脂肪细胞对胰岛β细胞功能的内分泌调节作用

脂肪因子包括脂肪细胞分泌的多种活性因子,它们通过内分泌方式调节胰岛β细胞的胰岛素分泌、基因表达以及细胞凋亡等多方面的功能。本文提出脂肪因子影响胰岛β细胞功能主要通过三条相互联系的途径而实现。第一是调节β细胞内葡萄糖和脂肪的代谢;第二是影响β细胞离子通道的活性;第三是改变β细胞本身的胰岛素敏感性。脂肪细胞的内分泌功能是一个动态过程,在不同的代谢状态下,各脂肪因子的分泌发生不同变化。从正常代谢状态发展到肥胖以及2型糖尿病的过程中,脂肪因子参与了胰岛β细胞功能障碍的发生与发展。     

高糖通过下调FoxO1磷酸化诱导β细胞去分化

胰岛β细胞发生去分化现象是导致其功能减退的机制之一。已有研究证明,FoxO1与β细胞去分化密切相关。然而,高糖是否可通过FoxO1诱导β细胞发生去分化目前尚未见报告。本研究通过不同浓度高糖干预MIN6细胞,采用葡萄糖刺激胰岛素分泌试验（GSIS）检测β细胞功能|实时荧光定量PCR及蛋白免疫印迹、免疫荧光方法检测高糖干预后β细胞内祖细胞标志基因、β细胞标志基因及FoxO1的表达变化。结果显示,不同浓度高糖干预β细胞后,当浓度达到35 mmol/L时,β细胞祖细胞标志基因表达明显增加。且在该浓度时,检测到β细胞标志基因表达明显降低,MIN6细胞葡萄糖刺激胰岛素分泌功能减退,磷酸化FoxO1表达减少。上述结果提示,高糖可诱导胰岛β细胞去分化的发生,其机制可能是通过FoxO1介导。     

保护胰岛β细胞的体外研究进展

糖尿病是一种由胰岛素分泌缺陷和（或）胰岛素作用缺陷引起的高血糖症性代谢疾病。自Edmonton临床试验取得成功后,胰岛移植成为一种新型治愈糖尿病的方法。但胰岛β细胞在体外分离过程中极易发生凋亡或死亡,且长期的体外培养或冷冻储存也容易令其胰岛素分泌功能逐渐丧失。因此,有效维持或改善β细胞的成活率及功能对胰岛移植的成功至关重要。对胰岛β细胞的体外保护方法进行阐述,并对其研究前景进行展望。     

NLRP3炎症小体与2型糖尿病的研究进展

NLRP3炎症小体作为固有免疫系统的重要组成部分,在2型糖尿病的发病过程中起着重要作用,而白细胞介素1β(IL-1β)是介导其发挥作用的关键因子。核糖体蛋白质合成、嘌呤受体P2X7、活性氧敏感的硫氧还原蛋白相互作用蛋白(TXNIP)与NLRP3炎症小体激活密切相关。肥胖时胰岛素作用的靶组织中NLRP3、IL-1β表达均增高,其介导的炎症反应在胰岛β细胞功能障碍、凋亡以及胰岛素抵抗发生过程中起关键作用。NLRP3炎症小体被多种途径激活,从而上调胰岛和脂肪组织中IL-1β的表达,促进胰岛β细胞凋亡及胰岛素抵抗的发生发展,导致糖尿病的产生。     

转录因子FoxO1在糖尿病中的作用研究

在糖尿病的进程中,常伴随有多种蛋白质的表达水平及功能的改变。叉头框蛋白1(FOXO1)蛋白是人体内重要的转录因子,可以调节机体中多种基因的表达,包括与糖脂代谢、胰岛素抵抗、胰岛β细胞增殖分化和凋亡、线粒体功能以及细胞自噬密切相关的基因。近年来,随着技术的不断进步,越来越多的实验结果表明,FoxO1可以通过上述不同的途径参与糖尿病的形成及其相关肝脏、血管、神经、心脏并发症的发展。研究FoxO1在糖尿病及其并发症中的作用,有助于为寻找糖尿病及其并发症的治疗靶点提供新思路。     

氧化应激与2型糖尿病

胰岛素抵抗、胰岛β细胞功能受损是2型糖尿病的主要病因。高血糖、高血脂导致在代谢过程中,线粒体产生大量活性氧,其可损坏线粒体功能,引起氧化应激反应。氧化应激可以激活细胞内的一系列应激信号通路,如JNK／SAPK、p38MAPK、IKKβ／NF-kβ和氨基己醣通路等。这些应激通路的激活可以产生以下结果：（1）阻断胰岛素作用通路,导致胰岛素抵抗;（2）降低胰岛素基因表达水平;（3）抑制胰岛素分泌;（4）促进β细胞凋亡等。本文主要针对活性氧的产生、氧化应激诱导胰岛素抵抗和胰岛β细胞功能受损等机制加以综述,以便进一步阐明2型糖尿病的发病机理。     

自噬在2 型糖尿病和胰岛β 细胞中作用研究进展

胰岛素分泌缺陷和胰岛素抵抗是2型糖尿病发病的主要机制之一。高血糖和脂质代谢紊乱,是糖尿病发病机制中最重要的获得性因素。最近研究表明自噬在维持内环境稳定,胰岛β细胞数量分泌能力,及对抗胰岛素抵抗等方面有重要作用。本文就自噬的基本概念及在糖尿病发病和维持β细胞功能方面作一综述。     

肝细胞核因子在2型糖尿病发生中的作用研究新进展

肝细胞核因子(Hepatocyte nuclear factors,HNFs)是一类分布在肝、胰、肠、肾等多个组织器官,调节肝脏内基因特异性表达的一类转录因子。其主要亚型为HNF1、HNF3、HNF4和HNF6等,这些转录因子相互作用构成的复杂调控网络。2型糖尿病(Type2 diabetes mellitus,T2DM)的基本病理生理机制是胰岛素抵抗及胰岛β细胞损伤,最终导致高血糖。近年来的研究表明,HNFs在胰岛素抵抗及胰岛β细胞损伤中发挥关键的调控作用。本文对HNFs在T2DM发生中的胰岛素抵抗及胰岛β细胞损伤作用研究新进展作以回顾性综述,旨在为认识T2DM发病机制及提出防治策略提供理论基础。     

翻白草水提物对2型糖尿病大鼠胰岛形态及功能的保护机制研究

观察翻白草水提液对2型糖尿病大鼠胰岛形态及功能保护作用及机制。采用高脂乳剂灌胃加低剂量链脲佐菌素,建立2型糖尿病模型。生化技术检测血糖和血脂,ELISA检测血胰岛素含量,HE染色观察动物胰腺形态,免疫组化检测胰岛素、FoxO1及其磷酸化的表达。结果翻白草水提物可降低2型糖尿病大鼠血糖和总TC,促进胰岛素释放。光镜下胰岛素表达增加,胰岛β细胞核内FoxO1表达减少,包浆中p-FoxO1表达增加。翻白草水提液通过降低FoxO1,增加FoxO1的磷酸化表达,调控胰腺β细胞数量和功能,对2型糖尿病大鼠胰腺细胞具有保护作用。     

棕榈酸诱导胰岛β细胞氧化应激和内质网应激的研究进展

2型糖尿病（T2DM）主要由胰岛β细胞的胰岛素分泌缺陷和胰岛素抵抗引起。棕榈酸作为人体内最丰富的游离脂肪酸之一，其体内含量过高易造成脂代谢紊乱，诱导胰岛β细胞功能障碍及胰岛素抵抗。这与T2DM的发生发展密切相关，但具体机制尚未完全明确。棕榈酸诱导胰岛β细胞发生的氧化应激和内质网应激（ERS）是影响胰岛β细胞功能以及破坏胰岛素信号传导的关键应激途径。棕榈酸通过增加线粒体氧化、二酰基甘油-蛋白质激酶C-还原型辅酶Ⅱ途径、改变线粒体呼吸链正常功能和炎症刺激加重氧化应激，通过影响内质网折叠能力、破坏胞内蛋白运输途径、上调未折叠蛋白反应相关转录因子、棕榈酰化、降解羧肽酶E和减少内质网中Ca2+促进ERS，加剧胰岛β细胞功能障碍和凋亡，最终导致T2DM的发生与发展。本文综述了棕榈酸与胰岛β细胞内氧化应激和ERS的关联性，介绍了蛋白激酶R抑制剂、人参皂苷Rg1和三黄汤等具有潜力的中、西医靶向干预药物，为T2DM的临床治疗提供新思路。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium.     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.