BACKGROUND:Mesenchymal stem cells are susceptible to senescence during in vitro expansion,which greatly hinders their application in vivo and in vitro.How to improve the replicative senescence of mesenchymal stem cells is an urgent problem to be solved in tissue engineering. OBJECTIVE:To determine whether vascular endothelial growth factor combined with basic fibroblast growth factor can improve the aging of bone marrow mesenchymal stem cells caused by replicative passage. METHODS:Rat bone marrow mesenchymal stem cells were extracted by whole bone marrow adhesion method.Passage 2 cells were selected as normal control group.Passage 7 and later algebraic cells were selected as aging model group.Vascular endothelial growth factor(50 μg/L),basic fibroblast growth factor(10 μg/L),and their combination were administered.Cell proliferation was detected by CCK-8 assay.Cell senescence was observed by β-galactosidase activity staining.Cytoskeleton size and colony formation ability were observed by phalloidine staining and Giemsa staining,respectively,and the levels of senescence-related genes P16,P21,and P53 were detected by qRT-PCR.Gene expression levels of P16,P21,and P53 were tested by qRT-PCR. RESULTS AND CONCLUSION:(1)Vascular endothelial growth factor combined with basic fibroblast growth factor could promote the proliferation of aged bone marrow mesenchymal stem cells,which began to enter the plateau stage on day 9,and the absorbance value of the combined intervention group was significantly higher than that of the model group on day 9(P<0.05).(2)The phenotypic markers of the cells in the combined intervention group did not change,and the cell morphology changed from broad to slender.(3)Compared with the model group,the positive rate of β-galactosidase was significantly decreased(P<0.01);the number of nuclei increased(P<0.001);the total area of cytoskeleton increased(P<0.01);colony formation ability was enhanced(P<0.05);expression level of P16 was decreased(P<0.01)in the combined intervention group.These results indicate that vascular endothelial growth factor combined with basic fibroblast growth factor can improve the senescence of bone marrow mesenchymal stem cells caused by replicative passage without changing the cell phenotype.

Different porous structures were studied through finite element analysis and then optimal porous structure was selected for the orthopedic applications.The optimal Voronoi structure was designed and fabricated using 3D printing.The mechanical properties and osseointegration ability were both investigated.The mechanical tests showed that the tensile strength,compressive strength and bending strength of Voronoi structures were obviously higher than that of the human bone,and the modulus of Voronoi structures were similar to human bone.In addition,the animal experimental results exhibited that obvious bone ingrowth was found from Month 1 to Month 6.This study provides some theoretical references for the orthopedic application of porous structures.

Transcatheter aortic valve replacement(TAVR)has become one of the effective methods for treating patients with aortic valve disease.With the continuous maturity of technology,innovation of instruments and increasing experience,the indications for TAVR has been expanded.Following international trends,the number of TAVR in China has steadily increased with each passing year.In 2023,the long-term follow-up results of TAVR in low-risk AS patients further confirm the long-term benefits of TAVR.The relevant research on TAVR for patients with aortic regurgitation and patients with bicuspid aortic stenosis provide evidence support for the expansion of TAVR indications.At the same time,the development of valve devices and new technological innovations are emerging in an endless stream,and the new concept of full life cycle management is increasingly being valued.Especially in China,the development of local devices is progressing rapidly,and multiple devices have entered the clinical research stage.The clinical manifestations and research results are worth pursuing.

Objective:To establish the rat cardiac arrest model in high-altitude hypobaric hypoxia environment, and to explore the effect of the treatment time in the hypobaric oxygen chamber on the reproduction of high-altitude rat cardiac arrest model.Methods:SPF grade healthy male Sprague-Dawley (SD) rats were used as observation subjects. The experiment was conducted in two different altitude areas. The rats from the Plateau Branch of Institute of Cardiopulmonary and Cerebral Resuscitation of Sun Yat-sen University (Xining, Qinghai) were weighed and numbered, and they were placed in a hypobaric oxygen chamber (simulated altitude of 3 000 meters, speed of ascent and descent of 15 m/min, temperature of 20 ℃, cabin pressure of 69.5 kPa, cabin oxygen pressure of 14.5 kPa). After 30 days of feeding, the rats were obtained according to random number table method, and the cardiac arrest model was established by asphyxia method as the 30-day hypobaric hypoxia group. After 60 days of feeding, rats were randomly selected again, and the cardiac arrest model was established as the 60-day hypobaric hypoxia group. Thirty rats were randomly selected from the Institute of Cardiopulmonary Cerebral Resuscitation at Sun Yat-sen University (Guangzhou, Guangdong) by the same method, and the cardiac arrest model was established as the plain control group. The differences in the body weight of rat modeling precursors and the induction time of asphyxia during the modeling process among different groups were compared.Results:Finally, cardiac arrest model was established in 16 rats in the 30-day hypobaric hypoxia group and in 22 rats in the 60-day hypobaric hypoxia group. There was no significant difference in the body weight of rats before modeling among the plain control group, 30-day hypobaric hypoxia group and 60-day hypobaric hypoxia group [g: 429.00 (389.25, 440.75), 440.00 (415.50, 486.25), 440.00 (400.00, 452.50), all P > 0.05]. The asphyxia induction time of rats in the 60-day hypobaric hypoxia group was significantly longer than that in the 30-day hypobaric hypoxia group (s: 294.59±75.39 vs. 234.31±93.86, P < 0.01), even about 1.4 times of the plain control group (s: 294.59±75.39 vs. 208.73±30.88, P < 0.01). There was no significant difference in the asphyxia induction time between the 30-day hypobaric hypoxia group and the plain control group ( P > 0.05). Conclusion:Rats treated in a hypobaric oxygen chamber for 60 days are more suitable for the preparation of high-altitude cardiac arrest model, and are also consistent with the oxygen reserve and hypoxia tolerance of high-altitude rats.

Objective To investigate the mechanism by which fragile X mental retardation protein(FMRP)regulates ferroptosis evasion in colorectal cancer(CRC)cells.Methods We examined FMRP expression levels in CRC cell lines using RT-qPCR and Western blotting and analyzed the biological functions and signaling pathways involved in FMRP-mediated regulation of CRC progression using the TCGA database.A lentiviral FMRP overexpression vector(Lv-FMRP)and 3 knockdown vectors(siFMRP-1,siFMRP-2,and siFMRP-3)were constructed,and their effects on proliferation of HCT116 cells were examined using CCK8 assay and plate clone formation assay;the changes in cell ferroptosis level was determined using MDA/ROS/GSH/Fe2+kits,mitochondrial membrane potential changes were detected using JC-1 fluorescence staining,and the expressions of proteins associated with ferroptosis and the RAS/MAPK signaling pathway were detected using Western blotting.The subcutaneous tumorigenic potential of the transfected cells was evaluated in nude mice.Results Compared with normal colonic mucosal epithelial NCM460 cells,the CRC cell lines had significantly higher FMRP expression level.Bioinformatics analysis suggested the involvement of FMRP in regulation of reactive oxygen,oxidative stress-induced cell death,mitochondrial respiration,and glutathione metabolism pathways.In the cell experiments,FMRP knockdown significantly inhibited proliferation of HCT116 cells,lowered cellular GSH content,increased MDA and ROS levels,Fe2+fluorescence intensity,and mitochondrial membrane potential,and decreased SLC7A11/GPX4 protein expressions and the phosphorylation levels of ERK,MEK,MAPK,and RAS proteins;FMRP overexpression resulted in the opposite changes in the cells.In the tumor-bearing nude mice,HCT116 cells with FMRP knockdown showed attenuated tumorigenic potential with lowered xenograft growth rate and reduced SLC7A11 expression in the xenograft.Conclusion The high expression of FMRP inhibits ferroptosis in CRC cells and promotes progression of CRC by activating the RAS/MAPK signaling pathway.

Celastrol and wilforlide A are the main active triterpenoids of the traditional Chinese medicine Lei Gong Teng, which have anti-tumour, anti-inflammatory and immunosuppressive activities, and are the material basis for the clinical efficacy of Lei Gong Teng-related Chinese medicinal preparations. By analysing the biosynthetic pathway of active ingredients, optimizing genetic elements and utilizing "cell factory" to produce triterpenoids heterologously will be an effective way to obtain from Tripterygium wilfordii in the future in a "low-cost and high-efficient" manner. CYP712Ks are the first cytochrome P450s involved in the skeleton modification of friedelane-type and oleanane-type triterpenoids in T. wilfordii, and they can catalyse the generation of polpunonic acid from friedelin and 3-epi-katonic acid from β-amyrin by carboxylation at C-29 position. In this study, four multifunctional TwCYP712K1/2/3/5 were used to clarify the catalytic function and substrate selection preference using in vivo functional characterization in Saccharomyces cerevisiae. The spatial structure of the protein-substrate binding was clarified through homology modeling and molecular docking, and then the differential amino acids in the active pocket of the protein were mutated to clarify the crucial amino acids determining the catalytic function and the selection of substrate structure. A total of 63 mutant elements were constructed, and the amino acid sites affecting the carboxylation function of TwCYP712Ks were analyzed. In particular, the key amino acids affecting the substrate selectivity of TwCYP712K2 towards oleanane-type and friedelane-type triterpenoids were revealed and the TwCYP712K2^F127I and TwCYP712K2^A227T mutants would result in a reversal of the product ratio. In conclusion, four proteins of TwCYP712Ks were semi-rationally designed by homologous protein alignment and mutual mutation to elucidate multiple amino acid sites determining the catalytic function of the proteins, and a series of activity-enhancing or altering mutants were obtained, which provide abundant catalytic elements for the biosynthesis of active triterpenoids from T. wilfordii, and the mechanism of carboxylation in the C-29 position was initially elucidated.

Objective To estimate adolescents and children age using stepwise regression and machine learning methods based on the pulp and tooth volumes of the left maxillary central incisor and cuspid on cone beam computed tomography(CBCT)images,and to compare and analyze the estimation re-sults.Methods A total of 498 Shanghai Han adolescents and children CBCT images of the oral and maxillofacial regions were collected.The pulp and tooth volumes of the left maxillary central incisor and cuspid were measured and calculated.Three machine learning algorithms(K-nearest neighbor,ridge regression,and decision tree)and stepwise regression were used to establish four age estimation models.The coefficient of determination,mean error,root mean square error,mean square error and mean ab-solute error were computed and compared.A correlation heatmap was drawn to visualize and the monotonic relationship between parameters was visually analyzed.Results The K-nearest neighbor model(R2=0.779)and the ridge regression model(R2=0.729)outperformed stepwise regression(R2=0.617),while the decision tree model(R2=0.494)showed poor fitting.The correlation heatmap demon-strated a monotonically negative correlation between age and the parameters including pulp volume,the ratio of pulp volume to hard tissue volume,and the ratio of pulp volume to tooth volume.Con-clusion Pulp volume and pulp volume proportion are closely related to age.The application of CBCT-based machine learning methods can provide more accurate age estimation results,which lays a founda-tion for further CBCT-based deep learning dental age estimation research.

Objective To investigate the clinical characteristics and prognosis of pneumococcal meningitis(PM),and drug sensitivity of Streptococcus pneumoniae(SP)isolates in Chinese children.Methods A retrospective analysis was conducted on clinical information,laboratory data,and microbiological data of 160 hospitalized children under 15 years old with PM from January 2019 to December 2020 in 33 tertiary hospitals across the country.Results Among the 160 children with PM,there were 103 males and 57 females.The age ranged from 15 days to 15 years,with 109 cases(68.1% )aged 3 months to under 3 years.SP strains were isolated from 95 cases(59.4% )in cerebrospinal fluid cultures and from 57 cases(35.6% )in blood cultures.The positive rates of SP detection by cerebrospinal fluid metagenomic next-generation sequencing and cerebrospinal fluid SP antigen testing were 40% (35/87)and 27% (21/78),respectively.Fifty-five cases(34.4% )had one or more risk factors for purulent meningitis,113 cases(70.6% )had one or more extra-cranial infectious foci,and 18 cases(11.3% )had underlying diseases.The most common clinical symptoms were fever(147 cases,91.9% ),followed by lethargy(98 cases,61.3% )and vomiting(61 cases,38.1% ).Sixty-nine cases(43.1% )experienced intracranial complications during hospitalization,with subdural effusion and/or empyema being the most common complication[43 cases(26.9% )],followed by hydrocephalus in 24 cases(15.0% ),brain abscess in 23 cases(14.4% ),and cerebral hemorrhage in 8 cases(5.0% ).Subdural effusion and/or empyema and hydrocephalus mainly occurred in children under 1 year old,with rates of 91% (39/43)and 83% (20/24),respectively.SP strains exhibited complete sensitivity to vancomycin(100% ,75/75),linezolid(100% ,56/56),and meropenem(100% ,6/6).High sensitivity rates were also observed for levofloxacin(81% ,22/27),moxifloxacin(82% ,14/17),rifampicin(96% ,25/26),and chloramphenicol(91% ,21/23).However,low sensitivity rates were found for penicillin(16% ,11/68)and clindamycin(6% ,1/17),and SP strains were completely resistant to erythromycin(100% ,31/31).The rates of discharge with cure and improvement were 22.5% (36/160)and 66.2% (106/160),respectively,while 18 cases(11.3% )had adverse outcomes.Conclusions Pediatric PM is more common in children aged 3 months to under 3 years.Intracranial complications are more frequently observed in children under 1 year old.Fever is the most common clinical manifestation of PM,and subdural effusion/emphysema and hydrocephalus are the most frequent complications.Non-culture detection methods for cerebrospinal fluid can improve pathogen detection rates.Adverse outcomes can be noted in more than 10% of PM cases.SP strains are high sensitivity to vancomycin,linezolid,meropenem,levofloxacin,moxifloxacin,rifampicin,and chloramphenicol.[Chinese Journal of Contemporary Pediatrics,2024,26(2):131-138]

Objective To investigate the prevalence of tension-type headache(TTH)in children and adolescents aged 0-19 years globally in 1990-2021,and to provide a basis for the prevention and treatment of TTH.Methods Based on the Global Burden of Disease Study data,the age-standardized prevalence distribution of TTH and its changing trend were analyzed among the children and adolescents aged 0-19 years,with different sexes,age groups,sociodemographic index(SDI)regions and countries/territories.Results The age-standardized prevalence rate(ASPR)of TTH in children and adolescents aged 0-19 globally in 2021 was 17 339.89/100 000,which was increased by 1.73%since 1990.The ASPR in females was slightly higher than that in males(1990:17 707.65/100 000 vs 16 403.78/100 000;2021:17 946.29/100 000 vs 16 763.09/100 000).The ASPR in adolescence was significantly higher than that in school-aged and preschool periods(1990:27 672.04/100 000 vs 10 134.16/100 000;2021:28 239.04/100 000 vs 10 059.39/100 000).Regions with high SDI exhibited a higher ASPR than the other regions,with significant differences in prevalence rates across different countries.From 1990 to 2021,there was a slight increase in global ASPR,with an average annual percentage change(AAPC)of 0.06%.Females experienced a smaller increase than males based on AAPC(0.04%vs 0.07%).There was reduction in ASPR in preschool and school-aged groups,with an AAPC of-0.02%,while there was a significant increase in ASPR in adolescence,with an AAPC of 0.07%.ASPR decreased in regions with low-middle and low levels of SDI,with an AAPC of-0.02%and-0.04%,respectively,while it increased in regions with middle SDI,with an AAPC of 0.24%.Conclusions There is a consistent increase in the ASPR of TTH in children and adolescents aged 0-19 years globally,with significant differences across sexes,age groups,SDI regions and countries/territories.

Objective To understand the change in distribution and antimicrobial resistance of bacteria isolated from blood specimens of Hunan Province,and provide for the initial diagnosis and treatment of clinical bloodstream infection(BSI).Methods Data reported from member units of Hunan Province Antimicrobial Resistance Survei-llance System from 2012 to 2021 were collected.Bacterial antimicrobial resistance surveillance method was imple-mented according to the technical scheme of China Antimicrobial Resistance Surveillance System(CARSS).Bacteria from blood specimens and bacterial antimicrobial susceptibility testing results were analyzed by WHONET 5.6 soft-ware and SPSS 27.0 software.Results A total of 207 054 bacterial strains were isolated from blood specimens from member units in Hunan Province Antimicrobial Resistance Surveillance System from 2012 to 2021,including 107 135(51.7％)Gram-positive bacteria and 99 919(48.3％)Gram-negative bacteria.There was no change in the top 6 pathogenic bacteria from 2012 to 2021,with Escherichia coli(n=51 537,24.9％)ranking first,followed by Staphylococcus epidermidis(n=29 115,14.1％),Staphylococcus aureus(n=17 402,8.4％),Klebsiella pneu-moniae(17 325,8.4％),Pseudomonas aeruginosa(n=4 010,1.9％)and Acinetobacter baumannii(n=3 598,1.7％).The detection rate of methicillin-resistant Staphylococcus aureus(MRSA)decreased from 30.3％in 2015 to 20.7％in 2021,while the detection rate of methicillin-resistant coagulase-negative Staphylococcus(MRCNS)showed an upward trend year by year(57.9％-66.8％).No Staphylococcus was found to be resistant to vancomy-cin,linezolid,and teicoplanin.Among Gram-negative bacteria,constituent ratios of Escherichia coli and Klebsiella pneumoniae were 43.9％-53.9％and 14.2％-19.5％,respectively,both showing an upward trend(both P＜0.001).Constituent ratios of Pseudomonas aeruginosa and Acinetobacter baumannii were 3.6％-5.1％and 3.0％-4.5％,respectively,both showing a downward trend year by year(both P＜0.001).From 2012 to 2021,resistance rates of Escherichia coli to imipenem and ertapenem were 1.0％-2.0％and 0.6％-1.1％,respectively;presenting a downward trend(P＜0.001).The resistant rates of Klebsiella pneumoniae to meropenem and ertapenem were 7.4％-13.7％and 4.8％-6.4％,respectively,presenting a downward trend(both P＜0.001).The resistance rates of Pseudomonas aeruginosa and Acinetobacter baumannii to carbapenem antibiotics were 7.1％-15.6％and 34.7％-45.7％,respectively.The trend of resistance to carbapenem antibiotics was relatively stable,but has de-creased compared with 2012-2016.The resistance rates of Escherichia coli to the third-generation cephalosporins from 2012 to 2021 were 41.0％-65.4％,showing a downward trend year by year.Conclusion The constituent ra-tio of Gram-negative bacillus from blood specimens in Hunan Province has been increasing year by year,while the detection rate of carbapenem-resistant Gram-negative bacillus remained relatively stable in the past 5 years,and the detection rate of coagulase-negative Staphylococcus has shown a downward trend.