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 analyze the combined effect of body mass index(BMI)and age with cancer occurrence among a hypertensive population in Minhang District,Shanghai.Methods Participants of this study were 212 394 hypertensive patients without cancer in Minhang District,Shanghai,registered in the electronic health information system from 2007 to 2015.Age and BMI were included as smoothing functions in the generalized additive Cox proportional risk model.The bivariate response model was constructed to visualize results using surface plots and to comprehensively analyze the association of BMI and age with the risk of cancer occurrence.Results A total of 22 141 participants developed cancer by Dec 31,2018.The association between age and the risk of cancer incidence showed an overall linear trend while the association between BMI and the risk of cancer incidence showed an overall"U"shape.BMI at about 26 kg/m2 showed the lowest risk of cancer incidence.The risk of cancer occurrence increased with increasing age in people with different BMIs.The associations between BMI and the risk of cancer incidence were different at different age groups:there was no significant association between BMI and the risk of cancer incidence in the young people(20-44 years).While in the middle-aged and older people aged over 45 years,BMI was associated with the risk of cancer incidence in a"U"shape.The lowest risk of cancer incidence was around the BMI of 26 kg/m2.Conclusion BMI among the population with hypertension should be controlled in a reasonable range,especially in the middle-aged and older population,to prevent cancer occurrence.

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.

The molecularly imprinted polymers membranes(MIPMs)were prepared for selective adsorption of lamotrigine(LTG)in plasma by surface molecular imprinting technology with polyvinylidenefluoride(PVDF)membranes as supporter,lamotrigine as template molecule,methyl methacrylate as functional monomer,ethylene glycol dimethacrylate as cross-linking agent,azodiisobutyronitrile as initiator and acetonitrile-dimethylformamide(1∶1.5,V/V)as pore-forming agent.The prepared MIPMs were characterized by scanning electron microscope,Fourier transform infrared spectroscopy,Brunaner-emmet-teller measurements,X-ray photoelectron spectroscopy,and thermogravimetric analysis.The adsorption properties of the materials were investigated by kinetic adsorption,isothermal adsorption,selective adsorption,adsorption-desorption and reusability experiments.The results showed that the imprinted layer of LTG was successfully coated on the surface of PVDF,and the materials had uniform particle size.The adsorption capacity and imprinting factor of the MIPMs towards LTG were 3.77 mg/g and 8.97,respectively.The nanomaterials showed fast mass transfer rate(30 min)and good reusability(the adsorption efficiency was 86.66%after 6 cycles),and could be used for the adsorption of LTG in plasma with low matrix interference,recoveries of 86.54%-90.48%and RSD of 1.51%-3.15%(n=5).The proposed LTG MIPMs were demonstrated to be simple and environment friendly,and had high selectivity in rapid separation and extraction of LTG in plasma.

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.

Objective To observe area of coagulation necrosis after microwave ablation(MWA)of rabbit liver showed on contrast-enhanced ultrasound(CEUS)in comparison with pathological findings.Methods Twenty-five healthy male experimental rabbits were equally randomly divided into L0,M0,H0,M7 and M14 groups.MWA was achieved with different power and time,and then CEUS and pathological examinations were performed,respectively.Four target areas of rabbit liver were ablated under 20 W for 1 min in L0 group,under 30 W for 1 min in M0 group and under 30 W for 3 min in H0 group,and the ablated areas were observed on the same day after MWA,while 2 target areas of rabbit liver were ablated under 30 W for 1 min in M7 and M14 groups,and the ablated areas were observed 7 days and 14 days after MWA,respectively.The ablated foci and ablated foci+edema band(inflammatory reaction band,IRB)showed on CEUS and pathology were compared,and their differences and changes with time going were analyzed.Results On the day of ablation,the extent of ablation foci,ablation foci+IRB as well as IRB in L0,M0 and H0 groups showed on CEUS were all larger than pathological findings under light microscopy(all P＜0.05),and the difference value of the length of the ablation foci between 2 methods increased sequentially among group L0,M0 and H0(all adjusted P＜0.05).Seven days after ablation,the area of ablation foci measured with CEUS in M 7 group was slightly larger than that measured with pathology(adjusted P=0.045),but no significant difference of the length nor the short diameter was found(both adjusted P＞0.05).Fourteen days after ablation,no significant difference of the length,the short diameter nor the area of ablation foci was detected between 2 methods in M14 group(all adjusted P＞0.05).The length,short diameter and area of ablation foci in M0 group measured with CEUS or pathology were all smaller than those in M 7 and M14 groups(all adjusted P＜0.05),while no significant difference was found between the latter 2 groups(all adjusted P＞0.05).Conclusion On the day of MWA of rabbit liver with different power and time settings,the areas of ablation foci,ablation foci+IRB and IRB showed on CEUS were larger than pathological findings.The range of ablation foci showed on CEUS 7 days after ablation was basically in line with pathology,indicating that CUES should be reexamined 7 days after ablation to evaluate the actual extent of coagulation and necrosis of ablation foci.

Objective To observe the impact of cold circulation liquid temperature on ablation focus morphology of microwave ablation(MWA)for in vitro porcine liver tissue.Methods Twenty in vitro fresh porcine liver blocks were randomly divided into ice water circulation group(group A)and normal temperature circulation group(group B),respectively.Ten target ablations in each subgroups in group A and group B,i.e.A1 and B1(50 W,1 min),A2 and B2(50 W,5 min),A3 and B3(60 W,1 min),A4 and B4(60 W,5 min),A5 and B5(70 W,1 min)as well as A6 and B6(70 W,5 min)subgroups were performed using different ablation power(50,60,70 W)and ablation time(1,5 min),respectively.Then the morphology indexes of ablation foci,including longitudinal diameter(LD),transverse diameter(TD),roundness index(RI)and volume(V)were compared between subgroups in group A and B,also among subgroups within group A and B.Results Under the same ablation power and time,LD of ablation foci in subgroups of group A were all smaller than those of group B(all P＜0.05).Significant differences of RI of ablation foci were found between A1 and B1,A2 and B2,A4 and B4,A5 and B5 as well as A6 and B6 subgroups(all P＜0.05),but not between A3 and B3 subgroups(P＞0.05).However,the main effect of cold circulation liquid temperature on ablation focus TD(F=1.125)nor V(F=3.332)was not significant(both P≥0.05).Under the same cold circulation liquid temperature,significant differences of the morphology indexes of ablation foci were detected between A1 and A2,A3 and A4 as well as A5 and A6 subgroups,also between corresponding subgroups in group B(all P＜0.05).Conclusion During MWA for in vitro porcine liver tissue under constant ablation power and time,taken ice water as the cold circulation liquid was benefit to ablation focus shaped spherically.With the extension of ablation time,the larger the ablation focus,the higher the RI.

Objective:To explore the clinical manifestations,pathological features,immunophenotype,as well as diagnosis,treatment and prognosis of patients with CD4-CD56+blastic plasmacytoid dendritic cell neoplasm(BPDCN),in order to further understand the rare disease.Methods:The clinical data,laboratory examinations and treatment regimens of two patients with CD4-CD56+BPDCN in the First Affiliated Hospital of Wannan Medical College were retrospectively analyzed.Results:The two patients were both elderly males with tumor involved in skin,bone marrow,lymph nodes,etc.Immunohistochemical results of skin lesions showed that both CD56 and CD123 were positive,while CD4,CD34,TdT,CD3,CD20,MPO and EBER were negative.Flow cytometry of bone marrow demonstrated that CD56,CD123,and CD304 were all positive,while specific immune markers of myeloid and lymphoid were negative.Two patients were initially very sensitive to acute lymphoblastic leukemia or lymphomatoid chemotherapy regimens,but prone to rapid relapse.The overall survival of both patients was 36 months and 4 months,respectively.Conclusion:CD4-CD56+BPDCN is very rare and easily misdiagnosed as other hematological tumors with poor prognosis.Acute lymphoblastic leukemia or lymphomatoid therapy should be used first to improve the poor prognosis.

Objective To propose an improved YOLOv5s-based lesion area detection method for ophthalmic ultrasound images so as to solve the problems due to high complexity,difficult deployment and low accuracy of the model during ophthalmic ultrasound imaging detection and diagnosis.Methods Firstly,an ophthalmic ultrasound image dataset was established contai-ning Lhe images of stellate vitreous degeneration,retinal detachment,vitreous hemorrhage,posterior vitreous detachment and posterior scleral staphyloma.Secondly,a YOLOv5s-MobileNetV2 model was constructed based on YOLOv5s with the original backbone feature extraction network CSPDarkNet replaced by the lightweight network MobileNet.Thirdly,the model's performance in recognizing lesion areas in ophthalmic ultrasound images was evaluated by multi-category mean average precision(mAP),number of parameters and frames per second(FPS).Finally,the intelligent detection software for ophthalmic ultrasound images was designed based on PyQt5 library.Results The YOLOv5s-MobileNetV2 model had the mAP,number of parameters and FPS being 97.73％,4.61×106 and 47 f/s respectively,which gained advantages in timeliness over YOLOv5s by decreasing the mAP by 0.22％and the number of parameters by 34.98％.The developed intelligent detection software for ophthalmic ultrasound images behaved in human-computer interaction and clinical applicability of YOLOv5s-MobileNetV2 model.Conclusion The improved YOLOv5s-based lesion area detection method for ophthalmic ultrasound images meets clinical diagnosis requirements for ophthalmic diseases by involving in lightweight models and detecting lesion areas accurately.[Chinese Medical Equipment Journal,2024,45(11):1-7]