A rare case of spontaneous expulsive suprachoroidal haemorrhage in a glaucomatous eye treated with topical alpha-adrenergic agonist

Spontaneous expulsive suprachoroidal hemorrhage is a rare ocular condition, which usually occurs after sudden decompression of the eyewall. Most of the cases of expulsive hemorrhage reported had a predisposing glaucoma with the combination of corneal pathology. We are reporting a case of spontaneous expulsive suprachoroidal hemorrhage in a glaucoma patient probably due to perpetuated inflammatory reaction and frequent eye rubbing induced by allergic reaction to topical alpha adrenergic agonist in a compromised cornea.

Sedation and Anesthesia of Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea), and African Spurred Tortoises (Centrochelys sulcata): A Retrospective Review (2009–2019)

Tortoises belong to the taxonomic family Testudinidae, which is considered one of the most imperiled families of the order Testudines. Anesthesia is often required for the medical and surgical management of large tortoises. The objectives of this retrospective study were to review drug regimens used to successfully anesthetize Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea) and African spurred (Centrochelys sulcata) tortoises, and to compare the times to effect and to extubation in tortoises administered different premedication protocols. Anesthetic records of giant tortoises admitted to the University of Florida College of Veterinary Medicine between January 2009 and December 2019 were reviewed. A total of 34 tortoises (six Aldabra, 23 Galapagos, and five African spurred) were included, resulting in 64 anesthetic events. Frequently used premedication protocols included an α-adrenergic agonist and ketamine combined with either midazolam (group αadrenergic agonist, midazolam, ketamine, AMK; n = 34), a μ-opioid receptor agonist (group αadrenergic agonist, μ-opioid receptor agonist, ketamine, AOK; n = 13), or a μopioid receptor agonist and midazolam (group αadrenergic agonist, midazolam, μ-opioid receptor agonist, ketamine, AMOK; n = 10). Inhalant anesthetics (isoflurane, n = 21; sevoflurane, n = 23) were frequently used for maintenance of anesthesia following premedication. Out of the 34 total tortoises, 22 had only one anesthetic event, five had two anesthetic events, three had three anesthetic events, and four had four or more anesthetic events. Few adverse effects were observed and there was no mortality reported during the peri-anesthetic period. Sedation and general anesthesia of giant tortoises can be successfully performed with a combination of an α-adrenergic agonist and ketamine in combination with midazolam and/or a μopioid receptor agonist.

Pathogenetic features of acute naphazoline poisoning in children

Introduction: Acute poisoning by nasal decongestants is an important issue in pediatrics due to physiological and anatomical characteristics of the child’s body and pharmacokinetics of drugs in early childhood. Epidemiology: The number of poisonings by this group of drugs ranged from 4% to 39% during the period from 2000 to 2018. All the studies reported that the most severe degree of intoxication was observed in children aged 1–3 years. Mechanism of action of nasal decongestants: The peculiarity of selective alpha2-adrenergic agonists is that when taken orally, misused or overdosed, they lose their selectivity for the target receptor. As a result, the drug causes acute poisoning and most often this effect occurs in children and adolescents. Clinical features and diagnostic criteria: Clinical signs of acute poisoning can appear both as a result of an overdose of the nasal decongestants and due to a therapeutic use of the drug according to the instruction. The symptoms are manifested by hypothermia, skin pallor, bradycardia, arterial hypotension, profuse sweating, and acrocyanosis. Imidazoline receptors and new opportunities: It is assumed that toxic effect of topical decongestants occurs not only by activation of alpha2-adrenergic receptors, but also through their influence on the selective imidazoline receptors. Based on the structure of these drugs, it is assumed that imidazoline receptors are the primary binding site for these drugs. Conclusion: Understanding the described mechanisms of alpha2-adrenergic agonist action and peculiarities of the child’s symptoms in acute poisoning is necessary for the timely diagnosis and selection of the correct treatment strategy.

Combined agonists act synergistically to increase mucociliary clearance in a cystic fibrosis airway model

Mucus clearance, a primary innate defense mechanism of airways, is defective in patients with cystic fibrosis (CF) and CF animals. In previous work, the combination of a low dose of the cholinergic agonist, carbachol with forskolin or a β adrenergic agonist, isoproterenol synergistically increased mucociliary clearance velocity (MCCV) in ferret tracheas. Importantly, the present study shows that synergistic MCCV can also be produced in CF ferrets, with increases ~ 55% of WT. Synergistic MCCV was also produced in pigs. The combined agonists increased MCCV by increasing surface fluid via multiple mechanisms: increased fluid secretion from submucosal glands, increased anion secretion across surface epithelia and decreased Na+ absorption. To avoid bronchoconstriction, the cAMP agonist was applied 30 min before carbachol. This approach to increasing mucus clearance warrants testing for safety and efficacy in humans as a potential therapeutic for muco-obstructive diseases.

The endogenous circadian system worsens asthma at night independent of sleep and other daily behavioral or environmental cycles

Asthma often worsens at night. To determine if the endogenous circadian system contributes to the nocturnal worsening of asthma, independent of sleep and other behavioral and environmental day/night cycles, we studied patients with asthma (without steroid use) over 3 wk in an ambulatory setting (with combined circadian, environmental, and behavioral effects) and across the circadian cycle in two complementary laboratory protocols performed in dim light, which separated circadian from environmental and behavioral effects: 1) a 38-h “constant routine,” with continuous wakefulness, constant posture, 2-hourly isocaloric snacks, and 2) a 196-h “forced desynchrony” incorporating seven identical recurring 28-h sleep/wake cycles with all behaviors evenly scheduled across the circadian cycle. Indices of pulmonary function varied across the day in the ambulatory setting, and both laboratory protocols revealed significant circadian rhythms, with lowest function during the biological night, around 4:00 AM, uncovering a nocturnal exacerbation of asthma usually unnoticed or hidden by the presence of sleep. We also discovered a circadian rhythm in symptom-based rescue bronchodilator use (β2-adrenergic agonist inhaler) whereby inhaler use was four times more likely during the circadian night than day. There were additive influences on asthma from the circadian system plus sleep and other behavioral or environmental effects. Individuals with the lowest average pulmonary function tended to have the largest daily circadian variations and the largest behavioral cycle effects on asthma. When sleep was modeled to occur at night, the summed circadian, behavioral/environmental cycle effects almost perfectly matched the ambulatory data. Thus, the circadian system contributes to the common nocturnal worsening of asthma, implying that internal biological time should be considered for optimal therapy.

Negative regulation of melatonin secretion by melatonin receptors in ovine pinealocytes

Melatonin (MLT) is a biological modulator of circadian and seasonal rhythms and reproduction. The photoperiodic information is detected by retinal photoreceptors and transmitted through nerve transmissions to the pineal gland, where MLT is synthesized and secreted at night into the blood. MLT interacts with two G protein-coupled receptors, MT1 and MT2. The aim of our work was to provide evidence for the presence of MLT receptors in the ovine pineal gland and define their involvement on melatonin secretion. For the first time, we identified the expression of MLT receptors with the specific 2-[125I]-MLT agonistic radioligand in ovin pinealocytes. The values of Kd and Bmax are 2.24 ± 1.1 nM and 20 ± 6.8 fmol/mg. MLT receptors are functional and inhibit cAMP production and activate ERK1/2 through pertussis toxin-sensitive Gi/o proteins. The MLT receptor antagonist/ inverse agonist luzindole increased cAMP production (189 ± 30%) and MLT secretion (866 ± 13%). The effect of luzindole on MLT secretion was additive with the effect of well-described activators of this pathway such as the β-adrenergic agonist isoproterenol and the α-adrenergic agonist phenylephrine. Co-incubation of all three compounds increased MLT secretion by 1236 ± 199%. These results suggest that MLT receptors are involved in the negative regulation of the synthesis of its own ligand in pinealocytes. While adrenergic receptors promote MLT secretion, MLT receptors mitigate this effect to limit the quantity of MLT secreted by the pineal gland.