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Objective To compare the discrepancies among results of three commonly used laboratory direct test methods for maximal oxygen uptake(VO2max),explore their linear regression relationships,mutual predictability and comparability.Methods Using a quasi-experimental design of cluster sampling and within-group interaction design,20 male cross-country skiers were tested for VO2max using the Bruce protocol(Method 1),90-second incremental load exercise on power bicycle(Method 2),and 1-minute incremental load exercise on treadmill(Method 3),with an interval of one week.The indepen-dent and dependent variable were the three VO2max test methods and the VO2max,respectively.Results Significant differences were found in the average VO2max of the three test results,with the value mea-sured by Method 1 ranking the first,followed by that assessed by Method 3 and Method 2(P<0.05).Moreover,the frequency of individual differences in the results of the three methods showed that the VO2max of Method 1 was about 6 and 3 ml/min·kg higher than that measured by Method 2 and 3.However,at the same treadmill speed,the average blood lactate evaluated using Method 3 was higher than Method 1,and the speed reached aerobic and anaerobic thresholds about one speed unit(1 km/h)lower than Method 1.Meanwhile,linear regression analyses of the test results between Method 1 and 2,as well as Method 1 and 3 showed that both the regression models and coefficients were statis-tically significant(P<0.001),with the R-squared values of 9.25 and 9.05,respectively.Conclusion The Bruce protocol performs best in assessing the maximum value of the athlete's VO2max phase,whose results have linear regression relationships with the other two methods,and can be used for pre-dicting their results.Moreover,athletes of different events and levels can choose different VO2max test methods accordingly.Lastly,the speed and heart rate ranges corresponding to the aerobic and anaero-bic thresholds can serve as an effective and convenient method to control the training intensity.
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Objective:To explore the key genes related to the development, progression and prognosis of acute myeloid leukemia (AML) based on bioinformatics, and to analyze their functions.Methods:The chip expression profile GSE84881 data set of AML patients including 19 AML samples and 4 normal tissue samples was downloaded from the gene expression omnibus (GEO) database. GEO online tool GEO2R was used to screen the differentially expressed genes (DEG). The DAVID online database was used to make gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis of DEG. The STRING online database was used to analyze the protein interaction (PPI) network of DEG, and the key genes were screened by using the Cytoscape software. The weighted gene co-expression network analysis (WGCNA) was used to build co-expressed network and obtain the central genes.LC-Bio online platform was used to construct Venn diagram and the key genes and central genes in PPI were crossed to finally obtain the true key genes. RNA-seq datasets GSE2191 and GSE90062 of human tissues were downloaded from GEO database to verify the screened key genes. Kaplan-Meier method was used to analyze the effects of key genes on the overall survival (OS) of AML based on the data of GEPIA database.Results:A total of 247 DEG were identified in GSE84881 data set, including 112 up-regulated genes and 135 down-regulated genes. According to the results of GO enrichment analysis, 247 DEG were mainly enriched in the regulation of signal transduction and cell proliferation in the biological process (BP); the cell composition (CC) revealed that these genes were mainly involved in the cytoplasm and exosomes; the molecular function (MF) analysis showed that these genes were mainly enriched in protein binding and calcium binding. Further KEGG pathway enrichment analysis showed that these 247 DEG were mainly involved in NOD-like receptor signal pathway and interleukin 17 (IL-17) signal pathway. And then the 12 key genes were obtained from PPI. WGCNA software was used to screen 13 central genes from GSE84881 dataset and finally 1 real key gene EGF was obtained after taking intersection. Kaplan-Meier method showed that OS time of AML patients in EGF high expression group was decreased than that in EGF low expression group, and the difference was statistically significant( P = 0.044). Conclusions:EGF may be an important diagnosis and treatment target of AML and may become a potential biomarker for clinical treatment and prognosis prediction of AML.