BACKGROUND:The structure,physical and chemical properties(such as rheological properties)and biological activity of hyaluronic acid with different molecular weights are quite different.When the degradation degree of non-cross-linked hyaluronic acid is too large and the high-molecular-weight hyaluronic acid is degraded to low-molecular-weight hyaluronic acid,the properties and biological functions of the product will also change,which will affect the use of the product. OBJECTIVE:To review the mechanism of molecular weight degradation of non-cross-linked hyaluronic acid and the impacts of molecular weight degradation on the structure,rheological properties,biological activity and applications of non-cross-linked hyaluronic acid. METHODS:The first author searched the articles related to the molecular weight of hyaluronic acid collected in PubMed,CNKI database and other databases.The high-quality articles with high correlation were screened according to the inclusion and exclusion criteria.The search time was from January 2017 to December 2022.The Chinese and English search terms were"hyaluronic acid,non-cross-linked hyaluronic acid,molecular weight,degradation,structure,rheological properties,biologic activity".Finally,47 articles were included for review and analysis. RESULTS AND CONCLUSION:(1)The molecular weight of non-cross-linked hyaluronic acid is mainly degraded by specific enzymatic hydrolysis and non-specific free radical degradation.(2)The molecular weight degradation of non-cross-linked hyaluronic acid will change its structure and rheological properties,resulting in the untie of polymer network structure,the decrease of rheological properties such as viscosity and viscoelasticity,and the decrease of mechanical properties,which will eventually affect the practical application effect of the product.(3)The biological activity of non-cross-linked hyaluronic acid is molecular weight dependent,and the biological activity of different molecular weight hyaluronic acid is different.Even the same receptor combined with high-molecular-weight hyaluronic acid and low-molecular-weight hyaluronic acid will express completely opposite biological effects.(4)The degradation of molecular weights of non-cross-linked hyaluronic acid will reduce the safety and efficacy of the products,affect their service life and application performance,and ultimately influence the clinical application results.(5)Non-cross-linked hyaluronic acid has great potential as a biodegradable biomaterial in wound healing,tissue engineering,aesthetic medicine and other fields,and further research and understanding of the correlation between molecular weight degradation of non-cross-linked hyaluronic acid and bioactivity is a prerequisite for better development of wound dressings,drug delivery systems and tissue-engineered scaffolds.(6)However,there are currently few studies on the molecular weight degradation of non-cross-linked hyaluronic acid,and it is unclear how to effectively avoid the potential risks associated with the molecular weight degradation of non-cross-linked hyaluronic acid in clinical applications.(7)Therefore,a series of potential risks associated with the molecular weight degradation of non-cross-linked hyaluronic acid during its application,including the effects on its structure,properties and biological activity,and the resulting changes on the body,is one of the future directions that need to be closely investigated.

The lung is an important organ in systemic toxicity test of medical devices and is significant in safety evaluation. Based on the authors' understanding of medical devices, this study provides a brief analysis of the lung examination and common problems in systemic toxicity, so as to provide references for the pre-clinical safety evaluation of medical devices. It should be noted that a reasonable risk assessment should be made after comprehensive assessment for specific medical device products.
Equipment Safety ; Humans ; Lung ; Risk Assessment

OBJECTIVE: To study the safety of alginate based gastric mucosal protective adhesive and its feasibility as a submucosal injection. METHODS: The feasibility of using alginate-based gastric mucosal protective gel as submucosal injection was evaluated by RESULTS: After injection of different concentrations of alginate base mucosal protective adhesive solution, the uplift height was significantly higher than that of normal saline ( CONCLUSIONS Gastric mucosa protector is a promising new medical device product with feasibility and good biocompatibility as submucosal uplift injection agent.
Adhesives ; Alginates ; Animals ; Feasibility Studies ; Gastric Mucosa ; Injections ; Rats ; Swine

Infertility has become one of the global problems, with the continuous improvement and penetration of human assisted reproductive technology, appliance products of medical devices for assisted reproductive technology, such as aspiration needles, micromanipulator and embryo transfer catheter, have been widely used. In order to ensure the safety and effectiveness of such products, it is necessary to establish an appropriate quality control system. This paper mainly discusses the quality control points of human assisted reproductive medical devices from the aspects of raw materials, product design, production process, key performance, packaging, preservation and transportation, so as to provide technical reference for the research and development, production and supervision of such products.
Cross-Sectional Studies ; Humans ; Quality Control ; Reproductive Techniques, Assisted

OBJECTIVE: In this paper, the key points of quality control and safety evaluation of human assisted reproductive medium were summarized to provide reference for the establishment of relevant standards and quality control in the future. METHODS: Through literature research, the key factors of quality control and risk control of human assisted reproductive medium were summarized, and the problems in clinical transformation were discussed. RESULTS: It is very important for the development of human assisted reproduction technology to study the active ingredients and their harmful degradation products and drugs in the culture medium of assisted reproduction. CONCLUSIONS At present, the biggest challenge is to effectively control the quality of the culture medium for human assisted reproduction, establish corresponding inspection methods and quality standards for the key components, ensure the safety and effectiveness during the product shelf life, and thus improve the success rate of human assisted reproduction technology.
Humans ; Quality Control ; Reproduction ; Reproductive Techniques, Assisted

The aim of this study was to evaluate the fatigue property
Heart Valve Prosthesis ; Heart Valves ; Materials Testing ; Prosthesis Design ; Stents

Water is an important component in liquid medical device products for human assisted reproductive technology. Water traits, conductivity, microbial limits, total organic carbon, easy oxides, heavy metal content, bacterial endotoxin and other indicators have an important impact on sperm, egg and embryo development in vitro, so for such products, the quality of water control is extremely important. The production water for producing such products is generally prepared by MilliQ purification system. In this research, we used four different types of water to fabricate the IVF liquids. It included deionized reverse osmosis water, ultra purified water and ultra purified water without endotoxin or nucleic acid, and compared with tap water. The in vitro rat embryo test system was used to study the embryotoxicity of this four different culture liquid production waters. From the result, the group of the super purified water without endotoxin and nucleic acid has the best result of the embryo formation rate, the number of total cell number and the inner cell number. This study proved the importance of removing endotoxin and nucleic acid from the water used for the preparation of the liquid products for assisted reproduction, and provided the basis for the selection of water quality for the liquid products for assisted reproduction.
Animals ; Embryonic Development ; Equipment Contamination ; Fertilization in Vitro/instrumentation* ; Humans ; Rats ; Reproductive Techniques, Assisted ; Research ; Technology ; Water

BACKGROUND: Ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for analyzing amino acids in biological samples is simple in sample preparation with a short analysis time, and has high sensitivity and specificity. Until now, it is only applied in analyzing glutamine contents in dialysate, urine and plasma. OBJECTIVE: To establish a method for determining glutamine concentration in human assisted reproductive media by UPLC-MS/MS. METHODS: The UPLC separation was performed on a SUPELCO Discovery HS F5-3 column (15 cm×2.1 mm, 3 μm) at 40 oC. The mobile phase was acetonitrile and water (both containing 0.1％ formic acid) in a gradient elute mode. The flow rate was 0.35 mL/min. Electrospray ionization with a negative-ion and multiple reaction monitoring mode was used. RESULTS AND CONCLUSION: The linearity was achieved in the range of 0.123 7-24.74 mg/L for glutamine (r=0.999 7). The recoveries were 102.9％-108.2％ with the range 2.3％-4.9％ for the relative standard deviation. The limit of qualification was 9.76 μ g/L. The fertilization culture medium containing glutamine was incubated at 37 oC for 96 hours, in which the glutamine content declined 6％ at 24 hours and 15％ at 96 hours respectively compared with initial content. Therefore, the method is simple, specific, accurate and sensitive without sample derivation, and the test time is short. It is suitable for the quality control of human assisted reproductive media and useful for the risk study related to the degradation of glutamine.

Skin-substitute has developed rapidly and it is essential to evaluate its effectiveness before clinical use.This paper reviews the development of skin-substitute,methods to evaluate the effectiveness of skin-substitute and relevant standards.This paper highlights the and means of preclinical effectiveness evaluation and provides theoretical basis for preclinical safety evaluation of skin-substitute.
Skin, Artificial

Objective To investigate the diagnostic value of multimodal MRI for dual pathology (DP)in temporal lobe epilepsy (TLE).Methods The methods of voxel based morphometry (VBM)and voxel based analysis (VBA)had been employed to study the difference between 36 patients (20 cases left group and 16 cases right group)with TLE caused by DP and 36 healthy subjects on the grey matter (GM)volume,exponential apparent diffusion coefficient (eADC)and cerebral blood flow (CBF)value.The corresponding statistical study had also been conducted.Results There were significant statistical differences (FDR correction,P=0.001)between healthy subj ects and patients on the GM volume,eADC and CBF value.Those values decreased with diseased laterality and wider range in functional imaging.These overlaying abnormal brain regions were located in the temporal pole (superior temporal gyrus), temporal pole (middle temporal gyrus),middle temporal gyrus,inferior temporal gyrus,fusiform gyrus,hippocampus and parahippocampal gyrus which represented in all examination results.Conclusion The combined findings of multimodal MRI can improve the localization ability of seizure focus in TLE,which caused by DP,before surgery.