Edward J. Bertaccini, MD, is a native of San Jose, California. He is a Cardinal Bellarmine Award winning graduate of Bellarmine College Preparatory in San Jose. He completed his undergraduate training in Biochemistry and Quantum Physics at the University of California, Davis, where he graduated Summa Cum Laude. He subsequently attended the St. Louis University School of Medicine in St. Louis, MO.

Dr. Bertaccini returned home to complete his internship at the Santa Clara Valley Medical Center, and his anesthesiology residency with subsequent ICU fellowship at the Stanford University School of Medicine. Upon completion of his training in 1994, he joined the faculty of the Stanford University Department of Anesthesia and began service to his country via his post in anesthesia and critical care medicine at the VA Palo Alto Health Care System.

Dr. Bertaccini is currently a Professor of Anesthesiology and Intensive Care Medicine within the Stanford University School of Medicine and maintains an internationally recognized program in the molecular modeling of anesthetic action. He practices as a cardiac anesthesiologist and intensive care specialist at the VA Palo Alto Health Care System where he has served as both the director of the operating room and the acting co-director of the intensive care units. His clinical efforts have played an integral part of teams that have achieved national recognition for both cardiac surgery as well as intensive care outcomes.

Professional Education

  • Residency, Stanford University Department of Anesthesia, Anesthesiology (1993)
  • fellowship, Stanford University Department of Anesthesia, Critical Care Medicine (1994)

Research & Scholarship

Current Research and Scholarly Interests

Molecular structures of drugs related to clinical, anesthesia; molecular modeling related to biological activity.


2018-19 Courses


All Publications

  • Assessment of Homology Templates and an Anesthetic Binding Site within the ?-Aminobutyric Acid Receptor. Anesthesiology Bertaccini, E. J., Yoluk, O., Lindahl, E. R., Trudell, J. R. 2013; 119 (5): 1087-1095


    BACKGROUND:: Anesthetics mediate portions of their activity via modulation of the γ-aminobutyric acid receptor (GABAaR). Although its molecular structure remains unknown, significant progress has been made toward understanding its interactions with anesthetics via molecular modeling. METHODS:: The structure of the torpedo acetylcholine receptor (nAChRα), the structures of the α4 and β2 subunits of the human nAChR, the structures of the eukaryotic glutamate-gated chloride channel (GluCl), and the prokaryotic pH-sensing channels, from Gloeobacter violaceus and Erwinia chrysanthemi, were aligned with the SAlign and 3DMA algorithms. A multiple sequence alignment from these structures and those of the GABAaR was performed with ClustalW. The Modeler and Rosetta algorithms independently created three-dimensional constructs of the GABAaR from the GluCl template. The CDocker algorithm docked a congeneric series of propofol derivatives into the binding pocket and scored calculated binding affinities for correlation with known GABAaR potentiation EC50s. RESULTS:: Multiple structure alignments of templates revealed a clear consensus of residue locations relevant to anesthetic effects except for torpedo nAChR. Within the GABAaR models generated from GluCl, the residues notable for modulating anesthetic action within transmembrane segments 1, 2, and 3 converged on the intersubunit interface between α and β subunits. Docking scores of a propofol derivative series into this binding site showed strong linear correlation with GABAaR potentiation EC50. CONCLUSION:: Consensus structural alignment based on homologous templates revealed an intersubunit anesthetic binding cavity within the transmembrane domain of the GABAaR, which showed a correlation of ligand docking scores with experimentally measured GABAaR potentiation.

    View details for DOI 10.1097/ALN.0b013e31829e47e3

    View details for PubMedID 23770602

  • Disruption of an intersubunit electrostatic bond is a critical step in glycine receptor activation PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Todorovic, J., Welsh, B. T., Bertaccini, E. J., Trudell, J. R., Mihic, S. J. 2010; 107 (17): 7987-7992


    Proper regulation of neurotransmission requires that ligand-activated ion channels remain closed until agonist binds. How channels then open remains poorly understood. Glycine receptor (GlyR) gating is initiated by agonist binding at interfaces between adjacent subunits in the extracellular domain. Aspartate-97, located at the alpha1 GlyR interface, is a conserved residue in the cys-loop receptor superfamily. The mutation of D97 to arginine (D97R) causes spontaneous channel opening, with open and closed dwell times similar to those of maximally activated WT GlyR. Using a model of the N-terminal domain of the alpha1 GlyR, we hypothesized that an arginine-119 residue was forming intersubunit electrostatic bonds with D97. The D97R/R119E charge reversal restored this interaction, stabilizing channels in their closed states. Cysteine substitution shows that this link occurs between adjacent subunits. This intersubunit electrostatic interaction among GlyR subunits thus contributes to the stabilization of the closed channel state, and its disruption represents a critical step in GlyR activation.

    View details for DOI 10.1073/pnas.1001845107

    View details for Web of Science ID 000277088700069

    View details for PubMedID 20385800

  • The common chemical motifs within anesthetic binding sites ANESTHESIA AND ANALGESIA Bertaccini, E. J., Trudell, J. R., Franks, N. P. 2007; 104 (2): 318-324


    It is not yet possible to obtain crystal structures of anesthetic molecules bound to proteins that are plausible neuronal targets; for example, ligand-gated ion channels. However, there are x-ray crystal structures in which anesthetics are complexed with proteins that are not directly related to anesthetic action. Much useful information about anesthetic-protein interactions can be derived from the x-ray crystal structures of halothane-cholesterol oxidase, bromoform-luciferase, halothane-albumin, and dichloroethane-dehalogenase. These structures show anesthetic-protein interactions at the atomic level.We obtained the known coordinate files for bromoform-luciferase, halothane- albumin, dichloroethane-dehalogenase, and halothane-cholesterol oxidase. These were then modified by adding hydrogens, edited into subsets, and underwent a series of restrained molecular mechanics optimizations. Final analysis of anesthetic polarization within the anesthetic binding site occurred via combined molecular mechanics-quantum mechanics calculations.The anesthetic binding sites within these well-characterized anesthetic-protein complexes possess a set of common characteristics that we refer to as "binding motifs." The common features of these motifs are polar and nonpolar interactions within an amphiphilic binding cavity, including the presence of weak hydrogen bond interactions with amino acids and water molecules. Calculations also demonstrated the polarizing effect of the amphipathic binding sites on what are otherwise considered quite hydrophobic anesthetics. This polarization appears energetically favorable.Anesthetic binding to proteins involves amphipathic interactions.

    View details for DOI 10.1213/01.ane.0000253029.67331.8d

    View details for Web of Science ID 000243661000018

    View details for PubMedID 17242087

  • Predicting the transmembrane secondary structure of ligand-gated ion channels PROTEIN ENGINEERING Bertaccini, E., Trudell, J. R. 2002; 15 (6): 443-453


    Recent mutational analyses of ligand-gated ion channels (LGICs) have demonstrated a plausible site of anesthetic action within their transmembrane domains. Although there is a consensus that the transmembrane domain is formed from four membrane-spanning segments, the secondary structure of these segments is not known. We utilized 10 state-of-the-art bioinformatics techniques to predict the transmembrane topology of the tetrameric regions within six members of the LGIC family that are relevant to anesthetic action. They are the human forms of the GABA alpha 1 receptor, the glycine alpha 1 receptor, the 5HT3 serotonin receptor, the nicotinic AChR alpha 4 and alpha 7 receptors and the Torpedo nAChR alpha 1 receptor. The algorithms utilized were HMMTOP, TMHMM, TMPred, PHDhtm, DAS, TMFinder, SOSUI, TMAP, MEMSAT and TOPPred2. The resulting predictions were superimposed on to a multiple sequence alignment of the six amino acid sequences created using the CLUSTAL W algorithm. There was a clear statistical consensus for the presence of four alpha helices in those regions experimentally thought to span the membrane. The consensus of 10 topology prediction techniques supports the hypothesis that the transmembrane subunits of the LGICs are tetrameric bundles of alpha helices.

    View details for Web of Science ID 000176585100001

    View details for PubMedID 12082162

  • Anesthetics and ion channels: Molecular models and sites of action ANNUAL REVIEW OF PHARMACOLOGY AND TOXICOLOGY Yamakura, T., Bertaccini, E., Trudell, J. R., Harris, R. A. 2001; 41: 23-51


    The mechanisms of general anesthesia in the central nervous system are finally yielding to molecular examination. As a result of research during the past several decades, a group of ligand-gated ion channels have emerged as plausible targets for general anesthetics. Molecular biology techniques have greatly accelerated attempts to classify ligand-gated ion channel sensitivity to general anesthetics, and have identified the sites of receptor subunits critical for anesthetic modulation using chimeric and mutated receptors. The experimental data have facilitated the construction of tenable molecular models for anesthetic binding sites, which in turn allows structural predictions to be tested. In vivo significance of a putative anesthetic target can now be examined by targeted gene manipulations in mice. In this review, we summarize from a molecular perspective recent advances in our understanding of mechanisms of action of general anesthetics on ligand-gated ion channels.

    View details for Web of Science ID 000168439400002

    View details for PubMedID 11264449

  • An In Vitro Model for Identifying Cardiac Side Effects of Anesthetics. Anesthesia and analgesia Chang, A. C., Chang, A. C., Nicin, L., Weber, G. J., Holbrook, C., Davies, M. F., Blau, H. M., Bertaccini, E. J. 2018


    The understanding of anesthetic side effects on the heart has been hindered by the lack of sophisticated clinical models. Using micropatterned human-induced pluripotent stem cell-derived cardiomyocytes, we obtained cardiac muscle depressant profiles for propofol, etomidate, and our newly identified anesthetic compound KSEB01-S2. Propofol was the strongest depressant among the 3 compounds tested, exhibiting the largest decrease in contraction velocity, depression rate, and beating frequency. Interestingly, KSEB01-S2 behaved similarly to etomidate, suggesting a better cardiac safety profile. Our results provide a proof-of-concept for using human-induced pluripotent stem cell-derived cardiomyocytes as an in vitro platform for future drug design.

    View details for DOI 10.1213/ANE.0000000000003757

    View details for PubMedID 30198930

  • Insights Into Receptor-Based Anesthetic Pharmacophores and Anesthetic-Protein Interactions. Methods in enzymology Fahrenbach, V. S., Bertaccini, E. J. 2018; 602: 77–95


    General anesthetics are thought to allosterically bind and potentiate the inhibitory currents of the GABAA receptor through drug-specific binding sites. The physiologically relevant isoform of the GABAA receptor is a transmembrane ligand-gated ion channel consisting of five subunits (gamma-alpha-beta-alpha-beta linkage) symmetrically arranged around a central chloride-conducting pore. Although the exact molecular structure of this heteropentameric GABAA receptor remains unknown, molecular modeling has allowed significant advancements in understanding anesthetic binding and action. Using the open-channel conformations of the homologous glycine and glutamate-gated chloride receptors as templates, a homology model of the GABAA receptor was constructed using the Discovery Studio computational chemistry software suite. Consensus structural alignment of the homology templates allowed for the construction of a three-dimensional heteropentameric GABAA receptor model with (gamma2-beta3-alpha1-beta3-alpha1) subunit linkage. An anesthetic binding site was identified within the transmembrane alpha/beta intersubunit space by the convergence of three residues shown to be essential for anesthetic activity in previous studies with mutant mice (beta3-N265, beta3-M286, alpha1-L232). Propofol derivatives docked into this binding site showed log-linear correlation with experimentally derived GABAA receptor potentiation (EC50) values, suggesting this binding site may be important for receptor activation. The receptor-based pharmacophore was analyzed with surface maps displaying the predominant anesthetic-protein interactions, revealing an amphiphilic binding cavity incorporating the three residues involved in anesthetic modulation. Quantum mechanics calculations of the bonding patterns found in complementary high-resolution receptor systems further elucidated the complex nature of anesthetic-protein interactions.

    View details for DOI 10.1016/bs.mie.2018.01.004

    View details for PubMedID 29588042

  • Design and Implementation of a Perioperative Surgical Home at a Veterans Affairs Hospital. Seminars in cardiothoracic and vascular anesthesia Walters, T. L., Howard, S. K., Kou, A., Bertaccini, E. J., Harrison, T. K., Kim, T. E., Shafer, A., Brun, C., Funck, N., Siegel, L. C., Stary, E., Mariano, E. R. 2016; 20 (2): 133-140


    The innovative Perioperative Surgical Home model aims to optimize the outcomes of surgical patients by leveraging the expertise and leadership of physician anesthesiologists, but there is a paucity of practical examples to follow. Veterans Affairs health care, the largest integrated system in the United States, may be the ideal environment in which to explore this model. We present our experience implementing Perioperative Surgical Home at one tertiary care university-affiliated Veterans Affairs hospital. This process involved initiating consistent postoperative patient follow-up beyond the postanesthesia care unit, a focus on improving in-hospital acute pain management, creation of an accessible database to track outcomes, developing new clinical pathways, and recruiting additional staff. Today, our Perioperative Surgical Home facilitates communication between various services involved in the care of surgical patients, monitoring of patient outcomes, and continuous process improvement.

    View details for DOI 10.1177/1089253215607066

    View details for PubMedID 26392388

  • Identification of an Inhibitory Alcohol Binding Site in GABA(A) rho 1 Receptors ACS CHEMICAL NEUROSCIENCE Borghese, C. M., Ruiz, C. I., Lee, U. S., Cullins, M. A., Bertaccini, E. J., Trudell, J. R., Harris, R. A. 2016; 7 (1): 100-108


    Alcohols inhibit γ-aminobutyric acid type A ρ1 receptor function. After introducing mutations in several positions of the second transmembrane helix in ρ1, we studied the effects of ethanol and hexanol on GABA responses using two-electrode voltage clamp electrophysiology in Xenopus laevis oocytes. The 6' mutations produced the following effects on ethanol and hexanol responses: small increase or no change (T6'M), increased inhibition (T6'V), and small potentiation (T6'Y and T6'F). The 5' mutations produced mainly increases in hexanol inhibition. Other mutations produced small (3' and 9') or no changes (2' and L277 in the first transmembrane domain) in alcohol effects. These results suggest an inhibitory alcohol binding site near the 6' position. Homology models of ρ1 receptors based on the X-ray structure of GluCl showed that the 2', 5', 6', and 9' residues were easily accessible from the ion pore, with 5' and 6' residues from neighboring subunits facing each other; L3' and L277 also faced the neighboring subunit. We tested ethanol through octanol on single and double mutated ρ1 receptors [ρ1(I15'S), ρ1(T6'Y), and ρ1(T6'Y,I15'S)] to further characterize the inhibitory alcohol pocket in the wild-type ρ1 receptor. The pocket can only bind relatively short-chain alcohols and is eliminated by introducing Y in the 6' position. Replacing the bulky 15' residue with a smaller side chain introduced a potentiating binding site, more sensitive to long-chain than to short-chain alcohols. In conclusion, the net alcohol effect on the ρ1 receptor is determined by the sum of its actions on inhibitory and potentiating sites.

    View details for DOI 10.1021/acs.chemneuro.5b00246

    View details for Web of Science ID 000368567200013

    View details for PubMedCentralID PMC4934417

  • Insights into the Nature of Anesthetic Protein Interactions: An ONIOM Study JOURNAL OF PHYSICAL CHEMISTRY B Qiu, L., Lin, J., Bertaccini, E. J. 2015; 119 (40): 12771-12782

    View details for DOI 10.1021/acs.jpcb.5b05897

    View details for Web of Science ID 000362701900005

    View details for PubMedID 26388288

  • Invasive Mechanical Ventilation in California Over 2000-2009: Implications for Emergency Medicine. The western journal of emergency medicine Mudumbai, S. C., Barr, J., Scott, J., Mariano, E. R., Bertaccini, E., Nguyen, H., Memtsoudis, S. G., Cason, B., Phibbs, C. S., Wagner, T. 2015; 16 (5): 696-706


    Patients who require invasive mechanical ventilation (IMV) often represent a sequence of care between the emergency department (ED) and intensive care unit (ICU). Despite being the most populous state, little information exists to define patterns of IMV use within the state of California.We examined data from the masked Patient Discharge Database of California's Office of Statewide Health Planning and Development from 2000-2009. Adult patients who received IMV during their stay were identified using the International Classification of Diseases 9th Revision and Clinical Modification procedure codes (96.70, 96.71, 96.72). Patients were divided into age strata (18-34yr, 35-64yr, and >65yr). Using descriptive statistics and regression analyses, for IMV discharges during the study period, we quantified the number of ED vs. non-ED based admissions; changes in patient characteristics and clinical outcome; evaluated the marginal costs for IMV; determined predictors for prolonged acute mechanical ventilation (PAMV, i.e. IMV>96hr); and projected the number of IMV discharges and ED-based admissions by year 2020.There were 696,634 IMV discharges available for analysis. From 2000-2009, IMV discharges increased by 2.8%/year: n=60,933 (293/100,000 persons) in 2000 to n=79,868 (328/100,000 persons) in 2009. While ED-based admissions grew by 3.8%/year, non-ED-based admissions remained stable (0%). During 2000-2009, fastest growth was noted for 1) the 35-64 year age strata; 2) Hispanics; 3) patients with non-Medicare public insurance; and 4) patients requiring PAMV. Average total patient cost-adjusted charges per hospital discharge increased by 29% from 2000 (from $42,528 to $60,215 in 2014 dollars) along with increases in the number of patients discharged to home and skilled nursing facilities. Higher marginal costs were noted for younger patients (ages 18-34yr), non-whites, and publicly insured patients. Some of the strongest predictors for PAMV were age 35-64 years (OR=1.12; 95% CI [1.09-1.14], p<0.05); non-Whites; and non-Medicare public insurance. Our models suggest that by 2020, IMV discharges will grow to n=153,153 (377 IMV discharges/100,000 persons) with 99,095 admitted through the ED.Based on sustained growth over the past decade, by the year 2020, we project a further increase to 153,153 IMV discharges with 99,095 admitted through the ED. Given limited ICU bed capacities, ongoing increases in the number and type of IMV patients have the potential to adversely affect California EDs that often admit patients to ICUs.

    View details for DOI 10.5811/westjem.2015.6.25736

    View details for PubMedID 26587094

  • Molecular Modeling of a Tandem Two Pore Domain Potassium Channel Reveals a Putative Binding Site for General Anesthetics ACS CHEMICAL NEUROSCIENCE Bertaccini, E. J., Dickinson, R., Trudell, J. R., Franks, N. P. 2014; 5 (12): 1246-1252


    Anesthetics are thought to mediate a portion of their activity via binding to and modulation of potassium channels. In particular, tandem pore potassium channels (K2P) are transmembrane ion channels whose current is modulated by the presence of general anesthetics and whose genetic absence has been shown to confer a level of anesthetic resistance. While the exact molecular structure of all K2P forms remains unknown, significant progress has been made toward understanding their structure and interactions with anesthetics via the methods of molecular modeling, coupled with the recently released higher resolution structures of homologous potassium channels to act as templates. Such models reveal the convergence of amino acid regions that are known to modulate anesthetic activity onto a common three- dimensional cavity that forms a putative anesthetic binding site. The model successfully predicts additional important residues that are also involved in the putative binding site as validated by the results of suggested experimental mutations. Such a model can now be used to further predict other amino acid residues that may be intimately involved in the target-based structure-activity relationships that are necessary for anesthetic binding.

    View details for DOI 10.1021/cn500172e

    View details for Web of Science ID 000346682000014

    View details for PubMedID 25340635

    View details for PubMedCentralID PMC4306477

  • Structural Models of Ligand-Gated Ion Channels: Sites of Action for Anesthetics and Ethanol ALCOHOLISM-CLINICAL AND EXPERIMENTAL RESEARCH Olsen, R. W., Li, G., Wallner, M., Trudell, J. R., Bertaccini, E. J., Lindahl, E., Miller, K. W., Alkana, R. L., Davies, D. L. 2014; 38 (3): 595-603


    The molecular mechanism(s) of action of anesthetic, and especially, intoxicating doses of alcohol (ethanol [EtOH]) have been of interest even before the advent of the Research Society on Alcoholism. Recent physiological, genetic, and biochemical studies have pin-pointed molecular targets for anesthetics and EtOH in the brain as ligand-gated ion channel (LGIC) membrane proteins, especially the pentameric (5 subunit) Cys-loop superfamily of neurotransmitter receptors including nicotinic acetylcholine (nAChRs), GABAA (GABAA Rs), and glycine receptors (GlyRs). The ability to demonstrate molecular and structural elements of these proteins critical for the behavioral effects of these drugs on animals and humans provides convincing evidence for their role in the drugs' actions. Amino acid residues necessary for pharmacologically relevant allosteric modulation of LGIC function by anesthetics and EtOH have been identified in these channel proteins. Site-directed mutagenesis revealed potential allosteric modulatory sites in both the trans-membrane domain (TMD) and extracellular domain (ECD). Potential sites of action and binding have been deduced from homology modeling of other LGICs with structures known from crystallography and cryo-electron microscopy studies. Direct information about ligand binding in the TMD has been obtained by photoaffinity labeling, especially in GABAA Rs. Recent structural information from crystallized procaryotic (ELIC and GLIC) and eukaryotic (GluCl) LGICs allows refinement of the structural models including evaluation of possible sites of EtOH action.

    View details for DOI 10.1111/acer.12283

    View details for Web of Science ID 000332758200001

    View details for PubMedID 24164436

  • Stabilization of the GluCl Ligand-Gated Ion Channel in the Presence and Absence of Ivermectin BIOPHYSICAL JOURNAL Yoluk, O., Bromstrup, T., Bertaccini, E. J., Trudell, J. R., Lindahl, E. 2013; 105 (3): 640-647


    Improving our understanding of the mechanisms and effects of anesthetics is a critically important part of neuroscience. The currently dominant theory is that anesthetics and similar molecules act by binding to Cys-loop receptors in the postsynaptic terminal of nerve cells and potentiate or inhibit their function. Although structures for some of the most important mammalian channels have still not been determined, a number of important results have been derived from work on homologous cationic channels in bacteria. However, partly due to the lack of a nervous system in bacteria, there are a number of questions about how these results relate to higher organisms. The recent determination of a structure of the eukaryotic chloride channel, GluCl, is an important step toward accurate modeling of mammalian channels, because it is more similar in function to human Cys-loop receptors such as GABAAR or GlyR. One potential issue with using GluCl to model other receptors is the presence of the large ligand ivermectin (IVM) positioned between all five subunits. Here, we have performed a series of microsecond molecular simulations to study how the dynamics and structure of GluCl change in the presence versus absence of IVM. When the ligand is removed, subunits move at least 2 Å closer to each other compared to simulations with IVM bound. In addition, the pore radius shrinks to 1.2 Å, all of which appears to support a model where IVM binding between subunits stabilizes an open state, and that the relaxed nonIVM conformations might be suitable for modeling other channels. Interestingly, the presence of IVM also has an effect on the structure of the important loop C located at the neurotransmitter-binding pocket, which might help shed light on its partial agonist behavior.

    View details for DOI 10.1016/j.bpj.2013.06.037

    View details for Web of Science ID 000323141100014

    View details for PubMedID 23931312

  • Association of age and packed red blood cell transfusion to 1-year survival - an observational study of ICU patients TRANSFUSION MEDICINE Mudumbai, S. C., Cronkite, R., Hu, K. U., Heidenreich, P. A., Gonzalez, C., Bertaccini, E., Stafford, R. S., Cason, B. A., Mariano, E. R., Wagner, T. 2013; 23 (4): 231-237


    OBJECTIVES: To compare the 1-year survival for different age strata of intensive care unit (ICU) patients after receipt of packed red blood cell (PRBC) transfusions. BACKGROUND: Despite guidelines documenting risks of PRBC transfusion and data showing that increasing age is associated with ICU mortality, little data exist on whether age alters the transfusion-related risk of decreased survival. METHODS: We retrospectively examined data on 2393 consecutive male ICU patients admitted to a tertiary-care hospital from 2003 to 2009 in age strata: 21-50, 51-60, 61-70, 71-80 and >80 years. We calculated Cox regression models to determine the modifying effect of age on the impact of PRBC transfusion on 1-year survival by using interaction terms between receipt of transfusion and age strata, controlling for type of admission and Charlson co-morbidity indices. We also examined the distribution of admission haematocrit and whether transfusion rates differed by age strata. RESULTS: All age strata experienced statistically similar risks of decreased 1-year survival after receipt of PRBC transfusions. However, patients age >80 were more likely than younger cohorts to have haematocrits of 25-30% at admission and were transfused at approximately twice the rate of each of the younger age strata. DISCUSSION: We found no significant interaction between receipt of red cell transfusion and age, as variables, and survival at 1 year as an outcome.

    View details for DOI 10.1111/tme.12010

    View details for Web of Science ID 000321975300005

    View details for PubMedID 23480030

  • Molecular Mechanism for the Dual Alcohol Modulation of Cys-loop Receptors PLOS COMPUTATIONAL BIOLOGY Murail, S., Howard, R. J., Broemstrup, T., Bertaccini, E. J., Harris, R. A., Trudell, J. R., Lindahl, E. 2012; 8 (10)


    Cys-loop receptors constitute a superfamily of pentameric ligand-gated ion channels (pLGICs), including receptors for acetylcholine, serotonin, glycine and γ-aminobutyric acid. Several bacterial homologues have been identified that are excellent models for understanding allosteric binding of alcohols and anesthetics in human Cys-loop receptors. Recently, we showed that a single point mutation on a prokaryotic homologue (GLIC) could transform it from a channel weakly potentiated by ethanol into a highly ethanol-sensitive channel. Here, we have employed molecular simulations to study ethanol binding to GLIC, and to elucidate the role of the ethanol-enhancing mutation in GLIC modulation. By performing 1-µs simulations with and without ethanol on wild-type and mutated GLIC, we observed spontaneous binding in both intra-subunit and inter-subunit transmembrane cavities. In contrast to the glycine receptor GlyR, in which we previously observed ethanol binding primarily in an inter-subunit cavity, ethanol primarily occupied an intra-subunit cavity in wild-type GLIC. However, the highly ethanol-sensitive GLIC mutation significantly enhanced ethanol binding in the inter-subunit cavity. These results demonstrate dramatic effects of the F(14')A mutation on the distribution of ligands, and are consistent with a two-site model of pLGIC inhibition and potentiation.

    View details for DOI 10.1371/journal.pcbi.1002710

    View details for Web of Science ID 000310568800011

    View details for PubMedID 23055913

  • Teaching an Old GABA Receptor New Tricks ANESTHESIA AND ANALGESIA Trudell, J. R., Bertaccini, E., Maclver, M. B. 2012; 115 (2): 270-273


    The accompanying articles in this issue of the journal's special collection describe attempts to improve on the dynamics of distribution and reduce side effects of analogs of etomidate and benzodiazepines. Both classes of drugs have their principal sites of action on γ-aminobutyric acid type A receptors, although at very different binding sites and by different mechanisms of action. Herein, we review the structure of γ-aminobutyric acid type A receptors and describe the location of the 2 likely binding sites. In addition, we describe how these drugs can interact with the nervous system at a systems level. We leave it to other reviewers to discuss whether these new drugs offer true clinical improvements.

    View details for DOI 10.1213/ANE.0b013e31824a0b3c

    View details for Web of Science ID 000306769500012

    View details for PubMedID 22344244

  • Induced changes in protein receptors conferring resistance to anesthetics CURRENT OPINION IN ANESTHESIOLOGY Bertaccini, E. J., Trudell, J. R. 2012; 25 (4): 405-410


    Although general anesthetics have been provided effectively for many years, their exact molecular underpinnings remain relatively unknown. In this article, we discuss the recent findings associated with resistance to anesthetic effects as a way of shedding light on these mechanisms.The original theories of anesthetic action based upon their effects on cellular membranes have given way to specific theories concerning direct effects on ion channel proteins. These molecular targets are intimately involved in the conduct of neuronal signaling within the central nervous system and are thought to be essential in the modulation of conscious states. It is the lack of a thorough understanding of unperturbed consciousness that fosters great difficulty in understanding how anesthetics alter this conscious state. However, one very fruitful line of analysis in the quest for such answers lies in the examination of both in-vitro and in-vivo ion channel systems that seem to maintain variable levels of resistance to anesthetics.Information about the possible targets and molecular nature of anesthetic action is being derived from studies of anesthetic resistance in γ aminobutyric acid receptors, tandem pore potassium channels, and an apparently wide variety of protein systems within the nematode, Caenorhabditis elegans.

    View details for DOI 10.1097/ACO.0b013e328354fda8

    View details for Web of Science ID 000306273900002

    View details for PubMedID 22614247

  • NEW HOMOLOGY MODELS OF GLYR AND GABAAR PROVIDE NEAR ATOMIC LEVEL RESOLUTION AND ARE SUITABLE FOR STUDIES OF GATING MOTIONS WITH MOLECULAR DYNAMICS 35th Annual Scientific Meeting of the Research-Society-on-Alcoholism (RSA) Trudell, J. R., Bertaccini, E., Davies, D., ALKANA, R., Perkins, D., Lindahl, E., Murail, S., Harris, R. A., Howard, R. WILEY-BLACKWELL. 2012: 362A–362A
  • Association of admission hematocrit with 6-month and 1-year mortality in intensive care unit patients TRANSFUSION Mudumbai, S. C., Cronkite, R., Hu, K. U., Wagner, T., Hayashi, K., Ozanne, G. M., Davies, M. F., Heidenreich, P., Bertaccini, E. 2011; 51 (10): 2148-2159


    This study examined the association of hematocrit (Hct) levels measured upon intensive care unit (ICU) admission and red blood cell transfusions to long-term (1-year or 180-day) mortality for both surgical and medical patients.Administrative and laboratory data were collected retrospectively on 2393 consecutive medical and surgical male patients admitted to the ICU between 2003 and 2009. We stratified patients based on their median Hct level during the first 24 hours of their ICU stay (Hct < 25.0%, 25% ≤ Hct < 30%, 30% ≤ Hct < 39%, and 39.0% and higher). An extended Cox regression analysis was conducted to identify the time period after ICU admission (0 to <180, 180 to 365 days) when low Hct (<25.0) was most strongly associated with mortality. The unadjusted and adjusted relationship between admission Hct level, receipt of a transfusion, and 180-day mortality was assessed using Cox proportional hazards regression modeling.Patients with an Hct level of less than 25% who were not transfused had the worst mortality risk overall (hazard ratio [HR], 6.26; 95% confidence interval [CI], 3.05-12.85; p < 0.001) during the 6 months after ICU admission than patients with a Hct level of 39.0% or more who were not transfused. Within the subgroup of patients with a Hct level of less than 25% only, receipt of a transfusion was associated with a significant reduction in the risk of mortality (HR, 0.40; 95% CI, 0.19-0.85; p = 0.017).Anemia of a Hct level of less than 25% upon admission to the ICU, in the absence of a transfusion, is associated with long-term mortality. Our study suggests that there may be Hct levels below which the transfusion risk-to-benefit imbalance reverses.

    View details for DOI 10.1111/j.1537-2995.2011.03134.x

    View details for Web of Science ID 000295917700014

    View details for PubMedID 21985048

  • Microsecond Simulations Indicate that Ethanol Binds between Subunits and Could Stabilize an Open-State Model of a Glycine Receptor BIOPHYSICAL JOURNAL Murail, S., Wallner, B., Trudell, J. R., Bertaccini, E., Lindahl, E. 2011; 100 (7): 1642-1650


    Cys-loop receptors constitute a superfamily of ion channels gated by ligands such as acetylcholine, serotonin, glycine, and γ-aminobutyric acid. All of these receptors are thought to share structural characteristics, but due to high sequence variation and limited structure availability, our knowledge about allosteric binding sites is still limited. These sites are frequent targets of anesthetic and alcohol molecules, and are of high pharmacological importance. We used molecular simulations to study ethanol binding and equilibrium exchange for the homomeric α1 glycine receptor (GlyRα1), modeled on the structure of the Gloeobacter violaceus pentameric ligand-gated channel. Ethanol has a well-known potentiating effect and can be used in high concentrations. By performing two microsecond-scale simulations of GlyR with/without ethanol, we were able to observe spontaneous binding in cavities and equilibrium ligand exchange. Of interest, it appears that there are ethanol-binding sites both between and within the GlyR transmembrane subunits, with the intersubunit site having the highest occupancy and slowest exchange (∼200 ns). This model site involves several residues that were previously identified via mutations as being crucial for potentiation. Finally, ethanol appears to stabilize the GlyR model built on a presumably open form of the ligand-gated channel. This stabilization could help explain the effects of allosteric ligand binding in Cys-loop receptors.

    View details for DOI 10.1016/j.bpj.2011.02.032

    View details for Web of Science ID 000289494200009

    View details for PubMedID 21463577

  • Modeling Anesthetic Binding Sites within the Glycine Alpha One Receptor Based on Prokaryotic Ion Channel Templates: The Problem with TM4 JOURNAL OF CHEMICAL INFORMATION AND MODELING Bertaccini, E. J., Wallner, B., Trudell, J. R., Lindahl, E. 2010; 50 (12): 2248-2255


    Ligand-gated ion channels (LGICs) significantly modulate anesthetic effects. Their exact molecular structure remains unknown. This has led to ambiguity regarding the proper amino acid alignment within their 3D structure and, in turn, the location of any anesthetic binding sites. Current controversies suggest that such a site could be located in either an intra- or intersubunit locale within the transmembrane domain of the protein. Here, we built a model of the glycine alpha one receptor (GlyRa1) based on the open-state structures of two new high-resolution ion channel templates from the prokaryote, Gloebacter violaceus (GLIC). Sequence scoring suggests reasonable homology between GlyRa1 and GLIC. Three of the residues notable for modulating anesthetic action are on transmembrane segments 1-3 (TM1-3): (ILE229, SER 267, and ALA 288). They line an intersubunit interface, in contrast to previous models. However, residues from the fourth transmembrane domain (TM4) that are known to modulate a variety of anesthetic effects are quite distant from this putative anesthetic binding site. While this model can account for a large proportion of the physicochemical data regarding such proteins, it cannot readily account for the alterations on anesthetic effects that are due to mutations within TM4.

    View details for DOI 10.1021/ci100266e

    View details for Web of Science ID 000285559900017

    View details for PubMedID 21117677

  • Normal Mode Gating Motions of a Ligand-Gated Ion Channel Persist in a Fully Hydrated Lipid Bilayer Model ACS CHEMICAL NEUROSCIENCE Bertaccini, E. J., Trudell, J. R., Lindahl, E. 2010; 1 (8): 552-558


    We have previously used molecular modeling and normal-mode analyses combined with experimental data to visualize a plausible model of a transmembrane ligand-gated ion channel. We also postulated how the gating motion of the channel may be affected by the presence of various ligands, especially anesthetics. As is typical for normal-mode analyses, those studies were performed in vacuo to reduce the computational complexity of the problem. While such calculations constitute an efficient way to model the large scale structural flexibility of transmembrane proteins, they can be criticized for neglecting the effects of an explicit phospholipid bilayer or hydrated environment. Here, we show the successful calculation of normal-mode motions for our model of a glycine α-1 receptor, now suspended in a fully hydrated lipid bilayer. Despite the almost uniform atomic density, the introduction of water and lipid does not grossly distort the overall gating motion. Normal-mode analysis revealed that even a fully immersed glycine α-1 receptor continues to demonstrate an iris-like channel gating motion as a low-frequency, high-amplitude natural harmonic vibration consistent with channel gating. Furthermore, the introduction of periodic boundary conditions allows the examination of simultaneous harmonic vibrations of lipid in synchrony with the protein gating motions that are compatible with reasonable lipid bilayer perturbations. While these perturbations tend to influence the overall protein motion, this work provides continued support for the iris-like motion model that characterizes gating within the family of ligand-gated ion channels.

    View details for DOI 10.1021/cn100026t

    View details for Web of Science ID 000281052400005

    View details for PubMedID 22816018

  • The Molecular Mechanisms of Anesthetic Action: Updates and Cutting Edge Developments from the Field of Molecular Modeling. Pharmaceuticals (Basel, Switzerland) Bertaccini, E. J. 2010; 3 (7): 2178-2196


    For over 160 years, general anesthetics have been given for the relief of pain and suffering. While many theories of anesthetic action have been purported, it has become increasingly apparent that a significant molecular focus of anesthetic action lies within the family of ligand-gated ion channels (LGIC's). These protein channels have a transmembrane region that is composed of a pentamer of four helix bundles, symmetrically arranged around a central pore for ion passage. While initial and some current models suggest a possible cavity for binding within this four helix bundle, newer calculations postulate that the actual cavity for anesthetic binding may exist between four helix bundles. In either scenario, these cavities have a transmembrane mode of access and may be partially bordered by lipid moieties. Their physicochemical nature is amphiphilic. Anesthetic binding may alter the overall motion of a ligand-gated ion channel by a "foot-in-door" motif, resulting in the higher likelihood of and greater time spent in a specific channel state. The overall gating motion of these channels is consistent with that shown in normal mode analyses carried out both in vacuo as well as in explicitly hydrated lipid bilayer models. Molecular docking and large scale molecular dynamics calculations may now begin to show a more exact mode by which anesthetic molecules actually localize themselves and bind to specific protein sites within LGIC's, making the design of future improvements to anesthetic ligands a more realizable possibility.

    View details for PubMedID 27713348

    View details for PubMedCentralID PMC4036663

  • ICU Management after Thoracic Aorta Surgery Pocket ICU Management, 2nd edition (electronic) Bertaccini E, Wall M, Roberts P, Farmer JC 2010
  • ICU Management after Cardiac Surgery Pocket ICU Management, 2nd edition (electronic) Bertaccini E, Wall M, Roberts P, Farmer JC 2010
  • The Molecular Mechanisms of Anesthetic Action: Updates and Cutting Edge Developments from the Field of Molecular Modeling Pharmaceuticals Bertaccini E 2010; 3 (7): 2178-2196
  • Roles for Loop 2 residues of alpha 1 glycine receptors in agonist activation JOURNAL OF BIOLOGICAL CHEMISTRY Crawford, D. K., Perkins, D. I., Trudell, J. R., Bertaccini, E. J., Davies, D. L., Alkana, R. L. 2008; 283 (41): 27698-27706


    The present study tested the hypothesis that several residues in Loop 2 of alpha1 glycine receptors (GlyRs) play important roles in mediating the transduction of agonist activation to channel gating. This was accomplished by investigating the effect of cysteine point mutations at positions 50-60 on glycine responses in alpha1GlyRs using two-electrode voltage clamp of Xenopus oocytes. Cysteine substitutions produced position-specific changes in glycine sensitivity that were consistent with a beta-turn structure of Loop 2, with odd-numbered residues in the beta-turn interacting with other agonist-activation elements at the interface between extracellular and transmembrane domains. We also tested the hypothesis that the charge at position 53 is important for agonist activation by measuring the glycine response of wild type (WT) and E53C GlyRs exposed to methanethiosulfonate reagents. As earlier, E53C GlyRs have a significantly higher EC(50) than WT GlyRs. Exposing E53C GlyRs to the negatively charged 2-sulfonatoethyl methanethiosulfonate, but not neutral 2-hydroxyethyl methanethiosulfonate, positively charged 2-aminoethyl methanethiosulfonate, or 2-trimethylammonioethyl methanethiosulfonate, decreased the glycine EC(50) to resemble WT GlyR responses. Exposure to these reagents did not significantly alter the glycine EC(50) for WT GlyRs. The latter findings suggest that the negative charge at position 53 is important for activation of GlyRs through its interaction with positive charge(s) in other neighboring agonist activation elements. Collectively, the findings provide the basis for a refined molecular model of alpha1GlyRs based on the recent x-ray structure of a prokaryotic pentameric ligand-gated ion channel and offer insight into the structure-function relationships in GlyRs and possibly other ligand-gated ion channels.

    View details for DOI 10.1074/jbc.M802384200

    View details for Web of Science ID 000259719200041

    View details for PubMedID 18658152

  • Effect of cobratoxin binding on the normal mode vibration within acetylcholine binding protein JOURNAL OF CHEMICAL INFORMATION AND MODELING Bertaccini, E. J., Lindahl, E., Sixma, T., Trudell, J. R. 2008; 48 (4): 855-860


    Recent crystal structures of the acetylcholine binding protein (AChBP) have revealed surprisingly small structural alterations upon ligand binding. Here we investigate the extent to which ligand binding may affect receptor dynamics. AChBP is a homologue of the extracellular component of ligand-gated ion channels (LGICs). We have previously used an elastic network normal-mode analysis to propose a gating mechanism for the LGICs and to suggest the effects of various ligands on such motions. However, the difficulties with elastic network methods lie in their inability to account for the modest effects of a small ligand or mutation on ion channel motion. Here, we report the successful application of an elastic network normal mode technique to measure the effects of large ligand binding on receptor dynamics. The present calculations demonstrate a clear alteration in the native symmetric motions of a protein due to the presence of large protein cobratoxin ligands. In particular, normal-mode analysis revealed that cobratoxin binding to this protein significantly dampened the axially symmetric motion of the AChBP that may be associated with channel gating in the full nAChR. The results suggest that alterations in receptor dynamics could be a general feature of ligand binding.

    View details for DOI 10.1021/ci700456s

    View details for Web of Science ID 000255448400015

    View details for PubMedID 18348519

  • Molecular Modeling and mutagenesis reveals a tetradentate binding site for Zn2+ in GABA(A) alpha beta receptors and provides a structural basis for the modulating effect of the gamma subunit JOURNAL OF CHEMICAL INFORMATION AND MODELING Trudell, J. R., Yue, M. E., Bertaccini, E. J., Jenkins, A., Harrison, N. L. 2008; 48 (2): 344-349


    Gamma-aminobutyric acid type A receptors (GABA(A)-R) containing alpha1beta2gamma2 subunits are weakly inhibited by Zn2+, whereas receptors containing only the alpha1beta2 subunits are strongly inhibited. We built homology models of the ion pores of alpha1beta2 and alpha1beta2gamma2 GABA(A)-R using coordinates of the nicotinic acetylcholine receptor as a template. Threading the GABA(A)-R beta2 sequence onto this template placed the 17' histidine and the 20' glutamate residues at adjacent locations in the mouth of the pore, such that a nearly ideal tetradentate site for Zn2+ was formed from two histidine and two glutamate residues between adjacent beta subunits in the alpha1beta2 GABA(A)-R. Following optimization with CHARMM, the distance between the alpha-carbons of the adjacent histidine residues was approximately 9.2 A, close to the ideal distance for a Zn2+ binding site. Loss of inhibition by Zn2+ in alpha1beta2gamma2 GABA(A)-R can be explained by the geometry of these residues in the arrangement alpha1beta2gamma2alpha1beta2, in which the nearest C-alpha-C-alpha distance between the histidine residues is 15.5 A, too far apart for an energetically optimal Zn2+ binding site. We then mutated the gamma subunit at the 17' and/or 20' positions. Zn2+ inhibition was not restored in alpha1beta2gamma2 (I282H) receptors. A novel finding is that the modeling shows the native 20' lysine in gamma2 can compete with Zn2+ for binding to the inserted 17' histidine. Sensitivity to Zn2+ was restored in the double mutant receptor, alpha1beta2gamma2 (I282H; K285E), in which the competition with lysine was removed and a more favorable Zn2+ binding site was formed.

    View details for DOI 10.1021/ci700324a

    View details for Web of Science ID 000253428400011

    View details for PubMedID 18197653

  • Evidence that ethanol acts on a target in Loop 2 of the extracellular domain of alpha 1 glycine receptors 29th Annual Meeting of the Research-Society-on-Alcoholism Crawford, D. K., Trudell, J. R., Bertaccini, E. J., Li, K., Davies, D. L., Alkana, R. L. WILEY-BLACKWELL PUBLISHING, INC. 2007: 2097–2109


    Considerable evidence indicates that ethanol acts on specific residues in the transmembrane domains of glycine receptors (GlyRs). In this study, we tested the hypothesis that the extracellular domain is also a target for ethanol action by investigating the effect of cysteine substitutions at positions 52 (extracellular domain) and 267 (transmembrane domain) on responses to n-alcohols and propyl methanethiosulfonate (PMTS) in alpha1GlyRs expressed in Xenopus oocytes. In support of the hypothesis: (i) The A52C mutation changed ethanol sensitivity compared to WT GlyRs; (ii) PMTS produced irreversible alcohol-like potentiation in A52C GlyRs; and (iii) PMTS binding reduced the n-chain alcohol cutoff in A52C GlyRs. Further studies used PMTS binding to cysteines at positions 52 or 267 to block ethanol action at one site in order to determine its effect at other site(s). In these situations, ethanol caused negative modulation when acting at position 52 and positive modulation when acting at position 267. Collectively, these findings parallel the evidence that established the TM domain as a target for ethanol, suggest that positions 52 and 267 are part of the same alcohol pocket and indicate that the net effect of ethanol on GlyR function reflects the summation of its positive and negative modulatory effects on different targets.

    View details for DOI 10.1111/j.1471-4159.2007.04680.x

    View details for Web of Science ID 000249452000035

    View details for PubMedID 17561937

  • Normal-mode analysis of the glycine alpha1 receptor by three separate methods JOURNAL OF CHEMICAL INFORMATION AND MODELING Bertaccini, E. J., Trudell, J. R., Lindahl, E. 2007; 47 (4): 1572-1579


    Predicting collective dynamics and structural changes in biological macromolecules is pivotal toward a better understanding of many biological processes. Limitations due to large system sizes and inaccessible time scales have prompted the development of alternative techniques for the calculation of such motions. In this work, we present the results of a normal-mode analysis technique based on molecular mechanics that enables the calculation of accurate force-field based vibrations of extremely large molecules and compare it with two elastic network approximate models. When applied to the glycine alpha1 receptor, all three normal-mode analysis algorithms demonstrate an "iris-like" gating motion. Such gating motions have implications for understanding the effects of anesthetic and other ligand binding sites and for the means of transducing agonist binding into ion channel opening. Unlike the more approximate methods, molecular mechanics based analyses can also reveal approximate vibrational frequencies. Such analyses may someday allow the use of protein dynamics elucidated via normal-mode calculations as additional endpoints for future drug design.

    View details for DOI 10.1021/ci600566j

    View details for Web of Science ID 000248192200029

    View details for PubMedID 17602605

  • Normal Mode Analysis Reveals the Channel Gating Motion within a Ligand Gated Ion Channel Model Proceedings of the 7th International Conference on Basic and Systematic Mechanisms of Anesthesia Nara, Japan 25-27 February 2005, International Congress Series Bertaccini E, Trudell JR, Lindahl E 2005; 1283: 160-163
  • Homology modeling of a human glycine alpha 1 receptor reveals a plausible anesthetic binding site JOURNAL OF CHEMICAL INFORMATION AND MODELING Bertaccini, E. J., Shapiro, J., Brutlag, D. L., Trudell, J. R. 2005; 45 (1): 128-135


    The superfamily of ligand-gated ion channels (LGICs) has been implicated in anesthetic and alcohol responses. Mutations within glycine and GABA receptors have demonstrated that possible sites of anesthetic action exist within the transmembrane subunits of these receptors. The exact molecular arrangement of this transmembrane region remains at intermediate resolution with current experimental techniques. Homology modeling methods were therefore combined with experimental data to produce a more exact model of this region. A consensus from multiple bioinformatics techniques predicted the topology within the transmembrane domain of a glycine alpha one receptor (GlyRa1) to be alpha helical. This fold information was combined with sequence information using the SeqFold algorithm to search for modeling templates. Independently, the FoldMiner algorithm was used to search for templates that had structural folds similar to published coordinates of the homologous nAChR (1OED). Both SeqFold and Foldminer identified the same modeling template. The GlyRa1 sequence was aligned with this template using multiple scoring criteria. Refinement of the alignment closed gaps to produce agreement with labeling studies carried out on the homologous receptors of the superfamily. Structural assignment and refinement was achieved using Modeler. The final structure demonstrated a cavity within the core of a four-helix bundle. Residues known to be involved in modulating anesthetic potency converge on and line this cavity. This suggests that the binding sites for volatile anesthetics in the LGICs are the cavities formed within the core of transmembrane four-helix bundles.

    View details for DOI 10.1021/ci0497399

    View details for Web of Science ID 000227982800016

    View details for PubMedID 15667138

  • Comparative modeling of a GABAA alpha1 receptor using three crystal structures as templates JOURNAL OF MOLECULAR GRAPHICS & MODELLING Trudell, J. R., Bertaccini, E. 2004; 23 (1): 39-49


    We built a model of a GABAA alpha1 receptor (GABAAR) that combines the ligand binding (LBD) and the transmembrane domains (TMD). We used six steps: (1) a four-alpha helical bundle in the crystal structure of bovine cytochrome c oxidase (2OCC) was identified as a template for the TMD of a single subunit. (2) The five pore-forming alpha helices of a bacterial mechanosensitive channel (1MSL) served as a template for the pentameric ion channel. (3) Five copies of the tetrameric template from 2OCC were superimposed on 1MSL to produce a homopentamer containing 20 alpha helices arranged around a funnel-shaped central pore. (4) Five copies of the GABAAR sequence were threaded onto the alpha-helical segments of this template and inter-helical loops were generated to produce the TMD model. (5) A model of the LBD was built by threading the aligned sequence of GABAAR onto the crystal structure of the acetylcholine binding protein (1I9B). (6) The models of the LBD and the TMD were aligned along a common five-fold axis, moved together along that axis until in vdW contact, merged, and then optimized with restrained molecular dynamics. Our model corresponds closely with recently published coordinates of the acetylcholine receptor (1OED) but also explains additional features. Our model reveals structures of loops that were not visible in the cryoelectron micrograph and satisfies most labeling and mutagenesis data. It also suggests mechanisms for ligand binding transduction, ion selectivity, and anesthetic binding.

    View details for DOI 10.1016/j.jmgm.2004.03.004

    View details for Web of Science ID 000224010100004

    View details for PubMedID 15331052

  • Use of a fully simulated intensive care unit environment for critical event management training for internal medicine residents CRITICAL CARE MEDICINE Lighthall, G. K., Barr, J., Howard, S. K., Gellar, E., Sowb, Y., Bertacini, E., Gaba, D. 2003; 31 (10): 2437-2443
  • Correlation of approximate entropy, bispectral index, and spectral edge frequency 95 (SEF95) with clinical signs of "anesthetic depth" during coadministration of propofol and remifentanil ANESTHESIOLOGY Bruhn, J., Bouillon, T. W., Radulescu, L., Hoeft, A., Bertaccini, E., Shafer, S. L. 2003; 98 (3): 621-627


    Several studies relating electroencephalogram parameter values to clinical endpoints using a single (mostly hypnotic) drug at relatively low levels of central nervous system depression (sedation) have been published. However, the usefulness of a parameter derived from the electroencephalogram for clinical anesthesia largely depends on its ability to predict the response to stimuli of different intensity or painfulness under a combination of a hypnotic and an (opioid) analgesic. This study was designed to evaluate the predictive performance of spectral edge frequency 95 (SEF95), BIS, and approximate entropy for the response to increasingly intense stimuli under different concentrations of both propofol and remifentanil in the therapeutic range.Ten healthy male and ten healthy female volunteers were studied during coadministration of propofol and remifentanil. After having maintained a specific target concentration for 10 min, the depth of sedation-anesthesia was assessed using the responsiveness component of the Observer's Assessment of Alertness/Sedation (OAA/S) rating scale, which was modified by adding insertion of a laryngeal mask and laryngoscopy. The electroencephalogram derived parameters approximate entropy, bispectral index, and SEF95 were recorded just before sedation level was assessed.The prediction probability values for approximate entropy were slightly, but not significantly, better than those for bispectral index, SEF95, and the combination of drug concentrations. A much lower prediction ability was observed for tolerance of airway manipulation than for hypnotic endpoints.Approximate entropy revealed informations on hypnotic and analgesic endpoints using coadministration of propofol and remifentanil comparable to bispectral index, SEF95, and the combination of drug concentrations.

    View details for Web of Science ID 000181290800007

    View details for PubMedID 12606904

  • Non-steady state analysis of the pharmacokinetic interaction between propofol and remifentanil ANESTHESIOLOGY Bouillon, T., Bruhn, J., Radu-Radulescu, L., Bertaccini, E., Park, S., Shafer, S. 2002; 97 (6): 1350-1362


    The pharmacokinetics of both propofol and remifentanil have been described extensively. Although they are commonly administered together for clinical anesthesia, their pharmacokinetic interaction has not been investigated so far. The purpose of the current investigation was to elucidate the nature and extent of pharmacokinetic interactions between propofol and remifentanil.Twenty healthy volunteers aged 20-43 yr initially received either propofol or remifentanil alone in a stepwise incremental and decremental fashion a target controlled infusion. Thereafter, the respective second drug was infused to a fixed target concentration in the clinical range (0-4 microg/ml and 0-4 ng/ml for propofol and remifentanil, respectively) and the stepwise incremental pattern repeated. Frequent blood samples were drawn for up to 6 h for propofol and 40 min for remifentanil after the end of administration and assayed for the respective drug concentrations with gas chromatography-mass spectrometry. The time courses of the measured concentrations were fitted to standard compartmental models. Calculations were performed with NONMEM. After having established the individual population models for both drugs and an exploratory analysis for hypothesis generation, pharmacokinetic interaction was identified by including an interaction term into the population model and comparing the value of the objective function in the presence and absence of the respective term.The concentration-time courses of propofol and remifentanil were described best by a three- and two-compartment model, respectively. In the concentration range examined, remifentanil does not alter propofol pharmacokinetics. Coadministration of propofol decreases the central volume of distribution and distributional clearance of remifentanil by 41% and elimination clearance by 15%. This effect was not concentration-dependent in the examined concentration range of propofol.Coadministration of propofol decreases the bolus dose of remifentanil needed to achieve a certain plasma-effect compartment concentration but does not alter the respective maintenance infusion rates and recovery times to a clinically significant degree.

    View details for Web of Science ID 000179590500004

    View details for PubMedID 12459659

  • Molecular modelling of specific and non-specific anaesthetic interactions BRITISH JOURNAL OF ANAESTHESIA Trudell, J. R., Bertaccini, E. 2002; 89 (1): 32-40


    There has been rapid progress in molecular modelling in recent years. The convergence of improved software for molecular mechanics and dynamics, techniques for chimeric substitution and site-directed mutations, and the first x-ray structures of transmembrane ion channels have made it possible to build and test models of anaesthetic binding sites. These models have served as guides for site-directed mutagenesis and as starting points for understanding the molecular dynamics of anaesthetic-site interactions. Ligand-gated ion channels are targets for inhaled anaesthetics and alcohols in the central nervous system. The inhibitory strychnine-sensitive glycine and gamma-aminobutyric acid type A receptors are positively modulated by anaesthetics and alcohols; site-directed mutagenesis techniques have identified amino acid residues important for the action of volatile anaesthetics and alcohols in these receptors. Key questions are whether these amino acid mutations form part of alcohol- or anaesthetic-binding sites or if they alter protein stability in a way that allows anaesthetic molecules to act remotely by non-specific mechanisms. It is likely that molecular modelling will play a major role in answering these questions.

    View details for Web of Science ID 000176825400004

    View details for PubMedID 12173239

  • Meperidine exerts agonist activity at the alpha(2B)-adrenoceptor subtype Annual Meeting of the American-Society-of-Anesthesiologists Takada, K., Clark, D. J., Davies, M. F., Tonner, P. H., Krause, T. K., Bertaccini, E., Maze, M. LIPPINCOTT WILLIAMS & WILKINS. 2002: 1420–26


    The opioid agonist meperidine has actions, such as antishivering, that are more pronounced than those of other opioid agonists and that are not blocked with nonselective opioid antagonists. Agonists at the alpha(2) adrenoceptors, such as clonidine, are very effective antishivering drugs. Preliminary evidence also indicates that meperidine interacts with alpha(2) adrenoceptors. The authors therefore studied the ability of meperidine to bind and activate each of the alpha(2)-adrenoceptor subtypes in a transfected cell system.The ability of meperidine to bind to and inhibit forskolin-stimulated cyclic adenosine monophosphate formation as mediated by the three alpha(2)-adrenoceptor subtypes transiently transfected into COS-7 cells has been tested. The ability of the opioid antagonist naloxone and the alpha(2)-adrenoceptor antagonists yohimbine and RX821002 to block the analgesic action of meperidine in the hot-plate test was also assessed. The ability of meperidine to fit into the alpha(2B) adrenoceptor was assessed using molecular modeling techniques.Meperidine bound to all alpha2-adrenoceptor subtypes, with alpha(2B) having the highest affinity (alpha(2B), 8.6 +/- 0.3 microm; alpha(2C), 13.6 +/- 1.5 microm, P < 0.05; alpha(2A), 38.6 +/- 0.7 microm). Morphine was ineffective at binding to any of the receptor subtypes. Meperidine inhibited the production of forskolin-stimulated cyclic adenosine monophosphate mediated by all receptor subtypes but was most effective at the alpha(2B) adrenoceptor (alpha(2B), 0.6 microm; alpha(2A), 1.3 mm; alpha(2C), 0.3 mm), reaching the same level of inhibition (approximately 70%) as achieved with the alpha2-adrenoceptor agonist dexmedetomidine. The analgesic action of meperidine was blocked by naloxone but not by the alpha 2-adrenoceptor antagonists yohimbine and RX821002. The modeling studies demonstrated that meperidine can fit into the alpha(2B)-adrenoceptor subtype.Meperidine is a potent agonist at the alpha2 adrenoceptors at its clinically relevant concentrations, especially at the alpha(2B)-adrenoceptor subtype. Activation of the alpha(2B) receptor does not contribute significantly to the analgesic action of meperidine. This raises the possibility that some of its actions, such as antishivering, are transduced by this mechanism.

    View details for Web of Science ID 000175965500021

    View details for PubMedID 12170055

  • Molecular modelling of anesthetic binding sites in ligand-gated ion channels 6th International Conference on Molecular and Basic Mechanisms of Anesthesia Trudell, J. R., Bertaccini, E. PABST SCIENCE PUBLISHERS. 2002: 18–22
  • Molecular modelling of anesthetic binding sites in ligand-gated ion channels Molecular and Basic Mechanisms of Anesthesia, Pabst Science Publishers Trudell JR, Bertaccini, E 2002: 18-22
  • A double-blind, randomized comparison of IV lorazepam versus midazolam for sedation of ICU patients via a pharmacologic model Annual Meeting of the Society-for-Critical-Care-Medicine Barr, J., Zomorodi, K., Bertaccini, E. J., Shafer, S. L., Geller, E. LIPPINCOTT WILLIAMS & WILKINS. 2001: 286–98


    Benzodiazepines, such as lorazepam and midazolam, are frequently administered to surgical intensive care unit (ICU) patients for postoperative sedation. To date, the pharmacology of lorazepam in critically ill patients has not been described. The aim of the current study was to characterize and compare the pharmacokinetics and pharmacodynamics of lorazepam and midazolam administered as continuous intravenous infusions for postoperative sedation of surgical ICU patients.With Institutional Review Board approval, 24 consenting adult surgical patients were given either lorazepam or midazolam in a double-blind fashion (together with either intravenous fentanyl or epidural morphine for analgesia) through target-controlled intravenous infusions titrated to maintain a moderate level of sedation for 12-72 h postoperatively. Moderate sedation was defined as a Ramsay Sedation Scale score of 3 or 4. Sedation scores were measured, together with benzodiazepine plasma concentrations. Population pharmacokinetic and pharmacodynamic parameters were estimated using nonlinear mixed-effects modeling.A two-compartment model best described the pharmacokinetics of both lorazepam and midazolam. The pharmacodynamic model predicted depth of sedation for both midazolam and lorazepam with 76% accuracy. The estimated sedative potency of lorazepam was twice that of midazolam. The predicted C50,ss (plasma benzodiazepine concentrations where P(Sedation > or = ss) = 50%) values for midazolam (sedation score [SS] > or = n, where n = a Ramsay Sedation Score of 2, 3, ... 6) were 68, 101, 208, 304, and 375 ng/ml. The corresponding predicted C50,ss values for lorazepam were 34, 51, 104, 152, and 188 ng/ml, respectively. Age, fentanyl administration, and the resolving effects of surgery and anesthesia were significant covariates of benzodiazepine sedation. The relative amnestic potency of lorazepam to midazolam was 4 (observed). The predicted emergence times from sedation after a 72-h benzodiazepine infusion for light (SS = 3) and deep (SS = 5) sedation in a typical patient were 3.6 and 14.9 h for midazolam infusions and 11.9 and 31.1 h for lorazepam infusions, respectively.The pharmacology of intravenous infusions of lorazepam differs significantly from that of midazolam in critically ill patients. This results in significant delays in emergence from sedation with lorazepam as compared with midazolam when administered for ICU sedation.

    View details for Web of Science ID 000170237800003

    View details for PubMedID 11506097

  • Evidence for a common binding cavity for three general anesthetics within the GABA(A) receptor JOURNAL OF NEUROSCIENCE Jenkins, A., Greenblatt, E. P., Faulkner, H. J., Bertaccini, E., Light, A., Lin, A., Andreasen, A., Viner, A., Trudell, J. R., Harrison, N. L. 2001; 21 (6)


    The GABA(A) receptor is an important target for a variety of general anesthetics (Franks and Lieb, 1994) and for benzodiazepines such as diazepam. Specific point mutations in the GABA(A) receptor selectively abolish regulation by benzodiazepines (Rudolph et al., 1999; McKernan et al., 2000) and by anesthetic ethers (Mihic et al., 1997; Krasowski et al., 1998; Koltchine et al., 1999), suggesting the existence of discrete binding sites on the GABA(A) receptor for these drugs. Using anesthetics of different molecular size (isoflurane > halothane > chloroform) together with complementary mutagenesis of specific amino acid side chains, we estimate the volume of a proposed anesthetic binding site as between 250 and 370 A(3). The results of the "cutoff" analysis suggest a common site of action for the anesthetics isoflurane, halothane, and chloroform on the GABA(A) receptor. Moreover, the data support a crucial role for Leu232, Ser270, and Ala291 in the alpha subunit in defining the boundaries of an amphipathic cavity, which can accommodate a variety of small general anesthetic molecules.

    View details for Web of Science ID 000167422200002

    View details for PubMedID 11245705

  • Molecular modeling of ligand-gated ion channels: Progress and challenges INTERNATIONAL REVIEW OF NEUROBIOLOGY, VOL 48 Bertaccini, E., Trudell, J. R. 2001; 48: 141-166


    There has been rapid progress in molecular modeling of LGICs in recent years. The convergence of improved software for molecular mechanics/dynamics, techniques of chimeric substitution and site-directed mutations, and the first X-ray structures of transmembrane ion channels will make it possible to build reasonable models of neuronal ion channels well in advance of publication of their crystal structures. These models will not only serve as guides for future site-directed mutagenesis, but they will also be a starting point for understanding the dynamics of ion channel gating.

    View details for Web of Science ID 000170995200004

    View details for PubMedID 11526737

  • The Interface Of Molecular Modeling and Molecular Genetics: A Search for Sites of Anesthetic Action Progress in Anesthesia Mechanisms Trudell J, Bertaccini E, Eger EI, Harrison NL, Mihic SJ, Harris RA 2000; 6: 172-178
  • Evaluation of forcefields for molecular mechanics/dynamics calculations involving halogenated anesthetics. Toxicology letters Trudell, J. R., Bertaccini, E. 1998; 100-101: 413-419


    (1) Successful application of molecular mechanics and molecular dynamics calculations to the binding of halogenated anesthetics requires forcefields with correct parameters for halocarbons. (2) Unfortunately, our survey of six popular forcefields revealed that some of them provide a very poor representation of electrostatic interactions for the halogens. (3) This problem is due to poor or missing assignments of partial atomic charges to the halogen atoms. (4) We describe the forcefields most appropriate for use with halogenated anesthetics and suggest a general method for editing the assignment of partial atomic charges by performing an initial quantum mechanics calculation.

    View details for PubMedID 10049174

  • Evaluation of forcefields for molecular mechanics/dynamics calculations involving halogenated anesthetics 5th International Conference on Molecular and Cellular Mechanisms of Anaesthesia Trudell, J. R., Bertaccini, E. ELSEVIER IRELAND LTD. 1998: 413–419
  • ICU sedation: A review of its pharmacology and assessment JOURNAL OF INTENSIVE CARE MEDICINE Hill, L., Bertaccini, E., Barr, J., Geller, E. 1998; 13 (4): 174-183


    To probe the hypothesis of a lipid-mediated mechanism of general anesthetic action on a molecular level, and to help elucidate the nature of the interactions of bioactive compounds with membranes, the effects of trichloroethylene (TCE), an inhalational general anesthetic, on a dioleoylphosphatidylcholine (DOPC) lipid bilayer have been investigated by molecular dynamics (MD) simulations at 37 degrees C and 1 atm and the results compared with 31P and 2H NMR experimental studies (Ref 1). The model used included a single TCE molecule embedded in a lipid bilayer consisting of 24 DOPC molecules and an 8 A layer of explicit water of solvation in each polar head group region of the bilayer, together with constant-pressure periodic boundary conditions in three dimensions. A comparison of the bilayer properties calculated in the presence and absence of the anesthetic led to the detection of three major perturbations of the bilayer caused by the anesthetic at 1 atm: i) an increase in the ratio of the effective areas of hydrocarbon tails and the head group per lipid, predicting the tendency of lipids near the anesthetic site of action to form a hexagonal phase (HII); ii) a slight increase in the frequency of chain dihedral angles found in the gauche conformation; and iii) a significant increase in the lateral mean-square displacement of lipid molecules, an indication of increased lipid lateral diffusion and membrane fluidity. The pressure antagonism of these effects was also studied by MD simulations at pressures of 200 and 400 atm. The study of the pressure reversibility of these effects at 200 and 400 atm indicated that they were partially prevented at 200 atm and essentially blocked at 400 atm, suggesting their probable relevance to the pressure reversal effect seen with general anesthesia. These results may thus provide insights into the interaction between general anesthetics and similar small organic molecules with membranes.

    View details for Web of Science ID A1995QJ14600001

    View details for PubMedID 7779297

  • Benzodiazepine Antagonists And Their Role In Anesthesia And Critical Care Anaesthetic Pharmacology Review Bertaccini E, Geller E 1995; 3 (1): 74-81


    An 11-month-old, 11-kg infant presented to the emergency department after ingesting 130 to 150 mg/kg of elemental iron. Emesis was induced twice and the child was lavaged throughout a 4-hour period with some tablet return. An abdominal radiograph after gastrointestinal decontamination showed at least 16 whole iron tablets remaining in the stomach. Serum iron drawn 2 hours postingestion was 46.7 mumol/L. Blood glucose was 7.7 mmol/L and white blood count was 21,800 mm3. Despite a second lavage 8 hours postingestion, a large number of whole tablets were visualized in the stomach per radiograph. Whole bowel irrigation with polyethylene glycol electrolyte lavage solution (Golytely, Braintree Laboratories, Inc, Braintree, MA) was begun via nasogastric tube 14 hours after the ingestion. Serial abdominal radiographs showed tablet movement out of the stomach within 4 hours after initiating whole bowel irrigation. This case demonstrates the safety and efficacy of WBI in an infant when conventional gastrointestinal decontamination has failed.

    View details for Web of Science ID A1991FW04100016

    View details for PubMedID 1675852