Meningioma and glioma as the first collision brain tumour reported in small animals.

We describe the clinical and pathological features of a brain collision tumour consisting of a fibrous meningioma and an anaplastic oligoastrocytoma in a 14-year-old male neutered French Bulldog. Computed tomography of the brain revealed a poorly defined, intra-axial lesion affecting the left frontal lobe. Following euthanasia, histological examination showed an anaplastic oligoastrocytoma invading the brain parenchyma and an adjacent fibrous meningioma. As synchronous intracranial tumours are rare in animals, the aims of this report are to describe the clinical, imaging and histopathological features of an intracranial collision tumour in a dog and highlight the importance of a complete histopathological study despite the imaging findings.

Functional recovery of injured cavernous nerves achieved through endogenous nerve growth factor-containing bioactive fibrous membrane.

Radical prostatectomy is a highly successful treatment for prostate cancer, among the most prevalent manifestations of the illness. Damage of the cavernous nerve (CN) during prostatectomy is the main cause of postoperative erectile dysfunction (ED). In this study, the capability of a personalized bioactive fibrous membrane to regenerate injured CN was investigated. The fibrous membrane bioactivity is conferred by the selectively bound nerve growth factor (NGF) present in the rat urine. In a rat model of bilateral CN crush, the implanted bioactive fibrous membrane induces CN regeneration and restoration of erectile function, showing a significantly increased number of smooth muscle cells and content of endothelial and neuronal nitric oxide synthases (eNOS; nNOS). In addition, the bioactive fibrous membrane promotes nerve regeneration by increasing the number of myelinated axons and nNOS-positive cells, therefore reversing the CN fibrosis found in untreated rats or rats treated with a bare fibrous membrane. Therefore, this personalized regenerative strategy could overcome the recognized drawbacks of currently available treatments for CN injuries. It may constitute an effective treatment for prostate cancer patients suffering from ED after being subject to radical prostatectomy. STATEMENT OF SIGNIFICANCE: The present work introduces a unique strategy to address post-surgical ED resulting from CN injury during pelvic surgery (e.g., radical prostatectomy, radical cystoprostatectomy, abdominoperineal resection). It comprises a bioactive and cell-free fibrous implant, customized to enhance CN recovery. Pre-clinical results in a rat model of bilateral CN crush demonstrated that the bioactive fibrous implant can effectively heal injured CN, and restore penile structure and function. This implant selectively binds NGF from patient fluids (i.e. urine) due to its functionalized surface and high surface area. Moreover, its local implantation reduces adverse side effects. This tailored regenerative approach has the potential to revolutionize the treatment of ED in prostate cancer patients following radical prostatectomy, overcoming current treatment limitations.

Chondrogenic differentiation induced by extracellular vesicles bound to a nanofibrous substrate.

Extracellular vesicles (EVs) are being increasingly studied owing to its regenerative potential, namely EVs derived from human bone marrow mesenchymal stem cells (hBM-MSCs). Those can be used for controlling inflammation, repairing injury, and enhancing tissue regeneration. Differently, the potential of EVs derived from human articular chondrocytes (hACs) to promote cartilage regeneration has not been thoroughly investigated. This work aims to develop an EVs immobilization system capable of selectively bind EVs present in conditioned medium obtained from cultures of hACs or hBM-MSC. For that, an anti-CD63 antibody was immobilized at the surface of an activated and functionalized electrospun nanofibrous mesh. The chondrogenic potential of bound EVs was further assessed by culturing hBM-MSCs during 28 days under basal conditions. EVs derived from hACs cultured under differentiation medium or from chondrogenically committed hBM-MSCs induced a chondrogenic phenotype characterized by marked induction of SOX9, COMP, Aggrecan and Collagen type II, and matrix glycosaminoglycans synthesis. Indeed, both EVs immobilization systems outperformed the currently used chondroinductive strategies. These data show that naturally secreted EVs can guide the chondrogenic commitment of hBM-MSCs in the absence of any other chemical or genetic chondrogenic inductors based in medium supplementation.

Stimulation of Neurite Outgrowth Using Autologous NGF Bound at the Surface of a Fibrous Substrate.

Peripheral nerve injury still remains a major clinical challenge, since the available solutions lead to dysfunctional nerve regeneration. Even though autologous nerve grafts are the gold standard, tissue engineered nerve guidance grafts are valid alternatives. Nerve growth factor (NGF) is the most potent neurotrophic factor. The development of a nerve guidance graft able to locally potentiate the interaction between injured neurons and autologous NGF would be a safer and more effective alternative to grafts that just release NGF. Herein, a biofunctional electrospun fibrous mesh (eFM) was developed through the selective retrieval of NGF from rat blood plasma. The neurite outgrowth induced by the eFM-NGF systems was assessed by culturing rat pheochromocytoma (PC12) cells for 7 days, without medium supplementation. The biological results showed that this NGF delivery system stimulates neuronal differentiation, enhancing the neurite growth more than the control condition.

Spatial immobilization of endogenous growth factors to control vascularization in bone tissue engineering.

The intimate crosstalk between endothelial and bony cells is essential for the reconstruction of bone tissue defects. Indeed, a successful bone repair is greatly dependent on the formation of new blood vessels, to ensure the supply of nutrients and gases, as well as the removal of metabolites. Bone morphogenetic proteins (BMPs) and vascular endothelial growth factor (VEGF) are involved on cells differentiation and bone vascularization aiming to develop viable bone tissue. Herein it is hypothesized that endogenous BMP-2 and VEGF bound in a parallel arrangement over a single nanofibrous substrate (NFM) can lead to a successful osteogenic and angiogenic differentiation of mesenchymal stem cells. For that, an engineered biofunctional system was developed comprising anti-BMP-2 and anti-VEGF antibodies, immobilized over an electrospun NFMs in a parallel pattern design, with the attempt to recreate the vasculature of bone tissue. The osteogenic and angiogenic potential of this engineered biofunctional system was demonstrated by culturing human bone marrow-derived mesenchymal stem cells (hBM-MSCs) during 21 days without exogenous induction. A chick chorioallantoic membrane (CAM) assay showed that the engineered biofunctional system, comprising bound endogenous BMP-2 and VEGF, is able to induce an increased angiogenic response. The angiogenic ability of this system, together with the osteogenic inductor BMP-2, enable obtaining an effective vascularized bone tissue engineering approach.

Fibronectin Bound to a Fibrous Substrate Has Chondrogenic Induction Properties.

Articular cartilage is an avascular tissue characterized by a dense and specific extracellular matrix (ECM). Fibronectin (FN) is a key constituent of the pericellular ECM, assembled into a fibrillar matrix through a cell-mediated process, being implicated in chondrogenic events. In this study, we evaluate the chondrogenic potential of FN bound to the surface of an electrospun nanofibrous mesh (NFM). For that, an anti-FN antibody was immobilized at the surface of NFMs, rendering them capable of selectively binding endogenous FN (eFN) from blood plasma. The chondrogenic potential of bound eFN was further assessed by culturing human bone marrow-derived mesenchymal stem cells (hBM-MSCs) for 28 days, in a basal growth medium. The biological results indicate that NFMs functionalized with eFN were able to successfully induce the chondrogenesis of hBM-MSCs, as demonstrated by the high expression of SOX9, Aggrecan, and Collagen type II. Therefore, biofunctionalized nanofibrous substrates comprising eFN significantly enhance the efficacy of a cartilage tissue-engineering strategy.

The Role of Diet Related Short-Chain Fatty Acids in Colorectal Cancer Metabolism and Survival: Prevention and Therapeutic Implications.

Colorectal Cancer (CRC) is a major cause of cancer-related death worldwide. CRC increased risk has been associated with alterations in the intestinal microbiota, with decreased production of Short Chain Fatty Acids (SCFAs). SCFAs produced in the human colon are the major products of bacterial fermentation of undigested dietary fiber and starch. While colonocytes use the three major SCFAs, namely acetate, propionate and butyrate, as energy sources, transformed CRC cells primarily undergo aerobic glycolysis. Compared to normal colonocytes, CRC cells exhibit increased sensitivity to SCFAs, thus indicating they play an important role in cell homeostasis. Manipulation of SCFA levels in the intestine, through changes in microbiota, has therefore emerged as a potential preventive/therapeutic strategy for CRC. Interest in understanding SCFAs mechanism of action in CRC cells has increased in the last years. Several SCFA transporters like SMCT-1, MCT-1 and aquaporins have been identified as the main transmembrane transporters in intestinal cells. Recently, it was shown that acetate promotes plasma membrane re-localization of MCT-1 and triggers changes in the glucose metabolism. SCFAs induce apoptotic cell death in CRC cells, and further mechanisms have been discovered, including the involvement of lysosomal membrane permeabilization, associated with mitochondria dysfunction and degradation. In this review, we will discuss the current knowledge on the transport of SCFAs by CRC cells and their effects on CRC metabolism and survival. The impact of increasing SCFA production by manipulation of colon microbiota on the prevention/therapy of CRC will also be addressed.

Chondrogenesis-inductive nanofibrous substrate using both biological fluids and mesenchymal stem cells from an autologous source.

During the last decade, many cartilage tissue engineering strategies have been developed, being the stem cell-based approach one of the most promising. Transforming Growth Factor-ß3 (TGF-ß3) and Insulin-like Growth Factor-I (IGF-I) are key proteins involved in the regulation of chondrogenic differentiation. Therefore, these two growth factors (GFs) were immobilized at the surface of a single electrospun nanofibrous mesh (NFM) aiming to differentiate human Bone Marrow-derived Mesenchymal Stem Cells (hBM-MSCs). The immobilization of defined antibodies (i.e. anti-TGF-ß3 and anti-IGF-I) allows the selective retrieval of the abovementioned GFs from human platelet lysates (PL). Biochemical assays, involving hBM-MSCs cultured on biofunctional nanofibrous substrates under basal culture medium during 28 days, confirm the biological activity of bound TGF-ß3 and IGF-I. Specifically, the typical spherical morphology of chondrocytes and the immunolocalization of collagen type II confirmed the formation of a cartilaginous ECM. Therefore, the proposed biofunctional nanofibrous substrate is able to promote chondrogenesis.

Colorectal Cancer Cells Increase the Production of Short Chain Fatty Acids by Propionibacterium freudenreichii Impacting on Cancer Cells Survival.

Propionibacterium freudenreichii is a commercially relevant bacterium with probiotic potential. This bacterium can exert protective effects particularly against colorectal cancer (CRC), via the production of short chain fatty acids (SCFA), namely acetate and propionate. In this work, we aimed to evaluate the performance and adaptation capacity of P. freudenreichii to a simulated digestive stress using different culture media, namely YEL, Basal medium, Mimicking the Content of the Human Colon medium (MCHC) and DMEM. The effect of the fermented culture broth on CRC cells survival and of CRC cells conditioned media on the bacteria performance was also evaluated. Basal medium was found to be the best for P. freudenreichii to produce SCFA. MCHC medium, despite being the medium in which lower amounts of acetate and propionate were produced, showed higher acetate and propionate yields as compared to other media. We also observed that the presence of lactate in CRC cells conditioned growth medium resulting from cell metabolism, leads to an increased production of SCFA by the bacteria. The bacterial fermented broth successfully inhibited CRC cells proliferation and increased cell death. Our results showed for the first time that P. freudenreichii performance might be stimulated by extracellular lactate produced by CRC metabolic switch also known as "Warburg effect," where cancer cells "ferment" glucose into lactate. Additionally, our results suggest that P. freudenreichii could be potentially used as a probiotic in CRC prevention at early stages of the carcinogenesis process and might help in CRC therapeutic approaches.

The Use of Electrospinning Technique on Osteochondral Tissue Engineering.

Electrospinning, an electrostatic fiber fabrication technique, has attracted significant interest in recent years due to its versatility and ability to produce highly tunable nanofibrous meshes. These nanofibrous meshes have been investigated as promising tissue engineering scaffolds since they mimic the scale and morphology of the native extracellular matrix. The sub-micron diameter of fibers produced by this process presents various advantages like the high surface area to volume ratio, tunable porosity, and the ability to manipulate the nanofiber composition in order to get desired properties and functionality. Electrospun fibers can be oriented or arranged randomly, giving control over both mechanical properties and the biological response to the fibrous scaffold. Moreover, bioactive molecules can be integrated with the electrospun nanofibrous scaffolds in order to improve the cellular response. This chapter presents an overview of the developments on electrospun polymer nanofibers including processing, structure, and their applications in the field of osteochondral tissue engineering.

Mechanism of action of novel naphthofuranquinones on rat liver microsomal peroxidation.

In order to elucidate the effect on mammal systems of new derivatives from 2-hydroxy-3-allyl-naphthoquinone, alpha-iodinated naphthofuranquinone (NPPN-3223), beta-iodinated naphthofuranquinone (NPPN-3222) and beta-methyl naphthofuranquinone (NPPN-3226) synthesized as possible trypanocidal agents, their effect on rat liver microsomal lipid peroxidation was investigated. They (a) inhibited NADPH-dependent, iron-catalyzed microsomal rat liver lipid peroxidation; (b) did not inhibit the tert-butyl hydroperoxide-dependent lipid peroxidation; (c) did not inhibit ascorbate-lipid peroxidation with the exception of NPPN-3226 which did inhibit it; (d) stimulated NADPH oxidation and microsomal oxygen uptake; (e) increased superoxide anion formation by NADPH-supplemented microsomes and (f) stimulated ascorbate oxidation. The three drugs were reduced to their seminaphthofuranquinone radical by the liver NADPH-P450 reductase system, as detected by ESR measurements. These results support the hypothesis that naphthofuranquinones reduction by microsomal NADPH-P450 reductase and semiquinone oxidation by molecular oxygen diverts electrons, preventing microsomal lipid peroxidation. In addition, hydroquinones and/or semiquinones formed by naphthofuranquinones reduction would be capable of lipid peroxidation inhibition and on interacting with the lipid peroxide radicals can lead to an antioxidant effect as we suggested for NPPN-3226 in close agreement to the inhibition of ascorbate-lipid peroxidation. Due to the properties of these molecules and their incoming structure developments, naphthofuranquinones would be considered as potentially promising therapeutic agents, mainly against Chagas disease.

Mitochondrial toxicity and antioxidant activity of a prenylated flavonoid isolated from Dalea elegans.

The prenylated flavanone 2'-4'-dihidroxy-5'-(1" '-dimethylallyl)-6-prenylpinocembrin) (6PP), isolated from the roots of Dalea elegans, shows antimicrobial activity. The aim of this study was to evaluate mitochondrial toxicity and antioxidant properties of 6PP. Addition of micromolar concentrations of 6PP to rat liver mitochondria, stimulated O2 uptake in state 4 and inhibited it in state 3 when malate-glutamate was the respiratory substrate, and inhibited O2 uptake in state 3 when succinate was the substrate. Highest concentration of 6PP also inhibited O2 uptake in state 4 in the latter case; in both conditions, respiratory control index values were decreased. This flavanone collapsed the mitochondrial membrane potential in a concentration-dependent manner. 6PP also inhibited F0F1-ATPase activity in coupled mitochondria and in submitochondrial particles. In the latter, this compound also inhibited NADH oxidase and succinate dehydrogenase activities. HEp-2 cells were incubated for 24 h with 6PP in presence or absence of 0.5% albumin. As measured by reduction of the mitochondrial-related probe MTT, in the albumin-free condition, 6PP was cytotoxic in a concentration-dependent manner; on the other hand, albumin decreased 6PP effect. In addition, in rat liver microsomes 6PP: (1) inhibited the enzymatic lipid peroxidation, (2) exhibited significant scavenging activity, measured by DPPH reduction assay and (3) demonstrated significant antioxidant activity by decreasing the reduction of Mo(VI) to Mo(V). We suggest that 6PP impairs the hepatic energy metabolism by acting as mitochondrial uncoupler and by inhibiting enzymatic activities linked to the respiratory chain. 6PP also exerts both antioxidant and antiradical activities. Due to its cytotoxicity, this molecule, and its future structure developments, can be considered as a potentially promising therapeutic agent, for instance in cancer chemotherapy.

Expression of caveolin-1 in rat Leydig cells.

Caveolin-1, the first member of caveolin family reported, is recognized as the structural component of caveola, a plasma membrane invagination or vesicles that are a subcompartment distinct from clathrin-coated pits. This protein is also known to be involved in cholesterol trafficking. The aim of this study was to determine the expression of caveolin-1 in adult rat Leydig cells. Testis sections incubated with an antibody to caveolin-1 showed, by immunohistochemistry, a moderate number of Leydig cells with different degrees of immunoreaction and a strong reaction in endothelial cells and in the lamina propia of seminiferous tubules. Caveolin- 1 was detected in the cell cytoplasm with a granular pattern and on the cell surface of Leydig cells cultured 24 h on uncoated, laminin-1 or type IV collagen coated coverslips. We also observed a milder reaction in 3 h cultures. Immunoreaction was also detected in Leydig cells with an antibody to tyrosine-phosphorylated caveolin-1. By double immunofluorescent technique, we observed co-localization of caveolin- I and 313-hydroxysteroid dehydrogenase. Western blot analysis revealed a band of about 22 kDa molecular weight that was recognized with both caveolin-1 and tyrosine-phosphocaveolin-1 antibodies. Caveolin-l is one of a few proteins with a demonstrated ability to bind cholesterol in vivo. In this context, the presence of caveolin- in Leydig cells may be related to cholesterol traffic--a rate limiting step in steroid biosynthesis.

Type IV collagen induces down-regulation of steroidogenic response to gonadotropins in adult rat Leydig cells involving mitogen-activated protein kinase.

We have previously shown that type IV collagen (alpha1 (IV) and alpha2 (IV) collagen chains) (Col-IV) inhibits testosterone (T) production by Leydig cells (LC). The aim of this study was to analyze mechanism/s by which Col-IV exerts this effect. No significant differences in the specific binding of hCG to LH/hCG receptors in LC cultured on uncoated or Col-IV coated plates were observed. An inhibition of cAMP production in hCG-stimulated LC cultured on Col-IV was detected. The inhibition exerted by Col-IV on T production in response to hCG was also observed when cells were stimulated with 8Bromo-cAMP. In addition, conversion of steroid precursors to T in LC cultured on uncoated and Col-IV coated plates was similar. On the other hand, we detected an increase of ERK1/2 phosphorylation in hCG-stimulated LC cultured on Col-IV. Genistein added to LC cultures reduced the ability of Col-IV to increase ERK1/2 phosphorylation and reverted the inhibitory effect of Col-IV on T production. An inhibitor of MEK, PD98059 added to LC cultures also reverted the inhibitory effect of Col-IV on T production. A decrease of steroidogenic acute regulatory protein (StAR) expression in hCG-stimulated LC cultured on Col-IV coated plates that could be reverted by addition of PD98059 to the cultures was also demonstrated. All together these results suggest that Col-IV inhibits T production in LC by binding to integrins, activating ERK1/2, decreasing cAMP production and decreasing StAR expression.

Anticuerpos anti-citoplasma de polimorfonuclear neutrófilo en granulomatosis de Wegener, en otras enfermedades autoinmunes y en pacientes hemodializados / Anticytoplasm antibodies of polymorphonuclear neutrophils in Wegener's granulomatosis, other autoimmune diseases and in patients under hemodialysis

Las vasculitis sistémicas son un grupo heterogénio de enfermedades caracterizadas por infiltración inflamatoria y necrosis de la pared vascular. Anticuerpos contra citoplasma de polimorfonuclear neutrófilo (ANCA-C y ANCA-P) fueron descriptos como marcadores serológicos de algunas de estas afecciones y de ciertos tipos de glomerulonefritis. La presencia de ANCA se investigó en el suero de 182 pacientes. En 16/17 con Granulomatosis de Wegener (G.W.) (critérios ACR) se encontró ANCA, 14 de ellos con imagen C (en 10 asociada a imagem P) y en los dos restantes, imagem P solamente (p < 0,001, comparando con los otros grupos estudiados). La presencia de estos anticorpos se asoció con la atividad clínica de la enfermedad (p, 0,01). El único paciente ANCA-C positivo fuera de este grupo tenía estonosis subglótica como única manifestación clínica con histología inespecífica, ANCA-P se encontró, además, en 6 por ciento de los casos con Enfermedades del Tejido Conectivo estudiados, y en 6/66 de la Unidad de Diálisis, lo cual sugiere que un mecanismo relacionado al ANCA puede ser el responsable de la nefropatía en aproximadamente el 10//de los pacientes en hemodiálisis crónica. Los resultados obtenidos indican que la investigación de ANCA puede ser un elemento de ayuda útil para el diagnóstico y monitoreo de la actividad clínica en la G.W

Anticuerpos anti-citoplasma de polimorfonuclear neutrófilo en granulomatosis de Wegener, en otras enfermedades autoinmunes y en pacientes hemodializados / Anticytoplasm antibodies of polymorphonuclear neutrophils in Wegeners granulomatosis, other autoimmune diseases and in patients under hemodialysis

Las vasculitis sistémicas son un grupo heterogénio de enfermedades caracterizadas por infiltración inflamatoria y necrosis de la pared vascular. Anticuerpos contra citoplasma de polimorfonuclear neutrófilo (ANCA-C y ANCA-P) fueron descriptos como marcadores serológicos de algunas de estas afecciones y de ciertos tipos de glomerulonefritis. La presencia de ANCA se investigó en el suero de 182 pacientes. En 16/17 con Granulomatosis de Wegener (G.W.) (critérios ACR) se encontró ANCA, 14 de ellos con imagen C (en 10 asociada a imagem P) y en los dos restantes, imagem P solamente (p < 0,001, comparando con los otros grupos estudiados). La presencia de estos anticorpos se asoció con la atividad clínica de la enfermedad (p, 0,01). El único paciente ANCA-C positivo fuera de este grupo tenía estonosis subglótica como única manifestación clínica con histología inespecífica, ANCA-P se encontró, además, en 6 por ciento de los casos con Enfermedades del Tejido Conectivo estudiados, y en 6/66 de la Unidad de Diálisis, lo cual sugiere que un mecanismo relacionado al ANCA puede ser el responsable de la nefropatía en aproximadamente el 10//de los pacientes en hemodiálisis crónica. Los resultados obtenidos indican que la investigación de ANCA puede ser un elemento de ayuda útil para el diagnóstico y monitoreo de la actividad clínica en la G.W (AU)

Autoimmune response against myocardial tissue in Chagas disease

Hacen aproximadamente 12 años se demostró en el suero de individuos chagásicos la presencia de un anticuerpo que, por inmunofluorescencia indirecta, reacciona con endocardio, vasos sanguíneos e intersticio de músculo cardíaco (anticuerpo EVI). En los primeros trabajos, se expresó erróneamente que dicha reactividad tenía carácter de autoanticuerpo; más recientemente se determinó su naturaleza heterófila. El propósito del presente trabajo fue determinar qué sistema está involucrado en la respuesta autoinmune humoral contra tejido cardíaco en la enfermedad de Chagas, su prevalencia y especificidad. La presencia de anticuerpos que reaccionan con cortes por criostato de corazón humano grupo 0 fue investigada por la técnica de inmunofluorescencia indirecta en pacientes chagásicos y controles. Los resultados positivos fueron hallados con la siguiente prevalencia: cardiopatía chagásica crónica: 22/34 (64%); infectados asintomáticos: 16/42 (38%); infectados sin datos clínicos: 19/43 (44%); cardiopatías congénitas (pre-cirugía); 0/17 y post-cirugía: 3/5; valvulopatía reumática y cardiopatía isquémica: 7/24 (34%); lupus eritematoso sistémico: 6/15 (40%); artritis reumatoidea: 5/17 (29%); osteoartritis (pacientes en la 6¬ y 7¬ década de vida): 4/19 (21%); controles normales (ciudad de Buenos Aires): 2/29 (7%); controles normales (provincia de Jujuy): 3/16 (19%). La imagen observada fue intracelular siguiendo las estrías. Los experimentos de absorción con glóbulos rojos de cobayo y con proteínas purificadas de músculo demostraron que la reacción intracelular es independiente del anticuerpo EVI, y es removida con miosina. En un caso, la autorreactividad fue confirmada entre una biopsia de miocardio y el suero del mismo paciente. Los títulos de reactividad de los anticuerpos oscilaron entre 1:15 y 1:60. La IgG estuvo siempre involucrada y en algunos casos también la IgM. El anticuerpo no fija C3. El presente estudio demuestra la existencia de una verdadera reacción autoinmune con miocardio en la enfermedad de Chagas. Su significado debe ser aún demostrado, pero podría ser secundario al daño tisular (AU)

Autoimmune response against myocardial tissue in Chagas' disease

Hacen aproximadamente 12 años se demostró en el suero de individuos chagásicos la presencia de un anticuerpo que, por inmunofluorescencia indirecta, reacciona con endocardio, vasos sanguíneos e intersticio de músculo cardíaco (anticuerpo EVI). En los primeros trabajos, se expresó erróneamente que dicha reactividad tenía carácter de autoanticuerpo; más recientemente se determinó su naturaleza heterófila. El propósito del presente trabajo fue determinar qué sistema está involucrado en la respuesta autoinmune humoral contra tejido cardíaco en la enfermedad de Chagas, su prevalencia y especificidad. La presencia de anticuerpos que reaccionan con cortes por criostato de corazón humano grupo 0 fue investigada por la técnica de inmunofluorescencia indirecta en pacientes chagásicos y controles. Los resultados positivos fueron hallados con la siguiente prevalencia: cardiopatía chagásica crónica: 22/34 (64%); infectados asintomáticos: 16/42 (38%); infectados sin datos clínicos: 19/43 (44%); cardiopatías congénitas (pre-cirugía); 0/17 y post-cirugía: 3/5; valvulopatía reumática y cardiopatía isquémica: 7/24 (34%); lupus eritematoso sistémico: 6/15 (40%); artritis reumatoidea: 5/17 (29%); osteoartritis (pacientes en la 6ª y 7ª década de vida): 4/19 (21%); controles normales (ciudad de Buenos Aires): 2/29 (7%); controles normales (provincia de Jujuy): 3/16 (19%). La imagen observada fue intracelular siguiendo las estrías. Los experimentos de absorción con glóbulos rojos de cobayo y con proteínas purificadas de músculo demostraron que la reacción intracelular es independiente del anticuerpo EVI, y es removida con miosina. En un caso, la autorreactividad fue confirmada entre una biopsia de miocardio y el suero del mismo paciente. Los títulos de reactividad de los anticuerpos oscilaron entre 1:15 y 1:60. La IgG estuvo siempre involucrada y en algunos casos también la IgM. El anticuerpo no fija C3. El presente estudio demuestra la existencia de una verdadera reacción autoinmune con miocardio en la enfermedad de Chagas. Su significado debe ser aún demostrado, pero podría ser secundario al daño tisular