共查询到20条相似文献，搜索用时 140 毫秒
1.
2.
3.
1999年,日本科学家Koji ma等人从小鼠的胃中提纯并鉴定了促生长激素分泌受体的特定的内源性配体,即生长素(Ghrelin)。它是一种含有28个氨基酸残基的多肽,主要由胃黏膜的一种内分泌细胞分泌,也分布于其他许多组织中,如垂体、下丘脑和胰腺等〔1〕。Ghrelin与其特异性受体结合后,会产生一系列生物学效应,如刺激垂体前叶释放生长激素,调节心血管功能,通过激活下丘脑弓状核细胞的NPY/AGRP神经元来调节采食,还参与体重和能量平衡的调节〔2,3〕。Ghrelin影响生殖系统功能并参与胃肠道生长和功能发育的调节,可以促进胃酸分泌和胃肠运动〔4,5〕… 相似文献
4.
5.
Ghrelin研究进展 总被引：10，自引：2，他引：10
Ghrelin是1999年发现的28肽,为生长激素促分泌素受体天然的内源性配体。由下丘脑、垂体和多种组织产生,其受体(GHS-R1a和GHS-R1b)在体内广泛分布。具有调节生长激素分泌、摄食、能量代谢、神经内分泌、记忆、睡眠、胃肠功能等多种生物学作用。 相似文献
6.
一种新的脑肠肽激素--Ghrelin 总被引：2，自引：0，他引：2
Ghrelin是1999年由日本科学家KoiiIna最先在小鼠和人胃内分泌细胞中发现的含有28个氨基酸的脑肠肽。GhreKn主要由胃分泌，下丘脑、肾脏、胎盘等也有分泌。GhrelinmRNA的表达部位十分广泛，细胞密集分布于胃部泌酸腺的颈部至底部。最近又在人的下丘脑和脑干发现Ghrelin的特异性受体——促生长激素分泌受体。具有刺激生长激素释放、调节机体生长发育、增加食欲、调节能量平衡的作用，同时有促进胃酸的分泌功能，并且与机体肥胖和癌症有关。 相似文献
7.
8.
Ghrelin及其生物学功能 总被引：1，自引：0，他引：1
Ghrelin是1999年发现的一种含有28个氨基酸残基的内分泌激素,主要由胃黏膜的一种内分泌细胞分泌,也分布于其他许多组织中,如垂体、下丘脑和胰腺等,是一种脑肠肽。Ghrelin与其特异性受体结合后,会产生一系列生物学效应,如刺激垂体前叶释放生长激素,增加采食,维持能量平衡,保护胃黏膜,促进胃酸分泌和胃肠运动等。本文对Ghrelin的结构、分布及其生物学功能进行了简要综述,以期为今后的研究提供相关的基础资料。 相似文献
9.
Ghrelin生物学功能的研究进展 总被引：1，自引：0，他引：1
Ghrelin是一种在大鼠和人胃内新发现的生长激素促分泌素受体(GHS-R)的内源性配基,有28个氨基酸,起促生长激素释放作用。当Ghrelin与位于垂体和下丘脑的GHS-R结合后,产生一系列生物学效应。本文从生长激素释放、机体生长发育、食欲和采食量、能量代谢、胃酸分泌等方面综述了Ghrelin的生物学功能,并初步探讨其在畜牧业上的应用前景。 相似文献
10.
Ghrelin是一种主要由胃肠道分泌产生的28个氨基酸组成的多肽,具有促进生长激素释放、促进摄食、参与能量代谢平衡等多种生理作用,近年来研究表明Ghrelin也参与动物生殖的调控。Ghrelin及其受体在下丘脑-垂体-性腺轴都有分布,体内外试验表明,Ghrelin在下丘脑、垂体和卵巢(睾丸)水平上对生殖具不同调节作用。基于此,论文就Ghrelin对动物生殖调控的研究进展做一综述。 相似文献
11.
12.
13.
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
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.
16.
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
17.
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
18.
19.
20.
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