A method was developed for determination of thirteen amines including seven aliphatic amines, two heterocyclic amines and four aromatic amines in atmospheric particulate matter (PM) by gas chromatography-mass spectrometry (GC-MS). Samples were ultrasonically extracted with ultra-pure water and derivatized with benzenesulfonyl chloride (BSC) under alkaline conditions. The derivatives were extracted with dichloromethane and then detected by GC-MS using DB-5MS chromatographic column. The method detection limit (S/N=3) and quantitation limit (S/N=10) were 0.00008-0.017 μg/mL and 0.00026-0.0565 μg/mL respectively, and the correlation coefficients were 0.9903-0.9996, which indicated that the standard curve had good linear correlation. In addition, the relative standard deviation was less than 30％ and the average recovery was 54.4％-159.7％ except for methylamine and benzylamine at spiked level of 1.0 μg/mL, showing high precision and accuracy. 9 kinds of amines were detected in the PM2.5 samples collected in Guangzhou city by this method, among which dimethylamine and butylamine accounted for 90％ of the total nine amines, which indicated that they were primary amines in PM2.5; while propylamine exhibited the lowest level in PM2.5 with the concentration less than 1.0 ng/m3.

Volatility can influence the lifetime of particles in the atmosphere, and provide useful information on the formation of secondary aerosol. The previous studies generally utilized thermodenuder ( TD ) to investigate the volatility behavior of particles. Using TD, semivolatile species are vaporized at different temperature, and the vaporized gas is adsorpted by activated charcoal. However, carbon might be emitted from activated charcoal under high temperature or activated charcoal ageing. In this study, a new method was developed for the measurement of particle volatility by coupling a thermodiluter system to an online single particle aerosol mass spectrometer ( SPAMS) . Aerosol particles were passed into two different channels, and then analyzed by SPAMS. Through Channel 1, aerosol particles were heated to different temperature by heating tube, then non-volatile particles and volatile gas entered into the diluter. After diluting and cooling by diluent air, the non-volatile particles were analyzed by SPAMS. Through Channel 2, aerosol particles were analyzed directly by SPAMS without the heating process. Particle volatility was obtained by comparing the information ( particle size, particle number and mass spectrum ) of particles through Channels 1 and 2. Laboratory tests showed that the diluter could avoid the re-condensation of volatiles to the particles. This developed method was applied in the real time measurement of individual particle volatility in the spring of Guangzhou. The results showed that these particles were primarily comprised of highly volatile and moderate volatile species.

Objective:To evaluate the relationship between preoperative mild cognitive impairment (MCI) and postoperative delirium (POD) in the patients undergoing total knee/hip arthroplasty.Methods:A total of 625 patients, aged 50-90 yr, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, undergoing total knee and hip arthroplasty under combined spinal-epidural anesthesia from September 2021 to February 2022, were included.One day before surgery, the cognitive function was assessed using the Mini-Mental State Examination and the Montreal Cognitive Assessment scale.The patients were divided into non-MCI group (NMCI group) and MCI group according to the diagnostic criteria of MCI.The concentrations of amyloid beta 40 (Aβ40), amyloid beta 42 (Aβ42), total tau protein (T-tau) and phosphorylated tau protein (P-tau) in cerebrospinal fluid (CSF) were detected by enzyme-linked immunosorbent assay.The development of POD was assessed on 1-7 days after operation.The relationship between MCI and POD and relationship of concentrations of β40, Aβ42, T-tau and P-tau in CSFA, Aβ40/T-tau ratio, Aβ42/P-tau ratio and Aβ42/T-tau ratio with POD and MCI were analyzed using binary logistic regression.Results:Compared with NMCI group, the incidence of POD was significantly increased, the concentrations of Aβ42 and Aβ40 in CSF, Aβ40/T-tau ratio, Aβ42/P-tau ratio and Aβ42/T-tau ratio were decreased, and T-tau and P-tau concentrations in CSF were increased in MCI group ( P<0.05).The results of logistic regression analysis showed that before and after adjusting for confounding factors, increased MCI and concentrations of P-tau and T-tau in CSF were the risk factors for POD, and increased concentrations of Aβ42 and Aβ40 in CSF, Aβ40/T-tau ratio, Aβ42/P-tau ratio and Aβ42/T-tau ratio were protective factors for POD ( P<0.05); elevated concentrations of P-tau and T-tau in CSF were risk factors for MCI before and after adjusting for confounding factors, and increased concentrations of Aβ4 in CSF, Aβ40/T-tau ratio, Aβ42/P-tau ratio, and Aβ42/T-tau ratio were protective factors for MCI after adjusting for confounding factors ( P<0.05). Conclusions:Preoperative MCI are risk factors for POD in the patients undergoing total knee/hip arthroplasty.

Objective:To evaluate the relationship between preoperative serum albumin concentrations and postoperative delirium (POD) in the patients undergoing total knee/hip arthroplasty.Methods:Five hundred patients of both sexes, aged 50-90 yr, with body mass index of 50-80 kg, of American Society of Anesthesiologists Physical Status classification Ⅰ or Ⅱ, undergoing elective total knee or hip replacement under combined spinal-epidural anesthesia in our hospital from December 2021 to December 2022, were selected. Cerebrospinal fluid (CSF) samples were collected after successful subarachnoid puncture for determination of amyloid-beta 42 (Aβ42), total tau protein (T-tau) and phosphorylated tau protein (P-tau) concentrations using enzyme-linked immunosorbent assay. Confusion Assessment Method and Memorial Delirium Assessment Scale were used to evaluate the occurrence and severity of POD at 1-7 days after surgery (or before discharge), and the patients were divided into POD group and non-POD group (NPOD group). Logistic regression analysis was used to identify the risk factors for POD. The accuracy of plasma albumin concentration and CSF biomarker concentration in predicting POD was evaluated by the receiver operating characteristic (ROC) curve, and the mediating effect of CSF biomarker was analyzed.Results:A total of 343 patients were finally enrolled in the study, and the incidence of POD was 23.3%. There were statistically significant differences in age, preoperative plasma albumin concentration and Memorial Delirium Assessment Scale score in POD group as compared with NPOD group ( P<0.05). Before and after adjusting for confounding factors, decreased plasma albumin and increased concentrations of P-tau and T-tau in CSF before operation were the risk factors for POD, and increased concentrations of Aβ42, Aβ42/P-tau and Aβ42/T-tau ratio in CSF were protective factors for POD. The area under the ROC curve of preoperative plasma albumin concentrations in predicting POD was 0.668, and the area under the ROC curve of preoperative plasma albumin concentrations combined with CSF biomarker concentrations in predicting POD was 0.810 ( P<0.05). The direct effect of plasma albumin on POD was -0.009 869 2, the total effect was 0.029 443 7, and the mediating effect of P-tau accounted for 33.53% of the total effect. Conclusions:Decreased preoperative plasma albumin concentration is a risk factor for POD, and P-Tau in CSF serves as a key mediator in the relationship between serum albumin concentrations and postoperative delirium in the patients undergoing total knee/hip arthroplasty.

Objective:To evaluate the relationship between the preoperative neutrophil/lymphocyte ratio(NLR) and postoperative delirium (POD)in elderly patients.Methods:Nine hundred and thirty-seven patients, undergoing elective knee or hip arthroplasty under combined spinal and epidural anesthesia, in whom Mini-Mental State Examination was completed at 1 day before operation, with Mini-Mental State Examination score≥24, were selected. Elbow venous blood samples were collected before surgery, neutrophils and lymphocytes were counted, and the ratio of neutrophils to lymphocytes was calculated.Cerebrospinal fluid (CSF) 2 ml was extracted after successful spinal-epidural puncture for measurement of preoperative amyloid beta40 (Aβ40), amyloid beta42 (Aβ42), total Tau (T-tau), and phosphorylated Tau (P-tau) by enzyme-linked immunosorbent assay. POD was assessed by Confusion Assessment Method, and the severity of POD was assessed by the Memorial Delirium Assessment Scale.The logistic regression equation was used to identify the risk factors for POD, and the mediating effect of CSF biomarkers was analyzed. Sensitivity analysis was used to test the stability of the results. The receiver operating characteristic curve was introduced, and the area under the curve was calculated to evaluate the accuracy of preoperative NLR in predicting POD.Results:A total of 853 patients were finally enrolled in this study, and 17.4% patients developed POD. Logistic regression analysis showed that the increased levels of NLR ( OR 1.141, 95% confidence interval [ CI] 1.033-1.260, P=0.010), P-tau in CSF ( OR 1.093, 95% CI 1.076-1.110, P<0.001) and T-tau in CSF( OR 1.003, 95% CI 1.001-1.005, P<0.001) were risk factors for POD, while the increased level of Aβ42 in CSF( OR 0.998, 95% CI 0.997-1.000, P=0.028) was a protective factor for POD after adjusting for multiple confounding factors. Analysis of mediating effect: T-tau and P-tau in CSF were the mediating factors in the relationship between NLR and POD with the mediating effects of 0.011 9 and 0.020 0 respectively, and the proportion of mediating effect was 46.1% and 53.1% respectively.The receiver operating characteristic curve showed that the area under the curve of NLR and combination of NLR and CSF biomarkers in predicting POD was 0.711 and 0.939 respectively. Conclusions:Increased preoperative NLR level is a risk factor for POD, and combination of NLR and CSF biomarkers shows a higher accuracy in predicting POD. T-tau and P-tau in CSF serve as the key mediators in the relationship between NLR and POD.

Objective:To evaluate the relationship between preoperative levels of serum uric acid (SUA) and postoperative delirium (POD).Methods:Seven hundred and fifty patients of either sex, aged 50-90 yr, with American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective knee replacement under spinal-epidural anesthesia, were selected.Venous blood samples were collected before anesthesia and levels of SUA were determined by enzyme-coupled assay.L 3-4 was selected as the puncture space, and the cerebrospinal fluid (CSF) specimens were obtained from the subarachnoid space for determination of concentrations of β-amyloid 42, total tau (t-tau) and phosphorylated tau (p-tau) by enzyme-linked immunosorbent assay.The patients were divided into hyperuric acid group (group HS) and non-hyperuric acid group (group NS) according to clinical diagnostic criteria of hyperuricemia, and into POD group (group POD) and non-POD group (group NPOD) according to the occurrence of POD.Logistic regression was used to identify the risk factors for POD.The mediating effect of CSF biomarkers was analyzed.The efficacy of SUA and CSF biomarker concentrations in predicting POD was evaluated using the receiver operating characteristic curve. Results:A total of 699 patients were finally enrolled in the study, and the incidence of POD was 21.5%.The results of logistic regression analysis after adjusting for multiple confounding factors, such as age, sex, years of education, Mini-Mental State Examination score, smoking history, drinking history, hypertension and diabetes history, showed that increased concentrations of SUA and p-tau and t-tau in CSF were risk factors for POD ( P<0.05). The results of mediation analysis showed that the concentrations of p-tau and t-tau in CSF were the mediating factors of the relationship between SUA and POD, with mediating effects of 0.000 301 (95% confidence interval 0-0.000 152) and 0.000 236 (95% confidence interval 0-0.000 092), respectively, and the intermediary proportion were 14.9% and 11.7%, respectively.The area under the receiver operating characteristic curve of SUA in predicting POD was 0.774 ( P<0.05). Conclusions:Increased preoperative SUA is a risk factor for POD, and the accuracy of predicting POD is high, and concentrations of p-tau and t-tau in CSF are mediators of SUA affecting POD.

Liver is the central hub regulating energy metabolism during feeding-fasting transition. Evidence suggests that fasting and refeeding induce dynamic changes in liver size, but the underlying mechanisms remain unclear. Yes-associated protein (YAP) is a key regulator of organ size. This study aims to explore the role of YAP in fasting- and refeeding-induced changes in liver size. Here, fasting significantly reduced liver size, which was recovered to the normal level after refeeding. Moreover, hepatocyte size was decreased and hepatocyte proliferation was inhibited after fasting. Conversely, refeeding promoted hepatocyte enlargement and proliferation compared to fasted state. Mechanistically, fasting or refeeding regulated the expression of YAP and its downstream targets, as well as the proliferation-related protein cyclin D1 (CCND1). Furthermore, fasting significantly reduced the liver size in AAV-control mice, which was mitigated in AAV Yap (5SA) mice. Yap overexpression also prevented the effect of fasting on hepatocyte size and proliferation. Besides, the recovery of liver size after refeeding was delayed in AAV Yap shRNA mice. Yap knockdown attenuated refeeding-induced hepatocyte enlargement and proliferation. In summary, this study demonstrated that YAP plays an important role in dynamic changes of liver size during fasting-refeeding transition, which provides new evidence for YAP in regulating liver size under energy stress.