Bronchodilator responsiveness testing with inhaled budesonide/formoterol in asthma.

BACKGROUND: The choice of bronchodilators for responsiveness testing (BRT) is a clinical decision according to ATS/ERS. Since January 2019 we use budesonide/formoterol for BRT in asthma at our center in Argentina. The aim was to compare budesonide/formoterol with salbutamol for BRT in stable asthmatic patients that were followed up in a short-acting beta2 agonist (SABA)-free asthma center. METHODS: From the Hospital database, we found for the same patient at least one BRT using salbutamol 200 µg and another with budesonide/formoterol 320/9 µg. RESULTS: We found similar BRT between salbutamol and budesonide/formoterol in 101 asthmatic individuals (26 males) aged 38.14 ± 16.1 yrs (mean ± Standard deviation). The absolute response was 0.18 ± 0.21 L in FEV1 after salbutamol and 0.20 ± 0.22 L in FEV1 after budesonide/formoterol. Afterwards, we showed 202 patients tested with budesonide/formoterol; the mean absolute response was 0.21 ± 0.22 L in FEV1. There were no unexpected safety findings. CONCLUSIONS: In asthmatic patients, we demonstrated similar efficacy between Budesonide/formoterol and salbutamol for BRT.

Asthma-related hospitalizations after implementing SABA-free asthma management with a maintenance and anti-inflammatory reliever regimen.

Overreliance on short-acting ß2-agonists (SABA) has been a common feature of asthma management globally for at least 30 years. However, given the evidence against the long-term use of SABA, including potentially increased risk of exacerbations, emergency room visits, overall healthcare resource utilization, and mortality, the latest Global Initiative for Asthma report no longer recommends SABA only therapy. Since 2014, we implemented an ICS-containing reliever strategy at our asthma center at the G Baigorria Hospital in Argentina; we only administered budesonide/formoterol via a single inhaler device across the spectrum of asthma severity and completely eliminated the use of SABA therapy. In this article, we compare hospitalization data from our center, previously reported in the EAGLE study (when inhaled corticosteroids plus as-needed SABA was administered) for the years 1999 and 2004 with data from 2017 to 2018 (when budesonide/formoterol in a single inhaler device was administered as maintenance and/or anti-inflammatory reliever therapy [MART/AIR] without any SABA) from our center, to assess the impact of two distinct asthma management strategies on asthma-related hospitalizations. MART/AIR regimens in our SABA-free center reduced asthma hospitalizations from 9 (1999 and 2004) to 1 (2017 and 2018) (Fisher's exact test, p = 0.031; odds ratio = 0.11; 95% confidence interval [CI] = 0.013-0.98); the hospitalization rate was reduced by 92% (1.47% in 1999 and 2004 to 0.12% in 2017 and 2018). Our data provide preliminary real-world evidence that MART/AIR with budesonide/formoterol simultaneously with SABA elimination across asthma severities is an effective asthma management strategy for reducing asthma-related hospitalizations.

Leptin does not enhance cell-mediated immune responses following mycobacterial antigen stimulation.

BACKGROUND: Tuberculosis (TB) is a infectious disease characterised by a profound immune-endocrine metabolic imbalance, including a diminution in leptin plasma levels. Leptin appears to be the link between nutritional status and the development of a protective immune response. OBJECTIVE: To examine the effects of leptin on the proliferation and production of interferon-gamma (IFN-γ) by peripheral blood mononuclear cells (PBMC) in TB patients and healthy controls stimulated with mycobacterial antigens with or without leptin. As macrophages are key cells in mycobacterial containment, the effect of leptin on the production of interleukin (IL) 1ß and IL-1Ra by the monocytic cell line THP-1 was also studied. RESULTS: Leptin diminished the proliferative capacity of PBMC on mycobacterial stimulation, and had no effect on IFN-γ production in terms of measurements in culture supernatants or intracytoplasmic analysis using flow cytometry. Real-time polymerase chain reaction studies of PBMC from TB patients revealed a preserved expression of leptin receptor. Furthermore, IL-1ß and IL-1Ra secretion by THP-1 cells was not modified by leptin treatment. CONCLUSION: The study results do not support the utility of treatment with leptin to correct immune imbalances due to TB.

Estudio de los polimorfismos genéticos del gen CYP1A1 en relación a pacientes con mielomeningocele no sinddrómico / Polymorphism of gen CYP1A1 i non-syndromic myelomeningocele patients

El gen CYP1A1 codifica para el Citocromo P1 450 y se considera un candidato marcador de susceptibilidad frente a la exposición de contaminantes ambientales hidrocarburos aromáticos policíclicos (HAPs). Las formas raras mutadas en homocigosis de tres polimorfismos confieren al individuo que las porta un alto riesgo de mutagénesis, carcinogénesis o teratogénesis. Debido al uso de agroquímicos en los cultivos de la Provincia de Misiones nos propusimos investigar la distribución de las frecuencias alélicas de los polimorfismos msp1 y del exon 7 del gen en poblaciones normales no aborígenes argentinas y chilenas y en una población de pacientes con mielomeningocele (MMC) no sindrómico, para correlacionarlas con los fenotipos de detoxificación ya descriptos por nosotros en publicaciones anteriores, en poblaciones controles y co MMC, identificando población de riesgo,contribuyendo al Screening Internacional del Proyecto Genoma Ambiental y poder realizar profilaxis. se obtuvo ADN de linfocitos de sangre periférica en 100 controles sanos argentinos y 100 chilenos y en 31 pacientes argentinos con MMC. Se amplificó el exon 7 CYP1A1, con la técnica de reacción en cadena de polimerasa (PCR) con ASO, para un polimorfismo. Para el otro denominado MSP1 , se amplificó el ADN con PCR-RFLP. Los productos se visualizaron en electroforesis en gel de agarosa al 1,8% con tinción con Bromuro de Etidio y se identificaron las variables alélicas. se hallaron los siguientes resultados: polimorfismos del exon 7: población argentina con 47% homocigota normal; 43% heterocigota y 10% homocigota mutado; población chilena con 25.8% , 61,3% y 12,9%, respectivamente (p<0,05%), siendo en cada caso el homocigota salvaje de bajo riesgo; el heterocigota de riesgo intermedio y monocigota mutado de ato riego o susceptibilidad frente a la exposición co HPAs. Las frecuencias genotipicas argentinas y chilenas halladas son significativamente diferentes.

In vivo erythroid recovery following paclitaxel injury: correlation between GATA-1, c-MYB, NF-E2, Epo receptor expressions, and apoptosis.

Paclitaxel (Px) is a cancer chemotherapeutic agent that causes bone marrow (BM) cytotoxicity by microtubule stabilization and by modifications in the expression of several genes. Hematopoietic progenitors show severe alterations following Px injury. Erythropoietic recovery should be accompanied by changes in the expression of transcription factors such as c-MYB, GATA-1, NF-E2, Bcl-x(L), and erythropoietin receptor (Epo-R). The aim of this work was to study the in vivo recovery of erythropoiesis and to correlate transcription factors, Bcl-x(L), and Epo-R expressions to apoptosis and changes in proliferation of murine erythroid progenitors following a single dose of Px (29 mg/kg, i.p.). BM total and differential cellularities, apoptosis (TdT-mediated dUTP Nick-End Labeling [TUNEL] assay), clonogenic assays, and immunoblots for transcription factors, Epo-R, and Bcl-x(L) were performed each day for 5 days post-injury. Apoptosis (24 +/- 0.81%, P < 0.01), inhibition of colony growth (burst-forming units-erythroid [BFU-E] and granulocyte-erythroid-macrophage [GEM]), and decrease in BM cellularities (28 +/- 4.2% of control) were maximal at 24 h following Px. The highest apoptosis was concomitant with the lowest BM cellularities. Apoptosis returned to normal values (3.08 +/- 0.61%) by day 3 post-Px. Up-regulation of c-MYB, GATA-1, Epo-R, and Bcl-x(L) expressions were observed between 24 and 48 h following Px. Correlations among c-MYB, GATA-1, Bcl-x(L), and Epo-R were extremely significant. Maximal expression of NF-E2 was observed on day 3 concomitant with the rise (threefold) of early erythroid precursors (BFU-E). Thus, cells that survive injury seem to be stimulated to produce early (24-48 h) erythroid-related and antiapoptotic proteins. Therefore, the results suggest an in vivo interplay between specific transcription factors and Bcl-x(L) during progenitor cell survival and proliferation; mechanisms triggered to restore size and composition of the erythroid compartment.

Hematotoxicity induced by paclitaxel: in vitro and in vivo assays during normal murine hematopoietic recovery.

Paclitaxel is a drug widely used in several oncological trials. Like other antineoplastics, it causes severe neutropenia. However, its effects on erythropoiesis are not as well known. This study analyzes the recovery of normal murine hematopoiesis after single dose paclitaxel administration (29 mg/kg i.p.) over 20 days. Different assays were used to analyze the restorative kinetics from primitive early progenitors to mature functional erythroid cells. Proliferation of the erythroid compartment was assessed by DNA microculture assays in medullar and splenic cells stimulated with recombinant human erythropoietin (rh Epo 0-500 mU/ml). Enhancement of early hematopoietic progenitors was determined using clonogenic assays and erythroid terminal maturation by 59Fe incorporation. Peripheral hematologic parameters and cellularities in both tissues were also determined on each day of the experimental schedule. At 2 days post-paclitaxel treatment, medullar cellularity diminished drastically (> 90%) and 59Fe incorporation decreased in all compartments. DNA assay revealed maximum sensitivity to Epo (p < 0.05 with 15 mU/ml) while clonogenic cultures failed to show significant results. At 5 days both bone marrow and spleen semisolid cultures showed great expansion of early hematopoietic progenitors (about 5- and 83-fold. respectively). Hormonal sensitivity decreased progressively along the experiment. Splenic cultures showed a linear dose-response to rh Epo at day 5 post-paclitaxel administration (p < 0.05 with 125 mU/ml). Medullar and splenic total progenitor colony-forming units (CFU) scorings with and without rh Epo revealed a notable enhancement at 5 days post-paclitaxel treatment. Data from this study suggest that paclitaxel causes deep injury in the erythropoietic compartment, including temporary variations of Epo sensitivity in late bone marrow erythroid progenitors, early multilineage hematopoietic explosion and terminal erythroid precursors depletion as a result of a complex microenvironmental restitutive regulation.

Expression of scinderin in megakaryoblastic leukemia cells induces differentiation, maturation, and apoptosis with release of plateletlike particles and inhibits proliferation and tumorigenesis.

Rapid proliferation of atypical megakaryoblasts is a characteristic of megakaryoblastic leukemia. Cells from patients with this disorder and cell lines established from this type of leukemia showed the presence of gelsolin but the absence of scinderin expression, 2 filamentous actin-severing proteins present in normal megakaryocytes and platelets. Vector-mediated expression of scinderin in the megakaryoblastic cell line MEG-01 induced a decrease in both F-actin and gelsolin. This was accompanied by increased Rac2 expression and by activation of the PAK/MEKK.SEK/JNK/c-jun, c-fos transduction pathway. The Raf/MEK/ERK pathway was also activated in these cells. Transduction pathway activation was followed by cell differentiation, polyploidization, maturation, and apoptosis with release of platelet-like particles. Particles expressed surface CD41a antigen (glycoprotein IIb/IIIa or fibrinogen receptor), had dense bodies, high-affinity serotonin transport, and circular array of microtubules. Treatment of particles with thrombin induced serotonin release and aggregation that was blocked by CD41a antibodies. PAC-1 antibodies also blocked aggregation. Exposure of cells to PD98059, a blocker of MEK, inhibited antigen CD41a expression, increases in cell volume, and number of protoplasmic extensions. Cell proliferation and cell ability to form tumors in nude mice were also inhibited by the expression of scinderin. MEG-01 cells expressing scinderin had the same fate in vivo as in culture. Thus, when injected into nude mice, they entered apoptosis and released platelet-like particles. The lack of scinderin expression in megakaryoblastic leukemia cells seems to be responsible for their inability to enter into differentiation and maturation pathways characteristic of their normal counterparts.

Myristoylated alanine-rich C kinase substrate phosphorylation is involved in thrombin-induced serotonin release from platelets.

Stimulation of platelets by thrombin induces protein kinase C (PKC) activation, phosphorylation of pleckstrin, aggregation and serotonin release. Here, we demonstrate that, in human platelets, thrombin stimulation also induced phosphorylation of the myristoylated alanine-rich C kinase substrate (MARCKS) and serotonin release in intact and digitonin-permeabilized platelets. MARCKS is known to bind actin and cross-link actin filaments, and this is inhibited by PKC-evoked MARCKS phosphorylation. MARCKS phosphorylation and serotonin release in response to increasing concentrations of thrombin have a similar EC50 and time course and, in permeabilized platelets, peptide MPSD, with an amino acid sequence corresponding to the phosphorylation site domain of MARCKS, blocked both responses. However, pleckstrin and myosin light chain phosphorylations were not modified. Ala-MPSD, in which the four serine residues of MPSD were substituted by alanines was ineffective. The results suggest a role for MARCKS in platelet secretion. The fact that pleckstrin phosphorylation has a different time course and was not modified in the presence of MPSD when MARCKS phosphorylation and serotonin release were inhibited would suggest either that pleckstrin phosphorylation is unrelated to secretion or that it might only be involved upstream in the events leading to secretion.

[In vitro and in vivo studies of murine erythropoietic recovery after treatment with cyclophosphamide]. / Estudios in vitro e in vivo de la recuperación eritropoyética murina post-tratamiento con ciclofosfamida.

OBJECTIVES: The aim of this study is to analyse functional changes in murine erythropoietic tissues over 20 days post cyclophosphamide (CY) treatment. The project was focused on the capability of femoral and splenic erythropoietic responsive cells (ERC) to proliferate with human recombinant erythropoietin (rh Epo) stimulation after cytotoxic treatment. MATERIALS AND METHODS: CF-1 mice were injected i.p. with CY (200 mg/Kg). Individual lots were studied at 0, 2, 5, 7, 10, 14, 17 and 20 days post cytotoxic treatment. Haematologic parameters [packed red cells (PRC) reticulocytes, white blood cells] were scored. Erythropoietic differentiation was assessed by the 59Fe uptake assay and the proliferative profiles of erythropoietic progenitors were determined by 3H-thymidine incorporation assay with several doses of rh Epo (0-250 mU/mL). Total and differential cellularities were scored in bone marrow (BM) and spleen. RESULTS: A drastical decrease of total nucleated BM cells was noticed at 2 days post CY, although cellularity was restored by the 7th day. Spleen, however, failed in showing significant decrease. The maintenance of PRC was achieved through a deep erythropoietic reorganization. 59Fe uptake revealed changes in erythroid differentiation in both tissues. Spleen maturative contribution to whole erythropoiesis was always less than medullary supply, except on day 10 post CY when a transient compensatory red cell contribution was noticed. Proliferative assays revealed that erythropoietic recovery in BM post CY was delayed in comparison with myelopoietic restoration. Splenic erythroid proliferative pattern correlated with differentiation data. CONCLUSIONS: Myelopoietic and erythropoietic progenitors showed different recovery patterns post CY administration in BM and spleen. Medullary hemopoietic lineages restoration described a particular sequence: myelopoiesis restitution was previous to the erythroid one. Medullary erythropoiesis occurred without drastic changes in erythropoietin sensitivity while the spleen showed a transient dramatic increment on 10 days post CY red proliferation. Experimental data strongly suggest that erythropoietic recovery after CY insult mainly depends on microenvironmental regulations rather than on hormone titers.

Effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on murine bone marrow and spleen erythropoiesis.

100 micrograms/kg of recombinant human granulocyte colony-stimulating factor was injected twice daily into normal adult CF1 female mice for a period of 15 days. After that time we have observed a decrease 59Fe marrow incorporation with a parallel increase in the spleen. During the first 9 days the marrow plus spleen erythroid cells number decreased to 60% of control approximately, but recovered thereafter and were not significantly different from normal values at 12-15 days. In addition, our studies demonstrate that the spleen erythropoiesis is quantitatively more important at the final time than marrow erythropoiesis. For this reason, splenic compensatory erythropoiesis maintained the hematocrit values between normal ranges. Regarding the granulocytic compartment, 15 days of rhG-CSF treatment produce a marked increase in total count of splenic granulocytes (a 7.7 fold rise from control values). Marrow granulocytes shows a 2-fold increment, but considering the absolute counts, bone marrow still was predominant as a granulopoieitc organ. Our results indicate that the spleen is a more important erythropoietic organ than marrow after 15 days of rhG-CSF treatment.

Effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on murine bone marrow and spleen erythropoiesis

100 mug/kg of recombinant human granulocyte colony ¹ stimulating factor was injected twice daily into normal adult CF1 female mice for a period of 15 days. After that time was have observed a decrease (59)Fe marrow incorporation with a parallel increase in the spleen. During the first 9 days the marrow plus spleen erythroid cells number decreased to 60 percent of control approximately, but recovered thereafter and were not significantly different from normal values at 12 ¹ 15 days. In addition, our studies demonstrate that the spleen erythropoiesis is quantitatively more important at the final time tham marrow erythropoiesis. For this reason, splenic compensatory erythropoiesis maintained the hematocrit values between normal ranges. Regarding the granulocytic compartment, 15 days of rhG-CSF treatment produce a marked increase in total count os splenic granulocytes (a 7.7 fold rise from control values). Marrow granulocytes shows a 2 ¹ fold increment, but considering the absolute counts, bone marrow still was predominant as a granulopoieitc organ. Our results indicate that the spleen is a more important erythropoietic organ than marrow after 15 days of rhG-CSF treatment. (AU)

Effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on murine bone marrow and spleen erythropoiesis

100 mug/kg of recombinant human granulocyte colony - stimulating factor was injected twice daily into normal adult CF1 female mice for a period of 15 days. After that time was have observed a decrease (59)Fe marrow incorporation with a parallel increase in the spleen. During the first 9 days the marrow plus spleen erythroid cells number decreased to 60 percent of control approximately, but recovered thereafter and were not significantly different from normal values at 12 - 15 days. In addition, our studies demonstrate that the spleen erythropoiesis is quantitatively more important at the final time tham marrow erythropoiesis. For this reason, splenic compensatory erythropoiesis maintained the hematocrit values between normal ranges. Regarding the granulocytic compartment, 15 days of rhG-CSF treatment produce a marked increase in total count os splenic granulocytes (a 7.7 fold rise from control values). Marrow granulocytes shows a 2 - fold increment, but considering the absolute counts, bone marrow still was predominant as a granulopoieitc organ. Our results indicate that the spleen is a more important erythropoietic organ than marrow after 15 days of rhG-CSF treatment.

Proliferative and maturative behaviour patterns on murine bone marrow and spleen erythropoiesis along hypoxia.

The present study was performed to determine quantitative and qualitative effects of hypoxia on murine erythron. CF1 mice were submitted to hypobaric hypoxia (HH) along 18 days. The proliferative response to recombinant human erythropoietin (rHuEPO: 0-250 mU/ml) was analyzed by DNA assays from bone marrow and spleen cells at different times. Bone marrow proliferative response showed a slight increment under stress but remained over control by the end of the experience. Splenic erythroid proliferative response was observed at a maximum rate on day 6 of HH (26 fold) and returned near to control values after day 10. The assessment of erythropoietic maturative pattern was performed by 59Fe uptake assays. Total nuclear cell counts increased in both tissues (1.5 times in marrow and 5 times in spleen) under hypoxia. In addition, percentages of different lineages (erythroid, myeloid and lymphoid) were scored. Total erythroid marrow cell counts increased in a narrowly degree and persisted above basal counts after day 18. Meanwhile, splenic red cells rose to 30 times over control on day 6 and failed sharply near control values from day 12 of HH. Splenic red cells contribution was approximately 60% of total production between 6-8 days. By the end of the assay bone marrow took back erythroid command (90%). These findings indicate correlation between the time course as well as quantitative and qualitative parameters in the patterns of proliferation and maturation. Moreover, the erythron response to hypoxia, seemed to be related to microenvironmental regulations rather than to hormonal variances.

Murine splenic proliferative response to human recombinant erythropoietin along hypoxia.

Hypoxia is the best physiological stress to disturb the erythropoietic steady state. The present study has been undertaken in the aim to analize the splenic erythropoietic proliferative response with different doses of recombinant human erythropoietin under hypoxic conditions along 18 days using the DNA synthesis assay. Normoxic splenic progenitors failed to show significative erythroid replication at 0 days. A clearly rh Epo response was noticed from 2 to 8 days of hypoxia. Splenic proliferation returned to basal pattern from 10 days to the end of the experience. The highest proliferative activity, 25 fold increase over control (p < 0.001), was found at 6 days from 62.5 to 250 mU/ml rh Epo. These results support suggestions that hypoxia induces a transiently erythroid splenic proliferative response changing its quantitative parameters in the Epo dose-response relationship during the physiological adaptation.

Respuesta esplénica murina a eritropoyetina humana recombinante en función de la hipoxia / Response splenic murine to recombinant human erythropoietin in function of hypoxia

La hipoxia es un estímulo que perturba el equilibrio hemopoyético, particularmente el compartimiento eritroide. Ante esta situación el sistema se acomoda para asimilar las variaciones del medio estableciendo un nuevo estado de equilibrio. Este trabajo se diseñó para analizar la variación de sensibilidad de las células esplénicas a distintas concentraciones de eritropoyetina humana recombinante (rh Epo), sometiendo al animal donante a diferentes tiempos de hipoxia y midiendo la respuesta proliferativa por la incorporación de timidina triatiada (3-HdTR). Los progenitores esplénicos muestran índices de estimulación crecientes en función de la hipoxia con un máximo entre 6 y 8 días. A partir de allí desciende la capacidad proliferativa eritroide del bazo. La actividad máxima se verifica con 32,5 y 62,5 rh-Epo mU/ml. La hipoxia cambia el comportamiento eritroideo esplénico con una actividad máxima entre los 6 y 8 días, expresado entre otras variables por un aumento de la proliferación de los progenitores eritroides hasta 25 veces los valores control. Estos resultados sugieren que bajo strees hemopoyético (hipoxia) las células esplénicas exhiben un incremento de sensibilidad a la rh Epo en forma transitoria (AU)

Murine splenic proliferative response to human recombinant erythropoietin along hypoxia

La hipoxia constituye el mejor stress fisiológico para la pertubación del estado estacionario eritropoyético. El present estudio tiende a analizar la respuesta proliferativa eritropoyética esplénica con diferentes dosis de eritropoyentina humana recombinante bajo condiciones hipóxicas a lo largo 18 días mediante el ensayo de síntesis del DNA. Los progenitores esplénicos normóxicos no sufren proliferación eritroide significativa al día 0. Una clara respuesta proliferativa a rh Epo se verificó entre los 2 y 8 días de hipoxia. La proliferación de los progenitores eritroides esplénicos hipóxicos retornó a un patrón basal desde los 10 días hasta el final de la experiencia. La mayor creatividad proliferativa, 25 veces sobre el control (p<0.001), se produjo a los 6 días de condicionamiento desde 62.5 hasta 250mU/ml de rh Epo. estos resultados son concordantes con el concepto que durante la daptación fisiológica a la hipoxia, las células progenitoras eritroides esplénicas modifican transitoriamente su tasa proliferativa observable por variaciones en la relación dosis-respueta a Epo

Respuesta esplénica murina a eritropoyetina humana recombinante en función de la hipoxia / Response splenic murine to recombinant human erythropoietin in function of hypoxia

La hipoxia es un estímulo que perturba el equilibrio hemopoyético, particularmente el compartimiento eritroide. Ante esta situación el sistema se acomoda para asimilar las variaciones del medio estableciendo un nuevo estado de equilibrio. Este trabajo se diseñó para analizar la variación de sensibilidad de las células esplénicas a distintas concentraciones de eritropoyetina humana recombinante (rh Epo), sometiendo al animal donante a diferentes tiempos de hipoxia y midiendo la respuesta proliferativa por la incorporación de timidina triatiada (3-HdTR). Los progenitores esplénicos muestran índices de estimulación crecientes en función de la hipoxia con un máximo entre 6 y 8 días. A partir de allí desciende la capacidad proliferativa eritroide del bazo. La actividad máxima se verifica con 32,5 y 62,5 rh-Epo mU/ml. La hipoxia cambia el comportamiento eritroideo esplénico con una actividad máxima entre los 6 y 8 días, expresado entre otras variables por un aumento de la proliferación de los progenitores eritroides hasta 25 veces los valores control. Estos resultados sugieren que bajo strees hemopoyético (hipoxia) las células esplénicas exhiben un incremento de sensibilidad a la rh Epo en forma transitoria

Murine splenic proliferative response to human recombinant erythropoietin along hypoxia

La hipoxia constituye el mejor stress fisiológico para la pertubación del estado estacionario eritropoyético. El present estudio tiende a analizar la respuesta proliferativa eritropoyética esplénica con diferentes dosis de eritropoyentina humana recombinante bajo condiciones hipóxicas a lo largo 18 días mediante el ensayo de síntesis del DNA. Los progenitores esplénicos normóxicos no sufren proliferación eritroide significativa al día 0. Una clara respuesta proliferativa a rh Epo se verificó entre los 2 y 8 días de hipoxia. La proliferación de los progenitores eritroides esplénicos hipóxicos retornó a un patrón basal desde los 10 días hasta el final de la experiencia. La mayor creatividad proliferativa, 25 veces sobre el control (p<0.001), se produjo a los 6 días de condicionamiento desde 62.5 hasta 250mU/ml de rh Epo. estos resultados son concordantes con el concepto que durante la daptación fisiológica a la hipoxia, las células progenitoras eritroides esplénicas modifican transitoriamente su tasa proliferativa observable por variaciones en la relación dosis-respueta a Epo (AU)

Murine splenic proliferative response to human recombinant erythropoietin along hypoxia.

Hypoxia is the best physiological stress to disturb the erythropoietic steady state. The present study has been undertaken in the aim to analize the splenic erythropoietic proliferative response with different doses of recombinant human erythropoietin under hypoxic conditions along 18 days using the DNA synthesis assay. Normoxic splenic progenitors failed to show significative erythroid replication at 0 days. A clearly rh Epo response was noticed from 2 to 8 days of hypoxia. Splenic proliferation returned to basal pattern from 10 days to the end of the experience. The highest proliferative activity, 25 fold increase over control (p < 0.001), was found at 6 days from 62.5 to 250 mU/ml rh Epo. These results support suggestions that hypoxia induces a transiently erythroid splenic proliferative response changing its quantitative parameters in the Epo dose-response relationship during the physiological adaptation.

The mechanism of the transient depression of the erythropoietic rate induced in the rat by a single injection of uranyl nitrate.

With the purpose of assessing the effect of uranyl nitrate (UN) on the rate of erythropoiesis, 1 mg/kg of the compound was injected iv to adult female Wistar rats. The dosing vehicle was injected into control animals. A single injection of UN induced a transient depression of the rate of red cell volume 59Fe uptake, which reached its lowest value (68% depression) by the seventh postinjection day. By 14 days, 59Fe incorporation had returned to normal. The amount of iron going to erythroid tissue per hour, reticulocyte count, and immunoreactive erythropoietin concentration in both plasma and kidney extracts were also significantly depressed in UN-treated rats in relation to these values in vehicle-injected rats by the seventh postinjection day. Dose-response curves for exogenous erythropoietin (Epo) performed in polycythemic intact and UN-treated rats 7 days after drug injection revealed a significant depression of the response in UN-injected animals. Moreover, bone marrow cells obtained from rats pretreated with UN formed a reduced number of erythroid colonies in vitro in response to Epo. Therefore, possible mechanisms for the observed transient depression in the rate of erythropoiesis associated with acute UN treatment include decreased Epo production and direct or indirect damage of erythroid progenitor cells.