Methionine synthase (MS, EC2.1.1.13), a key enzyme in the folate metabolism area catalyzing methyl transfer from N5-methyltetrahydrofolate to homocysteine to give tetrahydrofolate and methionine, takes a core position in folate cycle, one-carbon-unit transfer and sculpture amino acid pathways. Cobalamin-dependent methionine synthase was purified from rat liver. The enzyme was purified 609-fold to near homogeneity by batch chromatography on DE-52, anion-exchange chromatography on Q Sepharose Fast Flow and CHT-I hydroxyapatite column and was identified by SDS-PAGE and Western blotting. The enzyme activity was determined by spectrophotometric assay. In addition, the influencing factor and optimal reaction condition were performed. The steady state kinetic of rat liver methionine synthase was similar to that of other mammalian cobalamin-dependent methionine synthase which employed a Ping-Pong mechanism. The result indicated that cobalamin-dependent methionine synthase purified from rat liver is suitable for screening and studying methionine synthase specific inhibitors.

BACKGROUND: Recently biodegradable hydrogel has been extensively used to delivery anticancer drug and bioactive macromolecule. However, to protect the activity of the bioactive macromolecule, we need to obtain series of hydrogel which have milder hydrogelation conditions and shorter hydroglation time.OBJECTIVE: To prepare enantiomeric poly(L-Lactic acid) (PLLA)-poly(ethylene glycol (PEG)-PLLA/ poly(D-Lactic acid) (PDLA)-PEG-PDLA stereocomplex hydrogel which has shorter hydroglation time, to physically encapsulate a model drug-lysozyme and sustained release it from the hydrogel. METHODS: Triblock copolymers of PLLA-PEG-PLLA and PDLA-PEG-PDLA were synthesized by ring-opening polymerization of L(D)-lactide using PEG as the initiator and Sn(Oct)2 as the catalyst. The triblock copolymers were characterized by 1H nuclear magnetic resonance, FT-IR and X-Ray diffractometry. A hydrogel was prepared from an aqueous mixture of PLLA20-PEG227-PLLA20 and PDLA21-PEG227-PDLA21 (10 wt% concentration) at room temperature for 12 hours. X-Ray diffractometry test was used to research the gelation mechanism. The release profile of the lysozyme as a model drug from the hydrogel was tested. The morphology of the freeze-dried hydrogel was investigated by scanning electron microscope. The cytotoxicity of the hydrogel was evaluated by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide) assay.RESULTS AND CONCLUSION: Triblock copolymers of PLLA-PEG-PLLA and PDLA-PEG-PDLA were obtained. Both the PEG and PLA blocks in the copolymers could crystallize, but the crystallization of the PEG block was predominant. The stereocomplex formation between the PLLA and PDLA blocks within the hydrogel was confirmed by the X-Ray diffractometry analysis. The release profile of the lysozyme from the hydrogel exhibited a sustained-release pattern with a duration period of 7 days. The hydrogel exhibited a 3D interconnected porous structure with 50-100 μm pore size after being freeze-dried. The mouse fibroblast cell viability percentage was 99.3% after the cells contacted with the 100% extracted liquid for 72 hours.

Objective To evaluate the efficacy of preoperative biliary drainage (PBD) in the pancreaticoduodenectomy for malignant obstructive jaundice.Methods Database including PubMed,EMBASE,Cochrane Central Register of Controlled Trials,Academic Degree Dissertation Database and Conference Database were searched with malignant obstructive jaundice,pancreaticoduodenectomy,preoperative biliary drainage,comparative study.Literatures about the randomized controlled trials of PBD (PBD group) and efficacy of early surgery (ES group) in the pancreaticoduodenectomy were retrieved from January 2001 to December 2013,and then a Meta analysis was carried out based on the data.The count data were analyzed using the odds ratio (OR),relative risk (RR) and 95％ confidence interval (95％ CI),and the measurement data were analyzed using mean difference (MD) and 95％ CI.The heterogeneity of the data was analyzed using the I2 test.Data were integrated by fixed or random effect model.Results Twelve literatures including 1 982 patients were selected.There were 1 029 patients in the PBD group and 953 in the ES group.The results of Meta analysis showed that the operation time,volume of blood loss and rate of postoperative wound infection in the PBD group were significantly different from those in the ES group (MD =10.50,107.92,95％ CI:6.34-14.66,16.43-199.42;RR =1.62,95％CI:1.19-2.21,P ＜0.05).There were no significant differences in the postoperative mortality,incidence of pancreatic fistula,incidence of bile leakage,incidence of delayed gastric emptying and duration of hospital stay between the 2 groups (RR=0.69,95％CI:0.52-0.92;OR =0.68,1.35,95％CI:0.38-1.21,0.93-1.95;MD =0.69,95％CI:-0.67-2.05;RR =0.00,95％ CI:-0.02-0.01,P ＞0.05).Conclusion PBD in the pancreaticoduodenectomy for malignant obstructive jaundice cannot reduce postoperative mortality and incidence of complications in patients,and should not be used as the conventional management in the perioperative period.

Objective:To establish a new approach to synthesis of diethyl N-[4-[(2,4-diaminopyrido [3,2-d]pyrimidin-6-yl)methylamino]benzoyl]-L-glutamate.Methods:Target compound (5) was syn-thesized by the use of (2,4-dioxo-tetrahydropyridopyrimidin-6-yl) methyl acetate (1) as starting material via hydrolysis, chlorination, condensation with diethyl (p-aminobenzoyl)glutamate and aminolysis.Re-sults:A new approach to synthesis of diethyl N-[4-[(2,4-diaminopyrido[3,2-d]pyrimidin-6-yl)methyl-amino]benzoyl]-L-glutamatewas established .This synthetic route has hydrolysis reaction , chlorination, diethyl N-( p-aminobenzoyl )-L-glutamate condensation reaction and ammonolysis reaction .The total yield is 36.7%.The structures of those compounds have identified by 1 H nuclear magnetic resonance , 13 C nu-clear magnetic resonance and mass spectrometry .This synthetic route avoid the unstable brominated re-action product and improves the harsh condition of ammonolysis reaction .Conclusion:The new synthetic route has improved the reaction condition and the stability of the intermediate , and increased the extent of the derivative compounds , which has great significance to anti-folic acid of anti-tumor inhibitor synthesis .

ObjectiveTo explore the status of social anxiety and study the relationship between social anxiety and self-consciousness,self-esteem among primary students.MethodsUsing stratified randomization sampling method,568 primary students in grade 4 ～ 6 were investigated with social anxiety scale for children( SASC ),self-consciousness scale for children(PHCSS) and self-esteem scale(SES).Results①The score of SASC in the group of primary students was obviously higher than that of Chinese norm (P＜0.01).②The SASC and negative evaluation scores in the female were higher than the male (P ＜ 0.05 ),the negative evaluation scores in the sixth grade (3.22 ± 2.82) was higher than the fifth grade (2.53 ± 2.76,P ＜ 0.01 ) and fourth grade ( 2.54 ± 2.68,P＜ 0.05 ).The primary students in migrant workers elementary school,the single parent family and the relatively low income family had higher social anxiety scores than others(P＜0.05 ).③The SASC and two major factors were significantly negative correlated with the self-consciousness and each subscale( r =-0.202 ～ -0.511,P ＜ 0.01 ),and positive correlated with the self-esteem( r =0.282,0.270,0.305,P ＜ 0.01 ).④)The anxiety and gregariousness had significant prediction function of 25.5％ on negative evaluation,and 28.2％ on SASC,anxiety,gregariousness,intelligence and school situation had significant prediction function of 20.4％ on social avoidance and distress.ConclusionsPrimary students in grade 4 ～ 6 existed social anxiety.There are significant differences for their level of anxiety in different gender,grade,elementary school,family structure,monthly income.And social anxiety is closely related to self-consciousness and self-esteem.

Objective:To find the best synthesis method of 6-benzyl-1-[ ( benzyloxy ) methyl ]-3-hydro-xy-5-(hydroxymethyl)pyrimidine-2,4(1H,3H)-dione e for observing the change of its biological activity after N-3 hydroxylation .Methods:After trying some N-hydroxylation methods , the target compound was successfully synthesized via one-pot oxidizing process by sodium hydride ( NaH) and 3-chloroperbenzoic acid( m-CPBA);the anti-HIV reverse transcriptase ( RT) activity and integrase ( IN) activity of the tar-get compound was assayed via enzyme-linked immunesorbent assay ( ELISA) and phosphorylation of DNA package method .Results:The target compound could be obtained through the improved m-CPBA oxida-tive method by only one step , and the yield of the reaction could reach 60%-70%.And the structure of this compound was identified by 1 H NMR, 13 C NMR and MS;The activity result showed it added the an-ti-HIV IN activity after N-3 hydroxylation as well as retained the anti-HIV RT activity.Conclusion:The improved m-CPBA oxidative method is a convenient and efficient way to prepare the compound 6-benzyl-1-[(benzyloxy)methyl]-3-hydroxy-5-(hydroxymethyl)pyrimidine-2,4(1H,3H)-dione e which has both anti-HIV RT and IN activity .

Objective To develop and test the reliability and validity of the Intrinsic Capacity Assessment Scale for the Older People,so as to provide an effective tool for the assessment of the intrinsic capacity of the aged.Methods Based on the International Classification of Functioning,Disability and Health(ICF)as the theoretical framework,the initial version of The Intrinsic Capacity Assessment Scale for the Older People was developed through literature analysis,Delphi expert consultation and pre-survey.From July to September 2023,650 old people were selected by convenience sampling method to conduct a survey,and 20 old people were surveyed after 2 weeks again to test the reliability and validity of the scale.Results The effective questionnaire recovery rates of the 2 rounds of expert correspondence were 92.3％and 91.7％;the expert authority coefficients were 0.83 and 0.86;the mean importance scores of items were 2.04-3.79 and 3.50-3.82,and the full score ratios were 4.2％-83.3％and 54.6％-86.4％,respectively.The coefficients of variation were 0.11-0.42 and 0.11-0.23,respectively.A total of 5 common factors were extracted from exploratory factor analysis,and the cumulative variance contribution rate was 68.327％.The results of confirmatory factor analysis showed that the fit indexes were x2/df=1.908,RMSEA=0.054,CFI=0.931,IFI=0.932,TLI=0.922,indicating a good fit.The Cronbach's α coefficient of the scale was 0.944;the split half reliability was 0.806;the retest reliability was 0.933.The content validity index of item level was 0.82-1.00,and the content validity index of scale level was 0.91.The Intrinsic Capacity Assessment Scale for the Older People included 35 items in 5 dimensions:movement,vitality,sensation,cognition and psychology.Conclusion The Intrinsic Capacity Assessment Scale for the Older People has good reliability and validity,and it can be used as a reliable tool to evaluate the intrinsic capacity level of the aged.

Children and adults differ significantly in physiology,biochemistry and immune function,which leads to sig-nificant differences in blood transfusion strategies between children and adults.To guide the clinical transfusion practice of pediatric patients and improve the prognosis of children,the National Health Commission organized the formulation and re-lease of the health industry standard Guideline for Pediatric Transfusion(WS/T 795-2022).This paper will briefly introduce some concepts that help understand of the Standard and the preparation process of the Standard,and explain and interpret the preparation of the"scope","general provisions"and"factors to consider"of the Standard,hoping to contribute to the understanding and implementation of the Standard.

Objective To improve the charging management system for endoscopic pathological specimens and achieve comprehensive traceable information management throughout the entire process.Methods Through business process reengineer-ing,the manual recording process was digitized,and from the collection of endoscopic pathological specimens to the release of pa-thology reports,the medical information,management information,and fee information were integrated into the information system through joint transformation.Results The electronic management of endoscopic pathological specimens was realized,addressing key issues such as simplification of specimen labeling,missed charges,paper-based management,and lack of traceability in the information transmission process.Conclusion The use of information systems can improve the efficiency of closed-loop manage-ment of endoscopic pathological specimens and effectively solve the problem of missed charges.It has practical application value.

Objective:To explore the performance of the commonly used whole blood C-reactive protein (CRP) detection systems and give related recommendation on the performance requirements of detection systems.Methods:A total of 7 540 venous blood samples from 26 maternal, child and children′s hospitals were collected to conduct this multi-center study on the analytical performance of 5 commonly used whole blood CRP detection systems from March to April in 2019. The blank check, carryover, repeatability, intermediate precision, linearity, sample stability, influence of hematocrit/triglyceride/bilirubin, comparison with SIEMENS specific protein analyzer and trueness were evaluated. The 5 systems included BC-5390CRP autohematology analyzer, AstepPLUS specific protein analyzer, Ottoman-1000 Automated Specific Protein POCT Workstation, i-CHROMA Immunofluorometer equipment Reader and Orion QuikRead go detecting instrument. The 5 systems were labeled as a, b, c, d and e randomly.Results:Within the 5 systems, all values of blank check were less than 1.00 mg/L, the carryovers were lower than 1.00%. The repeatability of different ranges of CRP concentrations including 3.00-10.00, 10.00-30.00 and>30.00 mg/L were less than 10.00%, 6.00% and 5.00%, respectively, and the intermediate precision was less than 10.00%. The linearity correlation coefficients of the 5 systems were all above 0.975, while the slope was within 0.950-1.050. Whole blood samples were stable within 72 hours both at room temperature (18-25 ℃) and refrigerated temperature (2-8 ℃). The CRP results were rarely influenced by high triglyceride or bilirubin, except for the immmunoturbidimetric test based on microparticles coated with anti-human CRP F(ab) 2 fragments. When triglyceride was less than 15.46 mmol/L, the deviation of CRP was less than 10.00%. When bilirubin was less than 345.47 μmol/L, the deviation of CRP was less than 10.00%. CRP was more susceptible to Hct on the systems without Hct correction. The deviation of CRP between different Hct dilution concentration and 40% dilution concentration can reach as high as 67.48%. The correlation coefficients ( r) of 5 systems were all more than 0.975 in the range of 0-300.00 mg/L compared with Siemens specific protein analyzer. All systems passed the trueness verification using the samples with specified values of 12.89 and 30.60 mg/L. Conclusion:The performance of 5 systems can basically meet the clinical needs, but it is suggested that the whole blood CRP detection system without automatic Hct correction should be modified manually.