为研究四环素调控的胰岛素表达载体肌肉直接注射后对实验性糖尿病小鼠的降糖作用，构建了质粒prTA-tet42rhINS。以链脲佐菌素（STZ）诱导Balb/C小鼠成糖尿病模型，300μg质粒注射至小鼠的股部肌肉，并同时在饮水中加入不同浓度强力霉素（Dox），监测小鼠末梢血糖、体重，测定血清人胰岛素、C肽水平。用RT2PCR检测小鼠肌肉注射部位组织中人胰岛素原mRNA水平的表达情况。结果表明：质粒prTA2tet42rhINS注射后，给予Dox可显著降低糖尿病小鼠的血糖，血清人胰岛素、C肽水平相应升高，体重增加。效果持续大约二周。小鼠肌肉组织中有人胰岛素原mRNA表达。降糖效果和基因表达程度随Dox浓度增加而增强。质粒prTA2tet42rhINS对STZ诱导的糖尿病小鼠高血糖起到明显的降低作用。在糖尿病小鼠肌肉组织能很好地表达，并受Dox调控。

Objective:Thirteen urinary nucleosides,primarily degradation products of tRNA,were evaluated as potential tumor markers for breast cancer patients.Design and methods: The micellar electrokinetic chromatography(MEKC)method has been used to analyze the urinary nucleosides in 41 healthy controls,20 patients with benign breast tumors,and 26 breast cancer patients.Results: Urinary nucleoside concentrations of breast cancer patients were found to increase significantly compared to those of patients with benign breast tumors and healthy controls.By using 13 nucleoside concentrations as data vectors for principal component analysis (PCA), 73% (19/26) of breast cancer patients were correctly identified from healthy controls,while only 20% (4/20) of patients with benign breast tumors were indistinguishable from breast cancer patients. The mean level of all forms of urinary nucleosides in patients with metastatic breast cancer was higher than that in patients with primary breast cancer.The levels of modified nucleosides tended to decrease and return to normal after surgery.Conclusion: The results indicate that urinary nucleosides may be useful as tumor markers for breast cancer.