UNIDADES DE ALIMENTAÇÃO ININTERRUPTAS E OS REGIMES DE NEUTRO – CASO DE ESTUDO

As unidades de alimentação ininterruptas, UPS’s, desempenham na atualidade um papel fundamental na alimentação de cargas críticas nas instalações elétricas. Na cada vez mais premente necessidade de garantir qualidade e continuidade de energia levou a que este tipo de equipamentos se tenha desenvolvido e aperfeiçoado do ponto de vista tecnológico. A alimentação das instalações elétricas proveniente da rede de distribuição de energia contém ou está sujeita a micro interrupções, interrupções, sobretensões, conteúdo harmónico indesejável, não garantindo os níveis exigidos por alguns dos sistemas elétricos atuais colocando em causa a cadeia de valor de muitas empresas. O nível de disponibilidade e qualidade de potência está diretamente relacionado e produz efeitos diretos na continuidade das operações. Fatores como a produtividade, qualidade de produtos e serviços, capacidade concorrencial, segurança de bens e pessoas são imprescindíveis. Os sistemas de UPS’s de elevada potência com unidades de alimentação ligadas em paralelo garantindo redundância no fornecimento de energia às cargas constituem hoje a solução para o tipo de problemas referido. Contudo, a sua inserção nas instalações elétricas obriga a cuidados específicos, nomeadamente no que se refere ao regime de neutro da instalação, o qual condiciona de forma determinante a proteção de circuitos de distribuição e de pessoas. Em Portugal o regime de neutro adotado, de uma forma generalizada, regime de terras separadas (é o regime TT), no qual a proteção de pessoas é assegurada pela colocação de dispositivos de corrente residual diferencial. Solução que no caso das configurações de paralelos redundantes de UPS’s de elevada potência não garante um normal funcionamento destes sistemas concebidos para fundamentalmente funcionarem em regime TN (regime de Terra pelo Neutro). No presente trabalho apresenta-se no caso de estudo uma situação típica de instalação na qual se registam problemas de conflitos de neutro na saída de UPS’s que obrigam à alteração do tipo de dispositivo de proteção nas entradas das máquinas e circuito de bypass. São, ainda, apresentadas propostas de solução.

O doente diabético com doença coronária crónica. Como revascularizar?

A doença diabética representa uma das mais importantes preocupações para todos quantos têm de abordar e tratar a doença coronária, aguda ou crónica. A presença da diabetes coloca problemas particulares relacionados com o agravamento do prognóstico que nestes doentes se verifica, bem como as dificuldades inerentes à terapêutica, que nesta população levanta problemas especiais. O lugar da revascularização miocárdica no tratamento da doença coronária crónica tem sido matéria de controvérsia, muito por culpa de alguns estudos clínicos que falharam na demonstração da sua superioridade. Após o estudo BARI-2D a cirurgia de bypass aorto-coronário ganhou alguma vantagem sobre a angioplastia coronária, em doentes diabéticos com doença multivasos, vantagem esta que veio a ser recentemente consolidada no estudo FREEDOM, no qual se demonstra uma significa redução de eventos ao fim de cinco anos.

Biochemical mechanisms involved in pulmonary hypo-alveolarization induced by peroxides contaminating parenteral nutrition in newborn guinea pig

La dysplasie broncho-pulmonaire (DBP), caractérisée par un défaut de l’alvéolarisation, est une complication pathologique associée à un stress oxydant chez le nouveau-né prématuré. La DBP est présente chez près de 50 % des nouveau-nés de moins de 29 semaines de gestation. La nutrition parentérale (NP) que ces nouveau-nés reçoivent pour cause d’immaturité gastro-intestinale est une source importante de stress oxydant. En effet, leur NP est contaminée par des peroxydes, dont l’ascorbylperoxyde qui est une forme peroxydée du déshydroascorbate. La génération des peroxydes est catalysée par la lumière ambiante. La photoprotection de la NP, quoique difficile d’application en clinique, est associée à une diminution de l’incidence de la DBP chez les enfants prématurés. Chez l’animal nouveau-né, la photoprotection de la NP est associée à un meilleur développement alvéolaire. Ainsi, nous émettons l’hypothèse que l’ascorbylperoxide infusé avec la NP cause la perte d’alvéoles suite à une apoptose exagérée induite par l’oxydation du potentiel redox du glutathion. Cette oxydation du potentiel redox serait occasionnée par l’inhibition de la transformation hépatique de la méthionine en cystéine, menant à une diminution de la synthèse de glutathion au foie et dans les tissus tels que les poumons. La confirmation de cette hypothèse suggérera qu’un ajout de glutathion dans la NP permettra une meilleure détoxification de l’ascorbylperoxide par l’action de la glutathion peroxydase, et préviendra l’oxydation du potentiel redox et ainsi, la perte d'alvéoles par apoptose. Objectifs : Le but de mon projet de recherche est de comprendre les mécanismes biochimiques liant la NP et le développement de la DBP chez le nouveau-né prématuré et de proposer une alternative nutritionnelle prévenant le développement de cette complication fréquemment observée dans cette population. Les objectifs spécifiques sont : 1) d’évaluer l’impact, au poumon, de l’infusion de l’ascorbylperoxyde sur l’axe métabolique potentiel redox du glutathion - apoptose - le développement alvéolaire; 2) d’étudier l’impact de l’ascorbylperoxyde et du potentiel redox sur l’activité hépatique de la méthionine adénosyltransférase (MAT), première enzyme de la cascade métabolique transformant la méthionine en cystéine; et 3) de tenter de prévenir l’impact négatif de la NP ou de l’infusion d’ascorbylperoxyde sur le poumon en améliorant le statut en glutathion. Méthodes: Par un cathéter fixé dans la jugulaire, des cochons d’Inde de trois jours de vie (n = 8 par groupe) ont reçu en continu durant 4 jours une NP ou une solution de base (dextrose + NaCl) enrichie des différentes molécules à l’essai. Le premier objectif a été atteint en enrichissant la solution de base en ascorbylperoxyde à 0, 20, 60 et 180 μM. Ces solutions contenaient ou non 350 μM H2O2 pour se rapprocher des conditions cliniques. Le second objectif a été atteint en investiguant les mécanismes d’inhibition de la MAT dans des animaux infusés ou non avec des solutions contenant la solution de base, des peroxydes, du glutathion et la NP (dextrose + acides aminés + multivitamines + lipides). Le troisième objectif a été atteint en ajoutant ou non à une solution d’ascorbylperoxide ou à la NP 10 μM de glutathion (GSSG), afin d’obtenir une concentration plasmatique normale de glutathion. Après 4 jours, les poumons étaient prélevés et traités pour la détermination de GSH et GSSG par électrophorèse capillaire, le potentiel redox était calculé selon l'équation de Nernst et le niveau de caspase-3 actif (marqueur d’apoptose) par Western blot et l’index d’alvéolarisation quantifié par le nombre d’interceptes entre des structures histologiques et une droite calibrée. Les données étaient comparées par ANOVA, les effets étaient considérés comme significatifs si le p était inférieur à 0,05. Résultats: L’infusion de l’ascorbylperoxyde, indépendamment du H2O2, a induit une hypoalvéolarisation, une activation de la caspase-3 et une oxydation du potentiel redox de manière dose-dépendante. Ces effets ont été empêchés par l’ajout de GSSG à la NP ou à la solution d’ascorbylperoxyde (180 M). L’ascorbylperoxyde et le H2O2 ont inhibé l’activité de MAT tandis qu’elle était linéairement modulée par la valeur du potentiel redox hépatique. Conclusion : Nos résultats suggèrent que l’ascorbylperoxyde est l’agent actif de la NP conduisant au développement de la DBP. Ainsi la correction des bas niveaux de glutathion induits par les peroxydes de la NP favorise la détoxification des peroxydes et la correction du potentiel redox pulmonaire ; ce qui a protégé les poumons des effets délétères de la NP en outrepassant l’inhibition de la MAT hépatique. Nos résultats sont d'une grande importance car ils donnent de l'espoir pour une prévention possible de la DBP.

Traffic and spatial impacts and the classification of small highway-bypassed cities.

Texas Department of Transportation, Austin

A brief acconunt of the origin and progress of the patent syringe or stomach pump and lavement apparatus ... /

Mode of access: Internet.

Intelligent Automaticity in Moral Judgment and Decision-Making

Thesis (Ph.D.)--University of Washington, 2016-05

Advances in vascular tissue engineering

Coronary and peripheral artery bypass grafting is commonly used to relieve the symptoms of vascular deficiencies, but the Supply Of autologous artery or vein may not be sufficient or suitable for multiple bypass or repeat procedures, necessitating the use of other materials. Synthetic materials are suitable for large bore arteries but often thrombose when used in smaller arteries. Suitable replacement grafts must have appropriate characteristics, including resistance to infection, low immunogenicity and good biocompatability and thromboresistance, with appropriate mechanical and physiological properties and cheap and fast manufacture. Current avenues of graft development include coating synthetic grafts with either biological chemicals or cells with anticoagulatory properties. Matrix templates or acellular tubes of extracellular matrix (such as collagen) may be coated or infiltrated with cultured cells. Once placed into the artery, these grafts may become colonised by host cells and gain many of the properties of normal artery. Tissue-engineered blood vessels may also be formed from layers of human vascular cells grown in culture. These engineered vessels have many of the characteristics of arteries formed in vivo. Artificial arteries may be also be derived from peritoneal granulation tissue in body bioreactors by adapting the body's natural wound healing response to produce a hollow tube. (C) 2003 Elsevier Inc. All rights reserved.

Early alterations in serum creatine kinase and total cholesterol following high intensity eccentric muscle actions

Aim. The purpose of this experiment was to assess the levels of muscle soreness, serum total cholesterol (TC) and creatine kinase (CK) in the first 48 hours following fatiguing eccentric exercise performed with the triceps brachii. Methods. Eleven untrained male college students performed a total of 50 eccentric elbow extensions in 8 sets (6x7 and 2x4) with a load equal to 85% of their maximal concentric elbow extension strength. Isometric elbow extension strength, muscle soreness and circumference, and serum CK and TC concentrations were measured before, immediately after, and 2, 24 and 48 hours after the exercise. Results. Statistically reliable changes in isometric strength, serum CK and TC, muscle soreness and upper arm circumference occurred within the first 48 hours following eccentric exercise. Serum TC concentrations exhibited a very rapid (within 2 hours) reduction from pre-exercise values after eccentric exercise to a relatively stable concentration of approximately 85% of baseline. Conclusion. These results suggest that serum TC concentration may follow the time-course of reductions in force generating capacity more closely than other biochemical markers of muscle damage.

Evidence for endothermic ancestors of crocodiles at the stem of archosaur evolution

Physiological, anatomical, and developmental features of the crocodilian heart support the paleontological evidence that the ancestors of living crocodilians were active and endothermic, but the lineage reverted to ectothermy when it invaded the aquatic, ambush predator niche. In endotherms, there is a functional nexus between high metabolic rates, high blood flow rates, and complete separation of high systemic blood pressure from low pulmonary blood pressure in a four-chambered heart. Ectotherms generally lack all of these characteristics, but crocodilians retain a four-chambered heart. However, crocodilians have a neurally controlled, pulmonary bypass shunt that is functional in diving. Shunting occurs outside of the heart and involves the left aortic arch that originates from the right ventricle, the foramen of Panizza between the left and right aortic arches, and the cog-tooth valve at the base of the pulmonary artery. Developmental studies show that all of these uniquely crocodilian features are secondarily derived, indicating a shift from the complete separation of blood flow of endotherms to the controlled shunting of ectotherms. We present other evidence for endothermy in stem archosaurs and suggest that some dinosaurs may have inherited the trait.

Direct continuities between cisternae at different levels of the Golgi complex in glucose-stimulated mouse islet beta cells

Direct continuity between the membranes of cisternae in the Golgi complex in mammalian cells rarely has been observed; when seen, its documentation has been equivocal. Here we have used dual-axis electron microscope tomography to examine the architecture of the Golgi in three dimensions at approximate to6-nm resolution in rapidly frozen, freeze-substituted murine cells that make and secrete insulin in response to glucose challenge. Our data show three types of direct connections between Golgi cisternae that are normally distinct from one another. These connections all bypass interceding cisternae. We propose that when pancreatic beta cells are stimulated to synthesize and secrete insulin rapidly in vivo, such connections provide a continuous lumen that facilitates the rapid transit of large amounts of newly made protein for secretion. The heterotypic fusion of cisternae, even transiently, raises important questions about the molecular mechanisms that (i) facilitate the fusion/fission of cisternal membranes and control the directionality and specificity of such events, and (it) retain Golgi processing enzymes at specific places within individual cisternae when two cisternae at different levels in the Golgi have fused, maintaining the sequential processing hierarchy that is a hallmark of Golgi organization.

Quality assurance of paediatric cardiac surgery: A prospective 6-year analysis

Objective: To audit effective quality assurance methods to monitor outcomes following paediatric cardiac surgery at a single institution. Methods: All patients undergoing cardiac surgery from January 1996 to December 2001 were enrolled prospectively. Patients were stratified by complexity of surgical procedure into four groups, with Category 4 being the most complex procedure. Outcome measures included death, length of admission and morbidity from complications. Results: A total of 1815 patients underwent 1973 surgical procedures. Of these, 1447 (73.3%) were cardiopulmonary bypass procedures, and 543 (27.5%) were more complex (Category 3 and 4) procedures. Median patient age was 3.5 years (range, 1 day-20 years) and patient weight 15.0 kg (range, 900 g to 90 kg). Sixty-six patients (3.6%) died during the study period. Of the procedures in 1996, 22.7% were classified as complex compared with 29.2% of procedures in 2001. The annual surgical mortality ranged from 1.9-4.7% (P=0.20), and when mortality was adjusted for complexity of surgery, there was no significant yearly variation in the mortality rate (P=0.57). Analysis of individual surgeon's results showed no significant difference in the mortality rate by complexity of surgery performed (P=0.90). Mean ventilation times did not change significantly over time (P=0.79). The yearly incidence of significant neurological complications ranged from 0.6% to 4.5% and the incidence of arrhythmias from 4.2% to 8.0%. No difference was detected between the years. Conclusions: Stratifying complexity of surgery proved valuable in monitoring surgical outcomes and detecting differences in performance over time as large subgroups were created for analysis.

Clinical decision-making and myocardial viability: current perspectives

Not all myocardium involved in a myocardial infarction is dead or irreversibly damaged. The balance between the amount of scar and live tissue, and the nature of the live tissue, determine the likelihood that contractile function will improve after revascularisation. This improvement (which defines viability) may be predicted with about 80% accuracy using several techniques. This review examines the determinants of functional recovery and how they may be integrated in making decisions regarding revascularisation. (Intern Med J 2005; 35: 118–125)

3-D magnetic resonance angiography versus conventional angiography in peripheral arterial disease: Pilot study

Angiography is usually performed as the preoperative road map for those requiring revascularization for lower extremity peripheral arterial disease (PAD). The alternative investigations are ultrasound, 3-D magnetic resonance angiography (3-D MRA) and computed tomography angiography. This pilot study aimed to assess whether 3-D MRA could replace the gold standard angiography in preoperative planning. Eight patients considered for aortoiliac or infrainguinal arterial bypass surgery were recruited. All underwent both imaging modalities within 7 days. A vascular surgeon and a radiologist each reported on the images from both the 3-D MRA and the angiography, with blinding to patient details and each others reports. Comparisons were made between the reports for the angiographic and the 3-D MRA images, and between the reports of the vascular surgeon and the radiologist. Compared to the gold standard angiogram, 3-D MRA had a sensitivity of 77% and specificity of 94% in detecting occlusion, and a sensitivity of 72% and specificity of 90% in differentiating high grade (> 50%) versus low grade (< 50%) stenoses. There was an overall concordance of 78% between the two investigations with a range of 62% in the peroneal artery to 94% in the aorta. 3-D MRA showed flow in 23% of cases where conventional angiography showed no flow. In the present pilot study, 3-D MRA had reasonable concordance with the gold standard angiography, depending on the level of the lesion. At times it showed vessel flow where occlusion was shown on conventional angiogram. 3-D MRA in peripheral vascular disease is challenging the gold standard, but is inconsistent at present.

A cost-effectiveness analysis of fluvastatin in patients with diabetes after successful percutaneous coronary intervention

Background: The Lescol Intervention Prevention Study (LIPS) was a multinational randomized controlled trial that showed a 47% reduction in the relative risk of cardiac death and a 22% reduction in major adverse cardiac events (MACEs) from the routine use of fluvastatin, compared with controls, in patients undergoing percutaneous coronary intervention (PCI, defined as angioplasty with or without stents). In this study, MACEs included cardiac death, nonfatal myocardial infarction, and subsequent PCI and coronary artery bypass graft. Diabetes was the greatest risk factor for MACEs. Objective: This study estimated the cost-effectiveness of fluvastatin when used for secondary prevention of MACEs after PCI in people with diabetes. Methods: A post hoc subgroup analysis of patients with diabetes from the LIPS was used to estimate the effectiveness of fluvastatin in reducing myocardial infarction, revascularization, and cardiac death. A probabilistic Markov model was developed using United Kingdom resource and cost data to estimate the additional costs and quality-adjusted life-years (QALYs) gained over 10 years from the perspective of the British National Health Service. The model contained 6 health states, and the transition probabilities were derived from the LIPS data. Crossover from fluvastatin to other lipid-lowering drugs, withdrawal from fluvastatin, and the use of lipid-lowering drugs in the control group were included. Results: In the subgroup of 202 patients with diabetes in the LIPS trial, 18 (15.0%) of 120 fluvastatin patients and 21 (25.6%) of 82 control participants were insulin dependent (P = NS). Compared with the control group, patients treated with fluvastatin can expect to gain an additional mean (SD) of 0.196 (0.139) QALY per patient over 10 years (P < 0.001) and will cost the health service an additional mean (SD) of 10 (E448) (P = NS) (mean [SD] US $16 [$689]). The additional cost per QALY gained was;(51 (US $78). The key determinants of cost-effectiveness included the probabilities of repeat interventions, cardiac death, the cost of fluvastatin, and the time horizon used for the evaluation. Conclusion: Fluvastatin was an economically efficient treatment to prevent MACEs in these patients with diabetes undergoing PCI.