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 explore the clinical outcome and applicability of the comb flap technique and stepwise design concept in plastic aesthetic and reconstructive surgery.Methods:The clinical data of patients who underwent plastic aesthetic and reconstructive surgery with the comb flap technique in Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from January 2018 to December 2022 were retrospectively analyzed. The application of the comb flap technique follows the concept of stepwise design, that was, preoperative and intraoperative design and adjustment were carried out step by step and in sequence, and the design was combined with the surgical procedure. Its main operations included: an incision was designed along the edge of the target area, the tissue flap was widely separated at the base of the target area. The tissue flap was cut in sequence perpendicular to the cutting edge and temporarily sutured and fixed, the edge was cut and fixed. During the operation, the tension of the incision and the local appearance could be adjusted. The incisal edge was finely sutured, and the temporary suture was finally removed. The healing of surgical incision and complications were observed after the operation, and the facial recovery and surgical effect were followed up.Results:Six patients were enrolled, including 3 males and 3 females, aged from 2 to 58 years. One patient underwent upper eyelid tightening and lower eyelid blepharoplasty through subeyebrow incision. One patient underwent middle and lower face rhytidectomy. One patient underwent thick lip thinning and right facial liposuction. One patient underwent facial congenital melanocytic nevi resection. One patient underwent eyebrow congenital melanocytic nevus resection. One patient underwent facial flap repair. All patients had primary healing of incision, and no surgery-related complications occurred. All patients were followed up for 3 to 18 months, and all patients were satisfied with the surgical effect.Conclusion:The application of comb flap technique and stepwise design concept in plastic aesthetic and reconstructive surgery can delicately adjust the alignment of the incision margin, make the tension evenly distributed, and reduce the risk of scar formation and deformity after the operation. It has a wide range of clinical applications and good applicability.

Rapid epidemiological screening for tuberculosis (TB) usually uses tuberculin pure protein derivative (PPD) skin test, which has limitations such as low specificity and high side effects. ESAT-6 and CFP-10 are secreted proteins of Mycobacterium tuberculosis, but the related genes are missing from Bacillus Calmette-Guerin (BCG). In this study, the fusion protein ESAT6-CFP10 (EC) was expressed and purified, and prepared into chitosan nanoparticles (EC-NPs), which were loaded into the microneedle patch and carried out the preliminary test of tuberculosis skin test. The drug loading capacity of MNP-EC-NPs (microneedle patch, MNP) can reach 0.03 μg per needle and 1.92 μg per patch. The shelf life of MNP-EC-NPs can reach 6 months at room temperature, and it can effectively penetrate the epidermis. Volunteer skin test results showed that MNP-EC-NPs can effectively distinguish between BCG vaccinators, and can effectively show positive reaction in the skin of tuberculosis patients without significant side effects. The experiment was approved by the Ethics Committee of Wuhan Pulmonary Hospital [2022 (2)]. In this study, a TB skin test method was established, using ESAT6-CFP10 fusion protein instead of PPD, and using soluble microneedle dosage form, which improved the specificity of TB skin test diagnosis and provided a new technical scheme for TB epidemic screening.

Objective The causes of bleeding after endoscopic duodenal papilloma resection were analyzed and discussed,and the prediction model of nomogram was established.Methods A total of 233 patients who underwent endoscopic duodenal papilloma resection in our hospital from January 2018 to December 2023 were retrospectively analyzed,and they were divided into bleeding group(n=31 cases)and non-bleeding group(n=202 cases)according to whether postoperative bleeding occurred.The clinical data of the two groups were compared,the independent risk factors for postoperative bleeding were analyzed by multi-factor logistic regression,the risk nomogram prediction model was constructed,and the Bootstrap method was used for 1000 repeated samples to carry out internal verification.Results Anticoagulant drugs(OR=9.063,95％CI:2.132-38.525),lesion diameter ≥2 cm(OR=2.802,95％CI:1.073-7.321),intraoperative fragment resection(OR=27.653,95％CI:3.055～619.174)and pancreatic complications(OR=6.859,95％CI:1.930～24.377)were independent risk factors for postoperative bleeding after endoscopic duodenal papilloma resection(P＜0.05).A risk prediction nomogram model was constructed according to the Logistic regression analysis results.The samples were repeatedly sampled 1000 times through Bootstrap method for internal verification.The area under the ROC curve was 0.850,and the 95％CI was 0.780-0.913,indicating good differentiation ability of the model.Calibration curve analysis indicated that the prediction probability of postoperative bleeding predicted by the nomogram prediction model was in good agreement with the actual probability of postoperative bleeding,and Hosmer-Lemeshow showed good goodness of fit(x2=3.304 9,P=0.913 8).Conclusion Taking anticoagulant drugs,lesion diameter ≥2 cm,intraoperative segmentary resection,and postoperative combination of pancreas were independent risk factors for bleeding after endoscopic duodenal papilloma resection.A nomogram prediction model was established to help clinical assessment of postoperative bleeding risk in patients and improve decision-making basis for early prevention.

Objective To explore the postmortem diffusion rule of Aconitum alkaloids and their metabo-lites in poisoned rabbits,and to provide a reference for identifying the antemortem poisoning or post-mortem poisoning of Aconitum alkaloids.Methods Twenty-four rabbits were sacrificed by tracheal clamps.After 1 hour,the rabbits were administered with aconitine LD50 in decocting aconite root powder by intragastric administration.Then,they were placed supine and stored at 25℃.The biological samples from 3 randomly selected rabbits were collected including heart blood,peripheral blood,urine,heart,liver,spleen,lung and kidney tissues at 0 h,4 h,8 h,12 h,24 h,48 h,72 h and 96 h after intragastric administration,respectively.Aconitum alkaloids and their metabolites in the biological samples were ana-lyzed by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).Results At 4 h after intragastric administration,Aconitum alkaloids and their metabolites could be detected in heart blood,peripheral blood and major organs,and the contents of them changed dynamically with the preservation time.The contents of Aconitum alkaloids and their metabolites were higher in the spleen,liver and lung,especially in the spleen which was closer to the stomach.The average mass fraction of benzoylmesaconine metabolized in rabbit spleen was the highest at 48 h after intragastric administration.In contrast,the contents of Aconitum alkaloids and their metabolites in kidney were all lower.Aconi-tum alkaloids and their metabolites were not detected in urine.Conclusion Aconitum alkaloids and their metabolites have postmortem diffusion in poisoned rabbits,diffusing from high-content organs(stomach)to other major organs and tissues as well as the heart blood.The main mechanism is the dispersion along the concentration gradient,while urine is not affected by postmortem diffusion,which can be used as the basis for the identification of antemortem and postmortem Aconitum alkaloids poisoning.

Objective To compare the fidelity of chronic obstructive pulmonary disease(COPD)models established using two methods:exposure to cigarette smoke(CS)and exposure to motor vehicle exhaust(MVE)in rats.Methods Twenty-four male SD rats were randomly divided into control,CS-exposed(CS),and MVE-exposed(MVE)groups,with 8 rats per group.Rats in CS and MVE groups were exposed to CS or MVE,respectively,to induce COPD models.After COPD model established,lung function of each group was assessed.Bronchoalveolar lavage fluid(BALF)was collected to measure inflammatory cell counts,levels of inflammatory cytokines interleukin-6(IL-6)and tumor necrosis factor(TNF)-α,and expression levels of mucin 5AC(MUC5AC).Lung tissue sections were stained with hematoxylin and eosin(HE)to observe pulmonary tissue and airway pathological changes.Periodic acid-Schiff(PAS)staining was used to detect goblet cell hyperplasia in airways.Results Compared with control group,rats in CS and MVE groups showed significantly increased inspiratory resistance(RI),total lung capacity(TLC),and lung static compliance(Cchord)(P<0.05),while expiratory flow parameters FEV50/FVC were significantly decreased(P<0.05).Compared with MVE group,rats in CS group had significantly higher RI,TLC,and Cchord(P<0.05),and lower FEV50/FVC(P<0.05).HE staining of lung tissues showed that mean linear intercept(MLI)was significantly higher in both CS and MVE groups compared with control group(P<0.05),with CS group having higher MLI than MVE group(P<0.05).BALF analysis revealed that white blood cells,neutrophils,macrophages,lymphocytes,IL-6,and TNF-α levels were significantly higher in both CS and MVE groups compared with control group(P<0.05),and inflammatory cell counts,IL-6,and TNF-α levels were higher in CS group compared with MVE group(P<0.05).PAS staining of lung tissues indicated that goblet cells in large airways were significantly increased in both CS and MVE groups compared with control group(P<0.05),with CS group showing higher goblet cell counts than MVE group(P<0.05).Expression levels of MUC5AC in BALF were significantly higher in both CS and MVE groups compared with control group(P<0.05),with CS group having significantly higher MUC5AC levels than MVE group(P<0.05).Conclusions Exposure to CS or MVE can establish a rat model of COPD,with CS exposure better mimicking characteristics of acute exacerbation of COPD compared to MVE exposure.

Objective To investigate the clinical characteristics and prognosis of pneumococcal meningitis(PM),and drug sensitivity of Streptococcus pneumoniae(SP)isolates in Chinese children.Methods A retrospective analysis was conducted on clinical information,laboratory data,and microbiological data of 160 hospitalized children under 15 years old with PM from January 2019 to December 2020 in 33 tertiary hospitals across the country.Results Among the 160 children with PM,there were 103 males and 57 females.The age ranged from 15 days to 15 years,with 109 cases(68.1% )aged 3 months to under 3 years.SP strains were isolated from 95 cases(59.4% )in cerebrospinal fluid cultures and from 57 cases(35.6% )in blood cultures.The positive rates of SP detection by cerebrospinal fluid metagenomic next-generation sequencing and cerebrospinal fluid SP antigen testing were 40% (35/87)and 27% (21/78),respectively.Fifty-five cases(34.4% )had one or more risk factors for purulent meningitis,113 cases(70.6% )had one or more extra-cranial infectious foci,and 18 cases(11.3% )had underlying diseases.The most common clinical symptoms were fever(147 cases,91.9% ),followed by lethargy(98 cases,61.3% )and vomiting(61 cases,38.1% ).Sixty-nine cases(43.1% )experienced intracranial complications during hospitalization,with subdural effusion and/or empyema being the most common complication[43 cases(26.9% )],followed by hydrocephalus in 24 cases(15.0% ),brain abscess in 23 cases(14.4% ),and cerebral hemorrhage in 8 cases(5.0% ).Subdural effusion and/or empyema and hydrocephalus mainly occurred in children under 1 year old,with rates of 91% (39/43)and 83% (20/24),respectively.SP strains exhibited complete sensitivity to vancomycin(100% ,75/75),linezolid(100% ,56/56),and meropenem(100% ,6/6).High sensitivity rates were also observed for levofloxacin(81% ,22/27),moxifloxacin(82% ,14/17),rifampicin(96% ,25/26),and chloramphenicol(91% ,21/23).However,low sensitivity rates were found for penicillin(16% ,11/68)and clindamycin(6% ,1/17),and SP strains were completely resistant to erythromycin(100% ,31/31).The rates of discharge with cure and improvement were 22.5% (36/160)and 66.2% (106/160),respectively,while 18 cases(11.3% )had adverse outcomes.Conclusions Pediatric PM is more common in children aged 3 months to under 3 years.Intracranial complications are more frequently observed in children under 1 year old.Fever is the most common clinical manifestation of PM,and subdural effusion/emphysema and hydrocephalus are the most frequent complications.Non-culture detection methods for cerebrospinal fluid can improve pathogen detection rates.Adverse outcomes can be noted in more than 10% of PM cases.SP strains are high sensitivity to vancomycin,linezolid,meropenem,levofloxacin,moxifloxacin,rifampicin,and chloramphenicol.[Chinese Journal of Contemporary Pediatrics,2024,26(2):131-138]

Objective To monitor the susceptibility of clinical isolates to antimicrobial agents in tertiary hospitals in major regions of China in 2022.Methods Clinical isolates from 58 hospitals in China were tested for antimicrobial susceptibility using a unified protocol based on disc diffusion method or automated testing systems.Results were interpreted using the 2022 Clinical &Laboratory Standards Institute(CLSI)breakpoints.Results A total of 318 013 clinical isolates were collected from January 1,2022 to December 31,2022,of which 29.5％were gram-positive and 70.5％were gram-negative.The prevalence of methicillin-resistant strains in Staphylococcus aureus,Staphylococcus epidermidis and other coagulase-negative Staphylococcus species(excluding Staphylococcus pseudintermedius and Staphylococcus schleiferi)was 28.3％,76.7％and 77.9％,respectively.Overall,94.0％of MRSA strains were susceptible to trimethoprim-sulfamethoxazole and 90.8％of MRSE strains were susceptible to rifampicin.No vancomycin-resistant strains were found.Enterococcus faecalis showed significantly lower resistance rates to most antimicrobial agents tested than Enterococcus faecium.A few vancomycin-resistant strains were identified in both E.faecalis and E.faecium.The prevalence of penicillin-susceptible Streptococcus pneumoniae was 94.2％in the isolates from children and 95.7％in the isolates from adults.The resistance rate to carbapenems was lower than 13.1％in most Enterobacterales species except for Klebsiella,21.7％-23.1％of which were resistant to carbapenems.Most Enterobacterales isolates were highly susceptible to tigecycline,colistin and polymyxin B,with resistance rates ranging from 0.1％to 13.3％.The prevalence of meropenem-resistant strains decreased from 23.5％in 2019 to 18.0％in 2022 in Pseudomonas aeruginosa,and decreased from 79.0％in 2019 to 72.5％in 2022 in Acinetobacter baumannii.Conclusions The resistance of clinical isolates to the commonly used antimicrobial agents is still increasing in tertiary hospitals.However,the prevalence of important carbapenem-resistant organisms such as carbapenem-resistant K.pneumoniae,P.aeruginosa,and A.baumannii showed a downward trend in recent years.This finding suggests that the strategy of combining antimicrobial resistance surveillance with multidisciplinary concerted action works well in curbing the spread of resistant bacteria.

Aim To explore the feasibility of the cloud exposure system for in vitro exposure experiments on inhalation toxicology.Methods Calu-3 cells cultured at the air-liquid interface(ALI)were exposed to three concentrations of lipopolysaccha-ride(LPS):high,medium,and low(800,400,200 mg·L-1)by the cloud exposure system,and phosphate buffer solu-tion(PBS)was used as a negative control group for one expo-sure,while the high concentration of LPS was used to expose Calu-3 cells for five times.Calu-3 cells were exposed to phos-phate buffer solution(PBS)once as negative control group and to high concentration of LPS solution for five times,and the ac-tivity of Calu-3 cells,the release of lactate dehydrogenase(LDH),TEER,mucin MUC5AC,and the expression of inflam-matory factors IL-6,IL-8 and TNF-α were detected 3 h and 24 h after the end of the exposure,respectively.Results Compared with the PBS-negative control group,after exposure to the Calu-3 cell model at the air-liquid interface with three concentrations of LPS,high,medium,and low,there were no significant changes in the activity and LDH release,but the cellular electrical resist-ance value was reduced,and the barrier function of the cells was impaired;with the increase of the exposure concentration,the LPS promoted the expression of the cellular mucin MUC5AC,which led to a decrease in the expression of cellular IL-6,IL-8,and a decrease in the expression of TNF-α.Expression of IL-6 and IL-8 decreased and TNF-α expression increased;as the fre-quency of exposure increased,LPS inhibited the expression of mucin and increased the expression of IL-6;an increase in the frequency of exposure along with a prolongation of post-exposure assay time resulted in an increase in the expression of cellular IL-8 and TNF-a.Conclusions The ALI cloud exposure ap-proach can effectively reflect the cellular response to positive subjects,and this in vitro exposure can be used in subsequent exposure experiments to evaluate the inhalation toxicity of com-pounds.

Objective:To explore the clinical outcome and applicability of the comb flap technique and stepwise design concept in plastic aesthetic and reconstructive surgery.Methods:The clinical data of patients who underwent plastic aesthetic and reconstructive surgery with the comb flap technique in Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from January 2018 to December 2022 were retrospectively analyzed. The application of the comb flap technique follows the concept of stepwise design, that was, preoperative and intraoperative design and adjustment were carried out step by step and in sequence, and the design was combined with the surgical procedure. Its main operations included: an incision was designed along the edge of the target area, the tissue flap was widely separated at the base of the target area. The tissue flap was cut in sequence perpendicular to the cutting edge and temporarily sutured and fixed, the edge was cut and fixed. During the operation, the tension of the incision and the local appearance could be adjusted. The incisal edge was finely sutured, and the temporary suture was finally removed. The healing of surgical incision and complications were observed after the operation, and the facial recovery and surgical effect were followed up.Results:Six patients were enrolled, including 3 males and 3 females, aged from 2 to 58 years. One patient underwent upper eyelid tightening and lower eyelid blepharoplasty through subeyebrow incision. One patient underwent middle and lower face rhytidectomy. One patient underwent thick lip thinning and right facial liposuction. One patient underwent facial congenital melanocytic nevi resection. One patient underwent eyebrow congenital melanocytic nevus resection. One patient underwent facial flap repair. All patients had primary healing of incision, and no surgery-related complications occurred. All patients were followed up for 3 to 18 months, and all patients were satisfied with the surgical effect.Conclusion:The application of comb flap technique and stepwise design concept in plastic aesthetic and reconstructive surgery can delicately adjust the alignment of the incision margin, make the tension evenly distributed, and reduce the risk of scar formation and deformity after the operation. It has a wide range of clinical applications and good applicability.