Amalia Merelli

University of Buenos Aires, Buenos Aires, Buenos Aires F.D., Argentina

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Publications (10)13.23 Total impact

  • A Merelli, L Czornyj, A Lazarowski
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    ABSTRACT: Abstract Highly expressed Erythropoietin Receptor (EPO-R) has been detected in several non-hematopoietic hypoxic cells, including cells from different brain areas in response to many different types of cell injury. In brain, hypoxia-ischemia (HI) can induce a wide spectrum of biologic responses, where inflammation and apoptosis are the main protagonists. Inflammation, as a primary brain insult, can induce a chronic hypoxic condition, producing the continuous cycle of inflammation-hypoxia that increases the apoptotic-cell number. It has also been demonstrated that administration of erythropoietin (EPO) prevented the neuronal death induced by HI, as well as the induction of lipid peroxidation in the hippocampus in a rodent model of Alzheimer's disease. Anti-apoptotic, anti-inflammatory, anti-oxidant and/or cell-proliferative effects of EPO, have been observed in all type of cells expressing EPO-R, resulting in a potential tool for neuroprotection, neuroreparation or neurogenesis of brain damaged areas. The nasal route is an alternative way of drugs administration that has been successfully exploited for bypassing the blood brain barrier, and subsequently delivering EPO and other molecules to central nervous system. Intranasal administration of EPO could be a new therapeutic opportunity in several brain damages that includes hypoxia, inflammation, neurodegenerative process and apoptosis.
    The International journal of neuroscience. 11/2014;
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    ABSTRACT: Neuronal damage secondary to brain injuries such as cerebral hypoxia, seizures as well as neurodegenerative process, may include pro-inflammatory changes. The activation of a common mechanism related to survival or cell death, mediated by the stabilization and trans-activation of Hypoxia-Inducible Factor 1 (HIF-1), has been observed in these conditions. HIF-1 may induce over expression of P-glycoprotein, the product multidrug-resistance gene (MDR-1), both on blood-brain barrier as well as on the cerebral damaged cells, producing the refractoriness to therapeutic strategies for neuroprotection. However, in these same cells, HIF-1 can also induce the expression of erythropoietin receptor (Epo-R). Irrespective of its known properties on hematopoiesis, it was proposed that erythropoietin can trigger neuroprotective mechanisms mediated by Epo-R activation. Brain hypoxia, epilepsy, neurodegeneration and inflammation, can share the induction of Epo-R and several other growth factor receptors as well as signal transductions pathways after HIF-1 transactivation. Perhaps, the use of the intranasal route for the exogenous administration of Epo, (or other biological compounds) could help neuroprotection as well as to repair the brain areas damaged.
    Current pharmaceutical design 03/2013; · 4.41 Impact Factor
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    ABSTRACT: The ulcerative haemosiderinic dyschromia of chronic venous insufficiency is difficult to heal and presents a high accumulation of iron. Lactoferrin, a potent natural iron chela-tor, could help to scar this ulcerative haemosi -derinic dyschromia. The objective of this study was to determine whether the topical application of a liposomal gel with Lactoferrin favors scarring/degradation of the brown col-ored spot typical of ulcerative haemosiderinic dyschromia. Nine patients with severe chron-ic venous insufficiency and ulcerative haemosiderinic dyschromia (CEAP-C6), with a natural evolution of over 12 months, were included in the study. Hemo chromatosis gene mutations were investigated. The levels of serum ferritin, transferrin saturation and blood cell counts were analyzed. The presence of hemosiderin was investigated through periulcerous and ulcer fundus biopsies car-ried out at baseline and 30 days after treat-ment with Lactoferrin. The severity of the injuries (CEAP classification) was evaluated at the beginning of and throughout the whole 3-month treatment period. No patient had received compression treatment during the three months previous to this therapy. Significant improvement in these injuries, with a reduction in the dimensions of the brown spot (9 of 9) at Day 90, and complete scarring with a closure time ranging from 15 to 180 days (7 of 9) were observed. The use of topical lactoferrin is a non-invasive therapeu-tic tool that favors clearance of hemosiderinic dyschromia and scarring of the ulcer. The success of this study was not influenced either by the hemochromatosis genetics or the iron metabolism profile observed.
    Veins and Lymphatics. 12/2012; 1(e6):18-26.
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    ABSTRACT: Stroke is a major human health problem without efficient available therapeutics. Ischemic brain injury can induce cell death as well as upregulation of endogenous adaptive mechanisms depending on the severity and duration of hypoxia, and the activity of transcription factors, such as hypoxia inducible factor 1-α (HIF-1α). HIF-1α induces gene expression as multidrug resistance (MDR-1) gene associated with drug-refractory phenotype, as well as erythropoietin (Epo) and erythropoietin receptor (Epo-R) associated with O(2) supply. The spontaneous stimulation of the Epo/Epo-R system is not enough for brain protection. Therefore, administration of exogenous recombinant human Epo (rHu-Epo) was suggested as an alternative therapy in stroke. In several experimental models of brain hypoxia, Epo and Epo variants, including rHu-Epo, showed neuroprotective effects. Intranasal administration of these Epo-compounds can reach the central nervous system and protect the brain against ischemia, avoiding hematopoietic effects. However, it has been reported that high expression of Epo-R in neurons must be available to be activated by Epo. According to these considerations, intranasal delivery of rHu-Epo could be an interesting approach in the treatment of cerebral hypoxias avoiding both (i) adverse peripheral effects of treatment with Epo in stroke, and (ii) the pharmacoresistant phenotype depending on MDR-1 expression.
    Drug metabolism and drug interactions 01/2011; 26(2):65-9.
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    ABSTRACT: Stroke is a major human health problem inducing long-term disability without any efficient therapeutic option being currently available. Under hypoxia, hypoxia-inducible factor-1α (HIF-1α) activates several genes as erythropoietin receptor (Epo-R) related with O(2) supply, and the multidrug-resistance gene (MDR-1) related with drug-refractory phenotype. Brain cortical injection of CoCl(2) produces focal hypoxia-like lesion with neuronal and glial alterations, as well as HIF-1α stabilization and MDR-1 overexpression. Intranasal (IN) drug delivery can by-pass blood-brain barrier (BBB) where MDR-1 is normally expressed. We evaluated the effects of IN-rHu-Epo administration on spontaneous motor activity (SMA) and the brain pattern expression of HIF-1α, MDR-1, and Epo-R in our cobalt-induced hypoxia model. Adult male Wistar rats were injected by stereotaxic surgery in frontoparietal cortex, with CoCl(2) (2 μl-50 mM; n = 20) or saline (controls; n = 20). Ten rats of each group were treated with IN-rHu-Epo 24 U or IN-saline. In addition, erythropoietic stimulation was evaluated by reticulocytes (Ret) account during three consecutive days, after intraperitoneal (i.p.)-recombinant-human Epo (rHu-Epo) (950 U; n = 6) or IN-rHu-Epo (24 U; n = 6) administration. SMA was evaluated by open field and rotarod tests, before and after surgical procedures during five consecutive days. Histological and immunostaining studies of HIF-1α, MDR-1, and Epo-R were performed on brain slides. A significant difference in SMA was observed in the hypoxic rats of IN-rHu-Epo-administered group as compared with Co-Saline-treated subjects and controls (p < 0.001). HIF-1α, EPO-R, and MDR-1 were overexpressed in the hypoxic cortex areas, while in contralateral hemisphere or controls, they were negatives. Reticulocytes were only increased in intraperitoneal (i.p.)-rHu-Epo-administered group. In spite of MDR-1 overexpression being detected in neurons, the coexpression of Epo-R could explain the positive effects observed on SMA of IN-rHu-Epo-administered group.
    Neurotoxicity Research 11/2010; 20(2):182-92. · 2.87 Impact Factor
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    ABSTRACT: Ischemic brain injury is a dynamic process that involves oxidative stress, inflammation, and cell death, as well as activation of endogenous adaptive and regenerative mechanisms depending on activation of transcription factors such as hypoxia inducible factor 1-alpha (HIF-1alpha). Because CoCl2 activates HIF-1alpha, we described a new focal-hypoxia model by direct intracerebral CoCl2 injection. Adult male Wistar rats were intracerebrally injected with CoCl2 (2 microl-50 mM), in frontoparietal cortex of right hemisphere, and saline (2 microl) in the contralateral hemisphere. In slides of fixed brains at 1, 6, 9, 24 h or 5 day after treatment, TTC, histochemistry (toluidine blue, Hoescht-33342, TUNEL), immunostaining (HIF-1alpha, GFAP), Lycopersicon esculentum lectin staining, and electron microscopy (EM) were performed. Immediately after 1 h post CoCl2 injection, HIF-1alpha stabilization and neuronal nuclear shrinkage and cromathin condensation were observed by immunostaining and EM, respectively. Neuronal apoptotic nuclear morphology and GFAP immunoreactivity and lectin maximal reactivity were detected during 6-9 h. Ultrastructural alterations of morphology included edematous perinuclear cytoplasm, organelles and endoplasmic reticulum (RE) enlargement, mitochondrial swelling with increased matrix density, and deposits of electron-dense material. Neurons showed particular nuclear indentations. Astrocytes and oligodendrocytes presented alterations in both nuclei and RE with dilated lumen and altered mitochondrias, and all these ultrastructural changes became detectable at day 5. CoCl2 cortical injection mimics focal brain ischemia, inducing neuronal death and glial activation. This model brings the opportunity to develop focal ischemia in selected brain areas to study their functional consequences and potential pharmacological therapies for in vivo models of stroke.
    Neurotoxicity Research 06/2009; 15(4):348-58. · 2.87 Impact Factor
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    ABSTRACT: Neuronal damage after stroke-associated brain hypoxia is a leading cause of long-term disability and death. The refractoriness to therapeutic strategies for neuroprotection after 3 h post brain ischemia is poorly understood. P-glycoprotein (P-gp), the multidrug resistance gene (MDR-1) product is normally expressed at blood-brain-barrier. P-gp neuronal expression has been demonstrated in refractory epilepsy and after brain ischemia. In this report we investigated the hypoxia-induced neuronal P-gp expression after local injection of CoCl(2) (1-200 mM) in the fronto-parietal cortex of male adult rats (Bregma -1.30 mm) by stereotaxic surgery. P-gp immunostaining of brain slides was analyzed using specific monoclonal antibodies and double immunolabeling was done with specific astrocytic and neuronal markers. Five days after injection of 1 mM CoCl(2), P-gp expression surrounding the lesion site was observed in neurons, astrocytic end-foot on capillary blood vessels and endothelial cells on blood vessels. Higher CoCl(2) doses (200 mM) resulted in additional P-gp immunostaining of the entire astrocytic and neuronal cytoplasm. Electron microscopy (EM) studies showed alterations in neurons as early as 6 h after the CoCl(2) injection. P-gp expression in hypoxic neurons and astrocytic end-foot could potentially impair of drugs access to the brain parenchyma thus suggesting the presence of two P-gp-based pumping systems (one in astrocytes and other in the hypoxic neurons) that are able to behave as a previously unnoticed obstacle for pharmacological strategies of neuroprotection.
    Journal of the Neurological Sciences 08/2007; 258(1-2):84-92. · 2.24 Impact Factor
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    ABSTRACT: The regulation of transferrin receptor (RTF) is related to intracellular iron stores and with the soluble receptor is present in plasma. It has already been demonstrated that in iron deficiency anemia (IDA), receptor expression increases when iron stores decrease. In anemia of chronic diseases (ACD) it is difficult to establish the real iron status because of the influence exerted by inflammatory or infectious diseases on iron metabolism. We studied 30 healthy normal subjects and 42 anemic patients (hemoglobin less than 120 g/L) affected with ACD divided into two groups with and without iron deficiency, in order to establish the diagnostic value of measuring the soluble transferrin receptor (sRTF). We correlated erythropoietin (EPO) (as an erythropoietic stimulating factor) with the decreased hemoglobin values observed in both groups. The results were analysed with an ANOVA statistic test of one way analysis of variance, and there were no significant differences in sRTF values between the ACD groups with or without iron deficiency. The ratio log EPO vs hemoglobin showed a remarkably significant inverse correlation in both groups. We can conclude that sRTF levels are within the normal reference values in these patients and are not related to organic iron. Consequently, sRTF cannot be considered a good parameter for making a diagnosis of iron deficiency in chronic diseases.
    Medicina 02/2001; 61(5 Pt 1):552-6. · 0.42 Impact Factor
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    ABSTRACT: We studied 22 patients with hematological neoplasias which included: 12 patients with a diagnosis of Acute Myeloblastic Leukemia (AML) following the morphology and cytochemistry criteria established by FAB (French, American and British Committee), a Myeloblastic Leukemia secondary to MDS (Myelodysplastic Syndromes) and a biphenotypic acute leukemia where we established the relationship between the traditional peroxidase reaction with the anti-MPO by APAAP. We also carried out the nonspecific esterase reaction and determined the immunologic phenotype by FACS technology. The same procedure was used for the cellular analysis of the light chains kappa (kappa) and lambda (lambda) in 3 cases of hairy cell leukemia, one lymphoma and 4 cases of plasma cell neoplasia and reactive plasma cell disease. We conclude that immunocytochemical reactions must be used when morphology and traditional cytochemical reactions need to be confirmed in order to establish a correct diagnosis and this is specially important for B and T lymphomas. Their prognostic value is restricted and the results are useful as a complement to morphology, cytochemistry and immunological determinations.
    Medicina 02/1999; 59(1):11-6. · 0.42 Impact Factor
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    ABSTRACT: Resumen Se estudiaron 22 pacientes con neoplasias hematológicas que incluían: 12 pacientes con diagnóstico de Leucemia Mieloide Aguda (LMA) de novo, según criterio morfológico y citoquímico establecido por la FAB (Comité Francés, Americano, Británico), una LMA secundaria a Síndrome mielodisplásico (SMD), y una leucemia aguda bifenotípica, donde se correlacionó la reacción citoquímica de peroxidasas con la metodología de anti-mieloperoxidasa (MPO) por fosfatasa alcalina anti-fosfatasa (AFAAF). Los estudios fueron completados con la reac-ción citoquímica de esterasas inespecíficas y el fenotipo inmunológico se estableció por citometría de flujo para de-finir la estirpe celular mieloide o linfoide. La misma técnica fue utilizada para el análisis celular de restricción de ca-denas livianas κ y λ en 8 pacientes con desórdenes linfoproliferativos malignos de origen B que comprendían 3 ca-sos de Leucemia a células vellosas (HCL), 1 caso de Linfoma leucemizado y 4 casos de neoplasias de células plasmáticas vs una plasmocitosis reactiva. Se concluye que las reacciones inmunocitoquímicas aplicadas a las pato-logías estudiadas y otras enfermedades hematopoyéticas son útiles cuando la morfología y la citoquímica no han sido concluyentes para establecer un correcto diagnóstico y para distinguir un linaje celular, por ej. linfoma tipo B y T. Sin embargo, se debe enfatizar que su uso diagnóstico es útil como técnica complementaria de los estudios histopatológicos, morfológicos, citoquímicos y fenotípicos celulares, siendo aún discutida su importancia pronóstica. Abstract Immunocytochemistry techniques for the diagnosis of hematological neoplasias. We studied 22 patients with hematological neoplasias which included: 12 patients with a diagnosis of Acute Myeloblastic Leukemia (AML) following the morphology and cytochemistry criteria established by FAB (French, American and British Committee), a Myeloblastic Leukemia secondary to MDS (Myelodysplastic Syndromes) and a biphenotypic acute leukemia where we established the relationship between the traditional peroxidase reaction with the anti-MPO by APAAP. We also carried out the nonspecific esterase reaction and determined the immunologic phenotype by FACS technology. The same procedure was used for the cellular analysis of the light chains κ (kappa) and λ (lambda) in 3 cases of hairy cell leukemia, one lymphoma and 4 cases of plasma cell neoplasia and reactive plasma cell disease. We conclude that immunocytochemical reactions must be used when morphology and traditional cytochemical reactions need to be confirmed in order to establish a correct diagnosis and this is specially important for B and T lymphomas. Their prognostic value is restricted and the results are useful as a complement to morphology, cytochemistry and immunological determinations.

Publication Stats

49 Citations
13.23 Total Impact Points

Institutions

  • 2007–2013
    • University of Buenos Aires
      • • Faculty of Pharmacy and Biochemistry
      • • Clinical Biochemistry Department
      • • Faculty of Medicine
      Buenos Aires, Buenos Aires F.D., Argentina
  • 2011
    • Buenos Aires Institute of Neuroscience
      Buenos Aires, Buenos Aires F.D., Argentina