Browsing by Issue Date, starting with "2011-04"
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- Photosensitizers for photodynamic therapy: One-pot heterogeneous catalytic transfer reduction of porphyrinsPublication . Fernandes, A.; Rosa da Costa, Ana; Serra, Arménio C.; Pires, CatarinaA number of new porphyrin-based photosensitizers have been developed for Photodynamic Therapy (PDT) in recent years. Chlorins, which are a reduced form of porphyrins, show better potential of application since they have a stronger absorption band on the red region of the visible spectrum and, hence, a deeper penetration into tissues. We found that by using heterogeneous catalytic transfer reduction (CTR), meso-tetraphenylporphyrin (TPP) could be hydrogenated, although in modest yields, to meso-tetraphenylchlorin (TPC) in a single reaction step. Best reaction conditions were attained using formic acid or sodium phosphinate/water as hydrogen donors, tetrahydrofuran (THF) or toluene as solvent and 10% palladium on charcoal as catalyst.
- Advances in research on the prenatal development of skeletal muscle in animalsPublication . Rehfeldt, C.; Te Pas, M. F. W.; Wimmers, K.; Brameld, J. M.; Nissen, P. M.; Berri, C.; Valente, L. M. P.; Power, Deborah; Picard, B.; Stickland, N. C.; Oksbjerg, N.Selective breeding is an effective tool to improve livestock. Several selection experiments have been conducted to study direct selection responses as well as correlated responses in traits of skeletal muscle growth and function. Moreover, comparisons of domestic with wild-type species and of extreme breeds provide information on the genetic background of the skeletal muscle phenotype. Structural muscular components that differed with increasing distance in lean growth or meat quality in mammals were found to be myofibre number, myofibre size, proportions of fibre types as well as the numbers and proportions of secondary and primary fibres. Furthermore, markers of satellite cell proliferation, metabolic enzyme activities, glycogen and fat contents, the expression of myosin heavy chain isoforms, of activated AMPKa and other proteins in skeletal muscle tissue and circulating IGF1 and IGF-binding proteins have been identified to be involved in selection responses observed in pigs, cattle and/or chicken. The use of molecular methods for selective breeding of fish has only recently been adopted in aquaculture and studies of the genetic basis of growth and flesh quality traits are scarce. Some of the molecular markers of muscle structure/metabolism in livestock have also been identified in fish, but so far no studies have linked them with selection response. Genome scans have been applied to identify genomic regions exhibiting quantitative trait loci that control traits of interest, for example, muscle structure and meat quality in pigs and growth rate in chicken. As another approach, polymorphisms in candidate genes reveal the relationship between genetic variation and target traits. Thus, in large-scale studies with pigs’ associations of polymorphisms in the HMGA2, CA3, EPOR, NME1 and TTN genes with traits of carcass and meat quality were detected. Other studies revealed the significance of mutations in the IGF2 and RYR1 genes for carcass lean and muscle fibre traits in pigs. Mutations in the myostatin (MSTN) gene in fish were also examined. Advances in research of the genetic and environmental control of traits related to meat quality and growth have been made by the application of holistic ‘omics’ techniques that studied the whole muscle-specific genome, transcriptome and proteome in relation to muscle and meat traits, the development of new methods for muscle fibre typing and the adaptation of biophysical measures to develop parameters of muscle fibre traits as well as the application of in vitro studies. Finally, future research priorities in the field are defined.
- Blood coagulation dynamics: mathematical modeling and stability resultsPublication . Sequeira, Adelia; Santos, Rafael F.; Bodnar, TomasThe hemostatic system is a highly complex multicomponent biosystem that under normal physiologic conditions maintains the fluidity of blood. Coagulation is initiated in response to endothelial surface vascular injury or certain biochemical stimuli, by the exposure of plasma to Tissue Factor (TF), that activates platelets and the coagulation cascade, inducing clot formation, growth and lysis. In recent years considerable advances have contributed to understand this highly complex process and some mathematical and numerical models have been developed. However, mathematical models that are both rigorous and comprehensive in terms of meaningful experimental data, are not available yet. In this paper a mathematical model of coagulation and fibrinolysis in flowing blood that integrates biochemical, physiologic and rheological factors, is revisited. Three-dimensional numerical simulations are performed in an idealized stenosed blood vessel where clot formation and growth are initialized through appropriate boundary conditions on a prescribed region of the vessel wall. Stability results are obtained for a simplified version of the clot model in quiescent plasma, involving some of the most relevant enzymatic reactions that follow Michaelis-Menten kinetics, and having a continuum of equilibria.
- Detection of speleothem growth bands with an open source geophysical softwarePublication . Veiga-Pires, C.; Moura, Delminda; Luis, JoaquimSpeleothem growth bands are commonly referred as one of the parameters that are used for paleoclimate reconstructions. Accordingly, this work presents a new tool for detecting these bands based on the gray-scale image of the speleothem using the Mirone open source geophysical software.
- A integração dos assentamentos rurais tradicionais nas regiões urbanas: o exemplo do Algarve Central no Sul de PortugalPublication . Costa, Miguel Reimão; Batista, DesidérioO expressivo processo de expansão urbana que, em diferentes geografias, teve origem com a Revolução industrial, comportou frequentemente a integração de assentamentos rurais antes localizados em anéis exteriores à cidade tradicional. Este tema, associado em muitos casos à perda de valor do solo agrícola, tem adquirido maior relevância, nas últimas décadas, no contexto da transformação da cidade contemporânea e da urbanização extensiva e difusa. É nestas circunstâncias que se considera fundamental a inventariação e o estudo da arquitetura vernacular destas áreas, na medida em que estes poderão revelar diferentes edifícios, conjuntos e assentamentos que deveriam ser protegidos, comportando na cidade difusa um papel idêntico ao que os núcleos históricos adquiriram na cidade compacta, especialmente a partir do início da segunda metade do século passado. De facto, à medida que a dicotomia convencional entre cidade e campo perde relevância, as construções vernaculares – tal como o sistema ecológico, a rede de velhos caminhos ou a estrutura predial – têm necessariamente de ser considerados no âmbito do ordenamento metropolitano, tanto a nível da caracterização como da proposta. Deste modo, é fundamental retomar a contraposição entre padrões de dispersão e padrões de aglomeração, na medida em que cada qual levanta diferentes questões a nível da atual transformação do uso do solo. Para compreender alguns dos tópicos inerentes a este processo, consideraremos aqui a região central do Baixo Algarve que constitui, a este propósito, um bom caso de estudo. A investigação em torno aos assentamentos rurais tradicionais adquire especial relevância nesta área, uma vez que os diferentes instrumentos de ordenamento do território restringem, em grande medida, o processo de edificação fora dos perímetros urbanos à reabilitação ou renovação desses conjuntos edificados preexistentes.
- Motivação profissional no internato médico de medicina geral e familiar: um estudo nacionalPublication . Gaspar, Dina; de Jesus, Saul Neves; Cruz, Jose PestanaPROFESSIONAL MOTIVATION AND FAMILY MEDICINE RESIDENCY A National Study Background: Family medicine has some constraints, which may be considered critical for physicians' career choice, and motivation may be one of them. Motivation should be seen as a determinant of career success, particularly in educational context. The aim of this study was to develop an understanding about the family medicine residents' professional motivation, based on psychological and cognitive factors. Objectives: The following objectives were set: (1) to characterize the residents, in terms of cognitive-motivational variables; (2) to evaluate their assertive skills during the vocational training. Method: In 2005, we designed a mail survey applied to all graduates entering Family Medicine, in Portugal (N = 228), at the start of their specialty program. As part of a larger observational study, a 57 Likert scale items questionnaire was designed to collect descriptive data. In this cross sectional study we present data from professional project, professional commitment, intrinsic motivation, self-efficacy expectancies, results control expectancies, initial motivation to the specialty and assertiveness skills (cross sectional study). Results: From the target population, 109 completed questionnaires (47.8%) were returned. Most of the participants indicated high levels of professional orientation (77.1%) for family medicine and 92.6% had been globally committed in practice. At the beginning of the residency, the participants had medium (59.6%) or high (33.9%) levels of motivation for choosing this specialty, 89% were intrinsically motivated and 60.5% proved to be quite assertive in their patient approach. Conclusions: These findings suggest that medical graduates, studied in this research, were globally motivated for practicing in a Family Medicine context, contradicting the overall perception of a physicians' declined interest for this specialty. These results may have implications in the design of real-life training programs for postgraduate education in Family Medicine, a time when physicians are forming expectations about their career performance and professional well being. Future researches should continue studying more deeply the professional motivation of that population, throughout the vocational training in Family Medicine residency.
- Evidence that 1-methyl-l-tryptophan is a food-related odorant for the Senegalese sole (Solea senegalensis)Publication . Velez, Zélia; Hubbard, Peter; Hardege, Jörg D.; Welham, K.; Barata, E. N.; Canario, Adelino V. M.Nocturnal animals often rely heavily on olfactory cues to locate their food. This is especially true for fish whose prey live buried in the substrate. The aim of the current study was to identify non-polar odorants released by the ragworm (Hediste diversicolor) that are detected by the olfactory system of the Senegalese sole (Solea senegalensis) and therefore may be food-related cues. Ragworm-conditioned water was passed through a C18 solid-phase extraction cartridge (to remove polar compounds) and the eluate fractionated by reverse phase high-performance liquid chromatography (HPLC). The fractions were then tested for olfactory activity in the sole by the electro-olfactogram (EOG). Most olfactory activity was found in the first two fractions to elute from the HPLC column (0–4 min). Liquid chromatography-mass spectrometry (LC/MS) of both fractions revealed a base peak with a molecular mass of 219.4 Da and a fragment of 205.3 Da. These data are consistent with a methylated form of tryptophan; synthetic 1-methyl-l-tryptophan had a similar HPLC retention time (2.8 min) and similar LC/MS spectra. Furthermore, sole showed olfactory sensitivity to 1-methyl-l-tryptophan with the lower (left) epithelium being more sensitive than the upper (right). Cross-adaptation (using EOG recording) suggested that the olfactory receptors responding to 1-methyl-l-tryptophan are different in the lower epithelium from the upper. These results suggest that ragworms release 1-methyl-l-tryptophan, or similar tryptophan derivative, and that sole may use this chemical cue to locate and/or identify one of their main prey species. This may help the formation of artificial feeds that are more attractive to sole.
- Citizens’ voice as a device for political choicesPublication . Barreira, Ana Paula; Baleiras, Rui NunoWe describe a theoretical model aiming to discuss the welfare implications of different institutional architectures, varying from complete centralised political choices to different degrees of subnational political autonomy. By voting citizens express preferences regarding the desired political decision level. Citizens’ preferences can cover a variety of aspects, from environmental protection to public goods provision. The subnational political autonomy proposed in the model can assume two forms: The implementation of isolated communities or definition of a region. A trade-off between cost-sharing provision of public provision and the loss that results from sharing it with individuals holding different preferences is widely pondered. This model allows us to conclude that in the absence of inter-community compensatory transfers and in the presence of a unanimity voting system, citizens’ voice, stability and efficiency conditions are only guaranteed when citizens are completely segregated into homogenous communities or when there is a centralised political regime.
- A first last glacial maximum to younger dryas stalagmite record from southern PortugalPublication . Veiga-Pires, C.; Ghaleb, Bassam; Hélie, Jean-François; Moura, Delminda; Luis, Joaquim; Hillaire-Marcel, C.A newly launched research program permitted the sampling of speleothem deposit in the Algarve area (Southern Portugal) with the primary objective of constraining the ages of past humid intervals in the area from U-series measurements.
- Eukaryotic richness in the abyss: insights from pyrotag sequencingPublication . Pawlowski, Jan; Christen, Richard; Lecroq, Beatrice; Bachar, Dipankar; Shahbazkia, Hamid R.; Amaral-Zettler, Linda; Guillou, LaureBackground: The deep sea floor is considered one of the most diverse ecosystems on Earth. Recent environmental DNA surveys based on clone libraries of rRNA genes confirm this observation and reveal a high diversity of eukaryotes present in deep-sea sediment samples. However, environmental clone-library surveys yield only a modest number of sequences with which to evaluate the diversity of abyssal eukaryotes. Methodology/Principal Findings: Here, we examined the richness of eukaryotic DNA in deep Arctic and Southern Ocean samples using massively parallel sequencing of the 18S ribosomal RNA (rRNA) V9 hypervariable region. In very small volumes of sediments, ranging from 0.35 to 0.7 g, we recovered up to 7,499 unique sequences per sample. By clustering sequences having up to 3 differences, we observed from 942 to 1756 Operational Taxonomic Units (OTUs) per sample. Taxonomic analyses of these OTUs showed that DNA of all major groups of eukaryotes is represented at the deep-sea floor. The dinoflagellates, cercozoans, ciliates, and euglenozoans predominate, contributing to 17%, 16%, 10%, and 8% of all assigned OTUs, respectively. Interestingly, many sequences represent photosynthetic taxa or are similar to those reported from the environmental surveys of surface waters. Moreover, each sample contained from 31 to 71 different metazoan OTUs despite the small sample volume collected. This indicates that a significant faction of the eukaryotic DNA sequences likely do not belong to living organisms, but represent either free, extracellular DNA or remains and resting stages of planktonic species. Conclusions/Significance: In view of our study, the deep-sea floor appears as a global DNA repository, which preserves genetic information about organisms living in the sediment, as well as in the water column above it. This information can be used for future monitoring of past and present environmental changes.