Molecular insight into the potential functional role of pseudoenzyme GFOD1 via interaction with NKIRAS2.

The glucose-fructose oxidoreductase/inositol dehydrogenase/rhizopine catabolism protein (Gfo/Idh/MocA) family includes a variety of oxidoreductases with a wide range of substrates that utilize NAD or NADP as redox cofactor. Human contains two members of this family, namely glucose-fructose oxidoreductase domain-containing protein 1 and 2 (GFOD1 and GFOD2). While GFOD1 exhibits low tissue specificity, it is notably expressed in the brain, potentially linked to psychiatric disorders and severe diseases. Nevertheless, the specific function, cofactor preference, and enzymatic activity of GFOD1 remain largely unknown. In this work, we find that GFOD1 does not bind to either NAD or NADP. Crystal structure analysis unveils that GFOD1 exists as a typical homodimer resembling other family members, but lacks essential residues required for cofactor binding, suggesting that it may function as a pseudoenzyme. Exploration of GFOD1-interacting partners in proteomic database identifies NK-κB inhibitor-interacting Ras-like 2 (NKIRAS2) as one potential candidate. Co-immunoprecipitation (co-IP) analysis indicates that GFOD1 interacts with both GTP- and GDP-bound forms of NKIRAS2. The predicted structural model of the GFOD1-NKIRAS2 complex is validated in cells using point mutants and shows that GFOD1 selectively recognizes the interswitch region of NKIRAS2. These findings reveal the distinct structural properties of GFOD1 and shed light on its potential functional role in cellular processes.

Blinatumomab in Children with MRD-Positive B-Cell Precursor Acute Lymphoblastic Leukemia: A Report of 11 Cases.

Background/Objectives: Relapsed B-cell acute lymphoblastic leukemia (B-ALL) remains an unresolved matter of concern regarding adverse outcomes. This case study aimed to evaluate the effectiveness of blinatumomab, with or without door lymphocyte infusion (DLI), in treating measurable residual disease (MRD)-positive B-ALL. Methods: All patients who received blinatumomab salvage therapy were included in this study. Eleven patients were included in the study. All patients were evaluated for MRD-negativity. Results: Before starting blinatumomab therapy, seven patients tested positive for MRD, three tested negative, and one had refractory disease. Hematopoietic cell transplantation (HCT) was reserved for five patients with persistent MRD. Six patients became MRD-negative and subsequent HCT was not performed. Only two patients relapsed; one patient died of relapse, and the other one received carfilzomib-based therapy and was MRD-negative thereafter. Nine patients were MRD-negative at a median follow-up of 28 months (15-52 months). Two of three MRD-positive post-transplant patients remained in complete molecular remission after preemptive DLI at the last follow-up date. In the first salvage, blinatumomab may achieve complete remission and bridging to HCT in pediatric patients with end-of-induction MRD-positive B-cell precursor ALL. Conclusions: The decision on how to treat post-transplant relapse continues to affect survival outcomes. Blinatumomab combined with DLI may extend the armamentarium of release options for high-risk pediatric patients. This approach is encouraging for high-risk ALL patients who are MRD-positive post-transplantation.

Close outpatient follow-up associated with reduced readmission rates in patients with inflammatory bowel disease.

Background: Few studies have shown the effects of prompt outpatient follow-up in relation to reducing readmission rates in patients hospitalized with inflammatory bowel disease (IBD). Our study evaluated whether postdischarge follow-up was associated with fewer IBD-related readmissions. Methods: This single-center retrospective study included 477 patients with Crohn's disease (CD) or ulcerative colitis (UC) who were readmitted to our tertiary care hospital from January 1, 2016, to June 1, 2022. Rehospitalization admissions were defined as admissions that occurred within 90 days after discharge date. We used a chi-square or Fisher's exact test to test for bivariate comparisons to determine if there was an association in patients readmitted for IBD and primary care or gastroenterology follow-up at 1, 2, 3, and 4 weeks versus no follow-up. Results: In UC patients, there were 118 admissions from 2016 to 2022; 36/118 (31%) and 41/118 (34.7%) of the patients were readmitted at 30 days and 90 days, respectively. In the CD group, there were 101 (36.73%) readmissions among 277 patients, with 174 nonreadmissions (63.27%). Conclusions: Gastroenterology follow-up within 1 month was associated with reduced rates of admission in both groups (P < 0.05). This study highlights the importance of close gastroenterology follow-up for IBD-related hospitalizations.

Research Progress on Ti3C2Tx-Based Composite Materials in Antibacterial Field.

The integration of two-dimensional Ti3C2Tx nanosheets and other materials offers broader application options in the antibacterial field. Ti3C2Tx-based composites demonstrate synergistic physical, chemical, and photodynamic antibacterial activity. In this review, we aim to explore the potential of Ti3C2Tx-based composites in the fabrication of an antibiotic-free antibacterial agent with a focus on their systematic classification, manufacturing technology, and application potential. We investigate various components of Ti3C2Tx-based composites, such as metals, metal oxides, metal sulfides, organic frameworks, photosensitizers, etc. We also summarize the fabrication techniques used for preparing Ti3C2Tx-based composites, including solution mixing, chemical synthesis, layer-by-layer self-assembly, electrostatic assembly, and three-dimensional (3D) printing. The most recent developments in antibacterial application are also thoroughly discussed, with special attention to the medical, water treatment, food preservation, flexible textile, and industrial sectors. Ultimately, the future directions and opportunities are delineated, underscoring the focus of further research, such as elucidating microscopic mechanisms, achieving a balance between biocompatibility and antibacterial efficiency, and investigating effective, eco-friendly synthesis techniques combined with intelligent technology. A survey of the literature provides a comprehensive overview of the state-of-the-art developments in Ti3C2Tx-based composites and their potential applications in various fields. This comprehensive review covers the variety, preparation methods, and applications of Ti3C2Tx-based composites, drawing upon a total of 171 English-language references. Notably, 155 of these references are from the past five years, indicating significant recent progress and interest in this research area.

Biomechanical comparisons of F.E.R.I. techniques with different type of intramedullary screws fixation for Jones fractures.

Introduction: Jones fractures frequently fail to unite, and adequate fixation stability is crucial. This study aimed to elucidate the biomechanical stability of various intramedullary screw fixation constructs. Methods: Jones fracture model over the proximal 5th metatarsal of artificial bone was created in all specimens. Six groups were divided based on varied screw constructs with different screw lengths, either 30 or 40 mm, including cannulated screws-C30 and C40 groups, one high-resistance suture combined with intramedullary cannulated screws (F.E.R.I. technique)-CF30 and CF40 groups, and second-generation headless compression screws (SG-HCS) -HL30 and HL40 groups. Mechanical testing was conducted sequentially, and the maximal force (N) and stiffness (N/mm) of all constructs were recorded. Results: The maximal force (N) at 1.0 mm downward displacement in C30, C40, CF30, CF40, HL30, and HL40 groups were 0.56 ± 0.02, 0.49 ± 0.02, 0.65 ± 0.02, 0.49 ± 0.01, 0.68 ± 0.02, and 0.73 ± 0.02, respectively, and the stiffness (N/mm) in subgroups were 0.49 ± 0.01, 0.43 ± 0.01, 0.67 ± 0.01, 0.42 ± 0.01, 0.61 ± 0.01, and 0.58 ± 0.02, respectively. SG-HCS subgroups exhibited greater maximal force and stiffness than conventional cannulated screws. Screws of 30 mm in length demonstrated better stability than all 40 mm-length screws in each subgroup. In C30 fixation, the stiffness and maximum force endured increased by 1.16 and 1.12 times, respectively, compared with the C40 fixation method. There were no significant differences between CF30 and SG-HCS groups. Only the F.E.R.I technique combined with the 4.5 mm cannulated screw of 30 mm in length increased the biomechanical stability for Jones fractures. Discussion: These biomechanical findings help clinicians decide on better screw fixation options for greater stability in Jones fractures, especially when large-diameter screws are limited in use. However, this biomechanical testing of intramedullary screw fixation on Jones fracture model lacks clinical validation and no comparisons to extramedullary plate fixations. Moving forward, additional clinical and biomechanical research is necessary to validate our findings.

Outcome of Tocilizumab Treatment in Febrile Neutropenic Children with Severe Sepsis/Septic Shock in a Single-Center Retrospective Case Series.

PURPOSE: To assess the efficacy of an IL-6 blockade with tocilizumab on treatment outcome of severe sepsis/septic shock in children with febrile neutropenia. METHODS: We performed a retrospective study of febrile neutropenic patients younger than 18 years old who developed severe sepsis/septic shock at a single medical center between November 2022 and October 2023. RESULTS: Seven patients with febrile neutropenia complicated with severe sepsis/septic shock were identified. Four of seven patients received tocilizumab in addition to standard of care. The median IL-6 level before administration of tocilizumab was 14,147 pg/mL (range: 672-30,509 pg/mL). All four patients successfully recovered from severe sepsis/septic shock. Three of seven patients received standard of care without tocilizumab. IL-6 levels were checked intwo2 patients, with a median of 1514.5 (range: 838-2191). Only one of three (33%) patients without tocilizumab therapy made a full recovery from severe sepsis/septic shock. The mortality rate was higher in patients without tocilizumab therapy compared to patients with tocilizumab therapy (67% vs. 0%). CONCLUSIONS: Administration of tocilizumab reduced mortality of severe sepsis/septic shock in children with febrile neutropenia. However, it warrants confirmation with a larger number of patients and a longer follow-up.

Immunoenhancement effect of cinobufagin on macrophages and the cyclophosphamide-induced immunosuppression mouse model.

Cinobufagin (CBG) is a natural active substance. Although its various pharmacological activities have been explored, the immunomodulatory activity of CBG remains unexplored. Therefore, this study aimed to investigate the anti-inflammatory and immunomodulatory activities of CBG ex vivo and in vivo. The immunomodulatory activity of CBG was investigated in RAW 264.7 cells. CBG showed no significant toxicity to cells. Additionally, 0.5-8 µg/mL CBG significantly increased the phagocytosis ability of macrophages and the secretion levels of IL-1ß and TNF-α. Thus, it exerted immunomodulatory effects. We established the immunosuppressive model induced by cyclophosphamide (CTX) in mice and studied the immunomodulatory activity of CBG in vivo. The experimental results showed that the intervention of CBG alleviated the CTX-induced weight loss, restored the lymphocyte nuclear cell number, and promoted the secretion and mRNA expression of cytokines IFN-γ, IL-4, IL-6, and IL-12. Moreover, CBG increased the immune organ index, protected the growth of the spleen and thymus, and improved the pathological changes in immunosuppressed mice. Western blot results showed that different concentrations of CBG upregulated the phosphorylation level of PI3K/Akt/mTOR in the spleen of CTX-induced immunosuppressed mice. This suggests that the immunomodulatory effect of CBG may be related to the regulation of PI3K/Akt/mTOR signaling pathway. This study provides a theoretical basis for developing CBG immune enhancers and opens up new ideas for the comprehensive utilization and development of CBG in factories.

Comprehensive analysis of lactate-related gene profiles and immune characteristics in lupus nephritis.

Objectives: The most frequent cause of kidney damage in systemic lupus erythematosus (SLE) is lupus nephritis (LN), which is also a significant risk factor for morbidity and mortality. Lactate metabolism and protein lactylation might be related to the development of LN. However, there is still a lack of relative research to prove the hypothesis. Hence, this study was conducted to screen the lactate-related biomarkers for LN and analyze the underlying mechanism. Methods: To identify differentially expressed genes (DEGs) in the training set (GSE32591, GSE127797), we conducted a differential expression analysis (LN samples versus normal samples). Then, module genes were mined using WGCNA concerning LN. The overlapping of DEGs, critical module genes, and lactate-related genes (LRGs) was used to create the lactate-related differentially expressed genes (LR-DEGs). By using a machine-learning algorithm, ROC, and expression levels, biomarkers were discovered. We also carried out an immune infiltration study based on biomarkers and GSEA. Results: A sum of 1259 DEGs was obtained between LN and normal groups. Then, 3800 module genes in reference to LN were procured. 19 LR-DEGs were screened out by the intersection of DEGs, key module genes, and LRGs. Moreover, 8 pivotal genes were acquired via two machine-learning algorithms. Subsequently, 3 biomarkers related to lactate metabolism were obtained, including COQ2, COQ4, and NDUFV1. And these three biomarkers were enriched in pathways 'antigen processing and presentation' and 'NOD-like receptor signaling pathway'. We found that Macrophages M0 and T cells regulatory (Tregs) were associated with these three biomarkers as well. Conclusion: Overall, the results indicated that lactate-related biomarkers COQ2, COQ4, and NDUFV1 were associated with LN, which laid a theoretical foundation for the diagnosis and treatment of LN.

Facial recognition technology and human raters can predict political orientation from images of expressionless faces even when controlling for demographics and self-presentation.

Carefully standardized facial images of 591 participants were taken in the laboratory while controlling for self-presentation, facial expression, head orientation, and image properties. They were presented to human raters and a facial recognition algorithm: both humans (r = .21) and the algorithm (r = .22) could predict participants' scores on a political orientation scale (Cronbach's α = .94) decorrelated with age, gender, and ethnicity. These effects are on par with how well job interviews predict job success, or alcohol drives aggressiveness. The algorithm's predictive accuracy was even higher (r = .31) when it leveraged information on participants' age, gender, and ethnicity. Moreover, the associations between facial appearance and political orientation seem to generalize beyond our sample: The predictive model derived from standardized images (while controlling for age, gender, and ethnicity) could predict political orientation (r ≈ .13) from naturalistic images of 3,401 politicians from the United States, the United Kingdom, and Canada. The analysis of facial features associated with political orientation revealed that conservatives tended to have larger lower faces. The predictability of political orientation from standardized images has critical implications for privacy, the regulation of facial recognition technology, and understanding the origins and consequences of political orientation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Melatonin is a potential novel analgesic agent for osteoarthritis: Evidence from cohort studies in humans and preclinical research in rats.

Melatonin exhibits potential for pain relief and long-term safety profile. We examined the analgesic effects of oral melatonin on osteoarthritis (OA) and investigated the underlying mechanism. Using data from a UK primary care database, we conducted a cohort study in individuals with OA to compare the number of oral analgesic prescriptions and the risk of knee/hip replacement between melatonin initiators and hypnotic benzodiazepines (i.e., active comparator) initiators using quantile regression models and Cox-proportional hazard models, respectively. To elucidate causation, we examined the effects of melatonin on pain behaviors and explored several metabolites that may serve as potential regulatory agents of melatonin in the monoiodoacetate rat model of OA. Using data from another community-based cohort study, that is, the Xiangya OA Study, we verified the association between the key serum metabolite and incident symptomatic knee OA. Compared with the hypnotic benzodiazepines cohort (n = 8135), the melatonin cohort (n = 813) had significantly fewer subsequent prescriptions of oral analgesics (50th percentile: 5 vs. 7, 75th percentile: 19 vs. 29, and 99th percentile: 140 vs. 162) and experienced a lower risk of knee/hip replacement (hazard ratio = 0.47, 95% Cl: 0.30-0.73) during the follow-up period. In rats, oral melatonin alleviated pain behaviors and increased serum levels of glycine. There was an inverse association between baseline serum glycine levels and the risk of incident symptomatic knee OA in humans (n = 760). In conclusion, our findings indicate that oral melatonin shows significant potential to be a novel treatment for OA pain. The potential role of glycine in its analgesic mechanism warrants further investigation.

Vitiligo and Alopecia Areata After Donor Lymphocyte Infusions in a Child With Relapsed Acute Myeloid Leukemia.

Rarely do patients with chronic graft-versus-host disease (cGVHD) experience vitiligo and alopecia areata. Nevertheless, the exact cause of vitiligo and alopecia areata is still not fully understood. The patient experienced a relapse of acute myeloid leukemia (AML) following a second complete remission after undergoing HLA-6/8 mismatched unrelated donor hematopoietic cell transplantation (HCT). Achieving full donor chimerism was successful during the initial stages of the transplant. Nevertheless, the molecular evidence of measurable residual disease remained, prompting the administration of donor lymphocyte infusions (DLI) following a dose-escalation protocol. After three cycles of DLI given at two-month intervals, the circulating blasts eventually vanished. After the third DLI dose, vitiligo developed despite achieving molecular remission. The dermatologist confirmed the presence of vitiligo and alopecia areata, along with cutaneous cGVHD. The outcome was the complete elimination of the molecular presence, and the patient experienced both clinical and molecular remission for a period of five years following DLI. Based on our observations, it was found that DLI could effectively eradicate molecular leukemia in cases of AML relapse after HCT. The development of vitiligo and alopecia areata was influenced by the destruction of melanocytes due to autoimmune reactions caused by cGVHD.

Early Allogeneic Transplantation Favorably Influences the Outcome of Pediatric Acute Myeloid Leukemia-A Retrospective Study in a Single Center Over 2 Decades.

BACKGROUND: Transplantation advancements offer the potential for improving the prognosis of patients with acute myeloid leukemia (AML). Controversies surrounding indications and timing persist. We focused on identifying prognostic factors and exploring the advantages of early transplantation. PATIENTS AND METHODS: We studied 102 pediatric patients with AML (February 1999-August 2022), using Cox regression to analyze survival and hematopoietic cell transplantation (HCT) outcomes and Kaplan-Meier curves to assess HCT timing's impact on prognosis. RESULTS: "Treatment in First Complete Remission [CR1]: Chemotherapy" showed increased risk in multivariate and univariate Cox regression analyses, whereas "HCT during the study period" displayed divergent outcomes. Focusing on transplanted patients, "Treatment in CR1: Chemotherapy" still correlated with higher mortality risk. These findings emphasize the pivotal role of the treatment strategy adopted in CR1 on overall survival rather than HCT alone. Donor cytomegalovirus (CMV) positivity is also related to reduced mortality risk. Kaplan-Meier analysis supported superior 5-year survival rates with "HCT" compared with "chemotherapy" in CR1. In the 3-arm analysis, "HCT in CR1" demonstrated better 5-year overall survival (OS) and 5-year disease-free survival (DFS) compared with "Never HCT," whereas "HCT in CR2" had the least favorable prognosis (5-year OS: 79.2% vs 57.1% vs 50%, P = .056; 5-year DFS: 73.6% vs 55.2% vs 0%, P = .000). CONCLUSION: Our study highlights the benefits of transplantation during CR1 on prognosis. However, when contemplating CR1 transplantation recommendations, evaluation of various factors, such as the patient's clinical state, relapse risk, transplant-related mortality, CMV status, and other pertinent considerations, is vital. Comprehensive case discussions with patients and families are demanded in optimizing treatment.

Structural basis for substrate and antibiotic recognition by Helicobacter pylori isoleucyl-tRNA synthetase.

Helicobacter pylori infection is a global health concern, affecting over half of the world's population. Acquiring structural information on pharmacological targets is crucial to facilitate inhibitor design. Here, we have determined the crystal structures of H. pylori isoleucyl-tRNA synthetase (HpIleRS) in apo form as well as in complex with various substrates (Ile, Ile-AMP, Val, and Val-AMP) or an inhibitor (mupirocin). Our results provide valuable insights into substrate specificity, recognition, and the mechanism by which HpIleRS is inhibited by an antibiotic. Moreover, we identified Asp641 as a prospective regulatory site and conducted biochemical analyses to investigate its regulatory mechanism. The detailed structural information acquired from this research holds promise for the development of highly selective and effective inhibitors against H. pylori infection.

Diagnostic Accuracy of Ultrasound for Assessment of Synovial Abnormalities Among Patients With Knee Pain: A Meta-Analysis.

OBJECTIVE: Synovial abnormalities, which are modifiable treatment targets for knee pain, affect ~25% of adults. Ultrasound is a safe, inexpensive, and easily accessible imaging modality for assessing synovial abnormalities, but its diagnostic accuracy is still controversial. We conducted a meta-analysis by comparing ultrasound with the "reference standard" method, ie, magnetic resonance imaging (MRI), in assessing synovial abnormalities among patients with knee pain. METHODS: PubMed, Embase, and Web of Science were searched from inception to January 7, 2022, to retrieve studies including patients with knee pain for evaluating 1) the diagnostic accuracy of ultrasound versus MRI for synovial abnormalities (synovitis and synovial effusion) and 2) the correlations of synovial abnormalities assessed by ultrasound and MRI. The summary of diagnostic accuracy was analyzed using the bivariate model, and the correlation coefficients were pooled using the random effects model. RESULTS: Fourteen studies were included, representing a total of 755 patients. The pooled sensitivity, specificity, and area under the curve were 0.88 (95% confidence interval [95% CI] 0.65-0.96), 0.70 (95% CI 0.51-0.84), and 0.81 (95% CI 0.77-0.84) for synovitis and 0.90 (95% CI 0.81-0.95), 0.86 (95% CI 0.77-0.92), and 0.94 (95% CI 0.91-0.96) for synovial effusion, respectively. Strong correlations between ultrasound- and MRI-diagnosed synovitis (r = 0.64, 95% CI 0.56-0.71) and synovial effusion (r = 0.63, 95% CI 0.52-0.73) were observed. CONCLUSION: Ultrasound demonstrated a promising accuracy in detecting synovial abnormalities among patients with knee pain. The use of ultrasound provides equivalent synovial information to MRI but is less expensive and more accessible. Therefore, it is recommended as an adjuvant for managing patients with knee pain during diagnostic strategy and individualized treatment decision-making.

Insight into a natural novel histidine decarboxylase gene deletion in Enterobacter hormaechei RH3 from traditional Sichuan-style sausage.

Histamine (HIS) is primarily formed from decarboxylated histidine by certain bacteria with histidine decarboxylase (hdc) activity and is the most toxic biogenic amine. Hdc, which is encoded by the hdc gene, serves as a key enzyme that controls HIS production in bacteria. In this paper, we characterized the changes in microbial and biogenic amines content of traditional Sichuan-style sausage before and after storage and demonstrated that Enterobacteriaceae play an important role in the formation of HIS. To screen for Enterobacteriaceae with high levels of HIS production, we isolated strain RH3 which has a HIS production of 2.27 mg/mL from sausages stored at 37°C for 180 days, using selective media and high-performance liquid chromatography. The strain RH3 can produce a high level of HIS after 28 h of fermentation with a significant hysteresis. Analysis of the physicochemical factors revealed that RH3 still retained its ability to partially produce HIS in extreme environments with pH 3.5 and 10.0. In addition, RH3 exhibited excellent salt tolerance (6.0% NaCl and 1.0% NaNO2 ). Subsequently, RH3 was confirmed as Enterobacter hormaechei with hdc gene deletion by PCR, western blot, and whole-genome sequencing analysis. Furthermore, RH3 exhibited pathogenicity rate of 75.60% toward the organism, indicating that it was not a food-grade safe strain, and demonstrated a high level of conservation in intraspecific evolution. The results of this experiment provide a new reference for studying the mechanism of HIS formation in microorganisms. PRACTICAL APPLICATION: This study provides a new direction for investigating the mechanism of histamine (HIS) formation by microorganisms and provides new insights for further controlling HIS levels in meat products. Further research can control the key enzymes that form HIS to control HIS levels in food.

Construction of a novel cell-free tracheal scaffold promoting vascularization for repairing tracheal defects.

Functional vascularization is crucial for maintaining the long-term patency of tissue-engineered trachea and repairing defective trachea. Herein, we report the construction and evaluation of a novel cell-free tissue-engineered tracheal scaffold that effectively promotes vascularization of the graft. Our findings demonstrated that exosomes derived from endothelial progenitor cells (EPC-Exos) enhance the proliferation, migration, and tube formation of endothelial cells. Taking advantage of the angiogenic properties of EPC-Exos, we utilized methacrylate gelatin (GelMA) as a carrier for endothelial progenitor cell exosomes and encapsulated them within a 3D-printed polycaprolactone (PCL) scaffold to fabricate a composite tracheal scaffold. The results demonstrated the excellent angiogenic potential of the methacrylate gelatin/vascular endothelial progenitor cell exosome/polycaprolactone tracheal scaffold. Furthermore, in vivo reconstruction of tracheal defects revealed the capacity of this composite tracheal stent to remodel vasculature. In conclusion, we have successfully developed a novel tracheal stent composed of methacrylate gelatin/vascular endothelial progenitor exosome/polycaprolactone, which effectively promotes angiogenesis for tracheal repair, thereby offering significant prospects for clinical and translational medicine.

Association between gut microbiome-related metabolites and symptomatic hand osteoarthritis in two independent cohorts.

BACKGROUND: Since gut microbiome dysbiosis can cause inflammatory disorders by affecting host metabolism, we postulate that the gut microbiome and related metabolites could play a role in hand osteoarthritis. We characterised gut microbiome-related metabolites in people with symptomatic hand osteoarthritis (SHOA) in two independent cohorts. METHODS: Using data collected from a large-sample community-based observational study (discovery cohort), we assessed the relations of the microbial function and plasma key metabolites related to altered microbial function with SHOA. Finally, we verified the relations of plasma metabolites to SHOA in an independent observational study (validation cohort). FINDINGS: In the discovery cohort (n = 1359), compared to those without SHOA, participants with SHOA had significantly altered microbial functions related to tryptophan metabolism (Q = 0.025). Therefore we measured the plasma tryptophan metabolites and found that participants with SHOA had higher levels of 5-hydroxyindoleacetic acid (odds ratio [OR] = 1.25, 95% confidence interval [CI]: 1.09-1.42) and 5-hydroxytryptophol (OR = 1.13, 95% CI: 1.04-1.23), but lower levels of indole-3-lactic acid (ILA) (OR = 0.85, 95% CI: 0.72-1.00), skatole (OR = 0.93, 95% CI: 0.88-0.99) and 3-hydroxyanthranilic acid (OR = 0.90, 95% CI: 0.85-0.96). Findings from the validation cohort (n = 142) verified that lower levels of ILA were related to SHOA (OR = 0.70, 95% CI: 0.53-0.92). INTERPRETATION: Alterations of the microbial function of tryptophan biosynthesis and tryptophan metabolites, especially lower levels of ILA, are associated with SHOA. These findings suggest the role of the microbiome and tryptophan metabolites in developing of SHOA and may contribute to future translational opportunities. FUNDING: National Key Research and Development Plan and National Natural Science Foundation of China.

Research of Multicopper Oxidase and Its Degradation of Histamine in Lactiplantibacillus plantarum LPZN19.

In order to explore the structural changes and products of histamine degradation by multicopper oxidase (MCO) in Lactiplantibacillus plantarum LPZN19, a 1500 bp MCO gene in L. plantarum LPZN19 was cloned, and the recombinant MCO was expressed in E. coli BL21 (DE3). After purification by Ni2+-NTA affinity chromatography, the obtained MCO has a molecular weight of 58 kDa, and it also has the highest enzyme activity at 50 °C and pH 3.5, with a relative enzyme activity of 100%, and it maintains 57.71% of the relative enzyme activity at 5% salt concentration. The secondary structure of MCO was determined by circular dichroism, in which the proportions of the α-helix, ß-sheet, ß-turn and random coil were 2.9%, 39.7%, 21.2% and 36.1%, respectively. The 6xj0.1.A with a credibility of 68.21% was selected as the template to predict the tertiary structure of MCO in L. plantarum LPZN19, and the results indicated that the main components of the tertiary structure of MCO were formed by the further coiling and folding of a random coil and ß-sheet. Histamine could change the spatial structure of MCO by increasing the content of the α-helix and ß-sheet. Finally, the LC-MS/MS identification results suggest that the histamine was degraded into imidazole acetaldehyde, hydrogen peroxide and ammonia.