Immunopathologic studies in myocardial biopsies of patients with Chagas' disease and idiopathic cardiomyopathy

Right ventricular endomyocardial biopsies were studied in 30 patients, 15 with myocardiopathy from chronic Chagas'disease and 15 with idiopathic congestive myocardiopathy; five other myocardial samples were taken at necropsies of patients with chronic Chagas' disease. The authors tried to establish by means of direct immunofluorescence techniques whether there were immunoglobulins G, A and M, fibrinogen and C3 complement deposition in the myocardium; only one of these 30 patients exhibited a positive reaction to IgG, it was a patient with idiopathic congestive myocardiopathy. All fragments from patients with Chagas' disease showed no response to any of the fluorescent conjugates. These findings do not support the idea that anti-myoeardial antibodies have pathogenic importance in the evolution of dilated or chagasic myocardiopathies.

Structure to function studies in UDP-glucose dehydrogenases and nitroreductases

The thesis is divided into two parts corresponding to structural studies on two different proteins. The first part concerns the study of two UDP-glucose dehydrogenases (UGDs) from Sphingomonas elodea ATCC 31461 and Burkholderia cepacia IST 408, both involved in exopolysaccharide production. Their relevance arises because some of these bacterial exopolysaccharides are valuable as established biotechnological products, the former case, whilst others are highly problematic, when used by pathogens in biofilm formation over biological surfaces, as the latter case, namely in the human lungs. The goal of these studies is to increase our knowledge regarding UGDs structural properties, which can potentiate either the design of activity enhancers to respond to the increased demand of useful biofilms, or the design of inhibitors of biofilm production, in order to fight invading pathogens present in several infections. The thesis reports the production and crystallisation of both proteins, the determination of initial phases by single-wavelength anomalous dispersion (SAD) in S. elodea crystals using a seleno-methionine isoform, and phasing of B. cepacia crystals by molecular replacement (MR) using the S. elodea model, as well as the refinement, structural analysis and comparison between the several UGDs structures available during this work.(...)

Oogram studies in mice infected with Schistosoma mansoni and treated with dexamethasone

Mice infected with about 90 cercariae of Schistosoma mansoni (LE strain) were treated during five consecutive days with dexamethasone (50 mg/Kg, subcutaneously), starting on the 42th day of infection. Groups of five mice were then daily sacrificed from the first day after onset of treatment until the first day after. The perfusion of the portal system was performed and a piece of the intestine was processed for qualitative and quantitative oograms. This treatment carries to larger numbers of eggs in the tissues of treated mice, when compared with untreated groups. No changes were observed in the kinetics of oviposition, as all stages of viable eggs were observed in the tissues of treated and control mice. These data reinforce the hypothesis of a partial blockade of the egg excretion in immunossupressed mice.

(Un)suitability of the use of pH buffers in biological, biochemical and environmental studies and their interaction with metal ions – a review

The use of buffers to maintain the pH within a desired range is a very common practice in chemical, biochemical and biological studies. Among them, zwitterionic N-substituted aminosulfonic acids, usually known as Good’s buffers, although widely used, can complex metals and interact with biological systems. The present work reviews, discusses and updates the metal complexation characteristics of thirty one commercially available buffers. In addition, their impact on biological systems is also presented. The influences of these buffers on the results obtained in biological, biochemical and environmental studies, with special focus on their interaction with metal ions, are highlighted and critically reviewed. Using chemical speciation simulations, based on the current knowledge of the metal–buffer stability constants, a proposal of the most adequate buffer to employ for a given metal ion is presented.

The hamster (mesocricetus auratus) as experimental model in chagas' disease: parasitological and histopathological studies in acute and chronic phases of Trypanosoma cruzi infection

This research characterizes the acute and chronic phases of Chagas ' disease in hamster through parasitological and histopathological studies. The acute phase was achieved with 44 young hamsters injected intraperitoneally with 100.000 blood trypomastigotes of Benedito and Y strains of T. cruzi. The chronic phase was induced in 46 hamsters injected intraperitoneally with 35.000 trypomastigotes ofVicentina, Benedito and Y strains. Animals were sacrificed at regular intervals of 24 hours of acute phase and from the 3rd to the 10th month of infection ofchronic phase. In the acute phase, parasites were easily recoveredfrom all animals and there was an inflammatory reaction characterized by mononuclear and polymorphous leukocyte infiltration of variable degree in the majority of tissues and organs, specially in the connective loose and fatty tissues, smooth muscle myocardium and skeletal muscle. In the chronic phase the lesions occurred in the same tissues and organs, but the inflammatory response was less severe and characterized by mononuclear infiltration mainly with focal or zonalfibrosis in the myocardiun. In 50% of infected animals parasites were found inmyocardiun and recoveredfrom pericardic, peritoneal and ascitic fluids in some animals. Signs of heart failure, sudden death and enlargement of bowel were observed regularly. We concluded that the hamster is an useful model for Chagas' disease studies.

Genome-wide association studies reveal genomic windows and candidate genes related to fat deposition in chickens.

2016

Crystallographic studies of proteins involved in the mRNA localization mechanisms in Drosophila melanogaster and amidation of the peptidoglycan residues in Staphylococcus aureus

Part of the work described in this chapter, was the subject of the following publication: D. Vieira, T. a. Figueiredo, A. Verma, R. G. Sobral, A. M. Ludovice, H. de Lencastre, and J. Trincao, “Purification, crystallization and preliminary X-ray diffraction analysis of GatD, a glutamine amidotransferase-like protein from Staphylococcus aureus peptidoglycan,” Acta Crystallogr. Sect. F Struct. Biol. Commun., vol. 70, no. 5, pp. 1–4, Apr. 2014.

The role of objects in creative collaborations

Objects matter when professionals collaborate to create new products. Chapter 1 explains the intention of this work, to apply theories on objects in the empirical context of fashion design. Chapter 2 addresses the question of how creative professionals learn about and use strategy tools to turn their artistic fame into a commercial success. For Chapter 3 I collected ethnographic data on the development of a seasonal collection from the idea to the presentation at Fashion Week. The result is a deep insight into the collaborative processes and material objects used when a stable team of designers works with several outside experts. Chapter 4 applies the knowledge of the role of objects in fashion design gained during the ethnography in the context of online co-creation and crowd sourced fashion items. The synthesis of the empirical studies allows me to present the conceptual leap in Chapter 5. In the theoretical essay I review the findings on the role of objects in collaborations in relation to practice theory, present the new concept of the comprehensive object and conclude by stating the possibilities for future research.

Changes in body fluid and energy compartments during prolonged hunger strike

Prolonged total food deprivation in non-obese adults is rare, and few studies have documented body composition changes in this setting. In a group of eight hunger strikers who refused alimentation for 43 days, water and energy compartments were estimated, aiming to assess the impact of progressive starvation. Measurements included body mass index (BMI), triceps skinfold (TSF), arm muscle circumference (AMC), and bioimpedance (BIA) determinations of water, fat, lean body mass (LBM), and total resistance. Indirect calorimetry was also performed in one occasion. The age of the group was 43.3±6.2 years (seven males, one female). Only water, intermittent vitamins and electrolytes were ingested, and average weight loss reached 17.9%. On the last two days of the fast (43rd-44th day) rapid intravenous fluid, electrolyte, and vitamin replenishment were provided before proceeding with realimentation. Body fat decreased approximately 60% (BIA and TSF), whereas BMI reduced only 18%. Initial fat was estimated by BIA as 52.2±5.4% of body weight, and even on the 43rd day it was still measured as 19.7±3.8% of weight. TSF findings were much lower and commensurate with other anthropometric results. Water was comparatively low with high total resistance, and these findings rapidly reversed upon the intravenous rapid hydration. At the end of the starvation period, BMI (21.5±2.6 kg/m²) and most anthropometric determinations were still acceptable, suggesting efficient energy and muscle conservation. Conclusions: 1) All compartments diminished during fasting, but body fat was by far the most affected; 2) Total water was low and total body resistance comparatively elevated, but these findings rapidly reversed upon rehydration; 3) Exaggerated fat percentage estimates from BIA tests and simultaneous increase in lean body mass estimates suggested that this method was inappropriate for assessing energy compartments in the studied population; 4) Patients were not morphologically malnourished after 43 days of fasting; however, the prognostic impact of other impairments was not considered in this analysis.

(Un)suitability of the use of pH buffers in biological, biochemical and environmental studies and their interaction with metal ions - a review

The use of buffers to maintain the pH within a desired range is a very common practice in chemical, biochemical and biological studies. Among them, zwitterionic N-substituted aminosulfonic acids, usually known as Good's buffers, although widely used, can complex metals and interact with biological systems. The present work reviews, discusses and updates the metal complexation characteristics of thirty one commercially available buffers. In addition, their impact on biological systems is also presented. The influences of these buffers on the results obtained in biological, biochemical and environmental studies, with special focus on their interaction with metal ions, are highlighted and critically reviewed. Using chemical speciation simulations, based on the current knowledge of the metal-buffer stability constants, a proposal of the most adequate buffer to employ for a given metal ion is presented.

Chemical composition, antioxidant activity and bioaccessibility studies in phenolic extracts of two Hericium wild edible species

Mushrooms are rich sources of bioactive compounds such as phenolic acids. When ingested, these molecules have to be released from the matrix to be transformed/absorbed by the organism, so that they can exert their bioactivity. Several in vitro methodologies have been developed in order to evaluate the bioavailability of bioactive compounds. Herein, two Hericium species were analyzed for their chemical composition and antioxidant activity. Furthermore, an in vitro digestion of the mushrooms and mushroom phenolic extracts was performed, and the digested samples were also submitted to antioxidant activity evaluation in order to evaluate the bioaccessibility of the phenolic acids identified in the samples. Hericium species showed similar chemical profiles (except for tocopherols), varying only in the concentration of the compounds. The phenolic extracts revealed higher antioxidant activity than the in vitro digested samples, meaning that this process decrease the antioxidant properties of the extract/mushroom. Nevertheless, phenolic acids were found in the digested samples, meaning that those molecules are bioaccessible.

Looking for mechanisms regulating lung growth in CDH: rat and human studies

Tese de Doutoramento em Ciências da Saúde

Estudio de la micobiota y sus micotoxinas en ingredientes y raciones de animales domésticos. Estrategias orientadas a la prevención de las micotoxicosis. Studies on mycobiota and incidence of mycotoxins in raw material and feedstuff for domestic animals. Different strategies for mycotoxicosis prevention.

Numerosas investigaciones han desarrollado estrategias para la remoción de micotoxinas en alimentos por diferentes métodos, aunque muchos de ellos no han llegado a ser utilizados debido a los elevados costos o a las dificultades prácticas involucradas en el proceso de detoxificación. Estos argumentos estimulan a los investigadores a desarrollar nuevas estrategias de decontaminación que eviten el uso de agentes químicos y que reduzcan las pérdidas en el valor nutritivo y la palatabilidad de los alimentos decontaminados. Una de las alternativas promisorias es la detoxificación biológica. Las levaduras capaces de adsorber micotoxinas y con habilidades probióticas o prebióticas son promisorias para reducir la exposición humana a las micotoxinas. En el tracto gastrointestinal se encuentra normalmente un gran número de especies de bacterias comensales y patógenas; sin embargo, cuando se incrementa la cantidad de microorganismos patógenos se pueden producir alteraciones de la salud y muerte. La industria argentina de alimentos destinados a animales necesita reducir los niveles de micotoxinas presentes en ingredientes o en insumos terminados. Si bien los resultados obtenidos en el mundo en la temática son preliminares y promisorios, en nuestro país aún no se han desarrollado estrategias biológicas de decontaminación de micotoxinas aplicadas a estos alimentos. Estudios de incidencia de micoflora y detección de micotoxinas en alimentos balanceados para aves, llevados a cabo por nuestro grupo de investigación en la región del sur de Córdoba demostraron la presencia de los principales géneros toxicogénicos (Aspergillus, Penicillium y Fusarium) y sus micotoxinas asociadas (aflatoxinas, zearalenona y fumonisinas). En relación a porcinotecnia, la zona sur de la provincia de Córdoba es considerada una de las tres zonas de mayor densidad porcina en Argentina. Sin embargo, la contaminación de los granos con micotoxinas representa un serio problema debido a que producen rechazo del alimento, disminución de la tasa de crecimiento y reducción inmunológica. Si consideramos la evolución en la producción lechera en los últimos años ha seguido una línea de intensificación que ha conllevado un cambio en la utilización de los alimentos, evolucionando del simple pastoreo a los sistemas de alimentación única, basados en la formulación de alimentos balanceados que constituyen la clave de la alimentación de los animales. Diferentes estudios epidemiológicos usando técnicas moleculares han demostrado que con frecuencia la infección por A. fumigatus ocurre como consecuencia de la adquisición exógena del hongo. La magnitud del problema se manifiesta en la continua búsqueda de medidas de prevención y control de estas micotoxicosis. Debido a este impacto negativo que ejercen las toxinas fúngicas lo cual, afecta los parámetros productivos como ganancia de peso y conversión alimenticia con graves pérdidas a la industria animal tanto en el mercado interno como externo.