15,403 research outputs found
In vitro localization of bone growth factors in constructs of biodegradable scaffolds seeded with marrow stromal cells and cultured in a flow perfusion bioreactor
Tissue engineering strategies aim at controlling the behavior of individual cells to stimulate tissue
formation. This control is achieved by mimicking signals that manage natural tissue development
or repair. Flow perfusion bioreactors that create culture environments with minimal diffusion constraints
and provide cells with mechanical stimulation may closely resemble in vivo conditions for
bone formation. Therefore, these culturing systems, in conjunction with an appropriate scaffold and
cell type, may provide significant insight towards the development of in vitro tissue engineering models
leading to improved strategies for the construction of bone tissue substitutes. The objective of
this study was to investigate the in vitro localization of several bone growth factors that are usually
associated with bone formation in vivo by culturing rat bone marrow stromal cells seeded onto
starch-based biodegradable fiber meshes in a flow perfusion bioreactor. The localization of several
bone-related growth factors–namely, transforming growth factor-!1, platelet-derived growth factor-
A, fibroblast growth factor-2, vascular endothelial growth factor, and bone morphogenetic protein-
2–was determined at two different time points in scaffolds cultured under perfusion conditions
at two different flow rates using an immunohistochemistry technique. The results show the presence
of regions positively stained for all the growth factors considered, except platelet-derived growth
factor-A. Furthermore, the images obtained from the positively stained sections suggest an increase
in the immunohistochemically stained area at the higher flow rate and culture time. These observations
demonstrate that flow perfusion augments the functionality of scaffold/cell constructs grown
in vitro as it combines both biological and mechanical factors to enhance cell differentiation and cell
organization within the construct. This study also shows that flow perfusion bioreactor culture of
marrow stromal cells, combined with the use of appropriate biodegradable fiber meshes, may constitute
a useful model to study bone formation and assess bone tissue engineering strategies in vitro
Responsive and In situ-forming chitosan scaffolds for bone tissue engineering applications : an overview of the last decade
The use of bioabsorbable polymeric scaffolds is being investigated for use in bone tissue engineering applications, as their properties can be tailored to allow them to degrade and integrate at optimal rates as bone remodelling is completed. The main goal of this review is to highlight the “intelligent” properties exhibited by chitosan scaffolds and their use in the bone tissue engineering field. To complement the fast evolution of the bone tissue engineering field, it is important to propose the use of responsive scaffolds and take advantage of bioinspired materials and their properties as emerging technologies. There is a growing interest and need for new biomaterials, such as “smart”/responsive materials with the capability to respond to changes in the in vivo environment. This review will provide an overview of strategies that can modulate bone tissue regeneration by using in situ-forming scaffolds
A liquid chromatographic method optimization for the assessment of low and high molar mass carbonyl compounds in wines.
Carbonyl compounds (CC) play an important role in beverage aroma since they may affect flavor of wines, brandies, and beers, among others
Avaliação das caracterĂsticas do solo em uma recuperação de mata ciliar no municĂpio de ouro preto d'oeste, RondĂ´nia.
Este trabalho foi realizado na bacia do rio Boa vista, localizada no municĂpio de Ouro Preto d´Oeste - RondĂ´nia, com o intuito de avaliar os componentes quĂmicos e resistĂŞncia Ă penetração do solo submetido Ă recuperação da mata ciliar trĂŞs anos apĂłs o plantio comparando com uma área ao lado de plantio convencional
Penetrating Bladder Trauma: A High Risk Factor for Associated Rectal Injury
Demographics and mechanisms were analyzed in prospectively maintained level one trauma center database 1990–2012. Among 2,693 trauma laparotomies, 113 (4.1%) presented bladder lesions; 51.3% with penetrating injuries (n=58); 41.3% (n=24) with rectal injuries, males corresponding to 95.8%, mean age 29.8 years; 79.1% with gunshot wounds and 20.9% with impalement; 91.6% arriving the emergence room awake (Glasgow 14-15), hemodynamically stable (average systolic blood pressure 119.5 mmHg); 95.8% with macroscopic hematuria; and 100% with penetrating stigmata. Physical exam was not sensitive for rectal injuries, showing only 25% positivity in patients. While 60% of intraperitoneal bladder injuries were surgically repaired, extraperitoneal ones were mainly repaired using Foley catheter alone (87.6%). Rectal injuries, intraperitoneal in 66.6% of the cases and AAST-OIS grade II in 45.8%, were treated with primary suture plus protective colostomy; 8.3% were sigmoid injuries, and 70.8% of all injuries had a minimum stool spillage. Mean injury severity score was 19; mean length of stay 10 days; 20% of complications with no death. Concomitant rectal injuries were not a determinant prognosis factor. Penetrating bladder injuries are highly associated with rectal injuries (41.3%). Heme-negative rectal examination should not preclude proctoscopy and eventually rectal surgical exploration (only 25% sensitivity)
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