Publications by authors named "Yayama K"

Intestinal microbiota can indirectly modulate airway physiology and immunity through the gut-lung axis. Recent microbiome studies indicate that patients with coronavirus disease 2019 (COVID-19) exhibit a specific intestinal dysbiosis that is closely associated with the disease pathophysiology. Therefore, rebalancing the intestinal microbiome using probiotics may be effective for controlling COVID-19.

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Angiotensin II (Ang II) induces vasoconstriction through myosin light chain (MLC) kinase activation and MLC phosphatase inactivation via phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) by Rho kinase. However, the detailed mechanism underlying Rho kinase activation by Ang II is still unknown. We investigated the mechanism of Ang II-induced vasoconstriction mediated by Rho kinase in pressure-overloaded rat thoracic aortas.

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Orthovanadate (OVA), a protein tyrosine phosphatase inhibitor, induces contraction in endothelium-denuded mouse thoracic aortas. OVA-induced contraction was significantly (vs. control rings) suppressed by Rho kinase (Y-27632, 10 µM), extracellular signal-regulated kinase 1 and 2 (Erk1/2, FR180204, 10 µM), Erk1/2 kinase (MEK, PD98059, 10 µM), epidermal growth factor receptor (EGFR, AG1478, 10 µM), and Src inhibitors, and was partially suppressed by c-Jun N-terminal kinase (JNK, AS601245, 10 µM) and p38 (SB203580, 10 µM) inhibitors.

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Several studies have reported that amorphous nano-silica particles (nano-SPs) modulate calcium flux, although the mechanism remains incompletely understood. We thus analyzed the relationship between calcium flux and particle surface properties and determined the calcium flux route. Treatment of Balb/c 3T3 fibroblasts with nano-SPs with a diameter of 70 nm (nSP70) increased cytosolic calcium concentration, but that with SPs with a diameter of 300 or 1000 nm did not.

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There have been several reported studies on the distribution and/or toxicity of nanosilica particles. However, the influence of these particles on blood vessels through which they are distributed is poorly understood. Hence, we investigated the effects of nano- and micromaterials on blood vessel shrinkage and relaxation.

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Orthovanadate (OVA), a protein tyrosine phosphatase inhibitor, induces vasoconstriction in a Rho kinase-dependent manner. The aim of this study was to determine the mechanism underlying OVA-induced vasoconstriction of rat mesenteric arteries. OVA-induced constriction of mesenteric arterial rings treated with N(G)-nitro-L-arginine methyl ester (L-NAME, 0.

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We previously found that the protein tyrosine phosphatase inhibitor orthovanadate evoked a vasoconstrictor effect in rat aortas via Rho-kinase-dependent inactivation of myosin light chain phosphatase (MLCP) downstream of epidermal growth factor (EGF) receptor signaling. To determine whether the direct activation of EGF receptor by EGF also induces Rho-kinase-dependent vasoconstriction, isometric tension changes were measured in rat aortic rings without endothelium. Although EGF did not produce a contractile effect, the Ca(2+)-induced force in Ca(2+)-depleted rings significantly increased after treatment with 100nM EGF, suggesting that EGF induces Ca(2+) sensitization by MLCP inactivation.

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Silver nanoparticles (AgNPs) induce the production of reactive oxygen species (ROS) and apoptosis. These effects are enhanced by smaller particles. Using live-cell imaging, we show that AgNPs induced ROS production rapidly in a size-dependent manner after exposure of cells to 70-nm and 1-nm AgNPs (AgNPs-70, AgNPs-1), but not AgNO.

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Orthovanadate (OVA), a protein tyrosine phosphatase (PTPase) inhibitor, exerts contractile effects on smooth muscle in a Rho-kinase-dependent manner, but the precise mechanisms are not elucidated. The aim of this study was to determine the potential roles of Src and epidermal growth factor receptor (EGFR) in the OVA-induced contraction of rat aortas and the phosphorylation of myosin phosphatase target subunit 1 (MYPT1; an index of Rho-kinase activity) in vascular smooth muscle cells (VSMCs). Aortic contraction by OVA was significantly blocked not only by Rho kinase inhibitors Y-27632 [R-[+]-trans-N-[4-pyridyl]-4-[1-aminoethyl]-cyclohexanecarboxamide] and hydroxyfasudil [1-(1-hydroxy-5-isoquinolinesulfonyl)homopiperazine] but also by Src inhibitors PP2 [4-amino-3-(4-chlorophenyl)-1-(t-butyl)-1H-pyrazolo[3,4-d]pyrimidine] and Src inhibitor No.

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Hyperosmotic stress induces the contractile response of vascular smooth muscle cells (VSMCs). Previous studies have demonstrated that cytoskeleton reorganization and Rho/Rho-kinase-mediated inactivation of myosin light chain phosphatase (MLCP) play an important role in hyperosmotic vasoconstriction, but the precise mechanism is unknown. This study aimed to investigate the contractile response of endothelium-denuded rings of rat aortas to hyperosmolar sucrose (160 mM) in the presence or absence of inhibitors for various protein kinases.

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We previously reported that superimposition of 3-dimensional (3D) images reconstructed from computed tomographic images of skeletonized skulls on photographs of the actual skulls afforded a match of skull contours, thereby demonstrating that superimposition of 3D-reconstructed images provides results identical to those obtained with actual skulls. The current superimposition procedure requires a skeletonized skull with mouth closed and thus is not applicable to personal identification using a skull with residual soft tissue or the mouth fixed open, such as those found in mummified or burned bodies. In this study, we scanned using computed tomography the skulls of mummified and immersed body with mandibles fixed open by residual soft tissue, created 3D-reconstructed skull images, which were digitally processed by computer software to close the mandible, and superimposed the images on antemortem facial photographs.

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Vascular smooth muscle cells (VSMCs) exhibit shrinkage-induced activation of Na(+)/H(+) exchanger isoform 1 (NHE-1) and Na(+), K(+), 2Cl(-) cotransporter (NKCC) under hyperosmotic conditions. To investigate the roles of these ion transporters in vascular smooth muscle force induced by hyperosmotic stress, we tested the effects of 5-(N, N-dimethyl)-amiloride (DMA; NHE inhibitor), cariporide (a selective NHE-1 inhibitor), and bumetanide (NKCC inhibitor) on the contractile response of rat aortic rings to hyperosmolar solutions. NHE inhibitors significantly augmented the maximum force response and contractile sensitivity to hyperosmolar sucrose, NaCl, and glucose in endothelium-denuded rings.

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The objective of this study was to determine the mechanism by which Na(+)/H(+) exchanger (NHE) inhibitors induce vasodilatation. The NHE inhibitors, 5-(N,N-dimethyl)-amiloride (DMA), cariporide, and amiloride, evoked endothelium-dependent relaxation in rat aortas with ED50 values of 16, 89, and 148μM, respectively, and these effects were abolished by treatment with N(G)-nitro-l-arginine methyl ester (L-NAME). The relaxation effects induced by DMA and cariporide were strongly attenuated in aortas of the endothelial NO synthase (eNOS)-deficient mice, as compared to the effects in wild-type mice.

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Superimposition has been applied to skulls of unidentified skeletonized corpses as a personal identification method. The current method involves layering of a skull and a facial image of a suspected person and thus requires a real skeletonized skull. In this study, we scanned skulls of skeletonized corpses by computed tomography (CT), reconstructed three-dimensional (3D) images of skulls from the CT images, and superimposed the 3D images with facial images of the corresponding persons taken in their lives.

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Clear cell sarcoma (CCS) is a rare melanocytic malignant tumor with a poor prognosis. Our previous study demonstrated that in vitro cultured CCS cells have the ability to highly uptake l-BPA and thus boron neutron capture therapy could be a new option for CCS treatment. This paper proved that a remarkably high accumulation of (10)B (45-74 ppm) in tumor was obtained even in a CCS-bearing animal with a well-controlled biodistribution followed by intravenous administration of L-BPA-fructose complex (500 mg BPA/kg).

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Unprecedented fidelity and specificity have afforded DNA testing its long reigning status as the gold standard for establishing personal identification. While the method itself is flawless, forensic experts have undoubtedly stumbled across challenging cases in which no reference samples for an unknown person (UP) are available for comparison. In such cases, experts often must resort to an assortment of kinship analyses-primarily those involving alleged parents or children of a UP-to establish personal identification.

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Angiotensin II (Ang II) is an important mediator stimulating liver fibrosis after liver injury. However, it is not known whether Ang II plays a role in liver regeneration. Here, we investigate the effects of Ang II type 1 (AT(1)) receptor blocker (ARB), angiotensin-converting enzyme inhibitor (ACEI), systemic infusion of Ang II, and genetic deficiency of the AT(1a) receptor (AT1a-KO) on the hepatic regenerative response to partial hepatectomy (PH) in mice.

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Regulation of the kallikrein-kinin system in cerebral inflammation is still unclear. Here, we used reverse-transcription polymerase chain reaction (RT-PCR) techniques to show that lipopolysaccharide (LPS) activates the kallikrein-kinin system by enhancing liberation of bradykinin (BK), and alters mRNA levels of kallikrein-kinin system components, including high molecular weight (H-) and low molecular weight (L-) kininogens, in ECPC4 cells, a cell line of mouse choroid plexus epithelium. LPS treatment increased liberation of immunoreactive bradykinin in the supernatant of ECPC4 cells, and addition of LPS (500 ng/ml) to cultures resulted in elevation of H- and L-kininogen mRNA levels in ECPC4 cells within 24-48 h.

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Angiotensin II (Ang II) plays important roles in the regulation of cardiovascular functions and diseases mainly via the type 1 (AT1) receptor. In contrast, recent studies have shown that the actions of Ang II via the type 2 (AT2) receptor are counter-regulatory to those mediated via the AT1 receptor. Using an animal model of hypertension, we have demonstrated that Ang II produces a vasodilator effect through the AT2 receptor via the bradykinin (BK)-dependent activation of endothelial nitric oxide (NO) synthase.

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Calcitonin gene-related peptide (CGRP) is thought to be a prominent neuropeptide in cardiovascular regulation and neuroimmune modulation. There are two isoforms of CGRP (alphaCGRP and betaCGRP), and the main CGRP receptors are probably composed of a calcitonin receptor-like receptor (CLR) and a receptor activity-modifying protein (RAMP)1. However, the physiological functions of CGRP that are mediated through the CLR/RAMP1 receptors remain to be clarified.

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Angiotensin II (Ang II) signaling is mediated by two receptor subtypes, type 1 (AT(1)) and type 2 (AT(2)). The activation of AT(1) receptors is responsible for the development of Ang II-dependent hypertension, whereas the activation of AT(2) receptor is thought to play a counter-regulatory protective role in the regulation of blood pressure that opposes the AT(1) receptor-mediated vasoconstriction. However, the precise mechanisms by which increased numbers of AT(2) receptors counterbalance the AT(1)-mediated actions of Ang II are unknown.

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The interaction between viral capsid proteins and specific molecules exposed on the plasma membrane of the cells is involved in the viral tropism. A human adenovirus (Ad) belonging to subgroups A, C, D, E and F infects cells via the interaction between the fiber knob and the primary receptor, the coxsackievirus and adenovirus receptor (CAR). Conventional human adenovirus type 5 (hAd5) vectors show efficient transduction in CAR-positive cells; in contrast, hAd5 vector application is limited by poor transduction into cells lacking CAR expression.

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Angiotensin-converting enzyme (ACE) inhibitor enhances the liver regeneration in rats after partial hepatectomy (PH), though the precise mechanisms are unknown. To determine the roles of bradykinin and angiotensin II in the ACE inhibitor-induced enhancement of liver regeneration, we investigated effects of lisinopril (ACE inhibitor), candesartan and losartan (angiotensin II type 1 (AT1) receptor antagonists) and icatibant (bradykinin B2 receptor antagonist) on the hepatic regenerative response to 70% PH in the rat. The liver regeneration was evaluated by measuring the frequency of 5-bromo-2'-deoxyuridine (BrdU) incorporation into hepatocyte nuclei 48 h after PH.

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Abdominal aortic banding in mice induces upregulation of angiotensin II (Ang II) type 2 (AT2) receptors in the pressure-overloaded thoracic aorta. To clarify mechanisms underlying the vascular AT2 receptor-dependent NO production, we measured aortic levels of endothelial NO synthase (eNOS), eNOS phosphorylated at Ser633 and Ser1177, protein kinase B (Akt), and Akt phosphorylated at Ser473 in thoracic aortas of mice after banding. Total eNOS, both forms of phosphorylated eNOS, Akt, and phosphorylated Akt levels, as well as cGMP contents, were significantly increased 4 days after banding.

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Our present study aimed to characterize the effects of lipopolysaccharide (LPS) on the expression of the bradykinin B2-receptor in the mouse heart, which may have a role in cardiac depression during sepsis. We found that LPS induced the up-regulation of B2-receptor mRNA in the heart in vivo and in cultured cardiac myocytes in vitro. Like LPS, tumor necrosis factor-alpha (TNF-alpha) but not interleukin (IL)-1-beta, IL-6 or endothelin-1 stimulated B2-receptor expression in cultured myocytes.

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