High pressure homogenization: A promising approach to expand food applications of chia mucilage.

Two chia mucilages with different viscosities, obtained by extraction conditions optimized in a previous work, were homogenized by high pressure homogenization (HPH). Particle size, molecular weight, zeta potential, FTIR spectrum, rheological properties, water absorption capacity, water holding capacity and iron binding capacity were determined on both mucilages treated and without treatment. Homogenization led to a significant reduction in viscosity respect to chia mucilage controls, which can be related to the decrease in particle size and molecular weight. A high iron binding capacity was obtained for both mucilages. FTIR spectra of both mucilages with iron showed displacements in bands related with stretching of carboxylic uronic acids, suggesting the interaction site with this mineral. This interaction was also verified by particle size determination with a displacement to higher sizes in the presence of iron. Potential zeta showed a significant reduction in the presence of iron. A model to explain the binding between chia mucilage and iron is proposed. HPH appears as an alternative to expand chia mucilage functionality reducing the viscosity of chia mucilage solutions for the offer of a new ingredient also with optimal levels of hydration and iron binding capacity.

Cytotoxic activity of Solanum tuberosum polyphenolic extracts in human hepatocarcinoma cells is mediated by apoptosis and autophagy.

Hepatocellular carcinoma (HCC) is one of the most frequent tumors worldwide, associated with a high mortality rate. HCC patient's prognosis remains unfavorable, mainly due to late diagnosis and treatment instauration delay. Thus, there is an urgent requirement for the development of new therapeutical options, particularly for advanced HCC patients. Polyphenols are specialized plant metabolites, which have been broadly characterized for their beneficial effects on human health. Potato is one of the main sources of these compounds in human diet, due to its high consumption. The objectives of this study were to: characterize the polyphenolic composition, analyze the antioxidant properties, evaluate the cytotoxic activity in human tumoral hepatocytes, and describe the molecular mechanisms involved in cell death, of potato polyphenolic extracts (PPEs) from the pigmented Andigena cultivar CL658. The results showed that phenolic acids were the main group of polyphenols in the extracts, chlorogenic acid being the major compound, followed by caffeic acid. HPLC-DAD profile showed pelargonidin as the principal anthocyanin. The treatment of HCC cell lines with the cytotoxic concentration 50 (CC50 ) of the PPEs resulted in cytotoxicity, evidenced by increases in the percentage of dead cells (5-10%) after treatments. This cytotoxic effect was mainly due to apoptosis activation, evidenced by modulation of the Bcl-2 family proteins expression, in favor of pro-apoptotic members over anti-apoptotic in the final balance. PPEs also induced autophagy, indicated by increased LC3 expression (122-274%) and autophagosomes, and reduced p62 expression (32-48%), in variable magnitudes according to the treated cell line. Overall, these results support the potential use of PPEs from the cultivar CL658 as a source of bioactive compounds for novel treatments against HCC.

Electrochemical biosensor for quantitative determination of fentanyl based on immobilized cytochrome c on multi-walled carbon nanotubes modified screen-printed carbon electrodes.

Fentanyl is a powerful synthetic opioid used to treat severe pain. New administration routes toward its illegal consumption for recreational purposes pose a growing threat to public health, either due to misuse or abuse of this substance. As a result, the rapid qualitative and quantitative determination of fentanyl in biofluids is of great interest. A novel enzymatic biosensor based on adsorptive-stripping cyclic voltammetry is proposed as a cost-effective, reliable, and efficient device for fentanyl determination in urine samples. Disposable screen-printed carbon electrodes modified with multi-walled carbon nanotubes and cytochrome c were used to develop the testing platform. The electrochemical behavior of fentanyl exhibited a well-defined anodic wave around 0.66 V vs. pseudo reference electrode. The experimental conditions were optimized to obtain the best analytical response, and linear regression analysis of increasing concentration standards was applied to estimate the performance parameters. The results suggest a simple method with a wide linearity range, high sensitivity, low limits of detection (0.086 µg/mL) and quantification, and satisfactory precision (2.9% RSD). The feasibility and applicability of the voltammetric approach were assessed by fentanyl-spiked urine samples by standard additions calibration curves in two levels of enrichment with an accuracy of 92% and 100%.

Da psicodinâmica à psicopatologia do trabalho no Brasil: (in)definições e possibilidades / De la psicodinámica a la psicopatología del trabajo em Brasil: (in)definiciónes y posibilidades / From psychodynamics to psychopathology of work in Brazil: (in)definitions and possibilities

RESUMO. O presente artigo analisou o estado da arte da psicopatologia do trabalho no Brasil, como objeto de pesquisa e como disciplina, a partir de revisão bibliográfica sistemática integrativa. Foi realizado levantamento em bases de dados virtuais utilizando os descritores 'psicopatologia do trabalho' e 'psicopatologia' (AND) 'trabalho'. Foram incluídos artigos disponibilizados integralmente em português publicados em revistas com revisão cega de pares contendo os descritores no título, resumo, palavras-chave e/ou corpo do texto. O conjunto final dos textos analisados se constituiu de 28 artigos publicados entre 1992 e 2019 majoritariamente em periódicos da psicologia com psicodinâmica do trabalho como referencial teórico e/ou metodológico. Foram ainda identificadas três tendências no uso do termo 'psicopatologia do trabalho' nos artigos: 1) psicopatologia do trabalho como objeto de estudo; 2) como disciplina; e 3) para debater as compreensões das relações entre trabalho e patologias e suas implicações na prática. Enquanto objeto de estudo, as relações entre trabalho e doença mental são negligenciadas. Como disciplina, identificaram-se imprecisões que flexibilizam ou ignoram os limites entre psicopatologia e psicodinâmica do trabalho. Ambas as tendências da literatura podem estar relacionadas com a desconsideração de fatores históricos na determinação da construção dos campos de estudo.

RESUMEN. El presente artículo analizó el estado del arte de la Psicopatología del Trabajo en Brasil, como objeto de investigación y como disciplina, a partir de revisión bibliográfica sistemática integrativa. Se realizó un levantamiento en bases de datos virtuales utilizando los descriptores 'psicopatología del trabajo' y 'psicopatología' (AND) 'trabajo'. Se incluyeron artículos disponibles integralmente en portugués publicados en revistas con revisión ciega de pares conteniendo los descriptores en el título, resumen, palabras clave y/o cuerpo del texto. El conjunto final de textos analizados se constituyó de 28 artículos publicados entre 1992 y 2019 mayoritariamente en periódicos de Psicología con Psicodinámica del Trabajo como referencial teórico y/o metodológico. Se identificaron tres tendencias en el uso del término 'psicopatología del trabajo' en los artículos: 1) psicopatología del trabajo como objeto de estudio; 2) como disciplina; y 3) para debatir las comprensiones de las relaciones entre trabajo y patologías y sus implicaciones en la práctica. En cuanto objeto de estudio, las relaciones entre el trabajo y la enfermedad mental son poco estudiadas. Como disciplina, se identificaron imprecisiones que flexibilizan o ignoran los límites entre Psicopatología y Psicodinámica del Trabajo. Ambas tendencias de la literatura pueden estar relacionadas con la desconsideración de factores históricos en la determinación de la construcción de los campos de estudio.

ABSTRACT. This article analyzed the state of the art of psychopathology of work in Brazil, as an object of study and as a subject, by performing an integrative systematic literature review. A search was conducted in virtual databases using the descriptors 'psychopathology of work' and 'psychopathology' (AND) 'work'. We included articles available in full in Portuguese, published in blind peer-reviewed journals containing the descriptors in the title, abstract, keywords and/or body of the text. The final set of texts consisted of 28 articles published between 1992 and 2019, mostly in psychology journals using psychodynamics of work as theoretical and/or methodological reference. Three trends were also identified in the use of the term 'psychopathology of work' in the articles: 1) psychopathology of work as an object of study; 2) as a subject; and 3) to discuss the understandings of the relationships between work and pathologies and their practical implications. As an object of study, the relationship between work and mental illness is neglected. As a subject, inaccuracies that flexibilize or ignore the limits between psychopathology of work and psychodynamics of work were identified. Both trends in the literature may be related to the lack of reflections that consider the Brazilian context to understand the relations between work and pathology.

Rapid Determination of the 'Legal Highs' 4-MMC and 4-MEC by Spectroelectrochemistry: Simultaneous Cyclic Voltammetry and In Situ Surface-Enhanced Raman Spectroscopy.

The synthetic cathinones mephedrone (4-MMC) and 4-methylethcathinone (4-MEC) are two designer drugs that represent the rise and fall effect of this drug category within the stimulants market and are still available in several countries around the world. As a result, the qualitative and quantitative determination of 'legal highs', and their mixtures, are of great interest. This work explores for the first time the spectroelectrochemical response of these substances by coupling cyclic voltammetry (CV) with Raman spectroscopy in a portable instrument. It was found that the stimulants exhibit a voltammetric response on a gold screen-printed electrode while the surface is simultaneously electro-activated to achieve a periodic surface-enhanced Raman spectroscopy (SERS) substrate with high reproducibility. The proposed method enables a rapid and reliable determination in which both substances can be selectively analyzed through the oxidation waves of the molecules and the characteristic bands of the electrochemical SERS (EC-SERS) spectra. The feasibility and applicability of the method were assessed in simulated seized drug samples and spiked synthetic urine. This time-resolved spectroelectrochemical technique provides a cost-effective and user-friendly tool for onsite screening of synthetic stimulants in matrices with low concentration analytes for forensic applications.

Iron-caseinglycomacropeptide complexes: Characterization and application in beverages.

Complexing iron with organic compounds has been considered an alternative strategy to mitigate the problems associated with the level of bioavailable iron and the acceptability of products supplemented with this mineral. CMP contains specific amino acids associated with iron binding. The present study aims to optimize the conditions of Fe/CMP complex formation and understand the molecular basis of interactions between CMP and iron ions. Results showed that CMP can bind ferrous iron in a 1:1.5 M ratio, forming a stable peptide-iron complex, where CMP assembles in a tetrameric form. FTIR spectra indicated that iron binding altered the secondary structures of CMP. The iron-binding sites of CMP corresponded primarily to acid residues of Glu, Asp and sialic acid. Moreover, Fe/CMP complex remained stable in a wide pH range (2.0-6.5), suggesting the adequacy to be efficiently added in food or beverages and to keeping complexed in the digestion environment. Finally, Fe/CMP complex was added to a commercial beverage (2 mg of Fe per serving of beverage) and no changes were observed in their colour during storage. A model to explain the binding between CMP and iron is proposed. These results suggest a potential application of this peptide for iron fortification.

Eritema nodoso necrosante en lepra lepromatosa asociada a infección mixta por Mycobacterium lepromatosis y Mycobacterium leprae. Reporte de caso / Necrotizing erythema nodosumin lepromatous leprosy associated with mixed infection by Mycobacterium lepromatosis and Mycobacterium leprae. Case report

RESUMEN La lepra es una enfermedad causada por Mycobacterium leprae. Su evolución crónica a veces se ve interrumpida por cuadros inmunológicos llamados reacción leprosa en pacientes con alta carga bacilar. Estos cuadros inmunológicos incrementan la morbilidad y pueden complicarse, volviéndose potencialmente mortales. En el espectro de estas reacciones, se han descrito algunas caracterizadas por lesiones vasculo necróticas, como el Fenómeno de Lucio y el eritema nodoso lepromatoso necrosante, que son asociadas a la lepra lepromatosa difusa y a la especie de bacilos recién descripta, Mycobacterium lepromatosis. Presentamos un paciente de sexo femenino de 21 años de edad, que duranteel tratamiento específico para lepra multibacilar presentó cuadros recidivantes de eritema nudoso que evolucionó a la forma necrosante. En este paciente se precisó a través de la biología molecular la presencia simultánea de M. leprae y M. lepromatosis como causantes de la enfermedad. Este caso representa la primera comunicación de M. lepromatosis en el Paraguay, y también la primera infección dual como agente causante de lepra, en asociación con el M. leprae.

ABSTRACT Leprosy is a disease caused by Mycobacterium leprae. Its chronic evolution is sometimes interrupted by immunological conditions called leprosy reaction in patients with high bacillary load. These immunological conditions increase morbidity and can be complicated, becoming life threatening. In the spectrum of these reactions, some characterized by vasculonecrotic lesions have been described, such as Lucio's Phenomenon and Necrotizing Lepromatous Nodus Erythem, which are associated with diffuse lepromatous leprosy and the species of bacilli just described, Mycobacterium lepromatosis. We present a 21-year-old female patient, who during specific treatment for multibacillary leprosy presented recurrent pictures of erythema nodosum that evolved to the necrotizing form. In this patient, the simultaneous presence of M. leprae and M. lepromatosis as the cause of the disease was determined through molecular biology. This case represents the first communication of M. lepromatosis in Paraguay, and also the first dual infection as a causative agent of leprosy, in association with M. leprae.

Eritema nodoso necrosante en lepra lepromatosa asociada a infección mixta por Mycobacterium lepromatosis y Mycobacterium leprae

La lepra es una enfermedad causada por Mycobacterium leprae. Su evolución crónica a veces se ve interrumpida por cuadros inmunológicos llamados reacción leprosa en pacientes con alta carga bacilar. Estos cuadros inmunológicos incrementan la morbilidad y pueden complicarse, volviéndose potencialmente mortales. En el espectro de estas reacciones, se han descrito algunas caracterizadas por lesiones vasculo necróticas, como el Fenómeno de Lucio y el eritema nodoso lepromatoso necrosante, que son asociadas a la lepra lepromatosa difusa y a la especie de bacilos recién descripta, Mycobacterium lepromatosis. Presentamos un paciente de sexo femenino de 21 años de edad, que durante el tratamiento específico para lepra multibacilar presentó cuadros recidivantes de eritema nudoso que evolucionó a la forma necrosante. En este paciente se precisó a través de la biología molecular la presencia simultánea de M. leprae y M. lepromatosis como causantes de la enfermedad. Este caso representa la primera comunicación de M. lepromatosis en el Paraguay, y también la primera infección dual como agente causante de lepra, en asociación con el M. leprae.

Leprosy is a disease caused by Mycobacterium leprae. Its chronic evolution is sometimes interrupted by immunological conditions called leprosy reaction in patients with high bacillary load. These immunological conditions increase morbidity and can be complicated, becoming life threatening. In the spectrum of these reactions, some characterized by vasculonecrotic lesions have been described, such as Lucio's Phenomenon and Necrotizing Lepromatous Nodus Erythem, which are associated with diffuse lepromatous leprosy and the species of bacilli just described, Mycobacterium lepromatosis. We present a 21-year-old female patient, who during specific treatment for multibacillary leprosy presented recurrent pictures of erythema nodosum that evolved to the necrotizing form. In this patient, the simultaneous presence of M. leprae and M. lepromatosis as the cause of the disease was determined through molecular biology. This case represents the first communication of M. lepromatosis in Paraguay, and also the first dual infection as a causative agent of leprosy, in association with M. leprae.

Analgesia multidimensional para los pacientes en estadio terminal por cáncer de páncreas / Multidimensional analgesia for terminal stage patients with pancreatic cancer

RESUMEN Introducción: el cáncer es la segunda causa de muerte en el mundo; los tumores del sistema digestivo ocupan el segundo lugar y según localización los de páncreas poseen la menor tasa de supervivencia. Objetivo: evaluar la efectividad de la analgesia multidimensional para los pacientes en estadio terminal por cáncer de páncreas. Métodos: se realizó un estudio cuasiexperimental, comparativo, prospectivo y longitudinal en pacientes con dolor por tumor de páncreas en etapa final de su enfermedad, en el Hospital Abel Santamaria Cuadrado desde noviembre 2016 a julio 2019. Se incluyeron todos los pacientes con dolor por tumor de páncreas en estadio terminal, se conformaron tres grupos de acuerdo con el método de analgesia empleado; Grupo I (n=10) analgesia multimodal, Grupo II (n=10) analgesia multidimensional y Grupo III (n=3) esquema de analgesia de la Organización Mundial de la Salud, se evaluó calidad de la analgesia, la necesidad de dosis de rescate y uso de morfina, se compararon los métodos y se determinó la supervivencia. Resultados: la calidad de la analgesia fue mayor en los pacientes del grupo II, en igual grupo no fue necesario el uso de morfina hasta el 7mo mes y en solo dos pacientes, (p=0,00) no hubo diferencias en las tasas de supervivencia. Conclusiones: el enfoque multidimensional de la analgesia, donde se incluya al individuo como ser biopsicosocial y a la familia, logra mayor calidad de la analgesia. El método empleado para el alivio del dolor no influye en la supervivencia.

ABSTRACT Introduction: cancer is the second leading cause of death in the world; the tumors of the digestive system occupy the second place and according to itslocation, those in the pancreas have the lowest survival rate. Objective: to assess the effectiveness of multidimensional analgesia for patients in terminal stage due to pancreatic cancer. Methods: a quasi-experimental, comparative, prospective and longitudinal study was conducted in patients with pain due to pancreatic tumor in terminal stage at Abel Santamaria Cuadrado General Teaching Hospital from November 2016 to July 2019; all patients with pain due topancreatictumor were included. In the terminal stage of pancreatic cancer, three (3) groups were completed according to the analgesia method applied; Group I (n = 10) multimodal analgesia, Group II (n = 10) multidimensional analgesia and Group III (n = 3) following WHO analgesia scheme, analgesia quality, and the need for rescue dose and application of morphine, the methods were compared and survival rate was determined. Results: the quality of analgesia was higher in patients from group II, in the same group the application of morphine was not required until the 7th month and in only two patients (p = 0.00), there were no differences in the rates of survival. Conclusions: the multidimensional approach to analgesia, where the individual is included as a biopsychosocial being and the family achieves greater quality of analgesia, the method applied for pain relief does not influence on survival.

Perioperatorio y recurrencia oncológica: reto actual en la práctica anestésica / Perioperative and cancer relapse: a challenge in current anesthetic practice

Introducción: El cáncer es la segunda causa de muerte en el mundo y en Cuba. Su estrategia de tratamiento implica fármacos oncoespecíficos y cirugía; y diariamente aumentan los pacientes intervenidos quirúrgicamente lo que conlleva a un periodo perioperatorio y la administración de múltiples medicamentos anestésicos. Objetivo: Describir los principales factores relacionados con la anestesia que, durante el perioperatorio, influyen en la recurrencia oncológica. Desarrollo: El estrés quirúrgico y la anestesia general, con la subsecuente respuesta neuroendocrina e inflamatoria, por sí mismos, limitan la respuesta inmune y alteran el balance entre el potencial metastásico del tumor y antimetastásico de las defensas, lo cual representa un mecanismo plausible en el incremento de las metástasis y recurrencia oncológica. Conclusiones: La proliferación del cáncer y recidiva tumoral en el contexto quirúrgico asociado a la anestesia, es un tema relativamente nuevo y por tanto es necesario realizar estudios con mayor alcance que validen este fenómeno. No obstante, el efecto inmunosupresor que produce el estrés perioperatorio, fármacos anestésicos como opioides y halogenados pueden ser la clave para explicar este fenómeno. La anestesia general endovenosa total libre de opioides y adecuada analgesia regional contribuyen a disminuir este efecto(AU)

Introduction: Cancer is the second cause of death worldwide and in Cuba. Its treatment strategy involves oncospecific drugs and surgery. Every day, the number of patients who undergo surgery increases, which leads to a perioperative period and the administration of multiple anesthetic medications. Objective: To describe the main factors related to anesthesia and that, during the perioperative period, influence oncological recurrence. Development: Surgical stress and general anesthesia, with the subsequent neuroendocrine and inflammatory response, by themselves, limit the immune response and alter the balance between the metastatic potential of the tumor and the antimetastatic defense, which represents a plausible mechanism for increased metastasis and oncological relapse. Conclusions: The proliferation of cancer and tumor relapse in the surgical context associated with anesthesia is a relatively new issue and it is therefore necessary to carry out studies with greater scope that validate this phenomenon. However, the immunosuppressive effect produced by perioperative stress, as well as anesthetic drugs such as opioids and halogenated drugs, can be the key to explaining this phenomenon. Total intravenous opioid-free general anesthesia and adequate regional analgesia contribute to diminish this effect(AU)

Neurolisis del plexo celiaco en cáncer de páncreas / Neurolysis of the celiac plexus in pancreas cancer

Introducción: El cáncer en Cuba constituye la primera causa de mortalidad en edades de 15 a 64 años y la segunda en mayores de 65, los tumores digestivos ocupan la tercera posición en las neoplasias malignas y la afección pancreática el cuarto lugar dentro de estas. Objetivo: Presentar la evolución de un paciente con un tumor de páncreas y una supervivencia de más de 6 meses al cual se le realizó neurolisis del plexo celiaco. Presentación del caso: Paciente masculino de 64 años de edad con el diagnóstico de adenocarcinoma de cuerpo y cola de páncreas sin criterio quirúrgico con dolor de severa intensidad que imposibilita el inicio del tratamiento adyuvante para lo cual se le realizó neurolisis del plexo celiaco bilateral, con 7 mL de fenol al 10 por ciento por cada lado, vía posterior retrocrural bajo seguimiento con intensificador de imágenes, y se administró tratamiento coadyuvante vía oral a base de antidepresivos tricíclicos, analgésicos y ansiolíticos debido al componente mixto del dolor oncológico. Conclusiones: El bloqueo neurolitico del plexo celiaco asociado a terapia farmacológica analgésica convencional por vía oral proporcionó un alivio total del dolor por neoplasia de páncreas de forma inmediata y duradera, se logró mejorar el estado general del paciente lo cual facilitó el inicio de la terapia adyuvante oncológica(AU)

Introduction: In Cuba, cancer is the leading cause of death at ages 15-64 and the second at ages over 65, digestive tumors occupy the third position among malignancies and pancreatic affection the fourth place among these. Objective: To present the evolution of a patient with a pancreatic tumor and survival of more than 6 months who underwent neurolysis of the celiac plexus. Case presentation: A 64-year-old male patient diagnosed with adenocarcinoma of the body and tail of the pancreas without surgical criteria, with pain of severe intensity that made it impossible to start adjuvant treatment, for which he underwent neurolysis of the bilateral celiac plexus, with 7 mL of phenol-10 percent per side, through the retrocrural posterior space with follow-up with image intensifier, and oral adjuvant treatment was administered with tricyclic, analgesic and anxiolytic antidepressants due to the mixed component of oncological pain. Conclusions: The neurolytic block of the celiac plexus associated with conventional oral analgesic pharmacological therapy provided total relief of pain from pancreatic cancer in an immediate and lasting way. It was possible to improve the general state of the patient, which facilitates the start of adjuvant oncology therapy(AU)

Arginine vasopressin receptor 1a is a therapeutic target for castration-resistant prostate cancer.

Castration-resistant prostate cancer (CRPC) recurs after androgen deprivation therapy (ADT) and is incurable. Reactivation of androgen receptor (AR) signaling in the low androgen environment of ADT drives CRPC. This AR activity occurs through a variety of mechanisms, including up-regulation of AR coactivators such as VAV3 and expression of constitutively active AR variants such as the clinically relevant AR-V7. AR-V7 lacks a ligand-binding domain and is linked to poor prognosis. We previously showed that VAV3 enhances AR-V7 activity to drive CRPC progression. Gene expression profiling after depletion of either VAV3 or AR-V7 in CRPC cells revealed arginine vasopressin receptor 1a (AVPR1A) as the most commonly down-regulated gene, indicating that this G protein-coupled receptor may be critical for CRPC. Analysis of publicly available human PC datasets showed that AVPR1A has a higher copy number and increased amounts of mRNA in advanced PC. Depletion of AVPR1A in CRPC cells resulted in decreased cell proliferation and reduced cyclin A. In contrast, androgen-dependent PC, AR-negative PC, or nontumorigenic prostate epithelial cells, which have undetectable AVPR1A mRNA, were minimally affected by AVPR1A depletion. Ectopic expression of AVPR1A in androgen-dependent PC cells conferred castration resistance in vitro and in vivo. Furthermore, treatment of CRPC cells with the AVPR1A ligand, arginine vasopressin (AVP), activated ERK and CREB, known promoters of PC progression. A clinically safe and selective AVPR1A antagonist, relcovaptan, prevented CRPC emergence and decreased CRPC orthotopic and bone metastatic growth in mouse models. Based on these preclinical findings, repurposing AVPR1A antagonists is a promising therapeutic approach for CRPC.

Effect of Nanoparticles on Modified Screen Printed Inhibition Superoxide Dismutase Electrodes for Aluminum.

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme superoxide dismutase has been developed. The oxidation signal of epinephrine substrate was affected by the presence of Al(III) ions leading to a decrease in its amperometric current. The immobilization of the enzyme was performed with glutaraldehyde on screen-printed carbon electrodes modifiedwith tetrathiofulvalene (TTF) and different types ofnanoparticles. Nanoparticles of gold, platinum, rhodium and palladium were deposited on screen printed carbon electrodes by means of two electrochemical procedures. Nanoparticles were characterized trough scanning electronic microscopy, X-rays fluorescence, and atomic force microscopy. Palladium nanoparticles showed lower atomic force microscopy parameters and higher slope of aluminum calibration curves and were selected to perform sensor validation. The developed biosensor has a detection limit of 2.0 ± 0.2 µM for Al(III), with a reproducibility of 7.9% (n = 5). Recovery of standard reference material spiked to buffer solution was 103.8% with a relative standard deviation of 4.8% (n = 5). Recovery of tap water spiked with the standard reference material was 100.5 with a relative standard deviation of 3.4% (n = 3). The study of interfering ions has also been carried out.

A chronoamperometric screen printed carbon biosensor based on alkaline phosphatase inhibition for W(IV) determination in water, using 2-phospho-L-ascorbic acid trisodium salt as a substrate.

This paper presents a chronoamperometric method to determine tungsten in water using screen-printed carbon electrodes modified with gold nanoparticles and cross linked alkaline phosphatase immobilized in the working electrode. Enzymatic activity over 2-phospho-l-ascorbic acid trisodium salt, used as substrate, was affected by tungsten ions, which resulted in a decrease of chronoamperometric current, when a potential of 200 mV was applied on 10 mM of substrate in a Tris HCl buffer pH 8.00 and 0.36 M of KCl. Calibration curves for the electrochemical method validation, give a reproducibility of 5.2% (n = 3), a repeatability of 9.4% (n = 3) and a detection limit of 0.29 ± 0.01 µM. Enriched tap water, purified laboratory water and bottled drinking water, with a certified tungsten reference solution traceable to NIST, gave a recovery of 97.1%, 99.1% and 99.1% respectively (n = 4 in each case) and a dynamic range from 0.6 to 30 µM. This study was performed by means of a Lineweaver-Burk plot, showing a mixed kinetic inhibition.

Acetylcholinesterase inhibition-based biosensor for aluminum(III) chronoamperometric determination in aqueous media.

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme acetylcholinesterase has been developed. The immobilization of the enzyme was performed on screen-printed carbon electrodes modified with gold nanoparticles. The oxidation signal of acetylthiocholine iodide enzyme substrate was affected by the presence of Al(III) ions leading to a decrease in the amperometric current. The developed system has a detection limit of 2.1 ± 0.1 µM for Al(III). The reproducibility of the method is 8.1% (n = 4). Main interferences include Mo(VI), W(VI) and Hg(II) ions. The developed method was successfully applied to the determination of Al(III) in spiked tap water . The analysis of a certified standard reference material was also carried out. Both results agree with the certified values considering the respective associated uncertainties.

A disposable alkaline phosphatase-based biosensor for vanadium chronoamperometric determination.

A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 µM, a repeatability of 7.7% (n = 4) and a reproducibility of 8% (n = 3). A study of the possible interferences shows that the presence of Mo(VI), Cr(III), Ca(II) and W(VI), may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water.

Thick-film voltammetric pH-sensors with internal indicator and reference species.

The following paper describes the development of a screen-printed voltammetric pH-sensor based on graphite electrodes incorporating both internal indicator (i.e., phenanthraquinone) and reference species (i.e., dimethylferrocene). The key advantages of this type of system stem from its simplicity, low cost and ease of fabrication. More importantly, as opposed to conventional voltammetric systems where the height of the voltammetric peaks is taken into account to quantify the amount of a species of interest, here, the difference between the peak potential of the indicator species and the peak potential of the reference species is used. Thus, this measurement principle makes the electrochemical system presented here less dependent on the potential of the reference electrode (RE), as is often the case in other electrochemical systems. The developed system displays very promising performances, with a reproducible Super Nernstian response to pH changes and a lifetime of at least nine days.

Estudio toxicológico preclínico de la Psidium guajava L. (guayaba) / Toxicologic preclinical study of Psidium guajava L. (guayaba)

El estudio toxicológico preclínico se realizó con hojas secas de Psidium guajava L. A este material vegetal se le efectuó un estudio toxicológico agudo por 2 métodos: 1) dosis letal media LD50 en ratones suizos (OF1) y 2) toxicología alternativa (clases tóxicas agudas) en ratas Wistar. También se realizó la evaluación genotóxica de 2 extractos, uno acuoso y otro hexánico en un sistema in vitro de ensayo de inducción de segregación somática a corto plazo en el hongo Aspergillus nidulans, y un ensayo in vivo de la droga seca en el test de inducción de micronúcleos en médula ósea de ratón. Los resultados toxicológicos no arrojaron muertes en ninguno de los 2 modelos experimentales en el rango de dosis empleando hasta 2 000 mg/kg/p.c. y los resultados histológicos no sugieren daños atribuibles a toxicidad del material vegetal probado. En el estudio in vitro con Aspergillus nidulans D-30, los resultados demuestran la ausencia de efecto genotóxico de estos extractos, así como en el sistema de inducción de micronúcleos en médula ósea de ratón

Estudio toxicológico preclínico de la Psidium guajava L.(guayaba) / Toxicologic preclinical study of Psidium guajava L. (guayaba)

El estudio toxicológico preclínico se realizó con hojas secas de Psidium guajava L. A este material vegetal se le efectuó un estudio toxicológico agudo por 2 métodos: 1) dosis letal media LD50 en ratones suizos (OF1) y 2) toxicología alternativa (clases tóxicas agudas) en ratas Wistar. También se realizó la evaluación genotóxica de 2 extractos, uno acuoso y otro hexánico en un sistema in vitro de ensayo de inducción de segregación somática a corto plazo en el hongo Aspergillus nidulans, y un ensayo in vivo de la droga seca en el test de inducción de micronúcleos en médula ósea de ratón. Los resultados toxicológicos no arrojaron muertes en ninguno de los 2 modelos experimentales en el rango de dosis empleando hasta 2 000 mg/kg/p.c. y los resultados histológicos no sugieren daños atribuibles a toxicidad del material vegetal probado. En el estudio in vitro con Aspergillus nidulans D-30, los resultados demuestran la ausencia de efecto genotóxico de estos extractos, así como en el sistema de inducción de micronúcleos en médula ósea de ratón(AU)

Ausencia de actividad antimicrobiana de un extracto acuoso liofilizado de Aloe vera (Sabila) / Absence of antimicrobial activity of lyophilized aqueous extract of Aloe vera (sabila)

Se estudio la actividad antimicrobiana de dos concentraciones (10 y 50 mg/mL) de un extracto acuoso liofilizado de hojas de Aloe vera (sabila), mediante el sistema de ensayo de difusion en agar, con una bateri aminima de cepas de microorganismos compuesta por cuatro bacterias (Staphylococcus aureus, Bacillus subtilils, Escherichia coli y Pseudomonas aeruginosa) y una levadura (Candida albicans). Los resultados indican que solo frente al Staphylococcus aureus se obteine una ligera actividad inhibitoria, al compararla con la que produce el control positivo (estreptomicina). Para el resto de los microorganismos estudiados la respuesta es negativa. Estos resultados permiten desestimar el uso del extracto acuoso liofilizado de Aloe vera como antimicrobiano, en tanto que sugiere explorar este efecto con otro tipo de extracto con el objetivo de avalar o no la utilizacion de esta planta como antimicrobiano