Prior knowledge accelerates subsequent learning of similarly structured problems – a phenomenon termed learning to learn – by forming generalizable neural representations called neural correlates of schema (NCS). However, how the brain exploits stable NCS while remaining flexible towards changes (the stability-plasticity dilemma) remains unclear. Here, we show that the primate brain addresses this dilemma by representing the stable NCS and task-unique changes in a near-orthogonal manner. We analyzed neural activities in the dorsolateral premotor cortex of three male macaques trained to perform a series of visuomotor mapping tasks. By delineating decision and stimulus-related subspaces, we identified NCS within the decision subspace, whose reuse facilitated subsequent learning. In addition, the decision subspace exhibited a near-orthogonal relationship with the stimulus-related subspace, minimizing cross-domain interference. Our results reveal that restricting NCS to specific functional domains can preserve useful knowledge while maintaining near-orthogonality with other subspaces, enabling flexible adaptation to new environments, thereby resolving the stability-plasticity dilemma. This study reveals that during a series of learning tasks, the macaque brain represents the shared (e.g. the decision strategy) and task-unique information (e.g., sensory inputs) in a near-orthogonal manner, thereby supporting reuse of the shared component to facilitate learning, while remain flexible to changes in specifics.

Drug-resistant bacteria infected wounds often bring high risks of delayed healing process and even death. Sonodynamic therapy (SDT) can efficiently kill drug-resistant bacteria. However, superabundant reactive oxygen species (ROS) generated during SDT inevitably trigger significant inflammatory responses, hindering tissue remodeling. Herein, we develop intelligent ultrathin high-entropy hydrotalcites (UHE-HTs)-based injectable thermal-responsive hydrogel loaded with nicotinamide mononucleotide (UHE-HTs/PFN), aiming to achieve programmed antibacterial and anti-inflammatory effects. In the early infection stage, sonosensitive UHE-HTs/PFN hydrogel simultaneously can trigger rapid production of singlet oxygen (1O2) under ultrasound and efficient MDR bacterial sterilization. After halting ultrasonic irradiation, oxidoreductase-mimicking catalysis and nicotinamide mononucleotide release of UHE-HTs/PFN hydrogel effectively reduce ROS levels at wound sites, dampening the NF-κB inflammatory pathway. Such inhibited NF-κB expression can not only reduce the production of pro-inflammatory cytokines and inflammatory responses, but also significantly down-regulate the pyroptosis pathways (NLRP3/ASC/Casp-1) and inhibit pyroptosis that leads to inflammation. Moreover, significantly reduced ROS levels and synergistic release of Mg2+ reverse pro-inflammatory immune microenvironment. Both in vitro and in vivo assays demonstrate that UHE-HTs/PFN hydrogel can transform the adverse infected wound environment into a regenerative one by eradicating drug-resistant bacteria, scavenging ROS, and synergistic anti-inflammation. Therefore, this work develop an intelligent UHE-HTs/PFN hydrogel act as a “lever” that effectively achieve a balance between ROS generation and annihilation, rebuilding harmonious bactericidal and anti-inflammatory effects to remedy drug-resistant bacteria infected wound.

ObjectiveThe main purpose of the present study was to assess the beneficial effect of Lactobacillus plantarum GM11 (LacP GM11), screened from Sichuan traditional fermented food, in depressive rats induced by chronic unpredictable mild stress (CUMS).MethodsMale SPF SD rats were randomly assigned to 3 groups: the control group, CUMS group and CUMS + LacP GM11 group (n = 10). The rats in the CUMS and LacP GM11 groups received CUMS stimulation for 42 d. The behavioral tests and levels of monoamine neurotransmitter, glucocorticoid hormone and brain-derived neurotrophic factor (BDNF) in the serum and hippocampus were measured. The effects of LacP GM11 on the mRNA and protein expression of BDNF and cAMP response element binding protein (CREB) in the hippocampus were also investigated.ResultsAfter supplementation for 21 d, LacP GM11 was associated with alleviation of depressive-like behavior, not anxiety-like behavior, in depressive rats. LacP GM11 increased the levels of 5-hydroxytryptamine (5-HT) and BDNF and decreased the level of cortisol (CORT) in the serum and hippocampus in depressed rats. In addition, treatment with LacP GM11 also increased the mRNA and protein expression of BDNF and CREB in the hippocampus.ConclusionsThis work has revealed that LacP GM11 has potential beneficial effects on depression. This effect might be related to alleviating monoamine neurotransmitter deficiency, HPA axis hyperfunction and CREB-BDNF signaling pathway downregulation. This study demonstrates that LacP GM11 could be a potential therapeutic approach to treat depression and other mental health problems.

Lin, Tian, Huaping Jia, Yunming Li, Yongxing Xu, Bei Zhao, Dong Zheng, Hongfeng Yan, Meihui Zhao, Yanlei Li, Liping Xia, Fengxia Zhou, Cuiping Liu, Ke Ma, Ma Mi, and Jianwen Gu. Epidemiological survey of congenital heart disease among children aged from 2 to 18 in Suo County, Nagqu, Tibet. High Alt Med Biol. 00:000-000, 2024. Background: Studies have reported the prevalence of congenital heart disease (CHD) in parts of Tibet, but relative epidemiological surveys are rare. We aimed to explore the prevalence of CHD in children and its relationship with family history in Suo County, Nagqu, Tibet, an altitude of 3,980 meters. Methods: We recruited 4,002 children aged 2-18 years. Subjects underwent a family history investigation, cardiac auscultation, and clinical manifestation examination and then received echocardiographic screening. Results: The prevalence of CHD among children in Suo County was 0.97% (39 cases), much higher than the prevalence at sea level. The most common subtype was atrial septal defect, accounting for 53.9% of CHD, followed by patent ductus arteriosus (33.3%) and ventricular septal defect (12.8%). We also found that children whose mothers had previously borne children with CHD had a higher risk of CHD than those without (p = 0.002); other factors related to CHD during pregnancy, such as smoking, drinking, drug use, and viral infection, showed no statistical differences between children with and without CHD. Conclusions: The prevalence of CHD in children in Suo County is much higher than at low altitude, consisting mostly of simple forms with left-to-right shunt, with rare complex CHD. These results support implementing diagnostic and treatment plans to prevent CHD in Suo County.

Exercise-induced mechanical loading can increase bone strength whilst mechanical unloading enhances bone-loss. Here, we investigated the role of lncRNA NONMMUT004552.2 in unloading-induced bone-loss. Knockout of lncRNA NONMMUT004552.2 in hindlimb-unloaded mice caused an increase in the bone formation and osteoblast activity. The silencing of lncRNA NONMMUT004552.2 also decreased the osteoblast apoptosis and expression of Bax and cleaved caspase-3, increased Bcl-2 protein expression in MC3T3-E1 cells. Mechanistic investigations demonstrated that NONMMUT004552.2 functions as a competing endogenous RNA (ceRNA) to facilitate the protein expression of spectrin repeat containing, nuclear envelope 1 (Syne1) by competitively binding miR-15b-5p and subsequently inhibits the osteoblast differentiation and bone formation in the microgravity unloading environment. These data highlight the importance of the lncRNA NONMMUT004552.2/miR-15b-5p/Syne1 axis for the treatment of osteoporosis.

BACKGROUND:Breast cancer is one of the most common malignant tumors in women. A noninvasive ultrasound examination can identify mammary-gland-related diseases and is well tolerated by dense breast, making it a preferred method for breast cancer screening and of significant clinical value. However, the diagnosis of breast nodules or masses via ultrasound is performed by a doctor in real time, which is time-consuming and subjective. Junior doctors are prone to missed diagnoses, especially in remote areas or grass-roots hospitals, due to limited medical resources and other factors, which bring great risks to a patient's health. Therefore, there is an urgent need to develop fast and accurate ultrasound image analysis algorithms to assist diagnoses.METHODS:We propose a breast ultrasound image-based assisted-diagnosis method based on convolutional neural networks, which can effectively improve the diagnostic speed and the early screening rate of breast cancer. Our method consists of two stages: tumor recognition and tumor classification. (1) Attention-based semantic segmentation is used to identify the location and size of the tumor; (2) the identified nodules are cropped to construct a training dataset. Then, a convolutional neural network for the diagnosis of benign and malignant breast nodules is trained on this dataset. We collected 2057 images from 1131 patients as the training and validation dataset, and 100 images of the patients with accurate pathological criteria were used as the test dataset.RESULTS:The experimental results based on this dataset show that the MIoU of tumor location recognition is 0.89 and the average accuracy of benign and malignant diagnoses is 97%. The diagnosis performance of the developed diagnostic system is basically consistent with that of senior doctors and is superior to that of junior doctors. In addition, we can provide the doctor with a preliminary diagnosis so that it can be diagnosed quickly.CONCLUSION:Our proposed method can effectively improve diagnostic speed and the early screening rate of breast cancer. The system provides a valuable aid for the ultrasonic diagnosis of breast cancer.

BACKGROUND Neuroinflammation and oxidative stress after traumatic brain injury (TBI) can further lead to neuronal apoptosis, which plays a crucial role in the process of neuron death. Curcumin, which is derived from the rhizome of the Curcuma longa plant, has multiple pharmacological effects. OBJECTIVE The objective of this study was to investigate whether curcumin treatment has neuroprotective effects after TBI, and to elucidate the underlying mechanism. METHODS A total of 124 mice were randomly divided into 4 groups: Sham group, TBI group, TBI+Vehicle group, and TBI+Curcumin group. The TBI mice model used in this study was constructed with TBI device induced by compressed gas, and 50 mg/kg curcumin was injected intraperitoneally 15 minutes after TBI. Then, the blood-brain barrier permeability, cerebral edema, oxidative stress, inflammation, apoptosis-related protein, and behavioral tests of neurological function were utilized to evaluate the protective effect of curcumin after TBI. RESULTS Curcumin treatment markedly alleviated post-trauma cerebral edema and blood-brain barrier integrity, and suppressed neuronal apoptosis, reduced mitochondrial injury and the expression of apoptosis-related proteins. Moreover, curcumin also attenuates TBI-induced inflammatory response and oxidative stress in brain tissue and improves cognitive dysfunction after TBI. CONCLUSION These data provide substantial evidence that curcumin has neuroprotective effects in animal TBI models, possibly through the inhibition of inflammatory response and oxidative stress.

. The present study investigated the effect of COVID-19 infection on the development and patho-genesis of neurodegenerative diseases. The Cox proportional hazards regression method was used for the determination of development of neurodegenerative diseases in among the patients. The data obtained from the patients revealed that the risk of neurodegenerative disease development increases around 1.5-fold among COVID-19 patients compared to non COVID-19 population. Moreover, the risk of neurodegenerative disease development was significantly higher among males and patients above the age of 45 years. The risk of devel-oping neurodegenerative disease was found to be around 1.5-fold higher in COVID-19 patients during the first one-year of follow-up. In conclusion, the present study demonstrates that COVID-19 infection causes a significant increase in risk of development of neurodegenerative diseases. Therefore, the COVID-19 patients need to take care and consult doctors for prevention of neurodegenerative diseases.

Ketamine, an NMDA antagonist, is widely used in clinical settings. Recently, low-dose ketamine has gained attention because of its promising role as a rapid antidepressant. However, the effects of low-dose ketamine on brain function, particularly higher cognitive functions of primate brains, are not fully understood. In this study, we used two macaques as subjects and found that acute low-dose ketamine administration significantly impaired the ability for arbitrary visuomotor mapping (AVM), a form of associative learning (AL) essential for flexible behaviors, including executions of learned stimuli-response contingency or learning of new contingencies. We conducted in-depth analyses and identified intrinsic characteristics of these ketamine-induced functional deficits, including lowered accuracy, prolonged time for planning and movement execution, increased tendency to make errors when visual cues are changed from trial to trial, and stronger impact on combining associative learning and another key higher cognitive function, working memory (WM). Our results shed new light on how associative learning relies on the NMDA-mediated synaptic transmission of the brain and contribute to a better understanding of the potential acute side effects of low-dose ketamine on cognition, which can help facilitate its safe usage in medical practice.

Ketamine is an NMDAR antagonist that has been widely used for clinical anesthesia. In addition, low-dose ketamine has analgesic, anti-inflammatory and antidepressant effects, which have attracted extensive attention in recent years. However, how low-dose ketamine can affect the higher cognitive functions remain unclear. Here we review the effects of low-dose ketamine on working memory (WM). WM is the ability to temporally hold and manipulate information in the brain. It mainly relies on a network involving several key brain areas such as the prefrontal cortex (PFC), hippocampus, etc. WM plays a key role in many complex cognitive processes, thus to understand how it may be affected by low-dose ketamine is informative and important for its clinic use. Here we review the studies showing that acute or chronic use of low-dose ketamine will impair working memory in a sophisticated way. The possible mechanisms underlying such impairments include breaking the excitation/inhibition (E/I) balance in the PFC, changing the short-term and long-term synaptic plasticity, activating the DA pathway, etc. We also pointed out that to fully reveal the effects of low-dose ketamine on WM and related neural mechanism, future multi-facet studies combining behavioral tests, electrophysiology, neuroimaging, histology, etc, and with more comparable dosage and time of medication would be needed. We hope that this review will be instrumental for facilitating appropriate use of low-dose ketamine in clinical settings.

A novel structural dynamics test method and device were designed to test the biomechanical effects of dynamic axial loading on knee cartilage and meniscus. Firstly, the maximum acceleration signal-to-noise ratio of the experimental device was calculated by applying axial dynamic load to the experimental device under unloaded condition with different force hammers. Then the experimental samples were divided into non-specimen group (no specimen loaded), sham specimen group (loaded with polypropylene samples) and bovine knee joint specimen group (loaded with bovine knee joint samples) for testing. The test results show that the experimental device and method can provide stable axial dynamic load, and the experimental results have good repeatability. The final results confirm that the dynamic characteristics of experimental samples can be distinguished effectively by this device. The experimental method proposed in this study provides a new way to further study the biomechanical mechanism of knee joint structural response under axial dynamic load.

Objective:To explore the characteristics and nursing measures of medical rescue support in space station.Methods:According to the characteristics of medical rescue support task of manned space mission, practical nursing schemes and corresponding nursing measures were formulated from the aspects of personnel selection, personnel training, material preparation, process formulation, training exercise and epidemic prevention.Results:The "Shenzhou-12" mission includes the whole launch phase, operation phase and return phase. There are many tasks that cover a long time. The contents of medical rescue support include personnel's physical and mental quality, technical ability, environmental equipment, the possible injuries of astronauts, and the normalization of COVID-19's task guarantee. In view of this content, a practical nursing scheme was formulated to enable nurses to quickly master and skillfully cooperate with the treatment, win more time for the treatment and improve the overall rescue level.Conclusions:Various process plans have been integrated and optimized for medical rescue support of space mission. The equipment carried is advanced, and can be used in various complex environments and complex working conditions. The rescue support personnel have also done their best, kept improving and solidified the state. We should constantly sum up experience, explore and study new problems, and make new achievements in medical rescue support for space missions.

目的 研究轻型颅脑爆炸冲击伤后大鼠不同时间脑组织星形胶质细胞、小胶质细胞和神经元损伤反应的病理改变和过程.同时探讨富含鱼油饮食对轻型颅脑爆炸冲击伤大鼠的神经保护作用.方法 收集54只刚断乳SD大鼠,随机均分为对照组、模型组、治疗组,模型组及治疗组大鼠分别在喂养普通饲料和富含鱼油的饲料33 d后建立由冲击波诱导的轻型颅脑爆炸冲击损伤模型,对照组大鼠在喂养普通饲料33 d后不建立爆炸冲击波损伤模型.结果 与对照组相比,模型组和治疗组的大鼠体质量在致伤后出现一定程度的减轻,随后恢复至致伤前水平;轻型爆炸伤后6 h、24 h、3 d,模型组和治疗组大鼠大脑海马区GFAP阳性染色星形胶质细胞数量及海马区锥体细胞数量均减少.反之,模型组和治疗组大鼠脑组织中海马区的激活态小胶质细胞和皮层区域凋亡神经元数量均增加,且具有时间依赖性.此外,与模型组相比,治疗组可增加伤后星形胶质细胞和海马区锥体细胞数量,并降低激活态小胶质细胞和皮层区域凋亡神经元数量.结论 富含鱼油饮食可通过减轻颅脑爆炸伤后神经细胞损伤,抑制神经炎性反应等方面发挥其神经保护作用.

IntroductionDuring the COVID-19 pandemic, approximately 10%–35% of COVID-19 infected patients experience post-COVID sequela. Among these sequelae, pain symptoms should not be neglected. In addition, the sequelae of COVID-19 also decrease the quality of life of these populations. However, meta-analyses that systematically evaluated post-COVID pain are sparse.Methods and analysisA comprehensive screening will be performed by searching MEDLINE and Embase without language restriction from inception to August 2021. Cohort studies, case–control studies, cross-sectional studies and case series will be included. Case report and interventional studies will be excluded. Studies with less than 20 participants will be also excluded. We aim to investigate the prevalence of pain-related symptoms in patients after the acute phase of COVID-19. The impact of COVID-19 on the quality of life and pain symptoms among these populations in the post-acute phase will also be evaluated. ROBINS-I tool will be used to assess the risk of bias of cohort studies. The risk of bias tool developed by Hoy et al will be used to assess the risk of bias of prevalence studies. Metaprop command in Stata will be used to estimate the pooled prevalence of pain symptoms. DerSimonian and Laird random-effects models will be used to calculate the pooled relative risks. All analyses will be calculated using Stata software (V.15.0; StataCorp)Ethics and disseminationEthics approval is not required. Results of our study will be submitted to a peer-review journal.PROSPERO registration numberCRD42021272800.

Background Genetically modified probiotics have potential for use as a novel approach to express bioactive molecules for the treatment of obesity. The objective of the present study was to investigate the beneficial effect of genetically modified Escherichia coli Nissle 1917 (EcN-GM) in obese C57BL/6J mice. Methods First, an obesity model in C57BL/6J mice was successfully established. Then, the obese mice were randomly assigned into three groups: obese mice (OB), obese mice + EcN-GM (OB + EcN-GM), and obese mice + orlistat (OB + orlistat) ( n = 10 in each group). The three groups were gavaged with 0.3 ml of 10 10 CFU/ml control EcN, EcN-GM (genetically engineered EcN) and 10 ml/kg orlistat. Body weight, food consumption, fat pad and organ weight, hepatic biochemistry and hepatic histopathological alterations were measured. The effects of EcN-GM on the levels of endocrine peptides and the intestinal microbiota were also analyzed. Results After supplementation for 8 weeks, EcN-GM was associated with decreases in body weight gain, food intake, fat pad and liver weight, and alleviation hepatocyte steatosis in obese mice. EcN-GM also increased the level of GLP-1 in serum and alleviated leptin and insulin resistance. Moreover, supplementation with EcN-GM increased the α-diversity of the intestinal microbiota but did not significantly influence the relative abundance of Firmicutes and Bacteroidetes . Conclusions These results indicated that EcN-GM, a genetically modified E. coli strain, may be a potential therapeutic approach to treat obesity. The beneficial effect of EcN-GM may be independent of the alteration of the diversity and composition of the intestinal microbiota in obese mice.

BACKGROUND: Although previous studies have made significant contributions to establishing animal traumatic brain injury (TBI) models for simulation of human TBI, the accuracy, controllability, and modeling efficiency of animal TBI models need to be further improved. This study established a novel high-efficiency graded mouse TBI model induced by shock wave. METHODS: A total of 125 mice were randomly divided into sham, 0.7 mm, 0.6 mm, and 0.5 mm groups according to the depth of the cross groove of the aluminum sheets. The stability and repeatability of apparatus were evaluated, and the integrity of the blood-brain barrier, cerebral edema, neuropathologic immunohistochemistry, apoptosis-related protein, and behavioral tests of neurologic function were used to validate this new model. RESULTS: The results showed that 4 mice were injured simultaneously in 1 experiment. They received the same intensity of shock waves. Moreover, the mortality rates caused by 3 different aluminum sheets were consistent with the mortality rates of mild TBI, moderate TBI, and severe TBI. Compared with the sham group, mice in different injured groups significantly increased brain water content, blood-brain barrier permeability, and neuronal apoptosis. And the mice in all injured groups showed poor motor ability, balancing, spatial learning, and memory abilities. CONCLUSIONS: The novel TBI apparatus has advantages in its small size, simple operation, high repeatability, high efficiency, and graded severity. Our TBI apparatus provides a novel tool to investigate the neuropathologic changes and underlying mechanisms of TBI with various levels of severities.

Objective:Summarize the experience of the medical rescue team at the main landing site of China's manned space mission, analyze the new characteristics of the Shenzhou 12 space station mission, and take corresponding countermeasures and measures to ensure the strong medical rescue guarantee for astronauts.Methods:Search the publications about astronaut medical aid domestic and abroad, summarize the rescue and medical aid experiences from Shenzhou 5 to Shenzhou 11. In consideration of prolonged on-orbit time, Location adjustment of the landing site and the new characteristics of the complex terrain, new targeted strategies were presented.Results:The astronauts flew in orbit for 90 days, and the main landing site and launch site are in the same area. The medical security includes three parts: launch section, running section and return section. Desert rescue model were added. Ten injuries were simulated and each injury first-aid procedure was standardized.Conclusion:After targeted improvement and optimization, the Shenzhou 12 astronauts medical rescue support program ensures the safety of the whole process, all-weather and all-terrain emergency and rear delivery of the astronauts in the new mission environment and complex terrain.

Since December 2019, a novel coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 was found in Wuhan, and rapidly spread throughout China and extended globally.1 By the end of August 2020, the positive momentum in COVID-19 control has been locked in, and nationwide virus control is now being conducted on an ongoing basis in China. In order to improve the regular epidemic response mechanisms to prevent a resurgence of the outbreak, Beijing Municipal Health Commission recently issued a notice that appointment is required for all non-emergency outpatients in general hospitals. Although outpatient appointment has emerged for several years, queuing registration on-site is still the traditional and predominant way in China, which is different from the consistent outpatient reservation system in western countries. Whether this rapid shift in the approach of outpatient registration would heighten the difficulties in accessing medical services during the coronavirus crisis? In addition, although the situation of the COVID-19 epidemic is improved, China is still under pressure of preventing sporadic or asymptomatic cases. All these challenges are worthy of attention, and new ways of getting medical services are urgently needed. With the popularisation of smartphones and wireless networks, mobile health technology was applied to the self-management of chronic diseases, such as diabetes. Since 2016, mobile-based diabetes prevention and self-management have been highlighted and recommended by American Diabetes Association and Chinese Diabetes Society.2, 3 However, most of these mobile applications were focused on diabetes self-management and lacked the involvement of professional medical personnel, which results in limited effect. Beijing Municipal Medical Insurance Bureau recently released a notice saying expenses from Internet medical services could be covered by Chinese Medical Insurance Funds, which was a forceful policy support for patients to get individualised medical services in this regular epidemic containment stage. The latest research demonstrated that diabetes was a representative indicator of multi-organ injury and an earlier predictor for poor outcomes and death in COVID-19 patients.4-6 Assisting diabetes patients in managing diet and blood glucose during the COVID-19 epidemic has been a hot issue concerned by diabetologists. In order to explore the diabetes management model based on physician-nurse collaboratively online consultation during the coronavirus crisis, ‘306 Diabetes Club’, a mobile-based public WeChat account established by the Department of Endocrinology in our hospital, was provided to outpatients with diabetes.7 There were 1443 individuals who followed this account, including 491 new followers from 14 Feb to 31 Mar 2020. In this period, a total of 362 consulting questions were raised by followers, which mainly focused on diabetes diagnosis (27.1%) and medications (42.8%).7 All of these consultations were timely replied by professional endocrinologists and senior nurses, with high user satisfaction. By outpatient appointments combined with physician-nurse collaborative online consultation, the risk of coronavirus infection might be decreased by preventing crowding. Meanwhile, the basic medical needs could be timely met, which won outpatients’ high praise.7 In addition, flexible working pattern and reduced workload were also well received by health professionals, which may ease strained doctor–patient relationships in China. Considering practical feasibility and clear benefits, we expect outpatient appointments combined with mobile-based physician-nurse collaborative medical consultation could become routine in China with the regular containment of COVID-19. The authors declare no competing interests. Aihong Wang conceived the correspondence, led on drafting the manuscript, and revised the manuscript critically. Weibo Zhao drafted the manuscript and revised it critically. Jianwen Gu conceived this correspondence and revised the manuscript.

Background: Considering transaminase more than the upper limit of normal value as liver injury might overestimate the prevalence of liver involvement in COVID-19 patients.No meta-analysis has explored the impact of varied definitions of liver injury on the reported prevalence of liver injury.Moreover, few studies reported the extent of hypertransaminasemia stratified by COVID-19 disease severity.Methods: A literature search was conducted using PubMed and Embase.The pooled prevalence of liver injury and hypertransaminasemia was estimated.Results: In total, 60 studies were included.The overall prevalence of liver injury was 25%.Compared to subgroups with the non-strict definition of liver injury (33%) and subgroups without giving detailed definition (26%), the subgroup with a strict definition had a much lower prevalence of liver injury (9%).The overall prevalence of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) elevation was 19% and 22%.The prevalence of elevated ALT and AST were significantly higher in severe COVID-19 cases compare to non-severe cases (31% vs 16% and 44% vs 11%).In critically ill and fatal cases, no difference was found in the prevalence of elevated ALT (24% vs 30%) or AST (54% vs 49%).Sensitivity analyses indicated that the adjusted prevalence of ALT elevation, AST elevation, and liver injury decreased to 14%, 7%, and 12%. Conclusion:The overall prevalence of liver injury and hypertransaminasemia in COVID-19 patients might be overestimated.Only a small fraction of COVID-19 patients have clinically significant liver injury.The prevalence of hypertransaminasemia was significantly higher in severe COVID-19 cases compare to non-severe cases.Hence, in severe COVID-19 patients, more attention should be paid to liver function tests.