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Human immunodeficiency virus (HIV)
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Richard Basilan, William Salzer
Laboratory testing for HIV infection involves screening with a highly sensitive test, usually an enzyme-linked immunosor-bent assay (ELISA), also known as enzyme immunoassay, for HIV antibodies. The high sensitivity of the test makes it an effective screening tool, but requires a highly specific assay for confirmatory testing, such as western blot for antibodies to specific viral proteins. Virologic assays (PCR for HIV RNA) can be used for confirmatory testing when the western blot is indeterminate. Testing for HIV RNA by PCR is also used in neonates or when acute HIV infection is suspected. In recent years, multiple rapid tests using blood or saliva have been introduced for point-of-care testing, but it should be noted that all rapid tests require further confirmatory testing because of their high false-positive rate.
Immunological Approaches
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Deborah E. Dixon, Susan J. Steiner, Stanley E. Katz
An assay of this type was described by Wills and Wise [30] for gentamicin. The assay is a homogeneous enzyme immunoassay, meaning that all reactions are carried out in solution, and no phase separation step is required, a step that is necessary in both the enzyme linked immunosorbent assay (ELISA) and RIA. There are a number of important advantages to using this method over the other methods for assaying aminoglycosides in serum. The acetyltransferase method of Broughall and Reeves [30a] is quite good, but requires a scintillation counter. The most commonly used method, the microbial assay, often is inaccurate and usually requires 18 hr to complete. The EMIT system, by comparison, requires less than 0.1 ml of serum and provides results in less than 1 hr. No special or expensive equipment is necessary, and no sample dilution is required, as is in the case of RIA and fluoroimmunoassays. Greater amounts of antiserum are needed for the assay, but it is possible to obtain enough antiserum for 100,000 assay tubes from one rabbit.
Blastomycosis
Published in Rebecca A. Cox, Immunology of the Fungal Diseases, 2020
One of the impediments to serodiagnosis of blastomycosis has been the lack of a suitable antigen. Early studies that employed blastomycin in immunodiffusion or complement-fixing assays generally proved unsatisfactory. Of proven cases, only 50% demonstrated complement-fixing antibody, and many sera also were positive for anti-Histoplasma antibodies.52 The discovery of the A antigen in culture filtrates of Blastomyces yeast cells has provided a useful tool for serodiagnosis. The activity of this antigen is not affected by proteinases, is labile when boiled for 10 min, and is stable for months at 5°C in phosphate buffer.53 In one study using the A antigen, the complement-fixation test was positive (titer > 1:8) in 57% of proven cases and the immunodiffusion test detected 79% of proven cases. The combination of both tests detected 88% of proven cases. Little or no cross-reactions to sera from patients with histoplasmosis or coccidioidomycosis were noted.52 In one study of a small number of sera, the sensitivity of serology was improved to 100% when the A antigen was employed in an indirect enzyme immunoassay.54 That the indirect enzyme immunoassay is the most sensitive serological test for blastomycosis has been reaffirmed in an analysis of an outbreak in Wisconsin.55 The enzyme immunoassay detected 77% of definite and probable cases as compared to 27% and 8% for the immunodiffusion and complement-fixation test, respectively.
Effect of mandarin peel extract on experimentally induced arthritis in male rats
Published in Archives of Physiology and Biochemistry, 2021
Hader I. Sakr, Akef A. Khowailed, Safy S. Gaber, Osama M. Ahmed, Ahmed N. Eesa
Principle: The assay employs the quantitative sandwich enzyme immunoassay technique. Monoclonal antibodies specific for rat TNF-α, IL-1β, IL-4, and IL-10 had been pre-coated onto microplates. Standards, control, and samples were pipetted into the wells and any rat TNF-α, IL-1β, IL-4, and IL-10 present was bound by the immobilised antibody. After washing away any unbound substances, enzyme-linked polyclonal antibodies specific for rat TNF-α, IL-1β, IL-4, and IL-10 were added to the wells. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution was added to the wells. The enzymes reaction yielded a blue product that turned yellow when the stop solution was added. The intensity of the colour measured was in proportion to the amount of rat TNF-α, IL-1β, IL-4, and IL-10 bound in the initial step. The sample values were then read off the standard curve.
Salivary cortisol responses to acute stress vary between allergic and healthy individuals: the role of plasma oxytocin, emotion regulation strategies, reported stress and anxiety
Published in Stress, 2020
L. M. Glenk, O. D. Kothgassner, A. Felnhofer, J. Gotovina, C. L. Pranger, A. N. Jensen, N. Mothes-Luksch, A. Goreis, R. Palme, E. Jensen-Jarolim
Prior to analysis, samples were thawed on ice and centrifuged at room temperature at 3000×g for 15 min to obtain saliva. Aliquots (10 μl of a 1:10 dilution) of clear saliva were used for the analysis of cortisol. Analyses were carried out at the University of Veterinary Medicine in Vienna using a highly sensitive enzyme immunoassay kit. Samples were assayed in duplicates and cortisol concentrations were assessed in a double-antibody biotin-linked enzyme immunoassay (sensitivity of 0.2 ng/ml; Palme & Möstl, 1997). Duplicate samples with a coefficient of variation >10% were replicated and considered in the analysis only when a coefficient of variation <10% was achieved. If sample volumes were below the limit needed to run duplicates or sample volumes were too low before a coefficient of variation <10% was achieved, the sample was dismissed. Average intra- and inter-assay coefficients of variation were less than 10% and 13%, respectively.
Risk factors, management and prevention of transfusion-related acute lung injury: a comprehensive update
Published in Expert Review of Hematology, 2019
Susan A. Kuldanek, Marguerite Kelher, Christopher C. Silliman
Antibody-mediated TRALI requires identification of alloimmunized donors and recipients [129]. Donor workup for the presence of anti-HLA I, anti-HLA II, and anti-HNA antibodies should be undertaken so that these donors are deferred from further donation of plasma rich products [20,32]. As described by the ISBT Working Party on granulocyte Immunobiology, tests for antibodies against HLA class I antigens include: a) enzyme immunoassay, b) flow cytometry with microbeads, c) lymphocytotoxicity, d) lymphocyte immunofluorescence or e) other validated tests; while those assays for antibodies directed against HLA class II antigens rely on only a), b), or e) [129]. Importantly most of the TRALI reactions will be due to donor-derived antibodies to HLA class II antigens not HLA class I which may be absorbed by recipient platelets [130]. The recommendations for HNA antibody detection rely upon the combination of granulocyte immunofluorescence test (GIFT) and the granulocyte agglutination test (GAT) [129]. Ideally, testing for cognate antigen(s) in the recipient should be performed as well [20,32]. For more information please see the ISBT Working Party consensus paper on this topic [129].