排序方式: 共有137条查询结果,搜索用时 19 毫秒
91.
Thakur M Mergel K Weng A Frech S Gilabert-Oriol R Bachran D Melzig MF Fuchs H 《Biosensors & bioelectronics》2012,35(1):503-506
This work describes the application of an impedance-based measurement for the real time evaluation of targeted tumor therapies in cell culture (HeLa cells). We used a treatment procedure that is well established in cells and mice. Therein, tumor cells are treated with a combination of an epidermal growth factor-based targeted toxin named SE and particular plant glycosides called saponins. In the present study HeLa cells were seeded in different numbers onto interdigitated electrode structures integrated into the bottom of a 96 well plate. The cells were treated with SE in the presence and absence of the saponin SpnS-1 (isolated from Saponaria officinalis roots). The impedance was directly correlated with the viability of the cells. As expected from known end point measurements, a concentration dependent enhancement of toxicity was observed; however, with the impedance measurement we were for the first time able to trace the temporal changes of cell death during the combination treatment. This substantially added to the understanding of initial cellular mechanisms in the augmentation of the toxicity of targeted toxins by saponins and indicated the superiority of real time monitoring over end point assays. The method is less labor intensive and label-free with ease of monitoring the effects at each time point. 相似文献
92.
Mayank Bhagat Chitresh Bhushan Goutam Saha Shinsuke Shimjo Katsumi Watanabe Joydeep Bhattacharya 《PloS one》2009,4(9)
Background
Photosensitive epilepsy is a type of reflexive epilepsy triggered by various visual stimuli including colourful ones. Despite the ubiquitous presence of colorful displays, brain responses against different colour combinations are not properly studied.Methodology/Principal Findings
Here, we studied the photosensitivity of the human brain against three types of chromatic flickering stimuli by recording neuromagnetic brain responses (magnetoencephalogram, MEG) from nine adult controls, an unmedicated patient, a medicated patient, and two controls age-matched with patients. Dynamical complexities of MEG signals were investigated by a family of wavelet entropies. Wavelet entropy is a newly proposed measure to characterize large scale brain responses, which quantifies the degree of order/disorder associated with a multi-frequency signal response. In particular, we found that as compared to the unmedicated patient, controls showed significantly larger wavelet entropy values. We also found that Renyi entropy is the most powerful feature for the participant classification. Finally, we also demonstrated the effect of combinational chromatic sensitivity on the underlying order/disorder in MEG signals.Conclusions/Significance
Our results suggest that when perturbed by potentially epileptic-triggering stimulus, healthy human brain manages to maintain a non-deterministic, possibly nonlinear state, with high degree of disorder, but an epileptic brain represents a highly ordered state which making it prone to hyper-excitation. Further, certain colour combination was found to be more threatening than other combinations. 相似文献93.
Kensara OA Wooton SA Phillips DI Patel M Hoffman DJ Jackson AA Elia M;Hertfordshire Study Group 《American journal of physiology. Endocrinology and metabolism》2006,291(2):E365-E371
The effect of fetal programming on intermediary metabolism is uncertain. Therefore, we examined whether fetal programming affects oxidative and nonoxidative macronutrient metabolism and the prevalence of the metabolic syndrome in adult life. Healthy older men, aged 64-72 years, with either a lower birth weight (LBW, or=75th %ile; n = 13) had measurements of 1) net oxidative metabolism using indirect calorimetry before and for 6 h after a mixed meal (3,720 kJ) and 2) postprandial oxidation of exogenous [13C]palmitic acid. Body composition was measured using dual-energy X-ray absorptiometry. After adjustment for current weight and height, the LBW group had a lower resting energy expenditure (REE) in the preprandial (4.01 vs. 4.54 kJ/min, P = 0.015) and postprandial state (4.60 vs. 5.20 kJ/min, P = 0.004), and less fat-free mass than the HBW group. The BW category was a significant, independent, and better predictor of REE than weight plus height. There were no significant differences between groups in net oxidative and nonoxidative macronutrient (protein, fat, carbohydrate) metabolism (or of exogenous [13C]palmitate) or in the prevalence of the metabolic syndrome, which was present almost twice as commonly in the LBW than in the HBW group. The study suggests that fetal programming affects both pre- and postprandial EE in older life by mechanisms that are at least partly related to the mass of the fat-free body. BW was found to be a significant predictor of REE that was independent of adult weight plus height. 相似文献
94.
Friedreich's ataxia (FRDA) is a common hereditary degenerative neuro-muscular disorder caused by expansions of the (GAA)n repeat in the first intron of the frataxin gene. The expanded repeats from parents frequently undergo further significant length changes as they are passed on to progeny. Expanded repeats also show an age-dependent instability in somatic cells, albeit on a smaller scale than during intergenerational transmissions. Here we studied the effects of (GAA)n repeats of varying lengths and orientations on the episomal DNA replication in mammalian cells. We have recently shown that the very first round of the transfected DNA replication occurs in the lack of the mature chromatin, does not depend on the episomal replication origin and initiates at multiple single-stranded regions of plasmid DNA. We now found that expanded GAA repeats severely block this first replication round post plasmid transfection, while the subsequent replication cycles are only mildly affected. The fact that GAA repeats affect various replication modes in a different way might shed light on their differential expansions characteristic for FRDA. 相似文献
95.
Explicit-duration hidden Markov model inference of UP-DOWN states from continuous signals 总被引:1,自引:0,他引:1
Neocortical neurons show UP-DOWN state (UDS) oscillations under a variety of conditions. These UDS have been extensively studied because of the insight they can yield into the functioning of cortical networks, and their proposed role in putative memory formation. A key element in these studies is determining the precise duration and timing of the UDS. These states are typically determined from the membrane potential of one or a small number of cells, which is often not sufficient to reliably estimate the state of an ensemble of neocortical neurons. The local field potential (LFP) provides an attractive method for determining the state of a patch of cortex with high spatio-temporal resolution; however current methods for inferring UDS from LFP signals lack the robustness and flexibility to be applicable when UDS properties may vary substantially within and across experiments. Here we present an explicit-duration hidden Markov model (EDHMM) framework that is sufficiently general to allow statistically principled inference of UDS from different types of signals (membrane potential, LFP, EEG), combinations of signals (e.g., multichannel LFP recordings) and signal features over long recordings where substantial non-stationarities are present. Using cortical LFPs recorded from urethane-anesthetized mice, we demonstrate that the proposed method allows robust inference of UDS. To illustrate the flexibility of the algorithm we show that it performs well on EEG recordings as well. We then validate these results using simultaneous recordings of the LFP and membrane potential (MP) of nearby cortical neurons, showing that our method offers significant improvements over standard methods. These results could be useful for determining functional connectivity of different brain regions, as well as understanding network dynamics. 相似文献
96.
97.
Comparative functional analysis of three abiotic stress-inducible promoters in transgenic rice 总被引:2,自引:0,他引:2
To identify minimal effective promoters for driving abiotic stress-inducible transgene expression in rice, we selected promoter
elements of three stress-responsive genes, viz. rab16A coding for dehydrin, OsABA2 coding for zeaxanthin epoxidase, and a gene coding for a hypothetical protein (HP1) based on the presence of ABA-, salt-
and drought-responsive cis-acting elements. These were translationally fused to the gusA reporter gene and introduced into rice to study their effect on heterologous gene expression. The OsABA2 promoter was found
to be the most effective and desirable promoter among the three in terms of driving a low constitutive transgene expression
under normal conditions and high induction in response to ABA, salt and drought stress, the highest being a 12-fold induction
in response to ABA. The rab16A and HP1 promoters resulted in high levels of constitutive expression. While induction of GUS
activity was generally two- to threefold for all the treatments in roots for both the promoters, induction in leaves was generally
insignificant, the exceptions being rab16A in response to continuous salt stress and HP1 in response to water deficit. It
was also observed that the three promoters, in general, resulted in lower constitutive expression, but higher induction in
roots as compared to leaves.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
R. Wu: Deceased.
This paper is humbly dedicated to the memory of Professor Ray Wu. 相似文献
98.
Krishna Mayank Winternitz Jamie Garkoti Satish Chandra Penuelas Josep 《Journal of plant research》2021,134(4):753-764
Journal of Plant Research - Traits are the primary attributes that distinguish a species niche. Species and higher taxa are part of a structured phylogeny, and variation in plant traits depends on... 相似文献
99.
Melissa A. Pinard Justin J. Kurian Mayank Aggarwal Mavis Agbandje-McKenna Robert McKenna 《Acta Crystallographica. Section F, Structural Biology Communications》2016,72(7):573-577
Cryoannealing has been demonstrated to improve the diffraction quality and resolution of crystals of the β‐carbonic anhydrase psCA3 concomitant with a change in space group. After initial flash‐cooling in a liquid‐nitrogen cryostream an X‐ray diffraction data set from a psCA3 crystal was indexed in space group P21212 and was scaled to 2.6 Å resolution, but subsequent cryoannealing studies revealed induced protein rearrangements in the crystal contacts, which transformed the space group to I222, with a corresponding improvement of 0.7 Å in resolution. Although the change in diffraction resolution was significant, only minor changes in the psCA3 structure, which retained its catalytic `open' conformation, were observed. These findings demonstrate that cryoannealing can be successfully utilized to induce higher diffraction‐quality crystals while maintaining enzymatically relevant conformations and may be useful as an experimental tool for structural studies of other enzymes where the initial diffraction quality is poor. 相似文献
100.
Mayank Anand Gururani Jelli Venkatesh Ritesh Ghosh Reto Jörg Strasser Lakshmi Narayanan Ponpandian 《Plant biosystems》2018,152(5):945-952
In this study, we evaluated the effect of osmotic stress on photosynthetic machinery of Arabidopsis plants expressing a gene encoding small basic intrinsic protein (SIP1) isolated from Solanum tuberosum. Intact leaves of SIP Arabidopsis plants were exposed to 15% polyethylene glycol (PEG) solution and fast Chlorophyll-a (Chl-a) fluorescence induction kinetics was measured. Photosynthetic parameters like ratio of variable and maximum fluorescence (FV/FM), absorbance of photons per active reaction center (ABS/RC), trapping of photons per active reaction center (TRo/RC), electron transport per active reaction center (ETo/RC), and performance index (PI) were measured. Furthermore, the energy pipeline model was deduced in response to PEG stress. The membrane model includes a visualization of the average “antenna size”, which follows the value of the ABS/RC. Analysis of SIP Arabidopsis plants under PEG stress through fast Chl-a fluorescence transient showed that the damage caused due to PEG is more prominent at the donor side rather than the acceptor side of PSII. Higher PI in SIP plants under PEG stress indicated a better vitality than control plants. Overall, these results indicate that constitutive expression of SIP1 in Arabidopsis plants induces significant changes in the photosynthetic machinery under PEG-induced osmotic stress. 相似文献