Tomographic measurement of dielectric tensors at optical frequency.

The dielectric tensor is a physical descriptor of fundamental light-matter interactions, characterizing anisotropic materials with principal refractive indices and optic axes. Despite its importance in scientific and industrial applications ranging from material science to soft matter physics, the direct measurement of the three-dimensional dielectric tensor has been limited by the vectorial and inhomogeneous nature of light scattering from anisotropic materials. Here, we present a dielectric tensor tomographic approach to directly measure dielectric tensors of anisotropic structures including the spatial variations of principal refractive indices and directors. The anisotropic structure is illuminated with a polarized plane wave with various angles and polarization states. Then, the scattered fields are holographically measured and converted into vectorial diffracted field components. Finally, by inversely solving a vectorial wave equation, the three-dimensional dielectric tensor is reconstructed. Using this approach, we demonstrate quantitative tomographic measurements of various nematic liquid-crystal structures and their fast three-dimensional non-equilibrium dynamics.

Regularization of dielectric tensor tomography.

Dielectric tensor tomography reconstructs the three-dimensional dielectric tensors of microscopic objects and provides information about the crystalline structure orientations and principal refractive indices. Because dielectric tensor tomography is based on transmission measurement, it suffers from the missing cone problem, which causes poor axial resolution, underestimation of the refractive index, and halo artifacts. In this study, we study the application of total variation and positive semi-definiteness regularization to three-dimensional tensor distributions. In particular, we demonstrate the reduction of artifacts when applied to dielectric tensor tomography.

Vectorial inverse scattering for dielectric tensor tomography: overcoming challenges of reconstruction of highly scattering birefringent samples.

Many important microscopy samples, such as liquid crystals, biological tissue, or starches, are birefringent in nature. They scatter light differently depending on the polarization of the light and the orientation of the molecules. The complete characterization of a birefringent sample is a challenging task because its 3 × 3 dielectric tensor must be reconstructed at every three-dimensional position. Moreover, obtaining a birefringent tomogram is more arduous for thick samples, where multiple light scattering should also be considered. In this study, we developed a new dielectric tensor tomography algorithm that enables full characterization of highly scattering birefringent samples by solving the vectoral inverse scattering problem while accounting for multiple light scattering. We proposed a discrete image-processing theory to compute the error backpropagation of vectorially diffracting light. Finally, our theory was experimentally demonstrated using both synthetic and biologically birefringent samples.

Carryover Effects of Pain Neuroscience Education on Patients with Chronic Lower Back Pain: A Systematic Review and Meta-Analysis.

Background and Objectives: Because most individuals with chronic back pain (CLBP) have no specific cause, it is usually described as central sensitization. Pain neuroscience education (PNE) in top-down pain control may be effective against carryover effects; however, this remains unclear. In this study, the carryover effect was qualitatively and quantitatively synthesized and analyzed. Materials and Methods: Randomized controlled trials (RCTs) on PNE in individuals with CLBP were conducted using international databases until January 2023. Using RevMan5.4 provided by Cochrane, qualitative and quantitative analyses were performed with a risk of bias and meta-analysis, respectively. Results: Nine RCTs involving 1038 individuals with CLBP were included in the analysis. Four main results were identified: First, PNE had a short-term carryover effect on pain intensity (SMD = -1.55, 95% confidence interval [CI] = -2.59 to -0.50); second, PNE had a short-term carryover effect on pain catastrophizing (SMD = -2.47, 95% CI = -3.44 to -1.50); third, PNE had short- and long-term carryover effects on kinesiophobia (SMD = -3.51, 95% CI = -4.83 to -2.19); fourth, the appropriate therapeutic intensity of PNE for the pain intensity of individuals (SMD = -0.83, 95% CI = -1.60 to -0.07). Conclusions: PNE has a short-term carryover effect on pain intensity and pain cognition in individuals with CLBP and a long-term carryover effect on kinesiophobia.

Spatially multiplexed dielectric tensor tomography.

Dielectric tensor tomography (DTT) enables the reconstruction of three-dimensional (3D) dielectric tensors, which provides a physical measure of 3D optical anisotropy. Herein, we present a cost-effective and robust method of DTT using spatial multiplexing. Exploiting two orthogonally polarized reference beams with different angles in an off-axis interferometer, two polarization-sensitive interferograms were multiplexed and recorded using a single camera. Then, the two interferograms were demultiplexed in the Fourier domain. By measuring the polarization-sensitive fields for various illumination angles, 3D dielectric tensor tomograms were reconstructed. The proposed method was experimentally demonstrated by reconstructing the 3D dielectric tensors of various liquid-crystal (LC) particles with radial and bipolar orientational configurations.

Effects of air pollution on moderate and severe asthma exacerbations.

Background: Few studies have evaluated the impact of air pollution levels on the severity of exacerbations. Thus, we compared the relative risks posed by air pollutant levels on moderate and severe exacerbations.Methods: Exacerbation episodes of 618 from 143 adult asthmatics were retrospectively collected between 2005 and 2015 in a tertiary hospital of Korea. Air pollution GPS data for the location closest to each patient's home were obtained from the national ambient monitoring station. The relative impacts of air pollutants on asthma exacerbations were evaluated via a time-trend controlled symmetrical, bidirectional, case-crossover design using conditional logistic regression models on the day of the exacerbation (T-0) and up to 3 days before the exacerbation (T-1-T-3).Results: Overall asthma exacerbation were associated with O3 levels in summer and winter (OR: 1.012[1.003-1.02] and 1.009[1.003-1.016]), SO2 levels in spring and summer (OR: 1.009[1-1.018] and 1.02[1.006-1.035]) and NO2 levels in winter (OR: 1.007[1.003-1.011]). Analyses of the temporal relationship between O3 concentrations and exacerbations demonstrated that 63.2% of episodes in the summer occurred when the O3 concentrations on T-1 were significantly higher than those on control days, while 51% of exacerbation episodes in the winter occurred. Severe and moderate exacerbations were similarly associated with O3 levels in winter (OR: 1.012 [1.003-1.02] vs. 1.01 [0.999-1.021], p > 0.05) and in summer (OR: 1.006 [1.002-1.009] vs. 1.009 [1.003-1.016], p > 0.05).Conclusions: Asthma exacerbations may be associated with the seasonal elevation of O3, SO2 and NO2 levels in summer and winter with the similar relative risk between moderate and severe exacerbations.

Reference-free polarization-sensitive quantitative phase imaging using single-point optical phase conjugation.

We propose and experimentally demonstrate a method of polarization-sensitive quantitative phase imaging using two photodetectors and a digital micromirror device. Instead of recording wide-field interference patterns, finding the modulation patterns maximizing focused intensities in terms of the polarization states enables polarization-dependent quantitative phase imaging without the need for a reference beam and an image sensor. The feasibility of the present method is experimentally validated by reconstructing Jones matrices of several samples including a polystyrene microsphere, a maize starch granule, and a mouse retinal nerve fiber layer. Since the present method is simple and sufficiently general, we expect that it may offer solutions for quantitative phase imaging of birefringent materials.

Generalized quantification of three-dimensional resolution in optical diffraction tomography using the projection of maximal spatial bandwidths.

Optical diffraction tomography (ODT) is a three-dimensional (3D) quantitative phase imaging technique, which enables the reconstruction of the 3D refractive index (RI) distribution of a transparent sample. Due to its fast, non-invasive, and quantitative imaging capability, ODT has emerged as a powerful tool for various applications. However, the spatial resolution of ODT has only been quantified along the lateral and axial directions for limited conditions; it has not been investigated for arbitrary-oblique directions. In this paper, we systematically quantify the 3D spatial resolution of ODT by exploiting the spatial bandwidth of the reconstructed scattering potential. The 3D spatial resolution is calculated for various types of systems, including the illumination-scanning, sample-rotation, and hybrid scanning-rotation methods. In particular, using the calculated 3D spatial resolution, we provide the spatial resolution as well as the arbitrary sliced angle. Furthermore, to validate the present method, the point spread function of an ODT system is experimentally obtained using the deconvolution of a 3D RI distribution of a microsphere and is compared with the calculated resolution.

Combining Three-Dimensional Quantitative Phase Imaging and Fluorescence Microscopy for the Study of Cell Pathophysiology.

Quantitative phase imaging (QPI) has emerged as one of the powerful imaging tools for the study of live cells in a non-invasive manner. In particular, multimodal approaches combining QPI and fluorescence microscopic techniques have been recently developed for superior spatiotemporal resolution as well as high molecular specificity. In this review, we briefly summarize recent advances in three-dimensional QPI combined with fluorescence techniques for the correlative study of cell pathophysiology. Through this review, biologists and clinicians can be provided with insights on this rapidly growing field of research and may find broader applications to investigate unrevealed nature in cell physiology and related diseases.

Reconstructions of refractive index tomograms via a discrete algebraic reconstruction technique.

Optical diffraction tomography (ODT) provides three-dimensional refractive index (RI) tomograms of a transparent microscopic object. However, because of the finite numerical aperture of objective lenses, ODT has a limited access to diffracted light and suffers from poor spatial resolution, particularly along the axial direction. To overcome the limitation of the quality of RI tomography, we present an algorithm that accurately reconstructs RI tomography of a specimen with discrete and uniform RI, using prior information about the RI levels. Through simulations and experiments on various samples, including microspheres, red blood cells, and water droplets, we show that the proposed method can precisely reconstruct RI tomograms of samples which have discrete and homogenous RI distributions in the presence of the missing information and noise.

Effects of spatiotemporal coherence on interferometric microscopy.

Illumination coherence plays a major role in various imaging systems, from microscopy, metrology, digital holography, optical coherence tomography, to ultrasound imaging. Here, we present a systematic study on the effects of degrees of spatiotemporal coherence of an illumination (DSTCI) on imaging quality of interferometric microscopy. An optical field with arbitrary DSTCI was decomposed into wavelets with constituent spatiotemporal frequencies, and the effects on image quality were quantitatively investigated. The results show the synergistic effects on reduction of speckle noise when DSTCI is decreased. This study presents a method to systematically control DSTCI, and the result provides an essential reference on the effects of DSTCI on the imaging quality. We believe that the presented methods and results can be implemented in various imaging systems for characterizing and improving the imaging quality.

Time-multiplexed structured illumination using a DMD for optical diffraction tomography.

We present a time-multiplexing structured illumination control technique for optical diffraction tomography (ODT). Instead of tilting the angle of illumination, time-multiplexed sinusoidal illumination is exploited using a digital micromirror device (DMD). The present method effectively eliminates unwanted diffracted beams from binary DMD patterns, which deteriorates the image quality of the ODT in the previous binary Lee hologram method. We experimentally show the feasibility and advantage of the present method by reconstructing three-dimensional refractive index distributions of various samples and comparing with a conventional Lee hologram method.

Visualization and label-free quantification of microfluidic mixing using quantitative phase imaging.

Microfluidic mixing plays a key role in various fields, including biomedicine and chemical engineering. To date, although various approaches for imaging microfluidic mixing have been proposed, they provide only quantitative imaging capability and require exogenous labeling agents. Quantitative phase imaging techniques, however, circumvent these problems and offer label-free quantitative information about concentration maps of microfluidic mixing. We present the quantitative phase imaging of microfluidic mixing in various types of polydimethylsiloxane microfluidic channels with different geometries; the feasibility of the present method was validated by comparing it with the results obtained by theoretical calculation based on Fick's law.

Anti-inflammatory effects of Zea mays L. husk extracts.

BACKGROUND: Zea mays L. (Z. mays) has been used for human consumption in the various forms of meal, cooking oil, thickener in sauces and puddings, sweetener in processed food and beverage products, bio-disel. However, especially, in case of husk extract of Z. mays, little is known about its anti-inflammatory effects. Therefore, in this study, the anti-inflammatory effects of Z. mays husk extract (ZMHE) and its mechanisms of action were investigated. METHODS: The husks of Z. Mays were harvested in kangwondo, Korea. To assess the anti-inflammatory activities of ZMHE, we examined effects of ZMHE on nitric oxide (NO) production, and release of soluble intercellular adhesion molecule-1 (sICAM-1) and eotaxin-1. The expression level of inducible nitric oxide synthase (iNOS) gene was also determined by Western blot and luciferase reporter assays. To determine its mechanisms of action, a luciferase reporter assay for nuclear factor kappa B (NF-kB) and activator protein-1 (AP-1) was introduced. RESULTS: ZMHE inhibited lipopolysaccharide (LPS)-induced production of NO in RAW264.7 cells. In addition, expression of iNOS gene was reduced, as confirmed by Western blot and luciferase reporter assays. Effects of ZMHE on the AP-1 and NF-kB promoters were examined to elucidate the mechanism of its anti-inflammatory activity. Activation of AP-1 and NF-kB promoters induced by LPS was significantly reduced by ZMHE treatment. In addition, LPS-induced production of sICAM-1 and IL-4-induced production of eotaxin-1 were all reduced by ZMHE. CONCLUSIONS: Our results indicate that ZMHE has anti-inflammatory effects by downregulating the expression of iNOS gene and its downregulation is mediated by inhibiting NF-kB and AP-1 signaling.

Association between TAAR6 polymorphisms and airway responsiveness to inhaled corticosteroids in asthmatic patients.

BACKGROUND: Genetic polymorphisms may be responsible for the wide variation in response to inhaled corticosteroids in asthmatic patients. We had previously reported that one polymorphism rs7772821, located on the 3'-UTR of trace amine-associated receptor 6 (TAAR6), is significantly associated with percentile changes in the forced expiratory volume in 1 s (%ΔFEV1) after inhaled corticosteroid treatment in asthmatics using a genome-wide association study. The aim of the present study was to validate the association between 15 single-nucleotide polymorphisms (SNPs) on the TAAR6 and airway responsiveness to inhaled corticosteroids in the asthmatics. METHODS: The %ΔFEV1 induced by 4 weeks' treatment with inhaled fluticasone propionate (1000 µg daily) was measured in 246 asthmatics. The 15 SNPs of TAAR6 were genotyped using a TaqMan assay. An association analysis between %ΔFEV1 and TAAR6 polymorphisms was carried out using a linear regression model controlling for age, sex, smoking status, presence of atopy, and baseline FEV1 as covariates. RESULTS: Among the 15 SNPs and seven haplotypes of TAAR6, rs7772821 (T>G) on the 3'-UTR showed the strongest correlation with inhaled corticosteroid-induced %ΔFEV1 (Pcorr=0.002 in the codominant model, Pcorr=0.03 in the dominant model, Pcorr=0.01 in the recessive model). The %ΔFEV1 of the rs7772821T>G minor homozygotes (60.77%) was higher than that of patients harboring either the rs7772821 T/G or T/T genotypes (21.32 and 31.60%, respectively). CONCLUSION: The TAAR6 rs7772821 polymorphism may be one of the important genetic factors for predicting the response to treatment with inhaled corticosteroids in asthmatics.

Comparative study of iterative reconstruction algorithms for missing cone problems in optical diffraction tomography.

In optical tomography, there exist certain spatial frequency components that cannot be measured due to the limited projection angles imposed by the numerical aperture of objective lenses. This limitation, often called as the missing cone problem, causes the under-estimation of refractive index (RI) values in tomograms and results in severe elongations of RI distributions along the optical axis. To address this missing cone problem, several iterative reconstruction algorithms have been introduced exploiting prior knowledge such as positivity in RI differences or edges of samples. In this paper, various existing iterative reconstruction algorithms are systematically compared for mitigating the missing cone problem in optical diffraction tomography. In particular, three representative regularization schemes, edge preserving, total variation regularization, and the Gerchberg-Papoulis algorithm, were numerically and experimentally evaluated using spherical beads as well as real biological samples; human red blood cells and hepatocyte cells. Our work will provide important guidelines for choosing the appropriate regularization in ODT.

Active illumination using a digital micromirror device for quantitative phase imaging.

We present a powerful and cost-effective method for active illumination using a digital micromirror device (DMD) for quantitative phase-imaging techniques. Displaying binary illumination patterns on a DMD with appropriate spatial filtering, plane waves with various illumination angles are generated and impinged onto a sample. Complex optical fields of the sample obtained with various incident angles are then measured via Mach-Zehnder interferometry, from which a high-resolution 2D synthetic aperture phase image and a 3D refractive index tomogram of the sample are reconstructed. We demonstrate the fast and stable illumination-control capability of the proposed method by imaging colloidal spheres and biological cells. The capability of high-speed optical diffraction tomography is also demonstrated by measuring 3D Brownian motion of colloidal particles with the tomogram acquisition rate of 100 Hz.

Genome wide identification and expression profile in epithelial cells exposed to TiO2 particles.

Environmental particles are believed to provoke airway inflammation in susceptible individuals by stimulating epithelial cells to release mediators that exacerbate lung diseases. Here, we sought to identify genes expressed throughout the genome by epithelial cells stimulated with TiO2 particles. A human bronchial epithelial cell line, BEAS-2B, was stimulated with or without 40 µg TiO2 for 2 h. RNA was purified from cells and subjected to microarray analysis. Genes exhibiting more than a twofold change in RNA expression were selected. Candidate genes were then analyzed using bioinformatics tools, including pathway, ontology, and network analyses. ITGAV mRNA expression levels were measured in BEAS-2B cells using real-time polymerase chain reaction. Among 37,803 genes, 92 genes displayed more than a twofold change in mRNA levels according to the microarray analysis; 87 genes were upregulated while five genes were downregulated. The 92 genes were classified based on functional annotation using a protein information resource database search for biological processes and a pathway search using the KEGG pathway database. These genes are related to macromolecule biosynthesis, metabolic processes and, in particular, RNA metabolism. When genes with more than a threefold change were analyzed, KIF11, ITGAV, SEMA3C, IBTK, and DEK were selected as candidate genes induced by TiO2 -stimulated BEAS-2B cells. To validate these results, BEAS-2B cells stimulated with 40 µg TiO2 expressed threefold higher ITGAV mRNA levels compared to those without TiO2 particle stimulation. We conclude that KIF11, ITGAV, SEMA3C, IBTK, and DEK are candidate genes expressed by epithelial cells when stimulated with TiO2 particles.

Genome-wide association study of aspirin-exacerbated respiratory disease in a Korean population.

Aspirin-exacerbated respiratory disease (AERD) is a nonallergic clinical syndrome characterized by a severe decline in forced expiratory volume in one second (FEV1) following the ingestion of non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin. The effects of genetic variants have not fully explained all of the observed individual differences to an aspirin challenge despite previous attempts to identify AERD-related genes. In the present study, we performed genome-wide association study (GWAS) and targeted association study in Korean asthmatics to identify new genetic factors associated with AERD. A total of 685 asthmatic patients without AERD and 117 subjects with AERD were used for the GWAS of the first stage, and 996 asthmatics without AERD and 142 subjects with AERD were used for a follow-up study. A total of 702 SNPs were genotyped using the GoldenGate assay with the VeraCode microbead. GWAS revealed the top-ranked variants in 3' regions of the HLA-DPB1 gene. To investigate the detailed genetic effects of an associated region with the risk of AERD, a follow-up targeted association study with the 702 single nucleotide polymorphisms (SNPs) of 14 genes was performed on 802 Korean subjects. In a case-control analysis, HLA-DPB1 rs1042151 (Met105Val) shows the most significant association with the susceptibility of AERD (p = 5.11 × 10(-7); OR = 2.40). Moreover, rs1042151 also shows a gene dose for the percent decline of FEV1 after an aspirin challenge (p = 2.82 × 10(-7)). Our findings show that the HLA-DPB1 gene polymorphism may be the most susceptible genetic factor for the risk of AERD in Korean asthmatics and confirm the importance of HLA-DPB1 in the genetic etiology of AERD.

Robot-assisted radial forearm free flap harvesting: a propensity score-matched case-control study.

Although some surgeons prefer anterolateral thigh and latissimus dorsi flap for soft tissue reconstruction in the head and neck area because it minimizes donor site complications, the radial forearm flap remains the workhorse for soft tissue reconstruction due to its reliability. To reduce donor site morbidity, the authors developed a novel technique for radial forearm flap harvesting using a robotic device. 42 radial forearm free flap reconstruction cases were studied, consisting of 31 conventional and 11 robot-assisted cases. 1:1 propensity score matching was done according to age, sex, previous and postoperative radiation therapy history and method used for vein anastomosis. There was no significant difference in flap outcome, which was 100% vitality in the robot-assisted group and 90.9% vitality in the conventional group. The robot-assisted group showed significantly longer mean harvesting time than did the conventional group, being 107.2 min and 67.0 min, respectively. Robot-assisted radial forearm flap harvesting can reduce donor site complications by minimizing incision. When more surgical experience is gained under appropriate case selection, we expect our robot-assisted method will yield a harvesting time similar to that of the conventional method and thus become more reliable and feasible.