Objective:To investigate the clinical features and associated influencing factors of cognitive impairment in middle-aged and elderly Chinese adult patients undergoing maintenance hemodialysis (HD).Methods:A cross-sectional study was conducted among HD patients from 11 centers in Beijing city from April 2017 to June 2017. A neuropsychological battery covering domains of attention/processing speed, executive function, memory, language, and visuospatial function was applied in cognitive function assessment. Patients were classified as normal cognitive function group and cognitive impairment group according to the fifth version of the diagnostic and statistical manual of mental disorders criteria (DSM-V). Multivariate binary logistic regression was used to analyze the independent influencing factors of cognitive impairment. Results:A total of 613 HD patients were included in the study, and the prevalence of cognitive impairment was 80.91% (496/613). Attention impairment (81.05%) and memory impairment (63.51%) were the most common impaired domains, and 79.23% was concomitant impairment across two or more cognitive domains among those with cognitive impairment. Compared with the patients in the normal cognitive function group, the patients in the cognitive impairment group had senior age, longer dialysis vintage, higher proportion of diabetes, hypertension, and stroke, higher level of serum intact parathyroid hormone (iPTH), lower education level, and lower urea clearance index (Kt/V) (all P<0.05). Factors were independently associated with cognitive impairment including increasing age ( OR=1.110, 95% CI 1.072-1.150, P<0.001), education time>12 years (with education time<6 years as reference, OR=0.323, 95% CI 0.115-0.909, P=0.032), history of diabetes ( OR=2.151, 95% CI 1.272-3.636, P=0.004), history of stroke ( OR=2.546, 95% CI 1.244-5.210, P=0.011), increased dialysis vintage ( OR=1.016, 95% CI 1.010-1.022, P<0.001), reduced Kt/V( OR=0.008, 95% CI 0.002-0.035, P<0.001), and increased iPTH level ( OR=1.002, 95% CI 1.002-1.003, P=0.012). Conclusions:The prevalence of cognitive impairment in middle-aged and elderly adult Chinese patients undergoing HD is high. Memory and attention are the most commonly impaired domains. Increasing age, low education level, history of diabetes and stroke, increased dialysis vintage, reduced Kt/V and increased serum iPTH are the independent influencing factors associated with cognitive impairment.

Objective:To investigate the association between cognitive impairment and all-cause mortality in middle and elderly adult patients undergoing maintenance hemodialysis (HD).Methods:A prospective cohort study was conducted. Patients from 11 HD centers in Beijing between April and June 2017 were enrolled. Baseline data were collected, and a series of neuropsychological batteries covered 5 domains of cognitive function were applied for the assessment of cognitive function. The patients were then classified as normal and cognitive impairment groups according to the fifth version of the Diagnostic and Statistical Manual of Mental Disorders criteria (DSM-V) and followed-up until June 2018. The clinical characteristics of the two groups of patients were compared. Kaplan-Meier survival analysis was used to compare the difference in the cumulative survival rate between the two groups. Multivariate Cox regression model was used to analyze the independent influencing factors of all-cause mortality, to determine the relationship between cognitive impairment and different cognitive domain impairments and all-cause death.Results:A total of 613 patients were enrolled, of which 496(80.91%) patients had cognitive impairment. Compared with the normal cognitive function group, the patients in the cognitive impairment group tended to be older, longer dialysis vintage, a higher proportion of diabetes, hypertension, and stroke, increased serum iPTH level, and lower education level and urea clearance index (Kt/V) (all P<0.05). After (49.53±8.42) weeks of follow-up, Kaplan-Meier survival analysis showed that the cumulative survival rate of cognitive impairment group was significantly lower than that of cognitive normal group (Log-rank χ2=8.610, P=0.003). Multivariate Cox regression analysis showed that history of diabetes ( HR=2.742, 95% CI 1.598-4.723, P<0.001), coronary heart disease ( HR=1.906, 95% CI 1.169-3.108, P=0.010), dialysis vintage (every increase of 1 month, HR=1.007, 95% CI 1.003-1.011, P=0.001), serum level of albumin (every increase of 1 g/L, HR=0.859, 95% CI 0.809-0.912, P<0.001), cognitive impairment ( HR=2.719, 95% CI 1.088-6.194, P=0.032) were independently associated with all-cause mortality. Multivariate Cox regression analysis on different cognitive domains also indicated that memory impairment ( HR=2.571, 95% CI 1.442-4.584, P<0.001), executive function impairment ( HR=3.311, 95% CI 1.843-5.949, P=0.001) and three, four, five domains combined impairment ( HR=5.746, 95% CI 1.880-17.565, P=0.002; HR=12.420, 95% CI 3.690-41.802, P<0.001; HR=13.478, 95% CI 3.381-53.728, P<0.001) were independently related to all-cause mortality. Conclusions:Cognitive impairment is an independent risk factor of all-cause mortality in middle and elderly adult patients undergoing maintenance hemodialysis, and the risk is significantly increased in patients with the impairment of the domains of memory, executive function, or in the combination of three to five cognitive domains.

α-Amino acid ester acyltransferase (Aet) catalyzes the L-alanyl-L-glutamine forming reaction from L-alaine methylester hydrochloride and L-glutamine. In this study, the recombinant Escherichia coli saet-QC01 was used to express the α-amino acid acyltransferase, and its expression conditions were optimized. The recombinant protein was separated and purified by Ni-NTA affinity chromatography, and its enzymatic properties and catalytic applications were studied. The induction conditions suitable for enzyme production optimized were as follows: The temperature was 20 ℃, the induction stage (OD₆₀₀=2.0-2.5), IPTG concentration was 0.6 mmol/L, induction time was 12 h. The optimal reaction conditions of α-amino acid acyltransferase were 27 ℃, pH 8.5, it was most stable between pH 7.0 and 8.0 and relatively stable in an acidic environment, and low concentration of Co²⁺ or EDTA could promote the enzyme activity. Under optimal reaction conditions, 600 mmol/L of L-alaine methylester hydrochloride and 480 mmol/L of L-glutamine, the yield of L-alanyl-L-glutamine reached 78.2 g/L and productivity of 1.955 g/L/min, the conversion rate reached 75.0%. α-Amino acid ester acyltransferase has excellent acid-basei resistance, high catalytic efficiency. These characteristics suggest its application prospects in the industrial production.