ホタル生物発光における発光制御機構の化学生物学的研究

Firefly bioluminescence is an enzymatic reaction, which requires Mg2+, ATP, and O2. The mechanism of this bioluminescence is as follows; first, the luciferase catalyzes the adenylylation of the luciferin and then the oxygenation of the adenylylated luciferin, which makes an excited state oxyluciferin is generated and yellow-green (560 nm) light is emitted. This high efficiency luminescent system is widely used in the field of life science. At first, I have synthesized firefly luciferin analogs and evaluated bioluminescent property of 7- substituted and π-extended analogs. The π-extended type firefly luciferin analogs emitting blue, green, and red lights were developed. The longest emission maximum was observed at 675 nm (Near infra red, NIR), which belongs to the NIR biological window (650-900 nm), useful for deep site bioimaging of living animals. Next, I and the collaborator have applied NIR luciferin analog to in vivo cancer imaging. The light intensity of NIR emission luciferin analog (λmax= 675 nm) at the living mice imaging experiment had 10 times stronger than natural luciferin. The results indicate that the NIR emission luciferin analog has great potential to detect tumors in deeper sites. But firefly bioluminescence has a problem. The stronger light is required for realization of in vivo supersensitive deep site imaging. And another multi color luciferin analog has only very low light intensity. I have to solve this problem. The solution is that the light emission of the adenylated analogs was strongly enhanced compared with those of analogs themselves. But luciferin adenylate has low stability, so luciferin adenylate was not used imaging experiment as practical use tool. we aspire to create a high intensity and high stability luminescence system: a stable luciferyl- AMP. One has luciferyl-AMP’s structure activity correlation. Many kind of luciferin nucleotide was synthesized and evaluated those light intensity. One of luciferin nucleotide analog that was translated nucleotide structure at the phosphoester bond site has high stability. High stability luciferin nucleotide analog was developed and this technology can be applied to bule and red luciferin analogs. These technology will become a new powerful luminescent tool for life science field.電気通信大学201

Synthesis and Luminescence Properties of Near-Infrared N-Heterocyclic Luciferin Analogues for In Vivo Optical Imaging

As a means of achieving highly sensitive bioluminescence imaging of deep tissues utilizing the firefly luciferin-luciferase (L-L) reaction, we previously reported a luciferin analogue, AkaLumine, which exhibits high cell-permeability and emits near-infrared (NIR) light with high tissue-penetration by the L-L reaction. However, while AkaLumine enables us to observe targets in deep tissues, its poor solubility in aqueous media limits its utility for in vivo imaging. Herein, to address this issue, we have synthesized three AkaLumine derivatives with N-heterocyclic aromatic rings as new red luciferin analogues that have substantially higher solubility than that of AkaLumine in phosphate buffered saline solution. One of the derivatives (herein termed seMpai) exhibits an emission maximum at 675 nm upon L-L reaction with Photinus pyralis luciferase and presents an activity in mouse-tissue imaging similar to that of AkaLumine. It is hoped that seMpai will extend the application of high-sensitivity NIR bioluminescence imaging in a wide range of biomedical research fields

Functional visualization of NK Cell-mediated killing of metastatic single tumor cells

ナチュラルキラー（NK）細胞による転移がん細胞殺傷の可視化 --NK細胞とがん細胞の肺毛細血管上での戦いを実況中継する--. 京都大学プレスリリース. 2022-02-07.Natural killer (NK) cells lyse invading tumor cells to limit metastatic growth in the lung, but how some cancers evade this host protective mechanism to establish a growing lesion is unknown. Here we have combined ultra-sensitive bioluminescence imaging with intravital two-photon microscopy involving genetically-encoded biosensors to examine this question. NK cells eliminated disseminated tumor cells from the lung within 24 hrs of arrival, but not thereafter. Intravital dynamic imaging revealed that 50% of NK-tumor cell encounters lead to tumor cell death in the first 4 hrs after tumor cell arrival, but after 24 hrs of arrival, nearly 100% of the interactions result in the survival of the tumor cell. During this 24 hrs period, the probability of ERK activation in NK cells upon encountering the tumor cells was decreased from 68% to 8%, which correlated with the loss of the activating ligand CD155/PVR/Necl5 from the tumor cell surface. Thus, by quantitatively visualizing the NK-tumor cell interaction at the early stage of metastasis, we have revealed the crucial parameters of NK cell immune surveillance in the lung

慢性腎臓病では血中可溶型fms様チロシンキナーゼ-1産生の減少が動脈硬化症を悪化させる

Patients with chronic kidney disease (CKD) die of cardiovascular diseases for unknown reasons. Blood vessel formation in plaques and its relationship with plaque stability could be involved with signaling through the Flt-1 receptor and its ligands, vascular endothelial growth factor, and the closely related placental growth factor (PlGF). Flt-1 also exists as a circulating regulatory splice variant short-inhibitory form (sFlt-1) that serves as a decoy receptor, thereby inactivating PlGF. Heparin releases sFlt-1 by displacing the sFlt-1 heparin-binding site from heparin sulfate proteoglycans. Heparin could provide diagnostic inference or could also induce an antiangiogenic state. In the present study, postheparin sFlt-1 levels were lower in CKD patients than in control subjects. More importantly, sFlt-1 levels were inversely related to atherosclerosis in CKD patients, and this correlation was more robust after heparin injection, as verified by subsequent cardiovascular events. Knockout of apolipoprotein E (ApoE) and/or sFlt-1 showed that the absence of sFlt-1 worsened atherogenesis in ApoE-deficient mice. Thus, the relationship between atherosclerosis and PlGF signaling, as regulated by sFlt-1, underscores the underappreciated role of heparin in sFlt-1 release. These clinical and experimental data suggest that novel avenues into CKD-dependent atherosclerosis and its detection are warranted.博士（医学）・甲614号・平成26年3月17

A Stream-Weight Optimization Method for Multi-Stream HMMs Based on Likelihood Value Normalization

In the field of audio-visual speech recognition, multi-stream HMMs are widely used, thus how to automatically and properly determine stream weight factors using a small data set becomes an important research issue. This paper proposes a new stream-weight optimization method based on an output likelihood normalization criterion. In this method, the stream weights are adjusted to equalize the mean values of log likelihood for all HMMs. based on likelihood-ratio maximization which achieved significant improvement by using a large optimization data set. The new method is evaluated using Japanese connected digit speech recorded in real-world environments. Using 10 seconds speech data for stream-weight optimization, a 10% absolute accuracy improvement is achieved compared to the result before optimization. By additionally applying the MLLR (maximum likelihood linear regression) adaptation, a 23% improvement is obtained over the audio-only scheme

Unwinding on the Weekend from Work-Related Stress: Moderating Effect of Weekday Psychological Stress on the Relationship between Increased Recovery Experience and Reduction of Psychological Stress on the Weekend

Recovery is described as a process that is in contrast to the process whereby the psychological stress response increases. Recovery experiences refer to specific experiences that promote recovery and represent psychological attributes including relaxation. This preliminary study tested the hypothesis that levels of psychological stress before the weekend have a moderating effect on the relationship between an increased recovery experience during the weekend and a reduction of psychological stress from workdays to the weekend. Of 270 Japanese teachers who were invited to participate, 181 completed questionnaires on the psychological stress response before, on the psychological stress response and the recovery experience during the weekend. Data from 7 part-time teachers and 38 teachers who were not stressed at all before the weekend were excluded; therefore, data for 136 participants were ultimately analyzed. Results of hierarchal regression analysis indicated that increased relaxation was associated with an increased reduction in psychological stress response during the weekends in participants with high levels of psychological stress before the weekends. This moderating effect was not observed for other recovery experiences. Considering the psychological stress response is important for research on recovery experiences during weekends

Audio-Visual Speech Recognition Using Lip Information Extracted from Side-Face Images

This paper proposes an audio-visual speech recognition method using lip information extracted from side-face images as an attempt to increase noise robustness in mobile environments. Our proposed method assumes that lip images can be captured using a small camera installed in a handset. Two different kinds of lip features, lip-contour geometric features and lip-motion velocity features, are used individually or jointly, in combination with audio features. Phoneme HMMs modeling the audio and visual features are built based on the multistream HMM technique. Experiments conducted using Japanese connected digit speech contaminated with white noise in various SNR conditions show effectiveness of the proposed method. Recognition accuracy is improved by using the visual information in all SNR conditions. These visual features were confirmed to be effective even when the audio HMM was adapted to noise by the MLLR method