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BACKGROUND: The immune system is able to recognize substances that originate from inside or outside the body and are potentially harmful. Foreign substances that bind to immune system components exhibit antigenicity and are defined as antigens. The antigens exhibiting immunogenicity can induce innate or adaptive immune responses and give rise to humoral or cell-mediated immunity. The antigens exhibiting mitogenicity can cross-link cell membrane receptors on B and T lymphocytes leading to cell proliferation. All antigens vary greatly in physicochemical features such as biochemical nature, structural complexity, molecular size, foreignness, solubility, and so on. OBJECTIVE: Thus, this review aims to describe the molecular bases of protein-antigenicity and those molecular bases that lead to an immune response, lymphocyte proliferation, or unresponsiveness. CONCLUSION: The epitopes of an antigen are located in surface areas; they are about 880-3,300 Da in size. They are protein, carbohydrate, or lipid in nature. Soluble antigens are smaller than 1 nm and are endocytosed less efficiently than particulate antigens. The more the structural complexity of an antigen increases, the more the antigenicity increases due to the number and variety of epitopes. The smallest immunogens are about 4,000-10,000 Da in size. The more phylogenetically distant immunogens are from the immunogen-recipient, the more immunogenicity increases. Antigens that are immunogens can trigger an innate or adaptive immune response. The innate response is induced by antigens that are pathogen-associated molecular patterns. Exogenous antigens, T Dependent or T Independent, induce humoral immunogenicity. TD protein-antigens require two epitopes, one sequential and one conformational to induce antibodies, whereas, TI non-protein-antigens require only one conformational epitope to induce low-affinity antibodies. Endogenous protein antigens require only one sequential epitope to induce cell-mediated immunogenicity.

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BACKGROUND: Immunization or vaccination is the process of inducing artificial immunity against an antigen taking advantage of the mechanisms of immunological memory. Current vaccines include substances known as adjuvants, which tend to improve the immunogenicity of the antigen, reduce the antigen quantity employed, and boost the immune response in weak responders. Unfortunately, only a few vaccine adjuvants are approved for human use. OBJECTIVE: Thus, the objective of this study was to investigate the effect of Tannic acid on humoral and cell-mediated immunity against bovine serum albumin (BSA) as a protein antigen in Wistar rats. METHODS: In order to establish the Tannic acid concentration to test it as an adjuvant, the lethal dose 50 and maximum non-toxic dose were calculated through cytotoxicity and hemolytic assays with J774 A.1 cell line and rat erythrocytes by resazurin reduction method and UV/vis spectrophotometry. Thirty Wistar rats were divided into 5 groups that included two controls without antigen and three treatment groups of adjuvants plus BSA as a protein antigen. The rats were immunized in a 30-day scheme. Blood samples were collected for humoral immunity analysis by means of immunoglobulin quantification, isotyping and antigen-antibody precipitation inhibition analysis. Rat peritoneal macrophages and splenocytes were isolated for cell-mediated immunity analysis by means of nitric oxide quantification from adjuvant stimulated peritoneal macrophages and lymphocytes proliferation assay. RESULTS: Tannic acid was capable of increasing the immunogenicity of the antigen; besides, it was able to stimulate cell-mediated immunity by means of increased lymphocyte proliferation. Moreover, Tannic acid improved the humoral response by means of increased specific antibodies titers. These activities may be attributed to pattern recognition receptors stimulation. CONCLUSION: Tannic acid was considered biocompatible when tested in vivo because the concentration tested did not show cytotoxicity or hemolytic effect, and there was no detrimental effect observed on the animals' health. These results show Tannic acid as a promising candidate for vaccine adjuvant.

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In accidental intoxicated animals and humans, Karwinskia humboldtiana (Kh) causes lesions in the central and peripheral nervous system and organs like the kidney, liver, and lung. The objective was to evaluate the histology of myocardium and skeletal muscle after experimental chronic intoxication with mature fruit of Kh in Wistar rat. Twenty-five rats were used and divided into five groups (n = 5): four intoxicated and one control. Kh fruit was ground, dried, sieved, and administered by an orogastric tube. Intoxicated rats received 3.5 g/kg body weight fractionated in 5 doses. Control rats received only water. Animals were euthanized at 24, 48, 58, and 112 days, respectively. Samples of the myocardium and skeletal muscle were obtained and processed for light microscopy evaluation. Morphological analyses were performed, including a microdensitometric analysis. Results showed areas of necrosis in the muscle fibers, fibers with vacuolated cytoplasm, and disorganization of myofilaments, as well as staining variations in both myocardium and skeletal muscle time-depending. Zones with loss of continuity of the external lamina were identified with PAS with the diastase histochemical method. Immunolabeling with specific antibodies demonstrated diminution of actin and desmin myofilaments. The microdensitometric analysis showed a statistically significant difference between the intoxicated vs control group. These findings demonstrate that chronic intoxication of Kh fruit also causes damage in myocardial and skeletal muscle, these alterations will be useful to understand that the toxic effects of Kh fruit in accidently intoxicated humans are systemic, and not only over the nervous system.

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SUMMARY: The purpose of this study was to evaluate by morphological methods, if a mixture of Fibroquel® and hyaluronic acid implanted in an animal model of cranial bone injury could promote bone regeneration. 12 Wistar rats were divided in three groups, control group, bone injury without treatment and bone injury with treatment. After experimental period, bone samples were taken and stained with H & E, Masson trichrome, PAS-D, immunohistochemistry with anti-PCNA monoclonal antibody and applied a semiquantitative morphometric method. Treatment group showed extensive areas of collagen fibers in contact with normal bone tissue, areas of normal histology, PAS positive material and less cellular proliferation. We demonstrated for the first time that a mixture of Fibroquel® and hyaluronic acid implanted in an animal model of cranial bone injury promotes bone regeneration.

RESUMEN: El propósito de este estudio fue evaluar por métodos morfológicos, si una mezcla de Fibroquel® y ácido hialurónico implantado en un modelo animal de lesión del hueso craneal podría promover la regeneración ósea. Se dividieron 12 ratas Wistar en tres grupos, grupo control, lesión ósea sin tratamiento y lesión ósea con tratamiento. Después del período experimental, se tomaron muestras de hueso y se tiñeron con H & E, tricrómico de Masson, PAS-D, inmunohistoquímica con anticuerpo monoclonal anti-PCNA y se aplicó un método morfométrico semicuantitativo. El grupo de tratamiento mostró áreas extensas de fibras de colágeno en contacto con tejido óseo normal, áreas de histología normal, material PAS positivo y menor proliferación celular. Demostramos por primera vez que una mezcla de Fibroquel® y ácido hialurónico implantado en un modelo animal de lesión del hueso craneal promueve la regeneración ósea.

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BACKGROUND: The COVID-19 pandemic had infected more than 3.5M people around the world and more than 250K people died in 187 countries by May 2020. The causal agent of this disease is a coronavirus whose onset of symptoms to death range from 6 to 41 days with a median of 14 days. This period is dependent on several factors such as the presence of comorbidities, age and the efficiency of the innate or adaptive immune responses. METHODS: The effector mechanisms of both types of immune responses depend on the pathogen involved. In the case of a viral infection, the innate immune response may approach the harmful virus through pattern recognition receptors inducing an antiviral state. RESULTS: On the other hand, the adaptive immune response activates antibody production to neutralize or eliminate the virus. Phenolics are plant secondary metabolites with many biological activities for plants and humans against infection. Chemical modification of proteins may enhance their biological properties; thus, a protein of medical interest, for instance, a viral protein can be used as a scaffold to build a biopharmaceutical conjugated or complexated with phenolics exhibiting structural complexity or biological activities to achieve effective phenolic-protein-based therapeutics like vaccine adjuvant complexes, immunogen conjugates, and antiviral conjugates. CONCLUSION: Pharmaceutical biotechnology applies the principles of biotechnology to develop biopharmaceuticals for protein-based therapeutics; such as adjuvants, recombinant proteins, monoclonal antibodies, and antivirals. As neither a vaccine nor a treatment for COVID-19 is currently available, this manuscript focuses on insights from pharmaceutical biotechnology into phenolic biopharmaceuticals against COVID-19.

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Various cell types participate in the tumor process, in which the mast cells have been described; however, the role they play in colorectal adenocarcinoma has not yet been fully understood. Therefore, the present work aimed to compare employing histochemistry and immunohistochemistry, the number of mast cells and the content of some cytoplasmic granules in moderately differentiated non-metastatic and metastatic colorectal adenocarcinoma, analyzing tissue samples from patients. Histochemical techniques with Toluidine Blue (TBO), Periodic Schiff Acid (PAS), Alcian Blue/Periodic Acid-Schiff (PAB) and Alcian Blue/Safranin (ABS); as well as immunohistochemical reactions with anti-antibodies anti-Tryptase and anti-Chymase were applied to quantify total mast cells and content of some cytoplasmic granules. Statistical analysis was performed using SPSS V22.0 software (p ≤ 0.05). The degree of positivity of the reaction and degranulation of mast cells was reported in percentages. In our results, we observed that there are differences in the quantity and histochemical composition of the granules of mast cells (metastatic group PAS and ABS comparing the TBO reaction), as well as in the immunohistochemical composition between Tryptase and Chymase and the number of degranulated cells in both study groups (74 % degranulated mast cells in the metastatic group, 66 % integrate mast cells in the non-metastatic group). Therefore, we consider that the differences may be some of the probable factors that lead to metastasis of colorectal adenocarcinoma.

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All-trans retinoic acid (ATRA) has been extensively studied as an integrating component of endocrine functions in the pancreas. The aim of this study was to evaluate the effects of ATRA on physiopathological biomarkers in an experimental model of rat with type 1 diabetes induced by alloxan (T1D). Twenty Wistar rats were divided equally into five groups, each receiving a different treatment: a control group (CG), a diabetic group without T1D treatment, a diabetic group treated with ATRA, a diabetic group supplemented with vitamin E (VIT E), and a group that was given olive oil (V). The administration of ATRA for 17 days produced a significant reduction in weight and glucose levels, compared to the T1D and VIT E groups. The evaluation of total antioxidant capacity (TAC) and lipoperoxidation showed no relevant difference among the groups. The results of the histological analysis showed similarities both in the size and in the number of islets of Langerhans in the pancreatic tissue obtained from the ATRA group and the CG. ATRA displayed a significant reduction of glycemic values in diabetic rats. Ultrastructurally, ß-cells, acinar, and ductal cells restored their normal appearance. ATRA can contribute to the recovery of pancreatic damage due to alloxan induction. It seems that the antioxidant effect of ATRA is not responsible for the differences observed.

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El Theracal TM LC es un cemento silicato de calcio (Ca) modificado con resina (SMCR) que ha demostrado ser un material ideal para el tratamiento dentino-pulpar por su alta tasa de formación de calcio. Los biomateriales por su contenido de Ca tienden a tener un aumento en su biodisponibilidad, estimulando la formación del puente dentario atreves de las células involucradas en la formación de tejidos mineralizados, promoviendo la diferenciación de fibroblastos en odontoblastos y aumentando la actividad de la enzima pirofostasa responsable en la mineralización de la dentina. El presente estudio con el objetivo de evaluar la respuesta inflamatoria a Theracal TM LC subcutáneamente en ratas Wistar. Fueron usados seis ratas cepa Wistar en las cuales se realizaron cuatro bolsillos quirúrgicos subcutáneos. Cada uno de estos bolsillos se determinó como cuadrante distinto, conteniendo los siguientes implantes: 1 Theracal TM LC en tubo polietileno, 2 tubo de polietileno, 3 Theracal TM LC directo y 4 como control. Las muestras histológicas se procesaron y se evaluaron distintos tipos celulares mediante conteo a microscopio de luz a 100X utilizando las tinciones H&E y AT pH 2.3. Los resultados mostraron que existen diferencias significativas en todos los tipos celulares observados durante los diferentes tiempos de exposición. Las diferencias en los tipos celulares observados podrían ser debido al tiempo de exposición al Theracal TM LC, al tubo polietileno y a ambos. El tejido evaluado del implante del tubo polietileno y al tubo polietileno con Theracal TM LC, presentan mayor respuesta inflamatoria, a diferencia en el tejido implantado con Theracal TM LC directamente.

TheraCalTM LC is a resin-modified calcium silicate (Ca) resin (SMCR) that has proven to be an ideal material for dentin-pulp treatment due to its high rate of calcium formation. Biomaterials due to their Ca content tend to have an increase in their bioavailability, stimulating the formation of the dental bridge through the cells involved in the formation of mineralized tissues, promoting the differentiation of fibroblasts in odontoblasts and increasing the activity of the pyrophosphate enzyme responsible in dentin mineralization. The present study aimed to evaluate the inflammatory response to TheracalTM LC subcutaneously in Wistar rats. Six Wistar strain rats were used in which four subcutaneous surgical pockets were made. Each of these pockets was determined as a different quadrant, containing the following implants: 1 TheracalTM LC in polyethylene tube, 2 polyethylene tubes, 3 TheracalTM LC direct and 4 as control. The histological samples were processed, and different cell types were evaluated by light microscopy at 100X using the H&E and AT pH 2.3 stains. The results showed that there are significant differences in all cell types observed during the different exposure times. The differences in the cell types observed could be due to the exposure time to TheracalTM LC, to the polyethylene tube and to both. The evaluated tissue of the polyethylene tube implant and the polyethylene tube with TheracalTM LC present a greater inflammatory response, unlike in the tissue implanted with TheracalTM LC directly.

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RESUMEN: Estudios recientes han demostrado que los compuestos activos presentes en extractos de C. chayamansa, E. prostrata y J. dioica tienen propiedades antioxidantes. Los resultados obtenidos en nuestro estudio fueron compuestos fenólicos solubles mostraron en C. chayamansa 6,34, E. prostrata 10,67, J. dioica 1,83 mg equiv de ácido gálico/gm BS respectivamente. Los antioxidantes solubles en agua por el método ABTS fueron para C. chayamansa 5.9, E. prostrata 12.7 y para J. dioica 2.5 mM equiv. de trolox/gr BS. Los resultados histopatológicos muestran una mejoría en los tejidos tratados con los extractos después de la inducción a hiperglicemia.

SUMMARY: Recent studies have shown that the active compounds present in extracts of C. chayamansa, E. prostrata and J. dioica have antioxidant properties. The results obtained in our study were soluble phenolic compounds showed in C. chayamansa 6.34, E. prostrata 10.67, J. dioica 1.83 mg equiv of gallic acid/gm BS respectively. The antioxidants soluble in water by the ABTS method were for C. chayamansa 5.9, E. prostrata 12.7 and for J. dioica 2.5 mM equiv. of trolox/gr BS. The histopathological results show an improvement in the tissues treated with the extracts after the induction to hyperglycemia.

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Karwinskia parvifolia possesses the highest concentration levels of the anthracenone T-514 (PA1). Studies have demonstrated the induction of apoptosis by PA1 in cancer cell lines. The aim was to investigate the effects of PA1 on the apoptosis of the mouse liver in vivo and its underlying pathway. Sixty CD-1 mice were divided into three groups: untreated, vehicle, and treated with PA1. The animals were euthanized at 4, 8, 12, and 24 h post-treatment. To confirm the toxic effect of PA1 we determined the activity of catalase. Liver sections were prepared for morphological examination and for immunohistochemical evaluation of anti and pro-apoptotic markers. DNA fragmentation was detected by TUNEL assay and electrophoresis. Pre-apoptotic mitochondrial alterations and cytochrome c oxidase activity were analyzed by transmission electron microscopy. PA1 induced pre-apoptotic mitochondrial alterations, a high activity of the cytochrome oxidase, and apoptosis in hepatocytes. PA1 caused p53 over-expression and down regulation of PCNA. PA1 also increased the expression levels of the pro-apoptotic markers Bax and Bak, whereas the anti-apoptotic molecule Bcl-2 was decreased. PA1 induces apoptosis by activating the intrinsic mitochondrial apoptotic pathway. These results will be useful for studies regarding the use of PA1 as an antineoplastic agent.

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