双歧杆菌对大肠癌细胞ccL187cAMP,cGMP影响的实验研究

双歧杆菌对维持机体正常微生态平衡具有重要作用。本文研究了长双歧杆菌对大肠癌细胞ｃｃＬ１８７内第二信使ｃＡＭＰ、ｃＧＭＰ浓度的影响,对长双歧杆菌的对数期培养物分别进行下列处理：活菌、死菌、代谢产物作用ｃｃＬ１８７细胞２小时后分别收集ｃｃＬ１８７细胞内的ｃＡＭＰ、ｃＧＭＰ浓度。实验表明长双歧杆菌的不同状态及代谢产物对ｃＡＭＰ、ｃＧＭＰ产生显著影响,且存在时间依赖关系,三种处理作用ｃｃＬ１８７细胞内的ｃ     

肺动脉内皮细胞与肺动脉平滑肌细胞增殖的相互调节

血管内皮细胞和血管平滑肌细胞在结构和功能上关系密切,二者的相互关系在血管舒缩和血管壁结构的调节中起重要作用。本文观察了培养的小牛肺动脉内皮细胞（ＰＡＥＣ）和肺动脉平滑肌细胞（ＰＡＳＭ）在细胞增殖方面的相互调节作用。混合培养的ＰＡＥＣ和ＰＡＳＭ细胞的３Ｈ－ＴｄＲ参入明显降低（Ｐ＜０．００１,与对照组相比）。无论向培养的ＰＡＥＣ和ＰＡＳＭ中分别加入ＰＡＳＭ和ＰＡＥＣ的条件培养基还是二者共培养时,均发现ＰＡＥＣ的３Ｈ－ＴｄＲ参入明显降低,而ＰＡＳＭ的３Ｈ－ＴｄＲ明显升高（Ｐ＜０．０５,与对照组相比）。流式细胞测定也发现共培养时ＰＡＥＣ的Ｇ１期细胞增多,Ｇ２／Ｍ期细胞减少;而ＰＡＳＭ的Ｇ１期细胞减少,Ｇ２／Ｍ期细胞增多。共培养的ＰＡＳＭ细胞内ｃＡＭＰ增加,ｃＧＭＰ含量降低;而ＰＡＥＣ细胞的ｃＡＭＰ和ｃＧＭＰ含量均降低（Ｐ＜０．０１,与对照组相比）。上述结果提示,ＰＡＥＣ和ＰＡＳＭ相互作用可能通过第二信使而调节它们本身的增殖     

低氧对CRF,AVP和NE刺激体外培养腺垂体细胞生成cAMP的影响

本文探讨了ＣＲＦ,ＡＶＰ及ＮＥ对体外培养大鼠腺垂体细胞生成ｃＡＭＰ的作用。ＣＲＦ刺激体外培养大鼠腺垂体细胞内ｃＡＭＰ的生成,且浓度与效应正相关。ＡＶＰ未引起细胞内ｃＡＭＰ差异性变化（Ｐ＞０．５）。ＮＥ使培养腺垂体细胞内ｃＡＭＰ水平降低。低氧使ＣＲＦ刺激ｃＡＭＰ生成的作用降低。而ＡＶＰ及ＮＥ可能是通过其它胞内信息通路。     

双歧杆菌粘附体外肠上皮细胞的钙信号传递的研究

本文采用钙荧光探剂 Ｆｌｕｏ—３／ＡＭ染色法,定量研究了双歧杆菌１０２７株、肠致病性大肠杆菌（ＥＰＥＣ）对体外肠上皮细胞Ｌｏｖｏ细胞株粘附的钙信号传递机制。结果表明,双歧杆菌１０２７株粘附可引起Ｌｏｖｏ细胞内Ｃａ~＋２随时间延长而梯度升高,但双歧杆菌１０２７株的作用远不如ＥＰＥＣ明显。同时发现双歧杆菌粘附引起Ｌｏｖｏ。细胞内Ｃａ~２＋升高主要源于细胞外Ｃａ~２＋内流所致,这与ＥＰＥＣ粘附引起宿主细胞内Ｃａ~２＋升高主要源于细胞内Ｃａ~２＋储池的Ｃａ~２＋释放不同。ＥＰＥＣ粘附引起宿主细胞内Ｃａ~２＋大幅度升高是其致病的重要信号传递基础;而双歧杆菌粘附仅引起宿主细胞内Ｃａ~２＋轻度升高,可能是其作为生理性细菌与肠上皮细胞和谐共生的信号传递基础。     

新型生长抑肽对成纤维细胞的DNA合成及某些癌基因表达的影响

从细胞水平和基因水平研究了新型生长抑肽（ＥＰＰ）的生物学作用,研究表明：ＥＰＰ对ＮＣ３Ｈ１０及ＴＣ３Ｈ１０细胞的ＤＮＡ合成均有抑制作用,当ＥＰＰ与ｃＡＭＰ的位点选择性类似物８－Ｂｒ－ｃＡＭＰ共同作用时,其对ＮＣ３Ｈ１０细胞的ＤＮＡ合成的抑制作用消失,而对ＴＣ３Ｈ１０仍具有抑制作用;核酸杂交分析表明,ＥＰＰ可以抑制ｃ－ｆｏｓ、ｎｅｕ、ｋｉ－ｒａｓ三类癌基因在转化细胞中的表达。证明了ＥＰＰ对转化细胞的生长具有一定的抑制效应,且与８－Ｂｒ－ｃＡＭＰ联合使用时其效果更佳。     

双歧杆菌分泌RNA的实验

目的：通过双歧杆菌对数生长期培养液中出现核酸的性质的研究探索双歧杆菌作用于机体的分子机制。方法：采用液体培养双歧杆菌方法;提取对数生长的双歧杆菌培养发酵液中的总核酸;将纯化后的核酸用RNA降解酶降解,电泳观察核酸条带电泳结果。结果：双歧杆菌对数生长期培养发酵液中仅存在RNA。结论：双歧杆菌对数生长期可能分泌100bp RNA。     

膜去极化与cAMP在胰岛细胞株HIT中诱导CBP片段的转录活性

为了研究 Ｃ Ｂ Ｐ在胰岛 Ｈ Ｉ Ｔ 细胞中调节基因转录的机制,将不同的 Ｃ Ｂ Ｐ片段瞬时转染到细胞中,观察其转录活性．实验表明,在胰岛 Ｈ Ｉ Ｔ 细胞中,膜去极化及 ｃ Ａ Ｍ Ｐ 均可诱导 Ｃ Ｂ Ｐ３０（ Ｃ Ｒ Ｅ Ｂ结合功能区）转录活性增强,并有协同效应． Ｐ Ｋ Ｃ对 Ｃ Ｂ Ｐ３０ 的转录活性无影响;与 Ｃ Ｒ Ｅ Ｂ有更强结合力的 Ｃ Ｂ Ｐ Ｋ Ｉ Ｘ Ｓ／ Ｂ（氨基酸序列短于 Ｃ Ｂ Ｐ３０ 的 Ｃ Ｒ Ｅ Ｂ结合功能区）其基本转录活性及膜去极化、ｃ Ａ Ｍ Ｐ诱导下的转录活性均比 Ｃ Ｂ Ｐ３０ 更强．反义 Ｃ Ｒ Ｅ Ｂ 的过度表达可降低 ｃ Ａ Ｍ Ｐ诱导的 Ｃ Ｂ Ｐ的转录活性．提示在胰岛 Ｈ Ｉ Ｔ 细胞中,膜去极化及 ｃ Ａ Ｍ Ｐ对共转录因子 Ｃ Ｂ Ｐ转录活性的调节作用通过 Ｃ Ｒ Ｅ Ｂ介导．     

新型生长抑肽对成纤维细胞的DNA合成及某些癌基因表达的影响

从细胞水平和基国水平研究了新型生长抑肽（ＥＰＰ）的生物学作用，研究表明：ＥＰＰ对ＮＣ３Ｈ１０及ＴＣ３Ｈ１０细胞的ＤＮＡ合成均有抑制作用，当ＥＰＰ与ｃＡＭＰ的位点选择必类似物８－Ｂｒ－ｃＡＭＰ共同作用时，其对ＮＣ３Ｈ１０细胞的ＤＮＡ合成的抑制作用消失，而对ＴＣ３Ｈ１０仍具有抑制作用；核酸杂交分析表明，ＥＰＰ可以抑制ｃ－ｆｏｓ，ｎｅｕ，ｋｉ－ｒａｓ三类癌基因在转化中的表达，证明了ＥＰＰ对转化细胞的生长     

钙调素拮抗剂对人肺癌细胞增殖抑制及与cAMP信号系统相关性之初探

对钙调素（ＣａＭ）拮抗剂—三氟拉嗪（ｔｒｉｆｌｕｏｐｅｒａｚｉｎｅ,ＴＦＰ）在人肺癌细胞ＰＬＡ８０１的增殖抑制中的作用和ＣａＭ与ｃＡＭＰ信号系统水平的变化进行了研究．用５、１０、１５和２０μｍｏｌ／ＬＴＦＰ处理人肺癌细胞时观察到ＴＦＰ在抑制细胞内ＣａＭ活性的同时,抑制了细胞的增殖．药物处理的细胞在软琼脂中形成的集落数减少且明显小于对照组细胞．使用流式细胞光度术分析细胞周期的结果表明：１０μｍｏｌ／ＬＴＦＰ处理抑制了Ｇ１期细胞向Ｓ期的转移．当用１０μｍｏｌ／ＬＴＦＰ作用细胞５ｍｉｎ时,细胞内ｃＡＭＰ水平达到正常水平的１．８倍,直到３ｈ仍明显高于正常水平．同时,ｃＡＭＰ依赖的ＰＫＡ的活性在加药后１５ｍｉｎ上升到正常水平的２．８倍,直到加药３ｈ．活性仍保持较高水平,结果表明：钙调素功能的抑制,提高了ＰＬＡ－８０１细胞内ｃＡＭＰ系统的水平,Ｃａ２＋－ＣａＭ和ｃＡＭＰ－ＰＫＡ两个信号系统的协调作用,抑制了细胞的增殖     

双丁酰cAMP对人体肺腺癌细胞表面凝集素受体及其侵袭能力的影响

着重观察双丁酰ｃＡＭＰ对培养的人肺腺癌细胞膜上多种凝集素受体表达的影响,并将体外经双丁酰ｃＡＭＰ处理的癌细胞接种于裸鼠皮下,观察移植瘤自发性生长状况。结果表明,经双丁酰ｃＡＭＰ处理的人肺腺癌细胞表面ＲＣＡ、ＷＧＡ、ＵＥＡ－１、ＤＢＡ、ＣｏｎＡ凝集素受体表达降低,同时伴有移植瘤成瘤潜伏期延长,侵袭能力下降。结果提示双丁酰ｃＡＭＰ导致的癌细胞表面数种凝集素受体的表达下降,可能是恢复癌细胞间粘附识别能力、降低其侵袭力的机制之一     

乳杆菌DM9811代谢产物中的RNA组分对宫颈癌细胞cAMP/cGMP影响

目的通过分析乳杆菌DM9811代谢产物中的RNA组分对宫颈癌细胞cAMP/cGMP影响,探讨乳杆菌对细胞作用的分子机制。方法采用细胞与分子生物学方法。结果乳杆菌代谢产物中的RNA组分对细胞的信息分子cAMP具有重要的调节活性。当除去代谢产物中的RNA分子刺激细胞时,细胞内的cAMP水平低于纯化后的RNA组cAMP水平,低了1.75倍,cGMP水平也出现了对应关系。结论乳杆菌DM9811代谢产物中的RNA组分对细胞内信息分子cAMP/cGMP具有调节作用。     

Effects of fatty acids on activity of cGMP-stimulated cyclic nucleotide phosphodiesterase from calf liver

Effects of fatty acids, prostaglandins, and phospholipids on the activity of purified cGMP-stimulated cyclic nucleotide phosphodiesterase from calf liver were investigated. Prostaglandins A2, E1, E2, F1 alpha, and F2 alpha, thromboxane B2, and most phospholipids were without effect; lysophosphatidylcholine was a potent inhibitor. Several saturated fatty acids (carbon chain length 14-24), at concentrations up to 1 mM, had little or no effect on hydrolysis of 0.5 microM [3H]cGMP or 0.5 microM [3H]cAMP with or without 1 microM cGMP. In general, unsaturated fatty acids were inhibitory, except for myristoleic and palmitoleic acids which increased hydrolysis of 0.5 microM [3H]cAMP. The extent of inhibition by cis-isomers correlated with the number of double bonds. Increasing concentrations of palmitoleic acid from 10 to 100 microM increased hydrolysis of [3H]cAMP with maximal activation (60%) at 100 microM; higher concentrations were inhibitory. Palmitoleic acid inhibited cGMP hydrolysis and cGMP-stimulated cAMP hydrolysis with IC50 values of 110 and 75 microM, respectively. Inhibitory effects of palmitoleic acid were completely or partially prevented by equimolar alpha-tocopherol. Palmitelaidic acid, the trans isomer, had only slightly inhibitory effects. The effects of palmitoleic acid (100 microM) were dependent on substrate concentration. Activation was maximal with 1 microM [3H]cAMP and was reduced with increasing substrate; with greater than 10 microM cAMP, palmitoleic had no effect. Inhibition of cGMP hydrolysis was maximal at 2.5 microM cGMP and was reduced with increasing cGMP; at greater than 100 microM cGMP palmitoleic acid increased hydrolysis slightly. Palmitoleic acid did not affect apparent Km or Vmax for cAMP hydrolysis, but increased the apparent Km (from 17 to 60 microM) and Vmax for cGMP hydrolysis with little or no effect on the Hill coefficient for either substrate. These results suggest that certain hydrophobic domains play an important role in modifying the catalytic specificity of the cGMP-stimulated phosphodiesterase for cAMP and cGMP.     

Effects of intracellular cyclic AMP and cyclic GMP levels on DNA synthesis of young-adult rat hepatocytes in primary culture.

Possible roles of dibutyryladenosine 3',5'-cyclic monophosphate (cAMP) and dibutyryl-guanosine 3',5'-cyclic monophosphate (cGMP) in regulation of hepatocyte DNA synthesis were examined using primary cultures of young-adult rat hepatocytes maintained in arginine-free medium. Throughout the experimental period, nonparenchymal cells were hardly observed in the selective medium. When epidermal growth factor (EGF) was added to the cultures, a transient increase in the intracellular cAMP level preceded the elevation of hepatocyte DNA synthesis. EGF-stimulated hepatocyte DNA synthesis was remarkably enhanced by the elevation of the intracellular cAMP level induced by treatment with cAMP alone or a combination of cAMP and theophylline, an inhibitor of cyclic nucleotide phosphodiesterase. Furthermore, the early elevation of intracellular cAMP alone, which was induced by treatment with the combination of cAMP and theophylline, caused a remarkable increase in hepatocyte DNA synthesis. On the other hand, addition of EGF to the cultures caused a rapid decrease in the intracellular cGMP level followed by an increase in hepatocyte DNA synthesis. EGF-stimulated hepatocyte DNA synthesis was severely suppressed or completely inhibited by the elevation of the intracellular cGMP level induced by treatment with cGMP alone or a combination of cGMP and dipyridamole, a specific inhibitor of cGMP phosphodiesterase. These findings indicate that cAMP and cGMP act oppositely on the regulation of DNA synthesis of young-adult rat hepatocytes in primary culture: cAMP plays a positive role, whereas cGMP plays a negative role. Also it is strongly suggested that an early elevation of the intracellular cAMP level is essential for the onset of DNA synthesis in hepatocyte primary cultures.     

Cross-activation: overriding cAMP/cGMP selectivities of protein kinases in tissues.

cAMP- and cGMP-dependent protein kinases are homologous proteins and are predicted to exhibit very similar three-dimensional structures. Their cyclic nucleotide binding domains share a high degree of amino acid sequence identity. cAMP- and cGMP-dependent protein kinases are activated relatively specifically by cAMP and cGMP, respectively; and a single alanine-threonine difference between cAMP- and cGMP-binding domains partially accounts for this specificity. Thus, it would be expected that cAMP and cGMP mediate separate physiological effects. However, owing in part to the lack of absolute specificity of either enzyme and to the relatively high level of cAMP or cGMP in certain tissues, it is also possible that either cyclic nucleotide could cross-activate the other kinase. Increases in either cAMP or cGMP cause pig coronary artery relaxation. However, only cGMP-dependent protein kinase specific cyclic nucleotide analogues are very effective in causing relaxation, and cAMP elevation in arteries treated with isoproterenol or forskolin activates cGMP-dependent protein kinase, in addition to cAMP-dependent protein kinase. Conversely, increases in either cAMP or cGMP cause Cl- secretion in T-84 colon carcinoma cells, and the cGMP level in T-84 cells can be elevated sufficiently by bacterial enterotoxin to activate cAMP-dependent protein kinase. These results imply specific regulation of cAMP- and cGMP-dependent protein kinases by the respective cyclic nucleotides, but either cyclic nucleotide is able to cross-activate the other kinase in certain tissues.     

Thin layer chromatographic determination of organic acids for rapid identification of bifidobacteria at genus level

This study presents a simple and fast method for the identification of bifidobacteria using a thin layer chromatographic (TLC) analysis of the short chain fatty acids in a culture broth. When the chromatogram was sprayed with the indicator solution (methyl red-bromophenol blue in 70% ethanol), lactic acid exhibited two red spots, and acetic acid, propionic acid, and butyric acid all produced blue spots. Succinic acid and citric acid produced yellow and dark yellow spot, respectively. In addition, these organic acids showed different R(f) values. The total time taken to analyze the organic acids in the 10 bacterial culture broths using the proposed method was approximately 50 min. The proposed TLC method was used to analyze the organic acids in culture broths of the following strains, five Bifidobacterium species. (Bifidobacterium longum, B. breve, B. infantis, B. bifidum, and B. adolescentis) and five other lactic acid bacteria strains (Lactobacillus casei, L. bulgaricus, L. acidophilus, Streptococcus thermophilus, and S. lactis). Both spots of lactic acid and acetic acid were detected on all the TLC plates from the five bifidobacterial culture broths. The five other lactic acid bacterial culture broths, however, only exhibited lactic acid spots. Accordingly, the proposed TLC method would appear to be a useful tool for rapid identification of Bifidobacterium spp. at the genus level.     

The role of cyclic nucleotides in the regulation of mitotic activity in SSPE virus-infected human brain tissue.

The intracellular level of cGMP was independent of the rate of cell division in cells derived from virally infected brain tissue. The phosphodiesterase inhibitor R07-2956 (4-dimethoxybenzyl-2-imidazolidinone) increased the intracellular level of cGMP in virally infected brain cells, but it did not effect the level of cAMP. There was no correction between the increase in cGMP levels following addition of R07-2956 and changes in mitotic activity in the brain cell cultures. Experimental manipulations which increased the cAMP level were accompanied by a decreased mitotic rate indicating there was a correlation between mitotic activity and the level of cAMP in the same cells. Raising the intracellular level of cAMP by exogenous db-cAMP or cAMP or the use of other phosphodiesterase inhibitors routinely increased the level of cGMP as well. Conversely increasing the intracellular cGMP level by adding the exogenous cGMP increased the level of both cGMP and cAMP.A tissue culture system was used with the cell line derived from viral infected human brain tissue originally obtained from a patient with subacute sclerosing panencephalitis (SSPE). The intracellular levels of cAMP and cGMP were monitored by radioimmunoassay following manipulation of the system by addition of exogenous cGMP (0.05 mM), addition of exogenous db-cAMP (0.5 mM), or cAMP (0.5 mM) and the use of phosphodiesterase inhibitors: theophylline (1.0 mM), papaverine (50 μg/ml), 4-3-butoxy-4-methoxy benzyl-2-imidozalidinone (R020-1724) and R07-2956. Cell division was monitored in treated and non-treated cultures at 24 h intervals by analyzing the cell number and mitotic index.High levels of cGMP were found in cells which were not actively dividing but high levels were just as apt to be present in dividing cells. There was an inverse relationship between cell division and the level of cAMP.     

Guanosine 3',5'-monophosphate and the action of alkylating agents.

The intracellular level of guanosine 3',5'-monophosphate (cGMP) has been measured in Walker carcinoma cells in tissue culture after treatment with various alkylating agents. At concentrations which caused a rise in the level of adenosine 3',5'-monophosphate (cAMP) chlorambucil and 5-(1-aziridinyl)-2,4-dinitrobenzamide (CB 1954) produced only a small (35%) elevation of cGMP, while merophan had no such effect. This suggests that any effect of cAMP will not be outweighed by an equivalent rise in cGMP. Sepcific cytosolic binding of cGMP decreased with increasing resistance of Walker cells to alkylating agents, while the dissociation constant, KD, for binding increased. This was also observed with cAMP binding which suggests that the same protein in responsible for binding both nucleotides.     

Acid hydrolase activity and cyclic nucleotide contents in the rat heart during myocardial ischemia and postischemic reperfusion

The acid phosphatase and cathepsin D activities and cAMP and cGMP levels in isolated perfused rat heart were investigated during various periods of ischaemic myocardial injury and postischaemic reperfusion. The effect of phosphodiesterase inhibitor--caffeine was also studied. Free acid hydrolases activities and cyclic nucleotide content were increased under 40 and 60 min ischemia and 20 min postischaemic reperfusion. Addition of 50 microM caffeine to perfusion solution after 30 min of ischaemia resulted in increase of cAMP level, cAMP/cGMP ratio, lysosomal bound activities of acid hydrolase and decrease of free acid hydrolase activities. The obtained results suggested that defect in cAMP synthesis might be present in lysosomal membranes labilization in cardiomyocytes injured during ischaemic conditions. Addition of such agents, as caffeine, which increased heart cAMP level, may be effective in lysosomal membranes stabilization under reversible heart ischaemia and reperfusion.     

双歧杆菌粘附大肠癌细胞相关因素探讨

本文以青春双歧杆菌ＤＭ９２２７粘附大肠癌细胞ｃｌ－１８７为实验模型,探讨粘附的相关因素。结果表明：粘附需要一定的菌浓度（＞１０６ＣＦＵ／ｍｌ）,一定的温度（３７℃）及一定的时间（＞１０ｈ）,且偏酸更有利于粘附。破坏菌体表面的糖结构使粘附上升,而破坏蛋白结构则使粘附下降。