Effect of dimethyl fumarate on mitochondrial metabolism in a pediatric porcine model of asphyxia-induced in-hospital cardiac arrest.

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.

A Template for Translational Bioinformatics: Facilitating Multimodal Data Analyses in Preclinical Models of Neurological Injury.

Background: Pediatric neurological injury and disease is a critical public health issue due to increasing rates of survival from primary injuries (e.g., cardiac arrest, traumatic brain injury) and a lack of monitoring technologies and therapeutics for the treatment of secondary neurological injury. Translational, preclinical research facilitates the development of solutions to address this growing issue but is hindered by a lack of available data frameworks and standards for the management, processing, and analysis of multimodal data sets. Methods: Here, we present a generalizable data framework that was implemented for large animal research at the Children's Hospital of Philadelphia to address this technological gap. The presented framework culminates in an interactive dashboard for exploratory analysis and filtered data set download. Results: Compared with existing clinical and preclinical data management solutions, the presented framework accommodates heterogeneous data types (single measure, repeated measures, time series, and imaging), integrates data sets across various experimental models, and facilitates dynamic visualization of integrated data sets. We present a use case of this framework for predictive model development for intra-arrest prediction of cardiopulmonary resuscitation outcome. Conclusions: The described preclinical data framework may serve as a template to aid in data management efforts in other translational research labs that generate heterogeneous data sets and require a dynamic platform that can easily evolve alongside their research.

Pediatric Extracorporeal Cardiopulmonary Resuscitation: Development of a Porcine Model and the Influence of Cardiopulmonary Resuscitation Duration on Brain Injury.

Background The primary objective was to develop a porcine model of prolonged (30 or 60 minutes) pediatric cardiopulmonary resuscitation (CPR) followed by 22- to 24-hour survival with extracorporeal life support, and secondarily to evaluate differences in neurologic injury. Methods and Results Ten-kilogram, 4-week-old female piglets were used. First, model development established the technique (n=8). Then, a pilot study was conducted (n=15). After 80% survival was achieved in the final 5 pilot animals, a proof-of-concept randomized study was completed (n=11). Shams (n=6) underwent anesthesia only. Severe neurological injury was determined by a composite score of mitochondrial function, neuropathology, and cerebral metabolism: scale of 0-6 (severe: >3). Among 15 piglets in the pilot study, overall survival was 10 (67%); of the final 5, overall survival was 4 (80%). Eleven piglets were then randomized to 60 (CPR60, n=5) or 30 minutes of CPR (CPR30, n=5); 1 animal was excluded from prerandomization for intra-abdominal hemorrhage (10/11, 91% survival). Three of 5 animals in the CPR60 group had severe neurological injury scores versus 1 of 5 in the CPR30 group (P=0.52). During ECMO, CPR60 animals had lower pH (CPR60: 7.4 [IQR 7.4-7.4] versus CPR30: 7.5 [IQR 7.4-7.5], P=0.022), higher lactate (CPR60: 6.8 [IQR 6.8-11] versus CPR30: 4.2 [IQR 4.1-4.3] mmol/L; P=0.012), and higher ICP (CPR60: 19.3 [IQR 11.7-29.3] versus CPR30: 7.9 [IQR 6.7-9.3] mm Hg; P=0.037). Both groups had greater mitochondrial injury than shams (CPR60: P<0.001; CPR30: P<0.001). CPR60 did not differ from CPR30 in mitochondrial respiration, neuropathology, or cerebral metabolism. Conclusions A pediatric porcine model of extracorporeal cardiopulmonary resuscitation after 60 and 30 minutes of CPR consistently resulted in 24-hour survival with more severe lactic acidosis in the 60-minute cohort.

Intracranial Pressure and Cerebral Hemodynamic Monitoring After Cardiac Arrest in Pediatric Pigs Using Contrast Ultrasound-Derived Parameters.

OBJECTIVES: We explore the correlation of contrast-enhanced ultrasound (CEUS) parameters to intracranial pressure (ICP) in a porcine experimental model of pediatric cardiac arrest. METHODS: Eleven pediatric pigs underwent electrically induced cardiac arrest followed by cardiopulmonary resuscitation. ICP was measured using intracranial bolt monitor and CEUS was monitored through a cranial window. Various CEUS parameters were monitored at baseline, immediately post return of spontaneous circulation (ROSC), 1 hour-post ROSC, and 3 hours post-ROSC. RESULTS: There was significant ICP correlation with wash-out slope assessed by CEUS time intensity curve analysis at immediate post-ROSC. At 3 hours post-ROSC there was also significant negative correlation between ICP and peak enhancement which may be due to the evolution of anoxic injury. CONCLUSION: The use of CEUS in assessing disruption of cerebral hemodynamics and ICP post cardiac arrest will need future validation and comparison to other imaging modalities. The correlation between CEUS parameters and ICP may be due to the alterations in cerebral autoregulation that result from anoxic brain injury.

A versatile system for neuromuscular stimulation and recording in the mouse model using a lightweight magnetically coupled headmount.

Neural stimulation and recording in rodents are common methods to better understand the nervous system and improve the quality of life of individuals who are suffering from neurological disorders (e.g., epilepsy), as well as for permanent reduction of chronic pain in patients with neuropathic pain and spinal-cord injury. This method requires a neural interface (e.g., a headmount) to couple the implanted neural device with instrumentation system. The size and the total weight of such headmounts should be designed in a way to minimize its effect on the movement of the animal. This is a crucial factor in gait, kinematic, and behavioral neuroscience studies of freely moving mice. Here we introduce a lightweight 'snap-in' electro-magnetic headmount that is extremely small, and uses strong neodymium magnetics to enable a reliable connection without sacrificing the lightweight of the device. Additionally, the headmount requires minimal surgical intervention during the implantation, resulting in minimal tissue damage. The device has demonstrated itself to be robust, and successfully provided direct electrical stimulation of nerve and electrical muscle stimulation and recording, as well as powering implanted LEDs for optogenetic use scenarios.

Alterations in cerebral and cardiac mitochondrial function in a porcine model of acute carbon monoxide poisoning.

OBJECTIVES: The purpose of this study is the development of a porcine model of carbon monoxide (CO) poisoning to investigate alterations in brain and heart mitochondrial function. DESIGN: Two group large animal model of CO poisoning. SETTING: Laboratory. SUBJECTS: Ten swine were divided into two groups: Control (n = 4) and CO (n = 6). INTERVENTIONS: Administration of a low dose of CO at 200 ppm to the CO group over 90 min followed by 30 min of re-oxygenation at room air. The Control group received room air for 120 min. MEASUREMENTS: Non-invasive optical monitoring was used to measure cerebral blood flow and oxygenation. Cerebral microdialysis was performed to obtain semi real time measurements of cerebral metabolic status. At the end of the exposure, both fresh brain (cortical and hippocampal tissue) and heart (apical tissue) were immediately harvested to measure mitochondrial respiration and reactive oxygen species (ROS) generation and blood was collected to assess plasma cytokine concentrations. MAIN RESULTS: Animals in the CO group showed significantly decreased Complex IV-linked mitochondrial respiration in hippocampal and apical heart tissue but not cortical tissue. There also was a significant increase in mitochondrial ROS generation across all measured tissue types. The CO group showed a significantly higher cerebral lactate-to-pyruvate ratio. Both IL-8 and TNFα were significantly increased in the CO group compared with the Control group obtained from plasma. While not significant there was a trend to an increase in optically measured cerebral blood flow and hemoglobin concentration in the CO group. CONCLUSIONS: Low-dose CO poisoning is associated with early mitochondrial disruption prior to an observable phenotype highlighting the important role of mitochondrial function in the pathology of CO poisoning. This may represent an important intervenable pathway for therapy and intervention.

Increased cerebral mitochondrial dysfunction and reactive oxygen species with cardiopulmonary bypass.

OBJECTIVES: Neurodevelopmental injury after cardiac surgery using cardiopulmonary bypass (CPB) for congenital heart defects is common, but the mechanism behind this injury is unclear. This study examines the impact of CPB on cerebral mitochondrial reactive oxygen species (ROS) generation and mitochondrial bioenergetics. METHODS: Twenty-three piglets (mean weight 4.2 ± 0.5 kg) were placed on CPB for either 1, 2, 3 or 4 h (n = 5 per group) or underwent anaesthesia without CPB (sham, n = 3). Microdialysis was used to measure metabolic markers of ischaemia. At the conclusion of CPB or 4 h of sham, brain tissue was harvested. Utilizing high-resolution respirometry, with simultaneous fluorometric analysis, mitochondrial respiration and ROS were measured. RESULTS: There were no significant differences in markers of ischaemia between sham and experimental groups. Sham animals had significantly higher mitochondrial respiration than experimental animals, including maximal oxidative phosphorylation capacity of complex I (OXPHOSCI) (3.25 ± 0.18 vs 4-h CPB: 1.68 ± 0.10, P < 0.001) and maximal phosphorylating respiration capacity via convergent input through complexes I and II (OXPHOSCI+CII) (7.40 ± 0.24 vs 4-h CPB: 3.91 ± 0.20, P < 0.0001). At 4-h, experimental animals had significantly higher ROS related to non-phosphorylating respiration through complexes I and II (ETSCI+CII) than shams (1.08 ± 0.13 vs 0.64 ± 0.04, P = 0.026). CONCLUSIONS: Even in the absence of local markers of ischaemia, CPB is associated with decreased mitochondrial respiration relative to shams irrespective of duration. Exposure to 4 h of CPB resulted in a significant increase in cerebral mitochondrial ROS formation compared to shorter durations. Further study is needed to improve the understanding of cerebral mitochondrial health and its effects on the pathophysiology of neurological injury following exposure to CPB.

Brain Contrast-Enhanced Ultrasound Evaluation of a Pediatric Swine Model.

ABSTRACT: Brain injury remains a leading cause of morbidity and mortality in children. We evaluated the feasibility of using a pediatric swine model to develop contrast-enhanced ultrasound (CEUS)-based measures of brain perfusion for clinical application in various types of brain injury monitoring. Six-week-old, 10-kg swine (N = 10) were anesthetized, and an acoustic window was created in the right frontal cranium to provide visualization of an oblique coronal plane and bilateral thalami. Ultrasound contrast agent was administered via a femoral venous catheter as a weight-based (0.03 mL/kg) bolus. After localization of the imaging plane, CEUS cine clips were acquired for 90 seconds. Bolus injection of contrast agent provided global visualization of cerebral perfusion and highlighted microvasculature in the brain. Preliminary evaluation of bolus kinetics in piglets showed a central gray nuclei-to-cortex ratio similar to human infants with a steep wash-in that crossed and remained above the 1.0 threshold for most of the enhancement period. We demonstrated the similarity in brain perfusion between piglets and human infants, specifically central gray nuclei-to-cortex ratio, showing preliminary feasibility of its use as a pediatric model of brain perfusion. Contrast-enhanced ultrasound can be performed at the bedside as a minimally invasive procedure, and quantitative CEUS may provide critical information regarding changes in brain perfusion as a result of injury or as a response to therapy.

Matlab software for impedance spectroscopy designed for neuroscience applications.

BACKGROUND: Metal electrodes are a mainstay of neuroscience. Characterization of the electrical impedance properties of these cuffs is important to ensure successful and repeatable fabrication, achieve a target impedance, revise novel designs, and quantify the success or failure of implantation and any potential subsequent damage or encapsulation by scar tissue. NEW METHODS: Impedances are frequently characterized using lumped-parameter circuit models of the electrode-electrolyte interface. Open-source tools to gather and analyze these frequency sweep data are lacking. Here, we present such software, in the form of Matlab code, which includes a GUI. It automatically acquires frequency sweep data and subsequently fits a simplified Randles model to these data, over a user specified frequency range, providing the user with the model parameter estimates. Also, it can measure an unknown impedance of an element over a range of frequencies, as long as an external resistor can be added for the measurements. RESULTS: The tool was tested on five bright platinum nerve cuffs in vitro. The average charge transfer resistance, solution resistance, CPE value, and impedance magnitude were estimated. COMPARISON TO EXISTING METHODS: The measured values of the impedance of cuffs were in agreement with the literature (Wei and Grill, 2009). Variation between cuffs fabricated as consistently as possible amounted to 10% for impedance magnitude and 4° for impedance phase. CONCLUSION: The results show that this low-cost tool can be used to characterize a cuff across different conditions including after implantation. The latter makes it useful for a longer-term study of electrode viability.