Publications by authors named "Gregory Demopulos"

Most patients with COVID-19 in the intensive care unit develop an acute respiratory distress syndrome characterized by severe hypoxemia, decreased lung compliance, and high vascular permeability. Activation of the complement system is a hallmark of moderate and severe COVID-19, with abundant deposition of complement proteins in inflamed tissue and on the endothelium during COVID-19. Using a transgenic mouse model of SARS-CoV-2 infection, we assessed the therapeutic utility of an inhibitory antibody (HG4) targeting MASP-2, a key enzyme in the lectin pathway.

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Acute respiratory distress syndrome (ARDS) is a life-threatening disorder with a high rate of mortality. Complement activation in ARDS initiates a robust inflammatory reaction that can cause progressive endothelial injury in the lung. Here, we tested whether inhibition of the lectin pathway of complement could reduce the pathology and improve the outcomes in a murine model of LPS-induced lung injury that closely mimics ARDS in human.

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A high incidence of secondary and infection were observed in patients with severe COVID-19. The cause of this predisposition to infection is unclear. Our data demonstrate consumption of complement in acute COVID-19 patients reflected by low levels of C3, C4, and loss of haemolytic activity.

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Early and persistent activation of complement is considered to play a key role in the pathogenesis of COVID-19. Complement activation products orchestrate a proinflammatory environment that might be critical for the induction and maintenance of a severe inflammatory response to SARS-CoV-2 by recruiting cells of the cellular immune system to the sites of infection and shifting their state of activation towards an inflammatory phenotype. It precedes pathophysiological milestone events like the cytokine storm, progressive endothelial injury triggering microangiopathy, and further complement activation, and causes an acute respiratory distress syndrome (ARDS).

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Approximately 5 million people die from diseases related to nicotine addiction and tobacco use each year. The nicotine-induced increase of corticomesolimbic dopaminergic (DAergic) transmission and hypodopaminergic conditions occurring during abstinence are important for maintaining drug-use habits. We examined the notion of reequilibrating DAergic transmission by inhibiting phosphodiesterase 7 (PDE7), an intracellular enzyme highly expressed in the corticomesolimbic circuitry and responsible for the degradation of cyclic adenosine monophosphate (cAMP), the main second messenger modulated by DA receptor activation.

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Background And Aims: Andrographis paniculata is an annual herbaceous plant which belongs to the Acanthaceae family. Extracts from this plant have shown hepatoprotective, anti-inflammatory and antidiabetic properties, at least in part, through activation of the nuclear receptor Peroxisome Proliferator-Activated Receptor-gamma (PPAR γ). Recent evidence has demonstrated that activation of PPARγ reduces alcohol drinking and seeking in Marchigian Sardinian (msP) alcohol-preferring rats.

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In COVID-19, acute respiratory distress syndrome (ARDS) and thrombotic events are frequent, life-threatening complications. Autopsies commonly show arterial thrombosis and severe endothelial damage. Endothelial damage, which can play an early and central pathogenic role in ARDS and thrombosis, activates the lectin pathway of complement.

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Rationale: Peroxisome Proliferator Activator receptors (PPARs) are intracellular receptors that function as transcription factors, which regulate specific metabolic and inflammatory processes. PPARs are broadly distributed in the body and are also expressed in the central nervous system, especially in areas involved in addiction-related behavioral responses. Recent studies support a role of PPARs in alcoholism and pioglitazone: a PPARγ agonist used for treatment of type 2 diabetes showed efficacy in reducing alcohol drinking, stress-induced relapse, and alcohol withdrawal syndrome in rats.

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Peroxisome proliferator-activated receptor γ (PPARγ) is an intracellular transcription factor whose signaling activation by the selective agonist pioglitazone reduces alcohol drinking and alcohol-seeking behavior in rats. The present study utilized the two-bottle choice and operant self-administration procedures to investigate neuroanatomical substrates that mediate the effects of PPARγ agonism on alcohol drinking and seeking in msP rats. Bilateral infusions of pioglitazone (0, 5, and 10 μg/μl) in the rostromedial tegmental nucleus (RMTg) decreased voluntary alcohol drinking and alcohol self-administration.

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An isoform of peroxisome proliferator-activated receptors (PPARs), PPARγ, is the receptor for the thiazolidinedione class of anti-diabetic medications including pioglitazone. Neuroanatomical data indicate PPARγ localization in brain areas involved in drug addiction. Preclinical and clinical data have shown that pioglitazone reduces alcohol and opioid self-administration, relapse to drug seeking, and plays a role in emotional responses.

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Article Synopsis
  • The three complement activation pathways—classic pathway (CP), alternative pathway, and lectin pathway (LP)—all lead to the key event of C3 activation through formation of C3 convertases.
  • The C3 convertase complex requires both components C4 and C2, which are essential for CP and LP activation; without C4, CP cannot activate C3.
  • In the absence of C4 and/or C2, the LP can still activate C3 through the action of mannan-binding lectin-associated serine protease-2, demonstrating a bypass route for C3 activation in certain physiological conditions.
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Binge alcohol drinking has emerged as a typical phenomenon in young people. This pattern of drinking, repeatedly leading to extremely high blood and brain alcohol levels and intoxication is associated with severe risks of neurodegeneration and cognitive damage. Mechanisms involved in excitotoxicity and neuroinflammation are pivotal elements in alcohol-induced neurotoxicity.

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Rationale: Relapse to opioids is often driven by the avoidance of the aversive states of opioid withdrawal. We recently demonstrated that activation of peroxisome proliferator-activated receptor gamma (PPARγ) by pioglitazone reduces the motivation for heroin and attenuates its rewarding properties. However, the role of PPARγ in withdrawal and other forms of relapse to heroin is unknown.

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Background: Complement activation via the lectin activation pathway (LP) has been identified as the key mechanism behind post-ischemic tissue inflammation causing ischemia-reperfusion injury (IRI) which can significantly impact the clinical outcome of ischemic disease. This work defines the contributions of each of the three LP-associated enzymes-mannan-binding lectin-associated serine protease (MASP)-1, MASP-2, and MASP-3-to ischemic brain injury in experimental mouse models of stroke.

Methods: Focal cerebral ischemia was induced in wild-type (WT) mice or mice deficient for defined complement components by transient middle cerebral artery occlusion (tMCAO) or three-vessel occlusion (3VO).

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PPARγ is one of the three isoforms identified for the peroxisome proliferator-activated receptors (PPARs) and is the receptor for the thiazolidinedione class of anti-diabetic medications including pioglitazone. PPARγ has been long studied for its role in adipogenesis and glucose metabolism, but the discovery of the localization in ventral tegmental area (VTA) neurons opens new vistas for a potential role in the regulation of reward processing and motivated behavior in drug addiction. Here, we demonstrate that activation of PPARγ by pioglitazone reduces the motivation for heroin and attenuates its rewarding properties.

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Background: The purpose of this study was to evaluate the effect of OMS302 on intraoperative pupil diameter and early postoperative ocular pain when administered during intraocular lens replacement surgery.

Methods: Four hundred and six patients (406 study eyes; 202 in the OMS302 group and 204 in the placebo group) were entered into this randomized, double-masked, placebo-controlled, multicenter Phase III study, which was conducted at 15 centers in the USA and the Netherlands. The patients received OMS302 (60.

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Background And Purpose: Opioid drugs are potent analgesics. However, their chronic use leads to the rapid development of tolerance to their analgesic effects and subsequent increase of significant side effects, including drug dependence and addiction. Here, we investigated the role of PPARγ in the development of analgesic tolerance to morphine in mice.

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Background: Pioglitazone is a selective peroxisome proliferator-activated receptor γ (PPARγ) agonist used for the treatment of insulin resistance and type 2 diabetes. Previous studies conducted in our laboratory showed that activation of PPARγ by pioglitazone reduces alcohol drinking, stress-induced relapse, and alcohol withdrawal syndrome in rats. Pioglitazone was not able to prevent relapse elicited by alcohol cues.

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Purpose: This phase 2 study compared OMS103HP (Omeros, Seattle, WA) with control (lactated Ringer's) irrigation solution in patients undergoing arthroscopic partial meniscectomy.

Methods: This was a prospective, multicenter, double-blind, randomized, vehicle-controlled, parallel-group study. Safety and postoperative pain, range of motion, and self-reported function were evaluated for 90 days.

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Background: Pioglitazone and rosiglitazone belong to the class of thiazolidinediones (TZDs). They were first developed as antioxidants and then approved for the clinical treatment of insulin resistance and Type 2 diabetes. TZDs bind with high affinity and activate peroxisome proliferator-activated receptor-gamma (PPARγ) receptors, which in the brain are expressed both in neurons and in glia.

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Purpose: OMS103HP, an investigational drug product containing ketoprofen, amitriptyline, and oxymetazoline, is added to arthroscopic irrigation solution. OMS103HP was evaluated in patients undergoing arthroscopic anterior cruciate ligament reconstruction to assess the drug's safety and ability to improve postoperative knee function and motion, reduce postoperative pain, and allow earlier return to work.

Methods: This was a prospective, double-blind, vehicle-controlled, parallel-group, randomized study.

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Intraurethral procedures such as the transurethral resection of the prostate can generate detrusor overactivity and bladder irritability. The rabbit model of detrusor overactivity has proven to be an excellent model to study the effects of drugs on detrusor overactivity. Using this model, we evaluated the responses to intravesical ketoprofen.

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