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排序方式: 共有896条查询结果,搜索用时 15 毫秒
81.
Manuela Grimaldi Mario Scrima Cinzia Esposito Anna Ramunno Gerardino D'Errico Anna Maria D'Ursi 《生物化学与生物物理学报:生物膜》2010,1798(3):660-1426
Aβ (16-35) is the hydrophobic central core of β-amyloid peptide, the main component of plaques found in the brain tissue of Alzheimer's disease patients. Depending on the conditions present, β-amyloid peptides undergo a conformational transition from random coil or α-helical monomers, to highly toxic β-sheet oligomers and aggregate fibrils. The behavior of β-amyloid peptide at plasma membrane level has been extensively investigated, and membrane charge has been proved to be a key factor modulating its conformational properties. In the present work we probed the conformational behavior of Aβ (16-35) in response to negative charge modifications of the micelle surface. CD and NMR conformational analyses were performed in negatively charged pure SDS micelles and in zwitterionic DPC micelles “doped” with small amounts of SDS. To analyze the tendency of Aβ (16-35) to interact with these micellar systems, we performed EPR experiments on three spin-labeled analogues of Aβ (16-35), bearing the methyl 3-(2,2,5,5-tetramethyl-1-oxypyrrolinyl) methanethiolsulfonate spin label at the N-terminus, in the middle of the sequence and at the C-terminus, respectively. Our conformational data show that, by varying the negative charge of the membrane, Aβ (16-35) undergoes a conformational transition from a soluble helical-kink-helical structure, to a U-turn shaped conformation that resembles protofibril models. 相似文献
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84.
UVB-radiation-induced apoptosis in Jurkat cells: a coordinated fourier transform infrared spectroscopy-flow cytometry study 总被引:1,自引:0,他引:1
Pozzi D Grimaldi P Gaudenzi S Di Giambattista L Silvestri I Morrone S Congiu Castellano A 《Radiation research》2007,168(6):698-705
We studied the induction of apoptosis in Jurkat cells by UVB radiation (wavelength 290-320 nm) at a dose of 310 mJ/ cm2. We combined Fourier transform infrared (FTIR) spectroscopy with flow cytometry to determine whether the combination of both techniques could provide new and improved information about cell modifications. To do this, we looked for correspondences and correlations between spectroscopy and flow cytometry data and found three highly probable spectroscopic markers of apoptosis. The behavior of the wave number shift of both the Amide I beta-sheet component and the area of the 1083 cm(-1) band reproduced, with a high correlation, the behavior of the early apoptotic cell population, while the behavior of the Amide I area showed a high correlation with the early plus late apoptotic cell population. 相似文献
85.
Tettamanti G Grimaldi A Casartelli M Ambrosetti E Ponti B Congiu T Ferrarese R Rivas-Pena ML Pennacchio F Eguileor Md 《Cell and tissue research》2007,330(2):345-359
We have analyzed midgut development during the fifth larval instar in the tobacco budworm Heliothis virescens. In prepupae, the midgut formed during larval instars undergoes a complete renewal process. This drastic remodeling of the
alimentary canal involves the destruction of the old cells by programmed cell-death mechanisms (autophagy and apoptosis).
Massive proliferation and differentiation of regenerative stem cells take place at the end of the fifth instar and give rise
to a new fully functioning epithelium that is capable of digesting and absorbing nutrients and that is maintained throughout
the subsequent pupal stage. Midgut replacement in H. virescens is achieved by a balance between this active proliferation process and cell-death mechanisms and is different from similar
processes characterized in other insects.
This work was supported by FAR 2006 (University of Insubria) to G.T., by a MIUR-FIRB-COFIN grant (no. RBNE01YXA8/2004077251),
and by the Centro Grandi Attrezzature (University of Insubria). 相似文献
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Margaux Bouzin Laura Sironi Giuseppe Chirico Laura D’Alfonso Donato Inverso Piersandro Pallavicini Maddalena Collini 《Biophysical journal》2015,109(11):2246-2258
Anisotropic metallic nanoparticles have been devised as powerful potential tools for in vivo imaging, photothermal therapy, and drug delivery thanks to plasmon-enhanced absorption and scattering cross sections, ease in synthesis and functionalization, and controlled cytotoxicity. The rational design of all these applications requires the characterization of the nanoparticles intracellular trafficking pathways. In this work, we exploit live-cell time-lapse confocal reflectance microscopy and image correlation in both direct and reciprocal space to investigate the intracellular transport of branched gold nanostars (GNSs). Different transport mechanisms, spanning from pure Brownian diffusion to (sub-)ballistic superdiffusion, are revealed by temporal and spatio-temporal image correlation spectroscopy on the tens-of-seconds timescale. According to these findings, combined with numerical simulations and with a Bayesian (hidden Markov model-based) analysis of single particle tracking data, we ascribe the superdiffusive, subballistic behavior characterizing the GNSs dynamics to a two-state switching between Brownian diffusion in the cytoplasm and molecular motor-mediated active transport. For the investigation of intermittent-type transport phenomena, we derive an analytical theoretical framework for Fourier-space image correlation spectroscopy (kICS). At first, we evaluate the influence of all the dynamic and kinetic parameters (the diffusion coefficient, the drift velocity, and the transition rates between the diffusive and the active transport regimes) on simulated kICS correlation functions. Then we outline a protocol for data analysis and employ it to derive whole-cell maps for each parameter underlying the GNSs intracellular dynamics. Capable of identifying even simpler transport phenomena, whether purely diffusive or ballistic, our intermittent kICS approach allows an exhaustive investigation of the dynamics of GNSs and biological macromolecules. 相似文献
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90.
Raucci F Di Fiore MM 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(29):3268-3276
We investigated the involvement of D-Aspartic acid (D-Asp) on ovarian and testicular morphology of the green frog, Rana esculenta, and its effect on the testosterone production. The study has been performed throughout the reproductive cycle. In both ovary and testis a substantial amount of D-Asp is endogenously present and its concentration varies as function of reproduction. In the frog, D-Asp content is differently correlated with gonadal and plasmatic levels of testosterone, depending on the sex. In fact, the amount of the D-Asp is inversely linked with that of the testosterone in the ovary, while this correlation directly matched in the testis. In vivo short-term experiments, consisting of a single intra-peritoneal injection of D-Asp (2.0 μmol/g body weight), demonstrated that the enantiomer is significantly accumulated by both the ovary and testis, reaching after 3 h the highest uptake and thereafter decreasing to baseline values within 24 h. Furthermore, D-Asp influences the synthesis and/or the release of testosterone, causing a decrease of its level in the female, and an increase in the male, respectively. In vivo long-term experiments, D-Asp, chronically administered to the frogs of both sexes, enhances the maturation of both gonads, determining in the oocytes an higher accumulation of carbohydrate yolk plates in the ooplasm, and stimulating the spermatogenesis in the testis. Taken altogether, our results show that D-Asp operates differently in female and male frog gonads, indicating that it has different targets in the reproductive machinery depending on the sex. 相似文献