Publications by authors named "Shuhei Shibata"

9 Publications

  • Page 1 of 1

Acquisition of mesenchymal-like phenotypes and overproduction of angiogenic factors in lenvatinib-resistant hepatocellular carcinoma cells.

Biochem Biophys Res Commun 2021 Apr 3;549:171-178. Epub 2021 Mar 3.

Department of Gastroenterology, Graduate School of Medicine, Chiba University, Chiba, Japan.

Lenvatinib is one of the first-line drugs for patients with advanced hepatocellular carcinoma (HCC) and widely used around the world. However, the mechanisms underlying resistance to lenvatinib remain unclear. In this study, we conducted characteristic analyses of lenvatinib-resistant HCC cells. Lenvatinib-resistant HCC cell lines were established by exposure to serially escalated doses of lenvatinib over 2 months. The biological characteristics of these cells were examined by in vitro assays. To investigate the cytokine profile of lenvatinib-resistant HCC cells, the supernatant derived from lenvatinib-resistant Huh7 cells was subjected to nitrocellulose membrane-based sandwich immunoassay. Both activation of the MAPK/MEK/ERK signaling pathway and upregulation of epithelial mesenchymal transition markers were observed in lenvatinib-resistant cells. Concordant with these findings, proliferation and invasion abilities were enhanced in these cells compared with control cells. Screening of a cytokine array spotted with 105 different antibodies to human cytokines enabled us to identify 16 upregulated cytokines in lenvatinib-resistant cells. Among them, 3 angiogenic cytokines: vascular endothelial growth factor (VEGF), platelet-derived growth factor-AA (PDGF-AA), and angiogenin, were increased significantly. Conditioned medium from lenvatinib-resistant cells accelerated tube formation of human umbilical vein cells. In conclusion, lenvatinib-resistant HCC cells were characterized by enhanced proliferation and invasion abilities. These findings might contribute to the establishment of new combination therapies with lenvatinib.
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http://dx.doi.org/10.1016/j.bbrc.2021.02.097DOI Listing
April 2021

Minimizing scattering-induced phase errors in differential interference contrast microscopy.

J Biomed Opt 2020 12;25(12)

Utsunomiya University, Department of Optical Engineering, Tochigi, Japan.

Significance: Differential interference contrast (DIC) microscopes allow noninvasive in vivo observation of transparent microstructures in tissue without the use of fluorescent dyes or genetic modification. We show how to modify a DIC microscope to measure the sample phase distribution accurately and in real-time even deep inside sample tissue.

Aim: Our aim is to improve the DIC microscope's phase measurement to remove the phase bias that occurs in the presence of strong scattering.

Approach: A quarter-wave plate was added in front of the polarization camera, allowing a modified phase calculation to incorporate all four polarization orientation angles (0 deg, 45 deg, 90 deg, and 135 deg) captured simultaneously by the polarization camera, followed by deconvolution.

Results: We confirm that the proposed method reduces phase measurement error in the presence of scattering and demonstrate the method using in vivo imaging of a beating heart inside a medaka egg and the whole-body blood circulation in a young medaka fish.

Conclusions: Modifying a polarization-camera DIC microscope with a quarter-wave plate allows users to image deep inside samples without phase bias due to scattering effects.
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http://dx.doi.org/10.1117/1.JBO.25.12.123703DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7734411PMC
December 2020

Single shot 3D profilometry by polarization pattern projection.

Appl Opt 2020 Feb;59(6):1654-1659

We demonstrate a uniaxial 3D profilometry system illuminating the sample with a linear polarization pattern and measuring a polarization camera. The linear polarization pattern is generated by a spatial light modulator and a quarter-wave plate in the optical system. The system can measure four different fringe patterns with a phase difference of 90 deg simultaneously in the polarization camera. Therefore, we can measure three-dimensional shapes in a single shot. We present the measurement principles of the system and show the results of a real-time 3D profilometry experiment.
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http://dx.doi.org/10.1364/AO.382690DOI Listing
February 2020

Compact and high-speed Stokes polarimeter using three-way polarization-preserving beam splitters.

Appl Opt 2019 Jul;58(21):5644-5649

We present a new real-time Stokes parameter measurement technique using three polarized beam splitters without mechanical motion or electrical tuning. This system can analyze the polarization state of light at 30 kHz, limited only by the speed of the detector analog to digital converters. The optical system is also compact (52×30×25  mm) because it consists only of small volume optical devices. We show that the system can measure arbitrary polarization states with an accuracy of better than 0.006 in the normalized Stokes parameters. We also demonstrate the ability to measure fast dynamic polarization states by analyzing the state produced by a fast rotating quarter-wave plate and the time-dependent stress induced in a PMMA block by hitting the block with a hammer.
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http://dx.doi.org/10.1364/AO.58.005644DOI Listing
July 2019

Quantitative discrimination of biological tissues by micro-elastographic measurement using an epi-illumination Mueller matrix microscope.

Biomed Opt Express 2019 Aug 9;10(8):3847-3859. Epub 2019 Jul 9.

Graduate School of Engineering, Utsunomiya University, Utsunomiya, Tochigi, 321-8585, Japan.

We propose a method for estimating the stiffness of bio-specimens by measuring their linear retardance properties under applied stress. For this purpose, we employ an epi-illumination Mueller matrix microscope and show the procedures for its calibration. We provide experimental results demonstrating how to apply Mueller matrix data to elastography, using chicken liver and chicken heart as biological samples. Finally, we show how the histograms of linear retardance images can be used to distinguish between specimens and quantify the discrimination accuracy.
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http://dx.doi.org/10.1364/BOE.10.003847DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6701520PMC
August 2019

Erratum: Video-rate quantitative phase analysis by a DIC microscope using a polarization camera: errata.

Biomed Opt Express 2019 06 23;10(6):2967-2968. Epub 2019 May 23.

Department of Optical Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi, Japan.

[This corrects the article on p. 1273 in vol. 10, PMID: 30891345.].
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http://dx.doi.org/10.1364/BOE.10.002967DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6583344PMC
June 2019

Video-rate quantitative phase analysis by a DIC microscope using a polarization camera.

Biomed Opt Express 2019 Mar 19;10(3):1273-1281. Epub 2019 Feb 19.

Department of Optical Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi, Japan.

This paper describes how to take advantage of the replacement of an intensity camera with a polarization camera in a standard differential interference contrast (DIC) microscope. Using a polarization camera enables snapshot quantitative phase analysis so that real-time imaging of living transparent tissues become possible. Using our method, we quantify the phase measurement accuracy using a phantom consisting of glass beads embedded in lacquer. In order to demonstrate these advantages, we image the pumping heart and blood flow in a living egg.
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http://dx.doi.org/10.1364/BOE.10.001273DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6420286PMC
March 2019

Robust full Stokes imaging polarimeter with dynamic calibration.

Opt Lett 2019 Feb;44(4):891-894

We present a full Stokes imaging polarimeter using a rotating retarder in combination with a polarization camera-a detector array on which a pixelated polarizer array is attached. By itself, a polarization camera cannot capture the full Stokes parameters, but we add a rotating retarder in front and show how it can be used to provide full Stokes images. In addition, we demonstrate the advantage that it can be recalibrated dynamically while taking measurements, allowing accurate measurements even in environments where the retardance in changing.
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http://dx.doi.org/10.1364/OL.44.000891DOI Listing
February 2019

Hydrodynamically induced rhythmic motion of optically driven colloidal particles on a ring.

Phys Rev E Stat Nonlin Soft Matter Phys 2012 Jun 1;85(6 Pt 1):061402. Epub 2012 Jun 1.

Department of Physics, School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.

We experimentally study the motion of optically driven colloidal particles on a circular path by varying their number N. Although an identical driving force is applied to each particle, their equally spaced configuration is hydrodynamically unstable, and a doublet configuration is spontaneously formed. In small-N systems, the angular difference between neighboring particles exhibits oscillatory or nonoscillatory behavior. The number of oscillatory modes that appear depends on the maximum number of doublets that the system can contain. Frequent switching between different modes was observed with increasing N. The characteristic frequencies of the oscillatory modes are discussed theoretically by linear stability analysis of the equations that govern the motion of hydrodynamically coupled particles. The evaluated frequencies of the slowest modes exhibit reasonably good agreement with those of the mainly observed modes in experiments. The relationship between the characteristic frequencies and specific configurations is confirmed experimentally by setting a specific initial configuration for the particles. An increase in N also enhances the mean angular velocity of the particles owing to the reduced effective viscosity in large-N systems.
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http://dx.doi.org/10.1103/PhysRevE.85.061402DOI Listing
June 2012