T7 RNA polymerase (T7 RNAP) is one of the simplest known RNA polymerases. Its unique structural features make it a critical model for studying the mechanisms of RNA synthesis. This review systematically examines the static crystal structure of T7 RNAP, beginning with an in-depth examination of its characteristic “thumb”, “palm”, and “finger” domains, which form the classic “right-hand-like” architecture. By detailing these structural elements, this review establishes a foundation for understanding the overall organization of T7 RNAP. This review systematically maps the functional roles of secondary structural elements and their subdomains in transcriptional catalysis, progressively elucidating the fundamental relationships between structure and function. Further, the intrinsic flexibility of T7 RNAP and its applications in research are also discussed. Additionally, the review presents the structural diagrams of the enzyme at different stages of the transcription process, and through these diagrams, it provides a detailed description of the complete transcription process of T7 RNAP. By integrating structural dynamics and kinetics analyses, the review constructs a comprehensive framework that bridges static structure to dynamic processes. Despite its advantages, T7 RNAP has a notable limitation: it generates double-stranded RNA (dsRNA) as a byproduct. The presence of dsRNA not only compromises the purity of mRNA products but also elicits nonspecific immune responses, which pose significant challenges for biotechnological and therapeutic applications. The review provides a detailed exploration of the mechanisms underlying dsRNA formation during T7 RNAP catalysis, reviews current strategies to mitigate this issue, and highlights recent progress in the field. A key focus is the semi-rational design of T7 RNAP mutants engineered to minimize dsRNA generation and enhance catalytic performance. Beyond its role in transcription, T7 RNAP exhibits rapid development and extensive application in fields, including gene editing, biosensing, and mRNA vaccines. This review systematically examines the structure-function relationships of T7 RNAP, elucidates the mechanisms of dsRNA formation, and discusses engineering strategies to optimize its performance. It further explores the engineering optimization and functional expansion of T7 RNAP. Furthermore, this review also addresses the pressing issues that currently need resolution, discusses the major challenges in the practical application of T7 RNAP, and provides an outlook on potential future research directions. In summary, this review provides a comprehensive analysis of T7 RNAP, ranging from its structural architecture to cutting-edge applications. We systematically examine: (1) the characteristic right-hand domains (thumb, palm, fingers) that define its minimalistic structure; (2) the structure-function relationships underlying transcriptional catalysis; and (3) the dynamic transitions during the complete transcription cycle. While highlighting T7 RNAP’s versatility in gene editing, biosensing, and mRNA vaccine production, we critically address its major limitation—dsRNA byproduct formation—and evaluate engineering solutions including semi-rationally designed mutants. By synthesizing current knowledge and identifying key challenges, this work aims to provide novel insights for the development and application of T7 RNAP and to foster further thought and progress in related fields.

Objective: To investigate the characteristics of malignant tumor incidence and mortality in cancer registration areas of Sichuan Province in 2021. Methods: Cancer registration data from 142 registries in Sichuan Province in 2021 were collected via the China Cancer Registry Platform. Crude incidence and crude mortality were calculated. The Chinese population-standardized incidence and world population-standardized incidence were standardized using the age structure of the standard population from the Fifth National Population Census in 2000 and Segi's world standard population. Descriptive analyses examined the distribution of rates by genders, urban/rural areas, and ages, and the ranking of leading cancer sites. Results: In 2021, there were 248 600 new malignant tumor cases reported in Sichuan Province, with a crude incidence of 296.37/100 000. The Chinese population-standardized incidence and world population-standardized incidence were 164.67/100 000 and 160.47/100 000, respectively. There were 158 673 malignant tumor deaths, with a crude mortality of 189.16/100 000. The Chinese population-standardized mortality and world population-standardized mortality were 92.47/100 000 and 92.00/100 000, respectively. The Chinese population-standardized incidence and mortality in males were higher than in females (179.56/100 000 vs. 151.62/100 000, 125.09/100 000 vs. 60.35/100 000). The Chinese population-standardized incidence and mortality in urban areas were higher than in rural areas (175.74/100 000 vs. 157.54/100 000, 93.63/100 000 vs. 91.82/100 000). Both the crude incidence and crude mortality increased with age. The top ten malignant tumors by crude incidence were lung cancer, colorectal cancer, liver cancer, breast cancer, esophageal cancer, gastric cancer, cervical cancer, prostate cancer, thyroid cancer, and corpus uteri cancer, accounting for 76.33% of all new cases. The top ten by crude mortality were lung cancer, liver cancer, esophageal cancer, colorectal cancer, gastric cancer, breast cancer, pancreatic cancer, cervical cancer, prostate cancer, and brain tumors, accounting for 82.39% of all cancer deaths. Conclusions In registration areas of Sichuan Province, the incidence and mortality of malignant tumors are relatively low. Key populations such as males, urban residents, and the elderly require focused prevention and control efforts. Comprehensive measures should be prioritized for malignant tumors including lung cancer, liver cancer, esophageal cancer, gastric cancer, colorectal cancer, and breast cancer.

Objective:To analysis the job preference and heterogeneity of medical students by distinguishing their birthplaces,and to provide reference for optimizing the management of primary health care resources.Methods:Using a cluster sampling method,an online survey of discrete choice experiment was conducted with 925 medical students from six teaching hospitals in Beijing,741 valid questionnaires were obtained,the effective recovery rate was 80.1%.The mixed logit model was used to perform regression analysis on six job attributes and estimate the willingness to pay.Results:There were significant differences in the choice of work location among medical students from different birthplaces.The subgroup results showed that compared to medical students from city,undergraduates from rural and county district preferred a work with sufficient career development opportunities.The results of undergraduate subgroup showed that undergraduates from rural district preferred a work with good environment than those from other birthplaces.Conclusion:There is heterogeneity in job preferences of medical students from different birthplaces.Policy makers should pay attention to the medical students'birthplace,also take the educational level into account to optimize the diversified job attributes,formulating targeted intervention to attract primary health care talents.

ObjectiveTo explore whether the mechanism of Shuangshen Ningxin capsules （SSNX） in alleviating myocardial ischemia-reperfusion injury （MIRI） in rats is related to the regulation of mitochondrial fission and fusion. MethodThis study focused on Sprague Dawley （SD） rats and ligated the left anterior descending branch of the coronary artery to construct a rat model of MIRI. The rats were divided into the sham operation group， model group， SSNX group （90 mg·kg^-1） and trimetazidine group （5.4 mg·kg^-1）. The activity of superoxide dismutase （SOD） and the content of malondialdehyde （MDA） were detected by micro method. Changes in mitochondrial membrane potential （△Ψm） and the degree of mitochondrial permeability transition pore （mPTP） opening were detected by the chemical fluorescence method. The intracellular adenosine triphosphate （ATP） level was detected by the luciferase assay. The messenger ribonucleic acid （mRNA） and protein expression levels of mitochondrial fission and fusion related factors dynamin-related protein 1 （DRP1）， mitochondrial fission 1 protein （FIS1）， optic atrophy protein 1 （OPA1）， mitochondrial outer membrane fusion protein 1 （MFN1）， and MFN2 were detected by real-time polymerase chain reaction （real-time PCR） and Western blot. ResultCompared with the sham operation group， the model group showed a decrease in serum SOD activity and an increase in MDA content. The opening level of mPTP， the level of △Ψm and ATP content decreased， the protein expressions of mitochondrial fission factors DRP1 and FIS1 increased， and the protein expressions and mRNA transcription levels of fusion related factors OPA1 and MFN1 decreased. Compared with the model group，SSNX significantly increased serum SOD activity， reduced MDA content， increased intracellular ATP level and △Ψm， reduced the opening level of mPTP， downregulated the protein expressions of mitochondrial fission factors DRP1 and FIS1， and increased the mRNA transcription levels and protein expressions of fusion related factors OPA1 and MFN1. ConclusionSSNX inhibits the expressions of mitochondrial fission factors DRP1 and FIS1， and increases the expressions of fusion related factors OPA1 and MFN1， inhibiting mitochondrial fission and increasing mitochondrial fusion， thereby alleviating MIRI.

The paper is to establish an UPLC-MS/MS method for the simultaneous determination of 19 components in Microctis Folium from different production areas. The 50% methanol was used as extraction solvent. The Agilent ZORBAX SB C18 (150 mm × 2.1 mm, 1.8 μm) column was used; mobile phase was acetonitrile - 0.1% acetic acid with gradient elution, flow rate was 0.3 mL·min^-1, colume temperature was 30 ℃, and the injection volume was 2 μL; electrospray ionizaton source was used and detected in negative ion mode. The results showed that the established UPLC-MS/MS method could well separate the 19 components, and the methodological investigation results of 19 components were good. By means of orthogonal partial least squares discriminant analysis (OPLS-DA), 28 batches of Microctis Folium samples from different production areas can be divided into three categories, Guangdong, Guangxi and Hainan are each classified into one category, and 10 signature compounds which affecting the quality differences of different production areas were screened out. The established method is accurate, reliable, sensitive and reproducible. It can provide a basis for the establishment of the quality standard of Microctis Folium, as well as for safety and quality research.

Lipopolysaccharides (LPS) are major outer membrane components of Gram-negative bacteria. Unlike most Gram-negative bacteria, Acinetobacter baumannii can still survive and acquire polymyxin resistance after complete loss of LPS. Previous studies of LPS-deficient Acinetobacter baumannii mostly focused on LPS-deficient strains induced by polymyxin, whose background was complex and unstable. To investigate LPS loss-mediated polymyxin resistant-Acinetobacter baumannii, this study constructed a stable and clear background LPS-deficient strain by knocking out lpxC gene in Acinetobacter baumannii ATCC 19606 with CIRSPR/Cas9, and then studied the phenotypic changes of the lpxC-deficient strain including morphology, growth rate, antibiotic susceptibility, virulence, membrane permeability, and membrane potential. Animal experiments were approved by the Animal Care and Welfare Committee Institute of Medicinal Biotechnology, CAMS and PUMC (approval number: IMB-20240119D₉). The results indicated that the lpxC gene of Acinetobacter baumannii ATCC 19606 was successfully knocked out. After losing the lpxC, the strain underwent the morphological change from rod-shaped to spherical. Furthermore, it leads to reduced growth rate, enhanced membrane permeability, decreased membrane potential, lower virulence, and increased antibiotic susceptibility to β-lactams, quinolones, aminoglycosides, macrolides, glycopeptides. The lpxC deletion results in significant changes in membrane homeostasis and adaptability of Acinetobacter baumannii. Understanding the phenotypic changes of colistin-resistant Acinetobacter baumannii mediated by LPS loss is useful for exploring the resistance mechanism of Acinetobacter baumannii and developing new therapeutic strategies.

This study aims to investigate the effect of salvianolic acid B (Sal B), the active ingredient of Salvia miltiorrhiza, on H9C2 cardiomyocytes injured by oxygen and glucose deprivation/reperfusion (OGD/R) through regulating mitochondrial fission and fusion. The process of myocardial ischemia-reperfusion injury was simulated by establishing OGD/R model. The cell proliferation and cytotoxicity detection kit (cell counting kit-8, CCK-8) was used to detect cell viability; the kit method was used to detect intracellular reactive oxygen species (ROS), total glutathione (t-GSH), nitric oxide (NO) content, protein expression levels of mitochondrial fission and fusion, apoptosis-related detection by Western blot. Mitochondrial permeability transition pore (MPTP) detection kit and Hoechst 33342 fluorescence was used to observe the opening level of MPTP, and molecular docking technology was used to determine the molecular target of Sal B. The results showed that relative to control group, OGD/R injury reduced cell viability, increased the content of ROS, decreased the content of t-GSH and NO. Furthermore, OGD/R injury increased the protein expression levels of dynamin-related protein 1 (Drp1), mitofusions 2 (Mfn2), Bcl-2 associated X protein (Bax) and cysteinyl aspartate specific proteinase 3 (caspase 3), and decreased the protein expression levels of Mfn1, increased MPTP opening level. Compared with the OGD/R group, it was observed that Sal B had a protective effect at concentrations ranging from 6.25 to 100 μmol·L^-1. Sal B decreased the content of ROS, increased the content of t-GSH and NO, and Western blot showed that Sal B decreased the protein expression levels of Drp1, Mfn2, Bax and caspase 3, increased the protein expression level of Mfn1, and decreased the opening level of MPTP. In summary, Sal B may inhibit the opening of MPTP, reduce cell apoptosis and reduce OGD/R damage in H9C2 cells by regulating the balance of oxidation and anti-oxidation, mitochondrial fission and fusion, thereby providing a scientific basis for the use of Sal B in the treatment of myocardial ischemia reperfusion injury.

The outer membrane composed predominantly of lipopolysaccharide (LPS) is an essential biological barrier for most Gram-negative (G^-) bacteria. Lipopolysaccharide transport protein (Lpt) complex LptDE is responsible for the critical final stage of LPS transport and outer membrane assembly. The structure and function of LptDE are highly conserved in most G^- bacteria but absent in mammalian cells, and thus LptDE complex is regarded as an attractive antibacterial target. In recent 10 years, the deciphering of the three-dimensional structure of LptDE protein facilities the drug discovery based on such "non-enzyme" proteins. Murepavadin, a peptidomimetic compound, was reported to be the first compound able to target LptD, enlightening a new class of antibacterial molecules with novel mechanisms of action. This article is devoted to summarize the molecular characteristics, structure-function of LptDE protein complex and review the development of murepavadin and related peptidomimetic compounds, in order to provide references for relevant researches.

AIM: To establish a method for quantitation of cefepime and avibactam in M-H broth, and applicated in the in vitro dynamic PK/PD model. METHODS: The cefepime was also determined using the high-performance liquid chromatography method (HPLC), the avibactam was also determined using the liquid chromatography-mass spectrometry (LC-MS/MS), an in vitro dynamic PK/PD model was established to study the PK/PD relationship of cefepime/avibactam against carbapenem resistant Klebsiella pneumoniae (CRKP). RESULTS: The linear ranges of cefepime and avibactam were good at (0.5-20) and (0.1-25) μg/mL (r=0.999), and the lower limit concentrations were 0.5 and 0.1 μg/mL. The extraction recoveries of cefepime and avibactam in M-H broth were 88.0%-101.7% and 90.9%-95.2%, the relative standard deviation of intra-day precision and inter-day precision were less than 5.2%. The concentration-time curves were well simulated by the PK/PD model. All observed concentrations in each experiment were in the range of 20% of the targeted values. For the CRKP of MIC=8 μg/mL and MIC=16 μg/mL, the colony decreased to 2.783Log10 CFU/mL and 1.325Log10 CFU/mL at the cefepime/avibactam 2.5 g q8 h administration after 24 h. CONCLUSION: The determination method of cefepime and avibactam in broth established in this study has high sensitivity and good stability. For the CRKP with MIC≤8 μg/mL,cefepime/avibactam showed that good anti-CRKP activity under routine administration in vitro dynamic PK/PD model.

Vitamins,as important micronutrients widely involved in human physiological functions,play a significant role in parenteral nutrition therapy due to their inability to be synthesized or insufficient synthesis in the body,requiring exogenous supplementation. However,a consensus does not exist in China regarding the dosage and monitoring of vitamins in parenteral nutrition. Experts in the field are recruited by Chinese Nutrition Society for Medical Food and Nutrition Support,Chinese Society for Parenteral and Enteral Nutrition (CSPEN),Shanghai Medical Association for Parenteral and Enteral Nutrition and the Shanghai Nutrition Society to formulate a consensus paper.The current paper aims to provide standardized guidance for clinical use of vitamins in parenteral nutrition. The consensus paper is a composite of systematically reviewing pertinent literature,Chinese clinical practice and multiple sessions of debate,discussion,and composition,with reference to guidelines from European Society for Parenteral and Enteral Nutrition (ESPEN),American Society for Parenteral and Enteral Nutrition (ASPEN),Australasian Society for Parenteral and Enteral Nutrition (AuSPEN) and CSPEN.This includes 37 recommendations regarding the recommended dosage and monitoring of fat-soluble vitamins (vitamins A,D,E,K) and water-soluble vitamins (vitamin C and vitamins B1,B2,B6,B12,niacin,pantothenic acid,biotin,and folate) to serve varied adult parenteral nutrition patients.