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)

Polycythaemia vera (PV) patients' blood burst-forming units-erythroid (BFU-E) have an enhanced sensitivity to stem cell factor (SCF) compared to normal BFU-E. To characterize SCF receptors on erythroid progenitors from normal individuals and PV patients, we performed binding experiments using radioiodinated recombinant SCF (rSCF), day 1 BFU-E and day 8 erythroid colony-forming cells (ECFC), which are mostly colony-forming units-erythroid (CFU-E). 125I-rSCF binds to a single class of cell surface receptors (23,000/ECFC) at 0 degrees C with a high-binding affinity (Kd = 17 pM). Saturation occurred at 0.5 nM (10 ng/ml) which produces a nearly maximum biological effect. One half of the radiolabelled rSCF was internalized by the cells after 30 min at 37 degrees C. No significant differences in the receptor number, dissociation constant, or internalization rate were found between normal and PV ECFC. Autoradiographic analysis of 125I-rSCF binding to normal BFU-E and ECFC showed that no differences were present in either the percentage of positive cells or the number of radioactive grains/cell between the normal and PV erythroid progenitors. The enhanced sensitivity of PV BFU-E and CFU-E to SCF does not appear to be related to changes in SCF receptor number, binding affinity or internalization and the hypersensitivity of PV erythroid progenitors to SCF must reside in a further internal cellular abnormality.
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PMID:Polycythaemia vera. IV. Specific binding of stem cell factor to normal and polycythaemia vera highly purified erythroid progenitor cells. 752 30

We have previously shown that circulating progenitor cells in patients with polycythemia vera (PV) are hypersensitive to insulin-like growth factor I (IGF-I) with respect to erythroid burst formation in serum-free medium, and that this effect occurs through the IGF-I receptor. To investigate the molecular basis of this IGF-I hypersensitivity phenomenon, we examined tyrosine phosphorylation of the IGF-I receptor beta subunit in peripheral blood mononuclear cells (PBMNC) from eight PV patients and six normals. Cells were exposed to IGF-I at concentrations of 10(-8) and 10(-10) mol/L for 0, 1, 3, and 10 minutes, and then lysed. The IGF-I receptor beta subunit was immunoprecipitated, and the protein was resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotted with antiphosphotyrosine antibody (4G10). We found that, in the absence of exogenous IGF-I, there was a basal level of tyrosine phosphorylation of the IGF-I receptor beta subunit, and it was substantially greater in PV than in normal. At 10(-10) mol/L IGF-I in normals, no evidence of increased tyrosine phosphorylation was detected; however in PV, a pronounced increase in tyrosine phosphorylation was observed at both 10(-10) and 10(-8) mol/L IGF-I, and it occurred earlier and attained a higher level than in normal. In contrast, in PBMNC from three patients with erythrocytosis, no significant increase above normal was seen in either basal or induced tyrosine phosphorylation of the IGF-I receptor beta subunit. Thus, our findings show two distinctive features of the PV phenotype in PBMNC: (1) an increased basal tyrosine phosphorylation of the IGF-I receptor beta subunit, and (2) a hypersensitive and hyperresponsive receptor with respect to tyrosine phosphorylation. These features may influence the ability of the receptor to transmit a proliferative signal; thus, they may play a role in the pathogenesis of PV.
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PMID:Increased basal and induced tyrosine phosphorylation of the insulin-like growth factor I receptor beta subunit in circulating mononuclear cells of patients with polycythemia vera. 754

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

The effect of mast cell growth factor (MGF) was studied on erythropoietin (Epo)-dependent and Epo-independent ("spontaneous") erythroid colony formation in patients with polycythemia vera (PV). MGF stimulated both Epo-dependent and Epo-independent erythroid colony formation from PV peripheral blood progenitor cells in vitro at a dose similar to normal erythroid progenitor. In addition, evidence was obtained that the stimulating effect of MGF was a direct effect on the erythroid progenitor and independent of serum. Antibodies against interleukin-1 (IL-1), IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), and Epo could not abolish the enhancing effect of MGF. This was also supported by the finding that sorted CD34+ cells could be stimulated by MGF in the presence and absence of Epo. Finally, it was demonstrated that the spontaneous erythroid colony formation could not be ascribed to spontaneous release of MGF in the culture medium since anti-MGF did not affect the colony numbers. In conclusion, MGF has a direct stimulatory effect, independent of serum, on both Epo-dependent and Epo-independent erythroid colony formation in PV.
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PMID:Recombinant human mast cell growth factor supports erythroid colony formation in polycythemia vera in the presence and absence of erythropoietin and serum. 768 83

Interferon alpha (alpha-IFN) is increasingly used for the treatment of patients affected by polycythemia vera (PV). As prior studies are difficult to interpret in view of the lack of appropriate controls, we undertook a randomized comparison of lymphoblastoid alpha-IFN (alpha n-1 IFN) treatment against venesection treatment alone. In a crossover trial, we treated 22 PV patients alternatively for 5 months each with 3 MU/day sc of alpha n-1 IFN and phlebotomy alone. During IFN treatment, red blood cell count and hematocrit level were well controlled in both trial groups, reducing or eliminating the need for phlebotomy in all patients; furthermore, platelet number and white blood cell count declined during alpha-IFN therapy. In addition, the number of symptomatic patients was greatly reduced, and in six patients a reduction in splenic size was observed. Finally, the only patient with chromosomal abnormalities showed a complete cytogenetic conversion after 5 months of alpha-IFN therapy. Thus, for the first time, our results provide the unequivocal demonstration that alpha-IFN is superior to phlebotomy in controlling the pathologic expansion of erythroid elements and all the clinical aspects of this disease.
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PMID:A prospective comparison between treatment with phlebotomy alone and with interferon-alpha in patients with polycythemia vera. 801 66

A few simple, low-priced, outpatient investigations, including an upper abdominal ultrasonography, a measurement of the arterial oxygen saturation and, in some cases, a leukocyte alkaline phosphatase score (LAP) suffice to find out the etiology of an increased red cell mass in most patients. The diagnosis of polycythemia vera (PV) could be accepted in patients with an increased red cell mass if the spleen is enlarged and if the arterial oxygen saturation is normal, although the latter measurement may not be required in typical cases. If the spleen is not enlarged, the diagnosis of PV could be accepted if, in addition, the leukocyte or thrombocyte count is increased. An elevated LAP score also points to the diagnosis of PV, provided fever or inflammation are not present. If, at that stage, an etiologic diagnosis has not been made, smoker's polycythemia should be considered and excluded. The next step should include a serum erythropoietin assay and culture of erythroid stem cells before performing investigations aimed at ruling out the many conditions associated with secondary polycythemia.
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PMID:Biological and radiological investigations in patients with an increased red blood cell mass: Which are needed? Which are useful? which are unnecessary? 803 33

Erythroid progenitor cells isolated from patients with polycythemia vera (PV) proliferate and differentiate in methylcellulose in the absence of exogenous erythropoietin (EPO). To investigate the potential role of the erythropoietin receptor (EPO-R) in the pathogenesis of PV, we cultured bone marrow-derived or peripheral blood-derived erythroid progenitors in the presence of neutralizing monoclonal antibodies (MoAbs) specific for EPO or EPO-R. Mononuclear cells were obtained from 9 healthy adults and 9 PV patients by Ficoll-Hypaque gradients and cultured with or without EPO in methylcellulose for 12 days under standard or serum-free conditions. Neutralizing anti-EPO and anti-EPO-R MoAbs, added to cultures at day 0, caused dose-dependent growth inhibition of all normal burst-forming units-erythroid (BFU-E) derived from health adult controls. The MoAbs had no effect on the growth of nonerythroid progenitor cells under the same culture conditions. In contrast, neutralizing antibodies distinguished two classes of BFU-E derived from PV patients. Class I BFU-E from PV patients were EPO-dependent. These progenitors, like those derived from healthy adults, had normal EPO dose-dependent growth characteristics and showed a normal period of EPO requirement in vitro that extended 6 days after the initiation of culture. These results indicate that EPO exerts its critical effect early during erythroid differentiation; the addition of neutralizing antibodies to normal progenitors after 6 days had no effect on the subsequent size or maturation of the colonies. Class II BFU-E from PV patients were EPO-independent. They proliferated and differentiated even in the presence of high concentrations of neutralizing anti-EPO or anti-EPO-R MoAbs. We conclude that the class II BFU-E from PV patients are independent of free EPO.
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PMID:Anti-erythropoietin (EPO) receptor monoclonal antibodies distinguish EPO-dependent and EPO-independent erythroid progenitors in polycythemia vera. 808 Oct

Using a sequential double-immunostaining technique, a morphometric analysis was performed on routinely processed bone marrow trephines from 20 patients with secondary (reactive) polycythaemia and 28 patients with polycythaemia rubra vera to determine the proliferation capacity of erythropoiesis. Monoclonal antibodies PC10--anti-proliferating cell nuclear antigen (PCNA)--and Ret40f--anti-glycophorin C--were employed. For comparison with the PCNA-labelling index, in a pilot study, Ki-67 was additionally used on frozen-section material. In comparison with normal bone marrow (15 patients) morphometric and statistical evaluation revealed a numerical increase in erythroid precursors (pro-, erythro- and normoblasts) in secondary polycythaemia and to a pronounced degree in polycythaemia rubra vera. In comparison with secondary polycythaemia and the control group, in polycythaemia rubra vera there was a significant enhancement of proliferation according to PCNA-staining reactivity in all haematopoietic cell elements and particularly in the erythroid series. Evaluation of PCNA v. Ki-67 immunostaining disclosed only a slight difference, which could be mainly attributed to various modalities of antigen expression during the cell cycle. Our findings are in keeping with in vitro studies on cultured erythroid progenitor cells and, in problematic cases, may present a valuable aid in differentiation between reactive lesions and polycythaemia rubra vera.
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PMID:Proliferating cell nuclear antigen expression by erythroid precursors in normal bone marrow, in reactive lesions and in polycythaemia rubra vera. 810 13

A 42-year-old Caucasian male with sporadic primary polycythemia has been followed by us for 13 years. During the time of observation, his hemoglobin had been stable, and he has never had an elevated white count or platelet count or any other stigmata of polycythemia vera (PV). Both of his parents, his three children, and all siblings have been hematologically normal. The in vitro culture of erythroid progenitors revealed an absence of autonomous erythropoietin (Epo)-independent erythroid colonies but demonstrated a marked increase in the sensitivity of erythroid progenitors to Epo. We have undertaken a study designed to determine whether a mutation in the Epo receptor (Epo-R) gene could cause the polycythemia phenotype seen in either dominant or recessive primary polycythemia described by us and others, or in polycythemia vera. We have sequenced the cytoplasmic positive and negative regulatory domains of the Epo-R genomic DNA, and a transversion of C to T in nucleotide 6148 was found in one of the patient's chromosomes. This mutation is located in the negative regulatory domain and results in a change from proline to serine (P488S). We have subsequently analyzed more than 40 chromosomes from unrelated normal subjects, as well as autosomal dominant, recessive, and sporadic primary polycythemia and polycythemia vera subjects. In no instance was the same or any other mutation in the Epo-R found. To determine if this Epo-R mutation is a cause of increased sensitivity of erythroid progenitors to erythropoietin, Ba/F3 cells (interleukin-3-dependent murine lymphoid line) were transfected with normal and mutated Epo-R cDNA, rendering the transfected cells viable and able to proliferate in Epo. Transfectants with wild-type and mutant Epo-R cDNA exhibited no difference in the presence of Epo. More recently, we were able to obtain DNA from the seven family members of the propositus and found that the nonpolycythemic mother and one of the siblings have the same Epo-R mutation. We conclude that this first described mutation of Epo-R encountered in humans does not appear on its own to explain the polycythemia phenotype; however, the possibility that it may interact with some other acquired or congenital abnormality in generating the polycythemia phenotype cannot be excluded.
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PMID:Mutation in the negative regulatory element of the erythropoietin receptor gene in a case of sporadic primary polycythemia. 817 75

Increasing evidence for pathological erythroid clones and availability of additional diagnostic criteria suggest to reconsider the classification of polycythemia, with particular regard to the separation between primary proliferative polycythemia (PPP) or polycythemia vera, and other conditions in which the excessive red cell mass is not due to a myeloproliferative disorder. The characteristics of the abnormal erythropoietic clone in PPP are reviewed, with special reference to the in vitro growth of Epo-independent clones and the response to Epo and other growth factors. Traditional PPP diagnostic criteria are thus integrated with more recent parameters and the clinical features are considered; the main features of idiopathic erythrocytosis (IE) are also reviewed, as well as those of other forms, like familial, secondary and apparent polycythemia. It is pointed out that previously obscure forms are now being elucidated, with the decisive help from molecular biology investigations, allowing the discovery of genetic defects. It is thus becoming apparent that basic science acquisitions, as in the field of erythropoietic initiators (Epo receptor, GATA-1 transcription factor and so on) are eventually helping our understanding of clinical problems in this area, with relevant consequences on diagnosis and treatment of various forms of polycythemia.
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PMID:Polycythemia: from clones to clinic. 817 29


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