西洋参茎叶总皂苷对胰岛素抵抗脂肪细胞葡萄糖转运、GLUT-4转位和CAP基因表达的影响

目的观察西洋参茎叶总皂苷(PQS)对脂肪细胞胰岛素抵抗状态下葡萄糖转运、葡萄糖转运子-4(GLUT-4)转位和c-cb1结合蛋白(CAP)基因表达的影响。方法将3T3-L1前脂肪细胞诱导分化为成熟脂肪细胞,用游离脂肪酸(FFA)制备脂肪细胞胰岛素抵抗(IR)模型,液闪仪测定3H标记的葡萄糖的摄取率,免疫荧光法检测GLUT-4转位,用逆转录-聚合酶链反应(RT-PCR)法检测培养细胞中CAPmRNA的表达。结果模型组胰岛素刺激下的葡萄糖转运率明显低于正常对照组(P<0.01);与模型组相比,二甲双胍组、PQS大/中剂量组葡萄糖转运率明显增加(P<0.01、P<0.01、P<0.05),但PQS小剂量组作用不明显。正常对照组在胰岛素刺激前,GLUT-4大部分位于胞质内,胰岛素刺激30min后,胞质内的分布较刺激前明显减少,胞膜周围的分布相对增加;而模型组在胰岛素刺激前后,GLUT-4在细胞内的分布无变化;但在二甲双胍组和PQS3个剂量组的结果显示,胰岛素刺激后,胞质内GLUT-4分布减少,胞膜周围的分布相对增加。模型组CAPmRNA水平较正常组明显下降(P<0.05);与模型组相比,二甲双胍和PQS大、中剂量组CAPmRNA水平明显上升(P<0.01),PQS小剂量未见明显效果。结论PQS可改善脂肪细胞IR,这可能与其促进脂肪细胞CAP基因转录、GLUT-4转位和葡萄糖转运有关。     

双(α-呋喃甲酸)氧钒对胰岛素抵抗3T3-L1脂肪细胞糖摄取的影响

目的探讨新型的有机羧酸氧钒配合物双(α-呋喃甲酸)氧钒(BFOV)对正常及胰岛素抵抗的3T3-L1脂肪细胞糖摄取的影响。方法采用地塞米松诱导3T3-L1脂肪细胞建立胰岛素抵抗的细胞模型,研究双(α-呋喃甲酸)氧钒对正常及胰岛素抵抗3T3-L1脂肪细胞葡萄糖消耗的影响。结果双(α-呋喃甲酸)氧钒(2.5μmol·L-1~40μmol·L-1)对正常的3T3-L1脂肪细胞仅有增加葡萄糖消耗量的趋势,与空白对照组比较,差异无显著性;但能明显增加地塞米松诱导的胰岛素抵抗3T3-L1脂肪细胞的葡萄糖消耗量,改善模型细胞的胰岛素抵抗状态。结论双(α-呋喃甲酸)氧钒能促进胰岛素抵抗脂肪细胞的葡萄糖摄取,改善胰岛素抵抗状态。     

褪黑素改善胰岛素抵抗3T3-L1脂肪细胞葡萄糖的摄取

目的研究褪黑素对游离脂肪酸(FFA)诱导的胰岛素抵抗3T3-L1脂肪细胞葡萄糖摄取能力的影响。方法 "鸡尾酒"法培养诱导3T3-L1成纤维细胞分化成脂肪细胞,油红O染色鉴定脂肪细胞形态;利用棕榈酸(300μmol/L)诱导脂肪细胞的胰岛素抵抗,采用液体闪烁法检测细胞葡萄糖摄取能力;检测褪黑素对FFA处理的3T3-L1脂肪细胞的葡萄糖摄取能力的影响。结果 3T3-L1细胞经诱导分化成脂肪细胞,油红O染色呈圆形,脂滴呈典型的"戒环样"形态;用FFA处理上述细胞6 h后,细胞的葡萄糖摄取能力明显降低;褪黑素可以促进FFA处理的3T3-L1脂肪细胞胰岛素介导的葡萄糖摄取。结论 FFA可以降低胰岛素诱导的体外培养的脂肪细胞葡萄糖摄取能力,可能是胰岛素抵抗的病因之一。褪黑素可以干预FFA的作用,增加细胞的葡萄糖摄取能力。     

催产素对3T3-L1脂肪细胞糖脂代谢的影响

目的 观察催产素对3T3-L1脂肪细胞糖脂代谢的影响。方法 3T3-L1前脂肪细胞体外培养,并诱导其分化成熟为脂肪细胞。研究催产素对脂肪细胞葡萄糖消耗量以及三酰甘油、游离脂肪酸和甘油的影响。采用实时荧光定量PCR法检测糖脂代谢相关基因GLUT-1、GLUT-4、ATGT、HSL的m RNA表达。结果 与对照组比较,催产素20、50、100μg/m L组葡萄糖消耗量有所增加,且表现出剂量相关。催产素组较对照组的三酰甘油降低,而甘油和游离脂肪酸增高。催产素50μg/m L组中脂代谢相关基因HSL表达明显高于对照组,糖代谢相关基因GLUT-4 m RNA表达水平增加。结论 催产素处理可减少3T3-L1细胞脂质合成、增加脂质分解作用,并可明显改善脂质积聚。     

荭草素抑制3T3-L1前脂肪细胞分化及其改善胰岛素抵抗的作用研究

目的研究荭草素对3T3-L1前脂肪细胞分化及对脂肪细胞胰岛素抵抗的影响,并探讨其作用机制。方法传统鸡尾酒法诱导分化3T3-L1前脂肪细胞,MTT法检测荭草素对前脂肪细胞活力的影响,油红O染色法检测脂质积累,酶法检测细胞内甘油三酯(triglyceride,TG)的含量。地塞米松诱导成熟的脂肪细胞,建立胰岛素抵抗模型,荧光标记2-脱氧葡萄糖(2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose,2-NBDG)摄入法观察脂肪细胞对葡萄糖的摄取能力;Western blot检测腺苷酸活化蛋白激酶(adenosine monophosphate activated protein kinase,AMPK)、乙酰辅酶A羧化酶(acetyl Co A carboxylase,ACC)的磷酸化水平及葡萄糖转运体4(glucose transporter type 4,GLUT4)的表达水平,免疫荧光法检测GLUT4的向膜转位能力。结果荭草素可浓度依赖性地减少细胞脂滴的积累及细胞内TG的含量,但对细胞活力无明显的影响(P>0.05)。胰岛素抵抗状态下,荭草素明显增加脂肪细胞对2-NBDG的摄取(P<0.05),明显上调AMPK、ACC的磷酸化水平(P<0.05),促进GLUT4的向膜转位及表达。结论荭草素抑制前脂肪细胞的分化,同时,荭草素通过上调AMPK/GLUT4信号途径相关蛋白的表达,促进了细胞对葡萄糖的摄取,达到改善胰岛素抵抗的作用。     

HDL对3T3-L1细胞葡萄糖转运的影响及其机制研究

目的探讨HDL对3T3-L1细胞葡萄糖转运的影响及其机制。方法通过对3T3-L1成纤维细胞的分化,培养符合实验要求的3T3-L1脂肪细胞。通过葡萄糖消耗实验和~3H标记的2-脱氧葡萄糖的摄取实验,研究HDL对葡萄糖转运的影响,应用RT-PCR和Western blot探讨其机制。结果 HDL可以促进3T3-L1脂肪细胞对葡萄糖的转运和摄取。3T3-L1脂肪细胞对葡萄糖的转运和摄取过程中,蛋白在RNA转录水平上没有增加,而是发生了AKT、AMPK蛋白的磷酸化。结论 HDL促进3T3-L1脂肪细胞对葡萄糖的摄取是通过AKT和AMPK两种途径来实现的。     

黄连素通过调节磷脂酰肌醇-3-激酶/丝氨酸/苏氨酸激酶/葡萄糖转运蛋白4信号途径改善胰岛素抵抗的机制研究

目的研究黄连素对胰岛素抵抗细胞3T3-L1细胞磷脂酰肌醇-3-激酶/丝氨酸/苏氨酸激酶(AKT)和葡萄糖转运蛋白4(GLUT4)mRNA和蛋白表达的影响,探讨黄连素改善胰岛素抵抗的分子机制。方法将3T3-L1脂肪细胞随机分为正常对照组、胰岛素抵抗、黄连素3组,应用地塞米松诱导细胞胰岛素抵抗,黄连素组同时加入黄连素。以葡萄糖氧化酶法测定3组细胞上清液中葡萄糖消耗量,观察黄连素对脂肪细胞葡萄糖摄取的影响;应用免疫印迹技术(Western blotting)技术测定脂肪细胞AKT和GLUT4的蛋白水平变化;应用实时荧光定量PCR技术检测脂肪细胞AKT和GLUT4的mRNA表达变化。结果与正常对照组相比,胰岛素抵抗组的AKT和GLUT4 mRNA和蛋白表达明显下降(P<0.05),经黄连素干预后,AKT和GLUT4 mRNA和蛋白表达水平有一定升高,但仍显著低于正常对照组(P<0.05)。结论黄连素通过上调AKT基因和蛋白的表达进而增加GLUT4的水平,改善胰岛素抵抗状态。     

二氢杨梅素对胰岛素抵抗3T3-L1脂肪细胞的改善作用及其机制研究

目的研究二氢杨梅素(dihydromyricetin,DMY)对3T3-L1脂肪细胞胰岛素抵抗的改善作用及其机制。方法采用地塞米松诱导3T3-L1脂肪细胞形成胰岛素抵抗细胞,以1×10-6mol·L-1罗格列酮为阳性对照,DMY(1×10-5¹×10-8mol·L-1)与胰岛素抵抗3T3-L1脂肪细胞共培养72 h,用葡萄糖氧化酶法测定细胞培养基中的葡萄糖含量,计算葡萄糖消耗量;采用RT-PCR检测脂肪细胞的GLUT4、Akt 2和脂联素基因的表达量。DMY(1×10-51×10-8mol·L-1)与胰岛素抵抗3T3-L1脂肪细胞共培养72 h,用葡萄糖氧化酶法测定细胞培养基中的葡萄糖含量,计算葡萄糖消耗量;采用RT-PCR检测脂肪细胞的GLUT4、Akt 2和脂联素基因的表达量。DMY(1×10-5¹×10-8mol·L-1)加入正常3T3-L1脂肪细胞中培养48 h,检测细胞的葡萄糖消耗量。结果 DMY(5×10-71×10-8mol·L-1)加入正常3T3-L1脂肪细胞中培养48 h,检测细胞的葡萄糖消耗量。结果 DMY(5×10-7¹×10-8mol·L-1)明显增加地塞米松诱导胰岛素抵抗3T3-L1脂肪细胞的葡萄糖消耗量,并呈现一定的浓度依赖性,和罗格列酮相比,差异无统计学意义。1×10-51×10-8mol·L-1)明显增加地塞米松诱导胰岛素抵抗3T3-L1脂肪细胞的葡萄糖消耗量,并呈现一定的浓度依赖性,和罗格列酮相比,差异无统计学意义。1×10-5¹×10-8mol·L-1DMY处理正常3T3-L1脂肪细胞48 h后,葡萄糖消耗量与正常组相比差异无统计学意义。RT-PCR结果显示,DMY作用于胰岛素抵抗的脂肪细胞72 h后,脂肪细胞的GLUT4、Akt2和脂联素基因的表达量明显增加,与地塞米松模型组相比,差异有统计学意义。结论 DMY能改善3T3-L1脂肪细胞的胰岛素抵抗状态,其机制可能与其上调GLUT4、Akt2和脂联素基因的表达量有关。     

小檗碱与梓醇及其配伍对胰岛素抵抗3T3-L1脂肪细胞Glut-4、IRS-1、IRS-1 Ser307磷酸化蛋白表达的影响

目的：观察梓醇与小檗碱及其配伍对胰岛素抵抗3T3-L1脂肪细胞葡萄糖消耗及这一过程中葡萄糖转运子-4（Glut-4）、胰岛素受体底物-1（IRS-1）和胰岛素受体底物-1丝氨酸307（IRS-1Ser307）磷酸化蛋白表达的影响。方法：采用高糖联合高胰岛素诱导3T3-L1脂肪细胞产生胰岛素抵抗，分别给予小檗碱、梓醇、小檗碱＋梓醇、盐酸罗格列酮进行干预，以葡萄糖氧化酶法检测培养液中葡萄糖消耗量，以WesternBlot法检测蛋白的表达。结果：与模型组相比，小檗碱能增加培养液中葡萄糖的消耗（P〈0．01），但对Glut，4蛋白的表达无影响；梓醇、小檗碱＋梓醇均能显著增加培养液中葡萄糖的消耗（P〈0．01），并使细胞中Glut-4蛋白的表达增强（P〈0．05），且小檗碱＋梓醇组的效应优于梓醇组及小檗碱组；与模型组相比，小檗碱与梓醇及其配伍对IRS-1的表达没有显著性影响，但能降低IRS-1 Ser307磷酸化蛋白表达。结论：小檗碱、梓醇及其配伍能改善胰岛素抵抗3T3-L1脂肪细胞的胰岛素敏感性，其作用机制与罗格列酮不同。     

体外胰岛素抵抗细胞模型的建立及在药物筛选中的应用

目的在体外建立肝胰岛素抵抗细胞模型和脂肪细胞胰岛素抵抗模型,并初步应用于中药有效成分的胰岛素抵抗活性筛选中。方法采用高胰岛素诱发HepG2细胞建立肝胰岛素抵抗模型,地塞米松诱发3T3-L1脂肪细胞建立脂肪细胞胰岛素抵抗模型,研究不同药物对胰岛素抵抗模型细胞葡萄糖消耗的影响。结果将HepG2细胞置于10-6mol·L-1的胰岛素中36h,HepG2细胞对胰岛素的抵抗作用最为明显,该特性可维持48h,但未发现细胞形态学变化;地塞米松作用3T3-L1脂肪细胞后,96h空白组与模型组葡萄糖消耗量差值最大,此时为胰岛素抵抗的最高状态;脂肪细胞胰岛素抵抗模型成立后,撤掉地塞米松,胰岛素抵抗细胞模型能够在24h内稳定。某些中药提取成分(如水苏糖、小檗碱和人参皂苷等)能促进HepG2胰岛素抵抗模型和3T3-L1脂肪细胞胰岛素抵抗模型的葡萄糖消耗。结论高胰岛素诱导培养法可以复制出稳定可靠的肝胰岛素抵抗细胞模型;地塞米松诱导3T3-L1脂肪细胞也可建立稳定的脂肪细胞胰岛素抵抗模型。     

Synthese von γ,γ'-Dihydroxysulfonen und γ-Hydroxy-γ'-ketosulfonen

Syntheses of γ,γ'-Dihydroxysulfones and γ-Hydroxy-γ'-ketosulfones Reduction of γ,γ'-diketosulfones 1 with dimethylaminoborane leads to γ,γ'-dihydroxysulfones 3 via γ-hydroxy-γ'-ketosulfones 2 . The influence of substituents on the ratio of the yields of 2 and 3 is investigated.     

Analysis of γβ, βγ, γγ, ββ multiple turns in proteins

Abstract: The number of γ‐turns in a representative protein dataset selected from the current Protein Data Bank has increased almost seven times during the past decade. Eighty percent classic γ‐turns and 57% inverse γ‐turns are associated as multiple turns with either another γ‐turn or a β‐turn. We refer to these as multiple turns of the (γβ)_1,2,3 or (βγ)_1,2,3 type, depending upon whether the γ‐turn is before or after the β‐turn along the protein chain, respectively. However, for multiple turns involving only γ‐turns, we follow the nomenclature analogous to that proposed earlier for the multiple (or double) β‐turns. Fifty‐eight per cent β‐turns are associated as multiple turns with another β‐turn. We extracted multiple turns from the protein dataset and classified them on the basis of individual γ‐ or β‐turn types and the number of overlapping residues. Furthermore, we evaluated the amino acid positional potentials and determined the statistically significant amino acid preferences, hydrogen bond/side‐chain interaction preferences in the multiple turns and secondary structure preferences for residues immediately flanking these turns. The results of our analysis would be useful in the modeling, prediction or design of multiple turns in proteins. The amino acid sequence corresponding to the multiple turn, position in the protein chain, PDB Code/chain in which multiple turn is present and the individual turn types constituting the multiple turns are available from our website and this information would also be integrated in our Database of Structural Motifs in Proteins ( http://www.cdfd.org.in/dsmp.html ).     

Analysis of γβ, βγ, γγ, ββ continuous turns in proteins

Abstract: We report the observation of continuous turns in proteins which comprise individual γ‐turns or β‐turns or both that are situated immediately one after the other along the polypeptide chain. The continuous turns were identified from a representative data set of three‐dimensional protein crystal structures. The γβ/βγ, γγ and ββ continuous turns represent peptides of varying amino acid residue lengths and conformations. The continuous turns frequently observed in proteins were: γβ, between a coil and a strand; βγ, between a helix and a strand; γγ, between coils; and ββ, either between a strand and a coil or between strands or coils. We determined the statistically significant amino acid residue preferences at individual positions in the turn, calculated amino acid positional potentials and analyzed main chain hydrogen bonds and side‐chain interactions likely to stabilize the continuous turns. The data on continuous turns have been integrated in the database of structural motifs in proteins (DSMP) on our web server at ( http://www.cdfd.org.in/dsmp.html ). This is useful to make queries on sequences compatible with different continuous turns.     

3-O-demethyl-2,3-di-epi-fortimicins and 3-O-demethyl-3-epi-fortimicins

Syntheses of the 3-O-demethyl-2,3-di-epi-fortimicins A and B and the 3-O-demethyl-3-epi-fortimicins A and B have been accomplished in processes the key steps of which were solvolyses of 4-N-acetyl-3-O-demethyl-3-O-methanesulfonylfortimicin derivatives. Antibacterial activities of the new antibiotics are reported.     

3',3'-Difluoro-3'-deoxythymidine: comparison of anti-HIV activity to 3'-fluoro-3'-deoxythymidine.

3',3'-Difluoro-3'-deoxythymidine (3) has been synthesized in four steps from thymidine, and characterized by 1H NMR and NOE experiments. The JHF coupling constants support a conformation in solution that is predominantly 2'-endo (S). Although conformationally and sterically nucleoside 3 may resemble other thymidine analogs which are active against HIV-1, 3 is virtually inactive.     

Lactone, 10. Mitt. Zur Synthese N-heterocyclisch substituierter γ,γ-Diphenyl-γ-butyrolactone

Lactones, X: Synthesis of γ,γ-Diphenyl-γ-butyrolactones Substituted by N-Heterocycles Starting from 3 and 16 , syntheses of γ,γ-diphenyl-γ-butyrolactones with N-heterocycles at the α-position are described. Scope and limitation of the syntheses, tautomerism and stereochemistry of the products as well as spectroscopic results which are inconsistent with data from the literature are discussed.