Tissue factor (TF) is a transmembrane glycoprotein that complexes with factor VIIa to initiate blood coagulation. We previously reported that expression of high levels of TF in a human melanoma cell line promotes metastasis. Both the cytoplasmic domain of TF and its extracellular domain complexed with factor VIIa are required for the metastatic effect. To further explore the mechanism of TF-mediated metastasis, we investigated the possibility that a protease-activated receptor (PAR) might play a role. For this purpose, we first determined the expression levels of the known PARs (PAR1-4) in a human melanoma cell line, SIT1, that has low endogenous levels of TF and low metastatic potential. We found negligible levels of all of the known PARs and transfection of this cell line with human TF cDNA did not alter expression of the known PARs. To study the possible role of PAR1 in TF-mediated metastasis, we prepared a panel of transfected cell lines with varying levels of TF and PAR1. Our studies show that TF promotes metastasis by a pathway that does not involve high expression of known PARs by tumor cells. In addition, while overexpression of PAR1 is insufficient to induce metastasis in cells with low TF expression, it enhances the metastatic potential of cells with high TF expression, indicating a possible synergy between TF and PAR1 in promoting metastasis.
The relationship between tension and myosin 20,000-Da light chain phosphorylation in intact nonmuscle cells was investigated using a preparation of thrombin-activated, irreversibly aggregated platelets known as the platelet strip. Steady-state levels of tension generated by the platelet strip were found to be linearly related to the level of myosin phosphorylation. This relationship was observed during dose-dependent relaxation induced by the adenylate cyclase activators prostaglandin (PG) E1 and PGI2, and during contraction induced by ADP, epinephrine, and the prostaglandin endoperoxide analogue U-46619, which did not appreciably alter the basal level of adenosine 3',5'-cyclic monophosphate in the preparation. The fully relaxed platelet strip, in the absence of external Ca2+, was associated with a level of 12% light chain phosphorylation, which increased to 72% on maximal contraction. During both relaxation and contraction, changes in myosin phosphorylation were also found to precede or coincide with tension changes. Furthermore, steady-state contraction induced by ADP was associated with a maintained elevation in the level of myosin phosphorylation. These results support the concept that myosin phosphorylation is an important regulatory mechanism for contractility in platelets.
Introduction: Iron deficiency anemia (IDA) is common in the hospital setting and is frequently caused by gastrointestinal bleeding (GIB).While treatment is aimed at the underlying cause of IDA, it is also targeted at replenishing iron stores to reduce anemia progression and decrease the risk of end organ damage. Objective:The primary aim of this study was to assess whether patients hospitalized with IDA secondary to GIB received iron supplementation upon discharge.Methods: Retrospective analysis evaluating 992 patients admitted to our tertiary care hospital from 1/1/17 -12/1/17 who underwent endoscopy for GIB.IDA was defined as ferritin ≤ 30, iron saturation ≤ 10% or a ≥ 2gram drop from the patient's baseline hemoglobin.A secondary endpoint assessed readmission rates within a 180-day follow up period after discharge and associated morbidity and mortality.Results: A total of 228 patients met inclusion criteria for analysis.There were 115 males (50.4%) with an overall mean age of 62.6± 2.1y.Overall, 106 (46.5%) patients eligible by our criteria to receive iron therapy were discharged on this therapy.In regression analysis, receiving iron (OR = 13.6;95% CI, 7.0-26.6)or a blood transfusion (2.72; 1.1-6.9)during hospitalization were independently associated with discharge on iron.Discharge on iron was not associated with readmission but there was a non-significant trend toward anemia improvement for those supplemented with iron.Conclusions: At our institution, physicians failed to provide iron supplementation on discharge to over 50% of eligible patients.Patients diagnosed with IDA secondary to GIB are more likely to be discharged with iron supplementation if it was started during hospitalization or they received a blood transfusion.We believe the medication reconciliation performed automatically by the electronic medical record (EMR) at the time of discharge had a significant impact on this finding.
Immune thrombocytopenic purpura (ITP) in adults is usually a chronic disease in which a low platelet count often causes mucocutaneous bleeding. ITP is a diagnosis of exclusion. Pseudothrombocytopenia and such disorders as drug-induced thrombocytopenia, microangiopathic thrombocytopenia, bone marrow failure, and congenital thrombocytopenia must be ruled out. The disorder can be primary (idiopathic) or secondary. Secondary ITP is associated with systemic lupus erythematosus, chronic lymphocytic leukemia, lymphoma, HIV infection or full-blown AIDS, hepatitis C infection, and a variety of other disorders.Multiple mechanisms cause the thrombocytopenia in ITP, so the disorder is likely to be heterogeneous.1 Over 50 years ago, Harrington . . .
We consider deterministic random walks on the real line driven by irrational rotations, or equivalently, skew product extensions of a rotation by $\alpha$ where the skewing cocycle is a piecewise constant mean zero function with a jump by one at a point $\beta$. When $\alpha$ is badly approximable and $\beta$ is badly approximable with respect to $\alpha$, we prove a Temporal Central Limit theorem (in the terminology recently introduced by D.Dolgopyat and O.Sarig), namely we show that for any fixed initial point, the occupancy random variables, suitably rescaled, converge to a Gaussian random variable. This result generalizes and extends a theorem by J. Beck for the special case when $\alpha$ is quadratic irrational, $\beta$ is rational and the initial point is the origin, recently reproved and then generalized to cover any initial point using geometric renormalization arguments by Avila-Dolgopyat-Duryev-Sarig (Israel J., 2015) and Dolgopyat-Sarig (J. Stat. Physics, 2016). We also use renormalization, but in order to treat irrational values of $\beta$, instead of geometric arguments, we use the renormalization associated to the continued fraction algorithm and dynamical Ostrowski expansions. This yields a suitable symbolic coding framework which allows us to reduce the main result to a CLT for non homogeneous Markov chains.
Abstract : Tissue factor (TF) is a 47 kDa transmembrane glycoprotein that complexes with activated factor VII (FVIIa) to initiate blood coagulation. Breast cancer tumors and cell lines that have high expression of TF appear to be aggressive and have high metastatic potentia. Formation of the TF-FVIIa complex induces signaling that leads to activation of p44/42 mitogen-activated protein kinase and protein kinase B (Akt) pathways and inhibition of apoptosis in breast cancer cells. The Akt-mammalian target of rapamycin (mTOR) pathway regulates cell growth and survival and plays a major role in the pathogenesis of breast cancer. Inhibition of mTOR has been shown to increase TF expression in some cell types which might increase tumor TF expression leading to enhanced TF-mediated signaling as well as an increased hypercoagulable state. Inhibition of mTOR, downstream of Akt, is a recent, emerging strategy in the treatment of breast cancer. In this proposal we test the hypothesis that the TF-VIIa signaling pathway interacts with the mTOR pathway to play a critical role in promoting dysregulated proliferation of breast cancer cells. In the present study, we show that formation of TF-FVIIa-FXa complex induces phosphorylation of mammalian target of rapamycin (mTOR) and p70 S6 kinase in a human breast cancer cell line, Adr-MCF-7. Activation of the mTOR pathway, which is probably mediated by PAR1 and/or PAR2, was associated with enhanced cell migration, a key step in the metastatic cascade. Inhibition of this pathway with the specific mTOR inhibitor, rapamycin, markedly decreased cell migration induced by formation of TF-FVIIa-FXa complex and modestly increased tumor cell TF expression. Targeting the TF-mediated cell signaling pathway along with mTOR inhibition might represent a novel strategy for the treatment of breast cancer.
Infection with the novel severe acute respiratory syndrome coronavirus 2 has been associated with a hypercoagulable state. Emerging data from China and Europe have consistently shown an increased incidence of venous thromboembolism (VTE). We aimed to identify the VTE incidence and early predictors of VTE at our high-volume tertiary care center.We performed a retrospective cohort study of 147 patients who had been admitted to Temple University Hospital with coronavirus disease 2019 (COVID-19) from April 1, 2020 to April 27, 2020. We first identified the VTE (pulmonary embolism [PE] and deep vein thrombosis [DVT]) incidence in our cohort. The VTE and no-VTE groups were compared by univariable analysis for demographics, comorbidities, laboratory data, and treatment outcomes. Subsequently, multivariable logistic regression analysis was performed to identify the early predictors of VTE.The 147 patients (20.9% of all admissions) admitted to a designated COVID-19 unit at Temple University Hospital with a high clinical suspicion of acute VTE had undergone testing for VTE using computed tomography pulmonary angiography and/or extremity venous duplex ultrasonography. The overall incidence of VTE was 17% (25 of 147). Of the 25 patients, 16 had had acute PE, 14 had had acute DVT, and 5 had had both PE and DVT. The need for invasive mechanical ventilation (adjusted odds ratio, 3.19; 95% confidence interval, 1.07-9.55) and the admission D-dimer level ≥1500 ng/mL (adjusted odds ratio, 3.55; 95% confidence interval, 1.29-9.78) were independent markers associated with VTE. The all-cause mortality in the VTE group was greater than that in the non-VTE group (48% vs 22%; P = .007).Our study represents one of the earliest reported from the United States on the incidence rate of VTE in patients with COVID-19. Patients with a high clinical suspicion and the identified risk factors (invasive mechanical ventilation, admission D-dimer level ≥1500 ng/mL) should be considered for early VTE testing. We did not screen all patients admitted for VTE; therefore, the true incidence of VTE could have been underestimated. Our findings require confirmation in future prospective studies.
