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.

BACKGROUND:The extracellular-regulated protein kinase 5(ERK5)signaling protein is essential for the survival of organisms,and resveratrol can promote osteoblast proliferation through various pathways.However,whether resveratrol can regulate osteoblast function through the ERK5 signaling protein needs further verification. OBJECTIVE:To explore the regulatory effect of ERK5 on the proliferation of MC3T3-E1 cells and related secreted proteins,and to further verify whether resveratrol can complete the above process by activating ERK5. METHODS:Mouse MC3T3-E1 preosteoblasts were treated with complete culture medium,XMD8-92(an ERK5 inhibitor),epidermal growth factor(an ERK5 activator),resveratrol alone,XMD8-92+EGF,and resveratrol+XMD8-92,respectively.Western blot assay was used to detect the expression of ERK5 and p-ERK5 proteins,proliferation-related proteins Cyclin D1,CDK4 and PCNA,and osteoblast-secreted proteins osteoprotegerin and receptor activator of nuclear factor-κB ligand in MC3T3-E1 cells of each group.The fluorescence intensity of ERK5,osteoprotegerin and receptor activator of nuclear factor-κB ligand in each group was detected by cell immunofluorescence staining,and cell proliferation was detected by EdU staining,respectively.The appropriate concentration and time of resveratrol intervention in MC3T3-E1 cells were determined by cell morphology observation and cell counting kit-8 assay. RESULTS AND CONCLUSION:The activation of ERK5 signaling protein could effectively promote the proliferation of MC3T3-E1 cells,up-regulate the osteoprotegerin/receptor activator of nuclear factor-κB ligand ratio.The appropriate concentration and time for resveratrol intervention in MC3T3-E1 cells was 5 μmol/L and 24 hours,respectively.Resveratrol could activate ERK5 signaling protein,thereby promoting osteoblast proliferation and up-regulating the osteoprotegerin/RANKL ratio.All these results indicate that resveratrol can promote the proliferation of MC3T3-E1 cells and up-regulate the osteoprotegerin/RANKL ratio by activating the ERK5 signaling protein.

Objective:To evaluate the efficacy of ultrasound-guided median interspinous in-plane approach to subarachnoid puncture in obese pregnant patients.Methods:This study was a randomized controlled trial. Eighty obese parturients who underwent elective cesarean section from March 2022 to January 2024 in our hospital were divided into 2 groups( n=40 each) by the random number table method: median interspinous in-plane approach group(group M) and paramedian interlaminar in-plane approach group(group P). After successful puncture, 0.5% ropivacaine 15 mg(3 ml) was intrathecally injected in both groups. The first-attempt success of puncture, the number of puncture attempts, operation time, the total success of puncture, and the visibility scores of the anterior and posterior union, positioning structure(lamina in group P, spinous process in group M) and puncture needle under ultrasound were recorded. Results:Compared with group P, the visibility score of positioning structure under ultrasound was significantly increased, the success rate of puncture at the first attempt was increased, the number of puncture attempts was decreased, the operation time was shortened, the total success rate of puncture was increased( P<0.05), and no significant change was found in the visibility scores of the anterior and posterior union and puncture needle in group M( P>0.05). Conclusions:For obese pregnant patients, the ultrasound-guided median interspinous in-plane approach can accurately and quickly perform subarachnoid puncture, which has more advantages than the traditional paramedian interlaminar in-plane approach.

Objective:To evaluate the efficacy of ultrasound-guided median interspinous in-plane approach to subarachnoid puncture in obese pregnant patients.Methods:This study was a randomized controlled trial. Eighty obese parturients who underwent elective cesarean section from March 2022 to January 2024 in our hospital were divided into 2 groups( n=40 each) by the random number table method: median interspinous in-plane approach group(group M) and paramedian interlaminar in-plane approach group(group P). After successful puncture, 0.5% ropivacaine 15 mg(3 ml) was intrathecally injected in both groups. The first-attempt success of puncture, the number of puncture attempts, operation time, the total success of puncture, and the visibility scores of the anterior and posterior union, positioning structure(lamina in group P, spinous process in group M) and puncture needle under ultrasound were recorded. Results:Compared with group P, the visibility score of positioning structure under ultrasound was significantly increased, the success rate of puncture at the first attempt was increased, the number of puncture attempts was decreased, the operation time was shortened, the total success rate of puncture was increased( P<0.05), and no significant change was found in the visibility scores of the anterior and posterior union and puncture needle in group M( P>0.05). Conclusions:For obese pregnant patients, the ultrasound-guided median interspinous in-plane approach can accurately and quickly perform subarachnoid puncture, which has more advantages than the traditional paramedian interlaminar in-plane approach.

BACKGROUND:Fluid shear stress plays an important role in osteoblast proliferation and apoptosis.However,whether Caveolin-1 is involved in the process of fluid shear stress-induced proliferation and apoptosis in osteoblasts is unknown. OBJECTIVE:To explore the role of Caveolin-1 in fluid shear stress-regulated osteoblast proliferation and apoptosis. METHODS:The MC3T3-E1 osteoblasts in good growth status were selected and loaded with fluid shear stress at an intensity of 1.2 Pa for different times(0,30,60,90 minutes).The expression of Caveolin-1 protein was observed and conditions with a time of 60 minutes were screened for the experiment.MC3T3-E1 cells were divided into control group,fluid shear stress group,fluid shear stress+pcDNA 3.1 group(control),fluid shear stress+pcDNA Cav-1 group(plasmid overexpression),and intervened with fluid shear stress and overexpression of Cav-1,respectively.The expression of molecules related to proliferation and apoptosis in MC3T3-E1 cells was detected by qRT-PCR and western blot.In addition,the proliferative activity of MC3T3-E1 cells was detected by cell counting kit-8 and EdU assay;and cell apoptosis was detected by Hoechst 33258 and flow cytometry. RESULTS AND CONCLUSION:The expression of Caveolin-1 in MC3T3-E1 cells was significantly down-regulated after loading fluid shear stress,and the expression level was lowest after 60 minutes.Overexpression of Caveolin-1 attenuated the proliferation-promoting and apoptosis-suppressing effects of fluid shear stress in MC3T3-E1 cells.In conclusion,Caveolin-1 has a vital role in fluid shear stress-regulated osteoblast proliferation and apoptosis,which may offer a potential therapeutic strategy for osteoporosis.

Objectives:To examine the feasibility of using foundation model in computer vision for echocardiographic left ventricular ejection fraction measurement. Methods:Based on the most extensive publicly accessible repository of echocardiographic loops,EchoNet-Dynamic,featuring 10024 recordings from individual patients,a foundation model in computer vision,VideoMAE V2,was fine-tuned,validated,tested using 7460,1288,and 1276 echocardiographic loops,respectively. Results:The mean absolute error between left ventricular ejection fraction measurements of VideoMAE V2 and expert's measurements was 3.94％ (95％CI:3.79％-4.11％).The Pearson's correlation coefficient was 0.91 (95％CI:0.89-0.92).Additionally,VideoMAE V2 demonstrated exceptional accuracy in identifying patients with a left ventricular ejection fraction below 50％,achieving an AUC of 0.96 (95％CI:0.95-0.97). Conclusions:This study validates the feasibility of using foundation model in computer vision for measuring left ventricular ejection fraction in echocardiographic loops and lays the foundation for the development of a generalized multimodal automated interpretation system for echocardiography.

Objective:To evaluate the role of the sodium leak channel (NALCN) in the hippocampal dentate gyrus (DG) in the social behavior of mice.Methods:Thirty-nine male wild-type C57BL/6 mice, aged 6-8 weeks, weighing 18-22 g, were used in this study. Three mice were sacrificed to verify the expression and co-expression of NALCN with neuronal nuclear antigen (NeuN) in the hippocampal DG using the immunofluorescent staining. The remaining 36 mice were divided into 2 groups ( n=18 each) by the random number table method: control group (group C) and NALCN gene knockdown group (group KO). NALCN-shRNA virus was injected in group KO, and scrambled-shRNA virus was injected in group C. The three box social test and open field test were performed at 3 weeks after the virus injection. Mice were sacrificed under anesthesia after the behavioral test, hippocampal tissues were collected, and the injection location of the virus was verified with a fluorescence microscope, and the NALCN protein and mRNA expression in the hippocampal DG was detected by Western blot and real-time polymerase chain reaction, respectively. Results:NALCN and NeuN co-expressed a lot on the same neuron in the hippocampal DG of mice, indicating that NALCN was widely expressed on the neurons in the hippocampal DG. Compared with group C, the expression of NALCN and mRNA in the hippocampal DG was significantly down-regulated, and the social novelty preference disappeared ( P<0.05), and no significant change was found in the social ability and each parameter in the open field test in group KO ( P>0.05). Conclusions:NALCN in the hippocampal DG is involved in the regulation of social memory in mice, and the down-regulated expression of NALCN can lead to the loss of social novelty preference in mice.

Objective:To compare the efficacy of different drugs in reducing incidence of emergence agitation after tonsillectomy and adenoidectomy in the pediatric patients.Methods:Cochrane Library, PubMed, Web of Science, EMBASE, China National Knowledge Infrastructure, Wanfang and Chinese Biomedical Literature Databases were searched from inception to July 2023 for the randomized controlled trials involving interventions to reduce the incidence of emergence agitation after tonsillectomy and adenoidectomy in pediatric patients. Two researchers independently screened the literature, extracted data, and evaluated the risk of bias in the included studies. STATA 17.0 software was used to conduct a network meta-analysis according to the frequency-ology framework.Results:Twenty randomized controlled trials were finally included, involving 1 687 patients. Compared with placebo, 10 interventions could reduce the incidence of emergence agitation in pediatric patients after tonsillectomy and adenoidectomy, and the order of probability was as follows: dexmedetomidine ( OR and 95% confidence interval [ CI] 0.13 [0.09-0.20]), ketamine ( OR and 95% CI 0.15 [0.08-0.26]), clonidine ( OR and 95% CI 0.15 [0.05-0.50]), tramadol ( OR and 95% CI 0.16 [0.04-0.61]), remazolam ( OR and 95% CI 0.17 [0.06-0.47]), afentanil ( OR and 95% CI 0.22 [0.08-0.62]), remifentanil ( OR and 95% CI 0.24 [0.12-0.48]), desocine ( OR and 95% CI 0.29 [0.12-0.69]), fentanyl ( OR and 95% CI 0.31 [0.19-0.52]) and propofol ( OR and 95% CI 0.46 [0.24-0.86]). Four interventions cloud reduce the usage rate of postoperative rescue drugs, and the probability was ranked as follows: dexmedetomidine ( OR and 95% CI 0.19 [0.11-0.32]), tramadol ( OR and 95% CI 0.20 [0.10-0.42]), ketamine ( OR and 95% CI 0.49 [0.28-0.86]) and fentanyl ( OR and 95% CI 0.49 [0.32-0.77]). One intervention cloud reduce the incidence of postoperative nausea and vomiting: dexmedetomidine ( OR and 95% CI 0.54 [0.31-0.94]). Conclusions:Dexmedetomidine provides the best effect in reducing the incidence of emergence agitation after pediatric tonsillectomy and adenoidectomy.

Objective:To evaluate the relationship between Na + leak current channel (NALCN) in hippocampal dentate gyrus (DG) region and cognitive function in mice. Methods:Thirty-nine male wild type C57BL/6 mice, aged 6-8 weeks, weighing 18-22 g, were studied.Three mice were sacrificed to verify the expression of NALCN co-localized with neuronal nuclear antigen (NeuN) in the hippocampal DG region through immunofluorescence technique.The remaining 36 mice were divided into 2 groups ( n=18 each) by the random number table method: control group (group C) and NALCN gene knockout group (group KO). NALCN-shRNA virus was injected in hippocampal DG region in group KO, and scrambled-shRNA virus was injected in group C. Three weeks after virus injection, behavioral tests (Y maze test and open field test) were performed, then the animals were sacrificed, and the hippocampal tissues were removed for determination of the expression of NALCN protein and mRNA using Western blot and real-time polymerase chain reaction. Results:NALCN and NeuN colocalized a lot on the same neuron in the hippocampal DG region of mice, and NALCN was widely expressed in the hippocampal DG region.Compared with group C, the expression of NALCN protein and mRNA was significantly down-regulated, the times of entering the new arm were reduced, the duration of staying at the new arm was shortened ( P<0.05), and no significant change was found in the parameters mentioned above in the open field test in group KO ( P>0.05). Conclusions:NALCN in the hippocampal DG region is involved in the regulation of cognitive function in mice, and the down-regulation of NALCN may lead to cognitive decline.

Objective:To systematically compare the efficacy of different drugs in alleviating remifentanil-induced hyperalgesia.Methods:Databases such as PubMed, Cochrane Library, EMBASE, Web of Science, CNKI, Wanfang Data and CBM were searched using computers from inception to May 2020.The randomized controlled trials comparing the efficacy of different intervention measures for alleviating remifentanil-induced hyperalgesia were searched.After independently identifying the literature, the two reviewers conducted data extraction and evaluated the bias of the included studies, and Stata 14.0, ADDIS 1.16.5 and R4.0.2 softwares were used to analyze the data.Results:Thirty randomized controlled trials were included in our study.Compared with placebo, 3 out of 6 drugs could alleviate remifentanil-induced hyperalgesia, and the probability order for the effect was as follows: butorphanol with MD value (95% CI)-1.50 (-2.80, -0.24), dexmedetomidine with MD value (95% CI)-1.20 (-2.40, -0.09) and ketamine with MD value (95% CI) -0.88 (-1.60, -0.16). After sensitivity analysis, the efficacy of butorphanol remained to be verified.Two drugs could decrease the dosage of opioids within 24 h after operation, and the probability order for the effect was as follows: dexmedetomidine with MD value (95% CI) -14.00 (-28.00, -0.19) and ketamine with MD value (95% CI) -9.20 (-18.00, -0.08). One drug could decrease the incidence of postoperative nausea and vomiting within 24 h after operation: dexmedetomidine with RR value (95%CI) 0.28 (0.16, 0.22). Conclusion:The results of network meta-analyses show that dexmedetomidine has the best efficacy in alleviating remifentanil-induced hyperalgesia.