Genipin-crosslinked polyvinyl alcohol/silk fibroin/nano-hydroxyapatite hydrogel for fabrication of artificial cornea scaffolds—a novel approach to corneal tissue engineering

Abstract

Design of artificial corneal scaffolds substitute is crucial for replacement of impaired cornea. In this paper, porous polyvinyl alcohol/silk fibroin/nano-hydroxyapatite (PVA/SF/n-HA) composite hydrogel was prepared via the genipin (GP) cross-linking, the pore diameter of the hydrogel ranged from 8.138?nm and 90.269?nm, and the physical and physiological function of hydrogel were investigated. The resulting hydrogel exhibited favourable physical properties. With the GP content increasing, the structural regularity of PVA/SF/n-HA composite hydrogel was enhanced and the thermal stability was improved. The moisture content was slightly decreased and generally maintained at approximately 70%. The tensile strength was heightened up to 0.64?MPa, while the breaking elongation was decreased slightly. Moreover, the biofunction was investigated. The in vitro degradation test demonstrated that with the addition of GP, the stability of the composite hydrogels in protease XIV solution was promoted and the three-dimensional porosity structure of composite hydrogels was maintained as ever. And the human corneal fibroblasts (HCFs) were employed to examine the cells cytotoxicity of the PVA/SF/n-HA composite hydrogels with different GP content by CCK-8 assay. Based on confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM), HCFs had individually commendable adhesion and proliferation on PVA/n-HA/SF composite hydrogel. HCFs proliferated and grew into the pores of composite hydrogel. The results of biocompatibility experiments of composite hydrogel suggested that it was no acute toxicity, in vitro cytotoxicity was 0 or 1 grade. Overall, results from this paper, PVA/n-HA/SF composite hydrogel was a qualified medical material which conformed to the national standard, could be a promising alternative for artificial cornea scaffold material—a novel approach to corneal tissue engineering.     

Bladder tissue regeneration using acellular bi-layer silk scaffolds in a large animal model of augmentation cystoplasty

Acellular scaffolds derived from Bombyx mori silk fibroin were investigated for their ability to support functional tissue regeneration in a porcine model of augmentation cystoplasty. Two bi-layer matrix configurations were fabricated by solvent-casting/salt leaching either alone (Group 1) or in combination with silk film casting (Group 2) to yield porous foams buttressed by heterogeneous surface pore occlusions or homogenous silk films, respectively. Bladder augmentation was performed with each scaffold group (6 × 6 cm²) in juvenile Yorkshire swine for 3 m of implantation. Augmented animals exhibited high rates of survival (Group 1: 5/6, 83%; Group 2: 4/4, 100%) and voluntary voiding over the course of the study period. Urodynamic evaluations demonstrated mean increases in bladder capacity over pre-operative levels (Group 1: 277%; Group 2: 153%) which exceeded nonsurgical control gains (144%) encountered due to animal growth. Similarly, elevations in bladder compliance were substantially higher in augmented animals from baseline (Group 1: 357%; Group 2: 147%) in comparison to controls (41%). Gross tissue evaluations revealed that both matrix configurations supported extensive de novo tissue formation throughout the entire original implantation site which exhibited ultimate tensile strength similar to nonsurgical counterparts. Histological and immunohistochemical analyses showed that both implant groups promoted comparable extents of smooth muscle regeneration and contractile protein (α-smooth muscle actin and SM22α) expression within defect sites similar to controls. Parallel evaluations demonstrated the formation of a transitional, multi-layered urothelium with prominent cytokeratin, uroplakin, and p63 protein expression in both matrix groups. De novo innervation and vascularization processes were evident in all regenerated tissues indicated by synaptophysin-positive neuronal cells and vessels lined with CD31 expressing endothelial cells. Ex vivo organ bath studies demonstrated that regenerated tissues supported by both silk matrices displayed contractile responses to carbachol, α,β-methylene-ATP, KCl, and electrical field stimulation similar to controls. Our data detail the ability of acellular silk scaffolds to support regeneration of innervated, vascularized smooth muscle and urothelial tissues within 3 m with structural, mechanical, and functional properties comparable to native tissue in a porcine model of bladder repair.     

Polymorphism of the ABO blood group genes in Han, Kazak and Uygur populations in the Silk Route of northwestern China

Genetic polymorphism in the ABO blood group gene of Han, Kazak and Uygur populations inhabiting the most northwestern part of China was investigated using polymerase chain reaction-based techniques. The present study enrolled 43 healthy unrelated Han, 37 Kazak and 59 Uygur volunteers. The allele in A1 blood group is distinguished A0101 and A0102 in difference of nucleotide position 467. The A0101 allele is more frequent in Caucasian and the A0102 allele is characteristic in Mongoloid. It must be notable that A0201 in the A2 group (with a single base deletion at nucleotides 1059 to 1061) which was characteristic of Caucasian was observed in Kazak and Uygur populations but not in Han. Further, 00201 (with no nucleotide deletion at 261 and three nucleotide differences), which is frequent in different races including Caucasian except for Mongoloid, was detected also in Kazak and Uygur populations. The frequencies of B0101 in Kazak, Uygur and Han were comparable to those of other Asian populations but higher than those of Caucasian populations. Collectively, these results reveal that the allele frequencies of Kazak and Uygur at the ABO blood group locus are an intermediate between those of Mongoloid and Caucasian, suggesting the admixed feature of Kazak and Uygur with Mongoloid and Caucasian.     

TME联合双吻合器与丝线吻合的比较分析

目的分析直肠癌手术中应用TME联合双吻合器技术与传统手工丝线吻合技术在吻合口瘘上的不同。方法由病例档案室提供1999年1月至2009年7月的直肠癌患者资料。选取肿瘤下缘距齿状线距离大于4 cm的资料。采用随机数字方法,从使用TME联合双吻合器的直肠癌患者中随机选取30名患者;再从采用丝线吻合的直肠癌患者中随机选取30名患者。结果使用吻合器组发生吻合口瘘的有1例,使用丝线吻合组有8例。结论吻合器吻合比丝线吻合在预防吻合口瘘上效果要好。     

张掖地区异常血红蛋白和地中海贫血的研究

目的：研究甘肃省张掖地区异常血红蛋白和地中海贫血发病情况。方法：在张掖地区普查异常血红蛋白１０９００人，普查地中海贫血２１６１人。结果：检出异常血红蛋白携带者１２人，平均发生率为０．１１％。检出地中海贫血先证者４人，平均发生率为０．１８％。应用指纹分析技术分析１１例异常血红蛋白，鉴定６种变异体，即ＨｂＧＴａｉｐｅｉ，ＨｂＧＣｏｕｓｈａｔａ，ＨｂＮｅｗＹｏｒｋ，ＨｂＪＢａｎｇｋｏｋ，ＨｂＤＰｕｎｊａｂ和ＨｂＵｂⅠ－Ⅱ。应用ＰＣＲ／ＡＳＯ技术鉴定３例β地贫，均为ＣＤ１７（Ａ→Ｔ）杂合子。发现该地区以ＨｂＧＴａｉｐｅｉ和βＣＤ１７（Ａ→Ｔ）等基因突变为主，类似中原汉族的基本特征，但有部份ＨｂＧＣｏｕｓｈａｔａ和ＨｂＤＰｕｎｊａｂ变异体存在。结论：张掖地区人口融合了其他蒙古人种和高加索人的血缘，与该地的人口变迁及“丝绸之路”的影响一致。     

从简帛医书看《内经》足六脉病候

《内经》中《灵枢.经脉》以外还有一些篇章涉及到经脉病候,其中集中论述经脉病候的大都以足六脉形式表述。研究表明,足六脉病候与简帛经脉病候关系密切,提示我们,一方面,经脉病候研究不能仅仅局限于《灵枢.经脉》;另一方面,简帛经脉文献的影响相当深远。将观察经脉病候概念的视野扩大,并从学术发展的历史进程予以审视,有利于深化对经脉病候甚至早期经脉理论的理解。     

δ9-Tetrahydrocannabinol: Effects of route of administration on onset and duration of activity and tolerance development

Pigeons trained to key-peck for food reinforcement on a VI 3, were injected either orally, intramuscularly, or intravenously with ⁹-tetrahydrocannabinol and the onset and duration of this drug were determined. Onset of action was much faster for the intravenous route than the other two routes. Speed of and duration of effect were also affected by drag dosage. Using the same methods, the development of tolerance to the behavioral effects were investigated. Tolerance occurred with all three routes at about the same rate.