Electrochemical immunoassay using quantum dot/antibody probe for identification of cyanobacterial hepatotoxin microcystin-LR

The presence of cyanobacterial hepatotoxins such as microcystin-LR poses health threats to humans due to their potential for causing severe physiological effects when contaminated drinking water is ingested. Here, the electrochemical detection of microcystin-LR is explored using a quantum dot/antibody (QD/Ab) probe for nanoparticle-based amplification and direct electrochemical transduction. The immunological recognition of microcystin-LR using the QD/Ab probe was amplified and converted to an electrochemical signal by measuring the cadmium ions released from QD based on square wave stripping voltammetry under optimized electrochemical factors. Whereas a qualitative analysis for microcystin-LR was achieved using the specific peak potential of the anodic voltammogram at −0.6 ± 0.05 V, concentration of the toxin was quantified based on the charge density of the anodic peak; a dynamic range of 0.227 to 50 μg/L and limit of detection of 0.099 μg/L were obtained with high sensitivity. The extracted microcystin-LR from Microcystis aeruginosa was estimated as 1,944 μg/g of dried weight of the microorganism.     

Effect of cyclodextrin on allergic action of the PiCl-induced in NC/Nga mice

Itching dermatitis, which is very similar to human atopic dermatitis, arises spontaneously in NC/Nga mice. Changes in lesional skin and the plasma concentration of IgE during the development of atopic dermatitis-like disease up to 8 weeks after the start of picryl chloride (PiCl) in NC/Nga mice were examined. In the mice which atopic dermatitis had been induced, 28-day administration of α cyclodextrin (α CD) significantly inhibited aggravation of detmatitis without having effects on body weight. Clinical signs and symptoms seen in PiCl treated NC/Nga mice began with erythema and haemorrhage, following oedema, superficial erosion, deep excoriation, scaling and dryness of the skin. An increase was observed in the number of mast cells and eosinophil infiltration in the lesional skin. Almost human patients with nasal inflammation or bronchial asthmatics symptoms disappeared by oral administration of α CD (5 mg/day) for 2 month. These results suggest that α CD is useful for treatment of human atopic dermatitis.     

Diversification and selection mechanisms for the production of protein repertoires

The physiological mechanism for producing antigen-specific antibodies is based on a two-phase neo-Darwinian process: the first phase consists of diversity generation (formation of the repertoire), and the second phase is antigen-mediated selection. In this article, we consider how the natural immunoglobulin gene-diversification processes can be exploited both in vivo and in vitro in order to allow the generation of novel antibody (and heterologous protein) repertoires.     

含磷抗原及含硫抗原诱导的抗体水解活性的比较

以过渡态理论为基础,以羧肽酶A(CPA)的天然肽底物马脲酰-苯丙氨酸为模型,分别以磷原子和硫原子为四面体过渡态类似物的中心原子来设计和合成了半抗原和全抗原,将两类抗原用免疫方法诱导制备出抗体,然后对两类抗体水解肽键的活性进行比较。     

免疫分析法进展

本文首先从试剂分析的观点对免及分析的原理进行了论.述,对抗体作为分析试剂进行了评价并且总结了标记免投分析的三种方式和四个环节;其次,对免疫分析的现状作了综述,并评述了当代免反分析的五个热点:基因工程抗体,生物素一亲合素多重标记体系,时间分辨荧光免疫分析,多组分免疫分析和自动化免疫分析;最后,对免疫分析的发展趋势作了讨论。     

Evaluation of Traumatic Spinal Cord Injury in a Rat Model Using 99mTc-GA-5 as a Potential In Vivo Tracer

Spinal cord injury (SCI) refers to the damage suffered in the spinal cord by any trauma or pathology. The purpose of this work was to determine whether ^99mTc-GA-5, a radiotracer targeting Glial Fibrillary Acidic Protein (GFAP), can reveal in vivo the reactivation of astrocytes in a murine model with SCI. A method for the ^99mTc radiolabeling of the mouse anti-GFAP monoclonal antibody GA-5 was implemented. Radiochemical characterization was performed, and radioimmunohistochemistry assays were used to evaluate the integrity of ^99mTc-GA-5. MicroSPECT/CT was used for in vivo imaging to trace SCI in the rats. No alterations in the GA-5’s recognition/specificity ability were observed after the radiolabeling. The GA-5’s radiolabeling procedure implemented in this work offers a practical method to allow the in vivo following of this monoclonal antibody to evaluate its biodistribution and specificity for GFAP receptors using SPECT/CT molecular imaging.     

氧化石墨烯量子点对鸡卵清蛋白递送-免疫增强佐剂效力评估

利用改进的Hummers法氧化鳞片石墨,获得富含羟基和羧基的氧化石墨烯量子点(GOQDs)。通过透射电子显微镜、X射线衍射、红外光谱及拉曼光谱测试表征其理化性质。此外,利用鸡卵清蛋白(OVA)作为模式抗原,构筑GOQDs/OVA纳米疫苗并评估其载量、安全性、免疫效力等。结果显示,GOQDs/OVA纳米疫苗直径在5nm左右,具有高度的水分散性和稳定性。其对OVA的最大负载量约为 500mg·g^-1,在pH=5.5和7.4环境下24 h的释放率分别为74.65%和56.93%,表现出pH刺激响应释放性能。当GOQDs浓度在500μg·mL^-1以下时,不会引起溶血、细胞损伤、重要组织发生病变等现象。免疫后,与 OVA单独免疫对照组相比,GOQDs/OVA纳米疫苗可以诱导产生高水平的免疫球蛋白G(IgG)、免疫球蛋白G1(IgG1)及免疫球蛋白G2a(IgG2a)抗体,提高白细胞介素(IL)-1β、IL-2、IL-4和IL-6、肿瘤坏死因子-α(TNF-α)和γ干扰素(IFN-γ)的分泌,同时促进脾中辅助性(CD4⁺)和细胞毒性(CD8⁺)T淋巴细胞百分比的增加。     

Docking small ligands in flexible binding sites

A novel procedure for docking ligands in a flexible binding site is presented. It relies on conjugate gradient minimization, during which nonbonded interactions are gradually switched on. Short Monte Carlo minimization runs are performed on the most promising candidates. Solvation is implicitly taken into account in the evaluation of structures with a continuum model. It is shown that the method is very accurate and can model induced fit in the ligand and the binding site. The docking procedure has been successfully applied to three systems. The first two are the binding of progesterone and 5β-androstane-3,17-dione to the antigen binding fragment of a steroid binding antibody. A comparison of the crystal structures of the free and the two complexed forms reveals that any attempt to model binding must take protein rearrangements into account. Furthermore, the two ligands bind in two different orientations, posing an additional challenge. The third test case is the docking of N^α-(2-naphthyl-sulfonyl-glycyl)-D -para-amidino-phenyl-alanyl-piperidine (NAPAP) to human α-thrombin. In contrast to steroids, NAPAP is a very flexible ligand, and no information of its conformation in the binding site is used. All docking calculations are started from X-ray conformations of proteins with the uncomplexed binding site. For all three systems the best minima in terms of free energy have a root mean square deviation from the X-ray structure smaller than 1.5 Å for the ligand atoms. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 21–37, 1998     

氯嘧磺隆胶体金免疫检测试纸条的制备与应用

利用胶体金标记的经亲和层析纯化的氯嘧磺隆单克隆抗体,氯嘧磺隆-牛血清白蛋白,羊抗鼠IgG制备了氯嘧磺隆胶体金免疫检测试纸条。该试纸条的最低检测极限为100μg/L,检测时间10 m in。8个土壤样品分别添加0~2000μg/L的氯嘧磺隆标样,用0.15 mol/L NaHCO3提取2 h后用气相色谱和试纸条进行检测,如果以100μg/L作为阳性与阴性样品的区分标准,气相色谱和试纸条检测结果完全一致。所制备的胶体金免疫检测试纸条可以用于土壤中氯嘧磺隆残留的筛选。     

Natural catalytic immunity is not restricted to autoantigenic substrates

The autoimmune repertoire is well known from previous studies to be capable of producing catalytic antibodies directed to self-antigens. In the present study, we explored the ability of 26 monoclonal light chains (Lchains) from multiple myeloma patients to cleave radiolabeled gp 120, a foreign protein. One L chain with this activity was identified. ¹²⁵I-gp120 and unlabeled gp 120 were cleaved at several sites by the L chain, as shown by SDS-polyacrylamide gel electrophoresis, autoradiography, and immunoblotting, respectively. The apparent dissociation constant of the L chain was 130–145 nM, indicating high-affinity gp 120 recognition. ¹²⁵I-albumin was not cleaved by the L chain, and various proteins and peptides did not inhibit gp 120 cleavage by the L chain, suggesting that the activity is not a nonspecific phenomenon. The substrate recognition determinants may be conserved in different HIV-1 strains, because gp 120 isolated from strains SF2, MN, and IIIB was found to be cleaved by the L chain. Micromolar concentrations of a synthetic peptide corresponding to residues 23–30 of gp 120 inhibited the cleavage of ¹²⁵I-gp 120, suggesting that these residues are components of the epitope recognized by the L chain. The toxic effect of gp120 in neuronal cultures was reduced by about 100-fold by pretreatment of the protein with the L chain. These observations open the possibility of utilizing gp120-cleaving antibodies in the treatment of AIDS.