984 resultados para TIBIAL VESSEL OCCLUSIONS


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Thèse réalisée dans le cadre d'une cotutelle entre l'Université de Montréal et l'Université d'Auvergne en France

Relevância:

20.00% 20.00%

Publicador:

Resumo:

L'athérosclérose est une maladie inflammatoire chronique caractérisée par l'accumulation de cholestérol dans la paroi artérielle et associée à une réponse immunitaire anormale dans laquelle les macrophages jouent un rôle important. Récemment, il a été démontré que les vaisseaux lymphatiques jouent un rôle primordial dans le transport inverse du cholestérol (Martel et al. JCI 2013). L’objectif global de mon stage de maîtrise a été de mieux caractériser la dysfonction lymphatique associée à l’athérosclérose, en étudiant de plus près l’origine physiologique et temporelle de ce mauvais fonctionnement. Notre approche a été d’étudier, depuis l’initiation de l’athérosclérose jusqu’à la progression d’une lésion athérosclérotique tardive, la physiologie des deux constituants principaux qui forment les vaisseaux lymphatiques : les capillaires et collecteurs lymphatiques. En utilisant comme modèle principal des souris Ldlr-/-; hApoB100+/+, nous avons pu démontrer que la dysfonction lymphatique est présente avant même l’apparition de l’athérosclérose, et que cette dysfonction est principalement associée avec un défaut au niveau des vaisseaux collecteurs, limitant ainsi le transport de la lymphe des tissus périphériques vers le sang. De plus, nous avons démontré pour la première fois l’expression du récepteur au LDL par les cellules endothéliales lymphatiques. Nos travaux subséquents démontrent que ce défaut de propulsion de la lymphe pourrait être attribuable à l’absence du récepteur au LDL, et que la dysfonction lymphatique observée précocement dans l’athérosclérose peut être limitée par des injections systémiques de VEGF (vascular endothelial growth factor) –C. Ces résultats suggèrent que la caractérisation fonctionnelle de la capacité de pompage des vaisseaux collecteurs serait une condition préalable à la compréhension de l'interaction entre la fonction du système lymphatique et la progression de l'athérosclérose. Ultimement, nos travaux nous ont amené à considérer de nouvelles cibles thérapeutiques potentielles dans la prévention et le traitement de l’athérosclérose.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Maritime ports are inevitable for India’s economic development. The very existence and sustainable development of ports depend on clean port environment. There is a notion that shipping is an over regulated industry. But in India, it is being operated under sub- standard conditions, raising crucial issues of environmental pollution in the country’s ports. The negative impacts of vessel sourced pollution on the eco-fragile coastal peninsula can be detrimental to the living conditions, health and interests of the coastal population. It can disturb marine life and imbalance the aquatic ecosystem. The present study analyses control of vessel sourced pollution in Indian ports from an economic and ecological perspective. The study investigates legal reasons behind the weak control, regulation and monitoring over vessel sourced pollution in Indian ports. The loopholes in the legal system are identified and suggestion made to implement stronger enforcement. Unless, vessel operations are properly regulated in ports, the trade and economic prospects of India will be jeopardized.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

AEA Technology has provided an assessment of the probability of α-mode containment failure for the Sizewell B PWR. After a preliminary review of the methodologies available it was decided to use the probabilistic approach described in the paper, based on an extension of the methodology developed by Theofanous et al. (Nucl. Sci. Eng. 97 (1987) 259–325). The input to the assessment is 12 probability distributions; the bases for the quantification of these distributions are discussed. The α-mode assessment performed for the Sizewell B PWR has demonstrated the practicality of the event-tree method with input data represented by probability distributions. The assessment itself has drawn attention to a number of topics, which may be plant and sequence dependent, and has indicated the importance of melt relocation scenarios. The α-mode failure probability following an accident that leads to core melt relocation to the lower head for the Sizewell B PWR has been assessed as a few parts in 10 000, on the basis of current information. This assessment has been the first to consider elevated pressures (6 MPa and 15 MPa) besides atmospheric pressure, but the results suggest only a modest sensitivity to system pressure.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Time dependent gas hold-up generated in the 0.3 and 0.6 m diameter vessels using high viscosity castor oil and carboxy methyl cellulose (CMC) solution was compared on the basis of impeller speed (N) and gas velocity (V-G). Two types of hold-up were distinguished-the hold-up due to tiny bubbles (epsilon(ft)) and total hold-up (epsilon(f)), which included large and tiny bubbles. It was noted that vessel diameter (i.e. the scale of operation) significantly influences (i) the trends and the values of epsilon(f) and epsilon(ft), and (ii) the values of tau (a constant reflecting the time dependency of hold-up). The results showed that a scale independent correlation for gas hold-up of the form epsilon(f) or epsilon(ft) = A(N or P-G/V)(a) (V-G)(b), where "a" and "b" are positive constants is not appropriate for viscous liquids. This warrants further investigations into the effect of vessel diameter on gas hold-up in impeller agitated high viscosity liquids (mu or mu(a) > 0.4 Pa s). (C) 2003 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

OBJECTIVE: To determine the effects of different COCs on endothelial function. BACKGROUND: COCs all contain ethinylestradiol, but different progestins; three of the more common progestins are DSG, LN, and DR. Ethinylestradiol enhances some measures of vascular reactivity, but certain progestins may increase risk of vascular diseases and impair endothelial vasodilation. METHODS: Twenty-nine healthy women taking COCs containing 30 μg ethinylestradiol and 150 μg DSG (Marvelon, n = 10), 150 μg LN (Microgynon, n = 10), or 3 mg DR (Yasmin, n = 9) had their vascular reactivity measured using various techniques during their pill-free week (days 5-7) and the third week of active pills (days 26-28). A reference group (n = 10) underwent the same measurements on two consecutive cycles. RESULTS: FMD and LDI were significantly higher during active-pill visits than pill-free visits in women taking DSG and DR (p < 0.02), but not in women taking LN. There were no differences between the duplicate measures in the reference group. CONCLUSIONS: COCs containing 150 μg DSG or 3 mg DR significantly increase endothelium-dependent vasodilation in both large vessels and peripheral microvasculature. These effects may be due to the progestins exhibiting differential effects on eNOS expression.

Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Neurovascular coupling in response to stimulation of the rat barrel cortex was investigated using concurrent multichannel electrophysiology and laser Doppler flowmetry. The data were used to build a linear dynamic model relating neural activity to blood flow. Local field potential time series were subject to current source density analysis, and the time series of a layer IV sink of the barrel cortex was used as the input to the model. The model output was the time series of the changes in regional cerebral blood flow (CBF). We show that this model can provide excellent fit of the CBF responses for stimulus durations of up to 16 s. The structure of the model consisted of two coupled components representing vascular dilation and constriction. The complex temporal characteristics of the CBF time series were reproduced by the relatively simple balance of these two components. We show that the impulse response obtained under the 16-s duration stimulation condition generalised to provide a good prediction to the data from the shorter duration stimulation conditions. Furthermore, by optimising three out of the total of nine model parameters, the variability in the data can be well accounted for over a wide range of stimulus conditions. By establishing linearity, classic system analysis methods can be used to generate and explore a range of equivalent model structures (e.g., feed-forward or feedback) to guide the experimental investigation of the control of vascular dilation and constriction following stimulation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This article examines a 14th-c. translation into Old Occitan prose of a late-antique life of Alexander the Great: Justin’s Epitome of the 'Historia Philippicae' of Pompeius Trogus. The article argues that it is the work of translators whose knowledge of pagan Latin materials was incomplete and whose use of their native tongue rested on non-literary bases. This text has not been edited before, and examining its uneven treatment of its source provides important new insights into the work of translators in the later Middle Ages. In conclusion, the article suggests some new approaches to the understanding of translation as a process of reconstruction and adaptation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The field campaign LOFZY 2005 (LOFoten ZYklonen, engl.: Cyclones) was carried out in the frame of Collaborative Research Centre 512, which deals with low-pressure systems (cyclones) and the climate system of the North Atlantic. Cyclones are of special interest due to their influence on the interaction between atmosphere and ocean. Cyclone activity in the northern part of the Atlantic Ocean is notably high and is of particular importance for the entire Atlantic Ocean. An area of maximum precipitation exists in front of the Norwegian Lofoten islands. One aim of the LOFZY field campaign was to clarify the role cyclones play in the interaction of ocean and atmosphere. In order to obtain a comprehensive dataset of cyclone activity and ocean-atmosphere interaction a field experiment was carried out in the Lofoten region during March and April 2005. Employed platforms were the Irish research vessel RV Celtic Explorer which conducted a meteorological (radiosondes, standard parameters, observations) and an oceanographic (CTD) program. The German research aircraft Falcon accomplished eight flight missions (between 4-21 March) to observe synoptic conditions with high spatial and temporal resolution. In addition 23 autonomous marine buoys were deployed in advance of the campaign in the observed area to measure drift, air-temperature and -pressure and water-temperature. In addition to the published datasets several other measurements were performed during the experiment. Corresonding datasets will be published in the near future and are available on request. Details about all used platforms and sensors and all performed measurements are listed in the fieldreport. The following datasets are available on request: ground data at RV Celtic Explorer

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Split-hand/foot malformation (SHFM) associated with aplasia of long bones, SHFLD syndrome or Tibial hemimelia-ectrodactyly syndrome is a rare condition with autosomal dominant inheritance, reduced penetrance and an incidence estimated to be about 1 in 1,000,000 liveborns. To date, three chromosomal regions have been reported as strong candidates for harboring SHFLD syndrome genes: 1q42.2-q43, 6q14.1 and 2q14.2. We characterized the phenotype of nine affected individuals from a large family with the aim of mapping the causative gene. Among the nine affected patients, four had only SHFM of the hands and no tibial defects, three had both defects and two had only unilateral tibial hemimelia. In keeping with previous publications of this and other families, there was clear evidence of both variable expression and incomplete penetrance, the latter bearing hallmarks of anticipation. Segregation analysis and multipoint Lod scores calculations (maximum Lod score of 5.03 using the LINKMAP software) using all potentially informative family members, both affected and unaffected, identified the chromosomal region 17p13.1-17p13.3 as the best and only candidate for harboring a novel mutated gene responsible for the syndrome in this family. The candidate gene CRK located within this region was sequenced but no pathogenic mutation was detected.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Purpose of review Description of the progress about the vascular effects promoted by thyroid hormones. Recent findings Over the past few years, a number of studies have shown that in addition to genomic effects on blood vessels, thyroid hormones exert extranuclear nongenomic effects on vascular smooth muscle cells and endothelium. These nongenomic effects occur rapidly and do not involve thyroid hormone response elements-mediated transcriptional events. In this context, the genomic and nongenomic events promoted by thyroid hormones act in concert to control the vascular hemodynamic and regulate the cardiovascular function. Summary Considering the antiatherogenic property of thyroid hormones and the rapid effects produced by this molecule as a vasodilator, including that in the coronary bed, a better understanding of the molecular mechanisms involved in its action may contribute to the development of drugs that can be clinically used to increase the known benefits promoted by thyroid hormones in cardiovascular physiology.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Rationale: Major coronary vessels derive from the proepicardium, the cellular progenitor of the epicardium, coronary endothelium, and coronary smooth muscle cells (CoSMCs). CoSMCs are delayed in their differentiation relative to coronary endothelial cells (CoEs), such that CoSMCs mature only after CoEs have assembled into tubes. The mechanisms underlying this sequential CoE/CoSMC differentiation are unknown. Retinoic acid (RA) is crucial for vascular development and the main RA-synthesizing enzyme is progressively lost from epicardially derived cells as they differentiate into blood vessel types. In parallel, myocardial vascular endothelial growth factor (VEGF) expression also decreases along coronary vessel muscularization. Objective: We hypothesized that RA and VEGF act coordinately as physiological brakes to CoSMC differentiation. Methods and Results: In vitro assays (proepicardial cultures, cocultures, and RALDH2 [retinaldehyde dehydrogenase-2]/VEGF adenoviral overexpression) and in vivo inhibition of RA synthesis show that RA and VEGF act as repressors of CoSMC differentiation, whereas VEGF biases epicardially derived cell differentiation toward the endothelial phenotype. Conclusion: Experiments support a model in which early high levels of RA and VEGF prevent CoSMC differentiation from epicardially derived cells before RA and VEGF levels decline as an extensive endothelial network is established. We suggest this physiological delay guarantees the formation of a complex, hierarchical, tree of coronary vessels. (Circ Res. 2010;107:204-216.)