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.

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.

Objective: To investigate the effect of simple artifacts on the calculation of radiation dose in actual clinical operations by the aid of artificially caused CT artifacts. Methods: The phantom was scanned using CT before and after replacing the titanium alloy component. Then, the CT values were measured at different distances before and after replacement. After correcting the CT value of the titanium alloy region to the CT value of the water phantom, the doses to the phantom were calculated by using Varian′s AAA algorithm, AXB algorithm and Pinnacle system′s CCC algorithm. The absolute dose values at different distances were furtherly analyzed. Results: Varian system was consistent with Pinnacle system in evaluating the CT values. When the CT value deviated by less than 30 HU for a uniform phantom, the dose deviations of the three different algorithms were within 6.0 %-12.0 % at a distance of 0.5 cm from the body surface, and less than 1.0% at a distance of more than 1.5 cm from the body surface. When the CT value deviated by 15 HU for the lung phantom, both Varian′s AAA algorithm and Varian′s AXB algorithm showed about 1.0% dose deviation. However, the CCC algorithm of the Pinnacle system had a significant difference (5.0%) in dose values under the same conditions. Conclusions CT artifacts have noticeable effects on the calculation of radiation dose and change tissue dose distribution which may result in insufficient or excessive exposure doses.