Practical Laboratory Medicine最新文献

Introduction

Robust immunoassays for quantification of Alzheimer's disease (AD)-specific biomarkers are required for routine diagnostics. We report analytical performance characteristics of four new chemiluminescence immunoassays (ChLIA, EUROIMMUN) running on closed, fully automated random-access instruments for quantification of Aβ_1-40, Aβ_1-42, tTau, and pTau(181) in human cerebrospinal fluid (CSF).

Methods

ChLIAs were validated according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Optimal cut-offs for biomarkers and biomarker ratios were determined using samples from 219 AD patients and 220 patients with AD-related symptoms. For performance comparison, biomarker concentrations were measured in 110 diagnostic leftover samples using the ChLIAs and established Lumipulse G assays (Fujirebio).

Results

All ChLIAs met CLSI criteria. Overall agreement between assays was 89.0%–97.3 % with highly correlating results (Pearson's correlation coefficients: 0.82–0.99). Passing-Bablok regression analysis revealed systematic differences.

Discussion

EUROIMMUN ChLIAs showed good analytical performances and represent new valuable tools for diagnostics of AD.

Objectives

We aimed to evaluate the analytical performance of second-trimester maternal serum screening in China, and to compare if there are differences in sigma levels across different methods and months.

Methods

A retrospective study was conducted to assess the analytical quality levels of laboratories by calculating the Sigma metrics with prenatal screening biomarkers: AFP, Total β-hCG, free β-hCG, uE3. Data from 591 laboratories were selected. Sigma metrics were computed using the formula: Sigma metrics(σ) = (%TEa - |%Bias|)/%CV. The Friedman test and Mann-Whitney test were used to compare differences across various methods and different months. The Hodges–Lehmann was used for determining 95 % confidence intervals of pseudo-medians.

Results

Only uE3 showed significant monthly variations in sigma calculations. However, around 8 % of laboratories across all four analytes demonstrated sigma levels both above 6 and below 3 in different months. Laboratories utilizing time-resolved fluorescence methods significantly outperformed those using chemiluminescence in sigma level. For AFP, the pseudo-median difference between these methods lies within a 95 % confidence interval of (−3.22, −1.93), while for uE3, it is at (−2.30, −1.40). Notably, the median sigma levels for all analytes reached the 4-sigma threshold, with free β-hCG even attaining the 6-sigma level.

Conclusion

With current standards, China's second-trimester maternal serum screening is of relatively high analytical quality, and variations in sigma levels exist across different months and methods.

Aims

This study aimed to assess the use of glucometers by patients and the analytical performance of glucometers provided by the primary care services.

Methods

The analytical performance of 48 glucometers Accu-Chek® Active, was assessed through quintuplicate analyses of one Roche and one PNCQ (National Quality Control Program) control sample at different concentrations; 31 were also evaluated by a single proficiency testing sample. The evaluation metrics included imprecision, bias, and total error and were measured according to quality specifications based on biological variation (QSBV). Glucometer users answered a questionnaire regarding their experience.

Results

Among the 48 glucometers evaluated with internal control samples, 17 met precision criteria at both control levels according to QSBV, while 24 met the criteria at only one control level. Of the 31 glucometers further evaluated through proficiency test, 11 met accuracy criteria according to QSBV, and only one device showed an unacceptable result. Out of these 31, only 15 demonstrated a total error within the acceptable maximum limits based on QSBV.

Conclusions

Overall, our findings showed that patients had a good understanding of glucometer usage and suggested that some glucometers should be replaced, as they sometimes failed to meet even the manufacturer’s acceptable variation limits, and/or did not meet QSBV.

Background

AMH is important in child growth and the concentrations change with age and gender. This study aimed to evaluate the performance of the Pylon AMH assays and establish pediatric reference intervals.

Methods

The experiments on imprecision, sensitivity, linearity, reportable range, interference and comparison were carried out to evaluate the analytical performance. The AMH reference ranges were calculated in 238 females and 346 males aged 0–18 years using robust methods.

Results

The repeatability and the within-laboratory imprecision CVs of the assay were 3.7 % and 6.4 % at 2.25 ng/mL, and 4.6 % and 6.4 % at 15.49 ng/mL, respectively. The sensitivity (LoB = 0.05 ng/mL, LoD = 0.1 ng/mL and LoQ = 0.3 ng/mL) was verified. The linearity was 0.1–19.55 ng/mL and report up to 391 ng/mL with 20x pre-dilution. There was no significant interference from hemoglobin (500 mg/dL), triglyceride (500 mg/dL), bilirubin (10 mg/dL), cholesterol (800 mg/dL) and biotin (3000 ng/mL). The AMH measured by the Pylon assays correlated to those measured by the Elecsys assays. In males, the AMH levels were high at birth (0 d-1 m: median 95.10 ng/mL) and increased to a peak (7 m-1y: median 158.80 ng/mL) before they decreased with age (15–18 y: median 6.31 ng/mL). In females, the AMH concentrations were low at birth (0 d-1 m: median 0.20 ng/mL) and increased with age (15–18 y: median 3.03 ng/mL).

Conclusion

The Pylon AMH assays showed good analytical performance and the AMH reference intervals in chinese children determined may provide a basis in clinical diagnosis and treatment of related diseases.

Background: Since ancient times, poisoning, even serious poisoning, has been known to occur during nature walks. Intentional or unintentional ingestion of toxins of animal origin is one of the possible causes of poisoning. Bufadienolide poisoning is a critical case. This is because of its high potency and its ability to cross the blood-brain barrier. Due to the rarity of these poisonings in humans in Central Europe, their identification is often difficult. The following is a case report of a poisoning by toad eggs in an Italina child, that presented vertigo, fussiness and sleepiness. A method of toxin identification using the prince of pharmacotoxicology, liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS), and an innovative reasoning were used. This method can be applied to other poisoning cases.

Background

Long-read sequencing technology, widely used in research, is proving useful in clinical diagnosis, especially for infectious diseases. Despite recent advances, it hasn't been routinely applied to constitutional human diseases. Long-read sequencing detects intronic variants and phases variants, crucial for identifying recessive diseases.

Methods

We integrated long-read sequencing into the clinical diagnostic workflow for the MEFV gene, responsible for familial Mediterranean fever (FMF), using a Nanopore-based workflow. This involved long-range PCR amplification, native barcoding kit library preparation, GridION sequencing, and in-house bioinformatics. We compared this new workflow against our validated method using 39 patient samples and 3 samples from an external quality assessment scheme to ensure compliance with ISO15189 standards.

Results

Our evaluation demonstrated excellent performance, meeting ISO15189 requirements for reproducibility, repeatability, sensitivity, and specificity. Since October 2022, 150 patient samples were successfully analyzed with no failures. Among these samples, we identified 13 heterozygous carriers of likely pathogenic (LP) or pathogenic (P) variants, 1 patient with a homozygous LP/P variant in MEFV, and 4 patients with compound heterozygous variants.

Conclusion

This study represents the first integration of long-read sequencing for FMF clinical diagnosis, achieving 100 % sensitivity and specificity. Our findings highlight its potential to identify pathogenic variants without parental segregation analysis, offering faster, cost-effective, and accurate clinical diagnosis. This successful implementation lays the groundwork for future applications in other constitutional human diseases, advancing precision medicine.

Background

Anti-citrullinated protein antibodies (ACPA) are a specific serological biomarker used in the diagnosis of rheumatoid arthritis (RA). In clinical practice ACPA can be identified using immunoassays targeting synthetic cyclic citrullinated peptides (CCP). The 3rd generation anti-CCP IgG antibody (CCP3) offers improved sensitivity compared to the earlier versions. Recently, CCP3.1, capable of detecting both IgG and IgA antibodies, was introduced to enhance sensitivity, especially in patients with early RA.

Methods

We assessed serum CCP3.1 against CCP3 in 331 subjects undergoing RA panel serology, comprising 136 patients with RA and 195 patients without RA. Sera were tested for anti-CCP IgG (CCP3) and anti-CCP IgG/IgA (CCP3.1) antibodies. Clinical performance of these tests was compared at manufacturer-suggested cutoffs. A separate set of 81 patients with a diagnosis of RA by 2010 criteria and whose samples were obtained from within 1-year of RA diagnosis was similarly assessed to evaluate assay performance in an independent clinical RA cohort.

Results

Overall diagnostic accuracy was similar; CCP3 had an area under the curve (AUC) of 0.88, CCP3.1 had an AUC of 0.89. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for CCP3 were 79 %, 91 %, 86 %, and 86 %, respectively. For CCP3.1, sensitivity was 78 %, specificity 93 %, PPV 89 %, NPV 86 %. Both assays demonstrated excellent agreement; positive percent agreement of 94 % and negative percent agreement of 99 %.

Conclusion

Our findings indicate comparable diagnostic accuracy between CCP3 and CCP3.1 assays in these clinical cohorts.

Objectives

This study aims to determine the temporal stability of Schistosoma mansoni circulating cathodic antigens (CCA) in filter paper-based dried urine spot (FP-DUS) samples under varying temperatures condition.

Methods

Urine from 20 children confirmed to have S. mansoni infection using Kato-Katz (at least 1 egg per gram of stool) and Schisto POC-CCA (2+ and 3+) methods were stored in form of FP-DUS and urine at room temperature (RT), 4 °C and −20 °C. Standard urine and FP-DUS Schisto POC-CCA methods were employed to detect CCA in urine and FP-DUS samples respectively, at weeks 4, 8 and 12. The results were reported as negative or positive (trace, 1+. 2+, and 3+).

Results

In FP-DUS samples, POC-CCA scores initially increase after 4–8 weeks, but then showed a decrease in intensity while still remaining positive, independent of temperature condition. From week 4 to week 12, at least 80 % of urine samples had POC-CCA score of 3+, independent of temperature condition. However, 2 urine samples at RT tested negative at weeks 8 and 12.

Conclusions

Despite the decrease in the intensity of test line in many samples, S. mansoni CCA remains stable and detectable in urine samples stored in FP-DUS.

Objective

Cardiovascular diseases (CVDs) are a leading cause of mortality worldwide. Low density lipoprotein cholesterol (LDL-C) contributes to the atherogenic process. However, direct LDL-C (d-LDL) has rarely been estimated by the gold standard method because it is cumbersome and expensive. We aim to evaluate calculated low density lipoprotein (LDL-c) by various equations with reference to directly measured LDL-C in the Pakistani adult population as a cost-effective alternative.

Methods

We retrospectively evaluated the validity of seven equations for estimating calculated LDL-C by computing correlation coefficients (r) and Bland Altman plots to assess agreement (mean %) for (d-LDL) and calculated (LDL-c) on all seven equations. Statistical analysis was performed in Stata Statistical Software: Release 17, College Station, TX: StataCorp LLC.

Results

We analyzed 247082 direct assays of lipid profiles of adults aged ≥18 years. The mean LDL-C levels computed on Friedewald, de Cordova, Chen, Hattori, Vujovic, Teerakanchana, Sampson equations were 106.8 ± 31.4, 103.7 ± 25.0, 108.6 ± 28.2, 100.1 ± 29.5, 115.2 ± 31.2, 113.1 ± 28.3 and 110.3 ± 30.6 respectively. Friedewald and Hattori equations correlated strongly with direct LDL-C (r = 0.937) for each followed by Sampson (r = 0.935) and Vujovic (r = 0.931). However, the median bias was least for the Friedwald equation (−1.6) compared to the other equations.

Conclusion

In contrast to the global literature advocating for the use of newer equations, although the conventional and widely utilized Friedewald equation remains the best alternative for calculated LDL-C estimation in adult Pakistani population.

Chronic inflammation of the pancreas is considered to be one of the causes of pancreatic cancer. However, the diagnosis of chronic pancreatitis (CP) is very difficult in the pancreas, where biopsies are difficult to perform. The prevalence of CP is estimated to be many times more common than in patients with actual symptomatic CP. In recent years, abnormal cleavage of certain proteins has attracted attention as a biomarker for CP other than pancreatic enzymes. Connective tissue growth factor (CTGF) is one of the growth factors involved in tissue repair and other processes and is increased by stimulation of transforming growth factor-β, suggesting a relationship of CTGF with fibrosis. In this study, we measured the total length of CTGF in blood and N-terminal fragment CTGF in 48 cases of chronic pancreatitis, 64 cases of pancreatic cancer and 45 healthy volunteers (HV). Interestingly, we found that blood N-terminal fragment CTGF level was significantly increased in CP and pancreatic cancer patients. Multiple logistic regression analysis showed serum levels of N-terminal fragment CTGF, CRP and amylase were significant and independent variables for the differential diagnosis of CP from HV. Receiver operating characteristic analysis showed that area under the curve (AUC) value of serum N-terminal fragment CTGF level was 0.933, which can differentiate between CP and HV. Several factors would be involved in the increase in serum N-terminal fragment CTGF level. In conclusion, serum N-terminal fragment CTGF level is a promising new biomarker for CP.