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

Hydrocortisone, progesterone, testosterone, triiodothyronine, thyroxine, chorionic gonadotropin, prolactin, alpha-fetoprotein, luteinizing, follicle-stimulating, and thyrotropic hormones were measured in human sera and in Lyphochek Immunoassay Plus Control reference sera (Bio-Rad Laboratories, USA) using 4 commercial kits (Alkor Bio Inc. and Roche, automated analyzer Roche Cobas Core; DPC, automated analyzer Immulite; Bayer, automated analyzer ACS:180). Coordination and correlation between these kits was observed, the coordination decreasing in the series Alkor Bio/Bayer, Alkor Bio/Roche, and Alkor Bio/DPC.
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PMID:[Comparative analysis of serum analyte level measurements by commercial diagnostic kits from four manufacturers (Alkor-Bio, Roche, Diagnostic Products Corporation-DCP, and Bayer Corporation)]. 1241 3

It is known that total hip arthroplasties (THA) lead to adaptative remodeling changes resulting in periprosthetic bone loss. DEXA is recognized as the most precise and accurate method for quantifying bone mineral density (BMD) in humans. The present study compares over two years after THA, DEXA data to those of urinary deoxypyridinoline (uDPYR), a pyridinium crosslink of bone collagen fibrils proven to be a reliable bone resorption marker. 41 patients (21 postmenopausal female, 20 male) underwent cemented THA. Urinary excretion of DPYR was determined using ACS : 180 SE (Bayer Diagnostics) and normalized for creatinine excretion while periprosthetic BMD (g/cm2) was measured (QDR 4500, Hologic), at post-operative day, 3 months, 1 year and 2 years after surgery. The 7 periprosthetic subregions (R1-R7) of the Gr en method are the regions of interest for evaluating bone remodeling process. uDPYR showed a significant decrease between postoperation and 1 year: 10.6 0.80 vs 4.8 0.6 nmol/mmol, p < 0.0001 (Wilcoxon Test for paired samples and statistical significance accepted at p < 0.05) and non significant variation between 1 and 2 years. Between post-operation and 3 months global and regional BMDs decrease significantly (p < 0.04) followed by an increase in distal BMD (R3, R4, R5). During the second year BMD increases also for other regions. At 2 years BMD in distal regions is recovered except in the proximal R7 when comparing post-operation and 2 years, pattern consistent with literature. Thus, a discrepancy is observed between uDPYR and DMO results that does not allow us to use a bone resorption urinary marker to monitore local bone periprosthetic remodeling.
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PMID:[Bone remodeling assessment after total hip replacement]. 1244 32

Nonequimolar-response assays for prostate-specific antigen (PSA) are criticized for overestimating total PSA in some men without prostate cancer (PCA), and underestimating total PSA in some men with PCA. We recently studied three nonequimolar-response PSA assays that had undergone modifications. While two of the studied assays achieved equimolar-response characteristics with improved areas under receiver operating characteristic (ROC) curves (AUC), the modification of the Chiron ACS PSA assay (ACS PSA2, Chiron) failed to achieve this. Recently, the ACS assay underwent another modification (ACS PSA, Bayer), which we investigated. Sera from 305 men (155 without and 150 with PCA, PSA > or = 2 and < or = 30 microg/l, Tandem-E) were measured using both modifications of the ACS assay and equimolar-response reference methods (Tandem-R free and Tandem-E, Hybritech). Molar response relative to the reference method and clinical performance (comparison of AUCs) between the previous and new ACS assay modifications were studied. The new modification of the ACS assay (ACS PSA, Bayer) achieved equimolar-response characteristics but reported lower values (average 10%) than the Tandem-E assay. Compared to the previous modification (ACS PSA2, Chiron), a 3% improvement in AUC (p = 0.01) was found. Using results of the redesigned equimolar-response assay (ACS PSA, Bayer), we calculated that 6 of 155 men without PCA in this sample set could be spared unnecessary biopsy compared with the previous nonequimolar-response assay (ACS PSA2, Chiron) without missing additional PCA (90% sensitivity). These data provide additional evidence for clinical advantages of equimolar-response over nonequimolar-response PSA assay formats.
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PMID:A new modification of the Chiron ACS assay for total prostate-specific antigen achieves equimolar response characteristics and improves the detection of prostate cancer. 1263 56

Although prostate specific antigen (PSA) is widely used in the discrimination of benign prostatic hyperplasia (BPH) and prostate cancer, its diagnostic value is controversial due to an appreciable false positive rate. In the present study, we compared a recently introduced assay method, equimolar PSA measurement, to non-equimolar PSA measurement and also determined the diagnostic value of percent free PSA with changing total PSA (tPSA) measurements. Between April 1999 and December 2001, the sera of 61 patients with BPH and 41 with prostate cancer were examined. Total PSA and free PSA was determined using the Immulite 2000 assay system, whereas equimolar tPSA measurement was performed using Bayer PSA Q for the Chiron ACS 180 system. Comparative analysis of the two different assays revealed better diagnostic sensitivity and specificity values for equimolar tPSA measurement, which in turn would have led to 10% of the patients avoiding an unnecessary biopsy. Additionally, percent free PSA with the changing denominator of tPSA assays showed that the free PSA/equimolar tPSA ratio was the best tumor marker among the studied forms of PSA. It was concluded that equimolar tPSA measurement using recombinant Fab fragments is superior to the classical measurements with monoclonal antibodies, and that the use of percent free PSA with the equimolarly measured tPSA has better sensitivity and specificity in the discrimination of benign and malignant diseases of the prostate.
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PMID:Increased discrimination between benign prostatic hyperplasia and prostate cancer with equimolar total prostate specific antigen measurement. 1275 94

Prostate-specific antigen (PSA), the most important tumor marker for the detection of prostate cancer, exists in serum in a free, uncomplexed form (free PSA [fPSA]), and as bound to protease inhibitors (mainly alpha1-antichymotrypsin [ACT]). The measurement of complexed PSA (cPSA) concentration in serum has been shown to have better sensitivity and specificity than serum total PSA concentration. A new chemiluminescent immunoassay for cPSA for use on the Bayer ACS:180 fully automated system (Bayer Corp, Tarrytown, NY) has been developed and evaluated. The precision of the new assay was <3.9% (within-run coefficient of variation [CV]) and <5.0% (total CV). The analytical sensitivity (95% upper limit of noise at zero calibrator) was <0.03 ng/mL. A comparison of the ACS:180 cPSA results with the cPSA concentrations calculated from the ACCESS (Beckman-Coulter) PSA and fPSA assays yielded the following regression equation: ACS:180 cPSA=0.93* (calculated ACCESS cPSA)+0.43, R=0.993, n=95. The mean dilution and spike recovery for five samples were both 98%. No interference was observed from hemoglobin, triglyceride, or bilirubin (NCCLS protocol). These results indicate that the ACS:180 cPSA assay is precise, and compares well with the calculated cPSA from ACCESS total and free-PSA results.
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PMID:Evaluation of an automated chemiluminescent immunoassay for complexed PSA on the Bayer ACS:180 system. 1293 46

BACKGROUND: Reliability of cardiac troponin-I assays under real-time conditions has not been previously well studied. Most large published cTnI trials have utilized protocols which required the freezing of serum (or plasma) for delayed batch cTnI analysis. We sought to correlate the presence of the acute ischemic coronary syndrome (AICS) to troponin-I values obtained in real-time by three random-mode analyzer immunoassay systems: the Beckman ACCESS (BA), the Bayer ACS:180 (CC) and the Abbott AxSYM (AX). METHODS: This was an observational prospective study at a university tertiary referral center. Serum from a convenience sampling of telemetry patients was analyzed in real-time for troponin-I by either the BA-CC (Arm-1) or BA-AX (Arm-2) assay pairs. Presence of the AICS was determined retrospectively and then correlated with troponin-I results. RESULTS: 100 patients were enrolled in Arm-1 (38 with AICS) and 94 in Arm-2 (48 with AICS). The BA system produced 51% false positives in Arm-1, 44% in Arm-2, with negative predictive values of 92% and 100% respectively. In Arm-1, the BA and the CC assays had sensitivities of 97% and 63% and specificities of 18% and 87%. In Arm-2, the BA and the AX assays had sensitivities of 100% and 83% and specificities of 11% and 78%. CONCLUSIONS: In real-time analysis, the performance of the AxSYM and ACS:180 assay systems produced more accurate troponin-I results than the ACCESS system.
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PMID:Beckman Access versus the Bayer ACS:180 and the Abbott AxSYM cardiac Troponin-I real-time immunoassays: an observational prospective study. 1524

Endogenous digoxin-like immunoreactive factors (DLIF) may crossreact with antidigoxin antibody and falsely elevate immunoassay results. Recently, a new enzyme-linked immunosorbent chemiluminescent assay for digoxin has been available for use on the ADVIA IMS (Integrated Modular System) 800i analyzer (Bayer Diagnostics). We studied potential interference of DLIF with this new digoxin assay. We analyzed 30 serum specimens from patients who have pathologic conditions that may increase serum DLIF concentrations. These patients were never exposed to digoxin or other agents that may lead to a measurable digoxin concentration. We also analyzed 10 specimens from neonates, 10 cord blood specimens, and 10 amniotic fluid specimens. Apparent digoxin concentrations were measured using the new enzyme-linked immunosorbent digoxin assay (IMS-Digoxin), a fluorescence polarization immunoassay (FPIA), and also a chemiluminescent immunoassay (CLIA, run on ACS:180(R) system from Bayer Diagnostics). We observed measurable apparent digoxin levels with the FPIA in 4 uremic patients (range 0.21-0.36 ng/mL, digoxin equivalent), 7 patients with liver disease (range 0.21-0.72 ng/mL), and 3 patients in the third trimester of pregnancy (0.22-0.66 ng/mL). We also observed measurable DLIF concentrations with the FPIA in 2 neonates (0.22 and 0.36 ng/mL), 5 cord blood specimens (range 0.21-1.18 ng/mL), and 5 amniotic fluid specimens (0.21-0.50 ng/mL). None of these DLIF-positive specimens showed any measurable digoxin concentration using the IMS-Digoxin or the CLIA assay. When serum specimens containing elevated concentrations of DLIF but no digoxin (as measured by FPIA) were supplemented with known concentrations of digoxin, we observed falsely elevated digoxin concentrations, as expected, only by the FPIA. In contrast, we observed a good agreement between the target and observed concentrations when the new IMS-Digoxin or the CLIA assay was used. We conclude that the IMS-Digoxin assay is free from interference of DLIF.
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PMID:New enzyme-linked immunosorbent digoxin assay on the ADVIA IMS 800i system is virtually free from interference of endogenous digoxin-like immunoreactive factors. 1579 42

A microplate chemiluminescence enzyme immunoassay (CLEIA) with high sensitivity, selectivity and reproducibility was developed for the determination of free thyroxine (FT4) in human serum. A competitive assay has been utilized with horseradish peroxidase (HRP) labeled thyroxine analog in the chemiluminescence (CL) detection. The CL signal produced by the emission of photons from luminol was directly proportional to the amount of analyte. The linear range was 0.45-7.5 ng dL(-1 )and the detection limit was 0.09 ng dL(-1). Experimental conditions, such as temperature, pH, incubation time, titration level and other relevant variables upon the CL signal have been examined and optimized. A coefficient of variance of less than 16% was obtained for intra- and inter-assay precision. The present method has been successfully applied to the analysis of FT4 in human serum. The positive and negative coincidence ratios are satisfactory. Good correlations were obtained between the results by the proposed method and radioimmunoassay (RIA), as well as a Bayer ACS-180SE detection system.
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PMID:Development of a highly sensitive and selective microplate chemiluminescence enzyme immunoassay for the determination of free thyroxine in human serum. 1750 37

The investigations aimed to evaluate the usefulness of cardiac troponins as biomarkers of acute myocardial injury in the rat. Serum from female Hanover Wistar rats treated with a single intraperitoneal (IP) injection of isoproterenol (ISO) was assayed for cardiac troponin I (cTnI) (ACS: 180SE, Bayer), cTnI (Immulite 2000, Diagnostic Products Corporation) and cardiac troponin T (cTnT) (Elecsys 2010, Roche). In a time-course study (50.0 mg/kg ISO), serum cTnI (ACS:180SE) and cTnT increased above control levels at 1 hour postdosing, peaking at 2 hours (cTnI, 4.30 microg/L; cTnT, 1.79 microg/L), and declined to baseline by 48 hours, with histologic cardiac lesions first seen at 4 hours postdosing. The Immulite 2000 assay gave minimal cTnI signals, indicating poor immunoreactivity towards rat cTnI. In a dose-response study (0.25 to 20.0 mg/kg ISO), there was a trend for increasing cTnI (ACS:180SE) values with increasing ISO dose levels at 2 hours postdosing. By 24 hours, cTnI levels returned to baseline although chronic cardiac myodegeneration was present. We conclude that serum cTnI and cTnT levels are sensitive and specific biomarkers for detecting ISO induced myocardial injury in the rat. Serum troponin values reflect the development of histopathologic lesions; however peak troponin levels precede maximal lesion severity.
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PMID:Characterization of troponin responses in isoproterenol-induced cardiac injury in the Hanover Wistar rat. 1765 1

Testosterone, the major androgenic hormone in humans, is commonly measured to aid in the diagnosis of clinical conditions related to its excess or deficiency. In addition, testosterone measurements are used to monitor testosterone replacement-, or antiandrogen therapy. Most commonly, automated direct immunoassays have been used to measure testosterone in human serum. Their advantage compared with other methodologies, lies in high- and rapid sample throughput with minimal human intervention. However, many automated testosterone immunoassays suffer from poor accuracy at the low concentration levels (<50ng/dL) seen in women and children, or in men undergoing anti-androgen therapy. Our objective was to develop a LC-MS/MS method which measures testosterone in human serum while fulfilling the following criteria: Rapid pre-analytical sample processing with minimal manual sample manipulation; Minimize sample volume requirements; Accurate, precise and unambiguous measurement; Functional sensitivity of 5-10ng/dL; Sample throughput of at least 30 samples per hour. Our validation criteria for precision, accuracy, and linearity was to have accuracy and linearity within mean limits of +/-10%; Intra and inter-assay precision of <15% throughout the reporting range. We also wanted to compare our results to a previously validated LC-MS/MS assay which utilized a manual liquid-liquid extraction and to an automated commercial immunoassay (Bayer ACS:180). We describe here a sensitive and rapid testosterone assay based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) utilizing on-line sample extraction and multiplexing.
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PMID:Validation of a high throughput method for serum/plasma testosterone using liquid chromatography tandem mass spectrometry (LC-MS/MS). 1870 76


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