Publications by authors named "Yoshio Nakahara"

32 Publications

Synthesis of Silica Nanoparticles with Physical Encapsulation of Near-Infrared Fluorescent Dyes and Their Tannic Acid Coating.

ACS Omega 2021 Jul 29;6(27):17651-17659. Epub 2021 Jun 29.

Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510, Japan.

This study reports a novel method for the synthesis of silica nanoparticles (NPs) encapsulating near-infrared (NIR) fluorescent dyes through physical adsorption. Although a NIR cationic fluorescent dye, oxazine 725 (OXA), has no chemical bonding moiety toward silica NPs such as the triethoxysilyl group, the dyes were successfully incorporated into silica NPs without denaturation under the mild reaction conditions. Next, tannic acid (TA) molecules were coated in the presence of Fe on the particle surface for the functionalization of silica NPs encapsulating OXA ([email protected] NPs). The TA coating on the surface of [email protected] NPs was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. The TA coating significantly contributed to the resistance improvement against photobleaching and leakage of the dyes in the NPs. Furthermore, the obtained TA-coated silica NPs encapsulating OXAs ([email protected]@TA NPs) were used for the fluorescence imaging of African green monkey kidney (COS-7) cells, and it was shown that the fluorescence originated from [email protected]@TA NPs was clearly observed in the COS-7 cells.
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http://dx.doi.org/10.1021/acsomega.1c02204DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8280675PMC
July 2021

Size and surface modification of silica nanoparticles affect the severity of lung toxicity by modulating endosomal ROS generation in macrophages.

Part Fibre Toxicol 2021 06 17;18(1):21. Epub 2021 Jun 17.

Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan.

Background: As the application of silica nanomaterials continues to expand, increasing chances of its exposure to the human body and potential harm are anticipated. Although the toxicity of silica nanomaterials is assumed to be affected by their physio-chemical properties, including size and surface functionalization, its molecular mechanisms remain unclear. We hypothesized that analysis of intracellular localization of the particles and subsequent intracellular signaling could reveal a novel determinant of inflammatory response against silica particles with different physico-chemical properties.

Results: We employed a murine intratracheal instillation model of amorphous silica nanoparticles (NPs) exposure to compare their in vivo toxicities in the respiratory system. Pristine silica-NPs of 50 nm diameters (50 nm-plain) induced airway-centered lung injury with marked neutrophilic infiltration. By contrast, instillation of pristine silica particles of a larger diameter (3 μm; 3 μm-plain) significantly reduced the severity of lung injury and neutrophilic infiltration, possibly through attenuated induction of neutrophil chemotactic chemokines including MIP2. Ex vivo analysis of alveolar macrophages as well as in vitro assessment using RAW264.7 cells revealed a remarkably lower cellular uptake of 3 μm-plain particles compared with 50 nm-plain, which is assumed to be the underlying mechanism of attenuated immune response. The severity of lung injury and neutrophilic infiltration was also significantly reduced after intratracheal instillation of silica NPs with an amine surface modification (50 nm-NH) when compared with 50 nm-plain. Despite unchanged efficacy in cellular uptake, treatment with 50 nm-NH induced a significantly attenuated immune response in RAW264.7 cells. Assessment of intracellular redox signaling revealed increased reactive oxygen species (ROS) in endosomal compartments of RAW264.7 cells treated with 50 nm-plain when compared with vehicle-treated control. In contrast, augmentation of endosomal ROS signals in cells treated with 50 nm-NH was significantly lower. Moreover, selective inhibition of NADPH oxidase 2 (NOX2) was sufficient to inhibit endosomal ROS bursts and induction of chemokine expressions in cells treated with silica NPs, suggesting the central role of endosomal ROS generated by NOX2 in the regulation of the inflammatory response in macrophages that endocytosed silica NPs.

Conclusions: Our murine model suggested that the pulmonary toxicity of silica NPs depended on their physico-chemical properties through distinct mechanisms. Cellular uptake of larger particles by macrophages decreased, while surface amine modification modulated endosomal ROS signaling via NOX2, both of which are assumed to be involved in mitigating immune response in macrophages and resulting lung injury.
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http://dx.doi.org/10.1186/s12989-021-00415-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8210371PMC
June 2021

Fibroblasts positive for meflin have anti-fibrotic property in pulmonary fibrosis.

Eur Respir J 2021 May 28. Epub 2021 May 28.

National Hospital Organization Nagoya Medical Center, Nagoya, Japan.

The prognosis of elderly individuals with idiopathic pulmonary fibrosis (IPF) remains poor. Fibroblastic foci, in which aggregates of proliferating fibroblasts and myofibroblasts are involved, are the pathological hallmark lesions in IPF to represent focal areas of active fibrogenesis. Fibroblast heterogeneity in fibrotic lesions hampers the discovery of the pathogenesis of pulmonary fibrosis. Therefore, to determine of the pathogenesis of IPF, identification of functional fibroblasts is warranted. This study was aimed to determine the role of fibroblasts positive for meflin, identified as a potential marker for mesenchymal stromal cells, during the development of pulmonary fibrosis. We characterised meflin-positive cells in a single cell atlas established by single-cell RNA sequencing (scRNA-seq)-based profiling of 243 472 cells from 32 IPF lungs and 29 normal lung samples. scRNA-seq combined with RNA hybridisation identified proliferating fibroblasts positive for meflin in fibroblastic foci, not dense fibrosis, of fibrotic lungs in IPF patients. We determined the role of fibroblasts positive for meflin using bleomycin (BLM)-induced pulmonary fibrosis. A BLM-induced lung fibrosis model for meflin-deficient mice showed that fibroblasts positive for meflin had anti-fibrotic property to prevent pulmonary fibrosis. Although transforming growth factor-β-induced fibrogenesis and cell senescence with senescence-associated secretory phenotype were exacerbated in fibroblasts the repression or lack of meflin, these were inhibited in meflin-deficient fibroblasts with meflin reconstitution. These findings provide evidence to show the biological importance of meflin expression on fibroblasts and myofibroblasts in the active fibrotic region of pulmonary fibrosis.
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http://dx.doi.org/10.1183/13993003.03397-2020DOI Listing
May 2021

Effects of Polypropylene Glycol at Very Low Concentrations on Rheological Properties at the Air-Water Interface and Foam Stability of Sodium Bis(2-ethylhexyl)sulfosuccinate Aqueous Solutions.

Langmuir 2020 Sep 18;36(34):10043-10050. Epub 2020 Aug 18.

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510, Japan.

The present study investigates the effects of very low concentrations of polypropylene glycol (PPG) on the rheological properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) aqueous solutions at the surface for the precise control of foam properties. Langmuir trough experiments and Brewster angle microscopy (BAM) of the AOT monolayer on the surfaces of PPG aqueous solutions indicated that a very low concentration of PPG increased the number of AOT molecules at the surface. Viscoelastic behaviors at the surface and surface tension isotherms in mixed aqueous solutions of AOT and PPG revealed that AOT interacted with PPG in the surface and bulk phase. A modified Ross-Miles method was performed to assess the foam stabilities of AOT aqueous solutions with and without PPG. The stabilization of foam by PPG was attributed to the rheological properties of AOT aqueous solutions at the surface.
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http://dx.doi.org/10.1021/acs.langmuir.0c01109DOI Listing
September 2020

High-flow nasal cannula therapy for acute respiratory failure in patients with interstitial pneumonia: a retrospective observational study.

Nagoya J Med Sci 2020 May;82(2):301-313

Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.

High-flow nasal cannula (HFNC) oxygen is a therapy that has demonstrated survival benefits in acute respiratory failure (ARF). However, the role of HFNC in ARF due to interstitial pneumonia (IP) is unknown. The aim of this study was to compare the effects of HFNC therapy and non-invasive positive pressure ventilation (NPPV) in ARF due to IP. This retrospective observational study included 32 patients with ARF due to IP who were treated with HFNC (n = 13) or NPPV (n = 19). The clinical characteristics, intubation rate and 30-day mortality were analyzed and compared between the HFNC group and the NPPV group. Predictors of 30-day mortality were evaluated using a logistic regression model. HFNC group showed higher mean arterial blood pressure (median 92 mmHg; HFNC group vs 74 mmHg; NPPV group) and lower APACHEII score (median 22; HFNC group vs 27; NPPV group) than NPPV group. There was no significant difference in the intubation rate at day 30 between the HFNC group and the NPPV group (8% vs 37%: p = 0.069); the mortality rate at 30 days was 23% and 63%, respectively. HFNC therapy was a significant determinant of 30-day mortality in univariate analysis, and was confirmed to be an independent significant determinant of 30-day mortality in multivariate analysis (odds ratio, 0.148; 95% confidence interval, 0.025-0.880; p = 0.036). Our findings suggest that HFNC therapy can be a possible option for respiratory management in ARF due to IP. The results observed here warrant further investigation of HFNC therapy in randomized control trials.
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http://dx.doi.org/10.18999/nagjms.82.2.301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7276417PMC
May 2020

BK virus-associated viruria and viremia in a patient with lymphangioleiomyomatosis after lung re-transplantation: A case report and review of the literature on BK virus infection post-lung transplantation.

J Infect Chemother 2019 Oct 23;25(10):820-824. Epub 2019 Apr 23.

Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan. Electronic address:

The BK virus (BKV) is a member of the polyomaviridae family of DNA viruses. BKV reactivates under a highly immunosuppressed state and causes renal dysfunction. In renal transplant patients, BKV infection leads to tubular impairment and loss of transplanted kidney grafts. However, few studies have reported on the relationship between BKV and lung transplantation. Adjustment of the dosage of immunosuppressants is needed in some cases, but the treatment method has not been established. Here, we report a case of BKV-associated viruria and viremia in a patient with lymphangioleiomyomatosis (LAM) after lung re-transplantation. A 44-year-old female refractory LAM patient who had undergone lung re-transplantation 3 months earlier was diagnosed with BKV-associated viruria and viremia. Urine cytology indicated decoy cells and the urine and serum polymerase chain reaction test was positive for BKV. As scheduled after re-transplantation surgery, immunosuppressive drugs were progressively reduced. This patient was considered to have experienced spontaneous BKV-associated viremia and viruria. Review of the literature suggested that 17%-42% of BKV-associated viruria cases have been reported after lung transplantation, but cases of BKV-associated nephropathy are rarely reported. Based on the present case, doctors involved in lung transplantation should monitor patients for BKV infection. Decoy cell monitoring by urine cytology is a useful screening method in the follow-up observation after lung transplantation. Early-stage interventions may prevent BKV-associated nephropathy even in patients who have developed BKV viremia, and sirolimus can be administered to patients with histories of BKV infection if they are carefully monitored.
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http://dx.doi.org/10.1016/j.jiac.2019.04.002DOI Listing
October 2019

Repressive role of stabilized hypoxia inducible factor 1α expression on transforming growth factor β-induced extracellular matrix production in lung cancer cells.

Cancer Sci 2019 Jun 13;110(6):1959-1973. Epub 2019 May 13.

Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.

Activation of transforming growth factor β (TGF-β) combined with persistent hypoxia often affects the tumor microenvironment. Disruption of cadherin/catenin complexes induced by these stimulations yields aberrant extracellular matrix (ECM) production, characteristics of epithelial-mesenchymal transition (EMT). Hypoxia-inducible factors (HIF), the hallmark of the response to hypoxia, play differential roles during development of diseases. Recent studies show that localization of cadherin/catenin complexes at the cell membrane might be tightly regulated by protein phosphatase activity. We aimed to investigate the role of stabilized HIF-1α expression by protein phosphatase activity on dissociation of the E-cadherin/β-catenin complex and aberrant ECM expression in lung cancer cells under stimulation by TGF-β. By using lung cancer cells treated with HIF-1α stabilizers or carrying doxycycline-dependent HIF-1α deletion or point mutants, we investigated the role of stabilized HIF-1α expression on TGF-β-induced EMT in lung cancer cells. Furthermore, the underlying mechanisms were determined by inhibition of protein phosphatase activity. Persistent stimulation by TGF-β and hypoxia induced EMT phenotypes in H358 cells in which stabilized HIF-1α expression was inhibited. Stabilized HIF-1α protein expression inhibited the TGF-β-stimulated appearance of EMT phenotypes across cell types and species, independent of de novo vascular endothelial growth factor A (VEGFA) expression. Inhibition of protein phosphatase 2A activity abrogated the HIF-1α-induced repression of the TGF-β-stimulated appearance of EMT phenotypes. This is the first study to show a direct role of stabilized HIF-1α expression on inhibition of TGF-β-induced EMT phenotypes in lung cancer cells, in part, through protein phosphatase activity.
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http://dx.doi.org/10.1111/cas.14027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6549927PMC
June 2019

Crystallite Size Increase of Silver Nanoparticles by Ligand Exchange and Subsequent Washing Process with Antisolvent.

J Nanosci Nanotechnol 2019 Aug;19(8):4565-4570

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510, Japan.

Desorption performance of ligands from silver nanoparticles extremely affects a sintering process of nanoinks for their writing fine pattern. In this study, we investigated desorption behaviors of ligands on the surface of silver nanoparticle through ligand exchange and subsequent washing process with antisolvent. Ligand exchange reactions from oleic acid to tri-n-octylphosphine oxide (TOPO), octanoic acid (OA), and 1-dodecanethiol (DDT) were carried out on the surface of silver nanoparticle. After the washing process with methanol as an antisolvent, their crystallite sizes and the amounts of ligands existing on the particle surface were evaluated by powder X-ray diffraction and thermogravimetric analysis, respectively. In the case of ligand exchange with TOPO, the crystallite size dramatically increased and the amount of ligands existing on the particle surface significantly decreased. This result shows that TOPO is easy to desorb from the silver surface in the washing process with methanol, which resulted in the efficient coalescence of silver. In contrast, the coalescence of silver nanoparticles capped with OA and DDT was less efficient. Moreover, the effect of the antisolvent in the washing process on the coalescence of silver was demonstrated in detail.
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http://dx.doi.org/10.1166/jnn.2019.16361DOI Listing
August 2019

Effect of Protective Agents on Silver Nanoparticle Preparation by Vacuum Evaporation on Running Hydrocarbon Solution.

J Nanosci Nanotechnol 2018 Apr;18(4):2547-2554

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510, Japan.

In order to simply compare the performance of protective agents in the preparation of metal nanoparticles, a systematic investigation based on the same synthetic conditions is necessary. We successfully achieved this objective using improved vacuum evaporation on running oil substrate (VEROS) method. The efficient synthesis of nanoparticles with the improved VEROS method enabled us to characterize them by various analytical methods. In this study, five types of protective agents with different functional groups were employed to clarify their effect on the preparation of silver nanoparticles. They are sorbitan monooleate, oleylamine, oleic acid, oleyl alcohol, and methyl oleate. Particles synthesized by the improved VEROS method were evaluated by transmission electron microscope (TEM) and UV-vis spectrophotometer. These results indicate that sorbitan monooleate and oleic acid effectively protect the aggregation between particles. It is also evident from the evaluation of powdered nanoparticles isolated from the trap solution by thermogravimetric analysis (TGA) that these protective agents adsorb on the surface of the particles. On the other hand, the aggregates of silver nanoparticles were formed in the cases using oleic alcohol and methyl oleate. Silver nanoparticles were obtained in the case of oleylamine but the material efficiency of silver was extremely low. As a result, our systematic investigation using the improved VEROS method disclosed suitable protective agents in the preparation of silver nanoparticles with the physical method.
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http://dx.doi.org/10.1166/jnn.2018.14392DOI Listing
April 2018

Impact of mild to moderate COPD on feasibility and prognosis in non-small cell lung cancer patients who received chemotherapy.

Int J Chron Obstruct Pulmon Dis 2017 11;12:3541-3547. Epub 2017 Dec 11.

Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.

Background: Non-small cell lung cancer (NSCLC) is the predominant cause of death in patients with COPD, and the severity of COPD in NSCLC patients is classified mainly as mild to moderate. Most advanced NSCLC patients with mild to moderate COPD are treated with chemotherapy; however, the feasibility for and prognosis after chemotherapy of these patients are not well understood. The aim of this study was to elucidate the impact of mild to moderate COPD on the feasibility for and prognosis after chemotherapy in NSCLC patients.

Patients And Methods: A retrospective review was performed on 268 NSCLC patients who received first-line chemotherapy from 2009 to 2014 in our institution. Finally, 85 evaluable patients were included in this study. The clinical characteristics, toxicity profile, objective response rate, and prognosis were analyzed and compared between patients with mild to moderate COPD and those without COPD (non-COPD).

Results: Forty-three patients were classified as COPD (27 cases mild and 16 cases moderate) and 42 patients as non-COPD. The COPD group were older and had fewer never-smokers than the non-COPD group. The objective response rate did not differ between groups (=0.14). There was no significant difference in overall survival between COPD and non-COPD groups (15.0 and 17.0 months, log-rank test =0.57). In the multivariate Cox's proportional hazard model, the adjusted hazard ratio (HRadj) was statistically significant for male sex (HRadj =5.382, 95% CI: 1.496-19.359; =0.010), pathological diagnosis of adenocarcinoma (HRadj =0.460, 95% CI: 0.223-0.948; =0.035), and epithelial growth factor receptor negative mutation (HRadj =6.040, 95% CI: 1.158-31.497; =0.033), but not for the presence of COPD (HRadj =0.661, 95% CI: 0.330-1.325; =0.24). Toxicity profile in COPD group was favorable, as in the non-COPD group.

Conclusion: Mild to moderate COPD did not have a significant deleterious impact on toxicity and prognosis in NSCLC patients.
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http://dx.doi.org/10.2147/COPD.S149456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5729822PMC
September 2018

Exercise hypoxaemia as a predictor of pulmonary hypertension in COPD patients without severe resting hypoxaemia.

Respirology 2017 01 28;22(1):120-125. Epub 2016 Jul 28.

Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.

Background And Objective: Pulmonary hypertension (PH) in COPD is associated with morbidity and mortality. Previous studies showed a relationship between resting hypoxaemia and PH, but little is known about the relationship between exercise hypoxaemia and PH in COPD without resting hypoxaemia.

Methods: A retrospective observational study of COPD patients without resting hypoxaemia was conducted to evaluate the relationships between exercise hypoxaemia and pulmonary haemodynamics. Clinical characteristics, pulmonary function, blood gas analysis, 6-min walk distance (6MWD) and oxygen saturation of peripheral artery (SpO ) at the end of the 6-min walk test (6MWT) were reviewed. Correlation analysis and stepwise regression analysis were performed to identify the predictor of mean pulmonary artery pressure (mPAP).

Results: Eighty-four consecutive patients with a mean predicted forced expiratory volume in 1 s (FEV ) of 47 ± 21% were evaluated. In univariate analysis, mPAP had negative correlations with age (r = -0.27, P < 0.05), arterial partial pressure of oxygen (PaO , r = -0.24, P < 0.05), % predicted forced vital capacity (FVC, r = -0.28, P < 0.05), % predicted FEV (r = -0.40, P < 0.001), FEV /FVC ratio (r = -0.33, P < 0.005), % predicted diffusion capacity for carbon monoxide (DL , r = -0.40, P < 0.001), 6MWD (r = -0.40, P < 0.001) and SpO at the end of the 6MWT (r = -0.74, P < 0.001). In stepwise regression analysis, SpO at the end of the 6MWT and 6MWD remained as independent predictors of mPAP (R  = 0.60). In receiver operating characteristic (ROC) analysis, SpO at the end of the 6MWT presented an area under the curve of 0.896 for the prediction of PH, with a sensitivity of 0.86 and specificity of 0.84 for the cut-off point of 81%.

Conclusion: In addition to 6MWD, exercise hypoxaemia indicates PH in patients with COPD without resting hypoxaemia.
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http://dx.doi.org/10.1111/resp.12863DOI Listing
January 2017

Investigation of Ultraviolet Light Curable Polysilsesquioxane Gate Dielectric Layers for Pentacene Thin Film Transistors.

J Nanosci Nanotechnol 2016 Apr;16(4):3327-31

Polysilsesquioxane (PSQ) comprising 3-methacryloxypropyl groups was investigated as an ultraviolet (UV)-light curable gate dielectric-material for pentacene thin film transistors (TFTs). The surface of UV-light cured PSQ films was smoother than that of thermally cured ones, and the pentacene layers deposited on the UV-Iight cured PSQ films consisted of larger grains. However, carrier mobility of the TFTs using the UV-light cured PSQ films was lower than that of the TFTs using the thermally cured ones. It was shown that the cross-linker molecules, which were only added to the UV-light cured PSQ films, worked as a major mobility-limiting factor for the TFTs.
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http://dx.doi.org/10.1166/jnn.2016.12292DOI Listing
April 2016

High-Mobility 6,13-Bis(triisopropylsilylethynyl) Pentacene Transistors Using Solution-Processed Polysilsesquioxane Gate Dielectric Layers.

J Nanosci Nanotechnol 2016 Apr;16(4):3273-6

Polysilsesquioxane (PSQ) is a low-temperature curable polymer that is compatible with low-cost plastic substrates. We cured PSQ gate dielectric layers by irradiation with ultraviolet light at ~60 °C, and used them for 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) thin film transistors (TFTs). The fabricated TFTs have shown the maximum and average hole mobility of 1.3 and 0.78 ± 0.3 cm2V-1s-1, which are comparable to those of the previously reported transistors using single-crystalline TIPS-pentacene micro-ribbons for their active layers and thermally oxidized SiO2 for their gate dielectric layers. Itis therefore demonstrated that PSQ is a promising polymer gate dielectric material for low-cost organic TFTs.
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http://dx.doi.org/10.1166/jnn.2016.12293DOI Listing
April 2016

Bronchial occlusion with Endobronchial Watanabe Spigots for massive hemoptysis in a patient with pulmonary Mycobacterium avium complex infection.

Respir Investig 2016 Mar 20;54(2):121-4. Epub 2015 Nov 20.

Department of Respiratory Medicine, National Hospital Organization, Higashinagoya National Hospital, 5-101 Umemorizaka, Meito-ku, Nagoya, Aichi 468-8620, Japan. Electronic address:

The safety of occlusion with Endobronchial Watanabe Spigots (EWS) for the management of hemoptysis associated with chronic respiratory tract infection has not yet been established. A 57-year-old woman diagnosed as having pulmonary Mycobacterium avium complex (MAC) infection presented to our hospital with hemoptysis. She underwent bronchoscopy for bronchial occlusion with EWS, which resulted in the resolution of hemoptysis. Subsequently, she underwent bronchial artery embolization and then EWS were removed. During placement of EWS, no worsening of infection was observed. After removal of EWS, there was no recurrence of hemoptysis. Bronchial occlusion with EWS for hemoptysis associated with pulmonary MAC infection can be performed safely.
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http://dx.doi.org/10.1016/j.resinv.2015.09.004DOI Listing
March 2016

A single-molecule force-spectroscopic study on stabilization of G-quadruplex DNA by a telomerase inhibitor.

Analyst 2014 Aug;139(16):4037-43

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510, Japan.

Single-molecule force spectroscopy was carried out using AFM force measurements for the purpose of direct observation of the stabilization of G-quadruplex DNA by a telomerase inhibitor, which is 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin tetrakis(p-toluenesulfonate) (TMPyP). In AFM force measurements, we used an AFM tip and an Au substrate modified chemically with terminal-biotinylated telomere DNA and streptavidin, respectively. The telomere DNA was fully stretched by the AFM tip based on the bridge formation between the AFM tip and the Au substrate through the streptavidin-biotin interaction. The force-extension curves, which reflected the stretching of a single DNA molecule, were distinguished from all of the curves, judging from the rupture force and the contour length. The selected curves were analyzed using a worm-like chain model, and one of the fitting parameters, persistence length (lp), was used as an index for the stabilization of the G-quadruplex structure. Consequently, the lp value was significantly increased by the addition of TMPyP under the experimental conditions where the G-quadruplex structure could be formed. On the other hand, the value was hardly changed by the addition of TMPyP under the conditions except the above. Furthermore, the methodology developed and demonstrated in this work was applied to evaluate the stabilization of G-quadruplex DNA by other telomerase inhibitors such as ethidium bromide and p-xylene-bis(N-pyridinium bromide).
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http://dx.doi.org/10.1039/c4an00439fDOI Listing
August 2014

Highly selective recognition of acetate and bicarbonate by thiourea-functionalised inverse opal hydrogel in aqueous solution.

Chem Commun (Camb) 2013 Jan;49(9):886-8

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, Sakae-dani 930, Wakayama 640-8510, Japan.

We have synthesised an inverse opal hydrogel functionalised with a thiourea moiety as an anion recognition site. The resulting hydrogel showed remarkable changes of its structural colour with respect to acetate and bicarbonate ions selectively in aqueous solution, indicating a potential as colorimetric sensing materials for hydrophilic anions.
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http://dx.doi.org/10.1039/c2cc38052hDOI Listing
January 2013

Ultra-high-sensitive extraction-photometric determination of sodium ion using flow injection analysis with a chromogenic calix[4]arene derivative and a laser interferometric photothermal detector.

Anal Chem 2012 Apr 30;84(8):3710-5. Epub 2012 Mar 30.

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, Wakayama, Japan.

A novel flow injection analysis (FIA) system for ultra-high-sensitive determination of Na(+), which involves laser interferometric photothermal equipment as the detector, was designed using a proton-dissociable chromogenic calix[4]arene derivative with a dinitrophenol moiety as the extraction-photometric reagent. The chromogenic calix[4]arene derivative showed an excellent extractability toward Na(+), which reflected the cation-complexing property of the tetraethyl ester derivative of calix[4]arene. As the calibration graph of the Na(+) concentration could be successfully obtained at the nanomolar level by this method, the proposed FIA system was found to be promising for highly sensitive determination of Na(+) in very dilute samples such as supply water and cooling water in power plants.
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http://dx.doi.org/10.1021/ac300250bDOI Listing
April 2012

Morphological changes in vesicles and release of an encapsulated compound triggered by a photoresponsive Malachite Green leuconitrile derivative.

Langmuir 2010 Apr;26(8):5444-50

Department of Chemical Engineering, Nara National College of Technology, Yata 22, Yamato-koriyama, Nara 639-1080, Japan.

Photoinduced morphological changes in phosphatidylcholine vesicles are triggered by a Malachite Green leuconitrile derivative dissolved in the lipidic membrane, and are observed at Malachite Green derivative/lipid ratios <5 mol %. This Malachite Green derivative is a photoresponsive compound that undergoes ionization to afford a positive charge on the molecule by UV irradiation. The Malachite Green derivative exhibits amphiphilicity when ionized photochemically, whereas it behaves as a lipophilic compound under dark conditions. Cryo-transmission electron microscopy was used to determine vesicle morphology. The effects of the Malachite Green derivative on vesicles were studied by dynamic light scattering and fluorescence resonance energy transfer. Irradiation of vesicles containing the Malachite Green derivative induces nonspherical vesicle morphology, fusion of vesicles, and membrane solubilization, depending on conditions. Furthermore, irradiation of the Malachite Green derivative induces the release of a vesicle-encapsulated compound.
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http://dx.doi.org/10.1021/la904190cDOI Listing
April 2010

Application of gold nanoparticles to spectrophotometric sensing of hydrophilic anions based on molecular recognition by urea derivative.

Anal Sci 2009 Feb;25(2):261-5

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, Japan.

We have prepared gold nanoparticles (GNPs) modified with a thiol compound that possesses a phenylurea moiety for the spectrophotometric sensing of hydrophilic anions, such as dihydrogen phosphate, based on changes in the surface plasmon absorption of the GNP. We examined the spectral change of phenylurea-modified GNP in dichloromethane upon the addition of various anions as tetrabutylammonium salts to the solution. The GNP showed increasing plasmon intensity with the concentration of dihydrogen phosphate. For a control experiment with an inactive hexanethiolate-modified GNP, such an ion-selective change in the plasmon band was not observed. Furthermore, in order to realize the spectrophotometric detection of hydrophilic anions in water using GNP with the urea functionality, we attempted to prepare bifunctional GNP modified with both the phenylurea derivative and a water-soluble thiol (e.g., L-cysteine). The resulting bifunctional GNP showed anion-selective changes in the plasmon band accompanied by increasing absorbance at a longer wavelength due to GNPs aggregation.
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http://dx.doi.org/10.2116/analsci.25.261DOI Listing
February 2009

Analytical and separation chemistry by taking advantage of organic photochromism combined with macrocyclic chemistry.

Anal Sci 2009 Jan;25(1):9-20

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, Japan.

Photochromic crown compounds, such as monomeric and polymeric crown compounds incorporating spirobenzopyran, spironaphthooxazine, spirobenzothiapyran, Malachite Green, and Crystal Violet moieties, were synthesized for applications in the fields of analytical and separation chemistry. The photochromic crown compounds, especially crowned spirobenzopyran derivatives, were applied to metal ion extraction, extraction spectrophotometry, membrane transport, and ion chromatography, the sensitivity and selectivity of which were controlled and enhanced photochemically. Also, micelles and vesicles containing lipophilic crowned spirobenzopyrans and Malachite Greens were tested for their usefulness in spectrophotometric and fluorometric metal-ion determination and photocontrol of organic substance in aqueous systems. The polymeric crowned spirobenzopyrans were tried to use as a photochemical valve based on photochemical rheology changes. Moreover, attempts were made to directly observe photoinduced aggregation of the spirobenzopyran moiety and photoresponsive rheology changes of the polymeric crowned spirobenzopyran, by using chemical force microscopy.
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http://dx.doi.org/10.2116/analsci.25.9DOI Listing
January 2009

Molecular design of tetraazamacrocyclic derivatives bearing a spirobenzopyran and three carboxymethyl moieties and their metal-ion complexing behavior.

Anal Sci 2008 Apr;24(4):463-9

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, Wakayama, Japan.

Tetraazacyclododecane and tetraazacyclotetradecane derivatives bearing a spirobenzopyran and three carboxymethyl moieties, 1 and 2, and a diethylenetriamine derivative bearing a spirobenzopyran and four carboxymethyl moieties 3 were synthesized. The isomerization behaviors based on the spirobenzopyran moiety of these ligands were studied by UV-visible spectrophotometry in aqueous solutions containing various metal ions at neutral pH. These ligands formed stable 1:1 complexes with lanthanide ions, while the spirobenzopyran moiety was isomerized to its corresponding merocyanine form even under dark conditions. In aqueous solutions containing a lanthanide ion, the absorption spectra of 1 or 2 showed remarkable blue shifts, while absorbances at the maximum absorption wavelengths in the visible region were enhanced; such changes are attributable to the isomerization to the merocyanine form of the spirobenzopyran moiety. These results suggest that the phenolate anion of the merocyanine moiety interacts very strongly with a lanthanide ion bound by the complexing moiety because of the high charge density of lanthanide ions. In contrast, the absorbance of merocyanine form was decreased by the complexation of the macrocyclic ligand with transition metal ions, such as Cu2+ and Zn2+. This result indicates that macrocyclic ligands, 1 and 2, formed complexes with transition metal ions only by the aminocarboxylate moieties, and the phenolate ion of merocyanine moiety was not able to participate in the complexation. This conclusion was also demonstrated by density functional theory calculations.
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http://dx.doi.org/10.2116/analsci.24.463DOI Listing
April 2008

Photoinduced micelle-to-vesicle transition and encapsulation of by photoresponsive Malachite Green derivative.

Soft Matter 2008 Feb;4(3):560-563

Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, Sakae-dani 930, Wakayama 640-8510, Japan.

UV irradiation on a Malachite Green leuconitrile derivative afforded a cationic surfactant in aqueous solutions of sodium bis(2-ethylhexyl) sulfosuccinate. The result involved a micelle-to-vesicle transition and encapsulation which have been investigated by trapping experiment. Transmission electron microscopy was applied for direct observation of vesicle formation. The micellar solution was studied under dark conditions with pyrene emission spectra.
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http://dx.doi.org/10.1039/b716640kDOI Listing
February 2008

Fabrication and enzymatic degradation of fibronectin-based ultrathin films.

J Biomater Sci Polym Ed 2007 ;18(12):1565-73

Department of Tissue Engineering and Cell Therapy, Institute of Biomedical Research and Innovation, 1-5-4 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan.

Novel fibronectin (FN)-based ultrathin films were prepared by layer-by-layer (LbL) assembly. Among the various combinations of extracellular matrix (ECM) proteins and glycosaminoglycans (GAGs) such as FN, gelatin (G), alpha-elastin (E) and heparin (Hep), FN/Hep, FN/G and FN/E nanofilms were successfully fabricated in phosphate buffer solutions (pH 7.4). The film thickness of the nanofilms, in which each component can interact with each other by FN-specific interactions, was larger than that of other LbL films (E/Hep, G/E and G/Hep) prepared by electrostatic interactions. The FN/G film was rapidly decomposed by treatment with elastase, thus demonstrating, the enzymatic biodegradability of the nanofilm. We prepared the FN/heparinoid multilayers composed of FN and dextran sulfate (Dex), and its thickness was much larger than that of the FN/alpha-poly(L-lysine hydrochloride) (PLL) film prepared by LbL assembly using common electrostatic interactions. Furthermore, the FN/G and FN/Dex nanofilms prepared by FN-specific interaction were more stable in Eagle's MEM with 10% fetal bovine serum (FBS) than the electrostatic assembling films, FN/PLL and PLL/Dex. FN-based multilayers composed of FN and ECM components can be useful as artificial ECM films for tissue engineering and other biomedical applications.
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March 2008

Fabrication of cellular multilayers with nanometer-sized extracellular matrix films.

Angew Chem Int Ed Engl 2007 ;46(25):4689-92

Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.

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http://dx.doi.org/10.1002/anie.200701089DOI Listing
October 2007

Cutting edge: CD8+CD122+ regulatory T cells produce IL-10 to suppress IFN-gamma production and proliferation of CD8+ T cells.

J Immunol 2005 Dec;175(11):7093-7

Department of Immunology, Nagoya University Graduate School of Medicine, Nagoya, Japan.

We recently identified CD8+CD122+ regulatory T cells that directly control CD8+ and CD4+ cells without intervention of APCs. In this study, we investigated the effector mechanism of CD8+CD122+ regulatory T cells by using an in vitro regulation system. The profile of cytokine expression revealed that IL-10 was predominantly produced by CD8+CD122+ cells, whereas other cytokines were similarly expressed in CD8+CD122+ cells and CD8+CD122- cells. Suppression of both proliferation and IFN-gamma production by CD8+CD122- cells by CD8+CD122+ cells was blocked by adding anti-IL-10 Ab to the culture but not by adding anti-TGF-beta Ab. When IL-10 was removed from the conditioned medium from CD8+CD122+ cells, the conditioned medium no longer showed regulatory activity. Finally, CD8+CD122+ cells from IL-10-deficient mice had no regulatory activity in vitro and reduced regulatory activity in vivo. Our results clearly indicate that IL-10 is produced by CD8+CD122+ cells and mediates the regulatory activity of these cells.
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http://dx.doi.org/10.4049/jimmunol.175.11.7093DOI Listing
December 2005

New fluorescence method for the determination of the critical micelle concentration by photosensitive monoazacryptand derivatives.

Langmuir 2005 Jul;21(15):6688-95

Department of Molecular Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

A novel fluorescence method for the determination of the critical micelle concentration (cmc) is reported. The cmc values of nonionic and anionic surfactants were evaluated utilizing a photosensitive monoazacryptand-Ba2+ complex, whose fluorescence intensity is sensitively changed by environmental conditions based on the photoinduced electron transfer (PET) mechanism as a fluorescent probe (PET method). Based on a comparison of the cmc values obtained by the PET method versus those obtained by conventional fluorescence-based methods as well as the values reported in the literature, one can conclude that the PET method is useful for the cmc determination. In particular, the PET method was more effective for the cmc determination of nonionic surfactants with very low cmc values (< 10(-5) M) than any other fluorescence-based method. In the cases of anionic surfactants, the PET method revealed the formation of the premicellar aggregates comprised of surfactant molecules and fluorescent probes below the cmc. Moreover, the hydrophobicity around the monoazacryptand-Ba2+ complex incorporated into various nonionic surfactant micelles was evaluated by this PET method.
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http://dx.doi.org/10.1021/la050206jDOI Listing
July 2005

Fluorometric sensing of alkali metal and alkaline earth metal cations by novel photosensitive monoazacryptand derivatives in aqueous micellar solutions.

Org Biomol Chem 2005 May 12;3(9):1787-94. Epub 2005 Apr 12.

Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology, 5-16-1, Omiya, Asahi-ku, Osaka 535-8585, Japan.

Novel monoazacryptand-type fluorescent chemosensors, (derived from an 18-crown-6) and (derived from a 15-crown-5) both with a pyrene ring as their photoresponsive moiety, were synthesized. Their fluorescence properties for alkali metal and alkaline earth metal cations in water were then examined. The detection of metal cations was accomplished by a change in the fluorescence intensity of the host compounds, based on a photoinduced electron transfer (PET) mechanism. In aqueous solution, showed little fluorescence upon the addition of Ba2+ because of the very weak complexation with Ba2+, but the presence of micelles of polyoxyethylene(10) isooctylphenyl ether (Triton X-100) enabled to show highly sensitive and selective Ba2+ detection among alkali metal and alkaline earth metal cations. With respect to the selective fluorescent detection of important metal cations (Na+, K+, Mg2+, Ca2+) relevant to living organisms, was found to detect K+ with high selectivity in aqueous micellar solutions of polyoxyethylene(20) sorbitan monostearate (Tween-60). The selectivity for metal cations was mainly dependent on the goodness of fit of the host cavity and the metal cation size. In the presence of anionic surfactants, detected alkaline earth metal cations more effectively than alkali metal cations.
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http://dx.doi.org/10.1039/b501233cDOI Listing
May 2005

Synthesis of double-armed lariat ethers with pyrene moieties at each end of two sidearms and their fluorescence properties in the presence of alkali metal and alkaline earth metal cations.

J Org Chem 2004 Jun;69(13):4403-11

Department of Molecular Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

Two types of double-armed lariat ether derivatives having pyrene moieties at each end of two sidearms, (3x + 1)-crown-x derivatives 1 (x = 5), 2 (x = 6), and 3 (x = 4) (type A) and 3y-crown-y derivatives, 6 (y = 5) and 7 (y = 6) (type B), were synthesized, and their complexation behavior toward alkali metal and alkaline earth metal cations was examined by fluorescence spectroscopy. Pyrene excimer emission decreased accompanied by an increase in monomer emission upon metal ion complexation. This finding is ascribed to the change of the spatial distance of two pyrene rings by movement suppression of both the crown ring and one of the two sidearms based on complexation with the metal cation. The selectivity for alkaline earth metal cations was highly dependent on the fitness of the host cavity and the guest size. Although most of the fluorophores did not respond to alkali metal cations, only trans-7a containing an 18-crown-6 ring showed K(+) selectivity.
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http://dx.doi.org/10.1021/jo0498056DOI Listing
June 2004
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