Succinate prodrugs as treatment for acute metabolic crisis during fluoroacetate intoxication in the rat.

Sodium fluoroacetate (FA) is a metabolic poison that systemically inhibits the tricarboxylic acid (TCA) cycle, causing energy deficiency and ultimately multi-organ failure. It poses a significant threat to society because of its high toxicity, potential use as a chemical weapon and lack of effective antidotal therapy. In this study, we investigated cell-permeable succinate prodrugs as potential treatment for acute FA intoxication. We hypothesized that succinate prodrugs would bypass FA-induced mitochondrial dysfunction, provide metabolic support, and prevent metabolic crisis during acute FA intoxication. To test this hypothesis, rats were exposed to FA (0.75 mg/kg) and treated with the succinate prodrug candidate NV354. Treatment efficacy was evaluated based on cardiac and cerebral mitochondrial respiration, mitochondrial content, metabolic profiles and tissue pathology. In the heart, FA increased concentrations of the TCA metabolite citrate (+ 4.2-fold, p < 0.01) and lowered ATP levels (- 1.9-fold, p < 0.001), confirming the inhibition of the TCA cycle by FA. High-resolution respirometry of cardiac mitochondria further revealed an impairment of mitochondrial complex V (CV)-linked metabolism, as evident by a reduced phosphorylation system control ratio (- 41%, p < 0.05). The inhibition of CV-linked metabolism is a novel mechanism of FA cardiac toxicity, which has implications for drug development and which NV354 was unable to counteract at the given dose. In the brain, FA induced the accumulation of ß-hydroxybutyrate (+ 1.4-fold, p < 0.05) and the reduction of mitochondrial complex I (CI)-linked oxidative phosphorylation (OXPHOSCI) (- 20%, p < 0.01), the latter of which was successfully alleviated by NV354. This promising effect of NV354 warrants further investigations to determine its potential neuroprotective effects.

Succinate prodrugs in combination with atropine and pralidoxime protect cerebral mitochondrial function in a rodent model of acute organophosphate poisoning.

Pesticides account for hundreds of millions of cases of acute poisoning worldwide each year, with organophosphates (OPs) being responsible for the majority of all pesticide-related deaths. OPs inhibit the enzyme acetylcholinesterase (AChE), which leads to impairment of the central- and peripheral nervous system. Current standard of care (SOC) alleviates acute neurologic-, cardiovascular- and respiratory symptoms and reduces short term mortality. However, survivors often demonstrate significant neurologic sequelae. This highlights the critical need for further development of adjunctive therapies with novel targets. While the inhibition of AChE is thought to be the main mechanism of injury, mitochondrial dysfunction and resulting metabolic crisis may contribute to the overall toxicity of these agents. We hypothesized that the mitochondrially targeted succinate prodrug NV354 would support mitochondrial function and reduce brain injury during acute intoxication with the OP diisopropylfluorophosphate (DFP). To this end, we developed a rat model of acute DFP intoxication and evaluated the efficacy of NV354 as adjunctive therapy to SOC treatment with atropine and pralidoxime. We demonstrate that NV354, in combination with atropine and pralidoxime therapy, significantly improved cerebral mitochondrial complex IV-linked respiration and reduced signs of brain injury in a rodent model of acute DFP exposure.

Perioperative Exposure to Suspect Neurotoxicants From Medical Devices in Newborns With Congenital Heart Defects.

BACKGROUND: Industrial chemicals are increasingly recognized as potential developmental neurotoxicants. Di(2-ethylhexyl) phthalate (DEHP), used to impart flexibility and temperature tolerance to polyvinylchloride, and bisphenol A (BPA), used to manufacture polycarbonate, are commonly present in medical devices. The magnitude of exposure in neonates during hospitalization for cardiac operations is unknown. METHODS: We quantified urinary concentrations of DEHP metabolites and BPA preoperatively and postoperatively in neonates undergoing cardiac operations and their mothers. Urinary concentrations of these biomarkers reflect recent exposures (half-lives are approximately 6 to 24 hours). Biomarker concentrations in mothers' and infants' preoperative and postoperative samples were compared. RESULTS: Operations were performed in 18 infants (mean age, 5 ± 4 [SD] days). The maternal sample was obtained on postpartum day 4 ± 4. The preoperative urine sample was obtained on day-of-life 4 ± 2 and the postoperative sample on day-of-life 6 ± 4. Mean maternal concentrations for DEHP metabolites and BPA were at the 50th percentile for females in the United States general population. Infant preoperative concentrations of 1 DEHP metabolite and BPA were significantly higher than maternal concentrations. Postoperative concentrations for all DEHP metabolites were significantly greater than preoperative concentrations. CONCLUSIONS: There is considerable perioperative exposure to DEHP and BPA for neonates undergoing cardiac operations. Infant concentrations for both BPA and DEHP metabolites were significantly higher than maternal concentrations, consistent with the infant's exposure to medical devices. Further study is needed to determine the potential role of these suspect neurotoxicants in the etiology of neurodevelopmental disability after cardiac operations.