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31.
此项工作在新疆平原荒漠区盐化草甸带进行。研究结果显示出K、Na、Ca、Mg 4种元素在植物体内不同器官的含量分布特点和各个器官中不同元素间的含量关系。同时表明这4种元素在植物体不同器官中具有不同的作用。对于K、Na元素,地上部器官尤其叶片中含量水平反映出器官具有较强的留K排Ns的选择性元素的分配机制。 相似文献
32.
Richard J. Bold Jin Ishizuka Srinivasan Rajaraman †J. Regino Perez-Polo Courtney M. Townsend Jr. James C. Thompson 《Journal of neurochemistry》1995,64(6):2622-2628
Abstract: Carcinoid tumors are a group of neuroendocrine neoplasms distributed widely throughout the body but most commonly occurring in the gut. These tumors retain many characteristics of their neural crest origin, including secretion of neuroactive peptides and responsiveness to neurotrophic substances. Nerve growth factor (NGF), a neurotrophic protein involved in maintenance and differentiation of peripheral sympathetic and sensory neurons, regulates growth of several neural tumor cells by inducing a differentiated phenotype and subsequent inhibition of cell growth rate. We examined the actions of NGF in a functioning human pancreatic carcinoid cell line (termed BON). NGF has no effect on the cytoarchitecture or constitutive secretion of bioamines in this carcinoid cell line. NGF, however, stimulates the in vitro cellular proliferation of BON cells. BON cells possess mRNA for the NGF receptors (p75LNGFR and p140trkA ) and membrane-associated tyrosine kinase activity is increased in response to NGF. Both the mitogenic activity of NGF, as well as the receptor-linked tyrosine kinase activity, can be abrogated in BON cells by the trkA inhibitor K-252a and specific anti-NGF antibody. Our studies demonstrate that NGF is a mitogen for this carcinoid cell line without effect on cellular phenotype or cytoarchitecture. NGF may play a role in the development and progression of human carcinoid tumors. 相似文献
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34.
鱼腥藻HB1017株化能异养生长的研究 总被引:5,自引:1,他引:4
以葡萄糖和蔗糖为碳源,检测了六株(种)鱼腥藻的化能异养生产能力。其中鱼腥藻HB1017株化能异养生长较快,鱼腥藻HB0株化能异养生长缓慢,其余四种鱼腥藻不能进行化能异养生长。鱼腥藻HB1017株能利用果糖、葡萄糖、蔗糖为底物进行化能异养生长,但生长速率依次递减,差别显著。8磅湿热灭菌的果糖和蔗糖,与过滤灭菌的相比,只能维持低得多的化能异养生长速率。然而,8磅湿热灭菌的葡萄糖能维持比过滤法灭菌的高得 相似文献
35.
生态环境对白芷产量质量的影响 总被引:1,自引:0,他引:1
生态环境对白芷产量质量的影响陈兴福,丁德蓉,刘岁荣,卢进,黄文秀(四川省中医药研究院药物种植研究所,南川648408)EffectofEco-EnvironmentonDahurianAngelicaYieldandItsQuality¥ChenXi... 相似文献
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37.
Glycerol kinase as a substitute for dihydroxyacetone kinase in a mutant of Klebsiella pneumoniae. 总被引:2,自引:2,他引:0 下载免费PDF全文
With dihydroxyacetone as the sole source of carbon and energy, constitutively synthesized glycerol kinase of the glp system supported aerobic growth of Klebsiella pneumoniae mutants lacking the inducible dihydroxyacetone kinase of the dha system. Glycerol kinase had an apparent Km of 0.01 mM for its physiological substrate and 1 mM for its surrogate substrate. However, the growth rate on dihydroxyacetone of cells relying on glycerol kinase increased with the concentration of the carbon and energy source up to 50 mM, suggesting that permeation is rate limiting. 相似文献
38.
F S Jin R J Youle V G Johnson J Shiloach R Fass D L Longo S H Bridges 《Journal of immunology (Baltimore, Md. : 1950)》1991,146(6):1806-1811
Treatment of normal mice with a mAb to CD4 (GK1.5) was explored as a means of inhibiting the antibody response to an immunotoxin. Three days of pretreatment with 200 micrograms of GK1.5 completely abrogated the primary antibody response to a 3-micrograms dose of a mutant diphtheria toxin conjugated to an anti-transferrin receptor antibody. The same dose and schedule of anti-CD4 antibody significantly reduced and delayed, but did not prevent, the anamnestic antitoxin response in animals that had been previously primed to the immunotoxin. Three daily injections of anti-CD4 antibodies followed by weekly doses of immunotoxin resulted in a 3-wk delay in the development of antitoxin antibodies, and the kinetics of the antitoxin response correlated with the kinetics of recovery of CD4+ T cells in the spleen and lymph nodes. The antitoxin response to repeated doses of immunotoxin was completely abrogated when anti-CD4 antibodies were given every 2 wk throughout the course of immunotoxin treatment. Thus, transient depletion of Th cells during treatment can block the immune response to an immunotoxin. There was no evidence of tolerance induction with this regimen. 相似文献
39.
转移及非转移肿瘤移植后615小鼠血液流变学变化的研究 总被引:1,自引:0,他引:1
血道高转移瘤株FC、淋巴合并血道高转移瘤株U14、淋巴道高转移瘤株H22、非转移瘤株P615分别接种于336只纯系近交615小鼠.不同时间取血并处死动物,进行组织学及血液流变学检查.将转移瘤发展过程分为潜伏期、侵袭期、转移早、中、晚期,非转移瘤发展过程分为潜优期、增殖期、囊腔形成期及中心坏死期.本实验结果显示,不同转移能力及途径肿瘤发展的不同时期血液流变学变化规律不同,因而表明肿瘤侵袭、转移与血液流变学变化之间存在互为因果的紧密关系.其临床诊断及治疗意义被讨论. 相似文献
40.
3-Hydroxydicarboxylic acids are major urinary metabolites derived from fatty acid metabolism. These compounds are produced from the omega-oxidation of 3-hydroxy fatty acids. The production of the precursor 3-hydroxy fatty acids from incomplete beta-oxidation of fatty acids in rat liver mitochondria was investigated. Independent of the chain length or the concentration of fatty acid substrates, the accumulation of 3-hydroxyacyl intermediates was relatively constant at the concentration of 3-5 nmol/mg of mitochondrial protein. The extent of the incomplete oxidation was the same in Percoll gradient-purified mitochondria. Rotenone treatment increased the production of 3-hydroxy fatty acids. 3-Hydroxy fatty acids did not exist as pure L-enantiomer as expected from beta-oxidation. Instead, these metabolites were epimerized to a near racemic mixture of D- and L-isomers with a slightly dominant D-isomer (58 +/- 3%). By using deuterium-isotope labeling, the mechanism of epimerizartion was shown to be a rapid dehydration-rehydration through trans-2-enoyl-CoA. In addition, cis-3 and trans-3 fatty acids were produced; these metabolites were derived from the isomerization of trans-2-enoyl-CoA. Epimerase and isomerase were thought to be enzymes involved in the oxidation of unsaturated fatty acids. Current data have shown that the metabolism of these acids is actually through NADPH-dependent reduction pathways. The activities of epimerase and isomerase detected in rat liver mitochondria possibly function mainly in the metabolism of saturated fatty acids in a reverse role to the conventional concept. 相似文献