Effects of small leucine-rich proteoglycans on corneal transparency / 中华实验眼科杂志

Small leucine-rich proteoglycans (SLRPs) are necessary structural ingredients of the cornea, which are vital for the establishment and maintenance of corneal transparency.SLRPs are mainly located in the corneal stroma and can be divided into class Ⅰ, class Ⅱ, and class Ⅲ.The compensatory and cooperative interactions among SLRPs regulate the formation and assembly of stromal collagen fibrils, thereby maintaining the highly ordered arrangement of collagen fibrils, and establishing corneal transparency.Decorin and lumican are the main functional components of class Ⅰ and class Ⅱ SLRPs, respectively, and changes in their expression or abnormities in the structure of their core proteins affect the natural content and arrangement of other stromal extracellular matrix components, ultimately resulting in abnormal fibril formation, assembly, and arrangement, causing corneal opacity.SLRPs can regulate corneal wound healing and stromal matrix remodeling via binding to fibrotic molecules and their receptors, which provides bases for corneal diseases therapy and study of molecular mechanisms of corneal transparency.The bioactivities and the role of SLRPs in corneal transparency were reviewed in this article.

Biomimetic remineralization of dentin / 口腔疾病防治

@#In recent years, due to precise control of the amorphous mineral precursor in the demineralization of dentine collagen fibers in orderly deposition, forming apatite crystals similar to the natural mineralized dentin, the bottom-up remineralization approach which does not depend on the existence of seed crystallites, dentin biomimetic mineralization techniques gradually become a hotspot in the research field of restoration of demineralized dentin caused by dental caries. This paper reviews the changing concepts and practices of the remineralization of demineralized dentin, emphasizing biomimetic remineralization studies. The results of the literature review show that the traditional dentin remineralization method is usually a disordered mixture of demineralized dentin and minerals, so mineralized dentin is not comparable to natural mineralized dentin in terms of the morphological characteristics and mechanical properties. With its gradual increase in recent years, dentine biomimetic mineralization technology perfectly resembles the minerals in the dentin overlapping sequence arranged with the dentine collagen fiber structure characteristics, leading to greatly improved microstructural, physical and chemical properties. As a result, dentine biomimetic mineralization technology is expected to achieve new breakthroughs in the fields of resin-dentin bonding mixing layers and the decay of dentin. At present, the technical obstacles that need to be overcome in the clinical application of the biomimetic remineralization of dentin are how to continuously supplement all the active ingredients needed for mineralization in the process of remineralization and how to keep the mechanical properties of the parent material unchanged while slowly releasing all ingredients. Researchers have successively proposed three-step transportation of the biomimetic remineralization of raw materials, as well as the preparation of mineralization precursors stabilized by polymers in advance and the reuse of mesoporous silicon nanomaterials for the transportation of the mineralized ingredient system. The concept described above provides the preliminary in vitro experimental basis for the transformation of the biomimetic remineralization strategy of dentin in clinical applications.

Reinforcement property of collagen fibril in articular cartilage / 医用生物力学

Objective To evaluate and compare the differences in COSMOL articular cartilage (AC) simulation due to the application of collagen fibril reinforcement property. Methods Collagen fiber stress was modeled independently according to its orientation in AC and written into the original poro-elastic AC model. Function call was used to avoid quadric strain term. The iteration of solver was increased for better convergence. Results The initial superficial Y displacement of the reinforced model was 15 μm, which was 17.6% of the non-reinforced model. X normal strain of the reinforced model was 10% of that in the non-reinforced model, but the superficial X normal stress of the reinforced model was 10 times higher than that of the non-reinforced model. Conclusions The application of collagen fibril reinforcement property in COMSOL AC simulation is achieved, which provided the computational model and theoretical analysis for collagen fibril lesion. Lateral reinforcement of collagen fiber can constrain the vertical strain, by which enlarge AC load capacity and improve AC mechanical properties.

The Ultrastructural Observations of the Normal Anterior Cruciate Ligament / 中国运动医学杂志

Objective To study the ultrastructure of the anterior cruciate ligament.Methods Specimens were procured from seven patients with arthroscopy and observed under scanning and transmission electron microscope. Results Fibrils of normal anterior cruciate ligament arrayed in compact parallel form with waviness.Connecting fibers existed between fibrils.Diameters of fibrils were different with range of 30nm to 60nm mostly.Fibroblasts were distributed along with the fibrils.Active cells excrete filamentous collagen fibrils.Conclusion The ultrastructure of the anterior cruciate ligament was correlated with its function status.Mature fibroblasts existed in the ligament.

Hypertrophy of the Patellar Tendon induced by Local Injection of TGF-beta1 in Mature Rats / 대한정형외과연구학회지

PURPOSE: The effects of local injection of TGF-beta1 on the normal patellar tendon and the characteristics of remaining tendon after the partial resection of hypertrophic one were investigated. MATERIALS AND METHODS: TGF-beta1 was injected into the right patellar tendon of mature rats weekly for 3 weeks. Histological study, biomechanical analysis and the transmission electron microscopic evaluation were done. Half of hypertrophic tendon was resected at 4 weeks after the last injection and the same analyses were RESULTS: TGF-beta1 treated tendon increased in cross sectional area but decreased significantly in maximum tensile stress. The hypertrophic tissue was mainly composed of small collagen fibrils. After the partial resection of hypertrophic tendon, there was no significant difference in maximum tensile stress between remaining and control tendons. There were relatively larger collagen fibrils in the remaining tendon tissue than in non-resected hypertrophic one. CONCLUSION: Local injection of TGF-beta1 induced the hypertrophy of normal tendon. After the partial resection of hypertrophic tendon, the remaining one showed the more similar biomechanical properties to normal one.

Laser scanning confocal microscope study of wet bonding interface on different dentin bonding surfaces / 实用口腔医学杂志

Objective: To study the bonding interface characteristic of five wet bonding systems while bonding on different dentin bonding surfaces. Methods: Rhodamine B was used to label five adhesives(OptiBond Sol o,Single Bond,Gluma One-Bond,Bond-1 and One-Step) in consistency of 0.1%, an d the bonding interface of the 5 wet bonding systems on dry or wet dentin surfa ces was observed with laser scanning confocal microscope. Results: All five bonding systems could infiltrate well into dentin bonding interface when bonding on wet dentin surface. The fluorescence confocal images gave eviden ce of the adhesives penetrated into the widened tubules, lateral tubules and dem ineralized peritubular dentin. Little discontinuity in dentin tubular was observ ed in the images, especially in those of alcohol-water-based adhesives. When b onded in dry dentin surface, the hybrid thickness of acetone-based adhesives de creased significantly. Conclusion: The penetration ability of ad hesives may be reduced significantly on dry dentin surface.

Ultrastructual analysis of the fibrous layer of condyle in the rat temporomandibular joint with ageing

THE STRUCTURAL GRADING OF COLLAGEN FIBERS UNDER LIGHT AND ELECTRON MICROSCOPE / 解剖学报

The structure of collagen fibers in the loose and dense connective tissues, from various sources (central tendon of dog diaphragm, tentorium cerebelli of hen, pericardium of adult man, etc.) were investigated with light microscope (LM), transmitting electron microscope (TEM) with ultra thin sections cut after reembedding with epoxy resin following orientation under LM, and ultrathin section under TEM coordinated with the semithin section under LM. It was observed that: (1) The logitudinal striated structure within the so called collagen fibers and the collagen fiber without the logitudinal striated structure under LM are all the closely arranged collagen fibril bundle in which the space between the fibrils is narrower than 0.2?m under TEM. So that both must belong to the same grade. (2) The collagen fibrils in vivo may be singlely dispersed, or in double, or in bundles formed from 3 to hundreds of fibrils; the space between fibrils varied closely to several ?m. (3) The diameter of collagen fibrils is genera ly 20—200 nm, but there are also thicker or thiner fibrils. According to these and other previous works, we suggest the following points on the nomenclature: (1) The collagen fibril is the collagen structure which has generally the diameter of 20—200nm and the cross striations of 64—70nm along its longitudinal axis under EM It should no longer be Called the collagen microfibril. (2) The collagen fiber is the bundle which is composed of three or more closely arranging collagen fibrils bound by a small amount of cement substance. Under EM, the space between the bundles is larger than 0.2?m but the space between the fibrils within the bundle is narrower than 0.2?m. Under LM, the collagen fiber is the structure without the visible subunit filament and may branch and anastomose- each other. (3) The collection of collagen fibers should be called collagen fiber bundle. It includes the so called "collagen fibers" (old routine nomenclature) with the visible subunit filaments under LM. This nomenclature should remove the confusion on the structural grading of collagen fibers and unify the concept of collagen fiber under LM with that under EM.