Hydrolytic Stability of Methacrylamide and Methacrylate in Gelatin Methacryloyl and Decoupling of Gelatin Methacrylamide from Gelatin Methacryloyl through Hydrolysis

Gelatin methacryloyl (GelMA; GM) is a promising nature‐derived photocurable material that can mimic the extracellular matrix because GelMA features tailorable mechanical properties, proteolytic degradation, and good cell adhesion. GelMA contains not only methacrylamide but also methacrylate. However, the hydrolytic stability of methacrylamide and methacrylate groups of GelMA in aqueous solutions has not been scrutinized. Here, the structural change of GelMA through hydrolysis is investigated for the first time. The structural change of hydrolyzed GelMA is quantitatively identified using colorimetric and ¹H NMR methods. The methacrylate groups decompose markedly at high pH solutions, but the methacrylamide groups remain stable. Further, pure gelatin methacrylamide is successfully decoupled from GelMA for a better understanding of GelMA structure and future use for biomedical applications.     

Embryonic stem cells-derived exosomes enhance retrodifferentiation of retinal Müller cells by delivering BDNF protein to activate Wnt pathway

ObjectiveThe present study was intended to investigate the role of embryonic stem cell-derived exosomes (ESC-Exos) in Müller cell retrodifferentiation and their specific mechanism.MethodsFollowing co-incubation of the extracted ESC-Exos and Müller cells, their effects on the retrodifferentiation and proliferation of Müller cells were measured by EdU staining, immunofluorescence, and western blot. ESCs transfected with small interfering RNA of BDNF were co-incubated with Müller cells to determine Müller cell proliferation and retrodifferentiation. β-catenin expression in the nucleus and GSK-3β phosphorylation were measured to determine the role of the Wnt pathway in Müller cells. The function of the retina in RCS rats was observed using flash electroretinogram.ResultsCo-incubation of ESCs with Müller cells or overexpression of BDNF contributed to Müller cell retrodifferentiation and proliferation, as evidenced by increased cell proliferation, fluorescence intensities of proliferation markers and retinal stem cell markers, and expression of BDNF and β-catenin, and suppressed GSK-3β phosphorylation. However, co-incubation with ESCs silencing BDNF or treatment with GW4869 inhibited the proliferation and retrodifferentiation of retinal Müller cells. In addition, exosome injection increased BDNF, BrdU, PH3, SOX2, and Pax6 expression, enhanced β-catenin expression in the nucleus, diminished GSK-3β, and improved retinal degeneration in RCS rats.ConclusionESC-Exos accelerated Müller cell retrodifferentiation and proliferation through Wnt pathway activation by delivering BDNF protein to Müller cells.     

PCL-PEG-PCL载姜黄素纳米粒子的制备以及体外药物释放的考察

目的制备一种生物可降解、生物相容性良好的姜黄素纳米粒子,并对其体外药物释放行为进行考察。方法采用开环聚合法制备生物可降解的PCL-PEG-PCL三嵌段聚合物,然后采用乳液挥发法制备负载姜黄素的PCL-PEG-PCL纳米粒子,通过透射电镜观察所制备纳米粒子的形貌特征,动态光散射(DLS)测定粒径,采用HPLC测定纳米粒子的包封率和载药量,同时考察其体外药物释放行为。结果姜黄素纳米粒子具有球形结构,粒径在200 nm左右,载药量为(14.23±0.35)%,3 d体外累积释药量65%。结论所制备的姜黄素纳米粒子具有较高的载药量和包封率,同时体外药物释放实验证实姜黄素纳米粒子具有良好的缓释功能。     

In situ injectable nano-composite hydrogel composed of curcumin, N,O-carboxymethyl chitosan and oxidized alginate for wound healing application

In this paper, an in situ injectable nano-composite hydrogel composed of curcumin, N,O-carboxymethyl chitosan and oxidized alginate as a novel wound dressing was successfully developed for the dermal wound repair application. Nano-curcumin with improved stability and similar antioxidant efficiency compared with that of unmodified curcumin was developed by using methoxy poly(ethylene glycol)-b-poly(?-caprolactone) copolymer (MPEG-PCL) as carrier followed by incorporating into the N,O-carboxymethyl chitosan/oxidized alginate hydrogel (CCS-OA hydrogel). In vitro release study revealed that the encapsulated nano-curcumin was slowly released from CCS-OA hydrogel with the diffusion-controllable manner at initial phase followed by the corrosion manner of hydrogel at terminal phase. In vivo wound healing study was performed by injecting hydrogels on rat dorsal wounds. Histological study revealed that application of nano-curcumin/CCS-OA hydrogel could significantly enhance the re-epithelialization of epidermis and collagen deposition in the wound tissue. DNA, protein and hydroxyproline content in wound tissue from each group were measured on 7th day of post wounding and the results also indicated that combined using nano-curcumin and CCS-OA hydrogel could significantly accelerate the process of wound healing. Therefore, all these results suggested that the developed nano-curcumin/CCS-OA hydrogel as a promising wound dressing might have potential application in the wound healing.     

Artificial intelligence in screening,diagnosis, and classification of diabetic macular edema: A systematic review

We review the application of artificial intelligence (AI) techniques in the screening, diagnosis, and classification of diabetic macular edema (DME) by searching six databases– PubMed, Scopus, Web of Science, Science Direct, IEEE, and ACM– from January 1, 2005 to July 4, 2021. A total of 879 articles were extracted, and by applying inclusion and exclusion criteria, 38 articles were selected for more evaluation. The methodological quality of included studies was evaluated using the Quality Assessment for Diagnostic Accuracy Studies (QUADAS-2). We provide an overview of the current state of various AI techniques for DME screening, diagnosis, and classification using retinal imaging modalities such as optical coherence tomography (OCT) and color fundus photography (CFP). Based on our findings, deep learning models have an extraordinary capacity to provide an accurate and efficient system for DME screening and diagnosis. Using these in the processing of modalities leads to a significant increase in sensitivity and specificity values. The use of decision support systems and applications based on AI in processing retinal images provided by OCT and CFP increases the sensitivity and specificity in DME screening and detection.     

小学生双眼屈光不均衡发育的影响因素分析

目的：研究6～12岁儿童双眼屈光不均衡发育的影响因素。

方法：于2019-12在天津市滨海新区两所小学采用整群抽样的方法选取儿童607人,平均年龄8.2±1.8岁,均进行光学生物测量(眼轴长度、角膜前表面平均屈光力)、睫状肌麻痹后屈光检查及问卷调查。

结果：纳入儿童等效球镜度为-0.11±1.63D,双眼等效球镜度差异为-0.08±0.64D,等效球镜度差异绝对值为0.41±0.49D。检出屈光参差儿童56人,非屈光参差儿童551人,屈光参差儿童和非屈光参差儿童双眼角膜屈光力差异绝对值无差异(0.30±0.34D vs 0.27±0.24D,P=0.430),眼轴差异绝对值有差异(0.67±0.39mm vs 0.13±0.13mm,P=0.005)。多因素线性回归分析显示,每周手机/电脑使用时间、每周近距离工作时间、每周视疲劳次数、习惯阅读距离是屈光不均衡发育程度(双眼等效球镜度差异绝对值)的影响因素; 习惯阅读距离、写字时利手是屈光不均衡发育偏向(双眼等效球镜度差异)的影响因素。

结论：6～12岁儿童看手机/电脑时间长、近距离工作时间长、视疲劳次数增多、习惯阅读距离近可能引起屈光发育不均衡程度增加,写字时右利手且头部严重左偏和右偏的儿童右眼近视程度较左眼更深。     

学龄前高度远视和低度远视儿童屈光发育比较

目的：比较学龄前高度远视和低度远视儿童的屈光发育特点。方法：回顾性系列病例研究。收集 2020年7月至2021年12月在天津医科大学眼科医院就诊的学龄前远视性屈光不正儿童43例（86眼）。 根据睫状肌麻痹后球镜度结果将儿童分为高度远视组27例（54眼）,低度远视组16例（32眼）,分别于 基线和随访1年记录2组儿童的屈光度和眼球生物学参数,包括眼轴长度（AL）、角膜曲率半径、轴 率比。采用自身配对t检验进行组内屈光度和眼球生物学参数分析;采用Wilcoxon符号秩检验进行 组内最佳矫正视力比较;采用独立样本t检验进行组间眼生物学参数年变化量的差异分析。结果： 与基线值[（8.37±1.84）D]相比,高度远视组等效球镜度（SE）年降低量为（0.72±0.41）D（t=-9.26, P<0.001）。高度远视组AL年增长量[（0.31±0.18）mm]与低度远视组年增长量[（0.21±0.09）mm]的 差异有统计学意义（t=3.53,P=0.001）,2组间角膜曲率半径年变化差异无统计学意义;高度远视组 轴率比的年增长量（0.04±0.02）与低度远视组年增长量（0.02±0.03）的差异有统计学意义（t=3.23, P=0.002）。结论：与学龄前低度远视儿童相比,学龄前高度远视儿童的AL和轴率比的年增长幅度更 大,这提示有必要对高度远视儿童进行密切随访。