Publications by authors named "Tomohiro Kawahara"

Summary: Although supermicrosurgery techniques are essential skills for lymphatic surgery or perforator-flap surgery, an ideal training model is yet to be introduced. Living animal models, such as rodents, are considered to be ideal microsurgical training models. However, the use of living animal models is costly and involves bioethical considerations.

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A bacterial strain, WON2089, was isolated from the faeces of healthy Japanese adults and is able to use mucin as the sole carbon and nitrogen source. Sequencing of its 16S rRNA gene showed that WON2089 has 98.0 and 94.

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The avian egg is a closed system that protects the growing embryo from external factors but prevents direct observation of embryo development. Various culture systems exist in the literature to study the development of the embryo for short periods of incubation (from 12 h up to a maximum of 60 h of egg incubation). A common flaw to these culture techniques is the inability to culture the unincubated avian blastoderm with intact tissue tensions on its native yolk.

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Evidence linking the gut-brain axis to Alzheimer's disease (AD) is accumulating, but the characteristics of causally important microbes are poorly understood. We perform a fecal microbiome analysis in healthy subjects and those with mild cognitive impairment (MCI) and AD. We find that () correlates with cognitive scores and decreases in the MCI group compared with the healthy group.

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Cells adapt to applied cyclic stretch (CS) to circumvent chronic activation of proinflammatory signaling. Currently, the molecular mechanism of the selective disassembly of actin stress fibers (SFs) in the stretch direction, which occurs at the early stage of the cellular response to CS, remains controversial. Here, we suggest that the mechanosensitive behavior of myosin II, a major cross-linker of SFs, primarily contributes to the directional disassembly of the actomyosin complex SFs in bovine vascular smooth muscle cells and human U2OS osteosarcoma cells.

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In recent advanced information society, it is important to individually identify products or living organisms automatically and quickly. However, with the current identifying technology such as RFID tag or biometrics, it is difficult to apply to amphibians such as frogs or newts because of its size, stability, weakness under a wet environment and so on. Thus, this research aims to establish a system that can trace small amphibians easily even in a wet environment and keep stable sensing for a long time.

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The importance of in vitro 3D cultures is considerably emphasized in cell/tissue culture. However, the lack of experimental repeatability is one of its restrictions. Producing few repeatable results of pattern formation deteriorates the analysis of the mechanisms underlying the self-organization.

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Three-dimensional (3D) cell and tissue cultures more closely mimic biological environments than two-dimensional (2D) cultures and are therefore highly desirable in culture experiments. However, 3D cultures often fail to yield repeatable experimental results because of variation in the initial culture conditions, such as cell density and distribution in the extracellular matrix, and therefore reducing such variation is a paramount concern. Here, we present a 3D culture platform that demonstrates highly repeatable experimental results, obtained by controlling the initial cell cluster shape in the gel cube culture device.

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We propose a microrobotic platform for single motile microorganism observation and investigation. The platform utilizes a high-speed online vision sensor to realize real-time observation of a microorganism under a microscopic environment with a relatively high magnification ratio. A microfluidic chip was used to limit the vertical movement of the microorganism and reduce the tracking system complexity.

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Background: Small pulmonary tumors are difficult to localize during video-assisted thoracic surgery (VATS) because of lack of direct tissue contact. However, in partial lung resection, tumor localization is quite important. The aim of this study was to evaluate the safety and feasibility of a new noncontact sensor for detecting pulmonary nodules during VATS using human and porcine models.

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The chorioallantoic membrane (CAM) containing tiny blood vessels is an alternative to large animals for studies involving angiogenesis and tissue engineering. However, there is no technique to design the direction of growing blood vessels on the CAM at the microscale level for tissue engineering experiments. Here, a methodology is provided to direct blood vessel formation on the surface of a three-dimensional egg yolk using a cubic artificial eggshell with six functionalized membranes.

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Human rotavirus (RV) infection is a leading cause of dehydrating diarrhea in infants and young children worldwide. Since therapeutic approaches to RV gastroenteritis are limited to alleviation of dehydration with oral rehydration solutions, more direct approaches to palliate symptoms of RV gastroenteritis are required. Treatments with probiotics have been increasingly recognized as alternative safe and low cost treatments for moderate infectious diarrhea.

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An in vitro 3D culturing platform enabling multidirectional observations of 3D biosamples is presented. The 3D structure of biosamples can be recognized without fluorescence. The cubic platform employs two types of hydrogels that are compatible with conventional culture dishes or well plates, facilitating growth in culture, ease of handling, and viewing at multiple angles.

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We propose a novel system for the observation of living cell exposed to cyclic stretch under dynamic conditions. The developed system is mainly composed of a laptop PC, a stretching unit with three motorized stages, and a microscope with a CCD camera. The design of the cell tracking system is based on the deformation characteristics of the elastic chamber and its performance was confirmed through the basic experiments.

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An eggshell is a porous microstructure that regulates the passage of gases to allow respiration. The chick embryo and its circulatory system enclosed by the eggshell has become an important model for biomedical research such as the control of angiogenesis, cancer therapy, and drug delivery test, because the use of embryo is ethically acceptable and it is inexpensive and small. However, chick embryo and extra-embryonic blood vessels cannot be accessed freely and has poor observability because the eggshell is tough and cannot be seen through, which limits its application.

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Bifidobacterium, one of the major components of intestinal microflora, shows anti-influenza virus (IFV) potential as a probiotic, partly through enhancement of innate immunity by modulation of the intestinal immune system. Bifidobacterium longum MM-2 (MM-2), a very safe bacterium in humans, was isolated from healthy humans and its protective effect against IFV infection in a murine model shown. In mice that were intranasally inoculated with IFV, oral administration of MM-2 for 17 consecutive days improved clinical symptoms, reduced mortality, suppressed inflammation in the lower respiratory tract, and decreased virus titers, cell death, and pro-inflammatory cytokines such as IL-6 and TNF-α in bronchoalveolar lavage fluid.

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Therapeutic and diagnostic nanomaterials are being intensely studied for several diseases, including cancer and atherosclerosis. However, the exact mechanism by which nanomedicines accumulate at targeted sites remains a topic of investigation, especially in the context of atherosclerotic disease. Models to accurately predict transvascular permeation of nanomedicines are needed to aid in design optimization.

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Introduction: Under mirror-image conditions, surgeons often become confused and their task performance may deteriorate. This study aimed to quantitatively investigate the difficulty of performing laparoscopic surgery based on a mirror image and to find methods to improve performance under these conditions.

Methods: Twelve medical students with no prior endoscopic surgical experience and 10 surgical residents, each with over 50 laparoscopic surgery experiences, participated in this study.

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In this paper, we propose a novel, magnetically driven microrobot equipped with a frame structure to measure the effects of stimulating aquatic microorganisms. The design and fabrication of the force-sensing structure with a displacement magnification mechanism based on beam deformation are described. The microrobot is composed of a Si-Ni hybrid structure constructed using micro-electro-mechanical system (MEMS) technologies.

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Background: The detailed influence of virtual reality training (VRT) and box training (BT) on laparoscopic performance is unknown; we aimed to determine the optimal order of imparting these training programs.

Material And Methods: This randomized controlled trial involved two groups, each with 20 participants without prior laparoscopic surgical experience: A BT-VRT group (60 min BT followed by 60 min VRT) and a VRT-BT group (60 min VRT followed by 60 min BT). We objectively assessed the laparoscopic skills with a motion-analysis system (Hiroshima University Endoscopic Surgical Assessment Device: HUESAD), which reliably assesses surgical dexterity.

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The forkhead transcription factor Foxo1 regulates energy homeostasis by modulating gene expression in the hypothalamus. Foxo1 undergoes post-translational modifications such as phosphorylation and acetylation, which modulate its functional activities. Sirtuin1 (Sirt1), a nicotinamide adenine dinucleotide-dependent protein deacetylase, regulates the acetylation status of Foxo1 in mammalian cells.

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This study aimed to verify whether the approaching time (the time taken to reach the target point from another point, a short distance apart, during point-to-point movement in endoscopic surgery), assessed using the Hiroshima University Endoscopic Surgical Assessment Device (HUESAD), could distinguish the skill level of surgeons. Expert surgeons (who had performed more than 50 endoscopic surgeries) and novice surgeons (who had no experience in performing endoscopic surgery) were tested using the HUESAD. The approaching time, total time, and intermediate time (total time--approaching time) were measured and analyzed using the trajectory of the tip of the instrument.

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This paper presents an innovative driving method for an on-chip robot actuated by permanent magnets in a microfluidic chip. A piezoelectric ceramic is applied to induce ultrasonic vibration to the microfluidic chip and the high-frequency vibration reduces the effective friction on the MMT significantly. As a result, we achieved 1.

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Background: The goal of this study was to improve the efficiency of initial box training for laparoscopic surgery.

Materials And Methods: The study used the following task: suturing and knot tying task under a combination of four conditions. (1) The C (use of conventional instruments)-D (direct vision); (2) the C-V (indirect vision via a video monitor); (3) the L (use of laparoscopic instruments)-D; and (4) the L-V (the standard laparoscopic suturing and knot tying).

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Recently, significant attention has been focused on training and education for safe endoscopic surgery. A new assessment method, the Hiroshima University Endoscopic Surgical Assessment Device (HUESAD), has been designed at Hiroshima University to evaluate the smoothness of the movement of endoscopic instruments from velocity. Experts (with experience in performing more than 100 laparoscopic surgeries) and novices (with no experience in performing laparoscopic surgery) were recruited for this study.

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