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131.
Understanding near infrared light propagation in tissue is vital for designing next generation optical brain imaging devices. Monte Carlo (MC) simulations provide a controlled mechanism to characterize and evaluate contributions of diverse near infrared spectroscopy (NIRS) sensor configurations and parameters. In this study, we developed a multilayer adult digital head model under both healthy and clinical settings and assessed light‐tissue interaction through MC simulations in terms of partial differential pathlength, mean total optical pathlength, diffuse reflectance, detector light intensity and spatial sensitivity profile of optical measurements. The model incorporated four layers: scalp, skull, cerebrospinal‐fluid and cerebral cortex with and without a customizable lesion for modeling hematoma of different sizes and depths. The effect of source‐detector separation (SDS) on optical measurements' sensitivity to brain tissue was investigated. Results from 1330 separate simulations [(4 lesion volumes × 4 lesion depths for clinical +3 healthy settings) × 7 SDS × 10 simulation = 1330)] each with 100 million photons indicated that selection of SDS is critical to acquire optimal measurements from the brain and recommended SDS to be 25 to 35 mm depending on the wavelengths to obtain optical monitoring of the adult brain function. The findings here can guide the design of future NIRS probes for functional neuroimaging and clinical diagnostic systems. 相似文献
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Ekmekçigil Münire Bayraktar Meltem Akkuş Özge Gürel Aynur 《Plant Cell, Tissue and Organ Culture》2019,136(3):451-464
Plant Cell, Tissue and Organ Culture (PCTOC) - An efficient in vitro mass propagation through protocorm-like bodies (PLBs) was established in Cattleya forbesii Lindl., a commercially important... 相似文献
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S Sorrentino T Bucciarelli A Corsaro A Tosatto S Thellung V Villa ME Schininà B Maras R Galeno L Scotti F Creati A Marrone N Re A Aceto T Florio M Mazzanti 《PloS one》2012,7(7):e38314
The pathological form of prion protein (PrPSc), as other amyloidogenic proteins, causes a marked increase of membrane permeability. PrPSc extracted from infected Syrian hamster brains induces a considerable change in membrane ionic conductance, although the contribution of this interaction to the molecular mechanism of neurodegeneration process is still controversial. We previously showed that the human PrP fragment 90–231 (hPrP90–231) increases ionic conductance across artificial lipid bilayer, in a calcium-dependent manner, producing an alteration similar to that observed for PrPSc. In the present study we demonstrate that hPrP90–231, pre-incubated with 10 mM Ca++ and then re-suspended in physiological external solution increases not only membrane conductance but neurotoxicity as well. Furthermore we show the existence of a direct link between these two effects as demonstrated by a highly statistically significant correlation in several experimental conditions. A similar correlation between increased membrane conductance and cell degeneration has been observed assaying hPrP90–231 bearing pathogenic mutations (D202N and E200K). We also report that Ca++ binding to hPrP90–231 induces a conformational change based on an alteration of secondary structure characterized by loss of alpha-helix content causing hydrophobic amino acid exposure and proteinase K resistance. These features, either acquired after controlled thermal denaturation or induced by D202N and E200K mutations were previously identified as responsible for hPrP90–231 cytotoxicity. Finally, by in silico structural analysis, we propose that Ca++ binding to hPrP90–231 modifies amino acid orientation, in the same way induced by E200K mutation, thus suggesting a pathway for the structural alterations responsible of PrP neurotoxicity. 相似文献
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Glucocorticoids and cyclic AMP selectively increase hepatic lipin-1 expression, and insulin acts antagonistically 总被引:1,自引:0,他引:1
Manmontri B Sariahmetoglu M Donkor J Bou Khalil M Sundaram M Yao Z Reue K Lehner R Brindley DN 《Journal of lipid research》2008,49(5):1056-1067
Glucocorticoids (GCs) increase hepatic phosphatidate phosphatase (PAP1) activity. This is important in enhancing the liver's capacity for storing fatty acids as triacylglycerols (TAGs) that can be used subsequently for beta-oxidation or VLDL secretion. PAP1 catalyzes the conversion of phosphatidate to diacylglycerol, a key substrate for TAG and phospholipid biosynthesis. PAP1 enzymes in liver include lipin-1A and -1B (alternatively spliced isoforms) and two distinct gene products, lipin-2 and lipin-3. We determined the mechanisms by which the composite PAP1 activity is regulated using rat and mouse hepatocytes. Levels of lipin-1A and -1B mRNA were increased by dexamethasone (dex; a synthetic GC), and this resulted in increased lipin-1 synthesis, protein levels, and PAP1 activity. The stimulatory effect of dex on lipin-1 expression was enhanced by glucagon or cAMP and antagonized by insulin. Lipin-2 and lipin-3 mRNA were not increased by dex/cAMP, indicating that increased PAP1 activity is attributable specifically to enhanced lipin-1 expression. This work provides the first evidence for the differential regulation of lipin activities. Selective lipin-1 expression explains the GC and cAMP effects on increased hepatic PAP1 activity, which occurs in hepatic steatosis during starvation, diabetes, stress, and ethanol consumption. 相似文献
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Ayhan M Silistreli O Aytug Z Gorgu M Yakut M 《Plastic and reconstructive surgery》2005,115(5):1450-1451
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B Maras V Consalvi R Chiaraluce L Politi M De Rosa F Bossa R Scandurra D Barra 《European journal of biochemistry》1992,203(1-2):81-87
The complete amino acid sequence of glutamate dehydrogenase from the thermoacidophilic archaebacterium Sulfolobus solfataricus has been determined. The sequence was reconstructed by automated sequence analysis of peptides obtained after cleavage by trypsin, cyanogen bromide, Staphylococcus aureus V8 protease and pepsin. The enzyme subunit is composed of 421 amino acid residues yielding a molecular mass of 46.078 kDa. The presence of N-epsilon-methyllysine in six positions of the sequence was observed. Comparison of the sequence of glutamate dehydrogenase from S. solfataricus with the other known primary structures of the corresponding enzyme from different sources, gives an overall identity of 9.2% and shows a symmetrical evolutionary distance of this archaebacterial protein from the two groups of vertebrate on one side and eubacterial and low eucaryote enzymes on the other side. The occurrence of specific substitutions and a possible role for N-epsilon-methylation of lysine residues are discussed in view of current hypotheses on the molecular basis of thermal adaptation of proteins. 相似文献