Objective:To investigate the correlation of mitochondrial respiration function and oxidative phosphorylation of peripheral blood mononuclear cells(PBMCs)with grip strength and muscle mass in the elderly, and to identify potential biomarkers for the diagnosis of sarcopenia.Methods:A total of 65 patients admitted to our hospital from June 2019 to August 2020 were enrolled in this study.PBMCs were extracted from subjects.Mitochondrial oxidative respiration function was assessed via the Seahorse XF24 analyzer.Grip strength was measured using a hydraulic dynamometer, and appendicular skeletal muscle mass(ASM)was estimated by dual-energy X-ray absorptiometry(DXA). Multivariate analysis was conducted by using partial correlation analysis and multiple linear regression, in order to evaluate the correlation of mitochondrial oxidative respiration function with grip strength and ASM.Results:After adjustment for gender and body mass index(BMI), partial correlation analysis showed that grip strength and ASM had a negative correlation with age( r=-0.537 and -0.390, both P<0.001); and basal respiration, maximal respiration, ATP production and spare respiratory capacity of mitochondria in PBMCs were negatively correlated with age( r=-0.558, -0.614, -0.526 and -0.582, all P<0.001), whereas grip strength and ASM were positively correlated with basal respiration, maximal respiration, ATP production, spare respiratory capacity and proton leak of mitochondria in PBMCs(grip strength: r=0.414, 0.451, 0.362, 0.420 and 0.425, P=0.002, 0.001, 0.008, 0.002 and 0.002; ASM: r=0.319, 0.368, 0.299, 0.352 and 0.279, P=0.019, 0.006, 0.028, 0.009 and 0.041). Multiple linear regression analysis showed that grip strength and ASM were positively correlated with basal respiration, maximal respiration, ATP production, spare respiratory capacity and proton leak of mitochondria in PBMCs(grip: β=0.503, 0.548, 0.452, 0.519 and 0.532, t=3.248, 3.604, 2.774, 3.301 and 3.350, P=0.002, 0.001, 0.008, 0.002 and 0.002; ASM: β=0.302, 0.355, 0.289, 0.346 and 0.271, t=2.427, 2.856, 2.263, 2.716 and 2.091, P=0.019, 0.006, 0.028, 0.009 and 0.041). Age was negatively correlated with basal respiration, maximal respiration, ATP production and spare respiratory capacity of mitochondria in PBMCs( β=-0.581, -0.654, -0.558 and -0.640, t=-4.285, -5.157, -3.938 and -4.863, all P<0.001). Multiple linear regression analysis showed that ASM and grip strength had no significant correlation with basal respiration, maximal respiration, ATP production, spare respiratory capacity or proton leak of mitochondria in PBMCs. Conclusions:Age-related mitochondrial oxidative respiration in PBMCs can reflect changes in muscle strength and muscle mass and, combined with grip strength and ASM, may be considered as a biomarker for the evaluation of sarcopenia in the elderly.

Objective:To investigate the correlation between depression risk and the test time for dual-task timed up-and-go(TUG)test in the elderly.Methods:A total of 193 elderly volunteers aged 60 years and over who lived in the Nanjing community of Jiangsu Province were recruited.The Geriatric Depression Scale(GDS)was used to screen for geriatric depression.The single-task TUG(TUG-single), TUG with additional operational tasks(TUG-manual)and TUG with additional cognitive tasks(TUG-cognitive)were tested in all subjects.The differences in test times taken to complete TUG-single, TUG-manual and TUG-cognitive tests were analyzed by ANOVA.The correlation of GDS scores with test time for TUG-single, TUG-manual, TUG-cognitive was analyzed by using Pearson's correlation.Results:The average test times for TUG-cognitive and TUG-manual tests were longer than that for TUG-single test( P<0.0001). The higher the GDS score, the longer the TUG-single test time, with a significantly positive correlation between GDS and the test time for TUG-single( r=0.2261, P=0.0016). Similarly, GDS score showed significantly positive correlations with the test time for TUG-manual( r=0.2359, P=0.0010)and the TUG-cognitive test time( r=0.1946, P=0.0067). Conclusions:The increase of depression risk is significantly and positively correlated with the prolongation of the TUG test time in the elderly.The TUG test can be used to assess the functional mobility in elderly patients with depression.

Objective:To investigate the correlation of peripheral blood relative mitochondrial DNA copy number(mtDNAcn)with intrinsic capacity and body composition, and to identify potential biomarkers for healthy aging.Methods:Clinical data of 416 patients admitted to our hospital from September 2019 to June 2021 were consecutively collected.MtDNA was extracted from peripheral blood of these subjects, and mtDNAcn was determined by a real-time fluoresence quantitative reverse transcription-polymerase chain reaction(qRT-PCR). Intrinsic capacity assessment included 5 aspects that were exercise[Morse Fall Scale(MFS), Physiological Frailty Phenotype(PFP), Sarcopenia Questionnaire(SARC-CALF), Short Physical Performance Battery(SPPB), Time Up and Go Test(TUG)]; vitality[Mini Nutritional Assessment(MNA), Multidimensional Prognostic Index(MPI)]; cognition[Mini-Mental State Examination(MMSE)scale]; psychology[Geriatric Depression Scale(GDS), Self-rating Anxiety Scale(SAS)]; sensory capacities[Cumulative Illness Rating Scale-the Comorbidity Index(CIRS-CI)]. To assess body composition, dual-energy X-ray absorptiometry was used to measure body fat, including trunk fat, total body fat, fat in the abdominal region, fat in the buttock region, and then to calculate fat index(FMI)and limb skeletal muscle mass index(ASMI).Results:Spearman correlation analysis showed that mtDNAcn had a negatively correlation with age( r=-0.176, P<0.05). After adjustment for gender and body mass index, partial correlation analysis showed mtDNAcn were still negatively correlated with age( r=-0.144, P<0.05). Furthermore, mtDNAcn was significantly correlated with 4 m gait speed, the scores of SARC-CalF, MFS, MNA, MMSE, MPI and its sub-scale's Activities of Daily Living(ADL)and Short Portable Mental Status Questionnaire(SPMSQ)( r=0.171, -0.207, -0.163, 0.221, 0.184, -0.210, 0.241, -0.269, all P<0.05). After adjustment for age, gender and body mass index, partial correlation analysis showed mtDNAcn still had a significant correlation with gait speed, the scores of MFS, MNA, MPI and SPMSQ( r=0.170, -0.170, 0.148, -0.242, -0.188, all P<0.05). In addition, the Spearman correlation analysis showed that mtDNAcn was positively correlated with FMI, trunk fat, total body fat, abdominal fat and fat in the buttock region( r=0.168, 0.143, 0.175, 0.116, 0.199, all P<0.05). However, after adjustment for age and gender, mtDNAcn was only correlated with FMI, total body fat, fat in the buttock region( r=0.126, 0.131, 0.127, all P<0.05). On the other hand, multiple linear regression analysis showed that mtDNAcn was significantly correlated with age, gait speed, FMI, total body fat, fat in the buttock region, the scores of MFS, PFP, MNA and MPI( β=-0.191, 0.156, 0.126, 0.131, 0.125, -0.119, -0.145, 0.151, -0.171, all P<0.05). Conclusions:MtDNAcn is correlated with physical function, frailty, nutrition, falling, cognition and body composition, and may be considered as a biomarker for the evaluation of the locomotion and vitality of human intrinsic capacity.