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Abstract Axial velocity gradient (AVG) in the optical coherence tomography angiography (OCTA) signal affects measurement accuracy when the flow is not perpendicular to the scanning beam. We developed a dual beam OCTA method to decouple the contribution of AVG from the decorrelation signal. Decoupling is first verified by phantom experiments which reduces measurement uncertainty from 1.5 to 0.7% (standard deviation). We also tested the method in human skin in vivo and the results indicate that the contribution of AVG to decorrelation signal is reduced.

Diabetic wounds are difficult to repair effectively in the clinic. Tissue engineering based on mesenchymal stem cells (MSCs) showed great therapeutic potential in wound healing. MSCs-derived exosome could reproduce the effect of MSCs by transferring the bioactive substance to the recipient cells. The biological function of exosomes was determined by the state of the derived MSCs. In this study, we cultured hUC-MSCs with EGFL6 and isolated EGFL6-preconditioned exosomes (EGF-Exos), and then investigated the effect of EGF-Exos on wound healing. The results revealed that EGF-Exos promoted the proliferation and migration of HUVECs, had the anti-inflammtory function and improved angiogenesis. Moreover, we fabricated Gelama hydrogel to load EGF-Exos to repair diabetic wounds. In vivo results showed that EGF-Exos contributed to the repair of diabetic wound and provided valuable data for understanding the role of EGF-Exos in diabetic wound healing.

IntroductionAlfalfa (Medicago sativa L.) is a globally important legume crop with high nutritional and ecological value. Drought poses a serious threat to alfalfa acreage and yields. Spermine (Spm) has been shown to protect plants from drought damage. The aim of this study was to clarify the mechanism of exogenous Spm to improve drought resistance of alfalfa. MethodsIn this study, we root applied 0.1, 0.5, and 1 mM Spm to Gannong No. 3 (G3) alfalfa under drought stress, and then determined their physiological and metabolic changes. ResultsThe results showed that exogenous Spm increased chlorophyll content, chlorophyll fluorescence parameters and gas exchange parameters, enhanced antioxidant enzymes activity, improved ascorbic acid-glutathione (AsA-GSH) cycle, increased osmoregulatory substances content, reduced hydrogen peroxide and superoxide anion levels, and inhibited malondialdehyde accumulation in alfalfa under drought stress, thereby increasing plant height and leaf relative water content and enhancing drought tolerance of alfalfa. The redundancy analysis of the above physiological indicators showed that the addition of the optimal Spm to improve drought tolerance of alfalfa under drought stress was mainly achieved by increasing catalase activity and improving the ASA-GSH cycle. In addition, metabolomics analysis revealed that exogenous Spm increased the content of oxobutanedioic acid, citric acid, fumaric acid and malic acid to enhance the tricarboxylic acid cycle. Meanwhile, exogenous Spm increased endogenous Spm and proline (Pro) content to resist drought stress by enhancing Spm and Pro metabolism. Moreover, exogenous Spm increased the accumulation of the signaling substance abscisic acid. DiscussionIn conclusion, exogenous Spm enhanced drought resistance of alfalfa leaves under drought stress.

Deconvolution is a commonly employed technique for enhancing image quality in optical imaging methods. Unfortunately, its application in optical coherence tomography (OCT) is often hindered by sensitivity to noise, which leads to additive ringing artifacts. These artifacts considerably degrade the quality of deconvolved images, thereby limiting its effectiveness in OCT imaging. In this study, we propose a framework that integrates numerical random phase masks into the deconvolution process, effectively eliminating these artifacts and enhancing image clarity. The optimized joint operation of an iterative Richardson-Lucy deconvolution and numerical synthesis of random phase masks (RPM), termed as Deconv-RPM, enables a 2.5-fold reduction in full width at half-maximum (FWHM). We demonstrate that the Deconv-RPM method significantly enhances image clarity, allowing for the discernment of previously unresolved cellular-level details in nonkeratinized epithelial cells ex vivo and moving blood cells in vivo.

This study examines the measurement of film thickness, curvature, and defects on the surface or inside of an optical element using a highly accurate and efficient method. This is essential to ensure their quality and performance. Existing methods are unable to simultaneously extract the three types of information: thickness, curvature, and defects. Spectral-domain optical coherence tomography (SD-OCT), a non-invasive imaging technique with imaging depths down to the millimeter scale, provides the possibility of detecting the optical element components’ parameters. In this paper, we propose an error correction model for compensating delay differences in A-scan, field curvature, and aberration to improve the accuracy of system fitting measurements using SD-OCT. During data processing, we use the histogram-equalized gray stretching (IAH-GS) method to deal with strong reflections in the thin film layers inside the optics using individual A-scan averages. In addition, we propose a window threshold cutoff algorithm to accurately identify defects and boundaries in OCT images. Finally, the system is capable of rapidly detecting the thickness and curvature of film layers in optical elements with a maximum measurement depth of 4.508 mm, a diameter of 15 × 15 mm, a resolution of 5.69 microns, and a sampling rate of 70 kHz. Measurements were performed on different standard optical elements to verify the accuracy and reliability of the proposed method. To the best of our knowledge, this is the first time that thickness, curvature, and defects of an optical film have been measured simultaneously, with a thickness measurement accuracy of 1.924 µm, and with a difference between the calibrated and nominal curvature measurements consistently within 1%. We believe that this research will greatly advance the use of OCT technology in the testing of optical thin films, thereby improving productivity and product quality.

Drought and heat stresses cause yield losses in alfalfa, a forage crop cultivated worldwide. Improving its drought and heat tolerance is desirable for maintaining alfalfa productivity in hot, arid regions. Cuticular wax forms a protective barrier on aerial surfaces of land plants against environmental stresses. ABCG11 encodes an ATP binding cassette (ABC) transporter that functions in the cuticular wax transport pathway. In this study, ZxABCG11 from the xerophyte Zygophyllum xanthoxylum was introduced into alfalfa by Agrobacterium tumefaciens-mediated transformation. Compared to the wild type (WT), transgenic alfalfa displayed faster growth, higher wax crystal density, and thicker cuticle on leaves under normal condition. Under either drought or heat treatment in greenhouse conditions, the plant height and shoot biomass of transgenic lines were significantly higher than those of the WT. Transgenic alfalfa showed excellent growth and 50% greater hay yield than WT under field conditions in a hot, arid region. Overexpression of ZxABCG11 up-regulated wax-related genes and resulted in more cuticular wax deposition, which contributed to reduction of cuticle permeability and thus increased water retention and photosynthesis capacity of transgenic alfalfa. Thus, overexpression of ZxABCG11 can simultaneously improve biomass yield, drought and heat tolerance in alfalfa by increasing cuticular wax deposition. Our study provides a promising avenue for developing novel forage cultivars suitable for planting in hot, arid, marginal lands.

Soil salinity is a major abiotic stress limiting crop production globally. Oat (Avena sativa) is an annual cereal with a strong salt tolerance, a high yield, and nutritional quality, although the mechanisms underlying its salt stress response remain largely unknown. We examined the physiological and transcriptomic responses of A. sativa seedlings to salt stress in tolerant cultivar Qingyongjiu 195 and sensitive cultivar 709. Under salt stress, Qingyongjiu 195 maintained a higher photosynthetic efficiency, antioxidant enzymes activity, and leaf K+ accumulation but a lower Na+ uptake than 709. RNA-seq revealed 6616 differentially expressed genes (DEGs), including 4265 up- and 2351 downregulated. These were enriched in pathways like plant–pathogen interaction, phenylpropanoid biosynthesis, and MAPK signaling. We specifically highlight DEGs involved in photosynthesis (chlG, CP47 psbB, COX2, LHCB) and antioxidants (trxA, GroES). Qingyongjiu 195 also appeared to enhance K+ uptake via KAT1 and AKT2 and sequester Na+ in vacuoles via NHX2. Additionally, HKT restricted Na+ while promoting K+ transport to shoots, maintaining K+/Na+. The expression levels of CAX, ACA, CML, CaM, and CDPK in Qingyongjiu 195 were higher than those in 709. Oats regulated Ca2+ concentration through CAX and ACA after salt stress, decoded Ca2+ signals through CML, and then transferred Ca2+ signals to downstream receptors through the Ca2+ sensors CaM and CDPK, thereby activating K+/Na+ transporters, such as SOS1 and NHX, etc. Our results shed light on plant salt stress response mechanisms and provide transcriptomic resources for molecular breeding in improving salt tolerance in oats.

AbstractAim: Non-alcoholic fatty liver disease is characterized by diffuse hepatic steatosis and has quickly risen to become the most prevalent chronic liver disease. Its incidence is increasing yearly, but the pathogenesis is still not fully understood. Porphyromonas gingivalis (P. gingivalis) is a major pathogen widely prevalent in periodontitis patients. Its infection has been reported to be a risk factor for developing insulin resistance, non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), and metabolic syndrome. The aim of this review is to evaluate the association between P. gingivalis infection and NAFLD, identify the possible etiopathogenetic mechanisms, and raise public awareness of oral health to prevent and improve NAFLD.Methods: After searching in PubMed and Web of Science databases using ‘Porphyromonas gingivalis’, ‘non-alcoholic fatty liver disease’, and ‘hepatic steatosis’ as keywords, studies related were compiled and examined.Results: P. gingivalis infection is a direct risk factor for NAFLD based on clinical and basic research. Moreover, it induces systematic changes and systemic abnormalities by disrupting metabolic, inflammatory, and immunologic homeostasis.Conclusion: P. gingivalis-odontogenic infection promotes the occurrence and development of NAFLD. Further concerns are needed to emphasize oral health and maintain good oral hygiene for the prevention and treatment of NAFLD.

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory respiratory disease characterized by airflow limitation and infective exacerbations. Here, Chan et al. report the generation of nasopharyngeal and bronchial COPD organoids derived from adult stem cells and employ them in the study of host-pathogen interactions, including SARS-CoV-2 and Pseudomonas aeruginosa.

Purpose: Endocrine resistance hormone receptor-positive (HR+) advanced breast cancer (ABC) is generally insensitive to immunecheckpoint inhibitors (ICIs). This study sought to determine whether PI3Kδ inhibitor could enhance the sensitivity of endocrine resistance HR + advanced BC to ICIs by reducing immune evasion. Methods: Patient-derived HR + ABC xenografts were implanted into immune-humanized NSG mice and subsequently treated with YY20394 (PI3Kδ inhibitor) and camrelizumab. The mice were monitored for tumor progression, biochemical blood indicators, and peripheral blood T-cell subsets. The xenografted tumors were collected at the end of the treatment cycle and subjected to HE staining, immunohistochemistry and protein phosphorylation analysis. Besides, the xenografted tumors were also used to isolate primary breast cancer cells (BCCs) and regulatory T-cells (Tregs), which were subsequently used to evaluate drug sensitivity in vitro. Results: The humanized PDX model showed a favorable initial treatment response to camrelizumab combined with YY20394 and manageable toxicity. YY20394 plus camrelizumab showed a strong inhibitory effect on HR + BC in vivo mediated by suppression of Treg activity and an increased proportion of CD8+ T cells. Mice bearing tumors treated with YY20394 and camrelizumab had less invasion, mitotic figures, and ki67 expression, while having higher IL-12 expression compared with other groups. Mechanistically, YY20394 only effectively inhibited the PI3K pathway and proliferation activity in Tregs but not in BCCs. Conclusion: Our study suggests PI3Kδ inhibitor could the enhance the efficacy of ICIs in HR + BC PDX models by combating immune suppression and provides a feasible approach that may overcome the resistance of ICIs in HR + BC patients.

Abstract Background To assess the prevalence and demographics of lower eyelid epiblepharon in Chinese preschool children and to evaluate its association with refractive errors. Methods In this population-based, cross-sectional study, a total of 3170 children aged 3 to 6 years from Beijing, China underwent examinations including weight, height, cycloplegic autorefraction and slit-lamp examination of external eyes. The prevalence of lower eyelid epiblepharon in preschool children was evaluated and its association with age, sex, body mass index (BMI), and refractive errors was analyzed using logistic regression analysis. Results The prevalence of lower eyelid epiblepharon was 26.2%, which decreased with age, with prevalence in 3-, 4-, 5-, and 6-year-olds of 30.6, 28.0, 15.0, and 14.3%, respectively. Boys had a higher risk of having epiblepharon than girls (OR = 1.41; 95%CI, (1.20–1.66)) and no significant correlation was detected between BMI and epiblepharon after adjusting for age and sex (p = 0.062). Epiblepharon was significantly associated with a higher risk of refractive errors, including astigmatism (OR = 3.41; 95% CI, (2.68–4.33)), myopia (OR = 3.55; 95% CI, (1.86–6.76)), and hyperopia (OR = 1.53; 95% CI, (1.18–1.99)). Conclusions There is a high prevalence of lower eyelid epiblepharon in Chinese preschool children, particularly among boys and younger children. Preschoolers with lower eyelid epiblepharon are subject to a higher risk of developing astigmatism, myopia, and hyperopia, than those without. Increased attention should be paid to this eyelid abnormality in the preschool population.

We report an elliptical beam design for aberration mitigation in high-resolution optical coherence tomography (OCT). We polished a large angle on the fiber terminal facet in the sample arm to make a non-rotational symmetric beam with different numerical apertures (NA) for the two axes vertical to the optical axis. By sacrificing the resolution in the out-of-plane transverse direction, the elliptical beam mitigated the aberration introduced by the focusing optics in the OCT system. The elliptical beam with a doubled NA in the in-plane transverse direction promoted the axial field-of-view (FOV) by about 50% and increased the signal back-coupling efficiency by about 25%. We verified the feasibility of the design by imaging the USAF 1951 resolution chart, swine cornea ex vivo, and human skin in vivo. Results show that the proposed method relieves aberration-related problems in high-resolution OCT.

Intraocular lens (IOL) is widely used for cataract treatment. Its optical properties are crucial to obtain a good treatment efficacy and thus need to be evaluated and controlled. In this study, we propose a novel method based on optical coherence tomography (OCT) for noncontact and accurate in vitro measurement of thickness, refractive index and dioptric power of IOL implants. The OCT setup is specially designed to create two sampling optics, called dual-side view OCT (DSV-OCT), which allows for imaging IOL from the two opposite sides simultaneously in single OCT volume scanning. This can produce a three-dimensional surface contour without suffering image distortions due to the refraction of the curved surface. Then, the thickness and surface curvature can be easily computed from the surface contours. In addition, DSV-OCT is able to measure the refractive index. Three IOLs with different dioptric powers (5D, 20D and 28D) were chosen to evaluate this method. The results show that this method is capable to provide a comprehensive and accurate evaluation of IOLs from the aspects of thickness, refractive index and dioptric power, and hence can be potentially used as a quality assurance tool by IOL manufacturers.

In this paper, we propose an optical fiber-based broadband mode coupler for multimode optical coherence tomography (OCT) in the O-band (1.26–1.36 μm). The proposed device uses a tapered few-mode fiber (FMF) to lower the effective mode index of the selected higher-order mode, which can be phase matched to the fundamental mode of the single-mode fiber (SMF). The tapered FMF and the SMF are side polished to reduce the core-to-core separation to achieve efficient mode coupling. Key design parameters such as the tapering ratio of the FMF, FMF core to SMF core separation, coupler length, and coupling ratio in the O-band are studied thoroughly. Higher-order modes of the FMF will be effectively coupled from the fundamental mode of SMF in the sample arm of the multimode OCT system. The reflected signals of the higher-order modes from the sample will be separated into several single-mode signals using the same fiber device before interfering with the reference light, which was not possible before. The proposed fiber device will be a key component to efficiently achieve multimode OCT operation with better signal collection efficiency and improved penetration depth for deep tissue imaging.

Quantifying the viscosity of a gas is of great importance in determining its properties and can even be used to identify what the gas is. While many techniques exist for measuring the viscosities of gases, it is still challenging to probe gases with a simple, robust setup that will be useful for practical applications. We introduce a facile approach to estimating gas viscosity using a strain gauge inserted in a straight microchannel with a height smaller than that of the gauge. Using a constrained geometry for the strain gauge, in which part of the gauge deforms the channel to generate initial gauge strain that can be transduced into pressure, the pressure change induced via fluid flow was measured. The change was found to linearly correlate with fluid viscosity, allowing estimation of the viscosities of gases with a simple device.

Abstract Background Precise identification, discrimination and assessment of central nervous system (CNS) tumors is of critical importance to brain neoplasm treatment. Due to the complexity and limited resolutions of the existing diagnostic tools, however, it is difficult to identify the tumors and their boundaries precisely in clinical practice, and thus, the conventional way of brain neoplasm treatment relies mainly on the experiences of neurosurgeons to make resection decisions in the surgery process. The purpose of this study is to explore the potential of Micro-optical coherence tomography (μOCT) as an intraoperative diagnostic imaging tool for identifying and discriminating glioma and meningioma with their microstructure imaging ex vivo, which thus may help neurosurgeons to perform precise surgery with low costs and reduced burdens. Methods Fresh glioma and meningioma samples were resected from patients, and then slices of such samples were excised and imaged instantly ex vivo with a lab-built μOCT, which achieves a spatial resolution of ~ 2.0 μm (μm). The acquired optical coherence tomography (OCT) images were pathologically evaluated and compared to their corresponding histology for both tumor type and tumor grade discriminations in different cases. Results By using the lab-built μOCT, both the cross-sectional and en face images of glioma and meningioma were acquired ex vivo. Based upon the morphology results, both the glioma and meningioma types as well as the glioma grades were assessed and discriminated. Comparisons between OCT imaging results and histology showed that typical tissue microstructures of glioma and meningioma could be clearly identified and confirmed the type and grade discriminations with satisfactory accuracy. Conclusions μOCT could provide high-resolution three-dimensional (3D) imaging of the glioma and meningioma tissue microstructures rapidly ex vivo. μOCT imaging results could help discriminate both tumor types and grades, which illustrates the potential of μOCT as an intraoperative diagnostic imaging tool to help neurosurgeons perform their surgery precisely in tumor treatment process.

A systematic study is conducted on variation regularities for such properties of SMA wires with the diameter of wires, strain amplitude and loading cycles as the stress-strain curve, characteristic stresses, energy dissipation capacity, equivalent damping ratio. The results show: The diameter increase of SMA wires can degrade the mechanical properties of SMA wires; SMA wires can exhibit a good and stable hysteretic performance when the strain amplitude is 6% and the loading cycle is 15. Utilizing the superelasticity of SMA and combining the operating principle of the tuned mass damper, a new kind of SMA suspension pendulum damping system, which is easy to disassemble, was designed and fabricated with the trained SMA wires. Corresponding experiments were conducted to analyse the natural frequency of the damping system, phase relations between the mass vibrators and the controlled structure, variation regularity of the equivalent damping force with the mass vibrators and length of pendulum rod. The results indicate that phase relations between the mass vibrators and the controlled structure can desirably fall within 150°~180° when this damping system subjected to the sine waves and real earthquake waves. Meanwhile, the equivalent damping force increases significantly with the amplitude of external loads. In conclusion, this kind of damping system can provide a stable and efficient damping force and be simply applied to structural vibration control, thus to protect structures free from strong dynamic disasters.

Summary: Nano-structures of biological systems can produce diverse spectroscopic effects through interactions with broadband light. Although structured coloration at the surface has been extensively studied, natural spectroscopic contrasts in deep tissues are poorly understood, which may carry valuable information for evaluating the anatomy and function of biological systems. Here we investigated the spectroscopic characteristics of an important geometry in deep tissues at the nanometer scale: packed nano-cylinders, in the near-infrared window, numerically predicted and experimentally proved that transversely oriented and regularly arranged nano-cylinders could selectively backscatter light of the long wavelengths. Notably, we found that the spectroscopic contrast of nanoscale fibrous structures was sensitive to the pressure load, possibly owing to the changes in the orientation, the degree of alignment, and the spacing. To explore the underlying physical basis, we further developed an analytical model based on the radial distribution function in terms of their radius, refractive index, and spatial distribution. : Infrared Optics; Medical Imaging; Optical Imaging; Spectroscopy Subject Areas: Infrared Optics, Medical Imaging, Optical Imaging, Spectroscopy

The axial resolution of optical coherence tomography (OCT) is determined by the spectral shape and bandwidth of the detected light, which are limited by the gaps in the wavelength range of illumination, transmission, and detection. In this paper, we demonstrate that the axial resolution deteriorated by gaps in OCT spectra can be restored by adopting the gapped amplitude and phase estimation (GAPES) method. GAPES estimates the missing parts between separated spectral bands and obtains the axial profile of tissue with reduced sidelobe artifacts compared to the gapped spectra and significantly improved axial resolution over the individual bands. This technique may make it possible to combine spectrally separated sources and detectors to improve axial resolution in OCT images.

Conformal coating (CC) is widely used to protect printed circuit board from corrosion, mold growth, and electrical failures. To ensure effective protection, the thickness of the CC layer needs to be well controlled. However, to date, the coating thickness is usually measured in a destructive way under microscopes. In this paper, we proposed to use optical coherence tomography (OCT) to measure the CC thickness nondestructively. Specifically, to obtain a good accuracy in thickness measurement, we constructed a spectral domain OCT with the ultra-high axial resolution to image the CC layer in three dimensions and developed an image segmentation algorithm to detect the CC layer from the OCT images. Finally, we evaluated the effectiveness of the proposed method by comparing it with the conventional method, and the results demonstrate that the measurement by our method is consistent with that by the microscope. This also indicates that OCT with high axial resolution can potentially be used to measure the CC thickness accurately and nondestructively.

Development and progression of coronary atherosclerotic lesions is mediated by a number of cellular components that are not readily visualized using the current clinical investigation tools. Visualizing these cellular components in situ and in vivo may allow early detection of the vulnerable plaques, with implications for coronary artery disease therapy and for the prevention of acute myocardial infarction. In this paper, we have developed a fiber-optic micro-optical coherence tomography (μ OCT) probe for intravascular use. We conducted ex vivo imaging experiments in normal swine aorta and human atherosclerotic coronary arteries and demonstrated that the fiber-probe-based μ OCT could delineate not only the layered structures of arterial wall but also the cellular-level anatomical structures of atherosclerotic plaques, including foam cells and smooth muscle cells. These results demonstrate the feasibility of intravascular μ OCT imaging.

A novel method of pixel reassignment (PRA) is proposed to achieve transverse superresolution in the confocal microscopy. Inspired by it, for the first time, we report a pixel-reassigned spectral-domain optical coherence tomography (OCT) with ~1.5 times transverse resolution improvement both in numerical simulations and imaging experiments. PRA is implemented by transversely shifting the detection fiber from the on-axis position to five off-axis positions, capturing cross-sectional images at each shifting step of the detection fiber and digitally reassigning them together to give a sharper image with moderately extended depth of focus and enhanced intensity. So, we believe that the PRA technique will improve the imaging performance and be beneficial to the development of the OCT community.

In the present investigation, 48 new tertiary amine derivatives of cinnamic acid, phenylpropionic acid, sorbic acid and hexanoic acid (4d–6g, 10d–12g, 16d–18g and 22d–24g) were designed, synthesized and evaluated for the effect on AChE and BChE in vitro. The results revealed that the alteration of aminoalkyl types and substituted positions markedly influences the effects in inhibiting AChE. Almost of all cinnamic acid derivatives had the most potent inhibitory activity than that of other acid derivatives with the same aminoalkyl side chain. Unsaturated bond and benzene ring in cinnamic acid scaffold seems important for the inhibitory activity against AChE. Among them, compound 6g revealed the most potent AChE inhibitory activity (IC50 value: 3.64 µmol/L) and highest selectivity over BChE (ratio: 28.6). Enzyme kinetic study showed that it present a mixed-type inhibition against AChE. The molecular docking study suggested that it can bind with the catalytic site and peripheral site of AChE.

Abstract Diagnosis of corneal disease and challenges in corneal transplantation require comprehensive understanding of corneal anatomy, particularly that of the posterior cornea. Micro-optical coherence tomography (µOCT) is a potentially suitable tool to meet this need, owing to its ultrahigh isotropic spatial resolution, high image acquisition rate and depth priority scanning mode. In this study, we explored the ability of µOCT to visualize micro-anatomical structures of the posterior cornea ex vivo and in vivo using small and large animals. µOCT clearly delineated cornea layers and revealed micro-anatomical structures, including not only polygonal endothelial cells, stellate keratocytes, collagen fibres and corneal nerve fibres but also new structures such as the dome-shaped basolateral side of endothelial cells and lattice structures at the interface between endothelium and Descemet’s membrane. Based on these observations, a short post-harvest longitudinal study was conducted on rat cornea to test the feasibility of using µOCT to monitor the quality of endothelial cells. This study successfully reveals a series of morphological features and pathological changes in the posterior cornea at the cellular level in situ and in real time with µOCT. These findings enrich knowledge of corneal anatomy and suggest that µOCT may be a promising imaging tool in corneal transplantation.

Abstract Detecting early‐stage epithelial cancers and their precursor lesions are challenging as lesions could be subtle and focally or heterogeneously distributed over large mucosal areas. Optical coherence tomography (OCT) that enables wide‐field imaging of subsurface microstructures in vivo is a promising screening tool for epithelial diseases. However, its diagnostic capability has not been fully appreciated since the optical reflectance contrast is poorly understood. We investigated the back‐scattered intensities from clustered or packed nanometer scale intracellular scatterers using finite‐difference time‐domain method and 1‐μm resolution form of OCT, and uncovered that there existed correlations between the reflectance contrasts and the ultrastructural clustering or packing states of these scatterers, which allows us to interpret the physiological state of the cells. Specifically, both polarized goblet cells and foveolar cells exhibited asymmetric reflectance contrast, but they could be differentiated by the optical intensity of the mucin cup due to the different ultrastructural make‐ups of the mucin granules; keratinocytes could demonstrate varied cytoplasmic intensity and their cytoplasmic contrast was closely correlated with the packing state of keratin filaments. Further preliminary study demonstrated that these new understandings of OCT image contrast enables the characterization of precancerous lesions, which could complement the current morphology‐based criteria in realizing “virtual histology” and would have a profound impact for the screening and surveillance of epithelial cancers.

Objective: Our aim was to explore the engendering mechanism and gene targets for melanoma. Methods: The microarray data of GSE46517 were downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) between primary melanoma samples and normal controls were analyzed using the GEO2R online tool. The screened DEGs were mapped to a protein–protein interaction network based on the Search Tool for the Retrieval of Interacting Genes database. The functions and pathways involved with DEGs were analyzed using the Database for Annotation Visualization and Integrated Discovery software) online tools. Then, the DEGs were further annotated via the TRANSFAC, Tumor-Suppressor Gene, and Tumor-Associated Gene databases. Results: A total of 1095 DEGs including 511 upregulated genes and 584 down-regulated ones were screened out. The nodes of CCL5, ISG15, CDKN2A, EGFR, and ERBB2 showed a high connectivity degree in protein–protein interaction networks and were mainly enriched in Biological Process GO terms such as the regulation of catalytic activity and cell adhesion, as well as the pathways of cytochrome P450. The DEGs were classified into 31 transcription factors and 43 downregulated tumor associated genes. Conclusion: Catalytic activity, cell adhesion, and the cytochrome P450 associated pathways are dysregulated in the melanoma formation. The significant nodes such as ISG15, IRF4, ERBB2 and EGFP may be potential targets for primary melanoma treatment.

Microfabrication technologies have extensively advanced over the past decades, realizing a variety of well-designed compact devices for material synthesis, separation, analysis, monitoring, sensing, and so on. The performance of such devices has been undoubtedly improved, while it is still challenging to build up a platform by rationally combining multiple processes toward practical demands which become more diverse and complicated. Here, we present a simple and effective microfluidic system to produce and immobilize a well-defined functional material for on-chip permanganate (MnO4−) sensing. A droplet-based microfluidic approach that can continuously produce monodispersed droplets in a water-in-oil system is employed to prepare highly uniform microspheres (average size: 102 μm, coefficient of variation: 3.7%) composed of bovine serum albumin (BSA) hydrogel with autofluorescence properties in the presence of glutaraldehyde (GA). Each BSA hydrogel microsphere is subsequently immobilized in a microchannel with a hydrodynamic trapping structure to serve as an independent fluorescence unit. Various anions such as Cl−, NO3−, PO43−, Br−, BrO3−, ClO4−, SCN−, HCO3−, and MnO4− are individually flowed into the microchannel, resulting in significant fluorescence quenching only in the case of MnO4−. Linear correlation is confirmed at an MnO4− concentration from 20 to 80 μM, and a limit of detection is estimated to be 1.7 μM. Furthermore, we demonstrate the simultaneous immobilization of two kinds of different microspheres in parallel microchannels, pure BSA hydrogel microspheres and BSA hydrogel microspheres containing rhodamine B molecules, making it possible to acquire two fluorescence signals (green and yellow). The present microfluidics-based combined approach will be useful to record a fingerprint of complicated samples for sensing/identification purposes by flexibly designing the size and composition of the BSA hydrogel microspheres, immobilizing them in a desired manner and obtaining a specific pattern.

The mucosal microanatomy of the large intestine is characterized by the presence of crypts of Lieberkühn, which is associated predominantly with goblet cells. Such cellular-level intestinal microstructures undergo morphological changes during the progression of bowel diseases, such as colon cancer or ulcerative colitis. As an indicator of gastric cancers, intestinal metaplasia in the large intestine is characterized by the appearance of goblet cells in gastric epithelium, and therefore, visualization of intestinal microstructure changes in cross-sectional view, particularly in vivo, in a high-speed fashion would assist early disease diagnosis and its treatment. In this paper, we investigated the capability of micro-optical coherence tomography (μOCT) for high-speed cellular-level crypt and goblet cell structures imaging ex vivo and in vivo . The adopted μOCT system achieved a resolution of 2.0 μm in both the lateral and axial directions in air. Ex vivo and video-rate in vivo images acquired in 3-D at respective imaging rates of 20 and 60 frames/s are presented and compared with the histology images. Imaging results show that the detailed microstructures, such as the crypt lumen and the goblet cells, could be clearly identified and are also comparable with those in histology images. Such comparisons also indicate that high-resolution μOCT could be a powerful tool to perform “optical biopsy” in colorectal tissue. This is the first work, to the best of our knowledge, on cellular-level structure imaging in intestinal mucosa using spectral-domain OCT.

Plaque rupture is the critical cause of cardiovascular thrombosis, but the detailed mechanisms are not fully understood. Recent studies have found abundant cholesterol crystals in ruptured plaques, and it has been proposed that the rapid expansion of cholesterol crystals in a limited space during crystallization may contribute to plaque rupture. To evaluate the effect of cholesterol crystal growth on atherosclerotic plaques, we modeled the expansion of cholesterol crystals during the crystallization process in the necrotic core and estimated the stress on the thin cap with different arrangements of cholesterol crystals. We developed a two-dimensional finite element method model of atherosclerotic plaques containing expanding cholesterol crystals and investigated the effect of the magnitude and distribution of crystallization on the peak circumferential stress born by the cap. Using micro-optical coherence tomography (μOCT), we extracted the cross-sectional geometric information of cholesterol crystals in human atherosclerotic aorta tissue ex vivo and applied the information to the model. The results demonstrate that (1) the peak circumference stress is proportionally dependent on the cholesterol crystal growth; (2) cholesterol crystals at the cap shoulder impose the highest peak circumference stress; and (3) spatial distributions of cholesterol crystals have a significant impact on the peak circumference stress: evenly distributed cholesterol crystals exert less peak circumferential stress on the cap than concentrated crystals.

The presence of cholesterol crystals is a hallmark of atherosclerosis, but until recently, such crystals have been considered to be passive components of necrotic plaque cores. Recent studies have demonstrated that phagocytosis of cholesterol crystals by macrophages may actively precipitate plaque progression via an inflammatory pathway, emphasizing the need for methods to study the interaction between macrophages and crystalline cholesterol. In this study, we demonstrate the feasibility of detecting cholesterol in macrophages in situ using Micro-Optical Coherence Tomography (µOCT), an imaging modality we have recently developed with 1-µm resolution. Macrophages containing cholesterol crystals frequently demonstrated highly scattering constituents in their cytoplasm on µOCT imaging, and µOCT was able to evaluate cholesterol crystals in cultured macrophage cells. Our results suggest that µOCT may be useful for the detection and characterization of inflammatory activity associated with cholesterol crystals in the coronary artery.

We demonstrate the use of a high resolution form of optical coherence tomography, termed micro-OCT (μOCT), for investigating the functional microanatomy of airway epithelia. μOCT captures several key parameters governing the function of the airway surface (airway surface liquid depth, periciliary liquid depth, ciliary function including beat frequency, and mucociliary transport rate) from the same series of images and without exogenous particles or labels, enabling non-invasive study of dynamic phenomena. Additionally, the high resolution of μOCT reveals distinguishable phases of the ciliary stroke pattern and glandular extrusion. Images and functional measurements from primary human bronchial epithelial cell cultures and excised tissue are presented and compared with measurements using existing gold standard methods. Active secretion from mucus glands in tissue, a key parameter of epithelial function, was also observed and quantified.

Poly(L-lactide) was obtained from the ring-opening polymerization of L-lactide through a solvothermal process. Tin (II) chloride (SnC12) was used as the catalyst for the polymerization reaction. The focus of this paper was on the effect of solvents, catalyst usage, temperature, time, and antioxidants on the ring-opening reaction in the solvothermal synthesis. Ubbelohde viscometer, FTIR, GPC, and DSC were used to characterize the products. It is found that the optimal reaction condition for the highest molecular weight of PLA is at 160∘C for 10 hour with 0.4% SnCl2 in 10 mL toluene as solvent, and the high crystallinity can be obtained. The addition of antioxidant prior to the polymerization is conducive to obtaining high molecular weight and augment Tm, Tc and Xc values of PLA.