Small lipid-binding proteins known as fatty acid-binding proteins (FABPs) are extensively expressed in cells having elevated levels of fatty acid (FA) metabolism. There are ten known FABPs in mammals that exhibit expression patterns specific to tissues and tertiary structures that are substantially preserved. FABPs were first investigated as FA transport proteins inside cells. Subsequent research has shown that they are involved in signalling within their expression cells and in metabolism of lipid, directly and through the control of expression of gene. Additionally, there is evidence that they might be released and influence circulatory function. It has been observed that some tissues and organs linked to inflammatory, metabolic illnesses and also infectious disease have markedly elevated expression levels of FABPs. Thus, in addition to previously identified markers, FABPs represent a promising new biomarker that require additional investigation to optimise illness detection and prognosis techniques.

IntroductionThe objective of this study was to develop a highly sensitive time-resolved fluorescence immunoassay (TRFIA) method to detect phospholipase A2 receptor (PLA2R)-IgG1 antibodies and evaluate its clinical relevance in predicting the prognosis of individuals with idiopathic membranous nephropathy (IMN). Materials and methodsA three-step indirect TRFIA method was established using a PLA2R antigen-coated microtiter plate to capture PLA2R-IgG antibodies, followed by detection using mouse anti-human IgG1 and Eu3+-labeled goat anti-mouse IgG antibodies. This method was applied to the initial serum of 56 patients with PLA2R-IMN to investigate the clinical value of PLA2R-IgG1 antibody levels in predicting IMN prognosis. ResultsThe detection range of PLA2R-IgG1-TRFIA was 0.85–300RU/mL, with intra-assay precision of 3.54–5.93 % and inter-assay precision of 4.39–9.36 %. Recoveries were 101.77–108.04 %. A PLA2R-IgG1 level above 2.21RU/mL indicated PLA2R-IMN. At initial diagnosis, the median PLA2R-IgG level was 51.24RU/mL in the remission group and 93.27RU/mL in the non-remission group. The median PLA2R-IgG1 level was 603.32RU/mL in the non-remission group, which was 4.29 times higher than that in the remission group (140.67RU/mL). PLA2R-IgG1 levels (P = 0.001) more effectively distinguished between remission and non-remission groups compared with PLA2R-IgG levels (P = 0.094). ConclusionsThe first quantitative TRFIA for PLA2R-IgG1 was established, showing greater clinical value in predicting IMN prognosis, compared to that for PLA2R-IgG levels.

BackgroundCirculating tumor DNA (ctDNA) has emerged as a useful biomarker for cancer detection and prognosis. In this study, we developed a strategy for developing a highly specific multiplex qPCR assay to detect methylated ctDNA in the blood of colorectal cancer (CRC) patients and investigated the potential use for the detection and prognosis of CRC. MethodsBisulfite conversion and amplicon sequencing were used to confirm potential CRC-specific DNA methylation markers. The selected DNA methylation candidates were validated by qMSP. The six best-performing markers were used to develop a new single-tube multiplex quantitative methylation-specific PCR assay (mqMSP). The mqMSP assay was applied to analyze plasma samples from 114 CRC patients, 47 patients with advanced adenoma, 45 patients with benign polyps, and 57 healthy controls. The clinical performance of the assay and associations with clinical outcomes were assessed. ResultsSix DNA methylation biomarkers were confirmed to be specifically hypermethylated in CRC tumor tissues. The newly developed mqMSP assay detected CRC with extremely high specificity (specificity of 98.2 %, with sensitivity of 67.5 %). The detection rate of ctDNA was significantly correlated with tumor size and clinical stage, with ctDNA methylation levels in the blood markedly increased with larger tumor size, poor differentiation, and advanced stage. Moreover, high preoperative methylated ctDNA level was associated with worse recurrence-free survival and overall survival. ConclusionWe provided a strategy for identification of multiple highly-specific DNA methylation markers for designing multiplex DNA methylation assays for liquid biopsies of CRC. The newly developed assay has potential for CRC early detection, and prognosis.

BackgroundTotal IgE (tIgE) is a frequently requested analyte in patients presenting with symptoms of atopy. Although tIgE has limited clinical utility in the diagnosis of atopic diseases, it is still important that appropriate reference intervals are provided to the intepreting clinician. Concerns have recently been raised whether laboratories are using outdated tIgE reference intervals. The aim of this study was therefore to perform the first systematic literature review of tIgE reference intervals to aid laboratories in choosing appropriate sources of tIgE reference intervals. MethodsA search was performed in MEDLINE, Embase and the Cochrane Library from time of inception to July 2024. Eligible studies had to provide an estimate of paediatric and/or adult tIgE reference intervals using current generation immunoassays. The methodology followed PRISMA guidelines, and the study protocol was registered in the PROSPERO database (CRD42023396441). ResultsA total of 1667 records were screened of which 20 studies remained after the full text review. The studies included 23 910 individuals and covered 18 countries. Upper reference limits varied significantly, with participant selection (inclusion or exclusion of in vitro confirmed specific IgE sensitised individuals) and statistical methods identified as the most important factors influencing the upper reference limit. ConclusionThis review emphasises the need for laboratories to carefully evaluate the participant selection criteria and employed statistical methods whilst determining which tIgE reference intervals are the most appropriate to report to clinicians. Further efforts should also be made to harmonise and improve the reporting of tIgE reference interval studies.

BackgroundCell-free DNA (cfDNA) is non-randomly fragmented in human body fluids. Analyzing such fragmentation patterns of cfDNA holds great promise for liquid biopsy. Whole-genome bisulfite sequencing (WGBS) is widely used for cfDNA methylation profiling. However, its applicability for studying fragmentomic characteristics remains largely unexplored. MethodsWe performed paired WGBS and whole-genome sequencing (WGS) on 66 peripheral plasma samples from 58 pregnant women. Then, we systematically compared the fragmentation patterns of cell-free nuclear DNA and mitochondrial DNA (mtDNA) sequenced from these two approaches. Additionally, we evaluated the extent of the size shortening in fetal-derived cfDNA and estimated the fetal DNA fraction in maternal plasma using both sequencing methods. ResultsCompared to WGS samples, WGBS samples demonstrated a significantly lower genome coverage and higher GC content in cfDNA. They also showed a significant decrease in the size of cell-free nuclear DNA, along with alterations in the end motif pattern that were specifically associated with CpG and “CC” sites. While there was a slight shift in the inferred nucleosome footprint from cfDNA coverages in WGBS samples, the cfDNA coverage patterns in CTCF and TSS regions remained highly consistent between these two sequencing methods. Both methods accurately reflected gene expression levels through their TSS coverages. Additionally, WGBS samples exhibited an increased abundance and longer length of mtDNA in plasma. Furthermore, we observed the size shortening of fetal cfDNA in plasma consistently, with a highly correlated fetal DNA fraction inferred by cfDNA coverage between WGBS and WGS samples (r = 0.996). However, the estimated fetal cfDNA fraction in WGBS samples was approximately 7 % lower than in WGS samples. ConclusionsWe confirmed that WGBS can introduce artificial breakages to cfDNA, leading to altered fragmentomic patterns in both nuclear and mitochondrial DNA. However, WGBS cfDNA remains suitable for analyzing certain cfDNA fragmentomic characteristics, such as coverage in genome regulation regions and the essential characteristics of fetal DNA in maternal plasma.

BackgroundSerum homocysteine (Hcy) measurement accuracy is essential for detecting and diagnosing cardio-cerebrovascular illnesses. Although many different methods have been developed to determine the concentration of Hcy, those different assays showed nonequivalent results. This study aimed to develop an accurate and precise isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC/MS/MS) method for serum homocysteine (Hcy) and assign values for reference materials used in external quality assessment (EQA) programs. MethodsDifferent concentrations of homocysteine calibration solutions were prepared with d4-Hcy as the internal standard. This method employed DTT to reduce protein-bound Hcy, followed by protein precipitation, and gradient elution on a Supelcosil LC-CN column for chromatographic separation, and multiple reaction monitor (MRM) mode with electrospray ionization (ESI) for mass spectrometric detection. After optimized ID-LC/MS/MS parameters, imprecision, trueness, the limit of quantification (LoQ), the limit of detection (LoD), and measurement uncertainty were evaluated to check the methodological performance. The established method was employed in assigning values to EQA samples, which were sent to 63 clinical laboratories in Beijing to measure Hcy. ResultsAt 10.69,15.99, and 37.80 μmol/L levels, the present method demonstrated analytical imprecision of 0.57 %, 0.65 %, and 0.57 %, and recoveries of 99.67 % to 100.21 %, respectively. The bias between the target values of GBW (Guojia Biaozhun Wuzhi) were − 0.79 % to 0.62 %. The LoQ and LoD for Hcy were 0.36 nmol/L and 0.27 nmol/L. The method had an uncertainty (U 95 %) of 1.34 % to 1.48 %. For the three levels of EQA samples, the percentage of laboratories meeting the trueness evaluation criteria (±10 %) was 81.67 %, 83.33 %, and 71.67 % respectively. ConclusionsWith optimal method precision and trueness, the ID-LC/MS/MS method to measure serum Hcy can be used for value assignment of EQA samples, which can provide reliable data for monitoring the accuracy of clinical laboratory for Hcy measurement.

IntroductionSignificant variations in Biological Variation (BV) estimates have been reported for urine markers. This study aimed to systematically review and critically appraise BV studies for albumin, creatinine, albumin-to-creatinine ratio (ACR), and other urine markers to perform a meta-analysis of eligible studies. MethodsPublications were identified through a systematic search and evaluated using the Biological Variation Data Critical Appraisal Checklist (BIVAC). BIVAC-compliant studies (grades A-C; A being fully compliant) conducted in healthy individuals were included in the meta-analysis, providing within-subject (CVI) and between-subject (CVG) BV estimates with 95% confidence intervals for various sample collection types. ResultsOut of 37 studies evaluated, 16 were included (one grade A, three B, twelve C). No eligible publications were identified for meta-analysis of albumin and ACR. Limited data were available for first-morning urine specimens. A CVI between 15% and 30% was found for most measurands in 24-hour urine samples, while CVI estimates for random urine appeared higher. ConclusionPublished BV studies on urine markers utilized different sample collections and reporting units. Most were considered unfit for use or ineligible for meta-analysis. Given the critical role of urine albumin and ACR in chronic kidney disease risk assessment, there is a need for more BIVAC-compliant studies.