Somatic CALR mutations in myeloproliferative neoplasms with nonmutated JAK2

BACKGROUND

Somatic mutations in the Janus kinase 2 gene (JAK2) occur in many myeloproliferative neoplasms, but the molecular pathogenesis of myeloproliferative neoplasms with nonmutated JAK2 is obscure, and the diagnosis of these neoplasms remains a challenge.

METHODS

We performed exome sequencing of samples obtained from 151 patients with myeloproliferative neoplasms. The mutation status of the gene encoding calreticulin (CALR) was assessed in an additional 1345 hematologic cancers, 1517 other cancers, and 550 controls. We established phylogenetic trees using hematopoietic colonies. We assessed calreticulin subcellular localization using immunofluorescence and flow cytometry.

RESULTS

Exome sequencing identified 1498 mutations in 151 patients, with medians of 6.5, 6.5, and 13.0 mutations per patient in samples of polycythemia vera, essential thrombocythemia, and myelofibrosis, respectively. Somatic CALR mutations were found in 70 to 84% of samples of myeloproliferative neoplasms with nonmutated JAK2, in 8% of myelodysplasia samples, in occasional samples of other myeloid cancers, and in none of the other cancers. A total of 148 CALR mutations were identified with 19 distinct variants. Mutations were located in exon 9 and generated a +1 base-pair frameshift, which would result in a mutant protein with a novel C-terminal. Mutant calreticulin was observed in the endoplasmic reticulum without increased cell-surface or Golgi accumulation. Patients with myeloproliferative neoplasms carrying CALR mutations presented with higher platelet counts and lower hemoglobin levels than patients with mutated JAK2. Mutation of CALR was detected in hematopoietic stem and progenitor cells. Clonal analyses showed CALR mutations in the earliest phylogenetic node, a finding consistent with its role as an initiating mutation in some patients.

CONCLUSIONS

Somatic mutations in the endoplasmic reticulum chaperone CALR were found in a majority of patients with myeloproliferative neoplasms with nonmutated JAK2. (Funded by the Kay Kendall Leukaemia Fund and others.).

Isolation of megakaryocytes from human placentae

Shedding of cytoplasm from circulating megakaryocytes (MKs) within the pulmonary vasculature suggests the lungs are an important site for normal platelet production. Fetal lungs receive only a minor fraction of the circulating blood volume. The placenta may act as a site for intrauterine platelet formation. Isolation of MKs from fetal vessels within the placenta has not been previously reported. Immediately after delivery, 3 human placentae were subjected to forward and retrograde perfusion across the placental capillary bed on the fetal side. MKs in perfusates were harvested by 'whole blood filtration' and identified by morphological and immunochemical methods. All perfusates yielded MKs. Qualitatively MKs with copious cytoplasm were more commonly found in perfusates collected from fetal arteries compared with those from fetal veins. This is consistent with filtration of MKs and fragmentation of their cytoplasm within the placental microcirculation to produce platelets. Perfusion of human placentae followed by filtration of perfusates is a useful technique for harvesting fetal MKs and permitting further elucidation of their physiological role.

Common genetic variation contributes significantly to the risk of childhood B-cell precursor acute lymphoblastic leukemia

Recent genome-wide association studies (GWAS) have provided the first unambiguous evidence that common genetic variation influences the risk of childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL), identifying risk single-nucleotide polymorphisms (SNPs) localizing to 7p12.2, 9p21.3, 10q21.2 and 14q11.2. The testing of SNPs individually for an association in GWA studies necessitates the imposition of a very stringent P-value to address the issue of multiple testing. While this reduces false positives, real associations may be missed and therefore any estimate of the total heritability will be negatively biased. Using GWAS data on 823 BCP-ALL cases by considering all typed SNPs simultaneously, we have calculated that 24% of the total variation in BCP-ALL risk is accounted for common genetic variation (95% confidence interval 6-42%). Our findings provide support for a polygenic basis for susceptibility to BCP-ALL and have wider implications for future searches for novel disease-causing risk variants.

Surgical revascularisation in patients with severe limb ischaemia induces a pro-thrombotic state

Platelet and coagulation activation are implicated in the increased incidence of ischaemic events seen in patients with peripheral arterial disease. This study aimed to assess the effect of surgical revascularisation on platelet aggregation and coagulation in patients with severe limb ischaemia (SLI). Twenty-two patients had blood samples taken: prior to surgery, on reperfusion, 2, 24 and 48 h post-surgery. Platelet aggregation through COX-mediated and thrombin receptor activator peptide (TRAP)-stimulated GPIIb/IIIa pathways was measured by the Ultegra point of care system. Thrombin-antithrombin III Complex (TAT) and D-dimer were measured by ELISA. COX-mediated aggregation increased significantly at reperfusion and remained elevated at 24 h [median increase from baseline of 9% (range -16 to 33%) P = 0.011]. TRAP-stimulated aggregation increased significantly at reperfusion and remained elevated at 2 h post-surgery [median increase 18% (range -71 to 45%); P = 0.007]. TAT levels were significantly elevated from reperfusion and remained so at 48 h (P < 0.003), whereas D-dimer only increased at 24 h (P = 0.014). For the first time, we have demonstrated that in patients with SLI, platelet aggregation is increased following surgery and there is a mismatch in the balance between the coagulation and fibrinolytic pathways despite the use of aspirin and heparin. Thus in the early post-operative these patients exhibit a pro-thrombotic state.

Pathogenesis of chronic urticaria

Chronic urticaria is defined as the presence of urticaria (hives) for at least 6 weeks with the assumption that it occurs daily or close to it. If we eliminate physical urticarias and urticarial vasculitis from consideration, the remainder can be divided into autoimmune chronic urticaria (45%) and idiopathic chronic urticaria (55%). The autoimmune subgroup is associated with the IgG anti-IgE receptor alpha subunit in 35-40% of patients and IgG anti-IgE in an additional 5-10%. These autoantibodies have been shown to activate blood basophils and cutaneous mast cells in vitro with augmentation of basophil activation by complement and release of C5a, in particular. Binding methods (immunoblot and ELISA) yield positives in many autoimmune diseases as well as occasional normal subjects or patients with other forms of urticaria but most such sera are non-functional. Activation of basophils or mast cells causing histamine release is quite specific for chronic urticaria and defines the autoimmune subgroup. Although pathogenicity is not formally proven, the antibodies cause wealing upon intradermal injection, and removal of the autoantibody leads to remission. A cellular infiltrate is seen to be characterized by mast cell degranulation and infiltration of CD4+ T lymphocytes, monocytes, neutrophils, eosinophils, and basophils. The intensity of the infiltrate and clinical severity of the disease (including accompanying angio-oedema) is more severe in the autoimmune subpopulation. This latter group also has a higher evidence of human leucocyte antigen DR alleles associated with autoimmunity and a 25% incidence of antithyroid antibodies with diagnosed hypothyroidism in some. Hypo-responsiveness of patients' basophils to anti-IgE and hyperresponsiveness to serum defines another subpopulation (at least 50%) that overlaps the idiopathic and autoimmune subgroups. Hypo-responsiveness to anti-IgE has been shown to be associated with elevated levels of cytoplasmic phosphatases that inhibit degranulation. Reversal of the abnormality is seen with disease remission. Further work will be needed to distinguish whether this is a cause or a consequence of persistent urticaria and to further assess the relationship (or lack thereof) of altered responsiveness (decreased or increased) with the presence or absence of activating autoantibodies.

Genetic stability of human embryonic stem cells: A first-step toward the development of potential hESC-based systems for modeling childhood leukemia

Human ESCs provide an opportunity for modeling human-specific strategies to study the earliest events leading to normal hematopoietic specification versus leukemic transformation. Of interest, are the human childhood acute leukemias harboring specific fusion oncogenes such as MLL-AF4, TEL-AML1 or BCR-ABL wherein clinically significant manifestations arise in utero. The mechanisms of transformation are not amenable to analysis with patient samples and, many mouse models for pediatric leukemias have fallen short in illuminating the human disease because they do not recapitulate key aspects of the actual disease, suggesting that the mouse models are missing essential components of oncogenesis present in the human embryo. Prior to using hESCs as a tentative system for modeling leukemia, robust studies aimed at demonstrating their genetic stability are required; otherwise, cooperating mutations already present could prime hESCs susceptible to transformation. We performed an extensive molecular cytogenetic and cellular in vitro and in vivo analysis which reveals an overall genomic stability of HS181 and HS293 hESCs maintained long-term by mechanical dissociation in human feeders. Importantly, we show for the first time that the genetically stable HS181 hESC line differentiates into CD45+ hematopoietic cells and clonogenic hematopoietic progenitors. This data should encourage stem cell researchers to implement robust cytogenetic tools when assessing hESC genetic stability, in order to detect tiny but relevant biological functional or structural chromosome abnormalities and, paves the way for generating fusion oncogene-expressing transgenic hESCs as a human-specific system for studying the early in utero events leading to normal hematopoietic specification versus childhood leukemic transformation.

Stability of THAI ™ Process-Theoretical And Experimental Observations

Abstract

The performance of the THAI ™ process has been investigated in numerous 3D experiments, using heavy crudes and Athabasca oil sands bitumen. The stability of the process is demonstrated by high combustion zone temperatures, absence of gas channelling, insensitivity to large changes in air injection rate, tolerance of an overlying gas cap, increased combustion temperature and faster upgrading response with increasing oil layer thickness, 'controlled gas override', own 'front tracking' capability and steady oil production rate. The most important parameters for upscaling of (stable) experimental scale performance to (stable) field scale operation are combustion front temperature and combustion front velocity. Early stage results from the WHITESANDS THAI ™ field pilot at Christina Lake, confirm high combustion zone temperatures (700 – 800 °C), high fluids production of up to 2,000 barrels per day of gross fluids (50 – 55% bitumen cut) and signs of significant partial upgrading (up to 8.2 °API). These measures of field pilot performance are consistent with the experimental findings from 3D physical experiments. They are very encouraging indicators for the future development of THAI ™on a commercial scale.

Introduction

There is a long and tortuous history concerning the in situ combustion (ISC) process as applied to heavy crude and oil sands reservoirs. Some parts of it were tremendously innovative and successful, but there were also many failures, often due to poorly chosen reservoirs. One of the main reasons why projects failed was lack of control of propagation of the in situ combustion front. In many cases, there was a lack of understanding of the part played by gravity, and hence gravity segregation.

Since the first field test of the ISC process in 1951, more than 160 field pilots have been conducted; most of them in the period 1970 – 1990. This led to the development of both the dry and wet ISC processes. They were tested for normal heavy oil and for oil sands using air and enriched air. However, the commercial application of ISC was attained only for heavy crude reservoirs around 1970, using air injection. At that time, most operators started to realize that ISC was actually a gas displacement process, benefiting from oil viscosity reduction due to heat generated by ISC reactions. Therefore, as in any gas displacement process, the injectors should be located at the most updip position.

As of April 1992, according to an Oil & Gas Journal report, the incremental daily production from ISC was approximately 4,700 BOPD (from eight projects) in the USA, 8,000 BOPD (from ten projects) in the former Soviet Union, 7,300 BOPD (from three projects) in Canada and 12,000 BOPD (from five projects) in Romania. Thus, the 1992 world incremental daily oil production due to ISC was about 32,000 BOPD (from 26 reported projects)(1, 2). This included nineteen commercial operations and seven semi-industrial projects.

Currently, only four commercial heavy oil projects are active: Suplacu de Barcau (Romania), Balol and Santhal projects (India) and Bayou State Oil Corp. (BSOC) in Bellevue, Louisiana, USA.