Mutations of PsPALM1a and PsPALM1b associated with the afila phenotype in Pea.

Semi-leafless represents an advantageous plant architecture in pea breeding due to its ability to enhance resistance to lodging and potentially to powdery mildew. The introduction of semi-leafless pea varieties is considered a seminal advancement in pea breeding over the past half-century. The afila (af) mutation leads to the replacement of lateral leaflets by highly branched tendrils; combined with the semi-dwarfing le mutation, it forms the semi-leafless cultivated variety. In this study, we identified that mutations in two tandemly-arrayed genes encoding Cys(2)His(2) zinc finger transcription factors, PsPALM1a and PsPALM1b, were closely associated with the afila phenotype. These two genes may be deleted in the af mutant. In situ hybridization showed that both genes exhibit specific expression in early leaflet primordia. Furthermore, suppression of PsPALM1a/PsPALM1b resulted in a high frequency of conversion of lateral leaflets into tendrils. In conclusion, our study provides genetic evidence demonstrating that mutations in PsPALM1a and PsPALM1b are responsible for the af locus, contributing to a better understanding of compound leaf formation in peas and offering new insights for breeding applications related to afila.

A handheld isothermal fluorescence detector for duplex visualization of aquatic pathogens via enhanced one-pot LAMP-PfAgo assay.

The expansion of large-scale aquaculture has exacerbated the challenge of aquatic diseases, resulting in substantial economic losses annually. Currently, traditional laboratory-based diagnostic methods are time-consuming and costly, hindering on-site testing for individual farmers. We address this issue by developing a state-of-the-art handheld isothermal nucleic acid amplification device (WeD-1) capable of fluorescence tracking of reactions and integrating it with an enhanced one-pot Prokaryotic Argonaute based nucleic acid detection method, enabling duplex visual detection of aquatic pathogens. WeD-1 is portable, reusable, user-friendly, and cost-effective, offering real-time smartphone interaction and enabling real-time fluorescence observation during the reaction. The enhanced one-pot Loop-Mediated Isothermal Amplification (LAMP)-PfAgo method, incorporating paraffin-encapsulated lyophilized PfAgo protein, achieves precise target-specific cleavage, significantly enhancing multiplex nucleic acid detection. This innovation streamlines on-site testing, negating the need for specialized laboratory conditions while ensuring an aerosol-free system. With newly developed and highly sensitive LAMP primer sets, our compact WeD-1/LAMP-PfAgo nucleic acid rapid testing system exhibits remarkable sensitivity, readily detecting aquatic pathogens with naked eyes from rapidly prepared fish and shrimp samples within 40 min, even when the Ct values are as high as 34.

Integrated scRNAseq analyses of mouse cochlear supporting cells reveal the involvement of Ezh2 in hair cell regeneration.

BACKGROUND: In lower vertebrates like fish, the inner ear and lateral line hair cells (HCs) can regenerate after being damaged by proliferation/differentiation of supporting cells (SCs). However, the HCs of mouse cochlear could only regenerate within one to two weeks after birth but not for adults. METHODS AND RESULTS: To better understand the molecular foundations, we collected several public single-cell RNA sequencing (scRNAseq) data of mouse cochleae from E14 to P33 and extracted the prosensory and supporting cells specifically. Gene Set Enrichment Analysis (GSEA) results revealed a down-regulation of genes in Notch signaling pathway during postnatal stages (P7 and P33). We also identified 107 time-course co-expression genes correlated with developmental stage and predicated that EZH2 and KLF15 may be the key transcriptional regulators for these genes. Expressions of candidate target genes of EZH2 and KLF15 were also found in supporting cells of the auditory epithelia in chick and the neuromasts in zebrafish. Furthermore, inhibiting EZH2 suppressed regeneration of hair cells in zebrafish neuromasts and altered expressions of some developmental stage correlated genes. CONCLUSIONS: Our results extended the understanding for molecular basis of hair cell regeneration ability and revealed the potential role of Ezh2 in it.

Increased Expression of Inflammatory Cytokines and Discogenic Neck Pain.

OBJECTIVE: Although neck pain has become a serious economic and social problem worldwide, the etiology remains poorly understood. The aim of current study is to explore the possible pathogenesis of discogenic neck pain by analyzing the relationship between inflammatory cytokines and discogenic neck pain and provide a valuable reference for the prevention and treatment of discogenic neck pain. METHODS: A total of 111 cervical disc samples were collected between October 1, 2021, and October 1, 2022: 38 samples from the discogenic neck pain group, 41 samples from the symptomatic control group, and 32 samples from the normal control group. The concentration of nitric oxide (NO), interleukin (IL)-1, interleukin (IL)-6, and tumor necrosis factor alpha (TNF-α) was determined using the enzyme-linked immunosorbent assay in each sample, and the degeneration degree of the target discs were evaluated using T2-weighted sagittal magnetic resonance imaging (MRI) according to the Miyazaki disc degeneration grading system. Whether the differences among the three groups were statistically significant was tested using one-way analysis of variance and an unpaired t-test, respectively. RESULTS: The differences of the baseline characteristics were not statistically significant between the discogenic neck pain group and the symptomatic control group (p > 0.05). The expression of inflammatory cytokines in disc samples from the discogenic neck pain group (NO: 9.89 ± 1.75, IL-1ß: 10.74 ± 1.92, IL-6:31.65 ± 2.46, and TNF-α: 5.96 ± 1.91) was increased in comparison with the disc samples from both the symptomatic control group (NO: 7.15 ± 2.78, IL-1ß: 8.03 ± 1.87, IL-6: 25.79 ± 2.12, and TNF-α: 4.18 ± 2.87) and the normal control group (NO: 6.11 ± 1.37, IL-1ß: 5.84 ± 2.25, IL-6: 20.65 ± 1.26, and TNF-α: 2.05 ± 0.58). The differences were statistically significant (p < 0.001). Further, there were no statistical differences in the degree of degeneration between discogenic neck pain group and symptomatic control group. CONCLUSIONS: The increased expression of inflammatory cytokines in diseased cervical intervertebral discs might play a key role in the pathogenesis of discogenic neck pain. Although inflammation is involved in intervertebral disc degeneration, there is no linear positive correlation between the concentration of inflammatory cytokines and the degree of disc degeneration.

Control of compound leaf patterning by MULTI-PINNATE LEAF1 (MPL1) in chickpea.

Plant lateral organs are often elaborated through repetitive formation of developmental units, which progress robustly in predetermined patterns along their axes. Leaflets in compound leaves provide an example of such units that are generated sequentially along the longitudinal axis, in species-specific patterns. In this context, we explored the molecular mechanisms underlying an acropetal mode of leaflet initiation in chickpea pinnate compound leaf patterning. By analyzing naturally occurring mutants multi-pinnate leaf1 (mpl1) that develop higher-ordered pinnate leaves with more than forty leaflets, we show that MPL1 encoding a C2H2-zinc finger protein sculpts a morphogenetic gradient along the proximodistal axis of the early leaf primordium, thereby conferring the acropetal leaflet formation. This is achieved by defining the spatiotemporal expression pattern of CaLEAFY, a key regulator of leaflet initiation, and also perhaps by modulating the auxin signaling pathway. Our work provides novel molecular insights into the sequential progression of leaflet formation.

Predictive Factors Associated with Chronic Neck Pain in Patients with Cervical Degenerative Disease: A Retrospective Cohort Study.

Purpose: To explore the predictive factors of neck pain (NP) in patients with cervical degenerative disease by retrospectively analyzing their occupational and demographic characteristics and to provide a valuable reference for preventing and treating chronic NP. Patients and Methods: We retrospectively reviewed the occupational and demographic data of patients with cervical degenerative disease who had undergone anterior cervical surgery between June 2021 and December 2022 at our center. The patients were divided into NP and no-NP groups based on whether they had chronic NP before surgery. Relevant occupational and demographic data from all patients were statistically analyzed, and all variables were made categorical. Forward stepwise logistic regression models were constructed for preoperative chronic neck pain to explore the possible risk factors associated with chronic neck pain. Results: The differences in smoking, being an office worker, BMI, and disease types between NP and no-NP groups were statistically significant. In contrast, there were no statistically significant in age, sex, academic level, duration, and degeneration grade between the two groups. Moreover, further logistic regression analysis indicated that smoking, being an office worker, having an abnormal BMI, and cervical spondylotic radiculopathy (CSR) were related to chronic neck pain. Conclusion: The present study indicated that smoking, being an office worker, having an abnormal BMI, and CSR were predisposing risk factors for NP associated with cervical degenerative disease. Although intervertebral disc degeneration is the pathology basis of NP, the degeneration grade was not related to the occurrence of NP in our current study. Therefore, quitting smoking, avoiding sedentariness, and maintaining a normal BMI may prevent NP to some extent.

Study on Modification of Poplar Wood via Composite Impregnation with Silica Sol/Melamine-Glyoxal Resin.

In order to overcome the defects of fast-growing poplar wood, such as low strength and poor toughness, this paper introduces a method of modifying poplar wood via impregnation with silica sol/melamine-glyoxal (silica sol/MG) resin and explores its effects on the physical, mechanical, and thermal properties of poplar wood. It was found via scanning electron microscopy that the composite modifier covered and filled the cell lumen, cell interstitial space, and cell wall pores of poplar wood. Further, infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed that chemical cross-linking occurred between the silica sol/MG resin composite modifier and the internal groups of poplar wood and that the Si-O-Si flexible long chains introduced in the composite modifier formed a cross-linking network with poplar wood such as Si-O-Si and Si-O-C, which led to the improvement of the physical and mechanical properties and the enhancement of the thermal stability of poplar wood. The method provides a theoretical basis for the high-value utilization of fast-growing poplar wood.

The MIO1-MtKIX8 module regulates the organ size in Medicago truncatula.

Plant organ size is an important agronomic trait tightly related to crop yield. However, the molecular mechanisms underlying organ size regulation remain largely unexplored in legumes. We previously characterized a key regulator F-box protein MINI ORGAN1 (MIO1)/SMALL LEAF AND BUSHY1 (SLB1), which controls plant organ size in the model legume Medicago truncatula. In order to further dissect the molecular mechanism, MIO1 was used as the bait to screen its interacting proteins from a yeast library. Subsequently, a KIX protein, designated MtKIX8, was identified from the candidate list. The interaction between MIO1 and MtKIX8 was confirmed further by Y2H, BiFC, split-luciferase complementation and pull-down assays. Phylogenetic analyses indicated that MtKIX8 is highly homologous to Arabidopsis KIX8, which negatively regulates organ size. Moreover, loss-of-function of MtKIX8 led to enlarged leaves and seeds, while ectopic expression of MtKIX8 in Arabidopsis resulted in decreased cotyledon area and seed weight. Quantitative reverse-transcription PCR and in situ hybridization showed that MtKIX8 is expressed in most developing organs. We also found that MtKIX8 serves as a crucial molecular adaptor, facilitating interactions with BIG SEEDS1 (BS1) and MtTOPLESS (MtTPL) proteins in M. truncatula. Overall, our results suggest that the MIO1-MtKIX8 module plays a significant and conserved role in the regulation of plant organ size. This module could be a good target for molecular breeding in legume crops and forages.

A high-performance long-wave infrared photodetector based on a WSe2/PdSe2 broken-gap heterodiode.

Layered narrow bandgap quasi-two-dimensional (2D) transition metal dichalcogenides (TMDs) demonstrated excellent performance in long-wave infrared (LWIR) detection. However, the low light on/off ratio and specific detectivity (D*) due to the high dark current of the device fabricated using a single narrow bandgap material hindered its wide application. Herein, we report a type-III broken-gap band-alignment WSe2/PdSe2 van der Waals (vdW) heterostructure. The heterodiode device has a prominently low dark current and exhibits a high photoresponsivity (R) of 55.3 A W-1 and a high light on/off ratio >105 in the visible range. Notably, the WSe2/PdSe2 heterodiode shows an excellent uncooled LWIR response, with an R of ∼0.3 A W-1, a low noise equivalence power (NEP) of 4.5 × 10-11 W Hz-1/2, and a high D* of 1.8 × 108 cm Hz1/2 W-1. This work provides a new approach for designing high-performance room-temperature operational LWIR photodetectors.

Self-perception of academic ability and ADHD symptoms in college students in China and the United States: A preliminary study.

Children with ADHD are frequently reported to demonstrate a positive illusory bias in multiple domains. Less is known about such a bias in college students. This study examined academic positive illusory bias in college students and whether cultural factors play a role in its expression. A total of 633 college students from China and the United States completed measures designed to assess biased self-perception of academics. Among other measures, the nonclinical sample completed a math task and then estimated their own achievement and completed measures of intellectual and scholastic self-competence. Symptoms of ADHD were unrelated to overconfidence on the math task and were negatively related to reports of self-competence. However, individualism and collectivism were related to overconfidence and self-competence. In contrast to results from research in other domains, academic positive illusory bias among those with more symptoms of ADHD does not appear to persist into college.

Bioinformatics Research and qRT-PCR Verify Hub Genes and a Transcription Factor-MicroRNA Feedback Network in Intervertebral Disc Degeneration.

The present study explores the potentials of bioinformatics analysis to identify hub genes linked to intervertebral disc degeneration (IDD) and explored the potential molecular mechanism of transcription factor-microRNA regulatory network. Furthermore, the hub genes were identified through quantitative reverse transcriptase PCR (qRT-PCR). GEO database expression profile datasets for candidate genes (GSE124272) were downloaded. Genes that were differentially expressed (DEGs) were detected utilizing limma technique in the R programming language. Search Tool for the Retrieval of Interacting Genes/Proteins and NetworkAnalyst software identified hub genes. The Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis as well as Gene Ontology annotation of the DEGs were performed using Metascape. Using Bioinformatics data from the TRRUST, StarBase, and TransmiR databases, a TF-miRNA-hub genes network was constructed. qRT-PCR was utilized to confirm the result. As compared to healthy persons, 521 DEGs, comprising 203 down-regulated and 318 up-regulated genes, as well as 7 core genes, were found in people with IDD. Analysis revealed that all seven essential genes were under-expressed. qRT-PCR further confirmed the low expression of these seven important genes. Based on the TRRUST database, 16 TFs that could target five junction genes were then predicted. According to the StarBase database, four miRNAs were linked to crucial genes, while the TransmiR database predicted regulatory connections between four miRNAs and five TFs. The expression of the TP53-(hsa-miR-183-5p)-CCNB1 TF-miRNA-mRNA interaction network was discovered to be correlated with IDD. Throughout this investigation, a network of TF-miRNA-mRNA connections was built for investigation of the probable molecular mechanisms responsible for IDD. The identification of hub genes associated with IDD may reveal promising IDD treatment strategies.

TRPM7 transactivates the FOSL1 gene through STAT3 and enhances glioma stemness.

INTRODUCTION: We previously reported that TRPM7 regulates glioma cells' stemness through STAT3. In addition, we demonstrated that FOSL1 is a response gene for TRPM7, and the FOSL1 gene serves as an oncogene to promote glioma proliferation and invasion. METHODS: In the present study, we determined the effects of FOSL1 on glioma stem cell (GSC) markers CD133 and ALDH1 by flow cytometry, and the maintenance of stem cell activity by extreme limiting dilution assays (ELDA). To further gain insight into the mechanism by which TRPM7 activates transcription of the FOSL1 gene to contribute to glioma stemness, we constructed a FOSL1 promoter and its GAS mutants followed by luciferase reporter assays and ChIP-qPCR in a glioma cell line and glioma patient-derived xenoline. We further examined GSC markers ALDH1 and TRPM7 as well as FOSL1 by immunohistochemistry staining (IHC) in brain tissue microarray (TMA) of glioma patients. RESULTS: We revealed that FOSL1 knockdown reduces the expression of GSC markers CD133 and ALDH1, and FOSL1 is required to maintain stem cell activity in glioma cells. The experiments also showed that mutations of - 328 to - 336 and - 378 to - 386 GAS elements markedly reduced FOSL1 promoter activity. Constitutively active STAT3 increased while dominant-negative STAT3 decreased FOSL1 promoter activity. Furthermore, overexpression of TRPM7 enhanced while silencing of TRPM7 reduced FOSL1 promoter activity. ChIP-qPCR assays revealed that STAT3, present in nuclear lysates of glioma cells stimulated by constitutively activated STAT3, can bind to two GAS elements, respectively. We demonstrated that deacetylation of FOSL1 at the Lys-116 residue located within its DNA binding domain led to an increase in FOSL1 transcriptional activity. We found that the expression of TRPM7, ALDH1, and FOSL1 protein is associated with grades of malignant glioma, and TRPM7 protein expression correlates to the expression of ALDH1 and FOSL1 in glioma patients. CONCLUSIONS: These combined results demonstrated that TRPM7 induced FOSL1 transcriptional activation, which is mediated by the action of STAT3, a mechanism shown to be important in glioma stemness. These results indicated that FOSL1, similar to GSC markers ALDH1 and TRPM7, is a diagnostic marker and potential drug target for glioma patients.

Genome-Wide Characterization of PEBP Gene Family and Functional Analysis of TERMINAL FLOWER 1 Homologs in Macadamia integrifolia.

Edible Macadamia is one of the most important commercial nut trees cultivated in many countries, but its large tree size and long juvenile period pose barriers to commercial cultivation. The short domestication period and well-annotated genome of Macadamia integrifolia create great opportunities to breed commercial varieties with superior traits. Recent studies have shown that members of the phosphatidylethanolamine binding protein (PEBP) family play pivotal roles in regulating plant architecture and flowering time in various plants. In this study, thirteen members of MiPEBP were identified in the genome of M. integrifolia, and they are highly similarity in both motif and gene structure. A phylogenetic analysis divided the MiPEBP genes into three subfamilies: MFT-like, FT-like and TFL1-like. We subsequently identified two TERMINAL FLOWER 1 homologues from the TFL1-like subfamily, MiTFL1 and MiTFL1-like, both of which were highly expressed in stems and vegetative shoots, while MiTFL1-like was highly expressed in young leaves and early flowers. A subcellular location analysis revealed that both MiTFL1 and MiTFL1-like are localized in the cytoplasm and nucleus. The ectopic expression of MiTFL1 can rescue the early-flowering and terminal-flower phenotypes in the tfl1-14 mutant of Arabidopsis thaliana, and it indicates the conserved functions in controlling the inflorescence architecture and flowering time. This study will provide insight into the isolation of PEBP family members and the key targets for breeding M. integrifolia with improved traits in plant architecture and flowering time.

[Work Environment-Mediated Job Burnout and Intention-to-Stay in Registered Nurses].

BACKGROUND: Nurse engagement and retention are critical issues affecting the quality of healthcare. Although the work environment is known to affect nursing performance and patient outcomes, little is known regarding the impact of this environment on nurse burnout and future work intention, especially in non-Western settings. PURPOSE: This study explored the extent to which Taiwanese nurses' perceptions of their practice environment mediates burnout levels and intention-to-stay. METHODS: This descriptive, correlational study, conducted between September and December 2020, recruited nurses employed at a regional teaching hospital located in a relatively rural region in Taiwan. The participants completed standardized questionnaires, including a demographic information form, the 31-item Practice Environment Scale of the Nursing Work Index (PES-NWI), the 22-item Maslach Burnout Inventory (MBI-HSS), and the 6-item Intention-to-stay (ITS) scale. The mediating effect among the variables related to intention-to-stay was examined using Model 4 of the PROCESS macro and tested using the bootstrapping method (repeated 5,000 times) with a p value < .05. RESULTS: The mean age of the 376 participants was 34.3 years (SD = 8.1). Nearly one-third (30.3%) scored > 27 on the emotional exhaustion subscale of the MBI-HSS, indicating they were "highly burned-out". Also, nearly one-third (30.6%) were uncertain about their intention to stay with their current employer. Burnout was associated with intention-to-stay (ß = -.088, p < .001), and holding a positive perception toward their practice environment was shown to mediate the relationship between burnout and intention-to-stay (ß = -.015; p < .001). CONCLUSIONS / IMPLICATIONS FOR PRACTICE: Targeted interventions and technical support that promote a collaborative climate and psychological empowerment in clinical practice may alleviate burnout and intention-to-leave in nurses and improve workplace quality.

An efficient LC-MS/MS method for simultaneous determination of four substances in the Hcy metabolism pathway.

Aim: This study aimed to develop and validate an efficient LC-MS/MS method for the simultaneous determination of Hcy, Cys, Met and 5-methyltetrahydrofolate in human serum and to apply this method to patients with coronary artery disease. Methodology and results: Serum samples were prepared by reduction with dithiothreitol followed by protein precipitation. The analytical run time was 2.2 min. The linearity was good in the range of 2-100 µmol/l-1 for Hcy and Met, 10-500 µmol/l-1 for Cys, and 1-50 ng/ml-1 for 5-methyltetrahydrofolate. Conclusion: An accurate and precise method that was rapid, robust and with high-throughput for the routine clinical monitoring of patients with coronary artery disease was developed.

A simple and rapid liquid chromatography-tandem mass spectrometry method for the simultaneous determination of 15 bile acids in human serum and its application to patients with decompensated cirrhosis.

Liver cirrhosis is currently the twelfth leading cause of death globally and the sixth leading cause of death in China. Its treatment is expensive. Changes in the composition of the serum bile acid pool are sensitive indicators of the severity of liver cirrhosis. In this study, a novel LC-tandem mass spectrometry (LC-MS/MS) method was developed and used to simultaneously determine 15 bile acids in human serum in patients with decompensated cirrhosis. Sample preparation involved spiking with isotope internal standards followed by protein precipitation. The analytical run time was 5 min. The LC-MS/MS method was fully validated according to Clinical and Laboratory Standards Institute (CLSI) C62A and the consensus of method development and validation of liquid chromatography-tandem mass spectrometry in clinical laboratories. The method achieved an acceptable coefficient of variation for precision (0.83%-14.80%) and accuracy (89.39%-107.62%). Finally, as proof of applicability, the method was applied to patients with decompensated cirrhosis in routine clinical sample analysis. The degree of variation of different bile acids was clearly shown. These results indicated that abnormal metabolic pathways might play important roles in decompensated cirrhosis.

Genome-wide identification of the CPK gene family in wheat (Triticum aestivum L.) and characterization of TaCPK40 associated with seed dormancy and germination.

Calcium-dependent protein kinases (CPKs), important sensors of calcium signals, play an essential role in plant growth, development, and stress responses. Although the CPK gene family has been characterized in many plants, the functions of the CPK gene family in wheat, including their relationship to seed dormancy and germination, remain unclear. In this study, we identified 84 TaCPK genes in wheat (TaCPK1-84). According to their phylogenetic relationship, they were divided into four groups (I-IV). TaCPK genes in the same group were found to have similar gene structures and motifs. Chromosomal localization indicated that TaCPK genes were unevenly distributed across 21 wheat chromosomes. TaCPK gene expansion occurred through segmental duplication events and underwent strong negative selection. A large number of cis-regulatory elements related to light response, phytohormone response, and abiotic stress response were identified in the upstream promoter sequences of TaCPK genes. TaCPK gene expression was found to be tissue- and growth-stage-diverse. Analysis of the expression patterns of several wheat varieties with contrasting seed dormancy and germination phenotypes resulted in the identification of 11 candidate genes (TaCPK38/-40/-43/-47/-50/-60/-67/-70/-75/-78/-80) which are likely associated with seed dormancy and germination. The ectopic expression of TaCPK40 in Arabidopsis promoted seed germination and reduced abscisic acid (ABA) sensitivity during germination, indicating that TaCPK40 negatively regulates seed dormancy and positively regulates seed germination. These findings advance our understanding of the multifaceted functions of CPK genes in seed dormancy and germination, and provide potential candidate genes for controlling wheat seed dormancy and germination.

Preparation and properties of silica sol/melamine glyoxal resin.

In this study, a composite modifier for wood impregnation is prepared, which is functional and environmentally friendly. The surface of silica sol was modified by using KH-560. The modified silica sol, melamine, and glyoxal were used as raw materials. The silica sol/melamine glyoxal resin (from now on referred to as Silica sol/MG) composite modifier was prepared based on in-situ polymerization. The physicochemical properties (viscosity, solid content and etc.) of the composite modifier were evaluated. The structural and thermal properties were characterized and analyzed by FTIR spectroscopy, particle size distribution, TG and DSC. The results showed that the viscosity and solid content of the composite modifier decreased with the increase in the mass of the silica sol. The FTIR spectroscopy showed peaks at 473 cm-1 and 1101 cm-1, which were assigned to bending and stretching vibrations of the Si-O-Si bond, respectively, indicating that the modified silica sol was successfully introduced into the MG resin. When the modified silica sol mass fraction was 30%-40%, the particle size distribution of the composite modifier was relatively uniform. TG analysis found that the thermal stability of the composite modifier was significantly improved compared with the unmodified resin. DSC analysis showed that adding the modified silica sol reduced the curing temperature of the modifier from 115.5 °C to 107.9 °C.

Evaluation of analytical performance of homocysteine LC-MS/MS assay and design of internal quality control strategy.

OBJECTIVES: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become a common technique in clinical laboratories in recent years. Because most methods are laboratory-developed tests (LDTs), their reproducibility and quality control (QC) have been controversial. In this study, Westgard Sigma Rules were used to evaluate the analytical performance and establish an individualised internal QC (IQC) strategy for these LDTs. METHODS: Taking the LC-MS/MS LDT method for homocysteine (Hcy) as an example, the 'desirable specifications' from the Biological Variation Database were used as quality goals. Based on the external quality assessment (EQA) samples, bias was calculated and the coefficient of variation (CV) was also calculated by IQC measurements for six consecutive months. The analytical performance was evaluated by calculated sigma metrics and an IQC strategy was designed using the Westgard Sigma Rules with run size. RESULTS: Over 116 days within 6 months, a total of 850 data points were collected for each of IQC 1 and IQC 2. The monthly coefficient of variation CV% was 2.57-4.01%, which was non-significant (p-value: 0.75). The absolute bias% for IQC1 and IQC2 was 1.23 and 1.87%, respectively. The allowable total error (TEa) was selected as 15.5%, Sigma metrics were 4.02 and 4.30, and the analytical performance was 'Good'. The 13s/22s/R4s/41s multi rules (n=4, r=1) with a run size of 200 samples were suggested for the Hcy IQC scheme. The quality goal index (QGI) values were over 1.2, indicating that trueness needed to be improved. CONCLUSIONS: The analytical performance of the Hcy LC-MS/MS LDT conformed to the Six Sigma rating level, achieving 'good' (four Sigma). Clinical practice indicated that calibration bias was the primary factor affecting trueness.