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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • electromagnetic pulse
  • cell proliferation
  • cell membrane permeability
  • cell response to electromagnetic stress
  • apoptosis
  • cancer therapy
  • necrosis
应用领域
  • Intelligent Medical Engineering
机构单位
  • V.N. Karazin Kharkiv National University
1643 条数据
?? 中文（中国） ▾

  • The Neuroprotective Effect of Maltol against Oxidative Stress on Rat Retinal Neuronal Cells

    摘要： Purpose: Maltol (3-hydroxy-2-methyl-4-pyrone), formed by the thermal degradation of starch, is found in coffee, caramelized foods, and Korean ginseng root. This study investigated whether maltol could rescue neuroretinal cells from oxidative injury in vitro. Methods: R28 cells, which are rat embryonic precursor neuroretinal cells, were exposed to hydrogen peroxide (H2O2, 0.0 to 1.5 mM) as an oxidative stress with or without maltol (0.0 to 1.0 mM). Cell viability was monitored with the lactate dehydrogenase assay and apoptosis was examined by the terminal deoxynucleotide transferase-mediated terminal uridine deoxynucleotidyl transferase nick end-labeling (TUNEL) method. To investigate the neuroprotective mechanism of maltol, the expression and phosphorylation of nuclear factor-kappa B (NF-κB), extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 were evaluated by Western immunoblot analysis. Results: R28 cells exposed to H2O2 were found to have decreased viability in a dose- and time-dependent manner. However, H2O2-induced cytotoxicity was decreased with the addition of maltol. When R28 cells were exposed to 1.0 mM H2O2 for 24 hours, the cytotoxicity was 60.69 ± 5.71%. However, the cytotoxicity was reduced in the presence of 1.0 mM maltol. This H2O2-induced cytotoxicity caused apoptosis of R28 cells, characterized by DNA fragmentation. Apoptosis of oxidatively-stressed R28 cells with 1.0 mM H2O2 was decreased with 1.0 mM maltol, as determined by the TUNEL method. Western blot analysis showed that treatment with maltol reduced phosphorylation of NF-κB, ERK, and JNK, but not p38. The neuroprotective effects of maltol seemed to be related to attenuated expression of NF-κB, ERK, and JNK. Conclusions: Maltol not only increased cell viability but also attenuated DNA fragmentation. The results obtained here show that maltol has neuroprotective effects against hypoxia-induced neuroretinal cell damage in R28 cells, and its effects may act through the NF-κB and mitogen-activated protein kinase signaling pathways.

    关键词： Oxidative stress,Neuroprotection,Maltol,Rat retinal neuronal cell

    更新于2025-09-04 15:30:14

  • Gadolinium Doping Enhances the Photoacoustic Signal of Synthetic Melanin Nanoparticles: A Dual Modality Contrast Agent for Stem Cell Imaging.

    摘要： In this paper we show that gadolinium-loaded synthetic melanin nanoparticles (Gd(III)-SMNPs) exhibit up to a 40-fold enhanced photoacoustic signal intensity relative to synthetic melanin alone and higher than other metal-chelated SMNPs. This property makes these materials useful as dual labelling agents because Gd(III)-SMNPs also behave as magnetic resonance imaging (MRI) contrast agents. As a proof-of-concept, we used these nanoparticles to label human mesenchymal stem cells (hMSCs). Cellular uptake was confirmed with bright field optical and transmission electron microscopy. The Gd(III)-SMNP labeled stem cells continued to express the stem cell surface markers CD73, CD90, and CD105 and proliferate. The labeled stem cells were subsequently injected intramyocardially in mice, and the tissue was observed by photoacoustic and MR imaging. We found the photoacoustic signal increased as cell number increased (R2 = 0.96) indicating that such an approach could be employed to discriminate between stem cells populations with a limit of detection of 2.3 x 104 cells in in vitro tests. This multimodal photoacoustic/MRI approach combines the excellent temporal resolution of photoacoustics with the anatomic resolution of MRI.

    关键词： Photoacoustic Signal,Stem Cell Imaging,Gadolinium,Dual Modality Contrast Agent,Synthetic Melanin Nanoparticles

    更新于2025-09-04 15:30:14

  • Whole-cell, 3D and multi-color STED imaging with exchangeable fluorophores

    摘要： We demonstrate STED microscopy of whole bacterial and eukaryotic cells using fluorogenic labels that reversibly bind to their target structure. A constant exchange of labels guarantees the removal of photobleached fluorophores and their replacement by intact fluorophores, thereby circumventing bleaching-related limitations of STED super-resolution imaging. We achieve a constant labeling density and demonstrate a fluorescence signal for long and theoretically unlimited acquisition times. Using this concept, we demonstrate whole-cell, 3D, multi-color and live cell STED microscopy.

    关键词： PAINT,fluorogenic labels,multicolor imaging,live-cell STED microscopy,volumetric imaging,exchange-based STED microscopy

    更新于2025-09-04 15:30:14

  • High-resolution cost-effective compact portable inverted light microscope

    摘要： Commercial high-resolution optical microscopes are essential for microscopy imaging; however, they are expensive and bulky, which limits their use in point-of-care devices, resource-limited areas, and real-time imaging of a sample in a large apparatus. In this study, we report a novel compact (10 cm × 5 cm × 5 cm, without the light source) lightweight (≤0.5 kg) submicron-resolution inverted optical microscope at low cost (≤$ 300). Our technique utilises the proximity of the image sensor to a commercial microscope objective lens for compactness of the microscope. The use of an image sensor with a small pixel size helps to reduce the information loss, which provides high-resolution images. Moreover, our technique offers a freedom to tailor the design of microscope according to the required resolution, cost, and portability for specific applications, which makes it a suitable candidate for affordable point-of-care devices. Images of several micron-to-submicron scale patterns and spherical beads are acquired to observe the resolution and quality of the images obtained using our microscope. In addition, we demonstrate the applications of our microscope in various fields such as recording of high-speed water micro-droplet formation inside a microfluidic device, high-resolution live cell imaging inside an incubator, and real-time imaging of crack propagation in a sample under stretching by a material testing system (MTS). Therefore, this portable and inexpensive microscope provides the essential functionalities of a bulky expensive high-performance microscope at a lower cost.

    关键词： portable inverted microscope,microfluidics,discrete wavelet transform,submicron-scale imaging,industrial microscope,Cell imaging

    更新于2025-09-04 15:30:14

  • A machine learning approach for online automated optimization of super-resolution optical microscopy

    摘要： Traditional approaches for finding well-performing parameterizations of complex imaging systems, such as super-resolution microscopes rely on an extensive exploration phase over the illumination and acquisition settings, prior to the imaging task. This strategy suffers from several issues: it requires a large amount of parameter configurations to be evaluated, it leads to discrepancies between well-performing parameters in the exploration phase and imaging task, and it results in a waste of time and resources given that optimization and final imaging tasks are conducted separately. Here we show that a fully automated, machine learning-based system can conduct imaging parameter optimization toward a trade-off between several objectives, simultaneously to the imaging task. Its potential is highlighted on various imaging tasks, such as live-cell and multicolor imaging and multimodal optimization. This online optimization routine can be integrated to various imaging systems to increase accessibility, optimize performance and improve overall imaging quality.

    关键词： machine learning,multicolor imaging,online automated optimization,live-cell imaging,super-resolution optical microscopy,multimodal optimization

    更新于2025-09-04 15:30:14

  • Virtual Tissue Engineering and Optic Pathways: Plotting the Course of the Axons in the Retinal Nerve Fiber Layer

    摘要： As part of a larger project on virtual tissue engineering of the optic pathways, we describe the conditions that guide axons extending from the retina to the optic nerve head and formulate algorithms that meet such conditions. To find the entrance site on the optic nerve head of each axon, we challenge the fibers to comply with current models of axonal pathfinding. METHODS. First, we build a retinal map using a single type of retinal ganglion cell (RGC) using density functions from the literature. Dendritic arbors are equated to receptive fields. Shape and size of retinal surface and optic nerve head (ONH) are defined. A computer model relates each soma to the corresponding entry point of its axon into the optic disc. Weights are given to the heuristics that guide the preference entry order in the nerve. RESULTS. Retinal ganglion cells from the area centralis saturate the temporal section of the disc. Retinal ganglion cells temporal to the area centralis curve their paths surrounding the fovea; some of these cells enter the disc centrally rather than peripherally. Nasal regions of the disc receive mixed axons from the far periphery of the temporal hemiretina, together with axons from the nasal half. The model plots the course of the axon using Bezier curves and compares them with clinical data, for a coincidence level of 86% or higher. CONCLUSIONS. Our model is able to simulate basic data of the early optic pathways including certain singularities and to mimic mechanisms operating during development, such as timing and fasciculation.

    关键词： optic pathways,course of axons,retinal ganglion cell layer,computer modeling

    更新于2025-09-04 15:30:14

  • The Effect of Transient Local Anti-inflammatory Treatment on the Survival of Pig Retinal Progenitor Cell Allotransplants

    摘要： The development of photoreceptor degenerative disorders requires the identification of the optimal cell source and immunosuppressive regimen in a large animal model. Allotransplants are not acutely rejected in swine subretinal space, although it is not known if survival can be improved with immunosuppression. Here we investigated the survival and integration of expanded pig retinal progenitor cells (pRPCs) in normal recipients with and without transient anti-inflammatory suppression. pRPCs were derived from the neural retina of E60 GFP transgenic pigs, expanded for six passages, characterized, and transplanted into the subretinal space of 12 pigs. Six recipients received a single intravitreal injection of rapamycin and dexamethasone. pRPCs expressed the photoreceptor development genes Sox2, Pax6, Lhx2, Crx, Nrl, and Recoverin in vitro. Transplanted cells were identified in 9 out of 12 recipients 4 weeks after the injection. pRPCs integrated primarily into the photoreceptor inner segment layer and outer nuclear layer with single cells present in the inner nuclear layer. Donor cells remained recoverin-positive and acquired rhodopsin. We did not observe any signs of graft proliferation. The immunosuppression did not affect the survival or distribution of grafts. No macrophage infiltration or loss of retinal structure was observed in either group. Local immunosuppression with rapamycin and dexamethasone does not improve the outcome of pRPC allotransplantation into the subretinal space. Survival and integration of pRPC together with the lack of graft proliferation suggests that allogeneic RPC transplantation without transient immunosuppression is a favorable approach for photoreceptor cell replacement.

    关键词： rapamycin,retina,retinal progenitor cells,cell therapy,photoreceptors

    更新于2025-09-04 15:30:14

  • Análise da expans?o térmica volumétrica e das características estruturais de solu??es sólidas de (Pb, Ca)TiO3 entre 150 e 570 K

    摘要： Ceramic samples of lead modified calcium titanate (Pb1-xCaxTiO3) with calcium concentration between 0.24≤x≤0.55 were prepared and analyzed in order to determine the structural origin of the negative thermal expansion observed in this ferroelectric system. The Rietveld structural refinement method was used to assess the thermal evolution of the structural parameters using powder X-ray diffraction data collected between 150 and 570 K. Since the Pb1-xCaxTiO3 phase diagram and space groups are still unknown for the temperature range investigated, the structural analyses were based on adjustments of the refinement protocol. The results revealed the existence of a correlation between symmetry transitions and anomalies in the thermal expansion of the unit cell, being such transitions not necessarily of the ferroelectric-paraelectric nature.

    关键词： Rietveld refinement method,symmetry transitions,structural analyses,unit cell thermal expansion,ferroelectric ceramics

    更新于2025-09-04 15:30:14

  • FOCUSING TRANSLATIONAL VARIANT BISTATIC FORWARD-LOOKING SAR DATA BASED ON TWO-DIMENSIONAL NON-UNIFORM FFT

    摘要： Forward-looking imaging has extensive potential applications, such as self-navigation and self-landing. By choosing proper geometry, bistatic synthetic aperture radar (BiSAR) can break through the limitations of monostatic SAR on forward-looking imaging and provide possibility of the forward-looking imaging. In this special bistatic configuration, two problems involving large range cell migration (RCM) and large range-azimuth coupling are introduced by the forward-looking beam, which make it difficult to use traditional data focusing algorithms. To address these problems, a novel Omega-K algorithm based on two-dimensional non-uniform FFT (2-D NUFFT) for translational variant (TV) bistatic forward-looking SAR (BFSAR) imaging is proposed in this paper. In this study, we derive an accurate spectrum expression based on two-dimensional principle of stationary phase (2-D POSP). 2-D NUFFT is utilized to eliminate the range-variant term, which can make full use of the data and improve the computational efficiency as well. The experimental results, presented herein, demonstrate the effectiveness and advantages of the proposed algorithm.

    关键词： range-azimuth coupling,Omega-K algorithm,bistatic synthetic aperture radar,forward-looking imaging,2-D NUFFT,range cell migration

    更新于2025-09-04 15:30:14

  • Lab-on-a-Tip (LOT): Where Nanotechnology Can Revolutionize Fibre Optics

    摘要： Recently developed lab-on-a-chip technologies integrate multiple traditional assays on a single chip with higher sensitivity, faster assay time, and more streamlined sample operation. We discuss the prospects of the lab-on-a-tip platform, where assays can be integrated on a miniaturized tip for in situ and in vivo analysis. It will resolve some of the limitations of available lab-on-a-chip platforms and enable next generation multifunctional in vivo sensors, as well as analytical techniques at the single cell or even sub-cellular levels.

    关键词： Single cell analysis,Endoscopy,Lab-on-a-tip (LOT),Nanotechnology,Biosensor

    更新于2025-09-04 15:30:14