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排序方式: 共有871条查询结果,搜索用时 15 毫秒
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2.
Simultaneous HPLC quantification of total cholesterol,tocopherols and β-carotene in Barrosã-PDO veal 总被引:1,自引:0,他引:1
José A. Mestre Prates Mário A. Gonçalves Quaresma Rui J. Branquinho Bessa Carlos M.G. Andrade Fontes Cristina M.P. Mateus Alfaia 《Food chemistry》2006
A simple, rapid and sensitive procedure for the simultaneous determination of total cholesterol, tocopherols and β-carotene in meat is described. The method involves a direct saponification of the meat, a single n-hexane extraction and the analysis of the extracted compounds by normal-phase HPLC, using fluorescence (tocopherols) and UV–Vis photodiode array (cholesterol and β-carotene) detections in tandem. Rates of recovery of spiked meat samples were 93% for cholesterol, 83–86% for (α-, β- and -γ) tocopherols and 89% for β-carotene. Repeatabilities were high (CV < 6%) for all determined compounds, except for δ-tocopherol. This tocopherol, which is not usually present in meat, showed a much lower recovery percentage (73%) and repeatability (12.8%). This methodology was applied for the quantification of total cholesterol, tocopherols and β-carotene in three muscles (longissimus thoracis, longissimus lumborum and semitendinosus) of the Portuguese traditional Barrosã-PDO veal, obtained from autochthonous calves fed extensively during summer (with the least abundant green pastures) and slaughtered in early autumn (October). Barrosã-PDO veal showed median contents of total cholesterol (0.50–0.56 mg/g) and, depending on the analysed muscle, moderate to high contents of α-tocopherol (3.3–3.9 μg/g) and β-carotene (0.07–0.09 μg/g), suggesting an high sensorial and hygienic quality. 相似文献
3.
Wei-Chieh Huang Kao-Chang Lin Chih-Wei Hsia Chih-Hsuan Hsia Ting-Yu Chen Periyakali Saravana Bhavan Joen-Rong Sheu Shaw-Min Hou 《International journal of molecular sciences》2021,22(7)
Platelets play a crucial role in the physiology of primary hemostasis and pathological processes such as arterial thrombosis; thus, developing a therapeutic target that prevents platelet activation can reduce arterial thrombosis. Pterostilbene (PTE) has remarkable pharmacological activities, including anticancer and neuroprotection. Few studies have reported the effects of pterostilbene on platelet activation. Thus, we examined the inhibitory mechanisms of pterostilbene in human platelets and its role in vascular thrombosis prevention in mice. At low concentrations (2–8 μM), pterostilbene strongly inhibited collagen-induced platelet aggregation. Furthermore, pterostilbene markedly diminished Lyn, Fyn, and Syk phosphorylation and hydroxyl radical formation stimulated by collagen. Moreover, PTE directly hindered integrin αIIbβ3 activation through interfering with PAC-1 binding stimulated by collagen. In addition, pterostilbene affected integrin αIIbβ3-mediated outside-in signaling, such as integrin β3, Src, and FAK phosphorylation, and reduced the number of adherent platelets and the single platelet spreading area on immobilized fibrinogen as well as thrombin-stimulated fibrin clot retraction. Furthermore, pterostilbene substantially prolonged the occlusion time of thrombotic platelet plug formation in mice. This study demonstrated that pterostilbene exhibits a strong activity against platelet activation through the inhibition of integrin αIIbβ3-mediated inside-out and outside-in signaling, suggesting that pterostilbene can serve as a therapeutic agent for thromboembolic disorders. 相似文献
4.
Danique L. van den Kerkhof Paola E.J. van der Meijden Tilman M. Hackeng Ingrid Dijkgraaf 《International journal of molecular sciences》2021,22(7)
The integrin αIIbβ3 is the most abundant integrin on platelets. Upon platelet activation, the integrin changes its conformation (inside-out signalling) and outside-in signalling takes place leading to platelet spreading, platelet aggregation and thrombus formation. Bloodsucking parasites such as mosquitoes, leeches and ticks express anticoagulant and antiplatelet proteins, which represent major sources of lead compounds for the development of useful therapeutic agents for the treatment of haemostatic disorders or cardiovascular diseases. In addition to hematophagous parasites, snakes also possess anticoagulant and antiplatelet proteins in their salivary glands. Two snake venom proteins have been developed into two antiplatelet drugs that are currently used in the clinic. The group of proteins discussed in this review are disintegrins, low molecular weight integrin-binding cysteine-rich proteins, found in snakes, ticks, leeches, worms and horseflies. Finally, we highlight various oral antagonists, which have been tested in clinical trials but were discontinued due to an increase in mortality. No new αIIbβ3 inhibitors are developed since the approval of current platelet antagonists, and structure-function analysis of exogenous disintegrins could help find platelet antagonists with fewer adverse side effects. 相似文献
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Tomoo Yamamura Yoshinobu ShiokawaHajimu Yamana Hirotake Moriyama 《Electrochimica acta》2002,48(1):43-50
The redox flow battery using uranium as the negative and the positive active materials in polar aprotic solvents was proposed. In order to establish the guiding principle for the uranium compounds as the active materials, the investigation of uranium β-diketonate complexes was conducted on (i) the solubility of active materials, (ii) the electrode reaction of U(VI) and U(IV) β-diketonate complexes and (iii) the estimation of the open circuit voltage of the battery. The solubilities of higher than 0.8 mol dm−3 of U(VI) complexes and higher than 0.4 mol dm−3 of a U(IV) complex were obtained in the solvents. The electrode reactions of U(pta)4, UO2(dpm)2, UO2(fod)2 and UO2(pta)2 were first studied and the redox potentials of uranium β-diketonates were thermodynamically discussed. The open circuit voltage is estimated more than 1 V by using Hacac or Hdpm. The larger open circuit voltage is expected when a ligand with the larger basicity is used. 相似文献
7.
A notable amount of PP β-crystal (30%, by X-ray diffraction pattern) has been found in the PP samples as polymerized at normal static isothermal crystallization conditions without using any extra nucleating agents. Existence of catalyst residues in the sample is decisive, which slows down the crystallization rate facilitating the formation of β-form spherulites. Comparatively, high molecular weight PP favors the formation of β-form spherulites, deducting from no β-crystal detected in the degraded samples. Finally, high isotacticity is also required for obtaining qualitative β-form spherulites, demonstrated by increased β-crystal content after removal of weak crystalline fraction of the sample. 相似文献
8.
A simple solid state technique for electrochemical micromachining of metal substrates using a metal ion conductor (Na-β″-Al2O3) was proposed. The fundamental solid electrochemical cell consists of a (anode) metal substrate (M = Ag, Cu, Zn, and Pb)/pyramidal Na-β″-Al2O3/Ag (cathode) system, where the contact diameter between M/Na-β″-Al2O3 was extremely small, on the order of a few micrometer. Under an applied electric field, the metal substrate was electrochemically oxidized to metal ions (Mn+) at the M/Na-β″-Al2O3 microcontact. These Mn+ ions migrated into the Na-β″-Al2O3. As a result of continuous electrolysis, the metal substrate was locally consumed at the microcontact, and thus solid state electrochemical micromachining was accomplished. As expected, the machining size or depth depended on the electrolysis conditions (current, operating time) and the apex configuration of pyramidal Na-β″-Al2O3. Moreover, the scanning of the Na-β″-Al2O3 pyramid during electrolysis produced a fine patterned metal substrate. In the present paper, solid state electrochemical micromachining was performed for several metal substrates, and its advantages and disadvantages vis-a-vis the conventional electrochemical micromachining method are discussed in detail. 相似文献
9.
以环氧氯丙烷(EPI)为交联剂,在碱性介质中合成了β-环糊精(-βCD)水溶性交联聚合物,并以其为基体,以硝酸铈铵(CAN)为引发剂,在弱酸性条件下,合成出了新型的水溶性交联-βCD接枝聚丙烯酰胺(PAM)的共聚物絮凝剂(WCDP).对产物的红外光谱分析(FTIR)表明WCDP的合成是成功的.研究了WCDP的制备条件(交联剂用量、引发剂用量、温度、时间等)对吸附有机污染物和除浊性能的影响,结果表明:在最佳合成条件下,WCDP能同时去除水中的浊度和小分子有机污染物,并能形成絮体从水中分离.以高岭土和对硝基苯酚(p-NP)为研究对象,WCDP对浊度和p-NP的去除率分别为96.7%和60.6%. 相似文献
10.
谢荣源 《江苏工业学院学报》2014,(3):56-63
综述了阿尔茨海默病的药物治疗研究进展,包括乙酰胆碱酯酶抑制剂,NMDA受体拮抗剂,非甾体类抗炎药,抗氧化剂,免疫治疗以及针对Aβ的其它治疗手段等. 相似文献