共查询到20条相似文献，搜索用时 62 毫秒
1.
2.
细胞色素P450(Cytochrome P450,CYP450)属于亚铁血红素单加氧酶超家族,参与生理过程中重要化合物的生物合成,包括类固醇、脂肪酸、类花生酸类物质、脂溶性维生素、胆汁酸等.同时CYP450也是最主要的代谢外源化合物的酶,例如,药物、环境毒物.其介导的外源化合物的代谢是肝脏解毒系统中重要的一部分.细胞色素P4502A5(cytochrome P4502A5,CYP2A5)是鼠类CYP450酶系中的重要成员,与人类CYP2a6同源,在蛋白质序列和底物特异性上,与CYP2a6、CYP2a13高度相似,并且有相同的代谢底物,包括香豆素、尼古丁、可替宁、睾丸素、烟草类致癌物及亚硝胺类等[1]. 相似文献
3.
黄曲霉毒素B1(aflatoxin B1,AFB1)作为黄曲霉主要的代谢产物之一,进入动物体内后主要影响动物的抗氧化系统和免疫系统,是霉菌毒素中主要的致病致癌物质。AFB1代谢主要存在于动物肝脏中,肝微粒体中的细胞色素酶P450(cytochrome P450,CYP450s)是动物体内参与多种药物及毒物代谢的主要酶类。细胞色素酶P3A4(cytochrome P3A4,CYP3A4)是CYP450s的同工酶,主要参与肝脏内AFB1的代谢。进入动物机体内的AFB1经CYP3A4代谢的产物一部分与DNA、RNA结合产生致毒效应;另一部分在谷胱甘肽过氧化物酶(GSH-Px)、谷胱甘肽硫转移酶(GST)等作用下进入血液和尿液,发生解毒效应。在饲料中添加抗氧化剂对于缓解AFB1的毒性有良好效果。饲料中添加一些天然物质或化学成分可以适当抑制肝脏内CYP3A4的活性,对于研究AFB1对机体的损伤具有重要意义,还可为开发新的饲料添加剂提供新思路。 相似文献
4.
5.
采用SD大鼠和C57小鼠研究阿司匹林丁香酚酯(AEE)对肝脏主要药物代谢酶活性的影响。首先把研磨的AEE混悬在0.5%羧甲基纤维素钠溶液中，配制成20 g/L的AEE混悬液。将SD大鼠随机分为2组，试验组每日灌喂1次AEE(54 mg/kg),空白对照组每日灌喂1次等量的0.5%羧甲基纤维素钠溶液。连续3周后随机处死一半，取其肝脏，制备肝匀浆液；剩余一半的SD大鼠，停药2周处死，取其肝脏，制备肝匀浆液。采用ELISA考察AEE对肝脏细胞色素P450酶(cytochrome P450,CYP450)的影响。研究AEE对C57小鼠肝脏主要药物代谢酶活性的影响，方法同SD大鼠方法。结果显示，SD大鼠连续灌药3周后，AEE对CYP3A4、CYP2C19、CYP1A2的活性有一定的抑制作用(P<0.05),对CYP2C8的活性有一定的诱导作用(P<0.05);CYP2D6、CYP2C9无显著性差异(P>0.05);停药2周后，发现只有CYP2C19的活性没有恢复，而其余药酶活性都有一定的恢复，与正常组无显著性差异(P>0.05)。C57小鼠连续灌药3周后，AEE对CYP3... 相似文献
6.
7.
细胞色素P450为一类蛋白质超家族,在许多化学物质的生物转化中起重要作用,如纯化的CYPs可用于结构的研究或测定药物的代谢途径。本研究中,猪肝微粒体细胞色素P450（CYP）经octylamino琼脂糖和羟基磷灰石柱层析,纯化出CYP1A和CYP2A19两种CYPs。经Western blotting鉴定,抗大鼠和人的CYP1A2抗体能识别猪cYP1A;抗人的CYP2A6抗体能识别CYP2A19。 相似文献
8.
采用cocktail探针药物法研究了氟尼辛葡甲铵对猪肝微粒体细胞色素（CY）P450酶系的作用.将12头猪随机分为2组,试验组每日肌肉注射氟尼辛葡甲铵1次,对照组给予等体积的生理盐水,连续给药10 d.通过高效液相色谱法检测探针药物的代谢率,评价各组CYP450酶的活性水平.结果显示,试验组的氨苯砜代谢减慢,消除半衰期t1/2延长;而氯唑沙宗代谢加快,t1/2缩短.说明氟尼辛葡甲铵对猪的CYP3A4具有抑制作用,而对CYP2E1存在诱导效应. 相似文献
9.
建立同时测定大鼠血浆中3种细胞色素P450（CYP450）亚型酶( CYP1A2、CYP2C9、CYP3A4)活性的Cocktail探针药物的高效液相色谱（HPLC）检测方法,为相关肝药酶代谢研究提供方法学参考。分别取非那西丁,咪达唑仑和甲苯磺丁脲三种探针药物,制成混合探针溶液,用一种提取溶剂系统对3种探针药物同时提取,并用高效液相色谱法（HPLC）同时测定该3种探针药物的血药浓度,并对其进行专属性,线性范围及检测限,精密度,回收率,稳定性的验证。色谱条件选用Diamonsil C18色谱柱（4.6 mm×250 mm,5 μm）;流动相为甲醇-50 mM磷酸盐缓冲对（45:55;pH3.2）;检测波长：230 nm;流速1.0 mL/min;柱温35 ℃。结果：非那西丁,咪达唑仑,甲苯磺丁脲的线性范围分别为0.10～10.0 μg/mL(r=0.9993),0.05～5.0 μg/mL(r=0.9999),0.10～50.0 μg/mL(r=0.9991);方法回收率分别为79.28 %～87.91 %,76.43 %～85.36 %,82.79 %～90.61 %。该HPLC检测方法快捷,准确,灵敏度高,可以在同一次试验中,同时测定大鼠血浆中3种CYP450亚酶探针药物（非那西丁,甲苯磺丁脲,咪达唑仑）的浓度,各探针药物的吸收峰分离完全,无干扰,可用于开展某些受试药物对大鼠CYP450的3个主要亚型酶（CYP1A2,CYP2C9,CYP3A4）调控作用的相关研究。 相似文献
10.
《中国畜牧兽医》2020,(4)
本研究通过建立人肝微粒体体外孵育试验,考察泰妙菌素对4种CYP450亚酶的探针底物睾酮、非那西丁、氯唑沙宗、氢溴酸右美沙芬代谢的影响,以反映泰妙菌素对人CYP3A4、CYP1A2、CYP2E1、CYP2D6酶活性的作用。试验分为3组:药物试验组、阳性对照组(不含NADPH)、阴性对照组(不含CYP450抑制剂),孵育体系为100μL,孵育试验在96孔板中进行。终止反应后使用高效液相色谱串联质谱仪(LC-MS/MS),以内标法检测96孔板中孵育液的剩余探针底物浓度。根据药物试验组与阴性对照组的探针药物代谢浓度之比,计算药物试验组的探针药物代谢率。使用Graphpad Prism 6.0软件,以药物试验组相对代谢率为纵坐标,药物浓度对数值为横坐标作图,计算试验组药物IC_(50)值。针对泰妙菌素与CYP3A4的孵育试验设置多个孵育时间点观察孵育时间对IC_(50)值的影响。试验结果显示,酮康唑对CYP3A4的IC_(50)值为0.044μmol/L,α-萘黄酮对CYP1A2的IC_(50)值为0.030μmol/L、4-甲基吡唑对CYP2E1的IC_(50)值为0.022μmol/L、奎尼丁对CYP2D6的IC_(50)值为0.096μmol/L。泰妙菌素对CYP1A2及CYP2D6的IC_(50)值均大于50μmol/L,对CYP2E1的IC_(50)值为0.045μmol/L,对CYP3A4的IC_(50)值为1.609μmol/L。延长泰妙菌素与CYP3A4的孵育时间(10～50 min)后,泰妙菌素对CYP3A4的IC_(50)值由1.609μmol/L增加至8.657μmol/L。本研究中4种亚酶常用抑制剂的IC_(50)值与参照值相近,表明所建立人肝微粒体体外孵育试验方法可靠。以IC_(50)值为指标显示泰妙菌素对CYP1A2和CYP2D6无抑制作用,对CYP2E1和CYP3A4存在强抑制作用,泰妙菌素可能是CYP3A4的可逆性抑制剂。 相似文献
11.
12.
魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
13.
14.
本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
15.
REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
16.
17.
18.
Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
19.
20.
以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。 相似文献