Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0032463 (polycythemia vera)
 3,374 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We measured serum concentrations of erythropoietin in 59 patients with polycythemia using a sensitive and specific radioimmunoassay. The mean concentration was 17.5 +/- 8.4 mU/mL (+/- SD) in 26 patients with polycythemia vera and 14.9 +/- 4.2 mU/mL in 26 normal persons. In contrast, the average concentration was 94.3 +/- 101.2 mU/mL in 33 patients with secondary polycythemia, representing a highly significant elevation (p < 0.0001) compared to both normal and polycythemia vera groups. The average hematocrit value did not differ between the polycythemia vera and the secondary polycythemia patients, and both groups had higher values (median, 55%) than the normal donors (median, 41%). Erythropoietin concentrations ascertained by radioimmunoassay helped discriminate between polycythemia vera and secondary polycythemia. Ninety-two percent of polycythemia vera patients had concentrations less than 30 mU/mL (the concentration used as a cut off point), and 94% of secondary polycythemia patients had concentrations greater than 30 mU/mL. This represents an overall correct classification of 93% of the patients. Serum erythropoietin levels as ascertained by radioimmunoassay can distinguish between most polycythemia vera and secondary polycythemia patients and should prove useful in the differential diagnosis of polycythemia.
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PMID:Erythropoietin radioimmunoassay in evaluating patients with polycythemia. 744 23

Erythropoietin (EPO) is a prime stimulating factor for red cell production. EPO is a glycoprotein which has a molecular weight of 34,000, and is mainly produced by the kidney. EPO stimulates the differentiation and proliferation of erythroid progenitor cells in the bone marrow. The rate of production of EPO is regulated primarily by renal oxygen availability. Because anemia reduces renal oxygen availability, anemic stress accelerates EPO production in the kidney. Recently, EPO has mainly been determined by radioimmunoassay. Serum EPO titer is usually inversely correlated with hemoglobin concentration, as typically shown in iron deficiency anemia. Serum EPO titers in aplastic anemia are much higher than those in iron deficiency anemia relative to the hemoglobin concentration. Serum EPO titers in anemia caused by malignancies sometimes differ considerably among patients. Serum EPO in renal anemia usually show low titers irrespective of the degree of anemia. Serum EPO titers in untreated polycythemia vera are lower than those in treated polycythemia vera or secondary polycythemia. Determination of serum EPO is useful in differential diagnosis of polycythemia vera. Recombinant human EPO has been used to treat various anemias including renal anemia, refractory anemia, anemia in malignancies and secondary anemia. Determination of serum EPO titers is also valuable in many other situations of clinical medicine.
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PMID:[Erythropoietin determination in clinical medicine]. 835 Apr 98

Erythropoietin (EP) and stem cell factor (SCF) are essential growth factors for erythroid progenitor cell proliferation and differentiation in serum-free culture. It has been previously shown that burst-forming units-erythroid and colony-forming units-erythroid from patients with polycythemia vera (PV) have enhanced sensitivity to EP and SCF compared with normal erythroid progenitors, but little is known about the mechanism for this difference. In the present investigation, the effect of EP and SCF on protein tyrosine phosphorylation in day-8 normal and PV erythroid colony-forming cells, which give rise to colonies of 2-49 hemoglobinized cells, was studied. EP rapidly induced tyrosine phosphorylation of the EP receptor, whereas the most prominent phosphorylated protein induced by SCF was identified as the SCF receptor. No additional phosphorylated proteins were evident when PV cells were compared with normal cells. Culture of normal erythroid progenitors with orthovanadate, an inhibitor of protein tyrosine phosphatases, resulted in an increased number of erythroid colonies and enhanced protein tyrosine phosphorylation. However, in contrast, little enhancement was evident with PV cells. These results indicate that, although vanadate may be acting in normal erythroid progenitors as a phosphatase inhibitor that potentiates the kinase activity induced by SCF and EP, this function is diminished in PV cells. Because erythropoiesis is regulated by a balance between protein tyrosine kinase activity and protein tyrosine phosphatase activity, PV patients may have an abnormal phosphatase activity allowing increased cell proliferation.
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PMID:Polycythemia vera. V. Enhanced proliferation and phosphorylation due to vanadate are diminished in polycythemia vera erythroid progenitor cells: a possible defect of phosphatase activity in polycythemia vera. 916 Jun 62

The term "absolute erythrocytosis" denotes a heterogeneous group of disorders characterized by an increased red blood cell mass. The authors describe a 20-month-old girl with absolute erythrocytosis. Erythropoietin levels were found to be extremely increased, although extensive evaluation failed to reveal a cause for such an inappropriate increase. Of interest is also the documentation of spontaneous erythroid colony formation in the patient's bone marrow cultures. Although such a finding is considered typical of polycythemia vera, the diagnostic criteria of this myeloproliferative disorder were not met.
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PMID:Congenital erythrocytosis with increased erythropoietin level. 1199 Mar 14

We report the case of an 2-year-old boy presenting an essential polycythemia since birth, with details of the diagnostic procedures used and clinical course. Pediatric cases are very rare, and a secondary acquired polycythemia should be first investigated. Most causes of primary childhood polycythemia remains unknown. Erythropoietin (EPO) level may help to separate diseases with high EPO (Chuvash, or yet unclassified), or with normal/low EPO (congenital with truncation of the EPO receptor, polycythemia vera-Vaquez disease-, or currently with unknown mechanism).
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PMID:[Childhood essential polycythemia: an unusual disorder]. 1568 16

The JAK2(V617F) mutation is present in almost all patients with polycythemia vera (PV), large proportions of patients with essential thrombocythemia and idiopathic myelofibrosis, and less frequently in atypical myeloproliferative disorders (MPD). We show that transplantation of JAK2(V617F)-transduced bone marrow into BALB/c mice induces MPD reminiscent of human PV, characterized by erythrocytosis, granulocytosis, extramedullary hematopoiesis, and bone marrow fibrosis, but not thrombocytosis. Fluorescence-activated cell sorting of bone marrow and spleen showed proportional expansion of common myeloid progenitors, granulocyte-monocyte and megakaryocyte-erythrocyte progenitors. Megakaryocyte and late erythroid progenitors were dramatically increased, with only modest expansion of early erythroid progenitors. Erythropoietin (Epo) receptor expression was reduced on early, but normal on late erythroblasts. Serum levels of Epo and granulocyte colony-stimulating factor, but not granulocyte macrophage colony-stimulating factor, were reduced, whereas tumor necrosis factor-alpha was increased, possibly exerting a negative effect on JAK2(V617F)-negative hematopoiesis. These data suggest that erythrocytosis and granulocytosis in JAK2(V617F) mice are the net result of a complex interplay between cell intrinsic and extrinsic factors. There were no thromboembolic events and no animals succumbed to their disease, implicating additional factors in the manifestation of human disease. The disease was not transplantable and prolonged observation showed normalization of blood counts in most JAK2(V617F) mice, suggesting that the mutation may not confer self-renewal capacity.
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PMID:Characterization of murine JAK2V617F-positive myeloproliferative disease. 1714 59

Cavernoma of the portal vein is defined as a formation of venous channels within or around a previously thrombosed portal vein. We experienced a 50-year-old woman who presented a huge hepatic mass with right upper quadrant dull pain. Abdominal computed tomography showed a huge sponge-like hepatic mass with cavernous transformation of portal vein along the common bile duct and common hepatic duct. She had increased hemoglobin/hematocrit (15.7 g/dL/49.1%) and red blood cell mass (35 mL/kg). Platelet count was 450,000/microL and white blood cell count was 13,500/microL. Erythropoietin level was low normal range (10.2 mU/mL). Bone marrow biopsy showed a moderately hypercellular marrow and overall cellularity was about 80-90%. Megakaryocytes were slightly increased in number with abnormal clusterings Myelopoiesis and erythropoiesis were also slightly increased with moderate to severe fibrosis. She was diagnosed as polycythemia vera with cavernous transformation of portal vein. Repeated thrombosis occurred in the leg and the toe and was treated with angioplasty and thrombolytic therapy with phlebotomy.
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PMID:[A case of cavernoma of portal vein associated with polycythemia vera]. 1723 36

Erythropoietin (EPO) is the principal haematopoietic growth factor of the red blood cell line. Its major role is to stimulate the red blood cell production. EPO synthesis by peritubular cells in the kidney is regulated by oxygen concentration and must lead adaptation of the organism to face many different physiological situations. An imbalance can lead either to anaemia or polycythemia. Synthetic EPO, so-called recombinant, has definitively changed the treatment in the anaemia of chronic renal failure and regularly find new indications, legal (anaemia of cancer, anaemia of chronic inflammatory syndromes, myelodysplastic syndromes, neurology, cardiology...) or illegal (doping substance in sport). This article reviews the physiology, the role and the indications of EPO in clinical routine practice and define why and how EPO should be measured. We also focus on the analytical requirements for serum EPO concentration determination, especially in the differential diagnosis of polycythemias (secondary polycythemia/Polycythemia Vera).
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PMID:[Erythropoietin: indications and measurement]. 1978 22

Polycythemia vera (PV) is a stem cell disorder, characterized as a panhyperplastic, malignant, and neoplastic marrow disorder. Several reasons suggest that a mutation on the Janus kinase-2 gene (JAK2) is the most probable candidate gene involved in PV pathogenesis, as JAK2 is directly involved in intracellular signaling, following its exposure to cytokines, to which PV progenitor cells display hypersensitivity. A recurrent unique acquired clonal mutation in JAK2 was found in most patients with PV and other myeloproliferative diseases (MPDs). A female patient of age 50 years, presented with hemiplegia, diplopia, and had a consistent rise in hemoglobin and hematocrit. Serum Erythropoietin (Epo) was decreased. JAK2 mutation analysis was found to be negative. A diagnosis of polycythemia vera was made on the basis of the British Committee for Standards in Hematology (BCSH) guidelines.
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PMID:JAK2 Negative Polycythemia Vera. 2134 10

The JAK2V617F mutation that results in a hyper-activation of the JAK2 kinase in the erythropoietin pathway is a molecular marker for myeloproliferative neoplasms. Using allele-specific Real-Time PCR, we detected the mutation in the blood of 17.3% (17/98) of normal donors; the mutant allele burden was, however, very low (<0.01% compared to >1% in polycythemia vera). It was much higher in differentiated blood cells in the peripheral blood than in undifferentiated CD34+ cells. Erythropoietin-stimulated differentiation of normal CD34+ cells in liquid culture increased the mutation frequency by 3.34-fold. When progenitors from 9 normal donors were grown in erythropoietin-stimulated semi-solid cultures, the mutation was found in 8.69% of the colonies, but only in <3% of the JAK2 alleles in each positive colony, suggesting that the mutation occurred only in a few cells per colony. In mouse erythroleukemia cells carrying human JAK2 DNA, wild-type or JAK2V617F, the frequencies of mutations from JAK2 wild-type to JAK2V617F and vice versa increased following erythroid differentiation. These results suggest that the mutation occurs and accumulates during differentiation. We hypothesize that genetic stability, which relies on DNA repair, is efficient in normal hematopoietic stem cells but is downgraded in differentiating cells, rendering them susceptible to mutations, including JAK2V617F.
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PMID:The JAK2V617F mutation in normal individuals takes place in differentiating cells. 2812 23


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