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Query: UMLS:C0032463 (polycythemia vera)
 3,374 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent data concerning in vitro studies of erythroid progenitors in polycythemia vera (PV) are reviewed. As shown by different laboratories, at least two populations of CFUE seem to coexist in the bone marrow of such patients: one exhibits normal in vitro behavior; the other, probably of clonal origin, is abnormally sensitive to erythropoietin. This abnormal population of CFUE is highly sensitive to trace amounts of erythropoietin and is probably responsible for the in vivo development of polycythemia despite a depressed level of erythropoietin. At the BFUE level, two populations also seem to coexist. However, the abnormal behavior of erythroid progenitors is probably not expressed at this early level of differentiation but only at the late CFUE level. This is in agreement with some of the data, which suggest that in the differentiation of erythroid progenitors into erythroblasts, erythropoietin is only needed at a level very close to CFUE.
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PMID:Erythroid progenitors in polycythemia vera. 718 45

Bioassays for human erythropoietin are cumbersome, time-consuming, and insensitive. The purification of human erythropoietin (EP) had provided small quantities of highly bioactive EP (approximately 70,000 U/mg) required for the development of an EP radioimmunoassay (RIA). The RIA for EP described in this investigation, can detect 5 mU/ml of EP in the assay tube; the serum concentration of EP in normal individuals ranged from less than 18 to 81 mU/ml with a mean value of 29 mU/ml. In contrast, nine patients with severe aplastic anemia had markedly elevated serum EP concentrations with a mean value of 3,487 mU/ml, range 984--6,434 mU/ml. In this RIA, patients with Polycythemia vera had consistently undetectable EP concentrations, less than 18 mU/ml. Eleven patients with chronic renal failure had a higher mean serum EP concentration (40.5 mU/ml) than normal individuals, but the range (less than 18-115 mU/ml) overlapped that of normals. By immunologic and gel chromatographic criteria, EP measured in serum was similar to standard urinary EP. The EP immunoassay that we have developed has sufficient sensitivity and specificity not only to quantitate the elevated serum EP levels found in aplastic anemia but also to discriminate decreased from normal serum concentrations of EP in most circumstances. This simple, reliable RIA has provided the necessary framework upon which to increase our understanding of the importance of EP in hematopoiesis.
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PMID:Serum concentrations of erythropoietin measured by radioimmunoassay in hematologic disorders and chronic renal failure. 727 May 48

The primary polycythemias result from malignant proliferation of myeloid stem-cell. Typically, an increase of red cell mass and a decrease of erythropoietin is found. In polycythemia vera, augmentation of PCV is frequently associated with elevation of WBC and platelets, as well as splenomegaly. The treatment consists of venosection and administration of P32 or cytostatics; all of which methods exhibit a specific risk. In secondary polycythemias, augmentation of red cell mass is consecutive to increased erythropoietin production; these hypererythropoietinemias may be induced by hypoxia or, rarely, may result from an inappropriate tumoral (malignant or benign) secretion. "Spurious" polycythemias are finally defined by the more or less normal red cell mass. They are divided into three groups: micropolycythemias, relative polycythemias and "spurious" chronic polycythemias. The latter are frequent and exhibit relatively important morbidity and mortality, and therefore the recently proposed new therapeutic approaches should be considered. Tobacco addiction appears to be one of the major causes of these "spurious" polycythemias.
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PMID:[The polycythemias]. 728 Jun 28

Pluripotent hemopoietic progenitors (CFU-GEMM) give rise to multilineage hemopoietic colonies in culture. We have examined the erythropoietin requirements of CFU-GEMM-derived erythroid progeny in patients with polycythemia vera (PV) and studied their proliferative activity by short-term exposure to 3HTdR. Mixed colonies with erythroid components were observed in all bone marrow and peripheral blood samples from patients with PV that were cultured without addition of exogenous erythropoietin. This response is consistent with previously reported growth patterns for CFU-E and BFU-E. The frequency of mixed colonies increased regularly when erythropoietin was added to the cultures. Short-term exposure of peripheral blood specimens to 3HTdR prior to plating yielded a reduction of the plating efficiency by 20%-70% when compared to cells that were not exposed to 3HTdR. The observation of cycling CFU-GEMM in PV contrasts with the usually quiescent behavior of CFU-GEMM in peripheral blood of normal individuals under steady-state conditions. These results support the view that the increased proliferative rate observed for CFU-GEMM may be responsible for the increased formation of blood cells in PV.
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PMID:Pluripotent hemopoietic progenitors (CFU-GEMM) in polycythemia vera: analysis of erythropoietin requirement and proliferative activity. 730 7

Mononuclear cells from the peripheral blood of normals and patients with terminal renal insufficiency on hemodialysis were set up in methylcellulose cultures with and without addition of sera of patients with polycythemia vera (pv). In renal patients we found more intensive stimulation of hematopoietic progenitor cells after addition of pv-sera than in normals. The findings suggest a hematopoietic factor in sera of pv which is not identical with erythropoietin.
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PMID:[Stimulation of hematopoietic stem cells with serum specimens of patients with polycythemia vera]. 731 24

Erythropoietin is a hormone produced by the kidneys and by certain extrarenal tissues and released into the circulation in response to tissue hypoxia. Its study has provided new information about oxygen transport and bone marrow stem cell function and its determination in plasma can give valuable diagnostic clues as to the etiology and pathogenesis of anemias and polycythemias. The various methods used for such measurements are discussed, and it is recommended that the in vivo bioassay in polycythemic mice be utilized until a workable radioimmune assay has been perfected. The results with the use of this in vivo bioassay to measure plasma erythropoietin in patients with uncomplicated anemia, aplastic anemia, anemia of renal disease, anemia of chronic inflammatory or neoplastic disorder polycythemia vera, and secondary polycythemia are charted and their diagnostic significance discussed.
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PMID:Plasma erythropoietin in health and disease. 739 90

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

Recombinant human erythropoietin (EPO) therapy in uremic patients raises the hematocrit (Hct) and increases physical exercise capacity (1,2) and quality of life (1). In general, partial correction of anemia to subnormal levels in uremic patients has proven to be safe with few serious adverse effects apart from hypertension (3). Ever since the advent of EPO the prospect of abuse of the hormone by sportsmen has been subject to scrutiny. Both maximal oxygen uptake and endurance capacity are increased after EPO treatment in healthy subjects (4). Moreover, EPO treatment in healthy subjects has been found to induce an accentuated blood pressure reaction after submaximal exercise (5). Previous studies have shown that extreme physical exertion can predispose to an increased intravascular coagulation (6). Moreover there is a significantly increased risk of thrombosis in patients with myeloproliferative disorders, particularly in polycythemia vera (7). An enhanced risk of cardiovascular events may therefore arise should sportsmen abuse EPO as a blood doping agent. The aim of this study was to examine the effects of an EPO-induced increase in Hct on the coagulation system in healthy subjects.
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PMID:Treatment with recombinant human erythropoietin induces a moderate rise in hematocrit and thrombin antithrombin in healthy subjects. 749 99

The in vivo effects of hydroxyurea (HU) on circulating erythroid (BFU-E) and granulocyte-macrophage progenitors (CFU-GM) in patients with polycythemia vera (PV) have been evaluated. HU induced a strong decrease of both BFU-E and CFU-GM in the first month of treatment. During the following 4 months of treatment the level of circulating progenitors remained at very low values, until the end of the period of observation. HU activity involved both erythroid and myeloid committed progenitors and both erythropoietin-stimulated (normal) and endogenous (derived from the abnormal PV clone) BFU-E.
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PMID:Circulating hematopoietic progenitor cells in polycythemia vera: the in vivo effect of hydroxyurea. 754 29

A 13 year old Thoroughbred gelding was presented with a history of a single episode of collapse during mild exercise. Clinical examination revealed a high packed cell volume (PCV) of 72%, a haemoglobin concentration of 24.9 g/l and 15.2 millions erythrocytes/microliters. Despite continuous intravenous infusion therapy with large volumes, the PCV never decreased to a physiological level. The animal showed a normal appetite and no signs of discomfort or syncope. Arterial blood gas values were in the normal range as well as the concentration of erythropoietin (measured by radioimmunoassay, RIA). A test for neoplasms (carcino-embryonic antigen, CEA) was negative. The liver enzymes of the animal were extremely elevated and a liver biopsy showed a severe fibrosis. Examination of sternal bone marrow aspirate revealed no abnormalities. Based on these findings, the presumptive diagnosis was "absolute polycythaemia". The animal was treated for 7 days with repeated phlebotomy. During this time, the PCV never decreased below 50%, despite no obvious signs of discomfort from the animal. Because of the poor prognosis based on the liver biopsy result, the animal was euthanized 11 days after hospitalization. Post mortem findings were: a granular cell myoblastoma with a diameter of approximately 5 cm in the lungs, severe fibrosis of the liver, mild acute tubular nephrosis in the kidneys, activation of the erythropoietic cells in the bone marrow and thrombosis of the abdominal aorta. The possibility of secondary polycythaemia due to the lung neoplasia was not entirely excluded, but considered to be unlikely. Therefore, the definite diagnosis was polycythemia vera.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Case report: polycythemia in a horse]. 756 45


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