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41.
Sung Wook Kang Ok Kyun Kim Bochan Seo Sung Ho Lee Fu Shi Quan Jae Ho Shin Gi-Ja Lee Hun-Kuk Park 《Analytica chimica acta》2013
In this study, we simultaneously measured nitric oxide (NO) and oxygen (O2) dynamics in the myocardium during myocardial ischemia-reperfusion (IR) utilizing sol-gel modified electrochemical NO and O2 microsensors. In addition, we attempted to clarify the correlation between NO release in the ischemic period and O2 restoration in the myocardium after reperfusion, comparing a control heart with a remote ischemic preconditioning (RIPC)-treated heart as an attractive strategy for myocardial protection. Rat hearts were randomly divided into two groups: a control group (n = 5) and an RIPC group (n = 5, with RIPC treatment). Myocardia that underwent RIPC treatment (182 ± 70 nM, p < 0.05) released more NO during the ischemic period than those of the control group (63 ± 41 nM). The restoration value of oxygen tension (pO2) in the RIPC group significantly increased and was restored to pre-ischemic levels (92.6 ± 36.8%); however, the pO2 of the control group did not increase throughout the reperfusion period (5.7 ± 7.5%, p = 0.001). Myocardial infarct size measurements revealed a significant decrease in cell death in the myocardium region of the RIPC group (41.44 ± 6.42%, p = 0.001) compared with the control group (60.05 ± 10.91%). As a result, we showed that the cardioprotective effect of RIPC could be attributed to endogenous NO production during the ischemic period, which subsequently promoted reoxygenation in post-ischemic myocardia during early reperfusion. Our results suggest that the promotion of endogenous formation during an ischemic episode might be helpful as a therapeutic strategy for protecting the myocardium from IR injury. Additionally, our NO and O2 perm-selective microsensors could be utilized to evaluate the effect of drug or treatment. 相似文献
42.
Samarium(II) iodide promoted reductive deacetoxylation of 7-aminocephalosporanic acid derivatives to synthesize 3-alkylidenecepham-4-carboxylates, which could be valuable intermediates for the synthesis of new cephalosporin antibiotics, was investigated. 相似文献
43.
A novel alignment method for control of high pretilt angle in nematic liquid crystals (NLC), using a solvent dipping effect on various alignment layers, was successfully investigated. The pretilt angle of a NLC is increased by dipping before rubbing treatment on three kinds of rubbed polyimide (PI) surfaces. The pretilt generated by the dipping after rubbing a PI surface with a short side chain is high compared with a PI surface with a long side chain. The pretilt generated by dipping before rubbing homeotropic layer of a positive type NLC (δε > 0) is lower than that of the negative type NLC (δε < 0). The generated NLC pretilt angle is attributed to the perpendicular component of the permittivity epsilon of the NLC. 相似文献
44.
A new photoalignment material, copoly(4-methacryloyloxychalcone-cholesteryl methacrylate) (copoly(M4Ch-ChMA)), was synthesized and the electro-optical characteristics for the photoaligned vertically aligned (VA) liquid crystal display (LCD) were studied. Excellent voltagetransmittance characteristics were achieved for the photoaligned VA-LCD with 1 min polarized UV exposure at an oblique direction of 30° on the copoly(M4Ch-ChMA) surfaces. The response time of the VA-LCD was about 39 ms, and increased with increasing UV exposure time. We suggest that the proportion of photodimerized chalcone group increased with increasing UV exposure time, contributing to a higher response time. 相似文献
45.
All possible optically active regioisomers of myo‐inositol mono‐ and bisphosphates were synthesized using inositol derivatives suitably protected with various protecting groups (IRns) as key intermediates. A series of procedures including Novozym 435 catalyzed enzymatic resolution of (3aR,4S,7S,7aR)‐rel‐3a,4,7,7a‐tetrahydro‐2,2‐dimethyl‐1,3‐benzodioxole‐4,7‐diol diacetate, several protection and deprotection reactions, and acyl migration afforded two enantiomeric pairs of IR5 and six enantiomeric pairs of IR4. Phosphorylation of these key intermediates by the phosphitylation and oxidation procedure gave the target products after removal of the protecting groups. 相似文献
46.
Hyun Ook Seo Dae Han Kim Kwang-Dae Kim Eun Ji Park Chae Won Sim Young Dok Kim 《Adsorption》2013,19(6):1181-1187
Adsorption and desorption of toluene on bare and TiO2-coated silica with a mean pore size of 15 nm under dry and humid conditions were studied using toluene breakthrough curves and temperature programmed desorption (TPD) of toluene and CO2. Two TiO2/silica samples (either partially or fully covered with TiO2) were prepared with 50 and 200 cycles of TiO2 atomic layer deposition (ALD), respectively. The capacity of silica to adsorb toluene improved significantly with TiO2-thin film coating under dry conditions. However, toluene desorption from the surface due to displacement by water was more pronounced for TiO2-coated samples than bare samples under humid conditions. In TPD experiments, silica with a thinner TiO2 film (50-ALD cycled) had the highest reactivity for toluene oxidation to CO2 both in the absence and presence of water. Toluene adsorption and oxidation reactivity of silica can be controlled by modifying the silica surface with small amount of TiO2 using ALD. 相似文献
47.
We synthesized a fluorescent adenosine derivative, rApy, as a probe to study RNA structural transitions, in particular the intermolecular G-quadruplex formation. rApy was incorporated into the dangling positions of guanine-rich oligonucleotides, which under physiological conditions undergo π-stacking on top of each other exhibiting a strong emission signal in their G-quadruplex conformation, but not in their single-stranded state. 相似文献
48.
Electrophoresis 2014, 35, 1504–1508. DOI: 10.1002/elps.201400001 Combination of DNA biobarcode assay with micro‐capillary electrophoretic analysis on a chip allows us to perform breast and colorectal cancer cell detection with high sensitivity, multiplexity, and accuracy.
49.
Eui-Baek Byun Ha-Yeon Song Woo Sik Kim Jeong Moo Han Ho Seong Seo Woo Yong Park Kwangwook Kim Eui-Hong Byun 《Molecules (Basel, Switzerland)》2021,26(6)
Although our previous study revealed that gamma-irradiated chrysin enhanced anti-inflammatory activity compared to intact chrysin, it remains unclear whether the chrysin derivative, CM1, produced by gamma irradiation, negatively regulates toll-like receptor (TLR) signaling. In this study, we investigated the molecular basis for the downregulation of TLR4 signal transduction by CM1 in macrophages. We initially determined the appropriate concentration of CM1 and found no cellular toxicity below 2 μg/mL. Upon stimulation with lipopolysaccharide (LPS), CM1 modulated LPS-stimulated inflammatory action by suppressing the release of proinflammatory mediators (cytokines TNF-α and IL-6) and nitric oxide (NO) and downregulated the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways. Furthermore, CM1 markedly elevated the expression of the TLR negative regulator toll-interacting protein (Tollip) in dose- and time-dependent manners. LPS-induced expression of cell surface molecules (CD80, CD86, and MHC class I/II), proinflammatory cytokines (TNF-α and IL-6), COX-2, and iNOS-mediated NO were inhibited by CM1; these effects were prevented by the knockdown of Tollip expression. Additionally, CM1 did not affect the downregulation of LPS-induced expression of MAPKs and NF-κB signaling in Tollip-downregulated cells. These findings provide insight into effective therapeutic intervention of inflammatory disease by increasing the understanding of the negative regulation of TLR signaling induced by CM1. 相似文献
50.
Ki Cheol Hwang Hyun Young Shin Woo Jung Kim Mi Suk Seo Hoon Kim 《Molecules (Basel, Switzerland)》2021,26(6)
Persimmon (Diospyros kaki), a familiar and widespread fruit worldwide, is known to exhibit several physiological effects because of the presence of pharmacologically active compounds called phytochemicals. However, its high-molecular-weight compounds, particularly polysaccharides, have not been extensively studied. In this study, D. kaki extract (DK) was fractionated into low- and high-molecular-weight fractions (DK-L and DK-H, respectively) through ethanol fractionation, and their effects on antioxidant, anti-inflammatory, and antiwrinkle activities were investigated by an in vitro system. DK-H contained significantly higher contents of neutral sugar, uronic acid, and polyphenols compared to DK and DK-L. Furthermore, DK-H exhibited significantly improved pharmacological activities, such as antioxidant, anti-inflammatory, and antiwrinkle properties, compared to those of DK and DK-L, demonstrating that DK-H may play an important role in mediating the beneficial effects of persimmon. Sugar composition analysis and molecular characterization indicated that DK-H consisted of a galacturonic acid (GalA)-rich polysaccharide with a molecular weight of >345 kDa that mainly comprised GalA and small amounts of neutral sugar and polyphenol residues. These results suggest that the bioactive fraction DK-H is likely to be a GalA-rich pectic polysaccharide containing a small number of polyphenol residues, which may be a novel candidate in the pharmaceutical and cosmeceutical industries. 相似文献