Increased cerebral output of free radicals during hypoxia: implications for acute mountain sickness?

Bailey DM, Taudorf S, Berg RMG, Lundby C, McEneny J, Young IS, Evans KA, James PE, Shore A, Hullin DA, McCord JM, Pedersen BK, Moller K. Increased cerebral output of free radicals during hypoxia: implications for acute mountain sickness? Am J Physiol Regul Integr Comp Physiol 297: R1283-R1292, 2009. First published September 2, 2009; doi: 10.1152/ajpregu.00366.2009.-This study examined whether hypoxia causes free radical-mediated disruption of the blood-brain barrier (BBB) and impaired cerebral oxidative metabolism and whether this has any bearing on neurological symptoms ascribed to acute mountain sickness (AMS). Ten men provided internal jugular vein and radial artery blood samples during normoxia and 9-h passive exposure to hypoxia (12.9% O-2). Cerebral blood flow was determined by the Kety-Schmidt technique with net exchange calculated by the Fick principle. AMS and headache were determined with clinically validated questionnaires. Electron paramagnetic resonance spectroscopy and ozone-based chemiluminescence were employed for direct detection of spin-trapped free radicals and nitric oxide metabolites. Neuron-specific enolase (NSE), S100 beta, and 3-nitrotyrosine (3-NT) were determined by ELISA. Hypoxia increased the arterio-jugular venous concentration difference (a-v(D)) and net cerebral output of lipid-derived alkoxyl-alkyl free radicals and lipid hydroperoxides (P

Line-profile tomography of exoplanet transits - II. A gas-giant planet transiting a rapidly rotating A5 star

Most of our knowledge of extrasolar planets rests on precise radial-velocity measurements, either for direct detection or for confirmation of the planetary origin of photometric transit signals. This has limited our exploration of the parameter space of exoplanet hosts to solar- and later-type, sharp-lined stars. Here we extend the realm of stars with known planetary companions to include hot, fast-rotating stars. Planet-like transits have previously been reported in the light curve obtained by the SuperWASP survey of the A5 star HD15082 (WASP-33 V = 8.3, v sini = 86 km s-1). Here we report further photometry and time-series spectroscopy through three separate transits, which we use to confirm the existence of a gas-giant planet with an orbital period of 1.22d in orbit around HD15082. From the photometry and the properties of the planet signal travelling through the spectral line profiles during the transit, we directly derive the size of the planet, the inclination and obliquity of its orbital plane and its retrograde orbital motion relative to the spin of the star. This kind of analysis opens the way to studying the formation of planets around a whole new class of young, early-type stars, hence under different physical conditions and generally in an earlier stage of formation than in sharp-lined late-type stars. The reflex orbital motion of the star caused by the transiting planet is small, yielding an upper mass limit of 4.1MJupiter on the planet. We also find evidence of a third body of substellar mass in the system, which may explain the unusual orbit of the transiting planet. In HD 15082, the stellar line profiles also show evidence of non-radial pulsations, clearly distinct from the planetary transit signal. This raises the intriguing possibility that tides raised by the close-in planet may excite or amplify the pulsations in such stars.

Progenitors of Core-Collapse Supernovae

Knowledge of the progenitors of core-collapse supernovae is a fundamental component in understanding the explosions. The recent progress in finding such stars is reviewed. The minimum initial mass that can produce a supernova (SN) has converged to 8 +/- 1 M-circle dot from direct detections of red supergiant progenitors of II-P SNe and the most massive white dwarf progenitors, although this value is model dependent. It appears that most type Ibc SNe arise from moderate mass interacting binaries. The highly energetic, broad-lined Ic SNe are likely produced by massive, Wolf-Rayet progenitors. There is some evidence to suggest that the majority of massive stars above similar to 20 M-circle dot may collapse quietly to black holes and that the explosions remain undetected. The recent discovery of a class of ultrabright type H SNe and the direct detection of some progenitor stars bearing luminous blue variable characteristics suggest some very massive stars do produce highly energetic explosions. The physical mechanism is under debate, and these SNe pose a challenge to stellar evolutionary theory.

Fault Diagnostics for Internal Combustion Engines – Current and Future Techniques

The adoption of each new level of automotive emissions legislation often requires the introduction of additional emissions reduction techniques or the development of existing emissions control systems. This, in turn, usually requires the implementation of new sensors and hardware which must subsequently be monitored by the on-board fault detection systems. The reliable detection and diagnosis of faults in these systems or sensors, which result in the tailpipe emissions rising above the progressively lower failure thresholds, provides enormous challenges for OBD engineers. This paper gives a review of the field of fault detection and diagnostics as used in the automotive industry. Previous work is discussed and particular emphasis is placed on the various strategies and techniques employed. Methodologies such as state estimation, parity equations and parameter estimation are explained with their application within a physical model diagnostic structure. The utilization of symptoms and residuals in the diagnostic process is also discussed. These traditional physical model based diagnostics are investigated in terms of their limitations. The requirements from the OBD legislation are also addressed. Additionally, novel diagnostic techniques, such as principal component analysis (PCA) are also presented as a potential method of achieving the monitoring requirements of current and future OBD legislation.

Inverse Gaussian Modeling of Turbulence-Induced Fading in Free-Space Optical Systems

We propose the inverse Gaussian distribution, as a less complex alternative to the classical log-normal model, to describe turbulence-induced fading in free-space optical (FSO) systems operating in weak turbulence conditions and/or in the presence of aperture averaging effects. By conducting goodness of fit tests, we define the range of values of the scintillation index for various multiple-input multiple-output (MIMO) FSO configurations, where the two distributions approximate each other with a certain significance level. Furthermore, the bit error rate performance of two typical MIMO FSO systems is investigated over the new turbulence model; an intensity-modulation/direct detection MIMO FSO system with Q-ary pulse position modulation that employs repetition coding at the transmitter and equal gain combining at the receiver, and a heterodyne MIMO FSO system with differential phase-shift keying and maximal ratio combining at the receiver. Finally, numerical results are presented that validate the theoretical analysis and provide useful insights into the implications of the model parameters on the overall system performance. © 2011 IEEE.

Proteomic identification of plasma proteins as markers of growth promoter abuse in cattle

Growth-promoting agents are continually misused for increasing animal growth and fraudulent gain in the meat industry, yet detection rates from conventional targeted testing for drug residues do not reflect this. This is because testing currently relies on direct detection of drugs or related metabolites and administrators of such compounds can take adaptive measures to avoid detection through the use of endogenous or unknown drugs, and low dose or combined mixtures. New detection methods are needed which focus on the screening of biological responses of an animal to such growth-promoting agents as it has been demonstrated that genomic, proteomic and metabolomics profiles are altered by xenobiotic intake. Therefore, an untargeted proteomics approach using comparative two-dimensional gel electrophoresis (2DE) was carried out to identify putative proteins altered in plasma after treatment with oestradiol, dexamethasone or prednisolone. Twenty-four male cattle were randomly assigned to four groups (n = 6) for experimental treatment over 40 days, namely a control group of non-treated cattle, and three groups administered 17β-oestradiol-3-benzoate (0.01 mg/kg, intramuscular), dexamethasone sodium phosphate (0.7 mg/day, per os) or prednisolone acetate (15 mg/day, per os), respectively. Plasma collected from each animal at day 25 post study initiation was subjected to proteomic analysis by 2DE for comparison of protein expression between treated and untreated animals. Analysis of acquired gel images revealed 22 plasma proteins which differed in expression by more than 50 % (p < 0.05) in treated animals compared to untreated animals. Proteins of interest underwent identification by LC–MS/MS analysis and were found to have associated roles in transport, blood coagulation, immune response and metabolism pathways. In this way, seven proteins are highlighted as novel biomarker candidates including transthyretin which is shown to be significantly increased in all treatment groups compared to control animals and potentially may find use as global markers of suspect anabolic practice.

On the antioxidant properties of erythropoietin and its association with the oxidative-nitrosative stress response to hypoxia in humans

Aim: The aim of this study was to examine if erythropoietin (EPO) has the potential to act as a biological antioxidant and determine the underlying mechanisms.

Methods: The rate at which its recombinant form (rHuEPO) reacts with hydroxyl (HO center dot), 2,2-diphenyl-1-picrylhydrazyl (DPPH center dot) and peroxyl (ROO center dot) radicals was evaluated in-vitro. The relationship between the erythopoietic and oxidative-nitrosative stress response to poikilocapneic hypoxia was determined separately in-vivo by sampling arterial blood from eleven males in normoxia and following 12 h exposure to 13% oxygen. Electron paramagnetic resonance spectroscopy, ELISA and ozone-based chemiluminescence were employed for direct detection of ascorbate (A(center dot-)) and N-tert-butyl-a-phenylnitrone spin-trapped alkoxyl (PBN-OR) radicals, 3-nitrotyrosine (3-NT) and nitrite (NO2-).

Results: We found rHuEPO to be a potent scavenger of HO center dot (k(r) = 1.03-1.66 x 10(11) M-1 s(-1)) with the capacity to inhibit Fenton chemistry through catalytic iron chelation. Its ability to scavenge DPPH. and ROO center dot was also superior compared to other more conventional antioxidants. Hypoxia was associated with a rise in arterial EPO and free radical-mediated reduction in nitric oxide, indicative of oxidative-nitrosative stress. The latter was confirmed by an increased systemic formation of A(center dot-), PBN-OR, 3-NT and corresponding loss of NO2- (P <0.05 vs. normoxia). The erythropoietic and oxidative-nitrosative stress responses were consistently related (r =-0.52 to 0.68, P <0.05).

Conclusion: These findings demonstrate that EPO has the capacity to act as a biological antioxidant and provide a mechanistic basis for its reported cytoprotective benefits within the clinical setting.

Rapid-bTB: a novel lateral flow test able to differentiate Mycobacterium bovis from Mycobacterium tuberculosis in sputum

Background: A novel lateral flow, immunochromatographic assay (LFD) specific for Mycobacterium bovis, the cause of bovine tuberculosis and zoonotic TB, was recently developed at Queen’s University Belfast. The LFD detects whole M. bovis cells, in contrast to other commercially available LFD tests (BD MGITTM TBc ID, SD Bioline TB Ag MPT 64, Capilia TB-Neo kit) which detect MPT64 antigen secreted during growth. The new LFD test has been evaluated in the veterinary context, and its specificity for M. bovis in the broadest sense (i.e. subsp. bovis, subsp. caprae and BCG) and sensitivity to detect M. bovis in positive MGIT™ liquid cultures was demonstrated comprehensively.
Methods: Preliminary work was carried out by researchers at Queen’s University Belfast to optimise sputum sample preparation, estimate the limit of detection (LOD) of the LFD with M. bovis-spiked sputum samples, and check LFD specificity by testing a broad range of non-tuberculous Mycobacterium spp. (NTM) and other bacterial genera commonly encountered in sputum samples (Haemophilus, Klebsiella, Pseudomonas, Staphylococcus). In the Cameroon laboratory direct detection of M. bovis in human sputa was attempted, and 50 positive sputum MGIT™ cultures and 33 cultures of various Mycobacterium spp. originally isolated from human sputa were tested.
Results: Sputum sample preparation consisted of digestion with 1% NALC for 30 min, centrifugation at 3000g for 20 min, PBS wash, centrifugation again, and pellet resuspended in KPL blocking buffer before 100 µl was applied to the LFD. The LOD of the LFD applied to M. bovis-spiked sputum was estimated to be 104 CFU/ml. A small number of confirmed Ziehl-Neelsen ‘3+’ M. bovis positive sputum samples were tested directly but no positive LFD results were obtained. All of the sputum MGIT™ cultures and mycobacterial cultures (including M. tuberculosis, M. africanum, M. bovis, M. intracellulare, M. scrofulaceum, M. fortuitum, M. peregrinum, M. interjectum) tested LFD negative when read after 15 min except for the M. bovis cultures, thereby confirming specificity of LFD for M. bovis in the clinical microbiology context.
Conclusions: Results indicate that the ‘Rapid-bTB’ LFD is a very specific test, able to differentiate M. bovis from M. tuberculosis, M. africanum, and a range of NTM isolated from human sputa in MGITTM liquid cultures. However, the LFD lacks sufficient sensitivity to be applied earlier in the diagnostic process to directly test human sputa.

Nanoparticle-based biosensors: development and application

Tese dout., Ciências Biotecnológicas, Universidade do Algarve, 2009

Análise de sistemas de comunicação óptica com multiplexagem de subportadora e transmissão em banda lateral única

Tese dout., Engenharia Electrónica e Computação, Universidade do Algarve, 2005

Validação do método de deteção de eritropoietina recombinante humana em urina humana por focalização isoelétrica

A eritropoietina (EPO) é uma substância que estimula a produção de eritrócitos, aumentando a oxigenação muscular, sendo segregada de forma natural pelo organismo e excretada na urina em baixas concentrações. Devido às suas propriedades e características, a EPO foi rapidamente introduzida no mundo do desporto, como substância ilícita, proporcionando vantagens no rendimento desportivo. No início de 2000 foi desenvolvido um método de deteção direta de EPO Recombinante (rHuEPO) em urina humana por Lasne, baseado na focalização isoelétrica (IEF) em gel de poliacrilamida, seguido de duplo blote, tendo este sido publicado e validado. Em 2002, a Agência Mundial Antidopagem (AMA) implementou este mesmo método, sendo atualmente um dos métodos oficiais utilizado pelos laboratórios acreditados pela AMA. Desta forma, o ponto de partida para a realização deste trabalho consistiu na necessidade de implementar e validar o método de referência de IEF para a deteção de rHuEPO em urina humana. O trabalho foi realizado no Laboratório de Análises e Dopagem (LAD) do Instituto do Desporto de Portugal (IDP), atual Instituto Português do Desporto e Juventude (IPDJ). O principal objetivo deste trabalho consistiu no estudo/investigação de diferentes parâmetros de validação (especificidade/seletividade; capacidade de identificação; limite de deteção; exatidão e repetibilidade), de acordo com o protocolado no Procedimento Geral interno do Laboratório de Análises de Dopagem de Lisboa (LAD). O referido método de triagem e confirmação revelou possuir características de desempenho conformes com os requisitos aplicáveis, pelo que é considerado validado e apto.

Molecular tools in the diagnostic and epidemiology of infections caused by members of Mycobacterium avium Complex

Mycobacterium avium Complex (MAC) comprises microorganisms that affect a wide range of animals including humans. The most relevant are Mycobacterium avium subspecies hominissuis (Mah) with a high impact on public health affecting mainly immunocompromised individuals and Mycobacterium avium subspecies paratuberculosis (Map) causing paratuberculosis in animals with a high economic impact worldwide. In this work, we characterized 28 human and 67 porcine Mah isolates and evaluated the relationship among them by Multiple-Locus Variable number tandem repeat Analysis (MLVA). We concluded that Mah population presented a high genetic diversity and no correlations were inferred based on geographical origin, host or biological sample. For the first time in Portugal Map strains, from asymptomatic bovine faecal samples were isolated highlighting the need of more reliable and rapid diagnostic methods for Map direct detection. Therefore, we developed an IS900 nested real time PCR with high sensitivity and specificity associated with optimized DNA extraction methodologies for faecal and milk samples. We detected 83% of 155 faecal samples from goats, cattle and sheep, and 26% of 98 milk samples from cattle, positive for Map IS900 nested real time PCR. A novel SNPs (single nucleotide polymorphisms) assay to Map characterization based on a Whole Genome Sequencing analysis was developed to elucidate the genetic relationship between strains. Based on sequential detection of 14 SNPs and on a decision tree we were able to differentiate 14 phylogenetic groups with a higher discriminatory power compared to other typing methods. A pigmented Map strain was isolated and characterized evidencing for the first time to our knowledge the existence of pigmented Type C strains. With this work, we intended to improve the ante mortem direct molecular detection of Map, to conscientiously aware for the existence of Map animal infections widespread in Portugal and to contribute to the improvement of Map and Mah epidemiological studies.

Étude des collisions proton-proton dans l’expérience ATLAS avec les détecteurs ATLAS-MPX

Les seize détecteurs MPX constituant le réseau ATLAS-MPX ont été placés à différentes positions dans le détecteur ATLAS et sa averne au CERN dans le but de mesurer en emps réel les champs de radiation produits ar des particules primaires (protons des faisceaux) et des particules secondaires (kaons, pions, g, protons) issues des collisions proton-proton. Des films de polyéthylène (PE) et de fluorure de lithium (6LiF) recouvrent les détecteurs afin d’augmenter leur sensibilité aux neutrons produits par les particules primaires et secondaires interagissant avec les matériaux présents dans l’environnement d’ATLAS. La reconnaissance des traces laissées par les particules dans un détecteur ATLAS-MPX se fait à partir des algorithmes du logiciel MAFalda (“Medipix Analysis Framework”) basé sur les librairies et le logiciel d’analyse de données ROOT. Une étude sur le taux d’identifications erronées et le chevauchement d’amas a été faite en reconstruisant les activités des sources 106Ru et 137Cs. L’efficacité de détection des neutrons rapides a été mesurée à l’aide des sources 252Cf et 241AmBe (neutrons d’énergie moyenne de 2.13 et 4.08 MeV respectivement). La moyenne des efficacités de détection mesurées pour les neutrons produits par les sources 252C f et 241AmBe a été calculée pour les convertisseurs 6LiF et PE et donnent (0.8580 ± 0.1490)% et (0.0254 ± 0.0031)% pour LiF et (0.0510 ± 0.0061)% et (0.0591 ± 0.0063)% pour PE à bas et à haut seuil d’énergie respectivement. Une simulation du calcul de l’efficacité de détection des neutrons dans le détecteur MPX a été réalisée avec le logiciel GEANT4. Des données MPX correspondant aux collisions proton-proton à 2.4 TeV et à 7 TeV dans le centre de masse ont été analysées. Les flux détectés d’électrons et de photons sont particulièrement élevés dans les détecteurs MPX01 et MPX14 car ils sont plus près du point de collision. Des flux de neutrons ont été estimés en utilisant les efficacités de détection mesurées. Une corrélation avec la luminosité du LHC a été établie et on prédit que pour les collisions à 14 TeV dans le centre de masse et avec une luminosité de 10^34 cm-1*s-1 il y aura environ 5.1x10^8 ± 1.5x10^7 et 1.6x10^9 ± 6.3x10^7 particules détectées par les détecteurs MPX01 et MPX14 respectivement.

Infecção por C. psittaci: uma revisão com ênfase em psitacídeos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Canine ehrlichiosis: clinical, hematological, serological and molecular aspects

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)