Richard Jonathan Levy

All Publications

• Ancient Mitochondrial Genetic Variant, Modern-day Pandora's Box ANESTHESIOLOGY Levy, R. J., Morgan, P. G. 2026; 144 (6): 1269-1271

  View details for DOI 10.1097/ALN.0000000000006030

  View details for Web of Science ID 001763887800029

  View details for PubMedID 41996624

• Targetable Effects of the Anesthetic, Ubiquinone-5, on Murine Cardiac Rhythm FASEB JOURNAL Lim, H., Lu, R., Shi, C., Levy, R. J. 2026; 40 (4): e71598

  Abstract

  General anesthetics can adversely affect the heart, negatively impacting chronotropy, electrical conduction, and myocardial contractility. The intravenous sedative-hypnotic, propofol, for example, impairs ventricular contraction at clinically relevant doses and can cause dysrhythmias and atrioventricular block with acute administration. In addition, high cumulative propofol doses can induce bradyarrhythmias, cardiac conduction abnormalities, and myocardial failure. As with propofol, the recently identified intravenous anesthetic agent, ubiquinone-5 (Ub5), causes bradycardia and complete heart block at supratherapeutic doses. However, the cardiac effects of clinically relevant Ub5 doses are unknown. Thus, we aimed to determine how therapeutic doses of Ub5 impact cardiac rhythm, hypothesizing that Ub5 would interfere with dromotropy. We tested our hypothesis in vivo in the young adult mouse and ex vivo in the isolated-perfused murine heart. We then determined mechanistic contributors of Ub5-induced cardiotoxicity in isolated cardiomyocyte mitochondria. We found that Ub5 caused type 1 s-degree heart block and compromised the mitochondrial membrane potential in isolated cardiomyocyte mitochondria by inhibiting electron transport and inducing excessive proton leak. Pharmacological inhibition of the aspartate-glutamate carrier, Aralar, rescued Ub5-mediated disturbances in cardiac rhythm in the isolated-perfused heart. The findings suggest that Ub5 can impact cardiac conduction in a targetable manner, carrying importance for future drug development efforts.

  View details for DOI 10.1096/fj.202504065RR

  View details for Web of Science ID 001692326700001

  View details for PubMedID 41693609

  View details for PubMedCentralID PMC12908110

• Inclusion of Retracted Studies in a Systematic Review and Meta-Analysis of Prophylactic Dexmedetomidine and Postoperative Junctional Ectopic Tachycardia in Pediatric Cardiac Surgery Patients PEDIATRIC ANESTHESIA Feinstein, M. M., Levy, R. J., Ing, C. 2026; 36 (4): 458-460

  View details for DOI 10.1002/pan.70125

  View details for Web of Science ID 001655367200001

  View details for PubMedID 41498260

  View details for PubMedCentralID PMC12877520

• Effects of the Quinone Analog Ubiquinone-5 on Murine Mitochondria and Hypnosis ANESTHESIOLOGY Somnay, Y. R., Wang, A., Lim, H., Griffiths, K. K., Zandkarimi, F., Chen, K., Yang, G., Wasilczuk, A. Z., Kelz, M. B., Larr, D., Yang, M., Gil-Iturbe, E., Moon, A., Quick, M., Levy, R. J. 2025; 143 (3): 641-660

  Abstract

  A functional anesthetic target has long been suspected to reside within mitochondria, and disruption of bioenergetic capacity is believed to play a role in the anesthetic response. Unfortunately, the exact mechanism by which changes in mitochondrial target activity result in clinically relevant anesthetic endpoints remains unknown. Here, the authors leveraged knowledge of propofol toxicity to guide drug discovery and uncover a previously unknown pharmacologic target within mitochondria. They hypothesized that, like propofol, quinone analogs would interfere with electron transfer, cause excessive proton leak within mitochondria, and induce hypnosis. The authors tested their hypothesis using the short-chain coenzyme Q analog ubiquinone-5 (Ub5) and aimed to characterize its anesthetic phenotype in the mouse and elucidate the source of Ub5-induced mitochondrial leak.Anesthetic phenotype was assessed in vivo in the mouse using behavioral and neurophysiological approaches. The authors measured biologic activity in isolated mitochondria using polarography and spectrophotometry and identified source of proton leak using pharmacologic inhibitors, mutant mouse strains, and transport activity assays in proteoliposomes. Finally, they assessed cardiotoxic effects in the isolated-perfused mouse heart ex vivo .Coenzyme Q analogs caused uncompensated proton leak in developing cardiomyocyte mitochondria and reversible cardiotoxicity in a manner reminiscent of propofol. Tail vein injection of Ub5 induced short-lived loss of righting, electroencephalogram changes consistent with a deep state of anesthesia, and reversible decreases in neuronal calcium transients and mitochondrial membrane potential in vivo . Precipitous decline in mitochondrial membrane potential played a role in Ub5-induced unconsciousness, and the authors identified the aspartate-glutamate carrier Aralar as a functional target and source of Ub5-mediated proton leak.The data indicate that uncompensated mitochondrial proton leak is an important mechanistic contributor to the anesthetic response in addition to electron transport inhibition. These findings advance the authors' understanding of how anesthetics induce hypnosis and lay the foundation for next-generation drug discovery.

  View details for DOI 10.1097/ALN.0000000000005549

  View details for Web of Science ID 001554565300031

  View details for PubMedID 40315373

  View details for PubMedCentralID PMC12343201

• The Novel Anesthetic. Ubiquinone-5, Affects Murine Cardiac Rhythm in a Targetable Manner Lim, H., Lu, R., Shi, C., Levy, R. LIPPINCOTT WILLIAMS & WILKINS. 2025: 80

  View details for Web of Science ID 001551889100030

• Sedative-hypnotic properties and mitochondrial effects of coenzyme Q2 in mice CURRENT MOLECULAR PHARMACOLOGY Lim, H., Lu, R., Patel, S. N., Zinn, S., Garcia, P. S., Levy, R. J. 2025; 18 (1): 100-107

  View details for DOI 10.1016/j.cmp.2025.12.001

  View details for Web of Science ID 001669057600001

• Exploring the Mechanistic Role of Aralar in Mediating Murine Propofol-induced Anesthesia Lim, H., Lu, R., Griffiths, K., Levy, R. LIPPINCOTT WILLIAMS & WILKINS. 2024: 52

  View details for Web of Science ID 001349531300024

• Sulfide quinone oxidoreductase contributes to voltage sensing of the mitochondrial permeability transition pore FASEB JOURNAL Griffiths, K. K., Wang, A., Jonas, E. A., Levy, R. J. 2024; 38 (4): e23494

  Abstract

  Pathological opening of the mitochondrial permeability transition pore (mPTP) is implicated in the pathogenesis of many disease processes such as myocardial ischemia, traumatic brain injury, Alzheimer's disease, and diabetes. While we have gained insight into mPTP biology over the last several decades, the lack of translation of this knowledge into successful clinical therapies underscores the need for continued investigation and use of different approaches to identify novel regulators of the mPTP with the hope of elucidating new therapeutic targets. Although the mPTP is known to be a voltage-gated channel, the identity of its voltage sensor remains unknown. Here we found decreased gating potential of the mPTP and increased expression and activity of sulfide quinone oxidoreductase (SQOR) in newborn Fragile X syndrome (FXS) mouse heart mitochondria, a model system of coenzyme Q excess and relatively decreased mPTP open probability. We further found that pharmacological inhibition and genetic silencing of SQOR increased mPTP open probability in vitro in adult murine cardiac mitochondria and in the isolated-perfused heart, likely by interfering with voltage sensing. Thus, SQOR is proposed to contribute to voltage sensing by the mPTP and may be a component of the voltage sensing apparatus that modulates the gating potential of the mPTP.

  View details for DOI 10.1096/fj.202301280R

  View details for Web of Science ID 001166354000001

  View details for PubMedID 38376922

  View details for PubMedCentralID PMC11082757

• Multicenter Population Pharmacokinetics of Fentanyl in Neonatal Surgical Patients Using Dried Blood Spot Specimen Collection Demonstrates Maturation of Elimination Clearance. Anesthesia and analgesia Rzasa Lynn, R. S., Henthorn, T. K., Zuk, J., Hammer, G. B., Drover, D. R., Levy, R. J., Maxwell, L. G., Sadhasivam, S., Suresh, S., Galinkin, J. L. 2024; 138 (2): 447-455

  Abstract

  Fentanyl is widely used for analgesia and sedation in neonates, but pharmacokinetic (PK) analysis in this population has been limited by the relatively large sample volumes required for plasma-based assays.In this multicenter observational study of fentanyl kinetics in neonates up to 42 weeks of postmenstrual age (PMA) who received fentanyl boluses and continuous infusions, dried blood spots were used for small-volume sampling. A population PK analysis was used to describe fentanyl disposition in term and preterm neonates. Covariates for the model parameters, including body weight, PMA, birth status (preterm or term), and presence of congenital cardiac disease, were assessed in a stepwise manner.Clearance was estimated to be greater than adult clearance of fentanyl and varied with weight. Covariate selection did not yield a significant relationship for age as a continuous or dichotomous variable (term or preterm, the latter defined as birth with PMA of <37 weeks) and clearance.A supra-allometric effect on clearance was determined during covariate analyses (exponential scaling factor for body weight >0.75), as has been described in population PK models that account for maturation of intrinsic clearance (here, predominantly hepatic microsomal activity) in addition to scaling for weight, both of which impact clearance in this age group.

  View details for DOI 10.1213/ANE.0000000000006808

  View details for PubMedID 38215717

• Discovery of a New Quinone Anesthetic Leads to Identification of a Novel Pharmacological Target in Mice Levy, R., Griffiths, K., Yang, G., Kelz, M., Somnay, Y. LIPPINCOTT WILLIAMS & WILKINS. 2023: 63

  View details for Web of Science ID 001058985600020

• Clinical Studies in Anesthetic Neurotoxicity Research: An Update JOURNAL OF NEUROSURGICAL ANESTHESIOLOGY Arif, A., Chen, L., Levy, R. J., Ing, C. 2023; 35 (1): 97-103

  View details for DOI 10.1097/ANA.0000000000000886

  View details for Web of Science ID 000895262200015

  View details for PubMedID 36745170

• Modeling propofol-induced cardiotoxicity in the isolated-perfused newborn mouse heart PHYSIOLOGICAL REPORTS Barajas, M. B., Wang, A., Griffiths, K. K., Sun, L., Yang, G., Levy, R. J. 2022; 10 (15): e15402

  Abstract

  Infants and children are vulnerable to developing propofol infusion syndrome (PRIS) and young age is a risk factor. Cardiac involvement is often prominent and associated with death. However, the mechanisms of pediatric PRIS are poorly understood because of the paucity of investigation and lack of a gold standard animal model. Unfortunately, in vivo modeling of PRIS in a newborn mouse is not feasible and would be complicated by confounders. Thus, we focused on propofol-induced cardiotoxicity and aimed to develop an ex-vivo model in the isolated-perfused newborn mouse heart. We hypothesized that the model would recapitulate the key cardiac features of PRIS seen in infants and children and would corroborate prior in vitro observations. Isolated perfused newborn mouse hearts were exposed to a toxic dose of propofol or intralipid for 30-min. Surface electrocardiogram, ventricular contractile force, and oxygen extraction were measured over time. Real-time multiphoton laser imaging was utilized to quantify calcein and tetramethylrhodamine ethyl ester fluorescence. Propidium iodide uptake was assessed following drug exposure. A toxic dose of propofol rapidly induced dysrhythmias, depressed ventricular contractile function, impaired the mitochondrial membrane potential, and increased open probability of the permeability transition pore in propofol-exposed hearts without causing cell death. These features mimicked the hallmarks of pediatric PRIS and corroborated prior observations made in isolated newborn cardiomyocyte mitochondria. Thus, acute propofol-induced cardiotoxicity in the isolated-perfused developing mouse heart may serve as a relevant ex-vivo model for pediatric PRIS.

  View details for DOI 10.14814/phy2.15402

  View details for Web of Science ID 000835538100001

  View details for PubMedID 35923108

  View details for PubMedCentralID PMC9350423

• Assessment of Open Probability of the Mitochondrial Permeability Transition Pore in the Setting of Coenzyme Q Excess JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Griffiths, K. K., Wang, A., Levy, R. J. 2022

  Abstract

  The mitochondrial permeability transition pore (mPTP) is a voltage-gated, nonselective, inner mitochondrial membrane (IMM) mega-channel important in health and disease. The mPTP mediates leakage of protons across the IMM during low-conductance opening and is specifically inhibited by cyclosporine A (CsA). Coenzyme Q (CoQ) is a regulator of the mPTP, and tissue-specific differences have been found in CoQ content and open probability of the mPTP in forebrain and heart mitochondria in a newborn mouse model of fragile X syndrome (FXS, Fmr1 knockout). We developed a technique to determine the voltage threshold for mPTP opening in this mutant strain, exploiting the role of the mPTP as a proton leak channel. To do so, oxygen consumption and membrane potential (ΔΨ) were simultaneously measured in isolated mitochondria using polarography and a tetraphenylphosphonium (TPP+) ion-selective electrode during leak respiration. The threshold for mPTP opening was determined by the onset of CsA-mediated inhibition of proton leak at specific membrane potentials. Using this approach, differences in voltage gating of the mPTP were precisely defined in the context of CoQ excess. This novel technique will permit future investigation for enhancing the understanding of physiological and pathological regulation of low-conductance opening of the mPTP.

  View details for DOI 10.3791/63646

  View details for Web of Science ID 000898056900030

  View details for PubMedID 35723461

• Altered brown adipose tissue mitochondrial function in newborn fragile X syndrome mice MITOCHONDRION Somnay, Y. R., Wang, A., Griffiths, K. K., Levy, R. J. 2022; 65: 1-10

  Abstract

  Brown adipose tissue (BAT) mitochondria generate heat via uncoupled respiration due to excessive proton leak through uncoupling proteins (UCPs). We previously found hyperthermia in a newborn mouse model of fragile X syndrome and excessive leak in Fmr1 KO forebrain mitochondria caused by CoQ deficiency. The inefficient thermogenic nature of Fmr1 mutant forebrain mitochondria was reminiscent of BAT metabolic features. Thus, we aimed to characterize BAT mitochondrial function in these hyperthermic mice using a top-down approach. Although there was no change in steady-state levels of UCP1 expression between strains, BAT weighed significantly less in Fmr1 mutants compared with controls. Fmr1 KO BAT mitochondria demonstrated impaired substrate oxidation, lower mitochondrial membrane potentials and rates of respiration, and CoQ deficiency. The CoQ analog decylubiquinone normalized CoQ-dependent electron flux and unmasked excessive proton leak. Unlike mutant forebrain, where such deficiency resulted in pathological proton leak, CoQ deficiency within BAT mitochondria resulted largely in abnormal substrate oxidation. This suggests that CoQ is important in BAT for uncoupled respiration to produce heat during development. Although our data provide further evidence of a link between fragile X mental retardation protein (FMRP) and CoQ biosynthesis, the results highlight the importance of CoQ in developing tissues and suggest tissue-specific differences from CoQ deficiency. Because BAT mitochondria are primarily responsible for regulating core body temperature, the defects we describe in Fmr1 KOs could manifest as an adaptive downregulated response to hyperthermia or could result from FMRP deficiency directly.

  View details for DOI 10.1016/j.mito.2022.04.003

  View details for Web of Science ID 000797722500001

  View details for PubMedID 35500860

• Sulfide Quinone Oxidoreductase: A Novel Regulator of the Mitochondrial Permeability Transition Pore Griffiths, K. K., Levy, R. J., Somnay, Y., Wang, A. LIPPINCOTT WILLIAMS & WILKINS. 2022: 129

  View details for Web of Science ID 000840283000048

• Mitochondrial ATP synthase c-subunit leak channel triggers cell death upon loss of its F₁ subcomplex CELL DEATH AND DIFFERENTIATION Mnatsakanyan, N., Park, H., Wu, J., He, X., Llaguno, M. C., Latta, M., Miranda, P., Murtishi, B., Graham, M., Weber, J., Levy, R. J., Pavlov, E., Jonas, E. A. 2022; 29 (9): 1874-1887

  Abstract

  Mitochondrial ATP synthase is vital not only for cellular energy production but also for energy dissipation and cell death. ATP synthase c-ring was suggested to house the leak channel of mitochondrial permeability transition (mPT), which activates during excitotoxic ischemic insult. In this present study, we purified human c-ring from both eukaryotic and prokaryotic hosts to biophysically characterize its channel activity. We show that purified c-ring forms a large multi-conductance, voltage-gated ion channel that is inhibited by the addition of ATP synthase F1 subcomplex. In contrast, dissociation of F1 from FO occurs during excitotoxic neuronal death suggesting that the F1 constitutes the gate of the channel. mPT is known to dissipate the osmotic gradient across the inner membrane during cell death. We show that ATP synthase c-subunit knock down (KD) prevents the osmotic change in response to high calcium and eliminates large conductance, Ca2+ and CsA sensitive channel activity of mPT. These findings elucidate the gating mechanism of the ATP synthase c-subunit leak channel (ACLC) and suggest how ACLC opening is regulated by cell stress in a CypD-dependent manner.

  View details for DOI 10.1038/s41418-022-00972-7

  View details for Web of Science ID 000772342700001

  View details for PubMedID 35322203

  View details for PubMedCentralID PMC9433415

• Modified Technique for the Use of Neonatal Murine Hearts in the Langendorff Preparation JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Barajas, M. B., Levy, R. J. 2022

  Abstract

  The use of the ex-vivo retrograde perfused heart has long been a cornerstone of ischemia-reperfusion investigation since its development by Oskar Langendorff over a century ago. Although this technique has been applied to mice over the last 25 years, its use in this species has been limited to adult animals. Development of a successful method to consistently cannulate the neonatal murine aorta would allow for the systematic study of the isolated retrograde perfused heart during a critical period of cardiac development in a genetically modifiable and low-cost species. Modification of the Langendorff preparation enables cannulation and establishment of reperfusion in the neonatal murine heart while minimizing ischemic time. Optimization requires a two-person technique to permit successful cannulation of the newborn mouse aorta using a dissecting microscope and a modified commercially available needle. The use of this approach will reliably establish retrograde perfusion within 3 min. Because the fragility of the neonatal mouse heart and ventricular cavity size prevents direct measurement of intraventricular pressure generated using a balloon, use of a force transducer connected by a suture to the apex of the left ventricle to quantify longitudinal contractile tension is necessary. This method allows investigators to successfully establish an isolated constant-flow retrograde-perfused newborn murine heart preparation, permitting the study of developmental cardiac biology in an ex-vivo manner. Importantly, this model will be a powerful tool to investigate the physiological and pharmacological responses to ischemia-reperfusion in the neonatal heart.

  View details for DOI 10.3791/63349E

  View details for Web of Science ID 000927844600041

  View details for PubMedID 35311818

  View details for PubMedCentralID PMC12909778

• Propofol toxicity in the developing mouse heart mitochondria PEDIATRIC RESEARCH Barajas, M. B., Brunner, S. D., Wang, A., Griffiths, K. K., Levy, R. J. 2022; 92 (5): 1341-1349

  Abstract

  Propofol infusion syndrome (PRIS) is a potentially lethal consequence of long-term propofol administration. Children are vulnerable and cardiac involvement is often prominent and associated with mortality. We aimed to determine the mechanism of propofol toxicity in newborn mice, hypothesizing that propofol would induce discrete defects within immature cardiac mitochondria.Newborn murine cardiac mitochondria were exposed to propofol or intralipid in vitro. Non-exposed mitochondria served as controls. Mitochondrial respiration and membrane potential (ΔΨ) were measured and respiratory chain complex kinetics were determined.Propofol and intralipid exerted biological activity in isolated mitochondria. Although intralipid effects were a potential confounder, we found that propofol induced a dose-dependent increase in proton leak and caused a defect in substrate oxidation at coenzyme Q (CoQ). These impairments prevented propofol-exposed cardiomyocyte mitochondria from generating an adequate ΔΨ. The addition of the quinone analog, CoQ0, blocked propofol-induced leak and increased Complex II+III activity.Propofol uncoupled immature cardiomyocyte mitochondria by inducing excessive CoQ-sensitive leak and interfered with electron transport at CoQ. The findings provide new insight into the mechanisms of propofol toxicity in the developing heart and may help explain why children are vulnerable to developing PRIS.Propofol uncouples immature cardiomyocyte mitochondria by inducing excessive coenzyme Q (CoQ)-sensitive proton leak. Propofol also interferes with electron transport at the level of CoQ. These defects provide new insight into propofol toxicity in the developing heart.

  View details for DOI 10.1038/s41390-022-01985-1

  View details for Web of Science ID 000756191200002

  View details for PubMedID 35173299

  View details for PubMedCentralID PMC9378757

• Papper Event 2021: The COVID-19 Pandemic: Lessons Learned and the Way Forward JOURNAL OF NEUROSURGICAL ANESTHESIOLOGY Sun, L. S., Brambrink, A., Emala, C. W., Hua, M., Lee, H., Levy, R. J., Smiley, R. M., Whittington, R. A., Narula, J. 2022; 34 (1): 99-100

  View details for DOI 10.1097/ANA.0000000000000801

  View details for Web of Science ID 000726799100036

  View details for PubMedID 34870629

• Prevalence of SARS-CoV-2 Positivity in Pediatric Surgical Patients Amid the First Wave of the COVID-19 Pandemic in New York City Price, J. C., Lee, J. J., Ing, C., Li, G., Narula, J., Clark, M. K., Stylianos, S., Whittington, R. A., Levy, R. J., Sun, L. S. LIPPINCOTT WILLIAMS & WILKINS. 2022: 132-135

  Abstract

  New York State implemented an 11-week elective surgery ban in response to the coronavirus disease-2019 (COVID-19) pandemic, during which pediatric patients from the 10 New York Presbyterian network hospitals requiring urgent or emergent surgical procedures were cared for at Morgan Stanley Children's Hospital (MSCH).Data was abstracted from the electronic medical record of all patients aged 0 to 20 years who had surgery at MSCH from March 23, 2020 to June 7, 2020. Comparative analysis of demographic and clinical data elements between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive and negative cohorts was conducted using the Fisher exact tests.A total of 505 surgical procedures were performed in 451 patients, with 32 procedures (6.3%) performed in 21 SARS-CoV-2-positive children. The prevalence of SARS-CoV-2 positivity in Medicaid beneficiaries was more than twice the prevalence in commercially insured (6.8% vs. 2.6%, P=0.04) children. SARS-CoV-2-positive patients were more likely to undergo multiple surgical procedures (23.8% vs. 7.2%, P=0.02), and to have higher American Society of Anesthesiologists (ASA) class designations (69.8% III to V vs. 47.4% I to II, P=0.03). There was no significant difference in the prevalence of SARS-CoV-2 positivity across sex, age, race, or ethnicity groups, or in emergent case status or surgical procedure type. Thirty-day mortality rate was <0.1% overall, with no deaths in the SARS-CoV-2-positive group.During the first wave of the COVID-19 pandemic in New York City, we found a higher prevalence of SARS-CoV-2 positivity in urgent/emergent pediatric surgical patients compared with other institutions in the United States. SARS-CoV-2-positive patients were more likely to be Medicaid beneficiaries, were clinically more complex, and had more surgical procedures.

  View details for DOI 10.1097/ANA.0000000000000805

  View details for Web of Science ID 000726799100043

  View details for PubMedID 34870636

• A Novel Method to Detect Changes in Mitochondrial Permeability Transition Pore Voltage Gating in Isolated Mouse Heart Mitochondria Griffiths, K. K., Wang, A., Somnay, Y., Levy, R. J. LIPPINCOTT WILLIAMS & WILKINS. 2021: 798

  View details for Web of Science ID 000752526600347

• Altered Brown Adipose Mitochondrial Respiration in Fragile X Syndrome Mice Somnay, Y., Wang, A., Griffiths, K. K., Levy, R. J. LIPPINCOTT WILLIAMS & WILKINS. 2021: 564-565

  View details for Web of Science ID 000752526600240

• Isoflurane and low-level carbon monoxide exposures increase expression of pro-survival miRNA in neonatal mouse heart CELL STRESS & CHAPERONES Logan, S. M., Gupta, A., Wang, A., Levy, R. J., Storey, K. B. 2021; 26 (3): 541-548

  Abstract

  Anesthetics such as isoflurane are known to cause apoptosis in the developing mammalian brain. However, isoflurane may have protective effects on the heart via relieving ischemia and downregulating genes related to apoptosis. Ischemic preconditioning, e.g. through the use of low levels of carbon monoxide (CO), has promise in preventing ischemia-reperfusion injury and cell death. However, it is still unclear how it either triggers the stress response in neonatal hearts. For this reason, thirty-three microRNAs (miRNAs) known to be differentially expressed following anesthesia and/or ischemic or hypoxic heart damage were investigated in the hearts from neonatal mice exposed to isoflurane or low level of CO, using an air-exposed control group. Only miR-93-5p increased with isoflurane exposure, which may be associated with the suppression of cell death, autophagy, and inflammation. By contrast, twelve miRNAs were differentially expressed in the heart following CO treatment. Many miRNAs previously shown to be responsible for suppressing cell death, autophagy, and myocardial hypertrophy were upregulated (e.g., 125b-3p, 19-3p, and 21a-5p). Finally, some miRNAs (miR-103-3p, miR-1a-3p, miR-199a-1-5p) which have been implicated in regulating energy balance and cardiac contraction were also differentially expressed. Overall, this study demonstrated that CO-mediated miRNA regulation may promote ischemic preconditioning and cardioprotection based on the putative protective roles of the differentially expressed miRNAs explored herein and the consistency of these results with those that have shown positive effects of CO on heart viability following anesthesia and ischemia-reperfusion stress.

  View details for DOI 10.1007/s12192-021-01199-0

  View details for Web of Science ID 000625335800001

  View details for PubMedID 33661504

  View details for PubMedCentralID PMC8065082

• Insights image for "The newborn <i>Fmr1</i> knockout mouse: a novel model of excess ubiquinone and closed mitochondrial permeability transition pore in the developing heart" PEDIATRIC RESEARCH Barajas, M., Wang, A., Griffiths, K. K., Matsumoto, K., Liu, R., Homma, S., Levy, R. J. 2021; 89 (3): 707

  View details for DOI 10.1038/s41390-020-01144-4

  View details for Web of Science ID 000578253300002

  View details for PubMedID 32919395

• ATP Synthase c-Subunit Leak Causes Aberrant Cellular Metabolism in Fragile X Syndrome CELL Licznerski, P., Park, H., Rolyan, H., Chen, R., Mnatsakanyan, N., Miranda, P., Graham, M., Wu, J., Cruz-Reyes, N., Mehta, N., Sohail, S., Salcedo, J., Song, E., Effman, C., Effman, S., Brandao, L., Xu, G. N., Braker, A., Gribkoff, V. K., Levy, R. J., Jonas, E. A. 2020; 182 (5): 1170-+

  Abstract

  Loss of the gene (Fmr1) encoding Fragile X mental retardation protein (FMRP) causes increased mRNA translation and aberrant synaptic development. We find neurons of the Fmr1-/y mouse have a mitochondrial inner membrane leak contributing to a "leak metabolism." In human Fragile X syndrome (FXS) fibroblasts and in Fmr1-/y mouse neurons, closure of the ATP synthase leak channel by mild depletion of its c-subunit or pharmacological inhibition normalizes stimulus-induced and constitutive mRNA translation rate, decreases lactate and key glycolytic and tricarboxylic acid (TCA) cycle enzyme levels, and triggers synapse maturation. FMRP regulates leak closure in wild-type (WT), but not FX synapses, by stimulus-dependent ATP synthase β subunit translation; this increases the ratio of ATP synthase enzyme to its c-subunit, enhancing ATP production efficiency and synaptic growth. In contrast, in FXS, inability to close developmental c-subunit leak prevents stimulus-dependent synaptic maturation. Therefore, ATP synthase c-subunit leak closure encourages development and attenuates autistic behaviors.

  View details for DOI 10.1016/j.cell.2020.07.008

  View details for Web of Science ID 000571442200010

  View details for PubMedID 32795412

  View details for PubMedCentralID PMC7484101

• The newborn<i>Fmr1</i>knockout mouse: a novel model of excess ubiquinone and closed mitochondrial permeability transition pore in the developing heart PEDIATRIC RESEARCH Barajas, M., Wang, A., Griffiths, K. K., Matsumoto, K., Liu, R., Homma, S., Levy, R. J. 2021; 89 (3): 456-463

  Abstract

  Mitochondrial permeability transition pore (mPTP) closure triggers cardiomyocyte differentiation during development while pathological opening causes cell death during myocardial ischemia-reperfusion and heart failure. Ubiquinone modulates the mPTP; however, little is known about its mechanistic role in health and disease. We previously found excessive proton leak in newborn Fmr1 KO mouse forebrain caused by ubiquinone deficiency and increased open mPTP probability. Because of the physiological differences between the heart and brain during maturation, we hypothesized that developing Fmr1 KO cardiomyocyte mitochondria would demonstrate dissimilar features.Newborn male Fmr1 KO mice and controls were assessed. Respiratory chain enzyme activity, ubiquinone content, proton leak, and oxygen consumption were measured in cardiomyocyte mitochondria. Cardiac function was evaluated via echocardiography.In contrast to controls, Fmr1 KO cardiomyocyte mitochondria demonstrated increased ubiquinone content and decreased proton leak. Leak was cyclosporine (CsA)-sensitive in controls and CsA-insensitive in Fmr1 KOs. There was no difference in absolute mitochondrial respiration or cardiac function between strains.These findings establish the newborn Fmr1 KO mouse as a novel model of excess ubiquinone and closed mPTP in the developing heart. Such a model may help provide insight into the biology of cardiac development and pathophysiology of neonatal heart failure.Ubiquinone is in excess and the mPTP is closed in the developing FXS heart. Strengthens evidence of open mPTP probability in the normally developing postnatal murine heart and provides new evidence for premature closure of the mPTP in Fmr1 mutants. Establishes a novel model of excess CoQ and a closed pore in the developing heart. Such a model will be a valuable tool used to better understand the role of ubiquinone and the mPTP in the neonatal heart in health and disease.

  View details for DOI 10.1038/s41390-020-1064-6

  View details for Web of Science ID 000551009100001

  View details for PubMedID 32674111

  View details for PubMedCentralID PMC7855053

• A Novel Method to Detect Changes in Permeability Transition Pore Voltage Gating in Neonatal Mouse Heart Mitochondria Griffiths, K. K., Wang, A., Levy, R. J. LIPPINCOTT WILLIAMS & WILKINS. 2020: 700

  View details for Web of Science ID 000619264500337

• Successful Langendorff-perfused Isolated Heart Preparation in Neonatal Mice Barajas, M., Levy, R. J., Griffiths, K. K. LIPPINCOTT WILLIAMS & WILKINS. 2020: 119-120

  View details for Web of Science ID 000619264500053

• Propofol Toxicity in Cardiomyocyte Mitochondria of Developing Mice: A Novel Mechanism of Pediatric Propofol Infusion Syndrome? Barajas, M., Brunner, S., Wang, A., Levy, R. J. LIPPINCOTT WILLIAMS & WILKINS. 2020: 47-48

  View details for Web of Science ID 000619264500021

• Inefficient thermogenic mitochondrial respiration due to futile proton leak in a mouse model of fragile X syndrome FASEB JOURNAL Griffiths, K. K., Wang, A., Wang, L., Tracey, M., Kleiner, G., Quinzii, C. M., Sun, L., Yang, G., Perez-Zoghbi, J. F., Licznerski, P., Yang, M., Jonas, E. A., Levy, R. J. 2020; 34 (6): 7404-7426

  Abstract

  Fragile X syndrome (FXS) is the leading known inherited intellectual disability and the most common genetic cause of autism. The full mutation results in transcriptional silencing of the Fmr1 gene and loss of fragile X mental retardation protein (FMRP) expression. Defects in neuroenergetic capacity are known to cause a variety of neurodevelopmental disorders. Thus, we explored the integrity of forebrain mitochondria in Fmr1 knockout mice during the peak of synaptogenesis. We found inefficient thermogenic respiration due to futile proton leak in Fmr1 KO mitochondria caused by coenzyme Q (CoQ) deficiency and an open cyclosporine-sensitive channel. Repletion of mitochondrial CoQ within the Fmr1 KO forebrain closed the channel, blocked the pathological proton leak, restored rates of protein synthesis during synaptogenesis, and normalized the key phenotypic features later in life. The findings demonstrate that FMRP deficiency results in inefficient oxidative phosphorylation during the neurodevelopment and suggest that dysfunctional mitochondria may contribute to the FXS phenotype.

  View details for DOI 10.1096/fj.202000283RR

  View details for Web of Science ID 000527568000001

  View details for PubMedID 32307754

  View details for PubMedCentralID PMC7692004

• The role of anaesthesiologists in lethal injection: a call to action LANCET Kim, E., Levy, R. J. 2020; 395 (10225): 749-754

  View details for DOI 10.1016/S0140-6736(19)32986-1

  View details for Web of Science ID 000516755200032

  View details for PubMedID 32014115

  View details for PubMedCentralID PMC7416913

• An isolated retrograde-perfused newborn mouse heart preparation METHODSX Barajas, M., Yim, P. D., Gallos, G., Levy, R. J. 2020; 7: 101058

  Abstract

  The Langendorff-perfused model is a powerful tool to study biological responses in the isolated heart in the absence of confounders. The model has been adapted recently to enable study of the isolated mouse heart and the effects of genetic manipulation. Unfortunately, the small size and fragility of the mouse heart pose significant challenges, limiting application of the Langendorff model to the study of adult mice. Cardiac development is a complex and dynamic process that is incompletely understood. Thus, establishing an isolated-perfused heart model in the newborn mouse would be an important and necessary advance. Here we present a method to successfully cannulate and perfuse the isolated newborn murine heart. We describe the basic and fundamental physiological characteristics of the ex-vivo retrograde-perfused beating neonatal heart in wild-type C57Bl/6 male mice. Our approach will enable future study of the physiological and pharmacological responses of the isolated immature murine heart to enhance knowledge of how developmental cardiac biology impacts health and disease.•The Langendorff model is a powerful tool to study the heart without confounders.•An isolated-perfused newborn murine heart model has yet to be established.•We demonstrate the first successful isolated neonatal murine heart preparation.

  View details for DOI 10.1016/j.mex.2020.101058

  View details for Web of Science ID 000607658800011

  View details for PubMedID 32983923

  View details for PubMedCentralID PMC7492986

• PROPOFOL TOXICITY IN CARDIOMYOCYTE MITOCHONDRIA OF DEVELOPING MICE: THE ROLE OF THE MITOCHONDRIAL TRANSITION PORE Barajas, M., Levy, R. J., Brunner, S., Wang, L., Wang, A. LIPPINCOTT WILLIAMS & WILKINS. 2019: 85-86

  View details for Web of Science ID 000619263200044

• PROPOFOL TOXICITY IN TISSUE-SPECIFIC MITOCHONDRIA DURING DEVELOPMENT Brunner, S., Barajas, M., Wang, A., Wang, L., Levy, R. LIPPINCOTT WILLIAMS & WILKINS. 2019

  View details for Web of Science ID 000498593402286

• Report on the Sixth Pediatric Anesthesia Neurodevelopmental Assessment (PANDA) Symposium, "Anesthesia and Neurodevelopment in Children" Lee, J. J., Sun, L. S., Levy, R. J. LIPPINCOTT WILLIAMS & WILKINS. 2019: 103-107

  Abstract

  On April 14 and 15, 2018, the Sixth Biennial Pediatric Anesthesia Neurodevelopmental Assessment (PANDA) Symposium convened at Columbia University Medical Center and New York Presbyterian/Morgan Stanley Children's Hospital of New York. Since its inception over 10 years ago, the PANDA Symposium has served as a key forum for clinicians, researchers, and other major stakeholders to gather and review the current state of preclinical and clinical research related to anesthetic neurotoxicity in the developing brain. It has also served as an important venue for participants to gain insight and leverage support from various public and private regulatory bodies. Goals of this year's meeting included assessments of how current knowledge has evolved, endeavors to develop common outcome measures, and formulations of future directions for research and policy. The Symposium program highlighted a diverse body of cutting-edge work, from results of preclinical and clinical studies to updates in clinical practice and policymaking.

  View details for DOI 10.1097/ANA.0000000000000538

  View details for Web of Science ID 000453590900021

  View details for PubMedID 30767931

  View details for PubMedCentralID PMC6383795

• EVIDENCE OF A DISCRETE AND TARGETABLE MITOCHONDRIAL DEFECT IN THE DEVELOPING FRAGILE X SYNDROME BRAIN Levy, R. J., Griffths, K. K., Wang, A., Wang, L., Tracey, M., Quinzii, C., Jonas, E. A. LIPPINCOTT WILLIAMS & WILKINS. 2018: 67

  View details for Web of Science ID 000460106500040

• Data on the effect of sex on the size, cellular content, and neuronal density of the developing brain in mice exposed to isoflurane and carbon monoxide DATA IN BRIEF Wang, L., Wang, A., Supplee, W. W., Koffler, K., Cheng, Y., Quezado, Z. M. N., Levy, R. J. 2017; 13: 550-556

  Abstract

  The data presented here detail the changes in size, cellular content, and neuronal density of the developing brain over time with respect to sex in C57Bl/6 mice following neonatal exposure to isoflurane, carbon monoxide, or their combination. Specifically, brain weight- and brain volume-to-body weight ratios are presented, representative immunoblots of whole brain cell-specific protein content are depicted, and quantification of the number of neurons in the primary somatosensory cortex and CA3 region of the hippocampus are shown. Three discrete postnatal time points are represented: P7 (prior to exposure), P14 (one-week post exposure), and P42-56 (5-7 weeks post exposure). Major findings from the data presented here are reported in the manuscript "Carbon Monoxide Incompletely Prevents Isoflurane-induced Defects in Murine Neurodevelopment" (Wang et al., in press) [1].

  View details for DOI 10.1016/j.dib.2017.06.028

  View details for Web of Science ID 000453403700076

  View details for PubMedID 28702493

  View details for PubMedCentralID PMC5491399

• Volatile Organic Compounds Derived from Inhaled Anesthetics and Human Breath Pollute the Anesthesia Circuit Ng, F. W., Klausner, A. J., Cataneo, R., Phillips, M., Sun, L., Levy, R. J. LIPPINCOTT WILLIAMS & WILKINS. 2017: 1128

  View details for Web of Science ID 000412683000567

• Myocardial cytochrome oxidase activity increases with age and hypoxemia in patients with congenital heart disease PERFUSION-UK Onwugbufor, M., Levy, R. J., Zurakowski, D., Jonas, R. A., Sinha, P. 2017; 32 (4): 306-312

  Abstract

  Myocardial tolerance to ischemia is influenced by age and preoperative cyanosis through unknown mechanisms and significantly affects postoperative outcomes. Cytochrome c oxidase (CcOx), the terminal enzyme of the mitochondrial electron transport chain, may play a role in the susceptibility to ischemic-reperfusion (IR) injury. Our study aimed at investigating changes in human myocardial CcOx activity based on age and preoperative oxygen saturation to understand its role in transition from neonatal to mature myocardium and hypoxic conditions.The right atrial appendage from patients undergoing first time surgical repair/palliation of congenital heart defects was analyzed for steady state CcOx activity by oxidation of ferrocytochrome c via spectrophotometry and steady state CcOx subunit I protein content by protein immunoblotting. Student's t-test compared CcOx activity and protein levels between patients with preoperative hypoxia and normoxia. Multiple linear regression analysis was used to assess the effects of age and preoperative arterial oxygen saturations (SaO2) on CcOx protein activity and protein content.Thirty-two patients with a median (interquartile range) age of 83 days (8-174) and preoperative oxygen saturation 98% (85-100%) were enrolled. Independent of age, preoperative SaO2 ⩽90% was associated with significantly greater CcOx steady state activity (p=0.004). Additionally, older age itself was associated with increased CcOx steady state activity (p=0.022); the combination of preoperative SaO2 and age account for 33% of the variation in CcOx steady state activity (R2=0.332). There was no increase in the CcOx subunit I protein content with either age or preoperative hypoxia.In patients with congenital heart disease, an increase in CcOx steady state activity is seen with increasing age. Hypoxia leads to upregulation of CcOx steady state activity without an increase in the amount of enzyme protein itself. Higher CcOx activity in older and cyanotic patients may indicate CcOx-dependent reactive oxygen species as the mechanism for IR injury.

  View details for DOI 10.1177/0267659116681435

  View details for Web of Science ID 000400121000008

  View details for PubMedID 27913766

  View details for PubMedCentralID PMC5395335

• Carbon monoxide incompletely prevents isoflurane-induced defects in murine neurodevelopment NEUROTOXICOLOGY AND TERATOLOGY Wang, L., Wang, A., Supplee, W. W., Koffler, K., Cheng, Y., Quezado, Z. M. N., Levy, R. J. 2017; 61: 92-103

  Abstract

  Commonly used anesthetics have been shown to disrupt neurodevelopment in preclinical models. It has been proposed that such anesthesia-induced neurotoxicity is mediated by apoptotic neurodegeneration in the immature brain. Low dose carbon monoxide (CO) exerts cytoprotective properties and we have previously demonstrated that CO inhibits isoflurane-induced apoptosis in the developing murine brain. Here we utilized anti-apoptotic concentrations of CO to delineate the role of apoptotic neurodegeneration in anesthesia-induced neurotoxicity by assessing the effect of CO on isoflurane-induced defects in neurodevelopment.C57Bl/6 mouse pups underwent 1-hour exposure to 0ppm (air), 5ppm, or 100ppm CO in air with or without isoflurane on postnatal day 7. Cohorts were evaluated 5-7weeks post exposure with T-maze cognitive testing followed by social behavior assessment. Brain size, whole brain cellular content, and neuronal density in primary somatosensory cortex and hippocampal CA3 region were measured as secondary outcomes 1-week or 5-7weeks post exposure along with 7-day old, unexposed controls.Isoflurane impaired memory acquisition and resulted in abnormal social behavior. Low concentration CO abrogated anesthetic-induced defects in memory acquisition, however, it also resulted in impaired spatial reference memory and social behavior abnormalities. Changes in brain size, cellular content, and neuronal density over time related to the age of the animal and were unaffected by either isoflurane or CO.Anti-apoptotic concentrations of CO incompletely prevented isoflurane-induced defects in neurodevelopment, lacked concentration-dependent effects, and only provided protection in certain domains suggesting that anesthesia-related neurotoxicity is not solely mediated by activation of the mitochondrial apoptosis pathway.

  View details for DOI 10.1016/j.ntt.2017.01.004

  View details for Web of Science ID 000403512700011

  View details for PubMedID 28131877

  View details for PubMedCentralID PMC5498225

• Mitochondrial cAMP-dependent Phosphorylation in the Developing Murine Brain Levy, R. J., Wang, A., Long, Y. LIPPINCOTT WILLIAMS & WILKINS. 2017: 889

  View details for Web of Science ID 000412683000450

• EACA Is Associated with Reduced Blood Loss in Pediatric Craniofacial Surgery Reddy, S. K., Mann, T., Gordish-Dressman, H., Keating, R. F., Levy, R. J. LIPPINCOTT WILLIAMS & WILKINS. 2017: 920

  View details for Web of Science ID 000412683000468

• Carbon monoxide and anesthesia-induced neurotoxicity NEUROTOXICOLOGY AND TERATOLOGY Levy, R. J. 2017; 60: 50-58

  Abstract

  The majority of commonly used anesthetic agents induce widespread neuronal degeneration in the developing mammalian brain. Downstream, the process appears to involve activation of the oxidative stress-associated mitochondrial apoptosis pathway. Targeting this pathway could result in prevention of anesthetic toxicity in the immature brain. Carbon monoxide (CO) is a gas that exerts biological activity in the developing brain and low dose exposures have the potential to provide neuroprotection. In recent work, low concentration CO exposures limited isoflurane-induced neuronal apoptosis in a dose-dependent manner in newborn mice and modulated oxidative stress within forebrain mitochondria. Because infants and children are routinely exposed to low levels of CO during low-flow general endotracheal anesthesia, such anti-oxidant and pro-survival cellular effects are clinically relevant. Here we provide an overview of anesthesia-related CO exposure, discuss the biological activity of low concentration CO, detail the effects of CO in the brain during development, and provide evidence for CO-mediated inhibition of anesthesia-induced neurotoxicity.

  View details for DOI 10.1016/j.ntt.2016.09.002

  View details for Web of Science ID 000399509900006

  View details for PubMedID 27616667

  View details for PubMedCentralID PMC5344786

• Evidence of Mitochondrial Dysfunction in Autism: Biochemical Links, Genetic-Based Associations, and Non-Energy-Related Mechanisms OXIDATIVE MEDICINE AND CELLULAR LONGEVITY Griffiths, K. K., Levy, R. J. 2017; 2017: 4314025

  Abstract

  Autism spectrum disorder (ASD), the fastest growing developmental disability in the United States, represents a group of neurodevelopmental disorders characterized by impaired social interaction and communication as well as restricted and repetitive behavior. The underlying cause of autism is unknown and therapy is currently limited to targeting behavioral abnormalities. Emerging studies suggest a link between mitochondrial dysfunction and ASD. Here, we review the evidence demonstrating this potential connection. We focus specifically on biochemical links, genetic-based associations, non-energy related mechanisms, and novel therapeutic strategies.

  View details for DOI 10.1155/2017/4314025

  View details for Web of Science ID 000402329400001

  View details for PubMedID 28630658

  View details for PubMedCentralID PMC5467355

• Biomarkers, Genetics, and Epigenetic Studies to Explore the Neurocognitive Effects of Anesthesia in Children Levy, R. J., Herbstman, J. B., Bosnjak, Z. J., Loepke, A. W., McGowan, F. X. LIPPINCOTT WILLIAMS & WILKINS. 2016: 384-388

  Abstract

  Exposure to commonly used anesthetic agents causes widespread neuronal degeneration in the developing mammalian brain and has been shown to impair neurodevelopment in a variety of newborn vertebrate animal species. Although retrospective studies have suggested an association between anesthesia exposure in childhood and subsequent neurodevelopmental abnormalities, a causal relationship in humans has yet to be demonstrated. Unfortunately, translation of findings from bench to bedside is limited by several factors and histologic assessment in healthy children following exposure to anesthesia is not possible. Therefore, to prove that anesthesia-induced neurotoxicity occurs in humans, alternative approaches are necessary. Here we present the summary of a focus group discussion regarding the utility of biomarkers in translational studies of anesthetic neurotoxicity as part of The 2016 Pediatric Anesthesia NeuroDevelopmental Assessment (PANDA) Symposium at Columbia University Medical Center. The experts agreed that defining intermediate phenotypes using advanced neuroimaging as a biomarker is a highly feasible and reasonable modality to provide new insights into the deleterious effects of anesthetic exposure in the developing human brain and could illuminate a viable investigative path forward. Ultimately, well-defined intermediate phenotypes may allow us to fully understand the neurodevelopmental impact of anesthesia-induced neurotoxicity and permit us to develop the safest and most effective anesthetic strategies for the infants and children we care for.

  View details for DOI 10.1097/ANA.0000000000000351

  View details for Web of Science ID 000385211800018

  View details for PubMedID 27564554

  View details for PubMedCentralID PMC5326616

• Anesthesia-Related Carbon Monoxide Exposure: Toxicity and Potential Therapy ANESTHESIA AND ANALGESIA Levy, R. J. 2016; 123 (3): 670-681

  Abstract

  Exposure to carbon monoxide (CO) during general anesthesia can result from volatile anesthetic degradation by carbon dioxide absorbents and rebreathing of endogenously produced CO. Although adherence to the Anesthesia Patient Safety Foundation guidelines reduces the risk of CO poisoning, patients may still experience subtoxic CO exposure during low-flow anesthesia. The consequences of such exposures are relatively unknown. In contrast to the widely recognized toxicity of high CO concentrations, the biologic activity of low concentration CO has recently been shown to be cytoprotective. As such, low-dose CO is being explored as a novel treatment for a variety of different diseases. Here, we review the concept of anesthesia-related CO exposure, identify the sources of production, detail the mechanisms of overt CO toxicity, highlight the cellular effects of low-dose CO, and discuss the potential therapeutic role for CO as part of routine anesthetic management.

  View details for DOI 10.1213/ANE.0000000000001461

  View details for Web of Science ID 000381838800018

  View details for PubMedID 27537758

  View details for PubMedCentralID PMC5021316

• Anesthesia-Induced Neuronal Apoptosis in the Developing Retina: A Window of Opportunity ANESTHESIA AND ANALGESIA Cheng, Y., He, L., Prasad, V., Wang, S., Levy, R. J. 2015; 121 (5): 1325-1335

  Abstract

  Anesthetics cause widespread apoptosis in the developing brain, resulting in neurocognitive abnormalities. However, it is unknown whether anesthesia-induced neurotoxicity occurs in humans because there is currently no modality to assess for neuronal apoptosis in vivo. The retina is unique in that it is the only portion of the central nervous system that can be directly visualized noninvasively. Thus, we aimed to determine whether isoflurane induces apoptosis in the developing retina.CD-1 male mouse pups underwent 1-hour exposure to isoflurane (2%) or air. After exposure, activated caspase-3, caspase-9, and caspase-8 were quantified in the retina, cytochrome c release from retinal mitochondria was assessed, and the number and types of cells undergoing apoptosis were identified. Retinal uptake and the ability of fluorescent-labeled annexin V to bind to cells undergoing natural cell death and anesthesia-induced apoptosis in the retina were determined after systemic injection.Isoflurane activated the intrinsic apoptosis pathway in the inner nuclear layer (INL) and activated both the intrinsic and extrinsic pathways in the ganglion cell layer. Immunofluorescence demonstrated that bipolar and amacrine neurons within the INL underwent physiologic cell death in both cohorts and that amacrine cells were the likely targets of isoflurane-induced apoptosis. After injection, fluorescent-labeled annexin V was readily detected in the INL of both air-exposed and isoflurane-exposed mice and colocalized with activated caspase-3-positive cells.These findings indicate that isoflurane-induced neuronal apoptosis occurs in the developing retina and lays the groundwork for development of a noninvasive imaging technique to detect anesthesia-induced neurotoxicity in infants and children.

  View details for DOI 10.1213/ANE.0000000000000714

  View details for Web of Science ID 000363296800004

  View details for PubMedID 26465931

  View details for PubMedCentralID PMC4760346

• Carbon monoxide modulates cytochrome oxidase activity and oxidative stress in the developing murine brain during isoflurane exposure FREE RADICAL BIOLOGY AND MEDICINE Cheng, Y., Mitchell-Flack, M. J., Wang, A., Levy, R. J. 2015; 86: 191-199

  Abstract

  Commonly used anesthetics induce widespread neuronal degeneration in the developing mammalian brain via the oxidative-stress-associated mitochondrial apoptosis pathway. Dysregulation of cytochrome oxidase (CcOX), the terminal oxidase of the electron transport chain, can result in reactive oxygen species (ROS) formation. Isoflurane has previously been shown to activate this enzyme. Carbon monoxide (CO), as a modulator of CcOX, is of interest because infants and children are routinely exposed to CO during low-flow anesthesia. We have recently demonstrated that low concentrations of CO limit and prevent isoflurane-induced neurotoxicity in the forebrains of newborn mice in a dose-dependent manner. However, the effect of CO on CcOX in the context of anesthetic-induced oxidative stress is unknown. Seven-day-old male CD-1 mice underwent 1h exposure to 0 (air), 5, or 100ppm CO in air with or without isoflurane. Exposure to isoflurane or CO independently increased CcOX kinetic activity and increased ROS within forebrain mitochondria. However, exposure to CO combined with isoflurane paradoxically limited CcOX activation and oxidative stress. There were no changes seen in steady-state levels of CcOX I protein, indicating post-translational modification of CcOX as an etiology for changes in enzyme activity. CO exposure led to differential effects on CcOX subunit I tyrosine phosphorylation depending on concentration, while combined exposure to isoflurane with CO markedly increased the enzyme phosphorylation state. Phosphorylation of tyrosine 304 of CcOX subunit I has been shown to result in strong enzyme inhibition, and the relative reduction in CcOX kinetics following exposure to CO combined with isoflurane may have been due, in part, to such phosphorylation. Taken together, the data suggest that CO modulates CcOX in the developing brain during isoflurane exposure, thereby limiting oxidative stress. These CO-mediated effects could have implications for the development of low-flow anesthesia in infants and children to prevent anesthesia-induced oxidative stress.

  View details for DOI 10.1016/j.freeradbiomed.2015.05.029

  View details for Web of Science ID 000360569700018

  View details for PubMedID 26032170

  View details for PubMedCentralID PMC4568063

• Carbon monoxide pollution and neurodevelopment: A public health concern NEUROTOXICOLOGY AND TERATOLOGY Levy, R. J. 2015; 49: 31-40

  Abstract

  Although an association between air pollution and adverse systemic health effects has been known for years, the effect of pollutants on neurodevelopment has been underappreciated. Recent evidence suggests a possible link between air pollution and neurocognitive impairment and behavioral disorders in children, however, the exact nature of this relationship remains poorly understood. Infants and children are uniquely vulnerable due to the potential for exposure in both the fetal and postnatal environments during critical periods in development. Carbon monoxide (CO), a common component of indoor and outdoor air pollution, can cross the placenta to gain access to the fetal circulation and the developing brain. Thus, CO is of particular interest as a known neurotoxin and a potential public health threat. Here we review overt CO toxicity and the policies regulating CO exposure, detail the evidence suggesting a potential link between CO-associated ambient air pollution, tobacco smoke, and learning and behavioral abnormalities in children, describe the effects of subclinical CO exposure on the brain during development, and provide mechanistic insight into a potential connection between CO exposure and neurodevelopmental outcome. CO can disrupt a number of critical processes in the developing brain, providing a better understanding of how this specific neurotoxin may impair neurodevelopment. However, further investigation is needed to better define the effects of perinatal CO exposure on the immature brain. Current policies regarding CO standards were established based on evidence of cardiovascular risk in adults with pre-existing comorbidities. Thus, recent and emerging data highlighted in this review regarding CO exposure in the fetus and developing child may be important to consider when the standards and guidelines are evaluated and revised in the future.

  View details for DOI 10.1016/j.ntt.2015.03.001

  View details for Web of Science ID 000357142700004

  View details for PubMedID 25772154

  View details for PubMedCentralID PMC4568061

• Anesthetic and Sedative Neurotoxicity in the Patient with Congenital Heart Disease ANESTHESIA FOR CONGENITAL HEART DISEASE, 3RD EDITION Levy, R. J., Wise-Faberowski, L., Andropoulos, D. B. edited by Andropoulos, D. B., Stayer, S., Mossad, E. B., MillerHance, W. C. 2015: 184–98

  View details for Web of Science ID 000385225800010

• Subclinical Carbon Monoxide Limits Apoptosis in the Developing Brain After Isoflurane Exposure ANESTHESIA AND ANALGESIA Cheng, Y., Levy, R. J. 2014; 118 (6): 1284-1292

  Abstract

  Volatile anesthetics cause widespread apoptosis in the developing brain. Carbon monoxide (CO) has antiapoptotic properties, and exhaled endogenous CO is commonly rebreathed during low-flow anesthesia in infants and children, resulting in subclinical CO exposure. Thus, we aimed to determine whether CO could limit isoflurane-induced apoptosis in the developing brain.Seven-day-old male CD-1 mouse pups underwent 1-hour exposure to 0 (air), 5, or 100 ppm CO in air with or without isoflurane (2%). We assessed carboxyhemoglobin levels, cytochrome c peroxidase activity, and cytochrome c release from forebrain mitochondria after exposure and quantified the number of activated caspase-3 positive cells and TUNEL positive nuclei in neocortex, hippocampus, and hypothalamus/thalamus.Carboxyhemoglobin levels approximated those expected in humans after a similar time-weighted CO exposure. Isoflurane significantly increased cytochrome c peroxidase activity, cytochrome c release, the number of activated caspase-3 cells, and TUNEL positive nuclei in the forebrain of air-exposed mice. CO, however, abrogated isoflurane-induced cytochrome c peroxidase activation and cytochrome c release from forebrain mitochondria and decreased the number of activated caspase-3 positive cells and TUNEL positive nuclei after simultaneous exposure with isoflurane.Taken together, the data indicate that CO can limit apoptosis after isoflurane exposure via inhibition of cytochrome c peroxidase depending on concentration. Although it is unknown whether CO directly inhibited isoflurane-induced apoptosis, it is possible that low-flow anesthesia designed to target rebreathing of specific concentrations of CO may be a desired strategy to develop in the future in an effort to prevent anesthesia-induced neurotoxicity in infants and children.

  View details for DOI 10.1213/ANE.0000000000000030

  View details for Web of Science ID 000336352600019

  View details for PubMedID 24413549

  View details for PubMedCentralID PMC4029883

• Detection of Alpha II-Spectrin Breakdown Products in the Serum of Neonates With Congenital Heart Disease PEDIATRIC CRITICAL CARE MEDICINE Jain, P., Spaeder, M. C., Donofrio, M. T., Sinha, P., Jonas, R. A., Levy, R. J. 2014; 15 (3): 229-235

  Abstract

  To determine if alpha II-spectrin breakdown products can be detected in the serum of neonates with congenital heart disease in the perioperative period.Prospective observational cohort study.Pediatric cardiac ICU in an urban tertiary care academic center.Neonates with congenital heart disease undergoing surgical repair or palliation.Serial blood sampling for measurement of 120 and 150 kDa spectrin breakdown products.Fourteen neonates with congenital heart disease undergoing cardiac surgery were evaluated. Nine infants underwent open-heart surgery and five underwent closed-heart surgery. Serum spectrin breakdown products were measured with sandwich enzyme-linked immunosorbent assay preoperatively and then 6, 24, 48, 72, and 96 hours following surgery. Brain imaging was obtained as part of routine clinical care in 12 patients preoperatively and six patients postoperatively. Six patients had normal preoperative imaging (three closed-heart surgery and three open-heart surgery), whereas six had evidence of neurologic injury prior to surgery (one closed-heart surgery and five open-heart surgery). Only one patient had a postoperative imaging study that lacked injury. All others demonstrated infarction or hemorrhage. Spectrin breakdown product 120 kDa significantly increased 24 hours after open-heart surgery compared to preoperative values and time-matched closed-heart surgery levels. Spectrin breakdown product 150 kDa significantly increased 6 hours after open-heart surgery compared to preoperative values. There was no significant change in spectrin breakdown products following closed-heart surgery. Peak spectrin breakdown products significantly increased following open-heart surgery compared to closed-heart surgery.Spectrin breakdown products can be detected in the serum of neonates with congenital heart disease in the perioperative period and levels increased to a greater degree in infants following open-heart surgery. These findings suggest that, in future work, serum spectrin breakdown products may potentially be developed as biomarkers for brain necrosis and apoptosis in infants with congenital heart disease.

  View details for DOI 10.1097/PCC.0000000000000059

  View details for Web of Science ID 000335331700009

  View details for PubMedID 24395002

  View details for PubMedCentralID PMC4059536

• Specialized Delivery Room Planning for Fetuses With Critical Congenital Heart Disease AMERICAN JOURNAL OF CARDIOLOGY Donofrio, M. T., Levy, R. J., Schuette, J. J., Skurow-Todd, K., Sten, M., Stallings, C., Pike, J. I., Krishnan, A., Ratnayaka, K., Sinha, P., duPlessis, A. J., Downing, D. S., Fries, M. I., Berger, J. T. 2013; 111 (5): 737-747

  Abstract

  Improvements in fetal echocardiography have increased recognition of fetuses with congenital heart disease (CHD) that require specialized delivery room (DR) care. In this study, care protocols for these low-volume and high-risk deliveries were created. Elements included (1) diagnosis-specific DR care plans and algorithms, (2) a multidisciplinary team with expertise, (3) simulation, (4) checklists, and (5) debriefing. The purpose of this study was to assess the accuracy of fetal echocardiography to predict the need for specialized DR care and determine the effectiveness of the care protocols for the treatment of patients with critical CHD. Fetal and postnatal medical records and echocardiograms of fetuses with CHD assigned to an advanced level of care were reviewed. Safety and outcome variables were analyzed to determine care plan and algorithm efficacy. Thirty-four fetuses were identified: 12 delivered at Children's National Medical Center and 22 at the adult hospital. Diagnoses included hypoplastic left heart syndrome, aortic stenosis, d-transposition of the great arteries, tetralogy of Fallot with absent pulmonary valve, complex pulmonary atresia, arrhythmias, ectopia cordis, and conjoined twins. Delivery at Children's National Medical Center was associated with a shorter time to specialty care or intervention. Measures of physiologic stability and survival were similar. Need for specialized care was predicted in 84% of deliveries. For hypoplastic left heart syndrome, intervention was predicted in 10 of 11 deliveries and for d-transposition of the great arteries in 10 of 12 deliveries. Care algorithms addressed most DR events. Of the unanticipated events, none were unrecoverable. DR survival was 100%, and survival to discharge was 83%. In conclusion, fetal echocardiography predicted the need for specialized DR care in fetuses with critical CHD. Algorithm-driven protocols enable planning such that maternal and infant risk is minimized and outcomes are good.

  View details for DOI 10.1016/j.amjcard.2012.11.029

  View details for Web of Science ID 000315666600019

  View details for PubMedID 23291087

• Programmed Cell Death Is Impaired in the Developing Brain of <i>Fmr1</i> Mutants DEVELOPMENTAL NEUROSCIENCE Cheng, Y., Corbin, J. G., Levy, R. J. 2013; 35 (4): 347-358

  Abstract

  Fragile X syndrome (FXS), due to transcriptional silencing of fragile X mental retardation protein (FMRP), is characterized by excess synaptic connections and impaired dendrite maturation. Programmed cell death (PCD) is critical for synaptogenesis and elimination of aberrant neuronal connections in the developing brain; however, the role of FMRP in PCD is unknown. The aim of this work was to assess the intrinsic apoptosis pathway in the developing brain of Fmr1 mutants. To accomplish this, we evaluated two different Fmr1 mutant strains of 10-day-old male mice compared with appropriate controls. We performed immunohistochemistry for activated caspase-3 and TUNEL assays, quantified the number of neurons in neocortex and hippocampus, determined cytochrome c peroxidase activity, measured the amount of cytochrome c release from forebrain mitochondria, and assessed levels of key pro- and antiapoptotic mediators with immunoblot analysis. Both Fmr1 mutant strains demonstrated decreased apoptosis in neocortex, hippocampus, and basolateral amygdala, impaired cytochrome c and procaspase-9 release from mitochondria despite intact Bax translocation, increased expression of the antiapoptotic protein, BCL-xL, and increased number of neurons. Taken together, the data suggest that PCD is impaired due to increased BCL-xL expression and is associated with excess neurons in the developing brain of FMRP-deficient mice. It is possible that deficient PCD prevents neuron elimination and results in abnormal retention of developmentally transient neurons. Thus, defective PCD may contribute to the excess synaptic connections known to exist in Fmr1 mutants and could play a role in the behavioral phenotype of children with FXS.

  View details for DOI 10.1159/000353248

  View details for Web of Science ID 000323857000007

  View details for PubMedID 23900139

  View details for PubMedCentralID PMC5116766

• Glucose-6-Phosphate Dehydrogenase and NADPH Redox Regulates Cardiac Myocyte L-Type Calcium Channel Activity and Myocardial Contractile Function PLOS ONE Rawat, D. K., Hecker, P., Watanabe, M., Chettimada, S., Levy, R. J., Okada, T., Edwards, J. G., Gupte, S. A. 2012; 7 (10): e45365

  Abstract

  We recently demonstrated that a 17-ketosteroid, epiandrosterone, attenuates L-type Ca(2+) currents (I(Ca-L)) in cardiac myocytes and inhibits myocardial contractility. Because 17-ketosteroids are known to inhibit glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway, and to reduce intracellular NADPH levels, we hypothesized that inhibition of G6PD could be a novel signaling mechanism which inhibit I(Ca-L) and, therefore, cardiac contractile function. We tested this idea by examining myocardial function in isolated hearts and Ca(2+) channel activity in isolated cardiac myocytes. Myocardial function was tested in Langendorff perfused hearts and I(Ca-L) were recorded in the whole-cell patch configuration by applying double pulses from a holding potential of -80 mV and then normalized to the peak amplitudes of control currents. 6-Aminonicotinamide, a competitive inhibitor of G6PD, increased pCO(2) and decreased pH. Additionally, 6-aminonicotinamide inhibited G6PD activity, reduced NADPH levels, attenuated peak I(Ca-L) amplitudes, and decreased left ventricular developed pressure and ±dp/dt. Finally, dialyzing NADPH into cells from the patch pipette solution attenuated the suppression of I(Ca-L) by 6-aminonicotinamide. Likewise, in G6PD-deficient mice, G6PD insufficiency in the heart decreased GSH-to-GSSG ratio, superoxide, cholesterol and acetyl CoA. In these mice, M-mode echocardiographic findings showed increased diastolic volume and end-diastolic diameter without changes in the fraction shortening. Taken together, these findings suggest that inhibiting G6PD activity and reducing NADPH levels alters metabolism and leads to inhibition of L-type Ca(2+) channel activity. Notably, this pathway may be involved in modulating myocardial contractility under physiological and pathophysiological conditions during which the pentose phosphate pathway-derived NADPH redox is modulated (e.g., ischemia-reperfusion and heart failure).

  View details for DOI 10.1371/journal.pone.0045365

  View details for Web of Science ID 000309827300009

  View details for PubMedID 23071515

  View details for PubMedCentralID PMC3465299

• Two-dimensional speckle tracking imaging detects impaired myocardial performance in children with septic shock, not recognized by conventional echocardiography PEDIATRIC CRITICAL CARE MEDICINE Basu, S., Frank, L. H., Fenton, K. E., Sable, C. A., Levy, R. J., Berger, J. T. 2012; 13 (3): 259-264

  Abstract

  Sepsis is common in children and often results in cardiac dysfunction. Assessment of patients with sepsis-associated myocardial depression using ejection fraction and fractional shortening with conventional echocardiography is load dependent and often reveals cardiac dysfunction only after clinical deterioration has occurred. Speckle tracking imaging is a novel technology that can assess deformation and strain by tracking displacement of acoustic markers in the myocardium. We hypothesize that speckle tracking imaging will detect cardiac impairments during sepsis that are not appreciated by conventional echocardiography.Retrospective, observational study.A large, tertiary-care pediatric intensive care unit.Fifteen pediatric patients with septic shock, and 30 age- and gender-matched healthy controls.Transthoracic echocardiograms from subjects with septic shock (by American College of Chest Physicians/Society of Critical Care Medicine consensus criteria) and controls were evaluated. Speckle tracking imaging was used to obtain tissue displacement, velocity, strain, and strain rate in radial, longitudinal, and circumferential planes. Ejection fraction and fractional shortening were determined by conventional methods. Comparisons between groups were made using a paired t test.Compared to control subjects, children with septic shock demonstrated impaired myocardial performance as quantified by speckle tracking imaging. Significant differences were seen in circumferential and longitudinal strain (p < .001), strain rate (p < .05), radial displacement (p < .001), and rotational velocity and displacement (p < .01). There was no significant difference in ejection fraction and fractional shortening between septic patients and controls.Speckle tracking imaging detected a number of significantly impaired measures of ventricular performance in children with sepsis, not appreciated by conventional echocardiography. This technology may improve our understanding and identification of myocardial depression in the critically ill septic child.

  View details for DOI 10.1097/PCC.0b013e3182288445

  View details for Web of Science ID 000303984800013

  View details for PubMedID 21760563

• Acquired cytochrome C oxidase impairment in apheresis platelets during storage: a possible mechanism for depletion of metabolic adenosine triphosphate TRANSFUSION Diab, Y. A., Thomas, A., Luban, N. L. C., Wong, E. C. C., Wagner, S. J., Levy, R. J. 2012; 52 (5): 1024-1030

  Abstract

  Intracellular adenosine triphosphate (ATP) levels decline significantly during storage of platelet (PLT) products, in part due to PLT degranulation. However, metabolic ATP stores also become depleted during storage through an unclear mechanism. Since both anaerobic glycolysis and oxidative phosphorylation are important for PLT ATP production, it is possible that the reduction in metabolic ATP reflects impaired oxidative phosphorylation. To assess this, we evaluated the kinetic activity and protein expression of cytochrome C oxidase (CcOX) in stored apheresis PLTs.Apheresis PLTs were collected and stored with agitation at 22 ± 2°C for 7 days. In vitro measurements of PLT metabolic state, function, and activation were performed on Days 0, 2, 4, and 7 of storage. Total PLT ATP content, steady-state CcOX kinetic activity, and protein immunoblotting for CcOX Subunits I and IV were also performed using isolated PLT mitochondria from simultaneously collected samples.Intra-PLT ATP and steady-state PLT CcOX activity declined significantly and in a progressive manner throughout storage while steady-state levels of CcOX I and IV protein remained unchanged. Time-dependent decline in CcOX activity correlated with progressive ATP depletion over time.During storage of apheresis PLTs for 7 days, the parallel decline in CcOX function and intra-PLT ATP suggests development of an acquired impairment in PLT oxidative phosphorylation associated with perturbed ATP homeostasis in stored PLTs.

  View details for DOI 10.1111/j.1537-2995.2011.03446.x

  View details for Web of Science ID 000303876900014

  View details for PubMedID 22098205

• Neurodevelopmental Consequences of Sub-Clinical Carbon Monoxide Exposure in Newborn Mice PLOS ONE Cheng, Y., Thomas, A., Mardini, F., Bianchi, S. L., Tang, J. X., Peng, J., Wei, H., Eckenhoff, M. F., Eckenhoff, R. G., Levy, R. J. 2012; 7 (2): e32029

  Abstract

  Carbon monoxide (CO) exposure at high concentrations results in overt neurotoxicity. Exposure to low CO concentrations occurs commonly yet is usually sub-clinical. Infants are uniquely vulnerable to a variety of toxins, however, the effects of postnatal sub-clinical CO exposure on the developing brain are unknown. Apoptosis occurs normally within the brain during development and is critical for synaptogenesis. Here we demonstrate that brief, postnatal sub-clinical CO exposure inhibits developmental neuroapoptosis resulting in impaired learning, memory, and social behavior. Three hour exposure to 5 ppm or 100 ppm CO impaired cytochrome c release, caspase-3 activation, and apoptosis in neocortex and hippocampus of 10 day old CD-1 mice. CO increased NeuN protein, neuronal numbers, and resulted in megalencephaly. CO-exposed mice demonstrated impaired memory and learning and reduced socialization following exposure. Thus, CO-mediated inhibition of neuroapoptosis might represent an important etiology of acquired neurocognitive impairment and behavioral disorders in children.

  View details for DOI 10.1371/journal.pone.0032029

  View details for Web of Science ID 000302730900030

  View details for PubMedID 22348142

  View details for PubMedCentralID PMC3277503

• Hypoplastic Left Heart Syndrome With Intact Atrial Septum Sequelae of Left Atrial Hypertension In Utero JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Olivieri, L., Ratnayaka, K., Levy, R. J., Berger, J., Wessel, D., Donofrio, M. 2011; 57 (20): 1960

  View details for DOI 10.1016/j.jacc.2010.10.064

  View details for Web of Science ID 000290472300001

  View details for PubMedID 21565633

• Pentalogy of Cantrell with a Single-Ventricle Cardiac Defect: Collaborative Management of a Complex Disease PEDIATRIC CARDIOLOGY Marino, A. L., Levy, R. J., Berger, J. T., Donofrio, M. T. 2011; 32 (4): 498-502

  Abstract

  We present a case of ectopia cordis with a complex single-ventricle congenital heart defect in association with pentalogy of Cantrell. Management by a skilled multidisciplinary team was critical for patient survival. Early fetal diagnosis and the use of advanced imaging techniques allowed adequate time for planning and identified critical anatomic details. Preserving the heart's natural covering, performing cardiac surgery without cardiopulmonary bypass, and using catheter intervention decreased the risk to the patient. Complete coverage of the defect was achieved using skin generated with tissue expanders. This case illustrates the importance of collaboration when caring for infants with critical, high-risk disease and highlights the increased potential for survival with complex ectopia cordis in the current medical era.

  View details for DOI 10.1007/s00246-010-9867-6

  View details for Web of Science ID 000288557900019

  View details for PubMedID 21210095

• Glutamine Restores Myocardial Cytochrome <i>c</i> Oxidase Activity and Improves Cardiac Function During Experimental Sepsis JOURNAL OF PARENTERAL AND ENTERAL NUTRITION Groening, P., Huang, Z., La Gamma, E., Levy, R. J. 2011; 35 (2): 249-254

  Abstract

  Cardiac dysfunction occurs commonly in sepsis. Impaired mitochondrial function is a potential cause of sepsis-associated myocardial depression. Cytochrome oxidase (COX), the terminal oxidase of the electron transport chain, is inhibited in the septic heart. Glutamine (GLN) increases Krebs cycle intermediates and supports oxidative phosphorylation. Exogenous GLN has been shown to restore myocardial adenosine triphosphate levels and cardiac function following ischemia-reperfusion injury. The authors hypothesize that exogenous GLN will abrogate sepsis-induced myocardial COX inhibition and improve sepsis-associated myocardial depression.Under general anesthesia, male Sprague-Dawley rats underwent cecal ligation and double puncture (CLP) or sham operation. At the time of operation, rats underwent intraperitoneal injection of either GLN (0.75 g/kg) or an equal volume of saline. Twenty-four hours after the procedure, animals were killed, cardiac ventricles harvested, and mitochondria isolated. Steady-state COX kinetic activity was measured and normalized to citrate synthase activity. Steady-state levels of COX subunit I protein were determined with immunoblot analysis. Cardiac function was assessed using an isolated rat heart preparation. Five animals per group were evaluated. Significance was determined with analysis of variance and post hoc Tukey test.CLP significantly decreased myocardial COX activity, oxygen consumption, left ventricular pressure (LVP), and pressure developed during isovolumic contraction (+dP/dt) and relaxation (-dP/dt). GLN restored COX activity to sham levels, significantly increased myocardial oxygen extraction and consumption, increased LVP toward sham values, and increased ±dP/dt by >30% following CLP.The beneficial effects of GLN therapy during sepsis may be in part due to restoration of oxidative phosphorylation and abrogation of sepsis-associated myocardial depression.

  View details for DOI 10.1177/0148607110383040

  View details for Web of Science ID 000289632900014

  View details for PubMedID 21378254

• Clinical Effects and Lethal and Forensic Aspects of Propofol JOURNAL OF FORENSIC SCIENCES Levy, R. J. 2011; 56: S142-S147

  Abstract

  Propofol is a potent intravenous anesthetic agent that rapidly induces sedation and unconsciousness. The potential for propofol dependency, recreational use, and abuse has only recently been recognized, and several cases of accidental overdose and suicide have emerged. In addition, the first documented case of murder using propofol was reported a few months ago, and a high profile case of suspected homicide with propofol is currently under investigation. A number of analytical methods have been employed to detect and quantify propofol concentrations in biological specimens. The reported propofol-related deaths and postmortem blood and tissue levels are reviewed. Importantly, limitations of propofol detection are discussed, and future considerations are presented. Because propofol has the potential for diversion with lethal consequences, the forensic scientist must have a basic understanding of its clinical indications and uses, pharmacologic properties, and detection methods. In addition, medical institutions should develop systems to prevent and detect diversion of this potential drug of abuse.

  View details for DOI 10.1111/j.1556-4029.2010.01583.x

  View details for Web of Science ID 000285840200022

  View details for PubMedID 20950316

  View details for PubMedCentralID PMC3970210

• Mitochondrial Dysfunction and Resuscitation in Sepsis CRITICAL CARE CLINICS Ruggieri, A. J., Levy, R. J., Deutschman, C. S. 2010; 26 (3): 567-+

  Abstract

  Sepsis is among the most common causes of death in patients in intensive care units in North America and Europe. In the United States, it accounts for upwards of 250,000 deaths each year. Investigations into the pathobiology of sepsis have most recently focused on common cellular and subcellular processes. One possibility would be a defect in the production of energy, which translates to an abnormality in the production of adenosine triphosphate and therefore in the function of mitochondria. This article presents a clear role for mitochondrial dysfunction in the pathogenesis and pathophysiology of sepsis. What is less clear is the teleology underlying this response. Prolonged mitochondrial dysfunction and impaired biogenesis clearly are detrimental. However, early inhibition of mitochondrial function may be adaptive.

  View details for DOI 10.1016/j.ccc.2010.04.007

  View details for Web of Science ID 000280977500012

  View details for PubMedID 20643307

  View details for PubMedCentralID PMC2908601

• Detection of Carbon Monoxide During Routine Anesthetics in Infants and Children ANESTHESIA AND ANALGESIA Levy, R. J., Nasr, V. G., Rivera, O., Roberts, R., Slack, M., Kanter, J. P., Ratnayaka, K., Kaplan, R. F., McGowan, F. X. 2010; 110 (3): 747-753

  Abstract

  Carbon monoxide (CO) can be produced in the anesthesia circuit when inhaled anesthetics are degraded by dried carbon dioxide absorbent and exhaled CO can potentially be rebreathed during low-flow anesthesia. Exposure to low concentrations of CO (12.5 ppm) can cause neurotoxicity in the developing brain and may lead to neurodevelopmental impairment. In this study, we aimed to quantify the amount of CO present within a circle system breathing circuit during general endotracheal anesthesia in infants and children with fresh strong metal alkali carbon dioxide absorbent and define the variables associated with the levels detected.Fifteen infants and children (aged 4 months to 8 years) undergoing mask induction followed by general endotracheal anesthesia were evaluated in this observational study. CO was measured in real time from the inspiratory limb of the anesthesia circuit every 5 minutes for 1 hour during general anesthesia. Carboxyhemoglobin (COHb) levels were measured at the 1-hour time point and compared with baseline.CO was detected in all patients older than 2 years (0-18 ppm, mean 3.7 +/- 4.8 ppm) and rarely detected in patients younger than 2 years (0-2 ppm, mean 0.2 +/- 0.6 ppm). Only the relationship between CO concentration and fresh gas flow to minute ventilation ratio (FGF:(.)VE) remained significant after adjustment in longitudinal regression analysis (P < 0.001). Although not powered to determine such a relationship, CO levels were weakly associated with the use of desflurane and female sex. There was no significant association between CO concentration and anesthetic concentration. Baseline COHb levels were higher in children younger than 2 years and decreased significantly at the 1-hour time point compared with baseline and children older than 2 years. However, COHb levels increased significantly from baseline in a predictable manner consistent with CO exposure in children older than 2 years. FGF:(.)VE correlated significantly with change in COHb using simple linear regression (r = 0.62; P < 0.02).CO was detected routinely during general anesthesia in infants and children when FGF:(.)VE was <1. Peak CO levels measured in the anesthesia breathing circuit were in the range thought to impair the developing brain. Further study is required to identify the source of CO detected (CO produced by degradation of volatile anesthetic versus rebreathing CO from endogenous sources or both). However, these findings suggest that avoidance of low-flow anesthesia will prevent rebreathing of exhaled CO, and use of carbon dioxide absorbents that lack strong metal hydroxide could limit inspired CO if detection was attributable to degradation of volatile anesthetic.

  View details for DOI 10.1213/ANE.0b013e3181cc4b9f

  View details for Web of Science ID 000275137200024

  View details for PubMedID 20185653

• Caffeine restores myocardial cytochrome oxidase activity and improves cardiac function during sepsis CRITICAL CARE MEDICINE Verma, R., Huang, Z., Deutschman, C. S., Levy, R. J. 2009; 37 (4): 1397-1402

  Abstract

  Impaired mitochondrial function is a potential cause of sepsis-associated myocardial depression. Cytochrome oxidase (CcOX), the terminal oxidase of the electron transport chain, is inhibited in the septic heart. Caffeine increases CcOX activity by increasing cyclic adenosine monophosphate and protein kinase A activity. We hypothesized that caffeine will restore myocardial CcOX activity, increase cardiac function, and improve survival during sepsis.Prospective randomized controlled study.University hospital-based laboratory.One hundred twenty Sprague-Dawley male rats.Sprague-Dawley male rats underwent cecal ligation and puncture (CLP) or sham operation. At 24 and 48 hours, rats underwent intraperitoneal injection of either caffeine (7.5 mg/kg, the equivalent of 1-1.5 cups of coffee) or equal volume of saline.One hour following the 48-hour injection, steady-state CcOX kinetic activity was measured in isolated mitochondria and normalized to citrate synthase activity. Cardiac function was assessed using an isolated rat heart preparation and survival was tracked to 96 hours. CLP significantly decreased myocardial CcOX activity, oxygen consumption, left ventricular pressure, and pressure developed during isovolumic contraction (+dP/dt) and relaxation (-dP/dt). Caffeine restored CcOX activity and increased left ventricular pressure and +/-dP/dt toward sham values following CLP. Survival significantly improved following CLP in caffeine-injected animals compared with saline injection.Caffeine may be a novel therapy to treat sepsis-associated myocardial depression.

  View details for DOI 10.1097/CCM.0b013e31819cecd6

  View details for Web of Science ID 000264699000031

  View details for PubMedID 19242342

  View details for PubMedCentralID PMC3970220

• Exogenous cytochrome c restores myocardial cytochrome oxidase activity into the late phase of sepsis SHOCK Piel, D. A., Deutschman, C. S., Levy, R. J. 2008; 29 (5): 612-616

  Abstract

  Mitochondrial dysfunction is thought to play a role in the pathogenesis of a variety of disease states, including sepsis. An acquired defect in oxidative phosphorylation potentially causes sepsis-induced organ dysfunction. Cytochrome oxidase (CcOX), the terminal oxidase of the respiratory chain, is competitively inhibited early in sepsis and progresses, becoming noncompetitive during the late phase. We have previously demonstrated that exogenous cytochrome c can overcome myocardial CcOX competitive inhibition and improve cardiac function during murine sepsis at the 24-h point. Here, we evaluate the effect of exogenous cytochrome c on CcOX activity and survival in mice at the later time points. Exogenous cytochrome c (800 microg) or saline was intravenously injected 24 h after cecal ligation and puncture (CLP) or sham operation. Steady-state mitochondrial cytochrome c levels and heme c content increased significantly 48 h post-CLP and remained elevated at 72 h in cytochrome c-injected mice compared with saline injection. Cecal ligation and puncture inhibited CcOX at 48 h in saline-injected mice. However, cytochrome c injection abrogated this inhibition and restored CcOX kinetic activity to sham values at 48 h. Survival after CLP to 96 h after cytochrome c injection approached 50% compared with only 15% after saline injection. Thus, a single injection of exogenous cytochrome c 24 h post-CLP repletes mitochondrial substrate levels for up to 72 h, restores myocardial COX activity, and significantly improves survival.

  View details for DOI 10.1097/SHK.0b013e318157e962

  View details for Web of Science ID 000255210900012

  View details for PubMedID 18414235

  View details for PubMedCentralID PMC3970215

• Critical heart disease in the neonate: Presentation and outcome at a tertiary care center PEDIATRIC CRITICAL CARE MEDICINE Dorfman, A. T., Marino, B. S., Wernovsky, G., Tabbutt, S., Ravishankar, C., Godinez, R. I., Priestley, M., Dodds, K. M., Rychik, J., Gruber, P. J., Gaynor, J., Levy, R. J., Nicolson, S. C., Montenegro, L. M., Spray, T. L., Dominguez, T. E. 2008; 9 (2): 193-202

  Abstract

  To define the modes of presentation, incidence of major organ dysfunction, predictors of hospital mortality, and adverse outcomes in neonates with critical heart disease admitted to a tertiary care center.Retrospective chart review.A tertiary care pediatric cardiac intensive care unit and neonatal intensive care unit.The medical records for all neonates (< or = 30 days of age) with heart disease admitted to the cardiac intensive care unit or neonatal intensive care unit between October 1, 2002, and September 30, 2003, were reviewed.None.A total of 190 neonates met inclusion criteria during this 1-yr period, of which 146 (77%) had at least one surgical procedure. Single ventricle heart disease was present in 42%. The most common mode of presentation was following a prenatal diagnosis (53%), followed by diagnosis in the newborn nursery (38%) and diagnosis after newborn hospital discharge (8%). The most common presenting findings in the newborn nursery were isolated murmur (38%) or cyanosis (32%), while circulatory collapse (38%) was the most common presentation after discharge. For the entire study cohort, 13% had a known genetic syndrome, 23% had a major noncardiac congenital anomaly, and 16% weighed < 2.5 kg. The hospital mortality for the entire cohort was 7.4%. Risk factors associated with an increased risk of hospital mortality included younger age at admission, higher number of cardiopulmonary bypass runs, and need for postoperative cardiopulmonary resuscitation. Total hospital length of stay was > 1 month in 17% of neonates.In patients with complex congenital heart disease, including nearly half with single ventricle heart disease, neonatal hospital mortality was 7%. These patients have a high frequency of multiple congenital anomalies, genetic syndromes, low birth weight, and prolonged length of stay.

  View details for DOI 10.1097/PCC.0b013e318166eda5

  View details for Web of Science ID 000254033800008

  View details for PubMedID 18477933

• Chronic hypoxemia increases ventricular brain natriuretic peptide precursors in neonatal swine ANNALS OF THORACIC SURGERY Khan, A. R., Birbach, M., Cohen, M. S., Ittenbach, R. F., Spray, T. L., Levy, R. J., Gaynor, J. 2008; 85 (2): 618-623

  Abstract

  Circulating levels of atrial natriuretic peptide and brain natriuretic peptide (BNP) are elevated in patients with cyanotic congenital heart disease and associated with the severity of ventricular dysfunction. We evaluated the effect of chronic hypoxemia on left ventricle pro-atrial natriuretic peptide and pro-BNP, the cytoplasmic precursors of the plasma hormones.Forty newborn piglets were randomized to placement of a pulmonary artery to left atrium shunt to create hypoxemia or sham thoracotomy. Animals were studied at 1 or 2 weeks after the procedure (four groups, n = 10 per group). Arterial oxygen tension and hematocrit were obtained. Left ventricular shortening fraction was measured by echocardiography. Left ventricular tissue was harvested and cytoplasm was extracted. Pro-BNP levels were determined by Western blot analysis. Pro-atrial natriuretic peptide levels were determined using enzyme-linked immunosorbent assay.Significant differences among treatment groups were observed for arterial oxygen tension (p < 0.001) and hematocrit (p < 0.001). Pairwise comparisons indicated lower arterial oxygen tension and higher hematocrit for hypoxemic piglets compared with control piglets at 1 and 2 weeks. Left ventricular shortening fraction was not decreased in the hypoxemic animals at any time (p = 0.638). Left ventricular pro-atrial natriuretic peptide decreased in hypoxemic piglets (p = 0.029), whereas left ventricular pro-BNP increased in hypoxemic piglets at 2 weeks (p = 0.002).Chronic hypoxemia alone, even in the absence of cardiac dysfunction, is sufficient to increase ventricular levels of pro-BNP. This finding may have implications for the interpretation of BNP levels in the clinical management of patients with cyanotic congenital heart disease.

  View details for DOI 10.1016/j.athoracsur.2007.08.041

  View details for Web of Science ID 000252664900042

  View details for PubMedID 18222277

• Vascular superoxide and hydrogen peroxide production and oxidative stress resistance in two closely related rodent species with disparate longevity AGING CELL Csiszar, A., Labinskyy, N., Zhao, X., Hu, F., Serpillon, S., Huang, Z., Ballabh, P., Levy, R. J., Hintze, T. H., Wolin, M. S., Austad, S. N., Podlutsky, A., Ungvari, Z. 2007; 6 (6): 783-797

  Abstract

  Vascular aging is characterized by increased oxidative stress, impaired nitric oxide (NO) bioavailability and enhanced apoptotic cell death. The oxidative stress hypothesis of aging predicts that vascular cells of long-lived species exhibit lower production of reactive oxygen species (ROS) and/or superior resistance to oxidative stress. We tested this hypothesis using two taxonomically related rodents, the white-footed mouse (Peromyscus leucopus) and the house mouse (Mus musculus), that show a more than twofold difference in maximum lifespan potential (MLSP = 8 and 3.5 years, respectively). We compared interspecies differences in endothelial superoxide (O2-) and hydrogen peroxide (H2O2) production, NAD(P)H oxidase activity, mitochondrial ROS generation, expression of pro- and antioxidant enzymes, NO production, and resistance to oxidative stress-induced apoptosis. In aortas of P. leucopus, NAD(P)H oxidase expression and activity, endothelial and H2O2 production, and ROS generation by mitochondria were less than in mouse vessels. In P. leucopus, there was a more abundant expression of catalase, glutathione peroxidase 1 and hemeoxygenase-1, whereas expression of Cu/Zn-SOD and Mn-SOD was similar in both species. NO production and endothelial nitric oxide synthase expression was greater in P. leucopus. In mouse aortas, treatment with oxidized low-density lipoprotein (oxLDL) elicited substantial oxidative stress, endothelial dysfunction and endothelial apoptosis (assessed by TUNEL assay, DNA fragmentation and caspase 3 activity assays). According to our prediction, vessels of P. leucopus were more resistant to the proapoptotic effects of oxidative stressors (oxLDL and H2O2). Primary fibroblasts from P. leucopus also exhibited less H2O2-induced DNA damage (comet assay) than mouse cells. Thus, increased lifespan potential in P. leucopus is associated with a decreased cellular ROS generation and increased oxidative stress resistance, which accords with the prediction of the oxidative stress hypothesis of aging.

  View details for DOI 10.1111/j.1474-9726.2007.00339.x

  View details for Web of Science ID 000250938400008

  View details for PubMedID 17925005

• Cytochrome <i>c</i> oxidase dysfunction in sepsis CRITICAL CARE MEDICINE Levy, R. J., Deutschman, C. S. 2007; 35 (9): S468-S475

  Abstract

  Sepsis, the principal cause of death in critically ill patients, is associated with impaired oxygen extraction by tissues. One possible explanation is the development of mitochondrial dysfunction and ineffective oxygen utilization. This abnormality has been termed cytopathic hypoxia. This may be caused by an abnormality in the transport of electrons down the cytochrome chain on the mitochondrial inner membrane. In this article we review our studies on abnormalities in the function of complex IV (cytochrome oxidase), the final electron acceptor in this chain. In addition, we provide evidence that administration of cytochrome c may overcome these abnormalities and provide a novel therapeutic alternative.

  View details for DOI 10.1097/01.CCM.0000278604.93569.27

  View details for Web of Science ID 000208399900007

  View details for PubMedID 17713395

• Myocardial cytochrome oxidase activity is decreased following carbon monoxide exposure BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE Iheagwara, K. N., Thom, S. R., Deutschman, C. S., Levy, R. J. 2007; 1772 (9): 1112-1116

  Abstract

  Carbon monoxide (CO) inhalation often leads to cardiac dysfunction, dysrhythmias, ischemia, infarction, and death. However, the underlying mechanism of CO toxicity is poorly understood. We hypothesize that inhaled CO interrupts myocardial oxidative phosphorylation by decreasing the activity of myocardial cytochrome oxidase (CcOX), the terminal oxidase of the electron transport chain. Male C57Bl6 mice were exposed to either 1000 ppm (0.1%) CO or air for 3 h. Cardiac ventricles were harvested and mitochondria were isolated. CcOX kinetics and heme aa(3) content were measured. V(max), K(m), and turnover number were determined. Levels of CcOX subunit I message and protein were evaluated. Carboxyhemoglobin (COHb) levels were measured and tissue hypoxia was assessed with immunohistochemistry for pimonidazole hydrochloride. CO significantly decreased myocardial CcOX activity and V(max) without altering K(m). Heme aa(3) content and CcOX I protein levels significantly decreased following CO exposure while enzyme turnover number and CcOX I mRNA levels remained unchanged. CO exposure increased COHb levels without evidence of tissue hypoxia as compared to sham and hypoxic controls. Decreased CcOX activity following CO inhalation was likely due to decreased heme aa(3) and CcOX subunit I content. Importantly, myocardial CcOX impairment could underlie CO induced cardiac dysfunction.

  View details for DOI 10.1016/j.bbadis.2007.06.002

  View details for Web of Science ID 000249839200010

  View details for PubMedID 17628447

  View details for PubMedCentralID PMC2045065

• Mitochondrial resuscitation with exogenous cytochrome c in the septic heart CRITICAL CARE MEDICINE Piel, D. A., Gruber, P. J., Weinheimer, C. J., Courtois, M. R., Robertson, C. M., Coopersmith, C. M., Deutschman, C. S., Levy, R. J. 2007; 35 (9): 2120-2127

  Abstract

  Mitochondrial dysfunction may play a role in the pathogenesis of sepsis-induced organ dysfunction. Respiratory-chain deficiencies that occur in sepsis, however, have never been shown to cause organ failure or to be reversible. Cytochrome oxidase uses electrons donated by its substrate, cytochrome c, to reduce oxygen to H2O. In the septic heart, cytochrome oxidase is competitively inhibited. We hypothesized that cytochrome oxidase inhibition coupled with reduced substrate availability is a reversible cause of sepsis-associated myocardial depression.Prospective observational study aimed to overcome myocardial cytochrome oxidase inhibition with excess cytochrome c and improve cardiac function.University hospital-based laboratory.Seventy-five C57Bl6 male mice.Mice underwent cecal ligation and double puncture, sham operation, or no operation. Exogenous cytochrome c or an equal volume of saline was intravenously injected at the 24-hr time point. All animals were evaluated 30 mins after injection.Exogenous cytochrome c readily repleted cardiac mitochondria with supranormal levels of substrate (>1.6 times baseline), restored heme c content, and increased cytochrome oxidase kinetic activity. This increased left ventricular pressure and increased pressure development during isovolumic contraction (dP/dtmax) and relaxation (dP/dtmin) by >45% compared with saline injection.Impaired oxidative phosphorylation is a cause of sepsis-associated myocardial depression, and mitochondrial resuscitation with exogenous cytochrome c overcomes cytochrome oxidase inhibition and improves cardiac function.

  View details for DOI 10.1097/01.CCM.0000278914.85340.FE

  View details for Web of Science ID 000249038700015

  View details for PubMedID 17855825

• Mitochondrial dysfunction, bioenergetic impairment, and metabolic down-regulation in sepsis SHOCK Levy, R. J. 2007; 28 (1): 24-28

  Abstract

  Mitochondrial dysfunction is thought to play an important role in the pathogenesis of many different disease states. It has been proposed that an acquired defect in oxidative phosphorylation prevents cells from using molecular oxygen for adenosine triphosphate production and potentially causes sepsis-induced organ dysfunction. This concept, termed cytopathic hypoxia, however, has been difficult to prove because impaired oxidative phosphorylation has never been shown to cause sepsis-induced organ failure or to be a reversible phenomenon. Presented here is are view of oxidative phosphorylation, evidence of defective electron-transport-chain function in the heart and other organ systems during sepsis, and support for a link between mitochondrial dysfunction and pathologic metabolic down-regulation.

  View details for DOI 10.1097/01.shk.0000235089.30550.2d

  View details for Web of Science ID 000247832600004

  View details for PubMedID 17483747

• Deficient mitochondrial biogenesis in critical illness: Cengause, effect, or epiphenomenon? CRITICAL CARE Levy, R. J., Deutschman, C. S. 2007; 11 (4): 158

  Abstract

  Recent studies indicate that mitochondrial dysfunction plays a role in the pathogenesis of a number of disease states. The importance of these organelles in shock and multiple organ dysfunction is of particular interest to those caring for the critically ill. Mitochondria have their own unique DNA (mtDNA) that encodes 13 essential subunits of electron transport chain enzymes, two ribosomal RNAs and 22 transfer RNAs. Importantly, mtDNA is especially susceptible to deletions, rearrangements and mutations because it is not bound by histones and lacks the extensive repair machinery present in the nucleus. The study by Côté et al. in this issue of Critical Care examines changes in mtDNA in critically ill patients. The results support further investigation into the role of mtDNA in the critically ill.

  View details for DOI 10.1186/cc6098

  View details for Web of Science ID 000250469000036

  View details for PubMedID 17764588

  View details for PubMedCentralID PMC2206497

• Clinical implications of mitochondrial dysfunction ANESTHESIOLOGY Muravchick, S., Levy, R. J. 2006; 105 (4): 819-837

  Abstract

  Mitochondria produce metabolic energy, serve as biosensors for oxidative stress, and eventually become effector organelles for cell death through apoptosis. The extent to which these manifold mitochondrial functions are altered by previously unrecognized actions of anesthetic agents seems to explain and link a wide variety of perioperative phenomena that are currently of interest to anesthesiologists from both a clinical and a scientific perspective. In addition, many surgical patients may be at increased perioperative risk because of inherited or acquired mitochondrial dysfunction leading to increased oxidative stress. This review summarizes the essential aspects of the bioenergetic process, presents current knowledge regarding the effects of anesthetics on mitochondrial function and the extent to which mitochondrial state determines anesthetic requirement and potential anesthetic toxicity, and considers some of the many implications that our knowledge of mitochondrial dysfunction poses for anesthetic management and perioperative medicine.

  View details for DOI 10.1097/00000542-200610000-00029

  View details for Web of Science ID 000240932400028

  View details for PubMedID 17006082

• A child with anterior mediastinal mass supported with venoarterial extracorporeal membrane oxygenation PEDIATRIC CRITICAL CARE MEDICINE Frey, T. K. E., Chopra, A., Lin, R. J., Levy, R. J., Gruber, P., Rheingold, S. R., Hoehn, K. 2006; 7 (5): 479-481

  Abstract

  To demonstrate the utility of rescue with veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and to demonstrate the feasibility of administration of chemotherapy during VA-ECMO in a child with an anterior mediastinal mass.Case report.Large, tertiary care, pediatric intensive care unit.One patient with cardiopulmonary collapse in the setting of a new diagnosis of an anterior mediastinal mass.Cardiopulmonary support with VA-ECMO; administration of chemotherapy during VA-ECMO.Successful rescue with VA-ECMO and successful chemotherapy while on VA-ECMO.VA-ECMO can be successfully used to support patients with cardiopulmonary failure during initial diagnosis of an anterior mediastinal mass. In addition, we have demonstrated that successful chemotherapy can be administered while the patient is supported on VA-ECMO.

  View details for DOI 10.1097/01.PCC.0000235247.10880.F8

  View details for Web of Science ID 000241390500013

  View details for PubMedID 16885791

• Evidence of myocardial hibernation in the septic heart CRITICAL CARE MEDICINE Levy, R. J., Piel, D. A., Acton, P. D., Zhou, R., Ferrari, V. A., Karp, J. S., Deutschman, C. S. 2005; 33 (12): 2752-2756

  Abstract

  Myocardial hibernation is an adaptive response to ischemia and hypoxia. Hibernating cardiomyocytes are reversibly hypocontractile and demonstrate characteristic metabolic and ultrastructural changes. These include a switch in primary substrate utilization from fatty acids to glucose, up-regulation of the myocardial specific glucose transporters (GLUT1 and GLUT4), and glycogen deposition within and between cardiomyocytes. We hypothesized that myocardial hibernation may underlie sepsis-associated myocardial depression.Prospective observational study aimed at identifying the characteristic changes of hibernation in the septic heart.University hospital-based laboratory.Forty-three C57Bl6 male mice.Mice underwent cecal ligation and double puncture, sham operation, or no operation and were evaluated 48 hrs after the procedure.Using novel, clinically relevant technology such as magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography imaging, we found septic mice to have diminished cardiac performance, increased myocardial glucose uptake, increased steady-state levels of myocardial GLUT4, and increased deposits of glycogen, recapitulating the changes during hibernation. Importantly, these changes occurred in the setting of preserved arterial oxygen tension and myocardial perfusion.Sepsis-associated cardiac dysfunction may reflect hibernation. Furthermore, such down-regulation of cellular function may underlie sepsis-induced dysfunction in other organ systems.

  View details for DOI 10.1097/01.CCM.0000189943.60945.77

  View details for Web of Science ID 000234423700005

  View details for PubMedID 16352955

• Evaluation of tissue saturation as a noninvasive measure of mixed venous saturation in children. Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies Levy, R. J., Stern, W. B., Minger, K. I., Montenegro, L. M., Ravishankar, C., Rome, J. J., Nicolson, S. C., Jobes, D. R. 2005; 6 (6): 671-5

  Abstract

  Mixed venous saturation (S & OV0456;o2) is an important measurement that helps guide the care of critically ill patients. Invasive S & OV0456;o2 assessment in infants and children is often avoided because of the inherent risks. A noninvasive tissue saturation (S to 2) monitor has recently been developed that uses near-infrared spectroscopy to measure oxyhemoglobin saturation in muscle. In adult and animal studies, S to 2 correlated with oxygen delivery and S & OV0456;o2. There has been no evaluation in pediatric patients.To evaluate tissue saturation as a noninvasive measure of mixed venous saturation in children.A prospective observational study.Catheterization laboratory in a tertiary care children's medical center.We studied 98 children (49 without intracardiac mixing and 49 with intracardiac mixing)

  View details for DOI 10.1097/01.pcc.0000185488.44719.b0

  View details for PubMedID 16276334

• Chronic hypoxemia increases myocardial cytochrome oxidase JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Piel, D. A., Khan, A. R., Waibel, R., Birbach, M., Cohen, M. S., Spray, T. L., Deutschman, C. S., Gaynor, J. W., Levy, R. J. 2005; 130 (4): 1101-1106

  Abstract

  Cyanotic patients have potentially decreased tissue oxygen tension. Cytochrome oxidase catalyzes the reduction of oxygen and is integral to adenosine triphosphate production. Cytochrome oxidase subunit I, the active site, is encoded by mitochondrial DNA. Using a newborn swine model of chronic hypoxemia, we evaluated ventricular cytochrome oxidase subunit I mRNA and protein expression and assessed cytochrome oxidase activity.Thirty-two newborn piglets underwent thoracotomy and placement of a pulmonary artery-to-left atrium shunt or sham operation. Two weeks later, partial pressure of arterial oxygen, hematocrit, and left ventricular shortening fraction values were compared with baseline values. Northern blot hybridization and protein immunoblotting for ventricular cytochrome oxidase subunit I were performed. Cytochrome oxidase kinetic activity was measured. Heme a,a3 content and turnover number were determined. Significance was assessed with a t test.Baseline partial pressure of arterial oxygen and hematocrit values were similar. Hypoxemic piglets had a lower partial pressure of arterial oxygen of 38 +/- 10 mm Hg (P < .001) and higher hematocrit value of 31.4% +/- 2.9% (P < .001) compared with a partial pressure of arterial oxygen of 140 +/- 47 mm Hg and hematocrit value of 24.6% +/- 3.9% after the sham operation. Baseline and postprocedure left ventricular shortening fraction were similar within and between groups. Chronic hypoxemia increased right ventricular and left ventricular cytochrome oxidase I mRNA and protein by more than 1.4-fold. Cytochrome oxidase activity increased significantly in hypoxemia by 2.5-fold compared with that seen after the sham operation. Heme a,a3 content and turnover number increased by 1.5-fold during hypoxemia.Chronic hypoxemia increases cytochrome oxidase I message, protein expression, and activity. The increase in kinetics was due to increased enzyme content and catalytic activity. This is a possible adaptive mechanism that might preserve organ function during chronic hypoxemia.

  View details for DOI 10.1016/j.jtcvs.2005.06.030

  View details for Web of Science ID 000232544000023

  View details for PubMedID 16214526

• Glutamine and heat shock proteins: One more approach to lung injury CRITICAL CARE MEDICINE Deutschman, C. S., Levy, R. J., Weiss, Y. G. 2005; 33 (6): 1422-1424

  View details for DOI 10.1097/01.CCM.0000167072.03551.61

  View details for Web of Science ID 000230064100037

  View details for PubMedID 15942367

• An evaluation of a noninvasive cardiac output measurement using partial carbon dioxide rebreathing in children ANESTHESIA AND ANALGESIA Levy, R. J., Chiavacci, R. M., Nicolson, S. C., Rome, J. J., Lin, R. J., Helfaer, M. A., Nadkarni, V. M. 2004; 99 (6): 1642-1647

  Abstract

  Cardiac output (CO) is an important hemodynamic measure that helps to guide the therapy of critically ill patients. Invasive CO assessment in infants and children is often avoided because of the inherent risks. A noninvasive CO monitor that uses partial rebreathing has been recently developed to determine CO via the Fick principle for carbon dioxide. There have been no clinical studies confirming its accuracy in pediatric patients. This is a prospective observational study of 37 children <12 yr of age who underwent cardiac catheterization. Under general anesthesia via an endotracheal tube without a leak, we made multiple CO measurements using thermodilution and compared them with noninvasively determined CO measurements. Paired measurements were analyzed for bias, precision, and correlation via Bland-Altman plot and linear regression. Noninvasive measurements showed a linear correlation with thermodilution CO assessment with an r value of 0.83 (P < 0.03). Bland-Altman analysis yielded a bias of -0.27 L/min and a precision +/-1.49 L/min. Cardiac index measurements demonstrated a decreased r value of 0.67 (P = 0.15) and a bias of -0.18 L . min(-1) . m(-2) and precision of +/-2.13 L . min(-1) . m(-2). Differences between partial rebreathing measurements and thermodilution measurements were largest in children with a body surface area of 0.6 m(2) body surface area and >300 mL tidal volume.

  View details for DOI 10.1213/01.ANE.0000136952.85278.99

  View details for Web of Science ID 000225341600013

  View details for PubMedID 15562047

• Evaluating myocardial depression in sepsis SHOCK Levy, R. J., Deutschman, C. S. 2004; 22 (1): 1-10

  View details for DOI 10.1097/01.shk.0000129198.53836.15

  View details for Web of Science ID 000222150100001

  View details for PubMedID 15201694

• Competitive and noncompetitive inhibition of myocardial cytochrome C oxidase in sepsis SHOCK Levy, R. J., Vijayasarathy, C., Raj, N. R., Avadhani, N. G., Deutschman, C. S. 2004; 21 (2): 110-114

  Abstract

  Sepsis is the most common cause of death in intensive care units worldwide. The basic pathophysiologic defect in sepsis, causing functional abnormalities in many organ systems, remains elusive. One potential cause is disruption of oxidative phosphorylation in mitochondria. Here, we report that oxidation of cytochrome c by myocardial cytochrome c oxidase, the terminal oxidase in the electron transport chain, is competitively inhibited early in experimental sepsis (cecal ligation with single or double 23-gauge puncture) in mice. In severe sepsis (cecal ligation and double puncture, 75% mortality at 48 h), inhibition becomes noncompetitive by 48 h. The development of noncompetitive inhibition is associated with a decrease in heme a,a3 content, which is the key active site in the functional subunit (I) and catalyzes the reduction of molecular oxygen. In addition, there are persistently decreased steady-state levels of subunit I mRNA and protein after cecal ligation and double puncture. Both loss of heme and loss of subunit I could explain the observed irreversible inhibition of cytochrome c oxidase. Noncompetitive inhibition of cytochrome c oxidase may interrupt oxidative phosphorylation, leading to sepsis-associated cardiac depression. Importantly, this abnormality may underlie sepsis-associated dysfunction in other organ systems.

  View details for DOI 10.1097/01.shk.0000108400.56565.ab

  View details for Web of Science ID 000188392300003

  View details for PubMedID 14752282

• Pediatric airway issues CRITICAL CARE CLINICS Levy, R. J., Helfaer, M. A. 2000; 16 (3): 489-+

  Abstract

  Airway management in the pediatric patient requires an understanding and knowledge of the differences and characteristics unique to the child and infant. New and exciting techniques are currently being explored and developed for management of the pediatric airway. Technology in the area of imaging has allowed clinicians to better visualize the airway and aberrations of it. Presently, there are many different modes and routes of ventilation and oxygenation that are being applied to the pediatric patient for different disease states. Work continues to probe for methods and ways that will allow us to take care of infants and children better and to provide the safest and most effective means of delivering that care. No doubt, there will be more advances and exciting ideas to come that lead to better management of the pediatric airway.

  View details for DOI 10.1016/S0749-0704(05)70126-3

  View details for Web of Science ID 000088661300010

  View details for PubMedID 10941587

• Diabetes and transport: A potentially bittersweet combination PEDIATRIC EMERGENCY CARE Woodward, G. A., Levy, R. J., Weinzimer, S. A. 1998; 14 (1): 71-76

  Abstract

  These cases represent a portion of the spectrum of medical issues that may be seen in patients with a diagnosis of IDDM. As the first case suggests, knowledge of the disease process and an expanded differential diagnosis is imperative when acting as medical command for these patients. Interfacility transport does not only involve rapid and safe transport between institutions, but must also offer the highest level of expertise available for the referring physician and the patient. For this reason, we recommend the immediate availability of a senior level experienced pediatric physician for involvement in all but the most routine pediatric interfacility transports. Rapid recognition at the time of initial presentation or transport of the correct diagnosis in patient one may have altered potential outcome. Case 2 represents a potential untoward outcome which might be potentiated or exacerbated by the care given during transport. Although this patient's transport time was short, a similar patient may present who needs prolonged transport. The patient might also present to the transport service prior to neurologic deterioration. One must be prepared to intervene for all potential complications as they arise. Case 3 represents a patient whose physical examination suggested more intense therapy was needed than is offered by many DKA protocols. It is important to listen to what the patients are trying to tell us, rather than relying strictly on protocols or guidelines. While protocols or guidelines offer a menu of potential therapies, one must be prepared to vary from these guidelines if suggested by the patient's condition. Recognition of delayed capillary refill in patient 3 allowed for an increase in fluid administration and rapid patient improvement. While not evident with the presented short transports, the use of point of care testing in a transport vehicle can be useful for these types of patients. The opportunity to closely monitor blood chemistry evaluations and gasses can give insight about an ongoing process, suggest therapies, and help direct interventions that, in the past, often waited until the patient arrived at the receiving hospital. That additional information can be invaluable for the ill patient whose outcome may hinge on early recognition of subtle changes with subsequent appropriate interventions.

  View details for DOI 10.1097/00006565-199802000-00019

  View details for Web of Science ID 000072151900019

  View details for PubMedID 9516638