Serum profiling by MALDI-TOF mass spectrometry as a diagnostic tool for domoic acid toxicosis in California sea lions

No single peak was a good classifier of acute DAT, and ANN models were the best predictors of acute DAT. Performance measures for a single median ANN were: sensitivity, 100%; specificity, 60%; positive predictive value, 71%; negative predictive value, 100%. When 101 ANNs were combined and allowed to vote for the outcome, the performance measures were: sensitivity, 30%; specificity, 100%; positive predictive value, 100%; negative predictive value, 59%.These results suggest that MALDI-TOF peptide profiling and neural networks can perform either as a highly sensitive (100% negative predictive value) or a highly specific (100% positive predictive value) diagnostic tool for acute DAT. This also suggests that machine learning directed by populations of predictive models offer the ability to modulate the predictive effort into a specific type of error.The toxicosis associated with domoic acid (DA) ingestion has been linked to massive marine mammal stranding events along the coastal areas of the Western United States [1]. The California sea lion (Zalophus californianus) appears to be the most commonly affected species, likely due to its foraging on fish containing domoic acid [2]. Of sea lions admitted to The Marine Mammal Center (TMMC; Sausalito, CA) between 1998 and 2006 more than 24% were diagnosed with domoic acid toxicosis (DAT), of which 77% were acute DAT [3]. Mortality was significant, regardless of acute or chronic diagnosis, exceeding 40%.Arriving at a diagnosis of DAT is not always straight forward. Clinical signs can be highly variable [4] and diagnosis often requires post mortem information derived from histological examination of the brain. Some of the variability in clinical signs in stranded animals is likely due to variation in ingested dose, the time at which the sea lion strands, and the time at which examination occurs during the course of the intoxication. Clinical suspicion of DAT is based on the observation of abnormal behavior, e.g., ataxia, constant