bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leukemogenic FLT3 Mutations Confer Enhanced Proliferation and Survival Properties to Multipotent Progenitor Cells in a Murine Model of Chronic Myelomonocytic Leukemia.
Authors: Lee Benjamin H. , Tothova Zuzana , Levine Ross L. , Anderson Kristina , Buza-Vidas Natalija , Cullen Dana E. , McDowell Elizabeth P. , Adelsperger Jennifer , Frohling Stefan , Huntly Brian J.P. , Beran Miloslav , Jacobsen Sten Eirik , Gilliland D. Gary 
Published: April 2020

Abstract
FLT3 internal tandem duplication (ITD) activating mutations are among the most common genetic events in acute myelogenous leukemia (AML) and confer a poor clinical prognosis. Despite their known transforming properties, the effects of constitutive FLT3 signaling on multipotent stem and progenitor cells and hematopoietic differentiation are not well understood. Here we report a novel murine model harboring an ITD mutation in the endogenous murine Flt3 locus. These mice exhibit a myeloproliferative disease (MPD) resembling human chronic myelomonocytic leukemia (CMML) and concomitant with the murine phenotype, we identified FLT3-ITD mutations in a proportion of human CMML. Disease was more pronounced in animals that were bi-allelic for the ITD mutation (Flt3ITD/ITD) and these findings correlated with an increase in number, cell cycling and survival of multipotent stem and progenitor cells in Flt3+/ITD and Flt3ITD/ITD mice in a dose-dependent manner. Moreover, Flt3 mutant animals demonstrated expansion of granulocyte-monocyte (GMP) progenitors as well as reduction in erythroid progenitors and a block in normal B cell development. Together, these findings provide novel insights into the consequences of dysregulated FLT3 tyrosine kinase signaling on primitive hematopoietic progenitor quiescence, function and cell fate and how these effects contribute to the pathogenesis of acute myelogenous leukemia.
Identification of Tyrosine Residues of Importance for Survival Signaling through the Scaffolding Protein Gab2 in Both Wild-Type FLT3 and the FLT3-ITD.
Authors: Masson Kristina , Liu Tao , Sun Jianmin , Ronnstrand Lars 
Published: April 2020

Abstract
The receptor tyrosine kinase FLT3 is normally expressed in hematopoietic progenitor cells and has been implicated as a major cause of transformation in acute myeloid leukemia, where it in approximately 30% of cases is mutated and constitutively active. This is in most cases due to duplication of a DNA sequence coding for amino acids in the juxtamembrane region of FLT3, commonly referred to as ITD (Internal Tandem Duplication). In this study we have identified several novel in vivo tyrosine phosphorylation sites that are phosphorylated in wild-type FLT3 upon ligand stimulation and that are constitutively phosphorylated in the FLT3-ITD. We were able to demonstrate that these phosphorylation sites are critical for full phosphorylation of the scaffolding protein Gab2 both in wild-type FLT3 and FLT3-ITD. Y-to-F mutants of either wild-type FLT3 or FLT3-ITD, lacking these tyrosine residues, fail to phosphorylate Gab2 and demonstrate a considerable reduction in phosphorylation of Akt and Erk. Furthermore, FL-dependent survival and proliferation of wild-type FLT3 expressing Ba/F3 cells as well as FL-independent survival and proliferation of Ba/F3 cells transfected with FLT3-ITD was dramatically reduced by mutation of these tyrosine residues. In the case of the FLT3-ITD, this was shown to correlate with strongly reduced STAT5 phosphorylation. To verify the importance of Gab2 in FLT3-ITD signaling, we used siRNA technology to knock down the expression of Gab2 in the human AML cell line MV4-11 that is known to express FLT3-ITD. Knockdown of Gab2 expression led to a dramatic reduction in the phosphorylation of Akt, Erk and Stat5. To summarize, we have identified novel phosphorylation sites in FLT3 and how they link to downstream signaling of survival and proliferation. These findings not only reveal novel phosphorylation sites in FLT3 but also contribute to the understanding of the molecular mechanism by which FLT3-ITD functions in pathological conditions. Future studies are aiming at elucidating the mechanism by which Gab2 mediates phosphorylation and activation of STAT5, which could be a future potential target for therapy in AML with FLT3-ITD.
Sickle Cell Trait, Oral Contraceptives, and the Risk of Venous Thromboembolism.
Authors: Austin Harland , Lally Cathy , Benson Jane M. , Whitsett Carolyn , Hooper W. Craig , Key Nigel S. 
Published: April 2020

Abstract
We recently reported that sickle-cell trait (SCT) is a risk factor for venous thromboembolism (VTE) among African Americans (1). Since current usage of oral contraceptives (OC’s) is an established risk factor for VTE in women of European descent, we investigated the joint effect of OC’s and SCT on VTE risk in the Genetic Attributes and Thrombosis Epidemiology (GATE) study. This case-control study included 57 African American women with an idiopathic, first deep-vein thrombosis and/or pulmonary embolism and 185 controls between the ages of 18 and 49. Subjects were genotyped at codon 6 (E&gt;V) for the hemoglobin S mutation and were interviewed about OC usage. The distribution of cases and controls according to current OC use and SCT is displayed below: The odds ratio of VTE among OC users versus women not currently using OC’s is 2.7 (95% CI: 1.4, 5.1; P = 0.003). However, among subjects with SCT, the odds ratio for OC use is considerably higher (OR = 7.0; 1.1, 45; P = 0.04) than is the odds ratio for OC use among women without SCT (OR = 2.1; 1.0, 4.3; P = 0.05), although the difference in these two odds ratios is not statistically significant (P &gt; 0.20). Nonetheless, the findings indicate that overall, current OC use is a strong risk factor for VTE among African American women. The observation that there is synergy between current OC use and SCT provides some additional support for the finding that SCT is a risk factor for VTE. However, a limitation of this analysis is small numbers and the resultant imprecision. Replication of these findings is thus required before causation can be established.
Current OC use and Sickle Cell Trait SCT OC Case Control Odds Ratio No No 31 138 1.0 No Yes 15 32 2.1 Yes No 4 12 1.5 Yes Yes 7 3 10.4
JAK2 V617F in Patients with Idiopathic Thromboses in Common Locations.
Authors: Abel Gregory A. , DeAngelo Daniel J. , Connors Jean M. , Sholl Lynette M. , McCaffrey Ronald P. , Longtine Janina A. 
Published: April 2020

Abstract
Background: Polycythemia vera and essential thrombocytosis, two of the myeloproliferative disorders (MPD) often characterized by the recurrent somatic missense mutation JAK2 V617F, are associated with an increased risk of arterial and venous thrombosis. Although recent anecdotal reports have suggested the possibility of latent MPDs by finding JAK2 mutations in patients with abdominal venous thromboses (AVT), the usefulness of routine JAK2 V617F testing has not been assessed in a cohort of general hospital patients with idiopathic thromboses in common locations.
Methods: To assess the utility of JAK2 V617F testing in patients undergoing thrombophilia workup, we identified all patients with negative molecular diagnostic tests for the Factor V Leiden (FVL) mutation and the prothrombin gene mutation (G20210A) over the course of one year at the Brigham and Women’s Hospital. We then determined, by medical record review, the nature of the thrombotic events for which they were being evaluated, and tested their nucleated white blood cell DNA for the JAK2 V617F mutation using the amplification refractory mutation system (ARMS)-PCR assay (which has a lower limit of detection of 5% mutant alleles).
Results: From Februrary 2006 to February 2007, 111 patients had negative tests for both FVL and G20210A. Of these, our chart review revealed that 65 had documented thromboses without a history of malignancy or MPD. None of these were found to have the JAK2 V617F mutation. Laboratory hypercoaguability studies for thrombosis by type (from medical record review) were as follows:
Protein C deficiency (%) Protein S deficiency (%) Anti-thrombin III deficiency (%) Antiphospholipid Abs (%) Elevated homocysteine (%) JAK2 V617 mutation (%) None (%) CVA/Stroke (n=10) 0 20 0 10 0 0 70 DVT/PE (n=45) 11 20 2 4 13 0 60 AVT (n=6) 33 33 0 0 17 0 33 Other Arterial Thrombosis (n=4) 0 25 0 0 25 0 50
In terms of clinical risk factors, 27.6% of patients with documented thromboses had had surgery within the prior month, 26.2% were current smokers, and 31.4% of female patients were either pregnant or taking oral contraceptives. 29.2% of all patients had no clinical or laboratory thrombophilic risk factors.
Conclusions: About two-thirds of our general hospital patients with thrombosis and negative tests for FVL and G20210A had another underlying thrombophilic risk factor. Adding JAK2 V617F mutation testing as a routine component of the thrombophilia diagnostic workup is not recommended, as it is unlikely to reveal evidence of a putative latent MPD.
Regulation of Microparticles and Adhesion Molecules in Pregnancy. Diagnostic and Pathophysiologic Implications.
Authors: Hoppensteadt Debra , Cunanan Josephine , Anderson Anita Sylvester , Bergholt Thomas , Berthelsen Jorgen , Fareed Jawed 
Published: April 2020

Abstract
OBJECTIVE In addition to increased levels of coagulation factors and platelet counts,, microparticles are also found in increased numbers in pregnancy and are generated due to cellular activation and consumption. Microparticles may also be capable of amplifying the procoagulant and inflammatory responses by up regulating the adhesion molecules such as P, E and L selectins. This study will provide newer data on the regulation of microparticles in different trimesters of pregnancy and their relevance to the generation of adhesion molecules and tissue factor (TF).
STUDY DESIGN Blood samples from pregnant women at their first prenatal visit and during the second and third trimester (n=50) were collected and citrated plasma samples were profiled for TF (American Diagnostica, Stamford, CT), E, L and P-selection (R &D Systems, Minneapolis, MN) by using commercially available sandwich ELISA methods and microparticles utilizing a functional method from Hyphen Biomed (Neuville-Sur-Oise, France). The results were compiled for each trimester and compared to aged match non-pregnant controls (n=40).
RESULTS During the first trimester all of the mediators were increased in comparison to the controls. The relative increase was mediator dependent. L-selectin remained elevated, at a steady level, throughout the pregnancy. E-selectin showed a decrease in the second trimester with a rebound increase in the third trimester. A gradual increase in the TF and microparticles was evident throughout the pregnancy. The P-selectin levels decreased during the second trimester and stayed at this level for the remainder of the pregnancy.
CONCLUSION Throughout pregnancy the TF levels directly correlated with an increase in the MP levels indicating that TF cause cellular activation leading to the formation of MPs. However, the levels of the adhesion molecules, which were initially elevated, fluctuate throughout the 2nd and 3rd trimester. These results suggest that increased levels of TF and MPs are progressively generated during pregnancy and may be responsible for the observed thrombotic complications and prothrombotic state in pregnancy.
Risk Factors for Venous Thromboembolism (VTE) among Patients with Active Hematological Cancer: A Population-Based Case-Control Study.
Authors: Ashrani Aneel A. , Heit John A. , Schmoll Jeffrey A. , Farmer Sara A. , Petterson Tanya M. , Melton Lee J. 
Published: April 2020

Abstract
Background: Hematological cancer patients are at an increased risk for VTE (RR range = 12–32). However, whether VTE risk among such patients can be further stratified is uncertain.
Objective: To test hematological cancer type, stage, stage progression and chemotherapy as potential risk factors for VTE among active hematological cancer patients after controlling for other previously-identified VTE risk factors.
Methods: Using the resources of the Rochester Epidemiology Project, Mayo Clinic Master Diagnostic Index and Mayo Clinic Tumor Registry, we identified all Olmsted County, MN residents with active hematological cancer over the 28-year period, 1973–2000. From this prevalence cohort, we identified 86 patients with no prior VTE (controls) who were matched on age and date of hematological cancer diagnosis to 86 hematological cancer patients with incident VTE over the same time frame (cases). For all cases and controls, we reviewed the complete medical records in the community for baseline and hematological cancer-related characteristics. Hematological cancers were re-staged at the dates of the cancer and VTE diagnosis. We tested these characteristics as potential risk factors for VTE in active hematological cancer using conditional logistic regression.
Results: In an initial multivariate analysis that included body mass index (BMI), hospitalization, and any infection or central venous catheter placement within 90 days prior to the VTE event, VTE was significantly associated with hospitalization (OR=6.70; p&lt;0.001), and marginally associated with any infection (OR=2.18; p=0.09). After adjusting for the above variables, chemotherapy administered within the preceding 90 days was significantly associated with VTE (OR=4.25; p=0.02), while stage progression was marginally associated (OR=4.79; p=0.10). Compared to all other hematological cancer types, acute leukemia (OR=5.95; p=0.01) and non-Hodgkin’s lymphoma (OR=2.61; p=0.01) were associated with VTE. However, after adjusting for BMI, hospitalization, any infection and central venous catheter, only non-Hodgkin’s lymphoma was independently associated with VTE (OR=3.79, p=0.009), while acute leukemia was not (OR=2.66, p=0.35).
Conclusions: Hematological cancer type (in particular, non-Hodgkin’s lymphoma and possibly acute leukemia), recent hospitalization, recent chemotherapy, and possibly stage progression and recent infection, are risk factors for VTE among patients with active hematological cancer.
Myeloid Dyspoiesis as Determined by Flow Cytometry Is a More Powerful Predictor of Post-Transplant Relapse with MDS Than the Marrow Myeloblast Count.
Authors: Wells Denise A. , Scott Bart L. , Leisenring Wendy M. , Loken Michael R. , Deeg H. Joachim 
Published: April 2020

Abstract
We showed previously that the presence of aberrant marrow myeloblasts, as determined by flow cytometry immediately pre-transplant had predictive value for post-transplant outcomes in patients undergoing hematopoietic cell transplantation (HCT) for Myelodysplastic Syndrome (MDS). The characteristics of phenotypically abnormal myeloblasts in MDS include decreased expression of CD45, presence of non-lineage lymphoid antigens including CD56, and differences in the intensity of various myeloid antigens in comparison to healthy controls. In the present study, the bone marrow aspirates of 156 patients with MDS were analyzed before HCT for the presence of abnormal myeloblasts with the aim of determining whether myeloid dyspoiesis by flow cytometry was predictive of post-transplant outcomes, specifically in patients who were considered good risk by currently accepted criteria. All patients received ”myeloablative” conditioning, which in most patients (78%) consisted of busulfan (targeted) and cyclophosphamide followed by HLA-identical related (52%), HLA-matched unrelated (39%), or alternative donor (9%) stem cell infusions. In agreement with our initial report, patients with severe flow scores (≥4) had an increased hazard of relapse (HR=2.7, 95% CI_1.1–6.3, p=0.017) in comparison to patients with normal flow scores. In addition, even among patients with less than 5% marrow myeloblasts, dyspoietic characteristics of the blasts, as assessed by flow cytometry criteria were associated with an increased hazard of relapse (HR=4.0, 95% CI 1.4–12.1, p=0.013) as compared to patients without dyspoiesis by flow. The cumulative incidence of relapse in MDS patients with flow cytometrically normal marrow myeloblasts was 11.7%, compared to 28.1% in patients with less than 5% but phenotypically aberrant myeloblasts; the latter was not different from a relapse incidence of 31.4% in patients with 5% or more abnormal marrow myeloblasts. Furthermore, patients with intermediate-1 risk disease by the International Prognostic Scoring System, who showed flow cytometric aberrancies were at significantly increased risk of relapse (HR=4.2, p=0.01) in comparison to patients with intermediate-1 risk disease and no or mild dyspoiesis by flow cytometry. Thus, the presence of dyspoietic changes was more relevant than the proportion of marrow myeloblasts in predicting the risk of relapse, suggesting that flow cytometry is a powerful tool to select high risk patients from cohorts of patients who by established criteria would be considered to have good risk MDS.
High Incidence of Fatty Liver and Insulin Resistance in Long-Term Adult Survivors of Childhood Stem Cell Transplantation Recipients.
Authors: Tomita Yuichiro , Ishiguro Hiroyuki , Hyoudou Hiromi , Sinagawa Tsuyoshi , Yasuda Yukiharu , Shimizu Takashi , Morimoto Tsuyoshi , Shinohara Osamu , Yabe Hiromasa , Ando Kiyoshi , Kato Shunichi 
Published: April 2020

Abstract
[Introduction] An increasing number of long-term surviving stem cell transplantation (SCT) recipients have recovered from their primary disease but are at risk of developing failure of endocrine organs. Among the complications that have been described following SCT, metabolic syndrome (MS) has occurred in long-term survivors. Mechanism of MS as the late complication, however, is not completely elucidated.
[Patients & Methods] We investigated 52 recipients (30 males and 22 females) who underwent SCT during childhood or adolescence. The median age at SCT was 10.5 years (range 0.9–15.9 years), and the median follow-up duration after SCT was 15.0 years (range 6.7–24.7 years). Obesity was evaluated by analyzing changes in body mass index (BMI) and abdominal circumference. Lipid and glucose profiles were evaluated by the presence of fatty liver (hepatic steatosis), TG, T-Chol, HDL-C, LDL-C, adiponectine, leptin and HOMA-R, 75g OGTT, respectively.
[Results] 11 males (37%) and 11 females (50%) were diagnosed as fatty liver by abdominal ultrasound and computed tomography and biopsy was performed in selected patients. However only one male recipient satisfied MS criteria in all recipients. Among the 52 recipients, 9 males (30%) and 15 females (68%) indicated under 18.5 kg/m2 of BMI, whereas recipients with over 25 kg/m2 of BMI were two males and one female. The levels of TG and T-Chol were significantly higher in recipients with fatty liver compared to recipients without fatty liver (TG: 111mg/dL, range 49–751 vs 78, 41–219, p &lt;0.05, TC; 213mg/dL, 166–294 vs 175, 82–250, p &lt;0.05). In addition, the level of leptin was significantly increased in recipients with fatty liver compared to recipients without fatty liver (male: 9.9ng/mL, 2.4–20.8 vs 4.2, 1.9–10.4, p &lt;0.05, female: 18.0, 5.6–25.6 vs 7.9, 3.3–13.2, p &lt;0.05, respectively). On the other hand, the level of adiponectin was significantly decreased in recipients with fatty liver compared to recipients without fatty liver (male: 4.8 μg/mL, 2.6–8.9 vs 8.5, 5.0–29.5, p &lt;0.001, female: 4.1, 2.1–18.5 vs 11.4, 7.1–19.7, p &lt;0.05, respectively). The level of HOMA-R was significantly increased in recipients with fatty liver compared to recipients without fatty liver (2.3, 0.5–12.3 vs 1.2, 0.6–3.7, p &lt;0.05, respectively). Moreover, 75g OGTT indicated that insulin resistance significantly appeared in recipients with fatty liver.
Figure Figure
[Conclusion] These investigations emphasize the need of for long-term follow-up of endocrine and metabolic profiles in adult survivors of childhood SCT recipients.
CD55−CD59− Granulocytes in Patients with Aplastic Anemia Are Clonal Populations Derived from Single PIG-A Mutant Stem Cells without Any Proliferative Advantage.
Authors: Mochizuki Kanako , Sugimori Chiharu , Qi Zhirong , Lu Xuzhang , Nakao Shinji 
Published: April 2020

Abstract
Small populations of CD55−CD59− blood cells are detectable in approximately 50% of all acquired aplastic anemia (AA) patients and the presence of such PNH-type cells are also associated with a good response to immunosuppressive therapy (Sugimori C, et al. Blood 2006). In most patients showing 0.1% to 1.0% PNH-type cells at the diagnosis of AA, the PNH-type cell proportion remains unchanged over 3 years even after successfully responding to immunosuppressive therapy (Mochizuki K, et al. ASH 2006). Although these findings suggest that small populations of PNH-type cells are derived from a limited number of PIG-A mutants without any proliferative advantage, this hypothesis has not yet been verified at the molecular level. To appropriately address this issue, we studied 3 patients with AA who showed 0.14 to 1.6% PNH-type granulocytes. The CD55−CD59− granulocytes were sorted from these patients 2 different times at a minimum of 6 month intervals and then they were subjected to a PIG-A gene analysis. Five exons were amplified using 6 different primer sets and each amplified product was then subcloned into E. coli. At least 5 transformed clones for each amplified product were randomly plucked and subjected to sequencing. Single mutations were thereafter detected in all 3 patients as shown in Table 1. The same single mutations were then detected in the CD55−CD59− granulocytes from the patient obtained 6 months after the first examination. Two patients were in a state of hematologic remission at from 1 to 7 years after the first examination of their peripheral blood and the proportion of PNH-type cells remained stable during this period in all patients. Response to immunosuppressive therapy was not evaluable in one patient because he rejected ATG therapy. These findings indicate that PNH-type granulocytes from patients with AA are therefore clonal populations derived from single hematopoietic stem cells (HSCs) with a PIG-A mutation. If an AA patient has many HSCs with PIG-A mutations before the development of AA, then the immune system attack against HSCs should allow for the survival of the PIG-A mutants leading to the generation of a polyclonal PNH-type cell population. The presence of clonal PNH-type cells at the time of AA diagnosis suggests that the number of HSCs with a PIG-A mutation in healthy individuals may therefore be much lower than we expected and the paucity of PIG-A mutant HSCs may therefore account for the absence of increased number of PNH-type cells in approximately 20% of all AA patients who apparently respond to immunosuppressive therapy.
Table 1 Patient Age Gender Proportion of PNH-type granulocytes PIG-A mutation Response to IST 1 64 M 0.147% 593 bp (exon 2) T insertion PR 2 82 M 1.629% 3′splice site (intron 1) G to A change PR 3 76 M 0.161% 276 bp (exon 2) G deletion not evaluable