[Application of extracorporeal membrane oxygenation technique in patients with refractory shock caused by dichlorvos poisoning]

Dichlorvos poisoning can cause muscarinic (M) -like symptoms, nicotinoid (N) -like symptoms and central nervous system manifestations. When severe poisoning is combined with refractory shock, the mortality rate exceeds 60%. At present, there are more and more studies on ECMO for poisoning, but there is no report on ECMO for treating refractory hypotension caused by dichlorvos poisoning. We analyzed 3 successful cases of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in the treatment of refractory shock caused by acute severe dichlorvos poisoning to explore the effectiveness of VA-ECMO in patients with severe poisoning.

Cholinergic Mushroom Poisoning With a Detection of Muscarine Toxin in Urine

We report an uncommon case of cholinergic poisoning following an ingestion of wild mushrooms. Two middle-aged patients presented to the emergency unit with acute gastrointestinal symptoms including epigastric pain, vomiting and diarrhea, followed by miosis, palpitations and diaphoresis which were compatible with a cholinergic toxidrome. The patients volunteered a history of taking two tablespoons of cooked wild mushrooms collected in a country park. Mildly elevated liver transaminase was noted in one female patient. Mushroom specimens were sent to a mycologist for identification using morphological analysis. Muscarine, a cholinergic toxin found in mushrooms such as Inocybe and Clitocybe species, was subsequently extracted from and identified in the urine specimens of both patients, using a liquid-chromatography tandem mass spectrometry method. In this report, the variable clinical presentation of cholinergic mushroom poisoning is discussed. Key issues in the management of these cases were presented. In addition to conventional mushroom identification methods, this report also highlights the use of toxicology tests on different biological and non-biological specimens for diagnosis, prognosis and surveillance purposes.

M4 muscarinic receptors mediate acetylcholine-induced suppressant effects on the cough reflex in the caudal nucleus tractus solitarii of the rabbit

It has been shown that muscarinic acetylcholine receptors (mAChRs) located within the caudal nucleus tractus solitarii (cNTS) mediate a cholinergic inhibitory control mechanism of the cough reflex. Thus, identification of the involved mAChR subtypes could be of considerable interest for novel therapeutic strategies. In pentobarbital sodium-anesthetized, spontaneously breathing rabbits we investigated the contribution of different mAChR subtypes in the modulation of mechanically- and chemically-induced cough reflex. Bilateral microinjections of 1 mM muscarine into the cNTS increased respiratory frequency and decreased expiratory activity even to the complete suppression. Interestingly, muscarine induced strong cough-suppressant effects up to the complete abolition of the reflex. Microinjections of specific mAChR subtype antagonists (M₁-M₅) into the cNTS were performed. Only microinjections of the M₄ antagonist tropicamide (1 mM) prevented muscarine-induced changes in both respiratory activity and cough reflex. The results are discussed in light of the notion that cough involves the activation of the nociceptive system. They also suggest that M₄ receptor agonists may have an important role in cough downregulation within the cNTS.

Toxin screening of Pseudosperma umbrinellum (Agaricals, Basidiomycota): First report of phalloidin in Inocybaceae mushroom

Pseudosperma species are widely distributed worldwide. Many of them cause poisoning incidents every year, and the toxin responsible for poisoning is muscarine, which could stimulate the parasympathetic nervous system. This study established a method using multiwalled carbon nanotube purification and liquid chromatography-tandem mass spectrometry for the targeted screening of mushroom toxins (muscarine, isoxazole derivatives, tryptamine alkaloids, three amatoxins and three phallotoxins) from Pseudosperma umbrinellum, a common poisonous mushroom distributed in north and northwestern China. Surprisingly, in addition to muscarine, phalloidin was also detected in P. umbrinellum, and the contents were 3022.2 ± 604.4 to 4002.3 ± 804.6 mg/kg (k = 2; p = 95%) muscarine and 5.9 ± 1.2 to 9.3 ± 1.8 mg/kg (k = 2; p = 95%) phalloidin.

The effects of acetylcholinesterase inhibitors on morbidity after general anesthesia and surgery

Non-depolarizing neuromuscular blocking agents are used during general anesthesia to facilitate intubation and optimize surgical conditions. When patients leave the operating room after surgery, postoperative residual neuromuscular block occurs frequently, increasing vulnerability to respiratory complications such as hypoxemia and unplanned postoperative mechanical ventilation. To restore neuromuscular transmission and skeletal muscle strength, anesthesiologists typically administer peripherally acting acetylcholinesterase inhibitors such as neostigmine. However, neostigmine's desirable effects have a narrow therapeutic range. Even at recommended dose (15-50 μg/kg), neostigmine induces nicotinic (upper airway muscle weakness leading to dysphagia and upper airway obstruction, and decreased maximum inspiratory airflow) and muscarinic (blurred vision, bronchial constriction, abdominal cramping and nausea) side effects. Recent data have questioned as to whether neostigmine reversal of neuromuscular blockade improves relevant patient outcomes such as postoperative respiratory and perioperative cardiovascular complications. A central strategy to avoid side effects of neuromuscular blocking agents is their judicious use based on quantitative monitoring of neuromuscular transmission using repetitive peripheral nerve stimulation (train-of-four ratio). Peripherally acting acetylcholinesterase inhibitors such as neostigmine should then only be administered when indicated and dosed based on results of the train-of-four ratio.

Mushroom poisoning from Inocybe serotina: A case report from Ningxia, northwest China with exact species identification and muscarine detection

Mushroom poisoning is a serious food safety issue in China. However, there is insufficient information on many poisoning incidents, including mushroom species and their clinical manifestations, diagnosis, treatments and toxins. Detailed epidemiological investigation was conducted after the occurrence of a mushroom poisoning incident resulting in typical muscarinic syndrome in Ningxia, China. The suspected mushroom species was identified based on morphological and phylogenetic analyses. Muscarine was detected using ultrahigh-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). On September 2, 2019, two patients exhibited typical muscarinic syndrome after consuming wild mushrooms. The clinical manifestations included chills, sweating, salivation and diarrhoea; the incubation period was approximately 2 h. Treatments, including anti-inflammatory, detoxification and nutritional support, were remedial. Full recovery ensued within 24 h. The specimen was identified as Inocybe serotina, and its muscarine content was 324.0 ± 62.4 mg/kg (k = 2, p = 95%). Two patients were poisoned via stimulation of their parasympathetic nervous system due to mistaken consumption of muscarine-containing I. serotina. They fully recovered with supportive treatments. To our knowledge, this is the first case report of I. serotina poisoning worldwide and is the first record of this species in China. Further, a method for muscarine detection was established using UPLC-MS/MS.

Muscarinic cholinoreceptors (M1-, M2-, M3- and M4-type) modulate the acetylcholine secretion in the frog neuromuscular junction

Muscarinic cholinoreceptors regulate the neurosecretion process in vertebrate neuromuscular junctions. The diversity of muscarinic effects on acetylcholine (ACh) secretion may be attributed to the different muscarinic subtypes involved in this process. In the present study, the location of five muscarinic receptor subtypes (M1, M2, M3, M4 and M5) on the motor nerve terminals of frog cutaneous pectoris muscle was shown using specific polyclonal antibodies. The modulatory roles of these receptors were investigated via assessment of the effects of muscarine and specific muscarinic antagonists on the quantal content of endplate currents (EPCs) and the time course of secretion, which was estimated from the distribution of "real" synaptic delays of EPCs recorded in a low Ca²⁺/high Mg²⁺ solution. The agonist muscarine decreased the EPC quantal content and synchronized the release process. The depressing action of muscarine on the EPC quantal content was abolished only by pretreatment of the preparation with the M3 blockers 4-DAMP (1,1-Dimethyl-4-diphenylacetoxypiperidinium iodide) and J 104129 fumarate ((αR)-α-Cyclopentyl-α-hydroxy-N-[1-(4-methyl-3-pentenyl)-4-piperidinyl]benzeneacetamide fumarate). Moreover, antagonists of the M1, M2, M3 and M4 receptors per se diminished the intensity of secretion, which suggests a putative up-regulation of the release by endogenous ACh.

Two-Dimensional Surface Plasmon Resonance Imaging System for Cellular Analysis

Optical biosensors based on surface plasmon resonance (SPR) phenomenon have received a great deal of attention in cellular analysis applications. Sensitive and high-resolution SPR imaging (SPRi) platforms are very useful for real-time monitoring and measurement of individual cell responses to various exogenous substances. In cellular analysis, mainstream SPR-based sensors have potential for investigations of cell responses under ambient conditions. Evaluations that account only for the average response of cell monolayers mask the understanding of precise cell-molecular interactions or intracellular reactions at the level of individual cells. SPR/SPRi technology has attracted a great deal of attention for detecting the response of cell monolayers to various substances cultivated on the gold sensor chip. To unleash the full strength of SPRi technology in complex cell bio-systems, the applied SPR imaging system needs to be sufficiently effective to allow evaluation of a compound's potency, specificity, selectivity, toxicity, and effectiveness at the level of the individual cell. In our studies, we explore the utility of high-resolution 2D-SPR imaging for real-time monitoring of intracellular translocation of protein kinase C (PKC), and detection of neuronal differentiation in live cells at the level of individual cells. The PC12 cell line, which is one of the most commonly used neuronal precursor cell lines for research on neuronal differentiation, was chosen as a nerve cell model. Two dimensional SPR (2D-SPR) signals/images are successfully generated. We have found that cells treated with the differentiation factor nerve growth factor (NGF) showed a remarkable enhancement of SPR response to stimulation by muscarine, a nonselective agonist of the muscarinic acetylcholine receptor.