O-acetyl-L-homoserine (OAH) is a promising platform compound for the production of L-methionine and other valuable compounds, while its low yield and low conversion rate limit the industrial application. To solve these problems, we constructed a strain for high OAH production with the previously constructed L-homoserine producer Escherichia coli HS33 as the chassis by systematic metabolic engineering. Firstly, PEP accumulation, pyruvate utilization, and OAH synthesis pathway (overexpressing aspB, aspA, and thrA^C1034T) were enhanced to obtain an initial strain accumulating 13.37 g/L OAH. Subsequently, the co-factor synthesis genes were integrated to supply reducing power and energy, which increased the yield to 15.79 g/L. The OAH yield of the engineered strain OAH28 was further increased to 17.49 g/L by strengthening the acetic acid reuse pathway, improving the supply of acetyl-CoA, and regulating the expression of MetX from different sources. Finally, in a 5 L fermenter, OAH28 achieved an OAH titer of 47.12 g/L, with a glucose conversion rate of 32% and productivity of 0.59 g/(L·h). The results lay a foundation for increasing the OAH production by metabolic engineering and give insights into the industrial production of OAH.
Metabolic Engineering/methods* ; Escherichia coli/genetics* ; Homoserine/biosynthesis* ; Fermentation

Synthetic biology is a crucial tool for the development of the bio-industry and bio-economy, representing a significant aspect of new quality productive forces. As a core course for graduate students in bioengineering, Synthetic Biology plays a vital role in ensuring the supply of essential talents for the development of the bio-industry in the new era. To better serve regional economic development and provide high-level talents for China's progress in the bio-industry, we analyzed typical issues encountered in the past teaching activities, set up a multi-disciplinary teaching team, optimized the course contents, adjusted the teaching mode, and mobilized students' learning interest. With the application of scientific research project as the starting point, we guided students to think and discuss deeply through the simulation of application writing and project defense, which improved students' critical thinking and innovative thinking. With industrialization as a focus, we explored a new training model combining production, education, and research through the joint practice base of the university and enterprises introduced typical cases of biomanufacturing to encourage students to engage in scientific research. The teaching reform significantly enhances the comprehensive abilities and national sentiments of graduate students. This paper hopes to serve as a reference for colleagues engaged in teaching in this field.
Synthetic Biology/education* ; Teaching ; China ; Humans

Objective:To investigate the effect of the sizes of osteon-like concentric microgroove structures on the osteoclastic differentiation of macrophages on titanium surfaces, and to provide reference for the surface modification of implants.Methods:The silicon wafers sputtered with titanium were selected as the control group (smooth surface specimens) and four concentric groups (concentric circles with the maximum diameter of 200 μm, the minimum diameter of 20 μ m, the spacing of concentric circles of 10 or 30 μm, the width of microgrooves of 10 or 30 μm, and the depth of microgrooves of 5 or 10 μm) specimens (the total sample size in each group was 27). The width of microgrooves of C10-5 and C10-10 groups was 10 μm, the depth was 5 and 10 μm, and the width of microgrooves of C30-5 and C30-10 groups was 30 μ m, the depth was 5 and 10 μ m, respectively. The physicochemical properties of the material surfaces were characterized using scanning electron microscopy and contact-angle measurement. The proliferation, adhesion of macrophage-like cell line RAW264.7 and the formation of osteoclast actin-rings on the specimen surfaces were observed by cell counting kit-8 (CCK-8), immunofluorescence staining and laser confocal microscopy. Tartrate resistant acid phosphatase (TRAP) quantitative detection, real-time fluorescence quantitative PCR (RT-qPCR) and Western blotting were used to investigate the regulation of osteon-like concentric microgroove structures on the specimen surfaces on the osteoclastic differentiation of macrophages.Results:Macrophages aggregated and grew disorderly on the surface of the smooth group, and arranged in concentric circles along the microgroove structures on the surfaces of the concentric groups. After 5 days of culture, the cell proliferation of C30 groups (the A values of C30-5 group and C30-10 group were 1.335±0.018 and 1.340±0.033, respectively) was significantly higher than that of C10 groups (the A values of C10-5 group and C10-10 group were 0.967±0.015 and 1.182±0.020, respectively)(all P<0.05). The cell proliferation of the four concentric groups was significantly higher than that of the control group (the A value was 0.796±0.012), with statistical significance (all P<0.05). After osteoclastic induction for 5 days the osteoclasts induced in the C10-5 and C10-10 groups exhibited smaller actin rings and fewer numbers. The TRAP activity in each concentric group was significantly lower than that in the control group ( P<0.05). The expression levels of osteoclast differentiation-related genes TRAP (0.610±0.022) in the C10-10 group was lowest, and CtsK (0.489±0.136, 0.445±0.037) in the C10-5 and C10-10 groups were lower compared to the smooth group and other concentric groups, with statistical significance (all P<0.05), the expression levels of osteoclast differentiation-related proteins TRAP (0.648±0.041), MMP-9 (0.688±0.026) in the C10-10 group were lowest, and CtsK (0.491±0.016, 0.453±0.010) in the C10-10 and C30-10 groups were also lower compared to the smooth group and other concentric groups, with statistical significance (all P<0.05). Conclusions:The osteon-like concentric microgroove structures inhibit the osteoclastic differentiation of macrophage-like cell line RAW264.7, with the microgrooves 10 μm wide and 10 μm deep showing the most significant inhibitory effect on the osteoclastic differentiation.

Objective:To compare and analyze the similarities and differences in clinical manifestations, laboratory findings, pathological characteristics, and prognosis between urticarial vasculitis (UV) and chronic spontaneous urticaria with pigmentation (CSUwp) .Methods:A retrospective analysis was conducted on the clinical data and follow-up results from 35 UV patients and 54 CSUwp patients who attended the Department of Dermatology, Southwest Hospital, Army Medical University from 2014 to 2024. The clinical characteristics (duration of rash, pigmentation, petechiae and ecchymosis, itching, burning sensation, fever, fatigue, skin lesion characteristics, etc.) , laboratory test results, pathological features, and prognosis were compared between the two groups. Statistical analysis was carried out by t test, chi-square test, Mann-Whitney U test, and Kaplan-Meier survival analysis. Results:There were no significant differences in gender, age, or age of onset between the UV group and CSUwp group (all P < 0.05) . The proportions of patients with petechiae/purpura (68.57% [24/35] vs. 11.11% [6/54]) , and those with burning sensation (22.86% [8/35] vs. 3.70% [2/54]) were significantly higher in the UV group than in the CSUwp group (both P < 0.05) . Compared with the CSUwp patients, the UV patients presented with a greater number of lesions, larger lesion areas, and more frequent involvement of the lower limbs (all P < 0.05) , also showed significantly higher incidence rates of peripheral blood complement reduction, perivascular neutrophil infiltration, nuclear dust, fibrinoid necrosis of the vessel wall, and erythrocyte extravasation (all P < 0.05) , as well as more extensive dermal perivascular inflammation ( Z = -4.506, P < 0.001) . Among patients who achieved remission, the natural disease course was significantly longer in the CSUwp patients than in the UV patients (6.00 [2.5, 24] months vs. 2.00 [0.5, 24] months; Z = -2.618, P = 0.009]. However, the survival analysis showed no significant difference in the natural disease course or clinical outcomes between the two groups ( χ2 = 2.771, P = 0.096) . There were also no significant differences in rash duration or in the incidence rates of itching, angioedema, or joint pain between the two groups (all P > 0.05) . Conclusions:UV patients exhibited certain differences from CSUwp patients in clinical characteristics, laboratory test results, histopathological features, and prognosis. However, whether their natural disease courses differ requires further follow-up studies to confirm.

Metformin has been demonstrated to attenuate hyperglycaemia by modulating the gut microbiota. However, the mechanisms through which the microbiome mediates metformin monotherapy failure (MMF) are unclear. Herein, in a prospective clinical cohort study of newly diagnosed type 2 diabetes mellitus (T2DM) patients treated with metformin monotherapy, metagenomic sequencing of faecal samples revealed that Phocaeicola vulgatus abundance was approximately 12 times higher in nonresponders than in responders. P. vulgatus rapidly hydrolysed taurine-conjugated bile acids, leading to ceramide accumulation and reversing the improvements in glucose intolerance conferred by metformin in high-fat diet-fed mice. Interestingly, C22:0 ceramide bound to mitochondrial fission factor to induce mitochondrial fragmentation and impair hepatic oxidative phosphorylation in P. vulgatus-colonized hyperglycaemic mice, which could be exacerbated by metformin. This work suggests that metformin may be unsuitable for P. vulgatus-rich T2DM patients and that clinicians should be aware of metformin toxicity to mitochondria. Suppressing P. vulgatus growth with cefaclor or improving mitochondrial function using adenosylcobalamin may represent simple, safe, effective therapeutic strategies for addressing MMF.

Although a single nucleotide polymorphism for N-acetyltransferase 10 (NAT10) has been identified in patients with early-onset stroke, the role of NAT10 in ischemic injury and the related underlying mechanisms remains elusive. Here, we provide evidence that NAT10, the only known RNA N4-acetylcytidine (ac4C) modification "writer", is increased in the damaged cortex of patients with acute ischemic stroke and the peri-infarct cortex of mice subjected to photothrombotic (PT) stroke. Pharmacological inhibition of NAT10 with remodelin on Days 3-7 post-stroke or astrocytic depletion of NAT10 via targeted virus attenuates ischemia-induced infarction and improves functional recovery in PT mice. Mechanistically, NAT10 enhances ac4C acetylation of the inflammatory cytokine tissue inhibitor of metalloproteinase 1 (Timp1) mRNA transcript, which increases TIMP1 expression and results in the accumulation of microtubule-associated protein 1 light chain 3 (LC3) and progression of astrocyte autophagy. These findings demonstrate that NAT10 regulates astrocyte autophagy by targeting Timp1 ac4C after stroke. This study highlights the critical role of ac4C in the regulation of astrocyte autophagy and proposes a promising strategy to improve post-stroke outcomes via NAT10 inhibition.

Objective:To evaluate the clinical equivalence between a domestic calcipotriol/betamethasone dipropionate ointment and the originator product in the treatment of stable plaque psoriasis.Methods:A multicenter, randomized, double-blind, three-arm, parallel-group, active- and placebo-controlled study was conducted, and 449 patients aged 18 - 65 years with stable plaque psoriasis were enrolled from 25 hospitals (such as the First Affiliated Hospital of China Medical University). Eligible patients had a baseline physician's global assessment (PGA) score of ≥ 3 points, baseline body surface area (BSA) involvement of 5% - 30%, and a target lesion psoriasis area and severity index (TL-PASI) for plaque elevation of ≥ 3 points. Participants were randomly assigned in a 2:2:1 ratio to the test group ( n = 179), reference group ( n = 180), and placebo group ( n = 90), and applied the domestic calcipotriol/betamethasone dipropionate ointment, originator product, and ointment base respectively, once daily in the evening for 4 weeks. Efficacy and safety were assessed at weeks 1, 2, and 4. The primary efficacy endpoints were the treatment success rates and clinical success rates in each group at week 4. The per-protocol set (PPS) was used for the primary efficacy analysis, and the intention-to-treat (ITT) set for supplementary efficacy analysis. Equivalence between the test and reference preparations was tested using the Cochran-Mantel-Haenszel method adjusted for randomization strata. Superiority of the test and reference preparations over the placebo was also tested. Measurement data were compared among the 3 groups using analysis of variance or non-parametric tests, while treatment success rates, clinical success rates, and incidence rates of adverse reactions were compared using the chi-square test. Results:The ITT, PPS, and safety sets included 447, 420, and 448 patients, respectively. In the ITT set, patients were aged 43.6 ± 12.8 years, including 320 (71.6%) males and 127 (28.4%) females, and the disease duration was 11.21 ± 9.05 years; 316 (70.7%) had a PGA score of 3 points and 131 (29.3%) had a PGA score of 4 - 5 points. No significant differences in the baseline characteristics (including age, sex, disease duration and disease severity) were observed among the 3 groups (all P > 0.05). Based on the PPS analysis, the treatment success rates were 57.9% (99/171) in the test group, 50.3% (86/171) in the reference group, and 7.7% (6/78) in the placebo group, and the clinical success rates were 57.9% (99/171), 50.3% (86/171), and 10.3% (8/78), respectively; both the test and reference groups were superior to the placebo group in both treatment and clinical success rates (all P < 0.001) ; the rate differences for treatment success (90% confidence interval [ CI]: -1.3% - 16.4%) and clinical success (90% CI: -1.3% - 16.3%) between the test and reference groups were entirely within the pre-defined equivalence margin (-20% - 20%). Subgroup analyses by baseline PGA scores: for patients with a baseline PGA score of 3 points, the treatment success rates in the test, reference, and placebo groups were 60.8% (73/120), 52.1% (62/119), and 11.1% (6/54), respectively, and the corresponding clinical success rates were 61.7% (74/120), 53.8% (64/119), and 13% (7/54), respectively; the test and reference groups did not differ significantly in treatment or clinical success rates (both P > 0.05), but both showed higher success rates than the placebo group (all P < 0.001) ; the results of statistical comparisons among the 3 groups in patients with a baseline PGA score of 4 - 5 points were consistent with those observed in patients with a baseline PGA score of 3 points. The percentage reductions in PGA and TL-PASI scores from baseline to weeks 1, 2, and 4 showed significant differences among the 3 groups, which were significantly higher in the test and reference groups than in the placebo group (all P < 0.001), but did not differ between the test and reference groups (all P > 0.05). The primary adverse reactions were local skin reactions, such as pruritus, pain, and erythema. The incidence rates of adverse reactions were 8.9% (16/179) in the test group, 7.3% (13/179) in the reference group, and 7.8% (7/90) in the placebo group, with no significant difference among the 3 groups ( P > 0.05) . Conclusions:The domestic calcipotriol/betamethasone dipropionate ointment demonstrated clinical equivalence to the originator product in the treatment of stable plaque psoriasis, and the two agents exhibited comparable efficacy for patients with varying degrees of disease severity, and were comparable in the speed and degree of clinical improvement, with similar favorable safety profiles.

Functional constipation is a common functional gastrointestinal disorder with a multifactorial and incompletely understood pathogenesis.Recent studies have revealed that its development involves the interplay of multiple mechanisms,including neurogenic and myogenic dysfunction of the colon,reduction and impairment of interstitial cells of Cajal(ICCs),outlet obstruction,dysregulation of the gut-brain axis,immune activation,and gut microbiota imbalance.Slow-transit constipation is mainly associated with enteric neural abnormalities,disruption of ICC signaling,and inflammation,whereas outlet obstruction constipation often results from pelvic floor dysfunction and rectal hyposensitivity.Dysregulation of the gut-brain axis plays a central role,involving impaired central regulation,hormonal imbalance,and enhanced local immune response.Additionally,gut microbial metabolites such as short-chain fatty acids,bile acids,and methane affect colonic motility and inflammation.This review summarizes the current understanding and research progress on the pathogenesis of functional constipation,providing insights for mechanism-based and individualized therapeutic approaches.

Objective: To identify an optimal back-flush solution for leukocyte-depleted filters that maximizes peripheral blood mononuclear cell (PBMC) recovery with high viability, long-term storage stability, and sterility of the harvested residues, thereby providing a clinically translatable strategy. Methods: Three sterile bag-packaged solutions—Saline, Solvent, and Hanks' balanced salt solution (HBSS)—were used to back-flush randomly assigned leukocyte-depleted filters. Nucleated cell recovery rate and viability of the harvested residues were compared. The optimal solution identified was applied to an expanded sample set. PBMC viability and yield were evaluated after 1h vs 48h storage of the residues. PBMCs isolated from the residues were cryopreserved in liquid nitrogen for 1 month, followed by post-thaw comparisons of viability and T-cell expansion capacity. Results: The Solvent group achieved the highest and most consistent nucleated cell recovery rate. Post-flush recovery rate from filters after 400 mL whole blood processing was (21.3±1.6)% for the Solvent group, significantly higher than Saline group (19.2±6.3)% and HBSS group (11.2±5.0)%, with residues from all groups maintaining viability >90%. No biologically significant difference in residue viability was observed between 48h vs 1h storage groups (93.3±2.3)% vs (95.7±1.8)%). PBMC recovery rates from residues showed no statistical difference between 48h vs 1h storage groups [(48.2%±9.5%)vs (40.41%±8.35%), P>0.05], with (17.7±2.6)×10 cells. After 1-month cryopreservation and 10-day expansion, PBMCs isolated from 48-hour-stored residues retained (91.2±3.2)% viability and achieved a (61.9±15.9)-fold expansion. Conclusion: The bag-packaged Solvent, as a back-flush solution, enables sterile acquisition of leukocyte-depleted filter residues through closed-system tubing connections. These residues maintained PBMC viability and recovery rates after 48h storage at 2℃-8℃, with post-cryopreservation (1-month liquid nitrogen) viability and expansion capacity remaining stable. This protocol complies with blood bank regulatory criteria, addresses the concerns about the infectious window period in cell therapy raw materials, and provides a clinically translatable strategy for PBMC-based applications.

Objective:To compare the efficacy of Ilizarov ring external fixation and unilateral rail external fixation in the treatment of infected bone defects following surgery for tibial fractures.Methods:A retrospective cohort study was conducted to analyze the clinical data of 50 patients with infected bone defects after surgery for tibial fractures, who were admitted to the 940th Hospital of the Joint Logistics Support Force of the PLA from August 2019 to November 2021, including 37 males and 13 females, aged 19-59 years [(42.2±8.8)years]. After debridement and osteotomy, 28 patients were treated with Ilizarov ring external fixation (Ilizarov group) and 22 with unilateral rail external fixation (unilateral fixation group). All the patients in the two groups had previously undergone internal fixation with plates or Kirschner wires for tibial fracture before bone transport. Bone transport started at one week for three stages after successful infection control and osteotomy and was conducted. The following parameters were compared between the two groups: frame-wearing time and healing index after bone transport, self-rating anxiety scale (SAS) grade at 6 months after bone transport, Paley score and Association for the Study and Application of the Method of Ilizarov (ASAMI) score at the last follow-up, Hospital for Special Surgery (HSS) knee score and Baird-Jackson ankle score on admission, after external fixator removal and at the last follow-up, and incidence of postoperative complications.Results:All the patients were followed up for 28-36 months [(32.5±1.6)months]. There were no significant differences in frame-wearing time or healing index between the two groups after bone transport ( P>0.05). At 6 months after bone transport, the SAS grade in the unilateral fixation group (13 patients with mild anxiety, 8 with moderate anxiety, and 1 with severe anxiety) was better than that in the Ilizarov group (6 patients with mild anxiety, 19 with moderate anxiety, 3 with severe anxiety) ( P<0.01). No significant differences were found in the Paley score or ASAMI score between the two groups at the last follow-up ( P>0.05). There were no significant differences in HSS knee score or Baird-Jackson ankle score between the two groups on admission, after external fixator removal or at the last follow-up ( P>0.05). No significant differences were observed in the incidence of pin tract infection, poor healing, infection in the bone elongation area, or re-fracture between the two groups ( P>0.05). The incidence of postoperative axial deviation was 0 in the Ilizarov group, lower than 18% in the unilateral fixation group (4/22) ( P<0.05). Conclusion:Although Ilizarov ring external fixation and unilateral rail external fixation demonstrate comparable efficacy in the treatment of infected bone defects after surgery for tibial fractures, the former provides superior mechanical stability and postoperative axial deviation correction, while the latter offers advantages in reducing psychological burden and enhancing treatment tolerance.