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)

Polycythemia vera (PV) is a clonal hematologic disease characterized by hyperplasia of the three major bone marrow lineages. PV erythroid progenitor cells display hypersensitivity to several growth factors, which might be caused by an abnormality of tyrosine phosphorylation. In the present study, we have investigated protein tyrosine phosphatase (PTP) activity in highly purified erythroid progenitor cells and found that the total PTP activity in the PV cells was twofold to threefold higher than that in normal cells. Protein separation on anion-exchange and gel-filtration columns showed that the increased activity was due to a major PTP eluted at approximately 170 kD. This enzyme was sensitive to PTP inhibitors and it did not cross-react with antibodies to SHP-1, SHP-2, or CD45. Subcellular fractionation showed that the PTP localized with the membrane fraction, where its activity was increased by threefold in PV erythroid progenitors when compared with normal cells. As the erythroid progenitors progressively matured, activity of the PTP declined rapidly in the normal cells but at a much slower rate in the PV cells. These studies suggest that a potentially novel membrane or membrane-associated PTP, representing a major PTP activity, may have an important role in proliferation and/or survival of human erythroid progenitors and that its hyperactivation in PV erythroid progenitors might be responsible for the increased erythropoiesis in PV patients.
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PMID:Identification of increased protein tyrosine phosphatase activity in polycythemia vera erythroid progenitor cells. 922 65

In order to determine the relationship between bone marrow (bm) endosteal cells (EDC) and hemopoietic progenitors, we have analyzed the immunophenotype of EDC using various antibodies (Ab) against mesenchymal antigens. The Ab were applied on paraffin sections of normal bm (iliac crest, n=17; talus, n=1; phalanx, n=1), myeloregenerative bm (after chemotherapy), and hematologic disorders (acute myeloid leukemia (AML), n=8; chronic myeloid leukemia (CML), n=6; myelodysplastic syndromes (MDS), n=14; severe aplastic anemia (SAA), n=4; essential thrombocythemia (ET), n=2; idiopathic (primary) osteomyelo-fibrosis (IMF), n=1; polycythemia vera (PV), n=1). In normal bm, EDC were found to react with Ab against vimentin, tenascin, alpha-smooth muscle actin, osteocalcin, CD51, and CD56, but did not react with Ab against CD3, CD15, CD20, CD34, CD45, CD68, or CD117. An identical phenotype of EDC was found in AML, MDS, SAA, ET, IMF, PV, myeloregenerative bm, and peripheral bones lacking active hemopoiesis (talus, phalanx). In patients with CML, EDC reacted with Ab to CD51, but did not react with Ab to CD56. Based on their unique antigen profile, EDC were enriched from normal bm by enzyme digestion and cell sorting. However, these enriched cells (CD56+, CD45-, CD34-) did not give rise to hemopoietic cells under the culture conditions used, i.e. in the presence of the growth factors IGF-1, bFGF, SCF, IL-3, and GM-CSF Together, our data do not support the hypothesis that EDC are totipotent mesenchymal progenitors giving rise to hemopoietic cells.
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PMID:Immunophenotypic characterization of human bone marrow endosteal cells. 1039 6

Polycythemia vera (PV) is a myeloproliferative disorder arising in a multipotent hematopoietic stem cell. The pathogenesis of PV remains poorly understood; however, the biologic hallmark of this disease is the presence of erythropoietin (Epo)-independent colony formation (endogenous erythroid colony [EEC]) and cytokine hypersensitivity. We have developed a simple liquid culture from CD34+ cells to study PV erythroid differentiation. PV erythroid differentiation was characterized in this culture system by two types of abnormalities: 1) an increased proliferation of progenitors in response to cytokines, associated with strict cytokine dependency for preventing apoptosis; and 2) Epo-independent terminal erythroid differentiation in the presence of stem cell factor and interleukin-3 as evidenced by the acquisition of glycophorin A. The level of Epo-independent terminal differentiation correlates in PV patients with the number of EEC. Epo-independent terminal differentiation as well as normal Epo-induced differentiation were repressed by inhibitors of JAK2 (AG490), PI3K (LY294002), and the Src family kinases (PP2). In contrast, an inhibitor of the ERK/MAP kinase pathway (PD98059) had no effect on Epo-independent terminal differentiation. These signaling abnormalities were not mediated by a decreased expression or activity of the membrane tyrosine phosphatase CD45, which dephosphorylates JAK2 and Src family kinases. This study demonstrates that early steps of PV erythroid differentiation are strictly cytokine dependent. In contrast, late erythroid differentiation is an Epo-independent phenomenon that is mediated by signaling pathways identical to those in Epo-induced differentiation.
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PMID:Multiple signaling pathways are involved in erythropoietin-independent differentiation of erythroid progenitors in polycythemia vera. 1510 79

Acute erythroid leukemia in children is very rare. Here is a case of erythroleukemia in a child of age 1.5 years, which was diagnosed on peripheral smear, bone marrow examination, cytochemistry but was confirmed on immunophenotyping. CD45 versus side scatter demonstrated blast population (29%) expressing CD45 of variable intensity (dim to negative). The myeloid nature of blast population showed bright expression of cytoplasmic myeloperoxidase (MPO), heterogenous positivity of CD117 and dim expression of CD13, CD33. These blasts also showed bright positivity for CD71 which showed erythroid nature of blasts. Flow cytometry can be comprehensive enough to completely subtype cases of leukemias/myelodysplastic syndromes, polycythemia rubra vera, non-neoplastic conditions like reactive erythroid hyperplasia following immunosuppressive therapy or viral infections or nutritional deficiencies, unlyzed RBCs or thrombocytosis which may mimic acute erythroid leukemia on flow cytometry.
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PMID:Childhood acute erythroleukemia diagnosis by flow cytometry. 2139 10

Acute myeloid leukemia (AML) is the most common leukemia in adults. In rare cases, bone marrow necrosis (BMN) and osteolytic lesions are presenting features of AML. The following case describes a patient with known polycythemia vera (PV) that presented with signs of multiple myeloma, including hypercalcemia, anemia, and lytic lesions of the thoracic spine and skull. Laboratory workup was not indicative of myeloma. A bone marrow biopsy was performed, which revealed extensive BMN and initial pathology was consistent with metastatic carcinoma. However, no immunohistochemical stains could be performed due to the extent of BMN; a repeat biopsy was therefore performed. Flow cytometry and CD45 staining were consistent with PV that had transformed to AML. Due to the patient's comorbidities, she was a poor candidate for stem cell transplant and did not wish to pursue chemotherapy. Ultimately, she pursued hospice care. Based on our literature review, both BMN and osteolytic lesions are rare manifestations of AML and have not been reported to occur simultaneously. These findings can lead to a diagnostic dilemma and suspicion of other malignancies. This case demonstrates that AML should remain in the differential diagnosis in those patients who present with BMN and osteolytic lesions.
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PMID:Extensive Bone Marrow Necrosis and Osteolytic Lesions in a Case of Acute Myeloid Leukemia Transformed from Polycythemia Vera. 2743 18