Leigh syndrome is a fatal pediatric neurodegenerative disease caused by mitochondrial dysfunction, which can be modeled in the Ndufs4 KO mouse with mitochondrial respiratory chain complex I (CI) deficiency. This study explores NV354, a prodrug of succinate with enhanced oral bioavailability and brain uptake, as a potential therapy to counteract this devastating condition. NV354 modulated whole-body respiration and metabolic flexibility, prevented late-stage motor dysfunction, delayed clinical ataxia scores, and improved body weight development, but had otherwise minimal effect on neurobehavior and lifespan of the animals. The succinate prodrug prevented development of the brain stem lesions pathognomonic for Leigh syndrome, attenuated neuronal loss in the brainstem, diminished activation of astrocytes, blocked hypertrophic microglial accumulation, and reduced reactive oxygen species (ROS) levels in the brain. NV354 also partially alleviated motor symptoms and metabolic decompensation in a rat model of Parkinson disease induced by the CI inhibitor rotenone. In conclusion, the succinate prodrug NV354 shows promise as a potential treatment of mitochondrial CI-related neurodegeneration.

Carbon monoxide (CO) poisoning remains a major cause of toxicologic morbidity and mortality and is a leading cause of acute neurologic injury among poisoned patients, yet the mechanisms underlying cerebral bioenergetic dysfunction remain incompletely understood. In addition to impaired oxygen delivery through carboxyhemoglobin (COHb) formation, CO poisoning is associated with mitochondrial respiratory dysfunction and cerebral metabolic injury. We characterized systemic physiology, cerebral metabolism, mitochondrial bioenergetics, and exploratory translational biomarkers in a swine model of acute CO poisoning. Yorkshire swine underwent sham exposure or inhalational CO exposure at 1,000 or 2,000 ppm with serial physiologic monitoring, arterial blood gas analysis, cerebral microdialysis, high-resolution mitochondrial respirometry, ATP quantification, western blotting, and histologic/immunohistochemical analyses. Peripheral blood mononuclear cell (PBMC) mitochondrial respiration was explored as a systemic correlate of cerebral mitochondrial function. CO exposure produced dose-dependent elevations in COHb and lactate with associated metabolic acidosis and hemodynamic impairment. Cerebral microdialysis demonstrated variable lactate-to-pyruvate ratios, whereas extracellular glycerol was significantly elevated during late exposure/recovery following severe CO exposure, consistent with membrane injury and metabolic dysfunction. Mitochondrial respiration was impaired in both cortical and hippocampal tissue, with Complex IV-linked respiration among the most consistently affected respiratory states. Cortical ATP content was significantly reduced in severely exposed animals, supporting cerebral bioenergetic failure. Western blot analysis demonstrated increased HO-1 expression without significant reductions in citrate synthase or Complex IV protein abundance, suggesting functional respiratory inhibition rather than loss of mitochondrial content. Collectively, these findings demonstrate that acute CO poisoning produces early cerebral bioenergetic dysfunction characterized by impaired mitochondrial respiration, ATP depletion, and metabolic alterations, while supporting the exploratory potential of PBMC mitochondrial respiration as a translational biomarker of cerebral mitochondrial dysfunction.

Background and purpose:Ultra-high dose rate (UHDR) irradiation is being investigated as a strategy to widen the therapeutic window of radiotherapy, but the biological mechanisms that distinguish UHDR from conventional dose rate (CONV) irradiation remain unresolved. Because mitochondria integrate bioenergetics, redox control and stress signaling after irradiation, they represent a plausible site at which dose-rate effects could emerge. This study evaluated mitochondrial function after CONV and UHDR irradiation in a head and neck squamous cell carcinoma in vitro model. Materials and methods:LU-HNSCC4 (HN4, an oral cavity HNSCC cell line) cells and VH10 fibroblasts were treated with 0, 2, 6, 10 or 20 Gy delivered at CONV or UHDR using electron irradiation from a modified linear accelerator. High-resolution respirometry was performed immediately after irradiation and 48 h later. In the 0 and 20 Gy groups, flow cytometry was used to assess cellular reactive oxygen species (ROS), mitochondrial ROS (mtROS), mitochondrial membrane potential (MMP) and Magnesium Green fluorescence as an indirect ATP-related readout. RNA sequencing was performed in HN4 cells 48 h after 20 Gy. Results:Irradiation induced clear dose- and time-dependent increases in oxygen consumption in HN4 cells, affecting routine respiration, oxidative phosphorylation capacity and maximal electron transfer capacity. The effect was strongest at higher doses and at 48 h and involved both complex I- and complex II-linked pathways. No statistically significant differences between dose-rate modalities were detected for the principal respiratory endpoints. Flow-cytometric analyses at 20 Gy showed stress responses in both irradiation arms, with some possible differences in temporal pattern; but without a clearly distinct overall phenotype attributable to dose rate. Conclusion:The data support a model in which both CONV and UHDR engage a broadly similar post-irradiation mitochondrial adaptive program in HN4 cells. The findings are relevant to the study of radiation adaptation and support further testing of mitochondria-directed radiosensitization strategies in head and neck cancer.

Carbon monoxide (CO) poisoning is a leading cause of environmental poisoning in the United States and can impair cellular metabolism through both hypoxia and direct mitochondrial toxicity, particularly via inhibition of cytochrome c oxidase (Complex IV, CIV). In this study, we performed a comprehensive assessment of the cerebral metabolic response to CO exposure in a swine model. Twenty-nine swine (∼10 kg) were assigned to three groups: Sham (n = 10), CO 1000 ppm (n = 8), and CO 2000 ppm (n = 11). Animals in the CO groups were exposed to CO for 120 min followed by 30 min of room air. Cerebral metabolism was assessed using invasive cerebral microdialysis and continuous non-invasive diffuse optical monitoring of cerebral blood flow, oxygenation, and CIV redox state. Following the exposure period, brain tissue was harvested for mitochondrial respiration analysis and western blotting. Severe CO exposure (2000 ppm) produced significant cerebral metabolic impairment, demonstrated by decreased oxidation of cytochrome-c-oxidase, reduced oxygen metabolism, and increased microdialysis markers of metabolic stress including lactate-to-pyruvate ratio and glycerol. In contrast, moderate CO exposure (1000 ppm) resulted in minimal metabolic changes despite elevated carboxyhemoglobin levels. Ex-vivo mitochondrial respirometry also demonstrated impaired mitochondrial respiration in CO-exposed animals. These findings demonstrate greater cerebral metabolic dysfunction with higher CO exposure and suggest that carboxyhemoglobin levels alone may not accurately reflect the degree of cerebral metabolic injury.

Purpose The purpose of this in-depth interview study was to explore how parents of children with sensorineural hearing loss (SNHL) experienced genetic testing and whether they experienced risks and benefits. Background Most children with SNHL have a genetic etiology, which can be identified through genetic sequencing. A genetic test does not influence treatment, and whether patients and parents perceived genetic tests as valuable is unclear. Methods In this study, 10 parents of children with SNHL who underwent genetic testing were interviewed, and the content was analyzed using inductive thematic analysis. Results Three global themes were identified. In the first theme, (1) Limited knowledge creates uncertainty, parents described uncertainty related to the information provided, the test result itself and child-related factors. The second theme, (2) Genetic knowledge is considered important for the family and the future, explored the importance of knowledge. Parents wanted an explanation to make the future predictable, and the test had practical implications. In the last category, (3) Knowledge adds complexity and can be challenging, ethical considerations and risks associated with knowledge were highlighted. Conclusion The main conclusion was that parents experienced that genetic testing provided valuable personal information and had practical implications. However, a genetic diagnosis can cause concern and may affect family planning.

Organophosphate (OP) compounds are widely used agricultural chemicals that pose significant public health and chemical threat concerns due to their neurotoxic effects. Although OP toxicity has classically been attributed to acetylcholinesterase inhibition and cholinergic crisis, emerging evidence suggests mitochondrial dysfunction may represent an additional and clinically relevant mechanism of injury. Experimental OP exposure has been associated with impaired electron transport chain activity, reduced ATP production, increased oxidative stress, and disruption of mitochondrial membrane integrity. However, there are currently no established mitochondrial-targeted therapies for OP poisoning. Diisopropyl fluorophosphate (DFP), a well-established OP surrogate, reproduces several neurologic and mitochondrial features of nerve agent exposure. Cyclosporine A (CsA), an inhibitor of the mitochondrial permeability transition pore (mPTP), may represent a potential mitochondrial-targeted intervention. This preliminary translational study employed both in vitro and in vivo models to evaluate mitochondrial respiratory dysfunction following acute DFP exposure and to explore the feasibility of mitochondrial-targeted treatment paradigms using CsA. Human donor-derived peripheral blood mononuclear cells (PBMCs) were used for DFP and CsA dose-finding and mitochondrial respiratory characterization using high-resolution respirometry (Oroboros O2k) with standardized substrate–uncoupler–inhibitor titration (SUIT) protocols. In parallel, a non-survivor Sprague–Dawley rat model of acute DFP exposure was developed incorporating invasive hemodynamic monitoring, controlled ventilation, venous blood gas analysis, and CsA treatment paradigms administered either following DFP exposure or as pretreatment prior to exposure. Brain cortical homogenates were prepared for ex vivo respiratory assessment. Preliminary findings demonstrated that DFP exposure was descriptively associated with impaired mitochondrial respiration across multiple oxidative phosphorylation (OXPHOS)- and electron transport system (ETS)-linked respiratory states in both PBMC and rodent models. DFP exposure was additionally associated with physiologic and metabolic derangements, including acidosis and elevated lactate concentrations. Post-DFP CsA administration was associated with partial preservation of mitochondrial respiration across several respiratory states, while the Pre-DFP CsA group demonstrated respiratory profiles more closely approximating control values in select OXPHOS- and ETS-linked states, accompanied by relatively preserved physiologic and metabolic parameters. These preliminary findings support the feasibility of integrating mitochondrial respiratory phenotyping into translational models of acute OP toxicity and further support investigation of mitochondrial-targeted strategies in OP-associated mitochondrial dysfunction. The observed respiratory and physiologic trends associated with CsA exposure, particularly in the pretreatment paradigm, provide an exploratory foundation for future preclinical studies evaluating mitochondrial-directed countermeasures in OP poisoning.

Sudden sensorineural hearing loss (SSNHL) is defined as 30 decibels (dB) hearing loss in 3 consecutive frequencies occurring within 72 h. Pure-tone average of four frequencies (PTA4) is commonly used to evaluate hearing levels but may not accurately reflect the recovery. We aimed to identify prognostic factors for recovery and to evaluate how recovery should be assessed, by comparing PTA4 with an individual pure-tone average (iPTA), including solely the hearing thresholds for the affected frequencies. Demographic, clinical, and audiologic factors were analyzed using multivariable linear and logistic regression models. A Bland-Altman plot was used to compare recovery measurements based on iPTA and PTA4. In this cohort, the mean age was 57 years (range 19–91 years). Dizziness was a prominent negative predictive factor (logistic regression: iPTA OR 0.09 95

Carbon monoxide (CO) is a leading cause of environmental poisoning in the United States with substantial mortality and morbidity. The mechanism of CO poisoning is complex and includes hypoxia, inflammation, and mitochondrial dysfunction. Currently both biomarkers and therapies for CO poisoning are limited and require new approaches. Rats ( 300 g) were divided into four groups of ten rodents per group (exposure): Control (room air), CO-400 (400 ppm), CO-1000 (1000 ppm) and CO-2000 (2000 ppm). Rodents received the assigned exposure through a secured tracheotomy tube over 120 min followed by 30 min of re-oxygenation at room air for a total of 150 min. Five additional rodents in each group were administered a succinate prodrug (NV354) at the start of exposure for the duration of the experiment until the reoxygenation period as separate experiments. Cortical brain tissue and whole blood were obtained for mitochondrial respiration. Stored plasma and snap frozen tissue stored at -80oC were used to obtain protein quantification with Western Blotting. All animals in the Sham, CO-400, and CO-1000 groups survived until the end of the exposure period; no animals in the CO-2000 groups survived the exposure and were counted as attrition. We observed a dose-dependent decrease in key respiratory states in both isolated brain mitochondria and peripheral blood mononuclear cells (PBMCs), and, PBMCs respiration more positively correlated with isolated brain mitochondria when compared to carboxyhemoglobin (COHb). There was no significant difference in mitochondrial respiratory states in animals treated with NV354 compared to the untreated group. The primary findings from this study include: (1) A dose-dependent decrease with key respiration states with higher concentrations of CO; (2) PBMCs had a higher correlation to isolated brain mitochondria respiration when compared to COHb; and (3) there was no treatment effect with the use of NV354.

ImportanceThe genetic variation in patients with sensorineural hearing loss (SNHL) in the Nordic countries has not been previously reported.ObjectivesThe aim was to describe the genetic variation in a Swedish population and identify factors in favor of a high diagnostic yield.DesignThis was a prospective cohort study. Children with bilateral SNHL and adults with bilateral SNHL and clinically suspected genetic SNHL underwent genetic testing. A gene panel with ~200 genes was applied on whole genome sequencing (WGS) data. Variants were classified according to American College of Medical Genetics and Genomics criteria. Personal health data were extracted from medical records.Setting and ParticipantsEighty-five patients (aged 0-73 years) from Lund and Örebro University Hospitals, 2 tertiary referral centers for audiology in Sweden, with mild to profound SNHL.ResultsIn almost half (45%, n = 38) of the cases, a genetic cause was identified across 24 different genes. Eleven cases had syndromic hearing loss. A majority (n = 57) had prelingual onset (<2 years) of SNHL and most of them had moderate-to-profound hearing loss (n = 52). Prelingual onset was associated with higher yield than postlingual onset (OR 6.3, 95% CI 2.1-19.0). In patients with moderate-profound prelingual SNHL, the diagnostic yield was 60% (n = 31/52).ConclusionThis is the first reported cohort of hearing loss patients undergoing genetic testing with WGS from a Nordic country. Early onset of hearing loss favored a higher diagnostic yield than postlingual, and a genetic cause was found in a majority of cases in patients with prelingual, moderate-to-profound SNHL.

Antibiotics are crucial in treating infectious diseases, particularly in intensive care unit patients, but they can lead to side effects such as ototoxicity. A mechanism for this is antibiotics targeting mitochondrial components in eucaryotic cells, due to their resemblance of those in bacteria. Here we investigate how five classes of antibiotics (carbapenems, fluoroquinolones, aminoglycosides, glycopeptides, and oxazolidinones) affect mitochondrial respiratory function, ATP levels, mitochondrial membrane potential and levels of reactive oxygen species in an inner-ear derived epithelial cell line (HEI-OC1) and human primary blood cells (PBMCs) at clinically relevant concentrations.Mitochondrial respiration in intact HEI-OC1 cells was suppressed in response to the majority of the tested antibiotics. This effect was lost when the HEI-OC1 cells were permeabilized and substrate supply controlled. Further in these cells, ROS levels were increased and ATP levels reduced. In contrast, no measure of mitochondrial function of PBMCs was affected by any antibiotics at the same concentration. We show that HEI-OC1 cells are sensitive to a broad range of antibiotics, and that the mechanism of toxicity to mitochondrial respiration is upstream of the mitochondrial respiratory chain, with downstream effects on mitochondrial respiration, ATP levels and ROS levels.

Mitochondrial dysfunction is considered a hallmark of aging. Up to now, a gradual decline of mitochondrial respiration with advancing age has mainly been demonstrated in human muscle tissue. A handful of studies have examined age-related mitochondrial dysfunction in human blood cells, and only with small sample sizes and mainly in platelets. In this study, we analyzed mitochondrial respiration in peripheral blood mononuclear cells (PBMCs) and platelets from 308 individuals across the human lifespan (0–86 years). In regression analyses, with adjustment for false discovery rate (FDR), we found age-related changes in respiratory measurements to be either small or absent. The main significant changes were an age-related relative decline in complex I-linked respiration and a corresponding rise of complex II-linked respiration in PBMCs. These results add to the understanding of mitochondrial dysfunction in aging and to its possible role in immune cell and platelet senescence.

There is a growing interest for the possibility of using peripheral blood cells (including platelets) as markers for mitochondrial function in less accessible tissues. Only a few studies have examined the correlation between respiration in blood and muscle tissue, with small sample sizes and conflicting results.This study investigated the correlation of mitochondrial respiration within and across tissues. Additional analyses were performed to elucidate which blood cell type would be most useful for assessing systemic mitochondrial function.There was a significant but weak within tissue correlation between platelets and peripheral blood mononuclear cells (PBMCs). Neither PBMCs nor platelet respiration correlated significantly with muscle respiration.Muscle fibers from a group of athletes had higher mass-specific respiration, due to higher mitochondrial content than non-athlete controls, but this finding was not replicated in either of the blood cell types. In a group of patients with primary mitochondrial diseases, there were significant differences in blood cell respiration compared to healthy controls, particularly in platelets. Platelet respiration generally correlated better with the citrate synthase activity of each sample, in comparison to PBMCs.In conclusion, this study does not support the theory that blood cells can be used as accurate biomarkers to detect minor alterations in muscle respiration. However, in some instances, pronounced mitochondrial abnormalities might be reflected across tissues and detectable in blood cells, with more promising findings for platelets than PBMCs.

Neurological and cardiac injuries are significant contributors to morbidity and mortality following pediatric in-hospital cardiac arrest (IHCA). Preservation of mitochondrial function may be critical for reducing these injuries. Dimethyl fumarate (DMF) has shown potential to enhance mitochondrial content and reduce oxidative damage. To investigate the efficacy of DMF in mitigating mitochondrial injury in a pediatric porcine model of IHCA, toddler-aged piglets were subjected to asphyxia-induced CA, followed by ventricular fibrillation, high-quality cardiopulmonary resuscitation, and random assignment to receive either DMF (30 mg/kg) or placebo for four days. Sham animals underwent similar anesthesia protocols without CA. After four days, tissues were analyzed for mitochondrial markers. In the brain, untreated CA animals exhibited a reduced expression of proteins of the oxidative phosphorylation system (CI, CIV, CV) and decreased mitochondrial respiration (p < 0.001). Despite alterations in mitochondrial content and morphology in the myocardium, as assessed per transmission electron microscopy, mitochondrial function was unchanged. DMF treatment counteracted 25% of the proteomic changes induced by CA in the brain, and preserved mitochondrial structure in the myocardium. DMF demonstrates a potential therapeutic benefit in preserving mitochondrial integrity following asphyxia-induced IHCA. Further investigation is warranted to fully elucidate DMF's protective mechanisms and optimize its therapeutic application in post-arrest care.

IntroductionHead and neck squamous cell carcinoma (HNSCC) constitutes a heterogeneous group of cancers. Human papilloma virus (HPV) is associated with a subtype of HNSCC with a better response to treatment and more favorable prognosis. Mitochondrial function and metabolism vary depending on cancer type and can be related to tumor aggressiveness. This study aims to characterize the metabolism of HPV-positive and HPV-negative HNSCC cell lines.MethodsOxidative phosphorylation (OXPHOS) and glycolysis were assessed in intact cells, in four HNSCC cell lines using Seahorse XF Analyzer. OXPHOS was further studied in permeabilized cells using high-resolution respirometry in an Oroboros O2K. Metabolomic analysis was performed using mass spectroscopy.ResultsThe HPV-negative cell lines were found to display a higher OXPHOS capacity and were also able to upregulate glycolysis when needed. The HPV-positive cell line had a higher basal glycolytic rate but lower spare OXPHOS capacity. These cells were also unable to increase respiration in response to succinate, unlike the HPV-negative cells. In the metabolomic analysis, the HPV-positive cells showed a higher kynurenine/tryptophan ratio.DiscussionHPV-positive HNSCC preferred glycolysis to compensate for lower OXPHOS reserves, while the HPV-negative HNSCC displayed a more versatile metabolism, which might be related to increased tumor aggressiveness. The higher kynurenine/tryptophan ratio of HPV-positive HNSCC might be related to increased indoleamine 2,3-dioxygenase activity due to the carcinoma’s viral origin. This study highlights important metabolic differences between HPV-positive and HPV-negative cancers and suggests that future metabolic targets for cancer treatment should be individualized based on specific tumor metabolism.

Introduction Carbon monoxide (CO) is a colorless and odorless gas that is a leading cause of environmental poisoning in the USA with substantial mortality and morbidity. The mechanism of CO poisoning is complex and includes hypoxia, inflammation, and leukocyte sequestration in brain microvessel segments leading to increased reactive oxygen species. Another important pathway is the effects of CO on the mitochondria, specifically at cytochrome c oxidase, also known as Complex IV (CIV). One of the glaring gaps is the lack of rigorous experimental models that may recapitulate survivors of acute CO poisoning in the early phase. The primary objective of this preliminary study is to use our advanced swine platform of acute CO poisoning to develop a clinically relevant survivor model to perform behavioral assessment and MRI imaging that will allow future development of biomarkers and therapeutics. Methods Four swine (10 kg) were divided into two groups: control ( n = 2) and CO ( n = 2). The CO group received CO at 2000 ppm for over 120 min followed by 30 min of re-oxygenation at room air for one swine and 150 min followed by 30 min of re-oxygenation for another swine. The two swine in the sham group received room air for 150 min. Cerebral microdialysis was performed to obtain semi real-time measurements of cerebral metabolic status. Following exposures, all surviving animals were observed for a 24-h period with neurobehavioral assessment and imaging. At the end of the 24-h period, fresh brain tissue (cortical and hippocampal) was immediately harvested to measure mitochondrial respiration. Results While a preliminary ongoing study, animals in the CO group showed alterations in cerebral metabolism and cellular function in the acute exposure phase with possible sustained mitochondrial changes 24 h after the CO exposure ended. Conclusions This preliminary research further establishes a large animal swine model investigating survivors of CO poisoning to measure translational metrics relevant to clinical medicine that includes a basic neurobehavioral assessment and post exposure cellular measures.

Introduction Organophosphates (OPs) are a major public health problem worldwide due to ease of access and high toxicity lacking effective biomarkers and treatment. Cholinergic agents such as OPs and carbamates are responsible for many pesticide-related deaths. While the inhibition of AChE is thought to be the main mechanism of injury, there are other important pathways that contribute to the overall toxicity of OPs such as mitochondrial dysfunction. An existing gap in OP poisoning are biomarkers to gauge severity and prognosis. Cell-free DNA (cfDNA) are novel biomarkers that have gained increased attention as a sensitive biomarker of disease with novel use in acute poisoning. This study investigates alterations in cerebral mitochondrial function in a rodent model of chlorpyrifos poisoning with the use of cfDNA as a potential biomarker. Methods Twenty rodents were divided into two groups: Control ( n = 10) and Chlorpyrifos ( n = 10). Chlorpyrifos was administered through the venous femoral line with a Harvard Apparatus 11 Elite Syringe pump (Holliston, MA, USA) at 2 mg/kg. Animals were randomized to receive chlorpyrifos versus the vehicle (10% DMSO) for 60 min which would realistically present an acute exposure with continued absorption. At the end of the exposure (60 min), isolated mitochondria were measured for mitochondrial respiration along with measures of acetylcholinesterase activity, cfDNA, cytokines and western blot. Results The Chlorpyrifos group showed a significant decrease in heart rate but no change in the blood pressure. There was a significant increase in bulk cfDNA concentrations and overall decrease in mitochondrial respiration from brain tissue obtained from animals in the Chlorpyrifos group when compared to the Control group with no difference in acetylcholinesterase activity. In addition, there was a significant increase in both IL-2 and IL-12 in the Chlorpyrifos group. Conclusions In our study, we found that the total cfDNA concentration may serve as a more accurate biomarker of OP exposure compared to acetylcholinesterase activity. In addition, there was an overall decrease in cerebral mitochondrial function in the Chlorpyrifos group when compared to the Control group.

IntroductionCyanide exposure can occur in various settings such as industry and metallurgy. The primary mechanism of injury is cellular hypoxia from Complex IV (CIV) inhibition. This leads to decreased ATP production and increased reactive oxygen species production. The brain and the heart are the organs most affected due to their high metabolic demand. While the cardiac effects of cyanide are well known, the cerebral effects on cellular function are less well described. We investigated cerebral metabolism with a combination of brain respirometry, microdialysis, and western blotting using a rodent model of sub-lethal cyanide poisoning.MethodsTwenty rodents were divided into two groups: control (n = 10) and sub-lethal cyanide (n = 10). Cerebral microdialysis was performed during a 2 mg/kg/h cyanide exposure to obtain real-time measurements of cerebral metabolic status. At the end of the exposure (90 min), brain-isolated mitochondria were measured for mitochondrial respiration. Brain tissue ATP concentrations, acyl-Coenzyme A thioesters, and mitochondrial content were also measured.ResultsThe cyanide group showed significantly increased lactate and decreased hypotension with decreased cerebral CIV-linked mitochondrial respiration. There was also a significant decrease in cerebral ATP concentration in the cyanide group and a significantly higher cerebral lactate-to-pyruvate ratio (LPR). In addition, we also found decreased expression of Complex III and IV protein expression in brain tissue from the cyanide group. Finally, there was no change in acyl-coenzyme A thioesters between the two groups.ConclusionsThe key finding demonstrates mitochondrial dysfunction in brain tissue that corresponds with a decrease in mitochondrial function, ATP concentrations, and an elevated LPR indicating brain dysfunction at a sub-lethal dose of cyanide.