A novel way to evaluate autoantibody interference in samples with mixed antinuclear antibody patterns in the HEp-2 cell based indirect immunofluorescence assay and comparison of conventional microscopic and computer-aided pattern recognition.

BACKGROUND: A major challenge of the HEp-2 cell-based indirect immunofluorescence (IIF) assays is the correct identification of the individual anti-nuclear antibodies (ANAs) if more than one is present in a sample. We created artificial mixes by pooling two different samples with a single autoantibody in different titers. Comparison of the expected and observed patterns and titers clarifies the interference between the two tested ANAs. METHODS: Serum samples with a single homogeneous or speckled ANA pattern were serially diluted and mixed in 16 combinations, providing end-point titers of 1:5,120 to 1:80 for both patterns. These mixes were tested by a HEp-2 IIF assay and were evaluated by conventional evaluation, the EUROPattern (EPa) system and on-screen analysis. RESULTS: Homogeneous pattern can alter the identification of the speckled pattern much more than vice versa, but both has an interfering effect on the other. The effect of the interfering on the tested pattern was higher if the titer of the former one was higher. The pattern recognition efficacy of conventional and the on-screen evaluation was similar and superior compared to the EPa analysis. CONCLUSIONS: The application of artificial mixed samples can help the evaluation of the efficacy of manual and computer-aided ANA HEp-2 pattern recognition.

Increased sTREM-1 levels identify cirrhotic patients with bacterial infection and predict their 90-day mortality.

BACKGROUND AND AIMS: Patients with cirrhosis are susceptible to bacterial infections (BIs) that are major causes of specific complications and mortality. However, the diagnosis of BIs can often be difficult in advanced disease stage since their symptoms may overlap with the ones of acute decompensation (AD). Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) is released from monocytes/macrophages and neutrophils during activation and has been reported to correlate with activity of various inflammatory processes. We investigated its diagnostic and prognostic performance in patients with cirrhosis and BI. METHODS: Sera of 269 patients were assayed for sTREM-1 by ELISA (172 outpatients and 97 patients with AD of whom 56 had BI). We investigated capacity of sTREM-1 to identify patients with BI and conducted a 90-day follow-up observational study to assess its possible association with short-term mortality. RESULTS: sTREM-1 levels were significantly higher in patients with more severe liver disease, BI, and acute-on-chronic liver failure than in patients without these conditions. sTREM-1 had similar accuracy to CRP identifying BI [sTREM-1: AUROC (95%CI) 0.804 (0.711-0.897), p < 0.0001; CRP: 0.791 (0.702-0.881), p < 0.0001)] among AD patients. The combination of these two molecules and the presence of ascites into a composite score significantly increased their discriminative power (AUROC: 0.878, 95%CI: 0.812-0.944, p < 0.0001). High sTREM-1 level (>660 pg/mL) was an independent predictor of 90-day mortality in patients with BI [HR: 2.941, (95%CI: 1.009-8.573), p = 0.048] in our multivariate model. CONCLUSIONS: Use of sTREM-1 could increase the recognition of BIs in cirrhosis and help clinicians in mortality risk assessment of these patients.

A DNA pool of FLT3-ITD positive DNA samples can be used efficiently for analytical evaluation of NGS-based FLT3-ITD quantitation - Testing several different ITD sequences and rates, simultaneously.

Internal tandem duplication (ITD) in the fms-like tyrosine kinase 3 (FLT3) gene is one of the most frequent genetic alteration in acute myeloid leukemia (AML), and it is associated with worse clinical outcome. Not only the presence but also the size, localization and the rate of this variant or the presence of multiple ITDs has prognostic information. The traditional PCR based diagnostic methods cannot provide information about all of these parameters in one assay, however the application of next generation sequencing (NGS) technique can be a reliable solution for this diagnostic problem. In order to evaluate the analytical properties of an NGS-based FLT3-ITD detection assay a quality control sample was prepared from DNA of AML patients containing 19 different FLT3-ITD variants identified by NGS. The higher the total read count was in a certain sample of the NGS run, the more ITD variant types could be detected. The maximal sensitivity of FLT3-ITD detection by NGS technique was as low as 0.007% FLT3-ITD/total allele rate, however, below 0.1% rate, the reproducibility of the quantitation was poor (CV > 25%). DNA pools with several FLT3-ITDs can be used efficiently for analytical evaluation of NGS-based FLT3-ITD quantitation testing several different ITD sequences and rates, simultaneously.

Cystatin C as a potential predictor of osteoprotegerin levels in healthy men, a cross-sectional, observational study.

BACKGROUND: The aim of the present study is to evaluate serum osteoprotegerin (OPG) and soluble receptor activator of nuclear factor κB ligand (sRANKL) levels in a randomly selected male cohort over 50 years of age and its association with cystatin C, a cysteine proteinase inhibitor that decreases formation of osteoclasts by interfering at a late stage of pre-osteoclast differentiation, apart from being a marker of renal function independent of gender, muscle mass and age; in addition to known predictors such as age, sex hormones, vitamin D, bone mineral density (BMD) and biochemical markers of bone turnover. METHODS: We determined serum OPG and sRANKL levels and examined its relationship with cystatin C, age, osteocalcin, C-terminal telopeptides of type-I collagen, procollagen type 1 amino-terminal propeptide, 25-hydroxyvitamin D, parathyroid hormone, total 17ß-estradiol (E2), total testosterone and L1-L4 (LS) and femur neck (FN) BMD data available from 194 (age, range: 51-81 years) randomly selected ambulatory men belonging to the HunMen cohort. RESULTS: OPG correlated significantly with age (Spearman's rho (r) = 0.359, p < 0.001), cystatin C (r = 0.298, p < 0.001), E2 (r = 0.160, p = 0.028) and free testosterone index (FTI) (r = -0.230, p = 0.001). Compared to the middle-aged (age: ≤ 59 years, n = 98), older men (age > 59 years, n = 96) had significantly higher serum OPG (4.6 pmol/L vs. 5.4 pmol/L; p < 0.001), and lower sRANKL (0.226 pmol/L vs. 0.167 pmol/L; p = 0.048) levels. The older men showed a significant correlation between serum OPG levels and cystatin C (Spearman's rho = 0.322, p = 0.002), and E2 (Spearman's rho = 0.211, p = 0.043). Including cystatin C and E2 in a regression model showed that cystatin C (standard regression coefficient (ß) = 0.345; p = 0.002) was the only significant predictor of serum OPG levels in the older men. CONCLUSIONS: The results of this study demonstrated that in addition to age (which was the stronger predictor), other modifiable factors such as cystatin C, FTI and E2 were also significant predictors of OPG, and that the association between cystatin C and OPG was more evident with increased age (older age group). As such, cystatin C is a significant predictor of OPG independently of age, FTI and E2.

Serum sclerostin levels in healthy men over 50 years of age.

The aim of this study is to evaluate the relationship of serum sclerostin levels with age, cystatin C, bone mineral density (BMD) and biochemical markers of bone turnover in healthy Hungarian men >50 years of age. We determined serum levels of sclerostin and examined its relationship to age, cystatin C, osteocalcin, C-terminal telopeptides of type-I collagen, procollagen type 1 amino-terminal propeptide, 25-hydroxyvitamin D, parathyroid hormone, and L1-L4 (LS) and femur neck (FN) BMD data available from 194 randomly selected ambulatory men belonging to the HunMen cohort. In the study population as a whole [n = 194; age (median, range) 59 (51-81) years], statistically significant correlation was found between sclerostin and age (r = 0.211; p = 0.003), cystatin C (r = 0.246; p = 0.001), FN BMD (r = 0.147; p = 0.041) and LS BMD (r = 0.169; p = 0.019). Compared to middle-aged men (age ≤59 years, n = 98), elderly men (age >59 years, n = 96) had significantly higher serum sclerostin levels (67.8 ± 15.9 vs 63.5 ± 14 pmol/L; p = 0.047). Among men with normal (T score >-1.0) FN BMD, the elderly had significantly higher serum sclerostin levels compared to the middle-aged men (70.4 ± 17 vs 63.9 ± 11.5 pmol/L; p = 0.019). Furthermore, among the elderly men cystatin C was the only significant predictor of serum sclerostin levels (standardized regression coefficient (ß) = 0.487; p < 0.001). In the studied healthy elderly cohort, this study reports a significant increase in sclerostin levels with increasing age and deteriorating kidney function as determined by plasma cystatin C levels.

Detection of internal tandem duplications in the FLT3 gene by different electrophoretic methods.

BACKGROUND: In acute myeloid leukemia (AML), the internal tandem duplication (ITD) in the juxtamembrane domain of the FLT3 (Fms-like tyrosine kinase 3) gene is one of the most frequent genetic alterations associated with poor prognosis. METHODS: A complex evaluation of the analytical properties of the three most frequently used detection methods--PCR followed by agarose (AGE), polyacrylamide (PAGE) or capillary electrophoresis (CE)--was performed on 95 DNA samples obtained from 73 AML patients. RESULTS: All the three methods verified the presence of a mutant allele in 20 samples from 18 patients. AGE and PAGE could detect the presence of 1%-2% mutant allele, while the detection limit of CE was 0.28%. However, acceptable reproducibility (inter-assay CV <25%) of the mutant allele rate determination was only achievable above 1.5% mutant/total allele rate. The reproducibility of the ITD size determination by CE was much better, but the ITD size calculated by PeakScanner or GeneScan analysis was 7% lower as compared to values obtained by DNA sequencing. The presence of multiple ITD was over-estimated by PAGE and AGE due to the formation of heteroduplexes. CONCLUSIONS: This study suggests the use of PCR+CE in the diagnostics and the follow-up of AML patients. The data further supports the importance of proper analytical evaluation of home-made molecular biological diagnostic tests.