L-tyrosine is one of the 20 amino acids that make up proteins and is an essential amino acid for mammals, often used as a nutritional supplement. The conventional methods for synthesizing L-tyrosine have some problems such as the production of many by-products, high requirements for production conditions, and environmental pollution. In this study, we designed and constructed a multi-enzyme cascade for the synthesis of L-tyrosine with alanine, glutamate, ammonium chloride, and phenol as substrates. Initially, the sources of glutamate oxidase, alanine aminotransferase, and tyrosine phenol lyase were screened and analyzed, which was followed by the identification of the rate-limiting enzyme in the reaction process. A colorimetric screening method was established, and the rate-limiting enzyme DbAlaA was engineered to enhance its activity by 40.0%. Subsequently, the reaction conditions, including temperature, pH, cell concentration, and surfactant and coenzyme dosages, were optimized. After optimization, the yield of L-tyrosine reached 9.93 g/L, with a alanine conversion rate of 54.90%. Finally, a feed-batch fermentation strategy was adopted, and the yield of L-tyrosine reached 56.07 g/L after 24 h, with a alanine conversion rate of 65.22%. This study provides a reference for the whole-cell catalytic synthesis of L-tyrosine and its industrialization.
Tyrosine/biosynthesis* ; Escherichia coli/metabolism* ; Tyrosine Phenol-Lyase/genetics* ; Multienzyme Complexes/metabolism* ; Fermentation

Objective To assess inter-observer variations(IOV)in the delineation of target volumes and organs-at-risk(OAR)for intensity-modulated radiotherapy(IMRT)of nasopharyngeal carcinoma(NPC)among physicians from different levels of cancer centers,thereby providing a reference for quality control in multi-center clinical trials.Methods Twelve patients with NPC of different TMN stages were randomly selected.Three physicians from the same municipal cancer center manually delineated the target volume(GTVnx)and OAR for each patient.The manually modified and confirmed target volume(GTVnx)and OAR delineation structures by radiotherapy experts from the regional cancer center were used as the standard delineation.The absolute volume difference ratio(△V_diff),maximum/minimum volume ratio(MMR),coefficient of variation(CV),and Dice similarity coefficient(DSC)were used to compare the differences in organ delineation among physicians from different levels of cancer centers and among the 3 physicians from the same municipal cancer center.Furthermore,the IOV of GTVnx and OAR among physicians from different levels cancer centers were compared across different TMN stages.Results Significant differences in the delineation of GTVnx were observed among physicians from different levels of cancer centers.Among the 3 physicians,the maximum values of △V_diff,MMR,and CV were 97.23%±83.45%,2.19±0.75,and 0.31±0.14,respectively,with an average DSC of less than 0.7.Additionally,there were considerable differences in the delineation of small-volume OAR such as the left and right optic nerves,chiasm,and pituitary,with average MMR>2.8,CV>0.37,and DSC<0.51.However,relatively smaller differences were observed in the delineation of large-volume OAR such as the brainstem,spinal cord,left and right eyeballs,and left and right mandible,with average△V_diff<42%,MMR<1.55,and DSC>0.7.Compared with the differences among physicians from different levels cancer centers,the differences among the 3 physicians from the municipal cancer center were slightly reduced.Furthermore,there were also differences in the delineation of target volumes for NPC among physicians from different levels cancer centers,depending on the staging of the disease.Compared with the delineation of target volumes for earlier stage patients(stages I or II),the differences among physicians in the delineation of target volumes for advanced stage patients(stages III or IV)were smaller,with average △V_diff and DSC of 98.31%±67.36%vs 69.38%±72.61%(P<0.05)and 0.55±0.08 vs 0.72±0.12(P<0.05),respectively.Conclusion There are differences in the delineation of GTVnx and OAR in radiation therapy for NPC among physicians from different levels of cancer centers,especially in the delineation of target volume(GTVnx)and small-volume OAR for early-stage patients.To ensure the accuracy of multicenter clinical trials,it is recommended to provide unified training to physicians from different levels of cancer centers and review their delineation results to reduce the effect of differences on treatment outcomes.

Objective:In order to explore the impact of corona virus disease 2019(COVID-19)on the hospitalization of children with bronchiolitis and to improve clinicians′ understanding of the characteristics of bronchiolitis during the COVID-19 epidemic.Methods:This was a multicenter clinical study, and the data have been collected from 23 children′s medical centers in China.All the clinical data were retrospectively collected from children with bronchiolitis who were hospitalized at each study center from January 1, 2019 to December 31, 2021.The results included gender, age at hospitalization, length of stay, respiratory syncytial virus(RSV) test results, severity rating, ICU treatment, and the total number of children hospitalized with respiratory tract infection during the same period.The clinical data of children with bronchiolitis in 2019 before COVID-19 epidemic and in 2020、2021 during COVID-19 epidemic were statistically analyzed and compared.Results:According to a summary of data provided by 23 children′s medical centers, there were 4 909 cases of bronchiolitis in 2019, 2 654 cases in 2020, and 3 500 cases in 2021.Compared with 2019, the number of bronchiolitis cases decreased by 45.94% in 2020 and 28.70% in 2021.In 2019, 2020 and 2021, there were no significant differences in gender ratio, age, and duration of hospitalization.Compared with 2019, the ratio of bronchiolitis to the total number of hospitalizations for respiratory tract infection decreased significantly in 2020 and 2021( χ2=12.762, P<0.05; χ2=84.845, P<0.05).The proportion of moderate to severe bronchiolitis cases in both 2020 and 2021 was lower than that in 2019, and the difference was statistically significant ( χ2=4.054, P<0.05; χ2=8.109, P<0.05).There was no statistically significant difference in the proportion of bronchiolitis cases requiring ICU treatment between 2019, 2020, and 2021 ( χ2=1.914, P>0.05).In 2019, a total of 52.60%(2 582/4 909) of children with bronchiolitis underwent RSV pathogen testing, and among them, there were 708 cases with RSV positive, accounting for 28.00%.In 2020, 54.14%(1 437/2 654) of children with bronchiolitis underwent RSV pathogen testing, and there were 403 cases with RSV positive, accounting for 28.04%.In 2021, 66.80%(2 238/3 500) of children with bronchiolitis underwent RSV pathogen testing, and there were 935 cases with RSV positive, accounting for 41.78%.Compared with 2019 and 2020, the RSV positive rate in 2021 showed a significant increase( χ2=99.673, P<0.05; χ2=71.292, P<0.05). Conclusion:During the COVID-19 epidemic, the implementation of epidemic prevention and control measures reduced the hospitalization rate and severity of bronchiolitis, but did not reduce the positive rate of RSV detection.

Objective:This study aimed to evaluate the efficacy of decitabine (DAC) and identify factors influencing treatment responses in patients with primary immune thrombocytopenia (ITP) who had failed glucocorticoid therapy.Methods:Clinical data of 61 patients with glucocorticoid-resistant ITP who received DAC therapy (5 mg·m -2·d -1×3 d via intravenous infusion) for at least three cycles with 3-4-week intervals at the Department of Hematology, Qilu Hospital of Shandong University, from November 2015 to June 2021 were analyzed retrospectively. Results:The 61 patients comprised 20 males and 41 females, with a median age of 45 years (range: 15-81 years). Among them, 43 patients were glucocorticoid-dependent (glucocorticoid-dependent group), while 18 patients were glucocorticoid-resistant (glucocorticoid-resistant group). Following DAC treatment, 12 patients (19.67% ) achieved complete response (CR), and 16 patients (26.23% ) exhibited response (R), resulting in an overall response (OR) rate of 45.90% (28/61). Comparison between the OR group ( n=28) and the non-response (NR) group ( n=33) revealed significant differences in responses to glucocorticoids (dependent or resistant) and platelet counts before treatment ( χ2=8.789, P=0.003; z=-2.416, P=0.016). The glucocorticoid-dependent group showed higher platelet counts than the glucocorticoid-resistant group after the second and third cycles of DAC treatment ( P=0.032, 0.024). Moreover, the OR rates after the first, second, and third cycles of DAC treatment in the glucocorticoid-dependent group were all higher than those in the glucocorticoid-resistant group ( P=0.042, P=0.012, P=0.029). A significant correlation was observed between glucocorticoid dependence and responses to DAC treatment ( OR=9.213, 95% CI 1.937-43.820, P=0.005) . Conclusion:DAC demonstrates definitive efficacy with mild adverse effects in a subset of patients with glucocorticoid-resistant primary ITP. Glucocorticoid dependence and higher platelet counts before treatment are associated with a favorable response to DAC therapy.

Background: and Purpose Collateral circulation is considered an important factor affecting the risk of stroke, but the factors that affect collateral circulation remain unclear. This study was performed to identify the factors associated with collateral circulation, especially blood lipids. Methods: The study involved patients who had undergone digital subtraction angiography and were confirmed as having severe unilateral stenosis or occlusion of the internal carotid artery (ICA). We classified the collateral circulation status of each patient as good (Grade 3 or 4) or poor (Grade 0, 1, or 2) according to the grading system of the American Society of Interventional and Therapeutic Neuroradiology/American Society of Interventional Radiology. We collected data on patients’ characteristics and identified the factors that affect collateral circulation. Results: This study included 212 patients. The multivariate logistic regression analysis showed that the high-density lipoprotein cholesterol (HDL-C) concentration and a complete anterior half of the circle of Willis were independent protective factors for good collateral circulation, whereas elevated lipoprotein(a) [Lp(a)] and serum creatinine concentrations were independent risk factors for good collateral circulation. The area under the receiver operating characteristics curve (AUC) was 0.68 (95% confidence interval [CI], 0.61–0.76) for HDL-C and 0.69 (95% CI, 0.62–0.76) for Lp(a). A binary logistic regression model analysis of the joint factor of HDL-C and Lp(a) yielded an AUC of 0.77 (95% CI, 0.71–0.84). Conclusions In patients with severe unilateral ICA stenosis or occlusion, the combination of HDL-C and Lp(a) is a useful predictor of collateral circulation.

【Objective】 To investigate the airway parameters of adult-onset eosinophilic asthma （EA） and analyze the correlation between airway remodeling and lung function by quantitative CT. 【Methods】 From March 2015 to November 2016， totally 94 subjects from the “FACT-Digital Lung” Multi-research Center were divided into three groups： 30 normal subjects， 33 EA patients and 31 non-eosinophilic asthma （NEA） patients. We measured and recorded the bronchial parameters of RB1， LB1+2， RB10， and LB10， and small airway disease parameters. The indicators for quantitative evaluation of bronchial parameters include lumen area （LA）， wall thickness （WT）， wall area （WA）， and wall area percentage （WA%）. The parameters for the quantitative assessment of small airway disease included the percentage of inspiratory voxels below -950HU （IN-950）， the mean lung density （MLDin）， and the whole volume of the lung in inspiration （Vin）. Pearson or Spearman rank correlation analysis was used to evaluate the correlation between these parameters and lung function. 【Results】 The differences in LA/BSA， WT/√BSA， and WA/BSA between the three groups were statistically significant （P<0.05）. FEV1% had a significant correlation with IN-950 and MLDin （P<0.01）. FEV1/FVC had a significant correlation with Vin， IN-950， and MLDin （P<0.01）. EOS counts were positively related to IN-950 （r=0.343， P=0.011）， while EOS had a negative correlation with FEV1% （r=－0.343， P=0.015）. 【Conclusion】 With the increase of eosinophils counts in peripheral blood， the airway's stenosis in asthma patients gradually increased， and the extent of airflow limitation steadily increased. The IN-950 may be a sensitive imaging biomarker for evaluating the small airway disease in adult-onset eosinophilic asthma patients.

Objective: To exlpore the value of voxel-based quantitative CT in evaluation on injury degree and spatial distribution in different lobes of chronic obstructive pulmonary disease (COPD) patients. Methods: COPD patients who underwent inspired and expired CT scanning were consecutively recruited from the multi-center study named Digital Lung.Quantitative parametres of functional small-airway disease (fSAD) and emphysema (Emph) were measured. The degree and distribution of pulmonary lobar injury were analyzed according to Emph and fSAD among different pulmonary lobes. At the same time, the correlation of quantitative CT distribution and lung function of each lobe was analyzed. Results: A total of 50 COPD patients were eventually included. Emph and fSAD of the right middle lobe (RML) was the most severe, followed by the upper lobes of the two lungs, while the lowest degree of injury were seen in both lower lobes of the lungs. Emph and fSAD were both mainly distributed in the left upper lobe (LUL), followed by in the right upper lobe (RUL), while in the right middle lobe (RML) was the least. Either fSAD or Emph showed better correlations with FEV1% in both lower lobes. Conclusion: The injury of the lobes in COPD patients mainly distribute in the RML and both upper lobes, especially the former. Emph and fSAD mainly distribute in the LUL, followed by the RUL. The lower lobes of the lungs have greater influence on pulmonary function in COPD patients.

It is an important link and key of nursing skills improvement to effectively and comprehensively evaluate the nursing skills. Traditional evaluation method of nursing skills was single which needs to further explore the systematic and effective assessment system. Direct observation of procedural skills (DOPS) is an effectively formative evaluation method which evaluates operators and feedback immediately on clinical skills or operations by assessors. DOPS has teaching and assessment functions and has been paid attention to in the field of nursing practice. This paper combs and analyzes the application of DOPS in nursing practice so as to provide a reference and basis for further popularizing and properly use DOPS.

Objective To establish and validate a voxel-based method for the quantitative detection of air trapping (AT),and to explore its diagnostic value by preliminarily apply this method in chronic obstructive pulmonary disease (COPD) patients.Methods From March 2015 to February 2016,fifty healthy young volunteers and eighteen COPD patients who underwent both end-inspiratory and end-expiratory CT were included from the Digital Lung Multi-center Study.The quantitative parameters of AT and emphysema were measured by both the voxel-based quantitative method and the conventional threshold method,respectively.All subjects underwent pulmonary function examination within 3 days after CT examination.For healthy volunteers,paired sample rank-sum test was used to compare the difference of quantitative parameters between voxel-based method and threshold method,Spearman rank correlation analysis was used to investigate the correlation between quantitative parameters of the two methods and pulmonary function.For COPD patients,the distribution and extent of AT and emphysema in patients with similar degree of pulmonary function (PFT) injury were observed.Results There were varying degrees of AT in the asymptomatic youth,with a median value of 5.70％ for the voxel-based method and with a median value of 7.96％ for the conventional threshold method,there was significant difference(Z=-4.015,P＜0.001).The correlation between AT and emphysema parameters of the voxel-based method and PFT parameters (r=-0.399 and-0.494,-0.335 and-0.439 separately,P＜0.05) were higher than that of the conventional threshold method,respectively (r=-0.357 and-0.453,-0.284 and-0.391,respectively;all P＜0.05).Furthermore,the voxel-based method can classify COPD patients with similar degree of pulmonary function injury into three subtypes:AT-dominant,emphysema-dominant,and mixed.Conclusions The voxel-based AT quantitative measurement method not only has high sensitivity and accuracy,but also provides imaging phenotype for the diagnosis of COPD and provides assistant decision-making for clinical management.

Objective? To explore peer supporters experience for people with acquired immunodeficiency syndromes(AIDS). Methods? By purposive sampling, 6 peer supporters with AIDS who enrolled in the peer support program of Shanghai Public Health Clinical Center from May of 2017 to January of 2018 were selected as the interviewees in this study. Semi-structured in-depth interviews were conducted and the Claizzi seven-steps method was used to analyze the data. Results? Three themes about the AIDS peer supporter experience could be concluded: peer support has its own advantages, peer support has mutual benefits, peer support could bring about negative effects. Conclusions? Strengthen the positive role of peer support, reduce the possible negative impact, and standardize peer training to ensure the quality and effectiveness of peer support.