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Fulltext Review paper : application of DNA and immunoassay analytical methods for GMO testing in agricultural crops and plant-derived products

Jasbeer, K., Ghazali, F.M., Cheah, Y.K., Son, R.

International Food Research Journal, 2008;15(1):1-25.
MyJurnal

The introduction of new agricultural commodities and products derived from modernbiotechnology may have an impact on human and animal health, the environment and economiesof countries. As more Genetically Modified Organisms (GMO) enter markets worldwide, themonitoring of GMOs is being preferred for obvious reasons such as determination of seed purity,verification of non-GMO status of agricultural crops and fulfilling GMO labeling provisions, tomention a few. Numerous GMO analytical methods which include screening, identification andquantification have been developed to reliably determine the presence and/or amount of GMOin agricultural commodities, in raw agricultural materials and in processed and refined ingredients.The detection of GMOs relies on the detection of transgenic DNA or protein material. For routineanalysis, a good sample preparation technique should reproducibly generate DNA/protein ofsufficient quality, purity and yield while minimizing the effects of inhibition andcontamination.
The key sample preparation steps include homogenization, pretreatment, extraction andpurification. Due to the fact that analytical laboratories receive samples that are often processedand refined, the quality and quantity of transgenic target analyte (e.g. protein and DNA) frequentlychallenge the sensitivity of any detection method. With the development of GMO analysistechniques, the Polymerase Chain Reaction (PCR) technique has been the mainstay for GMOdetection, and the real-time PCR is the most effective and important method for GMOquantification. The choice of target sequence; for example a promoter, a terminator, a gene, or ajunction between two of these elements, is the single most important factor controlling the specificity of the PCR method. Recent developments include event-specific methods, particularlyuseful for identification and quantification of GM content. Although PCR technology has obvious
limitations, the potentially high degree of sensitivity and specificity explains why PCR in its various
formats, is currently the leading analytical technology employed in GMO analysis. Comparatively, immunoassays are becoming attractive tools for rapid field monitoring for the integrity of agricultural commodities in identity preservation systems, whereby non-specialised personnel can employ them in cost-effective manner. This review discusses various popular extraction methodologies and summarises the current status of the most widely used and easily applicable GMO analysis technologies in laboratories, namely the PCR and immunoassay technologies.

Matched MeSH terms: Immunoassay
Immuno-probed multiwalled carbon nanotube surface for abdominal aortic aneurysm biomarker analysis

Zhao X, Gopinath SCB, Zhao W

Biotechnol Appl Biochem, 2023 Apr;70(2):502-508.
PMID: 35661417 DOI: 10.1002/bab.2372

Abdominal aortic aneurysm (AAA), a medical complication, occurs when the aortic area becomes swollen and very large. It is mandatory to identify AAA to avoid the breakdown of aneurysms. C-reactive protein (CRP) has been recognized as one of the biomarkers for identifying AAA due to the possibility of CRP produced in vascular tissue, which contributes to the formation of an aneurysm, and it is elevated in patients with a ruptured AAA. This research work was designed to develop an immunosensor on a multiwalled carbon nanotube (MWCNT)-modified surface to quantify the CRP level. Anti-CRP specificity was constructed on the MWCNT surface through a silane linker to interact with CRP. The detection limit of CRP was calculated as 100 pM with an R2 (determination coefficient) value of 0.9855 (y = 2.3446x - 1.9922) on a linear regression graph. The dose-dependent linear pattern was registered from 200 to 3000 pM and attained the saturation level during binding at 3000 pM. Furthermore, serum-spiked CRP showed a clear increase in the current response, proving the specific recognition of CRP in biological samples. This designed biosensor identifies CRP at a lower level and can help diagnose AAA.

Matched MeSH terms: Immunoassay
Fulltext Evaluation of the Elecsys(®) Anti-HCV II assay for routine hepatitis C virus screening of different Asian Pacific populations and detection of early infection

Yoo SJ, Wang LL, Ning HC, Tao CM, Hirankarn N, Kuakarn S, et al.

J Clin Virol, 2015 Mar;64:20-7.
PMID: 25728074 DOI: 10.1016/j.jcv.2014.12.015

Early diagnosis of hepatitis C virus (HCV) infection is essential to allow appropriate treatment and prevent transmission.

Matched MeSH terms: Immunoassay/methods*
Bacterial detection: from microscope to smartphone

Gopinath SC, Tang TH, Chen Y, Citartan M, Lakshmipriya T

Biosens Bioelectron, 2014 Oct 15;60:332-42.
PMID: 24836016 DOI: 10.1016/j.bios.2014.04.014

The ubiquitous nature of bacteria enables them to survive in a wide variety of environments. Hence, the rise of various pathogenic species that are harmful to human health raises the need for the development of accurate sensing systems. Sensing systems are necessary for diagnosis and epidemiological control of pathogenic organism, especially in the food-borne pathogen and sanitary water treatment facility' bacterial populations. Bacterial sensing for the purpose of diagnosis can function in three ways: bacterial morphological visualization, specific detection of bacterial component and whole cell detection. This paper provides an overview of the currently available bacterial detection systems that ranges from microscopic observation to state-of-the-art smartphone-based detection.

Matched MeSH terms: Immunoassay/instrumentation*
Fulltext Comparison between AmniSure placental alpha microglobulin-1 rapid immunoassay and standard diagnostic methods for detection of rupture of membranes

Ng BK, Lim PS, Shafiee MN, Ghani NA, Ismail NA, Omar MH, et al.

Biomed Res Int, 2013;2013:587438.
PMID: 24073412 DOI: 10.1155/2013/587438

Objective. To determine the diagnostic accuracy of placental alpha microglobulin-1 assay and standard diagnostic methods for detecting rupture of membrane. Study Design. Prospective diagnostic study, between June 2011 to November 2011 at a tertiary centre. Initial evaluation included both the standard diagnostic methods for rupture of membranes and placental alpha microglobulin-1 immunoassay. The actual rupture of membranes was diagnosed on review of the medical records after delivery (absence of membrane or a positive pad chart). Main Outcome Measures. Placental alpha microglobulin-1 immunoassay and standard diagnostic methods for diagnosis of rupture of membrane. Results. A total of 211 patients were recruited. At initial presentation, 187 patients (88.6%) had ruptured membranes, while 24 patients (11.4%) had intact membranes. Placental alpha microglobulin-1 immunoassay confirmed rupture of membranes at initial presentation with a sensitivity of 95.7% (179 of 187), specificity of 100% (24 of 24), positive predictive value of 100% (179 of 179), and negative predictive value of 75.0% (24 of 32). By comparison, the conventional standard diagnostic methods had a sensitivity of 78.1% (146 of 187), specificity of 100% (24 of 24), positive predictive value of 100% (146 of 146), and negative predictive value of 36.9% (24 of 65) in diagnosing rupture of membrane. Conclusion. Placental alpha-microglobulin-1 immunoassay is a rapid and accurate method for confirming the diagnosis of rupture of membrane. It was superior to conventional standard diagnostic methods (pooling, nitrazine, and ferning), the nitrazine test alone or fern test alone.

Matched MeSH terms: Immunoassay/methods*
Hev b 5 and Hev b 13 as allergen markers to estimate the allergenic potency of latex gloves

Yeang HY, Arif SA, Raulf-Heimsoth M, Loke YH, Sander I, Sulong SH, et al.

J Allergy Clin Immunol, 2004 Sep;114(3):593-8.
PMID: 15356563 DOI: 10.1016/j.jaci.2004.05.039

BACKGROUND:
Sensitization to natural rubber latex has been linked to proteins from medical latex gloves. Various assays to estimate the amount of residual allergenic proteins extractable from latex gloves to assess their potential exposure hazard have inherent weaknesses.

OBJECTIVE:
This investigation was aimed at developing 2-site immunoenzymetric assays and identifying appropriate protein markers to assess the allergenic potential of latex gloves.

METHODS:
The presence of 6 latex allergens--Hev b 1, 2, 3, 5, 6, and 13--was measured in a cross-section of commercial latex medical gloves by using monoclonal and polyclonal antibody-based 2-site immunoenzymetric assays. The overall allergenic potential of these gloves was assessed by IgE-inhibition assay. Stepwise multiple regression analyses were performed to identify marker allergens that best explained the variation in latex glove allergenicity.

RESULTS:
All 6 latex allergens were detected in at least some of the glove samples. Hev b 5 and Hev b 13 were identified as the marker allergens that combined best to explain the variation in the glove allergenicity. The significant multiple correlation (R=0.855) between these 2 markers and glove allergenic potency forms the basis of an assay to gauge latex glove allergenicity.

CONCLUSION:
The overall allergenic potential of latex gloves can be estimated by using Hev b 5 and Hev b 13 as indicator allergens. The correlation between glove allergenicity and the level of these allergens was maintained for low-protein gloves (<200 microg/g). This estimation of glove allergenicity was superior to that obtained by using total protein readings.

Matched MeSH terms: Immunoassay/methods
Evaluation of the MAST CLA allergy system for diagnosis of allergies to house dust mites and cats

Ho TM, DeBruynne J, Ahamad M, Darussamin H

Asian Pac J Allergy Immunol, 1997 Sep;15(3):123-6.
PMID: 9438543

The MAST CLA system was evaluated against skin prick test (SPT) for diagnosis of allergies to house dust mites (Dermatophagoides pteronyssinus, Dermatophagoides farinae) and cats. Forty three asthmatic children were examined by SPT and MAST CLA. Chi-square analysis indicated significant association between SPT and MAST CLA results for the house dust mites but not for cats. The sensitivities of MAST CLA for house dust mites and cats were 100 and 25% respectively; specificities were all less than 50%. The efficiency of MAST CLA for detection of allergy to the house dust mites was 88% and 44% for cats. A significant linear correlation was found between SPT wheal size and MAST CLA grade for D. farinae but not for D. pteronyssinus and cats. It is concluded that the MAST CLA allergy system can be used to supplement SPT for diagnosis of allergies to house dust mites but not to cats.

Matched MeSH terms: Immunoassay/methods*
A Brugia malayi antigen specifically recognized by infected individuals

Rahmah N, Anuar AK, A'shikin AN, Lim BH, Mehdi R, Abdullah B, et al.

Biochem Biophys Res Commun, 1998 Sep 29;250(3):586-8.
PMID: 9784388

Western blot analyses were performed on 444 serum specimens: 40 sera from microfilaraemic individuals, 10 sera from elephantiasis patients, 24 treated individuals, 50 sera from residents of endemic areas without anti-filarial IgG4 antibodies (endemic normals), 20 sera from amicrofilaraemic individuals with high anti-filarial IgG4 antibodies, 200 sera from healthy city-dwellers (non-endemic samples), and 100 sera from soil-transmitted helminth-infected individuals. Phast electrophoresis system was used to electrophorese Brugia malayi soluble adult worm antigen on 10-15% SDS-PAGE gradient gels followed by electrophoretic transfer onto PVDF membranes. Membrane strips were then successively incubated with blocking solution, human sera, and monoclonal anti-human IgG4 antibody-HRP, with adequate washings done in between each incubation step. Luminol chemiluminescence detection was then used to develop the blots. An antigenic band with the MW of approximately 37 kDa was found to be consistently present in the Western blots of all microfilaraemic sera, all amicrofilaraemic sera with high titres of anti-filarial IgG4 antibodies, some treated patients, and some elephantiasis patients. The antigen did not occur in immunoblots of individuals with other helminthic infections, normal endemic individuals, and city dwellers. Therefore the B. malayi antigen of with the MW of approximately 37 kDa demonstrated specific reactions with sera of B. malayi-infected individuals and thus may be useful for diagnostic application.

Matched MeSH terms: Immunoassay/methods
Fulltext Diagnostic accuracy of rapid diagnostic tests for the early detection of leptospirosis

Alia SN, Joseph N, Philip N, Azhari NN, Garba B, Masri SN, et al.

J Infect Public Health, 2018 11 27;12(2):263-269.
PMID: 30502041 DOI: 10.1016/j.jiph.2018.10.137

BACKGROUND: Leptospirosis is often misdiagnosed with several other tropical febrile illnesses in Malaysia due to similarities in clinical manifestations. Although treatment regimens could be started based on clinical judgments, early diagnosis has become paramount as a guide to chemotherapeutic interventions. Confirmed laboratory diagnosis through MAT or PCR is time consuming and usually available only in reference laboratories and not practical in healthcare settings. Rapid and easy to perform diagnostic tests are widely used in these settings as the point of care diagnosis. The present study was undertaken to compare the diagnostic performance of two IgM based immunodiagnostic assay kits for acute leptospirosis.
METHODS: A total of 50 serum samples were collected from patients clinically suspected for acute leptospirosis on admission in the Hospital Serdang, from June 2016 to June 2017. All the samples were subjected to MAT, lipL32 PCR and the two rapid tests (Leptocheck-WB and ImmuneMed Leptospira IgM Duo Rapid test).
RESULTS: Out of the 50 clinically suspected patients sampled, 19 were confirmed positive for leptospirosis. Six (12%) were confirmed by MAT and 13 (26%) by PCR. Similarly, of the 50 clinically suspected cases, 17 (34%) showed positivity for Leptocheck-WB and 7 (14%) for ImmuneMed Leptospira IgM Duo Rapid test. The overall sensitivity and specificity was 47.37% and 80.65% for Leptocheck-WB, and 21.05% and 90.32% for ImmuneMed Leptospira IgM Duo Rapid test. In another set of previously confirmed MAT positive samples (1:400-1:3600) obtained from a reference laboratory, Leptocheck-WB showed higher sensitivity (90.72%) than ImmuneMed Leptospira IgM Duo Rapid test (40.21%), and comparable specificity for ImmuneMed Leptospira IgM Duo Rapid test (88.89%) and Leptocheck-WB (82.86%).
CONCLUSION: The sensitivity was higher for Leptocheck-WB and had a comparable specificity with ImmuneMed Leptospira IgM Duo Rapid test. Therefore, based on the present study, Leptocheck-WB is found to be a more sensitive rapid immunodiagnostic test for acute leptospirosis screening in hospital settings.

Matched MeSH terms: Immunoassay/methods*
Evaluation of a method to determine the natural occurrence of aflatoxins in commercial traditional herbal medicines from Malaysia and Indonesia

Ali N, Hashim NH, Saad B, Safan K, Nakajima M, Yoshizawa T

Food Chem Toxicol, 2005 Dec;43(12):1763-72.
PMID: 16019122

Traditional herbal medicines, popularly known as 'jamu' and 'makjun' in Malaysia and Indonesia, are consumed regularly to promote health. In consideration of their frequent and prolonged consumption, the natural occurrence of aflatoxins (AF) in these products was determined using immunoaffinity column clean-up and high-performance liquid chromatography with pre-column derivatization. The evaluated method, which entails dilution of sample extracts with Tween 20-phosphate buffered saline (1:9, v/v) and a chromatographic system using isocratic mobile phase composed of water-methanol-acetonitrile (70:20:10, v/v/v), was effective in separating AFB1, AFG1 and AFG2 from interference at their retention times. Results were confirmed using post-column derivatization with photochemical reactor. For 23 commercial samples analyzed, mean levels (incidence) of AFB(1), AFB(2) and AFG1 in positive samples were 0.26 (70%), 0.07 (61%) and 0.10 (30%) microg/kg, respectively; one sample was positive for AFG2 at a level of 0.03 (4%) microg/kg. In contrast to the high levels of AF in crude herbal drugs and medicinal plants reported previously by other researchers, the low contamination levels reported in this study may be attributed to the higher selectivity to AF of the method applied. Based on the AFB1 levels and the daily consumption of positive samples, a mean probable daily intake of 0.022 ng/kg body weight was calculated.

Matched MeSH terms: Immunoassay/methods
Heavy/light chain assay in the monitoring of multiple myeloma

Ting HY, Sthaneshwar P, Bee PC, Shanmugam H, Lim M

Pathology, 2019 Aug;51(5):507-511.
PMID: 31253381 DOI: 10.1016/j.pathol.2019.04.002

Serum protein (SPE) and immunofixation electrophoresis (IFE) have been extensively validated for the routine use of identifying, characterising and quantifying monoclonal proteins. However, accurate quantitation of IgA monoclonal proteins can be difficult when they migrate in to the β fraction, due to co-migration with transferrin and complement components. The heavy/light chain (HLC) immunoassay is an additional tool for measuring intact immunoglobulin monoclonal proteins. Therefore, we aimed to examine the clinical utility of the HLC assay for the disease monitoring of IgG and IgA multiple myeloma (MM) patients. A total of 177 samples from 30 MM patients (21 IgG and 9 IgA) were analysed retrospectively with median number of six follow up samples per patient (range 3-13). Serum free light chains (sFLC) and HLC were quantified using Freelite and Hevylite immunoassays. Details of M-protein concentration, β-globulin levels, total immunoglobulin levels and disease treatment response were obtained from the laboratory and patient information system. Passing-Bablok regression analysis was performed to compare (i) M-protein quantification with involved HLC (iHLC) and (ii) total immunoglobulin with summated HLC pairs for each immunoglobulin type (e.g., IgGκ+IgGλ). For 127 IgG MM samples, IgG iHLC levels showed a good correlation with SPE quantification (iHLC y=0.96x+4.9; r=0.917) and summated HLC showed a good correlation with total IgG concentration (summated HLC y=0.94x+5.74; r=0.91). In total, 95/127 (75%) IgG MM follow-up samples had an abnormal HLC ratio and 122/127 (96%) had a positive SPE, probably due to the lower sensitivity of HLC assay in detecting clonality in patients with IgG MM. Consistent with this, one patient assigned a very good partial response by International Myeloma Working Group criteria would be assigned a complete response based on HLC measurements. For 50 IgA MM samples, 42/50 (84%) had an abnormal HLC ratio. Conversely, 50/50 (100%) of M-proteins showed β fraction migration and were difficult to accurately quantify by SPE. Therefore, M-protein concentration and iHLC did not correlate as well in IgA MM (y=1.9x-8.4; r=0.8) compared to IgG MM. However, there was good correlation between total IgA and summated IgA HLC (IgAκ+IgAλ y=1.35x-0.33; r=0.95). Of the 8/50 (16%) IgA samples with a normal HLC ratio, 6/8 (75%) were consistent with the disease status being in complete remission. Interestingly, in one IgA MM patient, SPE and IFE were negative, but the serum FLC ratio and involved FLC were highly abnormal, consistent with the presence of light chain escape. Our data suggest HLC measurements could add value to the current disease monitoring of MM patients. In IgG MM patients, the M-protein level correlated well with HLC values. The HLC assay complements the serum FLC assay and is especially useful for monitoring of IgA MM patients who display M-proteins migrating in the β region on SPE.

Matched MeSH terms: Immunoassay/methods*
Portable electrochemical immunosensor for detection of Mycobacterium tuberculosis secreted protein CFP10-ESAT6 in clinical sputum samples

Mohd Azmi UZ, Yusof NA, Abdullah J, Alang Ahmad SA, Mohd Faudzi FN, Ahmad Raston NH, et al.

Mikrochim Acta, 2021 01 06;188(1):20.
PMID: 33404779 DOI: 10.1007/s00604-020-04669-x

An early detection of Mycobacterium tuberculosis is very important to reduce the number of fatal cases and allow for fast recovery. However, the interpretation of the result from smear microscopy requires skilled personnel due to the propensity of the method to produce false-negative results. In this work, a portable, rapid, and simple sandwich-type immunosensor reader has been developed that is able to detect the presence of M. tuberculosis in sputum samples. By using sandwich-type immunosensor, an anti-CFP10-ESAT6 antibody was immobilized onto the graphene/polyaniline (GP/PANI)-modified gold screen-printed electrode. After incubation with the target CFP10-ESAT6 antigen, the iron/gold magnetic nanoparticles (Fe3O4/Au MNPs) conjugated with anti-CFP10-ESAT6 antibody were used to complete the sandwich format. Differential pulse voltammetry (DPV) technique was used to detect the CFP10-ESAT6 antigen at the potential range of 0.0-1.0 V. The detection time is less than 2 h. Under optimal condition, CFP10-ESAT6 antigen was detected in a linear range from 10 to 500 ng mL-1 with a limit of detection at 1.5 ng mL-1. The method developed from this process was then integrated into a portable reader. The performance of the sensor was investigated and compared with the standard methods (culture and smear microscopy). It provides a good correlation (100% sensitivity and 91.7% specificity) with both methods of detection for M. tuberculosis in sputum samples henceforth, demonstrating the potential of the device as a more practical screening tool.Graphical abstract.

Matched MeSH terms: Immunoassay/methods
Fulltext Multi-center Performance Evaluations of Tacrolimus and Cyclosporine Electrochemiluminescence Immunoassays in the Asia-Pacific Region

Qin X, Rui J, Xia Y, Mu H, Song SH, Raja Aziddin RE, et al.

Ann Lab Med, 2018 Mar;38(2):85-94.
PMID: 29214751 DOI: 10.3343/alm.2018.38.2.85

BACKGROUND: The immunosuppressant drugs (ISDs), tacrolimus and cyclosporine, are vital for solid organ transplant patients to prevent rejection. However, toxicity is a concern, and absorption is highly variable across patients; therefore, ISD levels need to be precisely monitored. In the Asia-Pacific (APAC) region, tacrolimus and cyclosporine concentrations are typically measured using immunoassays. The objective of this study was to assess the analytical performance of Roche Elecsystacrolimus and cyclosporinee electrochemiluminescence immunoassays (ECLIAs).
METHODS: This evaluation was performed in seven centers across China, South Korea, and Malaysia. Imprecision (repeatability and reproducibility), assay accuracy, and lot-to-lot reagent variability were tested. The Elecsys ECLIAs were compared with commercially available immunoassays (Architect, Dimension, and Viva-E systems) using whole blood samples from patients with various transplant types (kidney, liver, heart, and bone marrow).
RESULTS: Coefficients of variation for repeatability and reproducibility were ≤5.4% and ≤12.4%, respectively, for the tacrolimus ECLIA, and ≤5.1% and ≤7.3%, respectively, for the cyclosporine ECLIA. Method comparisons of the tacrolimus ECLIA with Architect, Dimension, and Viva-E systems yielded slope values of 1.01, 1.14, and 0.897, respectively. The cyclosporine ECLIA showed even closer agreements with the Architect, Dimension, and Viva-E systems (slope values of 1.04, 1.04, and 1.09, respectively). No major differences were observed among the different transplant types.
CONCLUSIONS: The tacrolimus and cyclosporine ECLIAs demonstrated excellent precision and close agreement with other immunoassays tested. These results show that both assays are suitable for ISD monitoring in an APAC population across a range of different transplant types.

Matched MeSH terms: Immunoassay*
Fulltext Evaluation of Elecsys Syphilis Assay for Routine and Blood Screening and Detection of Early Infection

Kremastinou J, Polymerou V, Lavranos D, Aranda Arrufat A, Harwood J, Martínez Lorenzo MJ, et al.

J Clin Microbiol, 2016 09;54(9):2330-6.
PMID: 27358468 DOI: 10.1128/JCM.02544-15

Treponema pallidum infections can have severe complications if not diagnosed and treated at an early stage. Screening and diagnosis of syphilis require assays with high specificity and sensitivity. The Elecsys Syphilis assay is an automated treponemal immunoassay for the detection of antibodies against T. pallidum The performance of this assay was investigated previously in a multicenter study. The current study expands on that evaluation in a variety of diagnostic settings and patient populations, at seven independent laboratories. The samples included routine diagnostic samples, blood donation samples, samples from patients with confirmed HIV infections, samples from living organ or bone marrow donors, and banked samples, including samples previously confirmed as syphilis positive. This study also investigated the seroconversion sensitivity of the assay. With a total of 1,965 syphilis-negative routine diagnostic samples and 5,792 syphilis-negative samples collected from blood donations, the Elecsys Syphilis assay had specificity values of 99.85% and 99.86%, respectively. With 333 samples previously identified as syphilis positive, the sensitivity was 100% regardless of disease stage. The assay also showed 100% sensitivity and specificity with samples from 69 patients coinfected with HIV. The Elecsys Syphilis assay detected infection in the same bleed or earlier, compared with comparator assays, in a set of sequential samples from a patient with primary syphilis. In archived serial blood samples collected from 14 patients with direct diagnoses of primary syphilis, the Elecsys Syphilis assay detected T. pallidum antibodies for 3 patients for whom antibodies were not detected with the Architect Syphilis TP assay, indicating a trend for earlier detection of infection, which may have the potential to shorten the time between infection and reactive screening test results.

Matched MeSH terms: Immunoassay/methods*
Horseradish peroxidase-labeled silver/reduced graphene oxide thin film-modified screen-printed electrode for detection of carcinoembryonic antigen

Lee SX, Lim HN, Ibrahim I, Jamil A, Pandikumar A, Huang NM

Biosens Bioelectron, 2017 Mar 15;89(Pt 1):673-680.
PMID: 26718548 DOI: 10.1016/j.bios.2015.12.030

In this study, a disposable and simple electrochemical immunosensor was fabricated for the detection of carcinoembryonic antigen. In this method, silver nanoparticles (AgNPs) were mixed with reduced graphene oxide (rGO) to modify the surface of screen-printed carbon electrode (SPE). Initially, AgNPs-rGO modified-SPEs were fabricated by using simple electrochemical deposition method. Then the carcinoembryonic antigen (CEA) was immobilized between the primary antibody and horseradish peroxidase (HRP)-conjugated secondary antibody onto AgNPs-rGO modified-SPEs to fabricate a sandwich-type electrochemical immunosensor. The proposed method could detect the CEA with a linear range of 0.05-0.50µgmL-1 and a detection limit down to 0.035µgmL-1 as compared to its non-sandwich counterpart, which yielded a linear range of 0.05-0.40µgmL-1, with a detection limit of 0.042µgmL-1. The immunosensor showed good performance in the detection of carcinoembryonic antigen, exhibiting a simple, rapid and low-cost. The immunosensor showed a higher sensitivity than an enzymeless sensor.

Matched MeSH terms: Immunoassay/economics; Immunoassay/instrumentation*
Fulltext Kinetic analysis of IgM monoclonal antibodies for determination of dengue sample concentration using SPR technique

Jahanshahi P, Wei Q, Jie Z, Ghomeishi M, Sekaran SD, Mahamd Adikan FR

Bioengineered, 2017 May 04;8(3):239-247.
PMID: 27533620 DOI: 10.1080/21655979.2016.1223413

Surface plasmon resonance (SPR) sensing is recently emerging as a valuable technique for measuring the binding constants, association and dissociation rate constants, and stoichimetry for a binding interaction kinetics in a number of emerging biological areas. This technique can be applied to the study of immune system diseases in order to contribute to improved understanding and evaluation of binding parameters for a variety of interactions between antigens and antibodies biochemically and clinically. Since the binding constants determination of an anti-protein dengue antibody (Ab) to a protein dengue antigen (Ag) is mostly complicated, the SPR technique aids a determination of binding parameters directly for a variety of particular dengue Ag_Ab interactions in the real-time. The study highlights the doctrine of real-time dengue Ag_Ab interaction kinetics as well as to determine the binding parameters that is performed with SPR technique. In addition, this article presents a precise prediction as a reference curve for determination of dengue sample concentration.

Matched MeSH terms: Immunoassay/instrumentation*; Immunoassay/methods
Anti-cyclic citrullinated peptide autoantibodies (anti-CCP) in Malaysian patients with rheumatoid arthritis. [Abstract]

Yuslina MY, Shahnaz M, Too CL, Hussein H, Wahinuddin S, Eashwary M, et al.

APLAR Journal of Rheumatology, 2006;9 Suppl 1:A187-A188.

Background: Anti-cyclic citrullinated peptide autoantibodies (anti-CCP) is a new serological test for the diagnosis of rheumatoid arthritis (RA). It is an enzyme immunoassay (EIA) for the detection of antibodies directed toward citrullinated peptides. Studies show this test has an improved diagnostic value compared to rheumatoid factor (RF). Objective: To determine the sensitivity and specificity of anti-CCP in patients with rheumatoid arthritis and other rheumatic diseases. Method: 227 serum samples for rheumatology clinics (Putrajaya, Taiping, and Ipoh Hospital) were tested for the presence of anti-CCP and rheumatoid factor (RF). These included 171 patients diagnosed with RA and 56 from other rheumatic diseases. Patient demographic data, clinical diagnosis, radiographic information and other laboratory data were obtained from the patients' clinical notes. Results: Anti-CCP antibodies were detected in 76.6% (131/171) patients with RA and 17.9% (10/56) patients with other arthritis. The sensitivity and specificity of anti-CCP reactivity at the optimal cut off values were 66.1% and 87.5% respectively. The sensitivity of anti-CCP was higher than that for RF (41.8%). However, the presence of either anti-CCP or RF improved the sensitivity to 76.2%. Conclusion: The detection of anti-CCP alone maybe useful in the diagnosis of RA. However, when used concomitantly with RF, it can improve the diagnostic ability significantly.

Matched MeSH terms: Immunoassay
Usefulness of paired samples for the Serodiagnosis of toxoplasmosis infection in a tertiary teaching Hospital in Malaysia

Thangarajah P, Hajissa K, Wong WK, Abdullah MA, Ismail N, Mohamed Z

BMC Infect Dis, 2019 Feb 28;19(1):202.
PMID: 30819141 DOI: 10.1186/s12879-019-3830-9

BACKGROUND: Accurate diagnosis of Toxoplasma gondii (T. gondii) infection remains elusive and requires a comprehensive assessment through laboratory and clinical investigation. In this study, a diagnostic algorithm based on paired serum samples and clinical data was developed and evaluated.
METHODS: A total of 1267 suspected cases of Toxoplasma infection were enrolled in this study from January 2016 to December 2016. The cases were screened for anti-Toxoplasma IgM and IgG by electrochemiluminiscence immunoassay (ECLIA) method. Based on the serological profiles, all cases with first seropositive serum samples were considered as suggestive cases of Toxoplasma infection. Thus, second serum samples were obtained after an interval of 2 weeks. The diagnosis was made based on laboratory results and clinical data.
RESULTS: A total of 482 T. gondii seroreactive cases were selected. The patient's records were traced and the data were analysed. Accordingly, 152 cases were diagnosed as clinically confirmed cases; 198 cases were clinically asymptomatic and 132 cases were newborn babies or infants who did not have toxoplasmosis and only acquired passive immunity from their mothers. The paired serum algorithm allowed classifying the seroreactive cases as follows: early (0.6%), acute (1.9%), reactivation (13.5%), recent (1.5%), passive immunity from mother (27.3%) and possible congenital infections (1.2%). In addition, cases of reactivated toxoplasmosis were detected among the pregnant mothers (13/82; 15.8%), children aged above 1 year (2/8; 25.0%) and immunocompetent mothers (5/135; 3.7%). Furthermore, the application of the paired serum analysis resulted in remarkably improved treatment initiation.
CONCLUSIONS: Toxoplasmosis diagnosis and treatment can be improved through the use of paired serum diagnostic algorithm.

Matched MeSH terms: Immunoassay
Highly sensitive and specific graphene/TiO2 impedimetric immunosensor based on plant-derived tetravalent envelope glycoprotein domain III (EDIII) probe antigen for dengue diagnosis

Siew QY, Pang EL, Loh HS, Tan MTT

Biosens Bioelectron, 2021 Mar 15;176:112895.
PMID: 33358432 DOI: 10.1016/j.bios.2020.112895

This study reports on the development of a novel impedimetric immunosensor design using plant-derived antigenic glycoprotein for the detection of dengue virus (DENV) IgG antibodies. The electrochemical immunosensor platform was constructed using screen-printed carbon electrode (SPCE) modified with graphene/titanium dioxide (G/TiO2) nanocomposite to improve the electrode in terms electrochemical performance and specific surface area. A plant-derived dengue envelope domain III (EDIII) protein was used as the antigenic probe protein in this immunosensing strategy. Under optimised sensing conditions, the immunosensor demonstrated high sensitivity towards DENV IgG in a wide linear working range (62.5-2000 ng/mL), with a limit of detection of 2.81 ng/mL. The immunosensor showed high specificity for discriminating DENV IgG against antibodies of other infectious disease, including the closely related Zika virus (ZIKV). The reliability of the immunosensor in serological diagnosis was verified by challenging the immunosensor against serum samples, compared to conventional enzyme-linked immunosorbent assay (ELISA). As shown by its remarkable performance throughout the study, the devised immunosensor is proposed as a reliable and practical diagnostic tool for the serological detection of dengue in realistic applications.

Matched MeSH terms: Immunoassay
Fulltext Clinical value of a rapid fully automated thyroid autoantibody assay in the diagnosis and management of graves disease

Hanita, O., Azura, N.R., Faizal, M.M.Z.

Medicine & Health, 2012;7(1):24-31.
MyJurnal

The most common cause of hyperthyroidism is Graves disease (GD) which is characterised by the presence of autoantibodies which binds to the TSH receptor (TRAb). Recently, a rapid, fully automated electrochemiluminescent immunoassay ElecsysAnti-TSHR for detection of autoantibodies to TSH receptor was made available for routine clinical use. The objective of this study is to evaluate this assay and to determine the sensitivity, specificity and cut-off value. Interassay and total imprecision (CV) were determined at 3.78-7.02 IU/L and 13.5-21.2 IU/L respectively. A total of 124 samples which comprised of 46 GD, seven Hashimoto thyroiditis (HD), 11 non autoimmune nodular goitre (NAG), 2 thyroid cancers (Ca) and 58 normal controls were retrospectively analysed to determine the sensitivity, specificity and cut-off value. Inter-assay CV’s were 2.4% at a concentration of 3.90 IU/L (range: 3.78-7.02 IU/l) and 0.8% at 20.80 IU/L (range:13.5-21.2 IU/l). Total imprecision was 3.8% at a concentration of 3.80 IU/L (range:13.5-21.2 IU/l) and 1.0% at 20.8 IU/L (range:13.5-21.2 IU/l). The ROC analysis of patients with GD, other thyroid disorders and normal controls revealed that the highest sensitivity (94%) and specificity (98%) were seen at cut-off value of 1.69 IU/L. Positive predictive value (PPV) and negative predictive value (NPV) was 95% and 94% respectively. At this derived cut-off value of 1.69 IU/L, we found that the sensitivity of TRAb positivity within the group of 29 newly diagnosed GD patients was 94%. Our results demonstrate that this fully automated assay with testing time of 27 minutes has high sensitivity in detecting GD and high specificity for discriminating other thyroid disease and represent major improvement in the diagnosis and management of patients with thyroid diseases.

Matched MeSH terms: Immunoassay

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