Aminoglycosides (AG) are frequently administered to newborns for treatment of bacterial infection. Despite serum concentration monitoring and extended-interval dosing a significant number of newborns develop renal insufficiency as a consequence of AG therapy. The postnatal development of the kidney may also be impacted by AG-induced changes. Early identification of these changes is therefore important. While various urinary markers have been used to detect changes in tubular function they are neither sensitive nor specific for AG and development of additional biomarkers is needed. Proteomics is a tool to separate and identify differentially expressed proteins that may serve as candidate markers of toxicity and this technique can be used to investigate effects of AG on urinary protein expression. The broad, long-term objective of this research is to develop a tool for early detection of nephrotoxicity in AG-treated newborns via a phased development program. The primary objectives of this application are to identify candidate urinary protein markers of AG-induced toxicity and prioritize candidates based on their discriminatory ability. An exploratory objective is to characterize potential long-term effects of early postnatal AG on renal function. The central hypotheses of this proposal are as follows: (1) The urinary protein expression profile in newborns with AG-induced nephrotoxicity differs from that in treated infants without nephrotoxicity and (2) Differentially expressed urinary proteins and/or protein groups can discriminate between AG-treated newborns with and without nephrotoxicity. These hypotheses will be tested by addressing the following specific aim: Characterize the urinary protein expression profile in AG-treated newborns with and without nephrotoxicity. We have developed techniques to isolate proteins from urine that are well suited for use in newborns and these techniques will be used to create databases of proteins expressed in AG-treated newborn urine. The outcomes of the proposed research will provide important new information regarding effects of the AG on the urinary proteome. Identification of regulated proteins may also reveal candidate markers that can be investigated as part of a phased development plan in further hypothesis-driven research (i.e., R01). If we identify discriminatory proteins we can develop a clinical assay to measure the protein(s) of interest and subsequently assess diagnostic performance. This information may allow us to develop a screening tool to facilitate early diagnosis of AG-induced toxicity that is superior to the current standards of care (serum creatinine and AG levels). The proposed research is directly responsive to the mission of the agency in that it utilizes an "innovative research strategy" to identify potential markers of AG-induced renal damage that may ultimately be used to protect infants. It is also relevant to public health given that the AG are among the most common drugs given to newborn infants. The results of this research may allow us to identify infants who are at risk for developing significant injury before it occurs. [unreadable] [unreadable] [unreadable]