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41.
42.
光学分子影像技术及其在药物研发领域的应用 总被引:2,自引:0,他引:2
光学分子影像技术是一种发展迅速的生物医学影像技术,能够利用生物发光技术或荧光蛋白等,对生物体内特定的生物过程进行无创的定性或定量研究。应用该技术可以对药物进行筛选,选取具有潜在治疗效果的药物进行后续研究,而终止对可能无效药物的研究,同时可以评价药物对肿瘤的代谢、增殖、血管形成、凋亡和组织乏氧等方面的影响。本文主要介绍光学分子影像技术及其在药物研发,尤其是抗肿瘤药物研发领域的应用。 相似文献
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Breunig M Lungwitz U Liebl R Fontanari C Klar J Kurtz A Blunk T Goepferich A 《The journal of gene medicine》2005,7(10):1287-1298
BACKGROUND: Linear polyethylenimine (LPEI) with a molecular weight (MW) of 22 kDa has been described as having a superior ability to induce gene transfer compared to its branched form. However, the transfection efficiency of the polymer cannot be enhanced beyond a certain limit due to cytotoxicity. We explored the potential of utilizing LPEIs with MWs ranging from 1.0 to 9.5 kDa to overcome this limitation. METHODS: Polyplexes of plasmid DNA encoding for the enhanced green fluorescent protein (EGFP) and various LPEIs were compared concerning their transfection efficiency and cytotoxicity in CHO-K1 and HeLa cells by flow cytometry. The involvement of endolysosomes in LPEI-mediated gene transfer was investigated by applying the proton pump inhibitor bafilomycin A1 and the lysosomotropic agent sucrose. Confocal laser scanning microscopy was applied to assess the size and shape of polyplexes under cell culture conditions, to detect their endolysosomal localization and to observe their translocation to the nucleus. RESULTS: The transfection efficiency could be altered by varying the MW and the amount of the polymer available for polyplex formation. The highest transfection efficiency (about 44%), i.e. the fraction of EGFP-positive cells, was obtained with LPEI 5.6 kDa, while the cytotoxicity remained low. The colocalization of polyplexes and endolysosomes was observed, and it appeared that the larger polyplexes escaped from the acidic organelles particularly quickly. For LPEI 5.0 and 9.0 kDa, the number of cells and nuclei that had taken up DNA after 6 hours was similar, as determined by flow cytometry. CONCLUSIONS: Our study suggests that LPEIs with low MWs are promising candidates for non-viral gene delivery, because they are more efficient and substantially less toxic than their higher MW counterparts. 相似文献
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Eric Wickstrom Mathew L. Thakur Edward R. Sauter 《International journal of peptide research and therapeutics》2003,10(3-4):191-214
Summary Genomic sequencing makes it possible to identify all the genes of an organism, now includingHomo sapiens. Yet measurement of the expression of each gene of interest still presents a daunting prospect. Northern blots, RNase protection
assays, as well as microarrays and related technologies permit measurement of gene expression in total RNA extracted from
cultured cells or tissue samples. It would be most valuable, however, to quantitate gene expression noninvasively in living
cells and tissues. Unfortunately, no reliable method has been available to measure levels of specific mRNAsin vivo. Peptide nucleic acids (PNAs) display superior ruggedness and hybridization properties as a diagnostic tool for gene expression,
and could be used for this purpose. On the down side, they are negligibly internalized by normal or malignant cells in the
absence of conjugated ligands. Nevertheless, we have observed that Tc-99m-peptides can delineate tumors, and PNA-peptides
designed to bind to IGF-1 receptors on malignant cells are taken up specifically and concentrated in nuclei. We have postulated
that antisense Tc-99m-PNA-peptides will be taken up by human cancer cells, will hybridize to complementary mRNA targets, and
will permit scintigraphic imaging of oncogene mRNAs in human cancer xenografts in a mouse model. The oncogenes cyclin D1,ERBB2, c-MYC, K-RAS, and tumor suppressor p53 are being probed initially. These experiments provide a proof-of-principle for noninvasive detection
of oncogene expression in living cells and tissues. This scintigraphic imaging technique should be applicable to any particular
gene of interest in a cell or tissue type with characteristic receptors. 相似文献
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Haiyan Luo Sanghun Sin Joseph M. McDonough Carmen R. Isasi Raanan Arens David M. Wootton 《Journal of biomechanics》2014
Background
Improvements in obstructive sleep apnea syndrome (OSAS) severity may be associated with improved pharyngeal fluid mechanics following adenotonsillectomy (AT). The study objective is to use image-based computational fluid dynamics (CFD) to model changes in pharyngeal pressures after AT, in obese children with OSAS and adenotonsillar hypertrophy.Methods
Three-dimensional models of the upper airway from nares to trachea, before and after AT, were derived from magnetic resonance images obtained during wakefulness, in a cohort of 10 obese children with OSAS. Velocity, pressure, and turbulence fields during peak tidal inspiratory flow were computed using commercial software. CFD endpoints were correlated with polysomnography endpoints before and after AT using Spearman?s rank correlation (rs).Results
Apnea hypopnea index (AHI) decreases after AT was strongly correlated with reduction in maximum pressure drop (dPTAmax) in the region where tonsils and adenoid constrict the pharynx (rs=0.78, P=0.011), and with decrease of the ratio of dPTAmax to flow rate (rs=0.82, P=0.006). Correlations of AHI decrease to anatomy, negative pressure in the overlap region (including nasal flow resistance), or pressure drop through the entire pharynx, were not significant. In a subgroup of subjects with more than 10% improvement in AHI, correlations between flow variables and AHI decrease were stronger than in all subjects.Conclusions
The correlation between change in dPTAmax and improved AHI suggests that dPTAmax may be a useful index for internal airway loading due to anatomical narrowing, and may be better correlated with AHI than direct airway anatomic measurements. 相似文献49.
X-ray absorption and phase contrast imaging to study the interplay between plant roots and soil structure 总被引:2,自引:0,他引:2
Plant performance is, at least partly, linked to the location of roots with respect to soil structure features and the micro-environment
surrounding roots. Measurements of root distributions from intact samples, using optical microscopy and field tracings have
been partially successful but are imprecise and labour-intensive. Theoretically, X-ray computed micro-tomography represents
an ideal solution for non-invasive imaging of plant roots and soil structure. However, before it becomes fast enough and affordable
or easily accessible, there is still a need for a diagnostic tool to investigate root/soil interplay. Here, a method for detection
of undisturbed plant roots and their immediate physical environment is presented. X-ray absorption and phase contrast imaging
are combined to produce projection images of soil sections from which root distributions and soil structure can be analyzed.
The clarity of roots on the X-ray film is sufficient to allow manual tracing on an acetate sheet fixed over the film. In its
current version, the method suffers limitations mainly related to (i) the degree of subjectivity associated with manual tracing
and (ii) the difficulty of separating live and dead roots. The method represents a simple and relatively inexpensive way to
detect and quantify roots from intact samples and has scope for further improvements. In this paper, the main steps of the
method, sampling, image acquisition and image processing are documented. The potential use of the method in an agronomic perspective
is illustrated using surface and sub-surface soil samples from a controlled wheat trial. Quantitative characterization of
root attributes, e.g. radius, length density, branching intensity and the complex interplay between roots and soil structure,
is presented and discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
50.
Caroline Stefani Adam Lacy-Hulbert Thomas Skillman 《Journal of molecular biology》2018,430(21):4028-4035
ConfocalVR is a virtual reality (VR) application created to improve the ability of researchers to study the complexity of cell architecture. Confocal microscopes take pictures of fluorescently labeled proteins or molecules at different focal planes to create a stack of two-dimensional images throughout the specimen. Current software applications reconstruct the three-dimensional (3D) image and render it as a two-dimensional projection onto a computer screen where users need to rotate the image to expose the full 3D structure. This process is mentally taxing, breaks down if you stop the rotation, and does not take advantage of the eye's full field of view. ConfocalVR exploits consumer-grade VR systems to fully immerse the user in the 3D cellular image. In this virtual environment, the user can (1) adjust image viewing parameters without leaving the virtual space, (2) reach out and grab the image to quickly rotate and scale the image to focus on key features, and (3) interact with other users in a shared virtual space enabling real-time collaborative exploration and discussion. We found that immersive VR technology allows the user to rapidly understand cellular architecture and protein or molecule distribution. We note that it is impossible to understand the value of immersive visualization without experiencing it first hand, so we encourage readers to get access to a VR system, download this software, and evaluate it for yourself. The ConfocalVR software is available for download at http://www.confocalvr.com, and is free for nonprofits. 相似文献