22 research outputs found
Oxygen Tension Is a Determinant of the Matrix-Forming Phenotype of Cultured Human Meniscal Fibrochondrocytes
Get PDFBACKGROUND: Meniscal cartilage displays a poor repair capacity, especially when injury is located in the avascular region of the tissue. Cell-based tissue engineering strategies to generate functional meniscus substitutes is a promising approach to treat meniscus injuries. Meniscus fibrochondrocytes (MFC) can be used in this approach. However, MFC are unable to retain their phenotype when expanded in culture. In this study, we explored the effect of oxygen tension on MFC expansion and on their matrix-forming phenotype. METHODOLOGY/PRINCIPAL FINDINGS: MFC were isolated from human menisci followed by basic fibroblast growth factor (FGF-2) mediated cell expansion in monolayer culture under normoxia (21%O(2)) or hypoxia (3%O(2)). Normoxia and hypoxia expanded MFC were seeded on to a collagen scaffold. The MFC seeded scaffolds (constructs) were cultured in a serum free chondrogenic medium for 3 weeks under normoxia and hypoxia. Constructs containing normoxia-expanded MFC were subsequently cultured under normoxia while those formed from hypoxia-expanded MFC were subsequently cultured under hypoxia. After 3 weeks of in vitro culture, the constructs were assessed biochemically, histologically and for gene expression via real-time reverse transcription-PCR assays. The results showed that constructs under normoxia produced a matrix with enhanced mRNA ratio (3.5-fold higher; p<0.001) of collagen type II to I. This was confirmed by enhanced deposition of collagen II using immuno-histochemistry. Furthermore, the constructs under hypoxia produced a matrix with higher mRNA ratio of aggrecan to versican (3.5-fold, p<0.05). However, both constructs had the same capacity to produce a glycosaminoglycan (GAG) -specific extracellular matrix. CONCLUSIONS: Our data provide evidence that oxygen tension is a key player in determining the matrix phenotype of cultured MFC. These findings suggest that the use of normal and low oxygen tension during MFC expansion and subsequent neo-tissue formation cultures may be important in engineering different regions of the meniscus
Tension-Compression Loading with Chemical Stimulation Results in Additive Increases to Functional Properties of Anatomic Meniscal Constructs
Get PDFObjective: This study aimed to improve the functional properties of anatomically-shaped meniscus constructs through simultaneous tension and compression mechanical stimulation in conjunction with chemical stimulation. Methods: Scaffoldless meniscal constructs were subjected to simultaneous tension and compressive stimulation and chemical stimulation. The temporal aspect of mechanical loadingwas studied by employing two separate five day stimulation periods. Chemical stimulation consisted of the application of a catabolic GAG-depleting enzyme, chondroitinase ABC (C-ABC), and an anabolic growth factor, TGF-b1. Mechanical and chemical stimulation combinations were studied through a full-factorial experimental design and assessed for histological, biochemical, and biomechanical properties following 4 wks of culture. Results: Mechanical loading applied from days 10–14 resulted in significant increases in compressive, tensile, and biochemical properties of meniscal constructs. When mechanical and chemical stimuliwere combined significant additive increases in collagen per wet weight (4-fold), compressive instantaneous (3-fold) and relaxation (2-fold) moduli, and tensile moduli in the circumferential (4-fold) and radial (6-fold) directions were obtained. Conclusions: This study demonstrates that a stimulation regimen of simultaneous tension and compression mechanical stimulation, C-ABC, and TGF-b1 is able to create anatomic meniscus constructs replicating the compressive mechanica
Telegram, 1932 May 22, New York, to Amelia Earhart, Londonderry
No full textClyde Pangborn telegraph to Amelia Earhart, “Saw your name in the paper, congratulations,” May 22, 193
Texture and Flavor Characteristics of Beverages Containing Commercial Thickening Agents for Dysphagia Diets
No full text
Flavor expectation: The effect of assuming homogeneity on drink perception
No full textHere, we investigate whether the expectation that a drink tastes consistent across mouthfuls influences reported taste. A paradigm was developed to prompt the expectation that drink stimuli tasted identical to each other. Participants sipped two drinks and indicated whether they tasted the same. In some trials, the drinks appeared to be poured from the same jug, prompting the homogeneous taste expectation. These 'same-jug' drink pairs were reported more similar than 'different-jug' drink pairs, where the drinks were seen to be poured from different jugs, even when sweetness differed. This effect did not occur when the difference in sweetness between the drinks was too great. This suggests that expectancy effects act to smooth out variation in taste within a window of taste differences, until differences become perceptually noticeable. The expectation effect also dwindled over the course of the experiment, suggesting that expectations of similarity were updated with increasing experience of incongruous same-jug drinks. We conclude that flavor perception is best considered in terms of windows of flavor variation within which sensation changes to be more in line with expectations derived from past and current consumption experiences.</p
Clinical characteristics of patients with systemic lupus erythematosus showing a false-positive result of syphilis screening
No full textInvestigation of human flavor perception and discrimination of the fat content in food using DR A-Not A and 3-AFC methods
No full text
