bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Protein Subunit of Telomerase Is Downregulated with Normal Myeloid Differentiation, but Reactivated in Leukemic Progenitors.
Authors: Jamieson Catriona , Gilison D. , Allsopp R. , Weissman I. , Artandi S. 
Published: October 2019

Abstract
Telomeres are comprised of TTAGGG nucleotide repeats and a large protein complex that together protect chromosomal ends. Telomeres shorten progressively with cell division in the absence of telomerase, a reverse transcriptase that synthesizes telomere repeats. Critical telomere shortening has potent effects on cancer development, either blocking cancer progression by impairing proliferation and survival or promoting cancer by enhancing chromosomal instability. Although telomerase is upregulated in the vast majority of human cancers, where it is thought to endow cancer cells with unlimited proliferative capacity, the regulation of telomerase during the course of normal lineage development or during leukemogenesis remains unclear. Here, we show that expression of TERT, the protein catalytic subunit of telomerase, is tightly regulated during myeloid development in both human and mouse. Real time PCR analysis of RNA from purified human stem cell and progenitor cell populations showed that TERT mRNA was highest in human HSCs (100%, values normalized to HSC). TERT mRNA remained high in common myeloid progenitors (CMP, 47%), but was dramatically decreased with differentiation to granulocyte-monocyte progenitors (GMP, 3%) or megakaryocyte-erythroid progenitors (MEP, 0.2%). TERT was similarly down regulated during normal myeloid development in mouse bone marrow. In marked contrast, TERT was reactivated in leukemic GMP in a transgenic Faslpr/lprhMRP8BCL2 mouse model of acute myelogenous leukemia. Notably, transplantation experiments demonstrated that leukemic GMP provided the most robust leukemic transplantation potential compared with HSC or blasts suggesting that TERT reactivation may provide an important final step in leukemic pathogenesis by enhancing the replicative life-span of leukemic progenitors. Currently, we are in the process of assessing TERT regulation in human leukemic progenitors isolated from patients with CML in chronic, accelerated and blast phases. Together, these data indicate that TERT is most highly expressed in stem cells and multipotent progenitors. This pattern of TERT expression may reflect a need for efficient telomere maintenance in these stem/progenitor compartments. Furthermore, these data are consistent with our recent data showing novel, telomere length-independent functions for TERT in stem/progenitor cell compartments.
Proteomic Identification of TAL1/SCL-Interacting Proteins: ETO-2 and MTGR1 Interact with TAL1 in Erythroid Progenitors.
Authors: Cai Ying , Xu Zhixiong , Xie Jingping , Koury Mark J. , Hiebert Scott W. , Brandt Stephen J. 
Published: October 2019

Abstract
The TAL1/SCL gene, originally identified from its involvement by a recurrent chromosomal translocation in T-cel acute lymphoblastic leukemia, encodes a basic helix-loop-helix (bHLH) transcription factor essential for hematopoietic and vascular development. Although TAL1 is believed to regulate transcription of specific sets of target genes, the mechanisms underlying TAL1-directed gene expression are poorly understood. Previous studies have shown, in fact, that it can act as either an activator or repressor depending on the coregulator(s) with which it interacts. To comprehensively identify TAL1’s interaction partners in erythroid cells, we stably expressed a tandem epitope-tagged mouse TAL1 protein in murine erythroleukemia (MEL) cells and determined the composition of affinity-purified TAL1-containing complexes by multidimensional mass spectrometry. From this analysis, we identified all known members of a TAL1-containing DNA binding complex previously characterized in erythroid cells, including TAL1, its E protein DNA-binding partners, the zinc finger transcription factor GATA-1, the LIM-only protein LMO2, and the LIM domain-binding protein Ldb1, as well as proteins described to interact with GATA-1 (FOG-1), LMO2 (ELF2A2), and Ldb1 (SSDP2 and SSDP3). In addition, we identified a number of other DNA binding proteins, chromatin modifying proteins, and transcriptional regulators, including the ETO family members ETO-2 and MTGR1. TAL1 interaction with ETO-2 and MTGR1 was verified by coimmunoprecipitation analysis in MEL cells expressing these proteins at endogenous levels, in MEL cells stably expressing an epitope-tagged TAL1 protein, and in COS cells transiently transfected with TAL1 and ETO-2 or MTGR1 expression vectors. Mapping analysis with GAL4 fusion proteins identified the bHLH domain as the region in TAL1 responsible for interaction with these ETO family proteins. Significantly, expression of MTGR1 enhanced ETO-2 interaction with TAL1-GAL4 protein. Finally, transient transfection analysis with a luciferase reporter construct linked to multiple GAL4 DNA binding sites showed greater than additive augmentation of TAL1-directed gene repression with coexpression of the two ETO-related proteins compared to that observed with ETO-2 or MTGR1 transfected individually. These results identify ETO-2 and MTGR1 as authentic TAL1 interacting proteins and suggest that a hetero-oligomeric complex of the two contributes to TAL1-directed repression in erythroid progenitors.
Increased Generation of Hepatocytes Expressing Bone Marrow-Derived Markers after Hematopoietic Progenitors’ Mobilization in a Murine Model of Hepatic Damage.
Authors: Fellow Oscar Quintana-Bustamante , Alvarez-Barrientos Alberto , Fabregat Isabel , Bueren Juan A. , Segovia Jose C. 
Published: October 2019

Abstract
The contribution bone marrow (BM) cells to the repair of a damaged liver has been described in animal models and in humans. This process has been explained both as a result of hematopoietic stem cell (HSC) trans-differentiation, as well as a result of cell fusion between HSC-derived cells with cells from non-hematopoietic tissues. In the present work we have investigated whether the mobilization of HSCs can increase the generation of BM- derived hepatocytes (BM-DHs) in damaged livers. With this purpose, Ly-5.1 mice were myeloablated and transplanted with 107 BM cells from Ly-5.2 congenic mice, which also express the green fluorescent protein (EGFP) under the control of the b-actin promoter. Three months after transplantation, groups of 4–6 animals were injected with saline or with carbon tetrachloride (CCL4) for three more months to induce a cirrhosis-like damage. A marked dysbalance in serologic parameters, together with an altered hepatic structure was observed in the CCL4-treated animals. Part of the animals corresponding to each group were mobilized with G-CSF for one, two or three weeks. No difference in the mobilization of hematopoietic cells was observed in CCL4-treated versus non-treated animals. One month after G-CSF treatment, animals were sacrificed and the presence of BM-DHs, identified as EGFP+CD45− hepatocyte-like cells, with ability to accumulate glycogen, was evaluated by fluorescent immuno-histochemistry using specific antibodies for EGFP and the murine Ly-5.2 panleukocyte antigen and successive PAS staining. BM-DHs were clearly observed after hepatic damage (4 BM-DH/106 cells) at rates similar to results already published by others. Moreover, the G-CSF mobilization significantly augmented the percentage of BM-DHs in the liver of CCl4-treated and non CCl4-treated mice (69/106 and 23/106 cells, respectively). Whether these BM-DHs result from the trans-differentiation of HSCs or from the in vivo fusion of HSC-derived cells, and whether the mobilization treatment improve the recovery of the damaged liver are now under study. Taken together, this data demonstrate that the mobilization of HSCs from the BM to the periphery markedly increases the presence of BM-DHs in the liver of transplanted mice, opening the possibility of using hematopoietic growth factors in the treatment of non-hematopoietic degenerative diseases.
Safety and Efficacy of Alternate Desferrioxamine and Deferiprone Compared to Desferrioxamine Alone in the Treatment of Iron Overload in Transfusion-Dependent Thalassemia Patients.
Authors: Galanello Renzo , Kattamis Antonios , Piga Antonio , Tricta Fernando 
Published: October 2019

The safety and efficacy of alternating desferrioxamine and deferiprone for the treatment of iron overload in patients with transfusion-dependent anemias was studied in 60 thalassemia patients regularly treated with desferrioxamine. Patients were randomized to continue desferrioxamine alone (20–60 mg/kg/day, 5–7 days/week) or to alternate desferrioxamine (20–60 mg/kg/day, 2 days/week) with oral deferiprone (25 mg/kg tid, 5 days/week). Both treatment groups were similar for age (19.8 ± 6.1 years for desferrioxamine alone and 18.7 ± 4.8 years for alternate therapy) as was gender distribution and mean standard dose of desferrioxamine at the time of study initiation. Over the following 12 months, all patients were monitored weekly for adverse events and for their white blood cell count. Efficacy of the chelation was evaluated by measurement of the serum ferritin, liver iron concentration (magnetic susceptometry by SQUID), and by Non-Transferrin Bound Iron (NTBI). Compliance was comparable for both arms (96.1 ± 5.0% for alternate therapy vs 95.7 ± 5.7 % for desferrioxamine alone; p=0.7883). There was no significant difference in the proportion of patients with adverse events in the two therapy groups but the chelation regimens were associated with distinct adverse events. The alternate therapy was associated with transient gastrointestinal symptoms, such as vomiting in 5 patients (17%), abdominal pain in 3 patients (10%), or diarrhea in one patient (3%), or transient increase of serum ALT levels in one patient (3%), occurring mainly in the first weeks of therapy and were mild/moderate in severity. Daily infusions of desferrioxamine were associated with abscess at the site of infusion in one patient (3%), and allergic reactions in another patient (3%). Mean serum ALT levels were not significantly different between the two therapies. There were no episodes of agranulocytosis and only one patient, treated with desferrioxamine alone, experienced milder neutropenia.
Both therapies resulted in similar decreases of serum ferritin (−349 ± 573 mg/L for the desferrioxamine arm; −248 ± 791 for the alternate arm; p=0.5802), and of liver iron concentrations (−239 ± 474 μg/g wet weight for the desferrioxamine arm; −65 ± 615 μg/g wet weight for the alternate therapy arm; p=0.2263) by the end of the treatment period. No significant changes in NTBI were observed between the two treatment arms (1.10 ± 7.19 μmol/L for the desferrioxamine arm; −0.03 ± 8.13 μmol/L for the alternate arm; p=0.5775). In conclusion, this 12 month study in transfusion-dependent thalassemia demonstrated that the alternating therapy with deferiprone and desferrioxamine is not associated with a significant increase in the incidence of adverse events and that it has comparable efficacy to desferrioxamine alone in controlling iron overload.
Analytical Performance Evaluation of a Linear Array-Based β-Hemoglobinopathy Mutation Assay.
Authors: Jarvis Michael , Komaromy-Hiller Gabor , Amos Jean 
Published: October 2019

Abstract
Routine clinical evaluation of β-globin phenotypes usually includes HPLC screening and alkaline/acid electrophoresis and/or isoelectric focusing. Although common structural variants are easily identified in the routine environment, specific β-thalassemia mutations are not and these can be the basis for prognosis and also for subsequent prenatal diagnosis for at-risk family members. Herein, we report evaluation of the performance of a linear array-based β- hemoglobinopathy mutation assay provided by Roche Molecular Diagnostics (Pleasanton, CA) that detects 6 β-globin variants (S, C, E, Knossos, D-Los Angeles and O-Arab) and 42 β-thalassemia mutations (90% predicted detection in any at-risk population group). The assay consists of one multiplex PCR with biotinylated primers, amplicon hybridization to a reverse line blot array, and colorimetric detection of a streptavidin-HRP conjugate. We tested 50 archived, abnormal and 92 sequential clinical samples, all previously tested in our routine assays. The results of the DNA and HPLC/electrophoresis were 100% consistent with the linear array, although Hb-S, C, D-Los Angeles and E were the only structural variants present in our collection. We verified the presence of Hb-S and excluded Hb-O-Arab in an ambiguous compound heterozygote for which HPLC and electrophoresis could not distinguish possible Hb-C-Harlem from Hb-O-Arab. Of 15 putative β-thalassemia minor samples, 10 had 6 different β-thalassemia mutations. Based on our experience, the daily throughput for a single technologist performing this mutation analysis is approximately 200 samples; it is, thus, an appropriate second-tier assay for newborn screening programs. The assay is robust, reliable and is also an excellent screen prior to sequencing for rare mutations.
Lack of Correlation between Serum Ferritin and Liver Iron Concentration in Beta-Zero Thalassemia Intermedia.
Authors: Galanello Renzo , Giagu Nicolina , Barella Susanna , Maccioni Liliana , Origa Raffaella 
Published: October 2019

Abstract
Serum ferritin and liver iron concentration (LIC) are the most commonly used methods for assessment of iron overload in thalassemia. While in patients with thalassemia major a significant correlation has been found between these two parameters, data are lacking in patients with thalassemia intermedia. In this study we measured the serum ferritin and LIC in 22 adult patients with beta-zero thalassemia intermedia never transfused (14 patients) or sporadically transfused, i.e. less than 10 units in total (8 patients), who maintained a mean hemoglobin of 8.8 ± 1.1 g/dl. Serum ferritin levels were measured by an automated chemiluminescence immunoassay analyzer, whereas LIC was determined by atomic absorption in liver biopsies. We compared the results obtained in those patients with those obtained in 22 regularly transfused (mean annual Hb = 11.3 ± 0.3 g/dl) and iron chelated thalassemia major patients, matched by sex, age and liver iron concentration. We also determined serum erythropoietin (s-epo) and serum transferrin receptor (s-TfR) in a cohort of the two patient groups (12 thalassemia intermedia; 15 thalassemia major). Mean LIC was 11.3 ± 6 mg/g dry weight tissue in thalassemia intermedia, and 11.8 ± 7 mg/g d.w. in thalassemia major group. Mean serum ferritin (at least 2 determinations from each patient within ± 2 months of liver biopsy) was 627 ± 309 ng/ml in thalassemia intermedia and 2748 ± 2510 ng/ml in thalassemia major. The difference was statistically significant (p = 0.0001). LIC was weakly correlated with serum ferritin in thalassemia major patients (r2=0.46; p=0.001) and uncorrelated in patients with thalassemia intermedia (r2=0.04; p=0.37) (Figure). S-epo and s-TfR were significantly higher in thalassemia intermedia than in thalassemia major [s-epo 467 ± 454 mU/ml versus 71 ± 44 mU/ml (p<0.001); s-TfR 43 ± 13 mU/ ml versus 13 ± 6 mU/ml (p<0.0001)]. The discrepancy between LIC and serum ferritin in thalassemia intermedia patients may be due to the higher levels of s-epo (secondary to anemia) in those patients, which through the iron regulatory protein 1 determine an up-regulation of s-TfR and a repression of ferritin translation (Weiss et al 1997). The mechanism of iron overload may also be mediated by hepcidin, whose synthesis could be suppressed as a consequence of anemia. The observation reported has important implications for iron chelation in patients with thalassemia intermedia. In such patients serum ferritin levels have little value for the monitoring of iron overload.
Figure Figure
Relevance of Routine Bacterial Screening of Pooled Random Platelet Concentrates with the Bactalert® System.
Authors: te Boekhorst Peter A.W. , Beckers Erik A.M. , Vos Greet C. , Vermeij Hans , Leebeek Frank W.G. , van Rhenen Dick J. 
Published: October 2019

Abstract
Background: Transfusion of bacterial contaminated platelet (PLT) units can cause serious transfusion reactions. To prevent this complication, bacterial screening by the automated BacTalert® system of platelet concentrates was implemented in the southwest part of the Netherlands since october 2001. Despite this system, two severe transfusion reactions caused by bacterial contaminated PLT units occurred. Therefore, evaluation of the efficacy of this approach was done.
Material and Methods: PLT products in the Netherlands are produced by the Sanquin Bloodbanks. In the Southwest part of the Netherlands PLT products mainly consist of pooled products derived from five random donors. Of all produced platelet products, samples were taken and cultured (aerobic and anaerobic) for seven days using the automated BacTalert® system. The PLT products were issued to the hospitals on a "negative-to-date" basis. In case of positive cultures, conformation and identification cultures were taken. At the same time, involved and related products thet were derived from the same donor were also withdrawn. In case of delivery of possibly contaminated products to the hospitals, these were notified and the products were recalled. If the products were already transfused, treating physicians were notified and asked if adverse reactions had occurred in these patients.
Results: From October 2001 to 2003, a total of 28,104 produced pooled PLT units were tested for bacterial contamination using the BacTalert® system. Positive signals were found in 203 (0,72%) samples. At the time of a positive signal, 125 PLT products were already issued to the hospitals and of these 125 products, 113 units were already administered to patients. Analysis of all positive cultures revealed mainly skin-derived bacteria, but in 15 sample Bacillus cereus (7%). In 9.4% (=19) of the samples with a postive BacTalert® signal, bacterial growth could not be confirmed. None of the PLT units with a postive bacterial culture that were already administered to patients caused clinically significant transfusion reactions. Nevertheless, two neutropenic patients due to leukemia treatment, suffered from life-threatening B. cereus sepsis after PLT transfusion. In both cases, B.cereus was cultured from the PLT bags, whereas the BacTalert® tested samples remained negative.
Conclusions: Issuing pooled PLT units on a negative-to-date basis for bacterial screening resulted in a significant amount of recall procedures. The BacTalert® system failed to detect B. cereus contamination in at least two cases that resulted in sever transfusion reactions. Other strategies, including pathogen reduction, might be applied to guarantee a better degree of bacterial safety.
Complications of Pediatric Apheresis.
Authors: Michon Bruno , Duval Michel , Winikoff Rochelle , Champagne Martin A. 
Published: October 2019

Objectives
Even if the practice and applications of apheresis have grown over the last decade, the data in pediatrics are limited. The frequency of the complications is low in adults but there is a lack of clinical trials assessing the nature and the frequency of the complications in children.
Methods
We have revised the medical files of all patients (0–18 years old) who have undergone an apheresis at Ste-Justine Hospital (pediatric hospital in Montreal, Canada) between November 1994 and July 2002. The reported complications were: symptoms of hypocalcemia, hypotensions (drop of systolic BP ≥10 mmg Hg), complications of the vascular access (thrombosis and infection), reactions to blood products and severe anemia.
Results
A total of 1632 aphereis were performed on 186 different patients (32 distinct diagnosis). The procedures were plasma exchange (67%), peripheral blood stem cells collect (18%), red cell exchange (6,9%), cytoreduction leucapheresis (0,7%) and immunoadsorption (6,7%). Adverse reactions, although mostly minor, were reported in most of the patients. The more frequent complications were hypotensions (14% of apheresis and 48,4% of patients), hypotensions which needed bolus (4,8% of apheresis and 26,9% of patients) , symptoms of hypocalcemia (9,7% and 28,5%), allergic reactions (4,4% and 5,9%) and troubles related to the vascular access: infection (2,1% and 16,1%) and thrombosis (1,7% and 12,4%). A severe anemia (Hb < 70g/L) complicated 2,5% of apheresis (17,2% of patients). There were two deaths related to procedures. With a multivariate analysis, we have identified independent risk factors for occurence of complications: lower weight, lower hemoglobin pre-pheresis, pheresis in ICU and number of pheresis.
Conclusion
The incidence of complications of apheresis in our pediatric cohort is much higher than what is reported in adults. The adverse reactions can be explained by the citrate toxicity, the extravascular volume shift and the vascular access installed. We consider that apheresis in pediatrics present unique features and should be done in specialized centers.
Increased Clearance Explains the Ultra-Large Multimers in Von Willebrand Disease Type 2M Vicenza; Lessons from Recombinant VWF Vicenza and Modeling of Multimer Catabolism.
Authors: Gézsi András , Balázsi Gábor , Sallai Krisztina , Mohl Adrienn , Nagy Eszter , Szabó Teréz , Sadler J. Evan , Bodó Imre 
Published: October 2019

Abstract
The pathogenesis of VWD Vicenza has remained elusive. VWD Vicenza is characterized by low plasma but normal platelet VWF concentration, the presence of ultra-large plasma multimers, and a heterozygous R1205H mutation. VWF Vicenza is reported to have a decreased half-life in the circulation. When we expressed rVWF Vicenza R1205H in 293T cells, it was secreted with wild type efficiency and multimer distribution, suggesting that the primary defect is accelerated clearance. To evaluate this hypothesis, we developed a pharmacokinetic model of VWF multimer catabolism. The initial assumptions are: 1. Secretion occurs at a fixed rate with the initial “ultra-large” multimer distribution seen in platelet alpha granules. 2. Cleavage of multimers occurs with a probability p that increases with increasing multimer size. 3. Clearance occurs with a time constant determined by the plasma half life and is independent of multimer size. Modeled multimer distributions were compared to those determined experimentally for patient plasma samples. The effects of DDAVP infusion also were modeled and compared to published data (Casonato et al, Blood2002; 99:180). For p = 7.5 x 10−4 min−1 and a half life of 12 h, the modeled multimer patterns were comparable to the observed steady-state distribution of normal VWF. Decreasing the half life to 2 hours produces a low plasma concentration of “ultra-large” multimers typical of VWD Vicenza without a change in any other parameter. Conversely, increasing the probability of cleavage by only thirty percent produces typical VWD 2A multimer distributions. The model also reproduces the triplet patterns of normal and type 2A VWF. Finally, the DDAVP simulations reproduced the time course of VWF plasma concentrations and multimer distributions of DDAVP-treated patients. We conclude that increased clearance alone can explain the ultra-large multimer distribution of VWD Vicenza. Similar modeling should allow the estimation of VWF cleavage and clearance rates in other variants of VWD and in other clinical situations including thrombotic thrombocytopenic purpura.
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