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1.
J Neuroimaging ; 2024 Jun 10.
Article in English | MEDLINE | ID: mdl-38858847

ABSTRACT

BACKGROUND AND PURPOSE: Conclusions from prior literature regarding the impact of sex, age, and height on spinal cord (SC) MRI morphometrics are conflicting, while the effect of body weight on SC morphometrics has been found to be nonsignificant. The purpose of this case-control study is to assess the associations between cervical SC MRI morphometric parameters and age, sex, height, and weight to establish their potential role as confounding variables in a clinical study of people with multiple sclerosis (MS) compared to a cohort of healthy volunteers. METHODS: Sixty-nine healthy volunteers and 31 people with MS underwent cervical SC MRI at 3 Tesla field strength. Images were centered at the C3/C4 intervertebral disc and processed using Spinal Cord Toolbox v.4.0.2. Mixed-effects linear regression models were used to evaluate the effects of biological variables and disease status on morphometric parameters. RESULTS: Sex, age, and height had significant effects on cord and gray matter (GM) cross-sectional area (CSA) as well as the GM:cord CSA ratio. There were no significant effects of body weight on morphometric parameters. The effect of MS disease duration on cord CSA in the C4 level was significant when controlling for all other variables. CONCLUSIONS: Studies of disease-related changes in SC morphometry should control for sex, age, and height to account for physiological variation.

2.
Behav Cogn Psychother ; 52(1): 1-13, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37737054

ABSTRACT

BACKGROUND AND AIMS: People with hoarding behaviours often struggle to engage in treatment. This study aimed to explore the experiences of a sample of people who identify as engaging in hoarding behaviours and who are seeking support. Exploring motivation to seek help, the barriers those who hoard face in accessing support and what facilitates accepting help, can aid understanding of how best to intervene. METHOD: Eight individuals who self-identified as seeking help in relation to hoarding behaviours were recruited via social media and support groups. Interviews were conducted by telephone or video call, before being transcribed and analysed using interpretative phenomenological analysis. RESULTS: Participants described complex help-seeking narratives and reported continued ambivalence about addressing their hoarding behaviours. The four group experiential themes identified were Wrestling with identity; Who can I trust?; Services don't fit; and Being overlooked: 'they're too busy looking at the thing, not the person'. Difficulties trusting others and services were identified; services were experienced as rejecting and many participants sought help for problems other than their hoarding. Problems accessing appropriate help for hoarding were predominant in the narratives, although participants who had accessed peer support described this as valuable. CONCLUSIONS: There are both internal (e.g. fear of judgement; feeling overwhelmed) and external (e.g. service gaps) barriers that make finding useful help for hoarding behaviours very difficult. Services may facilitate those seeking help by taking a compassionate and person-centred approach to hoarding problems.


Subject(s)
Hoarding , Humans , Hoarding/therapy , Emotions , Affect , Trust , Qualitative Research
4.
J Pharmacol Exp Ther ; 383(3): 238-245, 2022 12.
Article in English | MEDLINE | ID: mdl-36167415

ABSTRACT

Although propofol is among the most commonly administered general anesthetics, its mechanism of action is not fully understood. It has been hypothesized that propofol acts via a similar mechanism as (R)-ethyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate (etomidate) by binding within the GABAA receptor transmembrane receptor domain at the two ß +/α - subunit interfaces with resultant positive allosteric modulation. To test this hypothesis, we leveraged the ability of diazepam to bind to those sites and act as a competitive antagonist. We used oocyte-expressed α 1 ß 3 γ 2L GABAA receptors to define the actions of diazepam (± flumazenil) on currents activated or potentiated by propofol and a zebrafish activity assay to define the impact of diazepam and flumazenil on propofol-induced anesthesia. We found that diazepam increased the amplitudes of GABAA receptor-mediated currents at nanomolar concentrations but reduced them at micromolar concentrations. The current amplitude changes produced by nanomolar diazepam concentrations were inhibited by flumazenil whereas those produced by micromolar diazepam concentrations were not. Studies of agonist potentiation showed that the micromolar inhibitory action of diazepam was surmountable by high concentrations of propofol and produced a rightward shift in the propofol concentration-response curve characterized by a Schild slope not statistically significantly different from 1, consistent with competition between diazepam and propofol. Although micromolar concentrations of diazepam (plus flumazenil) similarly reduced GABAA receptor currents modulated by propofol and etomidate, it only reduced the anesthetic actions of etomidate. We conclude that while both propofol and etomidate can modulate GABAA receptors by binding to the ß +/α - subunit interfacial sites, propofol-induced anesthesia likely involves additional target sites. SIGNIFICANCE STATEMENT: Although the drug combination of diazepam and flumazenil reverses the GABAA receptor positive modulatory actions of both propofol and (R)-ethyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate (etomidate), it only reverses the in vivo anesthetic actions of etomidate. These results strongly suggest that distinct mechanisms of action account for the anesthetic actions of these two commonly administered anesthetic agents.


Subject(s)
Etomidate , Propofol , Animals , Receptors, GABA-A/metabolism , Propofol/pharmacology , Diazepam/pharmacology , Zebrafish/metabolism , Etomidate/pharmacology , gamma-Aminobutyric Acid/pharmacology
5.
Ther Adv Endocrinol Metab ; 13: 20420188211058583, 2022.
Article in English | MEDLINE | ID: mdl-35186251

ABSTRACT

Cushing's syndrome (CS) is an endocrine disease characterized by excessive adrenocortical steroid production. One of the mainstay pharmacological treatments for CS are steroidogenesis enzyme inhibitors, including the antifungal agent ketoconazole along with metyrapone, mitotane, and aminoglutethimide. Recently, osilodrostat was added to this drug class and approved by the US Food and Drug Administration (FDA) for the treatment of Cushing's Disease. Steroidogenesis enzyme inhibitors inhibit various enzymes along the cortisol biosynthetic pathway and may be used preoperatively to lower cortisol levels and reduce surgical risk associated with tumor resection or postoperatively when surgery and/or radiation therapies are not curative. Because their selectivities for steroidogenic enzymes vary, they may even be administered in combination to achieve relatively rapid control of severe hypercortisolemia. Unfortunately, all currently available inhibitors are accompanied by serious adverse side effects that limit dosing and often result in treatment failures. Although more commonly known as a general anesthetic induction agent, etomidate is another member of the steroidogenesis enzyme inhibitor drug class. It suppresses cortisol production primarily by inhibiting 11ß-hydroxylase and is the only inhibitor that may be given parenterally. However, the sedative-hypnotic actions of etomidate limit its use as an acute management option for CS. Thus, some have recommended that it be used only in intensive care settings. In this review, we discuss the initial development of etomidate as an anesthetic agent, its subsequent development as a treatment for CS, and the recent advances in dosing and drug development that dissociate sedative-hypnotic and adrenostatic drug actions to facilitate CS treatment in non-critical care settings.

6.
Br J Pharmacol ; 178(24): 4842-4858, 2021 12.
Article in English | MEDLINE | ID: mdl-34386973

ABSTRACT

BACKGROUND AND PURPOSE: In addition to binding to the classical high-affinity extracellular benzodiazepine binding site of the GABAA receptor, some benzodiazepines occupy transmembrane inter-subunit anaesthetic sites that bind etomidate (ß+ /α- sites) or the barbiturate derivative R-mTFD-MPAB (α+ /ß- and γ+ /ß- sites). We aimed to define the functional effects of these interactions on GABAA receptor activity and animal behaviour. EXPERIMENTAL APPROACH: With flumazenil blocking classical high-affinity extracellular benzodiazepine site effects, modulation of GABA-activated currents by diazepam, midazolam and flurazepam was measured electrophysiologically in wildtype and M2-15' mutant α1 ß3 γ2L GABAA receptors. Zebrafish locomotive activity was also assessed in the presence of each benzodiazepine plus flumazenil. KEY RESULTS: In the presence of flumazenil, micromolar concentrations of diazepam and midazolam both potentiated and inhibited wildtype GABAA receptor currents. ß3 N265M (M2-15' in the ß+ /α- sites) and α1 S270I (M2-15' in the α+ /ß- site) mutations reduced or abolished potentiation by these drugs. In contrast, the γ2 S280W mutation (M2-15' in the γ+ /ß- site) abolished inhibition. Flurazepam plus flumazenil only inhibited wildtype receptor currents, an effect unaltered by M2-15' mutations. In the presence of flumazenil, zebrafish locomotion was enhanced by diazepam at concentrations up to 30 µM and suppressed at 100 µM, suppressed by midazolam and enhanced by flurazepam. CONCLUSIONS AND IMPLICATIONS: Benzodiazepine binding to transmembrane anaesthetic binding sites of the GABAA receptor can produce positive or negative modulation manifesting as decreases or increases in locomotion, respectively. Selectivity for these sites may contribute to the distinct GABAA receptor and behavioural actions of different benzodiazepines, particularly at high (i.e. anaesthetic) concentrations.


Subject(s)
Anesthetics , Receptors, GABA-A , Animals , Anesthetics/pharmacology , Benzodiazepines/metabolism , Benzodiazepines/pharmacology , Binding Sites , Flumazenil/chemistry , Flumazenil/pharmacology , Receptors, GABA-A/metabolism , Zebrafish/metabolism
7.
Anesthesiology ; 133(3): 583-594, 2020 09.
Article in English | MEDLINE | ID: mdl-32541553

ABSTRACT

BACKGROUND: Recent cryo-electron microscopic imaging studies have shown that in addition to binding to the classical extracellular benzodiazepine binding site of the α1ß3γ2L γ-aminobutyric acid type A (GABAA) receptor, diazepam also binds to etomidate binding sites located in the transmembrane receptor domain. Because such binding is characterized by low modulatory efficacy, the authors hypothesized that diazepam would act in vitro and in vivo as a competitive etomidate antagonist. METHODS: The concentration-dependent actions of diazepam on 20 µM etomidate-activated and 6 µM GABA-activated currents were defined (in the absence and presence of flumazenil) in oocyte-expressed α1ß3γ2L GABAA receptors using voltage clamp electrophysiology. The ability of diazepam to inhibit receptor labeling of purified α1ß3γ2L GABAA receptors by [H]azietomidate was assessed in photoaffinity labeling protection studies. The impact of diazepam (in the absence and presence of flumazenil) on the anesthetic potencies of etomidate and ketamine was compared in a zebrafish model. RESULTS: At nanomolar concentrations, diazepam comparably potentiated etomidate-activated and GABA-activated GABAA receptor peak current amplitudes in a flumazenil-reversible manner. The half-maximal potentiating concentrations were 39 nM (95% CI, 27 to 55 nM) and 26 nM (95% CI, 16 to 41 nM), respectively. However, at micromolar concentrations, diazepam reduced etomidate-activated, but not GABA-activated, GABAA receptor peak current amplitudes in a concentration-dependent manner with a half-maximal inhibitory concentration of 9.6 µM (95% CI, 7.6 to 12 µM). Diazepam (12.5 to 50 µM) also right-shifted the etomidate-concentration response curve for direct activation without reducing the maximal response and inhibited receptor photoaffinity labeling by [H]azietomidate. When administered with flumazenil, 50 µM diazepam shifted the etomidate (but not the ketamine) concentration-response curve for anesthesia rightward, increasing the etomidate EC50 by 18-fold. CONCLUSIONS: At micromolar concentrations and in the presence of flumazenil to inhibit allosteric modulation via the classical benzodiazepine binding site of the GABAA receptor, diazepam acts as an in vitro and in vivo competitive etomidate antagonist.


Subject(s)
Diazepam/pharmacology , Etomidate/antagonists & inhibitors , Hypnotics and Sedatives/pharmacology , Receptors, GABA/drug effects , Animals , Drug Antagonism , Hypnotics and Sedatives/antagonists & inhibitors , Models, Animal , Zebrafish
8.
Pharmacol Rep ; 72(1): 260-266, 2020 Feb.
Article in English | MEDLINE | ID: mdl-32016849

ABSTRACT

BACKGROUND: Many sedative-hypnotic agents are thought to act by positively modulating γ-aminobutyric acid type A (GABAA) receptors. However, for many agents, the location(s) of the binding site(s) responsible for such receptor modulation is uncertain. We previously developed a low efficacy ligand (naphthalene-etomidate) that binds within a homologous set of hydrophobic cavities located at GABAA receptor subunit interfaces in the transmembrane domain, and thus acts as a competitive antagonist for higher efficacy sedative-hypnotics that also bind to these sites. In this report, we describe studies using this compound as a pharmacological screening tool to test whether sedative-hypnotics representing a range of chemical classes can modulate GABAA receptors by binding within these receptor cavities. METHODS: The impact of naphthalene-etomidate on GABA-evoked currents that were mediated by oocyte-expressed α1ß3γ2L GABAA receptors and potentiated by muscimol, alphaxalone, 2,2,2-trichloroethanol, isoflurane, AA29504, loreclezole, or diazepam was quantified using electrophysiological techniques. RESULTS: Naphthalene-etomidate (300 µM) significantly reduced GABAA receptor currents potentiated by alphaxalone (by 22 ± 11%), 2,2,2-trichloroethanol (by 23 ± 6%), isoflurane (by 32 ± 10%), AA29504 (by 41 ± 6%), loreclezole (by 43 ± 9%), but significantly increased those potentiated by muscimol (by 26 ± 11%). Naphthalene-etomidate significantly increased currents potentiated by a low (1 µM) diazepam concentration (by 56 ± 14%) while reducing those potentiated by a high (100 µM) diazepam concentration (by 11 ± 7%). CONCLUSIONS: Our results suggest that many (but not all) sedative-hypnotics are capable of positively modulating the GABAA receptor by binding within a common set of hydrophobic cavities.


Subject(s)
Etomidate/pharmacology , GABA-A Receptor Antagonists/pharmacology , Hypnotics and Sedatives/administration & dosage , Naphthalenes/pharmacology , Animals , Etomidate/administration & dosage , Female , GABA-A Receptor Antagonists/administration & dosage , Humans , Hydrophobic and Hydrophilic Interactions , Hypnotics and Sedatives/pharmacology , Ligands , Naphthalenes/administration & dosage , Receptors, GABA-A , Xenopus laevis , gamma-Aminobutyric Acid/metabolism
9.
Trends Pharmacol Sci ; 40(11): 809-811, 2019 11.
Article in English | MEDLINE | ID: mdl-31623940

ABSTRACT

All currently available general anesthetics produce potentially deadly side effects. Unfortunately, few approaches have been developed to design safer ones, despite important advances in anesthetic mechanisms research. Cayla and colleagues recently showed that computational methods can be used to identify anesthetic lead compounds devoid of specific side effects.


Subject(s)
Anesthetics , Etomidate , Drug Discovery
10.
BMC Pharmacol Toxicol ; 20(1): 48, 2019 08 05.
Article in English | MEDLINE | ID: mdl-31383012

ABSTRACT

BACKGROUND: Cushing's syndrome is an endocrine disorder characterized by the overproduction of adrenocortical steroids. Steroidogenesis enzyme inhibitors are the mainstays of pharmacological treatment. Unfortunately, they produce significant side effects. Among the most potent inhibitors is the general anesthetic etomidate whose GABAA receptor-mediated sedative-hypnotic actions restrict use. In this study, we defined the sedative-hypnotic and steroidogenesis inhibiting actions of etomidate and four phenyl-ring substituted etomidate analogs (dimethoxy-etomidate, isopropoxy-etomidate, naphthalene-etomidate, and naphthalene (2)-etomidate) that possess negligible GABAA receptor modulatory activities. METHODS: In the first set of experiments, male Sprague-Dawley rats were assessed for loss of righting reflexes (LoRR) after receiving intravenous boluses of either etomidate (1 mg/kg) or an etomidate analog (40 mg/kg). In the second set of experiments, rats were assessed for LoRR and their abilities to produce adrenocortical and androgenic steroids after receiving 2-h infusions (0.5 mg kg- 1 min- 1) of either etomidate or an etomidate analog. RESULTS: All rats that received etomidate boluses or infusions had LoRR that persisted for minutes or hours, respectively. In contrast, no rat that received an etomidate analog had LoRR. Compared to rats in the vehicle control group, rats that received etomidate analog infusions had plasma corticosterone and aldosterone concentrations that were reduced by 80-84% and 68-94%, respectively. Rats that received etomidate infusions had plasma corticosterone and aldosterone concentrations that were also significantly reduced (by 92 and 96%, respectively). Rats that received etomidate or isopropoxy-etomidate had significant reductions (90 and 57%, respectively) in plasma testosterone concentrations whereas those that received naphthalene-etomidate had significant increases (1400%) in plasma dehydroepiandrosterone concentrations. Neither etomidate nor any etomidate analog significantly affected plasma androstenedione and dihydrotestosterone concentrations. CONCLUSIONS: Our studies demonstrate that the four phenyl-ring substituted etomidate analogs form a novel class of compounds that are devoid of sedative-hypnotic activities and suppress plasma concentrations of adrenocortical steroids but vary in their effects on plasma concentrations of androgenic steroids.


Subject(s)
Etomidate/analogs & derivatives , Hypnotics and Sedatives/pharmacology , Steroid Synthesis Inhibitors/pharmacology , Animals , Etomidate/chemistry , Etomidate/pharmacology , Hypnotics and Sedatives/chemistry , Male , Rats , Rats, Sprague-Dawley , Receptors, GABA-A/drug effects , Reflex/drug effects , Steroid Synthesis Inhibitors/chemistry , Steroids/blood
11.
Anesthesiology ; 131(2): 287-304, 2019 08.
Article in English | MEDLINE | ID: mdl-31166238

ABSTRACT

BACKGROUND: The etomidate analog ABP-700 produces involuntary muscle movements that could be manifestations of seizures. To define the relationship (if any) between involuntary muscle movements and seizures, electroencephalographic studies were performed in Beagle dogs receiving supra-therapeutic (~10× clinical) ABP-700 doses. γ-aminobutyric acid type A (GABAA) and glycine receptor studies were undertaken to test receptor inhibition as the potential mechanism for ABP-700 seizures. METHODS: ABP-700 was administered to 14 dogs (6 mg/kg bolus followed by a 2-h infusion at 1 mg · kg(-1) · min(-1), 1.5 mg · kg(-1) · min(-1), or 2.3 mg · kg(-1) · min(-1)). Involuntary muscle movements were documented, electroencephalograph was recorded, and plasma ABP-700 and CPM-acid concentrations were measured during and after ABP-700 administration. The concentration-dependent modulatory actions of ABP-700 and CPM-acid were defined in oocyte-expressed α1ß3γ2L GABAA and α1ß glycine receptors (n = 5 oocytes/concentration) using electrophysiologic techniques. RESULTS: ABP-700 produced both involuntary muscle movements (14 of 14 dogs) and seizures (5 of 14 dogs). However, these phenomena were temporally and electroencephalographically distinct. Mean peak plasma concentrations were (from lowest to highest dosed groups) 35 µM, 45 µM, and 102 µM (ABP-700) and 282 µM, 478 µM, and 1,110 µM (CPM-acid). ABP-700 and CPM-acid concentration-GABAA receptor response curves defined using 6 µM γ-aminobutyric acid exhibited potentiation at low and/or intermediate concentrations and inhibition at high ones. The half-maximal inhibitory concentrations of ABP-700 and CPM-acid defined using 1 mM γ-aminobutyric acid were 770 µM (95% CI, 590 to 1,010 µM) and 1,450 µM (95% CI, 1,340 to 1,560 µM), respectively. CPM-acid similarly inhibited glycine receptors activated by 1 mM glycine with a half-maximal inhibitory concentration of 1,290 µM (95% CI, 1,240 to 1,330 µM). CONCLUSIONS: High dose ABP-700 infusions produce involuntary muscle movements and seizures in Beagle dogs via distinct mechanisms. CPM-acid inhibits both GABAA and glycine receptors at the high (~100× clinical) plasma concentrations achieved during the dog studies, providing a plausible mechanism for the seizures.


Subject(s)
Etomidate/analogs & derivatives , Etomidate/pharmacology , Hypnotics and Sedatives/pharmacology , Muscle, Skeletal/drug effects , Muscle, Skeletal/physiopathology , Seizures/chemically induced , Animals , Disease Models, Animal , Dogs , Dose-Response Relationship, Drug , Electroencephalography/methods , Female , Male
12.
Ther Adv Med Oncol ; 11: 1758835918818335, 2019.
Article in English | MEDLINE | ID: mdl-30671144

ABSTRACT

BACKGROUND: With increasing numbers of oncology biosimilars in the approval pipeline, it is important to investigate oncology clinicians' understanding of biosimilars and what information they need prior to adoption. METHODS: Between January and May 2018, 77 oncology clinicians (52 physicians, 16 pharmacists, and 9 advanced practice providers) completed a survey covering three domains: clinician understanding, prescription preferences, and patient involvement. An in-depth interview was designed based on themes identified in the first 50 surveys: cost, safety and efficacy, patient preference, and disease stage. Participants were chosen to participate in the interview based on outlying responses to survey questions. RESULTS: When asked to define a biosimilar, 74% (57/77) of respondents could not give a satisfactory definition, and 40.3% (31/77) considered a biosimilar the same as a generic drug. The most important factor in biosimilar prescription was safety and efficacy (4.51 out of 5) followed closely by cost differences (4.34 out of 5). A 40% increase (53.2-94.8%) in clinicians' prescribing likelihood was seen after a biosimilar is designated as interchangeable. Participants in this study were split regarding the importance of shared decision-making with patients [50.7% (39/77) important or extremely important, 39.0% (30/77) somewhat or not at all important]. Clinicians were also split concerning the role that pharmacists should play in the decision to prescribe or substitute biosimilars. CONCLUSION: Understanding of biosimilars is low, and educational needs are high. The information that clinicians deem important to assess, such as safety, efficacy and cost, will need to be provided before they are comfortable prescribing biosimilars.

13.
Anesthesiology ; 129(5): 959-969, 2018 11.
Article in English | MEDLINE | ID: mdl-30052529

ABSTRACT

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Naphthalene-etomidate, an etomidate analog containing a bulky phenyl ring substituent group, possesses very low γ-aminobutyric acid type A (GABAA) receptor efficacy and acts as an anesthetic-selective competitive antagonist. Using etomidate analogs containing phenyl ring substituents groups that range in volume, we tested the hypothesis that this unusual pharmacology is caused by steric hindrance that reduces binding to the receptor's open state. METHODS: The positive modulatory potencies and efficacies of etomidate and phenyl ring-substituted etomidate analogs were electrophysiology defined in oocyte-expressed α1ß3γ2L GABAA receptors. Their binding affinities to the GABAA receptor's two classes of transmembrane anesthetic binding sites were assessed from their abilities to inhibit receptor labeling by the site-selective photolabels [H]azi-etomidate and tritiated R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid. RESULTS: The positive modulatory activities of etomidate and phenyl ring-substituted etomidate analogs progressively decreased with substituent group volume, reflecting significant decreases in both potency (P = 0.005) and efficacy (P < 0.0001). Affinity for the GABAA receptor's two ß - α anesthetic binding sites similarly decreased with substituent group volume (P = 0.003), whereas affinity for the receptor's α - ß/γ - ß sites did not (P = 0.804). Introduction of the N265M mutation, which is located at the ß - α binding sites and renders GABAA receptors etomidate-insensitive, completely abolished positive modulation by naphthalene-etomidate. CONCLUSIONS: Steric hindrance selectively reduces phenyl ring-substituted etomidate analog binding affinity to the two ß - α anesthetic binding sites on the GABAA receptor's open state, suggesting that the binding pocket where etomidate's phenyl ring lies becomes smaller as the receptor isomerizes from closed to open.


Subject(s)
Anesthetics, Intravenous/pharmacology , Etomidate/pharmacology , Receptors, GABA/metabolism , Animals , Cell Culture Techniques , Humans , Oocytes , Receptors, GABA/drug effects , Xenopus
14.
Methods Enzymol ; 603: 153-169, 2018.
Article in English | MEDLINE | ID: mdl-29673523

ABSTRACT

All currently available general anesthetic agents possess potentially lethal side effects requiring their administration by highly trained clinicians. Among these agents is etomidate, a highly potent imidazole-based intravenous sedative-hypnotic that deleteriously suppresses the synthesis of adrenocortical steroids in a manner that is both potent and persistent. We developed two distinct strategies to design etomidate analogs that retain etomidate's potent hypnotic activity, but produce less adrenocortical suppression than etomidate. One strategy seeks to reduce binding to 11ß-hydroxylase, a critical enzyme in the steroid biosynthetic pathway, which is potently inhibited by etomidate. The other strategy seeks to reduce the duration of adrenocortical suppression after etomidate administration by modifying the drug's structure to render it susceptible to rapid metabolism by esterases. In this chapter, we describe the methods used to evaluate the hypnotic and adrenocortical inhibitory potencies of two lead compounds designed using the aforementioned strategies. Our purpose is to provide a case study for the development of novel analogs of existing drugs with reduced side effects.


Subject(s)
Anesthetics, Intravenous/pharmacology , Etomidate/pharmacology , Propanolamines/pharmacology , Receptors, GABA-A/chemistry , Remifentanil/pharmacology , Steroid 11-beta-Hydroxylase/chemistry , Adrenal Cortex/drug effects , Adrenal Cortex/metabolism , Adrenocorticotropic Hormone/pharmacology , Anesthetics, Intravenous/chemical synthesis , Animals , Binding Sites , Biotransformation , Drug Discovery , Etomidate/analogs & derivatives , Etomidate/chemical synthesis , Hypnosis, Anesthetic/methods , Hypnotics and Sedatives/chemical synthesis , Hypnotics and Sedatives/pharmacology , Larva/drug effects , Larva/physiology , Molecular Docking Simulation , Propanolamines/chemical synthesis , Protein Binding , Rana pipiens , Rats , Rats, Sprague-Dawley , Receptors, GABA-A/metabolism , Reflex, Righting/drug effects , Reflex, Righting/physiology , Remifentanil/chemical synthesis , Steroid 11-beta-Hydroxylase/metabolism , Structure-Activity Relationship
15.
J Pharmacol Exp Ther ; 364(2): 229-237, 2018 02.
Article in English | MEDLINE | ID: mdl-29203576

ABSTRACT

Cushing's syndrome is characterized by the overproduction of adrenocortical steroids. Steroidogenesis inhibitors are mainstays of medical therapy for Cushing's syndrome; unfortunately, adverse side effects and treatment failures are common with currently available drugs. The general anesthetic induction agent etomidate is among the most potent inhibitors of adrenocortical steroidogenesis. However, its use as a treatment of Cushing's syndrome is complicated by its sedative-hypnotic activity and ability to produce myoclonus, central nervous system actions thought to be mediated by the GABAA receptor. Here, we describe the pharmacology of the novel etomidate analog (R)-ethyl 1-(1-(3,5-dimethoxyphenyl)ethyl)-1H-imidazole-5-carboxylate (dimethoxy-etomidate). In contrast to etomidate, dimethoxy-etomidate minimally enhanced GABA-evoked GABAA receptor-mediated currents even at a near-saturating aqueous concentration. In Sprague-Dawley rats, dimethoxy-etomidate's potency for producing loss of righting reflexes-an animal model of sedation/hypnosis-was 2 orders of magnitude lower than that of etomidate, and it did not produce myoclonus. However, similar to etomidate, dimethoxy-etomidate potently suppressed adrenocortical steroid synthesis primarily by inhibiting 11ß-hydroxylase. [3H]etomidate binding to rat adrenocortical membranes was inhibited by dimethoxy-etomidate in a biphasic manner with IC50 values of 8.2 and 3970 nM, whereas that by etomidate was monophasic with an IC50 of 22 nM. Our results demonstrate that, similar to etomidate, dimethoxy-etomidate potently and dose-dependently suppresses adrenocortical steroid synthesis by inhibiting 11ß-hydroxylase. However, it is essentially devoid of etomidate's GABAA receptor positive modulatory and sedative-hypnotic activities and produces no myoclonus, providing proof of concept for the design of etomidate analogs without important central nervous system actions for the pharmacologic treatment of Cushing's syndrome.


Subject(s)
Etomidate/analogs & derivatives , Etomidate/pharmacology , Steroids/biosynthesis , Animals , Electrophysiological Phenomena/drug effects , Etomidate/chemistry , Male , Movement/drug effects , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship , gamma-Aminobutyric Acid/pharmacology
16.
Diagn Progn Res ; 2: 18, 2018.
Article in English | MEDLINE | ID: mdl-31093566

ABSTRACT

BACKGROUND: In recent years, there has been increasing focus on the earlier detection of deterioration in the clinical condition of hospital patients with the aim of instigating earlier treatment to reverse this deterioration and prevent adverse outcomes. This is especially important in the ED, a dynamic environment with large volumes of undifferentiated patients, which carries inherent patient risk. SNAP40 is an innovative medical-grade device that can be worn on the upper arm that continuously monitors patients' vital signs including relative changes in systolic blood pressure, respiratory rate, heart rate, movement, blood oxygen saturation and temperature. It uses automated risk analysis to potentially allow clinical staff to easily and quickly identify high-risk patients. The aim of this study is to investigate whether the SNAP40 device is able to identify deterioration in the vital sign physiology of an ED patient earlier than current standard monitoring and observation charting techniques. METHODS/DESIGN: Single centre, teaching hospital ED open label, prospective, observational cohort study recruiting 250 high acuity participants aged 16 years or over presenting to the ED. Participants will be approached and enrolled in the ED and after consent will have the SNAP40 wearable monitoring device attached which will be used alongside standard care monitoring. Participants will be observed throughout their time in the ED. Any SNAP40 device alarm, standard monitoring alarms or standard practice vital sign observations indicating a deterioration in a patient's vital sign physiology (defined as an increase in NEWS score) will be recorded. Primary outcome is time to detection of deterioration. Secondary outcomes include staff time spent performing observations and responding to standard monitoring alarms, clinical escalation of care when deterioration is detected and participants and staff rating of experience of both SNAP40 and current monitoring. DISCUSSION: The SNAP40-ED study aims to recruit 250 patients. It will be the first study to compare the ability of a novel ambulatory monitoring device to detect deterioration compared to standard care in the ED. It may allow the earlier detection of deterioration in the clinical condition of ED patients and therefore earlier treatment to reverse this deterioration and prevent adverse outcomes. TRIAL REGISTRATION: NCT03179267 ClinicalTrials.gov. Registered on June 17, 2017.

17.
Anesthesiology ; 127(5): 824-837, 2017 11.
Article in English | MEDLINE | ID: mdl-28857763

ABSTRACT

BACKGROUND: The authors characterized the γ-aminobutyric acid type A receptor pharmacology of the novel etomidate analog naphthalene-etomidate, a potential lead compound for the development of anesthetic-selective competitive antagonists. METHODS: The positive modulatory potencies and efficacies of etomidate and naphthalene-etomidate were defined in oocyte-expressed α1ß3γ2L γ-aminobutyric acid type A receptors using voltage clamp electrophysiology. Using the same technique, the ability of naphthalene-etomidate to reduce currents evoked by γ-aminobutyric acid alone or γ-aminobutyric acid potentiated by etomidate, propofol, pentobarbital, and diazepam was quantified. The binding affinity of naphthalene-etomidate to the transmembrane anesthetic binding sites of the γ-aminobutyric acid type A receptor was determined from its ability to inhibit receptor photoaffinity labeling by the site-selective photolabels [H]azi-etomidate and R-[H]5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid. RESULTS: In contrast to etomidate, naphthalene-etomidate only weakly potentiated γ-aminobutyric acid-evoked currents and induced little direct activation even at a near-saturating aqueous concentration. It inhibited labeling of γ-aminobutyric acid type A receptors by [H]azi-etomidate and R-[H]5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid with similar half-maximal inhibitory concentrations of 48 µM (95% CI, 28 to 81 µM) and 33 µM (95% CI, 20 to 54 µM). It also reduced the positive modulatory actions of anesthetics (propofol > etomidate ~ pentobarbital) but not those of γ-aminobutyric acid or diazepam. At 300 µM, naphthalene-etomidate increased the half-maximal potentiating propofol concentration from 6.0 µM (95% CI, 4.4 to 8.0 µM) to 36 µM (95% CI, 17 to 78 µM) without affecting the maximal response obtained at high propofol concentrations. CONCLUSIONS: Naphthalene-etomidate is a very low-efficacy etomidate analog that exhibits the pharmacology of an anesthetic competitive antagonist at the γ-aminobutyric acid type A receptor.


Subject(s)
Binding, Competitive/physiology , Etomidate/analogs & derivatives , Etomidate/metabolism , GABA Antagonists/metabolism , Receptors, GABA-A/metabolism , Animals , Binding, Competitive/drug effects , Dose-Response Relationship, Drug , Etomidate/pharmacology , Female , GABA Antagonists/pharmacology , Naphthalenes/chemistry , Naphthalenes/metabolism , Naphthalenes/pharmacology , Oocytes , Treatment Outcome , Xenopus laevis , gamma-Aminobutyric Acid/metabolism , gamma-Aminobutyric Acid/pharmacology
18.
Healthc (Amst) ; 4(3): 155-9, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27637820

ABSTRACT

BACKGROUND: Many view advanced primary care models such as the patient-centered medical home as foundational for accountable care organizations (ACOs), but it remains unclear how these two delivery reforms are complementary and how they may produce conflict. The objective of this study was to identify how joining an ACO could help or hinder a primary care practice's efforts to deliver high-quality care. METHODS: This qualitative study involved interviews with a purposive sample of 32 early adopters of advanced primary care and/or ACO models, drawn from across the U.S. and conducted in mid-2014. Interview notes were coded using qualitative data analysis software, permitting topic-specific queries which were then summarized. RESULTS: Respondents perceived many potential benefits of joining an ACO, including care coordination staff, data analytics, and improved communication with other providers. However, respondents were also concerned about added "bureaucratic" requirements, referral restrictions, and a potential inability to recoup investments in practice improvements. CONCLUSIONS: Interviewees generally thought joining an ACO could complement a practice's efforts to deliver high-quality care, yet noted some concerns that could undermine these synergies. Both the advantages and disadvantages of joining an ACO seemed exacerbated for small practices, since they are most likely to benefit from additional resources yet are most likely to chafe under added bureaucratic requirements. IMPLICATIONS: Our identification of the potential pros and cons of joining an ACO may help providers identify areas to examine when weighing whether to enter into such an arrangement, and may help ACOs identify potential areas for improvement.


Subject(s)
Accountable Care Organizations/standards , Attitude of Health Personnel , Patient-Centered Care/standards , Physicians, Primary Care , Quality of Health Care/organization & administration , Humans , Interviews as Topic , Qualitative Research , United States
19.
Health Aff (Millwood) ; 33(5): 807-14, 2014 May.
Article in English | MEDLINE | ID: mdl-24799578

ABSTRACT

Millions of uninsured people use health care services every year. We estimated providers' uncompensated care costs in 2013 to be between $74.9 billion and $84.9 billion. We calculated that in the aggregate, at least 65 percent of providers' uncompensated care costs were offset by government payments designed to cover the costs. Medicaid and Medicare were the largest sources of such government payments, providing $13.5 billion and $8.0 billion, respectively. Anticipating fewer uninsured people and lower levels of uncompensated care, the Affordable Care Act reduces certain Medicare and Medicaid payments. Such cuts in government funding of uncompensated care could pose challenges to some providers, particularly in states that have not adopted the Medicaid expansion or where implementation of health care reform is proceeding slowly.


Subject(s)
Medically Uninsured/statistics & numerical data , Patient Protection and Affordable Care Act/economics , Uncompensated Care/economics , Cost Control/economics , Financing, Government/economics , Humans , Medicaid/economics , Medicare/economics , Reimbursement Mechanisms/economics , Safety-net Providers/economics , United States
20.
Percept Mot Skills ; 114(1): 217-35, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22582690

ABSTRACT

At present, a commercially available device (the 8-coil Shakti) claims to produce weak and complex magnetic fields that alter neurobiological processes. The effects of the Shakti on emotional responses to photographs that varied on emotional valence were investigated. Participants (N = 37) were exposed to either 30 min, of magnetic fields or a sham condition and rated their emotional reactions to a set of 54 color photographs. Although participants indicated significantly different emotional responses to images with distinct emotional valences, exposure to magnetic fields did not affect these responses, nor significantly interact with image emotional valence. Although the device's "amygdala signal" had no effect on the emotive response to images in this study, additional investigations examining the effects of weak and complex magnetic fields on various aspects of perception and cognition are warranted.


Subject(s)
Emotions , Magnetic Field Therapy/instrumentation , Pattern Recognition, Visual , Adolescent , Amygdala/physiology , CD-ROM , Emotions/physiology , Equipment Design , Female , Humans , Male , Pattern Recognition, Visual/physiology , Software , Therapy, Computer-Assisted/instrumentation , Young Adult
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