We nave discovered that bilirubin breakdown products are present in the CSF of subarachnoid hemorrhage (SAH) patients. These breakdown products are produced by the oxidation of bilirubin and we call these Bilirubin OXidation products: BOXes. Because they cause vasospasm in vitro and in vivo, and are not found in the CSF of nonvasospasm patients, we believe that the concentration of BOXes will be an objective and quantitative predictor (or assessor) of cerebral vasospasm in SAH patients. Therefore, we will make antibodies against the BOXes and use these new antibodies to diagnose and/or predict cerebral vasospasm by detecting them in the CSF of SAH patients. Following a subarachnoid hemorrhage caused by the rupture of an aneurysm, as many as 40% of the surviving patients develop cerebral vasospasm. Many patients are diagnosed with cerebral vasospasm, but frequently only after they have developed an untreatable stroke. What is needed is a specific, quick and easy method for predicting vasospasm. Currently, there is no specific test for predicting or assessing subarachnoid hemorrhage (SAH) induced cerebral vasospasm. The diagnosis is generally dependent upon clinical parameters such as focal neurological signs and/or angiographically evident vasospasm, and this diagnosis is usually made after there is vasospasm and stroke. We have identified novel molecules in the CSF of SAH patients that are produced by the oxidation of bilirubin and shown that the BOXes (but not pure bilirubin alone) cause vasospasm in vitro and in vivo. This has led us to hypothesize: that BOXes cause cerebral vasospasm following subarachnoid hemorrhage and that the presence and/or concentration of these compounds will predict and correlate with the occurrence of vasospasm. In this project we will make polyclonal antibodies against the three BOXes we have identified and determine the ability of these antibodies to detect BOXes in; 1) control solutions, 2) CSF spiked with known concentrations of BOXes, 3) CSF from vasospasm patients without spiking with BOXes, and 4) correlate the BOX concentrations in CSF to clinical parameters of vasospasm. These data will provide proof of concept that antibodies against BOXes can be used to diagnose and predict vasospasm in SAH patients.