BACKGROUND: As a metal internal fixation material, magnesium alloy has more unique advantages, such as biodegradability and elastic modulus. The elastic modulus of magnesium alloy is similar to the compact bone,which is enough to avoid stress-shelter effect. However, biological activity represents bonding ability with the bone in the body for fracture fixation materials, which is of great significance for studies on new kinds of magnesium alloys.OBJECTIVE: To observe the microstructure of Mg-Zn-Gd alloys and to analyze the corrosion products on the material surface after immersed in simulation body fluid.METHODS: The Mg-Zn-Gd alloys were manufactured by the method of fusion casting. Scanning electron microscope with spectrometer was applied to observe microstructure and distribution of precipitated phase and corrosion products of Mg-Zn-Gd alloys in simulated body fluid.RESULTS AND CONCLUSION: The Mg-Zn-Gd alloy was composed of α-Mg solid solution containing Gd and Zn elements and eutectic structure. The eutectic structure was almost feathery, oval-shaped, herringbone-shaped and strip-shaped along the grain boundary. The main ingredients of eutectic structure included Mg, Zn and Gd elements.Deposition layer was composed of O, Mg, Ca and P elements on the surface of Mg-Zn-Gd alloy after 72 hours soak in Hank's solution. X-ray diffraction analysis showed that film layer contained Mg(OH)2 phase, which promoted calcium salt deposition and reduced the corrosion rate. So Mg-Zn-Gd alloy can obtain better biological activity.

BACKGROUND:Magnesium al oy as a fracture fixation material has mechanical properties similar to the bone, good biocompatibility and biodegradability, but its rapid degradation rate in body fluids becomes a clinical bottleneck. Therefore, the use of surface treatments to improve its corrosion resistance is important.
OBJECTIVE:To use magnetron sputtering technology and alkali heat treatment technology in the preparation of coating characterized as both corrosion resistance and biological activity.
METHODS:First, we prepared Mg-Zn-Mn al oy using the smelting technology, and prepared a dense coating on the al oy surface by the magnetron sputtering technique. Then, we processed the coating surface using an alkaline solution, and studied the corrosion behavior of the coating by use of simulated body fluid experiments. We speculated the biological activity of the coating by measuring the content of calcium and phosphorus from the surface products.
RESULTS AND CONCLUSION:We prepared the coating, which had both corrosion resistance and biological activity, on the surface of magnesium al oy by use of magnetron sputtering and alkali heat treatment technology. After soaking in the simulated body fluid for 24 hours and 168 hours, the deposition of the coating surface contained Ca, P products. Ca/P ratios were 1.54 and 2.11, respectively, closed to the bone-phosphate Ca/P ratio. The coating surface formed 5-10μm pitting after 24 hours of immersion, and the pitting grew up with the immersion time. The pitting was enlarged to 100-800μm after 168 hours.

Objective To compare the safety and efficiency of laparoscopic transabdominal preperitoneal (TAPP) and totally extraperitoneal (TEP) procedure for herniorrhaphy. Methods Between Jan 1997 and Jan 2005, 235 patients (274 hernias) underwent laparoscopic inguinal hernia repair with 163 TAPP in 139 patients and 111 TEP procedures in 96 patients. Postoperative patients were followed-up for 6-24 months. Results No conversion was necessary. There were no significant differences between TAPP and TEP when considering operating time, postoperative hospital stay, VAS and time to return to daily activity. The recurrence rate was 1. 8% and 0. 9% respectively in TAPP and TEP( P = 0. 524). The total incidence of postoperative complications were 15. 3% and 10. 8% respectively ( P = 0. 282 ) , with seroma, transient neurapraxia and urinary retention being 5. 5% vs. 4. 5% ( P = 0. 707 ) , 5. 5% vs. 3. 6% ( P = 0.464) and 3. 1% vs. 2.7%(P = 1.000). The inhospital cost was significantly higher in TAPP than in TEP(P=0.000). Conclusion TAPP and TEP are both safe and efficient tension-free technique. Surgeons' experience was more important than choice of approach to laparoscopic repair for groin hernias.

ObjectiveTo evaluate intraoperative cholangiography (IOC) and laparoscopic ultrasonography (LUS) for detection of occult common bile duct stones (CBDS) during laparoscopic cholecystectomy (LC). Methods From Jun. 2000 to Sep. 2001, 98 patients undergoing LUS and IOC during LC were analyzed prospectively.Results[The successful rate of LUS and IOC were 100% and 95% respectively, the time for LUS (7 7?2 1) min was significantly shorter than IOC (11 4?3 5) min ( P 0 05). The visualization of intrapancreatic portion of CBD by LUS was 62% vs 97% by IOC ( P

Objective To evaluate the expression of vascular endothelial factor ( VEGF) -D in predicting the prognosis of colorectal carcinoma (CRC). Methods Between Jan 1996 and Jan 1998, 69 patients with CRC undergoing curative surgery were included in this study. Postoperative follow-up included physical examination, serum CEA, and imaging every 3 months in the first and the second year, every 6 months in the third year and once a year thereafter. The expression of VEGF-D protein and microvessel density ( MVD ) in 69 tissues of CRC and 20 normal colorectal tissues was examined by immunohistochemistry (IHC). Results of IHC staining were quantified by Axioplan 2 imaging analysis system. Results VEGF-D protein expression in the cytoplasm was found in all of the CRC tissues and 25% (5/20 ) of normal tissues. The VEGF-D expression was much higher in tumor tissue than in the corresponding normal tissue (P