Publications by authors named "Okitsu T"

The first lactam-type 2-iodobenzamide catalysts, 8-iodoisoquinolinones 8 (IB-lactam) and 9 (MeO-IB-lactam), were developed. These catalysts have a conformationally rigid 6/6 bicyclic lactam structure and are more reactive than the previously reported catalysts 2-iodobenzamides 4 (IBamide) and 5 (MeO-IBamide) for the oxidation of alcohols. The lactam structure could form an efficient intramolecular I---O interaction, depending on the size of the lactam ring.

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A BF-mediated domino dehydration/electrophilic cyclization of silylalkynols to form 2,3-fused tricyclic benzofulvenes was achieved. In the latter step, in situ generated BF·OH enables the electrophilic activation of alkynes. The predominant -selectivity of the reaction is also discussed.

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TAT rhodopsin extracted from the marine bacterium SAR11 HIMB114 has a characteristic Thr-Ala-Thr motif and contains both protonated and deprotonated states of Schiff base at physiological pH conditions due to the low p Here, using solid-state NMR spectroscopy, we investigated the C and N NMR signals of retinal in only the protonated state of TAT in the 1-palmitoyl-2-oleoyl--glycero-3-phosphoethanolamine/1-palmitoyl-2-oleoyl--glycero-3-phospho (1'-rac-glycerol) (POPE/POPG) membrane at weakly acidic conditions. In the C NMR spectrum of C retinal-labeled TAT rhodopsin, the isolated 14-C signals of 13-/15- and 13-/15- isomers were observed at a ratio of 7:3. N retinal protonated Schiff base (RPSB) had a significantly higher magnetic field resonance at 160 ppm.

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The oxidative cleavage reaction of pyrrolidine-2-methanols to γ-lactams has been described. In this reaction, [4-iodo-3-(isopropylcarbamoyl)phenoxy]acetic acid and powdered Oxone (2KHSO·KHSO·KSO) were employed as the catalyst and co-oxidant, respectively. The reaction is efficient and environmentally benign because it produces various lactams from readily available substrates in moderate to excellent yields using organocatalyst and inorganic non-toxic co-oxidant.

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Dearomative intramolecular Diels-Alder/sulfur extrusion reaction of thiophenes with alkynes successfully afforded fluoranthenes in moderate to excellent yields. The proximity of both reactive sites fixed at the peri-position of naphthalene would play an important role in the progress of this reaction. Tri(o-tolyl)phosphine effectively suppressed the side reactions as a sulfur scavenger.

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Heliorhodopsin (HeR) is a seven-helical transmembrane protein with a retinal chromophore that corresponds to a new rhodopsin family. HeR from the archaebacterium Thermoplasmatales archaeon (TaHeR) exhibits unique features, such as the inverted protein orientation in the membrane compared to other rhodopsins and a long photocycle. Here, we used solid-state nuclear magnetic resonance (NMR) spectroscopy to investigate the C and N NMR signals of the retinal chromophore and protonated Schiff base (RPSB) in TaHeR embedded in POPE/POPG membrane.

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Diabetes mellitus (DM) is a complex disease with high prevalence of comorbidity and mortality. DM is predicted to reach more than 700 million people by 2045. In recent years, several advanced in vitro models and analytical tools were developed to investigate the pancreatic tissue response to pathological situations and identify therapeutic solutions.

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Primary hepatocytes are essential cellular resources for drug screening and medical transplantation. While culture systems have already succeeded in reconstituting the biomimetic microenvironment of primary hepatocytes, acquiring additional capabilities to handle them easily as well as to expand them remains unmet needs. This paper describes a culture system for primary rat hepatocytes, based on cell fiber technology, that brings scalability and handleability.

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Bacteriorhodopsin (BR) functions as a light-driven proton pump that transitions between different states during the photocycle, such as (AT; BR568) and 13-, 15- (CS; BR548) state and K, L, M, M, N, and O intermediates. In this study, we used in situ photoirradiation C solid-state NMR to observe a variety of photo-intermediates and photoreaction pathways in [20-C]retinal-WT-BR and its mutant [20-C, 14-C]retinal-D96N-BR. In WT-BR, the CS state converted to the CS* intermediate under photoirradiation with green light at -20 °C and consequently converted to the AT state in the dark.

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Background: Mobile health (mHealth) interventions, a more cost-effective approach compared with traditional methods of delivering lifestyle coaching in person, have been shown to improve physical parameters and lifestyle behavior among overweight populations. In Japan, the Specific Health Checkups and Specific Health Guidance (SHG) started in 2008 to treat obesity and abdominal obesity. However, the effectiveness of SHG is limited owing to its in-person counseling.

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Middle rhodopsin (MR) found from the archaeon is evolutionarily located between two different types of rhodopsins, bacteriorhodopsin (BR) and sensory rhodopsin II (SRII). Some isomers of the chromophore retinal and the photochemical reaction of MR are markedly different from those of BR and SRII. In this study, to obtain the structural information regarding its active center (i.

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Upon sensing nitrate, NODULE INCEPTION (NIN)-like protein (NLP) transcription factors alter gene expression to promote nitrate uptake and utilization. Of the nine NLPs in Arabidopsis, the physiological roles of only three NLPs (NLP6-NLP8) have been characterized to date. To evaluate the unique and redundant roles of Arabidopsis NLPs, we assessed the phenotypes of single and higher order nlp mutants.

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Background: Evolutionary transitions from terrestrial to aquatic life history cause drastic changes in sensory systems. Indeed, the drastic changes in vision have been reported in many aquatic amniotes, convergently. Recently, the opsin genes of the full-aquatic sea snakes have been reported.

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Microneedle (MN) is a key technology of the biomedical engineering field due to its capability of accessing the biological information in a minimally invasive manner. One of the huge demands for next-generation healthcare monitoring is continuous monitoring, especially of blood glucose concentration. For this, MN should be kept inserted into the human skin for a certain period of time, enduring stresses induced by daily human motion and at the same time measuring biomarkers in ISF.

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Hydrogel glucose sensors with boronic acid-based fluorescence intensity theoretically hold promise to improve in vivo continuous glucose monitoring (CGM) by facilitating long-lasting accuracy. However, these sensors generally degrade after implantation and the fluorescence intensity decreases immediately over time. Herein, we describe a hydrogel glucose sensor with in vivo stability based on boronic acid-based fluorescence intensity, integrating two antioxidant enzymes, superoxide dismutase (SOD), and catalase.

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Transplantation technologies of pancreatic islets as well as stem cell-derived pancreatic beta cells encapsulated in hydrogel for the induction of immunoprotection could advance to treat type 1 diabetes mellitus, if the hydrogel transplants acquire retrievability through mitigating foreign body reactions after transplantation. Here, we demonstrate that the diameter of the fiber-shaped hydrogel transplants determines both in vivo cellular deposition onto themselves and their retrievability. Specifically, we found that the in vivo cellular deposition is significantly mitigated when the diameter is 1.

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Organ-on-chip technology is a promising tool for investigating physiological in vitro responses in drug screening development, and in advanced disease models. Within this framework, we investigated the behavior of rat islets of Langerhans in an organ-on-chip model. The islets were trapped by sedimentation in a biochip with a microstructure based on microwells, and perfused for 5 days of culture.

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Dearomative ipso-iodocyclization of 4-(1-ethoxyethoxy)-N-propargylanilines leading to 1-azaspiro[4.5]deca-3,6,9-trien-8-ones has been developed. This reaction is characterized by the yield of fewer toxic byproducts and is conducted by a more user-friendly protocol compared to other reported methods.

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Collagenase products are crucial to isolate primary cells in basic research and clinical therapies, where their stability in collagenolytic activity is required. However, currently standard collagenase products from Clostridium histolyticum lack such stability. Previously, we produced a recombinant 74-kDa collagenase from Grimontia hollisae, which spontaneously became truncated to ~60 kDa and possessed no stability.

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In optogenetics, red-shifted channelrhodopsins (ChRs) are eagerly sought. We prepared six kinds of new chromophores with one double bond inserted into the polyene side chain of retinal (A1) or 3,4-didehydroretinal (A2), and examined their binding efficiency with opsins (ReaChR and ChrimsonR). All analogs bound with opsins to afford new ChRs.

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We developed an acid-free p-dimethylaminocinnamaldehyde (DMAC) solution containing silicone oil that was suitable for spraying on clothing for analysis of biological samples such as touch DNA. We investigated the effect of this solution and irradiation with blue light emitting diode (LED) light on short tandem repeat (STR) analysis. To examine the effect of adding acid to the DMAC solution on visualizing biological samples, saliva sample was deposited on T-shirt.

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The collagenase secreted by strain 1706B is a 74 kDa protein that consists of two parts: the catalytic module and a C-terminal segment that includes the bacterial pre-peptidase C-terminal domain. Here, we produced a recombinant C-terminal segment protein and examined its ability to bind collagen and other characteristics as compared with collagen-binding domains (CBDs) derived from () collagenases; these CBDs are the only ones thus far identified in bacterial collagenases. We found that the C-terminal segment binds to collagen only when the collagen is in its triple-helical conformation.

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Iodocyclization of silyl group-substituted homopropargylic carbamates and amides proceeded via 6-exo-dig mode to afford 6-vinylene-4,5-dihydro-1,3-oxazines in moderate to quantitative yields. This is the first report for silyl group-solely directed iodocyclization of alkynes utilizing the β-silyl effect. Under these mild reaction conditions, various functionalities such as secondary alcohol, acetal, urea, and sulfide were tolerated.

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As optogenetic studies become more popular, the demand for red-shifted channelrhodopsin is increasing, because blue-green light is highly scattered or absorbed by animal tissues. In this study, we developed a red-shifted channelrhodopsin by elongating the conjugated double-bond system of the native chromophore, all -trans-retinal (ATR1). Analogues of ATR1 and ATR2 (3,4-didehydro-retinal) in which an extra C═C bond is inserted at different positions (C6-C7, C10-C11, and C14-C15) were synthesized and introduced into a widely used channelrhodopsin variant, C1C2 (a chimeric protein of channelrhodopsin-1 and channelrhodopsin-2 from Chlamydomonas reinhardtii).

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Pharanois phoborhodopsin (ppR) from Natronomonas pharaonis is a transmembrane photoreceptor protein involved in negative phototaxis. Structural changes in ppR triggered by photoisomerization of the retinal chromophore are transmitted to its cognate transducer protein (pHtrII) through a cyclic photoreaction pathway involving several photointermediates. This pathway is called the photocycle.

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