Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.2.1.1 (ACS)
 78,556 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel interference with measurements of serum free thyroxine (FT4) caused by rheumatoid factor (RhF) is described. We found misleading, sometimes gross, increases of FT4 results in 5 clinically euthyroid elderly female patients with high RhF concentrations. All 5 patients had high FT4 on Abbott AxSYM or IMx analyzers. "NETRIA" immunoassays gave misleading results in 4 of the 5 patients; Amerlex-MAB in 2 of 4 patients; AutoDELFIA in 2 of the 5; and Corning ACS-180 and Bayer Diagnostics Immuno 1 in 1 of the 5. BM-ES700 system results for FT4 in these women remained within the reference range. Results for serum T4, thyroid-stimulating hormone, free triiodothyronine, thyroid-hormone-binding globulin, and FT4 measured by equilibrium dialysis were normal in all 5 patients. Drugs, albumin-binding variants, and anti-thyroid-hormone antibodies were excluded as interferences. Addition to normal serum of the RhF isolated from each of the 5 patients increased the apparent FT4 (Abbott AxSYM). Screening of 83 unselected patients demonstrated a highly significant positive correlation between FT4 (Abbott AxSYM) and RhF concentrations. Discrepant, apparently increased FT4 with a normal result for thyroid-stimulating hormone should lead to measurement of the patient's RhF concentration.
 ...
PMID:Misleading results from immunoassays of serum free thyroxine in the presence of rheumatoid factor. 919 46

We studied the performances of the 17b-estradiol determination with the Kryptor System (Cis Bio international), in assisted medical procreation cycles. The detection is based on Trace technology. We compared this method with Estradiol-6 method on ACS-180 (Bayer Diagnostics). The Kryptor method is sensitive, has a good precision and accuracy. Comparison with ACS-180 showed a good correlation but results were much higher. Patients under stimulation for assisted procreation were followed by the two methods. The results were close to those obtained with ACS-180 but significantly higher. Thus it was necessary to define the levels which have to be reached before ovulation induction.
 ...
PMID:[A new technique for measuring 17beta-estradiol using Kryptor (Cis Bio International): utilization to monitor ovulation stimulation]. 1067 16

The presence of heterophilic antibodies in the serum of a small subpopulation of individuals continues to cause false results for modern-day immunoassays. In order to determine the frequency of heterophilic antibody (HA)-related false positives within our population of positive cardiac troponin I (cTnI) patients, we assayed 200 samples using the original in-house cTnI assay (Abbott AxSYM) and the Bayer ACS:180 cTnI, which we had previously observed to be more effective at blocking HA interference. Four samples were identified as false positives based on discordant results between the two assays, as well as the correction of the false positives by treatment of the samples with heterophilic antibody blocking reagent (HBR). An 'enhanced' version of the AxSYM cTnI reagent was designed to greatly reduce or eliminate HA interference, and has now replaced the original reagents. The present study shows that the enhanced reagent significantly reduced or eliminated much of the HA interference. Comparative studies between the enhanced cTnI reagent and the original Abbott AxSYM cTnI reagent showed excellent correlation and equivalent diagnostic concordance, when HA samples were excluded from the analysis.
 ...
PMID:Performance of the enhanced Abbott AxSYM cardiac troponin I reagent in patients with heterophilic antibodies. 1068 73

The LIAISON thyroid hormone assays TSH, FT4, FT3, T4 and T3 were evaluated by determining the imprecision, the reference ranges, the functional sensitivity (TSH), the dilution characteristics (accuracy) (FT4, FT3), and the recovery after spiking (TSH, T4, T3). Furthermore, inter-method comparisons were performed with following methods: Elecsys (Roche Diagnostics; TSH), AxSYM (Abbott Diagnostics; TSH, FT4, FT3, T4), ACS:180 (Bayer Diagnostics; all analytes), Amerlex-M (Johnson & Johnson; T4) and LISO-Phase (Techno Genetics; FT4). The fully automated LIAISON random access analyser is based on microparticle immunoassays and chemiluminescence. The coefficients of variation (CV) of intra-assay imprecision were between 0.2-6.0%, except for the control sample with extremely low TSH concentrations and low T3 concentrations. Inter-assay imprecision was performed by measuring controls covering the measuring range over a period of 9 to 20 days, with CVs ranging from 2.3-16.0%. The suitability of the sample material was determined by analysing serum and samples treated with EDTA, citrate or heparin in parallel. The results showed good correlations of the thyroid hormone concentrations between serum and plasma samples except for LIAISON FT3, for which lower results were observed with EDTA-plasma. The regression analysis of correlation studies gave slopes from 0.849 to 0.957 for TSH, from 1.023 to 1.375 for FT4, from 0.670 to 0.911 for FT3, from 0.917 to 1.166 for T4 and 1.00 for T3 depending on the concentration range and the method of comparison. The LIAISON FT4 assay showed a trend towards higher values in the high concentration range when compared with the ACS:180. The ranges of thyroid hormone concentrations determined in serum taken from apparently healthy subjects were found to be in accordance with published data. The clinical sample study confirmed that the LIAISON thyroid hormone assays are sensitive methods for the differentiation of euthyroid subjects and patients with hyper- and hypothyroidism. In conclusion, the automated thyroid hormone immunoassays on the random-access LIAISON immunoassay analyser proved to be very satisfactory, both from the analytical and the clinical point of view.
 ...
PMID:Evaluation of the LIAISON thyroid chemiluminescence immunoassays. 1079 Nov 27

Measurement of urinary free cortisol using the Bayer Automated Chemiluminescent System (ACS:180 PLUS) was evaluated and compared with an in-house extraction radioimmunoassay (RIA). Inter-assay coefficients of variation were acceptable, being respectively 5.3%, 4.8% and 3.8% at 141, 406 and 942 nmol/L (n=20) for the ACS direct assay and 19.4% and 12.1% at 27 and 116 nmol/L with dichloromethane extraction (n=10). Using tritiated cortisol, mean extraction efficiency for the ACS extraction protocol was 89% compared with 104% for the RIA method (n=6, P<0.001) and using urine spiked with ACS serum calibrator, extraction efficiency was only 76% (standard deviation 8.8%, n=49) on the ACS. Urine spiked with cortisol dissolved in ethanol also gave significantly lower recoveries on the ACS for both direct and extraction methods compared with the RIA. Regression analysis of results from a mixture of control serum samples and samples from patients (n=93) showed good correlations between the direct and extraction ACS methods and the RIA extraction assay. The median concentration in 23 normal subjects and 95% reference intervals (nmol/24 h) were: ACS direct, 237 (135-505); ACS extraction, 91 (33-239); and RIA extraction, 146 (80-334). 5Beta-dihydrocortisol was the only major interferent in all assays. The ACS extraction assay showed acceptable performance and correlated well with the extraction RIA, although there was evidence of matrix-dependent effects causing low recovery.
 ...
PMID:Measurement of urinary free cortisol using the Acs:180 serum cortisol chemiluminescent immunoassay. 1090 70

Prostate specific antigen (PSA) is a glycoprotein found in the epithelial cells of the prostatic duct and acini. PSA is elevated in all four stages of prostate cancer as well as in benign prostatic hypertrophy. We evaluated a new chemiluminescent assay for PSA by comparing this assay with the microparticle enzyme immunoassay for PSA (MEIA) on the AxSYM analyzer (Abbott Laboratories, Abbott Park, IL) and a Hybritech Tandem R assay for PSA. The new chemiluminescent assay is recently available from Bayer Diagnostics (Tarrytown, NY) and can be run using the ACS: 180 Plus analyzer. Precision of the new chemiluminescent assay was evaluated using commercially available controls (Bayer Diagnostics). The within-run and total CVs were 6.4 and 8.7% for the low control (mean: 0.43 microg/L), 1.6 and 5.2% for the next level control (mean:1.94 mg/L), 4.3 and 4.9% for the medium control (mean: 2.10 mg/L), 1.2 and 3.9% for the high control 1 (mean: 11.52 mg/L), and finally 3.2 and 6.9% for the high control 2 (mean: 21.52 mg/L). The spike recovery varied from 94.2 to 109.6% for five different specimens we studied. We also observed excellent dilution recoveries. For example, in the specimen supplemented with 3.02 mg/L of PSA, the dilution recoveries were 102. 1, 104.7, and 103.7% for 1:2, 1:4, and 1:8 dilutions, respectively. We analyzed 113 serum specimens from patients with various concentrations of PSA (range 0.5 mg/L-2040 mg/L) using the new chemiluminescent assay and compared our results with the MEIA and Hybridtech (Tandem-R PSA) assays. Using x axis as the PSA concentrations obtained by the Tandem-R assay and the y axis as the PSA values obtained by the new chemiluminescent assay, we observed the following regression equations: y = 1.04 x -0.19 (r = 0.99, n = 112). One specimen with PSA concentrations of 2040 microg/L by the MEIA and 2156 microg/L by the chemiluminescent assay was not used for regression analysis. Similarly using x axis as the PSA concentrations obtained by the MEIA assay and y axis as the PSA concentrations obtained by the chemiluminescent assay, we observed the following regression equation: y = 0.88 + 0.02 (r = 0.99, n = 112). We conclude that the new chemiluminescent assay has excellent precision and the results compared well with the existing assays.
 ...
PMID:Performance evaluation of a new chemiluminescent assay for prostate specific antigen. 1090 69

Cardiac troponin I is a marker for diagnosis of myocardial damage. Several immunoassays are currently available for determination of concentrations of troponin I in serum. We evaluated a chemiluminescent assay for troponin I using ACS:180 automated analyzer (Bayer Diagnostics). We compared our results with two other immunoassays using the OPUS Magnum (OPUS troponin I assay, Dade Behring) and AxSYM (microparticle enzyme immunoassay, Abbott) analyzers. The within-run and between-run CVs were less than 5% for all three levels of controls. The chemiluminescent assay for troponin I was linear up to a serum troponin I concentration of 50 ng/mL and the detection limit was 0.1 ng/mL of troponin. A good correlation between troponin I concentration measured by the chemiluminescent assay (y axis) and the microparticle enzyme immunoassay (MEIA) (x axis) was observed, although the concentrations of troponin I in individual specimens were approximately four times higher, when measured by the MEIA assay, than those measured by chemiluminescent assay. The correlation coefficient was 0.98 with the regression equation y = 0.22x + 1.125. We also observed a good correlation in troponin I concentrations obtained by the chemiluminescent assay (y axis) and OPUS troponin I assay (x axis). The correlation coefficient was 0.96 and the regression equation was y = 0.79x - 0.52. The correlation coefficient was 0.93 when we compared troponin I concentrations obtained by the OPUS assay (x axis) with the corresponding concentrations obtained by the MEIA assay (y axis). The corresponding regression equation was y = 0.25x + 3.5. We conclude that the chemiluminescent troponin I assay showed good analytical performance.
 ...
PMID:Performance evaluation of a new chemiluminescent cardiac troponin I assay. 1101 1

The introduction of automation for immunoassays in recent years has brought about important and evident improvements in assay precision. Increasing standardization and comparability between platforms should enable the development of clinical guidelines and diagnostic algorithms for appropriate clinical decision making. A continuing source of variation between different automated immunoassay platforms is the sporadic effect of interfering antibodies or substances, thus causing aberrant results not supporting the patient's clinical status. The aim of this study was to describe current thyroid panel variation between automated immunoassay platforms including population specimens at risk of antibody interference. A multisite design with laboratories in three different countries using four different automated immunoassay platforms (Roche-Boehringer Mannheim Elecsys (Italy), Roche-Boehringer Mannheim ES300 (Wales), Bayer Immuno 1 and the Bayer ACS:180 evaluated the thyroid panel of thyrotropin (TSH), triiodothyromine (T3), free thyroxine (FT4) and free triiodothyronine (FT3). A common set of 158 randomly selected patient samples of non-thyroid and thyroid disorders, with and without treatment, was tested. Included were 62 patient samples at risk for endogenous antibody interference with high antimicrosomal antibody, anti-TSH receptor antibody and increased rheumatoid factor sub-populations. Across all controls and between platforms, precision measurements were comparable and varied between 0.7% and 12.8% for TSH, 2.8% and 13% for FT4, 1.8% and 10.5% for FT3 and 3.1% and 16% for T3 assay. Acceptable correlation and reproducibility were found between the three Bayer Immuno 1 platforms at each country's site with all four thyroid panel assays demonstrating r-values of 0.989 to 1.000 and slopes of 0.915 to 1.078. Comparisons between the different platforms showed acceptable correlation for all thyroid panel assays. Specimens containing rheumatoid factor were associated with a significantly increased variation between systems for the FT4 and FT3 assays (p < 0.01). This effect did not appear to be selective for a given platform. For specimens with raised autoimmune antibodies and therefore at risk of assay antibody interference, no variation could be observed between the platforms.
 ...
PMID:Comparative multicentre study of a panel of thyroid tests using different automated immunoassay platforms and specimens at high risk of antibody interference. 1107 Oct 74

Recently, a fully automated method has become commercially available to measure the MUC-1-associated antigen CA27.29. The present investigation was performed in order to compare CA27.29 and CA15.3 in a wide series of patients affected with breast cancer. Overall, 603 cases with breast cancer and 194 healthy controls were investigated. Patients were enrolled in 4 institutions, while assays were performed in one laboratory. CA27.29 was measured by the ACS:180 BR assay (Bayer Diagnostics) and CA15.3 by the AxSYM (Abbott Laboratories). An excellent correlation was found between the results obtained by the two methods. The two markers showed comparable results in healthy controls, with higher levels in post-menopausal than in pre-menopausal subjects. The markers were significantly higher in primary breast cancer than in controls. The areas under the receiver operating characteristics (ROC) curves of the two tests were comparable, but CA27.29 showed better sensitivity in cases with low antigen concentrations (below the cut-off point). Accordingly, when comparing each test in different stage categories, significance levels of the differences were higher for CA27.29 than for CA15.3 for all T categories versus healthy controls, for pT1 versus pT2, for all N categories versus healthy controls and for node-negative versus N1-3 patients. From the results of the present study, that has been performed on samples taken at diagnosis and prior to any treatment from the widest series of patients with primary breast cancer reported so far, we can draw the following conclusions: CA27.29 provides comparable results to CA15.3; CA27.29 seems more sensitive than CA15.3 to limited variations of tumour extension; however, it cannot help clinicians in distinguishing stage I patients from stage II patients. However, from the point of view of clinical decision making, CA27.29 provides comparable results to CA15.3. CA27.29 is therefore suitable for routine use in the management of patients with breast cancer.
 ...
PMID:CA27.29: a valuable marker for breast cancer management. A confirmatory multicentric study on 603 cases. 1123 57

We compared troponin I (TnI) assays (AxSYM [Abbott]; ACS:180 [Bayer]) in blood samples with concentrations less than 10 ng/mL (< 10 micrograms/L). Discordant results were evaluated by linearity studies and by testing for rheumatoid factor. Patients with discordant TnI results were compared with patients with concordant results and patients with negative TnI who had a new myocardial infarction or died within 2 months of initial testing. Positive TnI cutoffs by AxSYM and ACS:180 were 0.7 ng/mL (0.7 microgram/L) and 0.13 ng/mL (0.13 microgram/L), respectively. We identified 173 specimens that were repeatedly positive by at least 1 assay; 143 specimens were positive by both assays. Twenty samples positive for TnI by AxSYM were negative by ACS:180, while 10 samples positive by ACS:180 were negative by AxSYM. The discordant samples showed no evidence of interfering substances, including rheumatoid factor. Clinical follow-up showed that 26% of patients with elevated TnI by both assays, 33% with TnI positive only by AxSYM, 22% with TnI positive only by ACS:180, and 8% with negative TnI by AxSYM encountered at least 1 clinical end point. Variable detection rates by these assays for low-positive TnI represent a clinically significant problem.
 ...
PMID:Clinical significance of low-positive troponin I by AxSYM and ACS:180. 1155 68


1 2 3 Next >>