Institute Estudios Avanzados IDEA

Caracas, Venezuela

Institute Estudios Avanzados IDEA

Caracas, Venezuela
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Castillo C.,Institute Estudios Avanzados IDEA | Norcini M.,New York University | Martin Hernandez L.A.,New York University | Correa G.,Institute Estudios Avanzados IDEA | And 2 more authors.
Neuroscience | Year: 2013

Satellite glia cells (SGCs), within the dorsal root ganglia (DRG), surround the somata of most sensory neurons. SGCs have been shown to interact with sensory neurons and appear to be involved in the processing of afferent information. We found that in rat DRG various N-methyl-d-aspartate receptor (NMDAr) subunits were expressed in SGCs in intact ganglia and in vitro. In culture, when SGCs were exposed to brief pulses of NMDA they evoked transient increases in cytoplasmic calcium that were inhibited by specific NMDA blockers (MK-801, AP5) while they were Mg2+ insensitive indicating that SGCs express functional NMDAr. The percentage of NMDA responsive SGCs was similar in mixed- (SGCs plus neurons) and SGC-enriched cultures. The pattern of the magnitude changes of the NMDA-evoked response was similar in SGCs and DRG neurons when they were in close proximity, suggesting that the NMDA response of SGCs and DRG neurons is modulated by their interactions. Treating the cultures with nerve growth factor, and/or prostaglandin E2 did not alter the percentage of SGCs that responded to NMDA. Since glutamate appears to be released within the DRG, the detection of functional NMDAr in SGCs suggests that their NMDAr activity could contribute to the interactions between neurons and SGCs. In summary we demonstrated for the first time that SGCs express functional NMDAr. © 2013 IBRO.


Alvarez A.,Institute Estudios Avanzados IDEA | Montero Y.,Institute Estudios Avanzados IDEA | Jimenez E.,Institute Estudios Avanzados IDEA | Zerpa N.,Institute Estudios Avanzados IDEA | And 2 more authors.
Toxicon | Year: 2013

Tityus caripitensis is responsible for most of scorpion stings related to human incidents in Northeastern Venezuela. The only treatment for scorpion envenomation is immunotherapy based on administration of scorpion anti-venom produced in horses. Avian antibodies (IgY) isolated from chicken egg yolks represent a new alternative to be applied as anti-venom therapy. For this reason, we produced IgY antibodies against T. caripitensis scorpion venom and evaluated its neutralizing capacity. The anti-scorpion venom antibodies were purified by precipitation techniques with polyethylene glycol and evaluated by Multiple Antigen Blot Assay (MABA), an indirect ELISA, and Western blot assays. The lethality neutralization was evaluated by preincubating the venom together with the anti-venom prior to testing. The IgY immunoreactivity was demonstrated by a dose-dependent inhibition in Western blot assays where antibodies pre-absorbed with the venom did not recognize the venom proteins from T. caripitensis. The anti-venom was effective in neutralizing 2LD50 doses of T. caripitensis venom (97.8mg of IgY neutralized 1mg of T. caripitensis venom). Our results support the future use of avian anti-scorpion venom as an alternative to conventional equine anti-venom therapy in our country. © 2013 Elsevier Ltd.


Rodriguez-Angulo H.O.,CNR Institute of Biophysics | Toro-Mendoza J.,Venezuelan Institute for Scientific Research | Marques J.A.,Central University of Venezuela | Concepcion J.L.,University of Los Andes, Venezuela | And 6 more authors.
PLoS Neglected Tropical Diseases | Year: 2015

Chagas cardiomyopathy, caused by the protozoan Trypanosoma cruzi, is characterized by alterations in intracellular ion, heart failure and arrhythmias. Arrhythmias have been related to sudden death, even in asymptomatic patients, and their molecular mechanisms have not been fully elucidated. The aim of this study is to demonstrate the effect of proteins secreted by T. cruzi on healthy, isolated beating rat heart model under a non-damage-inducing protocol. We established a non-damage-inducing recirculation-reoxygenation model where ultrafiltrate fractions of conditioned medium control or conditioned infected medium were perfused at a standard flow rate and under partial oxygenation. Western blotting with chagasic patient serum was performed to determine the antigenicity of the conditioned infected medium fractions. We observed bradycardia, ventricular fibrillation and complete atrioventricular block in hearts during perfusion with >50 kDa conditioned infected culture medium. The preincubation of conditioned infected medium with chagasic serum abolished the bradycardia and arrhythmias. The proteins present in the conditioned infected culture medium of >50 kDa fractions were recognized by the chagasic patient sera associated with arrhythmias. These results suggest that proteins secreted by T. cruzi are involved in Chagas disease arrhythmias and may be a potential biomarker in chagasic patients. © 2015 Rodríguez-Angulo et al.


Trigos A.S.,Institute Estudios Avanzados IDEA | Trigos A.S.,Simon Bolivar University of Venezuela | Longart M.,Institute Estudios Avanzados IDEA | Garcia L.,Institute Estudios Avanzados IDEA | And 3 more authors.
Frontiers in Cellular Neuroscience | Year: 2015

Several reports have shown that a sciatic nerve conditioned media (CM) causes neuronal-like differentiation in PC12 cells. This differentiation is featured by neurite outgrowth, which are exclusively dendrites, without axon or sodium current induction. In previous studies, our group reported that the CM supplemented with a generic inhibitor for tyrosine kinase receptors (k252a) enhanced the CM-induced morphological differentiation upregulating neurite outgrowth, axonal formation and sodium current elicitation. Sodium currents were also induced by depletion of endogenous precursor of nerve growth factorr (proNGF) from the CM (pNGFd-CM). Given that sodium currents, neurite outgrowth and axon specification are important features of neuronal differentiation, in the current manuscript, first we investigated if proNGF was hindering the full PC12 cell neuronal-like differentiation. Second, we studied the effects of exogenous wild type (pNGFwt) and mutated (pNGFmu) proNGF isoforms over sodium currents and whether or not their addition to the pNGFd-CM would prevent sodium current elicitation. Third, we investigated if proNGF was exerting its negative regulation through the sortilin receptor, and for this, the proNGF action was blocked with neurotensin (NT), a factor known to compete with proNGF for sortilin. Thereby, here we show that pNGFd-CM enhanced cell differentiation, cell proportion with long neurites, total neurite length, induced axonal formation and sodium current elicitation. Interestingly, treatment of PC12 cells with wild type or mutated proNGF isoforms elicited sodium currents. Supplementing pNGFd-CM with pNGFmut reduced 35% the sodium currents. On the other hand, pNGFd- CM+pNGFwt induced larger sodium currents than pNGFd-CM. Finally, treatments with CM supplemented with NT showed that sortilin was mediating proNGF negative regulation, since its blocking induced similar effects than the pNGFd-CM treatment. Altogether, our results suggest that proNGF within the CM, is one of the main inhibitors of full neuronal differentiation, acting through sortilin receptor. © 2015 Trigos, Longart, García, Castillo, Forsyth and Medina.


Benaim G.,Institute Estudios Avanzados IDEA | Benaim G.,Central University of Venezuela | Garcia C.R.S.,University of Sao Paulo
Tropical Biomedicine | Year: 2011

Ca 2+ has been largely recognized as an essential messenger in all eukaryotes, from mammals to parasites. The disruption of Ca 2+ homeostasis in any cell usually drives to lethal effects resulting in cell death by apoptosis or necrosis. This appears also to be the case in human trypanosomatids, such as Trypanosoma cruzi, the causative agent of Chagas' disease, Trypanosoma brucei, which produces "sleeping sickness" and Leishmania sp, responsible for leishmaniasis. The aim of this review is to describe the intracellular Ca 2+ regulation and the cytotoxic effect of new drugs regarding the disruption of Ca 2+ homeostasis in these parasites. With regard to intracellular Ca 2+ regulation, all these trypanosomatids possess a single mitochondrion that occupies 12% of the total volume of the parasite which is able to accumulate large amounts of Ca 2+. The endoplasmic reticulum is also involved in Ca 2+ regulation. These parasites also possess acidocalcisomes, an unusual organelle involved in the bioenergetics of these cells in accumulating large amounts of polyphosphates together with Ca 2+ ions. Trypanosomatids possess relatively large amounts of calmodulin. While this well conserved protein is identical among all vertebrates, there is 89% amino acid sequence identity between T. cruzi and vertebrate calmodulin. Recently, this protein has been cloned and expressed from T. cruzi, allowing a further characterization corroborating significant differences between calmodulin from T. cruzi and mammals. It has also been reported that a commonly used antiarrhytmic, amiodarone, which is used in chronic Chagas' patients with heart problems, is able to produce a large trypanocidal effect. The intracellular compartments responsible for the increase in the intracellular Ca 2+ concentration ([Ca 2+] i) upon the addition of amiodarone are the single large mitochondrion and the acidocalcisomes. Amiodarone is also capable to inhibit the oxidosqualene cyclase, a key enzyme in the synthesis of ergosterol. The effect of amiodarone was highly synergistic with posaconazole, a known potent inhibitor of the synthesis of ergosterol. Interestingly, posaconazole by itself is able to produce an increase in the [Ca 2+] i. Concerning putative treatments in humans, amiodarone was reported to induce the cure of a patient with Chagas' disease, when used in combination with itraconazole. Seemingly, a recent case indicated the cure of a patient with Chagas' disease by the administration of posaconazole. Miltefosine, an orally active alkyl-lysophospholipid with potent anti-Leishmania activity, represents a major advance in the treatment of leishmaniasis. Recently it was reported that miltefosine also disrupts the parasite's intracellular Ca 2+ homeostasis, by inducing a large increase in [Ca 2+] i, through the activation of a plasma membrane Ca 2+ channel. It has been found that the combination of miltefosine and amiodarone have synergistic effects on the proliferation of amastigotes growing inside macrophages and this led to 90% of parasitological cure in a murine model of leishmaniasis, as revealed by a PCR assay. More recently, posaconazole has been used successfully in a case of a human Old World cutaneous leishmaniasis. All these findings strongly suggest that the alteration of the intracellular Ca 2+ homeostasis of these parasites is a promising strategy as a target of new as well as repurposed old-known drugs.


Benaim G.,Institute Estudios Avanzados IDEA | Benaim G.,Central University of Venezuela | Hernandez-Rodriguez V.,Institute Estudios Avanzados IDEA | Hernandez-Rodriguez V.,Central University of Venezuela | And 8 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2012

Amiodarone, a commonly used antiarrhythmic, is also a potent and selective anti-Trypanosoma cruzi agent. Dronedarone is an amiodarone derivative in which the 2,5-diiodophenyl moiety of the parental drug has been replaced with an unsubstituted phenyl group aiming to eliminate the thyroid toxicity frequently observed with amiodarone treatment. Dronedarone has been approved by the Food and Drug Administration (FDA), and its use as a safe antiarrhythmic has been extensively documented. We show here that dronedarone also has potent anti-T. cruzi activity, against both extracellular epimastigotes and intracellular amastigotes, the clinically relevant form of the parasite. The 50% inhibitory concentrations against both proliferative stages are lower than those previously reported for amiodarone. The mechanism of action of dronedarone resembles that of amiodarone, as it induces a large increase in the intracellular Ca 2+ concentration of the parasite, which results from the release of this ion from intracellular storage sites, including a direct effect of the drug on the mitochondrial electrochemical potential, and through alkalinization of the acidocalcisomes. Our results suggest a possible future repurposed use of dronedarone for the treatment of Chagas' disease. Copyright © 2012, American Society for Microbiology. All Rights Reserved.


Benaim G.,Institute Estudios Avanzados IDEA | Benaim G.,Central University of Venezuela | Paniz Mondolfi A.E.,Institute Biomedicina SAIB | Paniz Mondolfi A.E.,St Lukes Roosevelt Hospital Center
Nature Reviews Cardiology | Year: 2012

Chagas disease has emerged as an important health problem in the Americas and, with globalization, in other parts of the world. Drug therapy for this parasitic infection has remained largely ineffective, especially in chronic stages of the disease. However, developments in experimental therapy might signal an important advance for the management of patients with Chagas disease. Herein, we review studies on the potential use of the benzofuran derivatives amiodarone and dronedarone in patients with Chagas disease. These agents have a dual role, not only as primary antiarrhythmic drugs, but also as antiparasitic agents. We believe that this 'kill two birds with one stone' approach represents a new tactic for the treatment of Chagas disease using currently approved drugs. © 2012 Macmillan Publishers Limited. All rights reserved.


Benaim G.,Institute Estudios Avanzados IDEA | Benaim G.,Central University of Venezuela | Garcia-Marchan Y.,Institute Estudios Avanzados IDEA | Reyes C.,Venezuelan Institute for Scientific Research | And 2 more authors.
Biochemical and Biophysical Research Communications | Year: 2013

The disruption of the intracellular Ca2+ homeostasis of Leishmania mexicana represents a major target for the action of drugs, such as amiodarone and miltefosine. However, little is known about the mechanism of Ca2+ entry to these cells. Here we show the presence of a Ca2+ channel in the plasma membrane of these parasites. This channel has many characteristics similar to the human L-type voltage-gated Ca2+ channel. Thus, Ca2+ entry is blocked by verapamil, nifedipine and diltiazem while Bay K 8644 opened this channel. However, different to its human counterpart, sphingosine was able to open this channel, while other well known sphingolipids had no effect. This fact could have important pharmacological implications. © 2012 Elsevier Inc.


PubMed | Institute Estudios Avanzados IDEA, Central University of Venezuela and Simon Bolivar University of Venezuela
Type: | Journal: European journal of medicinal chemistry | Year: 2017

With the aim to identify a potential drug candidate to treat cutaneous leishmaniasis, a series of 1-phthalazinyl hydrazones were synthesized and tested against Leishmania braziliensis parasite, one of the main responsible of this disease in the world. A structure-activity relationship permitted to identify two phthalazines containing nitroheterocyclic moiety 3l and 3m as promising new lead compounds. These compounds showed a significant antileishmanial activity against promastigote form of L.braziliensis, with EC


Recio-Pinto E.,NYU Langone Medical Center | Castillo C.,Institute Estudios Avanzados IDEA
Techniques in Regional Anesthesia and Pain Management | Year: 2010

The role of N-methyl-D-aspartate receptors (NMDArs) in pain sensation was initially uncovered in 1987 when the hyperexcitability of spinal cord dorsal horn nociceptive neurons evoked by C-fiber stimulation was found to be blocked by spinal delivery of NMDAr antagonist. Since then, many studies have focused on the role of central NMDArs in pain sensation. It is now apparent that peripheral NMDArs also play a role not only in the initiation but also in the maintenance of chronic pain states, particularly those following peripheral nerve injuries. Peripheral NMDArs are an attractive target for treating chronic pain, because under normal (nonpainful) stimulation NMDArs in dorsal root ganglia (DRG) neurons do not activate; in addition, some of the NMDArs isoforms are predominantly expressed in DRG neurons, and NMDArs have various regulatory sites that are isoform-dependent. This article concentrates on reviewing the possible role of peripheral NMDArs in initiating and maintaining chronic pain states. Of particular interest is the role of NMDArs not only on peripheral DRG neurons but also on their surrounding glia, since neuronal-glial interactions have been shown to contribute to injury-evoked neuronal hyperexcitability. Drugs that would target selectively peripheral NMDArs would improve treatment of chronic pain states. This review is divided into 5 sections: NMDAr structure and function; the role of peripheral NMDArs in pain perception; modulation of NMDArs during pain states; modulation of NMDAr activity by Substance P; and role of glia in DRG neuronal hyperexcitability. © 2010.

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