Ester Formation via Symbiotic Activation Utilizing Trichloroacetimidate Electrophiles.

Trichloroacetimidates are useful reagents for the synthesis of esters under mild conditions that do not require an exogenous promoter. These conditions avoid the undesired decomposition of substrates with sensitive functional groups that are often observed with the use of strong Lewis or Brønsted acids. With heating, these reactions have been extended to benzyl esters without electron-donating groups. These inexpensive and convenient methods should find application in the formation of esters in complex substrates.

Synthesis and initial evaluation of quinoline-based inhibitors of the SH2-containing inositol 5'-phosphatase (SHIP).

Recently, inhibition of the SH2-containing inositol 5'-phosphatase 1 (SHIP1) has become an attractive strategy for facilitating engraftment of MHC-I mismatched bone marrow grafts, increasing the number of adult stem cells in vivo, and inducing mobilization of hematopoietic stem cells. Utilizing high-throughput screening, two quinoline small molecules (NSC13480 and NSC305787) that inhibit SHIP1 enzymatic activity were discovered. New syntheses of these inhibitors have been developed which verified the relative stereochemistry of these structures. Utilizing this synthetic route, some analogs of these quinolines have been prepared and tested for their ability to inhibit SHIP. These structure activity studies determined that an amine tethered to the quinoline core is required for SHIP inhibition. SHIP inhibition may explain the antitumor effects of similar quinoline amino alcohols and provides an impetus for further synthetic studies in this class of compounds.

Total Knee Arthroplasty Revision in the Setting of Periprosthetic Joint Infection Resulting in Bone Cement Implantation Syndrome (BCIS), Pulseless Electrical Activity (PEA) Arrest, and Intraoperative Death: A Case Report and Literature Review.

An 87-year-old female with a history of total knee arthroplasty (TKA) presented to the emergency department (ED) for left knee pain in the setting of recent methicillin-sensitive Staphylococcus aureus (MSSA) sepsis of unknown origin. She was subsequently diagnosed with a complicated symptomatic periprosthetic joint infection of her left TKA hardware and was admitted for TKA revision following an orthopedic surgery consultation. Upon arrival at the operating room (OR), standard American Society of Anesthesiology (ASA) monitors were applied. These included non-invasive blood pressure, electrocardiogram (ECG), pulse oximeter, and an esophageal temperature probe. The patient then underwent induction of general endotracheal anesthesia (GETA) without significant hemodynamic compromise. Intraoperatively, the patient tolerated the removal of her infected hardware without major complication but upon placement of the methyl methacrylate (MMA), commonly referred to as bone cement, the patient had an acute drop in her end-tidal carbon dioxide (EtCO2) and then developed significant bradycardia and hypotension. Despite rapid detection and treatment, the patient continued to collapse hemodynamically and was noted to be pulseless and in pulseless electrical activity (PEA) arrest on ECG. Cardiopulmonary resuscitation (CPR) was immediately started per the Advanced Cardiac Life Support (ACLS) algorithm. Roughly after 45 minutes of continuous CPR and multiple doses of 1 mg epinephrine, it was determined that the patient had suffered a catastrophic and fatal intraoperative event. A team decision was made to stop providing any lifesaving interventions. This patient's presentation is consistent with bone cement implantation syndrome (BCIS), an uncommon phenomenon that remains poorly understood. Two leading models for BCIS described in the literature are the monomer-mediated and embolus-mediated models. However, further research into BCIS is warranted to better understand its pathophysiology, incidence, as well as potential prophylactic measures, including the use of cementless arthroplasty. This complicated and fatal case serves as a reminder of the morbidity and mortality associated with BCIS and underscores that anesthesiology teams must remain vigilant and prepared during orthopedic joint procedures.

Challenges of Providing Optimal and Safe Intrapartum Analgesia in Patients With HELLP Syndrome: A Case Report and Literature Review.

HELLP (Hemolysis, Elevated Liver enzymes, Low Platelets) Syndrome is a rare but serious complication of pregnancy that can lead to disseminated intravascular coagulation, pulmonary edema, respiratory failure, hepatic and renal injury, and death if not recognized and treated promptly. A 36-year-old nulligravid (G0) active duty Marine at 36 weeks and 1 day gestation with dichorionic diamniotic twins presented to triage for routine cervical examination found to have elevated blood pressures and symptomatic thrombocytopenia, with a suspected diagnosis of HELLP. A multidisciplinary decision was made by anesthesiology, obstetrics and gynecology, and pediatrics to deliver the twins to avoid any further complications. The twins were in cephalic presentation and the patient desired to attempt a vaginal delivery. Due to the patient's thrombocytopenia, neuraxial anesthesia (spinal and/or epidural) left the patient at a high risk of developing catastrophic complications such as an epidural hematoma, and the subsequent motor block/weakness would likely lessen the patient's ability to participate in active labor for a vaginal delivery. A Cesarean section under general anesthesia was also to be avoided as the patient's elevated risk of catastrophic hemorrhage would be worsened by volatile anesthetic agents which cause significant uterine vascular relaxation and reduced uterine muscular tone. Ultimately, the decision was made to provide analgesia through a remifentanil PCA (patient-controlled analgesia) for labor and a ketamine bolus for delivery. The mother delivered both twins vaginally in the operating room without perioperative complication. This case demonstrates the safety of alternate forms of anesthesia for delivery when neuraxial anesthesia is contraindicated.

Intraoperative Acute Cardiac Tamponade as a Result of Intracardiac Perforation Requiring Emergency Continuous Pericardiocentesis and Open Sternotomy: A Case Report and Literature Review of a Rare but Fatal Complication.

Intraoperative acute cardiac tamponade associated with iatrogenic intracardiac perforation from percutaneous interventional cardiac procedures is a rare but potentially catastrophic complication. We report a case of intraoperative acute hemopericardium caused by a left atrial (LA) perforation resulting in cardiac tamponade in a patient undergoing a baffling procedure for the correction of two anomalous pulmonary veins draining into her superior vena cava (SVC) that required continuous pericardiocentesis with autologous blood transfusion via the femoral vein and an emergency intraoperative transfer from the interventional cardiology cath lab to the cardiac operating room for an open sternotomy and primary repair. An 86-year-old female with known right-ventricular (RV) failure with preserved ejection fraction (left ventricular ejection fraction (LVEF): 50-55% on transesophageal echocardiography (TEE) one week prior) and atrial fibrillation was admitted for her third heat failure exacerbation in two months despite being adherent to her aggressive diuresis medication regimen. Upon her readmission and due to her symptomatic and seemingly refractory heart failure, the patient underwent a cardiac computer tomography (CT) with 3D reconstruction that showed previously undiagnosed partial anomalous pulmonary venous return (PAPVR) of two of her four pulmonary veins aberrantly draining into the SVC. This anatomic pathology was deemed to be the likely etiology of her repeated episodes of recurring heart failure exacerbations, shortness of breath, peripheral edema, and fatigue. The patient was counseled and consented to a percutaneous baffle of the two anomalous veins to redirect more of the returning pulmonary venous blood away from the SVC and to the LA. While under general endotracheal anesthesia (GETA) with a TEE in place during the procedure, the patient suddenly developed acute hypotension, tachycardia, and a reduction in expired carbon dioxide (EtCO2) was noted quickly followed by evidence of a rapidly accumulating hemopericardium on TEE. Cardiothoracic surgery was urgently consulted to the interventional cardiology cath lab while the patient underwent an emergency pericardiocentesis that momentarily alleviated her hemodynamic instability, cardiac tamponade physiology, and deteriorating overall clinical picture. While performing continuous pericardiocentesis with autologous return of the aspirated blood via femoral venous access the patient was urgently transported to the cardiac operating room and prepped for emergency sternotomy for primary repair of the LA. Following primary repair via sternotomy, multiple drains were placed and the thoracic cavity was closed with wires. The patient was immediately transported to the surgical intensive care unit (SICU) intubated, mechanically ventilated, and sedated. During this time, the patient progressively required additional vasoactive and inotropic agents to support her mean arterial pressure (MAP), and following a multidisciplinary discussion with the patient's family regarding her goals of care, the decision was made to withdraw further resuscitation efforts and the patient expired four hours later.

Scalable and Chromatography-Free Synthesis of Efflux Pump Inhibitor Phenylalanine Arginine ß-Naphthylamide for Its Validation in Wild-Type Bacterial Strains.

Phenylalanine arginine ß-naphthylamine, or PAßN, is a C-terminus capped dipeptide discovered in 1999 as an RND-type efflux pump inhibitor (EPI). Since then, PAßN has become a standard tool compound in EPI research and development. Despite this, PAßN lacks a detailed or efficient synthesis, and standard parameters for its use in wild-type bacterial strains are inconsistent or non-existent. Therefore, a scalable and chromatography-free synthesis of PAßN was developed using streamlined traditional solution-phase peptide coupling chemistry. With this procedure, gram scale quantities of PAßN were synthesized alongside analogues and stereoisomers to build a focused library to evaluate simple structure activity relationships. While most analogues were less active than the broadly utilized L,L-PAßN itself, we identified that its enantiomer, D,D-PAßN, also provided 8- to 16-fold potentiation of the antibiotic levofloxacin at 40 to 50 µg/mL concentrations of EPI in various wild-type Pseudomonas aeruginosa strains. Additionally, D,D-PAßN was shown to be significantly more hydrolytically stable than L,L-PAßN, indicating that it may be a useful, and now readily synthesized, tool compound facilitating future EPI research.

Physiologic Fidelity as a Domain in Assessing Mixed Reality Trauma Simulation.

INTRODUCTION: Mixed reality has been used in trauma and emergency medicine simulation for more than a decade. As mixed reality potential in trauma simulation continues to expand, so too does the need to validate it as a surrogate for real-life emergency scenarios. Validation of these simulations can occur by measuring fidelity, or the degree to which a computing system can reproduce real-world experiences. After performing a literature review, we determined that most fidelity assessments of trauma and emergency simulations focus on how the user subjectively experiences the simulation. Although subjective user assessment is an important component of determining fidelity, we pose an introductory three-part framework that may assess mixed reality trauma simulation more adequately. MATERIALS AND METHODS: A literature review was conducted using Google Scholar, PubMed, and the Uniformed Services University PowerER search database. Relevant articles were assessed to identify how studies measured fidelity in trauma simulation. We then designed the three-part framework to aid researchers in assessing the fidelity of mixed reality trauma simulations. RESULTS: The domains we determined to best assess mixed reality emergency simulation are as follows:1. Continue assessing fidelity via subjective user assessments. This allows the researcher to know how real the simulation looked and felt to the user based on their individual report.2. Determine whether the trauma simulation changes the medical decision-making capacity of the user. If the user's decision-making capacity changes with a stress-inducing trauma simulation versus a non-stress-inducing simulation, then the stress-inducing trauma environment would be approaching greater fidelity.3. Study the domain of our newly proposed concept: physiologic fidelity. We define physiologic fidelity as the degree to which the simulation elicits a measurable, autonomic response independent of observed emotion or perceived affect. Recreating objective autonomic arousal may be the best way to ensure a trauma simulation reaches fidelity. CONCLUSION: We propose a methodology to assess mixed reality trauma simulation fidelity. Once fidelity is more fully known to the researcher and the simulation user, adjustments can be made to approach reality more closely. Improved simulators may enrich the preparedness of both junior and senior learners for real-life emergencies. We believe assessing the three domains using the Wide Area Virtual Experience at the Val G. Hemming simulation center in Bethesda, MD, will validate mixed reality-trauma simulators as invaluable surrogates for real-life emergency scenarios and ultimately contribute to improved clinical outcomes for clinicians and their patients.

A multisubstrate reductase from Plantago major: structure-function in the short chain reductase superfamily.

The short chain dehydrogenase/reductase superfamily (SDR) is a large family of NAD(P)H-dependent enzymes found in all kingdoms of life. SDRs are particularly well-represented in plants, playing diverse roles in both primary and secondary metabolism. In addition, some plant SDRs are also able to catalyse a reductive cyclisation reaction critical for the biosynthesis of the iridoid backbone that contains a fused 5 and 6-membered ring scaffold. Mining the EST database of Plantago major, a medicinal plant that makes iridoids, we identified a putative 5ß-progesterone reductase gene, PmMOR (P. major multisubstrate oxido-reductase), that is 60% identical to the iridoid synthase gene from Catharanthus roseus. The PmMOR protein was recombinantly expressed and its enzymatic activity assayed against three putative substrates, 8-oxogeranial, citral and progesterone. The enzyme demonstrated promiscuous enzymatic activity and was able to not only reduce progesterone and citral, but also to catalyse the reductive cyclisation of 8-oxogeranial. The crystal structures of PmMOR wild type and PmMOR mutants in complex with NADP+ or NAD+ and either 8-oxogeranial, citral or progesterone help to reveal the substrate specificity determinants and catalytic machinery of the protein. Site-directed mutagenesis studies were performed and provide a foundation for understanding the promiscuous activity of the enzyme.

Dual enhancement of T and NK cell function by pulsatile inhibition of SHIP1 improves antitumor immunity and survival.

The success of immunotherapy in some cancer patients has revealed the profound capacity for cytotoxic lymphocytes to eradicate malignancies. Various immunotherapies work by blocking key checkpoint proteins that suppress immune cell activity. The phosphatase SHIP1 (SH2-containing inositol polyphosphate 5-phosphatase) limits signaling from receptors that activate natural killer (NK) cells and T cells. However, unexpectedly, genetic ablation studies have shown that the effector functions of SHIP1-deficient NK and T cells are compromised in vivo. Because chronic activation of immune cells renders them less responsive to activating signals (a host mechanism to avoid autoimmunity), we hypothesized that the failure of SHIP1 inhibition to induce antitumor immunity in those studies was caused by the permanence of genetic ablation. Accordingly, we found that reversible and pulsatile inhibition of SHIP1 with 3-α-aminocholestane (3AC; "SHIPi") increased the antitumor response of NK and CD8+ T cells in vitro and in vivo. Transient SHIP1 inhibition in mouse models of lymphoma and colon cancer improved the median and long-term tumor-free survival rates. Adoptive transfer assays showed evidence of immunological memory to the tumor in hematolymphoid cells from SHIPi-treated, long-term surviving mice. The findings suggest that a pulsatile regimen of SHIP1 inhibition might be an effective immunotherapy in some cancer patients.

A small-molecule inhibitor of SHIP1 reverses age- and diet-associated obesity and metabolic syndrome.

Low-grade chronic inflammation is a key etiological phenomenon responsible for the initiation and perpetuation of obesity and diabetes. Novel therapeutic approaches that can specifically target inflammatory pathways are needed to avert this looming epidemic of metabolic disorders. Genetic and chemical inhibition of SH2-containing inositol 5' phosphatase 1 (SHIP1) has been associated with systemic expansion of immunoregulatory cells that promote a lean-body state; however, SHIP1 function in immunometabolism has never been assessed. This led us to investigate the role of SHIP1 in metabolic disorders during excess caloric intake in mice. Using a small-molecule inhibitor of SHIP1 (SHIPi), here we show that SHIPi treatment in mice significantly reduces body weight and fat content, improves control of blood glucose and insulin sensitivity, and increases energy expenditure, despite continued consumption of a high-fat diet. Additionally, SHIPi reduces age-associated fat in mice. We found that SHIPi treatment reverses diet-associated obesity by attenuating inflammation in the visceral adipose tissue (VAT). SHIPi treatment increases IL-4-producing eosinophils in VAT and consequently increases both alternatively activated macrophages and myeloid-derived suppressor cells. In addition, SHIPi decreases the number of IFN-γ-producing T cells and NK cells in VAT. Thus, SHIPi represents an approach that permits control of obesity and diet-induced metabolic syndrome without apparent toxicity.

SHIPi Enhances Autologous and Allogeneic Hematolymphoid Stem Cell Transplantation.

Hematopoietic stem cell transplantation (HSCT) is a highly effective procedure enabling long-term survival for patients with hematologic malignancy or heritable defects. Although there has been a dramatic increase in the success rate of HSCT over the last two decades, HSCT can result in serious, sometime untreatable, disease due to toxic conditioning regimens, graft vs. host disease and required use of mismatched bone marrow in some cases. Studies utilizing germline knockout mice have discovered several candidate genes that could be targeted pharmacologically to create a more favorable environment for transplant success. SHIP1 deficiency permits improved engraftment of hematopoietic stem-progenitor cells (HS-PC) and produces a suppressive microenvironment ideal for incoming grafts. The recent development of small molecule SHIP1 inhibitors has opened a different therapeutic approach to creating transient SHIP1-deficiency. Here we show that SHIP1 inhibition (SHIPi) can mobilize functional HS-PC, accelerate hematologic recovery, and enhance donor HS-PC engraftment in both allogeneic and autologous transplant settings. We also observed the expansion of key cell populations known to suppress host-reactive cells formed during engraftment. Therefore, SHIPi represents a non-toxic, new therapeutic that has significant potential to improve the success and safety of therapies that utilize HSCT.