Thrombose veineuse profonde : une thrombolyse est-elle efficace ? : revue cochrane pour le praticien

Scénario: Une patiente de 45 ans vous consulte car sa jambe droite est bleue, cyanosée, avec une tension dans le mollet depuis cinq jours, qui s'est étendue progressivement jusqu'au haut de la cuisse. La circonférence du mollet droit est 4 cm plus grande que celle du mollet gauche. La patiente est en surpoids (IMC à 35 kg/m2) et suit depuis quelques années un traitement oestro-progestatif. Elle n'a pas d'anamnèse familiale ou d'antécédent de maladie thromboembolique. Un ultrason montre une thrombose veineuse profonde (TVP) avec un thrombus s'étendant de la veine poplitée à la veine iliaque externe. Question: La patiente pourrait-elle bénéficier d'une thrombolyse? Contexte: Les complications de la TVP comprennent l'embolie pulmonaire et le syndrome post-thrombotique. Un syndrome post-thrombotique léger à modéré peut survenir chez 30-50% des patients malgré un traitement anticoagulant, qui prévient principalement l'embolie pulmonaire et la récidive de TVP. Cette mise à jour de revue systématique compare l'efficacité du traitement anticoagulant à celui combinant les anticoagulants et la thrombolyse (par streptokinase, urokinase ou activateur tissulaire du plasminogène)

Thrombolyse bei tiefer Venenthrombose? [Thrombolytic therapy in deep venous thrombosis?]

Sie sehen eine 45-jährige Patientin mit einem bläulich-zyanotischen rechten Bein. Vor fünf Tagen habe ein Spannungsschmerz in der Wade begonnen und sich zunehmend in den Oberschenkel hochgezogen. Die rechte Wade misst im Umfang 4 cm mehr als die linke. Die Anamnese ergibt keine familiäre oder persönliche Vorgeschichte einer thromboembolischen Erkrankung. Die Patientin ist übergewichtig ( BMI 35 kg/m2) und nimmt seit einigen Jahren eine Östrogen-Progesteron-Kombination. Der Ultraschall zeigt eine Thrombose der tiefen Beinvenen, die bis in die äussere Beckenvene reicht

Swiss family physicians' perceptions and attitudes towards knowledge translation practices.

BACKGROUND: Several studies have been performed to understand the way family physicians apply knowledge from medical research in practice. However, very little is known concerning family physicians in Switzerland. In an environment in which information constantly accumulates, it is crucial to identify the major sources of scientific information that are used by family physicians to keep their medical knowledge up to date and barriers to use these sources. Our main objective was to examine medical knowledge translation (KT) practices of Swiss family physicians. METHODS: The population consisted of French- and German-speaking private practice physicians specialised in family medicine. We conducted four interviews and three focus groups (n = 25). The interview guides of the semi-structured interviews and focus groups focused on (a) ways and means used by physicians to keep updated with information relevant to clinical practice; (b) how they consider their role in translating knowledge into practice; (c) potential barriers to KT; (d) solutions proposed by physicians for effective KT. RESULTS: Family physicians find themselves rather ambivalent about the translation of knowledge based on scientific literature, but generally express much interest in KT. They often feel overwhelmed by "information floods" and perceive clinical practice guidelines and other supports to be of limited usefulness for their practice. They often combine various formal and informal information sources to keep their knowledge up to date. Swiss family physicians report considering themselves as artisans, caring for patients with complex needs. CONCLUSION: Improved performance of KT initiatives in family medicine should be tailored to actual needs and based on high quality evidence-based sources

Meeting physicians' needs: a bottom-up approach for improving the implementation of medical knowledge into practice.

Multiple barriers to knowledge translation in medicine have been identified (ranging from information overload to abstraction of models), leading to important implementation gaps. This study aimed at assessing the suggestions of practicing physicians for possible improvements of knowledge translation (KT) effectiveness into clinical practice. We used a mixed methods design. French- German- and Italian-speaking general practitioners, psychiatrists, orthopaedic surgeons, cardiologists, and diabetologists practicing in Switzerland were interrogated through semi-structured interviews, focus group discussions, and an online survey. A total of 985 physicians from three regions of Switzerland participated in the online survey, whereas 39 participated in focus group discussions and 14 in face-to-face interviews. Physicians expressed limitations and difficulties related to KT into their daily practice. Several barriers were identified, including influence and pressure of pharmaceutical companies, non-publication of negative results, mismatch between guidelines and practice, education gaps, and insufficient collaboration between research and practice. Suggestions to overcome barriers were improving education concerning the evaluation of scientific publications, expanding applicability of guidelines, having free and easy access to independent journals, developing collaborations between research and practice, and creating tools to facilitate access to medical information. Our study provides suggestions for improving KT into daily medical practice, matching the views, needs and preferences of practicing physicians. Responding to suggestions for improvements brought up by physicians may lead to better knowledge translation, higher professional satisfaction, and better healthcare outcomes

DRAM:A three-dimensional analytical model for the mobilisation of root reinforcement in direct shear conditions

Roots can stabilise slopes against shallow landslides by mobilising their mechanical strength. Existing analytical models are highly simplified and typically focus on the ultimate limit state only, thus providing little insight into the underlying mechanism of reinforcement mobilisation. A new analytical model (‘DRAM’) was therefore developed to predict mechanical root reinforcement as a function of direct shear displacements. This model accounts for elasto-plastic root behaviour, three-dimensional root orientations, root failure through breakage or slippage, and a dynamically changing shear zone thickness. Comparison to two independent experimental direct shear data sets showed that the model was able to accurately predict the gradual mobilisation of root strength, the magnitude of peak root reinforcement, as well as the presence of significant root reinforcement at large shear displacements, associated with a relatively large quantity of roots slipping out of the surrounding soil. Because the newly developed model more closely resembles the underlying physics of the mobilisation of root reinforcement in direct shear while still being easy to use, it will be a useful tool for the engineering industry, in terms of quantifying root reinforcement distribution for limit analyses at the ultimate limit state, as well as for directing future research into the drivers of mechanical root reinforcement.</p

Mechanisms of root reinforcement in soils:An experimental methodology using four-dimensional X-ray computed tomography and digital volume correlation

Vegetation on railway or highway slopes can improve slope stability through the generation of soil pore water suctions by plant transpiration and mechanical soil reinforcement by the roots. To incorporate the enhanced shearing resistance and stiffness of root-reinforced soils in stability calculations, it is necessary to understand and quantify its effectiveness. This requires integrated and sophisticated experimental and multiscale modelling approaches to develop an understanding of the processes at different length scales, from individual root-soil interaction through to full soil-profile or slope scale. One of the challenges with multiscale models is ensuring that they sufficiently closely represent real behaviour. This requires calibration against detailed high-quality and data-rich experiments. This study presents a novel experimental methodology, which combines in situ direct shear loading of a willow root reinforced soil with X-ray computed tomography to capture the 3D chronology of soil and root deformation within the shear zone. Digital volume correlation (DVC) analysis was applied to the computed tomography (CT) dataset to obtain full-field 3D displacement and strain information. This paper demonstrates the feasibility and discusses the challenges associated with DVC experiments on root-reinforced soils

In situ measurement of root reinforcement using corkscrew extraction method

Mechanical root reinforcement is an important parameter to evaluate for stability analysis of rooted slopes. The contribution of roots is however difficult to quantify in situ without time-consuming methods or heavy equipment. Here we report field testing using the newly developed “corkscrew” method at two different sites with plantings of conifers and blackcurrant. In both sites we found positive correlations between root quantity and root reinforcement in surface layers where many roots were found. Below 125 mm depth, no correlations could be found, probably due to variability in soil stress and gravel content. Roots were shown not only to increase the soil peak strength, but also to add ductility to the soil, i.e., adding strength over much larger displacement ranges. Measured reinforcement, although similar to other experimental studies, was smaller than predicted using existing models. This may be attributed to the distinct difference in shear displacement required to mobilize the strength of rooted soil as compared with fallow soil. At displacements sufficient to mobilize root strength, the soil strength component has reduced from peak to a much smaller residual strength. The corkscrew method proved a promising tool to quantify root reinforcement in field conditions due to its ease of use and short test duration.</p

Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis

Aims: Rhizodeposits collected from hydroponic solutions with roots of maize and barley, and seed mucilage washed from chia, were added to soil to measure their impact on water retention and hysteresis in a sandy loam soil at a range of concentrations. We test the hypothesis that the effect of plant exudates and mucilages on hydraulic properties of soils depends on their physicochemical characteristics and origin.Methods: Surface tension and viscosity of the exudate solutions were measured using the Du Noüy ring method and a cone-plate rheometer, respectively. The contact angle of water on exudate treated soil was measured with the sessile drop method. Water retention and hysteresis were measured by equilibrating soil samples, treated with exudates and mucilages at 0.46 and 4.6 mg g−1 concentration, on dialysis tubing filled with polyethylene glycol (PEG) solution of known osmotic potential.Results: Surface tension decreased and viscosity increased with increasing concentration of the exudates and mucilage in solutions. Change in surface tension and viscosity was greatest for chia seed exudate and least for barley root exudate. Contact angle increased with increasing maize root and chia seed exudate concentration in soil, but not barley root. Chia seed mucilage and maize root rhizodeposits enhanced soil water retention and increased hysteresis index, whereas barley root rhizodeposits decreased soil water retention and the hysteresis effect. The impact of exudates and mucilages on soil water retention almost ceased when approaching wilting point at −1500 kPa matric potential.Conclusions: Barley rhizodeposits behaved as surfactants, drying the rhizosphere at smaller suctions. Chia seed mucilage and maize root rhizodeposits behaved as hydrogels that hold more water in the rhizosphere, but with slower rewetting and greater hysteresis

Significance of root hairs for plant performance under contrasting field conditions and water deficit

Background and Aims Previous laboratory studies have suggested selection for root hair traits in future crop breeding to improve resource use efficiency and stress tolerance. However, data on the interplay between root hairs and open-field systems, under contrasting soils and climate conditions, are limited. As such, this study aims to experimentally elucidate some of the impacts that root hairs have on plant performance on a field scale. Methods A field experiment was set up in Scotland for two consecutive years, under contrasting climate conditions and different soil textures (i.e. clay loam vs. sandy loam). Five barley (Hordeum vulgare) genotypes exhibiting variation in root hair length and density were used in the study. Root hair length, density and rhizosheath weight were measured at several growth stages, as well as shoot biomass, plant water status, shoot phosphorus (P) accumulation and grain yield. Key Results Measurements of root hair density, length and its correlation with rhizosheath weight highlighted trait robustness in the field under variable environmental conditions, although significant variations were found between soil textures as the growing season progressed. Root hairs did not confer a notable advantage to barley under optimal conditions, but under soil water deficit root hairs enhanced plant water status and stress tolerance resulting in a less negative leaf water potential and lower leaf abscisic acid concentration, while promoting shoot P accumulation. Furthermore, the presence of root hairs did not decrease yield under optimal conditions, while root hairs enhanced yield stability under drought. Conclusions Selecting for beneficial root hair traits can enhance yield stability without diminishing yield potential, overcoming the breeder’s dilemma of trying to simultaneously enhance both productivity and resilience. Therefore, the maintenance or enhancement of root hairs can represent a key trait for breeding the next generation of crops for improved drought tolerance in relation to climate change

Modelagem do crescimento radicular em função da dinâmica da água e resistência do solo.

Editado por Arnaldo Colozzi Filho, João Henrique Caviglione, Graziela Moraes de Cesare Barbosa, Luciano Grillo Gil, Tiago Santos Telles