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91.
Justine Dionne Thierry Lefèvre Michèle Auger 《International journal of molecular sciences》2016,17(8)
To plentifully benefit from its properties (mechanical, optical, biological) and its potential to manufacture green materials, the structure of spider silk has to be known accurately. To this aim, the major ampullate (MA) silk of Araneus diadematus (AD) and Nephila clavipes (NC) has been compared quantitatively in the liquid and fiber states using Raman spectromicroscopy. The data show that the spidroin conformations of the two dopes are indistinguishable despite their specific amino acid composition. This result suggests that GlyGlyX and GlyProGlyXX amino acid motifs (X = Leu, Glu, Tyr, Ser, etc.) are conformationally equivalent due to the chain flexibility in the aqueous environment. Species-related sequence specificity is expressed more extensively in the fiber: the β-sheet content is lower and width of the orientation distribution of the carbonyl groups is broader for AD (29% and 58°, respectively) as compared to NC (37% and 51°, respectively). β-Sheet content values are close to the proportion of polyalanine segments, suggesting that β-sheet formation is mainly dictated by the spidroin sequence. The extent of molecular alignment seems to be related to the presence of proline (Pro) that may decrease conformational flexibility and inhibit chain extension and alignment upon drawing. It appears that besides the presence of Pro, secondary structure and molecular orientation contribute to the different mechanical properties of MA threads. 相似文献
92.
Matthieu Pérard Justine Le Clerc Fleur Meary Fabienne Pérez Sylvie Tricot-Doleux Pascal Pellen-Mussi 《Journal of materials science. Materials in medicine》2013,24(6):1527-1534
The primary objective of this study was to assess the biological effects of a new dentine substitute based on Ca3SiO5 (Biodentine?) for use in pulp-capping treatment, on pseudo-odontoblastic (MDPC-23) and pulp (Od-21) cells. The secondary objective was to evaluate the effects of Biodentine and mineral trioxide aggregate (MTA) on gene expression in cultured spheroids. We used the acid phosphatase assay to compare the biocompatibility of Biodentine and MTA. Cell differentiation was investigated by RT-qPCR. We investigated the expression of genes involved in odontogenic differentiation (Runx2), matrix secretion (Col1a1, Spp1) and mineralisation (Alp). ANOVA and PLSD tests were used for data analysis. MDPC-23 cells cultured in the presence of MTA had higher levels of viability than those cultured in the presence of Biodentine and control cells on day 7 (P = 0.0065 and P = 0.0126, respectively). For Od-21 cells, proliferation rates on day 7 were significantly lower in the presence of Biodentine or MTA than for control (P < 0.0001). Col1a1 expression levels were slightly lower in cells cultured in the presence of MTA than in those cultured in the presence of Biodentine and in control cells. Biodentine and MTA may modify the proliferation of pulp cell lines. Their effects may fluctuate over time, depending on the cell line considered. The observed similarity between Biodentine and MTA validates the indication for direct pulp-capping claimed by the manufacturers. 相似文献
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96.
Justine M. Webster Michael S. Sagmeister Chloe G. Fenton Alex P. Seabright Yu-Chiang Lai Simon W. Jones Andrew Filer Mark S. Cooper Gareth G. Lavery Karim Raza Ramon Langen Rowan S. Hardy 《International journal of molecular sciences》2021,22(15)
Glucocorticoids provide indispensable anti-inflammatory therapies. However, metabolic adverse effects including muscle wasting restrict their use. The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) modulates peripheral glucocorticoid responses through pre-receptor metabolism. This study investigates how 11β-HSD1 influences skeletal muscle responses to glucocorticoid therapy for chronic inflammation. We assessed human skeletal muscle biopsies from patients with rheumatoid arthritis and osteoarthritis for 11β-HSD1 activity ex vivo. Using the TNF-α-transgenic mouse model (TNF-tg) of chronic inflammation, we examined the effects of corticosterone treatment and 11β-HSD1 global knock-out (11βKO) on skeletal muscle, measuring anti-inflammatory gene expression, muscle weights, fiber size distribution, and catabolic pathways. Muscle 11β-HSD1 activity was elevated in patients with rheumatoid arthritis and correlated with inflammation markers. In murine skeletal muscle, glucocorticoid administration suppressed IL6 expression in TNF-tg mice but not in TNF-tg11βKO mice. TNF-tg mice exhibited reductions in muscle weight and fiber size with glucocorticoid therapy. In contrast, TNF-tg11βKO mice were protected against glucocorticoid-induced muscle atrophy. Glucocorticoid-mediated activation of catabolic mediators (FoxO1, Trim63) was also diminished in TNF-tg11βKO compared to TNF-tg mice. In summary, 11β-HSD1 knock-out prevents muscle atrophy associated with glucocorticoid therapy in a model of chronic inflammation. Targeting 11β-HSD1 may offer a strategy to refine the safety of glucocorticoids. 相似文献
97.
Measured bit-error-rate performance is reported for a wavelength-division-multiplexed subcarrier-multiplexed transmission experiment. Six digital channels were carried over two wavelengths in the 1.5 mu m wavelength region and amplified using a semiconductor laser amplifier which gave a 12 dB increase in tolerable path loss with no noticeable penalty.<> 相似文献
98.
Previously reported laboratory methods for measuring the rate of 14CO2 release from an aqueous sample require a series of replicate growth flasks. At chosen times, some of these are sacrificed in order to quantitate the 14CO2 released. The method presented here requires only one culture flask containing 200 ml of sample with labeled substrate, and one control-replacement flask containing 200 ml of sterile sample with labeled substrate. At each sampling time, of the liquid and headspace gas is removed from the modified 500 ml Erlenmeyer culture flask for 14CO2 recovery. This method was used to study the mineralization of labeled amino acids, starch, n-hexadecane and anthracene by microorganisms in river water, and of n-hexadecane and n-hexadecanoic acid by microorganisms in sewage effluent. 相似文献
99.
100.
D. G. Westlake S. T. Ockers M. H. Mueller K. D. Anderson 《Metallurgical and Materials Transactions B》1972,3(7):1709-1710
Tetragonal V4H3 was examined by the Debye-Scherrer technique and by X-ray diffractometry at temperatures below 300 K. Two structural transitions
were indicated. The observable changes in metal-metal atom distances may be manifestations of hydrogen ordering. 相似文献