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The germination process of radish sprouts was investigated in detail using volumetric dynamic optical coherence tomography (OCT). Dynamic OCT involves the sequential acquisition of 16 OCT images and subsequent temporal variance analysis of each pixel, enabling non-invasive visualization of the cellular and tissue activities of plants. The radish sprouts were longitudinally investigated for up to 12 days, and changes in morphology and dynamic OCT image patterns were observed as the plants developed. The dynamic OCT signals in the vessels and growing roots were relatively high in the early stage of germination and decreased as the tissue matured. These results suggest that dynamic OCT is sensitive to water and nutrient transport as well as cellular activities associated with plant growth., (© 2024 The Author(s). Journal of Biophotonics published by Wiley‐VCH GmbH.)

The archaeal mevalonate pathway is a recently discovered modified version of the eukaryotic mevalonate pathway. This pathway is widely conserved in archaea, except for some archaeal lineages possessing the eukaryotic or other modified mevalonate pathways. Although the pathway seems almost exclusive to the domain Archaea, the whole set of homologous genes of the pathway is found in the metagenome-assembled genome sequence of an uncultivated bacterium, Candidatus Promineifilum breve, of the phylum Chloroflexota. To prove the existence of the archaea-specific pathway in the domain Bacteria, we confirmed the activities of the enzymes specific to the pathway, phosphomevalonate dehydratase and anhydromevalonate phosphate decarboxylase, because only these two enzymes are absent in closely related Chloroflexota bacteria that possess a different type of modified mevalonate pathway. The activity of anhydromevalonate phosphate decarboxylase was evaluated by carotenoid production via the archaeal mevalonate pathway reconstituted in Escherichia coli cells, whereas that of phosphomevalonate dehydratase was confirmed by an in vitro assay using the recombinant enzyme after purification and iron-sulfur cluster reconstruction. Phylogenetic analyses of some mevalonate pathway-related enzymes suggest an evolutionary route for the archaeal mevalonate pathway in Candidatus P. breve, which probably involves horizontal gene transfer events.IMPORTANCEThe recent discovery of various modified mevalonate pathways in microorganisms, such as archaea and Chloroflexota bacteria, has shed light on the complexity of the evolution of metabolic pathways, including those involved in primary metabolism. The fact that the archaeal mevalonate pathway, which is almost exclusive to the domain Archaea, exists in a Chloroflexota bacterium provides valuable insights into the molecular evolution of the mevalonate pathways and associated enzymes. Putative genes probably involved in the archaeal mevalonate pathway have also been found in the metagenome-assembled genomes of Chloroflexota bacteria. Such genes can contribute to metabolic engineering for the bioproduction of valuable isoprenoids because the archaeal mevalonate pathway is known to be an energy-saving metabolic pathway that consumes less ATP than other mevalonate pathways do., Competing Interests: The authors declare no conflict of interest.

Rationale: Autosomal recessive bestrophinopathy (ARB) is a subtype of bestrophinopathy caused by biallelic mutations of the BEST1 gene, which affect the retinal pigment epithelium (RPE). Studying RPE abnormalities through imaging is essential for understanding ARB. This case series involved the use of multimodal imaging techniques, namely autofluorescence (AF) imaging at 488 nm [short-wavelength AF] and 785 nm [near-infrared AF (NIR-AF)] and polarization-sensitive optical coherence tomography (PS-OCT), to investigate RPE changes in 2 siblings with ARB., Patient Concerns: Two Japanese siblings (Case 1: male, followed for 20-23 years; Case 2: female, followed for 13-17 years) carried compound heterozygous mutations of the BEST1 gene., Diagnosis: Both siblings were diagnosed with ARB., Interventions and Outcomes: Multimodal imaging techniques were used to evaluate RPE changes. Both siblings had funduscopic changes similar to those seen in the vitelliruptive stage of Best vitelliform macular dystrophy during the follow-up period. NIR-AF imaging showed hypo-AF of the entire macular lesion in both cases, and this hypo-AF remained stable over time. PS-OCT confirmed reduced RPE melanin content in these hypo-AF areas. Additionally, hyper-NIR-AF dots were observed within hypo-NIR-AF areas. Concomitant identification of focally thickened RPE melanin on PS-OCT imaging and hyper-AF on short-wavelength AF imaging at the sites containing hyper-NIR-AF dots indicated that the hyper-NIR-AF dots had originated from either stacked RPE cells or RPE dysmorphia., Lessons: We confirmed RPE abnormalities in ARB, including diffuse RPE melanin damage in the macula alongside evidence of RPE activity-related changes. This case series demonstrates that multimodal imaging, particularly NIR-AF and PS-OCT, provides detailed insights into RPE alterations in ARB., Competing Interests: M Miura received funding support from Santen, Alcon, Altos, and Sandoz and lecture fees from Santen, Kowa, Senju, and Novartis. S Makita and Y Yasuno received funding support from Topcon, Nikon, Yokogawa Electric, Sky Technology, and Kao. S Azuma and T Mino were employees of Topcon. T Hayashi received funding support from Alcon, Johnson & Johnson Vision, AMO, Daiichi Sankyo, Chugai, Santen, Mitsubishi Tanabe Pharma, Senju, Bayer, Otsuka, Kyowa Kirin, Ritz Medical, Uni-hite, and Kuribara. For S Kameya, no conflict of interest or funding support to disclose. K Tsunoda received funding support from Janssen F R and lecture fees from Janssen F R, Astellas, Novartis, Santen, Senju, Otsuka, and Ezai., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Yb(OTf) 3 promoted the Krapcho decarboxylation of 2,2-difluoro-3-oxopropanoate, and a subsequent aldol reaction was achieved. This process is the first example of generating difluoroenolates through a decarboxylation-type process, and a large number of carbonyl compounds are applicable to the aldol reaction. The protocol is a complete one-pot reaction that uses the bench-stable and nonhygroscopic 2,2-difluoro-3-oxopropanoate to generate the difluoroenolate. This strategy has been applied for the synthesis of CF 2 -containing bioactive GABA B agonists, contributing to drug design., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

We demonstrate a method that reduces the noise caused by multi-scattering (MS) photons in an in vivo optical coherence tomography image. This method combines a specially designed image acquisition (i.e., optical coherence tomography scan) scheme and subsequent complex signal processing. For the acquisition, multiple cross-sectional images (frames) are sequentially acquired while the depth position of the focus is altered for each frame by an electrically tunable lens. In the signal processing, the frames are numerically defocus-corrected, and complex averaged. Because of the inconsistency in the MS-photon trajectories among the different electrically tunable lens-induced defocus, this averaging reduces the MS signal. Unlike the previously demonstrated volume-wise multi-focus averaging method, our approach requires the sample to remain stable for only a brief period, approximately 70 ms, thus making it compatible with in vivo imaging. This method was validated using a scattering phantom and in vivo unanesthetized small fish samples, and was found to reduce MS noise even for unanesthetized in vivo measurement., Competing Interests: Y. Zhu, L. Zhu, Lim, Makita, Guo, Yasuno: Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F), Panasonic (F), Santec (F). L. Zhu is currently employed by Santec., (© 2024 Optica Publishing Group.)

Cirratiomycin, a heptapeptide with antibacterial activity, was isolated and characterized in 1981; however, its biosynthetic pathway has not been elucidated. It contains several interesting nonproteinogenic amino acids, such as (2S,3S)-2,3-diaminobutyric acid ((2S,3S)-DABA) and α-(hydroxymethyl)serine, as building blocks. Here, we report the identification of a cirratiomycin biosynthetic gene cluster in Streptomyces cirratus. Bioinformatic analysis revealed that several Streptomyces viridifaciens and Kitasatospora aureofaciens strains also have this cluster. One S. viridifaciens strain was confirmed to produce cirratiomycin. The biosynthetic gene cluster was shown to be responsible for cirratiomycin biosynthesis in S. cirratus in a gene inactivation experiment using CRISPR-cBEST. Interestingly, this cluster encodes a nonribosomal peptide synthetase (NRPS) composed of 12 proteins, including those with an unusual domain organization: a stand-alone adenylation domain, two stand-alone condensation domains, two type II thioesterases, and two NRPS modules that have no adenylation domain. Using heterologous expression and in vitro analysis of recombinant enzymes, we revealed the biosynthetic pathway of (2S,3S)-DABA: (2S,3S)-DABA is synthesized from l-threonine by four enzymes, CirR, CirS, CirQ, and CirB. In addition, CirH, a glycine/serine hydroxymethyltransferase homolog, was shown to synthesize α-(hydroxymethyl)serine from d-serine in vitro. These findings broaden our knowledge of nonproteinogenic amino acid biosynthesis., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

We demonstrate deep-learning neural network (NN)-based dynamic optical coherence tomography (DOCT), which generates high-quality logarithmic-intensity-variance (LIV) DOCT images from only four OCT frames. The NN model is trained for tumor spheroid samples using a customized loss function: the weighted mean absolute error. This loss function enables highly accurate LIV image generation. The fidelity of the generated LIV images to the ground truth LIV images generated using 32 OCT frames is examined via subjective image observation and statistical analysis of image-based metrics. Fast volumetric DOCT imaging with an acquisition time of 6.55 s/volume is demonstrated using this NN-based method., Competing Interests: Liu, El-Sadek, Makita, Yasuno: Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F), Panasonic (F). Mori, Furukawa, Matsusaka: None., (© 2024 Optica Publishing Group.)

We demonstrate a deep-learning-based scatterer density estimator (SDE) that processes local speckle patterns of optical coherence tomography (OCT) images and estimates the scatterer density behind each speckle pattern. The SDE is trained using large quantities of numerically simulated OCT images and their associated scatterer densities. The numerical simulation uses a noise model that incorporates the spatial properties of three types of noise, i.e., shot noise, relative-intensity noise, and non-optical noise. The SDE's performance was evaluated numerically and experimentally using two types of scattering phantom and in vitro tumor spheroids. The results confirmed that the SDE estimates scatterer densities accurately. The estimation accuracy improved significantly when compared with our previous deep-learning-based SDE, which was trained using numerical speckle patterns generated from a noise model that did not account for the spatial properties of noise., Competing Interests: T. Seesan, P. Mukherjee, I.A. El-Sadek, Y. Lim, L. Zhu, S. Makita, Y. Yasuno: Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F)., (© 2024 Optica Publishing Group.)

We demonstrate label-free dynamic optical coherence tomography (D-OCT)-based visualization and quantitative assessment of patterns of tumor spheroid response to three anti-cancer drugs. The study involved treating human breast adenocarcinoma (MCF-7 cell-line) with paclitaxel (PTX), tamoxifen citrate (TAM), and doxorubicin (DOX) at concentrations of 0 (control), 0.1, 1, and 10 µM for 1, 3, and 6 days. In addition, fluorescence microscopy imaging was performed for reference. The D-OCT imaging was performed using a custom-built OCT device. Two algorithms, namely logarithmic intensity variance (LIV) and late OCT correlation decay speed (OCDS[Formula: see text]) were used to visualize the tissue dynamics. The spheroids treated with 0.1 and 1 µM TAM appeared similar to the control spheroid, whereas those treated with 10 µM TAM had significant structural corruption and decreasing LIV and OCDS[Formula: see text] over treatment time. The spheroids treated with PTX had decreasing volumes and decrease of LIV and OCDS[Formula: see text] signals over time at most PTX concentrations. The spheroids treated with DOX had decreasing and increasing volumes over time at DOX concentrations of 1 and 10 µM, respectively. Meanwhile, the LIV and OCDS[Formula: see text] signals decreased over treatment time at all DOX concentrations. The D-OCT, particularly OCDS[Formula: see text], patterns were consistent with the fluorescence microscopic patterns. The diversity in the structural and D-OCT results among the drug types and among the concentrations are explained by the mechanisms of the drugs. The presented results suggest that D-OCT is useful for evaluating the difference in the tumor spheroid response to different drugs and it can be a useful tool for anti-cancer drug testing., (© 2024. The Author(s).)

The MN ring of Caribbean ciguatoxin C-CTX-1 was synthesized from a meso - syn -2,7-dimethyloxepane derivative corresponding to the M ring via desymmetrization by acetal formation with a camphor derivative, followed by construction of the N ring via the Horner-Wadsworth-Emmons reaction and acetal formation. The meso - syn -2,7-dimethyloxepane derivative was synthesized via photoinduced electrocyclization of a conjugated exo -diene under flow conditions, giving a cyclobutene derivative, followed by ring expansion via oxidative cleavage and diastereoselective reduction of a β-hydroxy ketone.

CsPT4 is an aromatic prenyltransferase that synthesizes cannabigerolic acid (CBGA), the key intermediate of cannabinoid biosynthesis in Cannabis sativa, from olivetolic acid (OA) and geranyl diphosphate (GPP). CsPT4 has a catalytic potential to produce a variety of CBGA analogs via regioselective C-prenylation of aromatic substrates having resorcylic acid skeletons including bibenzyl 2,4-dihydroxy-6-phenylethylbenzoic acid (DPA). In this study, we further investigated the substrate specificity of CsPT4 using phlorocaprophenone (PCP) and 2',4',6'-trihydroxydihydrochalcone (THDC), the isomers of OA and DPA, respectively, and demonstrated that CsPT4 catalyzed both C-prenylation and O-prenylation reactions on PCP and THDC that share acylphloroglucinol substructures. Interestingly, the kinetic parameters of CsPT4 for these substrates differed depending on whether they underwent C-prenylation or O-prenylation, suggesting that this enzyme utilized different substrate-binding modes suitable for the respective reactions. Aromatic prenyltransferases that catalyze O-prenylation are rare in the plant kingdom, and CsPT4 was notable for altering the reaction specificity between C- and O-prenylations depending on the skeletons of aromatic substrates. We also demonstrated that enzymatically synthesized geranylated acylphloroglucinols had potent antiausterity activity against PANC-1 human pancreatic cancer cells, with 4'-O-geranyl THDC being the most effective. We suggest that CsPT4 is a valuable catalyst to generate biologically active C- and O-prenylated molecules that could be anticancer lead compounds.

Polarization-sensitive optical coherence tomography (PS-OCT) is a promising biomedical imaging tool for the differentiation of various tissue properties. However, the presence of multiple-scattering (MS) signals can degrade the quantitative polarization measurement accuracy. We demonstrate a method to reduce MS signals and increase the measurement accuracy of Jones matrix PS-OCT. This method suppresses MS signals by averaging multiple Jones matrix volumes measured using different focal positions. The MS signals are decorrelated among the volumes by focus position modulation and are thus reduced by averaging. However, the single scattering signals are kept consistent among the focus-modulated volumes by computational refocusing. We validated the proposed method using a scattering phantom and a postmortem medaka fish. The results showed reduced artifacts in birefringence and degree-of-polarization uniformity measurements, particularly in deeper regions in the samples. This method offers a practical solution to mitigate MS-induced artifacts in PS-OCT imaging and improves quantitative polarization measurement accuracy., Competing Interests: L. Zhu, S. Makita, Y. Lim, Y. Zhu, Y. Yasuno: Yokogawa Electric Corp. (F), Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F). J. Tamaoki, M. Kobayashi: None., (© 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.)

Biologically active cannabinoids are derived from cannabigerolic acid (CBGA), which is biosynthesized by aromatic prenyltransferase CsPT4. We exploit the catalytic versatility of CsPT4 to synthesize various CBGA analogues, including a geranylated bibenzyl acid, the precursor to bibenzyl cannabinoids of liverwort origin. The synthesized natural and new-to-nature cannabinoids exhibit potent cytotoxicity in human pancreatic cancer cells. CsPT4 can artificially extend the cannabinoid biosynthetic diversity with novel and improved biological activities.

Purpose: The purpose of this study was to demonstrate the utility of polarization-diversity optical coherence tomography (PD-OCT), a noninvasive imaging technique with melanin-specific contrast, in the quantitative and qualitative assessment of choroidal nevi., Methods: Nevi were imaged with a custom-built 55-degree field-of-view (FOV) 400 kHz PD-OCT system. Imaging features on PD-OCT were compared to those on fundus photography, auto-fluorescence, ultrasound, and non-PD-OCT images. Lesions were manually segmented for size measurement and metrics for objective assessment of melanin distributions were calculated, including degree of polarization uniformity (DOPU), attenuation coefficient, and melanin occupancy rate (MOR)., Results: We imaged 17 patients (mean age = 69.5 years, range = 37-90) with 11 pigmented, 3 non-pigmented, and 3 mixed pigmentation nevi. Nevi with full margin acquisition had an average longest basal diameter of 5.1 mm (range = 2.99-8.72 mm) and average height of 0.72 mm (range = 0.37 mm-2.09 mm). PD-OCT provided clear contrast of choroidal melanin content, distribution, and delineation of nevus margins for melanotic nevi. Pigmented nevi were found to have lower DOPU, higher attenuation coefficient, and higher MOR than non-pigmented lesions. Melanin content on PD-OCT was consistent with pigmentation on fundus in 15 of 17 nevi (88%)., Conclusions: PD-OCT allows objective assessment of choroidal nevi melanin content and distribution. In addition, melanin-specific contrast by PD-OCT enables clear nevus margin delineation and may improve serial growth surveillance. Further investigation is needed to determine the clinical significance and prognostic value of melanin characterization by PD-OCT in the evaluation of choroidal nevi.

We investigated birefringence-derived artifacts that potentially mimic focal defects of the lamina cribrosa (focal LC defects) in optical coherence tomography (OCT) imaging of eyes with glaucoma. This study included 74 eyes of 48 patients with glaucoma. Five horizontal line B-scan images of the optic disc were obtained using commercial swept-source OCT. From a dataset of prototype swept-source polarization-diversity OCT, we calculated the following types of OCT images: polarization-dependent, polarization-dependent attenuation-coefficient, polarization-independent, and polarization-independent attenuation-coefficient. We assessed the commercial OCT images for the presence of birefringence-derived artifacts by comparison with the polarization-diversity OCT images. Commercial OCT showed suggestive findings of focal LC defects in 17 of 74 eyes. Reevaluation using polarization-independent OCT revealed that the focal LC defects in one of 17 eyes (5.9%) were actually birefringence-derived artifacts. This study demonstrated the existence of birefringence-derived artifacts mimicking focal LC defects in commercial OCT imaging and indicated that polarization-diversity OCT is an effective tool to evaluate the presence of these artifacts., (© 2023. Springer Nature Limited.)

The guest editors introduce a feature issue commemorating the 30th anniversary of Optical Coherence Tomography., Competing Interests: The authors declare that there are no conflicts of interest related to this article., (© 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.)

This study aims at demonstrating label-free drug-response-patterns assessment of different tumor spheroids and drug types by dynamic optical coherence tomography (D-OCT). The study involved human breast cancer (MCF-7) and colon cancer (HT-29) spheroids. The MCF-7 and HT-29 spheroids were treated with paclitaxel (Taxol; PTX) and the active metabolite of irinotecan SN-38, respectively. The drugs were applied with 0 (control), 0.1, 1, and 10 μM concentrations and the treatment durations were 1, 3, and 6 days. A swept-source OCT microscope equipped with a repeated raster scanning protocol was used to scan the spheroids. Logarithmic intensity variance (LIV) and late OCT correlation decay speed (OCDS[Formula: see text]) algorithms were used to visualize the tumor spheroid dynamics. LIV and OCDS[Formula: see text] images visualized different response patterns of the two types of spheroids. In addition, spheroid morphology, LIV, and OCDS[Formula: see text] quantification showed different time-courses among the spheroid and drug types. These results may indicate different action mechanisms of the drugs. The results showed the feasibility of D-OCT for the evaluation of drug response patterns of different cell spheroids and drug types and suggest that D-OCT can perform anti-cancer drug testing., (© 2023. Springer Nature Limited.)

Renal tubule has distinct metabolic features and functional activity that may be altered during kidney disease. In this paper, we present label-free functional activity imaging of renal tubule in normal and obstructed mouse kidney models using three-dimensional (3D) dynamic optical coherence tomography (OCT) ex vivo. To create an obstructed kidney model, we ligated the ureter of the left kidney for either 7 or 14 days. Two different dynamic OCT (DOCT) methods were implemented to access the slow and fast activity of the renal tubules: a logarithmic intensity variance (LIV) method and a complex-correlation-based method. Three-dimensional DOCT data were acquired with a 1.3 [Formula: see text]m swept-source OCT system and repeating raster scan protocols. In the normal kidney, the renal tubule appeared as a convoluted pipe-like structure in the DOCT projection image. Such pipe-like structures were not observed in the kidneys subjected to obstruction of the ureter for several days. Instead of any anatomical structures, a superficial high dynamics appearance was observed in the perirenal cortex region of the obstructed kidneys. These findings suggest that volumetric LIV can be used as a tool to investigate kidney function during kidney diseases., (© 2023. Springer Nature Limited.)

Multiple scattering is one of the main factors that limits the penetration depth of optical coherence tomography (OCT) in scattering samples. We propose a method termed multi-focus averaging (MFA) to suppress the multiple-scattering signals and improve the image contrast of OCT in deep regions. The MFA method captures multiple OCT volumes with various focal positions and averages them in complex form after correcting the varying defocus through computational refocusing. Because the multiple-scattering takes different trajectories among the different focal position configurations, this averaging suppresses the multiple-scattering signal. Meanwhile, the single-scattering takes a consistent trajectory regardless of the focal position configuration and is not suppressed. Hence, the MFA method improves the ratio between the single-scattering signal and multiple-scattering signal, resulting in an enhancement in the image contrast. A scattering phantom and a postmortem zebrafish were measured to validate the proposed method. The results showed that the contrast of intensity images of both the phantom and zebrafish were improved using the MFA method, such that they were better than the contrast provided by the standard single focus averaging method. The MFA method provides a cost-effective solution for contrast enhancement through multiple-scattering reduction in tissue imaging using OCT systems., Competing Interests: L. Zhu, Makita, Lichtenegger, Lim, Y. Zhu, Yasuno: Yokogawa Electric Corp. (F), Sky technology (F), Nikon (F), Kao Corp. (F), Topcon (F). Tamaoki, Kobayashi: None., (Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.)

A novel scanning protocol, ammonite scan, is proposed for widefield optical coherence tomography angiography (OCTA) and relative retinal blood flow velocity imaging in the human retina using variable interscan time analysis (VISTA). A repeated circle scan using a 400 kHz swept-source was employed to achieve an interscan time of 1.28 ms. The center of the repeated circular scan continuously moved spirally towards the peripheral region, ensuring an extended and adjustable scan range while preserving the short interscan time. Image artifacts due to eye movement were eliminated via extra motion-correction processing using data redundancy. The relative blood flow velocity in superficial and deep plexus layers was calculated from the VISTA image, and their ratio was used to explore the microvascular flow parameter in the healthy human eye., Competing Interests: Provisional patent application No. 63/278,609. TM: Topcon (E), YM: Topcon (E), MT: Topcon (E), AM: Topcon (E), AK: Topcon (E), MA: Topcon (E), SM: Topcon (F), Yokogawa Electric (F), Nikon (F), Sky Technology (F), Kao (F), YY: Topcon (F), Yokogawa Electric (F), Nikon (F), Sky Technology (F), Kao (F), HE: Topcon (F), JGF: Optovue (I, P), Topcon (F), IP related to VISTA-OCTA (P), (© 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.)

A new formulation of the lateral imaging process of point-scanning optical coherence tomography (OCT) and a new differential contrast method designed by using this formulation are presented. The formulation is based on a mathematical sample model called the dispersed scatterer model (DSM), in which the sample is represented as a material with a spatially slowly varying refractive index and randomly distributed scatterers embedded in the material. It is shown that the formulation represents a meaningful OCT image and speckle as two independent mathematical quantities. The new differential contrast method is based on complex signal processing of OCT images, and the physical and numerical imaging processes of this method are jointly formulated using the same theoretical strategy as in the case of OCT. The formula shows that the method provides a spatially differential image of the sample structure. This differential imaging method is validated by measuring in vivo and in vitro samples., Competing Interests: Tomita, Makita, Morishita, Abd El-Sadek, Mukherjee, Lichtenegger, Yasuno: Nikon (F), Sky Technology (F), Yokogawa Electric Corp. (F), Kao Corp. (F), Topcon (F). Fukutake: Nikon (E). Tamaoki, Bian, Kobayashi: None. Mori, Matsusaka: None., (Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.)

An organoid is a three-dimensional (3D) in vitro cell culture emulating human organs. We applied 3D dynamic optical coherence tomography (DOCT) to visualize the intratissue and intracellular activities of human induced pluripotent stem cells (hiPSCs)-derived alveolar organoids in normal and fibrosis models. 3D DOCT data were acquired with an 840-nm spectral domain optical coherence tomography with axial and lateral resolutions of 3.8 µm (in tissue) and 4.9 µm, respectively. The DOCT images were obtained by the logarithmic-intensity-variance (LIV) algorithm, which is sensitive to the signal fluctuation magnitude. The LIV images revealed cystic structures surrounded by high-LIV borders and mesh-like structures with low LIV. The former may be alveoli with a highly dynamics epithelium, while the latter may be fibroblasts. The LIV images also demonstrated the abnormal repair of the alveolar epithelium., Competing Interests: Morishita, Mukherjee, Abd El-Sadek, Lim, Makita, Tomita, Yasuno: Yokogawa Electric Corp. (F), Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F), Tomey Corp (F). Suzuki: Chugai Pharmaceutical Co, Ltd (R), Nippon Boehringer Ingelheim (R), Sysmex Corporation (R). Lichtenegger: None. Yamamoto: HiLung Inc. (I, P). Nagamoto: HiLung Inc. (I)., (Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.)

We previously reported that the IL-2 Luc LTT can detect immunosuppressive effects of drugs that are attributed to their antimitotic activity. Here, we report an official validation study of the IL-2 Luc LTT. In the Phase I study that evaluated five coded chemicals, the within-laboratory reproducibility of three independent laboratories was 100.0%. In the combined results of the Phase I and II studies that evaluated 20 coded chemicals, the between-laboratory reproducibility was 92.0%. When compared with the reference data based on the previously-reported immunotoxicological information, the predictivity of the combined Phase I and II studies was 76.0% for Lab A and 72.0% for Labs B and C. In contrast, in the study in which the lead laboratory examined 37 non-pharmaceutical chemicals, the predictivity of the IL-2 Luc LTT and the IL-2 Luc assay was 48.6% and 64.9%, respectively, whereas that of the combined assays was 74.3%. It is clear that an integrated approach combining multiple assays is necessary for the development of in vitro immunosuppression testing. These data suggest that the IL-2 Luc LTT alone is not sufficient as a component of the integrated approach, but the combination of the IL-2 Luc assay and IL-2 Luc LTT is promising., Competing Interests: Declaration of Competing Interest None., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Degree of polarization uniformity (DOPU) imaging obtained by polarization-sensitive optical coherence tomography (PS-OCT) has the potential to provide biomarkers for retinal diseases. It highlights abnormalities in the retinal pigment epithelium that are not always clear in the OCT intensity images. However, a PS-OCT system is more complicated than conventional OCT. We present a neural-network-based approach to estimate the DOPU from standard OCT images. DOPU images were used to train a neural network to synthesize the DOPU from single-polarization-component OCT intensity images. DOPU images were then synthesized by the neural network, and the clinical findings from ground truth DOPU and synthesized DOPU were compared. There is a good agreement in the findings for RPE abnormalities: recall was 0.869 and precision was 0.920 for 20 cases with retinal diseases. In five cases of healthy volunteers, no abnormalities were found in either the synthesized or ground truth DOPU images. The proposed neural-network-based DOPU synthesis method demonstrates the potential of extending the features of retinal non-PS OCT., Competing Interests: SM, YY: Topcon (F), Yokogawa Electric (F), Nikon (F), Sky Technology (F), Kao (F). MM: Santen (F). SA, TM: Topcon (E)., (© 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.)

The recent discovery of the archaeal modified mevalonate pathway revealed that the fundamental units for isoprenoid biosynthesis (isopentenyl diphosphate and dimethylallyl diphosphate) are biosynthesized via a specific intermediate, trans -anhydromevalonate phosphate. In this biosynthetic pathway, which is unique to archaea, the formation of trans -anhydromevalonate phosphate from ( R )-mevalonate 5-phosphate is catalyzed by a key enzyme, phosphomevalonate dehydratase. This archaea-specific enzyme belongs to the aconitase X family within the aconitase superfamily, along with bacterial homologs involved in hydroxyproline metabolism. Although an iron-sulfur cluster is thought to exist in phosphomevalonate dehydratase and is believed to be responsible for the catalytic mechanism of the enzyme, the structure and role of this cluster have not been well characterized. Here, we reconstructed the iron-sulfur cluster of phosphomevalonate dehydratase from the hyperthermophilic archaeon Aeropyrum pernix to perform biochemical characterization and kinetic analysis of the enzyme. Electron paramagnetic resonance, iron quantification, and mutagenic studies of the enzyme demonstrated that three conserved cysteine residues coordinate a [4Fe-4S] cluster-as is typical in aconitase superfamily hydratases/dehydratases, in contrast to bacterial aconitase X-family enzymes, which have been reported to harbor a [2Fe-2S] cluster., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Komeyama, Kanno, Mino, Yasuno, Shinada, Ito and Hemmi.)

The zebrafish is an established vertebrae model in the field of biomedical research. With its small size, rapid maturation time and semi-transparency at early development stages, it has proven to be an important animal model, especially for high-throughput studies. Three-dimensional, high-resolution, non-destructive and label-free imaging techniques are perfectly suited to investigate these animals over various development stages. Optical coherence tomography (OCT) is an interferometric-based optical imaging technique that has revolutionized the diagnostic possibilities in the field of ophthalmology and has proven to be a powerful tool for many microscopic applications. Recently, OCT found its way into state-of-the-art zebrafish-based research. This review article gives an overview and a discussion of the relevant literature and an outlook for this emerging field., Competing Interests: Y. Yasuno: Yokogawa Electric Corp. (F), Sky technology (F), Nikon (F), Kao Corp. (F), Topcon (F). A. Lichtenegger, B. Baumann: None.

Background: Sleep is one of the most important health-related factors. This cross-sectional study focused on sleep quality relates to systemic symptoms, including dental symptoms. Methods: Resource data were compiled from 7995 men and women aged 30 to 69 years, which is the core of the Japanese working population. The subjects were divided into four groups based on their answers to two questions, one on sleep time and one on sleep sufficiency, and groups were compared with other items in the questionnaire by means of a contingency table analysis (χ2 test). Results: Relationships were found between the sleep groups and basic attributes, the presence of subjective symptoms, and the presence of hospital visits. The items with significant relationships included 14 symptoms, such as lower back pain (p < 0.01) and four diseases, including high blood pressure (p < 0.01). A multinomial logistic regression was conducted with the sleep groups as objective variables. In the poor sleep group, significant odds ratios were found for four items, including hours of work (odds ratio: 2.53) and feeling listless (2.01). Conclusions: The results allowed multiple symptoms and diseases related to sleep quality to be identified, and different trends in the response rates of the groups were found. These results suggest that the useful classification of sleep quality groups according to health problems contributes to understanding the effects of different symptoms.

We investigated birefringence-derived scleral artifacts in optical coherence tomography (OCT) images of eyes with pathologic myopia. This study included 76 eyes of 42 patients with pathologic myopia. Five sets of OCT B-scan images of the macula were obtained using commercial swept-source OCT. A dataset of prototype swept-source polarization-diversity OCT images was used to identify polarization-dependent OCT images (i.e., complex averaging of OCT signals from two polarization channels) and polarization-independent OCT images (i.e., intensity averaging of two OCT signals). Polarization-dependent OCT images and commercial OCT images were assessed for the presence of birefringence-derived artifacts by comparison with polarization-independent OCT images. Both polarization-dependent OCT images and commercial OCT images contained scleral vessel artifacts. Scleral vessel artifacts were present in 46 of 76 eyes (60.5%) imaged by polarization-dependent OCT and 17 of 76 eyes (22.4%) imaged by commercial OCT. The proportion of images that showed scleral vessel artifacts was significantly greater among polarization-dependent OCT images than among commercial OCT images (P < 0.001). Additionally, polarization-dependent OCT images showed low-intensity band artifacts. This study demonstrated the existence of birefringence-derived scleral artifacts in commercial OCT images and indicated that polarization-diversity OCT is an effective tool to evaluate the presence of these artifacts., (© 2022. The Author(s).)

Breast cancer is a leading cause of death in female patients worldwide. Further research is needed to get a deeper insight into the mechanisms involved in the development of this devastating disease and to find new therapy strategies. The zebrafish is an established animal model, especially in the field of oncology, which has shown to be a promising candidate for pre-clinical research and precision-based medicine. To investigate cancer growth in vivo in zebrafish, one approach is to explore xenograft tumor models. In this article, we present the investigation of a juvenile xenograft zebrafish model using a Jones matrix optical coherence tomography (JM-OCT) prototype. Immunosuppressed wild-type fish at 1-month post-fertilization were injected with human breast cancer cells and control animals with phosphate buffered saline in the tail musculature. In a longitudinal study, the scatter, polarization, and vasculature changes over time were investigated and quantified in control versus tumor injected animals. A significant decrease in birefringence and an increase in scattering signal was detected in tumor injected zebrafish in comparison to the control once. This work shows the potential of JM-OCT as a non-invasive, label-free, three-dimensional, high-resolution, and tissue-specific imaging tool in pre-clinical cancer research based on juvenile zebrafish models., (© 2022. The Author(s).)

Optical coherence tomography (OCT) is a high-speed non-invasive cross-sectional imaging technique. Although its imaging speed is high, three-dimensional high-spatial-sampling-density imaging of in vivo tissues with a wide field-of-view (FOV) is challenging. We employed convolved Lissajous and slow circular scanning patterns to extend the FOV of retinal OCT imaging with a 1-µm, 100-kHz-sweep-rate swept-source OCT prototype system. Displacements of sampling points due to eye movements are corrected by post-processing based on a Lissajous scan. Wide FOV three-dimensional retinal imaging with high sampling density and motion correction is achieved. Three-dimensional structures obtained using repeated imaging sessions of a healthy volunteer and two patients showed good agreement. The demonstrated technique will extend the FOV of simple point-scanning OCT, such as commercial ophthalmic OCT devices, without sacrificing sampling density., Competing Interests: SM: Topcon (F), Tomey (P), Yokogawa Electric (F), Nikon (F), Sky Technology (F), Kao (F). MM: Santen (F). SA: Topcon (E). TM: Topcon (E). TY: Topcon (E). YY: Topcon (F), Tomey (P), Yokogawa Electric (F), Nikon (F), Sky Technology (F), Kao (F)., (© 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.)

Label-free metabolic imaging of non-alcoholic fatty liver disease (NAFLD) mouse liver is demonstrated ex vivo by dynamic optical coherence tomography (OCT). The NAFLD mouse is a methionine choline-deficient (MCD)-diet model, and two mice fed the MCD diet for 1 and 2 weeks are involved in addition to a normal-diet mouse. The dynamic OCT is based on repeating raster scan and logarithmic intensity variance (LIV) analysis that enables volumetric metabolic imaging with a standard-speed (50,000 A-lines/s) OCT system. Metabolic domains associated with lipid droplet accumulation and inflammation are clearly visualized three-dimensionally. Particularly, the normal-diet liver exhibits highly metabolic vessel-like structures of peri-vascular hepatic zones. The 1-week MCD-diet liver shows ring-shaped highly metabolic structures formed with lipid droplets. The 2-week MCD-diet liver exhibits fragmented vessel-like structures associated with inflammation. These results imply that volumetric LIV imaging is useful for visualizing and assessing NAFLD abnormalities., Competing Interests: Mukherjee, El-Sadek, Zhu, Morishita, Lichtenegger: Yokogawa Electric Corp. (F), Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F). Makita, Yasuno: Yokogawa Electric Corp. (F), Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F), Tomey Corp (P). Okada: None. Miyazawa: Sky Technology (E). Fukuda, Lukmanto, Yamashita: None. Oshika: Topcon (F), Tomey Corp (F)., (Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.)

Terpene synthase (TS) from Bacillus alcalophilus (BalTS) is the only Class IB TS for which a 3D structure has been elucidated. Recently, geranyl-β-phellandrene, a novel cyclic diterpene, was identified as a product of BalTS in addition to the acyclic β-springene. In the present study, we have provided insight into the mechanism of geranyl-β-phellandrene formation. Deuterium labeling experiments revealed that the compound is produced via a 1,3-hydride shift. In addition, nonenzymatic reactions using divalent metal ions were performed. The enzyme is essential for the geranyl-β-phellandrene formation. Furthermore, BalTS variants targeting tyrosine residues enhanced the yield of geranyl-β-phellandrene and the proportion of the compound of the total products. It was suggested that the expansion of the active site space may allow the conformation of the intermediates necessary for cyclization. The present study describes the first Class IB TSs to successfully alter product profiles while retaining high enzyme activity., (© The Author(s) 2022. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

Collective total syntheses of trans -anhydromevalonic acid (tAHMA) and trans -anhydromevalonyl (tAHM) group-containing natural products (pestalotiopin A, pestalotiopamide C, pestalotiopamide D, farinomalein E, eleutherazine B, and trichocyclodipeptide A) were achieved using tAHMA esters as key intermediates. To this end, tAHMA tert -butyl ester was newly prepared by Z -vinyltosylation of tert -butyl 3-oxo-5-((triisopropylsilyl)oxy)pentanoate followed by the Negishi cross-coupling reaction with Me 2 Zn. tAHMA esters were converted to the target natural products via esterification or amidation. Comparison of the spectroscopic data of synthetic and natural products confirmed the E -configuration of the tAHM moieties in the natural products.

Here we demonstrate a long-depth-of-focus imaging method using polarization sensitive optical coherence tomography (PS-OCT). This method involves a combination of Fresnel-diffraction-model-based phase sensitive computational refocusing and Jones-matrix based PS-OCT (JM-OCT). JM-OCT measures four complex OCT images corresponding to four polarization channels. These OCT images are computationally refocused as preserving the mutual phase consistency. This method is validated using a static phantom, postmortem zebrafish, and ex vivo porcine muscle samples. All the samples demonstrated successful computationally-refocused birefringence and degree-of-polarization-uniformity (DOPU) images. We found that defocusing induces polarization artifacts, i.e., incorrectly high birefringence values and low DOPU values, which are substantially mitigated by computational refocusing., Competing Interests: Zhu, Oikawa, Mukerjee, Lichtenegger: Yokogawa Electric Corp. (F), Sky technology (F), Nikon (F), Kao Corp. (F), Topcon (F). Oida: Yokogawa Electric Corp. (F), Sky technology (F), Nikon (F), Kao Corp. (F), Topcon (F), Think-Lands Co., Ltd (E). Miyazawa: Yokogawa Electric Corp. (F), Sky technology (F, E), Nikon (F), Kao Corp. (F), Topcon (F). Makita, Yasuno: Yokogawa Electric Corp. (F), Sky technology (F), Nikon (F), Kao Corp. (F), Topcon (F), Tomey Corp (P)., (Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.)

Thyroid hormones are critical regulators of vertebrate development and metabolism. Under hyperthyroid conditions, excess thyroid hormones induce expression of several enzymes and activities via activation of ligand-bound thyroid hormone receptors (TRs). Arginase (ARG) is downstream of a ligand-bound TR and overexpression of ARG2 induces the production of reactive oxygen species and subsequent exacerbation of kidney ischemia/reperfusion (I/R) injury. To clarify the association between I/R-induced kidney injury and hyperthyroidism, mice were pretreated with L-thyroxine (LT4) or vehicle alone, then subjected to I/R. Proximal tubular cell-specific conditional knockout of thyroid hormone receptor β (TRβcKO) mice was generated and the effects of I/R were analyzed. Hyperthyroidism enhanced tubular damage and fibrosis in the kidneys of mice after I/R. Hyperthyroidism induced tubular cell necroptosis following inflammatory cell accumulation in the kidney after I/R. ARG2 expressions and reactive oxygen species accumulated in the kidneys of hyperthyroid mice after I/R, but these changes were ameliorated in the kidneys of TRβcKO mice. Hyperthyroidism-enhanced kidney injury was ameliorated in the kidney of TRβcKO mice after I/R. These results suggest that excess thyroid hormones are disadvantageous for the kidney under ischemic stress. Overt hypothyroidism represents a severe thyroid hormone deficiency disease that requires LT4 treatment, while overreplacement or iatrogenic thyrotoxicosis might cause kidney injury.

In recent years, conjugated microporous polymers (CMPs) have become important precursors for environmental and energy applications, compared with inorganic electrode materials, due to their ease of preparation, facile charge storage process, π-conjugated structures, relatively high thermal and chemical stability, abundance in nature, and high surface areas. Therefore, in this study, we designed and prepared new benzobisthiadiazole (BBT)-linked CMPs (BBT-CMPs) using a simple Sonogashira couplings reaction by reaction of 4,8-dibromobenzo(1,2-c;4,5-c')bis(1,2,5)thiadiazole (BBT-Br 2 ) with ethynyl derivatives of triphenylamine (TPA-T), pyrene (Py-T), and tetraphenylethene (TPE-T), respectively, to afford TPA-BBT-CMP, Py-BBT-CMP, and TPE-BBT-CMP. The chemical structure and properties of BBT-CMPs such as surface areas, pore size, surface morphologies, and thermal stability using different measurements were discussed in detail. Among the studied BBT-CMPs, we revealed that TPE-BBT-CMP displayed high degradation temperature, up to 340 °C, with high char yield and regular, aggregated sphere based on thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. Furthermore, the Py-BBT-CMP as organic electrode showed an outstanding specific capacitance of 228 F g -1 and superior capacitance stability of 93.2% (over 2000 cycles). Based on theoretical results, an important role of BBT-CMPs, due to their electronic structure, was revealed to be enhancing the charge storage. Furthermore, all three CMP polymers featured a high conjugation system, leading to improved electron conduction and small bandgaps.

The zebrafish is a valuable vertebrate animal model in pre-clinical cancer research. A Jones matrix optical coherence tomography (JM-OCT) prototype operating at 1310 nm and an intensity-based spectral-domain OCT setup at 840 nm were utilized to investigate adult wildtype and a tumor-developing zebrafish model. Various anatomical features were characterized based on their inherent scattering and polarization signature. A motorized translation stage in combination with the JM-OCT prototype enabled large field-of-view imaging to investigate adult zebrafish in a non-destructive way. The diseased animals exhibited tumor-related abnormalities in the brain and near the eye region. The scatter intensity, the attenuation coefficients and local polarization parameters such as the birefringence and the degree of polarization uniformity were analyzed to quantify differences in tumor versus control regions. The proof-of-concept study in a limited number of animals revealed a significant decrease in birefringence in tumors found in the brain and near the eye compared to control regions. The presented work showed the potential of OCT and JM-OCT as non-destructive, high-resolution, and real-time imaging modalities for pre-clinical research based on zebrafish., Competing Interests: Abd El-Sadek, Mukherjee, Zhu, Morishta, Tomita, Yokogawa Electric Corp. (F), Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F). Oida: Think-Lands Co., Yokogawa Electric Corp. (F), Sky Technology (F), Nikon (F), Kao Corp. (F), Topcon (F).Makita, Yasuno: Yokogawa Electric Corp. (F), Sky technology (F), Nikon (F), Kao Corp. (F), Topcon (F), Tomey Corp (P). Lichtenegger, Baumann, Kirchberger, Distel, Leskovar: None., (Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.)

In this study, the choroidal melanin content in healthy eyes was evaluated with polarization-sensitive optical coherence tomography (PS-OCT). We evaluated 105 healthy eyes of 105 Japanese subjects. The mean thickness of melanin-containing tissue in the choroid (thickness of MeCh) and the choroidal melanin occupancy rate within a 5-mm circular region from the foveal center were calculated using the degree of polarization uniformity obtained by PS-OCT and compared with the choroidal thickness, patient age, and axial length. To evaluate regional variations, the 5-mm circular region was divided into a center area and an outer ring area, and the outer ring area was further divided into four areas (nasal, temporal, superior, and inferior). The mean thickness of MeCh showed a significant positive correlation with the choroidal thickness. The mean choroidal melanin occupancy rate showed a significant positive correlation with age. The mean choroidal melanin occupancy rate of the center area was significantly larger than that of the outer ring area. The mean thickness of MeCh and choroidal melanin occupancy rate of the nasal area were significantly lower than those of other areas. The distribution of melanin-containing tissue in the choroid varies significantly with age and location., (© 2022. The Author(s).)

In this study, sunset glow fundus was evaluated in patients with Vogt-Koyanagi-Harada (VKH) disease using polarization-sensitive optical coherence tomography (PS-OCT). We evaluated 40 VKH eyes (20 patients) and 59 healthy eyes (59 age-matched controls). VKH eyes were divided into three groups according to color fundus images: sunset (17 eyes), potential sunset (13 eyes), and non-sunset (10 eyes). Choroidal melanin thickness (ChMeT) and the choroidal melanin thickness ratio (ChMeTratio) were calculated based on the degree of polarization uniformity from PS-OCT. ChMeT was significantly lower in sunset eyes than in non-sunset or control eyes (P = 0.003). The ChMeTratios of sunset or potential sunset eyes were significantly lower than those of non-sunset or control eyes (P = 0.04). Regional evaluation of ChMeT and the ChMeTratio showed that choroidal depigmentation predominantly occurred in the macula's outer ring area (P = 0.002). The areas under receiver operating characteristic curves discriminating combined sunset (sunset and potential sunset) from non-sunset eyes were 0.983 and 0.997 for ChMeT and the ChMeTratio, respectively. Time course evaluation of 12 eyes from disease onset showed that ChMeT and the ChMeTratio significantly decreased over time. PS-OCT may be useful for objectively evaluating choroidal depigmentation in patients with VKH disease., (© 2022. The Author(s).)