Increased Serum Erythropoietin Levels Research Articles

Hypoxia ameliorates maternal diet-induced insulin resistance during pregnancy while having a detrimental effect on the placenta.

Maternal overweight/obesity contributes significantly to the development of gestational diabetes, which causes risks to both mother and fetus and is increasing sharply in prevalence worldwide. Since hypoxia reprograms energy metabolism and can alleviate weight gain, adiposity, insulin resistance (IR), and dyslipidemia, we set out to study the potential of sustained reduced ambient oxygen tension (15% O2) during pregnancy for alleviating the detrimental effects of diet‐induced IR in C57Bl/6N mice, taking normal chow‐fed and normoxia (21% O2) groups as controls. Our data show that hypoxic intervention reduced maternal weight gain, adiposity, and adipose tissue inflammation, and ameliorated maternal glucose metabolism and IR during gestation in diet‐induced IR relative to normoxia. Where diet‐induced IR reduced maternal hemoglobin and increased serum erythropoietin levels, hypoxic intervention compensated for these changes. Diet‐induced IR reduced fetal growth in normoxia, and even more in hypoxia. Hypoxic intervention reduced liver weight gain during pregnancy in the dams with diet‐induced IR, maternal liver weight being positively associated with embryo number. In case of diet‐induced IR, the hypoxic intervention compromised placental energy metabolism and vascularization and increased end‐pregnancy placental necrosis. Altogether, these data show that although hypoxic intervention mediates several beneficial effects on maternal metabolism, the combination of it with diet‐induced IR is even more detrimental to the placental and fetal outcome than diet‐induced IR alone.

P0852PERICYTE-SPECIFIC MANIPULATION OF HYPOXIA-INDUCIBLE FACTORS REGULATES ERYTHROPOIESIS WITHOUT AGGRAVATING RENAL FIBROSIS

Abstract Background and Aims Stabilizers of hypoxia-inducible factor (HIF) have been shown to be effective on treatment of anemia in patients with chronic kidney disease (CKD). Increased erythropoietin (EPO) production and enhanced erythropoiesis are known to be the major mechanisms responsible for the treatment effects. However, the effect of HIF stabilization on renal fibrosis is controversial. We created animal models characterized by CKD and pericyte-specific stabilization of HIF to examine the effects of HIF on renal fibrosis and erythropoiesis. Method Gli1CreERT2/+;Egln1F/F, Gli1CreERT2/+;VhlF/F, and Gli1CreERT2/+;Hif1aF/F;Hif2aF/F mice were generated to study the effects of pericyte-specific overexpression or knockout of Hif. Unilateral ureteral obstruction (UUO) was used to induce CKD. The severity of fibrosis was determined by Picrosirius red stain and Col1a1 mRNA level in the kidney. Results Pericyte-specific stabilization of HIF resulted in increased serum EPO level, augmented splenic erythropoiesis, and polycythemia, while the severity of renal fibrosis was not affected. In line with these findings, pericyte-specific knockout of Hif1a or Hif2a did not result in significant change of renal fibrosis. Conclusion Our study endorses the neutral effects of pericyte-specific HIF stabilization on renal fibrosis.

Gamma-Aminobutyric Acid Increases Erythropoietin by Activation of Citrate Cycle and Stimulation of Hypoxia-Inducible Factors Expression in Rats.

Erythropoietin (EPO) is the primary regulator of erythropoiesis in the mammalian fetus and adult. Deficiency of EPO induces anemia. In this study, we investigated the effect of gamma-aminobutyric acid (GABA) on serum EPO levels and erythropoiesis in rats. Expression levels of Epo-related genes were measured by quantitative real-time PCR (qPCR) and expression of Epo and Epo receptor (Epor) proteins were measured by immunohistochemistry. The gene and protein expression profiles of kidney tissue in GABA-treated rats were evaluated by ribonucleic acid (RNA) sequencing and two-dimensional electrophoresis (2-DE), respectively. GABA significantly increased serum EPO levels and expression levels of Epo and Epor. GABA increased expression levels of hypoxia-inducible factor (Hif)-1 and Hif-2. Seven proteins with expression levels showing >2-fold change were identified by 2-DE followed by MALDI-TOF MS in GABA-treated rat kidney. The top KEGG pathway from the identified proteins was the tricarboxylic acid cycle, and nicotinamide adenine dinucleotide (NADH) dehydrogenase, succinate dehydrogenase, and isocitrate dehydrogenase were identified as key proteins. GABA treatment significantly increased ATP levels and NADH dehydrogenase activity in a dose-dependent manner. In conclusion, GABA shows a new physiological role in EPO production, and it can thus can contribute to the prevention of anemia when used alone or in combination with other anemia treating drugs.

Relationship between anemia, iron deficiency, and platelet production in dogs

Platelet production increases in anemic people. In particular, iron deficiency causes reactive thrombocytosis in such patients. Although anemia and iron deficiency are frequently seen in dogs, there are no published studies on this subject. The aim of the present study was to investigate the relationship between anemia, iron deficiency, and platelet production in dogs. A total of 81 dogs brought to the university animal hospital with signs of anemia were used. Haemogram parameters, serum iron (Fe), erythropoietin (EPO), and thrombopoietin (TPO) levels, as well as total iron binding capacity (TIBC), were measured. Transferrin saturation (TSAT) ratios were calculated. The animals were categorized as anemic or non-anemic, mildly anemic or moderately/ severely anemic, and having iron deficiency or no iron deficiency according to haemogram parameters and the serum Fe level. A high platelet number was observed in dogs with mild anemia. Dogs with mild anemia also had higher serum EPO levels than dogs with moderate/severe anemia (P = 0.047). Iron deficiency was detected in 31 dogs. The platelet number was higher in dogs with iron deficiency (P = 0.004). It was also observed that dogs with iron deficiency had higher serum EPO levels (P = 0.027) and lower TPO levels (P = 0.025) than dogs without iron deficiency. In conclusion, it can be said that mild anemia and iron deficiency cause thrombocytosis in dogs. The increased serum EPO levels, both in dogs with mild anemia and those with iron deficiency, suggest that the increase in platelet production is due to EPO. Nevertheless, there is a need for further research to fully understand the underlying mechanism.

A truncating mutation in EPOR leads to hypo-responsiveness to erythropoietin with normal haemoglobin

The cytokine erythropoietin (EPO), signalling through the EPO receptor (EPO-R), is essential for the formation of red blood cells. We performed a genome-wide association study (GWAS) testing 32.5 million sequence variants for association with serum EPO levels in a set of 4187 individuals. We detect an association between a rare and well imputed stop-gained variant rs370865377[A] (p.Gln82Ter) in EPOR, carried by 1 in 550 Icelanders, and increased serum EPO levels (MAF = 0.09%, Effect = 1.47 SD, P = 3.3 × 10−7). We validated these findings by measuring serum EPO levels in 34 additional pairs of carriers and matched controls and found carriers to have 3.23-fold higher EPO levels than controls (P = 1.7 × 10−6; Pcombined = 1.6 × 10−11). In contrast to previously reported EPOR mutations, p.Gln82Ter does not associate with haemoglobin levels (Effect = −0.045 SD, P = 0.32, N = 273,160), probably due to a compensatory EPO upregulation in response to EPO-R hypo-responsiveness.

Polycythemia vera and essential thrombocythemia: 2017 update on diagnosis, risk-stratification, and management.

Polycythemia Vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms respectively characterized by erythrocytosis and thrombocytosis; other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus, and risk of leukemic or fibrotic transformation. PV is defined by a JAK2 mutation, whose absence, combined with normal or increased serum erythropoietin level, makes the diagnosis unlikely. JAK2, CALR, and MPL mutations are the mutually exclusive "driver" mutations in ET with respective incidences of 55%, 25%, and 3%; approximately 17% are triple-negative. However, the same molecular markers might also be present in prefibrotic myelofibrosis, whose morphological distinction from ET is prognostically relevant. Median survivals are approximately 14 years for PV and 20 years for ET; the corresponding values for younger patients (age <60 years) are 24 and 33 years. Life-expectancy in ET is inferior to the control population. Driver mutational status has not been shown to affect survival in ET whereas the presence of JAK2/MPL mutations has been associated with higher risk of arterial thrombosis and that of MPL with higher risk of fibrotic progression. Risk factors for overall survival in both ET and PV include advanced age, leukocytosis and thrombosis. Leukemic transformation rates at 20 years are estimated at <10% for PV and 5% for ET; fibrotic transformation rates are slightly higher. Most recently, ASXL1, SRSF2, and IDH2 mutations have been associated with inferior overall, leukemia-free or fibrosis-free survival in PV; similarly adverse mutations in ET included SH2B3, SF3B1, U2AF1, TP53, IDH2, and EZH2. Current risk stratification in PV and ET is designed to estimate the likelihood of recurrent thrombosis. Accordingly, PV includes two risk categories: high-risk (age >60 years or thrombosis history) and low-risk (absence of both risk factors). In ET, risk stratification includes four categories: very low risk (age ≤60 years, no thrombosis history, JAK2/MPL un-mutated), low risk (age ≤60 years, no thrombosis history, JAK2/MPL mutated), intermediate risk (age >60 years, no thrombosis history, JAK2/MPL un-mutated), and high risk (thrombosis history or age >60 years with JAK2/MPL mutation). In addition, presence of extreme thrombocytosis (platelets >1000 × 10(9)/L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding. The main goal of therapy in PV and ET is to prevent thrombohemorrhagic complications. All patients with PV require phlebotomy to keep hematocrit below 45% and once-daily aspirin (81 mg). In addition, high-risk patients with PV require cytoreductive therapy. Very low risk ET patients might not require any form of therapy while low-risk patients require at least once-daily aspirin therapy. Cytoreductive therapy is also recommended for high-risk ET patients but it is not mandatory for intermediate-risk patients. First-line drug of choice for cytoreductive therapy, in both ET and PV, is hydroxyurea and second-line drugs of choice are interferon-α and busulfan. We currently do not recommend treatment with ruxolutinib or other JAK2 inhibitors in PV or ET, unless in the presence of severe and protracted pruritus or marked splenomegaly that is not responding to the aforementioned drugs. Screening for AvWS is recommended before administrating aspirin, in the presence of extreme thrombocytosis. Am. J. Hematol. 92:95-108, 2017. © 2016 Wiley Periodicals, Inc.

Effects of fullerenol C60(OH)24 on physiological and compensatory erythropoiesis

In this work, the effect of fullerenol on erythropoiesis was investigated in healthy rats and in rats that had suffered blood loss in the amount of 2% of body weight. Fullerenol C60(OH)24 was diluted in 2 mL of 0.9% sodium chloride solution and injected intraperitoneally in a dose of 0.1 or 0.2 mg/kg body weight. The counts of reticulocytes, erythrocytes, and serum erythropoietin levels were determined in 48 and 96 h, as were the numbers of erythroid cells and erythroblastic islands (EIs) of different maturity fractions in the bone marrow and the fraction of the red pulp in the spleen. In intact rats, the reconstruction of erythropoiesis was augmented 1.5-fold in response to 0.1 mg/kg fullerenol C60(OH)24 and 3.3-fold in response to 0.2 mg/kg fullerenol. Both doses increased the number of oxyphylic erythroblasts in the bone marrow twofold, and 0.2 mg/kg fullerenol increased the red pulp fraction in the spleen by 9%; at the same time, fullerenol did not affect the counts of reticulocytes and erythrocytes, or the serum erythropoietin level in the case of normal erythropoiesis. Following hemorrhage, exposure to a 0.2 mg/kg dose of fullerenol C60(OH)24 increased serum erythropoietin levels, delayed the maturation of erythroid cells in EIs, partially blocked the release of reticulocytes from the bone marrow, and promoted an increase in the relative spleen weight and the red pulp fraction in the spleen.

Polycythemia vera and essential thrombocythemia: 2015 update on diagnosis, risk-stratification and management.

Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms, respectively characterized by erythrocytosis and thrombocytosis. Other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus, and risk of leukemic or fibrotic transformation. PV is defined by a JAK2 mutation, whose absence, combined with normal or increased serum erythropoietin level, makes the diagnosis unlikely. Differential diagnosis in ET includes reactive thrombocytosis, chronic myeloid leukemia, and prefibrotic myelofibrosis. Janus kinase 2 (JAK2), calreticulin (CALR), or myeloproliferative leukemia virus oncogene (MPL) mutations occur in approximately 55%, 25%, and 3% of ET patients, respectively. The same molecular markers are also present in prefibrotic myelofibrosis, which needs to be morphologically distinguished from ET. Survival and leukemic/fibrotic transformation: Median survivals are ∼14 years for PV and 20 years for ET; the corresponding values for younger patients are 24 and 33 years. Life-expectancy in ET is inferior to the control population. JAK2/CALR mutational status does not affect survival in ET. Risk factors for survival in ET and PV include advanced age, leukocytosis, and thrombosis. Leukemic transformation rates at 20 years are estimated at <10% for PV and 5% for ET; fibrotic transformation rates are slightly higher. Thrombosis risk stratification: Current risk stratification in PV and ET is designed to estimate the likelihood of recurrent thrombosis: high-risk is defined by the presence of age >60 years or presence of thrombosis history; low-risk is defined by the absence of both of these two risk factors. Recent data consider JAK2V617F and cardiovascular risk factors as additional risk factors. Presence of extreme thrombocytosis might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding. The main goal of therapy in PV and ET is to prevent thrombohemorrhagic complications. In low risk patients, this is accomplished by the use of low-dose aspirin and phlebotomy (hematocrit target <45%) in PV. In high risk (for thrombosis) patients, treatment with hydroxyurea is additionally recommended. Treatment with busulfan or interferon-α is usually effective in hydroxyurea failures and the additional value of JAK inhibitor therapy in such cases is limited. Screening for AvWS is recommended before administrating aspirin, in the presence of extreme thrombocytosis.

Polycythemia vera and essential thrombocythemia: 2013 update on diagnosis, risk‐stratification, and management

Polycythemia Vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms (MPN) primarily characterized by erythrocytosis and thrombocytosis, respectively. Other disease features include leukocytosis, splenomegaly, thrombohemorrhagic complications, vasomotor disturbances, pruritus and a small risk of disease progression into acute myeloid leukemia or myelofibrosis. Almost all patients with PV harbor a JAK2 mutation. When PV is suspected, the presence of a JAK2 mutation highly suggests the diagnosis and its absence, combined with normal or increased serum erythropoietin level, excludes the diagnosis. Differential diagnosis of ET should include reactive thrombocytosis, chronic myeloid leukemia, prefibrotic myelofibrosis and RARS-T (refractory anemia with ring sideroblasts associated with marked thrombocytosis). A JAK2 mutation is found in 50-70% of patients with ET, myelofibrosis or RARS-T and is capable of distinguishing reactive from clonal thrombocytosis. Current risk stratification in PV and ET is designed to estimate the likelihood of thrombotic complications: high-risk is defined by the presence of age >60 years or presence of thrombosis history; low-risk is defined by the absence of both of these two risk factors. Recent data considers JAK2V617F and cardiovascular (CV) risk factors as additional risk factors for thrombosis. Presence of extreme thrombocytosis (platelet count >1,000 × 10(9) /L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding. Risk factors for shortened survival in both PV and ET include advanced age, leukocytosis, and history of thrombosis. Survival is near-normal in ET and reasonably long in PV. The 10-year risk of leukemic/fibrotic transformation is <1%/1% in ET and <3%/10% in PV. In contrast, the risk of thrombosis exceeds 20%. The main goal of therapy is therefore to prevent thrombohemorrhagic complications. In low risk patients, this is effectively and safely accomplished by the use of low-dose aspirin in both PV and ET and phlebotomy (hematocrit target of <45%) in PV. In high risk patients, treatment with hydroxyurea is additionally recommended, although not mandated in older patients without JAK2V617F or CV risk factors. Treatment with busulfan or interferon-α is usually effective in hydroxyurea failures. Screening for clinically significant AvWS is recommended before administrating aspirin in the presence of extreme thrombocytosis.

Leukemia kidney infiltration can cause secondary polycythemia by activating hypoxia-inducible factor (HIF) pathway

Secondary polycythemia with increased production of erythropoietin (EPO) is known to occur in kidney diseases such as hydronephrosis and cystic disease, but the mechanism remains unclear. We report an 18-year-old female with isolated renal relapse of acute lymphoblastic leukemia accompanied by polycythemia. At the relapse, she presented with bilateral nephromegaly, mild renal dysfunction, and erythrocytosis with increased serum EPO levels up to 52.1 mIU/mL (9.1-32.8). Renal biopsy demonstrated diffuse lymphoblastic infiltration. The expression of hypoxia-inducible factor (HIF)-1α, which is undetectable in normal kidney, was observed in the renal tubule epithelium compressed by lymphoblastic cells. These findings suggest that erythrocytosis was caused by renal ischemia due to leukemic infiltration. Polycythemia probably became apparent because of the lack of leukemic involvement of the bone marrow. With chemotherapy, the serum EPO level rapidly decreased to normal range accompanied by the normalization of kidney size and function. Renal leukemic infiltration may enhance EPO production, although not recognized in the majority of cases because of bone marrow involvement. Our case has clarified the mechanism of previously reported polycythemia associated with renal diseases as renal ischemia. Furthermore, we have added renal ischemia resulting from tumor infiltration to the list of causes of secondary polycythemia.

Polycythemia vera and essential thrombocythemia: 2012 update on diagnosis, risk stratification, and management

Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms primarily characterized by erythrocytosis and thrombocytosis, respectively. Other disease features include leukocytosis, splenomegaly, thrombohemorrhagic complications, vasomotor disturbances, pruritus, and a small risk of disease progression into acute myeloid leukemia or myelofibrosis. Almost all patients with PV harbor a JAK2 mutation. When PV is suspected, the presence of a JAK2 mutation confirms the diagnosis and its absence, combined with normal or increased serum erythropoietin level, excludes the diagnosis. Differential diagnosis of ET had to include chronic myelogenous leukemia and prefibrotic myelofibrosis. A JAK2 mutation is found in approximately 60% of patients with ET. Current risk stratification in PV and ET is designed to estimate the likelihood of thrombotic complications: high-risk is defined by the presence of age >60 years or presence of thrombosis history; low-risk is defined by the absence of both of these two risk factors. Presence of extreme thrombocytosis (platelet count >1,000 × 10(9)/L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding. Risk factors for shortened survival in both PV and ET include advanced age, leukocytosis, and history of thrombosis. Survival is near-normal in ET and reasonably long in PV. The 10-year risk of leukemic/fibrotic transformation is <1%/1% in ET and <3%/10% in PV. In contrast, the risk of thrombosis exceeds 20%. The main goal of therapy is therefore to prevent thrombohemorrhagic complications and this is effectively and safely accomplished by the use of low-dose aspirin (PV and ET), phlebotomy (PV) and hydroxyurea (high risk PV and ET). Treatment with busulfan or interferon-α is usually effective in hydroxyurea failures. Screening for clinically significant AvWS is recommended before administrating aspirin in the presence of extreme thrombocytosis.

Nonviral gene delivery of erythropoietin by mesenchymal stromal cells

Erythropoietin (EPO) acts on erythroblasts in the bone marrow (BM) to stimulate the formation of red blood cells. In this study, we wanted to determine whether BM-derived mesenchymal stromal cells (MSCs) can be used as cellular vehicles to deliver EPO in mice without the use of viral vectors. After isolation and characterization of murine MSCs (mMSCs), different transient transfection procedures were compared for their efficacy of gene transfer of the pEGFP-N2 plasmid. Nucleofection outperformed magnetofection and lipofection. Stably transfected mMSCs were generated by selection with G418-disulfate and single-cell-colony-forming unit (sc-CFU) assays without changes in their proliferation capacity and osteogenic/adipogenic differentiation potential. Next, murine EPO was stably introduced into mMSCs by nucleofection of a plasmid encoding the epo and egfp genes. Intraperitoneal transplantation of EPO-expressing mMSCs increased serum EPO levels, hematocrit and hemoglobin of C57BL/6 mice within 1 week. The hematocrit remained elevated for 5 weeks, but production of antibodies against both transgenes was detected in the hosts and serum EPO levels normalized. Our results suggest that nonviral gene delivery into MSCs can be used to enhance the known beneficial effects MSCs by additional production of therapeutic factors like EPO in vivo.

Repeated phlebotomy augments angiogenesis to improve blood flow in murine ischemic legs

Anemia may accelerate angiogenesis in ischemic organs through its ability to augment tissue hypoxia-induced generation of several known angiogenic factors and to increase erythropoietin levels, which are also potently angiogenic. We examined the effect of controlled phlebotomy (bloodletting) on blood flow in a mouse ischemic leg model. We ligated the right femoral artery of BALB/c mice. In the phlebotomy group, 200 microl of blood were drawn from the tail vein once a week. After 4 wk, blood flow in the ischemic leg was significantly better in the phlebotomy group (flow ratio of the ischemic to nonischemic leg, 0.87 + or - 0.04) than the control group (0.59 + or - 0.05, P < 0.05), and capillary density was significantly higher. Repeated phlebotomy increased serum erythropoietin levels as well as the expression of hypoxia-inducible transcription factor-1alpha and vascular endothelial growth factor and both the expression and activity of Akt and endothelial nitric oxide synthase (eNOS) in ischemic legs. Treatment with wortmannin or N(omega)-nitro-l-arginine methyl ester significantly attenuated the phlebotomy-induced improvement of blood flow. In addition, fluorescence-activated cell sorting analysis revealed an increase in circulating peripheral endothelial progenitor cells in the phlebotomy group, and treatment with AMD3100, a specific inhibitor of the chemokine receptor CXCR4, blocked the beneficial effect of phlebotomy. These findings suggest that repeated phlebotomy improves blood flow in ischemic legs through an angiogenic action that involves the Akt/eNOS pathway, endothelial progenitor cell mobilization, and their complicated cross talk. An adequately controlled phlebotomy might be one method by which to induce therapeutic angiogenesis.

Increased Serum Erythropoietin Level during Azathioprine Treatment in Renal Transplant Recipients

One hundred and six renal transplant patients were studied. During the first 12 months after renal transplantation all patients were treated with cyclosporine (Cy) and prednisone. At 12 months after transplantation the patients were randomly allocated to either conventional treatment with azathioprine (Az) and prednisone (group Az) or to continued treatment with Cy and prednisone (group Cy). Serum erythropoietin (s-EPO), glomerular filtration rate (GFR) and hematocrit (Hct) were measured at 12, 18 and 24 months after transplantation. s-EPO rose in the group Az from 19 U/l (mean) at 12 months to 28 U/l (p < 0.01) at 18 months and remained elevated at 24 months at 29 U/l compared with baseline level and with healthy subjects without anemia 18 U/l (p < 0.01). There was no significant change in s-EPO in group Cy during the study. The Hct in the two groups was not significantly different. GFR was the same in the two groups at 12 months and after 24 months. In conclusion, a switch from Cy to Az 1 year after renal transplantation results in a sustained rise in s-EPO which may in part represent a compensatory phenomenon to bone marrow suppression.

術前貯血式自己血輸血基準の考案 外科的顎矯正術への適応

Standards for stored autologous blood transfusion were established recently based on the clinical experience and research data for 140 autologous blood transfusions, which have been carried out in orthognathic surgery patients between 1985 and 1992 at the First Department of Oral and Maxillofacial Surgery, Kagoshima University Dental Hospital, Japan. Regarding standards designed to avoid anemia after phlebotomy, one time collection volume was decided using the following formula: predicted Hb level after collection=(circulating blood volume-one time collection volume) ÷circulating blood volume×Hb level before collection ≥10 g/dl. Fifteen female patients with mandibular prognathism were studied hematologically following a 400 ml autologous blood collection and a transfusion to evaluate the efficiency of this new standard.Two units of whole blood were collected 15 days before each patient's operation. All units of collected blood were transfused without homologous blood transfusion. RBCs, Hb and Hct, which were reduced after the phlebotomy, normalized the day before operation. The rate of reticulocytes was tended to increase during the period of blood storage and for one week after operation. The iron level in the serum was minimum on the day following operation, suggesting the need for postoperative iron supplementation. Increased serum erythropoietin levels, similar to reticulocytes, showed high erythropoietic activity from the first day following the phlebotomy to the postoperative period. There were no differences between the actual minimum Hb level and the predicted Hb level after blood collection of 400 ml. The Hb level on the first day after operation was significantly higher than the calculated Hb level on the same day without blood transfusion (p<0.01).These results suggested the usefulness of our standards.

Erythropoietin and Anemia in the Progression of Balkan Endemic Nephropathy and Other Renal Diseases

We have investigated anemia in patients at different stages of the evolution of three chronic renal diseases: Balkan endemic nephropathy (BEN), chronic pyelonephritis (PN) and chronic glomerulonephritis (GN). A total of 88 patients with creatinine clearances from 9 to 118 ml/min and hemoglobin concentrations from 70 to 160 g/l were studied with regard to the relationship, if any, between erythropoietin production and the type and stage of nephropathy. Anemia in BEN was a particular focus of interest since it had been stated that in BEN, anemia precedes renal failure. Our data neither prove nor disprove this statement. A significant positive correlation between creatinine clearance and hemoglobin concentration was found in all three nephropathies, indicating that in the patients studied the severity of anemia increased with the impairment of renal function regardless of the underlying disease. Serum levels of immunoreactive erythropoietin were in the normal range in 54 patients, moderately increased in 20 and slightly decreased in 14. The erythropoietin level appears to be unrelated to the stage of renal failure or the type of nephropathy. The only exception was the subgroup where the patients with glomerulonephritis and normal renal function had increased serum erythropoietin levels and significantly higher parameters of red blood cell concentration than the patients from the same subgroup with tubulointerstitial nephropathies. In patients with severe renal failure and anemia, serum erythropoietin levels were inappropriately low for the degree of anemia, indicating that erythropoietin plays a role in the pathogenesis of the anemia.

Polycythemia in transgenic mice expressing the human erythropoietin gene.

Erythropoietin is a glycoprotein hormone that regulates mammalian erythropoiesis. To study the expression of the human erythropoietin gene, EPO, 4 kilobases of DNA encompassing the gene with 0.4 kilobase of 5' flanking sequence and 0.7 kilobase of 3' flanking sequence was microinjected into fertilized mouse eggs. Transgenic mice were generated that are polycythemic, with increased erythrocytic indices in peripheral blood, increased numbers of erythroid precursors in hematopoietic tissue, and increased serum erythropoietin levels. Transgenic homozygotes show a greater degree of polycythemia than do heterozygotes as well as striking extramedullary erythropoiesis. Human erythropoietin RNA was found not only in fetal liver, adult liver, and kidney but also in all other transgenic tissues analyzed. Anemia induced increased human erythropoietin RNA levels in liver but not kidney. These transgenic mice represent a unique model of polycythemia due to increased erythropoietin levels.