Hee-Won Moon

Comparison of four current 25-hydroxyvitamin D assays

OBJECTIVES The performance of recently developed vitamin D total assays (ADVIA Centaur and Elecsys) was compared to that of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and LIASON 25-OH Vitamin D total assays. DESIGN AND METHODS A total of 157 clinical samples and standard reference material (SRM) 972 were analyzed. RESULTS The correlations of LC-MS/MS with the three immunoassays were acceptable. However, compared to LC-MS/MS, LIAISON and ADVIA Centaur showed negative bias, and Elecsys showed positive bias. There was a lack of agreement among the four methods with only LC-MS/MS results close to the certified values of SRM 972. The prevalence of vitamin D insufficiency (<50 nmol/L) was higher with ADVIA Centaur (51.6%) and LIAISON (52.2%) and lower with Elecsys (37.6%), compared with that of LC-MS/MS (44.6%). CONCLUSION The new, automated total vitamin D assays show acceptable correlation with LC-MS/MS, and could be used in routine laboratories. However, standardization of vitamin D assays and consideration of assay-specific decision limits should be addressed.

Plasma neutrophil gelatinase-associated lipocalin as a biomarker for acute kidney injury in critically ill patients with suspected sepsis.

OBJECTIVES The aim of this study was to investigate the diagnostic utility of plasma neutrophil gelatinase-associated lipocalin (NGAL) as an early objective biomarker to predict acute kidney injury (AKI) in critically ill patients with suspected sepsis, for whom procalcitonin (PCT) was used for the diagnosis and staging of sepsis. DESIGN AND METHODS Plasma NGAL was measured using the Triage NGAL Test (Alere, Inc., San Diego, CA, USA) in 231 samples obtained from patients with suspected sepsis. The results of NGAL were compared with those of Elecsys BRAHMS PCT (Roche Diagnostics, Basel, Switzerland). Renal failure was assessed using the renal subscore of Sepsis-related Organ Failure Assessment (SOFA) score. AKI was defined according to the Acute Kidney Injury Network criteria. RESULTS The concentrations of plasma NGAL were significantly different according to the five groups of PCT concentration (P<0.0001) and the renal subscore of SOFA score (P<0.0001). Plasma NGAL was significantly increased in the patients with AKI compared with those without AKI (416.5 ng/mL vs. 181.0 ng/mL, P=0.0223). CONCLUSION Plasma NGAL seems to be a highly sensitive and objective predictor of AKI in patients with sepsis. Plasma NGAL can be added for the diagnosis and staging of renal failure in sepsis.

Performance of the Vitek MS matrix-assisted laser desorption ionization time-of-flight mass spectrometry system for identification of Gram-positive cocci routinely isolated in clinical microbiology laboratories

We evaluated the performance of the Vitek MS for identification of Gram-positive cocci routinely isolated in clinical microbiology laboratories. With a total of 424 well-characterized isolates, the results of the Vitek MS were compared to those of conventional methods and 16S rRNA gene sequencing. The Vitek MS correctly identified 97.9 % of the isolates tested to species level. The Vitek MS correctly identified the species of 97.2 % of the staphylococci (95.9 % of coagulase-negative staphylococci), 97.8 % of the streptococci, and 100 % of the enterococci. For the identification of Gram-positive cocci isolates, the overall concordance rate between conventional identification and the Vitek MS was 94.5 %. The Vitek MS matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) system can be a reliable and rapid method for the identification of most relevant Gram-positive cocci. In addition, expanding the database of the Vitek MS, especially for coagulase-negative staphylococci, is needed to enhance the performance of the Vitek MS.

Analytical performance evaluation of the scanning capillary tube viscometer for measurement of whole blood viscosity.

BACKGROUND Whole blood viscosity (WBV) is the resistance of blood flow in blood vessels. Increased WBV may be a cardiovascular risk factor. The proper screening of WBV can help the early detection of cardiovascular disease. We investigated the performance of a new scanning capillary tube viscometer (SCTV) for the measurement of WBV. METHODS We evaluated the total precision of the SCTV for 20 days using three control viscosity materials, and the within-day precision with the whole blood samples of three different individuals. For the linearity evaluation, serial dilutions of a high concentration standard material were used. For the method comparison, the results of the SCTV method were compared to those of Brookfield rotating viscometer on 227 subjects. RESULTS The SCTV had good within-run and total-run coefficient of variant (CV)s at low-, medium-, and high-concentration samples, at shear rates of 1 and 300 s(-1). The within-day CVs with the three human blood samples were 6.3%, 3.7% and 3.8% at a shear rate of 1s(-1), and 3.2%, 3.0% and 4.1% at a shear rate of 300 s(-1). The SCTV method showed an excellent linearity in the range of 84.9 to 558.2 milliPoise (mP) and 28.8 to 71.0 mP at shear rates of 1 and 300 s(-1), respectively. For the comparison study, the SCTV and the rotating viscometer showed comparable results. CONCLUSIONS The SCTV showed a stable analytical performance, and was comparable with the rotational viscometer. This new SCTV method can be used in the clinical laboratory for various needs.

CD4+CD25highFoxP3+ Regulatory T-cells in Hematologic Diseases

Background CD4+CD25+ regulatory T-cells (Tregs) play a critical role in immune responses. We explored the status of Tregs in neoplastic and autoimmune hematologic diseases. We also evaluated the technical aspects of Treg measurement in terms of sample type and detection markers. Methods A total of 68 subjects were enrolled: 11 with AML, 8 with MDS, 10 with autoimmune diseases, and 39 controls. Tregs were analyzed in peripheral blood (PB) and bone marrow (BM) samples from each subject. Flow cytometry and the Human Regulatory T cell Staining Kit (eBioscience, USA) for CD4, CD25, and FoxP3 (forkhead box P3) were used. Results The CD4+CD25high/CD4 and CD4+CD25highFoxP3+/CD4 populations were significantly correlated (P<0.0001). The AML and high-risk MDS groups had significantly larger CD4+CD25high/CD4 and CD4+CD25highFoxP3+/CD4 populations in PB than the autoimmune (P=0.007 and 0.012, respectively) and control groups (P=0.004 and 0.006, respectively). Comparable findings were observed in BM. The CD4+CD25highFoxP3+/CD4 population was significantly larger in PB than in BM (P=0.0003). Conclusions This study provides comparison data for Tregs in AML, MDS, and autoimmune hematologic diseases, and would be helpful for understanding the different immunologic bases of various hematologic diseases. Treg measurement using CD4, CD25, and/or FoxP3 in PB rather than in BM seems to be practical for routine hematologic purposes. Large-scale analysis of the diagnostic role of Treg measurement is needed.

Performances of Four Fourth-Generation Human Immunodeficiency Virus-1 Screening Assays

Fourth‐generation human immunodeficiency virus‐1 (HIV‐1) screening assays have improved sensitivity, but vary in performance characteristics. The purpose of this study was to evaluate four different fourth‐generation HIV‐1 assays. These assays included the AxSYM HIV Ag/Ab Combo (Abbott diagnostics, Delkenheim, Germany), ARCHITECT HIV Ag/Ab Combo (Abbott), Elecsys 2010 HIV Combi (Roche Diagnostics GmbH, Mannheim, Germany), and Elecsys HIV Combi PT (Roche). A total of 1,306 samples that included 1,225 clinical samples and 81 samples consisting of seroconversion panels, an HIV‐1 p24 antigen sensitivity panel, and dilution series of HIV‐1 lysates and HIV‐1 antibodies were tested. All of the assays had sensitivities of 100% on clinical samples. The specificities of the AxSYM, ARCHITECT, Elecsys 2010 HIV Combi, and Elecsys HIV Combi PT were 99.6, 99.6, 99.0, and 99.5%, respectively. Of the 81 samples with different levels of HIV antigen or antibody and/or subtypes, Elecsys HIV Combi PT and ARCHITECT HIV Ag/Ab Combo showed better analytical sensitivities than the other two assays. In summary, the performance characteristics of AxSYM, ARCHITECT, and Elecsys HIV Combi PT were comparable and satisfactory for clinical samples. ARCHITECT HIV Ag/Ab Combo and Elecsys HIV Combi PT have the higher analytical sensitivities, and would be preferable for reducing the window period. J. Med. Virol. 84:1884–1888, 2012.

Comparison of Diagnostic Utility between Procalcitonin and C-Reactive Protein for the Patients with Blood Culture-Positive Sepsis

BACKGROUND Procalcitonin (PCT) is a relatively new marker for bacterial infections, and its diagnostic utility has been variable across the studies. We investigated the diagnostic utility of PCT for the patients with blood culture-positive sepsis, and compared it with that of C-reactive protein (CRP). METHODS In 1,270 consecutive blood samples, PCT and CRP were simultaneously measured and results were compared according to the five categories of PCT concentrations (<0.05 ng/mL; 0.05-0.49 ng/mL; 0.5-1.99 ng/mL; 2-9.99 ng/mL; > or = 10 ng/mL). In 506 samples, they were further analyzed according to the result of blood culture. PCT and CRP were measured using enzyme-linked fluorescent assay (bioMerieux Co., France) and rate nephelometry (Beckman Coulter Co., USA), respectively. Their diagnostic utilities were compared using ROC curves. RESULTS The mean concentrations of CRP in five categories of PCT were 15.4 mg/L, 42.1 mg/L, 101.2 mg/L, 125.0 mg/L, 167.1 mg/L, respectively (P<0.0001). Both PCT and CRP showed significant differences between the two positive and negative groups of blood culture (PCT, 8.47 vs 2.44 ng/mL, P=0.0133; CRP, 110.48 vs 59.78 mg/L, P<0.0001). The areas under the ROC curves (95% confidence interval) for PCT and CRP were 0.720 (0.644-0.788) and 0.558 (0.478-0.636), respectively, and showed a significant difference (P=0.005). CONCLUSIONS The diagnostic utility of PCT is superior to that of CRP for the patients with blood culture-positive sepsis. PCT seems to be reliable for sepsis diagnosis, and may provide useful information for the critically ill patients.

High prevalence of autoantibodies in Hepatitis A infection : The impact on laboratory profiles

Aims: In the absence of IgM antibodies against hepatitis A virus (HAV), HAV infections can be regarded as autoimmune hepatitis when they show positive autoantibodies by indirect immunofluorescence and lack other viral markers. The aim of this study was to evaluate the prevalence, titres and impact of autoantibodies in Korean patients with HAV infection. Methods: The study involved a retrospective review of the electronic medical records of 73 patients with HAV at Konkuk University Hospital from August 2005 to September 2008. The presence and pattern of anti-nuclear antibody, anti-smooth muscle antibody, anti-mitochondrial antibody and anti-liver/kidney microsomal antibody were assessed by indirect immunofluorescence on Hep-2 cells and mouse/kidney sections. Results: Of the 73 patients with hepatitis A, 65 (89.0%) showed positive indirect immunofluorescence tests. Of note, most of the positive tests (95.5%) showed a cytoplasmic pattern with filamentous staining of cytoplasmic fibres. There was no significant difference between groups in age or sex. In patients positive for autoantibodies, alanine aminotransferase and leucocyte count were significantly higher, while the increase in globulin was not statistically significant. In terms of titres, globulin was significantly higher in patients with ⩾1:160 titres than in those with ⩽1:80 titres (mean (SD) 3.4 (0.5) versus 2.8 (0.4) g/dl, respectively; p = 0.000). Conclusions: The study demonstrated a high prevalence of anticytoplasmic autoantibodies in patients with acute hepatitis A. These data would be useful to aid interpretation of indirect immunofluorescence testing in patients with acute hepatitis, especially in areas with a high prevalence of HAV.

Establishment of Trimester-Specific Reference Intervals for Thyroid Hormones in Korean Pregnant Women

Background Establishment of trimester- and assay-specific reference intervals for every population is recommended. The aim of this study was to establish a trimester- and assay-specific reference interval for thyroid-stimulating hormone (TSH) and free thyroxine (FT4) in Korean pregnant women. Methods From April 2012 to December 2012, 531 pregnant women receiving prenatal care and 238 age-matched, non-pregnant women were enrolled in this study. After excluding patients with pregnancy-associated complications or thyroid-specific autoantibody, 465 pregnant and 206 non-pregnant women were included. Non-parametric analysis (2.5-97.5th percentile) was performed to determine the reference interval. Levels of TSH and FT4 were determined by electrochemiluminescence immunoassay (Elecsys thyroid tests, Roche Diagnostics, Germany). Results The TSH reference intervals were 0.01-4.10, 0.01-4.26, and 0.15-4.57 mIU/L for the first, second, and third trimester, respectively. From the first trimester to the third trimester, the median TSH levels showed a significantly increasing trend (P<0.0001). The FT4 reference intervals were 0.83-1.65, 0.71-1.22, and 0.65-1.13 ng/dL for the first, second, and third trimester, respectively, showing a significantly decreasing trend (P<0.0001). Conclusions Establishing trimester-specific reference intervals in pregnant women is essential for accurate assessment of thyroid function. Our population-specific and method-specific reference intervals will be useful for screening Korean pregnant women for thyroid disease.

Role of C-reactive protein in osteoclastogenesis in rheumatoid arthritis

IntroductionC-reactive protein (CRP) is one of the biomarkers for the diagnosis and assessment of disease activity in rheumatoid arthritis (RA). CRP is not only the by-product of inflammatory response, but also plays proinflammatory and prothrombotic roles. The aim of this study was to determine the role of CRP on bone destruction in RA.MethodsCRP levels in RA synovial fluid (SF) and serum were measured using the immunoturbidimetric method. The expression of CRP in RA synovium was assessed using immunohistochemical staining. CD14+ monocytes from peripheral blood were cultured with CRP, and receptor activator of nuclear factor-κB ligand (RANKL) expression and osteoclast differentiation were evaluated using real-time PCR, counting tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells and assessing bone resorbing function. CRP-induced osteoclast differentiation was also examined after inhibition of Fcγ receptors.ResultsThere was a significant correlation between CRP levels in serum and SF in RA patients. The SF CRP level was correlated with interleukin (IL)-6 levels, but not with RANKL levels. Immunohistochemical staining revealed that compared with the osteoarthritis synovium, CRP was more abundantly expressed in the lining and sublining areas of the RA synovium. CRP stimulated RANKL production in monocytes and it induced osteoclast differentiation from monocytes and bone resorption in the absence of RANKL.ConclusionsCRP could play an important role in the bony destructive process in RA through the induction of RANKL expression and direct differentiation of osteoclast precursors into mature osteoclasts. In the treatment of RA, lowering CRP levels is a significant parameter not only for improving disease activity but also for preventing bone destruction.