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Objective To detect the concentrations of choline acetyltransferase (ChAT) and cholinesterase (ChE) in cerebrospinal fluid of elderly patients and explore their relationship with postoperative delirium (POD). Methods One hundred and eighty-three patients who underwent total knee/total hip arthroplasty at Qingdao Municipal Hospital from September 2018 to August 2019 were included. All patients underwent total knee or total hip arthroplasty, using combined spinal-epidural anesthesia. After subarachnoid puncture, 2 mL of cerebrospinal fluid (CSF) was extracted. Enzyme-linked immunosorbent assay was used to detect the concentration of ChAT, ChE, tumor necrosis factor-α(TNF-α) and interleukin-6 (IL-6) in CSF, and spectrophotometry was used to detect the activity of ChAT and ChE in CSF. The occurrence of POD was assessed using the Confusion Assessment of Method (CAM) after surgery. Results Among 183 patients, 157 cases without POD were as non-POD group and 26 cases with POD were as POD group, with an incidence rate of 14.21%. In the POD group, the preoperative CSF ChE concentration ［(31.99±2.78) vs (40.89±4.19)〖LM〗 ng/mL, t=13.915, P＜0.01］ significantly reduced, while ChAT ［(1.26±0.12) vs (0.86±0.15) ng/mL, t=12.920, P＜0.01］, 〖JP2〗TNF-α［(17.19±1.32) vs (12.29±1.64) pg/mL, t=14.467, P＜0.01］, 〖JP〗and IL-6［(33.98±5.02) vs (16.98±3.41) pg/mL, t=16.643, P＜0.01］ significantly increased compared to the non-POD group. In the POD group, the preoperative CSF ChE activity significantly reduced ［(4.28±0.52) vs (5.25±0.26) u/mL, t=9.321, P＜0.01］, while ChAT activity significantly increased ［(0.36±0.05) vs (0.27±0.03) u/mL, t=8.916, P＜0.01］ compared to the non-POD group. Conclusion The high activity of ChAT and low activity of ChE in CSF are related to the occurrence of POD in elderly patients, with cholinergic degradation closely related to its occurrence."

The nuclear double walled vessel is a common structural form of high temperature reactor body, which assumes the dual safety functions of primary pressure boundary and primary coolant "defense in depth" containment. However, the temperature of the inner container changes dramatically under transient conditions, and the thermal conductivity of the inner and outer containers is poor. The temperature difference in the radial direction (between the inner and outer containers) and the height direction of the double walled vessel is large, and the temperature of the double walled vessel is easy to appear in the phenomenon that the temperature of the inside is higher than that of the outside in the heating stage and the temperature of the inside is lower than that of the outside in the cooling stage. The temperature distribution of the double walled vessel is not uniform and the thermal deformation is not coordinated, the thermal ratchet effect is a possible important failure mode for the main discontinuous position of the nuclear double walled vessel. In this paper, a reasonable axisymmetric finite element model of a nuclear double walled vessel and its supporting structure was established, and the accuracy of the finite element model's temperature and stress analysis was verified. The temperature field under transient conditions was calculated by considering the three heat transfer modes of conduction, radiation and convection. The nonlinear stress and strain response of the structure under the heat-mechanical cyclic load was analyzed by considering the elastic-plastic of the material and geometric large deformation of the structure. The law and characteristics of ratchet effect distribution were studied based on the above analysis results. The results show that the thermal ratchet effect is significant, which is the main failure mode of this type of vessel. The thermal ratchet sensitive zone which locates at the main connection position of the double walled vessel of the supporting structure has the characteristics of multi-point distribution, and different parts of the inside and the outside are involved among which the connection position of the inner container's head and supporting ring is more sensitive. The plastic strain accumulation behavior in the danger zone mainly appears in the cooling stage of the cyclic temperature load, and the strain increment gradually becomes stable with the increase of the number of cycles. It is pointed out that the thermal ratchet effect is an important problem to be paid attention to in the design of nuclear double walled vessels and the nonlinear analysis method is an effective method to solve this problem. This study can provide important method guidance for the thermal ratchet' design of nuclear double walled vessels, the optimal design of operating parameters of primary circuit and the arrangement of strain monitoring points.

Homeostasis maintains serum metabolites within physiological ranges. For glucose, this requires insulin, which suppresses glucose production while accelerating its consumption. For other circulating metabolites, a comparable master regulator has yet to be discovered. Here we show that, in mice, many circulating metabolites are cleared via the tricarboxylic acid cycle (TCA) cycle in linear proportionality to their circulating concentration. Abundant circulating metabolites (essential amino acids, serine, alanine, citrate, 3-hydroxybutyrate) were administered intravenously in perturbative amounts and their fluxes were measured using isotope labelling. The increased circulating concentrations induced by the perturbative infusions hardly altered production fluxes while linearly enhancing consumption fluxes and TCA contributions. The same mass action relationship between concentration and consumption flux largely held across feeding, fasting and high- and low-protein diets, with amino acid homeostasis during fasting further supported by enhanced endogenous protein catabolism. Thus, despite the copious regulatory machinery in mammals, circulating metabolite homeostasis is achieved substantially through mass action-driven oxidation.

Mammalian organs are nourished by nutrients carried by the blood circulation. These nutrients originate from diet and internal stores, and can undergo various interconversions before their eventual use as tissue fuel. Here we develop isotope tracing, mass spectrometry, and mathematical analysis methods to determine the direct sources of circulating nutrients, their interconversion rates, and eventual tissue-specific contributions to TCA cycle metabolism. Experiments with fifteen nutrient tracers enabled extensive accounting for both circulatory metabolic cycles and tissue TCA inputs, across fed and fasted mice on either high-carbohydrate or ketogenic diet. We find that a majority of circulating carbon flux is carried by two major cycles: glucose-lactate and triglyceride-glycerol-fatty acid. Futile cycling through these pathways is prominent when dietary content of the associated nutrients is low, rendering internal metabolic activity robust to food choice. The presented in vivo flux quantification methods are broadly applicable to different physiological and disease states.