英语与写作Exercise.doc

Exercise Iohexol （碘海醇）is not bound to serum proteins （血清蛋白）and is filtered through the glomerulus (肾小球), with no identifiable reaborption (再吸收)or tubular secretion (肾小管分泌), making it an ideal marker for estimating GFR. Ultraperformance liquid chromatography (UPLC) (超高效液相色谱法), a recently introduced modification of LC, allows rapid chromatography owing to faster gradient curves （梯度曲线）, as well as the potential to use smaller particles and higher flow rates (流量；流率). Protocols have been developed that involve a single intravenous injection (静脉注射)of iohexol followed by timed blood collections. Iohexol is an iodinated contrast dye (碘化造影染料)that has been shown to be useful in clearance studies for the determination of GFR. We have combined these two techniques to develop a UPLC-MS/MS assay for iohexol in human serum that uses a simple sample preparation, a structural analog internal standard with the same retention time （保留/滞留时间）, and a ballistic gradient for rapid chromatographic analysis. Both of these techniques require lengthy run times to separate iohexol from endogenous (内生的，内源的)interfering compounds and the internal standards. In the subset of patients with suspected renal insufficiency （肾功能不全）for whom it is important to have an accurate assessment of glomerular filtration rate (GFR) （肾小球滤过率）, clearance measurements (间隙测量)provide the best information. No urine collection or quantification in urine is necessary, an advantage over iothalamate (碘酞酸盐), the other agent used for GFR studies. By comparison, the high selectivity of tandem mass spectrometry (MS/MS)(串联质谱法) as a detector generally allows simpler specimen cleanup and shorter chromatographic times compared with UV detection. 10. The majority of published methods for quantifying iohexol have used capillary electrophoresis (毛细管电泳)or gradient elution liquid chromatography (LC) (梯度洗脱高效液相色谱法)coupled with ultraviolet (紫外线) (UV) detection. Answer: In the subset of patients with suspected renal insufficiency for whom