High-throughput quantitation of serological dimethylarginines by LC/MS/MS: Potential cardiovascular biomarkers for rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by systemic inflammation of the joints and extra-articular tissues. The incidence of cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with RA. Despite the development of new therapeutics targeting the articular manifestations, the relief of the cardiovascular burden is still an unmet medical need during the management of RA. So, the early prognosis of RA-associated CVD plays a crucial role in improving the clinical outcomes of RA patients. Recently, circulating dimethylarginines have gained attention as potential biomarkers for CVDs. Here, we present the development and validation of a high-throughput liquid chromatography-tandem mass spectrometric (LC/MS/MS) method for simultaneous quantification of creatinine, arginine, and dimethylarginines in human serum within 2 mins by isotope dilution mass spectrometry. This method employed a protein precipitation method for rapid sample preparation, trichloroacetic acid (TCA)-based ion pairing chromatography for fast analyte separation, and multiple reaction monitoring (MRM) with stable isotope-labeled internal standards (ISs) for simultaneous quantitation. To assure the quality, our method was validated against the FDA guidelines for lower limit of quantitation (0.2 µM), linearity (square of coefficient correlation>0.99), precision (intra-&inter-assay imprecision < 10 %), accuracy (intra-&inter-assay inaccuracy < 10 %), sample preparation recovery (recovery ≥ 90 %), stability (instability < 10 %), matrix effect (signal suppression < 55 %), and carryover ( < 0.01 %). Afterward, we applied the validated method to a retrospective cross-sectional study. We aimed to evaluate the utility of serological dimethylarginines as potential cardiovascular biomarkers in the development of RA-associated CVD. Our results revealed that the serological ratio of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), an indicator of physiological arginine methylation status, was significantly elevated in patients with RA. This finding might provide value in detecting CVD to improve clinical outcomes in RA management.

Listeria monocytogenes Contamination Characteristics in Two Ready-to-Eat Meat Plants From 2019 to 2020 in Shanghai.

Listeria monocytogenes is a ubiquitous foodborne pathogen that causes listeriosis and is mostly linked to consumption of ready-to-eat (RTE) foods. Lack of hygiene in food processing environments may be a primary reason for contamination by L. monocytogenes isolates. In this study, L. monocytogenes strains isolated from two RTE meat processing plants in the Shanghai municipality, China, were characterized during 2019-2020 using pulsed-field gel electrophoresis and whole-genome sequencing. Results showed that 29 samples (12.2%) out of 239 were positive for L. monocytogenes, with 21 (18.9%) and 8 (6.25%) isolates from plants A and B, respectively. The packaging room at plant A had the most contamination (14, 48.3%; p < 0.05), with a peak occurrence of 76.5% in processing environments. Nineteen L. monocytogenes isolates belonging to the pulsotype (PT) 7 group were indistinguishable (≥ 95.7%). Furthermore, core-genome multiple loci sequencing typing identified up to nine allelic differences, and the closet pairwise differences among these ST5 isolates included 0-16 small nucleotide polymorphisms. Therefore, L. monocytogenes likely persisted at plant A during 2019-2020 with ongoing clone transmission. In contrast, no L. monocytogenes isolates were identified from processing environments at plant B. Most L. monocytogenes isolates were sampled from raw materials (62.5%). Several isolates (ST378, ST8, and ST120) were detected only once in 2020 and were considered as transient isolates. However, three ST121 isolates with the same PT (PT2) were detected in 2020 and should be noted for their stronger survival ability in harsh environments. These results suggest that continuous monitoring, stringent surveillance, and source tracking are crucial to guaranteeing food safety in RTE food plants.

Cadmium sulfide net framework nanoparticles for photo-catalyzed cell redox.

A strategy for synthesizing cadmium sulfide net framework (CdS-NF) nanoparticles was developed in a water-based system under mild reaction conditions. The CdS-NFs have not only the excellent photocatalytic properties of CdS, but also the large surface area and diverse porous structures of a metal-organic framework. An Escherichia coli-CdS-NF hybrid system was constructed using NADH regeneration to promote the conversion of trimethylpyruvate acid to l-tert-leucine. The E. coli-CdS-NF system showed higher NAD+ recycling efficiency and substrate conversion rate than CdS QDs under visible light illumination. This work demonstrates a novel method for developing a brilliant coenzyme recycling photocatalyst in bio-redox reactions.