Brain Protection after Anoxic Brain Injury: Is Lactate Supplementation Helpful?

While sudden loss of perfusion is responsible for ischemia, failure to supply the required amount of oxygen to the tissues is defined as hypoxia. Among several pathological conditions that can impair brain perfusion and oxygenation, cardiocirculatory arrest is characterized by a complete loss of perfusion to the brain, determining a whole brain ischemic-anoxic injury. Differently from other threatening situations of reduced cerebral perfusion, i.e., caused by increased intracranial pressure or circulatory shock, resuscitated patients after a cardiac arrest experience a sudden restoration of cerebral blood flow and are exposed to a massive reperfusion injury, which could significantly alter cellular metabolism. Current evidence suggests that cell populations in the central nervous system might use alternative metabolic pathways to glucose and that neurons may rely on a lactate-centered metabolism. Indeed, lactate does not require adenosine triphosphate (ATP) to be oxidated and it could therefore serve as an alternative substrate in condition of depleted energy reserves, i.e., reperfusion injury, even in presence of adequate tissue oxygen delivery. Lactate enriched solutions were studied in recent years in healthy subjects, acute heart failure, and severe traumatic brain injured patients, showing possible benefits that extend beyond the role as alternative energetic substrates. In this manuscript, we addressed some key aspects of the cellular metabolic derangements occurring after cerebral ischemia-reperfusion injury and examined the possible rationale for the administration of lactate enriched solutions in resuscitated patients after cardiac arrest.

Magnetic resonance spectroscopy of anoxic brain injury after cardiac arrest

Objective: We describe magnetic resonance spectroscopy (MRS) changes in comatose patients undergoing targeted temperature management (TTM) after cardiac arrest, and their relationships to relevant clinical, MRI, and EEG variables. Methods A prospective cohort of 50 patients was studied. The primary outcome was coma recovery to follow commands. Comparison of MRS measures in the posterior cingulate gyrus, parietal white matter, basal ganglia, and brainstem were also made to 25 normative control subjects. Results: Fourteen of 50 achieved coma recovery. Compared to patients who recovered, there was a significant decrease in total N-acetyl-aspartate (NAA/Cr) and glutamate; and an increase in lactate (Lac/Cr) and glutamine in patients who did not recover, with changes most prominent in the posterior cingulate gyrus. Patients who recovered had a decrease in NAA/Cr as compared to control subjects. Coma recovery was seen in patients with a moderate decrease in NAA/Cr, but the appearance of lactate resulted in a poor outcome. NAA/Cr had a linear relationship with MRI cortical apparent diffusion coefficient (ADC); lactate level exponentially increased with decreasing ADC. EEG suppression/burst suppression was universally associated with lactate elevation. Conclusions NAA and lactate changes are associated with clinical/MRI/EEG changes consistent with anoxic brain injury and are most prominent in the posterior cingulate gyrus. NAA/Cr decrease observed in patients with good outcomes suggests mild anoxic injury in patients asymptomatic at hospital discharge. The appearance of cortical lactate represents a deterioration of aerobic energy metabolism and is associated with EEG background suppression, synaptic transmission failure, and severe, potentially irreversible anoxic injury.

Takotsubo cardiomyopathy in children

Objective:To explore the epidemiology and outcomes of takotsubo cardiomyopathy in children.Methods:A retrospective analysis of the Healthcare Cost and Utilization 2012 and 2016 Kids’ Inpatient Database was performed. Patients admitted with the diagnosis of takotsubo cardiomyopathy in the age group of 1 month–20 years were identified using International Classification of Diseases (ICD)-9 code 429.83 and ICD-10 code I51.81.Results:Among a total of 4,860,859 discharges, there were 153 with the diagnosis of takotsubo cardiomyopathy (3.1 per 100,000 discharges). Among patients with takotsubo cardiomyopathy, 55.0% were male, 62.4% were white, and 16.7% were black. Eighty-nine percent of patients were between 12 and 20 years. Psychiatric diagnosis was documented in 46% and substance use disorder in 36.2%. Sepsis was documented in 22.8% of patients. The median length of stay was 5 days (interquartile range: 2.7–15), and median total charges were $75,080 (interquartile range: 32,176–198,336). The overall mortality for takotsubo cardiomyopathy was 7%. On multivariable regression analysis, mortality was higher in the presence of anoxic injury (odds ratio = 34.42, 95% confidence interval: 4.85–320.11, p = 0.00).Conclusions:Takotsubo cardiomyopathy is uncommon in children and carries a mortality rate of 7%. Most children with takotsubo cardiomyopathy are adolescent males, many of whom have psychiatric disorder or substance use disorder or both. Takotsubo cardiomyopathy should be considered in the differential diagnosis for patients who present with cardiac dysfunction and have underlying psychiatric disorders or drug abuse.

MRI–EEG correlation for outcome prediction in postanoxic myoclonus

ObjectiveTo examine the prognostic ability of the combination of EEG and MRI in identifying patients with good outcome in postanoxic myoclonus (PAM) after cardiac arrest (CA).MethodsAdults with PAM who had an MRI within 20 days after CA were identified in 4 prospective CA registries. The primary outcome measure was coma recovery to command following by hospital discharge. Clinical examination included brainstem reflexes and motor activity. EEG was assessed for best background continuity, reactivity, presence of epileptiform activity, and burst suppression with identical bursts (BSIB). MRI was examined for presence of diffusion restriction or fluid-attenuated inversion recovery changes consistent with anoxic brain injury. A prediction model was developed using optimal combination of variables.ResultsAmong 78 patients, 11 (14.1%) recovered at discharge and 6 (7.7%) had good outcome (Cerebral Performance Category < 3) at 3 months. Patients who followed commands were more likely to have pupillary and corneal reflexes, flexion or better motor response, EEG continuity and reactivity, no BSIB, and no anoxic injury on MRI. The combined EEG/MRI variable of continuous background and no anoxic changes on MRI was associated with coma recovery at hospital discharge with sensitivity 91% (95% confidence interval [CI], 0.59–1.00), specificity 99% (95% CI, 0.92–1.00), positive predictive value 91% (95% CI, 0.59–1.00), and negative predictive value 99% (95% CI, 0.92–1.00).ConclusionsEEG and MRI are complementary and identify both good and poor outcome in patients with PAM with high accuracy. An MRI should be considered in patients with myoclonus showing continuous or reactive EEGs.

High Quality Targeted Temperature Management (TTM) After Cardiac Arrest

Targeted temperature management (TTM) is a complex intervention used with the aim of minimizing post-anoxic injury and improving neurological outcome after cardiac arrest. There is large variability in the devices used to achieve cooling and in protocols (e.g., for induction, target temperature, maintenance, rewarming, sedation, management of post-TTM fever). This variability can explain the limited benefits of TTM that have sometimes been reported. We therefore propose the concept of “high-quality TTM” as a way to increase the effectiveness of TTM and standardize its use in future interventional studies.

P023 Identification of regulated mechanistic pathways and genes to protect intestinal barrier injury by larazotide acetate in an IBD microenvironment

Background Inflammatory bowel disease (IBD) is due to a combination of factors, including genetics, mucosal barrier dysfunction and dysregulated immune responses. Recently, it has been appreciated that IBD is associated with profound tissue anoxia. Tight junctions (TJs) located at the apical lateral region of adjacent intestinal epithelial cells are largely responsible for regulating the intestinal mucosal barrier. Larazotide acetate (LA, Innovate Biopharmaceuticals, Inc., Raleigh, NC) is a synthetic, eight amino acid peptide that is known to act as a TJ regulator capable of closing ‘leaky’ interepithelial junctions. Presently, LA is being studied in Phase 3 clinical trials for the treatment of celiac disease. Based on prior work in our lab, we hypothesised that LA would protect the TJ barrier in an anoxic injury IBD model associated with upregulation of TJ-associated signalling pathways. Methods C2BBe1 (Caco-2 brush border expressing) monolayers were treated apically with LA and were subjected to anoxia for 2 h followed by reoxygenation with 21% O2. Barrier function was assessed by measuring transepithelial electrical resistance (TEER) during anoxic injury and recovery. TJ proteins and cytoskeleton protein F-actin were assessed by western blotting and immunofluorescence microscopy. Then, next-generation RNA sequencing was employed to assess cellular regulatory pathways. Results Pre-treatment of anoxic injured C2BBe1cells with 10 mM LA significantly increased TEER as compared with untreated anoxic injured cells. The TJ protein occludin and ZO-1 were disrupted in anoxia-injured monolayer. Alternatively, treatment with 10 mM LA prevented disruption of TJ proteins during anoxic injury. Gene ontology annotation revealed a number of critical signalling pathways that were differentially expressed in cells treated with LA, including biological processes involved in establishment of cell polarity, molecular functions that regulate junctional structures, and cellular components associated with epithelial repair (cell leading edge, ruffle and apical junctional complex). Furthermore, Ras/Rho GTPase binding and protein serine/threonine kinase activity were differentially expressed in cells treated with LA. Additionally, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed enrichment of target genes for ‘cell cycle,’ ‘adherens junction’ and ‘Wnt signalling pathways’. Conclusion The results of the present study provide novel insights into the molecular mechanism of action of LA on the protection of TJ integrity in anoxic injury, an IBD microenvironment and the potential for a more broad use in important digestive diseases such as IBD.

Solution structure of human myeloid-derived growth factor suggests a conserved function in the endoplasmic reticulum

Human myeloid-derived growth factor (hMYDGF) is a 142-residue protein with a C-terminal endoplasmic reticulum (ER) retention sequence (ERS). Extracellular MYDGF mediates cardiac repair in mice after anoxic injury. Although homologs of hMYDGF are found in eukaryotes as distant as protozoans, its structure and function are unknown. Here we present the NMR solution structure of hMYDGF, which consists of a short α-helix and ten β-strands distributed in three β-sheets. Conserved residues map to the unstructured ERS, loops on the face opposite the ERS, and the surface of a cavity underneath the conserved loops. The only protein or portion of a protein known to have a similar fold is the base domain of VNN1. We suggest, in analogy to the tethering of the VNN1 nitrilase domain to the plasma membrane via its base domain, that MYDGF complexed to the KDEL receptor binds cargo via its conserved residues for transport to the ER.

Abstract 10: Early Neuroprognostication After Refractory VF/VT Cardiac Arrest Requiring ECPR

Background: Extracorporeal cardiopulmonary resuscitation (ECPR) can improve survival for refractory ventricular fibrillation (VF) cardiac arrest. Early prognostication will be critical to focus this resource-intensive care to patients likely to benefit. Objectives: The aim of this study is to examine the efficacy of current neuroprognostication tools early in the setting of ECPR for refractory VF. Methods: Consecutive patients transported for the University of Minnesota ECPR program and surviving to hospital admission between December 2015 and May 2019 were assessed. All patients received neurologic assessment with head CT, continuous EEG, cerebral near-infrared spectroscopy (NIRS), biomarkers including S100B and neuron specific enolase (NSE), and neurologic exam. All patients were considered viable unless they developed refractory shock, devastating brain injury, or family requested cessation of efforts. For this analysis, patients were divided into two groups: 1) neurologically favorable survival (CPC 1-2) and 2) those who died or had CPC 3-4. Data from the first 24 hours of hospital admission were used. Results: Of 168 patients, 130 patients survived to hospital admission. Of these, 42% (54/130) survived neurologically favorable. Abnormalities on admission head CT were predictive of poor outcomes; cerebral edema was 100% specific and 30% sensitive for poor outcomes while anoxic injury provided 98% specificity and 39% sensitivity. Admission NSE levels greater than three times the upper limit of normal were predictive with 98% specificity and 26% sensitivity for poor outcome. Admission S100B was highly variable failing to discriminate patient outcome. Absence of brainstem reflexes at 24 hours had 100% specificity and 32% sensitivity. An isoelectric EEG at 24 hours had 100% specificity and 20% sensitivity. NIRS did not predict poor outcomes. When combined, ≥ 1 of the following: anoxic injury on CT, edema on CT, NSE, absence of brainstem reflexes, isoelectric EEG have a specificity of 96% and sensitivity of 67% for poor outcome. Conclusions: Neuroprognostication after 24 hours of hospital admission may be possible in the refractory VF population requiring ECPR. High specificity is possible but sensitivity is limited. Further study is needed.

Neuroprotective effects of crocin I and II in an ischemia-reperfusion injury model

BackgroundCrocin I and II are derived from the medicinal plant Crocus sativus L. (Saffron), and their neuroprotective effects have been attracting more and more attention. However, their protective effect against cerebral apoplexy induced by hypoxia has not been reported. In this study, we aimed to clarify the roles of crocin I and II in protecting against ischemic injury.Materials/MethodsWe generated a rat cerebral ischemia-reperfusion injury model using a reversible cerebral artery occlusion suture method and found changes in amino acid neurotransmitters in the frontal cortex after drug administration. We also identified changes in mRNA expression of Bcl2, Bax, Casp3, P38, and NFkb1 in the frontal cortex and changes in antioxidant indices in the brain.ResultsCrocin I and II both had protective effects on ischemic/anoxic injury in vivo by downregulating the expression of Casp3 and Nfkb1 mRNA and the steady-state levels of excitatory amino acids/inhibitory amino acids during ischemia and reperfusion and by improving the total antioxidant capacity and total superoxide dismutase activities during ischemia. We also found that crocin I and II had synergistic effects when used together.ConclusionsThese findings displayed that crocin I and II could protect animal model against ischemic and anoxic injury and provided new evidence for both molecules’ potential medicinal value.