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Query: UMLS:C0728731 (prematurity)
 7,134 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The recent production of recombinant human growth factors has expanded the neonatal clinician's armamentarium for treating sepsis and anemia of prematurity (AOP). Agents that may prove useful in the premature neonate include recombinant human erythropoietin (rh-EPO), granulocyte colony-stimulating factor (rhG-CSF), and CSF). Within the neonatal population, research utilizing these agents is still relatively new. Appropriate clinical trials are still needed to elucidate the optimal dosing regimen for both rhG-CSF and rh-EPO, as are studies to address the issue of long-term safety. Use of rhG-CSF in sepsis and of rh-EPO for AOP is still considered experimental, but in instances where conventional treatments are not proving beneficial, these agents may provide a therapeutic alternative. Their potential for improving care of the premature neonate must also be assessed.
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PMID:Hematopoietic growth factors: Part I. 893 67

Erythropoietin, the primary stimulator of erythropoiesis, represents an important potential therapy for the anemia of prematurity. Enhancement of the therapeutic benefit of recombinant human erythropoietin (rhEp) in very-low-birth-weight infants will require a better understanding of rhEp's pharmacodynamic effects including its interaction with iron in stimulating erythropoiesis. The purpose of this study was to determine the effects of chronic rhEp administration on plasma iron levels and hematopoiesis using a twin lamb model. Nine pairs of twin lambs in which one twin was randomized to receive rhEp, and the other saline, were studied during a 1-week baseline and a subsequent 4- to 5-week treatment period. The effects of therapy on plasma iron levels and erythropoiesis were measured by integrating the areas under the concentration-time curves (AUC) of the study variables. During the rhEp treatment period, significantly greater negative daily AUCs were observed in the rhEp-treated lambs for plasma iron concentration (p = 0.0008), while significantly greater positive daily AUCs were observed for hemoglobin concentration (p = 0.04) and reticulocyte count (p = 0.02). In the rhEp-treated group, pretreatment iron concentrations were directly associated with the magnitude of the iron response during treatment such that the greater the pretreatment iron, the greater the daily AUC below the plasma iron concentration-time plot (r = -0.66, p = 0.05). For the placebo-treated group, this association tended toward, but did not achieve, statistical significance (r = -0.52, p = n.s.). These observations suggest that treatment of rapidly growing newborn lambs with rhEp results in increased iron utilization due to increased erythropoiesis and depends on iron status at the initiation of rhEp treatment. Use of the term neonatal lamb model offers advantages over studies in human infants for more detailed or invasive examinations of the interaction of iron and rhEp treatment.
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PMID:Effect of chronic erythropoietin administration on plasma iron in newborn lambs. 896 12

Neonatal erythropoiesis is limited by a relatively inadequate production of erythropoietin. This is likely the result of dependence on the hepatic production of erythropoietin and an incomplete switchover to renal production. The present model of neonatal erythropoiesis suggests that the use of exogenous erythropoietin should correct the early anemia of prematurity that is observed at 6 weeks of age in premature newborns. Randomized, controlled trials of erythropoietin use in very low birthweight infants are reviewed. The data support the conclusion that erythropoietin at doses of > or = 750 u/kg/wk started at less than 7 days of age results in improved reticulocyte counts and hemoglobin levels, but does not reduce the number of infants who will be exposed to blood products. Erythropoietin at doses of > or = 600 u/kg/wk started at an average of 21 days of life improves reticulocyte counts and hemoglobin levels, and reduces the number of infants will will require late transfusion, but does nothing for the bulk of infants who are transfused before that age.
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PMID:The role of erythropoietin in the anemia of prematurity. 919 30

Recombinant human erythropoietin has been available for clinical use since 1985. It was an immediate success in treating the anemia of chronic renal failure and has also enjoyed some objective success in the treatment of other anemias in either a therapeutic or prophylactic setting, but the issues of appropriate patient selection and cost-benefit ratios are still unresolved. This review discusses the most recent literature concerning the use of recombinant human erythropoietin for the anemia associated with cancer, HIV infection, myelodysplasia, prematurity, autologous blood transfusion, bone marrow transplantation, and chronic renal failure.
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PMID:Clinical use of erythropoietin. 937 81

The purpose of this review is to give an update of the recent progress in research on erythropoietin (Epo), the hormone that regulates red blood cell production. Epo is a glycoprotein with a molecular mass of approx 30 kDa, which circulates in plasma of the human with 165 amino acids with three N-linked and one O-linked acidic oligosaccharide side chains in the molecule. Both the alpha (39% CHO) and beta (24% CHO) forms are available for clinical use, and there does not appear to be any difference in the pharmacokinetics of these two forms of Epo. Radioimmunoassays and enzyme-linked immunoabsorbant (ELISA) assays are available in a kit form. Serum levels of Epo in normal human subjects range between 1 and 27 mmu/ml or approx 5 pmol/l. It seems clear that the cells in the adult mammalian kidney which produce Epo are the interstitial cells in the peritubular capillary bed and the perivenous hepatocytes in the liver. Expression of the human Epo gene sequences that direct expression in the kidney are located 6-14 kilobases 5' to the gene; whereas the sequences that control hepatocyte-specific expression are located within 0.7 KS to the 3'-flanking region and 0.5 KS to the 5'-flanking region. The signal transduction pathways postulated to be involved in the expression of Epo are: kinases A, G and C; both a constitutive factor and a second hypoxia-inducible factor-1 (HIF-1) located in the 5' end of an hypoxia inducible enhancer region of the Epo gene; and reactive oxygen species. The primary target cell in the bone marrow acted on by Epo is the colony-forming unit erythroid (CFU-E) which has the highest number of Epo receptors. It has been postulated that Epo decreases the rate which Epo-dependent progenitor cells undergo programed cell death (apoptosis). There are two major signal transduction pathways activated by the Epo receptor: the JAK2-STAT5 pathway and the ras pathway. Both pathways involve tyrosine phosphorylation. The approved clinical uses of Epo are the anemias associated with end-stage renal disease, cancer chemotherapeutic agents, and patients with HIV infection receiving AZT. Other anemias reported to respond to Epo therapy are anemia of prematurity, rheumatoid arthritis, and myelodysplasia. Other uses of Epo under investigation are in perioperative surgery and preoperative autologous blood donation.
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PMID:Erythropoietin: physiologic and pharmacologic aspects. 940 40

This review has two objects: a brief recapitulation of the biological background of erythropoietin (EPO), and a review of its clinical utilization in hematology. EPO, both in its naturally occurring and recombinant form (rH-EPO), is a single chain glycoprotein with an approximate molecular weight of 30.000 to 34.000 kD. Its heavy glycosilation is essential for its activity in vivo, since asialoEPO is readily cleared by the heptic asialoglycoprotein receptor. This impedes the recombinant molecule's synthesis in biologic cultures other than mammalian cells (Chinese hamster's ovary cells), and inevitably increases costs. If in vitro glycosilation of E. coli-derived rH-EPO could be achieved, the clinical utilization of the product would be considerably enhanced, most especially when very high doses are necessary, as discussed later. There is no antigenic diversity between natural and recombinant EPO, so that out of the enormous clinical experience only one single case of immunization has been recorded. Almost paradoxically there are however three published cases of pure red cell aplasia (PRCA) caused by immunization against autologous EPO. It is now established that in adults EPO is synthetized in renal peritubular interstitial cells, although some residual activity remains in the liver. Hypoxia results in a rapid induction of EPO expression, although the role of the oxygen sensor system is still debated. Cellular targets are notoriously erythroid progenitors and precursors (BFU-E, CFU-E, early and intermediate erythroblasts). The global erythropoietic activity resulted in various effects (proliferation, differentiation, survival), but most probably each single effect is integrated with and complementary of the others. The utilization of rH-EPO in hematologic diseases came much later than its dramatic success in renal anemia. A variety of tools useful for assessing the possible beneficial effects of rH-EPO in clinical hematology has been proposed, among which a low level of endogenous EPO is a good predictor for therapeutic success. 'Hemopathic' anemia can be subdivided into three categories: patients with normal erythropoiesis due to inadequate EPO production (anemia of prematurity), patients with depressed but nonclonal erythropoiesis (chemotherapy, lymphoid malignancies such as multiple myeloma-MM and chronic lymphatic leukemia-CCL) and patients with at least partially clonal anemia, such as paroxysmal nocturnal hemoglobinuria (PNH), hemoglobinopaties, myelodysplastic syndromes (MDS) and others. Results in the first category of patients are, as expected, prompt and satisfactory with physiologic doses. Although therapeutic strategy for MM is moving fast to curative intents, the utilization of rH-EPO is indicated for the control of anemia in conservatively-treated patients. In the third category the most important and controversial area is MDS. Significant erythropoietic results are generally obtained in about 20% of patients; however, the association with G-CSF has considerably enhanced the response rate. In the field of bone marrow transplantation there is an inadequate production of endogenous EPO in the allogeneic setting, and randomized studies have shown the benefits of rH-EPO in this situation. However, the most important results have been obtained in post-major-ABO incompatible PRCA, when the removal of the recipient's isohemagglutinins does not resolve the anemia. High and very high doses of rH-EPO (even over 500 UI/kg/day for 2-4 weeks) may resolve this occasionally quite refractory condition. Although extremely expensive, this treatment may be life-saving when an otherwise successful allogeneic transplant is at the risk of failure because of this relatively uncommon but severe immunohematologic complication.
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PMID:[Erythropoietin: biochemical characteristics, biologic effects, indications and results of use in hematology]. 948 78

Recombinant human erythropoietin is used in clinical practice mainly for treatment of anemia of renal failure. In the past years, however, its use has been approved for other indications, including prevention of anemia in surgical patients or in patients undergoing platinum-based chemotherapy, treatment of anemia of prematurity, of anemia induced by zidovudine therapy in HIV-infected patients, and of anemia induced by chemotherapy of nonmyeloid malignancies. Erythropoietin should routinely be given subcutaneously to maximize its effects. Most patients undergoing rHuEpo treatment develop functional iron deficiency, a situation in which iron supply to the erythroid marrow is inadequate for the erythrocyte precursor demand. Iron supplementation should, therefore, be given to all individuals receiving rHuEpo except for those patients with increased serum iron and transferrin saturation. Outside the setting of uremia, only a portion of patients can clearly benefit from erythropoietin therapy; therefore, the use of rHuEpo should be individualized in nonrenal applications.
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PMID:How and when to use erythropoietin. 957 Jul 2

The outcome of pregnancy in patients with end-stage renal failure has long been considered to be extremely poor, and the literature concerning pregnancy while on dialysis is rather scarce. We reviewed the records of five pregnancies in dialysis patients and performed a national survey on this topic. The dialysis technique and dialysis dose, the effects of erythropoietin (EPO), and the evolution of blood pressure levels in our patients are presented. The dose of EPO had to be increased to maintain the hemoglobin level at 10 to 11 g/dL. There was no case of EPO-related hypertension and no need for transfusion. The obstetric data of the national survey, including our own patients, were analyzed. The incidence of pregnancy going beyond the first trimester was 0.3 per 100 patient-years (15 cases in 1,472 females of childbearing age treated, for a total of 4,545 patient-years). In all but one patient initiating pregnancy while already on dialysis, the frequency and dose of dialysis were increased (to a weekly Kt/V of six to eight in our personal cases). The outcome was successful in 50% of pregnancies occurring in hemodialyzed patients and in 80% of patients who started dialysis after initiation of pregnancy. Polyhydramnios was found in eight of 13 cases and growth retardation in two of nine cases. The incidence of low birth weight and prematurity was 100%, and cesarean section was performed in 66% of successful pregnancies. In successful pregnancies, we found a correlation between birth weight and dose of dialysis. Our findings confirm the remarkable improvement in the prognosis of pregnancy in dialysis patients in recent years.
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PMID:Pregnancy and dialysis. 959 Feb

A total of 2,299 dialysis units listed by the Health Care Finance Administration were surveyed to determine the frequency and course of pregnancies in dialysis patients. The responses included 930 units caring for 6,230 females aged 14 to 44 years (1,699 receiving peritoneal dialysis and 4,531 receiving hemodialysis). Two percent of the female patients of childbearing age became pregnant over a 4-year period (2.4% of the hemodialysis patients and 1.1% of the peritoneal dialysis patients). The infant survival rate was 40.2% in the 184 pregnancies in women who conceived after starting dialysis and 73.6% in the 57 pregnancies in women who started dialysis after conception. In the subset of women in whom dialysis modality was known, infant survival was not significantly different between the hemodialysis and peritoneal dialysis patients (39.5% v 37%). There was a trend toward better infant survival in women who received dialysis > or = 20 hours per week and a weak correlation between number of hours of dialysis and gestational age (P = 0.05). Maternal complications included two maternal deaths and five intensive care unit admissions for hypertensive crisis. Seventy-nine percent of women had some degree of hypertension, and 32 had blood pressure higher than 170/110 mm Hg. Only 5.9% of women had a hematocrit greater than 30% throughout pregnancy. Twenty-six percent of women treated with erythropoietin (EPO) and 77% of women not receiving EPO required transfusions. Eleven infants had congenital anomalies and 11 had long-term medical problems. Eighty-four percent of infants born to women who conceived after starting dialysis were premature. The likelihood of a surviving infant resulting from pregnancy in dialysis patients is higher than previously observed. There is no preferred dialysis modality. There is a suggestion that increased dialysis time may improve outcome. Prematurity remains a major cause of morbidity and likely contributes to a high frequency of long-term medical problems in surviving infants.
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PMID:Registry of pregnancy in dialysis patients. 959 Feb

Our objective was to discuss the role of erythropoietin in fetal erythropoiesis and to review its clinical uses in perinatal medicine. All relevant articles compiled through a MEDLINE search (years 1986-1997) were reviewed. Erythropoietin is essential for fetal erythropoiesis and is produced in response to hypoxia and anemia. Cord blood erythropoietin is purely fetal and reflects tissue oxygenation. It has been found to be increased in many complicated pregnancies with underlying fetal hypoxia. Erythropoietin could be used as a marker of fetal hypoxia because its concentration rises rapidly by increased production in response to hypoxia. Its measurement might enable more accurate timing of hypoxic injury. In addition, erythropoietin levels have been well correlated with perinatal brain damage and may facilitate treatment of high risk neonates. Erythropoietin has also been used successfully in anemia of prematurity, decreasing the transfusion requirement. However, studies are still needed to determine the optimal doses of erythropoietin and iron supplementations required for maximizing the red blood cell response. Erythropoietin has been examined as potential maternal therapy in various disorders during pregnancy. These include end-stage renal disease, severe antepartum iron deficiency anemia, and postpartum anemia. Erythropoietin has been found to be effective and well tolerated in these conditions. An additional promising use lies in the optimization of maternal red blood cell mass to allow autologous blood donation. This may be critical in cases where a large amount of bleeding might be anticipated, as with placenta previa. This would also minimize the donor transfusion-related hazards. Erythropoietin with its wide clinical applications could improve maternal and neonatal outcome.
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PMID:Erythropoietin in obstetrics. 970 90


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