Publications by authors named "Andrew J Boileau"

7 Publications

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Use of cannabinoids for the treatment of patients with post-traumatic stress disorder.

J Basic Clin Physiol Pharmacol 2021 Mar 4. Epub 2021 Mar 4.

Department of Anatomy, Saba University School of Medicine, The Bottom, Saba, Caribbean Netherlands.

Objectives: Post-traumatic Stress Disorder (PTSD) is a diagnosis of extreme anxiety caused by a traumatic event. Less than 10% of individuals who have experienced severe trauma will develop this disorder. Treatment options include various psychotherapies, but not all patients respond to them. Different pharmacological approaches have been explored as potential adjuvants, including using cannabinoids to target the endocannabinoid system to reduce the symptoms and enhance extinction training over the associated fear memories. This review was aimed to determine the effects of using cannabinoids for treatment of PTSD.

Content: For this review, four cohort studies, four randomized clinical trials, one case report, and one case series were obtained from PubMed within the last 10 years. Cannabis extracts, tetrahydrocannabinol (THC) and cannabidiol (CBD), and synthetic cannabinoids were used in the studies to target the cannabinoid receptors 1 and 2. Cannabinoids were shown to improve overall PTSD symptoms, including sleep quality and quantity, hyperarousal, and treatment-resistant nightmares. When participants were undergoing extinction training, cannabinoids given within the same time interval enhanced consolidation and retention.

Summary And Outlook: Cannabinoids have been shown to be an effective treatment option for patients with PTSD. Besides aiding to relieve the symptoms and enhance extinction training, they also are relatively well tolerated. Common adverse effects included light-headedness, forgetfulness, dizziness, and headaches.
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http://dx.doi.org/10.1515/jbcpp-2020-0279DOI Listing
March 2021

The Role of Therapeutic Hypothermia After Traumatic Spinal Cord Injury--A Systematic Review.

World Neurosurg 2016 Feb 22;86:432-49. Epub 2015 Dec 22.

Saba University School of Medicine, The Bottom, Saba, Caribbean Netherlands, BQ. Electronic address:

Background: Traumatic spinal cord injury (SCI) is a devastating neurologic entity characterized by a primary insult followed by a secondary pathologic cascade that propagates further injury. Hypothermia has an established clinical role in preventing SCI after cardiac arrest and thoracoabdominal aortic aneurysm repair, yet its emergence as a potential neuroprotectant after spinal cord trauma remains experimental. There are currently no pharmacologic interventions available to prevent secondary mechanisms of injury after spinal cord trauma.

Methods: Systematic review of literature.

Results: Experimental studies demonstrated that hypothermia diminishes secondary pathomechanisms, such as ischemia, oxidative stress, apoptosis, inflammation, and edema. Early onset and longer durations of hypothermia as well as concomitant steroids or neural stem cell engraftment combined with hypothermia appear to improve functional and histologic outcomes in animal models of spinal cord trauma. Recent clinical studies provide evidence that localized and systemic hypothermia may be applied safely and efficaciously in patients with severe acute SCI. Randomized clinical trials are needed to better evaluate optimal cooling parameters and the effectiveness of hypothermia after traumatic SCI.

Conclusion: Although variability exists in the literature, therapeutic hypothermia most likely confers neuroprotection after spinal cord trauma by diminishing the destructive secondary cascade. The available clinical data suggest that regional and systemic hypothermia is a relatively safe and feasible initial treatment modality for patients with acute SCI when combined with surgical decompression/stabilization with or without steroids. However, establishing a clinical role for therapeutic hypothermia after spinal cord trauma will invariably depend on future well-designed, multicentered, randomized, controlled clinical trial data.
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http://dx.doi.org/10.1016/j.wneu.2015.09.079DOI Listing
February 2016

The short splice variant of the gamma 2 subunit acts as an external modulator of GABA(A) receptor function.

J Neurosci 2010 Apr;30(14):4895-903

Department of Physiology, Ponce School of Medicine, Ponce, Puerto Rico 00732.

GABA(A) receptors (GABA(A)Rs) regulate the majority of fast inhibition in the mammalian brain and are the target for multiple drug types, including sleep aids, anti-anxiety medication, anesthetics, alcohol, and neurosteroids. A variety of subunits, including the highly distributed gamma2, allow for pharmacologic and kinetic differences in particular brain regions. The two common splice variants gamma2S (short) and gamma2L (long) show different patterns of regional distribution both in adult brain and during the course of development, but show few notable differences when incorporated into pentameric receptors. However, results presented here show that the gamma2S variant can strongly affect both GABA(A)R pharmacology and kinetics by acting as an external modulator of fully formed receptors. Mutation of one serine residue can confer gamma2S-like properties to gamma2L subunits, and addition of a modified gamma2 N-terminal polypeptide to the cell surface recapitulates the pharmacological effect. Thus, rather than incorporation of a separate accessory protein as with voltage-gated channels, this is an example of an ion channel using a common subunit for dual purposes. The modified receptor properties conferred by accessory gamma2S have implications for understanding GABA(A)R pharmacology, receptor kinetics, stoichiometry, GABAergic signaling in the brain during development, and altered function in disease states such as epilepsy.
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http://dx.doi.org/10.1523/JNEUROSCI.5039-09.2010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2891256PMC
April 2010

Tandem couture: Cys-loop receptor concatamer insights and caveats.

Mol Neurobiol 2007 Feb;35(1):113-28

Department of Physiology, University of Wisconsin-Madison, Madison, WI, USA.

Receptor subunits in the Cys-loop superfamily assemble to form channels as homopentamers or heteropentamers, expanding functional diversity through modularity. Expression of two or more compatible subunit types can lead to various receptor assemblies or subtypes. However, what may be good for diversity in vivo may be undesirable for the bench scientist, because we often wish to reduce our analyses to a single receptor subtype. By linking two or more subunits, creating tandems or concatamers, we can control stoichiometry and limit expression to exactly one receptor subtype. In this fashion, receptors with mixed subunit subtypes and heterozygous mutations can be separated from a mixture and can be described in detail. However, several recent studies have shown that this may be more easily conceived than accomplished, because several unforeseen problems have arisen. Concatamers can degrade, linkers can sometimes be clipped after or during translation, and one subunit may "loop out" or even become part of a second (now linked) pentamer with different characteristics. Some strategies have been developed to overcome these drawbacks, and the resultant new information that has begun to emerge has revitalized the study of these receptors in heterologous expression systems.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2597025PMC
February 2007

Optimized expression vector for ion channel studies in Xenopus oocytes and mammalian cells using alfalfa mosaic virus.

Pflugers Arch 2007 Apr 5;454(1):155-63. Epub 2006 Dec 5.

Department of Physiology, University of Wisconsin-Madison, 601 Science Drive, Madison, WI 53711, USA.

Plasmid vectors used for mammalian expression or for in vitro cRNA translation can differ substantially and are rarely cross-compatible. To make comparisons between mammalian and Xenopus oocyte expression systems, it would be advantageous to use a single vector without the need for shuttle vectors or subcloning. We have designed such a vector, designated pUNIV for universal, with elements that will allow for in vitro or ex vivo expression in multiple cell types. We tested the expression of pUNIV-based cDNA cassettes using enhanced green fluorescent protein and two forms of the type A gamma-aminobutyric acid receptor (GABA(A)R) and compared pUNIV to vectors optimized for expression in either Xenopus oocytes or mammalian cells. In HEK293 cells, radioligand binding was robust, and patch clamp experiments showed that subtle macroscopic GABA(A)R kinetics were indistinguishable from our previous results. In Xenopus oocytes, agonist median effective concentration measurements matched previous work using a vector optimized for oocyte expression. Furthermore, we found that expression using pUNIV was significantly enhanced in oocytes and was remarkably long-lasting in both systems.
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http://dx.doi.org/10.1007/s00424-006-0183-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2574422PMC
April 2007

Tandem subunits effectively constrain GABAA receptor stoichiometry and recapitulate receptor kinetics but are insensitive to GABAA receptor-associated protein.

J Neurosci 2005 Dec;25(49):11219-30

Department of Physiology, University of Wisconsin-Madison, Madison, Wisconsin 53711, USA.

GABAergic synapses likely contain multiple GABAA receptor subtypes, making postsynaptic currents difficult to dissect. However, even in heterologous expression systems, analysis of receptors composed of alpha, beta, and gamma subunits can be confounded by receptors expressed from alpha and beta subunits alone. To produce recombinant GABAA receptors containing fixed subunit stoichiometry, we coexpressed individual subunits with a "tandem" alpha1 subunit linked to a beta2 subunit. Cotransfection of the gamma2 subunit with alphabeta-tandem subunits in human embryonic kidney 293 cells produced currents that were similar in their macroscopic kinetics, single-channel amplitudes, and pharmacology to overexpression of the gamma subunit with nonlinked alpha1 and beta2 subunits. Similarly, expression of alpha subunits together with alphabeta-tandem subunits produced receptors having physiological and pharmacological characteristics that closely matched cotransfection of alpha with beta subunits. In this first description of tandem GABAA subunits measured with patch-clamp and rapid agonist application techniques, we conclude that incorporation of alphabeta-tandem subunits can be used to fix stoichiometry and to establish the intrinsic kinetic properties of alpha1beta2 and alpha1beta2gamma2 receptors. We used this method to test whether the accessory protein GABAA receptor-associated protein (GABARAP) alters GABAA receptor properties directly or influences subunit composition. In recombinant receptors with fixed stoichiometry, coexpression of GABARAP-enhanced green fluorescent protein (EGFP) fusion protein had no effect on desensitization, deactivation, or diazepam potentiation of GABA-mediated currents. However, in alpha1beta2gamma2S transfections in which stoichiometry was not fixed, GABARAP-EGFP altered desensitization, deactivation, and diazepam potentiation of GABA-mediated currents. The data suggest that GABARAP does not alter receptor kinetics directly but by facilitating surface expression of alphabetagamma receptors.
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http://dx.doi.org/10.1523/JNEUROSCI.3751-05.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577015PMC
December 2005

GABA(A) receptor beta 2 Tyr97 and Leu99 line the GABA-binding site. Insights into mechanisms of agonist and antagonist actions.

J Biol Chem 2002 Jan 15;277(4):2931-7. Epub 2001 Nov 15.

Department of Physiology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.

The identification of residues that line neurotransmitter-binding sites and catalyze allosteric transitions that result in channel gating is crucial for understanding ligand-gated ion channel function. In this study, we used the substituted cysteine accessibility method and two-electrode voltage clamp to identify novel gamma-aminobutyric acid (GABA)-binding site residues and to elucidate the secondary structure of the Trp(92)-Asp(101) region of the beta(2) subunit. Each residue was mutated individually to cysteine and expressed with wild-type alpha(1) subunits in Xenopus oocytes. GABA-gated currents (I(GABA)) were measured before and after exposure to the sulfhydryl reagent, N-biotinylaminoethyl methanethiosulfonate (MTS). V93C, D95C, Y97C, and L99C are accessible to derivatization. This pattern of accessibility is consistent with beta(2)Val(93)-Leu(99) adopting a beta-strand conformation. Both GABA and SR95531 protect Y97C and L99C from modification, indicating that these two residues line the GABA-binding site. In D95C-containing receptors, application of MTS in the presence of SR95531 causes a greater effect on I(GABA) than MTS alone, suggesting that binding of a competitive antagonist can cause movements in the binding site. In addition, we present evidence that beta(2)L99C homomers form spontaneously open channels. Thus, mutation of a binding site residue can alter channel gating, which implies that Leu(99) may be important for coupling agonist binding to channel gating.
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http://dx.doi.org/10.1074/jbc.M109334200DOI Listing
January 2002