Bilayered nanosheets used for complex topography wound anti‑infection

There is a consensus that the prevention of wound infection should be achieved in the following ways:(1)closing the wound to protect it from extra infection;(2)an antibacterial agent that could kill endogenous bacteria.However,existing bulk two-dimensional antibacterial materials show inefficient adhesion to wounds with complex morphology and thus cause the prevention of wound closure.Reducing the thickness of bulk two-dimensional materials to less than 100 nanometres endows them with great flexibility,which could allow them to adhere to wounds with complex morphology by only physical adhesion.Herein,a broad-spectrum and efficient antimicrobial peptide(AMP)was introduced to biocompatible methacrylated gelatine(GelMA)with multiple modification sites,which served as an inner antibacterial layer.After being combined with a biodegradable and good mechanical poly-l-lactide(PLLA)outer layer through plasma-treatment-assisted spin coating,we finally constructed bilayered antibacterial nanosheets with a thickness of approximately 80 nm.These bilayered nanosheets possess good adhesion to surfaces with complex topography and thus achieve better wound closure than other bulk two-dimensional materials.Moreover,this AMP-grafted conjugation shows minimal cytotoxicity compared with Ag^+antibacterial agents,and the antibacterial rate of nanosheets is dependent on the graft rate of AMP.We suggest that this bilayered antibacterial nanosheet might be an advanced anti-infection dressing for wound treatment in clinical settings.

A sandwiched patch toward leakage-free and anti-postoperative tissue adhesion sealing of intestinal injuries

Ideal repair of intestinal injury requires a combination of leakage-free sealing and postoperative antiadhesion.However,neither conventional hand-sewn closures nor existing bioglues/patches can achieve such a combination.To this end,we develop a sandwiched patch composed of an inner adhesive and an outer antiadhesive layer that are topologically linked together through a reinforced interlayer.The inner adhesive layer tightly and instantly adheres to the wound sites via-NHS chemistry;the outer antiadhesive layer can inhibit cell and protein fouling based on the zwitterion structure;and the interlayer enhances the bulk resilience of the patch under excessive deformation.This complementary trilayer patch(TLP)possesses a unique combination of instant wet adhesion,high mechanical strength,and biological inertness.Both rat and pig models demonstrate that the sandwiched TLP can effectively seal intestinal injuries and inhibit undesired postoperative tissue adhesion.The study provides valuable insight into the design of multifunctional bioadhesives to enhance the treatment efficacy of intestinal injuries.

他克莫司个体内高变异度与肝移植术后免疫介导移植物损伤的临床研究

目的探讨他克莫司个体内变异度(IPV)与肝移植术后免疫介导移植物损伤的关系。方法回顾性分析2015年1月至2019年12月在西安交通大学第一附属医院肝胆外科进行经典原位肝移植的288例受者资料。采用移植后2~6个月期间至少5个他克莫司血药浓度谷值(C0)计算得到他克莫司血药浓度变异系数(CV)。设定的复合终点包括:(1)肝移植术后6个月后免疫介导的移植物失功,包括慢性排斥反应、活检证实的晚期急性排斥反应;(2)肝移植术后6个月后免疫抑制剂毒性作用导致的肝功能损害;(3)肝移植术后6个月后出现的CMV血症。以CV均值为临界值将受者分为低CV组和高CV组,比较两组到达复合终点的受者比例,分析肝移植术后发生免疫介导移植物损伤的影响因素。正态分布计量资料以均数±标准差(±s)表示,采用独立样本t检验进行比较;非正态分布计量资料以中位数表示,采用Mann-Whitney U检验进行比较。计数资料以例数(%)表示,采用χ^(2)检验进行比较。采用Kaplan-Meier法绘制生存曲线,使用log-rank检验进行比较。采用Cox比例风险模型分析肝移植术后免疫介导移植物损伤的危险因素,将单因素分析中P≤0.20的变量采用逐步后退法进行多因素分析。P<0.05为差异具有统计学意义。结果截至2021年6月30日,288例肝移植受者平均随访时间(37±16)个月(6~76个月),共37例(12.85%)到达复合终点。肝移植术后2~6个月他克莫司血药浓度CV平均值为(28.11±10.72)%,以28.11%作为临界值将288例受者分为低CV组(CV<28.11%)和高CV组(CV≥28.11%)。两组供者年龄、性别,受者年龄、性别、体质指数、原发病性质、术前终末期肝病模型评分、术前Child-Pugh评分、术后免疫抑制方案、慢性排斥反应发生率以及术后2~6个月他克莫司C0、总胆红素和ALT水平差异均无统计学意义(P均>0.05)。高CV组受者急性排斥反应和CMV血症发生率高于低CV组受者(3.13%和0,5.47%和1.25%),差异有统计学意义(P均<0.05)。高CV组到达复合终点的受者比例较低CV组高,分别为18.0%(23/128)和8.8%(14/160),差异有统计学意义(χ^(2)=5.397,P<0.05)。高CV组受者较低CV组到达复合终点的受者时间更短,分别为(1764±72)d和(1909±51)d,差异有统计学意义(χ^(2)=6.367,P<0.05)。Cox比例风险模型分析结果显示,供者年龄、移植前受者Child-Pugh评分、移植后2~6个月总胆红素和他克莫司血药浓度CV是肝移植术后发生免疫介导移植物损伤的独立危险因素(HR=1.033、2.353、1.011和0.450,P均<0.05)。结论肝移植术后2~6个月他克莫司高IPV(血药浓度CV≥28.11%)与免疫介导的移植物损伤存在显著相关性,可能导致急性排斥反应及CMV血症发生率增高。

Biomaterial strategies for the application of reproductive tissue engineering

Human reproductive organs are of vital importance to the life of an individual and the reproduction of human populations.So far,traditional methods have a limited effect in recovering the function and fertility of reproductive organs and tissues.Thus,aim to replace and facilitate the regrowth of damaged or diseased tissue,various biomaterials are developed to offer hope to overcome these difficulties and help gain further research progress in reproductive tissue engineering.In this review,we focus on the biomaterials and their four main applications in reproductive tissue engineering:in vitro generation and culture of reproductive cells;development of reproductive organoids and models;in vivo transplantation of reproductive cells or tissues;and regeneration of reproductive tissue.In reproductive tissue engineering,designing biomaterials for different applications with different mechanical properties,structure,function,and microenvironment is challenging and important,and deserves more attention.

Mechanism of hepatocellular damage in rat caused by low serum selenium

The aim of this paper is to investigate the mechanism of hepatocellular damage in rats caused by low serum selenium.Thirty six rats were randomly divided into 2 groups:group A(fed with low-selenium diet from the Keshan Disease area with the content of selenium being 0.017 mg/kg);group B[fed with sel-enium-supplemented diet and 0.3 mg/L selenium(Na_(2)SeO_(3))was added to the drinking water].Both were respectively fed for 12 weeks.At the end of the 12th week,the levels of serum selenium,glutathione peroxidase(GPX)and malondialdehyde(MDA)in hepatic tissue were measured;the hepatocellular ultrastructure and apoptosis were observed as well.The levels of serum sel-enium and GPX in group A were markedly lower than those in group B.MDA level in group A was significantly higher than that in group B.Under the electron micro-scope(EM),the mitochondria were remarkably changed in group A.The rate of liver cell apoptosis appeared much higher in group A as well.It indicated that the damage caused by selenium deficiency was through the process of oxidation.Selenium deficiency led to apoptosis of hepa-tocytes where oxidative damage to mitochondria might be the cause.