scholarly journals Alkaline phosphatase interference in immuno-enzymatic assays.

Author(s):  
OSMAN Oğuz ◽  
Huriye Serin ◽  
Fatma Hocaoğlu Emre

Background: Alkaline phosphatase (ALP) enzymes are widely used as signal amplifiers in immunoenzymatic methods. Conditions that cause ALP elevations, such as bone or liver diseases can cause interference in immunoenzymatic methods. Objective: We aimed to examine ALP's effect on immunoenzymatic assay by adding isolated pure ALP to the prepared serum pool. Material and Methods: We prepared a serum pool and divided into 4 groups. By adding isolated pure ALP at different concentrations to each group, we obtained sample groups containing ALP enzyme at concentrations of 85 U/L, 340 U/L, 870 U/L and 1570 U/L. In each group, 20-repetition of βhCG, Ferritin, FT4, TSH, Troponin I and Vit B12 tests were performed. Coefficient of variation, bias, and total error were calculated. All groups were compared by using Friedman test for paired samples. Result: After ALP addition, the calculated total error values of FT4, βhCG and troponin I tests were found to be above the acceptable error limits. There were statistically significant differences in βhCG ,FT4, troponin I and Vit B12 tests when compared to the baseline ALP level (P<0,0125).Conclusion: Isolated ALP elevations can be a source of interference for immunoenzymatic methods.KeywordsAlkaline phosphatase, ALP, bias, immunoenzymatic, total error

2018 ◽  
Vol 46 (1) ◽  
Author(s):  
Nermin Isik ◽  
Ozlem Derinbay Ekici ◽  
Ceylan Ilhan ◽  
Devran Coskun

 Background: Theileriosis is a tick-borne disease caused by Theileria strains of the protozoan species. Buparvaquone is the mostly preferred drug in the treatment theileriosis, while it is safety in sheep, has not been detailed investigated. It has been hypothesized that buparvaquone may show side effects and these effects may be defined some parameters measured from blood in sheep when it is used at the recommended dose and duration. The aim of this research was to determine the effect of buparvaquone on the blood oxidative status, cardiac, hepatic and renal damage and bone marrow function markers.Materials, Methods & Results: In this study, ten adult (> 2 years) Akkaraman rams were used. Healthy rams were placed in paddocks, provided water ad libitum, and fed with appropriate rations during the experiment. Buparvaquone was ad­ministered at the dose of 2.5 mg/kg (IM) intramuscularly twice at 3-day intervals. Blood samples were obtained before (0. h, Control) and after drug administration at 0.25, 0.5, 1, 2, 3, 4 and 5 days. The blood samples were transferred to gel tubes, and the sera were removed (2000 g, 15 min). During the study, the heart rate, respiratory rate, and body temperature were measured at each sampling time. In addition, the animals were clinically observed. Plasma oxidative status mark­ers (Malondialdehyde, total antioxidant status, catalase, glutathione peroxidase, superoxide dismutase), serum cardiac (Troponin I, creatine kinase-MBmass, lactate dehydrogenase), hepatic (Alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, gamma glutamyltransferase, total protein, albumin, globulin) and renal (Creatinine, blood urea nitrogen) damage markers and hemogram values (white blood cell, red blood cell, platelet, hemogram, hematocrit) were measured. Buparvaquone caused statistically significantly (P < 0.05) increases in the troponin I and blood urea nitrogen levels and fluctuations in alkaline phosphatase activity, but there was no any statistically significance difference determined in the other parameters.Discussion: In this study, buparvaquone was administered two times at a dose of 2.5 mg/kg (IM) at 3-day intervals. Al­though the result was not statistically significant (P > 0.05), it was determined that buparvaquone gradually increased the levels of the main oxidative stress marker, MDA, by approximately 2.8 fold. CAT and GPX levels were also found to have decreased by 2.2 fold. Buparvaquone may cause lipid peroxidation by producing free radicals. Some other antiprotozoal drugs may affect the oxidative status and may increase MDA level and decrease SOD level. In this study, MDA, which is an indicator of lipid peroxidation in vivo, was used to partially detect developing lipid peroxidation. Changes in the levels of reduced GPX and CAT enzymes could be attributed to their use in mediating the hydrogen peroxide detoxification mechanisms. The absence of significant changes in the TAS levels in this study suggests that buparvaquone may partially induce oxidative stress by producing hydrogen peroxide, but no significant changes occurred in the oxidative stress level because of the high antioxidant capacity of sheep. In this study, buparvaquone caused a statistically significant increase (P < 0.05) in the level of Tn-I, which is a marker of specific cardiac damage (P < 0.05), whereas there was no statistically (P > 0.05) significant increase in CK-MBmass. Tn-I and CK-MB levels, which are used to define heart damage in humans, have been successfully used to determine heart damage in sheep. In this research study, the statistically significant increases in Tn-I but not CK-MBmass levels could be considered indicative of mild cardiac damage.Keywords: ram, buparvaquone, safety.


Kanzo ◽  
1977 ◽  
Vol 18 (5) ◽  
pp. 314-318
Author(s):  
Hideo NISHIMURA ◽  
Daizo KAN ◽  
Junsuke NAWATA ◽  
Mituru ODAWARA ◽  
Mikio HAYAKAWA ◽  
...  

2019 ◽  
Vol 5 (2) ◽  
pp. 290-299
Author(s):  
Isabelle Danielle Piec ◽  
Beatrice Tompkins ◽  
William Duncan Fraser

Abstract Background Asfotase alfa (STRENSIQ®, Alexion Pharmaceuticals, Inc.) is the only approved treatment for patients with pediatric-onset hypophosphatasia, a disease caused by a mutation in the tissue-nonspecific alkaline phosphatase (TNSALP) gene. ALP is often used as signaling system in routine immunoassays. Because asfotase alfa contains the active site of the full ALP enzyme, it can catalyze the substrate as the antibody-conjugated ALP would within an assay. Therefore, its presence in a treated patient’s sample may generate false positive or false negative results. We investigated whether the presence of asfotase alfa within a sample induced interference in immunoassays that utilize ALP or alternative detection systems. Methods Asfotase alfa was added to samples at concentrations from 0.08–5 µg/mL and analysed on various immunoassays following manufacturer’s instructions. Results Asfotase alfa was detected in all ALP assays but ALKP1 (RayBiotech). We observed no changes in normetanephrine and noradrenaline (IBL) at any asfotase alfa concentration. However, asfotase alfa notably interfered in an oxytocin (ENZO) assay in nonextracted samples. Extraction using a C18 column eliminated the interference. No interference was observed on automated analyzers using alternative detection system (COBAS fT4 and TSH; Advia Centaur FSH, fT4; Architect LH; FSH). Immulite 2000 fT4, TSH, testosterone and hCG (ALP-based) showed no interference. However, the presence of asfotase alfa resulted in a dose-dependent increase of Troponin I signal. Conclusion The presence of asfotase alfa must be taken into consideration when analyzing blood samples in treated patients to avoid any risk of misinterpretation of false positive/negative results. It is essential that assays be tested for this possible interference.


1999 ◽  
Vol 45 (6) ◽  
pp. 822-828 ◽  
Author(s):  
David J Newman ◽  
Yemi Olabiran ◽  
William D Bedzyk ◽  
Suzette Chance ◽  
Eileen G Gorman ◽  
...  

Abstract Background: Available assays for cardiac troponin I (cTnI) yield numerically different results. The aim of this study was to compare patient values obtained from four cTnI immunoassays. Methods: We studied the Stratus® II assay, the Opus® II assay, the Access® assay, and a research-only cTnI heterogeneous immunoassay that uses the Dade Behring aca® plus immunoassay system equipped with two new noncommercial monoclonal antibodies. Because the aca plus cTnI assay is for research only, we first evaluated and analytically validated it for serum and citrated plasma. Initially, each method was calibrated using the method-specific calibrator supplied by each manufacturer; however, the aca plus cTnI assay was calibrated using patient serum pools containing cTnI and selected on the basis of increased creatine kinase MB isoenzyme and with values assigned by use of the Stratus cTnI assay. For method comparisons, individual patient sample cTnI values were determined and compared with the Stratus II assay. Results: Passing and Bablock regression analysis yielded slopes of 1.44 (r = 0.96; n = 72) for the Opus II vs Stratus II assays; 0.07 (r = 0.91; n = 72) for the Access vs Stratus II assays; and 0.90 (r = 0.91, n = 72) for the aca plus vs Stratus II assays. The recalibration of each method with a Stratus II-assigned serum pool improved, but did not entirely eliminate, the slope differences between the different assays (range, 1.00–1.16). The observed scatter in the correlation curves remained. Conclusion: There is a need to further explore the specificities of these assays with respect to the different circulating forms of cTnI.


Author(s):  
Arne Åsberg ◽  
Ingrid Hov Odsæter ◽  
Gustav Mikkelsen ◽  
Gunhild Garmo Hov

AbstractAllowable total error is usually derived from data on biological variation or from state-of-the-art of measuring technology. Here we present a new principle for evaluating allowable total error when the concentration of the analyte (the measurand) is used for prediction: What are the predictive consequences of allowable total errors in terms of errors in the estimate of the hazard ratio (HR)?We explored the effect of analytical measurement errors on Cox regression estimates of HR. Published data on Cox regression coefficients were used to illustrate the effect of measurement errors on predicting cardiovascular events or death based on serum concentration of cholesterol and on progression of chronic kidney disease to kidney failure based on serum concentrations of albumin, bicarbonate, calcium and phosphate, and urine albumin/creatinine-ratio.If the acceptable error in the estimate of the HR is 10%, allowable total errors in serum cholesterol, bicarbonate and phosphate are approximately the same as allowable total error based on biological variation, while allowable total error in serum albumin and calcium are a little larger than estimates based on biological variation.Evaluating allowable total error from its effect on the estimate of HR is universally applicable to measurands used for prediction.


2007 ◽  
Vol 21 (3) ◽  
pp. 133-139 ◽  
Author(s):  
Kinue Ooi ◽  
Katsuya Shiraki ◽  
Yoshitaka Morishita ◽  
Tsutomu Nobori

The Analyst ◽  
2015 ◽  
Vol 140 (15) ◽  
pp. 5065-5073 ◽  
Author(s):  
Yusuke Obayashi ◽  
Ryota Iino ◽  
Hiroyuki Noji

Digitalization of fluorogenic enzymatic assays through the use of femtoliter chamber array technology is an emerging approach to realizing highly quantitative bioassays with single-molecule sensitivity.


2019 ◽  
Vol 58 (1) ◽  
pp. 138-145 ◽  
Author(s):  
Federica Braga ◽  
Elena Aloisio ◽  
Andrea Panzeri ◽  
Takahito Nakagawa ◽  
Mauro Panteghini

Abstract Background Highly sensitive cardiac troponin assays (hs-cTn) are not available as point-of-care (POC) measurements. As rapid testing cannot be achieved at the expense of clinical performance, there is an urgent need to develop and rigorously validate POC hs-cTn. Konica Minolta (KM) has recently developed a surface plasmon-field enhanced fluorescence spectroscopy-based POC hs-cTn I system. Methods We validated the analytical characteristics of the KM POC system according to the international guidelines. Results Limit of blank (LoB) and limit of detection (LoD) were 0.35 and 0.62 ng/L, respectively, hs-cTn I concentrations corresponding to a total CV of 20%, 10% and 5% were 1.5, 3.9 and 11.0 ng/L, respectively. Method comparison studies showed that KM calibration was successfully traced to higher-order references. Limit of quantitation (LoQ), i.e. the hs-cTn I concentration having a total error of measurement of ≤34%, was 10.0 ng/L. The upper reference limit (URL) for 600 healthy blood donors was calculated at 12.2 ng/L (90% confidence interval [CI]: 9.2–39.2), while sex-partitioned URLs were 20.6 (males) and 10.7 ng/L (females), respectively (p < 0.0001). KM assay measured hs-cTn I concentrations >LoD in 65.7% of all reference individuals, in 76.7% of males and in 54.7% of females, respectively. Conclusions The KM system joins the characteristics of POC systems to the analytical performance of hs-cTn.


2009 ◽  
Vol 83 (1) ◽  
pp. 23-26 ◽  
Author(s):  
L.A. Marcos ◽  
A. Bussalleu ◽  
A. Terashima ◽  
J.R. Espinoza

AbstractThe prevalence of Fasciola hepatica infection, in endemic countries, in patients with established cirrhosis is unknown. We hypothesized that, in endemic countries, the presence of fascioliasis may be detected in a serum pool of cirrhotic patients. Forty-four previously stored serum samples of patients with established liver cirrhosis, in the Hospital Nacional Cayetano Heredia in Lima, Peru, were collected from 1998 to 2003 and assessed for hepatitis B, C and fascioliasis antibodies (Fas2 ELISA). Hepatitis B surface antigen (HBsAg) was positive in 8.8% (n = 34), hepatitis B core antibody (anti-HBc) in 32.5% (n = 34), hepatitis C antibodies (anti-HCV) in 9.1% (n = 33), and 9.1% (n = 44) were Fas2 ELISA positive. This disease is an example of an emerging tropical infection which can be present in chronic liver diseases, requiring greater clinician awareness especially in endemic rural areas. Further clinical studies are warranted.


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