Lesões da substância branca por ressonância magnética: uma avaliação entre as ponderações DWI e T2 FLAIR

RESUMO: Objetivos – Determinar a sensibilidade e especificidade das ponderações Difusão (DWI) e T2 Fluid-Attenuated Inversion Recovery (FLAIR) na avaliação de lesões da substância branca (SB) e verificar em que medida se complementam, por forma a criar um conjunto de boas práticas na RM cranioencefálica de rotina. Metodologia – Recorrendo-se a uma metodologia quantitativa, efetuou-se uma análise retrospetiva da qual foram selecionados 30 pacientes, 10 sem patologia e 20 com patologia (2 com EM, 7 com Leucoencefalopatia, 6 com doença microangiopática e 5 com patologia da substância branca indefinida). Obteve-se uma amostra de 60 imagens, nomeadamente: 30 imagens ponderadas em DWI e 30 em T2 FLAIR. Recorrendo ao programa Viewdex®, três observadores avaliaram um conjunto de imagens segundo sete critérios: visibilidade, deteção, homogeneidade, localização, margens e dimensões da lesão e capacidade de diagnóstico. Com os resultados obtidos recorreu-se ao cálculo de sensibilidade e especificidade pelas Curvas ROC, bem como à análise estatística, nomeadamente, Teste-T, Índice de Concordância Kappa e coeficiente de correlação de Pearson entre as variáveis em estudo. Resultados – Os resultados de sensibilidade e de especificidade obtidos para a ponderação T2 FLAIR foram superiores (0,915 e 0,038, respetivamente) aos da ponderação DWI (0,08 e 0,100, respetivamente). Não se verificaram variâncias populacionais significativas. Obteve-se uma elevada correlação linear entre as variáveis com um valor r situado entre 0,8 e 0,99. Verificou-se também uma variabilidade considerável entre os observadores. Conclusões – Dados os baixos valores de sensibilidade e especificidade obtidos para a DWI, sugere-se que esta deva ser incluída no protocolo de rotina de crânio como auxiliar no diagnóstico diferencial com outras patologias.

Efeito fisiológico da cafeína em estudos neurológicos com base na ponderação em susceptibilidade ferromagnética (SWI)

Introdução – O presente estudo avaliou o efeito da cafeína no valor da razão contraste ruído (CNR) em imagens SWI. Objetivos – Avaliar o efeito da cafeína qualitativamente e quantificado pelo cálculo do valor CNR em imagens de magnitude e MIP para as estruturas: veia cerebral interna, seio sagital superior, tórcula e artéria cerebral média. Metodologia – A população do estudo incluiu 24 voluntários saudáveis que estiveram pelo menos 24h privados da ingestão de cafeína. Adquiriram-se imagens SWI antes e após a ingestão de 100ml de café. Os voluntários foram subdivididos em quatro grupos de seis indivíduos/grupo e avaliados separadamente após decorrido um intervalo de tempo diferente para cada grupo (15, 25, 30 ou 45min pós-cafeína). Utilizou-se um scanner Siemens Avanto 1,5 T com bobine standard de crânio e os parâmetros: T2* GRE 3D de alta resolução no plano axial, TR=49; TE=40; FA=15; FOV=187x230; matriz=221x320. O processamento de imagem foi efetuado no software OsiriX® e a análise estatística no GraphPadPrism®. Resultados e Discussão – As alterações de sinal e diferenças de contraste predominaram nas estruturas venosas e não foram significantes na substância branca, LCR e artéria cerebral média. Os valores CNR pré-cafeína diferiram significativamente do pós-cafeína nas imagens de magnitude e MIP na veia cerebral interna e nas imagens de magnitude do seio sagital superior e da tórcula (p<0,0001). Não se verificaram diferenças significativas entre os grupos avaliados nos diferentes tempos pós-cafeína. Conclusões – Especulamos que a cafeína possa vir a ser usada como agente de contraste nas imagens SWI barato, eficaz e de fácil administração.

Estudo da leucoaraiose por transferência de magnetização e difusão em 36 doentes com status lacunar

Estuda-se por ressonância magnética (RM) da substância branca 36 idosos do Vale do Tejo com doença microvascular/leucoaraiose isquémica. A aquisição é em transferência da magnetização e difusão. Propósito de comparar duas populações com status lacunar basal, uma delas com confluência de lacunas basais (17 casos) e outra sem confluência (19 casos). Na RM desta “leucopatia vascular”, com desigual densidade lacunar, as alterações são difusas e não apenas testemunhadas pelo hiper-T2. A heterogeneidade semiológica das lesões subcorticais implica que também se estude a substância branca aparentemente normal. O coeficiente aparente de difusão será a chave do prognóstico do status lacunar avançado, quanto ao potencial risco cognitivo.

Seasonal variation of total particulate matter and children respiratory diseases at Lisbon primary schools using passive methods

In this work, 14 primary schools of Lisbon city, Portugal, followed a questionnaire of the ISAAC - International Study of Asthma and Allergies in Childhood Program, in 2009/2010. The questionnaire contained questions to identify children with respiratory diseases (wheeze, asthma and rhinitis). Total particulate matter (TPM) was passively collected inside two classrooms of each of 14 primary schools. Two types of filter matrices were used to collect TPM: Millipore (IsoporeTM) polycarbonate and quartz. Three campaigns were selected for the measurement of TPM: Spring, Autumn and Winter. The highest difference between the two types of filters is that the mass of collected particles was higher in quartz filters than in polycarbonate filters, even if their correlation is excellent. The highest TPM depositions occurred between October 2009 and March 2010, when related with rhinitis proportion. Rhinitis was found to be related to TPM when the data were grouped seasonally and averaged for all the schools. For the data of 2006/2007, the seasonal variation was found to be related to outdoor particle deposition (below 10 μm).

Strange matter in the universe

The strange quark matter hypothesis is one of the most exciting speculations of the XX Century Physics. If this hypothesis is correct, the ground state of the matter would be the strange matter, which could form the core of compact objects like neutron stars or even more exotic objects like quarks stars. Due to the high-density and low-temperature regime in these stars, the interaction between quarks through gluon exchange could favor the appearance of a color superconducting state, significantl modifying the equation of state of the system. In this paper we present a general overview of this Subject, taking also into account the effect of strong magnetic field in the quark stars.

Compact Stars and Magnetized CFL Matter

The stability of the color flavor locked phase in the presence of a strong magnetic field is investigated within the phenomenological MIT bag model. It is found that the minimum value of the energy per baryon in a color flavor locked state at vanishing pressure is lower than the corresponding one for unpaired magnetized strange quark matter and, as the magnetic field increases, the energy per baryon decreases. This implies that magnetized color flavor locked matter is more stable and could become the ground state inside neutron stars. The anisotropy of the pressures is discussed. The mass-radius relation for such stars is also studied.

Neutrinos and the Matter-Antimatters Asymmetry in the Universe

The discovery of neutrino oscillations provides a solid evidence for nonzero neutrino masses and leptonic mixing. The fact that neutrino masses are so tiny constitutes a puzzling problem in particle physics. From the theoretical viewpoint, the smallness of neutrino masses can be elegantly explained through the seesaw mechanism. Another challenging issue for particle physics and cosmology is the explanation of the matter-antimatter asymmetry observed in Nature. Among the viable mechanisms, leptogenesis is a simple and well-motivated framework. In this paper we briefly review these aspects, making emphasis on the possibility of linking neutrino physics to the cosmological bary asymmetry originated from leptogenesis.

Occupational exposure to particulate matter and respiratory symptoms in Portuguese swine barn workers

Certain environmental conditions in animal and plant production have been associated with increased frequency in respiratory illnesses, including asthma, chronic bronchitis, and hypersensitivity pneumonitis, in farmers occupationally exposed in swine production. The aim of this study was to characterize particulate matter (PM) contamination in seven Portuguese swine farms and determine the existence of clinical symptoms associated with asthma and other allergy diseases, utilizing the European Community Respiratory Health Survey questionnaire. Environmental assessments were performed with portable direct-reading equipment, and PM contamination including five different sizes (PM0.5, PM1.0, PM2.5, PM5.0, PM10) was determined. The distribution of particle size showed the same trend in all swine farms, with high concentrations of particles with PM5 and PM10. Results from the questionnaire indicated a trend such that subjects with diagnosis of asthma were exposed to higher concentrations of PM with larger size (PM2.5, PM5, and PM10) while subjects with sneezing, runny nose, or stuffy nose without a cold or flu were exposed to higher concentrations of PM with smaller size (PM0.5 and PM1). Data indicate that inhalation of PM in swine farm workers is associated with increased frequency of respiratory illnesses.

Occupational exposure to particulate matter and fungi in a composting plant: case study in Portugal

The handling of waste can be responsible for occupational exposure to particles and fungi. The aim of this study was to characterize exposure to particles and fungi in a composting plant. Measurements of particulate matter were performed using portable direct-reading equipment. Air samples of 50L were collected through an impaction method with a flow rate of 140L/min onto malt extract agar supplemented with chloramphenicol (0.05%). Surfaces samples were also collected. All the samples were incubated at 27ºC for 5 to 7 days. Particulate matter data showed higher contamination for PM, and PM10 sizes. Aspergillus genus presents the highest air prevalence (90.6%). Aspergillus niger (32.6%), A. fumigatus (26.5%) and A. flavus (16.3%) were the most prevalent fungi in air sampling, and Mucor sp. (39.2%), Aspergillus niger (30.9%) and A. fumigatus (28.7%) were the most found in surfaces. the results obtained claim the attention to the need of further research.

Exposure to volatile organic compounds, particulate matter and fungi in a composting plant

Composting is an important process of solid waste management and it can be used for treatment of a variety of different wastes (green waste, household waste, sewage sludge and more). This process aims to: 1. Reduce the volumes of waste and; 2. Create a valuable product which can be recycled as a soil amendment in agriculture and gardening. A natural self-heating process involving the biological degradation of organic matter under aerobic conditions. The handling of waste and compost is responsible for the release of airborne microorganisms and their compounds in the air. Possible contaminants: a) Dust; b) Mesophilic and thermophilic microorganisms; c) Volatile organic compounds; d) Endotoxins and mycotoxins…. Aim: assess exposure/contamination to: a) Volatile organic compounds (VOCs); b) Particulate matter (PM); c) Fungi. In a composting plant located in Lisbon. An additional goal was to identify the workplace with higher level of contamination. In a totally indoor composting plant. The composting operations consisted: 1º Waste already sorted is unloaded in a reception area; 2º Pretreatment - remove undesirable materials from the process (glass, rocks, plastics, metals…); 3º Anaerobic digestion; 4º Dehydration; 5º Open composting with forced aeration. All the process takes thirteen weeks.

Occupational exposure to particulate matter in 2 Portuguese waste-sorting units

Objectives - This study intended to characterize work environment contamination by particles in 2 waste-sorting plants. Material and Methods - Particles were measured by portable direct-reading equipment. Besides mass concentration in different sizes, data related with the number of particles concentration were also obtained. Results - Both sorting units showed the same distribution concerning the 2 exposure metrics: particulate matter 5 (PM5) and particulate matter 10 (PM10) reached the highest levels and 0.3 μm was the fraction with a higher number of particles. Unit B showed higher (p < 0.05) levels for both exposure metrics. For instance, in unit B the PM10 size is 9-fold higher than in unit A. In unit A, particulate matter values obtained in pre-sorting and in the sequential sorting cabinet were higher without ventilation working. Conclusions - Workers from both waste-sorting plants are exposed to particles. Particle counting provided additional information that is of extreme value for analyzing the health effects of particles since higher values of particles concentration were obtained in the smallest fraction.

Particulate matter distribution in selected Portuguese archives: a preliminary study

Particulate matter (PM) can have a significant impact on human health and on artifacts stored and kept inside museums and archives. To the author's knowledge, its immediate and/or longterm concentrations and distribution on Portuguese archives has never been determined. Four Portuguese archives (with and without HVAC/air filtration systems) were selected and the immediate concentration of airborne particulate matter was measured by active sampling. Indoor-outdoor ratios were also determined. International and national guidelines were used to ascertain the environment’s quality, both for the readers and staff and for the documents preserved in these institutions. Inside, PM2.5 ranged between 0.37μg/m3 and 27.61μg/m3, while PM10 ranged between 4.43μg/m3 and 285.52μg/m3. The lowest values were determined in storage rooms and the highest in reading rooms. In terms of human health, Portuguese guidelines for immediate PM10 concentration were not met in several locations. For conservation purposes, storage rooms were classified according to an original air quality grid. Air filtration systems proved valuable in maintaining a safe environment for our written heritage and the staff and readers that deal with it and care for it every day. This study constitutes the first snapshot of the particulate matter concentrations and distribution in Portuguese Archives.