Research advances in chitosan and its derivatives as scaffold for corneal tissue engineering / 眼科新进展

The current problems with corneal transplant,including shortage of donors and immune rejection,could be effectively solved by constructing cornea in vitro with tissue engineering techniques,in which the selection of suitable scaffold materials is especially critical.Chitosan and its derivatives are natural biomaterials with excellent biocompatibility,biodegradability,mechanical property and plasticity,indicating wide application prospects in corneal tissue engineering.This article systematically reviews the research advances in chitosan and its derivatives in corneal tissue engineering,and the existing problems are also highlighted in order to provide theoretical basis for further clinical research.

Preparation and properties of carboxymethyl chitosan calcium / 中国组织工程研究

BACKGROUND: Carboxymethyl chitosan is a water-soluble derivate modified from chitosan, with various biological activities. It is a good ligand of metal ion and can integrate Ca~(2+) to prepare a novel biological material. OBJECTIVE: To explore a method for preparing carboxymethyl chitosan calcium (CCC) and analyze its properties and structure. METHODS: CCC was produced by carboxymethyl ohitosan reacting with solution of calcium chloride. The solubility, carboxymethylation degree, rotational viscosity, and calcium content of CCC were determined, and infrared and ultraviolet spectral analyses were performed.RESULTS AND CONCLUSION: The calcium content of CCC was approximately 15%. Compared with carboxymethyl chitosan, infrared spectrum and ultraviolet spectrum of CCC were changed. The prepared CCC is a new calcium compound through property and structural analysis.

Feasibility study of Shuyisha as hemostasis and repair material for liver wound / 中华创伤杂志

Objective To discuss the feasibility of Shuyisha as hemostasis and repair material for liver wound. Methods Hemolysis rate, acute toxicity and eytotoxicity of Shuyisha were measured. A hemorrhage model was established by making an open wound (5 mm× 3 nun ×2 mm) on the left liver lobe of mice. Hemostasis was performed with Shuyisha in experimental group and with Surgicel in control group, when the hemostatic time and total blood loss (TBL) were accurately recorded and regular macro-scopic and histological observation carried out. Results The hemolysis rate of Shuyisha was 2.33%, with maximum tolerance does of over 0.48 g/kg and the eytotoxicity at zero. The hemostatie time of Shuy-isha was (5.00 ±0.00) s, with total blood loss of (0.88±0.18) g/kg, better than Surgicel (P< 0.05). Shuyisha was degraded completely within 14 days, with the wound healed within 21 days in ex-perimental group, much better than Surgieel. Conclusions The hemolysis rate, acute toxicity and cy-totoxicity of Shuyisha are up to the requirement of biomedical materials. Shuyisha has effective hemosta-sis, which may be related to its molecular structure and adhesion.

Preparation and cytocompatibility of chitosan-based carriers of corneal cells / 生物工程学报

To study the possibility of using hydroxypropyl chitosan-based blend membranes as carriers of corneal cells in tissue engineering, we prepared three kinds of blend membranes labeled hydroxypropyl chitosan/chondroitin sulfate, hydroxypropyl chitosan/gelatin/chondroitin sulfate and hydroxypropyl chitosan/oxidized hyaluronic acid/chondroitin sulfate. The transparency, water content and ability of protein adsorption of the blend membranes were measured. To evaluate the cytocompatibility of the blend membranes with corneal epithelial cells, rabbit corneal epithelial cells were cultured on the surface of the carrier membranes. The morphological characteristics, cell adhesion, cell proliferation and the activity of lactate dehydrogenase (LDH) in the media were investigated. Three kinds of blend membranes had good optical transmittance, suitable water content and ability of protein adsorption. The results showed that the less injury was made to corneal epithelial cells by the hydroxypropyl chitosan/gelatin/chondroitin sulfate blend membrane than the others. This kind of membrane was favor of the growth and adhesion of corneal epithelial cells. The hydroxypropyl chitosan/gelatin/chondroitin sulfate blend membrane is a promising carrier of corneal cells and can be used in reconstruction of tissue engineered cornea.

Preparation of carboxymethyl-chitosan with different molecular weight and its effects on proliferation of skin fibroblasts and keratinocytes / 生物医学工程学杂志

Effects of carboxymethyl-chitosan (CM-Chitosan) with different molecular weight on the proliferation of skin fibroblasts and keratinocytes were examined in vitro; bFGF and EGF, as controls, were seperately used for comparison. Chitosan with different molecular weight was prepared by acid degradation and oxidation degradation; CM-Chitosan with different molecular weight was synthesized from corresponding Chitosan. Microscopy and MTT method were applied to evaluate the different effects. The results demonstrated that CM-Chitosan with different molecular weight promoted the proliferation of skin fibroblasts and keratinocytes at 1-1000 ppm, and the concentration at 100 ppm had the strongest effects. The effects of low molecular weight CM-Chitosan were greater than those of high molecular weight CM-Chitosan. CM-Chitosan (Mn= 3KD) had the strongest promotive effects on skin fibroblasts and keratinocytes; it had equivalent effects when compared with bFGF and EGF.

The effect of the degree of deacetylation of chitosan on the biocompatibility of chitosan membrane with corneal stromal cells / 生物医学工程学杂志

Some different membranes were prepared by Chitosan with the degree of deacetylation (DD) of 63.7%, 73.7%, 83% and 97% respectively. To study the biocompatibility of Chitosan membrane toward corneal stromal cells, the rabbit cells were cultured on the surface of different DD chitosan membranes. The morphological characteristics, the cell-adhesion, the cell proliferation and the activity of LDH in the medium were investigated. The results of experiment shows that the DD of Chitosan has very significant effect on the biocompatibility of Chitosan membrane toward corneal stromal cells. The more DD of Chitosan, the less injury was made to corneal stromal cells by the chitosan membrane, which is favor of the growing and adhesion of corneal stromal cells. The biocompatibility of the membrane made with low DD Chitosan with corneal stromal cells became worse.

Factors influencing the in vitro culture of osteoblasts / 中国组织工程研究

OBJECTIVE: Osteoblasts are essential for osteogenesis and bone metabolism, the in vitro culture of osteoblasts is the foundation for studies on bone metabolism and osteogenetic mechanism. Therefore, it is of great significance to study the related factors affecting it.DATA SOURCES: Related literature about the influencing factors of in vitro culture of osteoblasts were searched for in Medline from January 1980 to December 2004 with retrieval words of "osteoblasts, culture in vitro, in fluencing factors", with the language limited to English. Meanwhile, it was also searched in the CBM between January 1995 and December 2004 with the retrieval words of "osteoblasts, in vitro culture, influencing factors",with the language of the articles limited to Chinese.STUDY SELECTION: After preliminary examination, literature that met the need of this study was searched for the full text. Inclusion criteria: Factors influencing the in vitro culture of osteoblasts included ① physical factors; ② microelements; ③ growth factors; and ④ hormones.Reviews were removed from this study because of summary or repetitive research.DATA EXTRACTION: A total of 105 articles related to the influencing factors of the in vitrocul ture of osteoblasts were obtained, articles of repetitive and similar researchwere removed; thereby 17 articles were included in the study.DATA SYNTHESIS: ① Physical factors: Ionizing radiation, microgravity,external force, and oxygen pressure. ② Microelements: microelement deficiency would hinder the skeletal growth, or even lead to malformation. Osteoblastic proliferation is closely related to some microelements, mainly including zinc, aluminum, fluorine, copper, manganese, calcium, and magnesium. ③ Growth factors closely related to osteogenesis mainly consist of bone morphogenetic protein, platelet-derived growth factor, fibroblast growth factor, transforming growth factor-beta, insulin like growth factor,and osteogenic growth peptide (OGP). ④ Hormones capable of promoting the proliferation and differentiation are growth hormone, estrogen, thyroxine, parathyroxine, and glucocorticosteroid.CONCLUSION: Multiple factors are involved in the in vitro culture of osteoblasts. It is helpful to understand these influencing factors to seek an effective way for the in vitro culture ofosteoblasts that is applied in tissue engineering.

The research actualities of chitinase and prospects / 中国海洋药物

Chitinase (EC3.2.1.14) catalyses the reaction of hydrolyzing the chitin into N acetylglucosamine (GlcNac) and (GlcNac) n.With the in deep study of chitinase,more and more biological function of chitinase appeared obviously.Now,we introduce the actualities of chitinase research,including substrate specificity,physiological function,antifungi function and transgenics, et al .

Determination of number average molecular mass of chitosan-oligosaccharide by acetylacetone method / 中国海洋药物

To determine the number average molecular mass of chitosan-oligosaccharide by u-sing the acetylacetone's method based on the color-producing reaction with amino terminal . Via the tests on the repetitiveness, accuracy and the stability, supposed this method was reliable. At the same time, the contrastive results of HPLC and the traditional K3Fe(CN)6 method indicate that the acetylacetone method was more suitable for the determination of chitosan-oligosaccharide molecular mass.

Characters of the chemical structure of CM-chitosan / 中国海洋药物

The characters of the chemical structure of CM-chitosan were studied, by assay the content of the N, carboxylation, Primary amine and DEPT,13C-NMR of CM-chitosan.

Screening of alginate producing strain and optimization of fermentation condition / 中国海洋药物

Objective A strain with high alginase activity was screened and isolated by decomposing sodium alginate from the decaying parts of brown alga Laminaria japonica and Undaria pinnatifida,in order to produce alginase.Methods The strain s4 with high alginase activity was chosen by filtration.The alginase producing media was optimized and the alginase was produced and its characterization was investigated.Results The optimum fermentation conditions for alginate lyase producing as follows: media AlgNa 1.2%,NH4Cl 0.9%,NaCl 1.5%,pH=7.5,and temperature 25℃.Conclusion The alginase produced by strain s4 showed high alginase activity and good stability.

Study on lead expelling effect of carboxymethyl chitosan calcium in lead poisoned mice / 中国海洋药物

Objective To observe the effect of carboxymethyl chitosan calcium(CCC) on the concentration of lead,calcium,and liver antioxidative capacity in lead poisoned mice.Methods mice were randomly divided into 6 groups.Three test groups were treated with CCC at three doses.The lead poisoned mice model was established by giving water containing lead acetate,and then CCC was administered to mice once a day.After 30 days,the mice were killed and the content of lead in blood,liver,brain and femur were determined by atomic absorption spectrophotometer,and antioxidative capacity in liver was measured using assay kit.Results CCC could reduce the contents of lead in blood,brain,liver and femur significantly,decrease the level of maleicdialdehyde(MDA),increase activities of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and total antioxidative capacity(T-AOC) in liver markedly. Conclusion CCC can promote the excretion of lead,increase the content of calcium in femur and antioxidative capacity in lead poisened mice.

Preliminary studies on the antitumor activities of D-glucosamine and its derivatives / 中国海洋药物

Objective The growth inhibitory effects of GlcNH_2?HCl,GlcNH_2 and NAG on human hepatoma SMMC-7721 cells in vitro was investigated.The antitumor activity of GlcNH_2?HCl against Sarcoma_(180) in KM mice was also investigated.Methods The cell viability in vitro was examined with MTT assay.DNA isolation and cell-cycle analyses were also performed.GlcNH_2?HCl was ig administered to Sarcoma_(180) KM mice.The inhibition rates,spleen and thymus index were calculated.Results GlcNH_2?HCl and GlcNH_2 resulted in a concentration-dependent reduction in hepatoma cell growth.The inhibition rates against SMMC-7721 cell of GlcNH_2?HCl and GlcNH_2 at concentration of 500?g?mL~(-1) were(50.24)% and 52.19%.As to the concentration of 1000?g?mL~(1), the rates were(82.21%) and 83.20%.This effect was accompanied by a marked increase in the proportion of S phase cells.Compared with the control,there was no significant difference among various concentrations of NAG,GlcNH_(2)?HCl exhibited inhibitiory effect against Sarcoma_(180) in mice at the dosage of 125～500 mg?kg~(-1),and the inhibition rate was about 27.84%～34.02%.The optimal inhibitory effect was 250 mg?kg~(-1).GlcNH_2?HCl could enhance the weights of thymus and spleen.In addition,it could promote lymphocyte transformation.Conclusion It is therefore postulated that the antitumor effect of GlcNH_2?HCl is probably host-mediated and cytocidal.

Screening of a high yield protease producing strain and studies on its fermentation conditions / 中国海洋药物

A1 strain with fibrinolytic activity was isolated from sea water in Qingdao. After combination treatment with ultraviolet light and MNNG, a mutant C22 producing 2947.60 u?mg -1 protein of fibrinolytic enzyme in culture broth was obtained.Its enzyme activity was 4.23 fold of wild stain A1.The optimum medium for fermentation consisted of 2.5% soy bean cake meal, 0.1% yeast extract,0.2%NaCl,0.05%MgSO 4?7H 2O,0.001%FeSO 4?7H 2O.They were dissolved with 0.05mol?L -1 ,pH7.4 phosphoric buffer.The strain producing maximum fibrnolytic activity after growth at 25℃ for 40h on a rotary shaker.The initial optimum pH was 7.0~7.5.

EFFECTS OF GLUCOSAMINE ON IMMUNE FUNCTION IN MICE / 营养学报

Objective:To study the effects of glucosamine(GlcNH2) on immune function in mice.Method:The effects of GlcNH2 on murine proliferation of splenocytes were carried out in vitro.After feeding mice by GlcNH2,the phagocytotic functions of mononuclear macrophage,murine delayed type hypersensitivity(DTH) caused by sheep red blood cells(SRBC),the ability of antibody production(tested by HC50),and the index of immune organs(thymus and spleen) were deteimined in vivo.Results:GlcNH2 could promote the proliferation of splenocytes,phagocytotic functions of mononuclear macrophage,DTH,the ability of antibody production and the index of immune organs.Conclusion:Glucosamine can enhance immune function in mice such as cellular immunity,humoral immunity and non-specific immunity.