Nonlinear elasticity of biological basement membrane revealed by rapid inflation and deflation

Basement membrane (BM) is a thin layer of extracellular matrix that surrounds most animal tissues, serving as a physical barrier while allowing nutrient exchange. Although they have important roles in tissue structural integrity, physical properties of BMs remain largely uncharacterized, which limits our understanding of their mechanical functions. Here, we perform pressure-controlled inflation and deflation to directly measure the nonlinear mechanics of BMs in situ. We show that the BMs behave as a permeable, hyperelastic material whose mechanical properties and permeability can be measured in a model-independent manner. Furthermore, we find that BMs exhibit a remarkable nonlinear stiffening behavior, in contrast to the reconstituted Matrigel. This nonlinear stiffening behavior helps the BMs to avoid the snap-through instability (or structural softening) widely observed during the inflation of most elastomeric balloons and thus maintain sufficient confining stress to the enclosed tissues during their growth.

Basement membrane (BM) is a thin layer of fibrous matrix separating cells from the connecting tissues, which functions as a physical barrier and widely exists across multicellular organisms (1). The BM is typically composed of laminins, collagen IV, nidogens, and proteoglycans; laminin and collagen IV are the major components that constitute networks forming the structure of the BM, and nidogen and proteoglycans are associated with the laminin and collagen IV networks. As a physical barrier, the structural and mechanical properties of BM are important in the organization and morphogenesis of tissues and organs as well as in the maintenance of adult functions (2); abnormal BM has been associated with a variety of diseases such as cancer (3). For example, in metastasis, cancer cells must invade through BMs to escape from the primary tumor—a process that causes 90% of cancer-related death (4). Indeed, breaks in BMs can be observed in malignant tumors (5). Thus, mechanical properties of the BM are considered to play important roles in regulating cancer cell invasion (6, 7). Furthermore, as a physical barrier differentiating different parts of tissues, BMs are required to be permeable to small molecules to allow exchange of water and nutrients; the permeability of BM is thus one of the essential kinetic parameters regulating biomolecule exchange and activities of internal cells (8, 9). Given the importance of BMs as a semipermeable barrier maintaining tissue structural integrity, however, their permeability and mechanical properties remain largely unknown, mainly due to the lack of direct measurement methods, especially in situ. This limits our understanding of the physical role of BMs in various physiological and pathological processes such as tumor development and angiogenesis.Determining the mechanical properties of intact BMs in situ is challenging because of their irregular shape, small thickness, and tight connection to the cells inside. Due to these limitations, conventional mechanical tests such as tensile, compression, and bending tests are difficult to be applied to characterize the mechanical behavior of the BM in situ. Instead, previous measurements had been carried out on fragmented BMs isolated from various tissues (e.g., via atomic force microscopy [AFM] indentation) and found that the BM stiffness ranges from ∼kPa to ∼MPa (10–17). In addition, a constitutive relationship is required to extract the material parameters such as elastic modulus and permeability from these experimental measurements. However, like most biological tissues, a reliable constitutive model for the BM is not yet available, causing additional difficulties in obtaining its mechanical parameters from most traditional experiments.In this work, we demonstrate an in situ method to simultaneously measure both the elastic properties and permeability of intact BM in breast cancer spheroid by recording the deflation process of an inflated BM filled with phosphate buffered saline (PBS) by microinjection without requiring complex sample preparation and post-data processing. During the deflation of the BM, its elastic retraction generates a pressure difference to drive the liquid flow through the membrane; the liquid flux can be calculated from the reduction of the intact BM diameter. With the BM thickness measured by transmission electron microscopy (TEM), we can determine the shear modulus, permeability, and diffusivity of the intact BM. Moreover, we find from our measurements that the elasticity of BM is highly nonlinear with a strong strain-stiffening effect. Furthermore, we discuss the possible impact of the strain-stiffening effects of BM on its functions.     

泽泻原三萜、降三萜和倍半萜的分离及其抗炎活性研究＊

目的 对泽泻中原三萜、降三萜和倍半萜化学成分分离和鉴定及其抗炎活性进行研究；方法 采用硅胶柱色谱、凝胶柱色谱、高速逆流色谱、中压制备色谱和半制备色谱法对泽泻中各类化合物进行分离，利用¹H和¹³C NMR对分离化合物进行结构鉴定；通过测定各单体对LPS（1 μg·mL^-1）诱导Caco-2细胞中NO生成的抑制作用评价其抗炎活性。结果 从泽泻中分离得到19个化合物，包括8个原三萜类成分：alisol A 23 acetate （1），alisol G （2），16-oxo-11-anhydroalisol A （3），16-oxo-11-anhydroalisol A 24 acetate （4），alisoma A （5），alisoma B （6），alismanol J （7），alismanol B （8）；1个降三萜类成分：17-nor-protostane （9）；9个倍半萜类成分：orientalol L （10），orientalol M （11），orientalol N （12），orientalol O （13），orientalol P （14），alismanoid A （15），heyneanones D （16），leptocladol B （17），chabrolidione B （18）；1个木脂素类成分：pnoresinol （19）。原三萜类成分均具有显著的抑制活性，化合物1-8的IC₅₀分别为2.1、0.9、7.3、10.0、11.0、16.0、13.5和10.5 μmol·mL^-1，降三萜及倍半萜活性较弱，化合物10、11、13、15、16和17的IC₅₀分别为24.0、26.2、30.6、15.7、17.2和15.2 μmol·mL^-1。结论 化合物16、17、18和19为该植物首次分离得到。首次报道了倍半萜类成分对LPS诱导Caco-2细胞中NO生成的抑制作用，其中alisol A 23 acetate和alisol G的抑制活性最强。     

I125 irradiation stent for treatment of hepatocellular carcinoma with portal vein thrombosis: A meta-analysis

PurposeA meta-analysis aimed to systematically evaluate the safety and efficiency of I¹²⁵ irradiation stent placement for patients with hepatocellular carcinoma (HCC) combined with portal vein tumor thrombosis (PVTT).Materials and methodsThe Cochrane library, PubMed/Medline, EMBASE, CNKI, Wanfang Data and CQVIP were systematically screened out from the earliest to December 2019. The qualities of all included studies were assessed. The primary endpoints were the 6-month, 12-month stent cumulative patency rate and 6-month, 12-month, 24-month overall survival rate while the secondary endpoints were the objective response rate of PVTT, main portal venous pressure changes and treatment-related adverse events. Our meta-analysis was conducted using Stata 12.0 software.ResultsTotally seven studies with 1018 patients were included in the final analysis, in which 602 patients received TACE and I¹²⁵ irradiation stent placement, and 416 patients in control group underwent TACE and stent placement without endovascular brachytherapy (EVBT). Meta-analysis showed that the I¹²⁵ irradiation stent improved the cumulative stent patency rates in 6 months [OR = 1.65, 95% CI (1.32–2.05), P < 0.001] and 12 months [OR = 2.55, 95% CI (1.90–3.42), P < 0.001] and the survival rates in 6 months [OR = 1.77, 95% CI (1.41–2.22), P < 0.001], 12 months [OR = 3.14, 95% CI (2.24–4.40), P < 0.001] and 24 months [OR = 7.39, 95% CI (3.55–15.41), P < 0.001]. However, there was no difference in the objective response rate of PVTT [OR = 1.13, 95% CI (0.87–1.48), P = 0.365], main portal venous pressure and the occurrence adverse event [OR = 0.88, CI = 0.72–1.08, P = 0.212] between two groups.ConclusionI¹²⁵ irradiation stent seems to be more effective in treating hepatocellular carcinoma with portal vein tumor thrombosis. The usage of portal vein stent combined endovascular brachytherapy has the potential to act as an alternative therapy for HCC with PVTT. On account of the limitation of studies included, more studies with high-level evidence, such as RCTs, are requisite to support the above promising results.     

Optimize the management of urological tube-related emergencies during the coronavirus disease 2019 (COVID-19) pandemic

BackgroundTo introduce and determine the value of optimized strategies for the management of urological tube-related emergencies with increased incidence, complexity and operational risk during the global spread of coronavirus disease 2019 (COVID-19).MethodsAll emergent urological patients at Tongji Hospital, Wuhan, during the period of January 23 (the beginning of lockdown in Wuhan) to March 23, 2020, and the corresponding period in 2019 were recruited to form this study’s COVID-19 group and control group, respectively. Tongji Hospital has the most concentrated and strongest Chinese medical teams to treat the largest number of severe COVID-19 patients. Patients in the control group were routinely treated, while patients in the COVID-19 group were managed following the optimized principles and strategies. The case incidence for each type of tube-related emergency was recorded. Baseline characteristics and management outcomes (surgery time, secondary complex operation rate, readmission rate, COVID-19 infection rate) were analyzed and compared across the control and COVID-19 periods.ResultsThe total emergent urological patients during the COVID-19 period was 42, whereas during the control period, it was 124. The incidence of tube-related emergencies increased from 53% to 88% (P<0.001) during the COVID-19 period. In particular, the incidence of nephrostomy tube-related (31% vs. 15%, P=0.027) and single-J stent-related problems (19% vs. 6%, P=0.009) increased significantly. The mean surgery times across the two periods were comparable. The number of secondary complex operations increased from 12 (18%) to 14 (38%) (P=0.028) during the COVID 19-period. The number of 2-week postoperative readmission decreased from 10 (15%) to 1 (3%) (P=0.049). No participants contracted during the COVID-19 period.ConclusionsUrological tube-related emergencies have been found to have a higher incidence and require more complicated and dangerous operations during the COVID-19 pandemic. However, the optimized management strategies introduced in this study are efficient, and safe for both urologists and patients.     

Prospective case‐control study of enterovirus detection differences in children’s cerebrospinal fluid between multiplex PCR and real‐time RT‐PCR assay

BackgroundViral encephalitis is common in childhood. It is an acute brain parenchymal inflammation caused by a variety of viral infection, and enterovirus accounts for the majority. Due to atypical clinical manifestations, pathogenic testing is important for assisting clinical diagnosis. The purpose of this study was to evaluate the performance of the multiplex PCR assay compared with quantitative real‐time PCR for enterovirus detection.MethodsA prospective case‐control study was performed involving 103 pediatric patients suspected for viral encephalitis and cerebrospinal fluid (CSF) samples were collected and tested for 9 pathogens using multiplex PCR assay during April to November in 2018. In parallel, an aliquot of samples was tested for enterovirus infection by real‐time PCR assay.ResultsThere were 85.4% children were confirmed as viral encephalitis on discharge, the remaining ones were diagnosed as other CNS diseases, such as epilepsy. The specificity of the two methods was the same as that of the clinical diagnosis, but the sensitivity and consistency with clinical diagnosis of multiplex PCR were both higher than the real‐time PCR. Besides of enterovirus, multiplex PCR could also detect coinfection of enterovirus with Epstein‐Barr virus and mumps virus.ConclusionResults of multiplex PCR method are more consistent with the clinical diagnosis and are superior to real‐time PCR for detecting enterovirus in CSF.     

某医疗机构核医学工作场所劳务派遣保洁人员的职业健康管理

近几年，"劳务派遣"成了医疗机构终末消毒、保洁、垃圾回收等工作新的用工形式。由于多数用工单位和用人单位不清楚对劳务派遣人员职业健康管理中各自应承担的责任和义务，以至于劳务派遣工在劳动过程中应享有的劳动保护权益未获得切实保障。本文就某医疗机构核医学工作场所劳务派遣保洁人员的职业健康管理监督案例进行讨论。     

关节镜辅助下轴向螺钉内固定术治疗Sanders-2型跟骨骨折疗效观察

目的探讨关节镜辅助下轴向螺钉内固定术治疗Sanders-2型跟骨骨折的临床疗效。方法将50例Sanders-2型跟骨骨折患者按照随机数字表法分为研究组与对照组,各25例。研究组给予关节镜辅助下轴向螺钉内固定术治疗,对照组给予传统切开复位内固定术治疗。术后观察3个月。比较两组手术时间、住院时间、骨折愈合时间、术前与术后3个月末两组Bohler角、Gissane角度数及跟骨高度、宽度,以及两组Maryland足功能评分、手术疗效。结果研究组手术时间、住院时间及骨折愈合时间均显著短于对照组(P<0.05或0.01)。术后3个月末两组Bohler角及Gissane角度数均较术前显著增大(P<0.01),研究组较对照组增大更显著(P<0.05或0.01)。术后3个月末研究组跟骨高度显著>术前(P<0.01),两组跟骨宽度均显著>术前(P<0.01),两组间比较差异无统计学意义(P>0.05)。术后3个月末两组Maryland足功能评分均较术前显著升高(P<0.01),研究组较对照组升高更显著(P<0.01)。研究组手术治疗总有效率显著高于对照组(P<0.05),并发症发生率显著低于对照组(P<0.05)。结论关节镜辅助下轴向螺钉内固定术治疗Sanders-2型跟骨骨折效果显著,能有效促进患者足踝功能恢复,安全性较高,值得临床推广应用。     

超声心动图诊断左心室射血分数减低的左冠状动脉异常起源于肺动脉的效果分析

目的探讨左心室射血分数（LVEF）减低的左冠状动脉异常起源于肺动脉（ALCAPA）的超声心动图特点及手术效果。 方法选取2008年10月至2018年9月首都医科大学附属北京儿童医院ALCAPA患者28例，根据LVEF分为LVEF减低组（LVEF＜50%）19例和LVEF正常组（LVEF≥50%）9例，比较2组患者超声心动图表现，应用两独立样本t检验比较2组患者间超声参数的差异。手术患者（17例）分别于术后1 d、1个月、6个月、1年进行超声心动图随访，应用配对t检验与术前超声参数进行对比。 结果LVEF减低组患者LVEF为30%~48%，平均年龄5.4个月；LVEF正常组LVEF为60%~73%，平均年龄2.5岁。LVEF减低组与LVEF正常组相比，左心室舒张末期内径大［（131.95±24.24）mm/m² vs（85.67±20.26）mm/m²］，右冠状动脉内径小［（3.06±0.51）mm vs（4.01±0.62）mm］，差异具有统计学意义（t=-4.465、4.075，P均＜0.001），易形成室壁瘤。LVEF减低组中10例行手术治疗，7例超声心动图随访至术后1年；与术前相比，术后1 d开始左心室舒张末期内径逐渐回缩［（109.98±16.06）mm/m²、（99.49±12.02）mm/m²、（89.48±10.90）mm/m²、（80.03±8.09）mm/m² vs（123.26±12.40）mm/m²］，差异具有统计学意义（t=-2.668、-7.519、-5.413、-6.526，P=0.004、0.001、0.012、0.007），LVEF术后1个月开始恢复，术后6个月达正常水平［（45.50±9.57）%、（66.25±10.34）%、（67.25±4.50）% vs（38.83±7.05）%］，差异具有统计学意义（t=3.162、3.683、5.869，P=0.025、0.014、0.002）。 结论LVEF减低的ALCAPA患儿年龄小、心脏病变重，超声心动图可以准确作出诊断，但需要与心内膜弹力纤维增生症、扩张型心肌病相鉴别。ALCAPA手术治疗远期效果较好，超声心动图在术后随访中有重要作用。     

基于泛素-蛋白酶体途径探讨远志散“益气化痰开窍”治疗阿尔茨海默病的科学内涵＊

阿尔茨海默病（Alzheimer′s disease，AD）是一种常见的神经系统退行性疾病，磷酸化Tau蛋白异常聚集所形成的神经纤维缠结（Neurofibrillary tangles，NFTs）是AD的典型病理特征，直接参与AD的发生发展。因此，AD的治疗可从调节磷酸化Tau蛋白异常聚集入手。中医学认为“痰浊”是导致AD发生的重要病理因素之一，“正气亏虚，痰浊蒙窍”是AD的核心病机。“痰浊”与磷酸化Tau蛋白异常聚集密切相关，磷酸化Tau蛋白异常聚集可归属“痰浊”的范畴。化痰开窍与减少磷酸化Tau蛋白聚集在AD的治疗中有不谋而合之处。泛素-蛋白酶体系统（Ubiquitin-proteasome system，UPS）是细胞内蛋白降解的主要途径，参与AD进程中磷酸化Tau蛋白的降解。UPS功能受损是磷酸化Tau蛋白异常聚集和AD发生的重要原因。本文试图从中医“痰”的视角认识磷酸化Tau蛋白异常聚集，探讨中医“痰浊”与现代医学磷酸化Tau蛋白异常聚集的相关性，并从UPS视角提出益气化痰开窍法治疗AD的作用机制假说，推测UPS可能是远志散益气化痰开窍干预AD的主要途径，精确调控UPS可能是未来研究防治AD的新视角，为科学阐释通过调控UPS蛋白降解途径治疗AD的作用机制提供新思路。