γδ T cell antigen receptor polyspecificity enables T cell responses to a broad range of immune challenges.

γδ T cells are essential for immune defense and modulating physiological processes. While they have the potential to recognize large numbers of antigens through somatic gene rearrangement, the antigens which trigger most γδ T cell response remain unidentified, and the role of antigen recognition in γδ T cell function is contentious. Here, we show that some γδ T cell receptors (TCRs) exhibit polyspecificity, recognizing multiple ligands of diverse molecular nature. These ligands include haptens, metabolites, neurotransmitters, posttranslational modifications, as well as peptides and proteins of microbial and host origin. Polyspecific γδ T cells are enriched among activated cells in naive mice and the responding population in infection. They express diverse TCR sequences, have different functional potentials, and include the innate-like γδ T cells, such as the major IL-17 responders in various pathological/physiological conditions. We demonstrate that encountering their antigenic microbiome metabolite maintains their homeostasis and functional response, indicating that their ability to recognize multiple ligands is essential for their function. Human γδ T cells with similar polyspecificity also respond to various immune challenges. This study demonstrates that polyspecificity is a prevalent feature of γδ T cell antigen recognition, which enables rapid and robust T cell responses to a wide range of challenges, highlighting a unique function of γδ T cells.

Sarcopenia as a predictor of hospitalization among older people: a systematic review and meta-analysis.

BACKGROUND: Previous cohort studies investigating the association between sarcopenia and the risk of hospitalization have been inconsistent. We performed a meta-analysis to determine if sarcopenia is a predictor of hospitalization. METHODS: Prospective cohort studies that evaluated the association between sarcopenia and hospitalization in older people were identified via a systematic search of four electronic databases (PubMed, EMBASE, Science Citation Index, and the Cochrane Library). A random-effect model was applied to combine the results according to the heterogeneity of the included studies. RESULTS: Five studies (2832 participants) were included in this meta-analysis. Pooled results demonstrated that older people with sarcopenia were at an increased risk of hospitalization (pooled hazards ratio [HR] = 1.57, 95% confidence interval [CI] = 1.26, 1.94, I2 = 4.5%, P = 0.000) compared to those without sarcopenia. Results of subgroup analyses showed that hospitalized patients with sarcopenia had a higher rate of hospitalization (HR = 2.01, 95% CI = 1.41, 2.88, p = 0.000) versus patients without sarcopenia. A similar result was also found in community-dwelling older people with sarcopenia versus those without sarcopenia (HR = 1.40, 95% CI = 1.05, 1.88, p = 0.023). In addition, the subgroup analysis for length of follow-up showed that studies with a follow-up period of 3 years or more (pooled HR = 1.52, 95% CI = 1.19, 1.94, P = 0.001) reported a significantly higher rate of hospitalization among individuals with sarcopenia compared to those without sarcopenia. However, this association was not found in the studies with a follow-up period of less than 3 years (pooled HR = 1.76, 95% CI = 0.90, 3.44, P = 0.099). CONCLUSIONS: Sarcopenia is a significant predictor of hospitalization among older individuals, and the association may not be significantly affected by the characteristics of the population or the definition of sarcopenia.

CD147 up-regulates calcium-induced chemotaxis, adhesion ability and invasiveness of human neutrophils via a TRPM-7-mediated mechanism.

OBJECTIVES: We aimed to investigate whether CD147 can up-regulate the chemotactic, adhesive and invasive properties of human neutrophils and to determine the mechanism underlying this process. METHODS: Human promyelocytic leukaemia cells (HL-60) cells and peripheral blood or synovial fluid neutrophils were isolated from RA patients. Under cyclophilin A (CypA) stimulation, chemotaxis, adhesion potential and invasion ability were assessed using chemotaxis, adhesion and invasiveness assays. Lipid raft isolation and western blot were used to determine the mechanism underlying the effects of CypA stimulation. RESULTS: CD147 up-regulates the calcium-induced chemotaxis, adhesion ability and invasiveness of human neutrophils in RA patients. Transient receptor potential melastatin 7 may be responsible for this phenomenon. CONCLUSION: These findings suggest that in RA patients, abundant CypA up-regulates the calcium-induced chemotactic, adhesive and invasive properties of neutrophils via direct binding to CD147. Cyclophilin-CD147 interactions might contribute to the destruction of cartilage and bone in RA.

Oscillatory Dynamics and Regulatory Mechanisms of the p53-Per2 Network in DNA-Damaged Cells.

Circadian rhythm disruptions are linked to increased cancer risk and unfavorable prognosis in patients with cancer, highlighting the critical role of the interplay between the circadian rhythm factor Per2 and the tumor suppressor p53. This brief presents, for the first time, a mathematical model to capture the dynamics of the p53-Per2 network in DNA-damaged cells. The model accurately describes the different stages of the process from unstressed cells to cellular repair and finally to apoptosis as the degree of DNA damage increases. Furthermore, it is found that increasing the inhibition of Per2 by p53 leads to the phase advance of Per2 oscillations, whereas by modulating the inhibition of Mdm2 by Per2, an independent amplitude modulation of active p53 can be achieved, with the range of modulation increasing with the strength of the inhibition. Moreover, the effects of time delays inherent in the transcription, translation, and nuclear translocation of Per2 on the circadian rhythm of DNA-damaged cells are quantitatively investigated by theoretical analyses. It is found that time delays can induce stable oscillations through a supercritical Hopf bifurcation, thereby maintaining the circadian function of DNA-damaged cells and enhancing their DNA-damage repair capacity. This study proposes new insights into cancer prevention and treatment strategies.

CD147 induces angiogenesis through a vascular endothelial growth factor and hypoxia-inducible transcription factor 1α-mediated pathway in rheumatoid arthritis.

OBJECTIVE: Rheumatoid arthritis (RA) is an inflammatory and angiogenic disease. However, the molecular mechanisms that promote angiogenesis in RA have not been clearly identified. Our objective was to study the role of CD147 in angiogenesis and determine whether the strategy in which CD147 is suppressed might be useful in reducing angiogenesis in RA. METHODS: Correlations among expression levels of CD147, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor 1α (HIF-1α) were determined by immunohistochemistry staining. RA fibroblast-like synoviocytes (FLS) cells were cultured under various conditions, and the production of VEGF and HIF-1α was examined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. The SCID mouse coimplantation model of RA (SCID-HuRAg) was established, mice were treated with CD147 monoclonal antibody, infliximab, or both CD147 and infliximab, and the volume of the grafts and the average vascular density were measured and analyzed. Western blot analyses were performed to examine the potential signaling pathways. RESULTS: The expression levels of CD147 showed significantly positive correlations with VEGF and HIF-1α levels, as well as with vascular density, in RA synovium. After small interfering RNA transfection or after addition of specific antibodies for CD147, the production of VEGF and HIF-1α were significantly reduced. The expression of VEGF and HIF-1α decreased more after CD147 inhibition than after infliximab treatment in the engrafted tissues in SCID-HuRAg mice. The phosphatidylinositol 3-kinase/Akt pathway may be involved in this process. CONCLUSION: CD147 induces up-regulation of VEGF and HIF-1α in RA FLS, further promotes angiogenesis, and leads to the persistence of synovitis. Inhibition of CD147 may be a promising target for novel therapeutic strategies.

Circadian Rhythm Regulated by Tumor Suppressor p53 and Time Delay in Unstressed Cells.

Circadian function and p53 network are interconnected on the molecular level, but the dynamics induced by the interaction between the circadian factor Per2 and the tumor suppressor p53 remains poorly understood. Here, we constructed an integrative model composed of a circadian clock module and a p53-Mdm2 feedback module to study the dynamics of p53-Per2 network in unstressed cells. As expected, the model can accurately predict the circadian rhythm, which is consistent with diverse experimental observations. In addition, using a combination of theoretical analysis and numerical simulation, the results demonstrated that p53 expression enhances the phase advance of circadian rhythm and reduces the robustness of circadian rhythm. Furthermore, the time delay required for the transcription and translation of Per2 protein induces oscillations by undergoing a supercritical Hopf bifurcation, and improves the robustness of circadian rhythm. In summary, this work shows that the p53-Per2 interaction and the time delay are two essential factors for circadian functions.

Expression of CD147 (EMMPRIN) on neutrophils in rheumatoid arthritis enhances chemotaxis, matrix metalloproteinase production and invasiveness of synoviocytes.

The occurrence of neutrophils at the pannus-cartilage border is an important phenomenon for understanding the pathogenesis of rheumatoid arthritis (RA). Matrix metalloproteinases (MMPs) are predominant enzymes responsible for the cartilage degradation. The present article studied the expression of CD147 on neutrophils and its potential role in neutrophil chemotaxis, MMPs production and the invasiveness of fibroblast-like synoviocytes (FLS). The results of flow cytometry revealed that the mean fluorescence intensity of CD147 expression on neutrophils of peripheral blood from RA patients was higher than that in healthy individual. The potential role of CD147 in cyclophilin A (CyPA)-mediated cell migration was studied using chemotaxis assay and it was found that the addition of anti-CD147 antibody significantly decreased the chemotactic index of the neutrophils. Significantly elevated release and activation of MMPs were seen in the co-culture of neutrophil and FLS compared with cultures of the cells alone. An increased number of cells invading through the filters in the invasion assays were also observed in the co-cultured cells. The addition of anti-CD147 antibody had some inhibitory effect, not only on MMP production but also on cell invasion in the co-culture model. Our study demonstrates that the increased expression of CD147 on neutrophils in RA may be responsible for CyPA-mediated neutrophil migration into the joints, elevated MMPs secretion and cell invasion of synoviocytes, all of which may contribute to the cartilage invasion and bone destruction of RA. Better knowledge of these findings will hopefully provide a new insight into the pathogenesis of RA.

[Hierarchical first aid training scheme for elementary and middle school students: the practices from the construction of "Baoan Model" social emergency medicine training].

OBJECTIVE: To share the implementation experience of hierarchical first aid training scheme for elementary and middle school students in Baoan District of Shenzhen City and evaluate its effect of training. METHODS: During August 2018 and August 2019, elementary and middle schools students who participated in the first aid training held by emergency rescue training center of Baoan District were enrolled. Baseline information including the number of students, the number of attending tutors, the number of cardiopulmonary resuscitation (CPR) training models, automated external defibrillator (AED) models were recorded. According to hierarchical levels of three age, students received different courses with content from simple to hard: the course of elementary school students was consisting of dialing 120, smart animation on how to identify accidental damage, demonstration of AED and Hemlick techniques, CPR practise (40 minutes). The course of junior high school students was consisted of how to dial 120, how to identify accidental damage and simple disposal, application of CPR and AED, practice CPR and AED and Hemlick techniques (90 minutes). The course of high school students was consisted of how to dial 120, identify accidental damage and right disposal, identification of out-of-hospital cardiac arrest, the key-point of CPR and AED, practice CPR and AED, Hemlick techniques and hemostatic bandage (120 minutes). At the end of course, elementary school students were voluntary for skill assessment; junior high school students only were compulsory for skill assessment in small classes but not required in large classes, just for demonstration; additionally, the whole high school students were compulsory for skill assessment. The characteristics of first aid training students at different levels were collected in order to compare the differences on the usage of CPR training model and AED training model, the distribution of emergency resource, the ratio for passing examination. RESULTS: A total of 12 896 students and 2 086 training instructors took parted in 200 lists of first aid training courses, 8 557 CPR models and 8 493 AED models were used. On average, there are 65.27±5.61 students in each session, and 10.52±10.43 training instructors. There are 43.09±19.06 CPR training models and 42.77±18.61 AED training models. The mean ratio of student to tutor was 6.07±1.47, student to CPR model was 1.54±1.02, and student to AED model was 1.54±1.03. In the end of course, 10 494 students participated in the examination with the participation rate of 81.37%; 10 114 students passed the examination with the passing rate of 96.38%. Hierarchical analysis showed: compare to elementary school students, the average number of junior high school students in every training session significantly increased (cases: 69.94±8.77 vs. 58.69±6.12, P < 0.05), but the average number of high school students in every training session significantly decreased (cases: 57.35±5.79 vs. 58.69±6.12, P < 0.05). The proportion of instructors in junior high school students' training significantly reduced (5.94±1.39 vs. 6.48±2.02, P < 0.05). The examination ratio of junior high school students and high school students was increased significantly [81.07% (6 667/8 224), 100% (2 313/2 313) vs. 64.18% (1 514/2 359), both P < 0.05], but the ratio of passing the examination was significantly reduced [95.47% (6 365/6 667), 96.88% (2 241/2 313) vs. 99.60%(1 508/1 514), both P < 0.01]. This might be related to the low difficulty of elementary school students' assessment and the low proportion of compulsory examination. CONCLUSIONS: Hierarchical scheme is feasible for first aid training in elementary and middle school students, the content of course should be desighed from easy to hard. Synchronously, sufficient training instructors and training models should be equipped to ensure the quality.

Contribution of cyclophilin A to the regulation of inflammatory processes in rheumatoid arthritis.

INTRODUCTION: Previous studies show that cyclophilin A (CypA) acts as a strong chemotactic cytokine to neutrophils, eosinophils, and monocytes in rheumatoid arthritis (RA). METHODS: In this study, monocytes were stimulated by purified CypA and the production of matrix metalloproteinase (MMPs), the cell invasion and the release of inflammatory cytokines were detected respectively by gelatin zymography, invasion assay, and cytometric bead array FCM. RESULTS: The elevated level of inflammatory cytokine IL-8 was also detected. Results showed that CypA significantly promoted the invasion of THP-1 cells and increased the production of MMP-2 and MMP-9, which displayed a biphasic concentration dependency. In vivo experiments found that the cartilage erosion scores in CypA injection group were significantly higher than those in control group (P < 0.05). CONCLUSION: Our findings suggest that CypA significantly enhances the secretion of MMP-2 and MMP-9, the cell invasion, and the inflammatory cytokines production of monocytes. Our findings may shed some new light on the inflammatory process and the degradation of cartilage and bone in RA.

Falls among older adults with sarcopenia dwelling in nursing home or community: A meta-analysis.

OBJECTIVES: To assess and quantify sarcopenia as a risk for falls among community-dwelling older people and nursing home older persons. METHODS: Prospective cohort studies that evaluated the association between sarcopenia and falls in older adults were identified via a systematic literature search of Medline (via Ovid), PubMed, EMBASE, and the Cochrane CENTRAL Library from database inception until October 15, 2018, in English and Chinese. RESULTS: 10 studies (10,073 participants) were included in the meta-analysis. Among older adults, having sarcopenia was significantly associated with a higher risk of falls, compared to older adults without sarcopenia (pooled OR-odds ratio = 1.52, 95% CI-confidence interval: 1.32-1.77, I2 = 39.1%). In addition, the results of subgroup analysis indicated that male participants with sarcopenia had a higher risk of falls than mixed gender participants with sarcopenia (pooled OR = 1.72, 95% CI: 1.36-2.18 versus pooled OR = 1.41, 95% CI: 1.16-1.70). Other subgroup analyses were conducted using different study follow-up periods (>1 year versus ≤ 1 year) (pooled OR 1.63, 95% CI: 1.38-1.92 versus 1.20, 95% CI: 0.87-1.65). In addition, community-dwelling older people with sarcopenia was significantly increase risk of fall, compared with non-sarcopenia (pooled OR = 1.69, 95% CI: 1.43-2.00), whereas it was not found among nursing home residents (pooled OR = 1.12, 95% CI: 0.84-1.51). Furthermore, sarcopenia definition subgroup analysis found that older adults with sarcopenia increase the risk of falls when using EWGSOP (pooled OR = 1.43, 95% CI: 1.19-1.72), FNIH (pooled OR = 1.82, 95% CI: 1.39-2.37), AWGS (pooled OR = 7.68, 95% CI: 1.41-41.80), respectively. CONCLUSION: The present study found that sarcopenia is a risk factor for falls among community-dwelling older people, but not among nursing home older persons. Future research is needed to provide evidence for specific interventions aimed at treating sarcopenia and preventing falls among older adults dwelling in the community.

Inhibitory effect of CD147/HAb18 monoclonal antibody on cartilage erosion and synovitis in the SCID mouse model for rheumatoid arthritis.

OBJECTIVE: To explore the therapeutic potential of CD147/HAb18 mAb in the treatment of RA in severe combined immunodeficiency (SCID) mice engrafted with human cartilage and rheumatoid synovium tissue (SCID-HuRAg). METHODS: SCID-HuRAg mice were treated separately with CD147/HAb18 mAb, anti-TNF-alpha mAb or a combination of both. The mice in control group were treated with anti-Japanese encephalitis virus mAb. The volume of engrafts was measured and the number of inflammatory cells and cartilage erosion score were examined. Expression of MMP-2, -3 and -9 was determined by immunohistochemistry. Human inflammatory cytokine levels in mouse sera were assessed using cytometric bead array kit. RESULTS: The volume of engrafts decreased significantly in SCID-HuRAg mice treated separately with anti-CD147 mAb or anti-TNF-alpha mAb, and in the mice treated with anti-CD147 mAb plus anti-TNF-alpha mAb (P < 0.05). Significant reduction was observed in cartilage erosion score in anti-CD147 treatment group and combined treatment group (P < 0.05). Immunohistochemical analysis showed that expression of MMP-2, -3 and -9 was lower in the anti-CD147 treatment group and combined treatment group than in the control mAb group (P < 0.05). Moreover, the level of TNF-alpha, IL-6 and -8 in CD147 mAb group showed a significant decrease compared with that of the control mAb group (P < 0.05). CONCLUSIONS: CD147/HAb18 mAb can reduce cartilage erosion and synovitis by inhibition of the MMPs and reduction of inflammatory cytokines in SCID-HuRAg mice, which suggests that CD147/HAb18 mAb is a promising treatment option for RA patients.

The interaction of HAb18G/CD147 with integrin alpha6beta1 and its implications for the invasion potential of human hepatoma cells.

BACKGROUND: HAb18G/CD147 plays pivotal roles in invasion by hepatoma cells, but the underlying mechanism remains unclear. Our previous study demonstrated that overexpression of HAb18G/CD147 promotes invasion by interacting with integrin alpha3beta1. However, it has never been investigated whether alpha3beta1 is solely responsible for this process or if other integrin family members also interact with HAb18G/CD147 in human hepatoma cells. METHODS: Human SMMC-7721 and FHCC98 cells were cultured and transfected with siRNA fragments against HAb18G/CD147. The expression levels of HAb18G/CD147 and integrin alpha6beta1 were determined by immunofluorescent double-staining and confocal imaging analysis. Co-immunoprecipitation and Western blot analyses were performed to examine the native conformations of HAb18G/CD147 and integrin alpha6beta1. Invasion potential was evaluated with an invasion assay and gelatin zymography. RESULTS: We found that integrin alpha6beta1 co-localizes and interacts with HAb18G/CD147 in human hepatoma cells. The enhancing effects of HAb18G/CD147 on invasion capacity and secretion of matrix metalloproteinases (MMPs) were partially blocked by integrin alpha6beta1 antibodies (P < 0.01). Wortmannin, a specific phosphatidylinositol kinase (PI3K) inhibitor that reverses the effect of HAb18G/CD147 on the regulation of intracellular Ca2+ mobilization, significantly reduced cell invasion potential and secretion of MMPs in human hepatoma cells (P < 0.05). Importantly, no additive effect between Wortmannin and alpha6beta1 antibodies was observed, indicating that alpha6beta1 and PI3K transmit the signal in an upstream-downstream relationship. CONCLUSION: These results suggest that alpha6beta1 interacts with HAb18G/CD147 to mediate tumor invasion and metastatic processes through the PI3K pathway.

Oscillatory Dynamics of p53 Genetic Network Induced by Feedback Loops and Time Delays.

DNA damage caused by γ -irradiation initiates oscillatory expression of the p53 genetic network. Although many studies revealed the effects of the p53-Mdm2 circuit on p53 dynamics, a few studies explored the contribution of upstream kinases to p53 oscillation. In this paper, an integrated mathematical model of the p53 network in response to γ -irradiation is studied, which consists of five basic components, two ubiquitous time delays, and two negative feedback loops. It is found that recurrent p53 pulses are externally initiated by ataxia telangiectasia mutated (ATM), and the negative feedback loop formed between ATM and p53, via Wip1, plays a dominant role in generating p53 oscillation. In addition, p53 oscillation requires not only an appropriate Mdm2 negative strength but also a threshold level of Wip1 negative strength. Furthermore, the time delays required for transcription and translation of Mdm2 and Wip1 proteins are essential for p53 oscillation. In particular, the critical value of time delay for inducing oscillation and the properties of delay-driven Hopf bifurcation are theoretically analyzed. As expected, the results are clearly in consistence with biological experiments and observations.

Contribution of time delays to p53 oscillation in DNA damage response.

Although the oscillatory dynamics of the p53 network have been extensively studied, the understanding of the mechanism of delay-induced oscillations is still limited. In this paper, a comprehensive mathematical model of p53 network is studied, which contains two delayed negative feedback loops. By studying the model with and without explicit delays, the results indicate that the time delay of Mdm2 protein synthesis can well control the pulse shape but cannot induce p53 oscillation alone, while the time delay required for Wip1 protein synthesis induces a Hopf bifurcation to drive p53 oscillation. In addition, the synergy of the two delays will cause the p53 network to oscillate in advance, indicating that p53 begins the repair process earlier in the damaged cell. Furthermore, the stability and bifurcation of the model are addressed, which may highlight the role of time delay in p53 oscillations.

Frailty as a Predictor of All-Cause Mortality Among Older Nursing Home Residents: A Systematic Review and Meta-analysis.

OBJECTIVES: We performed a meta-analysis based on prospective cohort studies to synthesize the pooled risk effect and to determine whether frailty is a predictor of all-cause mortality. DESIGN: Systematic review and meta-analysis. SETTING: PubMed, EMBASE, and the Cochrane Library were systematically searched in October 2018. A random effects model was applied to combine the results according to the heterogeneity of the included studies. PARTICIPANTS: Older nursing home residents. MEASUREMENTS: Mortality risk due to frailty. RESULTS: Fourteen studies (9076 participants) were included in this meta-analysis. Pooled results demonstrated that nursing home residents with frailty were at an increased risk of mortality [pooled hazards ratio (HR) = 1.88, 95% confidence interval (CI) = 1.57, 2.25, I2 = 47.8%, P < .001] compared to those without frailty. Results of subgroup analyses showed that frailty was significantly associated with the risk of mortality among older nursing home residents when using FRAIL-NH (pooled HR = 2.10, 95% CI = 1.60-2.77, P < .001) and Frailty Index (pooled HR = 1.74, 95% CI = 1.40-2.18, P < .001) to define frail people, whereas when using the diagnosis criteria of CSHA-CFS for frailty, the pooled HR was 2.82 (95% CI = 0.79-10.10, P = .111). In addition, the subgroup analysis for length of follow-up showed that studies with a follow-up period of 1 year or more (pooled HR = 1.83, 95% CI = 1.52, 2.21, P < .001) reported a significantly higher rate of mortality among individuals with frailty, compared to those without frailty. Similar results were also found in studies with a follow-up period of less than 1 year (pooled HR = 2.67, 95% CI = 1.43, 5.00, P = .002). CONCLUSIONS AND IMPLICATIONS: Frailty is a significant predictor of all-cause mortality in older nursing home residents. Therefore, there is an urgent need to screen for frailty in nursing home residents and carry out appropriate multidisciplinary intervention strategies to prevent poor outcomes and reduce the rate of mortality among older nursing home residents.

Chest-compression-only versus conventional cardiopulmonary resuscitation by bystanders for children with out-of-hospital cardiac arrest: A systematic review and meta-analysis.

BACKGROUND: For children with out-of-hospital cardiac arrest, previous observational studies regarding chest-compression-only CPR (CC-CPR) versus conventional CPR yielded inconsistent results. We aimed to summarize the current evidence and compare the outcomes after CC-CPR with those after conventional CPR by bystanders in children with out-of-hospital cardiac arrest. METHODS: Observational studies that compared CC-CPR to conventional CPR for children with out-of-hospital cardiac arrest were identified through systematic searches of three databases (PubMed, EMBASE, and the Cochrane Library). The primary outcome was 30-day survival after hospital discharge. STATA 11.0 was used for data analysis. RESULTS: Five studies with 14,427 participants were included. Pooled results indicated that children who received conventional CPR had a higher 30-day survival than those who received CC-CPR (odds ratio, 1.49; 95% confidence interval [CI], 1.27-1.74). Moreover, conventional CPR led to a higher 30-day neurologically intact survival compared to CC-CPR (odds ratio, 1.63; 95%CI, 1.30-2.04). Subgroup analyses showed that the higher survival associated with conventional CPR was only significant in children who had cardiac arrest with non-cardiac causes (odds ratio, 1.77; 95% CI, 1.30-2.40). CONCLUSIONS: Children who receive conventional CPR for out-of-hospital cardiac arrest may have better outcomes than those who receive CC-CPR. Due to the limited number of studies and lack of randomized trials included in this meta-analysis, more evidence is needed to confirm our findings.