Automated enzyme immunoassay for lutropin with the Abbott IMx analyzer.

1989 ◽  
Vol 35 (12) ◽  
pp. 2333-2335 ◽  
Author(s):  
K A Ford ◽  
H N Baker ◽  
J G Baar ◽  
D Balay ◽  
D Marlewski ◽  
...  
Keyword(s):  
Enzyme Immunoassay ◽  
Clinical Diagnosis ◽  
Cross Reactivity ◽  
Medium Size ◽  
Plasma Samples ◽  
Double Antibody ◽  
Human Choriogonadotropin ◽  
High Concentrations ◽  
Reproductive Pathology

Abstract An automated enzyme immunoassay for human lutropin for use with the Abbott IMx analyzer is described. The assay provides results in approximately 40 min with a sensitivity of 0.25 int. units of LH per liter for up to 23 serum or plasma samples. Cross-reactivity with follitropin (2000 int. units/L) and thyrotropin (2 int. units/L) was negligible; it was 0.016% with human choriogonadotropin (1 X 10(6) int. units/L). There was no interference by high concentrations of bilirubin (0.5 g/L), hemoglobin (7.50 g/L), or triglycerides (13.5 g/L). Intra-, inter-, and total assay CVs were less than or equal to 3.75%, less than or equal to 7.1%, and less than or equal to 7.94%, respectively. Values obtained with the IMx correlated well (r = 0.98, n = 194) with values obtained with Diagnostic Products' LH Double Antibody RIA, and Serono's LH MAIAclone assay. This assay should be useful for small to medium-size laboratories involved in the clinical diagnosis of reproductive pathology.

Evaluation of a solid-phase enzyme immunoassay for human choriogonadotropin beta subunit.

1983 ◽  
Vol 29 (11) ◽  
pp. 1964-1966 ◽  
Author(s):  
D D Davey ◽  
M M Sample ◽  
T O Oei
Keyword(s):  
Enzyme Immunoassay ◽  
Solid Phase ◽  
Cross Reactivity ◽  
Beta Subunit ◽  
Neoplastic Disease ◽  
Standard Curve ◽  
Human Choriogonadotropin ◽  
Beta Hcg ◽  
Substantial Problem ◽  
Sample Dilution

Abstract We evaluated a quantitative solid-phase enzyme immunoassay for human choriogonadotropin beta subunit (beta-HCG) with anti-beta-HCG:horseradish peroxidase conjugate, recently marketed by Abbott Laboratories. We compared results on 56 patients' serum specimens, obtained mostly for followup of neoplastic disease, with those by a competitive radioimmunoassay kit. The correlation was good, the differences being of little clinical significance. Linear regression in the low and intermediate ranges gave a slope of 0.93, a y-intercept of 0.34, and a correlation coefficient of 0.97. Precision studies yielded an interassay CV of 6.4% in the intermediate range and 13% in the low range. Sensitivity was 0.69 int. unit/L. Cross reactivity was 1 to 2% with specimens fortified with lutropin or follitropin. The only substantial problem was with linearity in the upper part of the standard curve, especially in the interval, 100-200 int. units/L. This problem is obviated by adequate sample dilution.

Double-antibody enzyme immunoassay for nortriptyline.

1978 ◽  
Vol 24 (9) ◽  
pp. 1590-1594 ◽  
Author(s):  
M N Al-Bassam ◽  
M J O'Sullivan ◽  
E Gnemmi ◽  
J W Bridges ◽  
V Marks
Keyword(s):  
Escherichia Coli ◽  
Gas Chromatography ◽  
Enzyme Activity ◽  
Enzyme Immunoassay ◽  
Cross Linking ◽  
Plasma Samples ◽  
Double Antibody ◽  
Radioimmunoassay Method

Abstract beta-D-Galactosidase (EC 3.2.1.23) from Escherichia coli was conjugated to desmethylnortriptyline by means of a bifunctional cross-linking reagent, dimethyl adipimidate, and used in a double-antibody immunoassay for nortriptyline. Eighty percent of the enzyme activity was retained after conjugation; 75% of the enzyme was conjugated to desmethylnortriptyline. In the final immunoassay the enzyme activity of the bound fraction was determined with o-nitrophenyl-beta-D-galactopyranoside as substrate. The sensitivity, precision, and simplicity of the enzyme immunoassay compared favorable with that of a published radioimmunoassay method. Results for nortriptyline in plasma samples correlated well with those determined by either radioimmunoassay or gas-chromatography.

Automated and manual quantitative assays of choriogonadotropin in serum compared.

1987 ◽  
Vol 33 (1) ◽  
pp. 167-169 ◽  
Author(s):  
C J Beinlich ◽  
R H Carpenter
Keyword(s):  
Enzyme Immunoassay ◽  
Quantitative Agreement ◽  
Cross Reactivity ◽  
Analytical Performance ◽  
Good Quantitative Agreement ◽  
Correlation Studies ◽  
Automated Assay ◽  
Human Choriogonadotropin ◽  
Interassay Precision

Abstract We found the analytical performance of a rapid, automated assay of human choriogonadotropin (hCG) in serum, the Stratus hCG Fluorometric Enzyme Immunoassay, superior to a widely used manual assay for hCG (Hybritech Tandem-E hCG). The two assays were comparable in sensitivity; recovery; cross reactivity with lutropin, follitropin, and thyrotropin; and freedom from interference from hemoglobin and bilirubin. Patient-correlation studies indicated good quantitative agreement [Stratus hCG = (1.08 X Tandem hCG) - 4.3 int. units/L]. However, intra- and interassay precision was substantially better with the Stratus hCG assay, and this may allow earlier confirmation of pregnancy.

Total interleukin-6 in plasma measured by immunoassay

1994 ◽  
Vol 40 (1) ◽  
pp. 116-123 ◽  
Author(s):  
H Brailly ◽  
F A Montero-Julian ◽  
C E Zuber ◽  
S Flavetta ◽  
J Grassi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Monoclonal Antibodies ◽  
Enzyme Immunoassay ◽  
Interleukin 6 ◽  
Binding Proteins ◽  
Biological Fluids ◽  
Plasma Samples ◽  
Cytokine Concentration ◽  
High Concentrations

Abstract Determinations of total cytokine concentration in biological fluids by immunoassays face two major problems: the biochemical heterogeneity of the analyte and the interference of cytokine-binding proteins. We developed an ultrasensitive enzyme immunoassay for interleukin-6 (IL-6), using monoclonal antibodies and acetylcholinesterase as the tracer enzyme. The antibodies recognized recombinant and glycosylated forms of IL-6 equally. The antibodies measured dimeric recombinant IL-6, yet we could not detect IL-6 oligomers in plasma samples. We investigated the potential interference of soluble IL-6 receptor (sIL-6R), which is present at high concentrations in plasma samples (1 to 2 nmol/L). Heat treatment of the sample obviated the sIL-6R interference. Using calibrators in a plasma matrix, we demonstrated by fractionation, dilution, and recovery experiments that the immunoassay accurately measured total IL-6 in both normal and pathological serum and plasma samples.

A thyrotropin radioimmunoassay kit evaluated vs two reference assays.

1984 ◽  
Vol 30 (3) ◽  
pp. 437-439 ◽  
Author(s):  
S T Bigos ◽  
A E Pekary ◽  
J MacLean ◽  
C E Pierce ◽  
A W Reed ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Human Serum ◽  
Clinical Data ◽  
Clinical Status ◽  
Cross Reactivity ◽  
Minimum Detectable Concentration ◽  
Double Antibody ◽  
Human Choriogonadotropin ◽  
Detectable Concentration

Abstract We evaluated a double-antibody radioimmunoassay kit for thyrotropin that includes calibrators prepared in a matrix of human serum and involves overnight nonequilibrium. Results were compared with those from two reference assays for thyrotropin. The range of within-assay CVs for the kit for thyrotropin values between 0.9 and 2.4 milli-int. units/L was 2.2 to 5.3%, that for between-assay CVs was 8.3 to 30%. The estimated minimum detectable concentration of thyrotropin was 0.6 milli-int. unit/L. We saw no cross reactivity with human choriogonadotropin by any of 48 sera from pregnant women. The original lot of serum specified as thyrotropin-free contained small but measurable amounts of thyrotropin; a second lot did not. Clinical data generated with the kit and the reference assays correlated well and were consistent with the clinical status of various categories of patients.

Measurement of Plasma 1,25 Dihydroxyvitamin D Using a Novel Immunoextraction Technique and Immunoassay with Iodine Labelled Vitamin D Tracer

1997 ◽  
Vol 34 (6) ◽  
pp. 632-637 ◽  
Author(s):  
W D Fraser ◽  
B H Durham ◽  
J L Berry ◽  
E B Mawer
Keyword(s):  
Vitamin D ◽  
Solid Phase ◽  
Plasma Concentrations ◽  
Sample Volume ◽  
Cross Reactivity ◽  
Regression Equations ◽  
Vitamin D Metabolites ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D ◽  
High Concentrations

We evaluated a novel assay for the measurement of 1,25 dihydroxyvitamin D (1,25 (OH)2D). Immunoextraction of 1,25 (OH)2D is performed using a mini column containing a solid-phase monoclonal antibody followed by radioimmunoassay (RIA) using an 125I-labelled 1,25 (OH)2D derivative tracer and Sac-cell separation. The mean recovery of 1,25(OH)2D3 was 101%, linearity was excellent, inter- and intra-assay coefficients of variation were 9, 8 and 13% and 11, 10 and 14% at low, medium and high concentrations of 1,25(OH)2D3, respectively. The cross-reactivity of vitamin D metabolites was <0·0015% for 25-hydroxyvitamin D3, 24, 25 dihydroxyvitamin D3 and dihydrotachysterol and 0·54% for lα calcidol. 1,25 dihydroxyvitamin D2 cross-reactivity was 79%. The detection limit of the assay was 5pmol/L. Comparison with a commercial radio receptor assay (RRA) and an in-house RIA gave regression equations of y = 0·94x+11·8 ( r = 0·98) and y = 0·91x-1·7 ( r = 0.95), respectively, with no major discrepancies between the methods in all patient groups studied. Plasma concentrations of 1,25 (OH)2D obtained with the assay were as follows: normal, unsupplemented subjects: mean 88, range 48–155 pmol/L, n = 68, patients with chronic renal failure: mean 11, range 3–36 pmol/L, n = 27, primary hyperparathyroidism: mean 198, range 130–299 pmol/L, n = 23, Paget's disease: mean 92, range 42–149 pmol/L, n = 24, osteomalacia: mean 43, range 27–61 pmol/L, n = 9. A minimum sample volume of 300 μL is required, the hands-on time is significantly less than other commercial assays and the measuring procedure is gamma counting rather than scintillation counting. The assay offers several advantages over previous methods and should allow more laboratories to offer measurement of 1,25 (OH)2D as part of their repertoire.

scholarly journals Detection of Neprilysin-Derived BNP Fragments in the Circulation: Possible Insights for Targeted Neprilysin Inhibition Therapy for Heart Failure

2019 ◽  
Vol 65 (10) ◽  
pp. 1239-1247 ◽  
Author(s):  
Evgeniya E Feygina ◽  
Marina M Artemieva ◽  
Alexander B Postnikov ◽  
Natalia N Tamm ◽  
Marina N Bloshchitsyna ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ring Opening ◽  
Active Form ◽  
Cross Reactivity ◽  
Plasma Samples ◽  
Time Points ◽  
Positive Effects ◽  
Edta Plasma ◽  
Neprilysin Inhibition ◽  
Nep Inhibition

Abstract BACKGROUND Entresto™ is a new heart failure (HF) therapy that includes the neprilysin (NEP) inhibitor sacubitril. One of the NEP substrates is B-type natriuretic peptide (BNP); its augmentation by NEP inhibition is considered as a possible mechanism for the positive effects of Entresto. We hypothesized that the circulating products of BNP proteolysis by NEP might reflect NEP impact on the metabolism of active BNP. We suggest that NEP-based BNP cleavage at position 17–18 results in BNP ring opening and formation of a novel epitope with C-terminal Arg-17 (BNP-neo17 form). In this study, we use a specific immunoassay to explore BNP-neo17 in a rat model and HF patient plasma. METHODS We injected BNP into rats, with or without NEP inhibition with sacubitril. BNP-neo17 in plasma samples at different time points was measured with a specific immunoassay with neglectable cross-reactivity to intact forms. BNP-neo17 and total BNP were measured in EDTA plasma samples of HF patients. RESULTS BNP-neo17 generation in rat circulation was prevented by NEP inhibition. The maximum 13.2-fold difference in BNP-neo17 concentrations with and without sacubitril was observed at 2 min after injection. BNP-neo17 concentrations in 32 HF patient EDTA plasma samples ranged from 0 to 37 pg/mL (median, 5.4; interquartile range, 0–9.1). BNP-neo17/total BNP had no correlation with total BNP concentration (with r = −0.175, P = 0.680) and showed variability among individuals. CONCLUSIONS BNP-neo17 formation is NEP dependent. Considering that BNP-neo17 is generated from the active form of BNP by NEP, we speculate that BNP-neo17 may reflect both the NEP activity and natriuretic potential and serve for HF therapy guidance.

Measurement of Theophylline in Dried Blood Spots by Spectrophotometric Enzyme Immunoassay

1988 ◽  
Vol 25 (6) ◽  
pp. 650-653 ◽  
Author(s):  
J M Rattenbury ◽  
Tracy Taylor
Keyword(s):  
Enzyme Immunoassay ◽  
Dried Blood Spots ◽  
Plasma Samples ◽  
Blood Spots

A widely-used enzyme immunoassay for the measurement of theophylline in plasma (EMIT) has been adapted for use with dried blood spots. Potential interference from haemoglobin in eluates of the spots was avoided by autoclaving them prior to analysis. The method was investigated in terms of the recovery of theophylline added to samples, precision, and the correlation of results in DBS with those in plasma samples. The recoveries of some other drugs from eluates of autoclaved DBS were also investigated.

scholarly journals The clinical cross-reactivity and immunological cross-antigenicity of wheat and barley

2021 ◽  
Author(s):  
Shohei Kubota ◽  
Yuji Aoki ◽  
Tomomi Sskai ◽  
Katsumasa Kitamura ◽  
Teruaki Matsui ◽  
...  
Keyword(s):  
Oral Immunotherapy ◽  
Cross Reactivity ◽  
The Other ◽  
Enzyme Linked Immunosorbent Assay ◽  
Wheat Allergy ◽  
Extract Concentration ◽  
Low Concentrations ◽  
High Concentrations ◽  
Food Challenges ◽  
Elisa Inhibition

Background: Some patients with a wheat allergy have been reported to show clinical cross-reactivity to barley. However, it is not clear whether the development of barley allergy in patients with a wheat allergy is due to cross-antigenicity between wheat and barley. In our study, we aimed to determine the clinical cross-reactivity and immunological cross-antigenicity of wheat and barley. Methods: We compared the results of barley oral food challenges (OFCs) before oral immunotherapy (OIT) for wheat with those after OIT in nine patients with a wheat allergy to estimate the clinical cross-reactivity of wheat and barley. Moreover, we performed enzyme-linked immunosorbent assay (ELISA) inhibition and immunoblotting inhibition using serum from seven patients allergic to wheat and barley. Results: Nine patients who had positive barley-OFC results performed before OIT for wheat were all negative on barley-OFC performed after OIT. In ELISA inhibition, preincubation of serum from patients allergic to wheat and barley with a high barley extract concentration inhibited binding of IgE to wheat extract by less than 10%. On the other hand, wheat and barley extracts equally inhibited binding to barley sIgE at high concentrations. In the immunoblotting inhibition test, the spots of wheat were inhibited but weakly by barley extracts, and most of the spots of barley were inhibited even by low concentrations of the wheat and barley extract. Conclusion: We showed that barley allergy associated with wheat allergy is caused by cross-reactivity from wheat. The OIT for wheat was one of the promising options for barley allergy.

scholarly journals Using a Commercially Available Enzyme Immunoassay to Quantify Testosterone in Avian Plasma

The Condor ◽  
2007 ◽  
Vol 109 (1) ◽  
pp. 181-186 ◽  
Author(s):  
Brian E. Washburn ◽  
Joshua J. Millspaugh ◽  
Dana L. Morris ◽  
John H. Schulz ◽  
John Faaborg
Keyword(s):  
Enzyme Immunoassay ◽  
Small Volume ◽  
Plasma Testosterone ◽  
Plasma Samples ◽  
Zenaida Macroura ◽  
Vireo Olivaceus ◽  
Testosterone Levels ◽  
Passerina Cyanea ◽  
Assay Procedure ◽  
Mourning Doves

Abstract Abstract Using a commercially available testosterone enzyme immunoassay (EIA), we developed and validated an assay procedure for determining testosterone levels in small-volume (20 µL) avian plasma samples. We evaluated this EIA's utility by measuring plasma testosterone levels in Mourning Doves (Zenaida macroura), White-eyed Vireos (Vireo griseus), Red-eyed Vireos (Vireo olivaceus), and Indigo Buntings (Passerina cyanea). Standard biochemical validations (e.g., parallelism, recovery of exogenous testosterone) demonstrated that the assay accurately and precisely measured testosterone in avian plasma. We compared plasma testosterone levels in males and females of all four species and Indigo Buntings in various reproductive stages to physiologically validate the assay's ability to determine biologically important changes in testosterone levels. Plasma testosterone levels were higher in males compared to females in three of four species. Prebreeding and breeding male Indigo Buntings had higher circulating testosterone levels than postbreeding males. Testosterone levels in our study were similar to reported values for other passerine species using radioimmunoassay procedures. Our results suggest that this EIA procedure is very effective for determining testosterone levels in small-volume avian plasma samples and is sensitive enough to detect biologically important changes in the gonadal activity of birds. Thus, this assay has considerable utility for measuring testosterone in small birds (<15 g), from which only small volumes of plasma (20 µL) can be collected.

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