BACKGROUND:The imbalance between bone resorption and bone formation in microgravity environments leads to significant bone loss in astronauts.Current research indicates that bone loss under microgravity conditions is the result of the combined effects of various cells,tissues,and systems. OBJECTIVE:To review different biological effects of microgravity on various cells,tissues,or systems,and summarize the mechanisms by which microgravity leads to the development of osteoporosis. METHODS:Databases such as PubMed,Web of Science,and the Cochrane Database were searched for relevant literature from 2000 to 2023.The inclusion criteria were all articles related to tissue engineering studies and basic research on osteoporosis caused by microgravity.Ultimately,85 articles were included for review. RESULTS AND CONCLUSION:(1)In microgravity environment,bone marrow mesenchymal stem cells tend to differentiate more into adipocytes rather than osteoblasts,and hematopoietic stem cells in this environment are more inclined to differentiate into osteoclasts,reducing differentiation into the erythroid lineage.At the same time,microgravity inhibits the proliferation and differentiation of osteoblasts,promotes apoptosis of osteoblasts,alters cell morphology,and reduces the mineralization capacity of osteoblasts.Microgravity significantly increases the number and activity of osteoclasts.Microgravity also hinders the differentiation of osteoblasts into osteocytes and promotes the apoptosis of osteocytes.(2)In a microgravity environment,the body experiences changes such as skeletal muscle atrophy,microvascular remodeling,bone microcirculation disorders,and endocrine disruption.These changes lead to mechanical unloading in the bone microenvironment,insufficient blood perfusion,and calcium cycle disorders,which significantly impact the development of osteoporosis.(3)At present,the mechanism by which microgravity causes osteoporosis is relatively complex.A deeper study of these physiological mechanisms is crucial to ensuring the health of astronauts during long-term space missions,and provides a theoretical basis for the prevention and treatment of osteoporosis.

[摘 要] 目的：探究长链非编码RNA（lncRNA）小核仁RNA宿主基因14（SNHG14）靶向miR-579-3p/富含半胱氨酸的酸性分泌蛋白（SPARC）对肝细胞癌（HCC）细胞恶性生物学行为的影响。方法：常规培养人正常肝细胞（LO2）和HCC细胞Huh7、Hep3B、HepG2，将Huh7细胞随机分为对照组、sh-NC组、sh-SNHG14组、sh-SNHG14 + anti-NC组和sh-SNHG14 + anti-miR-579-3p组，qPCR法检测细胞中SNHG14、miR-579-3p和SPARC mRNA的表达水平，双萤光素酶报告基因实验验证SNHG14与miR-579-3p及miR-579-3p与SPARC调控关系，MTT法、划痕愈合实验、Transwell实验、流式细胞术，以及WB法分别检测各组Huh7细胞的增殖、迁移、侵袭能力、凋亡，以及Huh7细胞中PCNA、E-cadherin、vimentin、SPARC蛋白的表达。结果：在HCC细胞中SNHG14、SPARC mRNA呈高表达、miR-579-3p呈低表达（均P < 0.05）；SNHG14与miR-579-3p和miR-579-3p与SPARC mRNA间存在直接结合调控关系（均P < 0.05）。敲减SNHG14可明显抑制Huh7细胞的增殖、迁移、侵袭、PCNA、vimentin、SPARC mRNA及蛋白的表达（均P < 0.05），促进细胞凋亡、miR-579-3p和E-cadherin表达（均P < 0.05）；抑制miR-579-3p则可部分逆转敲减SNHG14对Huh7细胞的作用（均P < 0.05）。结论：敲减SNHG14可通过靶向miR-579-3p/SPARC轴抑制Huh7细胞的恶性生物学行为，促进其凋亡；SNHG14和miR-579-3p/SPARC轴可能是HCC治疗的潜在靶点。

Alzheimer's disease (AD) is a leading cause of dementia in the elderly. Mitogen-activated protein kinase phosphatase 1 (MKP-1) plays a neuroprotective role in AD. However, the molecular mechanisms underlying the effects of MKP-1 on AD have not been extensively studied. MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level, thereby repressing mRNA translation. Here, we reported that the microRNA-429-3p (miR-429-3p) was significantly increased in the brain of APP23/PS45 AD model mice and N2A^APP AD model cells. We further found that miR-429-3p could downregulate MKP-1 expression by directly binding to its 3'-untranslated region (3' UTR). Inhibition of miR-429-3p by its antagomir (A-miR-429) restored the expression of MKP-1 to a control level and consequently reduced the amyloidogenic processing of APP and Aβ accumulation. More importantly, intranasal administration of A-miR-429 successfully ameliorated the deficits of hippocampal CA1 long-term potentiation and spatial learning and memory in AD model mice by suppressing extracellular signal-regulated kinase (ERK1/2)-mediated GluA1 hyperphosphorylation at Ser831 site, thereby increasing the surface expression of GluA1-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). Together, these results demonstrate that inhibiting miR-429-3p to upregulate MKP-1 effectively improves cognitive and synaptic functions in AD model mice, suggesting that miR-429/MKP-1 pathway may be a novel therapeutic target for AD treatment.

Objective:To study the current status of longitudinal extrauterine growth restriction (EUGR) in extremely preterm infants (EPIs) and to develop a prediction model based on clinical data from multiple NICUs.Methods:From January 2017 to December 2018, EPIs admitted to 32 NICUs in North China were retrospectively studied. Their general conditions, nutritional support, complications during hospitalization and weight changes were reviewed. Weight loss between birth and discharge > 1SD was defined as longitudinal EUGR. The EPIs were assigned into longitudinal EUGR group and non-EUGR group and their nutritional support and weight changes were compared. The EPIs were randomly assigned into the training dataset and the validation dataset with a ratio of 7∶3. Univariate Cox regression analysis and multiple regression analysis were used in the training dataset to select the independent predictive factors. The best-fitting Nomogram model predicting longitudinal EUGR was established based on Akaike Information Criterion. The model was evaluated for discrimination efficacy, calibration and clinical decision curve analysis.Results:A total of 436 EPIs were included in this study, with a mean gestational age of (26.9±0.9) weeks and a birth weight of (989±171) g. The incidence of longitudinal EUGR was 82.3%(359/436). Seven variables (birth weight Z-score, weight loss, weight growth velocity, the proportion of breast milk ≥75% within 3 d before discharge, invasive mechanical ventilation ≥7 d, maternal antenatal corticosteroids use and bronchopulmonary dysplasia) were selected to establish the prediction model. The area under the receiver operating characteristic curve of the training dataset and the validation dataset were 0.870 (95% CI 0.820-0.920) and 0.879 (95% CI 0.815-0.942), suggesting good discrimination efficacy. The calibration curve indicated a good fit of the model ( P>0.05). The decision curve analysis showed positive net benefits at all thresholds. Conclusions:Currently, EPIs have a high incidence of longitudinal EUGR. The prediction model is helpful for early identification and intervention for EPIs with higher risks of longitudinal EUGR. It is necessary to expand the sample size and conduct prospective studies to optimize and validate the prediction model in the future.

Objective To explore the efficacy and safety of ticagrelor de-escalation and nicorandil therapy in elderly patients with acute coronary syndrome(ACS)after percutaneous coronary intervention(PCI).Methods A total of 300 elderly patients with ACS were selected from the Sixth and Seventh Medical Center of Chinese PLA General Hospital and Beijing Chaoyang Integrative Medicine Emergency Rescue and First Aid Hospital from November 2016 to June 2019,including 153 males and 147 females,aged>65 years old.All the patients received PCI,and all had double antiplatelet therapy(DAPT)scores≥2 and a new DAPT(PRECISE-DAPT)score of≥25.All patients were divided into two groups by random number table method before operation:ticagrelor group(n=146,ticagrelor 180 mg load dose followed by PCI,and ticagrelor 90 mg bid after surgery)and ticagrelor de-escalation + nicorandil group(n=154,ticagrelor 180 mg load dose followed by PCI,ticagrelor 90 mg bid+nicorandil 5 mg tid after surgery,changed to ticagrelor 60 mg bid+ nicorandil 5 mg tid 6 months later).Follow-up was 12 months.The composite end points of cardiovascular death,myocardial infarction and stroke,the composite end points of mild hemorrhage,minor hemorrhage,other major hemorrhage and major fatal/life-threatening hemorrhage as defined by the PLATO study,and the composite end points of cardiovascular death,myocardial infarction,stroke and bleeding within 12 months in the two groups were observed.Results The comparison of general baseline data between the two groups showed no statistically significant difference(P>0.05).There was also no significant difference in the composite end points of cardiovascular death,myocardial infarction and stroke between the two groups(P>0.05).The cumulative incidence of bleeding events in ticagrelor de-escalation + nicorandil group was significantly lower than that in ticagrelor group(P<0.05),while the composite end points of cardiovascular death,myocardial infarction,stroke and bleeding were also significantly lower than those in tecagrelor group(P<0.05).Conclusion In elderly patients with ACS,the treatment of ticagrelor de-escalation + nicorandil after PCI may not increase the incidence of ischemic events such as cardiovascular death,myocardial infarction or stroke,and it may reduce the incidence of hemorrhagic events.

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of national bloodstream infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:During the study period，9 035 strains of Gram-negative bacteria were collected from 51 hospitals，of which 7 895（87.4%）were Enterobacteriaceae and 1 140（12.6%）were non-fermenting bacteria. The top 5 bacterial species were Escherichia coli（ n=4 510，49.9%）， Klebsiella pneumoniae（ n=2 340，25.9%）， Pseudomonas aeruginosa（ n=534，5.9%）， Acinetobacter baumannii complex（ n=405，4.5%）and Enterobacter cloacae（ n=327，3.6%）. The ESBLs-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus spp. were 47.1%（2 095/4 452），21.0%（427/2 033）and 41.1%（58/141），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（58/4 510）and 13.1%（307/2 340）；62.1%（36/58）and 9.8%（30/307）of CREC and CRKP were resistant to ceftazidime/avibactam combination，respectively. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 59.5%（241/405），while less than 5% of Acinetobacter baumannii complex was resistant to tigecycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 18.4%（98/534）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of main Gram-negative bacteria resistance among different regions，with statistically significant differences in the prevalence of CRKP and CRPA（ χ2=20.489 and 20.252， P<0.001）. The prevalence of CREC，CRKP，CRPA，CRAB，ESBLs-producing Escherichia coli and Klebsiella pneumoniae were higher in provinicial hospitals than those in municipal hospitals（ χ2=11.953，81.183，10.404，5.915，12.415 and 6.459， P<0.01 or <0.05），while the prevalence of CRPA was higher in economically developed regions（per capita GDP ≥ 92 059 Yuan）than that in economically less-developed regions（per capita GDP <92 059 Yuan）（ χ2=6.240， P=0.012）. Conclusions:The proportion of Gram-negative bacteria in bloodstream infections shows an increasing trend，and Escherichia coli is ranked in the top，while the trend of CRKP decreases continuously with time. Decreasing trends are noted in ESBLs-producing Escherichia coli and Klebsiella pneumoniae. Low prevalence of carbapenem resistance in Escherichia coli and high prevalence in CRAB complex have been observed. The composition ratio and antibacterial spectrum of bloodstream infections in different regions of China are slightly different，and the proportion of main drug resistant bacteria in provincial hospitals is higher than those in municipal hospitals.

Background Pesticide exposure may impact the reproductive health of women undergoing assisted reproductive technology (ART). However, data on pesticide exposure levels in women undergoing ART in China are scarce, and current research on influencing factors is limited. Objective To evaluate the preconceptional pesticide exposure levels and identify potential determinants among women undergoing ART. Methods This study was designed as a cross-sectional survey and recruited 508 women undergoing ART from July 2017 to December 2018 at the fertility clinic of the International Peace Maternity and Child Health Hospital Affiliated to Shanghai Jiao Tong University School of Medicine. Gas chromatography/liquid chromatography-tandem mass spectrometry was used to determine the metabolite concentrations of organophosphate pesticides (OPs), pyrethroid pesticides (PYRs), and neonicotinoid pesticides (NEOs) in urine. The sum of molar concentrations of the three pesticide classes (∑₂OPs, ∑₂PYRs, and ∑₂NEOs) were calculated. A questionnaire was used to collect demographic characteristics, dietary habits, and behavioral information. Multiple linear regression was employed to analyze the associations of demographic characteristics, dietary habits, and behavioral variables with the concentrations of pesticide metabolites in urine among the participants. Results The median creatinine-adjusted concentrations of ∑₂OPs, ∑₂PYRs, and ∑₂NEOs in this study were 419.77, 2.95, and 20.36 nmol·g⁻¹, respectively. The multiple linear regression results showed that the urinary concentration of ∑₂OPs was 42.88% higher in the participants with daily vegetable intake than in those who consumed vegetables ≤3 d per week (P<0.05), and the urinary concentration of ∑₂PYRs was 37.24% higher in the participants with daily fruit intake than in those who consumed fruits ≤3 d per week (P<0.01). Similarly, the urinary concentrations of ∑₂NEOs were 24.51% and 29.30% higher in the participants who consumed fruits daily and 4-6 d per week, respectively, than in those who consumed fruits ≤3 d per week (P<0.05). Besides, we also found that the urinary concentration of ∑₂PYRs was negatively correlated with body mass index (BMI) in the participants (P<0.05). Furthermore, the urinary concentration of ∑₂NEOs was not only positively correlated with age (P<0.05), but also significantly associated with pet ownership and infertility causes among the participants. Specifically, the participants who continued to own pets after conception had a 30.11% higher urinary concentration of ∑₂NEOs than those who never owned pets (P<0.05), and the participants with infertility due to female factors had a 24.10% lower urinary concentration of ∑₂NEOs than those who received ART treatment for infertility caused by male factors (P<0.05). Conclusion The women undergoing ART in Shanghai are widely exposed to pesticides. Age, BMI, frequency of vegetable and fruit intake, pet ownership, and infertility causes may be related to the pesticide exposure levels in this population. However, more human data are needed to confirm these findings.

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-positive bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-positive bacteria from blood cultures in member hospitals of National Bloodstream Infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:A total of 3 163 strains of Gram-positive pathogens were collected from 51 member units，and the top five bacteria were Staphylococcus aureus（ n=1 147，36.3%），coagulase-negative Staphylococci（ n=928，29.3%）， Enterococcus faecalis（ n=369，11.7%）， Enterococcus faecium（ n=296，9.4%）and alpha-hemolyticus Streptococci（ n=192，6.1%）. The detection rates of methicillin-resistant Staphylococcus aureus（MRSA）and methicillin-resistant coagulase-negative Staphylococci（MRCNS）were 26.4%（303/1 147）and 66.7%（619/928），respectively. No glycopeptide and daptomycin-resistant Staphylococci were detected. The sensitivity rates of Staphylococcus aureus to cefpirome，rifampin，compound sulfamethoxazole，linezolid，minocycline and tigecycline were all >95.0%. Enterococcus faecium was more prevalent than Enterococcus faecalis. The resistance rates of Enterococcus faecium to vancomycin and teicoplanin were both 0.5%（2/369），and no vancomycin-resistant Enterococcus faecium was detected. The detection rate of MRSA in southern China was significantly lower than that in other regions（ χ2=14.578， P=0.002），while the detection rate of MRCNS in northern China was significantly higher than that in other regions（ χ2=15.195， P=0.002）. The detection rates of MRSA and MRCNS in provincial hospitals were higher than those in municipal hospitals（ χ2=13.519 and 12.136， P<0.001）. The detection rates of MRSA and MRCNS in economically more advanced regions（per capita GDP≥92 059 Yuan in 2022）were higher than those in economically less advanced regions（per capita GDP<92 059 Yuan）（ χ2=9.969 and 7.606， P=0.002和0.006）. Conclusions:Among the Gram-positive pathogens causing bloodstream infections in China， Staphylococci is the most common while the MRSA incidence decreases continuously with time；the detection rate of Enterococcus faecium exceeds that of Enterococcus faecalis. The overall prevalence of vancomycin-resistant Enterococci is still at a low level. The composition ratio of Gram-positive pathogens and resistant profiles varies slightly across regions of China，with the prevalence of MRSA and MRCNS being more pronounced in provincial hospitals and areas with a per capita GDP≥92 059 yuan.

Objective:To understand the epidemiological characteristics of human respiratory syncytial virus (HRSV) among acute respiratory infection (ARI) cases in 16 provinces of China from 2009 to 2023.Methods:The data of this study were collected from the ARI surveillance data from 16 provinces in China from 2009 to 2023, with a total of 28 278 ARI cases included in the study. The clinical specimens from ARI cases were screened for HRSV nucleic acid from 2009 to 2023, and differences in virus detection rates among cases of different age groups, regions, and months were analyzed.Results:A total of 28 278 ARI cases were enrolled from January 2009 to September 2023. The age of the cases ranged from<1 month to 112 years, and the age M ( Q1, Q3) was 3 years (1 year, 9 years). Among them, 3 062 cases were positive for HRSV nucleic acid, with a total detection rate of 10.83%. From 2009 to 2019, the detection rate of HRSV was 9.33%, and the virus was mainly prevalent in winter and spring. During the Corona Virus Disease 2019 (COVID-19) pandemic, the detection rate of HRSV fluctuated between 6.32% and 18.67%. There was no traditional winter epidemic peak of HRSV from the end of 2022 to the beginning of 2023, and an anti-seasonal epidemic of HRSV occurred from April to May 2023. About 87.95% (2 693/3 062) of positive cases were children under 5 years old, and the difference in the detection rate of HRSV among different age groups was statistically significant ( P<0.001), showing a decreasing trend of HRSV detection rate with the increase of age ( P<0.001). Among them, the HRSV detection rate (25.69%) was highest in children under 6 months. Compared with 2009-2019, the ranking of HRSV detection rates in different age groups changed from high to low between 2020 and 2023, with the age M (Q1, Q3) of HRSV positive cases increasing from 1 year (6 months, 3 years) to 2 years (11 months, 3 years). Conclusion:Through 15 years of continuous HRSV surveillance analysis, children under 5 years old, especially infants under 6 months old, are the main high-risk population for HRSV infection. During the COVID-19 pandemic, the prevalence and patterns of HRSV in China have changed.

Objective:To evaluate the effects of fine particle matter(PM2.5)and ozone(O3)com-bined exposure on adenosine triphosphate(ATP)amount and ATPase activities in nasal mucosa of Spra-gue Dawley(SD)rats.Methods:Twenty male SD rats were divided into control group(n=10)and exposure group(n=10)by random number table method.The rats were fed in the conventional clean environment and the air pollutant exposure system established by our team,respectively,and exposed for 208 d.During the exposure period,the concentrations of PM2 5 and O3 in the exposure system were moni-tored,and a comprehensive assessment of PM2 5 and O3 in the exposure system was conducted by combi-ning self-measurement and site data.On the 208 d of exposure,the core,liver,spleen,kidney,testis and other major organs and nasal mucosal tissues of the rats were harvested.Each organ was weighed and the organ coefficient calculated.The total amount of ATP was measured by bioluminescence,and the ac-tivities of Na+-K+-ATPase and Ca2+-ATPase were detected by spectrophotometry.The t test of two inde-pendent samples was used to compare the differences among the indicator groups.Results:From the 3rd week to the end of exposure duration,the body weight of the rats in the exposure group was higher than that in the control group(P＜0.05),and there was no significant difference in organ coefficients be-tween the two groups.The average daily PM2 5 concentration in the exposure group was(30.68±19.23)μg/m3,and the maximum 8 h ozone concentration(O3-8 h)was(82.45±35.81)μg/m3.The chemi-luminescence value(792.4±274.1)IU/L of ATP in nasal mucosa of the rats in the exposure group was lower than that in the control group(1 126.8±218.1)IU/L.The Na+-K+-ATPase activity(1.53±0.85)U/mg in nasal mucosa of the rats in the exposure group was lower than that in the control group(4.31±1.60)U/mg(P＜0.05).The protein content of nasal mucosa in the control group and the exposure group were(302.14±52.51)mg/L and(234.58±53.49)mg/L,respectively,and the ac-tivity of Ca2+-ATPase was(0.81±0.27)U/mg and(0.99±0.73)U/mg,respectively.There was no significant difference between the groups.Conclusion:The ability of power capacity decreased in the rat nasal mucossa under the sub-chronic low-concentration exposure of PM2 5 and O3.