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71.
Decellularized colorectal cancer matrix as bioactive microenvironment for in vitro 3D cancer research 下载免费PDF全文
72.
Jan Buchholz Jan Krieger Claudio Bruschini Samuel Burri Andrei Ardelean Edoardo Charbon Jörg Langowski 《Biophysical journal》2018,114(10):2455-2464
Photon-counting sensors based on standard complementary metal-oxide-semiconductor single-photon avalanche diodes (SPADs) represent an emerging class of imagers that enable the counting and/or timing of single photons at zero readout noise (better than high-speed electron-multiplying charge-coupling devices) and over large arrays. They have seen substantial progress over the last 15 years, increasing their spatial resolution, timing accuracy, and sensitivity while reducing spurious signals such as afterpulsing and dark counts. They are increasingly being applied for time-resolved applications with the added advantage of enabling real-time options such as autocorrelation. We report in this study on the use of such a state-of-the-art 512 × 128 SPAD array, capable of a time resolution of 10?5–10?6 s for full frames while retaining acceptable photosensitivity thanks to the use of dedicated microlenses, in a selective plane illumination-fluorescence correlation spectroscopy setup. The latter allows us to perform thousands of fluorescence-correlation spectroscopy measurements simultaneously in a two-dimensional slice of the sample. This high-speed SPAD imager enables the measurement of molecular motion of small fluorescent particles such as single chemical dye molecules. Inhomogeneities in the molecular detection efficiency were compensated for by means of a global fit of the auto- and cross-correlation curves, which also made a calibration-free measurement of various samples possible. The afterpulsing effect could also be mitigated, making the measurement of the diffusion of Alexa-488 possible, and the overall result quality was further improved by spatial binning. The particle concentrations in the focus tend to be overestimated by a factor of 1.7 compared to a confocal setup; a calibration is thus required if absolute concentrations need to be measured. The first high-speed selective plane illumination-fluorescence correlation spectroscopy in vivo measurements to our knowledge were also recorded: although two-component fit models could not be employed because of noise, the diffusion of eGFP oligomers in HeLa cells could be measured. Sensitivity and noise will be further improved in the next generation of SPAD-based widefield sensors, which are currently under testing. 相似文献
73.
Giuseppe Torzillo Paola Accolla Edoardo Pinzani Jiři Masojidek 《Journal of applied phycology》1996,8(4-5):283-291
A chlorophyll fluorescence technique was applied to anin situ study on the effects of low temperature and high light stresses onSpirulina cultures grown outdoors in controlled tubular photobioreactors at high (1.1 g L–1) and low (0.44 g L–1) biomass concentrations. Diurnal changes in PSII photochemistry (F
v/F
m) after 15 min of darkness, or in the light (dF/F
m), and non-photochemical (qN) quenching were measured using a portable, pulse-amplitude-modulated fluorometer. The depression of theF
v/F
m ratio ofSpirulina cultures grown outdoors at 25°C (i.e. 10°C below optimum for growth) and 0.44 g L–1, reached 30% at the middle of the day. At the same time of the day thedF/F
m ratio showed a reduction of up to 52%. The depression of bothF
v/F
m anddF/F
m was lower in the cultures grown at 1.1 g L–1. Photoinhibition reduced the daily productivity of the culture grown at 0.44 g L–1 and 25°C by 33% with respect to that grown at 35°C. Changes in the growth yields of the cultures grown under different temperatures and growth rates correlate well with analogous changes in photon yield (dF/F
m). Simple measurements of photochemical yield (F
v/F
m) can be used to test the physiological status ofSpirulina cultures. The results indicate that the saturating pulse fluorescence technique, when usedin situ, is a powerful tool for assessment of the photosynthetic characteristics of outdoor cultures ofSpirulina. 相似文献
74.
75.
76.
Rousso Benny Zuse Bertone Edoardo Stewart Rodney A. Hughes Sara P. Hobson Peter Hamilton David P. 《Hydrobiologia》2022,849(6):1453-1469
Hydrobiologia - The objective of this study was to identify correlations between environmental variables and cyanobacterial diversity, succession and dominance in three Australian water supply... 相似文献
77.
In a previous paper we have introduced a phenomenological model of cell metabolism and of the cell cycle to simulate the behavior of large tumor cell populations (Chignola and Milotti 2005 Phys. Biol. 2 8). Here we describe a refined and extended version of the model that includes some of the complex interactions between cells and their surrounding environment. The present version takes into consideration several additional energy-consuming biochemical pathways such as protein and DNA synthesis, the tuning of extracellular pH and of the cell membrane potential. The control of the cell cycle, which was previously modeled by means of ad hoc thresholds, has been directly addressed here by considering checkpoints from proteins that act as targets for phosphorylation on multiple sites. As simulated cells grow, they can now modify the chemical composition of the surrounding environment which in turn acts as a feedback mechanism to tune cell metabolism and hence cell proliferation: in this way we obtain growth curves that match quite well those observed in vitro with human leukemia cell lines. The model is strongly constrained and returns results that can be directly compared with actual experiments, because it uses parameter values in narrow ranges estimated from experimental data, and in perspective we hope to utilize it to develop in silico studies of the growth of very large tumor cell populations (10(6) cells or more) and to support experimental research. In particular, the program is used here to make predictions on the behavior of cells grown in a glucose-poor medium: these predictions are confirmed by experimental observation. 相似文献
78.
Ihssane Bouybayoune Susanna Mantovani Federico Del Gallo Ilaria Bertani Elena Restelli Liliana Comerio Laura Tapella Francesca Baracchi Natalia Fernández-Borges Michela Mangieri Cinzia Bisighini Galina V. Beznoussenko Alessandra Paladini Claudia Balducci Edoardo Micotti Gianluigi Forloni Joaquín Castilla Fabio Fiordaliso Fabrizio Tagliavini Luca Imeri Roberto Chiesa 《PLoS pathogens》2015,11(4)
Fatal familial insomnia (FFI) and a genetic form of Creutzfeldt-Jakob disease (CJD178) are clinically different prion disorders linked to the D178N prion protein (PrP) mutation. The disease phenotype is determined by the 129 M/V polymorphism on the mutant allele, which is thought to influence D178N PrP misfolding, leading to the formation of distinctive prion strains with specific neurotoxic properties. However, the mechanism by which misfolded variants of mutant PrP cause different diseases is not known. We generated transgenic (Tg) mice expressing the mouse PrP homolog of the FFI mutation. These mice synthesize a misfolded form of mutant PrP in their brains and develop a neurological illness with severe sleep disruption, highly reminiscent of FFI and different from that of analogously generated Tg(CJD) mice modeling CJD178. No prion infectivity was detectable in Tg(FFI) and Tg(CJD) brains by bioassay or protein misfolding cyclic amplification, indicating that mutant PrP has disease-encoding properties that do not depend on its ability to propagate its misfolded conformation. Tg(FFI) and Tg(CJD) neurons have different patterns of intracellular PrP accumulation associated with distinct morphological abnormalities of the endoplasmic reticulum and Golgi, suggesting that mutation-specific alterations of secretory transport may contribute to the disease phenotype. 相似文献
79.
4‐Cyano‐α‐methyl‐l‐phenylalanine as a Spectroscopic Marker for the Investigation of PeptaibioticMembrane Interactions 下载免费PDF全文
Marta De Zotti Sara Bobone Annalisa Bortolotti Edoardo Longo Barbara Biondi Cristina Peggion Fernando Formaggio Claudio Toniolo Andrea Dalla Bona Bernard Kaptein Lorenzo Stella 《化学与生物多样性》2015,12(4):513-527
Two analogs of the ten‐amino acid residue, membrane‐active lipopeptaibiotic trichogin GA IV, mono‐labeled with 4‐cyano‐α‐methyl‐L ‐phenylalanine, a potentially useful fluorescence and IR absorption probe of the local microenvironment, were synthesized by the solid‐phase methodology and conformationally characterized. The single modification was incorporated either at the N‐terminus (position 1) or near the C‐terminus (position 8) of the peptide main chain. In both cases, the replaced amino acid was the equally helicogenic α‐aminoisobutyric acid (Aib) residue. We performed a solution conformational analysis by use of FT‐IR absorption, CD, and 2D‐NMR spectroscopies. The results indicate that both labeled analogs essentially maintain the overall helical propensity of the naturally occurring lipopeptaibiotic. Peptide? membrane interactions were assessed by fluorescence and ATR‐IR absorption techniques. Analogies and differences between the two peptides were highlighted. Taken together, our data confirm literature results that some of the spectroscopic parameters of the 4‐cyanobenzyl chromophore are sensitive markers of the local microenvironment. 相似文献
80.
Ornella Piazza Simona Cotena Edoardo De Robertis Ferdinando Caranci Rosalba Tufano 《Neurochemical research》2009,34(7):1289-1292
The pathogenesis of sepsis associated encephalopathy (SAE) is not yet clear: the blood–brain barrier (BBB) disruption has
been indicated among the possible causative mechanisms. S100B, a calcium binding protein, originates in the central nervous
system but it can be also produced by extra-cerebral sources; it is passively released from damaged glial cells and neurons;
it has limited passage through the BBB. We aimed to demonstrate BBB damage as part of the pathogenesis of SAE by cerebral
spinal fluid (CSF) and serum S100B measurements and by magnetic resonance imaging (MRI). This paper describes four septic
patients in whom SAE was clinically evident, who underwent MRI and S100B measurement. We have not found any evidence of CSF-S100B
increase. Serum S100B increase was found in three out of four patients. MRI did not identify images attributable to BBB disruption
but vasogenic edema, probably caused by an alteration of autoregulation, was diagnosed. S100B does not increase in CSF of
septic patients; S100B increase in serum may be due to extracerebral sources and does not prove any injury of BBB. MRI can
exclude other cerebral pathologies causing brain dysfunction but is not specific of SAE. BBB damage may be numbered among
the contributors of SAE, which aetiology is certainly multifactorial: an interplay between the toxic mediators involved in
sepsis and the indirect effects of hyperthermia, hypossia and hypoperfusion. 相似文献