Intramolecular hydrogen transfer reactions of thiyl radicals from glutathione: formation of carbon-centered radical at glu, cys, and gly

Glutathione thiyl radicals (GS(?)) were generated in H(2)O and D(2)O by either exposure of GSH to AAPH, photoirradiation of GSH in the presence of acetone, or photoirradiation of GSSG. Detailed interpretation of the fragmentation pathways of deuterated GSH and GSH derivatives during mass spectrometry analysis allowed us to demonstrate that reversible intramolecular H-atom transfer reactions between GS(?) and C-H bonds at Cys[(α)C], Cys[(β)C], and Gly[(α)C] are possible.     

Two new triterpenoids from the resin of Boswellia carterii

Two new triterpenoids, 3-oxotirucalla-7,9(11),24-trien-21-oic acid (1) and 18Hα,3β,20β-ursanediol (2), along with 15 known triterpenes, α-amyrin, α-boswellic acid, β-boswellic acid, acetyl α-boswellic acid, acetyl β-boswellic acid, 9,11-dehydro-β-boswellic acid, 9,11-dehydro-α-boswellic acid, acetyl 11α-methoxy-β-boswellic acid, 11-keto-β-boswellic acid, acetyl 11-keto-β-boswellic acid, acetyl α-elemolic acid, 3β-hydroxytirucalla-8,24-dien-21-oic acid, elemonic acid, 3α-hydroxytirucalla-7,24-dien-21-oic acid, and 3α-hydroxytirucall-24-en-21-oic acid, were isolated from the resin of Boswellia carterii Birdw.     

Probing the functional conformation of the tridecapeptide mating pheromone of Saccharomyces cerevisiae through study of disulfide-constrained analogs

Analogs of the Saccharomyces cerevisiaeα-mating factor, Trp-His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln-Pro-Met-Tyr, where Lys⁷ and Gln¹⁰ were replaced with Cys, Cys(CH₃), or Ser, were synthesized using solid-phase procedures on a phenylacetamidomethyl resin. Cyclo^7,10[Cys⁷,X⁹,Cys¹⁰,Nle¹²]α-factor, where X = D-Val, D-Ala, l -Ala and Gly, were prepared by on-resin cyclization using thallic trifluoroacetate in yields of 20–30%. Linear sulfhydryl-containing peptides were generated from their corresponding cyclic peptide by treatment with dithioerythritol in basic solution. In the linear analogs, replacement of both Lys⁷ and Gln¹⁰ with a cysteine residue resulted in an over 100-fold loss of the biological activity when compared with the native pheromone. The corresponding cyclic disulfides were 5–10-fold more active than their sulfhydryl-contaihing homologs, and cyclo^7,10[Cys⁷,L-Ala⁹,Cys¹⁰,Nle¹²] α-factor was 50-fold more potent than linear analogs containing Ser or Cys(CH₃) in positions 7 and 10. Binding competition studies indicated that all analogs had low affinity for the α-factor receptor and there was a poor correlation between binding and activity in a growth arrest assay. A cyclic analog in which residues 8 and 9 were replaced by 5-aminopentanoic acid was not biologically active. Based on NMR studies, all cyclic peptides have a higher tendency to form β-turns spanning residues 7–10 than their less active linear counterparts. The results provide strong evidence that this β-turn is important for optimal signal transduction by α-factor.     

Free radicals as potential mediators of metal-allergy: Ni- and Co-mediated free radical generation

The generation of free radicals by Ni²⁺ and Co²⁺ was studied at physiological pH in H₂O₂-containing solutions in the absence and presence of various radical-mediating ligands and in human peripheral blood mononuclear cell (PBMC) cultures. With ESR spectroscopy, free radical species were identified and quantitated by spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). Co²⁺ generated hydroxyl radicals from H₂O₂ in PBS solutions containing glutathione (GSH) or histidine (His). Omission of GSH or His from the reaction mixture significantly reduced the ESR-signal, indicating the importance of metal-chelation in free radical generation. Carnosine did not significantly enhance the reactivity of Co²⁺ toward H₂O₂, whereas cysteine (Cys) and N-acetylcysteine (NAC) suppressed free radical generation. Under identical reaction conditions, Ni²⁺ was markedly less reactive toward H₂O₂ in comparison with Co²⁺. GSH, His, Cys and NAC did not enhance free radical generation of Ni²⁺ from H₂O₂. However, in the presence of carnosine weak but significantly enhanced ESR intensities were found. Incubation of PBMC cultures from healthy subjects with Co²⁺ (10–50 μM) yielded the DMPO-OH adduct, suggesting Co²⁺-mediated hydroxyl radical generation. In contrast, incubation of PBMC cultures with Ni²⁺ (10–50 μM) did not produce a detectable ESR-signal. Ascorbic acid efficiently inhibited Co²⁺-mediated free radical generation in PBS solutions and PBMC cultures. The observed difference in free radical generating capacity between Ni²⁺ and Co²⁺ is of interest with respect to the absence of cross-reactivity between the two metal-ions in experimental allergic contact dermatitis.     

Specificity and formation of unusual amino acids of an amide ligation strategy for unprotected peptides

An important step in the recently developed ligation strategy known as domain ligation strategy to link unprotected peptide segments without activation is the ring formation between the C-terminal ester aldehyde and the N-terminal amino acid bearing a 8-thiol or 8-hydroxide. A new method was developed to define the specificity of this reaction using a dye-labeled alanyl ester aldehyde to react with libraries of 400 dipeptides which contained all dipeptide combinations of the 20 genetically coded amino acids. Three different ester aldehydes of the dye-labeled alanine: α-formylmethyl (FM), β-formylethyl (FE), and β,β,β-dimethyl and formylethyl esters (DFE), were examined. The DFE ester was overly hindered and reacted with N-terminal Cys dipeptides (Cys-X). Interestingly, it also reacted slowly with the sequences of X-Gly where Gly was the second amino acid and the X-Gly amide bond participated in the ring formation. Although the FE ester reacted similarly as the FM ester in the ring formation, the subsequent O,N-acyl transfer was at least 30-fold slower than those of the FM-ester. The FM α-formyl methyl ester was the most suitable ester and was reactive with dipeptides of six N-terminal amino acids: Cys, Thr, Trp, Ser, His and Asn. The order and extent of their reactivity were highly dependent on pH, solvent and neighboring participation by the adjacent amino acid. In general, they could be divided into three categories. (1) N-Terminal Cys and Thr were the most reactive. Cys reacted very rapidly and completely within 0.5 h to form thiazolidine in both aqueous and high content of water-miscible organic solvents. Thr reacted to form oxazolidine slowly in aqueous buffer (t₁/2 > 300 h) but rapidly and completely within 20 h in organic-water solvents. (2) N-Terminal Trp, His and Ser were comparatively much less reactive than Cys or Thr. Trp reacted slowly and completely in aqueous buffer but significantly more slowly and incompletely in water-organic solvents. Both His and Ser reacted very slowly and incompletely in both solvent systems. (3) Finally, Asn reacted nearly insignificantly in both solvent systems. The significant rate enhancement by the water-miscible organic solvent on Thr was particularly important to allow the synthesis of disulfide-rich protein domains. Furthermore, the ring formation with N-terminal Trp, His and Asn provided a convenient route to prepare their bicyclic and unusual heterocyclic derivatives for structure-activity study.     

18α-、18β-甘草次酸对他林洛尔在Caco-2细胞上外向转运的影响

目的:研究甘草次酸18位差向异构体即18α-甘草次酸(α-GA)、18β-甘草次酸(β-GA)对P-糖蛋白(P-gp)底物他林洛尔在Caco-2细胞上外向转运的调控作用。方法:建立Caco-2单层细胞模型,以P-gp底物他林洛尔为探针药物,评价α-GA、β-GA和P-gp抑制剂维拉帕米对他林洛尔在Caco-2细胞上外向转运的影响。HPLC法测定细胞转运液中他林洛尔的浓度,采用Luna C18色谱柱(4.6 mm×250 mm,5μm),流动相乙腈-甲醇-10 mmol·L-1醋酸铵(25∶10∶65,v/v/v),流速1.0mL·min-1,检测波长248 nm。结果:浓度为10μmol·L-1的α-GA、β-GA使他林洛尔TransportB-A增加,他林洛尔BL-AP表观渗透系数(Papp B-A)增大,对他林洛尔外向转运表现出诱导作用;α-GA诱导P-gp外排他林洛尔的能力强于β-GA。结论:α-GA、β-GA能诱导P-gp的外向转运,加速P-gp底物的外排,可能是甘草酸制剂增强肝脏解毒的机制之一。     

Solution structure of a biologically active cyclic LDV peptide analogue containing a type II′β-turn mimetic

The solution structure of cyclo-[Gly-Leu-Asp-Val-BTD] (BTD=β-turn dipeptide) has been determined by two-dimensional ¹H-NMR (nuclear magnetic resonance) spectroscopy and systematic conformational searching combined with molecular dynamics studies. The structure contains two hydrogen bonds between the Gly and Val residues, and a type I β-turn with Leu and Asp at the (i+ 1) and (i+ 2) positions of the turn. The cyclic compound shows activity in a scintillation proximity assay (SPA) for the inhibition of the interaction between the integrin α₄β₁ and vascular cell adhesion molecule-1 (VCAM-1). The structure-activity relationship of the LDV sequence is discussed. © Munksgaard 1996.     

Chelation in Metal Intoxication XXIX: α-Mercapto-β-aryl Acrylic Acids as Antidotes to Mercury (II) Toxicity

Abstract: α-Mercapto-β-(2-furyl) acrylic acid (MFA), α-mercapto-β-(phenyl) acrylic acid (MPA), α-mercapto-β-(2-hydroxyphenyl) acrylic acid (MHA), α-mercapto-β-(4-methoxyphenyl) acrylic acid (MMA), β-1,2-phenylene di-α-mercapto acrylic acid (1, 2-PDMA) and β-1, 4-phenylene di-α-mercapto acrylic acid (1, 4-PDMA) enhanced faecal excretion and reduced liver, spleen and blood burden of inorganic mercury when administered (0.5 m mol/kg, in two split doses) 24 hr after Hg (II) (1 mg/kg) in rats. MFA, MPA, MHA and MMA were also effective in lowering renal Hg mainly from the cytosol, without any significant increase in urinary excretion of Hg. The results indicate that all the mono-mercapto acrylic acids including MFA were more effective than di-mercapto acrylic acids and act through the mechanism characteristic of thiol chelators, that is, mobilization of Hg as their complexes, contrary to the reported observation that MFA acts through the induction of metallothionein.     

血清胱抑素C及β2微球蛋白联合检测在类风湿关节炎肾功能损伤中的临床意义

目的探讨血清胱抑素C（CysC）及β2微球蛋白（β2-MG）对不同病程类风湿关节炎（RA）患者肾功能损害的意义。方法选择107例不同病程RA患者,在全自动生化分析仪上测定血清CysC、β2-MG、尿素氮（BUN）、肌酐（Cr）。结果（1）CysC阳性率在RA亚急性期及慢性期高于急性期,RA亚急性期较高（26％）,与急性期比较差异有统计学意义（P0．05）;②随着患者病程的增加,血清CysC及血盼MG水平呈渐进性增高,差异有统计学意义（P〈0．05）;并且血清CysC与RA病程分层之间存在直线回归关系（P〈0．01）。结论联合检测血清CysC及β2-MG有助于发现早期RA。肾小球和肾小管的功能受损;血清CysC及陀MG的水平与RA的发生、发展有关,并对患者的预后判定有一定的临床意义。     

Chemical synthesis of five tubulin antigenic sequences

Five peptides comprising several potential epitopes of α and β-tubulin were synthesized by solid phase methods and purified to homogeneity by HPLC. These are RRNLDIERPTYTN (corresponding to positions 214–226 of the α chain of porcine brain tubulin), KDYEEVGVDSVEGE (α, 430–443), EGEFSEAREDMAALEKDYEEVGVDSVEGE (α, 415–443), RYPGQLNADLRKLAVN (β, 241–256) and ESNMNDLVSEYQQYQDATAD (β, 412–431). Appropriate conjugates with carrier proteins rendered all peptides immunogenic, raising antibodies that were cross-reactive with plate-adsorbed tubulin in ELISA. This reaction was completely inhibited by the corresponding free peptides, which indicates that these antibodies react specifically with the regions of α and β-tubulin encompassed by the peptides. The reaction was also fully inhibited by soluble tubulin in a stabilising buffer. In immunoblotting experiments, the anti-peptide antibodies were useful as specific markers for either α- or β-tubulin in brain extracts. The specificity of the anti-peptide antibodies for cellular microtubules was also examined by indirect immunofluorescence experiments.     

原发性高血压病患者尿微量蛋白检测的临床价值

目的探讨尿微量蛋白检测对原发性高血压病患者早期肾损害诊断的临床价值。方法选取原发性高血压病患者86例用竞争免疫分析法检测尿α1-微球蛋白（Uα1-MG）、尿β2-微球蛋白（Uβ2-MG）、尿白蛋白（UALB）、尿免疫球蛋白（UIGG）,并与40例正常健康者作比较。结果与正常对照组比较,原发性高血压病患者的UIGG增高显著（p〈0．05）,Uα1-MG、Uβ2-MG、UALB增高非常显著（P〈0．01）;与高血压1级患者比较,高血压2—3级患者的Uα1-MG、Uβ2-MG、UALB增高非常显著（P〈0．01）;与高血压1级患者比较,高血压2～3级患者Uα1-MG、Uβ2-MG、UALB检测的阳性率显著升高（P〈0．05）。结论尿微量蛋白检测对原发性高血压早期肾损害的诊断有帮助,能反映原发性高血压患者早期肾功能损害的部位和程度,其中以Uα1-MG、Uβ2-MG、UALB最敏感,定期检测对发现原发性高血压早期肾损害有重要的临床价值。     

Synthesis and biological activity of [L-hydroxyproline]3-tuftsin analogue and its α- or β-O-D-glucosylated derivatives

Syntheses are described of the Hyp³-tuftsin analogue and of its derivatives α- or β-O-glycosylated at the side chain function of the hydroxyproline residue. The carbohydrate-free tetrapeptide was prepared by reacting Z-Thr-Lys(Z)-OH with H-Hyp-Arg(NO₂)-OBzl by the mixed anhydride procedure. In the synthesis of the α-glycosylated analogue the O-glycosyl amino acid was incorporated by reacting Boc-(Glcα+β)Hyp-OH with H-Arg(NO₂)-OBzl through the same procedure. The α-glucosylated dipeptide was isolated from the diastereomeric mixture, selectively deblocked, and acylated with Z-Thr-Lys(Z)-OH by the mixed anhydride procedure. In the preparation of the β-glucosylated analogue the BOP procedure was used for reacting Boc-[Glc(Ac)₄β]Hyp-OH with H-Arg(NO)₂-OBzl was well as for the final coupling to tetrapeptide. Removal of protecting groups from crude tetrapeptides was achieved by catalytic hydrogenation. Deacetylation of the sugar moiety of the β-glucosylated tetrapeptide was achieved by treatment with sodium methoxide in methanol. The synthetic compounds were isolated by ion exchange chromatography, and characterized by elemental analysis, amino acid analysis, optical rotation and proton NMR. Their capacity to evoke the release of interleukin 1 from mouse peritoneal macrophages and to modulate immunogenic activity of antigen-fed cells was evaluated, in comparison with tuftsin and rigin. All of the analogues were found to possess tuftsin-like activity.     

羟丙基-β-环糊精与介质pH值对前列腺素E_1溶解度的综合影响（英文）

目的研究羟丙基-β-环糊精（HP-β-CD）与介质pH值对前列腺素E1（PGE1）溶解度的综合影响并进一步推导出该药物溶解度的理论方程。方法首先测定药物在不同pH值水中的溶解度;然后分别测定在酸性及中性系列浓度的HP-β-CD溶液中,药物的溶解度;最后推导出以HP-β-CD与介质pH值为变量的药物溶解度方程并对其合理性进行验证。结果溶解度测定结果表明,提高介质的pH值或以HP-β-CD为增溶剂,均可增加PGE1的溶解度。分子型药物或离子型药物与HP-β-CD测得的相溶解度图均为典型的AL型,提示药物结构上的五元碳环部分已嵌入HP-β-CD的疏水性孔穴中,从而形成1：1摩尔比包合物。结论以HP-β-CD作为增溶剂,同时提高介质的pH值,可对PGE1的溶解度产生协同增加效应。本研究中导出的PGE1溶解度方程,可有效表征HP-β-CD与介质pH值二者对该药物溶解度的综合影响。     

Unraveling the mechanism of β-N-oxalyl-α,β-diaminopropionic acid (β-ODAP) induced excitotoxicity and oxidative stress, relevance for neurolathyrism prevention

β-N-Oxalyl-α,β-diaminopropionic acid (β-ODAP) is a plant metabolite present in Lathyrus sativus (L. Sativus) seeds that is proposed to be responsible for the neurodegenerative disease neurolathyrism. This excitatory amino acid binds to α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors and several lines of evidence indicate that β-ODAP triggers motor neuron degeneration by inducing excitotoxic cell death and increasing oxidative stress. In addition, this toxin is known to disturb the mitochondrial respiration chain and recent data indicate that β-ODAP may inhibit the uptake of cystine thereby compromising the cells’ abilities to cope with oxidative stress. Recent work from our group furthermore suggests that β-ODAP disturbs the cellular Ca²⁺ homeostasis machinery with increased Ca²⁺ loading in the endoplasmic reticulum (ER)-mitochondrial axis. In this review, we aim to integrate the various mechanistic levels of β-ODAP toxicity into a consistent pathophysiological picture. Interestingly, the proposed cascade contains several aspects that are common with other neurodegenerative diseases, for example amyotrophic lateral sclerosis (ALS). Based on these mechanistic insights, we conclude that dietary supplementation with methionine (Met) and cysteine (Cys) may significantly lower the risk for neurolathyrism and can thus be considered, in line with epidemiological data, as a preventive measure for neurolathyrism.     

Specificity determinants of allosteric modulation in the neuronal nicotinic acetylcholine receptor: a fine line between inhibition and potentiation

We are interested in the allosteric modulation of neuronal nicotinic acetylcholine receptors (nAChRs). We have postulated that the anthelmintic morantel (Mor) positively modulates (potentiates) rat α3β2 receptors through a site located at the β(+)/α(-) interface that is homologous to the canonical agonist site (J Neurosci 29:8734-8742, 2009). On this basis, we aimed to determine the site specificity by studying differences in modulation between α3β2 and α4β2 receptors. We also compared modulation by Mor with that of the related compound oxantel (Oxa). Whereas Mor and Oxa each potentiated α3β2 receptors 2-fold at saturating acetylcholine (ACh) concentrations, Mor had no effect on α4β2 receptors, and Oxa inhibited ACh-evoked responses. The inhibition was noncompetitive, but not due to open channel block. Furthermore, the nature and extent of modulation did not depend on subunit stoichiometry. We studied six positions at the α(-) interface that differ between α3 and α4. Two positions (α3Ile57 and α3Thr115) help mediate the effects of the modulators but do not seem to contribute to specificity. Mutations in two others (α3Leu107 and α3Ile117) yielded receptors with appreciable α4-character; that is, Mor potentiation was reduced compared with wild-type α3β2 control and Oxa inhibition was evident. A fifth position (α3Glu113) was unique in that it discriminated between the two compounds, showing no change in Mor potentiation from control but substantial Oxa inhibition. Our work has implications for rational drug design for nicotinic receptors and sheds light on mechanisms of allosteric modulation in nAChRs, especially the subtle differences between potentiation and inhibition.     

Chelation in Metal Intoxication XXX: α-Mercapto-β-aryl Acrylic Acids as Antidotes to Cadmium Toxicity

Abstract: α-Mercapto-β-(2-furyl) acrylic acid (MFA), α-mercapto-β-(2-hydroxyphenyl) acrylic acid (MHA), β-1,2-phenylene di-α-mercaptoacrylic acid (1,2-PDMA) and β-1,4-phenylene di-α-mercapto acrylic acid (1,4-PDMA) were compared to sodium N-benzyl-D-glucamine dithiocarbamate (NBG-DTC) an effective cadmium chelator, for their ability to mobilize Cd and influence the Cd induced tissue metallothionein (MT) in rats administered ¹⁰⁰CdCl₂, 72 hr earlier. MFA was almost as effective as NBG-DTC but more effective than MHA in enhancing urinary and faecal excretion of Cd, reducing tissue and blood levels of Cd and in lowering Cd induced increase in hepatic and renal MT contents. 1,2-PDMA and 1,4-PDMA were effective only in reducing the hepatic burden of Cd. The resuls do not indicate any direct relationship between the efficacy of α-mercapto-β-aryl acrylic acids to decorporate body Cd and their lipophilic-hydrophilic character or number-arrangement of their sulfhydryl groups.     

Biological activities and modes of action of 9-alpha-D-arabinofuranosyladenine and 9-alpha-D-arabinofuranosyl-8-azaadenine

From earlier studies it is known that 9-α-d-arabinofuranosyladenine (α-araA) and 9-α-d-arabinofuranosyl-8-azaadenine (α-ara-8-azaA) bave in vitro antiviral activity, are cytotoxic, and are metabolized in mammalian cells to the triphosphates. This study was designed to compare the in vivo antiviral activities of these compounds and their loci of action with those of 9-β-d-arabinofura-nosyladenine (β-araA). the latter compound selectively inhibits DNA synthesis in intact cells, and its triphosphate is a known inhibitor of DNA polymerases and ribonucleotide reductase. Whereas β-araA was significantly effective in the treatment of systemic herpes simplex virus type 1 (HSV-1) infections in mice, α-araA and α-ara-8-azaA were therapeutically ineffective. α-AraATP at a concentration of ~1 mM did not inhibit (1) DNA polymerases present in crude extracts of cultured H.Ep.-2 cells; (2) DNA polymerases present in extracts of KB cells; (3) partially purified DNA polymerase-α from mouse embryo cells; or (4) DNA polymerases induced by HSV-1 and HSV-2. DNA polymerase-β from mouse embryo cells was inhibited to a small extent by 10^?4 M α-araATP. In contrast, all of these enzymes were inhibited by β-araATP at a concentration of 10^?5M (as shown in these or in earlier studies). the reductions of CDP and UDP by ribonucleotide reductase from L1210 cells were not inhibited by αaraATP (~10^?3M), whereas β-araATP produced 70–80 per cent inhibition at this concentration. In cultured H.Ep.-2 cells, α-ara-8-azaA inhibited the incorporation of thymidine, uridine, and formate into macromolecules, but it was without effect on the incorporation of adenine and hypoxanthine, and produced marginal inhibition of the incorporation of leucine. α-Ara-8-azaA produced a dose-dependent inhibition of the accumulation of [¹⁴C] formyl-glycinamide ribonucleotide in H.Ep.-2 cells treated with azaserine and [¹⁴C] formate. These results indicate that the α-nucleosides inhibit nucleic acid synthesis by mechanisms different from those of β-araA.     

1H-NMR signal assignments and secondary structure analysis of martentoxin

Martentoxin is a peptide of 37 amino acid residues purified from the venom of the Chinese scorpion Buthus martensi Karch, which has been demonstrated to be an inhibitor of voltage-dependent sodium channel and voltage-dependent delayed rectifier potassium channel. To elucidate the molecular mechanism of this interaction, the structure of martentoxin was studied by 2D-NMR. The secondary structure of martentoxin consists of a triple-stranded β-sheet connected to a α-helical structure. This helix encompasses 10 residues from Ser11 to Lys20. The three strands of β-sheet probably comprise residues Gly2-Asp5, Q27-N30 and Glu33-Cys36, Cys30-Asn33 with a type I′β turn centered on Asn31-Asn32. The results indicate that martentoxin possesses the conserved β α β β structure of all the potassium channel toxins.     

单侧输尿管结扎幼鼠肾间质纤维化中周细胞转分化趋势及意义

目的本实验旨在通过观察单侧输尿管结扎(UUO)幼鼠模型中周细胞标志物胶原Ⅰ型蛋白(coll1α1)、血小板源性生长因子β(PDGFRβ)、神经生长因子2(NG2)、平滑肌肌动蛋白(α-SMA)的表达水平的变化,进而探讨周细胞转分化趋势,以及用雷公藤多苷治疗后的干预效果。方法采用UUO模型,将5⁶周龄90只雄性幼年SD大鼠,按随机数表法平均分为3组,即假手术组(行手术分离但不结扎左侧输尿管)、模型组(手术结扎左侧输尿管近肾盂段)和雷公藤多苷干预组。分别在术后1、2、3、7、14 d每组各取6只小鼠处死,留取左肾,采用免疫组织化学法检测周细胞标志物coll1α1、PDGFRβ、NG2、α-SMA在肾间质纤维化过程中的表达水平的变化,同时利用Masson染色观测绿染面积(胶原纤维)的大小变化。结果 UUO模型组中coll1α1、PDGFRβ、NG2、α-SMA的表达水平显著高于假手术组(P<0.01),随着梗阻时间的延长,其表达水平均呈增高的趋势,纤维化程度逐渐加重;UUO模型组中Masson染色蓝染面积随着实验时间的增加而增大;雷公藤多苷干预组各时间点coll1α1、PDGFRβ、NG2、α-SMA的表达水平均低于模型组(P<0.01),纤维化程度较其减轻,但仍高于假手术组(P<0.01)。结论肾间质纤维化过程中,周细胞发生了转分化,治疗组雷公藤多苷可能有一定的抑制周细胞转分化作用,从而延缓纤维化的进程。     

β-endorphin. Synthesis and biological activity of analogs with disulfide bridges

Two analogs of human β-endorphin (β-EP) which contain cystine bridges, [Cys¹⁵-Cys²⁶,Phe²⁷,Gly³¹]-β-EP (I) and [Cys¹⁶-Cys²⁶,Phe²⁷,Gly³¹]-β-EP (II), were synthesized by the solid-phase method. Peptides I and II were shown to contain 2–2.5 times the opiate receptor binding activity of β-endorphin. We also synthesized two analogs with reduced alkylated cysteine residues and these peptides, [Arg^{9,19,24,28,29}Cys(Cam)^11,26, Phe²⁷,Gly³¹] and [Arg^{9,19,24,28,29},Cys-(Cam)^12,26, Phe²⁷, Gly³¹], were shown to have approximately the same opiate receptor activity as β-endorphin.