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Enteropathy and intestinal malabsorption in patients treated with antihypertensive drugs. A retrospective cohort study. Saudi Med J 2024; 45:437-441. [PMID: 38657980 DOI: 10.15537/smj.2024.45.4.20230739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 01/16/2024] [Indexed: 04/26/2024] Open
Abstract
OBJECTIVES To investigate differences in the incidence of enteropathy or intestinal malabsorption in patients taking angiotensin II receptor blockers (ARBs), angiotensin-converting enzyme inhibitor (ACEI), calcium channel blocker (CCB), and beta blockers (BBs) at a single center in Korea. METHODS In this retrospective study, we utilized data from the Yangsan electronic medical records to identify 129,169 patients. These individuals were prescribed olmesartan, other ARBs, ACEI, CCB, and BBs between November 2008 and February 2021. RESULTS Of the 44,775 patients, 51 (0.11%) were observed to have enteropathy or intestinal malabsorption. Compared with the ACEI group, the adjusted odds ratios (ORs) for enteropathy and intestinal malabsorption were OR=1.313 (95% confidence interval [CI]: [0.188-6.798], p=0.893) for olmesartan, OR=0.915 (95% CI: [0.525-1.595], p=0.754) for the other ARBs, OR=0.928 (95% CI: [0.200-4.307]; p=0.924) for the CCB, and OR=0.663 (95% CI: [0.151-2.906]; p=0.586) for the BBs group. These findings were adjusted for factors such as age, gender, duration of antihypertensive medication, and comorbidities. CONCLUSION In a retrospective cohort study of patients on antihypertensive medications, no significant difference was found in the incidence of enteropathy or intestinal malabsorption when ACEI was compared to olmesartan, other ARBs, CCB, and BBs.
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Association between pulse pressure and low muscle mass in Korean adults: A nationwide cross-sectional study. Medicine (Baltimore) 2023; 102:e36644. [PMID: 38206714 PMCID: PMC10754618 DOI: 10.1097/md.0000000000036644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 11/22/2023] [Indexed: 01/13/2024] Open
Abstract
Sarcopenia is characterized by a loss of muscle mass and strength and is associated with a high risk of cardiovascular events and increased mortality. Pulse pressure (PP) serves as a marker for changes in heart structure and function, as well as arterial stiffness. A high PP also increases the risk of cardiovascular disease and all-cause mortality. However, the relationship between PP and sarcopenia is poorly understood. We used the data of participants of the Korea National Health and Nutrition Examination Survey (KNHANES) of 2008 to 2011. Participants were divided into a control group (PP < 40 mm Hg) and a high-PP group (PP ≥ 40 mm Hg). PP was calculated by subtracting the diastolic blood pressure (DBP) from the systolic blood pressure (SBP), and the low muscle index was assessed using appendicular skeletal muscle mass (ASM) normalized by body mass index (BMI). Multiple logistic regression analyses were performed to examine the association between PP and the prevalence of low muscle mass, adjusting for potential confounders. The high-PP group had a higher age, SBP, DBP, and prevalence of hypertension, diabetes and hyperlipidemia than the control group. The high-PP group had a higher prevalence of low muscle mass than the control group in all models. A high PP is significantly associated with a higher prevalence of low muscle mass. Therefore, PP monitoring may help identify individuals at risk of sarcopenia and guide interventions to improve health outcomes.
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Functionalization of pine sawdust biochars with Mg/Al layered double hydroxides to enhance adsorption capacity of synthetic azo dyes: Adsorption mechanisms and reusability. Heliyon 2023; 9:e14142. [PMID: 36923877 PMCID: PMC10008992 DOI: 10.1016/j.heliyon.2023.e14142] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 02/13/2023] [Accepted: 02/23/2023] [Indexed: 03/06/2023] Open
Abstract
This study determined that the adsorption of azo dyes, Methyl Orange (MO) and Sunset Yellow FCF (SYF), using the pristine pine sawdust biochar (PSB) and post-modified PSB with Mg/Al layered double hydroxides (PSB-LDHMgAl) was examined to offer valuable information into the differences in their adsorption mechanisms. Although a lower specific surface area of PSB-LDHMgAl (147.2 m2 g-1) than PSB (495.7 m2 g-1), LDHMgAl were successfully functionalized on the PSB surface through co-precipitation, which was highly related to the improvements of adsorption capacity of PSB-LDHMgAl toward MO and SYF. The MO and SYF adsorption kinetics by PSB and PSB-LDHMgAl were confirmed to the pseudo-second-order and considered chemisorption. The adsorption capacity of MO and SYF adsorbed onto PSB-LDHMgAl (MO = 21.8 mg g-1, SYF = 23.6 mg g-1) were significantly higher than that of PSB (MO = 2.2 mg g-1, SYF = 1.6 mg g-1). The adsorption isotherms of MO and SYF by PSB were well fitted by Freundlich isotherm, whereas the MO and SYF via PSB-LDHMgAl were by Langmuir isotherm. Even after 3 adsorption-desorption cycles using desorbents, the PSB-LDHMgAl remained excellent reusability (reuse efficiency: >81.2%). These findings suggest that post-modification with LDHMgAl might accelerate the adsorption performance (i.e., electrostatic interaction) of azo dyes to PSB in water.
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Engineered kirigami design of PVDF-Pt core-shell nanofiber network for flexible transparent electrode. Sci Rep 2023; 13:2582. [PMID: 36788304 PMCID: PMC9929047 DOI: 10.1038/s41598-023-29812-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
Abstract
Nanofiber networks comprising polymer-metal core-shell structures exhibit several advantages, such as high uniformities and considerable flexibilities. Additionally, the flexibility of the nanofiber network may be further enhanced by engineering the network topology. Therefore, in this study, the topologies of polyvinylidene fluoride (PVDF)-Pt core-shell nanofiber (CS NF) networks were engineered, and their performances as flexible transparent electrodes were comprehensively evaluated. Three distinct topologies of nanofiber networks were induced using circular, square, and rectangular electrode collectors. A highly uniform nanofiber network was obtained using the square electrode collector, which generated a high density of nanofiber junctions (nodes). Consequently, this nanofiber network exhibited the smallest sheet resistance [Formula: see text] and lowest optical transmittance [Formula: see text] among the three CS NF networks. In contrast, nanofiber bundles were frequently formed in the randomly aligned CS NF network prepared using the circular electrode collector, reducing the node density. As a result, it simultaneously exhibited a very small [Formula: see text] and high [Formula: see text], generating the largest percolation figure of merit [Formula: see text]. Under certain strain directions, the CS NF network with the engineered topology exhibited a significantly enhanced mechanical durability. Finally, a flexible piezoelectric pressure sensor with CS NF network electrodes was fabricated and its sensing performance was excellent.
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Association between Serum Folic Acid Levels and Asthma in the Korean Population: A Study Based on the 2016-2018 Korea National Health and Nutrition Examination Survey. Korean J Fam Med 2022; 43:241-245. [PMID: 35903047 PMCID: PMC9334715 DOI: 10.4082/kjfm.21.0143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/17/2021] [Accepted: 01/14/2022] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Folic acid is involved in inflammatory reactions; however, the association between folic acid and allergic diseases, particularly asthma, remains unclear. Thus, this study aimed to evaluate the association between serum folic acid levels and asthma in Koreans. METHODS This study analyzed the serum folic acid levels of 6,615 individuals included in the 2016-2018 Korea National Health and Nutrition Examination Survey. The prevalence of asthma was determined using a questionnaire that identified cases of physician-diagnosed asthma. The relationship between serum folic acid levels and asthma was analyzed using logistic regression analysis. RESULTS Multiple logistic regression analysis showed that a 1 ng/mL increase in serum folic acid level significantly reduced the risk of asthma after adjusting for confounding factors including sex, age, household income, current smoking, current alcohol use, and body mass index (odds ratio [OR], 0.930; 95% confidence interval [CI], 0.876- 0.987; P=0.017). The relationship between the adjusted odds of asthma and serum folic acid levels were consistently inverse (OR, 2.266; 95% CI, 1.126-4.420; P for trend=0.038). CONCLUSION Serum folic acid levels are inversely associated with physician-diagnosed asthma in the Korean population.
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Combined use of energy-based interventions with low-dose isotretinoin for the treatment of inflammatory acne: An retrospective cohort analysis. J Cosmet Dermatol 2022; 21:4383-4391. [PMID: 35723897 DOI: 10.1111/jocd.15171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 05/22/2022] [Accepted: 06/15/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND The combined use of oral isotretinoin with energy-based interventions including fractional microneedle radiofrequency, pulsed dye laser, and ablative fractional laser is an effective way to treat moderate-to-severe inflammatory acne lesions. However, studies regarding its efficacy and safety are limited. AIMS This study aimed to assess the efficacy and safety of a treatment using low-dose isotretinoin with energy-based interventions for inflammatory acne. PATIENTS AND METHODS This retrospective cohort study included 126 patients who were diagnosed with inflammatory acne and were treated with systemic isotretinoin for at least 3 months. Patients were divided into EBD (energy-based intervention) (n=82) and non-EBD groups (n=44). Clinical outcomes of both groups were assessed using medical records and digital photographs. RESULTS After treatment, the modified Global Acne Grading Score of the EBD and non-EBD groups decreased by 35.1±17.2 and 25.6±10.1, respectively. The improvement in acne severity was significantly greater in the EBD group than in the non-EBD group. Cumulated isotretinoin dose and frequency of drug-related side effects were significantly higher in the non-EBD group than in the EBD group. CONCLUSION Combined treatment with low-dose isotretinoin and energy-based intervention is well tolerated and associated with positive responses in patients with inflammatory acne.
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Effect of Y₂O₃ Dispersion Method on the Microstructure Characteristic of Ni-Base Superalloy. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2021; 21:4955-4958. [PMID: 33691898 DOI: 10.1166/jnn.2021.19253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
An optimum route to fabricate the Ni-base superalloys with homogeneous dispersion of oxide nanoparticles is investigated. Two methods for developing a uniform dispersion of oxide nanopar-ticles are compared on the basis of the resulting microstructure. Microstructural analysis reveals that the calcined powder from polymeric additive solution with yttrium nitrate and polyvinyl alcohol represented more fine and uniform distribution of Ni, Y and O elements. The densified specimen by spark plasma sintering at 1000 °C using calcined powder exhibits fine microstructure with oxide nanoparticles compared with that using mechanically alloyed powder, presumably by the particle growth or agglomeration prevention from chelating reaction during the calcination step. The oxide particles in the sintered specimen is identified as Y-Al-O phase, formed by the reaction of Y₂O₃ with Al during calcination and sintering.
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Effect of Calcination Temperature on Photocatalytic Degradation Performance of Electrospun β-Ga₂O₃ Nanofibers. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2021; 21:4016-4021. [PMID: 33715736 DOI: 10.1166/jnn.2021.19247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In the present work, Ga₂O₃ nanofibers were successfully synthesized by electrospinning a solution of polyvinylpyrrolidone (PVP) and gallium nitrate, followed by temperature-controlled calcination treatment of the as-spun PVP and gallium nitrate composite nanofibers. The crystallinity and crystallite size of the Ga₂O₃ nanofibers can be readily controlled by varying the calcination temperature. From the physicochemical analysis results of the synthesized nanofiber, it was found that the nanofiber calcined at a higher temperature showed a higher crystallinity and a larger crystallite size. The photocatalytic degradation results on rhodamine-B (Rho B) revealed that the photocatalytic activity of the Ga₂O₃ nanofibers can be improved by optimizing the conflicting characteristics, crystallinity and crystallite size, through the control of the calcination temperature. The photocatalytic activity of a nanofiber calcined at 800 °C for the degradation of Rho B under ultraviolet irradiation exhibits 2.39 and 1.16 times higher than that of nanofibers synthesized at 700 °C and 900 °C, respectively, which is ascribed to relatively efficient charge transfer and dye molecule adsorption by its proper crystallinity and crystallite size.
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One-step synthesis of black TiO 2-x microspheres by ultrasonic spray pyrolysis process and their visible-light-driven photocatalytic activities. ULTRASONICS SONOCHEMISTRY 2021; 74:105557. [PMID: 33901752 PMCID: PMC8094901 DOI: 10.1016/j.ultsonch.2021.105557] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 04/06/2021] [Accepted: 04/12/2021] [Indexed: 06/12/2023]
Abstract
Black TiO2-x has recently emerged as one of the most promising visible-light-driven photocatalysts, but current synthesis routes that require a reduction step are not compatible with cost-effective mass production and a relatively large particle such as microspheres. Herein, we demonstrate a simple, fast, cost-effective and scalable one-step process based on an ultrasonic spray pyrolysis for the synthesis of black TiO2-x microspheres. The process utilizes an oxygen-deficient environment during the pyrolysis of titanium precursors to directly introduce oxygen vacancies into synthesized TiO2 products, and thus a reduction step is not required. Droplets of a titanium precursor solution were generated by ultrasound energy and dragged with continuous N2 flow into a furnace for the decomposition of the precursor and crystallization to TiO2 and through such a process spherical black TiO2-x microspheres were obtained at 900 °C. The synthesized black TiO2-x microsphere with trivalent titanium/oxygen vacancy clearly showed the variation of physicochemical properties compared with those of white TiO2. In addition, the synthesized microspheres presented the superior photocatalytic activity for degradation of methylene blue under visible light irradiation. This work presents a new methodology for a simple one-step synthesis of black metal oxides microspheres with oxygen vacancies for visible-light-driven photocatalysts with a higher efficiency.
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PBK Expression Is Associated With Prognosis of Patients With Oral Squamous Cell Carcinoma Treated With Radiotherapy: A Retrospective Study. Anticancer Res 2021; 41:2177-2182. [PMID: 33813430 DOI: 10.21873/anticanres.14991] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/05/2021] [Accepted: 03/10/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND/AIM To investigate the impact of PDZ-binding kinase (PBK) on the clinical outcome of patients with oral squamous cell carcinoma (OSCC) who received radiotherapy. PATIENTS AND METHODS PBK immunoreactivity of cancer specimens obtained from 179 patients with primary OSCC was analyzed by immunohistochemistry. RESULTS High PBK expression in tumor cells tended to be associated with advanced N-stage. The 5-year survival rate was greater for patients with high total PBK expression than in those with low PBK expression. After adjustment, high PBK remained associated with a favorable outcome. In subgroups according to tumor stage, the prognostic role was significant in patients with stage III/IV rather than those with stage I/II disease. CONCLUSION We suggest that PBK expression should be used as an independent prognostic marker for patients with OSCC treated with radiotherapy, especially for those with advanced-stage disease.
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Facile synthesis of hierarchical CuS microspheres with high visible-light-driven photocatalytic activity. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112782] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Association Between Weekend Catch-Up Sleep and Metabolic Syndrome with Sleep Restriction in Korean Adults: A Cross-Sectional Study Using KNHANES. Diabetes Metab Syndr Obes 2020; 13:1465-1471. [PMID: 32431530 PMCID: PMC7200717 DOI: 10.2147/dmso.s247898] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/15/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Many researchers have identified that adequate sleep duration is linked to the quality of life and metabolic diseases. Nowadays, it is hard to take enough sleep, so weekend catch-up sleep (CUS) may be an alternative option in modern society. To our knowledge, no previous studies reported the association between weekend CUS and metabolic syndrome, especially in the Korean population. OBJECTIVE We investigated the association between weekend CUS and the prevalence of metabolic syndrome in Korean adults (≥20 years old) with less than 6 hours of average weekday sleep. PATIENTS AND METHODS A total of 1,453 individuals were selected from the Korean National Health and Nutrition Examination Survey. Weekend CUS was divided into four categories: ≤0 hour, 0-1 hour, 1-2 hours, and ≥2 hours. Odds ratios (ORs) with 95% confidence intervals (CIs) were derived by univariate and multivariate logistic regression analyses. RESULTS Participants with weekend CUS ≥1 hour had decreased risk of metabolic syndrome in univariate analysis (CUS 1-2 hours: OR: 0.413, 95% CI: 0.301-0.568; CUS ≥2 hours: OR: 0.382, 95% CI 0.296-0.493). Weekend CUS 1-2 hours reduced the risk of metabolic syndrome in multivariate logistic regression analysis (OR: 0.552, 95% CI: 0.369-0.823). Based on the age group analysis, weekend CUS ≥1 hour reduced the metabolic syndrome among those aged 20-39 and 40-65 (20-39: CUS 1-2 hours OR: 0.248, 95% CI: 0.078-0.783, CUS ≥2 hours OR: 0.374, 95% CI: 0.141-0.991; 40-65: CUS 1-2 hours OR: 0.507, 95% CI 0.309-0.832 CUS ≥2 hours OR: 0.638, 95% CI: 0.415-0.981). CONCLUSION Weekend CUS was associated with a low risk of metabolic syndrome among Korean adults with sleep restriction.
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Synthesis, Morphology Control and Electromagnetic Wave Absorption Properties of Electrospun FeCo Alloy Nanofibers. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2016; 16:5190-5194. [PMID: 27483898 DOI: 10.1166/jnn.2016.12269] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recently, increasing interest has been focused on one-dimensional (1 D) magnetic nanomaterials that have significant anisotropic electromagnetic parameters and size effects that can be used to achieve improved shielding efficiency. In this study, the simple, low-cost and scalable synthesis of FeCo nanofibers is demonstrated by combining an electrospinning process with sequential thermal treatment involving calcination in air followed by reduction in H2 atmosphere. A citric acid has an influence on the morphology of the electrospun product. The as-spun precursor nanofibers are transformed into CoFe2O4 and FeCo phases through the sequential thermal treatment while maintaining the fibrous shapes. To evaluate the electromagnetic (EM) wave-absorbing abilities of the FeCo nanofibers, epoxy matrix composites with the nanofibers are fabricated. The composites show excellent EM wave absorption properties where the power loss of the FeCo nanofibers increased to 20 GHz without any degradation.
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Synthesis and Electromagnetic Wave Absorbing Property of BaTiO3@Fe Nanofibers with Core-Shell Structure . ACTA ACUST UNITED AC 2016. [DOI: 10.4150/kpmi.2016.23.1.38] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Synthesis of CuO Nanotubes with Controlled Diameters by Chemical Transformation of Cu Nanowires. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2015; 15:8166-8170. [PMID: 26726481 DOI: 10.1166/jnn.2015.11281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The simple, low-cost, and scalable transformation of Cu nanowires into CuO nanotubes was demonstrated by employing a thermal oxidation processes. The diameter of the Cu nanowires was controlled by utilizing anodic alumina templates with controlled pore sizes and this resulted in CuO nanotubes with various outer and inner diameters after thermal oxidation at 350 °C for 2 h. The morphology, phase, and microstructure of the transformed nanostructures were systematically investigated and it was confirmed that the transformation to the tubular nanostructures resulted from the Kirkendall effect caused by the different diffusion rates of Cu and O in CuxO generated during thermal oxidation. The transformed CuO nanotubes with the controlled diameters have a wide range of applications in photovolatics, catalysis, gas sensors, and field effect transistor because of their dimensionalities and large specific surface areas.
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Abstract
The hydrogen gas-sensing properties have been investigated of two types of thermochemical hydrogen (TCH) sensors composed of thermoelectric layers based on chalcogenide nanowire arrays and anodic aluminum oxide (AAO) templates. The monomorphic-type TCH sensor, which had only Bi2Te3 nanowire arrays, showed an output signal of 23.7 μV in response to 5 vol% hydrogen gas at room temperature, whereas an output signal of 215 μV was obtained from an n-p junction-type TCH sensor made of connected Bi2Te3 and Sb2Te3 nanowire arrays in an AAO template. Despite its small deposition area, the output signal of the n-p sensor was more than nine times that of the monomorphic sensor. This observation can be explained by the difference in electrical connections (parallel and serial conversions) in the TCH sensor between each type of nanowire array. Also, our n-p sensor had a wide detection range for hydrogen gas (from 400 ppm to 45 vol%) and a fast response time of 1.3 s at room temperature without requiring external power.
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Abstract
Correction for 'Three-dimensional hierarchical Te-Si nanostructures' by Jae-Hong Lim et al., Nanoscale, 2014, 6, 11697-11702.
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Abstract
Three-dimensional hybrid nanostructures (i.e., Te "nanobranches" on a Si "nanotrunk" or Te "nanoleaves" on a Si "nanotrunk") were synthesized by combining the gold-assisted chemical etching of Si to form Si "nanotrunks" and the galvanic displacement of Si to form Te "nanobranches" or "nanoleaves." By adjusting the composition of the electrolyte used for the galvanic displacement reaction, the shape of the Te nanostructures could be changed from nanoleaves to nanobranches. The Si nanotrunks with Te nanobranches showed stronger luminescent emission in the visible region, with their Raman spectrum having a higher wave number, owing to their grain size being larger. This suggested that the optical and photoelectrochemical properties of Te-Si hybrid nanostructures depend on their shape and size. Using this approach, it should be possible to fabricate various hierarchical nanostructures for use in photoelectronic and photoelectrochemical devices.
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Effect of calcination temperature on the photocatalytic properties of electrospun TiO2 nanofibers. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2014; 14:8005-8009. [PMID: 25942911 DOI: 10.1166/jnn.2014.9445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this study, TiO2 nanofibers with a high aspect ratio and a large specific surface area were synthesized using the electrospinning technique, and the effect of calcination temperature on their crystal structure, diameter, specific surface area and photocatalytic activity was systematically investigated. The electrospun, as-prepared PVP/TTIP nanofibers were several tens of micrometers in length with a diameter of 74 nm. TiO2 nanofibers with an average diameter of 50 nm were prepared after calcination at various temperatures. The calcination temperature significantly influenced the photocatalytic and material properties of TiO2 including grain size and specific surface area. When compared to other nanostructured TiO2 materials, such as commercial TiO2 nanoparticles (P25, Degussa), the TiO2 nanofibers exhibited greater photocatalytic activity for the degradation of acetaldehyde and ammonia.
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Fabrication and sensing property for conducting polymer nanowire-based biosensor for detection of immunoglobulin G. RESEARCH ON CHEMICAL INTERMEDIATES 2014. [DOI: 10.1007/s11164-014-1669-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Electrospun NiFe2O4 nanofibers as high capacity anode materials for Li-ion batteries. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2013; 13:7138-7141. [PMID: 24245211 DOI: 10.1166/jnn.2013.7698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ultra-long NiFe2O4 nanofibers were synthesized by a simple electrospinning process followed by thermal treatment. The NiFe2O4 nanofibers are polycrystalline with average diameter of 218 nm and lengths up to several millimeters. When evaluated for their lithium-storage properties, the electrospun NiFe2O4 nanofibers exhibit a high specific capacity that can exceed 660 mA h g(-1) after 100 cycles, along with enhanced cycling stability.
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Induced heat property of polyethyleneglycol-coated iron oxide nanoparticles with dispersion stability for hyperthermia. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2013; 13:6098-102. [PMID: 24205608 DOI: 10.1166/jnn.2013.7635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Fe3O4 nanoparticles have been used for hyperthermia treatment in an attempt to overcome various problems. When using hyperthermia treamtment, it is critical to control the surface modification of the particles. Magnetic nanoparticles tend to aggregate due to strong magnetic dipole--dipole attractions. The particles then have a high surface area and are of larger sizes, posing serious practical limitations. The nanoparticles are used to generate maximum heat and to maintain a constant heating temperature using the minimum magnetic nanoparticles dosage. In this study, we investigated the effect of PEG coated onto Fe3O4 nanoparticles. We tested the dispersion stability and repetitive heating property of nanoparticles for different PEG concentrations under an AC magnetic field. The results confirmed that the nanoparticles on a colloidal system maintained the heating properties of repetitve inductive heating as PEG concentration increased with dispersion stability. The nanoparticles with superior dispersion stability will be appropriate for hyperthermia applications in cancer treatments.
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Enhanced electrical and mechanical properties of silver nanoplatelet-based conductive features direct printed on a flexible substrate. ACS APPLIED MATERIALS & INTERFACES 2013; 5:5908-5913. [PMID: 23786607 DOI: 10.1021/am401757y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Noncontact direct printed conductive silver patterns with an enhanced flexural and bending strength and a proper electrical resistivity were fabricated using silver nanoplatelet inks without any surfactants for particle dispersion on a polyimide film. The microstructure, electrical resistivity, and bending strength of conductive features based on the nanoplatelets are systematically investigated and compared to nanoparticles to demonstrate superior properties. Nanoplatelets stack neatly on the substrate after noncontact direct printing, which minimizes void formation during sintering. This microstructure results in excellent resistivity on external repetitive bending stress as well as sufficiently lower electrical resistivity. It is believed to be a general conductive material to fabricate the noncontact direct printed conductive patterns with excellent mechanical stability for various flexible electronics, including solar cells, displays, RFID, and sensors.
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Synthesis and electromagnetic properties of FeNi alloy nanofibers using an electrospinning method. JOURNAL OF THE KOREAN CRYSTAL GROWTH AND CRYSTAL TECHNOLOGY 2012. [DOI: 10.6111/jkcgct.2012.22.5.218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Adhesion enhancement of ink-jet printed conductive copper patterns on a flexible substrate. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm31381b] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Characterization and stability of liposome-enveloped trypsin/Fe3O4 for drug delivery and drug release behavior. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2011; 11:4592-4595. [PMID: 21780503 DOI: 10.1166/jnn.2011.3638] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Liposome encapsulating Fe3O4 (liposome complexes) has been prepared for targeting a drug to a specific organ, as well as for MRI (magnetic resonance imaging) contrast agents. The objective of the present work was to investigate the Fe3O4 properties and the effects of chitosan concentration on the characteristics of chitosan-coated liposome complexes. They were characterized by DLS, FT-IR, XRD, VSM, UV-Vis spectrometer, TEM and phase-contrast microscopy. The average liposome complex size was approximately 500 nm, with individual Fe3O4 nanoparticle sizes of 10 nm. The drug incorporation efficiency of trypsin in liposome complexes was 65-69%, the drug release was sustained and the incorporated drugs had the magnetization properties of the liposome complexes. Incorporation of chitosan into the liposome bilayer decreased trypsin release from the liposome complexes due to an increased rigidity of the liposome membrane structure. Chitosan-coated liposome complexes showed a higher stability when compared with the stability of non-coated liposome complexes.
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Tunable synthesis of cuprous and cupric oxide nanotubes from electrodeposited copper nanowires. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2011; 11:1455-1458. [PMID: 21456211 DOI: 10.1166/jnn.2011.3343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Polycrystalline copper oxide nanostructures with different valence/oxidation states (i.e., Cu2O and CuO) were readily synthesized by thermal oxidation of single crystalline copper nanowires at relative low operating temperature (200 to 300 degrees C). Operating temperature of 200 to 250 degrees C in air oxidized copper to Cu2O and further increased temperature (i.e., 300 degrees C) led to form CuO nanostructures. The morphology of nanostructures significantly altered from nanowires to nanotubes which might be attributed to Kirkendall effect. The electrical resistivity of single copper nanowire, Cu2O and CuO nanotube were determined to be 3.4 x 10(-4), 33, and 211 omega cm, respectively.
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Preparation, characterization, cytotoxicity and drug release behavior of liposome-enveloped paclitaxel/Fe3O4 nanoparticles. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2011; 11:889-893. [PMID: 21446568 DOI: 10.1166/jnn.2011.3267] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Phospholipid vesicles encapsulating magnetic nanoparticles (liposome complexes) have been prepared for targeting a drug to a specific organ using a magnetic force, as well as for local hyperthermia therapy. Liposome complexes are also an ideal platform for use as contrast agents of magnetic resonance imaging (MRI). We describe the preparation and characterization of liposomes containing magnetite. These liposomes were obtained by thin film hydration method and Fe3O4 nanoparticles were synthesized by coprecipitation method. They were characterized by an electrophoretic light scattering spectrophotometer, the liposome complexes were subsequently coated using chitosan. We have further investigated the ability of the above formulation for drug delivery and MRI applications. We are specifically interested in evaluating our liposome complexes for drug therapy; hence, we selected paclitaxel for the combination study. The amount of paclitaxel was measured at 227 nm using a UV-Vis spectrophotometer. Cytotoxicity of liposome complexes was treated with the various concentrations of paclitaxel in PC3 cell lines. The structure and properties of liposome complexes were analyzed by FT-IR, XRD and VSM. The particle size was analyzed by TEM and DLS.
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Loading behavior of Pt nanoparticles on the surface of multiwalled carbon nanotubes having defects formed via microwave treatment. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2011; 11:479-483. [PMID: 21446480 DOI: 10.1166/jnn.2011.3216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We developed a simple and efficient method to load Pt nanoparticles (NPs) uniformly on defects generated in multiwalled CNTs (MWCNTs) without using reduction agents or organic reagents. Defects on the surfaces of MWCNTs were artificially generated by microwave treatment at various exposure times. Nucleation of Pt NPs occurs on the defect sites spontaneously due to an innate electropotential difference. Because of the correlation between defects and Pt NPs, we were able to control the size of Pt NPs by changing defect size, quantity and distribution, which was confirmed by Raman spectroscopy and TEM. After microwave treatment for 3 min, more uniform and smaller Pt NPs were observed. Also, the defects via microwave treatment make adhesion of Pt NPs stronger, which can be helpful to improve the reliability for applications. Finally, the methanol oxidation behavior of MWCNTs with Pt NPs was examined by cyclic voltammetry (CV).
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Preparation and characterization of TiO2 coated Fe nanofibers for electromagnetic wave absorber. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2011; 11:763-767. [PMID: 21446541 DOI: 10.1166/jnn.2011.3240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Recently, electromagnetic interference (EMI) and electromagnetic compatibility (EMC) have become serious problems due to the growth of electronic device and next generation telecommunication. It is necessary to develop new electromagnetic wave absorbing material to overcome the limitation of electromagnetic wave shielding materials. The EMI attenuation is normally related to magnetic loss and dielectric loss. Therefore, magnetic material coating dielectric materials are required in this reason. In this study, TiO2 coated Fe nanofibers were prepared to improve their properties for electromagnetic wave absorption. Poly(vinylpyrrolidone) (PVP) and Iron (III) nitrate nonahydrate (Fe(NO3)3 x 9H2O) were used as starting materials for the synthesis of Fe oxide nanofibers. Fe oxide nanofibers were prepared by electrospinning in an electric field and heat treatment. TiO2 layer was coated on the surface of Fe oxide nanofibers using sol-gel process. After the reduction of TiO2 coated Fe oxide nanofibers, Fe nanofibers with a TiO2 coating layer of about 10 nm were successfully obtained. The morphology and structure of fibers were characterized by SEM, TEM, and XRD. In addition, the absorption properties of TiO2 coated Fe nanofibers were measured by network analyzer.
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Patterning of catalysts for the selective growth of carbon nanotubes using laser irradiation of nickel nitrate. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2011; 11:602-605. [PMID: 21446506 DOI: 10.1166/jnn.2011.3226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We developed a simple method to produce patterned catalysts for the growth of carbon nanotubes (CNTs) on Si substrate using laser irradiation of Ni nitrate. We found that Ni nitrate can easily be decomposed into Ni oxide by KrF laser irradiation and that unexposed Ni nitrate can be removed using deionized (DI) water. Once we obtained patterned Ni oxide, we were able to synthesize multi-walled CNTs using a conventional thermal CVD. This new method does not require any photoresist or vacuum processes. Not only is the method compatible with low-temperature and large-area fabrication, it also significantly reduces the total processing steps required for conventional lithographic patterning technology. A detailed investigation of the decomposition process of this patterned catalyst and the microstructure of the patterned multi-walled CNTs was carried out using IR, SEM and TEM.
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Morphology controlled 1D Pt nanostructures synthesized by galvanic displacement of Cu nanowires in chloroplatinic acid. Electrochim Acta 2010. [DOI: 10.1016/j.electacta.2010.02.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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36
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Synthesis and electrical property of indium tin oxide nanofibers using electrospinning method. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2007; 7:3910-3913. [PMID: 18047086 DOI: 10.1166/jnn.2007.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this study indium tin oxide (ITO) nanofibers were synthesized using an electrospinning method. The morphological properties of the ITO nanofibers were considered and their specific resistances were measured to determine their applicability as filler for a transparent conducting film. ITO/PVP composite nanofibers were successfully obtained by electrospinning using a precursor solution containing indium nitrate, tin chloride, and poly(vinlypyrrolidone). After the heat treatment of ITO/PVP composite nanofibers at 600 degrees C and 1000 degrees C, ITO nanofibers with an average diameter of about 168 nm and 165 nm were synthesized, respectively.
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Development of AFLP-derived STS markers for the selection of 5-methyltryptophan-resistant rice mutants. PLANT CELL REPORTS 2004; 23:71-80. [PMID: 15064855 DOI: 10.1007/s00299-004-0790-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2003] [Revised: 02/24/2004] [Accepted: 02/24/2004] [Indexed: 05/24/2023]
Abstract
To increase the specific free amino acid content in the japonica rice (Oryza sativa L.) cultivar Donganbyeo, mutant cell lines resistant to growth inhibition by 5-methyltryptophan (5MT) were selected from embryo-cultured callus irradiated with 50 Gy gamma-rays. Four 5MT-resistant homozygous M4 lines, MRI-40, MRI-116, MRII-8, and MRII-12, were obtained. The mean content of nine free essential amino acids were 70.1, 72.5, 31.7, and 35.4% greater than the original variety in these four mutant lines, respectively. For AFLP analysis, 8 EcoRI (+2) and 8 MseI (+3) primers used in 45 primer combinations generated a total of 3,684 bands with a mean of 82 bands, of which 361 (9.8%) were clearly polymorphic with the control cultivar, the four 5MT-resistant mutants, and five sensitive lines. The lines were grouped into three clusters through cluster analysis using unweighted pair grouping method of averages. The 36 polymorphic PCR products present only in the four homozygous 5MT-resistant lines were cloned and sequenced, and 10 of these sequenced products were converted into sequence tagged site (STS) markers. These STS primer sets were designated OSMR1-OSMR10. Six STS primer sets (OSMR1, OSMR2, OSMR3, OSMR4, OSMR5, and OSMR6) generated a single monomorphic PCR product identical in size to the original AFLP fragments. The broad applicability of these STS markers for the screening of 5MT resistance was evaluated with seven putative 5MT-resistant M2 plants (PM-1 to PM-7). Four STS markers (OSMR1, OSMR2, OSMR4, and OSMR5) out of six STS primer sets were revealed as polymorphic products between the control cultivar and the seven M2 plants. These markers can be utilized for the fine selection of 5MT resistance in rice, and this PCR-screening technique is less time-consuming, less labor-intensive, and more accurate and reliable than selection based solely on phenotypic evaluation involving soaking in 5MT solutions.
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Stage-dependent regulation of ovarian pituitary adenylate cyclase-activating polypeptide mRNA levels by GnRH in cultured rat granulosa cells. Endocrinology 2001; 142:3828-35. [PMID: 11517159 DOI: 10.1210/endo.142.9.8384] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The present study was designed to test whether GnRH regulates pituitary adenylate cyclase-activating polypeptide mRNA levels in a stage-dependent manner during follicle development in the rat ovary. The granulosa cells of preovulatory and immature follicles obtained from PMSG- and estrogen-treated rats, respectively, were cultured in serum-free conditions in the presence of various hormones. GnRH receptor mRNA expression was detected in both preovulatory and immature granulosa cells and was down-regulated by gonadotropins. Treatment of preovulatory granulosa cells with GnRH agonist stimulated pituitary adenylate cyclase-activating polypeptide mRNA levels in a dose-dependent manner. In situ hybridization analysis of cultured preovulatory follicles revealed that GnRH-induced pituitary adenylate cyclase- activating polypeptide signals were detected in granulosa cells, but not thecal cells. In immature granulosa cells, cotreatment with GnRH agonist suppressed FSH-stimulated pituitary adenylate cyclase-activating polypeptide mRNA levels in a dose-dependent manner, whereas treatment with GnRH alone had no effect. Furthermore, treatment with GnRH antagonist inhibited LH-induced pituitary adenylate cyclase-activating polypeptide gene expression in preovulatory granulosa cells, whereas it stimulated FSH-induced pituitary adenylate cyclase-activating polypeptide gene expression in immature granulosa cells. Interestingly, GnRH-stimulated pituitary adenylate cyclase-activating polypeptide mRNA levels in preovulatory granulosa cells was inhibited by arachidonyltri fluoromethyl ketone, an inhibitor of phospholipase A(2), but not by an inhibitor of protein kinase A or C. Lastly, treatment of preovulatory follicles with pituitary adenylate cyclase-activating polypeptide antagonist suppressed GnRH-stimulated progesterone production during 6--9 h of culture. Taken together, these results demonstrate the stage-dependent regulation of pituitary adenylate cyclase-activating polypeptide mRNA levels by GnRH, the stimulatory and inhibitory effect in granulosa cells of preovulatory and immature follicles, respectively.
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Phosphorylation of purified recombinant hepatitis B virus-X protein by mitogen-activated protein kinase and protein kinase C in vitro. J Virol Methods 2001; 95:1-10. [PMID: 11377708 DOI: 10.1016/s0166-0934(00)00282-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The recombinant human hepatitis B virus-X protein (rhHBx) has been expressed as inclusion bodies in Escherichia coli and purified. By sequential dialysis of urea, rhHBx was folded into the native structure, which was demonstrated by both the efficacy of its transcriptional activation of the adenovirus major late promoter, fluorescence and circular dichroism (CD) analysis. The increase in CD values at 220 nm and a corresponding blue shift of the intrinsic fluorescence emission confirmed the ability of HBx to refold in lower concentrations of urea to produce the active protein. After purification and renaturation, the rhHBx protein was found to be phosphorylated by protein kinase C (PKC) and mitogen-activated protein kinase (MAPK). In vivo phosphorylation of HBx was also demonstrated. Although PKC and MAPK enhance the HBx phosphorylation in vitro, neither protein kinase A nor caseine kinase II (CKII) phosphorylate HBx protein, though there are possible substrate residues of both kinases in HBx protein. Phosphoamino acid analysis of the total acid hydrolyzed HBx showed that serine residues can be phosphorylated by PKC or MAPK.
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The hepatitis B virus-X protein activates a phosphatidylinositol 3-kinase-dependent survival signaling cascade. J Biol Chem 2001; 276:16969-77. [PMID: 11278872 DOI: 10.1074/jbc.m011263200] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The hepatitis B virus-X (HBx) protein is known as a multifunctional protein that not only coactivates transcription of viral and cellular genes but coordinates the balance between proliferation and programmed cell death, by inducing or blocking apoptosis. In this study the role of the HBx protein in activation of phosphatidylinositol 3-kinase (PI3K) was investigated as a possible cause of anti-apoptosis in liver cells. HBx relieved serum deprivation-induced and pro-apoptic stimuli-induced apoptosis in Chang liver (CHL) cells. Treatment with 1-d-3-deoxy-3-fluoro-myo-inositol, an antagonist to PI3K, which blocks the formation of 3'-phosphorylated phosphatidyl inositol in CHL cells transformed by HBx (CHL-X) but not normal Chang liver (CHL) cells, showed a marked loss of viability with evidence of apoptosis. Similarly, treatment with wortmannin, an inhibitor of PI3K, stimulated apoptosis in HBx-transformed CHL cells but not in normal cells, confirming that HBx blocks apoptosis through the PI3K pathway. The serine 47 threonine kinase, Akt, one of the downstream effectors of PI3K-dependent survival signaling was 2-fold higher in HBx-transformed CHL (CHL-X) cells than CHL cells. Phosphorylation of Akt at serine 473 and Bad at serine 136 were induced by HBx, which were specifically blocked by wortmannin and dominant negative mutants of Akt and Bad, respectively. We also demonstrated that HBx inhibits caspase 3 activity and HBx down-regulation of caspase 3 activity was blocked by the PI3K inhibitor. Regions required for PI3K phosphorylation on the HBx protein overlap with the known transactivation domains. HBx blocks apoptosis induced by serum withdrawal in CHL cells in a p53-independent manner. The results indicate that, unlike other DNA tumor viruses that block apoptosis by inactivating p53, the hepatitis B virus achieves protection from apoptotic death through a HBx-PI3K-Akt-Bad pathway and by inactivating caspase 3 activity that is at least partially p53-independent in liver cells. Moreover, these data suggest that modulation of the PI3K activity may represent a potential therapeutic strategy to counteract the occurrence of apoptosis in human hepatocellular carcinoma.
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Hepatitis C virus core protein transactivates insulin-like growth factor II gene transcription through acting concurrently on Egr1 and Sp1 sites. Virology 2001; 283:167-77. [PMID: 11336542 DOI: 10.1006/viro.2001.0892] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The possibility that hepatitis C virus core gene product (HCV-core) acts as a transactivator in insulin-like growth factor II (IGF-II) gene transcription was tested. HCV-core protein increases endogenous IGF-II expression from promoter 4 (P4) of the IGF-II gene through two cis-acting elements: Sp1 and Egr1 binding sites. Sp1 and Egr1 both bind to IGF-II P4 and functionally cooperate in mediating the maximal activity of IGF-II P4. HCV-core protein induced the binding of Sp1 and Egr1 on its binding sites on IGF-II P4. In addition, Sp1 and Egr1 were stimulated to phosphorylate by HCV-core, and its DNA binding activity was up-regulated upon HCV-core transfection. Transfection with HCV-core in HepG2 cells stimulated the membrane translocation of protein kinase C (PKC) and the treatment of HCV-core transfected cells with calphostin C, a PKC inhibitor, blocked induction of Sp1 and Egr1 DNA binding activity, and eventually transcriptional transactivations of the IGF-II gene. Increasing the DNA binding activity of the phosphorylated form of Sp1 and Egr1 might be an important mechanism for regulating IGF-II gene expression and for promoting cell division during hepatic carcinogenesis. These results indicate that HCV-core functions as a positive regulator of IGF-II transcription through the PKC pathway and that Sp1 and Egr1 are direct targets of the transcriptional regulation of the IGF-II gene which plays an important role in hepatitis C virus pathogenesis during the formation of hepatocellular carcinoma (HCC).
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Activation of the IGF-II gene by HBV-X protein requires PKC and p44/p42 map kinase signalings. Biochem Biophys Res Commun 2001; 283:303-7. [PMID: 11327698 DOI: 10.1006/bbrc.2001.4767] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We have recently shown that HBx protein, one of the causative agents of hepatocellular carcinomas, regulates Sp1 mediated transcription of insulin-like growth factor II promoter 4 (Lee et al. (1998) Oncogene 16, 2367-2380). Here we show that PKC and p44/p42MAPK signalings are required for the HBx-induced Sp1-mediated IGF-II P4 transcriptional activity since (i) PKC activation by PMA or PKC expression vector increases Sp1 phosphorylation and P4 activity in HBx-transfected HepG2 cells; (ii) PKC inhibition by PKC inhibitor Gö6976 reduces Sp1 phosphorylation, P4 activity, and IGF-II mRNA in HBx-transfected HepG2 cells; and (iii) the inhibition of MEK activation by U0126 reduces Sp1 phosphorylation, P4 activity and IGF-II mRNA in HBx-transfected HepG2 cells. These results demonstrate that PKC and p44/p42 MAPK cascades are the essential signaling pathways in Sp1-mediated IGF-II gene activation by HBx.
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MESH Headings
- Carbazoles/pharmacology
- Carcinoma, Hepatocellular/etiology
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/metabolism
- Enzyme Inhibitors/pharmacology
- Gene Expression Regulation, Neoplastic/drug effects
- Hepatitis B Antigens/genetics
- Hepatitis B Antigens/toxicity
- Humans
- Indoles/pharmacology
- Insulin-Like Growth Factor II/genetics
- Liver Neoplasms/etiology
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/metabolism
- Phosphorylation
- Promoter Regions, Genetic
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Neoplasm/genetics
- RNA, Neoplasm/metabolism
- Signal Transduction
- Sp1 Transcription Factor/metabolism
- Trans-Activators/genetics
- Trans-Activators/toxicity
- Transcriptional Activation
- Transfection
- Tumor Cells, Cultured
- Viral Regulatory and Accessory Proteins
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Metal-assisted esterification: glutaric acid-iron(II) complexes in the gas phase. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2001; 15:484-488. [PMID: 11268132 DOI: 10.1002/rcm.254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Transition metal ions are routinely used to assist organic reactions; however, direct detection of the intermediates in such reactions is uncommon. Here, we demonstrate a transition metal ion-assisted reaction between glutaric acid (L) and methanol, using electrospray ionization mass spectrometry (ESI-MS). Esterification of glutaric acid does not occur in aqueous methanol solution under ESI conditions, but the FeII-bound acid cluster, [FeII L2 - H]+, adds methanol and dehydrates to give rise to an abundant product ion with a 14 Da increased mass. The occurrence of methyl esterification is supported by collision-induced dissociation and isotopic labeling data, which indicate that the sequence by which the product ion is generated is loss of water, followed by the addition of methanol. Electrospray ionization conditions, specifically the tube lens offset voltage, strongly affect the reaction efficiency, presumably through control of the dehydration process. Other transition metal ions, such as NiII, ZnII, CoII and CuII, also show distinctive metal-assisted reactions.
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Activation of the insulin-like growth factor II transcription by aflatoxin B1 induced p53 mutant 249 is caused by activation of transcription complexes; implications for a gain-of-function during the formation of hepatocellular carcinoma. Oncogene 2000; 19:3717-26. [PMID: 10949925 DOI: 10.1038/sj.onc.1203694] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Aflatoxin B1 (AFB1) induced mutation of the p53 gene at codon 249 (p53mt249) is critical during the formation of hepatocellular carcinoma (HCC) following hepatitis B virus (HBV) infection. p53mt249 markedly increases insulin-like growth factor II (IGF-II) transcription largely from promoter 4, accumulating the fetal form of IGF-II. Modulation of the transcription factor binding to IGF-II P4 by wild-type p53 and p53mt249 was identified. Wild-type p53 inhibited binding of transcription factors Sp1 and TBP on the P4 promoter, while p53mt249 enhanced the formation of transcriptional complexes through enhanced DNA-protein (Sp1 or TBP) and protein-protein (Sp1 and TBP) interactions. p53mt249 stimulates transcription factor Sp1 phosphorylation which might be a cause of increased transcription factor binding on the P4 promoter while wild-type p53 does not. Transfection of hepatocytes with p53mt249 impaired induction of apoptosis by the HBV-X protein and TNF-alpha. Therefore, the blocking of apoptosis through enhanced production of IGF-II should provide a favorable opportunity for the selection of transformed hepatocytes. These results explain the molecular basis for the genesis of HCC by p53mt249 which was found to be induced by a potent mutagen, AFB1.
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Hepatitis B virus-X protein upregulates the expression of p21waf1/cip1 and prolongs G1-->S transition via a p53-independent pathway in human hepatoma cells. Oncogene 2000; 19:3384-94. [PMID: 10918595 DOI: 10.1038/sj.onc.1203674] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Progression through the cell cycle is controlled by the induction of cyclins and activation of cognate cyclin-dependent kinases. The human hepatitis B virus-X (HBV-X) protein functions in gene expression alterations, in the sensitization of cells to apoptotic killing and deregulates cell growth arrest in certain cancer cell types. We have pursued the mechanism of growth arrest in Hep3B cells, a p53-mutant human hepatocellular carcinoma (HCC) cell line. In stable or transient HBV-X transformed Hep3B cells, HBV-X increased protein and mRNA levels of the cyclin-dependent kinase inhibitor (CDKI) p21(waf1/cip1) increased binding of p21(waf1/cip1) with cyclin-dependent kinase 2 (CDK2), markedly inhibited cyclin E and CDK2 associated phosphorylation of histone H1 and induced the activation of a p21 promoter reporter construct. By using p21 promoter deletion constructs, the HBV-X responsive element was mapped to a region between -1185 and -1482, relative to the transcription start site. Promoter mutation analysis indicated that the HBV-X responsive site coincides with the ets factor binding sites. These data indicate that in human hepatocellular carcinoma cells, HBV-X can circumvent the loss of p53 functions and induces critical downstream regulatory events leading to transcriptional activation of p21(waf1/cip1). As a consequence, there is an increased chance of acquisition of mutations which can enhance the genesis of hepatomas. Our results also emphasize the chemotherapeutic potential of p21(waf1/cip1) inhibitors, particularly in the HBV-X infected hepatoma which lacks functional p53.
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Mutations in the p53 tumor suppressor gene in tree shrew hepatocellular carcinoma associated with hepatitis B virus infection and intake of aflatoxin B1. Gene 2000; 251:73-80. [PMID: 10863098 DOI: 10.1016/s0378-1119(00)00183-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Infection with hepadnaviruses and exposure to aflatoxin B1 (AFB1) are considered to be major risk factors in the development of hepatocellular carcinoma (HCC) in humans. A high rate of p53 mutations at codon 249 has been reported in these tumors. The tree shrew (Tupaia belangeri chinensis) is a useful animal model for the development of HCC after human hepatitis B virus (HBV) infection or AFB1 treatment. Therefore, it was of particular interest to determine whether the p53 gene in tree shrew HCCs associated with HBV infection and/or with exposure to AFB1 is affected in the same manner as in human HCCs. We determined the tree shrew p53 wild-type nucleotide sequences by RT-PCR and automatic DNA-sequencing. Tree shrew wild-type p53 sequence showed 91.7 and 93.4% homologies with human p53 nucleotide and amino acids sequences, respectively, while it showed 77.2 and 73.7% homologies in mice. One HCC and normal liver tissue from AFB1 treated and one HCC from AFB1- and HBV-treated tree shrew showed no change in p53 sequences, while three HCCs from AFB1- and HBV-treated tree shrews showed point mutations in p53 sequences. One HCC showed point mutations at codon 275, which is on the DNA-binding domain of p53 gene, which might be a cause of gain-of-function during the development of HCC. As a result, our finding indicates that tree shrews exposed to AFB1 and/or HBV had neither codon 249 mutations nor significant levels of other mutations in the p53 gene, as is the case with humans.
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MESH Headings
- Aflatoxin B1/toxicity
- Amino Acid Sequence
- Animals
- Base Sequence
- Carcinoma, Hepatocellular/chemically induced
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/virology
- Cloning, Molecular
- DNA Mutational Analysis
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Disease Models, Animal
- Genes, Tumor Suppressor/genetics
- Hepatitis B/virology
- Hepatitis B virus
- Liver/metabolism
- Liver/pathology
- Liver Neoplasms/chemically induced
- Liver Neoplasms/genetics
- Liver Neoplasms/virology
- Molecular Sequence Data
- Mutation
- Point Mutation
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Tumor Suppressor Protein p53/genetics
- Tupaiidae/genetics
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Abstract
Transforming growth factor-beta1 (TGF-beta) inhibits cell-cycle progression of many types of cells by arresting them in G(1)/S phase through inhibition of the active cyclin-Cdk complexes that lead to inhibition of Rb phosphorylation. In gastric-cancer cells, SNU16, TGF-beta treatment induced enhanced expression of p21(WAF1/CIP1) (p21), which inhibited the kinase activity of cyclin-D- and cyclin-E-associated Cdks and blocked p130 phosphorylation. TGF-beta also enhanced the stability of p130, suggesting that hypophosphorylation of p130 and increased stability of p130 contribute to p130-mediated G(1) arrest in gastric-cancer cells. Our results demonstrate that p21 and p130 are major downstream targets of TGF-beta in gastric-cancer cells and that a p21-G(1) cyclin/Cdks-p130/E2F pathway mediates growth inhibition by TGF-beta in these cells.
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48
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Abstract
Cellular immediate early genes (IEG) such as c-fos were originally defined as rapid and transient inducible gene, but their products show a varying degree of basal expression in the brain of normal animals, suggesting that they also play a role in the transcriptional control under physiological conditions. In this study, we used an immunohistochemical method to investigate changes in the number of c-Fos-immunoreactive cells in the cerebral cortex and hippocampal formation of the aged rat. There was a remarkable decrease in the number of c-Fos-immunoreactive cells in the piriform and temporal cortex of aged rats compared with young adult rats. There was a slight decrease in the number of c-Fos-immunoreactive cells in the parietal cortex of aged rat. In the hippocampal complex, there were also decreases in the number of c-Fos-immunoreactive cells in aged rat; the degree of decrease was most prominent in the dentate gyrus. This report provides the first morphological evidence for decreased levels of basal c-Fos expression in some cerebral cortical areas and in the hippocampal complex of aged rats.
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Human interleukin 6 gene is activated by hepatitis B virus-X protein in human hepatoma cells. Clin Cancer Res 1998; 4:1711-7. [PMID: 9676846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Interleukin 6 (IL-6) is a pleiotropic cytokine that induces many biological activities, including some aspects of the immune reaction and inflammatory responses. In the liver, IL-6 regulates the synthesis of a broad spectrum of acute-phase proteins. IL-6 is also known to be a factor involved in the immunoregulatory perturbations in patients with chronic liver diseases (CLDs). Here, we report that IL-6 can be induced by hepatitis B virus (HBV)-X protein, as evidenced by high levels of serum IL-6 in patients with CLD with HBV infection, IL-6 productions observed in HBV-X-transfected cells, and transcriptional transactivations of the IL-6 gene by HBV-X. We determined serum levels of IL-6 in patients with chronic hepatitis B (CH-B), chronic hepatitis C (CH-C), liver cirrhosis (LC) caused by hepatitis B, and LC with hepatocellular carcinoma (HCC) caused by hepatitis B (LC+HCC). Mean serum levels of IL-6 in all CLD patients were higher than those in normal controls, and the difference was statistically significant (P < 0.05). Mean IL-6 levels of LC and LC+HCC patients were significantly higher than those of CH-B patients (P < 0.05). Because the etiological factor in all cases except CH-C (CH-B, LC, and LC+HCC) was HBV, we checked the possibility of HBV-transactivator-X activation of IL-6 promoter. Using deletion constructs of 5'-flanking regulatory regions of the IL-6 gene linked to the chloramphenicol acetyltransferase gene as a reporter, we found that the binding of nuclear factor-kappaB to a cis element is essential and sufficient for the induction of the IL-6 gene by HBV-X. We also found that HBV-X enhances the binding of two subunits of nuclear factor-kappaB (p65 and p52) to their target DNA binding sequences. These observations are relevant, in that HBV-X might play an important role in hepatic inflammation and diseases by up-regulating IL-6 production, which can eventually lead to LC and HCC.
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The human hepatitis B virus transactivator X gene product regulates Sp1 mediated transcription of an insulin-like growth factor II promoter 4. Oncogene 1998; 16:2367-80. [PMID: 9620554 DOI: 10.1038/sj.onc.1201760] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Human hepatitis B virus (HBV) is one of the causative agents of hepatocellular carcinoma (HCC). The virus encodes a 17 kDa protein, X, which is known to be a causative agent in the formation of HCC. An insulin-like growth factor-II (IGF-II) is expressed during the formation of HCC. Among the four promoters of the IGF-II gene, promoters 2, 3 and 4 become activated during the formation of HCC. The high frequency of detection of hepatitis B virus X (HBV-X) antigen in liver cells from patients with chronic hepatitis, cirrhosis, and liver cancer suggested that the expressions of HBV-X and IGF-II are associated. Studies were carried out to test the relationship between the HBV-X gene product and the activation of IGF-II promoter 4. We demonstrated that the HBV-X protein increases the endogenous IGF-II expression from promoter 3 and 4 of IGF-II gene. Analysis of the fourth promoter of IGF-II gene showed that the HBV-X gene product positively regulates transcription. Two copies of a motif are responsible for conferring HBV-X regulation on the fourth promoter of IGF-II. These motifs have been identified as Sp1 binding sites. Sp1 binding to IGF-II P4 promoter was identified by gel mobility shift assay using purified Sp1. By using a GAL4-Sp1 fusion protein it was demonstrated that HBV-X positively regulates the Spl mediated transcriptional activity of IGF-II in vivo. A protein-affinity chromatography experiment showed that HBV-X protein does not bind directly to Sp1, but HBV-X does augment the DNA binding activity of the phosphorylated form of Sp1 in HepG2 cells. Sp1 was phosphorylated by HBV-X and its DNA-binding activity was up-regulated upon HBV-X transfections. Various HBV-X mutant expression vectors were used for the demonstration of specific interactions between Sp1 and HBV-X. These results indicate that HBV-X functions as a positive regulator of transcription, and that Sp1 is a direct target for the transcriptional regulation of IGF-II. Increasing the DNA binding ability of the phosphorylated form of Sp1 by HBV-X might be an important mechanism for regulating the IGF-II gene expression and possibly promoting cell division during hepatic carcinogenesis. Our experimental results suggest that expression of HBV-X might induce the expression of IGF-II and the IGF-II might play a role in hepatitis B virus pathogenesis during the formation of HCC.
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