In vivo assay to identify bacteria with ß-glucosidase activity

Background: ß-Glucosidase assay is performed with purified or semipurified enzymes extracted from cell lysis. However, in screening studies, to find bacteria with ß-glucosidase activity among many tested bacteria, a fast method without cell lysis is desirable. In that objective, we report an in vivo ß-glucosidase assay as a fast method to find a ß-glucosidase producer strain. Results: The method consists in growing the strains for testing in a medium supplemented with the artificial substrate p-nitrophenyl-ß-glucopyranoside (pNPG). The presence of ß-glucosidases converts the substrate to p-nitrophenol (pNP), a molecule that can be easily measured in the supernatant spectrophotometrically at 405 nm. The assay was evaluated using two Bifidobacterium strains: Bifidobacterium longum B7254 strain that lacks ß-glucosidase activity and Bifidobacterium pseudocatenulatum B7003 strain that shows ß-glucosidase activity. The addition of sodium carbonate during pNP measurement increases the sensitivity of pNP detection and avoids the masking of absorbance by the culture medium. Furthermore, we show that pNP is a stable enzymatic product, not metabolized by bacteria, but with an inhibitory effect on cell growth. The ß-glucosidase activity was measured as units of enzyme per gram per minute per dry cell weight. This method also allowed the identification of Lactobacillus strains with higher ß-glucosidase activity among several lactobacillus species. Conclusion: This in vivo ß-glucosidase assay can be used as an enzymatic test on living cells without cell disruption. The method is simple, quantitative, and recommended, especially in studies screening for bacteria not only with ß-glucosidase activity but also with high ß-glucosidase activity.

Outro inferno de Dante numa mina de ouro na época de Vargas: Nova Lima, Minas Gerais / Another Dante's inferno in a gold mine during the Vargas era: Nova Lima, Minas Gerais

O artigo analisa as estratégias de controle existentes no trabalho na mina de Morro Velho, Minas Gerais, e as mudanças resultantes da implementação da legislação trabalhista durante o governo Vargas. Discute as doenças causadas pelo trabalho na mina, silicose e arsenicismo, através de depoimentos de ex-mineiros e do livro de um autor anônimo que aborda as doenças e as relações de poder entre patrões e empregados, apontando os limites da legislação e das lutas operárias. O livro traz um depoimento contundente de como a empresa proprietária, inglesa, burlou, durante muito tempo, leis como a da taxa de insalubridade. Direito que outras mineradoras, não só de propriedade inglesa, costumavam e até hoje costumam desrespeitar pelo mundo.

This article analyzes the control strategies in place at Morro Velho mine in the Brazilian state of Minas Gerais, and the changes after the implementation of labor legislation during the Vargas administration. The diseases common amongst mine workers, silicosis and arsenicosis, are investigated through statements given by former miners and a book by an anonymous author that discusses the diseases and the power relations between employers and employees, identifying the limitations of the legislation and the workers’ struggles. The book presents a striking story of how for many years the British company side-stepped laws such as the insalubrity premium, a right which other mining companies, not only of British ownership, flouted and still flout in different parts of the world.

Spectroscopic studies on the interaction of efonidipine with bovine serum albumin

Efonidipine hydrochloride is an antihypertensive and antianginal agent with fewer side effects and is better tolerated in the treatment of hypertension with renal impairment. Its interaction with bovine serum albumin (BSA) is of great use for the understanding of the pharmacokinetic and pharmacodynamic mechanisms of the drug. The binding of efonidipine to BSA was investigated by fluorescence spectroscopy and circular dichroism. BSA fluorescence was quenched by efonidipine, due to the fact that efonidipine quenched the fluorescence of tryptophan residues mainly by the collision mode. The thermodynamic parameters ÄH0 and ÄS0 were 68.04 kJ/mol and 319.42 J·mol-1·K-1, respectively, indicating that the hydrophobic interactions played a major role. The results of circular dichroism and synchronous fluorescence measurements showed that the binding of efonidipine to BSA led to a conformational change of BSA. The fraction of occupied sites (è) for the 8-anilino-1-naphthalein-sulfonic acid (ANS)-BSA system is 85 percent, whereas for the NZ-105-BSA system, it is 53 percent, which suggests that the interaction of ANS with BSA is stronger than that of NZ-105 with BSA. Binding studies in the presence of ANS indicated that efonidipine competed with ANS for hydrophobic sites of BSA. The effects of metal ions on the binding constant of the efonidipine-BSA complex were also investigated. The presence of metal ions Zn2+, Mg2+, Al3+, K+, and Ca2+ increased the binding constant of efonidipine_BSA complex, which may prolong the storage period of NZ-105 in blood plasma and enhance its maximum effects.

Small-molecule aggregation inhibitors reduce excess amyloid in a trisomy 16 mouse cortical cell line

We have previously characterized a number of small molecule organic compounds that prevent the aggregation of the β-amyloid peptide and its neurotoxicity in hippocampal neuronal cultures. We have now evaluated the effects of such compounds on amyloid precursor protein (APP) accumulation in the CTb immortalized cell line derived from the cerebral cortex of a trisomy 16 mouse, an animal model of Down's syndrome. Compared to a non-trisomic cortical cell line (CNh), CTb cells overexpress APP and exhibit slightly elevated resting intracellular Ca2+ levéis ([Ca2+]¡). Here, we show that the compounds 2,4-dinitrophenol, 3-nitrophenol and 4-anisidine decreased intracellular accumulation of APP in CTb cells. Those compounds were non-toxic to the cells, and slightly increased the basal [Ca2+]¡. Results indícate that the compounds tested can be leads for the development of drugs to decrease intracellular vesicular accumulation of APP in trisomic cells.

Necesidad del uso de cromógenos para cuantificar promastigotes de Leishmania en placas de 96 pozos / The need for the use of chromogens for quantifying Leishmania promastigotes on plates from 96 wells

The existing difficulties in the treatment of leishmaniasis justify the testing of the effect of new products on parasite forms in the search of a therapeutic alternative for the parasitosis. Given the need of establishing a method to evaluate the activity of natural synthetic products in vitro under the Cuban conditions, this paper was aimed at defining the usefulness of p-nitrophenilphosphate as a chromogenic substance for quantification of parasites in plaques from 96 wells. To standardize this colorimetric method the stages of the parasite growth curve were set. The study of linearity and selection of the sample size, which was optional for these assays, showed that it was possible to obtain maximum linear determination coefficient with 20 mm. Likewise, the variation coefficient was compared with and without the chromogen and the effect of changes in culture medium on the reading of absorbances was analyzed. The set limit of quantification proved the need of using chromogen for the purposes of this paper and the general results allow to recommend this less subjective, simpler and quicker methodology to test products of interest in this field.

Validación de la técnica para la determinación cuantitativa del Disofenol por Potenciometría / Validation of the technique for the quantitative determination of disophenol by potentiometry

Se realizó la validación prospectiva del método desarrollado para la determinación cuantitativa del disofenol, un compuesto de actividad antihelmíntica reconocida, mediante una valoración potenciométrica de neutralización en un medio no acuoso. Teniendo en cuenta la clasificación del método, se evaluaron los parámetros: específicidad, linealidad, precisión y exactitud. Los resultados obtenidos demostraron que la técnica es fiable, pues permitió la determinación del compuesto estudiado en presencia de 4-nitrofenol (impureza de la síntesis); además el procesamiento estadístico de los resultados evidenció la linealidad, precisión y exactitud del método

Metabolitos nitrofenólicos urinarios de insecticidas organofosforados / Nitrophenols urinary metabolite od organophosphorus insecticides

El nivel urinario de nitrofenoles puede constituir un indicador adecuado de esposición a insecticidas organofosforados, que contienen dichos grupos en su molécula. Se detalla la metodología para la evaluación de p-nitrofenol y p-nitrocresol en orina. Se hidrolizan 3 ml de orina con HCI (c), en un baño de agua a ebullición y luego se extraen los nitrofenoles con n-hexano-éter etílico 70:30. Tratando, posteriormente, una alicuota del extracto orgánico con hexametildisilazano en hexano, se forman los derivados sililados, que se cuantifican por CGL, empleando una columna de 3% SE-30 y detector de captura electrónica de 63Ni. El método descripto constituye una simplificación del recomendado por la Agencia para la Protección Ambiental (EPA), de los Estados Unidos, para la determinación de p-nitrofenol. Es sensible, preciso y se detectan 50 ng/ml de p-nitrofenol y 100 ng/ml de p-nitrocresol en la orina. La recuperación es superior al 85%. La aplicación del método a orina de ratas tratadas con paratión o fenitrotión, permitió encontrar picos coincidentes con los tiempos de retención del p-nitrofenol y p-nitrocresol, respectivamente. Será de utilidad en Toxicología Ocupacional para evaluar el grado de contaminación de trabajadores que emplean paratión, metil paratión y/o fenitrotión.

Capillária hepática: relato de caso na infância / Capillária hepática: report of a case in childhood

A infecçäo por Capilária hepática é rara em humanos sendo, a maioria dos casos, diagnosticados à autópsia. Os autores relatam um caso de diagnóstico histopatológico em um menino de 17 meses; apresentam sua evoluçäo clínico-laboratorial e destacam o sucesso obtido com a terapêutica empregada

Infeccao humana por Capillaria hepatica.Relato de um caso tratado com exito. / Human infection due to Capillaria hepatica. Report of a case sucessfully treated

Os autores tecem comentarios a respeito da biologia da Capillaria hepatica, encontrando na mesma a justificativa para a raridade da verdadeira infeccao humana, separando-a da pseudo-infeccao. Relatam o caso de um paciente cujas manifestacoes clinicas eram febre elevada, anorexia, emagrecimento, mialgias e artralgias, gigantesca hepatomegalia dolorosa discreta esplenomegalia, leucocitose com intensa eosinofilia (superior a 60%), hemossedimentacao muito acelerada, discreta elevacao das transaminases e fosfatase alcalina. O diagnostico foi conseguido merce de biopsia cirurgica do figado. Dada a ausencia de indicacoes terapeuticas, os A.A. formularam um esquema a base de prednisona, di-isofenol e tartarato de pirantel que resultou totalmente eficaz. Este caso constitui-se no unico registrado na literatura nacional com diagnostico em vida. Outro houve, mas como achado necroscopico