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Background Neutrophil gelatinase-associated lipocalin (NGAL) is a new useful biomarker for the early diagnosis of acute kidney injury. The aim of the study was to compare two analytical methods for measurement of urinary NGAL: enzyme-linked immunosorbent assay (ELISA) and chemiluminescent microparticle immunoassay (CMIA). Methods Two assays were used to measure urinary NGAL: ELISA kit (R&D Systems) and ARCHITECT Urine NGAL (Abbott Laboratories). The study material was the urine obtained from 30 healthy subjects (mean age 56.4 ± 15.2). Results The median value and interquantile range of urinary NGAL in the studied group measured by ELISA (RD 6.6) and by CMIA (ARCHITECT Urine NGAL assay, Abbott Diagnostics) were 4.4 ng/ml (1.9; 9.4). Levels of urinary NGAL obtained by CMIA were significantly higher than by ELISA. There was a significant positive correlation between the concentration of urinary NGAL determined by both methods (r = 0.8625, P < 0.01). Conclusion The comparison of individual data obtained by ELISA and CMIA should be taken with care. From laboratory's point of view, ELISA is less expensive than CMIA method for the determination of NGAL in urine. However, CMIA method allows rapid determination of urinary NGAL concentration through automated assay.

Background To establish a novel method based on time-resolved immunofluorometric assay (TR-IFMA) with higher sensitivity and a broader detection range for detecting serum hepatitis B virus large surface protein (L protein). Methods The precision, sensitivity, specificity, coefficient of recovery, and stability of the assay were evaluated and comparison with the classical enzyme-linked immunosorbent assay (ELISA) was also executed. Results The precision, specificity, and sensitivity of the TR-IFMA were clearly better than ELISA. Particularly, the sensitivity was 0.1 ng/ml; moreover, the specificity was 100%, 96%, 92.5%, 96.9%, 97.8%, and 100% in the sera of healthy blood donors, systemic lupus erythematosus (SLE) patients, rheumatoid arthritis (RA) patients, hepatitis C virus (HCV) patients, cytomegalovirus (CMV) infection patients, and pregnant patients, respectively. Meanwhile, we observed that the established TR-IFMA kit has a wider acceptable linear range of 0.63–10,367 ng/ml rather than the regular commercial ELISA kit having range of only 10.12–1095.9 ng/ml. Subsequently, correlation coefficient between the TR-IFMA and ELISA was 0.8009. The intra- and interassay precision rates were less than 5% for three different concentrations. The average recovery rate for L protein was 101.17%. In sum, the established assay kit performed better in terms of stability than the commercial ELISA kit. Conclusion The TR-IFMA that we developed for L protein presented a higher sensitivity and wider detecting range than regular commercial ELISA. Therefore, this TR-IFMA has promising value both in the screening of HBV and monitoring of antiviral therapy.

Background Many studies reported for estimating serum YKL-40 using ELISA or RIA methods. This study introduces the plausible utilization of real-time surface plasmon resonance (SPR) technology in investigating the expression of serum YKL-40 protein levels and ELISA method for serum IgE in bronchial asthma. Methods A commercially available BIAcore 2000 instrument, based on SPR technology, was utilized for assessing serum YKL-40 levels in a control sample size of 45 and active sample size of 97. Antibody immobilization was optimized to obtain the best sensor performance and a sensitive analytic detection. A commercially available ELISA kit was utilized for detecting serum IgE to estimate allergic condition-associated asthma. Results The results of SPR technology could distinctly classify with highly statistical significance, the asthma severities by estimating the elevated levels of YKL-40 in blood sera of minute quantities (up to 0.33 ng/ml), and thus differentiates superior utility in comparison with ELISA method. No statistically significant correlation of YKL-40 and IgE was observed. Conclusions Serum YKL-40 may be used as a protein marker in classifying asthma severity by applying SPR technology as a reliable, label-free, highly sensitive, and cost-effective tool.

BACKGROUND: We studied the association between high serum levels of vascular endothelial growth factor (VEGF) and clinical outcomes of intracerebral hemorrhage (ICH) patients. METHODS: Patients were divided into group A (30 mL) based on the bleeding amount. ICH patients were also categorized into the mild group,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 moderate group (16‐30), and severe group (31‐45) based on the National Institutes of Health Stroke Scale (NIHSS). The serum levels of VEGF in acute ICH patients detected at 24, 48, and 72 hours were obtained using ELISA kit, and then compared with control group. Main clinical outcomes were evaluated using the modified Rankin scale at 90 days. RESULTS: The serum levels of VEGF were significantly higher than those in the control group. The serum levels of VEGF in group C were specifically higher compared with those in other two groups. The severe group exhibited higher levels of VEGF than the other two groups. NIHSS scores in patients with good outcomes were lower than those with poor outcomes. Besides, VEGF levels in patients with good outcomes were much higher than those in patients with poor outcomes. ROC results indicated that the optimal cut‐off value of VEGF at 72 hours for predicting good outcomes was 111.17 pg/mL with 91.5 sensitivity, 98.7 specificity, and an AUC of 0.952 Our results showed that higher serum levels of VEGF were associated with process of ICH. CONCLUSION: VEGF could be a new marker in ICH for severity.

E‐selectin, an adhesion molecule, is detectable in the blood. Serum levels of E‐selectin can be a prognostic indicator for various malignancies. We developed a microplate enzyme‐linked immunosorbent assay (ELISA) for the detection of circulating E‐selectin by coating the microwell with monoclonal anti‐E‐selectin. We incubated the specimen and the biotinylated detecting antibody simultaneously, and used HPR‐conjugated streptavidin to generate a signal for quantification. The assay has a sensitivity of 3.8 ng/mL, and the coefficients of variation (CVs) for both within‐day and day‐to‐day precision were all

Penicillinase (beta-lactamase) enzyme-linked immunosorbent assay (ELISA) for various reproductive hormones developed in the laboratory were found to have wide applicability in the fertility check clinic of the Institute. A need was thought to transform these assays into ready-to-use kit forms. Therefore, prototype ELISA kits for these hormones were developed and stability of the individual component was ascertained at various temperatures (room temperature, 37 degrees C and 2-8 degrees C). Stability studies were conducted on previously validated assay for pregnanediol-3 alpha-glucuronide (PdG). The studies showed that immunosorbents (antibody coated plates) are stable at room temperature for a period of 2 weeks, at 37 degrees C for 1 week and at 2-8 degrees C for a period of 9 months when preserved after treatment with glycerol solution. The lyophilised conjugate, standard and immunoassay buffer, colour reagent, and its substrate were stable at 37 degrees C up to 1 week and at room temperature up to 2 weeks and at 2-8 degrees C for a period of 6 months, during which the stability was studied.

Eight commercially available enzyme-linked immunoadsorbent assays (ELISA) for the detection of cytomegalovirus (CMV)-specific IgM were used in parallel to determine the presence of CMV-IgM in 123 serum samples from pregnant women. The results obtained with the eight kits were compared. Based on concordance of six or more of the eight kits, we assessed sensitivity, specificity, and overall agreement, as well as incidence of false-positive and -negative results for each kit. The results obtained by ELISA were then compared with those obtained by immunofluorescence (IF) and immunoblotting (IB). Our study did not single out one outstanding ELISA kit among the eight evaluated, nor did it suggest that IF or IB are better than ELISA. Furthermore our results indicate that IB might be useful in several cases as, beside its good sensitivity, most IB-false-positive sera are easily recognized as reacting exclusively with pp150, the unique reactivity to pp150 not being among the IB profiles of IB-true-positive sera. Nevertheless 14.6% of sera remained CMV-IgM-indeterminate.