甲酸与费林试剂斑氏试剂反应的探讨

甲酸(H COH),由于其同时具有羧基COH和醛基H C,因此它具有羧酸的通性和醛的某些特性。一般认为甲酸能被弱氧化剂氧化,如和土伦试剂(Tollens)、费林试剂(Fehling)、斑氏试剂(Benedict)反应,生成相应产物Ag和Cu2O。在深入探讨甲酸与费林试剂和斑氏试剂反应的多次实验的基础上,发现甲酸在通常情况下不与斑氏试剂反应生成砖红色Cu2O沉淀,与费林试剂的反应也有疑问。     

氯化钾干扰鲎试剂凝胶反应的异议

王健美在《10％氯化钾对鲎试验的影响》(成空药学．1992年第3期)一文的讨论中认为；①氯化钾存在使得蛋白质变性或抑制了酶的活力，能使鲎试剂失效或敏感度下降。②输液中如加入10％氯化钾，再用鲎法分析药液是否存在热原，结论就会出现假阴性。     

临床诊断梅毒的两种试剂比较

梅毒是常见性病中对人体造成较大危害的一种。目前 ,临床上常用梅毒明胶颗粒凝集试验 (采用 TPPA试剂盒 )来进行梅毒的确认。最近 ,一种酶结合免疫吸附测定法( EL ISA)检测梅素的试剂盒上市。为了比较这两种试剂在敏感性和特异性方面的差异 ,我们用已确认的梅毒血清进行了检测。现将结果报告如下。1　材料和方法1.1　材料 :1血清 :来自于山西省性病门诊经 TPPA试剂盒确认的 3 0例阳性和 60例阴性血清。 2 EL ISA试剂盒 :北京金伟凯医学生物技术公司。实验原理 :所用包被抗原和酶标抗原均为精致的基因工程表达的梅毒螺旋体特异性抗原…     

化学发光酶免疫试剂与ELISA试剂检测HIV抗体的对比分析

经多年的检测实践和试剂评估结果证明,在种类繁多的HIV筛查试剂中,仍然缺乏其特异性和敏感性能与酶免试剂媲美的不同原理的艾滋病检测试剂。这对提高HIV检测质量无疑是一大缺陷。因此,寻求一种设计原理不同,敏感性和特异性均符合HIV筛查和复检试剂要求的艾滋病检测试剂,显得非常必要。本文对化学发光酶免疫试剂与ELISA试剂检测HIV抗体方法进行对比分析。     

试剂储存温度对试剂质量的影响

目的分析长时间储存的试剂稳定性下降的原因,寻求解决办法,保证试剂质量提高血液安全。方法对同一批试剂进行不同温度条件储存,测定其稳定性有无差异用来揭示试剂储存温度对试剂质量有无影响。结果长时间在不同温度条件下储存的试剂稳定性有较大差异。结论日常储存试剂的冰箱（平开门）在拿取存放的过程中温度波动较大,长时间储存对试剂的质量影响较大。     

肽键构建的新途径

肽键作为天然肽和蛋白的骨干普遍存在。氨基酸借肽键联结成蛋白质,肽键如同关节一样构建了蛋白质的骨架。同时肽键键也广泛存在于很多药物小分子中,常用的生成肽键键方法是羧酸和胺的脱水耦合反应,本综述总结了肽键生成的一些新途径,侧重于未保护的多肽片段的耦合。     

水份测定所用试剂的比较

本文用“有机碱试剂”代费休氏试剂使用于部分抗生素药品的水分测定，收到较好效果。该试剂稳定性强，毒性小，可用于生产过程及成品的质量控制。     

免疫试剂在使用前进行确认的必要性

<正>任何免疫试剂,不管是正规厂家还是一般厂家生产的试剂,不管是进口试剂还是国产试剂,亦或者是同一试剂,不同批次之间,试剂质量仍然存在差别,故在试剂进入实验室前都应该进行确认,确认包括方法、设备、人员技能以及其他与实验相关的因素的检测,只有通过检测,进行比较才能将适合本实验室的试剂运用于临床,保证实验的准确性和有效性。本实验欲将英国索灵公司生产的人类免疫缺陷病毒     

试剂对药检工作的干扰

试剂对药检工作的干扰烟台市药品检验所２６４０００侯爱荣孙书美尹爱群邹爱玲在药品检验工作中，甲醇、无水乙醇是最常用的化学试剂．许多人在得到不合格实验数据时，会冒然判定该样品即为不合格产品，往往忽视了试剂的影响．其实，有些试剂中的杂质足以让人们得出相反结...     

Effects of amounts of additives on peptide coupling mediated by a water-soluble carbodiimide in alcohols

Abstract: The optimal amounts of 1-hydroxybenzotriazole (HOBt), 3,4-dihydro-3-hydroxy-4-oxo-1,2,3-benzotriazine (HOOBt) and 1-hydroxy-7-azabenzotriazole (HOAt) for enhancement of peptide coupling mediated by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) hydrochloride in alcoholic solvents were found to be less than equimolar against the carboxyl component or the carbodiimide. In comparison with the use of equimolar additives, the use of less equimolar ones was more effective in suppressing the competitive ester formation and in increasing the yield of desired peptides. EDC hydrochloride/around 0.1 equimolar HOAt or HOOBt were efficient reagents for peptide synthesis in the media.     

POLYMERIC 2-MERCAPTOPYRIDINE AND 2-MERCAPTO-NITROBENZENE DERIVATIVES: New Reagents for Peptide Synthesis

Insoluble 2-mercaptopyridine and 2-mercapto-nitrobenzene derivatives were prepared by modification of commercially available polystyrene. Applicability of these polymers as reagents for the thiolytic removal of the 2-nitrophenyl-sulphenyl amino-protecting group and as supports for preparation of polymeric active esters was evaluated. Polymeric 2-mercaptopyridine (PMP) was found efficient for both purposes. It was used in the stepwise synthesis of Leu-enkephalin via the polymeric reagent approach, serving as an Nps-cleaver. Polymeric esters derived from PMP and Boc-amino acids proved to be excellent acylators. Their usefulness is exemplified in the preparation of two dipeptides, which were produced rapidly and in high yields and purity.     

Coupling factor 6 as a novel vasoactive and proatherogenic peptide in vascular endothelial cells

Coupling factor 6 (CF6) is composed of 76 amino acids and is present in the peripheral stalk of mitochondrial ATP synthase. The generation of CF6 is positively regulated by tumor necrosis factor α and shear stress via nuclear factor κB, and by high glucose via protein kinase C and p38 mitogen-activated protein kinase. CF6 is released outside of the cells from vascular endothelial cells, and binds to the β-subunit of the plasma membrane-bound ATP synthase in vascular endothelial cells and leads to intracellular acidosis. CF6 produces vasoconstriction, and the biological active site resides at the C-terminal portion. CF6 suppresses prostacyclin generation via inhibition of cytosolic phospholipase A₂. CF6 also suppresses nitric oxide synthase activity via an increase in asymmetric dimethylarginine and a decrease in platelet/endothelial cell adhesion molecule-1. CF6 induces the gene and protein expression of proatherogenic molecules such as endothelin 2, urokinase type plasminogen activator receptor, estrogen receptor β, a soluble short form of vascular endothelial growth factor receptor-1, and lectin-like oxidized low-density lipoprotein receptor-1. The plasma level of CF6 is elevated in patients with essential hypertension, diabetes mellitus, end-stage renal disease, acute myocardial infarction, and coronary heart disease. It is likely that CF6 contributes to the pathogenesis of cardiovascular diseases, but further intensive investigation is needed.     

Development of Peptidyl Lysine Dendrons: 1,3‐Dipolar Cycloaddition for Peptide Coupling and Antibody Recognition

A straightforward synthesis strategy to multimerize a peptide mimotopes for antibody B13‐DE1 recognition is described based on lysine dendrons as multivalent scaffolds. Lysine dendrons that possess N‐terminal alkyne residues at the periphery were quantitative functionalized with azido peptides using click chemistry. The solid‐phase peptide synthesis (SPPS) allows preparing the peptide dendron in high purity and establishing the possibility of automation. The presented peptide dendron is a promising candidate as multivalent ligand and was used for antibody B13‐DE1 recognition. The binding affinity increases with higher dendron generation without loss of specificity. The analysis of biospecific interaction between the synthesized peptide dendron and the antibody was done via surface plasmon resonance (SPR) technique. The presented results show a promising tool for investigations of antigen–antibody reactions.     

坎利酮的简便高效合成法

目的 简便高效合成坎利酮。方法 将醋酸去氢表雄酮依次经硫叶立德环氧化,NaCH(COOEt)2内酯化,2,3-二氯-5,6-二氰基-1,4-苯醌选择性脱氢得到目标产物坎利酮。结果 总产率69.8%。目标物经紫外光谱、红外光谱、核磁共振氢谱、质谱及元素分析确证了其化学结构。结论　改进后的工艺原材料价廉易得,操作简便,降低了生产成本,更适合工业化生产。     

Efficient Total Synthesis and Biological Activities of 6‐Deoxyisojacareubin

6‐Deoxyisojacareubin was directly synthesized in a six‐step route with an overall yield of about 20%. In this route, the excellent site selectivity of this Claisen rearrangement‐cyclization reaction cascade was achieved by inserting a bulky p‐tosyl group into the free 1‐OH, and in the last step, some efficient demethylation methods were explored. Furthermore, all synthesized intermediates including 6‐deoxyisojacareubin were evaluated for their inhibitory activity against the QGY‐7703 cell line. Of these, compound 1 and 6‐deoxyisojacareubin showed moderate activities with IC₅₀ values of 39.61 and 9.65 µM, respectively, when compared to the positive control 5‐fluorouracil with an IC₅₀ value of 11.24 µM. Further investigation using non‐radioactive detection of protein kinase C (PKC) suggested that these two compounds possessed potency in the inhibition of PKC.     

Peptide G protein agonists from a phage display library

G proteins may serve as targets for pharmacological activation of signaling pathways bypassing the regulatory events that may counteract the effect of the external stimulus on the level of receptors. We sought to identify peptides as lead structures interacting with G proteins utilizing a commercially available phage-display library. The heptapeptide library was screened for binding to human G alpha(i1) which was modified with a hexahistidine tag and immobilized on a Ni(2+)-coated surface. After several rounds of phage selection a number of phage clones with consensus sequences were found. Peptides with such sequences were chemically synthesized and their effect on [35S]GTP gamma S binding to G alpha(i1) and other G protein alpha subunits was determined. Through this process two peptide 'families' with the capability to activate G proteins were identified. The peptides showed no structural similarity to known peptide or nonpeptide G protein activators with a cationic amphiphilic structure like mastoparan or alkylamines. The functional relevance of the peptide-G protein interaction was shown by an increased sensitivity for guanine nucleotides of high-affinity agonist binding to A(1) adenosine receptors. The peptide G protein activators may, therefore, serve as novel tools for further investigation of receptor-independent activation of G proteins.     

A Novel and Efficient High-Yield Method for Preparing Bacterial Ghosts

Bacterial ghosts (BGs) are empty cell envelopes possessing native extracellular structures without a cytoplasm and genetic materials. BGs are proposed to have significant prospects in biomedical research as vaccines or delivery carriers. The applications of BGs are often limited by inefficient bacterial lysis and a low yield. To solve these problems, we compared the lysis efficiency of the wild-type protein E (E_W) from phage ΦX174 and the screened mutant protein E (E_M) in the Escherichia coli BL21(DE3) strain. The results show that the lysis efficiency mediated by protein E_M was improved. The implementation of the pLysS plasmid allowed nearly 100% lysis efficiency, with a high initial cell density as high as OD₆₀₀ = 2.0, which was higher compared to the commonly used BG preparation method. The results of Western blot analysis and immunofluorescence indicate that the expression level of protein E_M was significantly higher than that of the non-pLysS plasmid. High-quality BGs were observed by SEM and TEM. To verify the applicability of this method in other bacteria, the T7 RNA polymerase expression system was successfully constructed in Salmonella enterica (S. Enterica, SE). A pET vector containing E_M and pLysS were introduced to obtain high-quality SE ghosts which could provide efficient protection for humans and animals. This paper describes a novel and commonly used method to produce high-quality BGs on a large scale for the first time.     

Folate and TAT Peptide Co-Modified Liposomes Exhibit Receptor-Dependent Highly Efficient Intracellular Transport of Payload In Vitro and In Vivo

Purpose

Using different chain lengths of PEG as linkers to develop a novel folate (FA) and TAT peptide co-modified doxorubicin (DOX)-loaded liposome (FA/TAT-LP-DOX) and evaluate its potential for tumor targeted intracellular drug delivery.

Methods

FA/TAT-LP-DOX was prepared by pH gradient method and post-insertion method and the optimal ligand density was screened by MTT assay. In vitro evaluation was systematically performed through cytotoxicity assay, cellular uptake studies, subcellular localization and cellular uptake mechanism in folate receptor (FR) over-expressing KB tumor cells. In vivo tumor targeted delivery of FA/TAT-LP-DOX was also studied by in vivo fluorescence imaging in a murine KB xenograft model.

Results

The particle size and zeta potential determination indicated that FA and TAT were successfully inserted into the liposome and cationic TAT peptide was completely shielded. With the optimal ligand density (5% of FA and 2.5% TAT), the FA/TAT-LP-DOX exhibited improved cytotoxity and cellular uptake efficiency compared with its single-ligand counterparts (FA-LP-DOX and PEG/TAT-LP-DOX). Competitive inhibition and uptake mechanism experiments revealed that FA and TAT peptide played a synergistic effect in facilitating intracellular transport of the liposome, and association between FA and FA receptors activated this transport process. In vivo imaging further demonstrated the superiority of FA/TAT-LP in tumor targeting and accumulation.

Conclusions

Folate and TAT peptide co-modified liposome using different chain lengths of PEG as linkers may provide a useful strategy for specific and efficient intracellular drug delivery.     

Immunoassays and Reagents: December to February

The field of antisense oligonucleotides (ASONs) has now matured to the point that much of the original optimism regarding their therapeutic potential has been rekindled. The first antisense to reach the commercial stage, fomivirsen (Vitravene?) for cytomegalovirus (CMV) retinitis in immunocompromised patents, may be prescient for future successful members of this new therapeutic class in that it clearly illustrates the utility of ASONs when the problem of delivery is solved. The simplest way to solve the delivery problem is to administer ASONs directly, i.e., locally, to the target tissue. Fomivirsen is approved for direct intravitreal injection. This brief review examines recent work on local delivery of ASONs to treat a variety of human diseases.