Objective To investigate the occurrence status quo and influencing factors of low muscle mass(LMM)among young and middle-aged health examination population.Methods The young and middle-aged people undergoing the body composition analysis in this hospital from January to December 2023 were selected as the study subjects.The general data,body composition indices and biochemical indicators were col-lected.The body composition analysis was performed by the bioelectrical impedance analysis(BIA).LMM was diagnosed based on the skeletal muscle index.The univariate and multivariate logistic regression were used to analyze the influencing factors of LMN occurrence in the young and middle-aged health examination population.The receiver operating characteristic(ROC)curve and the area under the curve(AUC)were em-ployed to evaluate the predictive value of each indicator.Results A total of 2 351 people undergoing the phys-ical examination were included,aged 18-49 years old,366(15.57％)cases of LMM were detected out.The skeletal muscle index,sex,age,age group distribution,body mass index(BMI),body fat percentage(BFP),body fat percentage grade,visceral fat area(VFA),AST/ALT,Hb,serum creatinine,blood uric acid,HbA1c,fasting blood glucose,TC,LDL-C,HDL-C,TG and triglyceride-glucose index(TyG)had statistical differences between the LMM group and normal group(P＜0.05).Multivariate logistic regression revealed that the sex(OR=2.606,95％CI:1.755-3.870),BMI(OR=0.579,95％CI:0.538-0.623),BFP(OR=5.885,95％CI:4.176-8.292)and VFA(OR=0.955,95％CI:0.944-0.967)were the influencing factors for the LMM oc-currence in the young and middle-aged people undergoing the physical examination(P＜0.001).The ROC a-nalysis showed the AUC values of the sex,BMI,BFP and VFA for predicting LMM were 0.580,0.821,0.636 and 0.715 respectively,in which the predictive value of BMI was highest.Conclusion The population of fe-male,low BMI,high BFP and low VFA maybe the high-risk groups for LMM.The health management for the above-mentioned groups needs to be strengthened.

BACKGROUND:The temporal and spatial expression of fibroblast growth factor receptors 1 and 2 remains a controversial issue during kidney development,so the relationship between them and kidney development remains unclear. OBJECTIVE:To observe the dynamic expression of fibroblast growth factor receptors 1 and 2 during kidney development of mice,and to investigate the relationship between them and kidney development. METHODS:The kidneys of fetal mice[embryotic days(E)12,14,16,and 18]and neonatal mice[neonatal days(N)1,3,7,14,24,and 40]were selected to examine the temporal and spatial expression of fibroblast growth factor receptors 1 and 2 by immunohistochemistry method in kidney tissues,and quantitative analysis was performed using western blot assay. RESULTS AND CONCLUSION:(1)Immunohistochemistry showed that fibroblast growth factor receptor 1 was mainly localized in metanephric tissue surrounding the tip of the ureteral bud at E12.Subsequently,fibroblast growth factor receptor 1 was expressed in immature renal corpuscles at various stages,some distal convoluted tubules and capillary loops.The positive site was mainly concentrated in the generative region.Fibroblast growth factor receptor 2 was initially expressed in both ureteral buds and metanephric tissue.Fibroblast growth factor receptor 2 was localized in immature renal corpuscles,distal tubules,collecting ducts and thin segments of medullary loops with kidney development.However,the expression of renal corpuscles was weak.(2)Stereology and western blot assay showed that the expression of fibroblast growth factor receptor 1 was high before birth and gradually decreased after birth,while the expression was very low after N7 day.The expression level of fibroblast growth factor receptor 2 increased gradually with the kidney development and tended to be stable after N7 day.(3)The results exhibit that fibroblast growth factor receptors 1 and 2 are expressed spatially and temporally during kidney development.It is speculated that fibroblast growth factor receptors 1 and 2 may influence nephron development and maturation,and fibroblast growth factor receptor 2 is critical during the formation of ureteral buds and morphology.