Percorrer por autor "Guerreiro, Pedro"
A mostrar 1 - 10 de 19
Resultados por página
Opções de ordenação
- Active removal of inorganic phosphate from cerebrospinal fluid by the choroid plexusPublication . Guerreiro, Pedro; Bataille, Amy M.; Parker, Sonda L.; Renfro, J. LarryThe P-i concentration of mammalian cerebrospinal fluid (CSF) is about one-half that of plasma, a phenomenon also shown here in the spiny dogfish, Squalus acanthias. The objective of the present study was to characterize the possible role of the choroid plexus (CP) in determining CSF P-i concentration. The large sheet-like fourth CP of the shark was mounted in Ussing chambers where unidirectional P-33(i) fluxes revealed potent active transport from CSF to the blood side under short-circuited conditions. The flux ratio was 8: 1 with an average transepithelial resistance of 87 +/- 17.9 Omega . cm(2) and electrical potential difference of + 0.9 +/- 0.17 mV (CSF side positive). Active P-i absorption from CSF was inhibited by 10 mM arsenate, 0.2 mM ouabain, Na+ -free medium, and increasing the K+ concentration from 5 to 100 mM. Li+ stimulated transport twofold compared with Na+-free medium. Phosphonoformic acid (1 mM) had no effect on active Pi transport. RT-PCR revealed both P-i transporter (PiT) 1 and PiT2 (SLC20 family) gene expression, but no Na+ -P-i cotransporter II (SLC34 family) expression, in the shark CP. PiT2 immunoreactivity was shown by immunoblot analysis and localized by immunohistochemistry in (or near) the CP apical microvillar membranes of both the shark and rat. PiT1 appeared to be localized primarily to vascular endothelial cells. Taken together, these data indicate that the CP actively removes P-i from CSF. This process has transport properties consistent with a PiT2, Na+-dependent transporter that is located in the apical region of the CP epithelium.
- An empirical study of aspect-oriented metricsPublication . Piveta, Eduardo Kessler; Moreira, Ana; Pimenta, Marcelo Soares; Araujo, Joao; Guerreiro, Pedro; Tom Price, R.Metrics for aspect-oriented software have been proposed and used to investigate the benefits and the disadvantages of crosscutting concerns modularisation. Some of these metrics have not been rigorously defined nor analytically evaluated. Also, there are few empirical data showing typical values of these metrics in aspect-oriented software. In this paper, we provide rigorous definitions, usage guidelines, analytical evaluation, and empirical data from ten open source projects, determining the value of six metrics for aspect-oriented software (lines of code, weighted operations in module, depth of inheritance tree, number of children, crosscutting degree of an aspect, and coupling on advice execution). We discuss how each of these metrics can be used to identify shortcomings in existing aspect-oriented software. (C) 2012 Elsevier B.V. All rights reserved.
- Assessment of male reproductive traits in endangered leuciscids from the Iberian Peninsula: first attempts to store gametes both at short- and long-termPublication . Hernandez, Ana; Sousa-Santos, Carla; Gil, Fátima; Cabrita, Elsa; Guerreiro, Pedro; Gallego, VictorDuring the spring of 2022, several endangered leuciscid species (Anaecypris hispanica, Squalius aradensis, Anachondrostoma Occidentale, and Iberochondrostoma lusitanicum) were sampled both at the Vasco da Gama aquarium facilities and in some rivers of the Algarve region, Portugal. Sperm samples were extracted by gentle abdominal pressure and sperm motion parameters were assessed for the first time in four species, using a computerized analysis system. The results obtained showed that spermatozoa kinetic patterns were similar for all 4 species, with high motility and velocity values after the sperm activation time and with a marked decrease after 20. On the other hand, sperm longevity was highly variable between species, with short longevities (around 40 s) for A. hispanica and S. aradensis, and longer longevities (100-120 s) for A. occidentale and I. lusitanicum, which could indicate a latitudinal pattern in terms of sperm longevity. At the same time, morphometric analysis was carried out for the four target species, revealing that spermatozoa showed similar sizes and shapes to other external fertilizers belonging to Leuscididae, with small spherical heads, uniflagellate, and without acrosomes. In addition, a short-term gamete storage trail was performed by diluting sperm in 1:9 (sperm:extender) and storing them at 4oC. Although the results obtained were uneven among the species studied, the dilution and extender used generated motilities above 40% up to day 4 of storage in S. aradensis and I. lusitanicum, and up to days 1-2 in A. hispanica and A. occidentale, respectively. Finally, gamete cryopreservation trials were also carried out on these threatened species. Although cryopreserved samples showed significantly lower motility than fresh samples, some protocols generate acceptable percentages of viability, DNA integrity, and sperm motility in some species such as I. lusitanicum and A. occidentale. The data revealed that the protocol based on 10% DMSO plus 7.5% egg yolk generated the best results.This study is the first to assess the reproductive traits of wild and captive populations of endangered leuciscids endemic from the Iberian Peninsula, describing the spermatozoa kinetics and developing protocols for managing male gametes both in short- and long-term storage. Outcomes will provide new and useful tools to complement the management and conservation of ex situ breeding programs that are being developed for these four endangered species.
- Atividade física e envelhecimento: guia para uma prática segura e regular em casaPublication . Pais, Sandra; Guerreiro, Pedro; Santos, Joana; Guerreiro, Carla; Botelho, MartaA prática regular de atividade física está associada a um decréscimo da morbilidade e mortalidade, assim como, ao contrário, a inatividade física faz parte dos principais fatores de risco de mortalidade a nível global.
- Differential evolution in shortest path problemsPublication . Guerreiro, Pedro; Jesus, Mário; Marquez, AlbertoThis paper proves that the Differential Evolution (DE) algorithm is valid to solve the Shortest Path (SP) problem in random, median sized networks. From the trials, we have obtained an 9% accuracy, in the worst case scenario.
- Differential tissue immune stimulation through immersion in bacterial and viral agonists in the Antarctic Notothenia rossiiPublication . Sousa, Carmen; Peng, Maoxiao; Guerreiro, Pedro; Cardoso, João; Chen, Liangbiao; Canario, Adelino; Power, DeborahThe genome evolution of Antarctic notothenioids has been modulated by their extreme environment over millennia and more recently by human -caused constraints such as overfishing and climate change. Here we investigated the characteristics of the immune system in Notothenia rossii and how it responds to 8 h immersion in viral (Poly I:C, polyinosinic: polycytidylic acid) and bacterial (LPS, lipopolysaccharide) proxies. Blood plasma antiprotease activity and haematocrit were reduced in Poly I:C-treated fish only, while plasma protein, lysozyme activity and cortisol were unchanged with both treatments. The skin and duodenum transcriptomes responded strongly to the treatments, unlike the liver and spleen which had a mild response. Furthermore, the skin transcriptome responded most to the bacterial proxy (cell adhesion, metabolism and immune response processes) and the duodenum (metabolism, response to stress, regulation of intracellular signal transduction, and immune system responses) to the viral proxy. The differential tissue response to the two proxy challenges is indicative of immune specialisation of the duodenum and the skin towards pathogens. NOD -like and C -type lectin receptors may be central in recognising LPS and Poly I:C. Other antimicrobial compounds such as iron and seleniumrelated genes are essential defence mechanisms to protect the host from sepsis. In conclusion, our study revealed a specific response of two immune barrier tissue, the skin and duodenum, in Notothenia rossii when exposed to pathogen proxies by immersion, and this may represent an adaptation to pathogen infective strategies.
- Distribution and risk assessment of potential invasiveness of Australoheros facetus (Jenyns, 1842) in PortugalPublication . Baduy, Flavia; Saraiva, João; Ribeiro, Filipe; Canario, Adelino; Guerreiro, PedroInvasive species are recognized as a major cause of biodiversity decline. Legal regulations relating to the prevention, control, or eradication of invasive species should always be up-to-date, as the failure to recognize the problem, lack of adequate scientific information, or long legal intervals required to prepare the legislation may result in irreversible, possibly catastrophic, outcomes. This implies constant monitoring of the species distribution and levels of establishment, as well as detailed knowledge about its biology to predict dissemination and viability under changing environmental conditions. Pre-screening kits for potential invasive species are valuable tools for policy makers, as they provide information about if and how management measures should be taken. The Freshwater Fish Invasiveness Scoring Kit (FISK) and the Aquatic Species Invasiveness Screening Kit (AS-ISK) have been suggested as reliable tools to assess the potential risk of a species becoming invasive. The present study highlights the spread of the non-native chameleon cichlid Australoheros facetus in several streams of the major river drainages in southern Portugal and compares the fish assemblages and ecological indices in two selected sites in the Vascão and Odelouca rivers. We reviewed the current knowledge on the distribution, physiology, and behavior of A. facetus, and applied the toolkits FISK v2 and AS-ISK to this species to evaluate whether the species should be classified as invasive in Portugal. Field data show high abundance of the species in most streams and dominance in specific hotspots. The scores reached by the kits (FISK v2: 23; AS-ISK: 37) places A. facetus as a species with high potential of invasiveness and support the recent inclusion of this species in the invasive species list in Portugal (Decree-Law 92/2019), but, most of all, highlights the importance of frequent updates in both the field monitoring and the legal regulation and watch lists of invasive organisms.
- Does work per repetition and phase angle play a role in Sarcopenia?Publication . Pais, Sandra; Guerreiro, Pedro; Guerreiro, Carla; Botelho, MartaAging is related to the increase of several chronic diseases, such as, osteoarthritis, osteoporosis, diabetes, hypertension and sarcopenia. Sarcopenia (progressive loss of muscle mass and physical performance) is related to difficulties in treating other comorbidities, whether pharmacologically or non-pharmacologically.
- Effects of different slipping methods on the mortality of sardine, Sardina pilchardus, after purse-seine capture off the Portuguese Southern coast (Algarve)Publication . Marçalo, Ana; Guerreiro, Pedro; Bentes, Luis; Rangel, Mafalda; Monteiro, Pedro; Oliveira, Frederico; Afonso, Carlos; Pousao-Ferreira, Pedro; Benoit, Hugues P.; Breen, Mike; Erzini, Karim; Gonçalves, Jorge Manuel SantosThe effects of two different slipping methods on the survival, physical and physiological response of sardines, Sardina pilchardus, captured in a purse-seine fishery were investigated in southern Portugal. Sardines were collected and transferred into holding tanks onboard a commercial fishing vessel after being captured, crowded and deliberately released using two slipping procedures: standard and modified. The standard slipping procedure aggregated fish at high densities and made them "roll over" the floatline, while the modified procedure aggregated the fish at moderate densities and enabled them to escape through an opening created by adding weights to the floatline. Both slipping methods were compared with minimally harmed non-slipped sardines (sardines collected from the loose pocket of the purse seine). Survival rates were monitored in captivity over 28 days using three replicates for each treatment. The estimated survival of sardines was 43.6% for the non-slipped fish, 44.7% for the modified slipping and 11.7% for the standard slipping treatments. Scale loss indicated the level of physical impact experienced, with dead fish from the non-slipped and modified slipping technique showing significantly lower scale loss than those fish from the standard slipping treatment within the same period. Of the physiological indicators of stress measured, cortisol, glucose, lactate and osmolality attained peak values during slipping and up to the first hours after introduction to captivity. This work indicates that although delayed mortality after release may be substantial, appropriately modified slipping techniques significantly enhance survival of slipped sardines.
- Environmental salinity modulates olfactory sensitivity in the euryhaline European seabass, Dicentrarchus labrax, acclimated to seawater and brackish waterPublication . Velez, Zélia; Hubbard, Peter; Carvalho Alves, Alexandra; Costa, Rita; Guerreiro, PedroThe olfactory epithelium of fish is – of necessity – in intimate contact with the surrounding water. In euryhaline fish, movement from seawater to freshwater (and vice versa) exposes the epithelium to massive changes in salinity and ionic concentrations. How does the olfactory system function in the face of such changes? The current study compared olfactory sensitivity in seawater- (35‰) and brackish water-adapted seabass (5‰) using extracellular multi-unit recording from the olfactory nerve. Seawater-adapted bass had higher olfactory sensitivity to amino acid odorants when delivered in seawater than in freshwater. Conversely, brackish water-adapted bass had largely similar sensitivities to the same odorants when delivered in seawater or freshwater, although sensitivity was still slightly higher in seawater. The olfactory system of seawater-adapted bass was sensitive to decreases in external [Ca2+], whereas brackish water-adapted bass responded to increases in [Ca2+]; both seawater- and brackish water-adapted bass responded to increases in external [Na+] but the sensitivity was markedly higher in brackish water-adapted bass. In seawater-adapted bass, olfactory sensitivity to L-alanine depended on external Ca2+ ions, but not Na+; brackish water-adapted bass did respond to L-alanine in the absence of Ca2+, albeit with lower sensitivity, whereas sensitivity was unaffected by removal of Na+ ions. A possible adaptation of the olfactory epithelium was the higher number of mucous cells in brackish water-adapted bass. The olfactory system of seabass is able to adapt to low salinities, but this is not immediate; further studies are needed to identify the processes involved.