Impact of Critical Care Transesophageal Echocardiography in Medical-Surgical ICU Patients: Characteristics and Results From 274 Consecutive Examinations.

OBJECTIVE: Critical care echocardiography has become an integral tool in the assessment and management of critically ill patients. Critical care transesophageal echocardiography (TEE) offers diagnostic reliability, superior image quality, and an expanded diagnostic scope to transthoracic echocardiography. Despite its favorable attributes, TEE use in North American intensive care units (ICUs) remains relatively undescribed. In this article, we seek to characterize the feasibility, indications, and clinical impact of a critical care TEE program. DESIGN: Retrospective, observational study. SETTING: Tertiary care, academic critical care program consisting of 2 hospitals in Ontario, Canada. PARTICIPANTS: Consecutive critical care TEE examinations on ICU patients performed between December 2012 and December 2016. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Consecutive critical care TEE studies on ICU patients from December 1, 2012, to December 31, 2016, were reviewed. The TEEs performed on cardiac surgery patients and those without reports were excluded. Examination details, including indications, complications, examination complexity (number of views, Doppler techniques), and clinical recommendations were aggregated and analyzed. Two hundred seventy-four TEE studies were performed by 38 operators. Common indications for TEE studies were hemodynamic instability (45.2%), assessment for infective endocarditis (22.2%), and cardiac arrest (20.1%). A change in patient management was proposed following 79.5% of TEE studies. Thirty-eight percent of TEE studies were performed during evening hours or on weekends. There were no mechanical complications. CONCLUSIONS: Our observational data support intensivist-performed TEE as being safe and therapeutically influential across a broad range of indications. Our program's demonstrated feasibility and impact may act as a model for TEE adoption in other North American ICUs.

Diagnostic Accuracy of Critical Care Transesophageal Echocardiography vs Cardiology-Led Echocardiography in ICU Patients.

BACKGROUND: Critical care transesophageal echocardiography (ccTEE) performed by intensivists is increasingly used to investigate cardiorespiratory failure in the ICU. Validation of the accuracy of TEE in the hands of intensivists remains largely unknown. The goal of this study was to characterize the diagnostic accuracy of ccTEE. METHODS: This study was a two-center, retrospective comparison between TEE studies performed and interpreted by intensivists and cardiology-led TEE or transthoracic echocardiography (TTE) performed and/or interpreted by cardiologists. The study period was December 2012 to December 2016 for all consecutive ICU patients who received an initial ccTEE and either a cardiology TEE or TTE within 72 h. Using the cardiology-conducted examination as the gold standard, we reported sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of ccTEE. RESULTS: Comparisons between ccTEE and cardiology TEE/TTE performed yielded 56 patients (five ccTEE vs cardiology TEE and 51 ccTEE vs cardiology TTE). The comparison between ccTEE and cardiology TEE showed 100% sensitivity, specificity, PPV, NPV, and accuracy for the primary diagnosis and other major findings. For the combined ccTEE and cardiology TEE/TTE comparison, there was a high sensitivity/specificity/PPV/NPV/accuracy for the primary diagnosis (90%-100% range), as well as other major diagnoses (88%-100% range). CONCLUSIONS: This study showed that ccTEE has a high sensitivity, specificity, PPV, NPV, and accuracy compared with the gold standard cardiology TEE or TTEs in critically ill patients, when performed by advanced echocardiogram-trained/experienced intensivists.

Bilateral blindness secondary to optic nerve ischemia from severe amlodipine overdose: a case report.

BACKGROUND: Calcium channel blockers are commonly prescribed medications; calcium channel blocker overdose is becoming increasingly prevalent. The typical presentation of a calcium channel blocker overdose is hypotension and decreased level of consciousness. We describe a case of a calcium channel blocker overdose that led to bilateral cortical blindness, a presentation that has not previously been reported. CASE PRESENTATION: A 49-year-old white woman with known bilateral early optic atrophy presented to our hospital with hypotension and obtundation following a known ingestion of 150 mg of amlodipine. She was transferred to our intensive care unit where she was intubated, mechanically ventilated, and required maximal vasopressor support (norepinephrine 40 mcg/minute, epinephrine 40 mcg/minute, and vasopressin 2.4 units/hour) along with intravenously administered crystalloid boluses. Despite these measures, she continued to deteriorate with persistent hypotension and tachycardia, as well as anuria. Intralipid emulsion therapy was subsequently administered to which no initial response was observed. A chest X-ray revealed diffuse pulmonary edema; intravenous diuresis as well as continuous renal replacement therapy was initiated. Following the initiation of continuous renal replacement therapy, her oxygen requirements as well as urine output began to improve, and 3 days later she was liberated from mechanical ventilation. Following extubation, she complained of new onset visual impairment, specifically seeing only red-green colors, but no objects. An ophthalmologic examination revealed that this was due to bilateral optic atrophy from prolonged hypotension during the first 24 hours after the overdose. CONCLUSION: Persistent hypotension in the setting of a calcium channel blocker overdose can lead to worsening optic atrophy resulting in bilateral cortical blindness.

ATP-binding cassette A1-mediated lipidation of apolipoprotein A-I occurs at the plasma membrane and not in the endocytic compartments.

ATP-binding cassette transporter (ABC) A1 is required for the lipidation of apolipoprotein A-I to generate high density lipoprotein (HDL). This process is proposed to occur through a retro-endocytosis pathway in which apoA-I internalizes with ABCA1 and generates HDL from the endosomal compartments before resecretion. The aim of this study was to determine the route of apoA-I endocytosis and whether endocytosis contributes to HDL biogenesis. Using confocal microscopy, we found that internalized apoA-I only transiently colocalized with transferrin, a retro-endocytosis marker. Instead, apoA-I perfectly colocalized with a bulk phase uptake marker (fluorescein isothiocyanate-dextran) and, at later time points, with LysoTracker in several cell models including macrophages, fibroblasts, and baby hamster kidney cells. ABCA1 colocalized poorly with internalized apoA-I. To determine the contribution of internalized apoA-I to HDL biogenesis, we specifically removed apoA-I from the cell surface and analyzed the fate of internalized apoA-I. We found that 23% of cell-associated apoA-I was internalized at steady state. Of internalized apoA-I, only 20% was converted to HDL, and the rest was degraded, consistent with a lysosomal destination. We also found that apoA-I was released approximately five times faster from the plasma membrane than from the intracellular compartments. From these kinetic parameters, we estimated that approximately 5.6% of apoA-I that interacts with cells is degraded and that internalized apoA-I contributes to approximately 1.4% of total HDL production. We also found that blocking endocytosis with sucrose or cytochalasin D did not decrease cholesterol efflux or HDL biogenesis. We therefore conclude that the plasma membrane is the main platform where ABCA1-mediated lipidation of apoA-I occurs.

Drugs and their molecular targets: an updated overview.

About 330 targets bind approved drugs, 270 encoded by the human genome and 60 belonging to pathogenic organisms. A large number of druggable targets have been recently proposed from preclinical and first clinical data, but a huge reservoir of putative drug targets, possibly several thousands, remains to be explored. This overview considers the different types of ligands and their selectivity in the main superfamilies of drug targets, enzymes, membrane transporters and ion channels, and the various classes of membrane and nuclear receptors with their signalling pathway. Recently approved drugs such as monoclonal antibodies, tyrosine kinase and proteasome inhibitors, and major drugs under clinical studies are reviewed with their molecular target and therapeutic interest. The druggability of emerging targets is discussed, such as multidrug resistance transporters and cystic fibrosis transmembrane conductance regulator (CFTR), hyperpolarization-activated cyclic nucleotides-gated (HCN), cyclic nucleotide-gated (CNG) and transient receptor potential (TRP) ion channels, tumour necrosis factor (TNF) and receptor activator of NFkappaB (RANK) receptors, integrins, and orphan or recently deorphanized G-protein-coupled and nuclear receptors. Large advances have been made in the therapeutical use of recombinant cytokines and growth factors (i.e. tasonermin, TNFalpha-1a; becaplermin, platelet-derived growth factor (PDGF); dibotermin-alpha, bone morphogenetic proteins (BMP)2; anakinra, interleukin-1 receptor antagonist protein (IRAP), and in enzyme replacement therapy, i.e. algasidase (alpha-galactosidase) and laronidase (alpha-l-iduronidase). New receptor classes are emerging, e.g. membrane aminopeptidases, and novel concepts are stimulating drug research, e.g. epigenetic therapy, but the molecular target of some approved drugs, such as paracetamol and imidazolines, still need to be identified.

The "Epigenetic Code Replication Machinery", ECREM: a promising drugable target of the epigenetic cell memory.

Discrete chemical modifications of the chromatin (DNA and primarily histones) can regulate gene expression or repression and can be transmitted to the descent (cells or organisms) thanks to an epigenetic memory. These modifications involve histone post-translational modifications, DNA methylation at CpG islands and small nuclear RNAs processes. They play fundamental roles in cell proliferation and differentiation. These two processes are crucial in particular during embryonic development, X chromosome inactivation in females, genomic imprinting, gene bookmarking, cell reprogramming, position effect and silencing of retroviral elements. While, only one major DNA modification is known, more than 150 post-translation modifications of histones have been reported, including methylations, acetylations, ubiquitinations, SUMOylations and phosphorylations. How these modifications are inherited from mother cells to daughter cells or from an organism to its descent remains a major scientific challenge. We propose here a macro-molecular complex, called ECREM for "Epigenetic Code REplication Machinery", as being involved in the inheritance of the epigenetic code. The composition of ECREM may vary in a spatio-temporal manner according to the chromatin state, the cell phenotype and the development stage. We describe the members of ECREM, responsible for the epigenetic code inheritance, i.e., enzymes involved in DNA methylation and histone post-translational modifications. Some of them, such as DNA methyltransferases (DNMTs), histone acetyltransferases (HATs) and histone deacetylases (HDACS including sirtuins), have been found to be deregulated in several types of pathologies and are already targeted by inhibitors. ECREM, thus, appears to be an interesting complex to be investigated in order to find new drugs for cancer, metabolic, neuro-degenerative and inflammatory diseases therapy.

ATP-binding cassette transporter A1 expression disrupts raft membrane microdomains through its ATPase-related functions.

ATP-binding cassette transporter A1 (ABCA1) is known to mediate cholesterol efflux to lipid-poor apolipoprotein A-I. In addition, ABCA1 has been shown to influence functions of the plasma membrane, such as endocytosis and phagocytosis. Here, we report that ABCA1 expression results in a significant redistribution of cholesterol and sphingomyelin from rafts to non-rafts. Caveolin, a raft/caveolae marker also redistributes from punctate caveolae-like structures to the general area of the plasma membrane upon ABCA1 expression. Furthermore, we observed significant reduction of Akt activation in ABCA1-expressing cells, consistent with raft disruption. Cholesterol content in the plasma membrane is, however, not altered. Moreover, we provide evidence that a non-functional ABCA1 with mutation in an ATP-binding domain, A937V, fails to redistribute cholesterol, sphingomyelin, or caveolin. A937V also fails to influence Akt activation. Finally, we show that apolipoprotein A-I preferentially associates with non-raft membranes in ABCA1-expressing cells. Our results thus demonstrate that ABCA1 causes a change in overall lipid packing of the plasma membrane, likely through its ATPase-related functions. Such reorganization by ABCA1 effectively expands the non-raft membrane fractions and, consequentially, pre-conditions cells for cholesterol efflux.

The Rac/Cdc42 guanine nucleotide exchange factor beta1Pix enhances mastoparan-activated Gi-dependent pathway in mast cells.

Carbachol stimulates granule exocytosis, phospholipase C (PLC), and phospholipase D (PLD) in RBL-2H3hm1 mast cells by a mechanism that involves Galphaq. However, mastoparan stimulates the same responses through Gi protein. Both Gi and Galphaq pathways are suppressed by Clostridium difficile toxin B, suggesting that Rac and Cdc42 small GTPases are also involved. Over-expression of beta1Pix, a guanine nucleotide exchange factor for Rac and Cdc42, enhances mastoparan-but not carbachol-induced hexosaminidase secretion and PLC and PLD activation. Furthermore, cells expressing beta1Pix exhibit elevated levels of mastoparan-stimulated IP3 production. Taken together, these findings implicate beta1Pix in regulating hexoasaminidase secretion and IP3 production in early stage upon mastoparan stimulation.

G protein-dependent activation of mast cell by peptides and basic secretagogues.

Signaling pathways leading to exocytosis and arachidonate release from serosal mast cells by basic secretagogues, including cationic peptides, arise from the involvement of betagamma subunits from G(i2) and G(i3) GTP-binding proteins. The original concept that basic secretagogues directly interact with G proteins implicated the entry of secretagogues into mast cells. This has been demonstrated only for the neuropeptide substance P. Basic secretagogues might share a common mechanism of penetration with the newly described cell-penetrating peptides. The involvement of some membrane transporter or non-selective membrane receptor to basic secretagogues cannot be excluded.

Agmatine: a mastoparan-like activity related to direct activation of heterotrimeric G proteins.

We examined agmatine and imidazoline derivatives as putative ligands of trimeric G protein in rat peritoneal mast cells. Agmatine induced a concentration-dependent and pertussis toxin-sensitive secretion of histamine (exocytosis) and arachidonate. Clonidine and idazoxan had no effect. Blockage of Gbetagamma dimers by a specific anti-Gbeta antibody inhibited exocytosis elicited by agmatine and mastoparan. The G protein antagonist [p-Glu(5),D-Trp(7,9,10)]substance P-(5-11) prevented both mastoparan- and agmatine-induced exocytosis when it was allowed to reach its intracellular targets by streptolysin-O permeabilisation. In intact cells, this response was prevented by both the removal of sialic acid residues by neuraminidase and by [D-Pro(4),D-Trp(7,9,10)]substance P-(4-11) acting at the mast cell surface. Exocytosis was restored by permeabilisation of the plasma membrane with streptolysin-O. These results suggest that agmatine might have several molecular targets, exerting its neurotransmitter function at low concentrations (i.e., with high affinity) through membrane receptors and at high concentrations (i.e., with weak affinity) through direct G protein activation.