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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 23-year-old woman experienced six distinct episodes of severe combined neutropenia and thrombocytopenia. At least one of the episodes was accompanied by hemodialysis-requiring acute renal failure and fragmentation hemolysis (hemolytic uremic syndrome [HUS]). In retrospect, all episodes were probably associated with the ingestion of quinine. Quinine-dependent antibodies to platelets, neutrophils, T lymphocytes, and red blood cells (RBCs) were detected in the patient's serum. By a monoclonal antibody antigen capture assay, the patient's serum contained IgG antibodies, which in the presence, but not absence, of quinine reacted with platelet glycoprotein (GP) complexes Ib/IX and IIb/IIIa, but not Ia/IIa. By immunoprecipitation assay, the serum, after addition of quinine, reacted strongly with an 85-Kd neutrophil membrane protein and weakly with 130- and 60-Kd moieties. Serum adsorbed with RBCs in the presence of quinine continued to react with platelets and neutrophils, and serum that was absorbed with platelets continued to react with neutrophils and RBCs, indicating that the antigenic targets were different on platelets, neutrophils, and RBCs. Since platelets and endothelial cells share some antigens, we tested patient serum for antibodies to human umbilical vein endothelial cells (HUVEC); no quinine-dependent antibodies to HUVEC were detected. However, her quinine-dependent antibodies not only bound to platelets and neutrophils, but also activated neutrophils. Thus, the patient's serum with quinine aggregated neutrophils, but neither agent alone caused activation. Moreover, the patient's serum with quinine (but not without) augmented the adherence of neutrophils to HUVEC. Treatment of the patient's serum with staphylococcal protein A removed the quinine neutrophil aggregation cofactor, suggesting it was due to IgG. In both neutrophil aggregation and adherence assays, decomplementation of the patient's serum markedly blunted its effect. Furthermore, the patient's serum failed to aggregate formalin-inactivated neutrophils, suggesting neutrophil activation, probably by activated complement, was necessary for aggregation and adhesivity to endothelium. We conclude that our patient's neutropenia, thrombocytopenia, lymphopenia, and anemia were due to quinine-dependent antibodies, and that these antibodies recognized epitopes that were different in the three target cell populations. We further suggest that HUS was likely secondary to the activation and adhesion of neutrophils to endothelium.
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PMID:Characterization of multiple quinine-dependent antibodies in a patient with episodic hemolytic uremic syndrome and immune agranulocytosis. 161 Oct 88

The renal glycoprotein hormone erythropoietin is an essential growth factor for the erythrocytic progenitors in the bone marrow. Erythropoietin deficiency is the main cause of the anemia in chronic renal failure. Genetical engineering has made it possible to produce recombinant human erythropoietin (rhu-Epo) in CHO cell cultures as a pharmaceutical compound. Endogenous and recombinant erythropoietin are similar with respect to their biological and chemical properties (M(r) 30,400 Da, protein content 60%, 165 amino acids, 4 carbohydrate side chains). With few side-effects, rhu-Epo corrects the anemia of predialysis and dialysis renal failure patients. In addition, rhu-Epo treatment may reduce the need for blood transfusion in other types of anemias, including those of rheumatoid arthritis, AIDS, malignant diseases and major surgical procedures. However, rhu-Epo has not been approved as yet for treatment of non-renal anemias in Germany.
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PMID:[Chemical structure, biotechnical production and clinical use of recombinant erythropoietin]. 164 21

Erythropoietin, a glycoprotein produced by the kidneys in response to anemia and hypoxia, is a major growth factor for cells of the erythroid lineage. Erythropoietin interacts with high-affinity cell surface receptors (EpoR) present on developing progenitors and is required for their survival. Previously we characterized the gene for EpoR and demonstrated that its promoter acts in a cell-specific manner. Here we show that the hematopoietic-specific transcription factor GATA-1 is necessary, and indeed is sufficient as the sole cell-restricted regulator, for activation of the EpoR promoter in fibroblast transfection assays. Hence, GATA-1, which participates in transcriptional control of the majority of erythroid-expressed genes, also acts on the promoter of an essential lineage-restricted receptor (EpoR). This central contribution of GATA-1 to EpoR promoter function provides a mechanism whereby a cell-restricted regulator may ensure the viability and subsequent maturation of progenitor cells during hematopoietic differentiation.
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PMID:Activation of the erythropoietin receptor promoter by transcription factor GATA-1. 166 Jan 43

In various anaemias the values of 8 acute phase factors were determined simultaneously before and at the end of treatment: seromucoid, sialic acid, acid alpha 1-glycoprotein, alpha 1-antitrypsin, haptoglobin, ceruloplasmin, transferrin and fibrinogen. In iron-deficiency anaemia without coexistent inflammatory changes in organs the levels of 4 proteins--seromucoid, alpha 1-antitrypsin, ceruloplasmin and transferrin, were consistently raised. In iron-deficiency anemia with concomitant infection 4 proteins also were increased, but in place of alpha 1-antitrypsin the haptoglobin level was raised. In megaloblastic anaemia the ceruloplasmin level was increased, and in haemolytic anaemia one factor--sialic acid--was decreased. At the end of treatment the concentrations of certain proteins were changed depending on their specific role in various forms of anaemia and on various additional factors. In iron-deficiency anaemia without coexistent infection the concentration of seromucoid was decreased, and in this anaemia with coexistent infection alpha 1-antitrypsin, haptoglobin, and fibrinogen levels were raised, in haemolytic anaemia only fibrinogen was increased, and megaloblastic anaemia was associated with raised seromucoid level. The therapeutic result was good in all these anaemias with the exception of iron-deficiency anaemia associated with infection in which it was less propitious.
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PMID:[Acute phase factors in anemia]. 172 69

Erythropoietin is a glycoprotein hormone that plays a vital role in erythropoiesis. It is mainly produced in the fetal liver till the third trimester of pregnancy. At that point, the kidney interstitium takes over this function and becomes the main source of erythropoietin. Hypoxia stimulates erythropoietin production by a mechanism that may require a heme protein as a second messenger. Erythropoietin stimulates the maturation of erythroid precursors (colony-forming unit-erythroid and burst-forming unit-erythroid) via at least two types of cell surface receptors. The higher-affinity receptors appear to be more important in modulating the effects of erythropoietin in vivo. Changes in intracellular calcium may ultimately mediate the action of erythropoietin on erythroid precursors. A specific and sensitive radioimmunoassay is now available for accurately measuring erythropoietin levels. All forms of erythrocytosis except polycythemia vera are associated with elevated erythropoietin levels. Levels are also high in cord blood obtained following fetal asphyxia. Reduced levels are seen in patients with anemia due to renal diseases. The response of erythropoietin to the degree of anemia appears to be attenuated in patients with cancer, chronic diseases, and human immunodeficiency virus (HIV) infection. Erythropoietin has been successfully used for treating patients with anemia due to renal failure. Its use has also been approved for the treatment of anemia patients receiving zidovudine for HIV infection. Encouraging results have been observed when erythropoietin was used to treat anemia due to rheumatoid arthritis, hematological malignancies, and prematurity. It has also been used to increase the yield of autologous blood collected prior to an elective surgical procedure. However, it has not proved to be useful in sickle cell anemia and myelodysplastic syndromes.
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PMID:Erythropoietin. Biology and clinical applications. 178 66

Hematological disorders are commonly complicated by anemia, and the symptoms of red cell deficiency adversely affect the quality of life. Erythropoietin is a glycoprotein which controls red blood cell production. Recombinant human erythropoietin, 50 U/kg/day, was given subcutaneously to 16 patients with myelodysplastic syndrome and anemia. All but one patient was transfusion dependent. Diverse pretreatment endogenous serum erythropoietin levels were noted and ranged from 17 to 3616 IU/l. Two patients (12.5%) demonstrated an improvement in hemoglobin levels obviating the need for transfusions. Their responses lasted 5+ and 7 months with maintenance erythropoietin treatment. The responders had endogenous serum erythropoietin levels of 44 and 170, respectively. Treatment was generally tolerated without constitutional side-effects. However, three patients developed thrombocytopenia and one developed joint pain and leukocytosis on treatment. Overall, six patients showed changes in non-erythroid cells: two patients had an increase in platelet counts; three patients, a decrease in platelet counts; and one patient, an increase in white blood cell counts. Most of these changes reversed rapidly once erythropoietin was stopped. It is concluded that (a) serum erythropoietin levels are extremely variable in anemia patients with myelodysplastic syndrome, (b) only a minority of patients benefit from treatment with recombinant human erythropoietin, and (c) erythropoietin can affect cells of the myeloid and megakaryocytic lineage in a small proportion of patients.
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PMID:Erythropoietin treatment in patients with myelodysplastic syndrome and anemia. 196 Oct 41

The paraneoplastic syndrome (PNS) is an association of symptoms and signs not directly related to the site or local manifestations of a malignant tumor or its metastases. Hematologic abnormalities as PNS include erythrocytosis, anemia, neutrophilia, neutropenia, eosinophilia, thrombocytosis, thrombocytopenia, venous thromboembolism and disseminated intravascular coagulation (DIC). These abnormalities are, by and large, due to the production of biologically active growth factors, hormones or as yet unidentified "humors" by the tumor. As our understanding of growth factors controlling hematopoiesis has increased in recent years, the biologic basis of hematologic PNS are better understood. For instance, tumor-associated neutrophilia is now known to be caused by the production of G-CSF by the tumor. The mechanism by which tumor causes thromboembolism have also been extensively investigated. Cancer cells induce platelet aggregation both in vitro and in vivo. Platelet aggregating material has been isolated and partially characterized from tumor cells. The involvement of platelet glycoprotein II b/IIIa in the tumor-platelet interaction has also been shown. Malignant cells contain a unique procoagulant, cancer procoagulant A, that directly activates factor X. Together with tissue factor, this procoagulant appears to have been contribute to a high incidence of thromboembolism in cancer patients. Better understanding of hematologic PNS is important for clinical care of the patients with cancer.
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PMID:[Paraneoplastic syndrome hematologic abnormalities]. 200 36

Epoetin (recombinant human erythropoietin, EPO) is of proven benefit in the treatment of renal anaemia, and preliminary reports suggest that it may have a role in the management of other anaemic conditions. Pharmacokinetic and therapeutic studies have examined the use of epoetin administered intravenously, intraperitoneally and subcutaneously, and there is accumulating evidence that the last route has several advantages. After intravenous administration, epoetin is distributed in a volume comparable to the plasma volume, and plasma concentrations decay monoexponentially with a half-life of between 4 and 12 hours. Administration of epoetin in peritoneal dialysis fluid results in detectable concentrations in the bloodstream after 1 to 2 hours, and peak concentrations of the order of 2 to 4% of those obtained with the same intravenous dose are found after approximately 12 hours. The bioavailability of epoetin administered intraperitoneally in dialysis fluid is about 3 to 8%, but this may be increased by injecting the drug into a dry peritoneal cavity. Subcutaneous administration results in peak concentrations at about 18 hours which are 5 to 10% of those found after the same intravenous dose. The bioavailability of subcutaneous epoetin is about 20 to 30% and detectable serum concentrations are still present 4 days after administration, in contrast to intravenous administration after which concentrations have returned to baseline within 2 to 3 days. Remarkably little is known about the metabolic fate of either erythropoietin or epoetin. In addition, there is much controversy surrounding the relative roles of the kidney and liver in the catabolism of epoetin. About 3 to 10% of epoetin is excreted unchanged in the urine. In common with other glycoproteins, the carbohydrate residues which constitute 40% of its molecular size are essential for maintaining the stability of epoetin in circulation. Desialated epoetin, although biologically active in vitro, is cleared very rapidly from plasma with resultant loss of activity. Further work is required, however, in identifying the pathways of metabolism and elimination of this glycoprotein hormone.
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PMID:Clinical pharmacokinetics of epoetin (recombinant human erythropoietin). 202 9

Erythropoietin is a glycoprotein hormone of primarily renal origin that promotes the proliferation and differentiation of erythrocyte precursors. Technological advances have resulted in the production of recombinant hormone suitable for therapeutic use and have permitted significant progress in the characterization of the physiologic and pathologic processes involved in endogenous erythropoietin production. In situ hybridization studies have shown that erythropoietin production in the hypoxic kidney occurs primarily in peritubular cells, most likely endothelial cells. In renal carcinoma associated with polycythemia, however, erythropoietin mRNA has been detected in the tumor cells, which are tubular in origin. New information regarding the biochemistry of the erythropoietin receptor has been gleaned subsequent to the cloning of the gene encoding the receptor; however, much remains to be learned about the interaction of the hormone with its target cells. With regard to clinical experience, recombinant erythropoietin has been shown to correct the anemia associated with chronic renal failure in patients requiring dialysis, having a significant beneficial effect on the overall physical and psychological state of the patient; the major adverse effect of such treatment is hypertension. The role of recombinant erythropoietin in predialysis patients, patients with anemias of other origin, and other clinical settings is currently being evaluated.
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PMID:Erythropoietin: physiology and clinical experience. 219 61

The variant surface glycoprotein (VSG) of trypanosomes is attached to the cell surface by means of a phosphatidylinositol-containing glycolipid membrane anchor. The studies presented in this paper support the hypothesis that the transfer of VSG from trypanosomes to erythrocytes could lead to one of the pathological features associated with trypanosome infection--i.e., anemia. Migration of trypanosome VSG from live trypanosomes to target cells (sheep erythrocytes) could be shown by preincubating erythrocytes with trypanosomes and subsequently testing the washed erythrocytes for insertion of VSG by their susceptibility to lysis by complement in the presence of an anti-VSG antibody. Complement-mediated lysis was found to depend on the strain-specific anti-VSG antibody used. Extent of erythrocyte lysis increased with time of cell exposure to trypanosomes and with trypanosome concentration. No erythrocyte lysis was observed when trypanosomes were preincubated with anti-VSG antibody before adding erythrocytes. Purified membrane-form VSG (which retains the glycolipid anchor), but not soluble VSG (which no longer has the terminal diacylglycerol moiety), could sensitize erythrocytes to anti-VSG antibody-mediated complement lysis. The intermembrane transfer of VSG from trypanosomes to cells of the infected host could provide a molecular mechanism for the pathogenesis of trypanosomiasis.
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PMID:Trypanosome variant surface glycoprotein transfer to target membranes: a model for the pathogenesis of trypanosomiasis. 230 May 63


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