Rapid detection of aflatoxin B_1 in Chinese herbal medicines by indirect and direct competitive enzyme-linked immunosorbent assays: a comparative analysis / 中国中药杂志

The indirect competitive enzyme-linked immunosorbent assay(ic-ELISA) and direct competitive enzyme-linked immunosorbent assay(dc-ELISA) were performed for the rapid detection of aflatoxin B_1(AFB_1) in Astragali Radix, Zingiberis Rhizoma Recens, Jujubae Fructus, and Nelumbinis Semen with self-made antigens and antibodies. Different extraction methods were investigated to reduce the matrix effects of different medicinal parts in Chinese herbal medicines. The sensitivity of dc-ELISA method was improved by optimizing the molar ratio of AFB_1 to horseradish peroxidase(HRP). In this study, the sensitivity(IC_(50)) of ic-ELISA and dc-ELISA was 0.046 and 0.023 ng·mL~(-1), with the limit of detection(LOD) of 0.007 and 0.004 ng·mL~(-1), respectively. The detection time was 3 h and 50 min for ic-ELISA and dc-ELISA, respectively. The recovery rates were within the range of 62.96%-104.4%, with RSDs of less than 10%. Confirmed by LC-MS/MS, three positive samples of Nelumbinis Semen were detected from 53 samples. Two ELISA methods established in this study were accurate, rapid and sensitive, and can be used for rapid screening of AFB_1 in Chinese herbal medicines such as Astragali Radix, Zingiberis Rhizoma Recens, Jujubae Fructus, and Nelumbinis Semen. In addition, the advantages and limitations of the two methods were compared and discussed, which can provide a reference for the testing institutions to choose the proper method.

Establishment of an in vitro screening model for uranium decorporation chelators based on the competitive ELISA method / 药学学报

Uranium [U(Ⅵ)] in the blood is known to form stable complexes with apotransferrin (apo-Tf), which plays an important role in mediating the cytotoxicity induced by U(Ⅵ) transported to cells. The present study aimed to establish an new in vitro screening model of U(Ⅵ) decorporation agents through exploring the capability of chelating agents competing with U(Ⅵ) binding to apo-transferrin based on enzyme-linked immunosorbent assay (ELISA). The optimal concentrations of apo-Tf coated antigen, Tf antibody, secondary antibody and U(Ⅵ) treatment were achieved and the stability and reproducibility of this method were validated by methodology study. Using this model, the ability of four chelating agents to mobilize the U(Ⅵ) binding to apo-Tf was evaluated, and the rank of competitiveness was catechol-3,6-bis(methyleiminodiacetic acid） (CBMIDA) ≈ Tiron > apo-Tf > DTPA-CaNa3 ≈ DTPA-ZnNa3. The efficacy of these chelating agents in removal of U(Ⅵ) was tested by animal experiments. The results showed that immediate administration of CBMIDA or Tiron after injection of U(Ⅵ) in mice significantly promoted urinary U(Ⅵ) excretion and reduced U(Ⅵ) accumulation in kidneys and femurs, while DTPA-CaNa3 and DTPA-ZnNa3 have no obvious effects as compared to U(Ⅵ)-exposed mice alone, which was consistent with the results of competitive ELISA method. The animal experiments conform to the rules of the Animal Research Ethics Committee of School of Pharmacy of Fudan University. These results show that the new proposed method is rapid, simple and convenient with good reproducibility and has the potential to be used for in vitro screening of U(Ⅵ) decorporation agents.

Preparation of an anti-cotinine monoclonal antibody and its application in immunological detection / 浙江大学学报·医学版

OBJECTIVE@#To prepare monoclonal antibody against cotinine (COT) and to establish immunoassay for detecting COT in human urinary samples.@*METHODS@#BALB/c mice were immunized with synthesized cotinine-bovine serum albumin (COT-BSA) to screen monoclonal antibody with technique of cell fusion. The monoclonal antibody was used for the indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and colloidal gold immunochromatographic strip assay for the detection of COT in human urine.@*RESULTS@#The monoclonal antibody against COT was identified by ic-ELISA with a 50%inhibitive concentration (IC@*CONCLUSIONS@#The ic-ELISA and colloidal gold immunochromatographic strip assay using the prepared monoclonal antibody against COT have been proved to be reliable for the rapid detection of COT in human urines, which may be used for monitoring of environmental tobacco smoke.

Effect of Puerarin on the Pharmacokinetics of Baicalin in Gegen Qinlian Decoction () in Mice / 中国结合医学杂志

<p><b>OBJECTIVE</b>To study the pharmacokinetics of puerarin (PUE) in Gegen Qinlian Decoction (, GQD), and the effects of PUE dosage variations on the pharmacokinetics of baicalin (BAL) in mice.</p><p><b>METHODS</b>GQD is composed of the concentrated granules of four Chinese herbs. Three dosages with different levels of PUE, including GQD, GQD co-administered with PUE, and GQD co-administration with two times the amount of PUE, were used to research the pharmacokinetics of PUE and BAL in mice. The indirect competitive enzyme-linked immunosorbent assay (icELISA) methods based on an anti PUE-monoclonal antibody (MAb)and BAL-MAb were employed to determine the concentration of PUE and BAL in mice blood.</p><p><b>RESULTS</b>After the co-administration of GQD with PUE, the area under the curves (AUC) of PUE increased 2.8 times compared with GQD. At the dose of GQD co-administration at two times that of PUE, the (AUC) of PUE was almost equal to that of GQD co-administration of PUE, showing non-linear pharmacokinetics. The (AUC) of BAL showed a good dose-related increase of PUE (r=0.993) in the range from 100 to 300 mg/kg, indicating that PUE dramatically affects the absorption of BAL in mice. There was no significant difference in the other pharmacokinetic parameters, such as the first time of maximum concentration (T), the second T, or the mean residence time.</p><p><b>CONCLUSIONS</b>The icELISA methods were successfully applied to pharmacokinetic studies of PUE and BAL in GQD in mice. The dosage variability of PUE of the main ingredient in GQD affects its own pharmacokinetic characteristics and the absorption characteristics of BAL.</p>

A serological study of severe fever with thrombocytopenia syndrome using a virus neutralization test and competitive enzyme-linked immunosorbent assay

Severe fever with thrombocytopenia syndrome (SFTS) is caused by the SFTS virus (SFTSV). The SFTSV appears to have a wide host range, as SFTSV-positive ticks have been isolated from both farm animals and wild rodents. Therefore, it is important to monitor SFTSV-positive animals to prevent the transmission of SFTSV from animals to humans. Previously, we developed a competitive enzyme-linked immunosorbent assay (cELISA) to detect SFTSV-specific antibodies from field animals and compared the cELISA results to those from an indirect immunofluorescence assay (IFA). In this study, cELISA results were compared to and evaluated against the results from both an IFA and a virus neutralization (VN) test of 193 bovine serum samples (including two bovine positive control sera) and 70 horse serum samples. The consistency (98.9%) between cELISA and VN results was higher than that (97.4%) between cELISA and IFA for the bovine serum samples. Similarly, for the horse serum samples, the consistency (88.6%) between cELISA and VN results was higher than that (84.3%) between the cELISA and IFA. These findings indicate that our newly developed cELISA can be used for surveillance or epidemiological studies of SFTSV in animals.

Direct Competitive Enzyme-Linked Immunosorbent Assay for Detection of Acrylamide in Food Samples / 分析化学

Due to the low molecular weight and simple structure, the production of specific antibodies against acrylamide is unavailable. In this study, a novel hapten was synthesized through the derivatization of acrylamide and 4-mercaptophenylacetic acid. The hapten was then coupled to carrier protein and used to immunize New Zealand rabbits. Polyclonal antibody which showed specific binding to the acrylamide derivative ( hapten) was obtained. The antibody was labeled with horseradish peroxidase ( HRP) and used to develop a direct competitive enzyme-linked immunosorbent assay ( dc-ELISA) . The dc-ELISA was used to determine the content of acrylamide derivative, and then transferred to the content of acrylamide. The assay showed an IC50 value of 45. 49 μg/L, a limit of detection of 3. 0 μg/L and the linear range of 9. 2-195 μg/L for acrylamide. The recovery of acrylamide from spiked food sample was determined ranging from 83 . 6% to 112 . 7%. Good correlations between the results of dc-ELISA and standard HPLC-MS/MS were obtained. The proposed dc-ELISA is suitable for the determination of acrylamide in food samples.

Identification of the antigenic determinants of human augmenter of liver regeneration (hALR) recognized by its monoclonal antibodies / 中国免疫学杂志

Objective:Identification of the antigenic determinants of hALR.Methods:Theoretic antigenic determinants of hALR was predicted by using Hopp&Wodds method and and Goldkey software package.The four polypeptides according to the amino acid sequences of the predictive linear epitopes of hALR were synthesized and were used to analyze the antigenic determinants of hALR recognized by antibodies.Results:The polypeptides corresponding to residues 6～5,68～80 and 105～112 of hALR were its antigenic determinants.Conclusion:Prediction of the protein antigenic determinants by computer program and detection of them by competitive ELISA with synthesized polypeptides is a useful method of identification of the antigenic determinants.