PURPOSE: Enzyme immunoassay (EIA) is now a widely used technique. We have described the application of enzyme amplification (sensitive ELISA) in the field of immunoassays of pediatric population. There are two issues with the sensitive ELISA. First is that one can minimize the serum volume, an important concern for pediatricians. The second is the problem of background signal. We demonstrate that it is possible to develop EIAs of high sensitivity and detectability with using very small volume of infant's sera immunized with Hib-PRP vaccine. METHODS: Monoclonal Abs HG11, HP6016, HK2, and KL1 specific for human IgG1, IgG2, C , and C were used. The mAb OAK-1 specific for a subfamily of V I L chains (V Ia), the mAbs KB13 and B12 specific for human V II and V III L chains were also used respectively. Adults were immunized with Hib-CRM vaccine. Immune serum was obtained 4 to 8 wk after immunization. Twenty infants received Hib-CRM vaccine at 2, 4, and 6 month of age and blood samples were obtained at 7 month old. The amount of anti-Hib-PS Ab expressing a V subgroup or V was determined by sandwich type immunoassays using conventional substrate. The amount of the enzyme immobilized to the well was determined with para-nitrophenyl phosphate substrate. A standard ELISA was performed but different substrate (lyophilized NADPH) and amplifier (alcohol dehydrogenase and diaphorase) were used to develop color in final step for enzyme amplification method. RESULTS: We get the dose-response curves obtained using the conventional and amplified detection methods in the anti-PRP Ab assay. The sensitivities of the two assay methods were compared. We can increase the sensitivities four to sixteen folds and minimize the infant's sera volume to perform varing anti-PRP antibody assays. To obtain the advantages of increased sensitivity, any background is minimized by using noncontaminated reagents. CONCLUSIONS: It is possible to develop EIAs of high sensitivity and detectability with using very small volume of infant's sera with using enzyme amplification system (sensitive ELISA).
Adult ; Antibodies* ; Child* ; Enzyme-Linked Immunosorbent Assay* ; Humans ; Immunization ; Immunoassay ; Immunoenzyme Techniques ; Immunoglobulin G ; Indicators and Reagents ; Infant ; Oxidoreductases

BACKGROUND: Clostridium difficile is one of the most important pathogens responsible for nosocomial diarrhea. The disease is mediated by two toxins, designated as A and B; therefore, identification of the toxins is important for diagnosis. However, culture or cytotoxin assay are not easily done because of tedious procedures. Instead, toxin A immunoassay is widely used. We evaluated two different enzyme immunoassays (EIA) for C. difficile toxin A and compared them with culture and PCR results. METHODS: A total of 65 stool specimens were examined for toxin A using enzyme linked fluorescent immunoassay (ELFA, VIDAS CD II, Bio-Merieux, France) and enzyme linked immunosolvent assay (ELISA, C.DIFFICILE TOX A II, TECHLAB, USA ) and were also cultured for C. difficile using cycloserine cefoxitine fructose agar. We amplified toxin A and B genes using primers NK9-NK 11 and NK104-NK105, respectively, in 23 C. difficile isolates. RESULTS: The concordance rate between ELFA and ELISA was 76.9%. The sensitivity and specificity of the ELFA and ELISA based on the culture and PCR results for toxin A gene were 84.6%/98.1% and 84.6%/67.3%. Positive and negative predictive values were 91%/96.2% in VIDAS and 78.0%/ 94.6% in TECHLAB. The positive rates of toxin B genes were 100%, 83.3% and 50% in toxin A positive, variant and negative strains, respectively. CONCLUSIONS: The sensitivities of the ELFA and ELISA for toxin A were the same, but specificity and positive predictive value of the ELFA were higher than those of the ELISA. PCR or EIA method detecting both toxin A and toxin B is strongly recommended, because the variant strains (toxin A negative and toxin B positive) of C. difficile may be more prevalent than were anticipated in Korea.
Agar ; Cefoxitin ; Clostridium difficile* ; Clostridium* ; Cycloserine ; Diagnosis ; Diarrhea ; Enzyme-Linked Immunosorbent Assay ; Fructose ; Genes, vif ; Immunoassay ; Immunoenzyme Techniques* ; Korea ; Polymerase Chain Reaction ; Sensitivity and Specificity

BACKGROUND: Elecsys 2010 immunoassay system is based on the electrochemiluminescence immunoassay using a ruthenium (II) tris (bipyridyl) label. Since it was the first time to use the system in our laboratory, we would like to evaluate the analytical performances (precision, linearity and recovery rate) and correlation with radioimmunoassay (RIA) and microparticle enzyme immunoassay (MEIA) methods. METHODS: We used precicontrol tumor marker (TM1, TM2) for alpha-fetoprotein (AFP), prostatic specific antigen (PSA) and carcinoembryonic antigen (CEA), Precicontrol universal (Ul, U2) for triiodothyronine (T3) and thyroxine (T4), Precicontrol-TSH for thyrotropin (TSH) and pooled serum for the evaluation of precision and recovery rate. Patients' sera were used for the linearity and comparison study. RESULTS: The coefficients of variatron of Imprecision study were below; 4.0%, 8.7% and 10.2%, respectively in the within-run, within-day and between-day analysis. The recovery rates were 100.5%, 96.1% and 102.5%, respectively in T4, TSH, and AFP. The linearity were y=1.02x-0.182(r=0.99) for T4, y=1.01x+0.12 (r=0.99) for TSH and y=1.01x+0.54(r=1.00) for AFP. T3, T4, TSH, CEA and PSA results showed good correlation with RIA (r>0.90), but AFP showed r=0.88. Also, AFP, CEA and PSA results showed excellent correlation with AxSYM (r>0.99). CONCLUSION: Elecsys 2010 immunoassay system showed excellent precision, recovery rate, clinically acceptable linearity and good correlation with the results obtained by RIA and MEIA methods.
alpha-Fetoproteins ; Carcinoembryonic Antigen ; Immunoassay* ; Immunoenzyme Techniques ; Radioimmunoassay ; Ruthenium ; Thyrotropin ; Thyroxine ; Triiodothyronine

Digoxin plays a part in healing of congestive heart failure in clinic. Its therapeutic dose is very approximate to toxic dose and even they overlap each other sometimes. There are many influencing factors on blood drug level of digoxin. Pharmacodynamics and pharmacokinetics varies with different individuality. It is indispensable to detecting blood drug level in order to treat disease and prevent intoxication. Integrating with the detecting-methods of blood drug level of digoxin home and broad, characteristic of many methods are summarized from sensitivity, linearity range, cross-reaction and precision. These methods include radio immunoassay, enzyme immunoassay, chemiluminescence immunoassay, fluorescence immunoassay and HPLC-MS-MS. These methods are popular for their specialized ascendancy. The cost of radio immunoassay is low. Enzyme immunoassay has good specificity. Sensitivity and stability of chemiluminescence immunoassay is very excellent. Fluorescence polarization immunoassay is sensitive and convenient. HPLC-MS-MS has high resolution and good specificity. One of the development tendencies is to combine two or more methods in detecting the blood drug level of digoxin which contribute to these methods integrated use.
Chemistry Techniques, Analytical ; methods ; Chromatography, High Pressure Liquid ; Digoxin ; blood ; Enzyme-Linked Immunosorbent Assay ; Fluorescence Polarization Immunoassay ; Fluoroimmunoassay ; Humans ; Radioimmunoassay ; Reproducibility of Results ; Tandem Mass Spectrometry

Immunology plays an important role in prevention, discovery, diagnosis and treatment. There are 4 major immunological techniques including ELISA (enzyme linked immuno-sorbent assay), ICA (immuno-chromatography assay), GLORIA (gold labeled optical read rapid immunoassay) and MCIA (membrane capture immunoassay). These techniques with the simple test devices such as test paper, test stick, test cassette provided the rapid results. The immunological techniques have been applying in emergency tests (myocardial infection, embolism, thrombosis, and occlusion), infection viral infection, allergy, cancer and drug abuse
Immunology ; Immunoassay ; Enzyme-Linked Immunosorbent Assay

The followings are the results for external quality assessment (EQA) in immunoserology for 2003: 1.Evaluation of EQA was done in 2 trials in May and November, about 99% of laboratories participating average 8.2 items. 2.In C-reactive protein (CRP), rheumatoid factor (RF) and anti-streptolysin O (ASO) tests, about 63%, 49% and 44% of the participating laboratories respectively have used quantitative assays. Because the laboratories using quanitiative assays were on the increase annually, commercial control, Liquicheck(TM) Immunology Contol from Bio-Rad Laboratories (Irvine, CA, USA) was used to assure the quality of quantitiavie results in 2003. A few laboratories reproted the outlier results, comparing with the reference ranges presented by the company. 3.Over 92% of participating laboratoreis have used imunoassays including enzyme immunoassay (EIA), microparticle EIA (MEIA), chemiluminescence immunoassay (CIA), immunochromatography assay (ICA) or radioimmunoassay (RIA) for detedting viral antigens or antibodies. Especially for anti-HCV, over 98% of participating laboratoreis have used various kind of imunoassays. Laboratories using ICA increased and about 24% of participating laboratoreis have used ICA for anti-HCV and anti-HIV. However, many laboratories using ICA for detecting anti-HCV reported false negative results, suggesting lower sensitivity of ICA than those of other immunoassays. 4.The criteria of interpretation were considered to be evaluated in Widal test and laboratories using ICA increased in serological tests for syphilis.
Allergy and Immunology ; Antibodies ; Antigens, Viral ; C-Reactive Protein ; Hepatitis B Surface Antigens ; Immunoassay ; Immunochromatography ; Immunoenzyme Techniques ; Korea* ; Luminescence ; Nephelometry and Turbidimetry ; Radioimmunoassay ; Reference Values ; Rheumatoid Factor ; Serologic Tests ; Syphilis

The followings are the results for external quality assessment (EQA) in immunoserology for 2002: 1. Evaluation of EQA was done in 2 trials in May and November, about 96% of laboratories participating average 8.3 items. 2. In C-reactive protein (CRP), rheumatoid factor (RF) and anti-streptolysin O (ASO) tests, about 40%, 53% and 52% of the participating laboratories respectively have used qualitative assays, mainly latex agglutination. And about 55%, 43% and 40% of the participating laboratories have used quantitative assays, turbidimetric immunoassay (TIA) or nephelometry in CRP, RF and ASO tests respectively. Laboratories using TIA increased and those using nephelometry decreased. The instruments which were the most frequently used in nephelometry were BN series (Dade Behring Inc., Germany). The instruments of Hitachi series (Hitachi Ltd., Japan), Cobas Integra and Mira series (Roche Diagnostics GmbH, Germany), Toshiba series (Toshiba Corporation, Japan) and Olympus AU series (Olympus Optical Co., Ltd., Japan) were frequently used in TIA. The quantitative results were quite variable according to the methods or reagents, especially in RF and ASO. 3. Over 90% of participating laboratoreis have used imunoassay including enzyme immunoassay (EIA), microparticle EIA (MEIA), chemiluminescence immunoassay (CIA), immunochromatography assay (ICA) or radioimmunoassay (RIA). Laboratories using CIA and ICA increased. Sensitivities of ICA were lower than those of other immunoassays in the results of HBsAg and anti-HCV. The sensitivity of SD HCV (Standard Diagnostics, Inc., Korea) was especially lower in anti-HCV results. Sensitivities of CIA and ICA were also lower than those of EIA including MEIA in the results of anti-HIV. 4. The criteria of interpretation were considered to be evaluated in Widal test and laboratories using ICA increased in serological tests for syphilis.
Agglutination ; C-Reactive Protein ; Hepatitis B Surface Antigens ; Immunoassay ; Immunochromatography ; Immunoenzyme Techniques ; Indicators and Reagents ; Korea* ; Latex ; Luminescence ; Nephelometry and Turbidimetry ; Radioimmunoassay ; Rheumatoid Factor ; Serologic Tests ; Syphilis

Serum IgE level and Clonorchis specific IgE in individuals with Clonorchis sinensis were determined by radioimmunosorbent(RIST) and radioallergosorbent technique(RAST) respectively. Highly significant elevations of serum IgE (P<0.001) and specific IgE antibodies (P<0.01) were observed in area from individuals with clonorchiasis. The mean values of serum IgE in individuals with clonorchiasis and healthy individuals were 2,372 IU/ml and 364 IU/ml respectively and specific IgE antibodies of both groups were 52.0 and 4.4%. A close correlation(r=0.9451) between serum IgE level and specific IgE antibodies were observed and correlation (r=0.6056) between serum IgE and EPG and between specific IgE and EPG(r=0.5693) were also observed.
parasitology-helminth-trematoda ; Clonorchis sinensis ; clonorchiasis ; immunology ; radioimmunosorbent test ; radioallergosorbent test ; IgA ; IgE ; serum

BACKGROUND: The importance and usefulness of therapeutic drug monitoring (TDM) have been emphasized, and analysis of drugs has been increased in clinical laboratories. We evaluated the analytical performance and clinical usefulness of a recently introduced enzyme multiplied immunoassay instrument, Viva-E Drug Testing System (Dade Behring Inc., USA). METHODS: Using patients' samples and quality control material, we evaluated the analytical performance of Viva-E for a total of 11 drugs (cyclosporine, tacrolimus, mycophenolic acid, valproic acid, digoxin, theophylline, carbamazepine, phenytoin, phenobarbital, vancomycin, and gentamicin) with respect to linearity, precision, and correlations with other methods according to CLSI guidelines. Cobas Integra 800 (Roche Diagnostics, Switzerland) and API 4000 LC-MS/MS System (Applied Biosystems, USA) were used to make a comparison. In addition, we analyzed analysis time. RESULTS: Viva-E showed a good linearity (r2 > or = 0.97) for all items. Within-run CVs were within 5% and total CVs were within 10% for all drugs except for tacrolimus and digoxin at low concentrations. The system correlated well with the other methods (r=0.9283-0.9778). The time required for reporting the first sample was 11 min and the analysis time was 1.1 min. CONCLUSIONS: Since Viva-E showed a good analytical performance required for TDM in its linearity, precision, and accuracy with its wide drug menus including cyclosporine, tacrolimus, and mycophenolic acid, stat and random accessing functions, and the consolidation to a single workstation, it could be very useful in the clinical laboratory for various needs.
Data Interpretation, Statistical ; Drug Monitoring/*instrumentation/methods ; Enzyme Multiplied Immunoassay Technique/*instrumentation ; Humans ; Immunoenzyme Techniques ; Pharmaceutical Preparations/*analysis ; Quality Control ; Reference Standards ; Reproducibility of Results

BACKGROUND: Since the emergence of variant Clostridium difficile strains that fail to produce detectable toxin A, diagnostic kits targeted to detect toxin A only showed a considerable rate of false negative results. The aim of this study was to evaluate a toxins A and B (toxins A/B) detection kit recently marketed in Korea, and to compare toxin positive rates before and after introduction of the new kit. METHODS: The results of 5,783 toxin A assays performed during the 7-year period from 2001 through 2007 were analyzed and compared them to the toxins A/B assay data of 519 samples obtained from January to June 2008 in a university hospital. An enzyme-linked fluorescent immunoassay for toxins A/B (VIDAS C. difficile Toxin A & B, bioMerieux SA, France: VIDAS CDAB) and PCR for toxin genes A/B were performed directly in 102 stool samples from hospitalized patients. RESULTS: The positive rates of toxin A assays tended downward annually from 2001 to 2007 (16.3%, 17.8%, 13.9%, 11.4%, 13.8%, 8.2%, and 5.8%, respectively), but increased to 12.1% in 2008 after changing to the toxin A/B detection kit. The concordant rate of the VIDAS CDAB kit with the PCR method was 82.4%. Compared to the PCR method, the sensitivity and specificity of the toxin A/B kit were 60.7% and 90.5% respectively. CONCLUSION: Testing kits for C. difficile toxin A only could result in a misdiagnosis more frequently than the testing kit for toxins A/B. The sensitivity of the newly launched toxin A/B detection kit from bioMerieux SA needs to be improved, but it showed a good specificity
Clostridium ; Clostridium difficile ; Diagnostic Errors ; Humans ; Immunoassay ; Immunoenzyme Techniques ; Korea ; Polymerase Chain Reaction ; Sensitivity and Specificity