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End date: 2019 × Start date: 2019 × DDC: 570 × Type: Text × Publisher: Hoboken, NJ : Wiley ×

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Now showing 1 - 5 of 5
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    Photoactivatable Hsp47: A tool to control and regulate collagen secretion & assembly
    (Hoboken, NJ : Wiley, 2018) Khan, Essak; Sankaran, Shrikrishnan; Paez, Julieta; Muth, Christina; Han, Mitchell; Del Campo, Aránzazu
    Collagen is the most abundant structural protein in mammals and is crucial for the mechanical integrity of tissues. Hsp47, an endoplasmic reticulum resident collagen-specific chaperone, is involved in collagen biosynthesis and plays a fundamental role in the folding, stability, and intracellular transport of procollagen triple helices. This work reports on a photoactivatable derivative of Hsp47 that allows regulation of collagen biosynthesis within mammalian cells using light. Photoactivatable Hsp47 contains a non-natural light-responsive tyrosine (o-nitro benzyl tyrosine (ONBY)) at Tyr383 position of the protein sequence. This mutation renders Hsp47 inactive toward collagen binding. The inactive, photoactivatable protein is easily uptaken by cells within a few minutes of incubation, and accumulated at the endoplasmic reticulum via retrograde KDEL receptor-mediated uptake. Upon light exposure, the photoactivatable Hsp47 turns into functional Hsp47 in situ. The increased intracellular concentration of Hsp47 results in stimulated secretion of collagen. The ability to promote collagen synthesis on demand, with spatiotemporal resolution, and in diseased state cells is demonstrated in vitro. It is envisioned that photoactivatable Hsp47 allows unprecedented fundamental studies of collagen biosynthesis, matrix biology, and inspires new therapeutic concepts in biomedicine and tissue regeneration.
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    Surface structure influences contact killing of bacteria by copper
    (Hoboken, NJ : Wiley, 2014) Zeiger, Marco; Solioz, Marc; Edongué, Hervais; Arzt, Eduard; Schneider, Andreas S.
    Copper kills bacteria rapidly by a mechanism that is not yet fully resolved. The antibacterial property of copper has raised interest in its use in hospitals, in place of plastic or stainless steel. On the latter surfaces, bacteria can survive for days or even weeks. Copper surfaces could thus provide a powerful accessory measure to curb nosocomial infections. We here investigated the effect of the copper surface structure on the efficiency of contact killing of Escherichia coli, an aspect which so far has received very little attention. It was shown that electroplated copper surfaces killed bacteria more rapidly than either polished copper or native rolled copper. The release of ionic copper was also more rapid from electroplated copper compared to the other materials. Scanning electron microscopy revealed that the bacteria nudged into the grooves between the copper grains of deposited copper. The findings suggest that, in terms of contact killing, more efficient copper surfaces can be engineered.
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    A correlative analysis of gold nanoparticles internalized by A549 cells
    (Hoboken, NJ : Wiley, 2014) Böse, Katharina; Koch, Marcus; Cavelius, Christian; Kiemer, Alexandra K.; Kraegeloh, Annette
    Fluorescently labeled nanoparticles are widely used to investigate nanoparticle cell interactions by fluorescence microscopy. Owing to limited lateral and axial resolution, nanostructures (<100 nm) cannot be resolved by conventional light micro­scopy techniques. Especially after uptake into cells, a common fate of the fluorescence label and the particle core cannot be taken for granted. In this study, a correlative approach is presented to image fluorescently labeled gold nanoparticles inside whole cells by correlative light and electron microscopy (CLEM). This approach allows for detection of the fluorescently labeled particle shell as well as for the gold core in one sample. In this setup, A549 cells are exposed to 8 nm Atto 647N-labeled gold nanoparticles (3.3 × 109 particles mL−1, 0.02 μg Au mL−1) for 5 h and are subsequently imaged by confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Eight fluorescence signals located at different intracellular positions are further analyzed by TEM. Five of the eight fluorescence spots are correlated with isolated or agglomerated gold nanoparticles. Three fluorescence signals could not be related to the presence of gold, indicating a loss of the particle shell.
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    Adhesion characteristics of PDMS surfaces during repeated pull-off force measurements
    (Hoboken, NJ : Wiley, 2010) Kroner, Elmar; Arzt, Eduard; Maboudian, Roya
    To mimic the adhesive effects of gecko toes, artificial surfaces have been manufactured recently using polydimethylsiloxanes (PDMS). However, the effects of repeated contacts on the adhesive properties remain largely unexplored. In this paper we report on the effect of repeated pull-off force measurements on the adhesion behavior of PDMS (polymer kit Sylgard 184, Dow Corning) tested with a borosilicate glass probe. A decrease in pull-off force with increase in number of test cycles is found until a plateau is reached. The initial value and the rate of change in pull-off force strongly depend on the sample preparation procedure, including curing time and cross-linking. It is proposed that the behavior is due to steady coverage of the probe with free oligomers. The results are crucial for developing reusable, durable, and residue-free bioinspired adhesives.
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    The Caveolin-3 G56S sequence variant of unknown significance: Muscle biopsy findings and functional cell biological analysis
    (Hoboken, NJ : Wiley, 2016) Brauers, Eva; Roos, Andreas; Kollipara, Laxmikanth; Zahedi, René P.; Beckmann, Alf; Mohanadas, Nilane; Bauer, Hartmut; Häusler, Martin; Thoma, Stéphanie; Kress, Wolfram; Senderek, Jan; Weis, Joachim
    Purpose: In the era of next-generation sequencing, we are increasingly confronted with se- quence variants of unknown significance. This phenomenon is also known for variations in Caveolin-3 and can complicate the molecular diagnosis of the disease. Here, we aimed to study the ambiguous character of the G56S Caveolin-3 variant. Experimental design: A comprehensive approach combining genetic and morphological stud- ies of muscle derived from carriers of the G56S Caveolin-3 variant were carried out and linked to biochemical assays (including phosphoblot studies and proteome profiling) and morphological investigations of cultured myoblasts. Results: Muscles showed moderate chronic myopathic changes in all carriers of the variant. Myogenic RCMH cells expressing the G56S Caveolin-3 protein presented irregular Caveolin-3 deposits within the Golgi in addition to a regular localization of the protein to the plasma mem- brane. This result was associated with abnormal findings on the ultra-structural level. Phos- phoblot studies revealed that G56S affects EGFR-signaling. Proteomic profiling demonstrated alterations in levels of physiologically relevant proteins which are indicative for antagonization of G56S Caveolin-3 expression. Remarkably, some proteomic alterations were enhanced by osmotic/mechanical stress. Conclusions and clinical relevance: Our studies suggest that G56S might influence the mani- festation of myopathic changes upon the presence of additional cellular stress burden. Results of our studies moreover improve the current understanding of (genetic) causes of myopathic disorders classified as caveolinopathies.