Efficacy and Safety of Lianhua Qingke Tablets in the Treatment of Long Coronavirus Disease (COVID) Cough: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Clinical Study

Lianhua Qingke tablets,a patented traditional Chinese medicine that has validated clinical efficacy for treating cough caused by severe acute respiratory syndrome coronavirus 2 infection,lack rigorous evidence-based research evaluating their effect on long coronavirus disease(COVID)cough.A randomized,double-blind,placebo-controlled,multicenter clinical study was conducted among patients with long COVID cough from 19 hospitals and 23 community health centers in China.Patients were randomized 1:1 to receive either Lianhua Qingke tablets or placebo orally for 14 days(four tablets,1.84 g,three times a day).The primary endpoint indicator was the disappearance of cough,with the remission of cough also considered.Among 482 randomized patients,480(full analysis set 480;per-protocol set 470;safety set 480)were included in the primary analysis.According to the full analysis,the time until cough disappearance was significantly shorter in the trial group than in the control group,with a significant increase in the 14-day cough disappearance rate.Accordingly,the time to cough remission was significantly shorter in the trial group than in the control group.The change in the total symptom score was significantly greater in the trial group than in the control group on days 7 and 14,consistent with the results indicated by the visual analog scale(VAS)and cough evaluation test(CET)scores.No serious adverse events were recorded during the study.Lianhua Qingke tablets significantly improved the clinical symptoms of patients with long COVID cough.

A New Flexible Multibody Dynamics Analysis Methodology of Deployable Structures with Scissor-Like Elements

There are vast constraint equations in conventional dynamics analysis of deployable structures,which lead to differential-algebraic equations(DAEs)solved hard.To reduce the difficulty of solving and the amount of equations,a new flexible multibody dynamics analysis methodology of deployable structures with scissor-like elements(SLEs)is presented.Firstly,a precise model of a flexible bar of SLE is established by the higher order shear deformable beam element based on the absolute nodal coordinate formulation(ANCF),and the master/slave freedom method is used to obtain the dynamics equations of SLEs without constraint equations.Secondly,according to features of deployable structures,the specification matrix method(SMM)is proposed to eliminate the constraint equations among SLEs in the frame of ANCF.With this method,the inner and the boundary nodal coordinates of element characteristic matrices can be separated simply and efficiently,especially on condition that there are vast nodal coordinates.So the element characteristic matrices can be added end to end circularly.Thus,the dynamic model of deployable structure reduces dimension and can be assembled without any constraint equation.Next,a new iteration procedure for the generalized-a algorithm is presented to solve the ordinary differential equations(ODEs)of deployable structure.Finally,the proposed methodology is used to analyze the flexible multi-body dynamics of a planar linear array deployable structure based on three scissor-like elements.The simulation results show that flexibility has a significant influence on the deployment motion of the deployable structure.The proposed methodology indeed reduce the difficulty of solving and the amount of equations by eliminating redundant degrees of freedom and the constraint equations in scissor-like elements and among scissor-like elements.

Genome-wide association analysis identified molecular markers associated with important tea flavor-related metabolites

The characteristic secondary metabolites in tea(theanine,caffeine,and catechins)are important factors contributing to unique tea flavors.However,there has been relatively little research on molecular markers related to these metabolites.Thus,we conducted a genome-wide association analysis of the levels of these tea flavor-related metabolites in three seasons.The theanine,caffeine,and catechin levels in Population 1 comprising 191 tea plant germplasms were examined,which revealed that their heritability exceeded 0.5 in the analyzed seasons,with the following rank order(highest to lowest heritabilities):(+)-catechin>(−)-gallocatechin gallate>caffeine=(−)-epicatechin>(−)-epigallocatechin-3-gallate>theanine>(−)-epigallocatechin>(−)-epicatechin-3-gallate>catechin gallate>(+)-gallocatechin.The SNPs detected by amplified-fragment SNP and methylation sequencing divided Population 1 into three groups and seven subgroups.An association analysis yielded 307 SNP markers related to theanine,caffeine,and catechins that were common to all three seasons.Some of the markers were pleiotropic.The functional annotation of 180 key genes at the SNP loci revealed that FLS,UGT,MYB,and WD40 domain-containing proteins,as well as ATP-binding cassette transporters,may be important for catechin synthesis.KEGG and GO analyses indicated that these genes are associated with metabolic pathways and secondary metabolite biosynthesis.Moreover,in Population 2(98 tea plant germplasm resources),30 candidate SNPs were verified,including 17 SNPs that were significantly or extremely significantly associated with specific metabolite levels.These results will provide a foundation for future research on important flavor-related metabolites and may help accelerate the breeding of new tea varieties.

Safety of hepatitis B virus core antibody-positive grafts in liver transplantation: A single-center experience in China

BACKGROUND Given the shortage of suitable liver grafts for liver transplantation, proper use of hepatitis B core antibody-positive livers might be a possible way to enlarge the donor pool and to save patients with end-stage liver diseases. However, the safety of hepatitis B virus core antibody positive(HBcAb+) donors has been controversial. Initial studies were mainly conducted overseas with relatively small numbers of HBcAb+ liver recipients, and there are few relevant reports in the population of China's Mainland. We hypothesized that the safety of HBcAb+ liver grafts is not suboptimal.AIM To evaluate the safety of using hepatitis B virus(HBV) core antibody-positive donors for liver transplantation in Chinese patients.METHODS We conducted a retrospective study enrolling 1071 patients who underwent liver transplantation consecutively from 2005 to 2016 at West China Hospital Liver Transplantation Center. Given the imbalance in several baseline variables, propensity score matching was used, and the outcomes of all recipients were reviewed in this study.RESULTS In the whole population, 230 patients received HBcAb+ and 841 patients received HBcAb negative(HBcAb-) liver grafts. The 1-, 3-and 5-year survival rates in patients and grafts between the two groups were similar(patient survival: 85.8% vs 87.2%, 77.4% vs 81.1%, 72.4% vs 76.7%, log-rank test, P = 0.16; graft survival: 83.2% vs 83.6%, 73.8% vs 75.9%, 70.8% vs 74.4%, log-rank test, P = 0.19). After propensity score matching, 210 pairs of patients were generated. The corresponding 1-, 3-and 5-year patient and graft survival rates showed no significant differences. Further studies illustrated that the post-transplant major complication rates and liver function recovery after surgery were also similar. In addition, multivariate regression analysis in the original cohort and propensity score-matched Cox analysis demonstrated that receiving HBcA b+ liver grafts was not a significant risk factor for long-term survival. These findings were consistent in both HBV surface antigen-positive(HBsAg+) and HBsA g negative(HBsAg-) patients.Newly diagnosed HBV infection had a relatively higher incidence in HBsAg-patients with HBcAb+ liver grafts(13.23%), in which HBV naive recipients suffered most(31.82%), although this difference did not affect patient and graft survival(P = 0.50 and P = 0.49, respectively). Recipients with a high HBV surface antibody(anti-HBs) titer(more than 100 IU/L) before transplantation and antiviral prophylaxis with nucleos(t)ide antiviral agents post-operation, such as nucleos(t)ide antiviral agents, had lower de novo HBV infection risks. CONCLUSION HBcA b+ liver grafts do not affect the long-term outcome of the recipients. Combined with proper postoperative antiviral prophylaxis, utilization of HBcAb+ grafts is rational and feasible.

The origin of the extraordinary stability of mercury catalysts on the carbon support: the synergy effects between oxygen groups and defects revealed from a combined experimental and DFT study

Thermal stability of HgCl2 has a pivotal importance for the hydrochlorination reaction as the loss of mercuric compounds is toxic and detrimental to environment.Here we report a low-mercury catalyst which has durability over 10000 h for acetylene hydrochlorination under the industrial condition.The stability of the catalyst is carefully analyzed from a combined experimental and density functional theory study.The analysis shows that the extraordinary stability of mercury catalyst is resulted from the synergy effects between surface oxygen groups and defective edge sites.The binding energy of HgCl2 is increased to be higher than 130 kJ/mol when adsorption is at the edge site with a nearby oxygen group.Therefore,the present study revealed that the thermal stability problem of mercury-based catalyst can be solved by simply adjusting the surface chemistry of activated carbon.Furthermore,the reported catalyst has already been successfully applied in the commercialized production of vinyl chloride.

Treatment of the acute thromboembolic event during endovascular embolization of intracranial aneurysm

Objective:The study aimed to discuss the treatment of acute thromboembolic event(TE)during endovascular embolization of intracranial aneurysms.Methods:Between April 2013 and April 2019,158 patients with 167 intracranial aneurysms were treated with endovascular embolization in our hospital,in which 9 cases of acute TEs occurred during the embolization procedures.The clinical data,radiological findings and treatments of the 9 patients were reviewed and analyzed.Results:The TEs occurred at the aneurysmal neck in 3 patients,at distal part of the parent artery in 3,in the stent in 2,and at the proximal part of the parent artery in 1.Intra-arterial(IA)infusion of tirofiban were performed in 6 patients,mechanical thromboectomy(MT)with a stent in 2 patients,and combined use of the two methods in 1 patients.According to the modified Thrombolysis In Cerebral Infarction(mTICI)score,7 patients had recanalization of 2b/3a,1 patients had recanalization of 1,and 1 patients had recanalization of 0.At discharge,the mRS score was 0 in 3 patients,1 in 3 patients,and 2,3,4 in 1 patient each.6 months after the endovascular treatment,the mRS score was 0 in 5 patients,1 in 2 patients,and 3 in 1 patient.Conclusions:IA tirofiban and MT are effective remedies for the acute TE during endovascular embolization of intracranial aneurysm,reasonable selection of which may improve the prognosis of patients.

Mechanism underlying carbon tetrachloride-inhibited protein synthesis in liver

AIM: To study the mechanism underlying carbon tetrachloride (CCl4)-induced alterations of protein synthesis in liver. METHODS: Male Sprague-Dawley rats were given CCl4 (1 mL/100 g body weight) and 3H-leucine incorporation. Malondialdehyde (MDA) level in the liver, in vitro response of hepatocyte nuclei nucleotide triphosphatase (NTPase) to free radicals, and nuclear export of total mRNA with 3'-poly A+ were measured respectively. Survival response of HepG2 cells to CCl4 treatment was assessed by methyl thiazolyl tetrazolium. Km and Vmax values of nuclear envelope NTPase activity in liver of rats treated with CCl4 were assayed by a double-reciprocal plot. RESULTS: The protein synthesis was inhibited while the MDA level was signif icantly increased in liver of rats treated with CCl4. In addition, CCl4 decreased the NTPase binding capacity of nuclear envelope (Km value) in cultured HepG2 cells. Moreover, in vitro ferrous radicals from Fenton's system suppressed the NTPase activity of liver nuclear envelope in a dose-dependent manner. Down-regulation of the nuclear envelope NTPase activity indicated a lower energy provision for nucleocytoplasmic transport of mRNA molecules, an evidence in CCl4-treated HepG2 cells correspondingly supported by the nuclear sequestration of poly (A)+ mRNA molecules in morphological hybridization research. CONCLUSION: Inhibition of mRNA transport, suggestive of decreased NTPase activity of the nuclear envelope, may be involved in carbon tetrachloride-inhibited protein synthesis in liver.

Cost-effectiveness analysis of transcatheter arterial chemoembolization with or without sorafenib for the treatment of unresectable hepatocellular carcinoma

BACKGROUND: Transcatheter arterial chemoembolization(TACE) and TACE in combination with sorafenib(TACEsorafenib) have shown a significant survival benefit for the treatment of unresectable hepatocellular carcinoma(HCC). Adopting either as a first-line therapy carries major cost and resource implications. The objective of this study was to estimate the relative cost-effectiveness of TACE against TACE-sorafenib for unresectable HCC using a decision analytic model.METHODS: A Markov cohort model was developed to compare TACE and TACE-sorafenib. Transition probabilities and utilities were obtained from systematic literature reviews, and costs were obtained from West China Hospital, Sichuan University, China. Survival benefits were reported in quality-adjusted life-years(QALYs). The incremental cost-effectiveness ratio(ICER) was calculated. Sensitive analysis was performed by varying potentially modifiable parameters of the model.RESULTS: The base-case analysis showed that TACE cost $26 951 and yielded survival of 0.71 QALYs, and TACE-sorafenib cost $44 542 and yielded survival of 1.02 QALYs in the entire treatment. The ICER of TACE-sorafenib versus TACE was $56 745 per QALY gained, which was above threshold for cost-effectiveness in China. Sensitivity analysis revealed that the major driver of ICER was the cost post TACE-sorafenib therapy with stable state.CONCLUSION: TACE is a more cost-effective strategy than TACE-sorafenib for the treatment of unresectable HCC.

Hierarchical Self-assembly of Well-Defined Louver-Like P-Doped Carbon Nitride Nanowire Arrays with Highly Effcient Hydrogen Evolution

Self-assembled nanostructure arrays integrating the advantages of the intrinsic characters of nanostructure as well as the array stability are appealing in advanced materials.However,the precise bottom-up synthesis of nanostructure arrays without templates or substrates is quite challenging because of the general occurrence of homogeneous nucleation and the difficult manipulation of noncovalent interactions.Herein,we first report the precisely manipulated synthesis of well-defined louver-like P-doped carbon nitride nanowire arrays(L-PCN)via a supramolecular self-assembly method by regulating the noncovalent interactions through hydrogen bond.With this strategy,CN nanowires align in the outer frame with the separation and spatial location achieving ultrastability and outstanding photoelectricity properties.Significantly,this self-assembly L-PCN exhibits a superior visible light-driven hydrogen evolution activity of 1872.9μmol h^−1 g^−1,rendering a^25.6-fold enhancement compared to bulk CN,and high photostability.Moreover,an apparent quantum efficiency of 6.93%is achieved for hydrogen evolution at 420±15 nm.The experimental results and first-principles calculations demonstrate that the remarkable enhancement of photocatalytic activity of L-PCN can be attributed to the synergetic effect of structural topology and dopant.These findings suggest that we are able to design particular hierarchical nanostructures with desirable performance using hydrogen-bond engineering.

A cloud optical and microphysical property product for the advanced geosynchronous radiation imager onboard China's Fengyun-4 satellites: The first version

风云四号作为中国新一代静止气象卫星,提供了高时空分辨率的监测产品。本文介绍风云四号搭载的先进地球同步轨道辐射成像仪AGRI的云光学和微物理特性产品.该产品包含了基于双光谱通道反演的云光学厚度和云粒子有效半径产品,以及基于机器学习的云识别和云相态产品。与时空匹配的主动卫星观测结果对比显示,该产品的云识别和云相态的准确率分别在95%和85%;该产品提供的云光学厚度和云有效粒径与经典的MODIS产品的相关系数达到0.76和0.63.团队将持续优化和更新该云光学和微物理特性定量产品,服务风云四号卫星定量应用。

Expression of p53, p21^(CIP1/WAF1) and eIF4E in the adjacent tissues of oral squamous cell carcinoma:establishing the molecular boundary and a cancer progression model

The present study evaluated the expression of key molecules and the status of DNA in both oral squamous cell carcinoma（OSCC） and adjacent tissues to establish a molecular surgical boundary and provide a cancer progression model. Biopsy samples from 50 OSCC patients were divided into T（cancer）, P1（0–0.5 cm）, P2（0.5–1 cm）, P3（1–1.5 cm） and P4（1.5–2 cm） groups based on the distances from the visible boundary of the primary focus. Twenty samples of normal mucosa were used as controls. We used immunohistochemical staining and flow cytometry to evaluate p53, p21CIP1/WAF1, e IF4 E and Ki-67 expression and to determine DNA status, respectively. Sub-mucosal invasion was present in the P1 and P2 groups as determined by haematoxylin and eosin staining.Mutant p53 expression decreased gradually from cancerous to normal mucosae, whereas p21CIP1/WAF1 expression displayed an opposite trend. e IF4 E expression decreased from cancerous to normal mucosae. Ki-67 expression, the heteroploidy ratio, S-phase fraction and proliferative index decreased gradually with the distance from the tumour centre. Based on these results, we suggest that the resection boundary in OSCC surgery should be beyond 2 cm from the tumour. Additionally, the adjacent tissues of the primary focus could be used as a model for assessing cancer progression.

Transcriptome and metabolome analysis reveal that oral secretions from Helicoverpa armigera and Spodoptera litura influence wound-induced host response in cotton

Cotton(Gossypium hirsutum)is an important fiber crop worldwide.Insect attack causes cotton yield and quality losses.However,little is known about the mechanism of cotton response to insect attack.We simulated insect feeding by applying insect oral secretions(OS)to wounds,and combined transcriptome and metabolome analysis to investigate how OS from two major pest species(Helicoverpa armigera and Spodoptera litura)affect cotton defense responses.We found that respectively 12,668 and 13,379 genes were differentially expressed in comparison with wounding alone.On addition of OS,the jasmonic acid signaling pathway was rapidly and strongly induced,whereas genes involved in salicylic acid biosynthesis were downregulated.On constructing a coexpression gene network,we identified a hub gene encoding a leucine-rich repeat receptor kinase that may play an important role in early signal recognition and transduction.OS from the two insect species altered the abundance of flavonoid-related compounds in different patterns.Gossypol remained in lower concentration after OS application than after wounding alone,suggesting a suppressive effect of OS on cotton defense response.This study illustrated transcriptional and metabolic changes of cotton in responding to OS from two chewing insect species,identified potential key response genes,and revealed evidence for OS inhibition of wounding-induced cotton defense response.

Knockdown of PGC1α suppresses dysplastic oral keratinocytes proliferation through reprogramming energy metabolism

Oral potentially malignant disorders(OPMDs)are precursors of oral squamous cell carcinoma(OSCC).Deregulated cellular energy metabolism is a critical hallmark of cancer cells.Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha(PGC1α)plays vital role in mitochondrial energy metabolism.However,the molecular mechanism of PGC1αon OPMDs progression is less unclear.Therefore,we investigated the effects of knockdown PGC1αon human dysplastic oral keratinocytes(DOKs)comprehensively,including cell proliferation,cell cycle,apoptosis,xenograft tumor,mitochondrial DNA(mtDNA),mitochondrial electron transport chain complexes(ETC),reactive oxygen species(ROS),oxygen consumption rate(OCR),extracellular acidification rate(ECAR),and glucose uptake.We found that knockdown PGC1αsignificantly inhibited the proliferation of DOKs in vitro and tumor growth in vivo,induced S-phase arrest,and suppressed PI3K/Akt signaling pathway without affecting cell apoptosis.Mechanistically,downregulated of PGC1αdecreased mtDNA,ETC,and OCR,while enhancing ROS,glucose uptake,ECAR,and glycolysis by regulating lactate dehydrogenase A(LDHA).Moreover,SR18292(an inhibitor of PGC1α)induced oxidative phosphorylation dysfunction of DOKs and declined DOK xenograft tumor progression.Thus,our work suggests that PGC1αplays a crucial role in cell proliferation by reprograming energy metabolism and interfering with energy metabolism,acting as a potential therapeutic target for OPMDs.

Transformation of myocardial energy metabolism pattern during myocardial remodeling caused by volume overload

Objective To elucidate the transformation of energy metabolism patterns in the process of myocardial remodeling induced by volumeoverload and to explore a novel intervention target for the prevention,delay or even reversal of structural heart dysfunction.Methods Thirty C57/BL6 mice,20-30 g,half male and half female,were randomly divided into model group(n=15)and sham operation group(n=15).Each group was divided into subacute phase(2 weeks after surgery,n=5),cardiac functional compensation phase(5 weeks after surgery,n=5)and decompensation phase(15 weeks after surgery,n=5).

A simultaneous occurrence of pulmonary embolism and cerebral infarction following Micra^(TM)leadless pacemaker implantation

Since the successful implantation of the first cardiac pacemaker(PM)in 1958,PM has been widely used in clinical practice.With the advancement of interventional technology,PMs have become smaller and more effective.Despite continuous improvements,traditional PMs remain associated with a proportional risk of immediate-and short-term complications(9%–12%),[1]which are mainly related to electrodes or pockets.Short-term complications include pneumothorax,cardiac tamponade.

Effect of Ganduqing Granule on metabolic disorder and liver dysfunction in patients with chronic hepatitis B

Objective:This study investigated the potential mechanisms of Ganduqing Granule(GDQG)in improving the liver function in patients with chronic hepatitis B(CHB).Methods:Plasma samples from 30 healthy volunteers and 30 patients with CHB before and after the treatment with GDQG were measured for the alterations in liver function and metabolites,using the method of ultra-high-performance liquid chromatography coupled with time-of-flight mass spectrometry.Results:Patients with CHB developed severe liver dysfunction,which was associated with the higher plasma levels of 8 metabolites when compared with those of the normal control(P<0.05).Interestingly,after treatment with GDQG for 3 weeks,the 8 metabolites were significantly reduced(P<0.05).Among them,glycochenodeoxycholate-3-sulfate,glycochenodeoxycholic acid-3-glucuronide,taurochenodeoxycholic acid,and 7b-hydroxy-3-oxo-5b-cholanoic acid were associated with the metabolism of bile acids,while 3b,16a-dihydroxyandrostenone sulfate,lysophosphatidylcholine(C18:3),and lysophosphatidylethanolamine(C22:1)were related to the metabolism of lipids.2,6-Diamino-4-hydroxy-5-N-methylformamidopyrimidine was related to hepatic oxidative stress.Meanwhile,liver damage in patients was greatly reduced.Conclusion:Treatment with GDQG has improved liver function of patients with CHB through the possible mechanism of adjusting the metabolic disorders related to lipids,bile acids,and oxidative stress.

Expression and subcellular localization of a novel gene <i>Bm-X</i>of the silkworm, <i>Bombyx mori</i>

According to the large-scale sequencing of cDNA library from silkworm pupae, the cDNA of a novel gene with blank research background was identified and temporarily named Bm-X. The length of this cDNA is 778 bp. We obtained its ORF for further study by bioinformatics analysis. It is 444 bp and encodes 147 amino acid residues, with a predicted molecular weight (MW) of 16.4 kD and an isoelectric point (pI) of 3.69. In this study, we successfully constructed a recombinant plasmid pET-28a(+)-Bm-X and expressed it in Escherichia coli. We used the fusion protein rBm-X which purified by Niaffinity chromatography to produce polyclonal antibodies against Bm-X for Western blot analysis. The analysis revealed that Bm-X was expressed in the larval midgut, the epidermis and the silk gland. In addition, the subcellular localization analysis of silkworm ovary epithelial cells (BmN cells) showed that Bm-X protein was located both in cytoplasm and nucleus, and the signal was stronger in cytoplasm than in nucleus. Our findings indicate that Bm-X gene is a novel species-specificity gene and its expression product can be detected in tissues of the fifth silkworm instar larvae and BmN cells.

Study on Flow Unit of Heavy Oil Bottom Water Reservoir with Over-Limited Thickness in Offshore Oilfield

The upper Ming section of L oilfield is a typical offshore heavy oil bottom-water reservoir with thick fluvial layers. All horizontal wells are developed by natural energy. Due to the few drilling holes and influence by the resolution of seismic data, it is difficult to describe reservoirs with thickness over 20 meters. In this paper, seismic resonance amplitude inversion technology is introduced to restore the real response of thick reservoirs and interbeds by drilling and drilling verification, and the geological bodies with different thickness are displayed by frequency division RGB three primary colors. Flow units of heavy oil reservoirs with bottom water are divided according to the three major factors of interlayer, lithologic internal boundary and water-oil thickness ratio which have the greatest influence on horizontal well development, thick sand bodies are divided into 10 different flow units in three levels, each unit is separated from each other, and the reservoir structure, water-cut characteristics and water-flooding characteristics are different. The reliability of the research is improved by using the dynamic data of horizontal wells and newly drilled passing wells, which provides a basis for tapping the potential of heavy oil reservoirs with bottom water.

Strategies for High-quality Development of Greenhouse Vegetables in Zibo City,Shandong Province

This investigation report got a clear picture of the general situation of the development of greenhouse vegetable industry in Zibo,and found out the existing problems such as frequent harmful weather,few special varieties and high-grade varieties of greenhouse vegetables,fragmentation of new technology promotion of greenhouse vegetables,low level of intensive seedling raising of vegetables,backward level of facility planting structure and equipment,etc.This paper puts forward the strategies for the future high-quality development of vegetables:promoting the adjustment of vegetable planting structure,rationally arranging vegetables for rotation,strengthening vegetable technical guidance,and innovating vegetable consumption patterns.

Nitrogen Metabolism and Curing Characteristics of Flue-cured Tobacco Variety NC71

[Objectives]To explore the growth characteristics,nitrogen metabolism and curing characteristics of the new variety NC71 in strongly aromatic tobacco leaves production area.[Methods]With Yunyan 87 as the control and NC71 as the experimental material,the experiment was carried out in Nanyang tobacco area for two consecutive years to study the growth characteristics of tobacco plants,the activity of key enzymes in nitrogen metabolism,the content of secondary metabolites,and the differences of tobacco-related water content,PPO enzyme activity and total phenol content.[Results]NC71 plants had lower height,better appearance quality and lower nicotine,total sugar and chlorine content.NC71 high nitrogen treatment and Yunyan 87 medium nitrogen treatment had similar key enzyme activity of nitrogen metabolism,content of secondary metabolites;Yunyan 87 and NC71 were easy to cure and resistant to curing.[Conclusions]This study provides a reference for measuring the appropriate nitrogen application rate and optimizing the curing process from the activities of the key enzymes NR and GS in nitrogen metabolism at the mature stage of the variety.