in the level of FIX. The cogulation reactions were initiated by monocyte-expressed tissue factor (assayed at 1pM). Variation in FIX had a marked effect on thrombin generation. However, in plasma with the same levels of factors, as expected, variations in FIX had no effect on the PT-INR. Thus, we hypothesized that a subject with a lower FIX level than average may have a lower level of thrombin generation than is indicated by the INR. The INR might, therefore, underestimate the level of anticoagulation in such a subject. If s/he is maintained in the “therapeutic range” as measured by the INR, s/he will actually be over-anticoagulated and prone to hemorrhage. A prospective, single centre clinical study has been carried out to test this hypothesis in warfarinized patients. Between October 2010 and June 2011, 312 consecutive patients admitted to the emergency department of Edouard Herriot Hospital in Lyon, with an INR between 1.8 and 3.2, were included in the study after obtaining informed consent. Twenty six patients were admitted for a bleeding episode, 18 for recurrent thrombosis and 268 for other medical reasons. Patients presenting with bleeding, 17 males and 9 females, were aged 74±14 years old compared to the rest of the patients aged 76±14. Among the 26 bleeders, 7 had a spontaneous intracranial haemorrhage, 2 had a trauma-induced intracranial haemorrhage, 12 presented a gastrointestinal bleeding and 5 exhibited muscle hematomas, severe epistaxis or urinary tract bleeding. PT-INR and vitamin K-dependent factor levels were determined in all patients. Thrombin generation capacity in platelet poor plasma was measured using Calibrated Automated Thrombin generation assay (Thrombinoscope bv, Maastricht, The Netherlands), with tissue factor 1pM and phospholipids PC:PS:PE 4μM. No statistically significant difference was observed in the PT-INR of bleeding patients (INR=2.4±0.4) and those having a thrombosis (INR=2.5±0.5) or patients admitted for other reasons (INR=2.6±0.2). Plasma prothrombin and factor × levels were also similar in all three groups. However, a statistically lower plasma factor IX activity was observed in bleeders (p=0.01, Mann Whitney test) compared to other groups, 47.6±20 IU/dL vs. 63±33 IU/dL. In all the warfarinized subjects with an INR between 1.8 and 3.2, no correlation was found between thrombin generation capacity and PT-INR results (p=0.85, Spearman correlation test). However, a statistically significant correlation was observed between thrombin generation capacity and factor IX levels (p=0.0002). In patients, presenting with warfarin-related haemorrhage, the endogenous thrombin potential (ETP) was significantly lower at 340±335 nM.min (p=0.05) then that of warfarinized subjects who did not suffer bleeding (ETP 406±215 nM.min). These data support our hypothesis based on our in vitro results and show that patients who bleed when their PT-INR is in the target range 2 – 3 might have defective thrombin generation related to a lower level of factor IX than expected. Thus, our results suggest that the appropriate target INR level might not be the same for all patients. Those with factor IX levels that differ significantly from the mean of the population might be managed best by selecting a target INR that is based on the level of thrombin generation. Of course, a “target range” for parameters of thrombin generation during warfarin therapy would need to be developed if the assay were to be used for this purpose. Disclosures: No relevant conflicts of interest to declare.

Journal of Leukocyte Biology, Feb 1, 1996

coagulation and fibrinolytic pathways predispose to alveolar fibrin deposition in the adult respi... more coagulation and fibrinolytic pathways predispose to alveolar fibrin deposition in the adult respiratory distress syndrome. J. Clin. Invest. 84, 695-705. 49. Bertozzi, P., Astedt, B., Zenzius, L., Lynch, K., LeMaire, F., Zapol, W., Chapman, HA. (1990) Depressed bronchoalveolar urokinase activity in patients with adult respiratory distress syndrome. N. EngI. J. lied. 322, 890-897. 50. Izaki, S., Isozaki, Y., Satoh, M., Hibino, T., Kon, S., Izaki, M. (1983) Comparative study with two polar types of mw-inc leprosy: an involvement of plasminogen activator and its possible regulating factor in the granulomatous tissue reaction. J. invest. Dermatol. 80, 81-85. 51. Sitrin, R.G., Bruhaker, P., Fantone, J.C. (1986) Tissue fibrin deposition during acute lung injury in rabbits and its relationship to local expression of procoagulant and fIbrinolytic activities. Am. Rev. Respir. Dis. 135,930-936. 52. Colucci, M., Paramo, J., Collen, D. (1985) Generation in plasma of a fast-acting inhihitorofplasminogen activator in response to endotoxin stimulation. J. Clin. Invest. 75, 818-824.

Research and practice in thrombosis and haemostasis, 2023

Springer eBooks, Oct 13, 2020

Biochimica et biophysica acta. Molecular cell research, Oct 1, 1991

The serine proteinase inhibitor heparin eofactor II (HC) can be cleaved by polymorphenuelear leuk... more The serine proteinase inhibitor heparin eofactor II (HC) can be cleaved by polymorphenuelear leukocyte (PMN) elastase (LE) to yield potent chemotactie activity for PMN and monocytes. In contrast to the bacterially4erived chemotaxin formyl-Met-Leu-Phe (IMLP), the HC-derived chemotaxin does not stimulate PMN degranulation or oxidative burst activity. We compared the effects of HC-derived chemotosins to the effects of IMLP en PMN actin confor~.,,atien and on the cAMP levels. Beth the HC chemotaxins and tMLP rapidly induced an increase in F-actin which was similar in magnitude and time.course. However, in contrast to iA~L1P) tiC.derived ehemota~ns did not elevate cAMP levels, l-IC-derived chemotaxins may be useful probes of chemotaefic responses, since they do not have ~de mixed biological activities of tMLP.

Transfusion, Apr 22, 2016

BACKGROUND: Recent animal studies suggest that transfusion of plasma from young donors reverses a... more BACKGROUND: Recent animal studies suggest that transfusion of plasma from young donors reverses agerelated neurologic and cardiac changes in older recipients. Associations between age of blood product donors and corresponding outcomes in recipients have not been studied in humans. Therefore, our primary objective was to examine this relationship between donor age and recipient outcomes among patients that received plasma during and after coronary artery bypass grafting (CABG) surgery. STUDY DESIGN AND METHODS: This retrospective cohort included patients undergoing CABG surgery who received plasma during or after surgery. All plasma units transfused were evenly divided into tertiles based on the plasma donor age (17-37, 38-50, and 51-86 years), and CABG patients receiving all perioperative plasma within a single donor tertile were studied. Patient demographics and outcomes including mortality, length of stay (LOS), and acute kidney injury (AKI) were measured. RESULTS: Overall, 1306 patients (24% of 5339) received American Red Cross plasma perioperatively, with a median dose of 2 units. In a multivariate model of 1-year mortality, transfusion of a greater number of plasma units (p 5 0.0007) and EuroSCORE (p < 0.0001) were significantly associated with patient mortality while donor age was not. There was no difference in mortality between patients receiving plasma from donors in the youngest, middle, or oldest age tertile (10.2 and 8.1% vs. 7.8%, respectively, p 5 0.76). Other outcomes, including rates of AKI or LOS, were also independent of plasma donor age. CONCLUSIONS: We did not observe an association between donor age and recipient outcomes among patients who received plasma perioperatively while undergoing CABG surgery.

Transfusion, Jul 1, 1987

Single-donor cryoprecipitate is the most convenient and reliable source of fibrinogen. A change b... more Single-donor cryoprecipitate is the most convenient and reliable source of fibrinogen. A change by the regional Red Cross Blood Service to the production of low-volume cryoprecipitate led theauthors to reexamine the fibrinogen content of cryoprecipitate units. The average fibrinogen content of individual low-volume (4 ml) units (n = 23) was 101 * 48 mg; in the 10-unit pools (n = 9 pools), content was 89 f 13 mg. Both measurements were considerably lower than previously published. By contrast, the mean fibrinogen content of regular-volume (15 ml) cryoprecipitate units (n = 8) was 142 f 50 mg. The fibrinogen was stable for at least 4 hours after thawing, and it survived refreezing and thawing.

Journal of Thrombosis and Haemostasis, Nov 1, 2010

Haemophilia, Jul 23, 2013

Previous work has shown that normalized haemostasis only at the time of an injury is not sufficie... more Previous work has shown that normalized haemostasis only at the time of an injury is not sufficient to promote optimal wound healing in haemophilia B (HB) mice. However, the duration of treatment required for optimal healing has not been established. The goal of these studies was to determine the effect of different durations of replacement or bypassing therapy [factor IX(FIX) or factor VIIa (FVIIa)] on wound healing parameters in a mouse model of HB. A dermal wound was placed on the back of HB mice. Animals were either untreated or pretreated and then subsequently treated for 3 days, 5 days, or 7 days with FIX or FVIIa. Wound area, time to wound healing, haematoma formation and iron deposition were measured. All treated animals showed shortened time to healing relative to untreated animals. Haematoma formation was prevented by treatment and bleeding into the wounds, measured by iron scores, was reduced by treatment. In addition, there was a progressive improvement in healing with 7 days of treatment more effective than 5 days which was more effective than 3 days. Replacement therapy with FIX had slightly shorter healing times than bypassing therapy with FVIIa. HB mice treated with FIX had slightly smaller wound area than untreated animals; by contrast, FVIIa-treated animals had much smaller wound areas that were close to the wound areas seen in wild-type animals. The data suggest that sustained therapy is required for normal wound healing.

Molecular Therapy - Nucleic Acids

Nature Communications, 2021

Despite their limitations, unfractionated heparin (UFH) and bivalirudin remain standard-of-care p... more Despite their limitations, unfractionated heparin (UFH) and bivalirudin remain standard-of-care parenteral anticoagulants for percutaneous coronary intervention (PCI). We discovered novel direct thrombin inhibitors (DTIs) from tick salivary transcriptomes and optimised their pharmacologic activity. The most potent, ultravariegin, inhibits thrombin with a Ki of 4.0 pM, 445-fold better than bivalirudin. Unexpectedly, despite their greater antithrombotic effect, variegin/ultravariegin demonstrated less bleeding, achieving a 3-to-7-fold wider therapeutic index in rodent thrombosis and bleeding models. When used in combination with aspirin and ticagrelor in a porcine model, variegin/ultravariegin reduced stent thrombosis compared with antiplatelet therapy alone but achieved a 5-to-7-fold lower bleeding time than UFH/bivalirudin. Moreover, two antibodies screened from a naïve human antibody library effectively reversed the anticoagulant activity of ultravariegin, demonstrating proof-of-pr...

Blood, 2021

Introduction Hemophilia A (HA) is an inherited bleeding disorder caused by the deficiency of coag... more Introduction Hemophilia A (HA) is an inherited bleeding disorder caused by the deficiency of coagulation factor VIII (FVIII) resulting in severe hemorrhage if untreated. Recombinant and plasma derived FVIII products have long been the standard of care in hemophilia. However, approximately 25-30% of patients with severe HA develop inhibitors, neutralizing alloantibodies to FVIII, a significant complication in the treatment of patients with HA that leads to bleeding despite factor therapy. First approved for bleed prophylaxis in HA with inhibitors in the US by the FDA in 2018, emicizumab (Genentech, USA) has initiated a new era of HA treatment. This drug is a bispecific, monoclonal antibody that binds to activated Factor IX (FIXa) and Factor X (FX), mimicking activated FVIII (FVIIIa) by bringing FIXa and FX into proximity to enable FX activation, even in the presence of inhibitors. Emicizumab prophylaxis drastically reduces bleed episodes. However, thromboses and thrombotic microangio...

Journal of Biological Chemistry, 1991

Heparin cofactor I1 (HC) is a plasma serine proteinase inhibitor (serpin) that inhibits the coagu... more Heparin cofactor I1 (HC) is a plasma serine proteinase inhibitor (serpin) that inhibits the coagulant proteinase a-thrombin. We have recently demonstrated that proteolysis of HC by catalytic amounts of polymorphonuclear leukocyte proteinases (elastase or cathepsin G) generates leukocyte chemotaxins (Hoffman,

Blood, 2005

Elevated plasma homocysteine (HCys) is associated with atherosclerosis and thrombosis. We have pr... more Elevated plasma homocysteine (HCys) is associated with atherosclerosis and thrombosis. We have previously found that clots from plasma, whole blood and purified fibrinogen from homocysteinemic rabbits are composed of thin, tightly-packed fibers and are resistant to fibrinolysis. HCys thiolactone is a metabolite of Hcys that can react with lysine residues under physiologic conditions. This reaction introduces a new free sulfhydryl group into the protein. The current study was designed to test the hypothesis that HCys thiolactone modifies key lysines in fibrinogen, thereby causing the alterations in fibrin structure and susceptibility to fibrinolysis that characterize the homocysteine-induced dysfibrinogenemia. We examined the effect of incubation of HCys thiolactone with purified human fibrinogen. The control and homocysteine thiolactone treated fibrinogen (HCys-fibrinogen) samples were added to fibrinogen-deficient plasma, which was then clotted by addition of thrombin and calcium i...