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951.
Polyhedral oligomeric silsesquioxane (POSS) suppresses enzymatic degradation of PCL-based polyurethanes 总被引:1,自引:0,他引:1
In this Article, we studied the enzymatic hydrolytic biodegradation behavior of a novel multiblock thermoplastic polyurethane (TPU) system, which incorporates polyhedral oligomeric silsesquioxane (POSS) into linear biodegradable thermoplastic polyurethanes containing poly(ε-caproactone) (PCL) and polyethylene glycol (PEG) blocks. The biodegradation behavior of POSS-PCL-PEG TPUs was characterized by proton nuclear magnetic resonance spectroscopy ((1)H NMR), differential scanning calorimetry (DSC), tensile tests, scanning electron microscopy (SEM), and wavelength dispersive X-ray spectrometry (WDS) after enduring 22-day accelerated enzymatic hydrolytic degradation tests. POSS incorporation significantly suppressed in vitro enzymatic hydrolytic degradation of PCL-PEG-based multiblock TPUs by a surface passivation mechanism. WDS observations revealed that the covalently bonded POSS moieties developed a near-continuous and robust POSS-layer after initial degradation, which prevented ester bonds of PCL from enzymatic attack, thereby inhibiting further degradation. These striking results provide a new strategy to fabricate the polyester-based biostable thermoplastic polyurethanes (TPUs) of potential use in long-term surgical implants. 相似文献
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955.
Jun Li Jiahong Xu Junjie Xiao Hong Zhang Dandan Liang Yi Liu Yangyang Zhang Ying Liu Wei Wen Yaer Hu Zhuo Yu Biao Yan Bing Jiang Zhao‐Nian Zhou Yi‐Han Chen 《Journal of cellular and molecular medicine》2011,15(1):134-140
Abnormal activation of mitochondrial translocator protein (TSPO) contributes to arrhythmogenesis during cardiac metabolic compromise; however, its role in the antiarrhythmic activities of chronic hypoxia adaptation remains unclear. Our results demonstrated that 80% of normoxic rats developed ischaemic VF, whereas this condition was seldom observed in rats with 14 days of chronic intermittent hypobaric hypoxia (CIHH). TSPO stimulation or inhibition affected the arrhythmias incidence in normoxic rats, but did not change the CIHH‐mediated antiarrhythmic effects. Abrupt and excessive elevation of TSPO activity was positively linked to ischaemic VF, and CIHH preserved TSPO activity during ischaemia. The preservation of TSPO activity by CIHH also contributed to the maintenance of intracellular Ca homeostasis. These results suggest that the blunt sensitivity of TSPO to ischaemic stress may be responsible for the antiarrhythmic effects by CIHH. 相似文献
956.
Junjie Xiao Huaming Cao Dandan Liang Ying Liu Hong Zhang Hong Zhao Yi Liu Jun Li Biao Yan Luying Peng Zhaonian Zhou Yi‐Han Chen 《Journal of cellular and molecular medicine》2011,15(5):1166-1176
Microtubule integrity is important in cardio‐protection, and microtubule disruption has been implicated in the response to ischemia in cardiac myocytes. However, the effects of Taxol, a common microtubule stabilizer, are still unknown in ischemic ventricular arrhythmias. The arrhythmia model was established in isolated rat hearts by regional ischemia, and myocardial infarction model by ischemia/reperfusion. Microtubule structure was immunohistochemically measured. The potential mechanisms were studied by measuring reactive oxygen species (ROS), activities of oxidative enzymes, intracellular calcium concentration ([Ca2+]i) and Ca2+ transients by using fluorometric determination, spectrophotometric assays and Fura‐2‐AM and Fluo‐3‐AM, respectively. The expression and activity of sarcoplasmic reticulum Ca2+‐ATPase (SERCA2a) was also examined using real‐time polymerase chain reaction, Western blot and pyruvate/Nicotinamide adenine dinucleotide‐coupled reaction. Our data showed that Taxol (0.1, 0.3 and 1 μM) effectively reduced the number of ventricular premature beats and the incidence and duration of ventricular tachycardia. The infarct size was also significantly reduced by Taxol (1 μM). At the same time, Taxol preserved the microtubule structure, increased the activity of mitochondrial electron transport chain complexes I and III, reduced ROS levels, decreased the rise in [Ca2+]i and preserved the amplitude and decay times of Ca2+ transients during ischemia. In addition, SERCA2a activity was preserved by Taxol during ischemia. In summary, Taxol prevents ischemic ventricular arrhythmias likely through ameliorating abnormal calcium homeostasis and decreasing the level of ROS. This study presents evidence that Taxol may be a potential novel therapy for ischemic ventricular arrhythmias. 相似文献
957.
Two new sorbicillinoids, 1 and 2 , together with a novel benzofuranone derivative named phialofurone ( 3 ), were isolated from a deep‐sea sediment‐derived fungus, Phialocephala sp. Their structures were established on the basis of spectroscopic data. All compounds displayed cytotoxic effects against P388 (IC50 values of 11.5±1.4, 0.1±0.1, and 0.2±0.01 μM , resp.) and K562 (IC50 values of 22.9±0.8, 4.8±0.3 and 22.4±0.9 μM , resp.) cell lines. 相似文献
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959.
Junyong Zhang Yonghui Deng Dong Gu Shutao Wang Lan She Renchao Che Zhong‐Sheng Wang Bo Tu Songhai Xie Dongyuan Zhao 《Liver Transplantation》2011,1(2):241-248
A novel ligand‐assisted assembly approach is demonstrated for the synthesis of thermally stable and large‐pore ordered mesoporous titanium dioxide with a highly crystalline framework by using diblock copolymer poly(ethylene oxide)‐b‐polystyrene (PEO‐b‐PS) as a template and titanium isopropoxide (TIPO) as a precursor. Small‐angle X‐ray scattering, X‐ray diffraction (XRD), transmission electron microscopy (TEM), high‐resolution scanning electron microscopy, and N2‐sorption measurements indicate that the obtained TiO2 materials possess an ordered primary cubic mesostructure with large, uniform pore diameters of about 16.0 nm, and high Brunauer–Emmett–Teller surface areas of ~112 m2 g?1, as well as high thermal stability (~700 °C). High resolution TEM and wide‐angle XRD measurements clearly illustrate the high crystallinity of the mesoporous titania with an anatase structure in the pore walls. It is worth mentioning that, in this process, in addition to tetrahydrofuran as a solvent, acetylacetone was employed as a coordination agent to avoid rapid hydrolysis of the titanium precursor. Additionally, stepped evaporation and heating processes were adopted to control the condensation rate and facilitate the assembly of the ordered mesostructure, and ensure the formation of fully polycrystalline anatase titania frameworks without collapse of the mesostructure. By employing the obtained mesoporous and crystallized TiO2 as the photoanode in a dye‐sensitized solar cell, a high power‐conversion efficiency (5.45%) can be achieved in combination with the N719 dye, which shows that this mesoprous titania is a great potential candidate as a catalyst support for photonic‐conversion applications. 相似文献
960.
Despite its potent antitumor effect, clinical use of Doxorubicin is limited because of serious side effects including myocardial
toxicity. Understanding the cellular mechanism involved in this process in a better manner is beneficial for optimizing Doxorubicin
treatment. In the current study, the authors focus on the AMP-activated protein kinase (AMPK) in the said process. In this
study, the authors discovered for the first time that Doxorubicin induces AMPK activation in cultured rat embryonic ventricular
myocardial H9c2 cells. Reactive oxygen species (ROS)-dependent LKB1 activation serves as the upstream signal for AMPK activation
by Doxorubicin. Evidence in support of the activation of AMPK contributing to Doxorubicin-induced H9c2 cell death/apoptosis—probably
by modulating multiple downstream signal targets, including regulating JNK, p53, and inhibiting mTORC1—is provided in this
article. 相似文献