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1
Armbruster, D. A., R. H. Schwarzhoff, E. C. Hubster, and M. K. Liserio. "Enzyme immunoassay, kinetic microparticle immunoassay, radioimmunoassay, and fluorescence polarization immunoassay compared for drugs-of-abuse screening." Clinical Chemistry 39, no. 10 (1993): 2137–46. http://dx.doi.org/10.1093/clinchem/39.10.2137.
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Abstract The newest formulation of the Syva EMIT assay for drugs of abuse, EMIT II, and a new immunoassay, OnLine (Roche), utilizing the kinetic interaction of microparticles in solution (KIMS) methodology, RIA tests, and TDx fluorescence polarization immunoassay (FPIA) procedures were compared for marijuana, cocaine, opiates, and barbiturates. Both EMIT II and OnLine immunoassays were performed with a Hitachi 717 analyzer. Calibration curves, the degree of separation between negative and cutoff calibrators, precision, likelihood of carryover from positive to negative samples, and overall ease and speed of analysis were evaluated. RIA and OnLine detected 99% of gas chromatography/mass spectrometry (GC/MS)-confirmed marijuana samples; TDx, 95%; and EMIT II, 88%. All four immunoassays detected approximately 99% of confirmed cocaine-positive urines. RIA, OnLine, and TDx all detected 100% of opiate-confirmed samples; EMIT II, 97%. Barbiturate assays exhibited the greatest disparity, with OnLine and TDx detecting 100% of confirmed positives; EMIT II, 88%; and RIA, 78%. For a variety of reasons, we prefer the fully automated EMIT II and OnLine assays for high-volume urine testing, in comparison with our laboratory's semiautomated RIA tests and the limited-throughput TDx system. The four immunoassays investigated delivered comparable performance in terms of detection rates for GC/MS-confirmed positives for some drugs but not for others.
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Armbruster, D. A., E. C. Hubster, M. S. Kaufman, and M. K. Ramon. "Cloned enzyme donor immunoassay (CEDIA) for drugs-of-abuse screening." Clinical Chemistry 41, no. 1 (1995): 92–98. http://dx.doi.org/10.1093/clinchem/41.1.92.
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Abstract Large numbers of specimens (5000-18,000) were screened for amphetamines, barbiturates, cocaine, marijuana, opiates, and phencyclidine by RIA (Roche), Emit II (Syva), and a new immunoassay, CEDIA (cloned enzyme donor immunoassay, Microgenics). All immunoassays performed equivalently for cocaine, opiates, and phencyclidine. All immunoassays detected the same amphetamine/methamphetamine-positive specimens, but all also detected numerous specimens containing cross-reacting sympathomimetic amines. CEDIA detected 100%, Emit II 93%, and RIA 82% of the barbiturate-positive specimens. Emit II and CEDIA detected 86-88% of the specimens found by RIA to be marijuana positive. A subset of specimens was additionally screened by OnLine (Roche) and TDx (Abbott) for amphetamines, cocaine, and marijuana. OnLine and TDx also detected all of the amphetamine-positive specimens and numerous specimens containing cross-reacting sympathomimetic amines. All immunoassays performed equivalently for cocaine, and the four nonisotopic tests detected 86-89% of the marijuana positives found by RIA. Interfering sympathomimetic amine drug compounds can be eliminated by using an oxidizing agent, thus decreasing the number of unconfirmable amphetamine presumptive positives. The CEDIAs for all of the major drugs of abuse are reliable and effective for large-volume urine screening programs.
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Ehm, M., and A. Kappel. "Immunoassays for diagnosis of coagulation disorders." Hämostaseologie 30, no. 04 (2010): 194–201. http://dx.doi.org/10.1055/s-0037-1619055.
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SummaryImmunoassays play a pivotal role in the clinical laboratory. In the coagulation section of the laboratory, they are used as an aid for diagnosis of deep vein thrombosis or pulmonary embolism, thrombophilia screening, or detection of coagulation factor deficiencies, respectively. Enzyme-linked immunosorbent assay (ELISA) and latex agglutination immunoassay technologies are currently most widely used, while Luminescent Oxygen Channeling Immuno - assay (LOCI®) and other chemiluminescencebased immunoassays are emerging technologies for the coagulation laboratory. However, not all immunoassay technologies employed are compatible with the workflow requirements of the coagulation laboratory, and, not all technologies are suitable for detection or quantification of every marker.This review focuses on technical and performance aspects of those immunoassay technologies that are most widely used in the coagulation laboratory, and provides a description of markers that are typically tested by immunoassays.
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Lukefahr, Ashley, and Barun De. "Laboratory Diagnosis of HIV in the Outpatient Setting: One Hospital’s Perspective." American Journal of Clinical Pathology 152, Supplement_1 (2019): S20—S21. http://dx.doi.org/10.1093/ajcp/aqz112.040.
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Abstract Traditional methods for the diagnosis of human immunodeficiency virus types 1 and 2 (HIV-1, HIV-2) involve initial screening by an immunoassay followed by a specific method Western blot. However, Western blot is not sensitive compared to third-generation immunoassay, which detects both IgG and IgM antibodies against viral envelope proteins causing false-positive results. In addition, neither initial screening nor confirmatory Western blot is capable of detecting acute infection earlier in the disease process, when the virus is more adaptable and highly infectious. To detect both acute and established infection, Abbott Architect platform introduced a new fourth-generation antigen/antibody initial screening assay in 2013. Also, to reduce false-negative results from Western blot, an alternate method Bio-Rad multisport immunoassay was recommended by the Centers for Disease Control and Prevention (CDC) that has higher sensitivity and can differentiate HIV-1 and HIV-2 infections. In 2014, the CDC released updated recommendations for the laboratory diagnosis of HIV. The CDC diagnostic algorithm recommends an initial combination immunoassay that detects HIV-1 and HIV-2 antibodies, followed by supplemental testing with an immunoassay that differentiates HIV-1 and HIV-2 antibodies. Specimens reactive on the initial antigen/antibody immunoassay but nonreactive or indeterminate on the differentiation immunoassay should be followed by nucleic acid testing (NAT) for resolution of this discrepancy. The objective of our study was to review the effect of this updated testing algorithm on HIV testing results in the outpatient setting at Banner University Medical Center–Tucson in Tucson, Arizona. Our study utilized laboratory information system queries to retroactively review all outpatient HIV laboratory testing results obtained from 2013 to 2017. A total of 17,397 HIV-1/2 antigen/antibody immunoassays were performed during this time period. Of the initial antigen/antibody immunoassays, 1.1% were reactive (n = 183). Of these reactive tests, 85% were collected from individuals with established HIV infections (n = 155). HIV-1/HIV-2 antibody differentiation assays were performed on 175 patients, with 86% reactive (n = 150), 2.3% indeterminate (n = 4), and 12% nonreactive (n = 21). Acute HIV-1 infections (antigen/antibody immunoassay reactive, antibody differentiation immunoassay nonreactive or indeterminate, and NAT positive) accounted for 2.7% of patients with reactive initial antigen/antibody immunoassays and 0.03% of all patients screened for HIV infection with the initial antigen/antibody immunoassay (n = 5). Viral loads in the patients with acute HIV-1 infection ranged from 173,000 to >10,000,000 copies/mL. No HIV-2 infections were identified in our patient population. Given that the previous CDC testing algorithm for HIV-1 failed to identify acute HIV-1 infections, our data, which confirm the ability of the current CDC algorithm to detect HIV-1 infections, represent important information for infectious disease practitioners, public health officials, and laboratory directors.
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Kaufman, Bennett M., and Marion Clower. "Immunoassay of Pesticides: An Update." Journal of AOAC INTERNATIONAL 78, no. 4 (1995): 1079–90. http://dx.doi.org/10.1093/jaoac/78.4.1079.
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Abstract Measurement of levels of pesticide residues in foods and crops most often requires extensive cleanup and instrumental techniques such as gas chromatography. Immunoassay measurement techniques, on the other hand, may be used directly on the test portion or require only minimal cleanup. Further refinements of the common antibody–enzyme-based solid-phase assays, such as use of coated magnetic particles, antibody-coated crystals, and continuous-flow devices, have extended the measurement range and applicability of these assays. Likewise, new immunoassays for pesticides have been developed, and existing assays have been refined, optimized, and more completely characterized and validated. In addition to their ability to accurately and reliably measure amounts of residues present in food and crops, immunoassays can be readily used as rapid screening methods for contaminants in field samples. We have previously reviewed much of the work in the area of pesticide immunoassay; this report updates previous information and discusses some new immunoassay techniques.
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Dawood, Sadia, Ayesha Hafeez, Aamir Ijaz, Summera Moeen, Asif Ali Memon, and Sumaira Mubarik. "DIAGNOSTIC ACCURACY OF DRUG SCREENING IMMUNOASSAYS IN DRUG FACILITATED CRIMES." PAFMJ 71, no. 1 (2021): 101–06. http://dx.doi.org/10.51253/pafmj.v71i1.3167.
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Objective: To determine the diagnostic accuracy of immunoassays in drug screening as required in emergency for the rapid diagnosis of drug intoxication in travel related crimes.
 Study Design: Diagnostic accuracy study.
 Place and Duration of Study: department of Chemical Pathology and Endocrinology, Armed Forces Institute ofPathology, Rawalpindi Pakistan, from Jul 2017 to Jun 2018.
 Methodology: Sealed urine specimens of 77 patients with history of suspected intoxication in drugs facilitatedstreet crimes, received for toxicology screening were included in the study. All the specimens were analysed,initially on immunoassay (index test) and then on Triple Quadrupole Liquid chromatography–Mass spectrometry (reference standard). Benzodiazepine being the main class of drugs involved in travel related crimes, diagnostic accuracy of immunoassay technique was assessed for these by calculating its sensitivity, specificity, positive predictive value and negative predictive value.
 Results: Victims were predominantly males and public transportation was the most common mode of transport. The most commonly used drug was Lorazepam. Immunoassay failed to detect few cases who were shown to be intoxicated with benzodiazepines by liquid-chromatography tandem mass spectrometry. The false negative rate was 4.9%. Only one false positive case was observed. The accuracy was calculated to be 94.8% with sensitivity of 95.08% and specificity of 93.7%.
 Conclusion: Immunoassay was found reliable for rapid testing in drug facilitated intoxication cases. Howevercritical decision making should be done cautiously keeping in mind the limitations associated with thesescreening procedures.
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Lin, Yen-Heng, Chih-Ching Wu, Wan-Ling Chen, and Kai-Ping Chang. "Anti-p53 Autoantibody Detection in Automatic Glass Capillary Immunoassay Platform for Screening of Oral Cavity Squamous Cell Carcinoma." Sensors 20, no. 4 (2020): 971. http://dx.doi.org/10.3390/s20040971.
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The incidence of oral squamous cell carcinoma (OSCC), which is one of the most common cancers worldwide, has been increasing. Serum anti-p53 autoantibody is one of the most sensitive biomarkers for OSCC. Currently, the most commonly used method on clinical screening platforms is the enzyme-linked immunosorbent assay, owing to its high specificity and repeatability. However, conducting immunoassays on 96-well plates is typically time consuming, thereby limiting its clinical applications for fast diagnosis and immediate prognosis of rapidly progressive diseases. The present study performed immunoassays in glass capillaries of 1-mm internal diameter, which increases the surface to volume ratio of the reaction, to shorten the time needed for immunoassay. The immunoassay was automated while using linear motorized stages and a syringe pump. The results indicated that, when compared with the 96-well plate immunoassay, the glass capillary immunoassay decreased the reaction time from typical 120 min to 45 min, reduced the amount of reagent from typical 50 µL to 15 µL, and required only simple equipment setup. Moreover, the limit of detection for glass capillary anti-p53 autoantibody immunoassay was 0.46 ng mL−1, which is close to the 0.19 ng mL−1 value of the conventional 96-well plate assay, and the glass capillary method had a broader detection range. The apparatus was used to detect the serum anti-p53 autoantibody concentration in clinical patients and compare its results with the conventional 96-well plate method results, which suggested that both of the methods detect the same trend in the relative concentration of serum anti-p53 autoantibody in healthy individuals or patients with OSCC.
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Rossi, Brian, Francesca Freni, Claudia Vignali, et al. "Comparison of Two Immunoassay Screening Methods and a LC-MS/MS in Detecting Traditional and Designer Benzodiazepines in Urine." Molecules 27, no. 1 (2021): 112. http://dx.doi.org/10.3390/molecules27010112.
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Sensitive and specific immunoassay screening methods for the detection of benzodiazepines in urine represent an important prerequisite for routine analysis in clinical and forensic toxicology. Moreover, emerging designer benzodiazepines force labs to keep their methodologies updated, in order to evaluate the reliability of the immunochemical techniques. This study aimed at evaluating the sensitivity and specificity of two different immunoassay methods for the detection of benzodiazepines in urine, through a comparison with the results obtained by a newly developed liquid chromatographic tandem mass spectrometric (LC-MS/MS) procedure. A cohort of authentic urine samples (N = 501) were processed, before and after a hydrolysis procedure, through two immunoassays and an LC-MS/MS method. The LC-MS/MS target procedure was optimized for monitoring 25 different molecules, among traditional and designer benzodiazepines, including some metabolites. At least one of the monitored substances was detected in 100 out of the 501 samples. A good specificity was observed for the two immunoassays (>0.99), independently of the cut-offs and the sample hydrolysis. The new kit demonstrated a fairly higher sensitivity, always higher than 0.90; in particular, a high cross-reactivity of the new immunoassay was observed for samples that tested positive for lorazepam and 7-aminoclonazepam. The two immunoassays appeared adequate to monitor not only traditional benzodiazepines but also new designer ones.
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Luzzi, Veronica I., Al N. Saunders, John W. Koenig, et al. "Analytic Performance of Immunoassays for Drugs of Abuse Below Established Cutoff Values." Clinical Chemistry 50, no. 4 (2004): 717–22. http://dx.doi.org/10.1373/clinchem.2003.028878.
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Abstract Background: The analytic performance and accuracy of drug detection below Substance Abuse and Mental Health Services Administration (SAMHSA) cutoffs is not well known. In some patient populations, clinically significant concentrations of abused drugs in urine may not be detected when current SAMHSA cutoffs are used. Our objectives were to define the precision profiles of three immunoassay systems for drugs of abuse and to evaluate the accuracy of testing at concentrations at which the CV was <20%. Methods: Drug-free urine was supplemented with analytes to assess the precision in three commercial drugs-of-abuse immunoassay systems below the SAMHSA-dictated cutoffs for amphetamines, opiates, benzoylecgonine, phencyclidine, and cannabinoids. Consecutive urine samples with signals associated with a CV <20% by Emit® immunoassay and below SAMHSA cutoffs were then subjected to confirmatory analysis. Results: The CV of all immunoassay systems tested remained <20% to drug concentrations well below SAMHSA cutoffs. The accuracy of urine drug-screening results between the SAMHSA-specified cutoffs and the precision-based cutoffs was less than accuracy for specimens above the SAMHSA cutoffs, but the use of the precision-based cutoff produced a 15.6% increase in the number of screen-positive specimens and a 7.8% increase in the detection of specimens that yielded positive results on confirmatory testing. Conclusion: The precision of three commercial immunoassay systems for drugs-of-abuse screening is adequate to detect drugs below SAMHSA cutoffs. Knowledge of the positive predictive values of screening immunoassays at lower cutoff concentrations could enable efficient use of confirmatory testing resources and improved detection of illicit drug use.
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Emerson, Jane F., Gilda Ngo, and Scott S. Emerson. "Screening for Interference in Immunoassays." Clinical Chemistry 49, no. 7 (2003): 1163–69. http://dx.doi.org/10.1373/49.7.1163.
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Abstract Background: The presence of interfering substances in patient samples submitted for immunoassay cannot be reliably anticipated. We therefore evaluated three interference screening techniques and estimated the prevalence of interfering substances as defined by positive outcomes with these protocols. Methods: We evaluated 160 samples for the presence of substances that may interfere with four immunoassays (40 samples for each): thyroid-stimulating hormone, prostate-specific antigen, β-human chorionic gonadotropin, and cortisol. Interference was defined by nonlinear responses with serial dilution, discrepant results after pretreatment with heterophile blocking reagent (HBR), and positive reactions on a mouse-antibody-negative control reaction (Tandem ICON® ImmunoConcentration HCG). Criteria for declaring significant discrepant results were based on a Z-score computed using the assay CV. The McNemar test was used to compare the prevalence of discrepancies across the three screening techniques. The association between type of immunoassay and prevalence of discrepant results was determined by a modified Pearson χ2 statistic. Results: Five of the 160 samples [3.1%; 95% confidence interval (CI), 1.0–7.1%] screened positive with the ICON. Seventy-two of the 148 samples with informative serial dilutions (48.6%; 95% CI, 40.4–57.0%) had at least one discrepant result at higher dilutions. After pretreatment with HBR, 53 of the 140 samples (38%; 95% CI, 29.8–46%) were discrepant. Only 48 of the 140 samples with informative measurements for all three screening techniques (34%; 95% CI, 26–43%) were negative by all three. The prevalence of positive screens varied significantly by type of immunoassay (P <0.0001) for both HBR and serial dilution. Only 3% (0.8–7%) of the samples tested with HBR showed a change from normal to abnormal or the reverse after treatment. Conclusions: Introducing a protocol based on any of these three techniques into the immunochemistry laboratory to prescreen for interfering substances is not warranted. The evaluation of specimens for the presence of interfering anti-animal antibodies should be reserved for cases in which clinical history or suspicious results indicate the need.
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Tesfazghi, Merih T., Rick Bardelmeier, Al N. Saunders, Sarah M. Riley, Stephen M. Roper, and Dennis J. Dietzen. "Development and Implementation of One-Step, Broad-Spectrum, High-Sensitivity Drug Screening by Tandem Mass Spectrometry in a Pediatric Population." Journal of Applied Laboratory Medicine 7, no. 2 (2022): 409–20. http://dx.doi.org/10.1093/jalm/jfab157.
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Abstract Background Drug screening by immunoassay is common in pediatric populations. However, false-positive and -negative results due to antibody cross-reactivity and dilute urine are frequent and underappreciated. Accurate ascertainment of drug exposure in children has significant clinical and medico-legal consequences. Design and Methods We developed and characterized an LC–MS/MS drug screening assay to supplant immunoassay and detect 38 compounds at the lowest concentrations distinguishable from analytic noise. Once implemented, we conducted a retrospective analysis of 3985 pediatric urine drug screens performed a year before (n = 1663) and after (n = 2322) implementation to examine the frequency and breadth of drug detection in our pediatric population. Results Using immunoassay, 23% (293/1269) of samples from the general pediatric and 37% (147/394) of nursery populations had presumptively positive results. Of the presumptive positive compounds, 85% (288/338) from the general pediatric population and 40% (65/162) from the nursery cohort were confirmed by mass spectrometry. After LC–MS/MS implementation, 31% (628/2052) of general pediatric, and 18% (48/270) of the nursery samples were positive for 1 or more compounds. In the nursery population, immunoassays over-detected the presence of THC but under-detected exposure to cocaine. Conclusion A broadly targeted, analytically sensitive LC–MS/MS drug screening assay detects a larger number and variety of compounds in a single step compared to a screen-then-confirm approach initiated by immunoassay in our pediatric population. Rapid delivery of accurate results enables timely, appropriate disposition of patients in a variety of settings including the emergency department and labor/delivery.
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Chen, Zijian, Wei-Xuan Huang, Hongwu Wang, Meiling Zhang, Kai Chen, and Hao Deng. "Development of a Dual-Readout Multicolor Immunoassay for the Rapid Analysis of Isocarbophos in Vegetable and Fruit Samples." Foods 13, no. 24 (2024): 4057. https://doi.org/10.3390/foods13244057.
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Multicolor immunoassay is a powerful tool for rapid analysis without the use of bulky instruments owing to various color conversions, which is suitable for on-site visual analysis for pesticides. Herein, this study developed a multicolor immunoassay for the rapid detection of isocarbophos. After competitive immunoassay, the secondary antibody (GAM-ALP) catalyzed ascorbyl-2-phosphate (AAP) into ascorbic acid (AA). The AA can reduce K3[Fe(CN)6] into K4[Fe(CN)6]. The latter can react with Fe3+ to form Prussian blue; otherwise, the orange AAP-Fe3+ complex was generated. Therefore, the multicolor immunoassay achieved a color conversion of orange–green–blue in response to isocarbophos, allowing for rapid semiquantitative analysis by the naked eye. After parameter optimization, the multicolor immunoassay was developed depending on the ratiometric absorbance between the Prussian blue and AAP-Fe3+ complex. Moreover, a smartphone was used to measure the RGB value of the color conversion for the development of portable visual, quantitative analysis. Both the absorbance-based and RGB-based multicolor immunoassays showed good accuracy and practicability in the recovery test. This study provided a common approach for the development of dual-readout multicolor immunoassay, which can be used for on-site rapid screening by quantitative or visual semiquantitative analysis.
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Chin, Julia D., Michael A. Quilliam, J. Marc Fremy, Sushil K. Mohapatra, and Hanna M. Skorska. "Screening for Okadaic Acid by Immunoassay." Journal of AOAC INTERNATIONAL 78, no. 2 (1995): 508–13. http://dx.doi.org/10.1093/jaoac/78.2.508.
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Abstract Increasing incidences of phytoplankton blooms with the potential danger of toxin release into the food chain have necessitated the search for new diagnostic methods that can detect toxins quickly and reliably. A competitive enzymelinked immunosorbent assay (ELISA) was developed to quantitate okadaic acid in shellfish and phytoplankton extracts. To determine the specificity of the assay, a number of toxins, such as calyculin A, brevetoxin-1, and dinophysistoxins-1, -2, and -3 were analyzed. Both dinophysistoxins-2 and -1 could be detected by the assay but in concentration ranges 10- and 20-fold higher than that for okadaic acid, respectively. Dinophysistoxin-3, calyculin A, or brevetoxin-1 could not be detected with this assay. To validate the accuracy of the method, 18 mussel and 7 phytoplankton extracts were analyzed in parallel for okadaic acid content by ELISA and liquid chromatography combined with either fluorescence or mass spectrometric detection. Very high correlation between the results was found.
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Sadeg, Nouredine, Gilles François, Brigitte Petit, Hélène Dutertre-Catella, and Michel Dumontet. "Automated liquid-chromatographic analyzer used for toxicology screening in a general hospital: 12 months’ experience." Clinical Chemistry 43, no. 3 (1997): 498–504. http://dx.doi.org/10.1093/clinchem/43.3.498.
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Abstract We evaluated the clinical utility of an automated HPLC system (Remedi, Bio-Rad) for identification of drugs and metabolites in biological fluids. Serum or urine or both from 354 consecutive cases of poisoning were analyzed by the system and by a set of fluorescence polarization immunoassay (FPIA, Abbott) and thin-layer chromatographic (TLC) procedures. Antidepressants and most phenothiazines were recognized by the new system. Comparison of Remedi results with final clinical diagnoses yielded diagnostic specificity and sensitivity of 80% and 90%, respectively. Remedi detected 26 additional compounds that were neither reactive in the immunoassay screening tests nor detected by TLC procedures. Because the Remedi expands the range of drugs covered by the immunoassays and provides a rapid, preliminary report in emergency situations, we conclude that this system can be a useful complementary technique in the clinical toxicology laboratory. Although urine toxicological screening seemed adequate for a good toxicological report, blood analysis allows extra toxicokinetic data such as blood concentrations and half-life estimations.
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Leclercq, Marion, Marion Soichot, Brigitte Delhotal-Landes, et al. "False positive amphetamines and 3,4-methylenedioxymethamphetamine immunoassays in the presence of metoprolol—two cases reported in clinical toxicology." Journal of Analytical Toxicology 44, no. 2 (2019): 200–205. http://dx.doi.org/10.1093/jat/bkz051.
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Abstract Amphetamines, frequently used recreational drugs with high risk of toxicity, are commonly included in urine drug screens. This screening is based on enzyme immunoassay, which is a quick and easy-to-perform technique, but may lack specificity resulting from cross-reactivity with other compounds, causing false positive results. We present two cases of presumed false positive MULTIGENT® amphetamine/methamphetamine and MULTIGENT® ecstasy (Abbott®) immunoassays with the beta-blocker metoprolol. Both metoprolol-poisoned patients presented positive urine screening despite no history of drug abuse. No confirmation for amphetamine molecular structures was found with gas chromatography–mass spectrometry. The cross-reactivity was further investigated by doping urine samples with metoprolol and its two major phase-I metabolites. Metoprolol showed positive results for both amphetamine and MDMA tests at low concentrations (200 and 150 μg/mL, respectively). Metoprolol metabolites cross-reacted with the amphetamines immunoassay only, but at higher concentrations (i.e., 2000 μg/mL for α-hydroxymetoprolol and 750 μg/mL for O-demethylmetoprolol). In conclusion, false positive results in amphetamines and MDMA immunoassays are possible in the presence of metoprolol. Toxicologists should be aware of frequent analytical interferences with immunoassays and a detailed medication history should be taken into consideration for interpretation. In vitro investigation of suspected cross-reactivity should include not only the parent drug but also its related metabolites.
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RONALD, A., and W. H. STIMSON. "The evolution of immunoassay technology." Parasitology 117, no. 7 (1999): 13–27. http://dx.doi.org/10.1017/s0031182099004989.
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Since they were first utilized, immunoassays have witnessed phenomenal growth in the range and scope of their applications. A vast array of different labels and assay strategies has been developed to meet the requirements of sensitivity, accuracy and convenience. The development of increasingly sensitive labels and detection equipment has seen a drastic improvement in the sensitivity of immunoassay systems, allowing an ever-increasing range of analytes to be measured accurately. At the same time, simple to use, inexpensive assay systems have been developed with the necessary reliability, accuracy and sensitivity to bring immunoassay technology to much more diverse areas such as home testing, near-patient monitoring, and large screening programmes in developing countries. Recent developments in molecular biology techniques have made possible the production of fusion antibody conjugates, which can lead to further improvements in sensitivity and cost of reagents, as well as possibly revolutionizing the production of monoclonal antibodies. However, dissatisfaction with various aspects of existing immunoassay technology will necessarily lead to the continued development of this already widely diverse subject.
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Saleem, Mohamed, Helen Martin, Anne Tolya, and Penny Coates. "Do all screening immunoassay positive buprenorphine samples need to be confirmed?" Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 54, no. 6 (2017): 707–11. http://dx.doi.org/10.1177/0004563216688489.
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Background Interference from opiates in the Microgenics CEDIA® Buprenorphine assay is known to produce false-positive buprenorphine screening immunoassay results necessitating confirmatory buprenorphine testing by chromatography/mass spectrometry methods. Method We reviewed data on falsely positive buprenorphine immunoassay screen (cut-off ≥ 5 µg/L) but negative for buprenorphine by gas chromatography mass spectrometry (cut-off ≥ 5 µg/L) and had a positive opiate immunoassay result (cut-off ≥ 300 µg/L). The results were collected over three months, and the data were evaluated to determine whether there is an opiate immunoassay screen concentration below which a false-positive buprenorphine result will not occur. Results We found that cross-reactivity in the CEDIA® buprenorphine immunoassay by opiates at concentrations <2000 µg/L will not cause a false-positive buprenorphine result. After changing our practice to not proceed with confirmatory buprenorphine gas chromatography mass spectrometry assay when the opiate screening concentration is below an even more conservative cut-off of <1500 µg/L, we estimate a potential cost-saving of AU$ 17,810 per year without compromising clinical care. Conclusion Samples with CEDIA® opiate immunoassay result <2000 µg/L and a positive CEDIA® buprenorphine immunoassay screen do not require confirmatory testing for buprenorphine.
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Melanson, Stacy. "KIMS, CEDIA, and HS-CEDIA Immunoassays Are Inadequately Sensitive for Detection of Benzodiazepines in Urine from Patients Treated for Chronic Pain." Pain Physician 4;17, no. 4;7 (2014): 259–66. http://dx.doi.org/10.36076/ppj.2014/17/259.
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Background: Patients treated for chronic pain may frequently undergo urine drug testing to monitor medication compliance and detect undisclosed prescribed or illicit drug use. Due to the increasing use and abuse of benzodiazepines, this class of medications is often included in drug screening panels. However, immunoassay-based methods lack the requisite sensitivity for detecting benzodiazepine use in this population primarily due to their poor cross-reactivity with several major urinary benzodiazepine metabolites. A High Sensitivity Cloned Enzyme Donor Immunoassay (HS-CEDIA), in which betaglucuronidase is added to the reagent, has been shown to perform better than traditional assays, but its performance in patients treated for chronic pain is not well characterized. Objectives: To determine the diagnostic accuracy of HS-CEDIA, as compared to the Cloned Enzyme Donor Immunoassay (CEDIA) and Kinetic Interaction of Microparticles in Solution (KIMS) screening immunoassays and liquid chromatography-tandem mass spectrometry (LC-MS/MS), for monitoring benzodiazepine use in patients treated for chronic pain. Study Design: A study of the diagnostic accuracy of urine benzodiazepine immunoassays. Setting: The study was conducted at an academic tertiary care hospital with a clinical laboratory that performs urine drug testing for monitoring medication compliance in pain management. Methods: A total of 299 urine specimens from patients treated for chronic pain were screened for the presence of benzodiazepines using the HS-CEDIA, CEDIA, and KIMS assays. The sensitivity and specificity of the screening assays were determined using the LC-MS/MS results as the reference method. Results: Of the 299 urine specimens tested, 141 (47%) confirmed positive for one or more of the benzodiazepines/metabolites by LC-MS/MS. All 3 screens were 100% specific with no false-positive results. The CEDIA and KIMS sensitivities were 55% (78/141) and 47% (66/141), respectively. Despite the relatively higher sensitivity of the HS-CEDIA screening assay (78%; 110/141), primarily due to increased detection of lorazepam, it still missed 22% (31/141) of benzodiazepine-positive urines. The KIMS, CEDIA, and HS-CEDIA assays yielded accuracies of 75%, 79%, and 90%, respectively, in comparison with LC-MS/MS. Limitations: This study was limited by its single-site location and the modest size of the urine samples utilized. Conclusions: While the HS-CEDIA provides higher sensitivity than the KIMS and CEDIA assays, it still missed an unacceptably high percentage of benzodiazepine-positive samples from patients treated for chronic pain. LC-MS/MS quantification with enzymatic sample pretreatment offers superior sensitivity and specificity for monitoring benzodiazepines in patients treated for chronic pain. Key words: High sensitivty immunoassay, benzodiazepine, beta-glucoronidase, pain management, compliance, LC-MS/MS, screening
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Brown, E. N., T. J. McDermott, K. J. Bloch, and A. D. McCollom. "Defining the smallest analyte concentration an immunoassay can measure." Clinical Chemistry 42, no. 6 (1996): 893–903. http://dx.doi.org/10.1093/clinchem/42.6.893.
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Abstract An immunoassay's minimal detectable concentration (MDC), the smallest analyte concentration the assay can reliably measure, is one of its most important properties. Bayes' theorem is used to unify the five current mathematical MDC definitions. The unified definition has significant implications for defining positive results for screening and diagnostic tests, setting criteria for immunoassay quality control and optimal design, reliably measuring biological substances at low concentrations, and, in general, measuring small analyte concentrations with calibrated analytic methods. As an illustration, we apply the unified definition to the microparticle capture enzyme immunoassay for prostate-specific antigen (PSA) developed for the Abbott IMx automated immunoassay system. The MDC of this assay as estimated by our unifying approach is shown to be 4.1-7.1 times greater than currently reported. As a consequence, the ability of the assay to measure reliably small concentrations of PSA to detect early recurrences of prostate cancer is probably overstated.
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de Hora, Mark R., Natasha L. Heather, Tejal Patel, Lauren G. Bresnahan, Dianne Webster, and Paul L. Hofman. "Measurement of 17-Hydroxyprogesterone by LCMSMS Improves Newborn Screening for CAH Due to 21-Hydroxylase Deficiency in New Zealand." International Journal of Neonatal Screening 6, no. 1 (2020): 6. http://dx.doi.org/10.3390/ijns6010006.
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The positive predictive value of newborn screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency was <2% in New Zealand. This is despite a bloodspot second-tier immunoassay method for 17-hydroxyprogesterone measurement with an additional solvent extract step to reduce the number of false positive screening tests. We developed a liquid chromatography tandem mass spectrometry (LCMSMS) method to measure 17-hydroxyprogesterone in bloodspots to replace our current second-tier immunoassay method. The method was assessed using reference material and residual samples with a positive newborn screening result. Correlation with the second-tier immunoassay was determined and the method was implemented. Newborn screening performance was assessed by comparing screening metrics 2 years before and 2 years after LCMSMS implementation. Screening data analysis demonstrated the number of false positive screening tests was reduced from 172 to 40 in the 2 years after LCMSMS implementation. The positive predictive value of screening significantly increased from 1.71% to 11.1% (X2 test, p < 0.0001). LCMSMS analysis of 17OHP as a second-tier test significantly improves screening specificity for CAH due to 21-hydroxylase deficiency in New Zealand.
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West, Cameron. "An Evaluation of the Diagnostic Accuracy of Liquid Chromatography-Tandem Mass Spectrometry Versus Immunoassay Drug Testing in Pain Patients." Pain Physician 3;13, no. 3;5 (2010): 273–81. http://dx.doi.org/10.36076/ppj.2010/13/273.
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Background: Immunoassay screening is used by pain physicians to determine compliance with controlled substances. Because clinical use of pain medications is different from illicit drug use, there is a need to evaluate the level of diagnostic accuracy of this procedure for the pain patient. Objective: To compare the results of automated screening by immunoassay with analysis by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) in identifying pain patients using illicit drugs and pain patients excreting low concentrations of their prescribed medications. Study Design: A diagnostic accuracy study. Methods: Urine samples from 4,200 pain patients were tested by immunoassay and LCMS/MS for the following drugs and metabolites: Amphetamine, Methamphetamine, Alphahydroxyalprazolam, Lorazepam, Nordiazepam, Oxazepam, Temazepam, Cannabinoids, Cocaine, Methadone, Methadone Metabolite, Codeine, Hydrocodone, Hydromorphone, Morphine, Propoxyphene, and Norpropoxyphene. Results: In a number of patients negative immunoassay findings were superseded by positive results on analysis by Mass Spectrometry. These were termed false negative results. The greatest failures were for the benzodiazepines (28%) and for cocaine (50%). Limitations: The study was limited by the lack of complete demographics for the cohort and because only one immunoassay diagnostic product was used. It was also limited because not all drugs react the same in the immunoassay. Conclusions: We show that in general, immunoassay screening results are accurate, although as shown in this study there are many false negative observations. The use of LC-MS/MS technology significantly decreases the number of false negative results. Key words: Drug abuse, illicit drug use, opioids, illicit drugs, benzodiazepines, false negatives, liquid chromatography-mass spectrometry, immunoassay, adherence monitoring
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BENSON, CONSTANCE A. "Enzyme Immunoassay Screening for Hepatitis B Immunization." Annals of Internal Medicine 104, no. 5 (1986): 730. http://dx.doi.org/10.7326/0003-4819-104-5-730_2.
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Jaskowski, Troy D., Carl Schroder, Thomas B. Martins, C. Lars Mouritsen, Christine M. Litwin, and Harry R. Hill. "Screening for Antinuclear Antibodies by Enzyme Immunoassay." American Journal of Clinical Pathology 105, no. 4 (1996): 468–73. http://dx.doi.org/10.1093/ajcp/105.4.468.
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Sakai, Ruriko, Masahiro Osako, Yukihiro Yoshida, Naoki Haga, Kiyoshi Iwashima, and Masaru Tanaka. "Screening Studies on Dioxin Using Enzyme Immunoassay." Journal of the Japan Society of Waste Management Experts 8, no. 7 (1997): 311–20. http://dx.doi.org/10.3985/jswme.8.311.
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Jin, Kai, Ping Zhao, Wenhui Fang, et al. "An Impedance Sensor in Detection of Immunoglobulin G with Interdigitated Electrodes on Flexible Substrate." Applied Sciences 10, no. 11 (2020): 4012. http://dx.doi.org/10.3390/app10114012.
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Immunoassay plays an important role in the early screening and diagnosis of diseases. The use of electrochemical methods to realize the label-free, specific and rapid detection of antigens has attracted extensive attention from researchers. In this study, we realized the function of immunosensing and detection by lithography, the interdigitated gold electrode on the polyethylene naphthalate (PEN) membrane. Then, the gold electrode was biofunctionalized and the characterization was verified by atomic force microscopy, which was finally for the detection of mice IgG. This immunosensor has a low detection limit, with a broad linear detection range of 0.01–10 ng/mL. The results show that the electrochemical impedance sensor made of metal electrodes based on PEN flexible materials is suitable for immunoassay experiments. If this method could be proved by further studies, broad application prospects can be seen in routine immunoassays.
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Rhoads, Daniel D., Jonathan R. Genzen, Christine P. Bashleben, James D. Faix, and M. Qasim Ansari. "Prevalence of Traditional and Reverse-Algorithm Syphilis Screening in Laboratory Practice: A Survey of Participants in the College of American Pathologists Syphilis Serology Proficiency Testing Program." Archives of Pathology & Laboratory Medicine 141, no. 1 (2016): 93–97. http://dx.doi.org/10.5858/2016-0110-cp.
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Context.—Syphilis serology screening in laboratory practice is evolving. Traditionally, the syphilis screening algorithm begins with a nontreponemal immunoassay, which is manually performed by a laboratory technologist. In contrast, the reverse algorithm begins with a treponemal immunoassay, which can be automated. The Centers for Disease Control and Prevention has recognized both approaches, but little is known about the current state of laboratory practice, which could impact test utilization and interpretation. Objective.—To assess the current state of laboratory practice for syphilis serologic screening. Design.—In August 2015, a voluntary questionnaire was sent to the 2360 laboratories that subscribe to the College of American Pathologists syphilis serology proficiency survey. Results.—Of the laboratories surveyed, 98% (2316 of 2360) returned the questionnaire, and about 83% (1911 of 2316) responded to at least some questions. Twenty-eight percent (378 of 1364) reported revision of their syphilis screening algorithm within the past 2 years, and 9% (170 of 1905) of laboratories anticipated changing their screening algorithm in the coming year. Sixty-three percent (1205 of 1911) reported using the traditional algorithm, 16% (304 of 1911) reported using the reverse algorithm, and 2.5% (47 of 1911) reported using both algorithms, whereas 9% (169 of 1911) reported not performing a reflex confirmation test. Of those performing the reverse algorithm, 74% (282 of 380) implemented a new testing platform when introducing the new algorithm. Conclusion.—The majority of laboratories still perform the traditional algorithm, but a significant minority have implemented the reverse-screening algorithm. Although the nontreponemal immunologic response typically wanes after cure and becomes undetectable, treponemal immunoassays typically remain positive for life, and it is important for laboratorians and clinicians to consider these assay differences when implementing, using, and interpreting serologic syphilis screening algorithms.
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Benn, Peter A., Gregory S. Makowski, James FX Egan, and Dave Wright. "Reproducibility of Risk Figures in 2nd-Trimester Maternal Serum Screening for Down Syndrome: Comparison of 2 Laboratories." Clinical Chemistry 52, no. 11 (2006): 2087–94. http://dx.doi.org/10.1373/clinchem.2006.068783.
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Abstract Background: Analytical error affects 2nd-trimester maternal serum screening for Down syndrome risk estimation. We analyzed the between-laboratory reproducibility of risk estimates from 2 laboratories. Methods: Laboratory 1 used Bayer ACS180 immunoassays for α-fetoprotein (AFP) and human chorionic gonadotropin (hCG), Diagnostic Systems Laboratories (DSL) RIA for unconjugated estriol (uE3), and DSL enzyme immunoassay for inhibin-A (INH-A). Laboratory 2 used Beckman immunoassays for AFP, hCG, and uE3, and DSL enzyme immunoassay for INH-A. Analyte medians were separately established for each laboratory. We used the same computational algorithm for all risk calculations, and we used Monte Carlo methods for computer modeling. Results: For 462 samples tested, risk figures from the 2 laboratories differed &gt;2-fold for 44.7%, &gt;5-fold for 7.1%, and &gt;10-fold for 1.7%. Between-laboratory differences in analytes were greatest for uE3 and INH-A. The screen-positive rates were 9.3% for laboratory 1 and 11.5% for laboratory 2, with a significant difference in the patients identified as screen-positive vs screen-negative (McNemar test, P &lt;0.001). Computer modeling confirmed the large between-laboratory risk differences. Conclusion: Differences in performance of assays and laboratory procedures can have a large effect on patient-specific risks. Screening laboratories should minimize test imprecision and ensure that each assay performs in a manner similar to that assumed in the risk computational algorithm.
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Badia, Roser, Rafael de la Torre, Sergio Corcione, and Jordi Segura. "Analytical approaches of European Union laboratories to drugs of abuse analysis." Clinical Chemistry 44, no. 4 (1998): 790–99. http://dx.doi.org/10.1093/clinchem/44.4.790.
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Abstract We report a survey on urine drug testing within a total of 269 laboratories of the European Union. Clinical laboratories predominated over forensic laboratories (59.5% vs 28.5%). Screening without identification/quantification was the common approach used by clinical laboratories, whereas screening with identification/quantification was the approach used by almost all forensic laboratories. Screening was primarily performed by immunoassay in both types of laboratories. Gas chromatography coupled to mass spectrometry was the main analytical method used for specific identification/quantification of drugs, but other methods (including immunoassays) were also used. Cutoff values applied varied by laboratory type, country, and method used. A high percentage of laboratories did not use or report cutoff values. Overall, countries of the European Union vary significantly in regards to drugs tested, analytical approach, and screening and identification cutoff values. It is recommended to clearly state the analytical method and the cutoff values used when reporting results for drugs of abuse testing.
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Pierre, Christina, Catherine Gineste, and Lindsay Bazydlo. "A Kratom Metabolite Causes False Positive Urine Drug Screening Results for Methadone." American Journal of Clinical Pathology 154, Supplement_1 (2020): S19—S20. http://dx.doi.org/10.1093/ajcp/aqaa137.035.
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Abstract Background The synthetic opioid methadone is utilized in pain management and opioid addiction therapy. Patients with methadone prescriptions are monitored for compliance using immunoassay-based urine drug screens (UDS) for methadone and its primary metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP). It is well documented that immunoassays are subject to false positive results due to cross-reactivity of antibody reagents with structurally related and unrelated compounds. A 30-year-old male with a history of polysubstance abuse presented to the emergency department with altered mental status and was noted to have a positive UDS for EDDP. Reflex mass spectrometry testing was negative for both methadone and EDDP. Upon improvement, the patient endorsed use of powder derived from the tropical plant Kratom, whose main components, mitragynine and 7-hydroxymitragynine, function as opioid receptor agonists. Kratom use has become popularized in the United states in spite of warnings by the United States Food and Drug Administration about its potential to cause addiction, abuse, and dependence. Here we describe our investigation of Kratom as a positive interferent in the Thermo Scientific CEDIA Methadone Metabolite (EDDP) immunoassay. Methods Patient specimens that underwent urine drug screens as part of routine clinical care at the University of Virginia Health System over 3 non-contiguous months meeting the following criteria were included in the study: EDDP screen ≥10 arbitrary absorbance units, negative methadone screen, and negative methadone or EDDP mass spectrometry confirmation (if available). Urine drug screens were performed on the Olympus AU480 Chemistry Analyzer using the Thermo Scientific CEDIA Methadone Metabolite (EDDP) immunoassay and the Siemens Syva Emit II Plus Methadone assay. Specimens were tested for mitragynine, 7-hydroxymitragynine, methadone and EDDP using the Sciex X500R QTOF with Sciex Exion Liquid Chromatography. Results A total of 48 specimens met the inclusion criteria, where 50% (24/48) confirmed positive for mitragynine and/or 7-hydroxymitragynine and negative for methadone/ EDDP. Methadone and/or EDDP was detected in 33% (16/48), none of which confirmed positive for mitragynine or 7-hydroxymitragynine and 17% were negative for all four analytes. Urine spiked with a methanol extract prepared from Kratom powder produced no signal in the EDDP screen. Spiking drug-free urine with 10,000 ng/mL mitragynine and 10,000 ng/mL 7-hydroxymitragynine both resulted in indeterminate EDDP screens. Since several drugs are glucuronidated during phase II metabolism we performed enzymatic hydrolysis on urine specimens and rescreened the specimens using the EDDP immunoassay. Upon hydrolysis, mitragynine and/or 7-hydroxymitragynine positive specimens showed a significantly higher percent increase in absorbance on the EDDP screen compared to those in which methadone and/or EDDP was detected (p=0.0031). Conclusion Our studies suggest that a Kratom metabolite can cause false positive results in the Thermo Scientific CEDIA Methadone Metabolite (EDDP) immunoassay. Kratom use should be investigated in cases of false positive urine drug screens for EDDP.
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Rajesh, K. Sharma, K. Sharma Pankaj, Talat Gaush, Gautam Praveen, Chhabra Reba, and Singh Surinder. "BRIEF OVERVIEW ON HEPATITIS C VIRUS IMMUNOASSAYS." International Journal of Research – Granthaalayah 4, no. 1 (2017): 178–84. https://doi.org/10.5281/zenodo.848525.
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The publication deals with a brief overview of Hepatitis C Virus (HCV) and donor blood screening for HCV by using conventional Rapid, Enzyme Linked Immunosorbent Assay (ELISA) and Chemiluminescence Immunoassay (CLIA) also. The advantages of various generation o
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Tsang, Raymond SW, Sandra Michelle Radons, and Muhammad Morshed. "Laboratory Diagnosis of Syphilis: A Survey to Examine the Range of Tests Used in Canada." Canadian Journal of Infectious Diseases and Medical Microbiology 22, no. 3 (2011): 83–87. http://dx.doi.org/10.1155/2011/627076.
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Laboratory diagnosis of syphilis has undergone major changes in the past decade with the introduction of immunoassays and recombinantTreponema pallidumantigens as screening tools for syphilis infection. To address this change in laboratory practice, a national syphilis laboratory working group was established with members from the Public Health Agency of Canada, provincial public health laboratories across the country as well as sexually transmitted infection researchers, clinicians and epidemiologists. This working group aims to examine how the use of newer immunoassays will affect syphilis diagnosis, surveillance and disease management. To provide a baseline for this work, an e-mail survey was conducted in the fall of 2009 to determine current laboratory practices for syphilis diagnosis in Canada. The most commonly used tests were rapid plasma reagin, enzyme immunoassay,T pallidumpassive particle agglutination, venereal disease research laboratory, fluorescent treponemal antibody absorption, line immunoassay and polymerase chain reaction with 92%, 36%, 32%, 20%, 12%, 12% and 12% of the responding laboratories reporting using these tests, respectively. The ultimate goal of this working group will be to update laboratory guidelines for the diagnosis of syphilis, and to identify syphilis surveillance and research priorities in Canada.
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Allred, Laura K., Jennifer A. Sealey Voyksner, and Robert D. Voyksner. "Evaluation of Qualitative and Quantitative Immunoassays To Detect Barley Contamination in Gluten-Free Beer with Confirmation Using LC/MS/MS." Journal of AOAC INTERNATIONAL 97, no. 6 (2014): 1615–25. http://dx.doi.org/10.5740/jaoacint.14-058.
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Abstract To meet the need for the detection and quantitation of barley gluten in beer, qualitative screening and quantitative immunoassays based on the monoclonal antigluten antibody 401/21 (Skerritt) were validated in a single laboratory. Sample replicates were tested at each stage of beer production using multiple yeast strains and methods of end-stage protein removal. Quantitation was performed using barley-specific standards based on barley flour extracts. Immunoassay results were confirmed using LC/MS/MS for barley-specific peptides. The LOD for the qualitative screening test was 5 mg/L barley gluten. Recovery for the barley-spiked worts ranged from 81 to 128% in the quantitative ELISA assay; the LOD was &lt;1 mg/L, and the LOQ was 5 mg/L. Both screening and confirmation methods were found to be fit for the purposes of detection of low levels of barley gluten in beer.
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Schuler, Charles F., Carmen Gherasim, Kelly O’Shea, et al. "Accurate point-of-care serology tests for COVID-19." PLOS ONE 16, no. 3 (2021): e0248729. http://dx.doi.org/10.1371/journal.pone.0248729.
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Background As COVID-19 vaccines become available, screening individuals for prior COVID-19 infection and vaccine response in point-of-care (POC) settings has renewed interest. We prospectively screened at-risk individuals for SARS-CoV-2 spike and nucleocapsid protein antibodies in a POC setting to determine if it was a feasible method to identify antibody from prior infection. Methods Three EUA-approved lateral flow antibody assays were performed on POC finger-stick blood and compared with serum and a CLIA nucleocapsid antibody immunoassay. Variables including antibody class, time since PCR, and the assay antigen used were evaluated. Results 512 subjects enrolled, of which 104 had a COVID-19 history and positive PCR. Only three PCR-positive subjects required hospitalization, with one requiring mechanical ventilation. The POC results correlated well with the immunoassay (93–97% sensitivity) and using serum did not improve the sensitivity or specificity. Conclusions Finger-stick, POC COVID-19 antibody testing was highly effective in identifying antibody resulting from prior infections in mildly symptomatic subjects. Using high-complexity serum immunoassays did not improve the screening outcome. Almost all individuals with COVID-19 infection produced detectable antibodies to the virus. POC antibody testing is useful as a screen for prior COVID-19 infection, and should be useful in assessing vaccine response.
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Pierce, Thomas. "Immunoassay as a Screening Tool for Industrial Toxicants." Journal of Occupational and Environmental Medicine 28, no. 8 (1986): 589–92. http://dx.doi.org/10.1097/00043764-198608000-00013.
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Garrote, Sorell, Alfonso, et al. "A novel visual immunoassay for coeliac disease screening." European Journal of Clinical Investigation 29, no. 8 (1999): 697–99. http://dx.doi.org/10.1046/j.1365-2362.1999.00518.x.
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Singh, Prithipal, Bhanu P. Ram, and Nikolai Sharkov. "Enzyme immunoassay for screening of sulfamethazine in swine." Journal of Agricultural and Food Chemistry 37, no. 1 (1989): 109–14. http://dx.doi.org/10.1021/jf00085a025.
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MacBeath, Gavin, and Donald Hilvert. "Monitoring Catalytic Activity by Immunoassay: Implications for Screening." Journal of the American Chemical Society 116, no. 14 (1994): 6101–6. http://dx.doi.org/10.1021/ja00093a006.
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Chapman, J., E. Youkilis, and E. Woods. "Multiple immunoassay mouse model for screening potential immunomodulators." International Journal of Immunopharmacology 7, no. 3 (1985): 376. http://dx.doi.org/10.1016/0192-0561(85)90387-x.
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GHOSH, R. "Rapid antibody screening by membrane chromatographic immunoassay technique." Journal of Chromatography B 844, no. 1 (2006): 163–67. http://dx.doi.org/10.1016/j.jchromb.2006.07.030.
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Sheth, Hasmukh B., and Peter sporns. "Enzyme Immunoassay For Screening Of Sulfathiazole In Honey." Journal of AOAC INTERNATIONAL 73, no. 6 (1990): 871–74. http://dx.doi.org/10.1093/jaoac/73.6.871.
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Abstract A simple enzyme Immunoassay (EIA) was developed to screen honey samples for sulfathiazole (ST) adulteration. Honey samples required only a 30-fold dilution before use In the procedure. Because 96 well microtlter plates were used and only 100 μL of diluted honey sample was required per well, numerous replicates or samples could be tested simultaneously. The EIA was able to detect at least 0.3 ppm levels of ST In honey and also provide a rough quantitation of ST amounts.
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Taran, Frédéric, Cécile Gauchet, Barbara Mohar, et al. "High-Throughput Screening of Enantioselective Catalysts by Immunoassay." Angewandte Chemie 114, no. 1 (2002): 132–35. http://dx.doi.org/10.1002/1521-3757(20020104)114:1<132::aid-ange132>3.0.co;2-d.
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Taran, Frédéric, Cécile Gauchet, Barbara Mohar, et al. "High-Throughput Screening of Enantioselective Catalysts by Immunoassay." Angewandte Chemie International Edition 41, no. 1 (2002): 124–27. http://dx.doi.org/10.1002/1521-3773(20020104)41:1<124::aid-anie124>3.0.co;2-r.
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Lenicek Krleza, Jasna, Merica Aralica, Lara Milevoj Kopcinovic, and Renata Zrinski Topic. "Clinical and Analytical Comparison of Monoclonal and Polyclonal Immunoassays for Fecal Pancreatic Elastase." Diagnostics 14, no. 11 (2024): 1166. http://dx.doi.org/10.3390/diagnostics14111166.
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Background: Numerous immunoassays have been commercialized to determine pancreatic elastase (PE) in feces in screening for exocrine pancreatic insufficiency (EPI), but how the different assays compare to one another is controversial, especially in the context that all methods use the same cut-off values for interpreting the results obtained on the presence or absence of EPI or the degree of insufficiency if it is present. Our aim was to analytically verify a new method for determining PE, compare the results with a previous method, and verify the declared cut-off values for interpretation of the results. Methods: PE in the stool was assayed using a previous monoclonal enzyme-linked immunosorbent assay (“ScheBo ELISA”) and a new polyclonal particle-enhanced turbidimetric immunoassay (“Bühlmann PETIA”). The direct method comparison of two immunoassays was performed in 40 samples. Clinical comparisons were conducted against each other for the binary determination of “abnormal/normal” elastase levels and the three-way determination of “severe/moderate/no” EPI in 56 samples. The indirect comparison method used external quality assessment (EQA) data to compare the monoclonal and polyclonal immunoassays for PE, and additionally compare the monoclonal ScheBo ELISA to a monoclonal chemiluminescence immunoassay (“DiaSorin CLIA”). Results: Precision in the series and intra-laboratory precision for Bühlmann PETIA met the manufacturer’s specifications for the concentration range of limit/lower values and the range of normal values. The Bühlmann PETIA immunoassay on different analytical platforms yielded comparable results and nearly perfect agreement in the case of three-way classification (kappa = 0.89 with 95%CI from 0.79 to 1.00. ScheBo ELISA tends to generate higher values of pancreatic elastase than the Bühlmann PETIA; agreement between the methods was moderate in the case of binary classification (kappa = 0.43; 95% CI 0.25 to 0.62), and substantial in the case of three-way classification (kappa = 0.62; 95% CI 0.50 to 0.75). EQA data analysis showed a statistically significant difference between ScheBo ELISA and Bühlmann PETIA peer groups (p = 0.031), as well as the DiaSorin CLIA and ScheBo ELISA peer groups (p = 0.010). Conclusion: The ScheBo ELISA and Bühlmann PETIA do not appear to be commutable in the analytical and clinical context. Our data address a discordance between different mono- and polyclonal immunoassays for pancreatic elastase and the potential of misclassification using its universal cut-off values in screening suspected patients for exocrine pancreatic insufficiency.
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Jaskowski, Troy D., Thomas B. Martins, Christine M. Litwin, and Harry R. Hill. "Comparison of Three Different Methods for Measuring Classical Pathway Complement Activity." Clinical Diagnostic Laboratory Immunology 6, no. 1 (1999): 137–39. http://dx.doi.org/10.1128/cdli.6.1.137-139.1999.
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ABSTRACT The complement system plays an important role in host defense against infection and in most inflammatory processes. The standard 50% hemolytic complement (CH50) assay is the most commonly used method of screening patient sera for functional activity of the classical complement pathway. Our objective in this study was to compare two newer methods (the enzyme immunoassay and the liposome immunoassay) to a commercial CH50 assay for measuring total classical complement activity. We conclude that both newer methods compare well with a CH50 assay and are equally sensitive in screening routine clinical sera.
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Gray, Teresa R., Tamsin Kelly, Linda L. LaGasse, et al. "New Meconium Biomarkers of Prenatal Methamphetamine Exposure Increase Identification of Affected Neonates." Clinical Chemistry 56, no. 5 (2010): 856–60. http://dx.doi.org/10.1373/clinchem.2009.139055.
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Abstract Background: Prenatal methamphetamine (MAMP) exposure is poorly reflected in neonatal meconium. Often, maternal self-reported MAMP use is not corroborated by positive results in amphetamines immunoassays of meconium, and even if initial test results are positive, they frequently are not confirmed for MAMP or amphetamine (AMP) by chromatographic analysis. The presence of the MAMP metabolites p-hydroxymethamphetamine (pOHMAMP), p-hydroxyamphetamine (pOHAMP), and norephedrine (NOREPH) in meconium may improve the identification of MAMP- and AMP-exposed neonates. Methods: Immunoassay-positive and -negative meconium samples were subjected to liquid chromatography– tandem mass spectrometric reanalysis for these recently identified metabolites. Results: pOHAMP and NOREPH were detected only when MAMP and/or AMP were present and thus do not appear to be promising biomarkers of prenatal MAMP exposure. pOHMAMP, in contrast, identified 6 additional neonates whose mothers reported MAMP exposure, yet had a meconium sample screened as negative; pOHMAMP was more likely to be present if maternal MAMP use continued into the third trimester. Although the pOHMAMP results for meconium samples corroborated the maternal self-reports, the confirmation rate for positive meconium screening results did not improve with the inclusion of these new biomarkers. Conclusions: pOHMAMP identified additional MAMP- exposed neonates; therefore, MAMP, AMP, and pOHMAMP should be included in meconium chromatographic analyses. Maximizing the identification of MAMP-exposed children requires improvement in immunoassay screening tests to reduce false-negative and false-positive results. Additional research will help clarify which AMP-related compounds, if any, contribute to unconfirmed positive results in screening tests. Furthermore, nonamphetamine compounds endogenous to the complex meconium matrix also may cross-react, making chromatographic confirmation of screening results essential.
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Enomoto, Koji, Yuko Aono, Takashi Mitsugi, et al. "High Throughput Screening for Human Interferon-y Production Inhibitor Using Homogenous Time-Resolved Fluorescence." Journal of Biomolecular Screening 5, no. 4 (2000): 263–68. http://dx.doi.org/10.1177/108705710000500409.
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An immunoassay for interferon-γ (IFN-γ) using homogeneous time-resolved fluorescence (HTRF) has been developed. In this assay, IFN-γ can be detected by simply adding a mixture of three reagents-biotinylated polyclonal antibody, europium cryptate (fluorescence donor, EuK)-labeled monoclonal antibody, and crosslinked allophycocyanin (fluorescence acceptor, XL665) conjugated with streptavidin-and then measuring the time-resolved fluorescence. The detection limit of IFN-γ by the proposed method is about 625 pg/ml. We applied the method to the detection of IFN-γ secreted from NK3.3 cells and employed it in high throughput screening for IFN-γ production inhibitors. With this screening format, IFN-γ can be measured by directly adding the above reagents to microplate wells where NK3.3 cells are being cultured and stimulated with interleukin-12. This "in situ" immunoassay requires only pipetting reagents, with no need to transfer the culture supernatant to another microplate or wash the plate. Therefore, this screening format makes possible full automation of cell-based immunoassay, thus reducing cost and experimental time while increasing accuracy and throughput.
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Marques, Bárbara Araújo, Ericka Vianna Machado Carellos, Vânia Maria Novato Silva, et al. "Comparison between Enzyme Immunoassays Performed on Samples of Dried Blood and Serum for Toxoplasmosis Prenatal Screening: Population-based Study." Revista Brasileira de Ginecologia e Obstetrícia / RBGO Gynecology and Obstetrics 43, no. 05 (2021): 351–56. http://dx.doi.org/10.1055/s-0041-1730285.
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Abstract Objective Most prenatal screening programs for toxoplasmosis use immunoassays in serum samples of pregnant women. Few studies assess the accuracy of screening tests in dried blood spots, which are of easy collection, storage, and transportation. The goals of the present study are to determine the performance and evaluate the agreement between an immunoassay of dried blood spots and a reference test in the serum of pregnant women from a population-based prenatal screening program for toxoplasmosis in Brazil. Methods A cross-sectional study was performed to compare the immunoassays Imunoscreen Toxoplasmose IgM and Imunoscreen Toxoplasmose IgG (Mbiolog Diagnósticos, Ltda., Contagem, Minas Gerais, Brazil)in dried blood spots with the enzyme-linked fluorescent assay (ELFA, BioMérieux S.A., Lyon, France) reference standard in the serum of pregnant women from Minas Gerais Congenital Toxoplasmosis Control Program. Results The dried blood spot test was able to discriminate positive and negative results of pregnant women when compared with the reference test, with an accuracy of 98.2% for immunoglobulin G (IgG), and of 95.8% for immunoglobulin M (IgM). Conclusion Dried blood samples are easy to collect, store, and transport, and they have a good performance, making this a promising method for prenatal toxoplasmosis screening programs in countries with continental dimensions, limited resources, and a high prevalence of toxoplasmosis, as is the case of Brazil.
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Melzer-Lange, Marlene, Laurie Good, and Halim Hennes. "Chlamydia trachomatisInfections: Implications for Pregnant Adolescents and Their Infants." Infectious Diseases in Obstetrics and Gynecology 2, no. 1 (1994): 10–15. http://dx.doi.org/10.1155/s1064744994000323.
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Objective: Chlamydia trachomatisinfections are common in pregnant adolescents. Previous studies have shown that treating pregnant women of all ages with erythromycin prevents transmission of this infection to their infants. However, there are no published studies on the efficacy of aggressive screening and treatment ofC. trachomatisin pregnant adolescents. This study was undertaken to determine if aggressive screening forC. trachomatisin pregnant adolescents and early treatment with erythromycin can prevent complications in their newborn infants.Methods:A group of pregnant adolescents enrolled at Teen Pregnancy Service of Milwaukee was evaluated prospectively for the presence ofC. trachomatisinfection. Screening was performed during the 1st and 3rd trimesters by enzyme immunoassay. Adolescents with positive enzyme immunoassays forChlamydiawere treated with erythromycin for 10 days. Those with negative enzyme immunoassays were enrolled as controls. All infants born to adolescents in both groups were followed for episodes of conjunctivitis, pneumonia, and wheezing during their 1st year of life.Results:Ninety mother/infant pairs were followed during the study period. Twenty-eight mothers (31%) had positive enzyme assay tests and all received erythromycin therapy. Nasopharyngeal cultures were obtained from 60 (67%) infants; all were negative. There were no significant differences in general characteristics, development of conjunctivitis (relative risk 1.27), wheezing (relative risk 0.91), or pneumonia (relative risk 1.12) between infants born to adolescents in either group.Conclusions:We conclude that aggressive screening and treatment ofC. trachomatisinfection in pregnant adolescents may prevent complications in their offspring.
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Yatsula, Victoria, Christopher Shelburne, Qian Ning, et al. "Rapid Immunoassay Development using the U-PLEX® Assay Platform." Journal of Immunology 198, no. 1_Supplement (2017): 81.18. http://dx.doi.org/10.4049/jimmunol.198.supp.81.18.
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Abstract In the expanding field of biomarker research, methods to identify immunoassay reagents and optimize their use can be rate limiting for product development programs. Flexible tools that accelerate assay development, from antibody screening and selection to assay feasibility, can accelerate these programs. Here we demonstrate the use of the MSD® U-PLEX platform to conduct early assay development steps in parallel in a multiplex format. This resulted in rapid identification of a multiplexed panel of compatible assays. Unbiased pairwise screening of 59 antibodies was performed on MULTI-SPOT® U-PLEX plates using biotinylated capture antibodies and detection antibodies conjugated with SULFO-TAG™ label. Feasible antibody pairs were identified based on high signal and low background, then ranked using parameters such as dynamic range, sensitivity, specificity, sample recognition, and matrix tolerance. Within four weeks, two prototype immunoassays were developed and characterized. This screening time frame can range from days to weeks depending on the number of starting antibodies (typically 10–50) and the level of characterization required. Due to the flexible nature of the platform and the ability to mix and match reagents, the same conjugated reagents identified in screening were used to create and characterize multiplex assay panels. Parameters such as calibration curve, assay protocol, detection antibody concentration, and non-specific binding were characterized with up to ten assays simultaneously in a multiplex. In conclusion, we demonstrate the utility of a flexible assay development system that allows rapid identification and optimization of assays for stand-alone use or in combination with existing MSD assays.
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Akter, Tanjina, and Nikolina Babic. "Lorazepam Detection with Urine Benzodiazepines Screening Tests: Not all Tests are Created Equal." American Journal of Clinical Pathology 160, Supplement_1 (2023): S121. http://dx.doi.org/10.1093/ajcp/aqad150.264.
Full textAbstract:
Abstract Lorazepam belongs to the benzodiazepines family of drugs and is one of the commonly used anti-anxiety medications in the US. In clinical practice, immunoassay screening tests are used to monitor compliance, detect abuse and in cases of drug overdose. Many clinicians rely on benzodiazepine immunoassay screening tests to detect lorazepam due to the test availability on automated clinical analyzers, short turnaround time and cost efficiency. However, compromised test sensitivity often leads to erroneous results. In this study, we used mass spectrometry to establish the lorazepam cross-reactivity threshold in two commonly used benzodiazepine screening tests: the Abbott ARCHITECT cSystem 16000 and NexScreen Drug Screen Cup. Methods: Mass spectrometry testing was performed at a major reference laboratory. Lorazepam-positive patient urine at concentrations of 320 ng/mL and 4,895 ng/mL were tested concurrently by two immunoassay methods. The Abbott ARCHITECT is a semi-quantitative assay with a positivity cut-off of 200 ng/mL. According to the manufacturer’s instructions for use (IFUs), the cross-reactivity threshold of the test is equivalent to a lorazepam concentration of 650 ng/mL. The NexScreen Drug Screen Cup is a lateral flow immunoassay used as a point-of-care (POC) test. The positivity cut-off of this test is 300 ng/mL; per IFUs, the cross-reactivity threshold of this test to lorazepam is 3,900 ng/mL, and 5,000 ng/mL for lorazepam-glucuronide, a drug metabolite. To determine the test sensitivity of the NexScreen test, patient specimen (4,895 ng/mL) was diluted at 1:5, 1:10, 1:20, 1:50, and 1:100, targeting the lorazepam concentrations of 979, 490, 245, 98 and 49 ng/mL respectively. To determine the sensitivity of the immunoassays to the parent molecule vs the metabolite, pre-screened negative urine was spiked with lorazepam or lorazepam-glucuronide at a concentration of 650 ng/mL, 5000 ng/mL, and 10000 ng/mL. Results: Abbott ARCHITECT failed to detect lorazepam in both patients, while the NexScreen resulted in positive benzodiazepine screen results for both patient specimens. All lorazepam-spiked specimens tested positive on both methods. However, all lorazepam glucuronide-spiked specimens tested negative on Abbott ARCHITECT and positive on NexScreen cup. The highest dilution detected by NexScreen was 1: 20, equivalent to approximately 245 ng/mL of lorazepam. Conclusion: Our findings suggest that the ARCHITECT benzodiazepine assay should not be used to screen patients on lorazepam, given its inability to detect the major metabolite, lorazepam glucuronide. Whenever available, a mass spectrometry method is always preferred. The results of our study demonstrated that in a specific patient population, where the likelihood of positive lorazepam test is high, the NexScreen cup is a viable, cost-effective alternative due to its excellent sensitivity.