网膜填塞法闭合经自然腔道内镜手术胃壁瘘口的研究

目的应用动物模型评价网膜填塞法闭合经自然腔道内镜手术(NOTES)胃壁瘘口方法的可行性及有效性。方法 29只杂种犬经胃前壁内镜下全层切开(10 mm),经此入路完成NOTES腹腔探查术,其中12只应用网膜填塞法闭合胃壁瘘口(网膜填塞组),17只内镜钛夹闭合(钛夹组),闭合成功动物术后存活2周。比较两种胃壁瘘口闭合术的操作耗时、闭合成功率以及瘘口愈合和腹腔感染发生率。结果网膜填塞法闭合胃壁瘘口的成功率为91.7%(11/12),高于内镜下钛夹闭合方法成功率82.4%(14/17),但未见显著统计学差异(P>0.05);网膜填塞闭合法操作平均耗时(11.7±2.1)min/例次,明显低于钛夹闭合法(25.0±5.6)min/例次(P<0.05)。25只动物胃壁闭合成功后者术后均存活14 d,复查胃镜见胃壁瘘口愈合良好。处死后实验动物未发现腹腔严重感染及明显脏器损伤;网膜填塞组8只犬(72.7%,8/11)可见胃壁瘘口处胃壁浆膜面黏连,显著高于钛夹闭合组(14.3%,2/14,P<0.05)。结论网膜填塞法能有效闭合NOTES经胃壁瘘口,与传统内镜钛夹闭合法相比具有操作简单、成功率高的优点,但容易发生瘘口黏连是其明显不足。     

Covalently functionalized graphene oxide wrapped by silicon–nitrogen-containing molecules: preparation and simultaneous enhancement of the thermal stability,flame retardancy and mechanical properties of epoxy resin nanocomposites

A novel functionalized graphene oxide (FGO) wrapped with Si–N-containing flame retardant (FR-fGO) was successfully synthesized via a chemical modification process and applied to enhance the thermal stability, fire resistance, and mechanical properties of epoxy resin (EP). Herein, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to explore the structure and morphology of FR-fGO to overcome the fact that the FGO cannot strongly bond with the polymer matrix. With the incorporation of FR-fGO into EP, the thermal stability improved and the total heat release decreased compared with pure EP. Meanwhile, FR-fGO composites significantly reduced the amount of flammable and toxic volatiles. A possible flame-retardant mechanism of FR-fGO was deduced from a theoretical analysis of the chemical bond energy and the experimental results of thermal decomposition: namely, well-dispersed FR-fGO nanosheets constituted a physical barrier, with an Si–N-containing synergy system forming a highly graphitized residual char with an Si-containing cross-linked network. The enhancement in mechanical properties demonstrated that the composites had remarkable compatibility. This study provides a novel modification strategy to improve the dispersion and flame retardance of graphene.

This study provided a modification strategy for improving the flame retardance of graphene and its derivatives in a polymer matrix.     

Dual responsive oligo(lysine)-modified Pluronic F127 hydrogels for drug release of 5-fluorouracil

Peptide-containing hydrogels have become a research hotspot due to their unique secondary structure and biocompatibility. Herein, we used amino-terminated F127 as a macroinitiator to initiate the ring-opening polymerization of l-lysine(z)-NCA, and the obtained oligo(lysine)-modified F127 (FL) had degrees of polymerization of lysine of 2, 5, and 8. The results showed that the FL hydrogels had reversible temperature-dependent sol–gel transitions, and the introduction of lysine increased the critical gel temperature. In the dilute solution of FL, the micelle size increased and aggregated as the pH increased; the micelle grew into a rod-like shape under alkaline conditions. Scanning electron micrographs showed that the interior of the FL hydrogel had a more complete porous structure. The FL-2 hydrogel loaded with 5-fluorouracil exhibited an approximately linear release trend within 12 h and has good biocompatibility. Therefore, FL hydrogels have potential applications in the field of biomedicine.

Oligo(lysine)-F127 hydrogels have a temperature-responsive sol–gel transition and pH-responsive micelle morphology.     

Monosodium iodoacetate induces apoptosis via the mitochondrial pathway involving ROS production and caspase activation in rat chondrocytes in vitro

Monosodium iodoacetate (MIA) is an inhibitor of glyceraldehyde‐3‐phosphate dehydrogenase activity, and causes dose‐dependent cartilage degradation resembling the pathological changes of human osteoarthritis (OA). In this study, we assessed the apoptosis induced by MIA and clarified the underlying mechanisms using the primary rat chondrocytes. The apoptosis of primary rat chondrocytes was analyzed by flow cytometry. The levels of mitochondrial membrane potential (ΔΨm) were evaluated using fluorescence spectrophotometer. The production of reactive oxygen species (ROS) was determined by fluorescence spectrophotometer. Apoptosis‐related protein cytochrome c and procaspase‐3 expressions were examined by Western blotting. We found that MIA treatment induces apoptosis in chondrocytes, as confirmed by increases in the percent of apoptotic cells, up‐regulation of cytochrome c and caspase‐3 protein levels. Treatment with MIA increases ROS production and decreases the levels of ΔΨm. The antioxidant, N‐acetylcysteine (NAC), significantly prevented the production of ROS, the reduction of ΔΨm, the release of cytochrome c and the activation of caspase‐3. Further, NAC completely protected the cells from MIA‐induced apoptosis. Together these observations suggest that the mechanisms of MIA‐induced apoptosis are primarily via ROS production and mitochondria‐mediated caspase‐3 activation in primary rat chondrocytes. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 364–369, 2013     

Normobaric hyperoxia retards the evolution of ischemic brain tissue toward infarction in a rat model of transient focal cerebral ischemia

Objectives: Oxygen therapy has been long considered a logical therapy for ischemic stroke. Our previous studies showed that normobaric hyperoxia (normobaric hyperoxia (NBO), 95% O₂ with 5% CO₂) treatment during ischemia reduced ischemic neuronal death and cerebromicrovascular injury in animal stroke models. In this study, we studied the effects of NBO on the evolution of ischemic brain tissue to infarction in a rat model of transient focal cerebral ischemia.

Methods: Male Sprague-Dawley rats were given NBO (95% O₂) or normoxia (21% O₂) during 90-min filament occlusion of the middle cerebral artery (MCAO), followed by 3 or 22.5 h of reperfusion. 2,3,5-triphenyltetrazolium chloride (TTC) staining was used to evaluate the longitudinal evolution of tissue infarction.

Results： In normoxic rats, MCA-supplied cortical and striatal tissue was infarcted after 90-min MCAO with 22.5 h of reperfusion. NBO-treated rats showed a 61.4% reduction in infarct size and tissue infarction mainly occurred in the ischemic striatum. When infarction was assessed at an earlier time point, i.e. at 3 h of reperfusion, normoxic rats showed significantly smaller but mature infarction (no TTC staining, white color), with the infarction mainly occurring in the striatum. Unexpectedly, NBO-treated rats only showed immature lesion (partially stained by TTC, light white color) in the ischemic striatum, indicating that NBO treatment also retarded the process of neuronal death in the ischemic core. Of note, NBO-preserved striatal tissue underwent infarction after prolonged reperfusion.

Conclusions： Our results demonstrate that NBO treatment given during cerebral ischemia retards the evolution of ischemic brain tissue toward infarction and NBO-preserved cortical tissue survives better than NBO-preserved striatal tissue during the phase of reperfusion.     

2013-2018年北京市海淀区麻疹风疹疑似病例血清学检测结果分析

 目的 探讨麻疹、风疹的流行病学特征,为麻疹、风疹的疫情监测提供实验室诊断依据。方法 应用酶联免疫吸附试验(enzyme linked immunosorbent assay,ELISA)对北京市海淀区2013-2018年麻疹、风疹疑似病例血清样本中的麻疹IgM和风疹IgM抗体同时进行检测,结果使用SPSS 22.0软件进行统计学分析。结果 2013-2018年共检测麻疹、风疹疑似病例476例,其中麻疹IgM抗体阳性153例,阳性率为32.14%,不同年份阳性率差异有统计学意义(χ²=34.82,P<0.01);风疹IgM抗体阳性32例,阳性率为6.72%,不同年份阳性率差异有统计学意义(χ²=19.76,P<0.01)。麻疹IgM抗体阳性病例中,男女性别比为0.96∶1,男女之间阳性率差异无统计学意义(χ²=1.70);风疹IgM抗体阳性病例中,男女性别比为3.00∶1,男女之间阳性率差异有统计学意义(χ²=6.33,P<0.05)。麻疹和风疹IgM抗体阳性病例主要为外省户籍病例,分别占56.21%和68.75%;麻疹抗体阳性病例主要为无免疫史病例,占55.56%。3-5月为麻疹、风疹的集中发病期。结论 应加强重点人群的常规接种,加强外省户籍人口的管理,接种疫苗,从而降低麻疹、风疹发病率。