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Submitted by Priscila Nascimento (pnascimento@icict.fiocruz.br) on 2012-11-29T13:14:34Z No. of bitstreams: 1 ana-paula-araujo.pdf: 1867740 bytes, checksum: ab9d7b2866753474ebe7ecb95d8e32d9 (MD5) / Made available in DSpace on 2012-11-29T13:14:34Z (GMT). No. of bitstreams: 1 ana-paula-araujo.pdf: 1867740 bytes, checksum: ab9d7b2866753474ebe7ecb95d8e32d9 (MD5) Previous issue date: 2011 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil. / A eritropoetina (EPO) é um hormônio produzido, principalmente, pelos rins, que regula a produção de células vermelhas do sangue. Trata-se de uma glicoproteína com 166 aminoácidos, três sítios de N-glicosilação e um de O-glicosilação. Apresenta massa molecular na faixa de 30-34 kDa, sendo aproximadamente 40% correspondente aos glicídeos. A EPO está disponível como agente terapêutico produzido através da tecnologia do DNA recombinante em cultura de células de mamíferos. A EPO humana recombinante (rHuEPO) é usada para o tratamento de anemia associada à insuficiência renal crônica. Devido a relevância médica da rHuEPO, sua produção está sendo nacionalizada através do processo de transferência de tecnologia do Centro de Inmunología Molecular (CIM), de Cuba, para o Instituto de Tecnologia de Imunobiológicos (Bio-Manguinhos)/FIOCRUZ. O controle de qualidade sobre o processo produtivo da rHuEPO e seu produto final é bastante rigoroso. Neste contexto, o mapeamento peptídico é um dos mais importantes ensaios usados no controle em processo da produção de proteínas recombinantes. Este ensaio assegura a integridade da estrutura primária das proteínas ao final das etapas de suas purificações. Sendo assim, o objetivo desta dissertação de mestrado foi definir uma metodologia de mapeamento peptídico da rHuEPO, visando o controle de processo da produção deste biofármaco em Bio-Manguinhos. Previamente, a preparação da rHuEPO fornecida pelo CIM foi avaliada quanto a sua homogeneidade e caracterizadapor eletroforeses em gel de poliacrilamida, cromatografia de fase reversa, cromatofocalização eespectrometria de massa. Para obter os peptídeos da rHuEPO, a hidrólise enzimática desta glicoproteína com a enzima tripsina foi avaliada em diferentes tempos de incubação e com relações enzima/substrato distintas. O fracionamento dos peptídeos foi feito por cromatografia líquida de fase reversa em coluna C18, empregando-se diferentes colunas cromatográficas e gradientes de eluição. As principais frações peptídicas isoladas da cromatografia de fase reversa foram analisadas por espectrometria de massa a fim de comprovar a identidade dos peptídeostrípticos da rHuEPO. A especificidade da metodologia desenvolvida foi avaliada através da comparação dos perfis peptídicos do hidrolisado tríptico da rHuEPO e do quimotripsinogênio A. A hidrólise tríptica usando-se relação enzima/substrato de 1/50 (p/p), concentração de rHuEPO de 1 mg/mL e incubação de 1 hora a 37o C hidrolisou mais de 99% da glicoproteína. As colunas cromatográficas de fase reversa Hi-Pore RP 318, Vydac 218TP C18 e Delta Pak C18 se mostraram aptas para o fracionamento dos peptídeos trípticos da rHuEPO. Em comparação à metodologia usada no CIM, o tempo de incubação de hidrólise foi reduzido em, pelo menos,2 horas e a duração da corrida cromatográfica para obtenção do mapa peptídico diminuiu em, pelo menos, 1 hora e 42 minutos. Na análise por espectrometria de massa das frações isoladas da cromatografia de fase reversa, seis peptídeos trípticos da rHuEPO foram observados. Tais frações peptídicas foram identificadas como pertencentes à EPO humana pelo programa Mascot Search Results. Dessa forma, ficou estabelecida uma metodologia de mapeamento peptídico especifica, simples e rápida para ser utilizada no controle em processo da produção da rHuEPO em Bio-Manguinhos. / Erythropoietin (EPO) is a hormone produced mainly by the kidney that regulates the production of red blood cells. It is a glycoprotein with 166 amino acids, three N-glycosylation and one O-glycosylation sites. It has a molecular weight in the range of 30-34 kDa, being approximately 40% of its content corresponding to carbohydrates. EPO is available as a therapeutic agent produced by recombinant DNA technology in mammaliancell culture. The recombinant human EPO (rHuEPO) is used to treat anemia associated with chronic renal disease. Due to rHuEPO medical relevance, its production technology is a subject of transference from the Centro de Inmunología Molecular(CIM), Cuba, to the Instituto de Tecnologia em Imunonobiologicos(Bio-Manguinhos)/FIOCRUZ. The quality control over production process of rHuEPO and its final product is quite rigorous. In this context, peptidemapping is one of the most important tests used in process control of recombinant proteins production. This test ensures the primary structure integrity of a protein after its purification processes. Thus, the objective of this dissertation was to define a methodology for peptide mapping of rHuEPO aiming to be used in the process control of this biopharmaceutical production in Bio-Manguinhos. Previously, the preparation of rHuEPO provided by CIM was characterized by polyacrylamidegel electrophoresis, reversed phase chromatography, chromatofocusing and mass spectrometry. In order to obtain rHuEPO peptides, the enzymatic hydrolysis of this glycoprotein with the enzyme trypsin was assessed at differents incubation times and enzyme/substrate ratio. Peptides fractionation was performed by reverse phase liquid chromatography, using distincts C18 columns and elution gradients. The main peptide fractions from reversed phase chromatography were analyzed by mass spectrometry to confirm the identity of rHuEPO tryptic peptides. The specificity of the developed methodology was evaluated by comparing peptides profiles from rHuEPO and Chymotrypsinogen A tryptic hydrolysates. The tryptic digestion using enzyme/substrate ratio of 1/50 (w/w), substrate concentration of 1 mg/mL and incubation for 1 hour at 37°C hidrolysated more than 99% of the glicoprotein. The reversed phase columns Hi-Pore RP318, Vydac 218TP C18 e Delta Pak C18 were able to fractionate the rHuEPO tryptic peptides. Compared to the methodology used in CIM, the hydrolysis incubation time was reduced by at least 2 hours and the chromatographic running time to obtain the peptide map was decreased by at least 1 hour and 42 minutes. The mass spectrometry analysis of the fractions isolated from reversed-phase chromatography showed six tryptic peptides of rHuEPO. These peptide fractions were identified as belonging to human EPO by the program Mascot Search Results. Thus it was established an specific, simple and fast peptide mapping methodology to use in process control of rHuEPO in Bio-Manguinhos.

O estudo teve como objetivo avaliar a razão de custo-efetividade, sob a perspectiva do Sistema Único de Saúde SUS, do tratamento da anemia de pacientes em Terapia Renal Substitutiva. Duas alternativas foram comparadas: um novo medicamento recentemente registrado no Brasil, o Ativador Contínuo de Receptor de Eritropoetina (Continuous Erythropoietin Receptor Activator), CERA, e outro, atualmente disponível no sistema de saúde brasileiro, a Eritropoetina Recombinante Humana - Epo-rHu. Métodos: Um modelo de Markov simulou o curso de uma coorte de pacientes em Terapia Renal Substitutiva tratados com CERA e Epo-rHu por quatro anos. A qualidade de vida associada ao uso dos medicamentos foi estimada de forma indireta, por meio de entrevista qualificada com os profissionais cuidadores, previamente submetida e aprovada pelo Comitê de Ética em Pesquisa local. Foi realizada análise de sensibilidade no modelo proposto através da variação dos parâmetros: dose dos medicamentos, custo das estratégias, taxa de desconto e efetividade utilizados para sua construção. Resultados: A média da qualidade de vida atribuída aos pacientes tratados foi 6,3 para a Epo-rHu, 7,8 para o CERA e 9,3 para os pacientes transplantados. O modelo demonstrou que a estratégia mais custo-efetiva é a terapêutica com a Epo-rHu, com um custo por QALY de R$ 21.052,00. O custo incremental por QALY ganho associado ao CERA foi de R$ 72.974,00. Conclusão: A utilização mensal do medicamento CERA está associada à maior qualidade de vida quando comparada a Epo-rHu. No entanto, a terapia com o novo medicamento não se mostrou mais custo-efetiva frente ao tratamento com Epo-rHu / This study sought to determine the cost-effectiveness of anemia treatment in dialysis patients for Brazilian Public Health System. Two alternatives were compared: a new drug, the Continuous Erythropoietin Receptor Activator, CERA, recently registred in Brazil, and another one, provided nowadays by the National Health System, Epo-rHu (Recombinant Human Eythropoietin). Methods: A Markov cohort of dialysis patients treated with CERA and Epo-rHu for four years was used to perform the base case analysis. The model outputs were QALYs and costs. The quality of life associated with each drug was measured by interviews applied to health care professionals. These interviews were previously submitted and approved by the local ethics committee. A sensitivity analysis was applied to the model to test it, varying the values of drugs dosage, costs, discount rate and effectiveness. Results: The average quality of life assigned by health care professionals to the patients treated with Epo-rHu, CERA and to kidney transplant receptors were respectively 6,3, 7,8 and 9,3. The model showed that Epo-rHu treatment was more cost-effective than CERA treatment. The cost-effectiveness ratio of Epo-rHu therapy was R$ 21.052,00. In addition, the cost per QALY gained of CERA therapy was R$ 72.974,00. Conclusion: Anemia treatment with CERA is associated with improvement in quality of life compared to Epo-rHu therapy. However, the new drug is not more cost-effective than the drug provided by the Brazilian Public Health System

O estudo teve como objetivo avaliar a razão de custo-efetividade, sob a perspectiva do Sistema Único de Saúde SUS, do tratamento da anemia de pacientes em Terapia Renal Substitutiva. Duas alternativas foram comparadas: um novo medicamento recentemente registrado no Brasil, o Ativador Contínuo de Receptor de Eritropoetina (Continuous Erythropoietin Receptor Activator), CERA, e outro, atualmente disponível no sistema de saúde brasileiro, a Eritropoetina Recombinante Humana - Epo-rHu. Métodos: Um modelo de Markov simulou o curso de uma coorte de pacientes em Terapia Renal Substitutiva tratados com CERA e Epo-rHu por quatro anos. A qualidade de vida associada ao uso dos medicamentos foi estimada de forma indireta, por meio de entrevista qualificada com os profissionais cuidadores, previamente submetida e aprovada pelo Comitê de Ética em Pesquisa local. Foi realizada análise de sensibilidade no modelo proposto através da variação dos parâmetros: dose dos medicamentos, custo das estratégias, taxa de desconto e efetividade utilizados para sua construção. Resultados: A média da qualidade de vida atribuída aos pacientes tratados foi 6,3 para a Epo-rHu, 7,8 para o CERA e 9,3 para os pacientes transplantados. O modelo demonstrou que a estratégia mais custo-efetiva é a terapêutica com a Epo-rHu, com um custo por QALY de R$ 21.052,00. O custo incremental por QALY ganho associado ao CERA foi de R$ 72.974,00. Conclusão: A utilização mensal do medicamento CERA está associada à maior qualidade de vida quando comparada a Epo-rHu. No entanto, a terapia com o novo medicamento não se mostrou mais custo-efetiva frente ao tratamento com Epo-rHu / This study sought to determine the cost-effectiveness of anemia treatment in dialysis patients for Brazilian Public Health System. Two alternatives were compared: a new drug, the Continuous Erythropoietin Receptor Activator, CERA, recently registred in Brazil, and another one, provided nowadays by the National Health System, Epo-rHu (Recombinant Human Eythropoietin). Methods: A Markov cohort of dialysis patients treated with CERA and Epo-rHu for four years was used to perform the base case analysis. The model outputs were QALYs and costs. The quality of life associated with each drug was measured by interviews applied to health care professionals. These interviews were previously submitted and approved by the local ethics committee. A sensitivity analysis was applied to the model to test it, varying the values of drugs dosage, costs, discount rate and effectiveness. Results: The average quality of life assigned by health care professionals to the patients treated with Epo-rHu, CERA and to kidney transplant receptors were respectively 6,3, 7,8 and 9,3. The model showed that Epo-rHu treatment was more cost-effective than CERA treatment. The cost-effectiveness ratio of Epo-rHu therapy was R$ 21.052,00. In addition, the cost per QALY gained of CERA therapy was R$ 72.974,00. Conclusion: Anemia treatment with CERA is associated with improvement in quality of life compared to Epo-rHu therapy. However, the new drug is not more cost-effective than the drug provided by the Brazilian Public Health System

Erythropoietin (Epo) modulates red blood cell production (erythropoiesis) by binding to its receptor and activating STAT5, a Signal Transducer and Activator of Transcription (STAT) protein implicated in both basal and stress erythropoiesis. Epo concentration in serum changes over three orders of magnitude, as it regulates basal erythropoiesis and its acceleration during hypoxic stress. However, it is not known how STAT5 translates the changes in Epo concentration into the required erythropoietic rates. We addressed this question by studying STAT5 phosphorylation, at the single cell level, in developing erythroblasts. We divided erythroid progenitors in tissue into several flow-cytometric subsets and found that each of them exhibited distinct modes of Stat5 activation, based on their developmental stage. STAT5 activation is bistable in mature erythroblasts, resulting in a binary (or digital), low-intensity STAT5 phosphorylation signal (p-Stat5). In early erythroblasts, and in response to stress levels of Epo, the low intensity bistable p-Stat5 signal is superseded by a high-intensity graded, or analog, signal. The gradual shift from high-intensity graded signaling in early erythroblasts to low intensity binary signaling in mature erythroblasts is due to a decline in STAT5 expression with maturation. We were able to convert mature, digital transducing erythroblasts into analog transducers simply by expressing high levels of exogenous STAT5. We found that EpoR-HM mice, expressing a mutant EpoR that lacks STAT5 docking sites, generate the binary, but not the analog, STAT5 signal. Unlike Stat5-null mice, which die perinatally, the EpoR-HM mice are viable but deficient in their response to stress, demonstrating that while binary STAT5 signaling is sufficient to support basal erythropoiesis, analog signaling is required for the stress response. Bistable systems contain a positive loop, which is important for flipping the switch between the two stable ‘on’ or ‘off’ states. We show that bistable activation is the result of an autocatalytic loop in which active STAT5 promotes further STAT5 activation. The isolated STAT5 N-terminal domain, which is not required for STAT5 phosphorylation, enhanced autocatalysis, converting a high intensity graded signal into a high intensity binary response. The N-terminal domain is known to participate in a radical conformational reorientation of STAT5 dimers inherent in STAT5 activation. We propose that the N-terminal domains of active STAT5 dimers facilitate the conformational reorientation of inactive dimers, in a prion-like autocatalytic interaction that underlies bistability and binary signaling. Together, bistable STAT5 activation, combined with a graded response allow erythropoietic rate to faithfully reflect a wide Epo concentration range, while preventing aberrant signaling.

Les récepteurs Erythropoietin-producing hepatocyte (EPH) constituent la plus grande famille de récepteurs à activité tyrosine kinase transmembranaires. Leur activité kinase peut être induite par leurs ligands, les éphrines (EFN). Une fois activés, ces récepteurs sont impliqués dans la régulation de la fonction cellulaire par transduction antérograde ou rétrograde du signal EPH-EFN. Au cours de la dernière décennie, nos études ont démontré que les EPH / EFN jouent un rôle important dans la régulation de la pression artérielle par la modulation de la contractilité des cellules musculaires lisses vasculaires (VSMC). EPHB6, EFNB1 et EFNB3 ont un effet négatif sur la contractilité des VSMC et la pression artérielle, tandis que EPHB4 et EFNB2 montrent un effet positif. La famille EPH / EFN est donc un nouveau système yin et yang qui ajuste finement l'homéostasie de la pression artérielle. Nous avons également constaté que les catécholamines urinaires de 24 h sont réduites chez les souris mâles EPHB6 knockout (KO), suggérant que l’EPHB6 régule la pression artérielle non seulement via les VSMC mais aussi par la sécrétion de catécholamine (CAT). La régulation de CAT par l’EPHB6 dépend de la testostérone car (1) les niveaux réduits de CAT ne sont pas observés chez les souris femelles EPHB6 KO ; et (2) la castration chez les souris mâles EPHB6 KO ramène la CAT à des niveaux normaux. Durant ma thèse, nous avons étudié le mécanisme impliqué dans la régulation de la sécrétion et de la synthèse des catécholamines chez les cellules chromaffines des glandes surrénales (AGCC) par la voie de signalisation de l’EPHB6. En ex vivo, la teneur totale en épinéphrine et la sécrétion d'épinéphrine déclenchée par l'acétylcholine (ACh) sont toutes deux réduites dans les glandes surrénales venant des souris KO mâles mais pas dans celles venant des femelles ou de mâles castrés. Ensuite, nous avons observé une diminution de l’afflux de Ca2+ dépendant de l'ACh dans les AGCC venant des souris mâles EPHB6 KO, ce qui découle de l'effet non-génomique de la testostérone. En appliquant le patch clamping de cellules entières sur les AGCC, nous avons démontré que la diminution d’afflux de Ca2+ dans ces cellules est causée par l’augmentation des courants de potassium à grande conductance activé par le calcium (BK). En utilisant l'enregistrement ampérométrique, nous avons constaté que la sécrétion de CAT par les AGCC est compromise en l'absence d'EPHB6. Nous avons également observé une diminution du désassemblage de la F-actine corticale dans les AGCC venant de souris mâles KO associée à une diminution de l'exocytose des vésicules contenant es catécholamines. Ces deux phénomènes n’ont pas été observés chez les femelles KO ni chez les mâles castrés. Des études complémentaires ont montré que le désassemblage défectueux de la F-actine dans les AGCC est régulé par la signalisation inverse de l'EPHB6 à l'EFNB1 via deux voies de signalisations différentes : la voie du membre A de la famille des homologues Ras (RHOA) et la voie de la tyrosine kinase proto-oncogène de la famille Src (FYN) / proto-oncogène c-ABL / la calponine monooxygénase associée aux microtubules et le domaine LIM contenant 1 (MICAL-1). En outre, nous avons observé que la diminution de la teneur totale en épinéphrine dans la glande surrénale venant des souris mâles KO est causée par une expression altérée de la tyrosine hydroxylase (TH), qui est l’enzyme limitant la vitesse dans la biosynthèse des CAT. L'effet non génomique de la testostérone a également participé dans ce processus. Nous avons révélé que la signalisation inverse d'EPHB6 à EFNB1 contribue à la surexpression de TH dans les AGCC par l’augmentation de son niveau de transcription. La voie en aval de cette signalisation inverse implique la petite famille Rac GTPase 1 (RAC1) / MAP kinase kinase 7 (MKK7) / c-Jun N-terminal kinase (JNK) / proto-oncogène c-Jun / activator protein 1 (AP1) / réponse de croissance précoce 1 (EGR1). Ces travaux démontrent pour la première fois un rôle spécifique de la famille EPH / EFN dans la régulation de la biologie médullaire de la glande surrénale. La signalisation rétrograde d’EPHB6 via EFNB1 régule la synthèse et la sécrétion des catécholamines de concert avec la testostérone dans les AGCC. / Erythropoietin-producing hepatocyte (Eph) receptors are the largest family of cell surface transmembrane receptor tyrosine kinases. Their kinase activity can be activated by their ligands, ephrins (EFNs), and involved in cell function regulation through either EPH-EFN forward or reverse signaling transduction. In the last decade, we have revealed the previously unknown function of EPHs/EFNs in the regulation of blood pressure by modulating the contractility of vascular smooth muscle cells (VSMCs). EPHB6, EFNB1, and EFNB3 have a negative effect on the VSMCs contractility and blood pressure, while EPHB4 and EFNB2 show a positive effect instead. Thus, EPH/EFN family is a novel yin and yang system that finely tunes blood pressure homeostasis. EPHB6 also targets cells responsible for catecholamine (CAT) secretion in addition to the VSMCs, since we found that the 24-h urine catecholamines are reduced in male EPHB6 knockout (KO) mice. This phenotype in EPHB6 KO mice is testosterone-dependent because the reduced CAT levels are not observed in female KO mice; castration in KO male mice reverts the CAT levels to a normal range. In this research, we investigated the mechanism for the regulation of catecholamine secretion and synthesis in adrenal gland chromaffin cells (AGCCs) by EPHB6 signaling. In ex vivo, the total content of epinephrine and the acetylcholine (ACh)-triggered epinephrine secretion were both reduced in the adrenal gland from KO male but not female or castrated mice. Then, we found a reduced ACh-dependent Ca2+ influx in AGCCs from male EPHB6 KO mice, and this effect depended on the non-genomic effect of testosterone. The results of whole-cell patch clamping on AGCCs indicated that the enhanced large-conductance calcium-activated potassium (BK) currents were responsible for the reduced Ca2+ influx in these cells. Using amperometry recording, we found that CAT secretion by AGCCs was compromised in the absence of EPHB6. The cortical F-actin disassembly in AGCCs from KO male but not female or castrated mice was reduced, accompanied by decreased catecholamine vesicle exocytosis. Further study showed such defective F-actin disassembly in AGCCs was regulated by the reverse signaling from EPHB6 to EFNB1 via the Ras homolog family member A (RHOA) and proto-oncogene Src family tyrosine kinase (FYN)/proto-oncogene c-ABL/microtubule-associated monooxygenase calponin and LIM domain containing 1 (MICAL-1) pathways. Further, we observed that the reduced total content of epinephrine in the adrenal gland from male KO mice was caused by impaired expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in CAT biosynthesis. The non-genomic effect of testosterone was also involved in this process. We revealed that the reverse signaling from EPHB6 to EFNB1 contributed to the up-regulation of TH expression in AGCCs by enhancing its transcription. The downstream pathway of this reverse signaling involved Rac family small GTPase 1 (RAC1)/MAP kinase kinase 7 (MKK7)/c-Jun N-terminal kinase (JNK)/ proto-oncogene c-Jun/activator protein 1 (AP1)/early growth response 1 (EGR1). The present research, for the first time, revealed the specific role of the EPH/EFN family on the regulation of the adrenal gland medullary biology. The EPHB6 reverse signaling through EFNB1 in concert with testosterone regulates the catecholamine synthesis and secretion in AGCCs.

BACKGROUND:Diffuse axonal injury is a common consequence of traumatic brain injury (TBI) and often co-occurs with hypoxia, resulting in poor neurological outcome for which there is no current therapy. Here, we investigate the ability of the multifunctional compound erythropoietin (EPO) to provide neuroprotection when administered to rats after diffuse TBI alone or with post-traumatic hypoxia.METHODS:Sprague-Dawley rats were subjected to diffuse traumatic axonal injury (TAI) followed by 30minutes of hypoxic (Hx, 12% O2) or normoxic ventilation, and were administered recombinant human EPO-alpha (5000IU/kg) or saline at 1 and 24hours post-injury. The parameters examined included: 1) behavioural and cognitive deficit using the Rotarod, open field and novel object recognition tests / 2) axonal pathology (NF-200) / 3) callosal degradation (hematoxylin and eosin stain) / 3) dendritic loss (MAP2) / 4) expression and localisation of the EPO receptor (EpoR) / 5) activation/infiltration of microglia/macrophages (CD68) and production of IL-1beta.RESULTS:EPO significantly improved sensorimotor and cognitive recovery when administered to TAI rats with hypoxia (TAI+Hx). A single dose of EPO at 1hour reduced axonal damage in the white matter of TAI+Hx rats at 1day by 60% compared to vehicle. MAP2 was decreased in the lateral septal nucleus of TAI+Hx rats / however, EPO prevented this loss, and maintained MAP2 density over time. EPO administration elicited an early enhanced expression of EpoR 1day after TAI+Hx compared with a 7-day peak in vehicle controls. Furthermore, EPO reduced IL-1beta to sham levels 2hours after TAI+Hx, concomitant to a decrease in CD68 positive cells at 7 and 14days.CONCLUSIONS:When administered EPO, TAI+Hx rats had improved behavioural and cognitive performance, attenuated white matter damage, resolution of neuronal damage spanning from the axon to the dendrite, and suppressed neuroinflammation, alongside enhanced expression of EpoR. These data provide compelling evidence of EPO's neuroprotective capability. Few benefits were observed when EPO was administered to TAI rats without hypoxia, indicating that EPO's neuroprotective capacity is bolstered under hypoxic conditions, which may be an important consideration when EPO is employed for neuroprotection in the clinic.

The American Medical Association (AMA) has estimated that as many as 40 percent of all prescriptions are issued for off-label use. Off-label prescribing is considered to be clinically beneficial and rational in certain life-threatening situations. However, off-label use can pose risks to patients in terms of adverse drug events as well as contribute to rising pharmaceutical costs. The anti-anemic drugs erythropoietin and darbepoetin are costly, and there are significant off-label uses for these drugs some of which are not supported with clinical evidence, hence were selected as study drugs. Our study goals included quantification of the prevalence rate and appropriateness of off-label use of erythropoietin and darbepoetin across U.S. hospitals, and identification of possible predictors of off-label use from the domains of patient characteristics, physician specialty, hospital characteristics and drug characteristics. To address the research questions we performed a retrospective review of 464,834 discharged patients across 515 hospitals who have received erythropoietin and darbepoetin from the time periods between 2001and 2004. The data was supplied by Solucient®. The uses of the two drugs have been categorized using an evidence-based medicine framework that classifies them into: a) on-label use (approved by the FDA), b) off-label use supported (use not approved by FDA but there is strong clinical evidence supporting off-label use), and c) off-label use unsupported (lack of clinical evidence). A multinomial logistic regression model clustered by hospitals was conducted to determine predictors of off-label use. The results of this study revealed that more than half of the utilization of the two erythropoietic drugs is for off-label purposes, the majority of which is supported with evidence. Among the covariates, physician specialty, patient age group, race, drug coverage and length of hospital stay were significant (0.05 level) predictors of off-label use (supported and unsupported) relative to on-label. It is useful to understand the extent and appropriateness of off-label utilization in order to ensure safe and cost-effective use in patients. The availability of empirically derived knowledge on the national level could precipitate the promulgation of more meaningful post-marketing surveillance measures.

Adaptation to chronic hypoxia increases myocardial resistance to acute ischemia/reperfusion (I/R) injury, similarly to application of exogenous erythropoietin (EPO). Nevertheless, it is not known if EPO induced by chronic hypoxia plays a role in its cardioprotective mechanism. The aim of this study was to find out if protective effect of exogenous EPO adds up to protection offered by chronic hypoxia. Adult male mice (ICR) were adapted to intermittent hypobaric hypoxia 8 hours per day, 5 days per week for 5 weeks. The degree of hypoxia corresponded to 7000 metres. Control animals were housed for the same time in normoxic environment. Resistance to I/R injury was assessed according to size of myocardial infarction induced by 45-min global ischemia and 1-h reperfusion of the heart in vitro. Animals were treated 24 h before the experiment with 200 or 5000 U/kg EPO. Treatment with 200 U/kg EPO was sufficient to significantly limit infarct size in normoxic animals (33,56 ± 2,93 % vs. 25,71 ± 2,29 %). Hypoxic adaptation decreased infarct area to 23,49 ± 2,30%, but additive effect of EPO in hypoxic group was not detected. The results indicate that exogenous EPO employs the same cardioprotective mechanisms as adaptation to chronic intermittent hypoxia. Preliminary results indicate that repeated application of EPO...