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

Polycythemia vera (PV) represents an apparent monoclonal stem cell proliferation with a frequent transition to full neoplastic behavior. Up to 26% of untreated PV patients can be expected to have some chromosome abnormalities in the marrow at the time of diagnosis, and 10--15% have an abnormal cell line or clone. Both structural and numerical aberrations occur. Aneuploidy is the most common type of chromosome abnormality, however, with hyperdiploid clones occurring more frequently than hypodiploid clones. Chromosomes 1, 8, 9 and 20 are involved in a non-random pattern, and aberrations of all the F group, or at least the No. 20 chromosome seem to be associated to some extent with diseases involving erythroid hyperplasia. Leukemia develops in a certain percentage of patients regardless of the type of treatment they have received, but the relationship, if any, between the chromosome abnormalities and the development of leukemia is still uncertain. The abnormal clones that occur in PV appear to be quite stable and there is no indication at this time that they correlate with a prognosis of leukemic transformation.
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PMID:Chromosome studies in polycythemia vera. 10 10

Peripheral blood mononuclear cells from patients with polycythemia vera or myelofibrosis with myeloid metaplasia were studied for their erythroid colony growth characteristics in plasma clot cultures. In both diseases, erythroid colonies formed early in culture in the absence of added erythropoietin (endogenous colonies). In no instance did early, endogenous colony formation occur with peripheral blood cells from normals or patients with secondary polycythemia. A normal response to erythropoietin was observed with both control and patients' peripheral blood cells. Spleen mononuclear cells obtained from one patient with myelofibrosis also produced endogenous colonies and showed a response to erythropoietin. This study suggests that culture of peripheral blood mononuclear cells might serve as a useful tool in discriminating polycythemia vera from secondary polycythemia.
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PMID:Endogenous erythroid colony formation by peripheral blood mononuclear cells from patients with myelofibrosis and polycythemia vera. 11 8

A 10-year-old boy, who had been in an uninterrupted remission of acute lymphocytic leukemia (ALL) for six years, developed polycythemia vera (PV). One and a half months after detection of PV, he was found to have active leukemia. Both the polycythemia and leukemia receded with anti-leukemia therapy. Three possible explanations for the development of PV in a child with ALL are discussed: 1) PV was a part of his original ALL and recurred whtn patient relapsed. The PV phase was detected only during relapse because the patient was under close observation. 2) PV was a second neoplasm independent of ALL. 3) PV was part of a second leukemia which was different from the original leukemia; this new ALL was derived from a pluripotential cell line involving both erythroid and lymphoid elements. A precedent for this explanation has been observed in chronic myelogenous leukemia.
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PMID:Polycythemia vera in a child with acute lymphocytic leukemia. 28 32

In vitro studies using the plasma clot culture system have been performed in order to compare the red cell pregenitors able to rise to erythrocytic colonies in 7 days (CFUE) in the bone marrow of polycythemia vera (PV), secondary polycythemias and normal subjects. In PV but never in normal individuals or secondary polycythemias, the bone marrow cells producing erythroid colonies without addition of erythropoietin were found. The erythropoietin dode response curves in PV is biphasic with a plateau up to a concentration of erythropoietin of 0.02-0.05 i.U./ml followed by a near normal response to erythropoietin at higher doses. Thus our results demonstrate that two populations of erythroid stem cells coexist in PV, one being abnormally sensitive to (or independant of) erythropoietin, the other normally responding to erythropoietin. After remission induced by P32 treatment, the abnormal population can disappear but the prognostic significance of this disappearance is uncertain. On the whole these results are in agreement with those of others laboratories using the plasma clot culture system. The reasons of the disagreement with the data published using the methylcellulose technic of culture are discussed.
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PMID:[In vitro study of erythroblast precursors in Vasquez disease (polycythemia vera). Arguments in favor of a double population of erythroblastic stem cells in the bone marrow]. 44 Sep 61

Fetal hemoglobin was studied in 50 unselected patients with polycythemia vera with chemical determinations of Hb F and measurements of F-cell levels using fluorescent anti-Hb F antibodies. Although in the majority of the patients Hb F production did not differ from that in normal controls, in 20% of the patients F-cell values were above the normal range. There was no correlation between F-cell values and duration of disease, treatment modality, presence of myelofibrosis, or hematologic parameters at the time of study. In 5 of 50 patients 30%--45% of the erythrocytes contained Hb F; such striking elevations of F cells may reflect a distorted differentiation of erythroid precursor cells in certain patients with this disorder.
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PMID:Fetal hemoglobin in polycythemia vera: cellular distribution in 50 unselected patients. 44 54

We investigated the pathogenesis of isolated erythrocytosis of 14 yr duration in a 28-yr-old man. The increase in red cell mass was attributed to increased erythropoietin production. An extensive search for recognized causes of secondary erythrocytosis was unrevealing. Family members were found to be hematologically normal. After reduction of the circulating red cell mass by 20%, erythropoietin activity nearly quadrupled, thus suggesting a normal erythropoietin response to phlebotomy. When bone marrow cells of the patient were cultured in plasma clots in the absence of added erythropoietin, endogenous erythroid colony formation was observed, a pattern previously believed to be specific for polycythemia vera bone marrow cells. Our observations suggest that the erythrocytosis in this individual is best explained by an abnormal "servoregulatory" mechanism of erythropoietin production. In addition, this is the first instance in which the rule that endogenous erythroid colony formation is correlated with the diagnosis of polycythemia vera has not held.
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PMID:Erythropoietin-dependent primary pure erythrocytosis. 44 59

In previous studies of two patients with polycythemia vera (PV) and heterozygous at the X-linked locus for glucose-6-phosphate dehydrogenase (G-6-PD), only type A isoenzyme was found in non-lymphoid hematopoietic cells. However, some granulocytic and erythrocytic colonies grown in vitro had type B G-6-PD and therefore arose from presumably normal progenitors. In this study we exposed marrow cells from these same two patients to high-specific activity tritiated thymidine (3HTdR) before culture to kill cells actively synthesizing DNA. Individual granulocytic colonies were plucked and tested for G-6-PD after 14 d of culture. The frequency of type B colonies rose after exposure to 3HTdR from 8/101 to 11/36 in patient 1 and from 0/32 to 6/31 in patient 2 (P less than 0.003). No increase in the frequency of normal erythroid bursts after 3HTdR exposure was seen, implying that in PV, early granulopoiesis, and erythropoiesis are regulated differently. The results demonstrated that only type A granulocytic colonies, arising from the abnormal clone, were removed by the 3HTdR. In addition, for patient 2, statistical analysis indicated there was an absolute increase in normal granulocytic colonies detected in culture. Thus, PV clonal colony-forming units in culture (CFU-C) cycle more rapidly than do normal CFU-C and may suppress proliferation of normal CFU-C in vitro.
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PMID:Polycythemia vera. Increased expression of normal committed granulocytic stem cells in vitro after exposure of marrow to tritiated thymidine. 50 Aug 13

A patient with classical polycythemia vera (PV) was found to have an inappropriately elevated serum erythropoietin (Ep) level. Investigations did not reveal any lesion or blood abnormality known to be associated with excessive Ep production and erythrocytosis. Sudden withdrawal of blood to reduce the Hb and Hct from 18.5 gm% and 56% to 13.6 gm% and 41.5%, respectively, resulted in an increment of serum Ep to abnormal level. With iron treatment there was a brisk return of Hb and Hct to prebleeding levels which was associated with reduction in the serum Ep. The inverse relationship between the Ep and Hb or Hct is inconsistent with the presence of excessive Ep-producing lesion. These results suggested that the threshold for Ep secretion from normal Ep-secreting tissue to Hb and Hct levels is set at an abnormal level. This patient's marrow cells when cultured in vitro in the absence of Ep, unlike other PV patients' (except one) marrow cells, did not grow erythroid colonies. In the presence of Ep, however, the colonies comparable to those formed from normal marrow cultures were obtained. These results suggested that his marrow erythropoietic cells were neither Ep independent nor Ep-hyperresponsive, as has been suggested by some investigators for erythropoiesis in PV. This patient presents phenomena that hitherto have not been reported.
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PMID:Inappropriate erythropoietin secretion in polycythemia vera. 60 35

Bone marrow cells from two glucose-6-phosphate dehydrogenase (G-6-PD) heterozygotes with polycythemia vera were cultured to determine whether progenitors which wre not of the polycythemia vera clone were present, and, if present, which cell lines contributed to the increase in erythroid colonies observed in response to added erythropoietin (ESF). To accomplish this, the G-6-PD isoenzyme activity of individual erythroid colonies was determined. All of the erythroid colonies analyzed in cultures without added ESF, contained the G-6-PD isoenzyme type characteristic of the abnormal clone. With higher ESF concentrations in the culture, however, there was an increase in the colonies that were not of the polycythemia vera clone. Analysis of the ratio of the various types of colonies indicated that normal and polycythemia vera cells are capable of responding to ESF in vitro. In selected patients, this technique permits analysis of the ratios of normal to abnormal cells during the course of the disease, in response to therapy and during late complications, such as myelofibrosis or leukemic transformation.
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PMID:Polycythemia vera. The in vitro response of normal and abnormal stem cell lines to erythropoietin. 65 76

In vitro studies using the plasma clot culture system have been performed in order to compare the red cell pregenitors able to rise to erythrocytic colonies in 7 days (CFUE) in the bone marrow of polycythemia vera (PV), secondary polycythemias and normal subjects. In PV but never in normal individuals or secondary polycythemias, the bone marrow cells producing erythroid colonies without addition of erythropoietin were found. The erythropoietin dose response curves in PV is biphasic with a plateau up to a concentration of erythropoietin of 0.02--0.05 i.U./ml followed by a near normal response to erythropoietin at higher doses. Thus our results demonstrate that two populations of erythroid stem cells coexist in PV, one being abnormally sensitive to (or independent of) erythropoietin, the other normally responding to erythropoietin. After remission induced by P32 treatment, the abnormal population can disappear but the prognostic significance of this disappearance is uncertain. In the whole these results are in agreement with those of others laboratories using the plasma clot culture system. The reasons of the disagreement with the data published using the methylcellulose technic of culture are discussed.
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PMID:[In vitro study of erythroid precursors in Vaquez' disease (polycythemia vera). Evidence supporting 2 populations of erythroid stem cells in the bone marrow]. 75 50


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