A reconstrução tomográfica em SPECT com utilização dos novos métodos iterativos “WBR”: comparação com métodos analíticos

Os métodos utilizados pela Medicina moderna no âmbito da Imagem Molecular e na sua capacidade de diagnosticar a partir da “Função do Orgão” em vez da “Morfologia do Orgão”, vieram trazer á componente fundamental desta modalidade da Imagiologia Médica – A Medicina Nuclear – uma importância acrescida, que se tem traduzido num aumento significativo no recurso á sua utilização nas diferentes formas das suas aplicações clínicas. Para além dos aspectos meramente clínicos, que só por si seriam suficientes para ocupar várias dissertações como a presente; a própria natureza desta técnica de imagem, com a sua inerente baixa resolução e tempos longos de aquisição, vieram trazer preocupações acrescidas quanto ás questões relacionadas com a produtividade (nº de estudos a realizar por unidade de tempo); com a qualidade (aumento da resolução da imagem obtida) e, com os níveis de actividade radioactiva injectada nos pacientes (dose de radiação efectiva sobre as populações). Conhecidas que são então as limitações tecnológicas associadas ao desenho dos equipamentos destinados á aquisição de dados em Medicina Nuclear, que apesar dos avanços introduzidos, mantêm mais ou menos inalteráveis os conceitos base de funcionamento de uma Câmara Gama, imaginou-se a alteração significativa dos parâmetros de aquisição (tempo, resolução, actividade), actuando não ao nível das condições técnico-mecânicas dessa aquisição, mas essencialmente ao nível do pós-processamento dos dados adquiridos segundo os métodos tradicionais e que ainda constituem o estado da arte desta modalidade. Este trabalho tem então como objectivo explicar por um lado, com algum pormenor, as bases tecnológicas que desde sempre têm suportado o funcionamento dos sistemas destinados á realização de exames de Medicina Nuclear, mas sobretudo, apresentar as diferenças com os inovadores métodos, que aplicando essencialmente conhecimento (software), permitiram responder ás questões acima levantadas.

Longshore Transport Estimation on Ofir Beach in Northwest Portugal: Sand-Tracer Experiment

This work aims to shed some light on longshore sediment transport (LST) in the highly energetic northwest coast of Portugal. Data achieved through a sand-tracer experiment are compared with data obtained from the original and the new re-evaluated longshore sediment transport formulas (USACE Waterways Experiment Station’s Coastal Engineering and Research Center, Kamphuis, and Bayram bulk formulas) to assess their performance. The field experiment with dyed sand was held at Ofir Beach during one tidal cycle under medium wave-energy conditions. Local hydrodynamic conditions and beach topography were recorded. The tracer was driven southward in response to the local swell and wind- and wave-induced currents (Hsb=0.75mHsb=0.75m, Tp=11.5sTp=11.5s, θb=8−12°θb=8−12°). The LST was estimated by using a linear sediment transport flux approach. The obtained value (2.3×10−3m3⋅s−12.3×10−3m3⋅s−1) approached the estimation provided by the original Bayram formula (2.5×10−3m3⋅s−12.5×10−3m3⋅s−1). The other formulas overestimated the transport, but the estimations resulting from the new re-evaluated formulas also yield approximate results. Therefore, the results of this work indicated that the Bayram formula may give satisfactory results for predicting the longshore sediment transport on Ofir Beach.

Fishing the key biological components of the bacterium Geobacter metallireducens for optimal biotechnological applications

Os resultados apresentados no capítulo 2 foram incluídos no artigo Dantas JM, Campelo LM, Duke NEC, Salgueiro CA, Pokkuluri PR (2015) "The structure of PccH from Geobacter sulfurreducens – a novel low reduction potential monoheme cytochrome essential for accepting electrons from an electrode", FEBS Journal, 282, 2215-2231.

Pelvic lymphoscintigraphy: contribution to the preoperative staging of rectal cancer

PURPOSE: Preservation of the anal sphincter in surgery for cancer of the distal rectum in an attempt to avoid colostomy has been a main concern of colorectal surgeons. Various proposed procedures contradict oncological principles, especially with respect to pelvic lymphadenectomy. Therefore, prior knowledge of pelvic lymph node involvement is an important factor in choosing the operative technique, i.e., radical or conservative resection. Introduction of ultrasound, computerized tomography, and magnetic resonance have made preoperative study of the area possible. Nevertheless, these resources offer information of an anatomical nature only. Lymphoscintigraphy enables the morphological and functional evaluation of the pelvic area and contributes toward complementing the data obtained with the other imaging techniques. The objective of this prospective study is twofold: to standardize the lymphoscintigraphy technique and to use it to differentiate patients with rectal cancer from those with other coloproctologic diseases. CASUISTIC AND METHODS: Sixty patients with various coloproctologic diseases were studied prospectively. Ages ranged from 21 to 96 years (average, 51 and median, 55 years). Twenty-six patients were male and 34 were female. Thirty patients had carcinoma of the distal rectum as diagnosed by proctologic and anatomic-pathologic examinations, 20 patients had hemorrhoids, 5 had chagasic megacolon, 2 had diverticular disease, 2 had neoplasm of the right colon, and 1 had ulcerative colitis as diagnosed by proctologic exam and/or enema. The lymphoscintigraphy method consisted of injecting 0.25 mL of a dextran solution marked with radioactive technetium-99m into the right and left sides of the perianal region and obtaining images with a gamma camera. The results were analyzed statistically with a confidence level of 95% (P < .05) using the following statistical techniques: arithmetic and medium average, Fisher exact test, chi-square test corrected for continuity according to Yates, and distribution tables for the number of patients. RESULTS: In rectal cancer, the tracer progresses unilaterally or is absent; in other patients, the progress of the tracer is bilateral and symmetrical, although its progress may be slow. Statistical tests showed with high significance that the agreement index between the clinical diagnosis and the result of the lymphoscintigraphic exam was 93%. CONCLUSIONS: Lymphoscintigraphy is a standardized, painless, and harmless test that can be performed in all cases; it differentiates patients with rectal cancer from those with other coloproctological diseases.

Use of nonradioactive labeling to detect large gene rearrangements in 21-hydroxylase deficiency

PURPOSE: To establish the Southern blotting technique using hybridization with a nonradioactive probe to detect large rearrangements of CYP21A2 in a Brazilian cohort with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH-21OH). METHOD: We studied 42 patients, 2 of them related, comprising 80 non-related alleles. DNA samples were obtained from peripheral blood, digested by restriction enzyme Taq I, submitted to Southern blotting and hybridized with biotin-labeled probes. RESULTS: This method was shown to be reliable with results similar to the radioactive-labeling method. We found CYP21A2 deletion (2.5%), large gene conversion (8.8%), CYP21AP deletion (3.8%), and CYP21A1P duplication (6.3%). These frequencies were similar to those found in our previous study in which a large number of cases were studied. Good hybridization patterns were achieved with a smaller amount of DNA (5 mug), and fragment signs were observed after 5 minutes to 1 hour of exposure. CONCLUSIONS: We established a non-radioactive (biotin) Southern blot/hybridization methodology for CYP21A2 large rearrangements with good results. Despite being more arduous, this technique is faster, requires a smaller amount of DNA, and most importantly, avoids problems with the use of radioactivity.

Metodologias Participativas: Os media e a educação

Este livro reúne experiências e reflexões de académicos e não académicos sobre as potencialidades dos media para envolver e capacitar comunidades. Ao longo destas páginas, encontram-se textos que documentam propostas educativas e cívicas em torno dos media ou refletem sobre as capacidades dos media para trabalhar no seio das comunidades, incluindo as esferas da infância/juventude e/ou dos adultos e seniores. As metodologias participativas têm uma grande tradição em países da América Latina, de África e da Ásia e estão agora a ser mais usadas na Europa, particularmente, em Portugal. Esta inspiração reflete-se nas diferentes geografias que podem ser encontradas nesta obra, desde Reino Unido, Alemanha ou Brasil, até ao Quénia. Este livro está dividido em quatro partes. Uma primeira foca-se no projeto que deu mote ao livro, o RadioActive Europe, dando conta das suas práticas em Portugal e noutros países europeus. De seguida, juntamos experiências comunitárias e participativas nacionais e internacionais e, por fim, expomos vários caminhos de reflexão em torno da literacia e dos media.

“Learning through Radio, Learning for Life!”: Notas sobre o desenvolvimento de uma rádio participativa online

(Excerto) Olhando para o percurso do RadioActive, há uma ideia que parece ser transversal a todo o projeto. Referimo-nos a um princípio que chamaríamos de “identificação” e que foi determinante – é determinante – nos processos de investigação participativa. Falamos da identificação dos investigadores com os princípios da investigação-ação, da identificação das intervenções com as particularidades de cada contexto. Da imprescindível e progressiva identificação dos participantes com o projeto. Na verdade, sem esta multifacetada identificação é impossível pensar em resultados sustentáveis e persistentes. Investigadores e demais participantes têm de sentir que o projeto é “seu”, que os objetivos são “seus”, embora o façam necessariamente a velocidades diferentes. A aprendizagem, neste âmbito, expande-se sempre de dentro para fora, emerge dos interesses do sujeito e não de uma estrutura pré-concebida e imposta pelos que chegam (Ravenscroft et al., 2011), neste caso, os investigadores. Uma das diferenças das pesquisas participativas em relação às tradicionais é, precisamente, a atuação coletiva e não solitária do investigador. Os pesquisadores fazem parte de um processo participatório em que estão envolvidos numa estrutura (Cammarota & Fine, 2008: 5). Paulo Freire é o autor primordial em todos os projetos e países onde a RA101 foi aplicada. As suas concepções em torno da investigação-ação participativa tentam apontar sempre para uma ação e também para uma reflexão sobre os processos.

Aspectos bioquímicos y celulares de la reproducción de los vectores de la enfermedad de Chagas: regulación e importancia fisiológica. Biochemical and cellular aspects of the reproduction of Chagas’ disease vectors: regulation and physiologycal impact

En la hipótesis de trabajo del presente proyecto se considera la importancia del metabolismo de lípidos y proteínas en los insectos hematófagos, en particular en los vectores de la enfermedad de Chagas, para afrontar exitosamente la demanda energética de la reproducción. Las hembras de estas especies pueden ingerir una comida de sangre abundante en lípidos y proteínas, los que son modificados en el intestino para su utilización y posterior almacenamiento en estructuras organizadas en el tejido ovárico, sustentando así el rápido crecimiento de los ovocitos. Estos aspectos resultan críticos para el ciclo de vida del insecto y para el mantenimiento de la cadena epidemiológica de la enfermedad. En estas especies, recientemente hemos caracterizado a nivel bioquímico y celular la interacción entre lipoproteínas y tejidos [Fruttero y col., Insect Biochem. Mol. Biol. 39: 322-331 (2009); Fruttero y col. Biocel 33 (3): 260 (2009)] y las fases del ciclo reproductivo [Aguirre y col., J. Insect Physiol. 54: 393-402 (2008)]. No obstante, los factores que participan en su regulación son aún escasamente conocidos. En este contexto, el estudio propone emplear dos especies de triatominos con el objeto de: (1) caracterizar los factores involucrados en la formación y regulación de reservas nutricionales en los ovocitos; (2) analizar los eventos que participan en la regresión del tejido ovárico: atresia folicular y mecanismos de muerte celular. (3) evaluar el impacto de productos naturales (ureasas vegetales y péptidos derivados) en el desarrollo del tejido ovárico. Para la ejecución de los objetivos se llevarán a cabo ensayos in vivo e in vitro con trazadores fluorescentes, fraccionamiento subcelular, estudios de expresión de proteínas (mRNA y proteína), estudios histo-morfológicos, ultraestructurales e inmunocitoquímicos, microscopía láser confocalizada, ensayos de actividad enzimática, ELISA, western-blot, electroforesis bidimensional, espectrometria de masas en tándem, etc. También se evaluarán los mecanismos de muerte celular (apoptosis/autofagia) mediante microscopía electrónica, detección de apoptosis in situ (TUNEL), inmunofluorescencia, etc. Los resultados obtenidos permitirán un mejor conocimiento sobre la fisiología y bioquímica de estos vectores, los que resultan indispensables en el diseño de nuevas estrategias para su control. Debido a la carencia de un tratamiento específico para la enfermedad y a la falta de métodos preventivos (vacuna), el control del vector es una de las vías más importantes para reducir la incidencia de la enfermedad. Actualmente, la situación socio-económica que sufren amplios núcleos de nuestra población propicia condiciones de vida que facilitan la reproducción de los vectores y la transmisión vectorial del parásito. El estudio permitirá además explorar aspectos bioquímicos y celulares básicos, generando conocimientos que podrían ser extensivos a otros insectos de importancia económica en la ganadería y/o agricultura. The aim of this project is to analyze the biochemical and cellular events involved in the lipid and protein metabolism in Chagas' disease vectors, and to evaluate their impact on the physiology of reproduction, particularly in the formation of nutritional resources in developing oocytes. At present, little is known about these critical aspects for the life cycle of the insect and for the epidemiology of the disease. The experimental approaches, which will be carried out using two species of triatomines, were designed: (1) to characterize factors involved in the formation and regulation of nutritional resources in developing oocytes; (2) to analyze the biochemical and cellular events that play a role during the regression of ovarian tissue, including the processes of oocyte resorption and programmed cell death. (3) to evaluate the impact of natural products (ureases from jackbean and related peptides) in the development of ovarian tissue. Methods and techniques involved in the project are: in vivo and in vitro assays with fluorescent tracers, ELISA, chemical assays, enzyme activities, western-blot; protein expression (mRNA), histological techniques, immunohistochemical and ultrastructural studies. Cell death will be analyzed by detection of apoptosis in situ (TUNEL), immunofluorescence (for autophagy), among others. The results obtained from the study will offer the opportunity to explore important aspects in the biology and physiology of Chagas' disease vectors that could be of potential utility in designing alternative strategies for the control of the insect.

The Benefits of Prone SPECT Myocardial Perfusion Imaging in Reducing Both Artifact Defects and Patient Radiation Exposure

AbstractBackground:Prone imaging has been demonstrated to minimize diaphragmatic and breast tissue attenuation.Objectives:To determine the role of prone imaging on the reduction of unnecessary rest perfusion studies and coronary angiographies performed, thus decreasing investigation time and radiation exposure.Methods:We examined 139 patients, 120 with an inferior wall and 19 with an anterior wall perfusion defect that might represented attenuation artifact. Post-stress images were acquired in both the supine and prone position. Coronary angiography was used as the “gold standard” for evaluating coronary artery patency. The study was terminated and rest imaging was obviated in the presence of complete improvement of the defect in the prone position. Quantitative interpretation was performed. Results were compared with clinical data and coronary angiographic findings.Results:Prone acquisition correctly revealed defect improvement in 89 patients (89/120) with inferior wall and 12 patients (12/19) with anterior wall attenuation artifact. Quantitative analysis demonstrated statistically significant difference in the mean summed stress scores (SSS) of supine and mean SSS of prone studies in patients with disappearing inferior wall defect in the prone position and patent right coronary artery (true negative results). The mean difference between SSS in supine and in prone position was higher with disappearing than with remaining defects.Conclusion:Technetium-99m (Tc-99m) tetrofosmin myocardial perfusion imaging with the patient in the prone position overcomes soft tissue attenuation; moreover it provides an inexpensive, accurate approach to limit the number of unnecessary rest perfusion studies and coronary angiographies performed.

PET Molecular Imaging of Hypoxia in Ischemic Stroke: An Update.

Hypoxia, a condition of insufficient oxygen availability to support metabolism, occurs when the vascular supply is interrupted, as in stroke. The identification of the hypoxic and viable tissue in stroke as compared with irreversible lesions (necrosis) has relevant implications for the treatment of ischemic stroke. Traditionally, imaging by positron emission tomography (PET), using 15O-based radiotracers, allowed the measurement of perfusion and oxygen extraction in stroke, providing important insights in its pathophysiology. However, these multitracer evaluations are of limited applicability in clinical settings. More recently, specific tracers have been developed, which accumulate with an inverse relationship to oxygen concentration and thus allow visualizing the hypoxic tissue non invasively. These belong to two main groups: nitroimidazoles, and among these the 18F-Fluoroimidazole (18F-FMISO) is the most widely used, and the copper-based tracers, represented mainly by Cu-ATSM. While these tracers have been at first developed and tested in order to image hypoxia in tumors, they have also shown promising results in stroke models and preliminary clinical studies in patients with cardiovascular disorders, allowing the detection of hypoxic tissue and the prediction of the extent of subsequent ischemia and clinical outcome. These tracers have therefore the potential to select an appropriate subgroup of patients who could benefit from a hypoxia-directed treatment and provide prognosis relevant imaging. The molecular imaging of hypoxia made important progress over the last decade and has a potential for integration into the diagnostic and therapeutic workup of patients with ischemic stroke.

The roles of haemolymphatic lipoproteins in the oogenesis of Rhodnius prolixus

The fates of purified 32P-vitellin and 32P-lipophorin were followed in vitellogenic females of Rhodnius prolixus. While the radioactivity from 32P-vitellin 6 hours after injection was found almost exclusively in the ovary, the radioactivity from injected 32P-lipophorin was found distributed among several organs. In the ovary, the radioactivity from 32P-vitellin was associated with the contents of the yolk granules. 32P-lipophorin delivered a great amount of radioactive phospholipids to the ovary with no accumulation of its protein moiety, as observed after its iodination with 131I. The delivery of phospholipids was inhibited at 0ºC and by the metabolic inhibitors, sodium azide and sodium fluoride. Comparison of the radioactivity incorporation from 32P-lipophorin with that of 14C-inulin suggests that the 32P-phospholipids from lipophorin are not taken up by fluid phase endocytosis. The data presented here are compatible with the concept of lipophorin as a carrier of lipids in insects and provide evidence that lipophorin transports phospholipids as shown previously for other classes of lipids. The utilization by the oocytes of the phospholipids transported by lipophorin is discussed.

Pollution and pollutant transport in the geosphere - An introduction to the symposium

Environmental research in earth sciences is focused on the geosphere, i.e. (1) waters and sediments of rivers, lakes and oceans, and (2) soils and underlying shallow rock formations,both water-unsaturated and -saturated. The subsurface is studied down to greater depths at sites where waste repositories or tunnels are planned and mining activities exist. In recent years, earth scientists have become more and more involved in pollution problems related to their classical field of interest, e.g. groundwater, ore deposits, or petroleum and non-metal natural deposits (gravel, clay, cement precursors). Major pollutants include chemical substances, radioactive isotopes and microorganisms. Mechanisms which govern the transport of pollutants are of physical, chemical (dissolution, precipitation, adsorption), or microbiological (transformation) nature. Land-use planning must reflect a sustainable development and sound scientific criteria. Today's environmental pollution requires working teams with an interdisciplinary background in earth sciences, hydrology, chemistry, biology, physics as well as engineering. This symposium brought together for the first time in Switzerland earth and soil scientists, physicists and chemists, to present and discuss environmental issues concerning the geosphere.

Seven years of gamma-ray spectrometry interlaboratory comparisons in Switzerland.

Since the 1990s, regular comparisons of gamma-ray spectrometry in Switzerland were organized to improve laboratory abilities to measure the radioactivity in the environment and food stuffs at typical routine levels. The activity concentration of the test samples and the evaluation of the associated uncertainties remained each year the main required test result. Over the years, the comparisons used certified reference solutions as well as environmental samples. The aim of this study is to research the effect of the comparisons on measurement quality. An analysis of the seven last interlaboratory comparisons revealed that the Swiss measurement capability is up to date. In addition, the results showed that the participants now have an improved evaluation of the uncertainties associated with their measurement.