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.     

Progress on ocular siRNA gene‐silencing therapy and drug delivery systems

Age‐related macular degeneration (AMD) and glaucoma are global ocular diseases with high blindness rate. RNA interference (RNAi) is being increasingly used in the treatment of these disorders with siRNA drugs, bevasiranib, AGN211745 and PF‐04523655 for AMD, and SYL040012 and QPI‐1007 for glaucoma. Administration routes and vectors of gene drugs affect their therapeutic effect. Compared with the non‐viral vectors, viral vectors have limited payload capacity and potential immunogenicity. This review summarizes the progress of the ocular siRNA gene‐silencing therapy by focusing on siRNA drugs for AMD and glaucoma already used in clinical research, the main routes of drug delivery and the non‐viral vectors for siRNA drugs.     

T1WI_Star_VIBE_FS序列在头颈部放疗MR定位中扫描方法研究

目的 对比分析T1WI_Star_VIBE_FS序列在头颈部肿瘤患者MR定位中不同扫描方式对图像质量、信噪比、对比噪声比等参数的影响,确定优选扫描方式。方法 回顾性分析 78例头颈部MR定位患者,分别采用组织补偿法(A组 23例)、分段扫描拼接法(B组 18例)和二者结合法(C组 37例)进行增强扫描,对比上述3种扫描方式获取的图像质量、颈前部软组织信噪比(SNR)和对比噪声比(CNR)的差异。结果 C组扫描方式可获取较高的图像质量评分;3种扫描方式获取图像的SNR的平均值分别为 214.70±148.78、91.95±59.26、307.61±127.80;CNR的平均值分别为 208.74±148.27、85.79±59.50、301.58±127.48;C组在图像质量评分、SNR和CNR方面均明显优于A、B组(P<0.01)。结论 推荐使用组织补偿和分段拼接扫描相结合方式作为头颈部肿瘤放疗MR定位的优选扫描方式。     

Qianzheng powder for the treatment of primary Hemifacial spasm: A protocol for systematic reviews and meta-analysis

Background:Hemifacial spasm (HFS) is a clinical common neurological disease, its main performance for 1 side or 2 sides muscles (the orbicularis oculi muscle, expression, orbicularisoris muscles) recurrent paroxysmal, involuntary twitching, aggravating when excited or nervous, more severe cases of the disease may include difficulty in opening the eyes, crooked corners of the mouth, and twitching noises in the ears, etc.^[1] Early manifestations of the disease are intermittent mild convulsions of the orbicularis oculi muscle, and then gradually spread to 1 side of the facial muscles, such as frowning muscles, nasal muscles, buccinalis muscles, etc, especially the most obvious spasms of the oral muscles, which can involve the ipsilateral platysma muscle in severe cases, with each twitch for a few seconds to a few minutes. The disease will affect the quality of life such as speaking, eating, seeing and so on, and even cause psychological effects such as inferiority, anxiety and depression. At present, the incidence of the disease in China is 11 per 1.1 million, females are more common than males. There are many ways to treat HFS, but the Qianzheng powder has a unique advantage in treating this disease. Therefore, our systematic review aims to evaluate the efficacy and safety of Qianzheng powder in the treatment of Primary Hemifacial spasm, and to provide a reliable basis for clinical decision makers.Methods:From its inception until April 2021, we will search electronic databases, including PubMed, Embase, Cochrane Library, China Biomedical Literature Database, China Knowledge Infrastructure, Wanfang Database, and China Scientific Journals Database. The authors will independently sift through studies, extract data information, and assess methodological quality using the Cochrane Risk of Bias tool. The RevManV. 5.3 software will be used for statistical analysis.Results:The results of this study, which will be published in a peerreviewed journal, will evaluate the efficacy and safety of Qianzheng powder in the treatment of primary Hemifacial spasm.Conclusion:This systematic review will provide reliable evidence-based basis for treating primary Hemifacial spasm with Qianzheng powder.INPLASY Registration number:INPLASY202130037.     

随访数据信息化管理系统对超声医师诊断效能的影响

目的探讨随访数据信息化管理系统的构建，并研究该系统对超声医师诊断效能的影响。 方法回顾性分析2016年7月至2018年12月北京大学深圳医院的8951个病例，均经病理证实。采用分级诊断构建随访数据信息化管理系统。所有病例采用诊断等级（1~3级，每个等级细分为诊断符合与不符合）并进行诊断加权分评估。计算随访效率（随访每100个有效病例所需要的人员和时间）。超声医师诊断效能通过诊断等级、诊断符合率及诊断加权分评价。采用χ²检验比较随访数据信息化管理系统构建前后超声医师诊断等级、诊断符合率的差异，采用t检验比较诊断加权分的差异。 结果随访工作占用成本由随访系统构建前的5.2人时/100例降低至构建后的3.1人时/100例。随访数据信息化管理系统构建前、后诊断等级比较（1级/2级/3级∶21.0%/21.0%/58.0% vs 17.3%/23.9%/58.8%），差异有统计学意义（χ²=23.708，P＜0.001），构建后的诊断等级优于构建前，对病变良恶性作出判断病例（2级+3级）的构成比增加（82.7% vs 79.0%）。系统构建后1级、3级诊断符合率与系统构建前比较有所提高（83.8% vs 66.6%；87.8% vs 85.7%），差异均具有统计学意义（χ²=361.453、5.573，P＜0.001、=0.020）；2级诊断符合率比较，差异无统计学意义（P＞0.05）。超声医师诊断加权分均值从3.93分提高至4.51分，差异具有统计学意义（t=-14.816，P＜0.001）。 结论随访数据信息化管理系统的构建能提高随访效率，并定量评价超声医师的诊断效能，通过系统反馈和校正的方式可提高超声医师的诊断效能。     

Simultaneous Determination and Pharmacokinetics of Tetrandrine, Fangchinoline, and Cyclanoline in Rat Plasma by Ultra-High Performance Liquid Chromatography-Mass Spectrometry after Oral Administration of Stephaniae Tetrandrae Radix Extract

Objective: The objective of the study wasto develop a rapid and sensitive ultra?performance liquid chromatography?tandem massspectrometric method for the determination of tetrandrine, fangchinoline, and cyclanoline in rat plasma and to investigate their pharmacokinetics after oral administration of Stephaniae Tetrandrae Radix extracts. Methods: Sample pretreatment involved methanol pretreatment and liquid–liquid extraction of ethyl acetate from plasma with methanol. Tramadol was used as the internal standard. The analysis was performed using an high strength silica T3 column (100 mm × 2.1 mm, 1.8 μm) and a gradient elution method consisting of mobile phase solution A (0.1% formic acid in water) and B (acetonitrile) at a flow rate of 0.4 mL/min. The detection was performed using a triple quadrupole tandem mass spectrometer in the multiple reaction monitoring mode and using an electrospray ionization source in the positive ionization mode. Results: High efficiency was achieved with an analysis time of 4 min/sample. The calibration curve linear in the concentration range of 1250 ng/ml (R2 ≥ 0.9900) and the lower limit of quantification is 1 ng/ml. The intraday and interday precision (relative standard deviation) values were lower than 9.4. Accuracy (relative error) was within 10.3% at all three quality control levels. Conclusions: This method was successfully applied in pharmacokinetics of tetrandrine, fangchinoline, and cyclanoline in rats after oral administration of Stephaniae Tetrandrae Radix extracts. The maximum plasma concentration (Cmax) of tetrandrine, fangchinoline, and cyclanoline was 124.71 ± 16.08, 84.56 ± 3.28, and 57.61 ± 6.26 ng/ mL, respectively. The time to reach Cmax was 10.39 ± 3.04 for tetrandrine, 10.17 ± 3.04 for fangchinoline, and 6.40 ± 3.16 for cyclanoline. The pharmacokinetic results might help further guide the clinical application of Stephaniae Tetrandrae Radix.     

针对所有高血压患者进行原醛症筛查：势在必行

原发性醛固酮增多症(primary hyperaldosteronism,PA)占所有高血压患者的5％～10％.筛查为诊断PA的关键步骤.本文根据国内外最新证据,提出了目前筛查PA存在的一些主要问题,并给出建议,以期指导临床工作和提高PA检出率.