619 research outputs found
Parents d'enfants hospitalisés dans une unité de soins intensifs: une étude exploratoire de leur vécu.
Le travail présenté ici repose sur une recherche qualitative effectuée par l'Institut universitaire de médecine sociale et préventive de Lausanne (IUMSP), sur l'initiative de l'unité des soins intensifs médico-chirurgicaux de pédiatrie (SIP) du Centre hospitalier universitaire vaudois (CHUV). Cette étude détaille le vécu de parents dont l'enfant a été hospitalisé dans une unité de soins intensifs. Il a paru essentiel aux initiateurs du projet d'imaginer offrir un accompagnement et une aide de type préventif aux personnes concernées par la maladie ou l'accident de leur enfant. Toutefois, avant de procéder à ce dispositif, il convenait de savoir plus précisément: 1. Ce que les parents vivaient durant l'hospitalisation de leur enfant; 2. Quels étaient leurs besoins et leurs attentes (à l'égard de l'unité, à l'égard des soignants) en pareilles circonstances
The effect of beta-tricalcium phosphate on mechanical and thermal performances of poly(lactic acid)
Orthophosphates are bioactive crystals with similar structure, in terms of elemental composition and crystal nature, to human bone. In this work, biocomposite materials were prepared with poly(lactic acid) (PLA) as matrix, and betatricalcium phosphate (b-TCP) as osteoconductive filler by extrusion-compounding followed by conventional injection molding. The b-TCP load content was varied in the 10 40 wt% range and the influence of the b-TCP load on mechanical performance of PLA/b-TCP composites was evaluated. Mechanical properties of composites were obtained by standardized tensile, flexural, impact, and hardness tests. Thermal analysis of composites was carried out by means of differential scanning calorimetry; degradation at high temperatures was studied by thermogravimetric analysis; and the effect of the b-TCP load on dynamical response of composites was studied by mechanical thermal analysis in torsion mode. The bestbalanced properties were obtained for PLA composites containing 30 wt% b-TCP with a remarkable increase in the Young s modulus. These materials offer interesting properties to be used as base materials for medical applications such as interference screws due to high stiffness and mechanical resistance.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by "Conselleria d'Educacio, Cultura i Esport" - Generalitat Valenciana ref: GV/2014/008.Ferri Azor, JM.; Gisbert, I.; García Sanoguera, D.; Reig Pérez, MJ.; Balart Gimeno, RA. (2016). The effect of beta-tricalcium phosphate on mechanical and thermal performances of poly(lactic acid). Journal of Composite Materials. 50(30):4189-4198. https://doi.org/10.1177/0021998316636205S41894198503
Transcriptomic analysis of field-droughted sorghum from seedling to maturity reveals biotic and metabolic responses.
Drought is the most important environmental stress limiting crop yields. The C4 cereal sorghum [Sorghum bicolor (L.) Moench] is a critical food, forage, and emerging bioenergy crop that is notably drought-tolerant. We conducted a large-scale field experiment, imposing preflowering and postflowering drought stress on 2 genotypes of sorghum across a tightly resolved time series, from plant emergence to postanthesis, resulting in a dataset of nearly 400 transcriptomes. We observed a fast and global transcriptomic response in leaf and root tissues with clear temporal patterns, including modulation of well-known drought pathways. We also identified genotypic differences in core photosynthesis and reactive oxygen species scavenging pathways, highlighting possible mechanisms of drought tolerance and of the delayed senescence, characteristic of the stay-green phenotype. Finally, we discovered a large-scale depletion in the expression of genes critical to arbuscular mycorrhizal (AM) symbiosis, with a corresponding drop in AM fungal mass in the plants' roots
Biofabrication of customized bone grafts by combination of additive manufacturing and bioreactor knowhow
This study reports on an original concept of additive manufacturing for the fabrication of
tissue engineered constructs (TEC), offering the possibility of concomitantly manufacturing a
customized scaffold and a bioreactor chamber to any size and shape. As a proof of concept
towards the development of anatomically relevant TECs, this concept was utilized for the
design and fabrication of a highly porous sheep tibia scaffold around which a bioreactor
chamber of similar shape was simultaneously built. The morphology of the bioreactor/scaffold
device was investigated by micro-computed tomography and scanning electron microscopy
confirming the porous architecture of the sheep tibiae as opposed to the non-porous nature of
the bioreactor chamber. Additionally, this study demonstrates that both the shape, as well as
the inner architecture of the device can significantly impact the perfusion of fluid within the
scaffold architecture. Indeed, fluid flow modelling revealed that this was of significant
importance for controlling the nutrition flow pattern within the scaffold and the bioreactor
chamber, avoiding the formation of stagnant flow regions detrimental for in vitro tissue
development. The bioreactor/scaffold device was dynamically seeded with human primary
osteoblasts and cultured under bi-directional perfusion for two and six weeks. Primary human
osteoblasts were observed homogenously distributed throughout the scaffold, and were viable
for the six week culture period. This work demonstrates a novel application for additive
manufacturing in the development of scaffolds and bioreactors. Given the intrinsic flexibility
of the additive manufacturing technology platform developed, more complex culture systems
can be fabricated which would contribute to the advances in customized and patient-specific
tissue engineering strategies for a wide range of applications.This work was supported by the NHMRC, the Australian Research Council and Hans Fischer Senior Fellowship, IAS-TUM. Pedro Costa acknowledges the Portuguese Foundation for Science and Technology for his PhD grant (SFRH/BD/62452/2009)
Automation of Pivot Sprinkler Irrigation Systems to More Efficiently Utilize Rainfall and Irrigation Water
A study was conducted to develop automated pivot sprinkler irrigation systems and determine if such systems use less water and energy than manually operated systems. The study was conducted near Earth, Texas, using irrigation systems located on producers farms.
Sensors with transmitters and receivers were constructed and tested so that the irrigation systems can be controlled by wind, soil water tension, and rainfall. The sensors can be used separately or in combination to control the irrigation systems.
For several reasons it was not possible to determine if automated systems use less water and energy than manually operated systems. The major reason was the low capacity of the wells (114 to 204 m3/hr) supplying the irrigation systems.
To meet crop water requirements and losses due to evaporation and runoff, the well capacity should be at least 284 m3/hr. Since the wells could not supply adequate water, soil water tension was out of the tensiometer range for the last 60 days of the growing season. Considerable variation in soil water tension and content was noted between irrigation systems and within quadrants of each irrigation system. Systems planted to cotton would probably be easier to automate than those planted in corn because of the lower water requirements of cotton.
The wind and rainfall controls have more promise to aid in increasing water use efficiency than controls activated by soil water sensors. Wind controls could be used during preirrigation when more time is available to apply water and rainfall controls could be an aid to producers with remotely located irrigation systems
Influence of porosity and fibre diameter on the degradation of chitosan fibre-mesh scaffolds and cell adhesion
The state of the art approaches for tailoring the
degradation of chitosan scaffolds are based on altering the
chemical structure of the polymer. Nevertheless, such alterations
may lead to changes in other properties of scaffolds,
such as the ability to promote cell adhesion. The aim of this
study was to investigate the influence of physical parameters
such as porosity and fibre diameter on the degradation
of chitosan fibre-mesh scaffolds, as a possible way of tailoring
the degradation of such scaffolds. Four sets of scaffolds
with distinct fibre diameter and porosity were produced and
their response to degradation and cell adhesion was studied.
The degradation study was carried out at 37"C in a lysozyme
solution for five weeks. The extent of degradation was expressed
as percentage of weight loss of the dried scaffolds after
lysozyme treatment. Cell adhesion was assessed by Confocal
Microscopy. The results have shown that the scaffolds
with higher porosity degrade faster and that, within the same
range of porosity, the fibres with smaller diameter degrade
slightly faster. Furthermore, the morphological differences
between the scaffolds did not affect the degree of cell adhesion,
and the cells were observed throughout the thickness of
all four types of scaffold
Microparticles for sustained growth factor delivery in the regeneration of critically-sized segmental tibial bone defects
The Publisher's final version can be found by following the DOI link. Open access article.This study trialled the controlled delivery of growth factors within a biodegradable scaffold in a large segmental bone defect model. We hypothesised that co-delivery of vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) followed by bone morphogenetic protein-2 (BMP-2) could be more effective in stimulating bone repair than the delivery of BMP-2 alone. Poly(lactic-co-glycolic acid) (PLGA ) based microparticles were used as a delivery system to achieve a controlled release of growth factors within a medical-grade Polycaprolactone (PCL) scaffold. The scaffolds were assessed in a well-established preclinical ovine tibial segmental defect measuring 3 cm. After six months, mechanical properties and bone tissue regeneration were assessed. Mineralised bone bridging of the defect was enhanced in growth factor treated groups. The inclusion of VEGF and PDGF (with BMP-2) had no significant effect on the amount of bone regeneration at the six-month time point in comparison to BMP-2 alone. However, regions treated with VEGF and PDGF showed increased vascularity. This study demonstrates an effective method for the controlled delivery of therapeutic growth factors in vivo, using microparticles
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