Search Results

You are looking at 1 - 10 of 305 items for :

  • Immunoassay x
Clear All
Open access

Nikolina Babić

, Selvaag SR, Lorenz JD, Napoli JL. Determination of vitamin D status by radioimmuno - assay with an 125I-labeled tracer. Clin Chem 1993; 39: 529-33. 27. Bouve J, De Boever J, Leyseele D, Bosmans E, Dubois P, Kohen F, Vandekerckhove D. Direct enzyme immunoassay of estradiol in serum of women enrolled in an in vitro fertilization and embryo transfer program. Clin Chem 1992; 38: 1409-13. 28. Roda A, Girotti S, Piacentini AL, Preti S, Lodi S. Deve lop - ment of a sensitive, direct luminescent enzyme immuno - assay for plasma estradiol-17 beta

Open access

Gian Luca Salvagno, Davide Giavarina, Moira Meneghello, Roberta Musa, Rosalia Aloe, Giorgio Da Rin and Giuseppe Lippi

latest generation methods in patients with suspected acute coronary syndrome without persistent ST-segment elevation. Clin Chem Lab Med 2013; 51: 1727-37. 4. Lippi G, Cervellin G. Do we really need high-sensitivity troponin immunoassays in the emergency department? Maybe not. Clin Chem Lab Med 2013 Jul 30: 1-8. doi: 10.1515/cclm-2013-0524. [Epub ahead of print] 5. Apple FS. A new season for cardiac troponin assays: it’s time to keep a scorecard. Clin Chem 2009; 55: 1303-6. 6. Gaze D. Sensitive cardiac troponin assays

Open access

R.S. Zań, Z. Roliński, C.J. Kowalski, A. Bojarska-Junak and J. Madany

Abstract

This paper describes research on the levels of endogenous melatonin (MLT) in the blood serum in dogs in different seasons (March, June, September, December) and at different times of day (11:00, 12:00, 23:00, 24:00 and 1:00), using immunoassay method. Blood samples were collected in the diurnal cycle, in consecutive seasons. The conducted studies show that MLT levels undergo clear changes in both the diurnal cycle, as well as in seasonal one in this species.

Open access

Giuseppe Lippi, Gian Luca Salvagno, Antonio Fortunato, Mariella Dipalo, Rosalia Aloe, Giorgio Da Rin and Davide Giavarina

-8. 10. Farrell CJ, Martin S, McWhinney B, Straub I, Williams P, Herrmann M. State-of-the-art vitamin D assays: a comparison of automated immunoassays with liquid chromatography- tandem mass spectrometry methods. Clin Chem 2012; 58: 531-42. 11. Moon HW, Cho JH, Hur M, Song J, Oh GY, Park CM, et al. Comparison of four current 25-hydroxyvitamin D assays. Clin Biochem 2012; 45: 326-30. 12. Chen Y, Kinney L, Božović A, Smith H, Tarr H, Diamandis EP, LeBlanc A. Performance evaluation of Siemens ADVIA Centaur and Roche MODULAR Analytics E170

Open access

Rukiye Nar and Dilek Iren Emekli

. Turkish Journal of Biochemistry 2015; 40 (S1). 20. Ercan M, Bogdaycıo lu N, Akbulut ED, O uz E, Top cuo lu C et al. Assessment of the analytic performance for immunassay tests with six sigma methodology. Clin Chem Lab Med 2015; 53, Special Suppl, pp S1-S1450. 21. Aksoy N, Tekin NH, Bireroğlu N, Serin NO. Application of sigma metrics for immunoassay tests. Clin Chem Lab Med 2014; 52, Special Suppl, pp S1-S1760. 22. Theodorson E. Quality assurance in clinical chemistry: a touch of statistics and a lot of common sense. J Med

Open access

Xin Yao, Ting Wu, Cheng Zhou, Yi-min Li, Feng-cai Zhu, Qiang Yan, Wei-jin Huang, Chuan Ji, Zheng-lun Liang and Jun-zhi Wang

humans in eastern China. J Infect Dis 2006; 193:1643-1649. 21 Khuroo MS, Kamili S, Dar MY, Moecklii R, Jameel S. Hepatitis E and long-term antibody status. Lancet 1993; 341:1355. 22 Myint KS, Endy TP, Shrestha MP, Shrestha SK, Vaughn DW, Innis BL, et al. Hepatitis E antibody kinetics in Nepalese patients. Trans R Soc Trop Med Hyg 2006;100:938-941. 23 Innis BL, Seriwatana J, Robinson RA, Shrestha MP, Yarbough PO, Longer CF, et al. Quantitation of immunoglobulin to hepatitis E virus by enzyme immunoassay. Clin Diagn Lab

Open access

A.L. Ahmad, N. Ideris, B.S. Ooi, S.C. Low and A. Ismail

LITERATURE CITED 1. Wasunna, A.A. (2007). Health Demands in Developing Country . Pennsylvania, USA: Elsevier B.V. 2. Yuan, Z., Chen, W., Zhang, J., Zhang, J., Xiang, T., Hu, J., Wu, Z., Du, X., Huang, A. & Zheng, J. (2012). Development of an immunoassay for differentiating human immunodeficiency virus infections-from vaccine-induced immune response in Tiantan vaccine trials in China. Clin Biochem. 45(15), 1219–1224. DOI: 10.1016/j.clinbiochem.2012.05.013. 3. Ivo dos Santos, J., Galvao-Castro, B., Mello, D.C., Pereira, H.G. & Pereira, M.S. (1987

Open access

Snežana Jovičić, Svetlana Ignatović, Ranka Kangrga, Anđelo Beletić, Duško Mirković and Nada Majkić-Singh

Summary

Determination of 25-hydroxyvitamin D [25(OH)D] represents a unique challenge, considering its lipophilic na - ture. Considering the widespread prevalence of vitamin D deficiency, which leads to increasing number of requests for 25(OH)D determination, immunoassay measurements adjusted to automated analyzers are being developed. Because of the variability among assays, it is often difficult to monitor vitamin D status and supplementation. The aim of this study was to compare the results of two immunoassays with high performance liquid chromatography with ultraviolet detection (HPLC-UV). Also, the aim was to estimate vitamin D status, since up to date the prevalence of vitamin D deficiency in Serbia was not examined. We have evaluated analytical characteristics of two automated immunoassays for 25(OH)D determination, from Roche (CobasR e601) and Abbott (Architect). For comparison studies we used HPLC analysis of 25-(OH)-Vitamin D3/D2 from Chromsystems (Waters isocratic system). In order to estimate vitamin D status in general population, we have searched the database of the laboratory information system and analyzed the data from 533 patients whose 25(OH)D was determined together with intact parathyroid hormone (iPTH). For imprecision assessment, four serum pools were prepared with following 25(OH)D concentrations: 35 nmol/L, ∼50 nmol/L, ∼75 nmol/L and ∼125 nmol/L. Obtai ned CVs for Roche method were 1.5-2.8% for within-run and 4.0-6.7% for between-run imprecision. For Abbott method, CVs were 0.7-4.4% for within- run and 3.8-7.2% for between-run imprecision. Inaccuracy was analyzed with commercial control sera. Obtained deviations from target value were 2.1% for Roche assay and 1.3-1.5% for Abbott method, and were not statistically significant (P>0.05). Comparison of Roche and HPLC-UV methods using Passing-Bablok regression analysis gave the following equation for the regression line y=0.937x+9.518 (r=0.739; n=97) and the regression line equation from the comparison of Abbott and HPLC-UV methods was y=0.745x+10.343 (r=0.793; n=97). Mean difference and SD for Bland-Altman plot were -4.5 nmol/L and 21.75 nmo/L, respectively for Roche method and 6.4 nmol/L and 18.8 nmol/L, respectively for Abbott. Statistical analysis (Chi-square test) of frequency distribution among different vitamin D status categories (<25 nmol/L severe deficiency, 25-50 nmol/L deficiency, 50-75 nmol/L insufficiency and >75 nmol/L sufficiency) showed that the frequency distribution obtained with Abbott method was significantly different from the distribution of the HPLC results, in contrast to Roche results frequency distribution which did not differ significantly. Also, statistical analysis of the agreement between the three methods for each vitamin D status category showed that results of both Roche and Abbott methods were significantly higher than HPLC in the two deficiency categories (P=0.005 for Roche, P=0.0407 for Abbott), and in the sufficiency category Abbott method significantly underestimated concentration of 25(OH)D compared to HPLC results (P<0.0001). Median population values of 25(OH)D and iPTH were 41.8 nmol/L and 76.6 ng/L, respectively. ANOVA analyses showed significant (P<0.05) decrease in iPTH and Ca2+ concentrations across the 25(OH)D concentration categories. Stepwise multiple linear regression analysis indicated independent correlation of iPTH with 25(OH)D concentration (b=-0.290, P=0.0008). Also, one-way ANOVA with Student-Newman-Keuls test demonstrated that 25(OH)D concentrations measured in summer and autumn were significantly (P<0.001) higher compared to those determined in winter and spring. Despite acceptable imprecision and inaccuracy of both examined methods, results obtained with them did not correlate well with HPLC-UV (r<0.9), which was used as a reference. However, methods showed satisfactory ability to classify patients into vitamin D status categories, which is important for diagnosis of vitamin D deficiency and therapy follow-up. About two thirds (68.5%) of the examined po pulation had vitamin D deficiency (25(OH)D<50 nmol/L) and only 8% had sufficient 25(OH)D concentration (>75 nmol/L).

Open access

Ljerka Prester, Irena Karačonji and Jelena Macan

Determination of mite Allergens in House Dust Using the Enzyme Immunoassay

The aim of this study was to determine the level of two major mite allergens Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1) in 30 urban homes in Zagreb, Croatia, using the enzyme immunoassay with two monoclonal antibodies which has been established as the reference method for indoor allergen analysis. Dust samples were taken by vacuuming a carpeted area and collected on cellulose filters. The ranges of Der p 1 and Der f 1 were (0.1-12.5) μg g-1 (median 0.32 μg g-1) and (0.1-31.2) μg g-1 (median 0.35 μg g-1), respectively. Der p 1 and Der f 1 (>2 μg g-1) associated with increased risk of sensitization to mite allergens were found in approximately 16% homes for each allergen. The sum of allergen (Der p 1 + Der f 1) exceeded the lower threshold in 27% of homes. Analytical evaluation of the ELISA assay showed satisfactory results for precision (intra-assay CV <6.9%, inter-assay CV<13.3%), accuracy (91% to 93%), and sensitivity (2 ng mL-1).

The ELISA assay for the measurement of dust mite allergens demonstrated very good analytical characteristics for routine laboratory use, and will provide the essential basis for our future studies of various indoor allergens.

Open access

Cristina Petrişor, Nadia Gherman-Ionică, Ramona Bologa, Manuela Sfichi and Natalia Hagău

Abstract

Background and aims: to assess the sensitivity and specificity for the basophil activation test (BAT) and the detection of drug-specific antibodies (IgE) in the retrospective diagnosis of β-lactam allergy by using assay- specific thresholds as resulted from the performance of receiver operating characteristics curve (ROC) analysis and to describe a sequential algorithm that might increase diagnostic sensitivity and reduce the number of patients that should undergo drug challenge tests by the joint use of in vivo and in vitro diagnostic tests. Methods: 37 patients with suspected β-lactam immediate-type hypersensitivity reactions were tested for the culprit drug. 31 healthy controls were similarly tested. BAT was performed with Flow2Cast technique (Bühlmann Laboratories, Switzerland). Drug-specific IgE antibodies were detected using “sandwich”-type radio-immunoassay (RIA) with sepharose as solid phase (Pathologie Université „H. Poincare”, France). Results: ROC curve analysis identifies an optimal threshold>1.9 for RIA positivity, with 70.3% sensitivity and 90.3% specificity. For BAT, an optimal threshold>1.97 yields 51.4% sensitivity and 90.3% specificity. 89.18% of the patients were diagnosed by the combined use of skin tests and in vitro tests results, while 10.82% of the patients had negative tests results. Conclusions: RIA seems to have higher sensitivity than BAT (70.3% versus 51.4%) for β-lactams. The joint use of allergy diagnostic tests has 89.18% sensitivity. A combination of allergologic skin tests, detection of antibiotic- specific antibodies, followed by BAT may be suitable for investigating β-lactam hypersensitivity reactions since no diagnostic test has absolute diagnostic accuracy.