Pyran- and furanocoumarins are key representatives of tetrahydropyrans and tetrahydrofurans, respectively, exhibiting diverse physiological and medical bioactivities. However, the biosynthetic mechanisms for their core structures remain poorly understood. Here we combined multiomics analyses of biosynthetic enzymes in Peucedanum praeruptorum and in vitro functional verification and identified two types of key enzymes critical for pyran and furan ring biosynthesis in plants. These included three distinct P. praeruptorum prenyltransferases (PpPT1-3) responsible for the prenylation of the simple coumarin skeleton 7 into linear or angular precursors, and two novel CYP450 cyclases (PpDC and PpOC) crucial for the cyclization of the linear/angular precursors into either tetrahydropyran or tetrahydrofuran scaffolds. Biochemical analyses of cyclases indicated that acid/base-assisted epoxide ring opening contributed to the enzyme-catalyzed tetrahydropyran and tetrahydrofuran ring refactoring. The possible acid/base-assisted catalytic mechanisms of the identified cyclases were theoretically investigated and assessed using site-specific mutagenesis. We identified two possible acidic amino acids Glu303 in PpDC and Asp301 in PpOC as vital in the catalytic process. This study provides new enzymatic tools in the epoxide formation/epoxide-opening mediated cascade reaction and exemplifies how plants become chemically diverse in terms of enzyme function and catalytic process.

ObjectiveTo evaluate the clinical efficacy and safety of Tongluo Mingmu capsules in the treatment of diabetic retinopathy with blood stasis， collateral obstruction， and Qi and Yin deficiency syndrome. MethodA randomized， double-blind， positive-control， and multi-center clinical trial design method was used. 416 patients with diabetic retinopathy with blood stasis， collateral obstruction， and Qi and Yin deficiency syndrome in four test centers were included （the ratio of the treatment group to the control group was 3∶1）. On the basis of standardized hypoglycemic treatment， the treatment group was given both four Tongluo Mingmu capsules and two Calcium Dobesilate capsule agents three times a day， while the control group were given both two Calcium Dobesilate capsules and four Tongluo Mingmu capsule agents three times a day. The course of treatment was 12 weeks. The curative effect of Tongluo Mingmu capsules was evaluated by comparing the comprehensive curative effect of diabetic retinopathy， traditional Chinese medicine（TCM） syndrome score， corrected visual acuity， fundus changes， fundus fluorescence angiography， and other curative effect indexes before and after treatment in the two groups. At the same time， general examination， laboratory examination， and adverse events were performed to evaluate the safety of the drug. ResultThe baseline demographic data and disease characteristics of the treatment group and the control group were balanced and comparable， with the difference not statistically significant. After 12 weeks of treatment， the total effective rate of the comprehensive curative effect of diabetic retinopathy in the treatment group （61.0%， 189/310） was better than that in the control group （44.1%， 45/102）， and the difference was statistically significant （χ²=8.880， P<0.01）. The total effective rate of TCM syndromes in the treatment group （88.4%， 259/293） was better than that in the control group （69.9%， 65/93）， and the difference was statistically significant （χ²=17.927， P<0.01）. The disappearance rate of dry eyes （χ²=8.305）， dull complexion （χ²=4.053）， lassitude （χ²=10.267）， shortness of breath （χ²=8.494）， and dry stool （χ²=8.657） in the treatment group was higher than that in the control group， and the difference between the groups was statistically significant （P<0.05， P<0.01）. In terms of improving corrected visual acuity （χ²=8.382）， fundus changes （χ²=6.026） ， the treatment group was significantly better than the control group （P<0.05）. During the trial， the incidence of adverse events in the treatment group and the control group was 1.3% and 2.9%， respectively. There was no significant difference between the two groups. In addition， there were no serious adverse events and adverse events leading to withdrawal in both groups. ConclusionTongluo Mingmu capsules can improve the comprehensive curative effect of diabetic retinopathy and enhance the efficacy of TCM syndromes， visual acuity， fundus changes， and fundus fluorescein angiography， with great safety. Therefore， it can provide a new alternative therapeutic drug for patients with diabetic retinopathy.

Objective Based on clinical surgical statistical instances,the influence of double fenestration branch stents on the blood flow field after different depths of implantation in the diseased thoracic aorta was investigated.Methods Thoracic aorta,thoracic aorta-coated stent,and branch vessel-coated stent were established.The finite element calculation method was used to analyze the branch stent implanted into the diseased aorta at different depths(5,10,and 15 mm),and experimental verification was performed using an in vitro tachymetry experimental platform.Results There were certain patterns for maintaining stable perfusion of the blood flow field with branch stent implantation at different depths in the thoracic aorta.The branch blood perfusion rate in Group D10-5(the implantation depths of the left common carotid artery branch stent and left subclavian artery branch stent were 10 mm and 5 mm,respectively)was at a good level,and TAWSSmax was at the lowest level(44.94 Pa),thereby showing the best simulation results.Conclusions When the left subclavian artery branch stent implantation in the thoracic aorta was short,the depth of the left common carotid artery branch stent implantation in the aorta was appropriately increased to obtain a more stable blood flow field.This study provides a theoretical reference for the double-fenestration technique in clinical practice.

Objective:To investigate the effect of deviation from the isocenter point on the quality of CT images at the same radiation dose.Methods:A 160-layer CT scanner was used to scan the phantom at isocenter and deviations of 3, 6, 9, 12 and 15 cm. CT was performed with the following parameters: 120 kVp; 400 mAs; slice thickness, 1 mm; and slice increment, 1 mm. Images were reconstructed using the filtered back projection algorithm. Noise power spectrum (NPS), task transfer function (TTF) and detectability index (d′) were measured. NPS peak was used to quantify the noise magnitude and TTF 50% was used to quantify the spatial resolution. NPS, TTF and d′ were compared using one-way ANOVA. Results:The NPS average spatial frequency, spatial resolution and d′ values gradually decreased as the offset distance increased and the amount of noise increased. NPS peak at isocenter and deviations of 3 cm, 6 cm, 9 cm, 12 cm and 15 cm were (94.31±1.48), (104.25±1.46), (131.44±1.96), (171.86±1.91), (224.05±1.37), (286.51±2.09)HU 2·mm 2, respectively ( F=37 241.91, P<0.001). And d′ values of 2 mm low-contrast lesions were 3.51±0.06, 3.31±0.04, 3.01±0.04, 2.59±0.06, 2.21±0.03, 1.88±0.03, respectively. The reduction in spatial resolution was more pronounced for high contrast, and the d′ values decreased to a similar extent for various types of lesions. The noise was increased by about 82%, the high contrast spatial resolution was decreased by about 12%, and the d′ value was decreased by about 26% at 9 cm from the isocenter point (all P<0.05). The noise was increased by about 204%, the high contrast spatial resolution was decreased by about 27%, and the d′ value was decreased by about 45% at 15 cm from the isocenter (all P<0.05). Conclusion:The CT image quality was decreased with the increase of the offset distance from the CT isocenter point. The image quality was severely compromised at offset distances greater than 9 cm.

Asthma is a common chronic airway inflammatory disease, which is characterized by airway stenosis, airway wall thickening and increased mucus secretion followed by reversible airflow restriction.At present, asthma is considered to be a complex and heterogeneous disease, and its pathogenesis remains elusive.There are diverse immune cells involved in the formation of asthma, including T lymphocytes, eosinophils, neutrophils, etc.Due to the continuous renewal of classification and function of T lymphocytes subsets, their role in asthma has attracted more attention.Here, this review aims to summarize the immunological characteristics and roles of different T cell subsets in asthma, and highlight the new findings of T cell subsets in the pathogenesis of severe asthma, leading to provide inspiration and help for the study of the immunology pathogenesis, clinical diagnosis, treatment and prognosis in asthma.

Objective:To investigate the characteristic of mild cognitive impairment (MCI) in the adults aged 48 years and over in a coal mine community, and to analyze its associated risk factors.Methods:From July to October 2019, a questionnaire survey for basic information was conducted among 180 middle-aged and elderly adults who met the inclusion criteria in the Datong coal mine community. The cognitive function was evaluated by Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). The effects of gender, age, years of education, sleep, living alone, physical exercise, social activities, smoking and drinking status, body mass index and chronic diseases on cognitive level were analyzed by single factor stratification and multiple linear regression.Results:There was no significant difference in the positive rate of MCI screened by MMSE and MoCA in the age groups of 48-<64, 64-<72 and 72-90 (original and corrected P>0.05); The positive rate of MCI in MoCA screening (64.4%, 66.7%, 60.9%) was significantly higher than that in MMSE (35.6%, 45.6%, 28.1%) (all P<0.05); MMSE was positively correlated with MoCA score ( r=0.762, P<0.001). With the increase of age, the scores of memory, execution and visual space detected by MoCA decreased significantly (all P<0.05), while the scores of attention, language and orientation did not change significantly (all P>0.05). Univariate stratification showed that the significant influencing factors of MMSE or MoCA scores were gender, age, years of education and sleep status (all P<0.05). Multiple linear regression analysis showed that gender ( βMMSE=-0.192; βMoCA=-0.140), years of education ( βMMSE=0.209; βMoCA=0.328) and sleep status( βMMSE=-0.162; βMoCA=-0.136) were risk factors affecting MMSE and MoCA scores ( P<0.05). Conclusions:More middle-aged and elderly adults with MCI might be observed in a coal mine community, and the main characteristics of MCI are impaired memory, executive function and visual space. To prevent and reduce the occurrence of dementia, early interventions of MCI should be carried out among the adults with female, old age, low years of education and poor sleep quality.

Objective To detect the radiation of ¹³¹I in treatment site of a grade A tertiary hospital. Methods A total of 25 patients with thyroid cancer were administrated ¹³¹I at a total dose of 82880 MBq. After administration, the ambient dose equivalent rate of the ward was detected with X- and γ-ray detectors. After patient discharge, surface contamination of the ward was detected with α/β surface contamination meter. During patient hospitalization and on the day of discharge, air samples were collected from ¹³¹I treatment site and office area. The air samples were measured using a HPGe γ-ray spectrometer and the concentration of ¹³¹I in air was calculated. Results The ambient dose equivalent rate in the ward ranged from 0.15 to 0.46 μSv/h. Before ward cleaning, surface contamination ranged from 0.53 to 40.1 Bq/cm² and the highest value was recorded on the toilet. Within 4 h after administration, the concentrations of ¹³¹I in air in treatment site and the corridor of the office area were 1.74 Bq/m³ and 0.66 Bq/m³, respectively. The ventilation air flow rate in the treatment site was 0.50 m/s. Ventilation decreased the concentration of ¹³¹I in air by 29.7%, 79.7%, and 53.3% compared with the previous day during hospitalization and on the day of discharge. Conclusion The radiation of external exposure of ¹³¹I in the treatment site is low and the shielding is effective. Before ward cleaning, the surface contamination is lower than the required limits except for the toilet. Ventilation is the primary way to reduce the concentration of ¹³¹I in air.

Objective:To construct a recombinant HBV replication-type plasmid with liver-enriched transcription factor binding site mutation at proximal of HBV C promoter in order to elucidate the role of HBx-enhanced HBV replication.Methods:Site-directed mutagenesis technology was used to construct a recombinant plasmid with liver-enriched transcription factor binding site mutation at proximal of HBV C promoter on the basis of wild-type HBV replicating plasmid and HBV replicating plasmid lacking HBx expression. Subsequently, plasmid transfection was carried out in HBV liver cancer cell replication model and mouse replication model, and HBV replication intermediates of cells and mouse liver tissue were extracted for detection.Results:Based on the HBV replicating plasmid, the HBV replicating plasmid with liver-enriched transcription factor binding site mutation at proximal of HBV C promoter was successfully constructed. HBx-enhanced HBV replication were detected in both the HBV liver cancer replication model and the mouse replication model. After mutating liver-enriched transcription factor binding site mutation at proximal of HBV C promoter, the effect of HBx on the enhancement of HBV replication was not significantly affected.Conclusion:HBx may not enhance HBV replication through liver-enriched transcription factor binding site mutation at proximal of HBV C promoter. The role of other liver-enriched transcription factor binding sites in HBx-enhanced HBV replication needs further study.

Chronic hepatitis B and its related complications seriously endanger the lives and health of our country people. Although the first-line nucleos(t)ide analogs such as entecavir, tenofovir disoproxil fumarate and tenofovir alafenamide fumarate can inhibit virus replication to a certain extent, delay or prevent disease progression, and reduce the incidence of hepatitis B-related liver cancer, but in clinical practice, HBV DNA positivity is still detected continuously or intermittently in the serum of some patients. Therefore, low-level viremia has received widespread attention and triggered discussion, and has become the difficulties and hotspot of antiviral treatment of chronic hepatitis B. This article summarizes and discusses the definition and incidence in line with the main guidelines and studies, impact of disease control and clinical prognosis, and the current treatment options in order to provide definite reference for the management of low-level viremia during antiviral therapy in patients with chronic hepatitis B.

Background:As one of the most popular traditional Chinese medicines (TCMs) for the treatment of various liver diseases,virgate wormwood herb (Artemisia capillaris Thunb.) has a long application history in TCM practices.It has been well established that the chemical composition is responsible for the pronounced therapeutic spectrum of A.capillaris.Although they are comprehensive,the time-intensive liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) assays cannot fully satisfy the analytical measurement workload from many test samples.Direct infusion-MS/MS (DI-MS/MS) may be the optimal choice to achieve high-throughput analysis if the mass spectrometer can universally record MS2 spectra.Methods:According to the application of gas phase ion fractionation concept,the MS/MSALL program enables to gain MS2 spectrum for each nominal m/z value with a data-independent acquisition algorithm via segmenting the entire MS1 ion cohort into sequential ion pieces with 1 Da width,when sufficient measurement time is allowed by DI approach.Here,rapid clarification of the chemical composition was attempted for A.capillaris using DI-MS/MSALL.A.capillaris extract was imported directly into the elec-trospray ionization interface to obtain the MS/MSALL measurement.After the MS1-MS2 dataset was well organized,we focused on structural characterization through retrieving information from the available databases and literature.Results:Twenty-six compounds were found,including 12 caffeoyl quinic acid derivatives,7 flavonoids,and 7 compounds belonging to other chemical families.Among them,24 ones were structurally iden-tified.Compared with the LC-MS/MS technique,DI-MS/MSALL has the advantages of low-costing,solvent-saving,and time-saving.Conclusions:Chemical profiling of A.capillaris extract was accomplished within 5 min by DI-MS/MSALL,and this technique can be an alternative choice for chemical profile characterization of TCMs due to its extraordinary high-throughput advantage.