Immunoassays

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Amitava Dasgupta - One of the best experts on this subject based on the ideXlab platform.

  • Zinc Sulfate, a Recently Introduced Urinary Adulterant Can Invalidate Urine Cotinine Test Using Immunoassay but Has Less Effect on Liquid Chromatography Combined With Tandem Mass Spectrometry-Based Test.
    Therapeutic Drug Monitoring, 2015
    Co-Authors: R. B. Dixon, Amitava Dasgupta
    Abstract:

    Zinc sulfate is a recently introduced urinary adulterant, which causes false-negative results with Immunoassays used for screening drugs of abuse in urine but whether zinc sulfate also could invalidate urine cotinine assay using immunoassay or liquid chromatography combined with mass spectrometry has never been studied.Four urine pools containing none detected to high levels of cotinine were analyzed using DRI cotinine immunoassay on the Olympus 640 analyzer as well as using liquid chromatography combined with tandem mass spectrometry. Specimens were reanalyzed after supplementing with various amounts of zinc sulfate that are known to invalidate Immunoassays used for drugs of abuse testing.Zinc sulfate in all concentrations studied caused false-negative results using Immunoassays, but zinc sulfate also reduced cotinine values by approximately 2.1%-38.4% when analyzed using liquid chromatography combined with mass spectrometry.Zinc sulfate caused false-negative cotinine result when DRI immunoassay was used and also had small to moderate impact on liquid chromatography combined with tandem mass spectrometry-based assay for urine cotinine.

  • Immunoassay Platform and Designs
    Clinical Chemistry Immunology and Laboratory Quality Control, 2014
    Co-Authors: Amitava Dasgupta, Amer Wahed
    Abstract:

    This chapter will discuss various platforms of Immunoassays, homogenous vs. heterogenous platforms, as well as various methods of detection. Common immunoassay designs such as EMIT, FPIA, CEDIA, MEIA, and chemiluminescence detection will also be discussed. In this chapter, important interferences of heterophilic antibodies with various Immunoassays (especially Immunoassays) used for analysis of large molecules will also be addressed.

  • Impact of interferences including metabolite crossreactivity on therapeutic drug monitoring results.
    Therapeutic drug monitoring, 2012
    Co-Authors: Amitava Dasgupta
    Abstract:

    Therapeutic drug monitoring is an integral part of services offered by toxicology laboratories because certain drugs require routine monitoring for dosage adjustment to achieve optimal therapeutic response and avoid adverse drug reactions. Immunoassays are widely used for therapeutic drug monitoring. However, Immunoassays suffer from interferences from both exogenous and endogenous compounds including metabolites of the parent drug. Digoxin Immunoassays are affected more commonly than any other Immunoassays used for therapeutic drug monitoring. Digoxin Immunoassays are affected by endogenous digoxin-like immunoreactive substances and exogenous compounds such as various drugs, certain herbal supplements, and Digibind. Carbamazepine is metabolized to carbamazepine 10, 11-epoxide, and the crossreactivity of this metabolite with carbamazepine immunoassay may vary from 0% to 94%. Immunoassays used for measuring concentrations of tricyclic antidepressants are affected by tricyclic antidepressant metabolites and by a number of other drugs. Immunoassays for immunosuppressants are also subjected to significant interferences from metabolites, and liquid chromatography combined with mass spectrometry or tandem mass spectrometry is recommended for therapeutic drug monitoring of immunosuppressants. However, liquid chromatography combined with mass spectrometry may also suffer from interferences, for example, due to ion suppression or from isobaric ions.

  • Effect of Indian Ayurvedic medicine Ashwagandha on measurement of serum digoxin and 11 commonly monitored drugs using Immunoassays: study of protein binding and interaction with Digibind.
    Archives of Pathology & Laboratory Medicine, 2007
    Co-Authors: Amitava Dasgupta, Amanda Peterson, Alice Wells, Jeffrey K Actor
    Abstract:

    ● Context.—Ashwagandha, a popular Ayurvedic medicine, is now available in the United States. Alkaloids found in this herb have structural similarity with digoxin. Objective.—To study potential interference of Ashwagandha with serum digoxin measurement by Immunoassays. Potential interference was also investigated with Immunoassays for 11 other commonly monitored drugs. In addition, interaction of components of Ashwagandha with the Fab fragment of antidigoxin antibody (Digibind) was investigated. Design.—Two different brands of liquid extract and 1 dry powdered form of Ashwagandha were used for this investigation. Aliquots of drug-free serum were supplemented with various concentrations of Ashwagandha and apparent digoxin concentrations were measured by 3 digoxin Immunoassays. Mice were fed with Ashwagandha and apparent digoxin concentrations were measured 1 and 3 hours after feeding. Potential interference of Ashwagandha with Immunoassays of 11 other drugs was also investigated. Interaction of components of Ashwagandha with Digibind was studied in vitro. Results.—Significant apparent digoxin concentrations were observed both in vitro and in vivo using the fluorescence polarization immunoassay of digoxin, whereas the Beckman and the microparticle enzyme immunoassay digoxin assay demonstrated minimal interference. Immunoassays of 11 other drugs tested were unaffected. When Ashwagandha extract was added to a serum pool containing digoxin, falsely elevated digoxin value was observed with fluorescence polarization immunoassay, but values were falsely lowered when measured by the microparticle enzyme immunoassay. Digibind neutralized digoxin-like immunoreactive components of Ashwagandha in vitro. Conclusions.—Components of Ashwagandha interfered with serum digoxin measurements using Immunoassays. Digibind neutralized free digoxin-like immunoreactive components of Ashwagandha. (Arch Pathol Lab Med. 2007;131:1298–1303)

  • Bidirectional (positive/negative) interference in a Digoxin immunoassay: Importance of antibody specificity
    Therapeutic Drug Monitoring, 1998
    Co-Authors: Pradip Datta, Amitava Dasgupta
    Abstract:

    : The importance of high specificity in Immunoassays used in therapeutic monitoring is highlighted by a case study in which therapeutic-to-toxic borderline digoxin levels were measured by a digoxin immunoassay in the serum sample from a patient administered digitoxin rather than digoxin. The sample, mistakenly sent to the laboratory for digoxin analysis, gave discordant results in three digoxin Immunoassays: 1.99 and 0.79 ng/ml in assays using polyclonal antibodies (fluorescence-polarization immunoassay and microparticle enzyme immunoassay, respectively), and

Yves Gallois - One of the best experts on this subject based on the ideXlab platform.

  • Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques
    Clinica Chimica Acta, 2007
    Co-Authors: Valérie Moal, Elisabeth Mathieu, Pascal Reynier, Yves Malthièry, Yves Gallois
    Abstract:

    Abstract Background Low levels of serum testosterone, as typically found in women and children, cannot be measured reliably by Immunoassays. Our aim was to develop a sensitive assay to quantitate low serum testosterone concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results were compared to those obtained with various immunoassay techniques. Methods Serum testosterone levels in 70 women and children were measured using LC-MS/MS and compared with two automated, non-isotopic Immunoassays, and three manual, isotopic Immunoassays. Serum extraction was required only for LC-MS/MS and one of the isotopic methods. Results Deming regression analysis was used for comparison: the correlation coefficients were between 0.772 and 0.870, and the slopes between 0.972 and 1.365. Using Bland and Altman analysis, all the 5 Immunoassays showed a positive mean difference compared with LC-MS/MS: all overestimated the testosterone levels in women and children. Conclusion None of the Immunoassays tested proved sufficiently reliable when low testosterone concentrations (≤ 3.47 nmol/L) were measured. In contrast to conventional isotopic and non-isotopic immunoassay techniques, LC-MS/MS allows the precise determination of low testosterone levels. It has adequate sensitivity and is not subject to interference from other steroids that were tested.

  • Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques.
    Clinica chimica acta; international journal of clinical chemistry, 2007
    Co-Authors: Valérie Moal, Elisabeth Mathieu, Pascal Reynier, Yves Malthièry, Yves Gallois
    Abstract:

    Low levels of serum testosterone, as typically found in women and children, cannot be measured reliably by Immunoassays. Our aim was to develop a sensitive assay to quantitate low serum testosterone concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results were compared to those obtained with various immunoassay techniques. Serum testosterone levels in 70 women and children were measured using LC-MS/MS and compared with two automated, non-isotopic Immunoassays, and three manual, isotopic Immunoassays. Serum extraction was required only for LC-MS/MS and one of the isotopic methods. Deming regression analysis was used for comparison: the correlation coefficients were between 0.772 and 0.870, and the slopes between 0.972 and 1.365. Using Bland and Altman analysis, all the 5 Immunoassays showed a positive mean difference compared with LC-MS/MS: all overestimated the testosterone levels in women and children. None of the Immunoassays tested proved sufficiently reliable when low testosterone concentrations (< or =3.47 nmol/L) were measured. In contrast to conventional isotopic and non-isotopic immunoassay techniques, LC-MS/MS allows the precise determination of low testosterone levels. It has adequate sensitivity and is not subject to interference from other steroids that were tested.

Elisabeth Mathieu - One of the best experts on this subject based on the ideXlab platform.

  • Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques
    Clinica Chimica Acta, 2007
    Co-Authors: Valérie Moal, Elisabeth Mathieu, Pascal Reynier, Yves Malthièry, Yves Gallois
    Abstract:

    Abstract Background Low levels of serum testosterone, as typically found in women and children, cannot be measured reliably by Immunoassays. Our aim was to develop a sensitive assay to quantitate low serum testosterone concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results were compared to those obtained with various immunoassay techniques. Methods Serum testosterone levels in 70 women and children were measured using LC-MS/MS and compared with two automated, non-isotopic Immunoassays, and three manual, isotopic Immunoassays. Serum extraction was required only for LC-MS/MS and one of the isotopic methods. Results Deming regression analysis was used for comparison: the correlation coefficients were between 0.772 and 0.870, and the slopes between 0.972 and 1.365. Using Bland and Altman analysis, all the 5 Immunoassays showed a positive mean difference compared with LC-MS/MS: all overestimated the testosterone levels in women and children. Conclusion None of the Immunoassays tested proved sufficiently reliable when low testosterone concentrations (≤ 3.47 nmol/L) were measured. In contrast to conventional isotopic and non-isotopic immunoassay techniques, LC-MS/MS allows the precise determination of low testosterone levels. It has adequate sensitivity and is not subject to interference from other steroids that were tested.

  • Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques.
    Clinica chimica acta; international journal of clinical chemistry, 2007
    Co-Authors: Valérie Moal, Elisabeth Mathieu, Pascal Reynier, Yves Malthièry, Yves Gallois
    Abstract:

    Low levels of serum testosterone, as typically found in women and children, cannot be measured reliably by Immunoassays. Our aim was to develop a sensitive assay to quantitate low serum testosterone concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results were compared to those obtained with various immunoassay techniques. Serum testosterone levels in 70 women and children were measured using LC-MS/MS and compared with two automated, non-isotopic Immunoassays, and three manual, isotopic Immunoassays. Serum extraction was required only for LC-MS/MS and one of the isotopic methods. Deming regression analysis was used for comparison: the correlation coefficients were between 0.772 and 0.870, and the slopes between 0.972 and 1.365. Using Bland and Altman analysis, all the 5 Immunoassays showed a positive mean difference compared with LC-MS/MS: all overestimated the testosterone levels in women and children. None of the Immunoassays tested proved sufficiently reliable when low testosterone concentrations (< or =3.47 nmol/L) were measured. In contrast to conventional isotopic and non-isotopic immunoassay techniques, LC-MS/MS allows the precise determination of low testosterone levels. It has adequate sensitivity and is not subject to interference from other steroids that were tested.

  • testosterone measured by 10 Immunoassays and by isotope dilution gas chromatography mass spectrometry in sera from 116 men women and children
    Clinical Chemistry, 2003
    Co-Authors: Joelle Taieb, Elisabeth Mathieu, Bruno Mathian, Francoise Millot, Marieclaude Patricot, Nicole Queyrel, Isabelle Lacroix, Claude Sommadelpero, Philippe Boudou
    Abstract:

    Background: Commercially available testosterone Immunoassays give divergent results, especially at the low concentrations seen in women. We compared Immunoassays and a nonimmunochemical method that could quantify low testosterone concentrations. Methods: We measured serum testosterone in 50 men, 55 women, and 11 children with use of eight nonisotopic Immunoassays, two isotopic Immunoassays, and isotope-dilution gas chromatography–mass spectrometry (ID/GC-MS). Results: Compared with ID/GC-MS, 7 of the 10 Immunoassays tested overestimated testosterone concentrations in samples from women; mean immunoassay results were 46% above those obtained by ID/GC-MS. The Immunoassays underestimated testosterone concentrations in samples from men, giving mean results 12% below those obtained by ID/GC-MS. In women, at concentrations of 0.6–7.2 nmol/L, 3 of the 10 Immunoassays gave positive mean differences >2.0 nmol/L (range, −0.7 to 3.3 nmol/L) compared with ID/GC-MS; in men at concentrations of 8.2–58 nmol/L, 3 of the 10 Immunoassays tested gave mean differences >4.0 nmol/L (range, −4.8 to 2.6 nmol/L). Conclusion: None of the Immunoassays tested was sufficiently reliable for the investigation of sera from children and women, in whom very low (0.17 nmol/L) and low (<1.7 nmol/L) testosterone concentrations are expected.

Valérie Moal - One of the best experts on this subject based on the ideXlab platform.

  • Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques
    Clinica Chimica Acta, 2007
    Co-Authors: Valérie Moal, Elisabeth Mathieu, Pascal Reynier, Yves Malthièry, Yves Gallois
    Abstract:

    Abstract Background Low levels of serum testosterone, as typically found in women and children, cannot be measured reliably by Immunoassays. Our aim was to develop a sensitive assay to quantitate low serum testosterone concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results were compared to those obtained with various immunoassay techniques. Methods Serum testosterone levels in 70 women and children were measured using LC-MS/MS and compared with two automated, non-isotopic Immunoassays, and three manual, isotopic Immunoassays. Serum extraction was required only for LC-MS/MS and one of the isotopic methods. Results Deming regression analysis was used for comparison: the correlation coefficients were between 0.772 and 0.870, and the slopes between 0.972 and 1.365. Using Bland and Altman analysis, all the 5 Immunoassays showed a positive mean difference compared with LC-MS/MS: all overestimated the testosterone levels in women and children. Conclusion None of the Immunoassays tested proved sufficiently reliable when low testosterone concentrations (≤ 3.47 nmol/L) were measured. In contrast to conventional isotopic and non-isotopic immunoassay techniques, LC-MS/MS allows the precise determination of low testosterone levels. It has adequate sensitivity and is not subject to interference from other steroids that were tested.

  • Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques.
    Clinica chimica acta; international journal of clinical chemistry, 2007
    Co-Authors: Valérie Moal, Elisabeth Mathieu, Pascal Reynier, Yves Malthièry, Yves Gallois
    Abstract:

    Low levels of serum testosterone, as typically found in women and children, cannot be measured reliably by Immunoassays. Our aim was to develop a sensitive assay to quantitate low serum testosterone concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results were compared to those obtained with various immunoassay techniques. Serum testosterone levels in 70 women and children were measured using LC-MS/MS and compared with two automated, non-isotopic Immunoassays, and three manual, isotopic Immunoassays. Serum extraction was required only for LC-MS/MS and one of the isotopic methods. Deming regression analysis was used for comparison: the correlation coefficients were between 0.772 and 0.870, and the slopes between 0.972 and 1.365. Using Bland and Altman analysis, all the 5 Immunoassays showed a positive mean difference compared with LC-MS/MS: all overestimated the testosterone levels in women and children. None of the Immunoassays tested proved sufficiently reliable when low testosterone concentrations (< or =3.47 nmol/L) were measured. In contrast to conventional isotopic and non-isotopic immunoassay techniques, LC-MS/MS allows the precise determination of low testosterone levels. It has adequate sensitivity and is not subject to interference from other steroids that were tested.

Mohammed Zourob - One of the best experts on this subject based on the ideXlab platform.

  • A rapid colorimetric immunoassay for the detection of pathogenic bacteria on poultry processing plants using cotton swabs and nanobeads
    Microchimica Acta, 2018
    Co-Authors: Saleh Alamer, Shimaa Eissa, Raja Chinnappan, Mohammed Zourob
    Abstract:

    The work describes a simple cotton swab-based colorimetric immunoassay as a rapid screening tool for pathogenic bacteria on poultry processing plants. This immunosensing platform can be used for the detection of pathogens present on surfaces such as glass, stainless steel and chicken meat. Unlike the reported assays, here, cotton swab plays dual function: as a sample collector from the solid surfaces and as detection platform. The immunoassay was tested for the detection of 4 different bacteria; Salmonella typhimurium, Salmonella enteritidis, Staphylococcus aureus and Campylobacter jejuni . The Immunoassays were fabricated by immobilizing specific antibody for each bacterium on a cotton swab that is used to recover the cells from contaminated surfaces. Then, a sandwich immunoassay was developed by immersing the cotton swab in different colored nanobead-conjugated antibody solutions which corresponds to different bacteria. The Immunoassays response was detected colorimetrically by following the change in the color intensity produced by the nanobeads due to the specific binding on the cotton swab. This simple colorimetric assay is very sensitive with a detection limit of 10 cfu.mL^−1. Furthermore, no significant cross reactivity of the Immunoassays with non specific bacteria was observed indicating good selectivity of the Immunoassays. This simple, disposable and easy-to- use colorimetric platform shows great promise as rapid qualitative and semi quantitative detection tool for microorganisms on food processing plants and other surfaces. Graphical abstract Schematic of the sandwich colorimetric immunosensor for the detection of pathogenic bacteria on poultry processing plants using cotton swabs and nanobeads.

  • A rapid colorimetric immunoassay for the detection of pathogenic bacteria on poultry processing plants using cotton swabs and nanobeads
    Mikrochimica Acta, 2018
    Co-Authors: Saleh Alamer, Shimaa Eissa, Raja Chinnappan, Mohammed Zourob
    Abstract:

    The work describes a simple cotton swab-based colorimetric immunoassay as a rapid screening tool for pathogenic bacteria on poultry processing plants. This immunosensing platform can be used for the detection of pathogens present on surfaces such as glass, stainless steel and chicken meat. Unlike the reported assays, here, cotton swab plays dual function: as a sample collector from the solid surfaces and as detection platform. The immunoassay was tested for the detection of 4 different bacteria; Salmonella typhimurium, Salmonella enteritidis, Staphylococcus aureus and Campylobacter jejuni. The Immunoassays were fabricated by immobilizing specific antibody for each bacterium on a cotton swab that is used to recover the cells from contaminated surfaces. Then, a sandwich immunoassay was developed by immersing the cotton swab in different colored nanobead-conjugated antibody solutions which corresponds to different bacteria. The Immunoassays response was detected colorimetrically by following the change in the color intensity produced by the nanobeads due to the specific binding on the cotton swab. This simple colorimetric assay is very sensitive with a detection limit of 10 cfu.mL−1. Furthermore, no significant cross reactivity of the Immunoassays with non specific bacteria was observed indicating good selectivity of the Immunoassays. This simple, disposable and easy-to- use colorimetric platform shows great promise as rapid qualitative and semi quantitative detection tool for microorganisms on food processing plants and other surfaces.