Erythropoietin assay in mice made polycythemic by transfusion of heterologous red cells.

A simple in vivo bioassay suitable for routine testing of quality control of recombinant human erythropoietin (rHu-EPO) analogues was developed. Mice made polycythemic by intraperitoneal injection of 1.2 ml of a 80% suspension of heterologous (rat) red cells were used as assay animals and splenic 59Fe uptake as expression of the response to rHu-EPO. The assay took three days and the following schedule is proposed: 1) intraperitoneal injection of 1.2 ml of washed packed red cells obtained from donor rats, 2) subcutaneous injection of test material 4-5 h after transfusion, 3) intravenous administration of 59Fe tracer 48 h later, and 4) determination of splenic isotope uptake 6 h after injection. This method for the in vivo bioassay of rHu-EPO analogues is an economical and reliable alternative to the existing bioassays of the hormone.

Erythropoietin assay in mice made polycythemic by transfusion of heterologous red cells

A simple in vivo bioassay suitable testing of quality control of recombinant human erythropoietin (rHu-EPO) analogues was developed. Mice made polycythemic by intraperitoneal injection of 1.2 ml of a 80 per cent suspension of heterologous (rat) red cells were used as assay animals and splenic 59 Fe uptke as expression of the response to rHu-EPO. The assay took three days and the following schedule is propose: 1)intraperitoneal injection of 1.2 ml of washed packed red cells obtained from donor rats, 2) subcutaneous injection of test material 4-5 h after transfusion, 3) intravenous administration of 59 Fe tracer 48 h later, and 4) determination of splenic isotope uptake 6 h after injection. This method for the in vivo biossay of rHu-EPO analogues is an economical and reliable alternative to the existing bioassays of the hormone

Erythropoietin assay in mice made polycythemic by transfusion of heterologous red cells.

A simple in vivo bioassay suitable for routine testing of quality control of recombinant human erythropoietin (rHu-EPO) analogues was developed. Mice made polycythemic by intraperitoneal injection of 1.2 ml of a 80

suspension of heterologous (rat) red cells were used as assay animals and splenic 59Fe uptake as expression of the response to rHu-EPO. The assay took three days and the following schedule is proposed: 1) intraperitoneal injection of 1.2 ml of washed packed red cells obtained from donor rats, 2) subcutaneous injection of test material 4-5 h after transfusion, 3) intravenous administration of 59Fe tracer 48 h later, and 4) determination of splenic isotope uptake 6 h after injection. This method for the in vivo bioassay of rHu-EPO analogues is an economical and reliable alternative to the existing bioassays of the hormone.

Erythropoietin assay in mice made polycythemic by transfusion of heterologous red cells

A simple in vivo bioassay suitable testing of quality control of recombinant human erythropoietin (rHu-EPO) analogues was developed. Mice made polycythemic by intraperitoneal injection of 1.2 ml of a 80 per cent suspension of heterologous (rat) red cells were used as assay animals and splenic 59 Fe uptke as expression of the response to rHu-EPO. The assay took three days and the following schedule is propose: 1)intraperitoneal injection of 1.2 ml of washed packed red cells obtained from donor rats, 2) subcutaneous injection of test material 4-5 h after transfusion, 3) intravenous administration of 59 Fe tracer 48 h later, and 4) determination of splenic isotope uptake 6 h after injection. This method for the in vivo biossay of rHu-EPO analogues is an economical and reliable alternative to the existing bioassays of the hormone(AU)

Plasma disappearance of exogenous erythropoietin in mice under different experimental conditions.

Erythropoietin (EPO) is a glycoprotein hormone produced primarily in the kidneys and to a lesser extent in the liver that regulates red cell production. Most of the studies conducted in experimental animals to assess the role of EPO in the regulation of erythropoiesis were performed in mouse models. However, little is known about the in vivo metabolism of the hormone in this species. The present study was thus undertaken to measure the plasma tl/2 of radiolabeled recombinant human EPO (rh-EPO) in normal mice as well as in mice with altered erythrocyte production rates (EPR), plasma EPO (pEPO) titer, marrow responsiveness, red cell volume, or liver function. Adult CF-1 mice of both sexes were used throughout. For the EPO life-span studies, 30 mice in each experiment were intravenously injected with 600,000 cpm of 125l-rh-EPO and bled by cardiac puncture in groups of five every hour for 6 h. Trichloroacetic acid (TCA) was added to each plasma sample and the radioactivity in the precipitate measured in a gamma-counter. EPO, pEPO, marrow responsiveness, or red cell volume were altered by either injections of rh-EPO, 5-fluorouracil, or phenylhydrazine, or by bleeding, or red cell transfusion. Liver function was altered by CI4C administration. In the normal groups of mice, the estimated tl/2 was 182.75+/-14.4 (SEM) min. The estimated tl/2 of the other experimental groups was not significantly different from normal. These results, therefore, strongly suggest that the clearance rate of EPO in mice is not subjected to physiologic regulation and that pEPO titer can be really taken as the reflection of the EPO production rate, at least in the experimental conditions reported here.

Unexpected hypoxia-dependent erythropoietin secretion during experimental conditions not affecting tissue oxygen supply/demand ratio.

Although a great deal of evidence supports the hypothesis that plasma erythropoietin (EPO) levels of mammals are related to the oxygen supply to the tissues relative to their oxygen needs, several observation millitate against its inherent simplicity. This study presents our results obtained from in vivo experiments that suggest that hypoxia-dependent EPO production can be altered by conditions which apparently do not modify the tissue oxygen supply/demand ratio. Hypoxia-dependent EPO production rate (EPO-PR), derived from plasma EPO titers and plasma EPO half-lives, were estimated in both transfused-polycythemic and normocythemic mouse models subjected to different treatments. From calculations of the O2 carrying capacity of blood and body O2 consumption, it was assumed that the tissue supply/demand ratios were similar in both experimental and control mice of the same model at the time of induction of EPO production. The following observations were worth noting: (1) EPO-PRs in transfused polycythemic mice whose erythropoietic rates were stimulated by intermittent exposure to hypobaria (0.5 atm, 18 hr/day x 3 weeks), phenylhydrazine administration (40 mg/kg at weekly intervals x 3 weeks) or repeated rh-EPO injections (1500 U/kg 3 times a week x 3 weeks) before transfusion were more than five times high than in comparabily polycythemic mice whose erythropoietic rates were not stimulated previously; and (2) EPO-PR in response to hypobaric hypoxia was 2.08 times normal in normocythemic mice with cyclophosphamide (100 mg/kg) induced depression of erythropoiesis, and 0.33 times normal in normocythemic mice with rh-EPO (400 U/kg x 2) induced enhancement of erythropoiesis. Although the results obtained in polycythemic mice are difficult to explain, those from normocythemic mice suggest the existence of a feedback mechanism between EPO-responsive cells and EPO-producing cells. Both demonstrate the existence of experimental conditions in which modulation of the hypoxia-dependent expression of the EPO gene appears to occur. This modulation would be dependent on factors other than oxygen.

Enhanced Erythropoietin Response to Acute Hypoxemia in Mice with Pharmacological Depression of Erythropoiesis.

The recent report of a depression of stimulated production of erythropoietin (EPO) in mice with enhanced erythropoiesis suggests that unknown mechanism (s) other than hypoxia may be involved in the regulation of EPO formation. The present study was thus designed to investigate EPO production during acute hypoxemia in a mouse model in which the oxygen-carrying capacity of blood, the plasma EPO level, and the plasma EPO half-life were within normal values in spite of a marked depression of the red cell production rate (RCPR) induced by cyclophosphamide (CP) administration. Injection of 100 mg/Kg of the drug into adult female CF-1 mice that previously received 0.4 ml of packed red cells depressed markedly the 24-hour RBC 59Fe uptake without affecting the plasma immunoreactive EPO level and the plasma disappearance of 1251-labeled recombinant human EPO. The EPO production rate, calculated from the change in plasma EPO levels and the estimated EPO clearance rate, after 4 h of exposure to hypobaric air was about 2.8 times higher in mice with CP-induced inhibition of the RCPR than in mice with normal RCPR. The results support the hypothesis that the EPO production rate in mammals is not only related to the oxygen supply to the tissues relative to their oxygen needs (main stimulus) but also to the erythroid activity of the marrow (modulatory action).

Depression of stimulated erythropoietin production in mice with enhanced erythropoiesis.

BACKGROUND: The reports of lower plasma erythropoietin (EPO) in anemic patients with active erythropoiesis (hyperplastic) than in comparably anemic subjects with erythroid hypoplasia have generally been interpreted as the result of EPO utilization by the target cells of the hormone. An alternative explanation could be that there is a feedback mechanism through which EPO formation by EPO-producing cells is modulated by the erythroid activity of the erythropoietic organs. The present study was thus designed to investigate EPO production during acute hypoxemia in a mouse model in which the oxygen-carrying capacity of blood, the plasma EPO level, the blood viscosity and the plasma EPO half-life are within normal values in spite of an intense stimulation of erythropoiesis. MATERIALS AND METHODS: Adult female mice of the CF1 strain with either normal or increased rates of erythropoiesis were used in this study. Erythropoiesis was stimulated by two injections of 10 units of rhEPO given 24 h apart. All experimental determinations were performed 24 h after the second EPO injection. Erythropoiesis was measured by the percent of a tracer dose of 59Fe incorporated into the spleen. Hypobaric hypoxemia was induced by exposing mice to atmospheric air maintained at 50% atmospheric pressure for 6 h. Plasma EPO concentration was determined by RIA. Plasma disappearance of radiolabeled rhEPO was determined by i.v. injection of the hormone and sampling by cardiac puncture every hour for 6 h. RESULTS: Administration of rhEPO to mice increased splenic 59Fe uptake significantly without affecting the hematocrit, the plasma EPO level or the plasma disappearance of radiolabeled EPO. Plasma EPO titer after 6 h of exposure to hypobaric air was about 70% lower in mice with EPO-induced stimulation of erythropoiesis than in mice with normal erythropoiesis. CONCLUSIONS: The results of this study suggest that there is an inverse relationship between the rate of stimulated EPO production and erythropoietic marrow activity. They also suggest that the variations in plasma EPO levels during periods of rapidly increasing erythropoiesis are the reflection of a decrease in the rate of production rather than an increase in the rate of utilization by a proliferating pool of erythroid cells.

[HBsAG-positive mothers and neonatal immunization: experience at the USL No. 1 in Trapani]. / Madri HBsAg positive e immunizzazione dei neonati: esperienza dell'USL n. 1 di Trapani.

A vaccination campaign against HBV was undertaken by the Division of Neonatal Pathology at the Hospital of Trapani from 1984 to 1989 with the aim of reducing morbidity and mortality rates due to HBV. 6,849 women were studied in order of HBV diagnosis. Seventy-four of these (1.08%) were HBsAg positive, and 4/74 were HBeAg positive. Seventy-two high-risk newborns underwent passive immunoprophylaxis and a vaccination cycle. Antibody titres demonstrated the effectiveness of therapy in 95.1% of subjects.

[Intravenous immunoglobulins in newborn infants at risk of infection. Comparative efficacy of preparations 7S and 5S]. / Immunoglobuline intravenose in neonati a rischio settico. Efficacia comparativa di preparazioni 7S e 5S.

Some reports have been published concerning the positive effects of using intravenous immunoglobulins as immunotherapy and immunoprophylaxis of infection in newborns. The safety and efficacy of intravenously administered gamma globulins 7S versus 5S was evaluated in 64 high-risk neonates. The infants admitted to this study conformed to the following criteria: birth weight less than 1800 g and gestational age less than 34 weeks; receiving intensive care. The infants were classified into two groups: one group received IgG 7S and the other IgG 5S. The incidence of infection and the mortality rate were assessed in each group. The data show that intravenous immunoglobulin infusions of both IgG 7S and IgG 5S are both safe and effective for the prophylaxis and therapy of infection in high-risk newborns.

[Hematoma of the adrenal gland]. / Ematoma della ghiandola surrenale.

Two neonates, with a palpable mass in the loin, turned out to have adrenal haemorrhage. One of them had also hypertension and a poorly functioning kidney on the same side. None of them needed surgery.

[Epidemiologic profile of the neonatal population in Trapani]. / Profilo epidemiologico della popolazione neonatale a Trapani.

Since 1984 we utilized computer data systems to store patient information. This study examines epidemiological statistic data relative to all newborns in the Trapani's Hospital from 01.01.84 to 31.12.86 and moreover, it examines the characteristic traits of the pathologic newborns admitted in the Neonatal Intensive Care Unit in the same period, divided into inpatients (born in our hospital) and outpatients (born in other hospitals and transferred by ambulance). The elaborated data emphasized that the preterm infants (babies of less than 37 completed weeks of gestational age) is 4.55%; low birth weight infants (less than 2500 gms) rate is 5.2% with a prevalence almost alike in other regions. The prevalence of the VLBW (less than 1500 gms) significantly differs from other italian regions and european countries. The VLBW percentage, in Trapani, is steadily 1.1% of all newborns, with remarkable difference from other provinces and countries (0.32% in France, 0.5% in Marche, 0.7% in Sassari and in Trento). Besides, the rate of the newborns with weight less than 1001 gms in Trapani is 0.3%, whereas in other regions is about 0.1%. If we consider that in our case-report 59.5% of the infants dead from 0 to 28 days is made up by newborns with weight less than 1500 gms and 45.5% of them have a birth weight less than 1000 gms, if we also consider the high incidence of severe asphyxia (33.8%) in the death causes, we understand how the VLBW decrease to the levels of the other regions would bring about a remarkable decrease of the neonatal death rate.(ABSTRACT TRUNCATED AT 250 WORDS)