107 research outputs found

    Schlieren textures in free-standing nematic films: evidence of biaxiality

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    Conoscopic studies reveal that the nematic phase of 4,4-( p -terphenyl)-bis\[2,3,4-tri(dodecyloxy)benzal]imine is biaxial, the biaxial angle increasing with schlieren textures exhibited by the nematic phase have been between glass plates, as well as free-standing consisting entirely of s or 2-brush disclinations, confirming an earlier suggestion that the absence of 4-brush disclinations is evidence of biaxiality. decreasing temperature. The examined. Films sandwiched films, exhibit a nematic schlieren texture

    Improving In Vitro Generated Cartilage-Carrier-Constructs by Optimizing Growth Factor Combination

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    The presented study is focused on the generation of osteochondral implants for cartilage repair, which consist of bone substitutes covered with in vitro engineered cartilage. Re-differentiation of expanded porcine cells was performed in alginate gel followed by cartilage formation in high-density cell cultures. In this work, different combinations of growth factors for the stimulation of re-differentiation and cartilage formation have been tested to improve the quality of osteochondral implants. It has been demonstrated that supplementation of the medium with growth factors has significant effects on the properties of the matrix. The addition of the growth factors IGF-I (100 ng/mL) and TGF-Ξ²1 (10 ng/mL) during the alginate culture and the absence of any growth factors during the high-density cell culture led to significantly higher GAG to DNA ratios and Young’s Moduli of the constructs compared to other combinations. The histological sections showed homogenous tissue and intensive staining for collagen type II

    Extrinsic Fluorescent Dyes as Tools for Protein Characterization

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    Noncovalent, extrinsic fluorescent dyes are applied in various fields of protein analysis, e.g. to characterize folding intermediates, measure surface hydrophobicity, and detect aggregation or fibrillation. The main underlying mechanisms, which explain the fluorescence properties of many extrinsic dyes, are solvent relaxation processes and (twisted) intramolecular charge transfer reactions, which are affected by the environment and by interactions of the dyes with proteins. In recent time, the use of extrinsic fluorescent dyes such as ANS, Bis-ANS, Nile Red, Thioflavin T and others has increased, because of their versatility, sensitivity and suitability for high-throughput screening. The intention of this review is to give an overview of available extrinsic dyes, explain their spectral properties, and show illustrative examples of their various applications in protein characterization

    Tissue engineering of functional articular cartilage: the current status

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    Osteoarthritis is a degenerative joint disease characterized by pain and disability. It involves all ages and 70% of people aged >65 have some degree of osteoarthritis. Natural cartilage repair is limited because chondrocyte density and metabolism are low and cartilage has no blood supply. The results of joint-preserving treatment protocols such as debridement, mosaicplasty, perichondrium transplantation and autologous chondrocyte implantation vary largely and the average long-term result is unsatisfactory. One reason for limited clinical success is that most treatments require new cartilage to be formed at the site of a defect. However, the mechanical conditions at such sites are unfavorable for repair of the original damaged cartilage. Therefore, it is unlikely that healthy cartilage would form at these locations. The most promising method to circumvent this problem is to engineer mechanically stable cartilage ex vivo and to implant that into the damaged tissue area. This review outlines the issues related to the composition and functionality of tissue-engineered cartilage. In particular, the focus will be on the parameters cell source, signaling molecules, scaffolds and mechanical stimulation. In addition, the current status of tissue engineering of cartilage will be discussed, with the focus on extracellular matrix content, structure and its functionality

    Tension stimulation drives tissue formation in scaffold-free systems

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    Scaffold-free systems have emerged as viable approaches for engineering load-bearing tissues. However, the tensile properties of engineered tissues have remained far below the values for native tissue. Here, by using self-assembled articular cartilage as a model to examine the effects of intermittent and continuous tension stimulation on tissue formation, we show that the application of tension alone, or in combination with matrix remodelling and synthesis agents, leads to neocartilage with tensile properties approaching those of native tissue. Implantation of tension-stimulated tissues results in neotissues that are morphologically reminiscent of native cartilage. We also show that tension stimulation can be translated to a human cell source to generate anisotropic human neocartilage with enhanced tensile properties. Tension stimulation, which results in nearly sixfold improvements in tensile properties over unstimulated controls, may allow the engineering of mechanically robust biological replacements of native tissue

    Infrared Multiple Photon Dissociation Spectroscopy of Potassiated Proline

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    The structure of proline in [proline + K](+) has been investigated in the gas phase using high level DFT and MP2 calculations and infrared photo dissociation spectroscopy with a free electron laser (FELIX). The respective FELIX spectrum of [proline + K](+) matches convincingly the calculated spectra of two structurally closely related and nearly iso-energetic zwitterionic salt bridge (SB) structures. An additional unresolved band at similar to 1725 cm(-1) matching with the characteristic CO stretching mode of charge solvation (CS) structures points toward the presence of a minor population of these conformers of proline in [proline + K](+). However, theory predicts a significant energy gap of 18.9 kJmol(-1) (B3LYP/6-311++G(2d,2p)) or 15.6 kJ mol(-1) (MP2) between the lowest CS conformer of proline and the clearly favored SB structure
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