The coadsorption behavior of two complementary DNA bases,adenine(A) and thymine(T),was studied on Au(111) electrode by cyclic voltammetry(CV) and electrochemical scanning tunneling microscopy ( ECSTM) in aqueous solution. From the CVs,the coadsorption behavior of A and T was more closed to the adsorption behavior of A. In the potential range of physisorption,high- resolution ECSTM images of revealed that a new super-structure was formed by the hydrogen bonds between A and T. A molecular model of the super-structure was proposed based on the STM results and the possible hydrogen bonds between A and T.

Objective To detect the spreading scope of rectal cancer to mesorectum by RT PCR using carcinoembryonic antigen (CEA) mRNA as a marker and to investigate the excision scope of mesorectum in resection of rectal cancer. Methods Forty specimens from 40 rectal cancer patients who underwent curative operation was employed to detect the metastatic deposits scattered in the mesorectum by RT PCR using CEA as a marker. Results Nine of 40 (22.5%) specimens contained metastatic deposits scattered in the mesorectum. The metastasis was just within the range of 4cm mesorectum under the verge of tumor. The tumor spreading to mesorectum is correlated with Dukes stages,the infiltrated depth of bowel wall, tumor differentiation and tumor type( P 0.05). Conclusion The excision of mesorectum should be within the range of 5cm under the verge of tumor in surgical management of rectal cancer.

Purpose:To further improve the therapeutic results of ESWL and to reduce the complications of ESWL. Methods: Clinical materials of 5 140 cases of patients with urinary calculi underwent ESWL from 1989 to 1999 were analyzed retrospectively. Results: Ignorance of the routine examination in urine, blood, hepatic func tion and specialization etc, the serious complications may be produced by ESWL. Low energy and emergency ESWL have obtained satisfactory results. Conclusions:Every routine examination is essential to secure the patient to get satisfactory therapeutic result from ESWL and prevent the complication from occurring. Complete dis charge rate of stones was affected by the tissue structure and type of the renal pelvis and calyces, beside the site of stones.

Neurotrophic keratopathy (NK) is a degenerative disease in which damage to the corneal nerves leads to corneal hypoesthesia and even blindness.Traditional NK treatments aim at supporting corneal healing and preventing progression of corneal damage.In recent years, corneal neurotization has made some progress in NK.Compared with traditional treatment, it can not only solve the problem of corneal nerve defect, and avoid the subsequent keratopathy, but also significantly restore corneal sensitivity, corneal epithelium and vision.Corneal neurotization surgery methods are mainly divided into direct corneal neurotization (DCN) and inderect corneal neurotization (ICN).At present, this surgical method has gradually been used clinically, and has achieved satisfactory effects on unilateral NK caused by herpes virus and neuroma, as well as bilateral NK.However, it is little known about the surgical treatment of NK caused by dry eye, diabetes, and chronic glaucoma.In the future, multi-center prospective randomized studies can be conducted to further improve the treatment of NK with other causes.This article introduces this new surgical technique from three aspects, the specific surgical procedures of corneal neurotization, the selection of surgical methods, and the timing of the operation.