共查询到20条相似文献，搜索用时 93 毫秒
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D P McDonnell D J Mangelsdorf J W Pike M R Haussler B W O'Malley 《Science (New York, N.Y.)》1987,235(4793):1214-1217
Vitamin D3 receptors are intracellular proteins that mediate the nuclear action of the active metabolite 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Two receptor-specific monoclonal antibodies were used to recover the complementary DNA (cDNA) of this regulatory protein from a chicken intestinal lambda gt11 cDNA expression library. The amino acid sequences that were deduced from this cDNA revealed a highly conserved cysteine-rich region that displayed homology with a domain characteristic of other steroid receptors and with the gag-erbA oncogene product of avian erythroblastosis virus. RNA selected via hybridization with this DNA sequence directed the cell-free synthesis of immunoprecipitable vitamin D3 receptor. Northern blot analysis of polyadenylated RNA with these cDNA probes revealed two vitamin D receptor messenger RNAs (mRNAs) of 2.6 and 3.2 kilobases in receptor-containing chicken tissues and a major cross-hybridizing receptor mRNA species of 4.2 kilobases in mouse 3T6 fibroblasts. The 4.2-kilobase species was substantially increased by prior exposure of 3T6 cells to 1,25(OH)2D3. This cDNA represents perhaps the rarest mRNA cloned to date in eukaryotes, as well as the first receptor sequence described for an authentic vitamin. 相似文献
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Vitamin D deficiency inhibits pancreatic secretion of insulin 总被引：15，自引：0，他引：15
The effects of a vitamin D deficiency on insulin and glucagon release was determined in the isolated perfused rat pancreas by radioimmunoassay of the secreted proteins. During a 30-minute period of perfusion with glucose and arginine, pancreases from vitamin D-deficient rats exhibited a 48 percent reduction in insulin secretion compared to that for pancreases from vitamin D-deficient rats that had been replenished with vitamin D. Vitamin D status had no effect on pancreatic glucagon secretion. This result, along with the previously demonstrated presence in the pancreas of a vitamin D-dependent calcium-binding protein and cytosol receptor for the hormonal form of vitamin D, 1,25-dihydroxyvitamin D3, indicates an important role for vitamin D in the endocrine functioning of the pancreas. 相似文献
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1,25-dihydroxyvitamin D3: a novel immunoregulatory hormone 总被引：24，自引：0，他引：24
The hormonal form of vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], at picomolar concentrations, inhibited the growth-promoting lymphokine interleukin-2, which is produced by human T lymphocytes activated in vitro by the mitogen phytohemagglutinin. Other metabolites of vitamin D3 were less effective than 1,25(OH)2D3 in suppressing interleukin-2; their order of potency corresponded to their respective affinity for the 1,25(OH)2D3 receptor, suggesting that the effect on interleukin-2 was mediated by this specific receptor. The proliferation of mitogen-activated lymphocytes was also inhibited by 1,25(OH)2D3. This effect of the hormone became more pronounced at later stages of the culture. These findings demonstrate that 1,25(OH)2D3 is an immunoregulatory hormone. 相似文献
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分别用0、5000、10000、15000、20000 IU.L-1维生素A和维生素D3浸浴菲律宾蛤仔96 h,研究维生素A和维生素D3对蛤仔内脏团酸性磷酸酶(ACP)、碱性磷酸酶(ALP)和溶菌酶(LSZ)活性的影响.结果表明:维生素A能提高蛤仔内脏团ACP、ALP和LSZ的活性,在一定剂量范围内随着维生素A剂量的增加,ACP、ALP和LSZ活性显著提高(P0.05),但到96h时20000 IU.L-1维生素A会抑制ACP和LSZ的活性;维生素D3能提高ACP、ALP和LSZ的活性,在一定剂量范围内随着维生素D3剂量的增加,ACP、ALP和LSZ活性提高;维生素A和维生素D3微粒悬浮于水层中被蛤仔滤食,可在一定程度上提高3种水解酶的活性,以10000和15000 IU.L-1剂量的效果较好. 相似文献
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Embryonic chick intestine in organ culture: response to vitamin D 3 and its metabolites 总被引：3，自引：0，他引：3
R A Corradino 《Science (New York, N.Y.)》1973,179(71):402-405
Embryonic chick intestine maintained in organ culture responded to vitamin D(3) and its metabolites 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol by synthesis of calcium-binding protein and enchanced calcium-45 uptake. The dihydroxy metabolite was by far the most potent inducer of the protein and also acted more rapidly than vitamin D(3) to stimulate isotope uptake. Despite its lower potency, vitamin D(3) itself was effective. 相似文献
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Radioreceptor assay for 1 alpha,25-dihydroxyvitamin D3 总被引：14，自引：0，他引：14
P F Brumbaugh D H Haussler R Bressler M R Haussler 《Science (New York, N.Y.)》1974,183(129):1089-1091
A competitive protein binding assay with a sensitivity of 80 picograms has been developed for 1alpha,25-dihydroxyvitamin D(3), the hormonal form of vitamin D(3). lalpha,25-Dihydroxyvitamin D(3) displaced tritiated hormone from a cytosol-chromatin receptor preparation isolated from chick small intestine, providing a simple assay for the hormone. The concentration of lalpha, 25-dihydroxyvitamin D(3) in human plasma, as determined by this assay, is approximately 6 nanograms per 100 milliliters; in patients with renal disease the concentration of this kidney-produced hormone is significantly lower. 相似文献
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【目的】研究在基础日粮中添加不同水平维生素D3（VD3）对仔鹅钙磷代谢和免疫机能的影响。【方法】将300只健康、体重均匀的28日龄扬州鹅公鹅随机分成5个处理组,每个处理组6个重复,每个重复10只。对照组饲喂基础饲粮,试验组分别饲喂添加500、1 000、2 000和4 000 IU•kg-1维生素D3的试验饲粮,饲养至10周龄。【结果】基础日粮中添加1 000 IU•kg-1的维生素D3显著提高了10周龄扬州鹅血清钙含量、胫骨钙含量、胫骨强度和血清免疫球蛋白IgG含量（P＜0.05）;添加2 000 IU•kg-1维生素D3显著提高了血清钙含量（P＜0.01）、胸腺指数和血清白细胞介素-4水平（P＜0.05）;但日粮维生素D3水平对血清磷含量和碱性磷酸酶活性影响不显著（P＞0.05）。【结论】日粮中添加适宜水平的维生素D3（1 000—2 000 IU•kg-1）有利于提高扬州鹅仔鹅的钙代谢和免疫机能。 相似文献
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Liu PT Stenger S Li H Wenzel L Tan BH Krutzik SR Ochoa MT Schauber J Wu K Meinken C Kamen DL Wagner M Bals R Steinmeyer A Zügel U Gallo RL Eisenberg D Hewison M Hollis BW Adams JS Bloom BR Modlin RL 《Science (New York, N.Y.)》2006,311(5768):1770-1773
In innate immune responses, activation of Toll-like receptors (TLRs) triggers direct antimicrobial activity against intracellular bacteria, which in murine, but not human, monocytes and macrophages is mediated principally by nitric oxide. We report here that TLR activation of human macrophages up-regulated expression of the vitamin D receptor and the vitamin D-1-hydroxylase genes, leading to induction of the antimicrobial peptide cathelicidin and killing of intracellular Mycobacterium tuberculosis. We also observed that sera from African-American individuals, known to have increased susceptibility to tuberculosis, had low 25-hydroxyvitamin D and were inefficient in supporting cathelicidin messenger RNA induction. These data support a link between TLRs and vitamin D-mediated innate immunity and suggest that differences in ability of human populations to produce vitamin D may contribute to susceptibility to microbial infection. 相似文献
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1,25-dihydroxyvitamin D-responsive element and glucocorticoid repression in the osteocalcin gene 总被引：29，自引：0，他引：29
N A Morrison J Shine J C Fragonas V Verkest M L McMenemy J A Eisman 《Science (New York, N.Y.)》1989,246(4934):1158-1161
The active hormonal form of vitamin D3, 1,25-dihydroxyvitamin D3[1,25(OH), which regulates cellular replication and function in many tissues and has a role in bone and calcium homeostasis, acts through a hormone receptor homologous with other steroid and thyroid hormone receptors. A 1,25(OH)2D3-responsive element (VDRE), which is within the promoter for osteocalcin [a bone protein induced by 1,25(OH)2D3] is unresponsive to other steroid hormones, can function in a heterologous promoter, and contains a doubly palindromic DNA sequence (TTGGTGACTCACCGGGTGAAC; -513 to -493 bp), with nucleotide sequence homology to other hormone responsive elements. The potent glucocorticoid repression of 1,25(OH)2D3 induction and of basal activity of this promoter acts through a region between -196 and +34 bp, distinct from the VDRE. 相似文献
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A hydroxy analog of vitamin D(2), 1alpha-hydroxyvitamin D(2), has been synthesized and tested for biological activity. This vitamin derivative is active in stimulating intestinal calcium transport and bone calcium mobilization in the rat and exhibits antirachitic activity. Its biopotency is comparable to that of the corresponding vitamin D(3) analog, 1alpha-hydroxyvitamin D(3). 相似文献
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饲料中维生素D3含量对大口黑鲈生长和抗氧化能力的影响 总被引：1，自引：1，他引：0
为了探究饲料中维生素D3的含量对大口黑鲈(Micropterus salmoides)生长性能、钙磷代谢、肝脏抗氧化能力、血清生化指标和机体抗感染能力的影响,在基础饲料中分别添加0、15、30、45和60 IU/kg的维生素D3,设置5种维生素D3含量分别为1370、1385、1400、1415和1430 IU/kg的等氮等能饲料,饲养初始体质量为(14.19±0.05)g的大口黑鲈9周。结果表明:饲料中不同含量的维生素D3显著影响大口黑鲈的增重率、特定生长率和饲料系数,对存活率、肥满度和脏体比没有显著影响,添加维生素D3会显著降低大口黑鲈肝体比;随着饲料中维生素D3含量的升高,大口黑鲈脊椎骨中粗灰分、钙和磷的含量以及血清中钙离子含量呈增加趋势,但对肌肉粗蛋白质、粗脂肪、粗灰分和水分的含量没有显著影响。饲料中添加维生素D3可以显著提高大口黑鲈肝脏中总超氧化物歧化酶活力、过氧化氢酶活力和总抗氧化能力,显著降低血清中谷草转氨酶活力;机体对嗜水气单胞菌的抗感染能力也随着饲料中维生素D3含量的升高而增强。综上可知,饲料中维生素D3含量在1370~1430 IU/kg时,对大口黑鲈具有促进生长和保护健康的作用。 相似文献
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【目的】通过在0—15周龄鹅饲粮中添加不同水平维生素D3,探讨其对鹅生产性能、胴体品质和胫骨发育的影响;【方法】试验选择1日龄肝用型青农灰鹅360只,随机分为6个处理,每个处理6个重复,每个重复10只。维生素D3在基础饲粮中添加量分别为：0(对照组)、200、400、800、1600、3 200 IU•kg-1;试验期为15周,记录其采食量、体重和健康状况,计算生产性能;4周龄末和15周龄末分别从每重复抽取1只和2只试验鹅屠宰,测定其屠宰性能、胴体品质和胫骨指标。【结果】（1）饲粮中未添加维生素D3的对照组软骨症发生率为：0—4周36.67%,5—15周26.67%,明显高于试验组;维生素D3添加量3 200 IU•kg-1无临床中毒症状。（2）与对照组相比,饲粮添加400 IU•kg-1维生素D3可显著提高0—4周龄鹅日采食量和日增重(P＜0.05),维生素D3的添加可显著提高5—15周鹅日增重(P＜0.05),但添加组组间差异不显著。（3）饲粮中添加800 IU•kg-1维生素D3可极显著提高15周龄鹅的屠宰率(P＜0.01),显著提高半净膛率(P＜0.05);添加维生素D3对胸肌肉色有显著影响(P＜0.05)。（4）提高饲粮维生素D3水平可显著提高4周龄鹅胫骨的密度、重量及钙磷含量和15周龄胫骨密度、重量和灰分含量(P＜0.05);【结论】（1）添加维生素D3对鹅的生产性能、屠宰性能、肌肉品质和胫骨发育具有重要调控作用;饲粮中不添加维生素D3鹅的软骨症发生率明显增加。（2）鹅饲粮维生素D3最适添加量为：0—4周471.70 IU•kg-1,5—15周548.63 IU•kg-1。 相似文献
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为了进一步探究第11位氨基酸的性质对LvIA靶点结合活性的影响，设计了LvIA的2个新型突变体[D11R]LvIA和[D11H]LvIA，即用2个碱性氨基酸?精氨酸（R）和组氨酸（H）分别替换原来的酸性氨基酸D。先人工合成了这2个新突变体的线性肽，然后采用2步氧化法进行折叠，以获得在第1位和第3位半胱氨酸（Cys 1～3）、第2位和第4位半胱氨酸（Cys 2～4）之间定点连接形成二硫键。经高效液相色谱分离纯化和质谱鉴定，合成了含有Cys(1～3, 2～4)二硫键连接方式的多肽，其分子质量正确，纯度在95%以上。利用双电极电压钳电生理学技术对这2种突变体与α3β2 nAChR的结合活性进行了检测。结果发现，当该位点的氨基酸性质由酸性转换为碱性后，对LvIA的活性影响巨大，直接导致对α3β2 nAChR的阻断活性丧失。[D11R]LvIA和[D11H]LvIA的活性与野生型LvIA相比分别降低了574.38%和408.62%。由此表明，第11位氨基酸的酸碱性对LvIA的活性至关重要。 相似文献
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25-hydroxycholecalciferol: direct effect on calcium transport 总被引：5，自引：0，他引：5
The perfused small intestine from a vitamin D deficient rat exhibits about one-half the calcium transport of the intestine from a rat given vitamin D. These levels of calcium transport can be maintained for at least 4 hours. Addition of 2.5 micrograms of 25-hydroxycholecalciferol added to the vitamin D deficient intestine via the arterial blood perfusate induces a rise in calcium transport to +D levels within 2 hours. In contrast, 250 micrograms of vitamin D(3) given in the same manner has no effect on the calcium transport level overa 4-hour period. These data provide strong evidence that 25-hydroxycholecalci ferol represents the metabolically active form of vitamin D(3). 相似文献
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Solution conformations of the A and seco B rings of vitamin D(3), 1(alpha), 25-dihydroxyvitamin D(3), 1(alpha)-hydroxyvitamin D(3), and dihydrotachysterol(3) have been established by high resolution, 300-megahertz proton magnetic resonance spectroscopy. The A ring of these steroids is dynamically equilibrated between two chair conformers. For vitamin D(3), 1(alpha)-hydroxyvitamin D(3), and 1(alpha),25-dihydroxyvitamin D(3) the relative proportions of the two conformers are 1 : 1, whereas dihydrotachysterol3 exists principally as only one conformer. Thus, the substituent groups on the A ring may be either equatorially or axially oriented, and suggests a refinement of the existing topological model for vitamin D hormonal activity. 相似文献
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不同处理方式对草莓贮藏保鲜的影响 总被引：2，自引：0，他引：2
通过研究45℃预热处理和冰浴2种物理处理方式,以及柠檬酸、Ca Cl2和维生素C等复合化学处理方式对草莓贮藏保鲜效果的影响,探究了不同保鲜处理方式对贮藏4 d和6 d后草莓的外观、硬度、失重量、可滴定酸、可溶性固形物、SOD酶活性和维生素C含量的影响,筛选最适的保鲜剂浓度及贮存条件。结果表明,冰浴处理30 min能明显保持草莓外观与硬度,有效维持草莓可溶性固形物含量。2%柠檬酸处理1 min能显著提高草莓的SOD酶活性,2%柠檬酸+3%CaCl_2处理1 min能明显维持草莓保鲜中重量,2%柠檬酸+2%维生素C处理1 min能显著保持草莓可滴定酸和维生素C含量。综合分析表明,采用2%柠檬酸+2%维生素C处理1 min能较大程度的保持采后草莓的外观、硬度、口感及营养品质,保鲜期达6 d以上,可用于草莓采后保鲜。 相似文献
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EGF receptor and erbB-2 tyrosine kinase domains confer cell specificity for mitogenic signaling 总被引：17，自引：0，他引：17
P P Di Fiore O Segatto W G Taylor S A Aaronson J H Pierce 《Science (New York, N.Y.)》1990,248(4951):79-83
The epidermal growth factor (EGF) receptor (EGFR) can efficiently couple with mitogenic signaling pathways when it is transfected into interleukin-3 (IL-3)-dependent 32D hematopoietic cells. When expression vectors for erbB-2, which is structurally related to EGFR, or its truncated counterpart, delta NerbB-2, were introduced into 32D cells, neither was capable of inducing proliferation. This was despite overexpression and constitutive tyrosine kinase activity of their products at levels associated with potent transformation of fibroblast target cells. Thus, EGFR and erbB-2 couple with distinct mitogenic signaling pathways. The region responsible for the specificity of intracellular signal transduction was localized to a 270-amino acid stretch encompassing their respective tyrosine kinase domains. Thus, tissue- or cell-specific regulation of growth factor receptor signaling can occur at a point after the initial interaction of growth factor with receptor. Such specificity in signal transduction may account for the selection of certain oncogenes in some malignancies. 相似文献