Pyrolysis Kinetic Properties of Thermal Insulation Waste Extruded Polystyrene by Multiple Thermal Analysis Methods

Extruded polystyrene (XPS) is a thermal insulation material extensively applied in building systems. It has attracted much attention because of outstanding thermal insulation performance, obvious flammability shortcoming and potential energy utilization. To establish the reaction mechanism of XPS’s pyrolysis, thermogravimetric experiments were performed at different heating rates in nitrogen, and multiple methods were employed to analyze the major kinetics of pyrolysis. More accurate kinetic parameters of XPS were estimated by four common model-free methods. Then, three model-fitting methods (including the Coats-Redfern, the iterative procedure and masterplots method) were used to establish the kinetic model. Since the kinetic models established by the above three model-fitting methods were not completely consistent based on different approximations, considering the effect of different approximates on the model, the reaction mechanism was further established by comparing the conversion rate based on the model-fitting methods corresponding to the possible reaction mechanisms. Finally, the accuracy of the above model-fitting methods and Particle Swarm Optimization (PSO) algorithm were compared. Results showed that the reaction function g(α) = (1 − α)⁻¹ − 1 might be the most suitable to characterize the pyrolysis of XPS. The conversion rate calculated by masterplots and PSO methods could provide the best agreement with the experimental data.     

The enigmatic role of cholinergic reflex in the pathogenesis of Chagas disease

This study evaluated the inflammatory process in the colons of mice infected with Trypanosoma cruzi QM2 strain, through the analysis of muscle reactivity and the measurement of butyrylcholinesterase (BuChE) in plasma. “Swiss” mice were infected with T. cruzi QM2 strain and after 15 (G15), 30 (G30), 60 (G60), 90 (G90), and 210 (G210) days, each group had blood collected for the measurement of butyrylcholinesterase plasma concentrations ([BuChE]), a measure which functioned as an indicator of plasmatic Ach levels. All groups, except G15, had a segment of proximal colon removed to assess muscle reactivity to acetylcholine (Ach) and noradrenaline (NA) stimulation. After reactivity tests, the tissues were then fixed and stained with hematoxylin and eosin (HE) for histological evaluation of inflammatory response. The QM2 strain did induce inflammatory process in mice colon, and demonstrated differences in muscular contraction between the G60 and G210 groups, with p?<?0.05. Plasma [BuChE] increased during the acute phase of infection (p?<?0.05) with subsequent heterogeneous decline in the late chronic phase. These results show that the QM2 strain has tropism to the colon of mice and causes damage characteristic of megacolon; also, Ach has an enigmatic importance in the anti-inflammatory reflex over the course of T. cruzi infection.     

Magnitude and mechanisms of glucose counterregulation following islet transplantation in patients with type 1 diabetes suffering from severe hypoglycaemic episodes

Aims/hypothesis

Pancreatic islet transplantation stabilises glycaemic control in type 1 diabetes mellitus patients with neuroglycopoenia, despite them not achieving insulin independence because of limited graft function. However, the extent and underlying metabolic pathways of restored glucose counterregulation are unknown. We therefore compared systemic glucose turnover, including lactate gluconeogenesis (GN) and muscle glucose uptake, in individuals with type 1 diabetes who were transplant recipients with partial graft function (T1DM/ITx⁺), matched non-transplanted individuals with type 1 diabetes (T1DM/ITx^?) and matched healthy non-diabetic individuals.

Methods

Participants (n?=?12 in each group) underwent a euglycaemic and a hypoglycaemic (2.5–2.8 mmol/l) hyperinsulinaemic clamp (0.8 mU kg^?1 min^?1) in a randomised crossover fashion. Systemic and skeletal muscle glucose and lactate kinetics were assessed using a combination of isotopic and forearm balance techniques.

Results

Whole-body glucose counterregulation, the difference in glucose infusion rates required to maintain the glycaemic goal between the hypoglycaemic and euglycaemic clamps, was improved in T1DM/ITx⁺ (7.8?±?1.3 μmol kg^?1 min^?1) compared with T1DM/ITx^? (0.3?±?0.9 μmol kg^?1 min^?1), but was ～45% lower than in controls (14.1?±?2.1 μmol kg^?1 min^?1). Increased endogenous glucose production (EGP) and decreased systemic glucose disposal accounted for 49% and 39% of glucose counterregulation in T1DM/ITx⁺, respectively, compared with 60% and 36% in controls. Lactate GN increased in T1DM/ITx⁺ (2.7?±?0.4 μmol kg^?1 min^?1) and controls (1.7?±?0.5 μmol kg^?1 min^?1), such that it accounted for 70% and 20% of the increased EGP, respectively. Skeletal muscle accounted for similar proportions of the decrease in systemic glucose disposal in controls (49%) and T1DM/ITx⁺ (41%).

Conclusions/interpretation

Partial islet graft function improves hypoglycaemia counterregulation by increasing EGP, largely via lactate GN and decreasing systemic glucose disposal. This may explain the reduction in severe hypoglycaemic events in T1DM/ITx⁺ individuals. Trial registration: ClinicalTrials.gov NCT01668485     

Functional mechanism of tracheal relaxation,antiasthmatic, and toxicological studies of 6-hydroxyflavone

Previously, we described tracheal rat rings relaxation by several flavonoids, being 6-hydroxyflavone (6-HOF) the most active derivative of the series. Thus, its mechanism of action was determined in an ex vivo tracheal rat ring bioassay. The anti-asthmatic effect was assayed in in vivo OVAlbumin (OVA)-sensitized guinea pigs. Finally, the toxicological profile of 6-HOF was studied based on Organization of Economic Cooperation and Development guidelines with modifications. 6-HOF–induced relaxation appears to be related with receptor-operated calcium channel and voltage-operated calcium channel blockade as the main mechanism of action, and also through the production of relaxant second messengers NO and cGMP. Molecular docking supports that 6-HOF acts as calcium channel blocker and by activation of nitric oxide synthase. In addition, the in vivo anti-asthmatic experiments demonstrate the dose-dependent significant anti-allergic effect of 6-HOF induced by OVA, with best activity at 50 /kg. Finally, toxicological studies determined a LD50 > 2,000 mg/kg and, after 28 day of treatment with 6-HOF (50 mg/kg) by intragastric route, mice did not exhibit evidence of any significant toxicity. In conclusion, experiments showed that 6-HOF exerts significant relaxant activity through calcium channel blockade, and possibly, by NO/cGMP-system stimulation on rat trachea, which interferes with the contraction mechanism of smooth muscle cells in the airways. In addition, the flavonoid shows potential anti-asthmatic properties in an anti-allergic pathway. Furthermore, because the pharmacological and safety evidence, we propose this flavonoid as lead for the development of a novel therapeutic agent for the treatment of asthma and related respiratory diseases.     

慢性乙型肝炎、乙肝肝硬化、乙肝肝癌患者Th1/Th2型细胞因子水平变化研究

目的分析慢性乙型肝炎(CHB)、乙肝肝硬化(LC)、乙肝肝癌(HCC)患者血清中Th1/Th2型细胞因子水平变化,为慢性乙型肝炎至肝癌的发生发展过程中的免疫变化研究提供线索,并为患者的临床治疗研究提供免疫学指标。方法选取2010年2月-2011年11月于首都医科大学附属北京佑安医院就诊的40例CHB患者、40例LC患者、53例HCC患者,用Luminex技术检测血清中Th1类细胞因子[白细胞介素(interleukin,IL)-12、干扰素(interferon,IFN)-γ和肿瘤坏死因子(tumor necrosis factor,TNF)-α]水平及Th2类细胞因子(IL-4、IL-6和IL-10)水平,并将25例健康志愿者作为正常对照组进行比较。结果除TNF-α外,CHB组、LC组和HCC组Th1类IL-12、IFN-γ和Th2类IL-4、IL-6、IL-10细胞因子水平均低于正常对照组;CHB组中大部分Th1类和Th2类细胞因子都高于LC组和HCC组;HCC组中TNF-α细胞因子水平要高于CHB组、LC组。结论 CHB、LC和HCC患者体内Th1/Th2细胞因子分泌水平受到抑制,Th1/Th2平衡发生漂移,对HBV病毒的清除作用受到抑制。TNF-α在肝癌发生过程中发挥着重要作用。     

新型冠状病毒肺炎诊疗的若干思考

作为一种新发的传染性极强的呼吸道疾病,新型冠状病毒肺炎（COVID-19,以下简称新冠肺炎）在全球范围内传播、蔓延。目前,该病已经造成了数以百万计的人感染、近30万人死亡,严重威胁着人类生命财产安全等众多方面。本文通过在临床治疗过程中对该疾病特点及疾病演变规律的总结,为新冠肺炎的诊治提供参考。