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Query: UMLS:C0035078 (renal failure)
 31,970 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of recombinant human erythropoietin (rHuEpo) on megakaryopoiesis remains controversial. Treatment with rHuEpo in renal failure patients has been associated with a slight elevation of platelet counts. In animal studies, high doses of rHuEpo produced an increase of platelet counts followed by a gradual return to normal after 7 to 15 days or even a substantial degree of thrombocytopenia. However, because iron deficiency is also known to be associated with thrombocytosis, (functional) iron deficiency during rHuEpo could be contributing to these observations. We investigated the impact of iron supply on changes in platelet counts induced by rHuEpo. Rats were either fed normal food (normal rats) or received 1% carbonyl iron for 2 weeks or 3 months, as well as during the experiment, to achieve iron supplementation or overload, respectively. Rats of all three categories then received daily intravenous injections of rHuEpo (10, 50, or 150 U) or normal saline (0 U) for 20 days. With 0 to 10 U rHuEpo, platelets remained stable. In normal rats receiving 50 to 150 U rHuEpo, platelets increased to 120% to 140% of baseline at 4 to 12 days to level off at 120% at 16 to 20 days. This response was less sustained in splenectomized animals. Iron-supplemented rats receiving 50 to 150 U rHuEpo also increased platelets initially, but the peak was at day 4, followed by a gradual return to baseline and even a moderate thrombocytopenia later on. Iron-overloaded rats receiving 50 to 150 U rHuEpo also had increased platelets at day 4, but the duration of platelet increase was shorter, and they experienced a more pronounced degree of thrombocytopenia in proportion to the dose of rHuEpo. Because the early elevation of platelets was of larger magnitude than hematocrit changes, it is unlikely that it could be accounted for by shrinkage of plasma volume. Because it was observed in all three iron conditions, there appears to be some direct positive effect of rHuEpo on platelet production. However, after this transient effect, expanded erythropoiesis appears to exert a negative impact upon platelet production. Secondary thrombocytopenia was not related to splenic pooling, and its very slow correction after cessation of rHuEpo therapy is not compatible with changes in platelet survival. Rather, it is consistent with stem cell competition between erythroid and megakaryocytic development. However, this secondary thrombocytopenia is masked by (functional) iron deficiency in rats not receiving an adequate iron supply from food or stores.
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PMID:The effect of recombinant human erythropoietin on platelet counts is strongly modulated by the adequacy of iron supply. 1023 80

Erythropoietin (Epo) controls the proliferation, differentiation and survival of the erythroid progenitors. Epo exerts its effects by binding to a cell surface receptor. The Epo receptor includes a p66 chain, which is dimerized upon Epo activation, and two accessory proteins, which have been defined by cross-linking. Epo binding induces stimulation of the Jak2 tyrosine kinase. Jak2 activation leads to the tyrosine phosphorylation of several proteins, including the Epo receptor itself. Different intracellular pathways are activated: Ras/MAP kinase, phosphatidylinositol 3-kinase and STAT transcription factors. However, the exact mechanisms by which the proliferation and/or differentiation of erythroid cells are regulated after Epo stimulation are not known. Target disruption of both Epo and Epo receptors showed that Epo is not involved in the commitment of the erythroid lineage; it seems to act mainly as a survival factor. Epo is synthesized largely by the kidney and the liver, and sequences required for tissue-specific expression have been localized in the Epo gene. A 3' enhancer is responsible for hypoxia-inducible Epo gene expression. Hypoxia-induced factor-1 (HIF-1) protein binds to this enhancer. In addition to anaemia of renal failure, the indication for treatment with epoetin has been extended to the anaemia of chronic diseases.
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PMID:The molecular biology of erythropoietin. 1033 64

Cancer-related anaemia has a number of causes, not least the underlying malignancy itself which plays a role in suppressing erythropoiesis. Anaemia is often exacerbated by cancer treatments, in particular routinely used cytotoxic chemotherapy. Chronic anaemia of cancer is often characterized by inappropriately low levels of endogenous erythropoietin for the degree of anaemia, and manifests clinically with generalized hypoxia and resultant severe fatigue. Epoetin alfa is one recombinant form of erythropoietin, the primary human growth factor responsible for promoting proliferation and survival of erythroid progenitor cells. Epoetin alfa has been widely studied for the treatment of anaemia associated with renal failure and is now recognized as having significant potential in the management of cancer-related anaemia. Studies suggest that epoetin alfa is an effective treatment in a proportion of cancer patients with symptomatic anaemia. It also appears useful for the prevention of chemotherapy-induced anaemia. Studies in a number of different cancer settings have shown that epoetin alfa significantly increases haemoglobin and haematocrit, reduces transfusion requirements and improves quality of life for the patient.
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PMID:Epoetin in cancer-related anaemia. 1033 73

Increasing use of maintenance parenteral iron in the erythropoietin (EPO) era has been accompanied by growing concern about iron overload. This article attempts to put the issue of iron overload in hemodialysis patients into perspective. The condition is less common in all dialysis patients today than it was in the pre-EPO era, since fewer patients are being transfused and EPO therapy shifts iron into erythroid cells. Patients with end stage renal disease (ESRD) are less likely than patients with hemochromatosis to develop iron-induced organ dysfunction. Diagnosis of iron overload is best accomplished through liver biopsy. Clinically significant iron overload, which rarely occurs if ESRD patients are properly managed, can be treated in most EPO-treated renal failure patients by simply withholding parenteral iron therapy.
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PMID:Iron overload in the erythropoietin era. 1111 50

In an attempt to add to existing sparse literature on the haematological profile in chronic renal failure (CFR) in Nigeria, we have undertaken a comprehensive haematological sturdy of 39 patients (male 27, female 12) age range 11-56 yr., (mean 28.8 +/- 11.8) who had established pre-dialytic CFR. The mean haematocrit was 24.1 +/- 6.7% (range 12-40%). Severe anaemia was found in seven (18%), mild to moderate anaemia in 27 (69%) whilst five patients were not anaemic. Haematocrit correlated inversely with the degree of renal failure as assessed by serum creatinine (r = -0.35, P < 0.05). Red cell morphology was variable but the majority of patients showed a normocytic, normochromic blood film. The reticulocyte counts/indices were low. The mean total white cell count was generally within normal limits, ranging from (2 to 10.5 x 10(9)/l), with a mean of 5.3 +/- 2.1 x 10(9)/l and striking eosinophilia in 5 patients. Platelet count ranged between 82 and 350 x 10(9)/l (mean 156.5 +/- 65.7 x 10(9)/l) with only 3 patients having a relatively low count of < 100 x 10/l. Prolonged bleeding time (BT) > 9 minutes occurred in 13 (25.6%). There was no significant correlation between platelet count and bleeding time r = 0.21, P = 0.34. No significant correlation was observed between serum creatinine and bleeding time r = 0.09, P > 05. The bone marrow showed predominantly normocellular marrow but 7 patients had hypocellularity. Myeloid: Erythroid ratio ranged between 1:1 and 10:1, (mean 3:6:1) and correlated positively with serum creatinine values. (r = 0.37, P = 0.048). Bone marrow storage iron was absent in two and reduced in six patients. Severe anaemia is a common feature in Nigeria patients with CRF and it strongly associated with the severity of the renal failure. The low reticulocyte count and the tendency for erythroid hpoplasia to occur with increasing severity of renal failure would necessitate the use of erythropietin in our patients. The increased bleeding tendency in some of the patients calls for caution in surgical procedures in these patient.
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PMID:The haematological profile of Nigerians with chronic renal failure. 1137 60

The introduction of recombinant human erythropoietin (rh-Epo, epoetin) as a treatment for the anaemia of renal failure has transformed the management of this condition. Nevertheless, a significant number of patients fail to respond. There are many different possible causes of inadequate response to epoetin. Iron deficiency, whether absolute or functional, is considered to be the most important, and it is widely accepted that maintaining adequate iron levels reduces rh-Epo dosage requirement and improves efficacy in haemodialysis patients. Infection and inflammation have been shown to influence responsiveness to rh-Epo by disrupting iron metabolism and eliciting the release of cytokines that inhibit erythropoiesis. Another factor for consideration is severe hyperparathyroidism, which can lead to a reduced number of responsive erythroid progenitor cells. Inadequate dialysis can also negatively impact on rh-Epo therapy, and aluminium overload interferes with iron metabolism and reduces the efficacy of rh-Epo. Deficiencies in vitamin B(12), folic acid and potentially vitamin C can all reduce the efficacy of treatment with rh-Epo. Optimizing patient response to rh-Epo therapy, therefore, requires consideration of many factors, some well established and others that are more controversial, and the list continues to grow with the identification of new factors.
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PMID:Hyporesponsiveness to recombinant human erythropoietin. 1159 Feb 53

Several patients with clinical features of chronic myeloid leukemia (CML) have fusion of the TEL (ETV6) gene on 12p13 with ABL on 9q34 and express a chimeric Tel-Abl protein that contains the same portion of the Abl tyrosine kinase fused to Tel, an Ets family transcription factor, rather than Bcr. In a murine retroviral bone marrow transduction-transplantation model, a Tel (exon 1-5)-Abl fusion protein induced 2 distinct illnesses: a CML-like myeloproliferative disease very similar to that induced by Bcr-Abl but with increased latency and a novel syndrome characterized by small-bowel myeloid cell infiltration and necrosis, increased circulating endotoxin and tumor necrosis factor alpha levels, and fulminant hepatic and renal failure. Induction of both diseases required the Tel pointed homology oligomerization domain and Abl tyrosine kinase activity. Myeloid cells from mice with both diseases expressed Tel-Abl protein. CML-like disease induced by Tel-Abl and Bcr-Abl was polyclonal and originated from cells with multilineage (myeloid, erythroid, and B- and T-lymphoid) repopulating ability and the capacity to generate day-12 spleen colonies in secondary transplantations. In contrast to findings with Bcr-Abl, however, neither Tel-Abl-induced disease could be adoptively transferred to irradiated secondary recipient syngeneic mice. These results show that Tel-Abl has leukemogenic properties from distinct from those of Bcr-Abl and may act in a different bone marrow progenitor.
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PMID:The Tel-Abl (ETV6-Abl) tyrosine kinase, product of complex (9;12) translocations in human leukemia, induces distinct myeloproliferative disease in mice. 1203 90

In renal failure, severe anemia and associated fatigue, cognitive and sexual dysfunction have a significant impact on the patient's quality of life. Anemia has also been identified as an important etiologic factor in the development of left ventricular hypertrophy. The major cause of anemia in presence of a reduction of glomerular filtration rate is an inadequate production of a glycoprotein hormone, the erythropoietin (EPO). EPO is the primary regulator of the growth and survival of erythroid progenitor. The introduction of recombinant human erythropoietin (rHuEPO) has revolutionized the treatment of anemia in chronic renal failure. The vast majority of patients respond very well to treatment, but 5-10% of patients show some resistance to EPO, the most common cause of which is iron deficiency. Several studies are recently commenced to investigate the effects of preventing renal anemia ever developing. The target of hemoglobin concentration in pre-dialysis and dialysis patients are object of continuous re-examinations.
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PMID:Anemia in renal insufficiency. 1273 11

Chronic anemia of variable severity occurs in more than two-thirds of patients with multiple myeloma (MM) as a consequence of the B cell malignancy. Its pathogenesis is multifactorial. Besides the altered inflammatory cytokine network, other events are held responsible, namely persistent defect of erythropoietin due to the kidney failure, shortening of red cell survival, accumulation of the serum monoclonal component and platelet dysfunction. Our recent studies have demonstrated that excessive erythroblast apoptosis promoted by myeloma cells drives the appearance of anemia, in particular in patients with severely progressive disease. A number of clinical trials have provided evidence for the effectiveness of recombinant human erythropoietin (rHuEPO-alpha: epoetin alpha) in improving the deregulated erythropoiesis in MM, since it acts as a major erythroid growth factor by exerting a specific anti-apoptotic effect. In the majority of these studies, the long-term treatment of MM-associated anemia with rHuEPO-alpha induced a significant improvement of erythropoiesis, as shown by a stable increase of hemoglobin values (> or = 2g/dL) and reduction of transfusion requirements. In a recent trial which included both a double-blind and an open-label phase, we have documented that rHuEPO-alpha induces a stable improvement of anemia in more than 75% of patients and a significant decrease of fatigue, with an overall recovery of the quality of life. Patients receiving a placebo also achieved similar results in the open-label phase, when they were switched to rHuEPO-alpha.
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PMID:The role of recombinant human erythropoietin alpha in the treatment of chronic anemia in multiple myeloma. 1273 13

Several clinical and experimental observations suggest that an intact and activated renin-angiotensin system (RAS) may be an important determinant of erythropoiesis in a variety of clinical conditions, including hypertension, chronic renal insufficiency or failure, chronic obstructive pulmonary disease, and congestive heart failure. Accordingly, RAS inactivation may confer susceptibility to the hematocrit-lowering effects of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Indeed, a dose-dependent decrease in hematocrit is observed within the first month of such therapy. In the majority of patients with hypertension decreases in hematocrit values after RAS inactivation are small and not clinically important. In extreme conditions, however, such as erythrocytosis after successful renal transplantation, secondary polycythemia of chronically hypoxemic COPD patients, erythrocytosis associated with renovascular hypertension, severe cardiac or renal failure, the hematocrit-lowering effect of angiotensin-converting enzyme inhibitors and angiotensin receptor blocker may be profound and even lead to or worsen anemia. Hematocrit reaches its nadir value within three months, and then it remains stable during long-term observations. After discontinuation of RAS blockade, hematocrit values rise gradually over the next three to four months towards the pretreatment levels. The mechanism(s) related to this phenomenon is not yet fully understood, but angiotensin II seems to be responsible for inappropriately sustaining secretion of erythropoietin despite hematocrit elevation and capable to directly stimulate the erythroid progenitors in bone marrow to produce erythrocytes.
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PMID:Hematocrit-lowering effect following inactivation of renin-angiotensin system with angiotensin converting enzyme inhibitors and angiotensin receptor blockers. 1496 14


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