Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Physostigmine was originally isolated from the Calabar Bean, which was used for ordeal by poison in West Africa. The main alkaloid was isolated in 1864. It acts through inhibition of acetylcholinesterase, and has been of major importance in elucidating the kinetics and configuration of the enzyme. Physostigmine has been important for our understanding of neurohumoral chemical transmission, and in mapping the cholinergic nerves. It was the first antagonist to curare, and has been widely used for various therapeutic purposes. Today it has been largely replaced by more efficient and safe drugs. It is still used as an antidote to poisoning from various psychopharmacological drugs, and to treat postoperative somnolence and respiratory depression. It is considered a potent antidote to organophosphorous poisoning and is used experimentally to treat Alzheimer's disease.
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PMID:[Development of physostigmine from a poisonous plant to an antidote. One of the most important drugs in the development of modern medicine?]. 157 14

The effect of physostigmine, a cholinesterase inhibitor, on the loss of consciousness induced by three different intravenous induction anesthetics, namely midazolam, etomidate and althesin at ED50, was studied in three comparable groups of patients. Ten min before induction, the first and second groups received physostigmine 8 micrograms/kg and 16 micrograms/kg, respectively, and the third group received 2 ml of saline solution. Physostigmine 16 micrograms/kg resulted in a significant decrease in the percentage of unconscious patients with midazolam (from 50% to 10%), but it did not modify the incidence with etomidate or althesin. Physostigmine at doses of 8 micrograms/kg and 16 micrograms/kg could cause 6.7% and 10% nausea, respectively. Although the mechanism of the drug interaction of physostigmine and midazolam is unclear, physostigmine could be used clinically to reverse post-anesthetic somnolence induced by midazolam.
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PMID:Effect of physostigmine on the loss of consciousness induced by midazolam, etomidate and althesin. 175 60

The effect of physostigmine on the loss of consciousness and respiratory depression induced in rabbits by flunitrazepam, 1 mg/kg, was studied to demonstrate whether the restoration of consciousness and respiration rate results from an increase in central cholinergic activity or from an interference by physostigmine with specific binding of flunitrazepam to its receptors. Physostigmine, 0.1-0.4 mg/kg iv, caused a dose-related reversal of consciousness and respiration rate within 15 min of its injection, which lasted 15-30 min depending on the dose. This was associated with peak inhibition of acetylcholinesterase (AChE) in the frontal cortex and medulla, at 15 min, ranging from 35-51%. The analeptic effect of physostigmine in flunitrazepam-treated rabbits was prevented by pretreatment with scopolamine, 1 mg/kg. The effective dose range for physostigmine, 3-12 mumol/kg, is close to concentrations of this agent that inhibit activity in solubilized preparations of AChE from rabbit cortex, 1-3 X 10(-8) M. However, physostigmine, 10(-9) -10(-4) M, failed to displace 3H flunitrazepam from specific binding sites on membranes prepared from rabbit cerebral cortex. It is concluded that physostigmine antagonizes the somnolence and respiratory depression induced by benzodiazepines by restoring cholinergic transmission to normal levels. The effective dose range of physostigmine is small, and serious side effects from overdose can occur as a result of excess cholinergic activity at neuromuscular synapses.
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PMID:Mechanism of antagonism by physostigmine of acute flunitrazepam intoxication. 300 60

This case illustrates the effect of abnormal pseudocholinesterase on the metabolism and actions of chloroprocaine in a postpartum patient. The patient apparently could not adequately metabolize chloroprocaine which may have led to excessive somnolence intraoperatively. It also led to a prolonged chloroprocaine block (normally the block would last only 45-60 minutes) of 3 hours as well as to detectable serum chloroprocaine 5 hours after administration. Abnormal pseudocholinesterase was verified by the prolonged apnea following subsequent succinylcholine administration and by the fact that her dibucaine number at 6 weeks postpartum was indicative of a homozygote for the atypical cholinesterase variant or a heterozygote with 1 gene for the atypical variant and one for the silent variant. This case suggests that an abnormal reaction to chloroprocaine can occur in a patient with atypical cholinesterase and that an abnormal reaction to chloroprocaine has clinical implications beyond a prolonged epidural block. An abnormal reaction to chloroprocaine should alert the anesthesiologist to the possibility of a pseudocholinesterase deficiency which should suggest that the subsequent use of succinylcholine may result in a prolonged neuromuscular blockade.
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PMID:A prolonged chloroprocaine epidural block in a postpartum patient with abnormal pseudocholinesterase. 708 36

Organophosphates are frequently used as insecticides in agricultural areas, therefore they may pose a risk for accidental exposure by dermal contact or through inhalation. We present the cases of eight young men, who worked unprotected and inexperienced with organophosphates. They were exposed dermally and developed mainly gastrointestinal symptoms and also diaphoresis, hypersalivation, blurred vision and miosis. One patient developed severe weakness, fasciculations, disorientation and sleepiness. All had low levels of plasma acetylcholinesterase. All were admitted to the hospital and received antidotal treatment of atropine and toxogonin. They were released after 48 hours in good physical condition. The hospital staff rapidly diagnosed the organophosphate intoxication; additional doctors and nurses were called to the emergency department. The patients were decontaminated in showers within the hospital. This case emphasizes the need for workers handling pesticides, to be supervised by an experienced person and the advantages of hospital drills in rapid diagnosis and preparedness to provide treatment to many patients.
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PMID:[Organophosphate poisoning in inexperienced workers]. 1157 29

Diffuse Lewy body disease (DLB) is a neurodegenerative disorder characterized by dementia, fluctuations in mental status, hallucinations, and parkinsonism. Diffuse Lewy body disease is the second most common cause of dementia, following Alzheimer's disease. The treatment of DLB includes cholinergic therapy for cognitive impairment, atypical neuroleptics to alleviate hallucinations, and levodopa/carbidopa to improve parkinsonism. The recognition and diagnosis of DLB has critical treatment implications. Centrally acting cholinesterase inhibitors, such as rivastigmine, donepezil, and galantamine partially reverse decreased cortical cholinergic activity and may improve cognition and neuropsychiatric symptoms in DLB. Rivastigmine has been demonstrated to improve cognition and neuropsychiatric symptoms in patients with DLB without worsening parkinsonian features. Due to the potential adverse events associated with neuroleptics in this population, treatment with cholinesterase inhibitors is currently considered first-line therapy in the treatment of hallucinations and mental status fluctuations in DLB. Exquisite sensitivity to neuroleptic medications is a hallmark of DLB and life-threatening complications have been reported. Caution should be exercised when implementing antipsychotic therapy for the treatment of behavioral disturbances of DLB. When required, atypical neuroleptics with the least extrapyramdial side effects, such as quetiapine, should be used. The parkinsonian features of DLB may respond to dopaminergic therapy with levodopa. If parkinsonian symptoms result in clinical disability, a trial of levodopa is warranted. Unfortunately, dopaminergic medications may worsen hallucinations. Because dopamine agonists have a greater tendency to induce hallucinations and somnolence, levodopa is the treatment of choice for parkinsonism in DLB. Rapid eye movement (REM) sleep behavior disorder (RBD) is now recognized as a feature of DLB. Awareness of the presence of this symptom in patients with DLB is important and treatment with low dose clonazepam may help. Cholinergic aumentation may also improve these symptoms in patients with DLB.
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PMID:Diffuse Lewy Body Disease. 1158 27

The long-acting anticholinesterase, distigmine bromide (Ubretid), is widely used for the treatment of underactive neurogenic bladder. Therefore, we emphasize its hazardable side-effect of cholinergic crisis. A 78-year-old man with duodenal ulcer complained of nocturia, and was administered distigmine bromide 10 mg daily under the diagnosis of mild benign prostatic hypertrophy with underactive neurogenic bladder. It seemed that administration slightly improved his symptom but he developed bradycardia, dyspnea and drowsiness suddenly on the 4th day. Blood examination revealed extremely low cholinesterase in his serum, suggesting distigmine bromide intoxication. He was treated intensively with several intravenous injections of atropine, high-concentration oxygen and transfusion of fresh frozen plasma. Nevertheless, his condition did not recover, resulting in death of "cholinergic crisis" on the 6th day.
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PMID:[Cholinergic crisis following administration of distigmine bromide: a case report]. 1186 80

Microbiological, biological, and chemical toxins have been employed in warfare and in terrorist attacks. In this era, it is imperative that health care providers are familiar with illnesses caused by these agents. Botulinum toxin produces a descending flaccid paralysis. Staphylococcal enterotoxin B produces a syndrome of fever, nausea, and diarrhea and may produce a pulmonary syndrome if aerosolized. Clostridium perfringens epsilon-toxin could possibly be aerosolized to produce acute pulmonary edema. Ricin intoxication can manifest as gastrointestinal hemorrhage after ingestion, severe muscle necrosis after intramuscular injection, and acute pulmonary disease after inhalation. Nerve agents inhibit acetylcholinesterase and thus produce symptoms of increased cholinergic activity. Ammonia, chlorine, vinyl chloride, phosgene, sulfur dioxide, and nitrogen dioxide, tear gas, and zinc chloride primarily injure the upper respiratory tract and the lungs. Sulfur mustard (and nitrogen mustard) are vesicant and alkylating agents. Cyanide poisoning ranges from sudden-onset headache and drowsiness to severe hypoxemia, cardiovascular collapse, and death. Health care providers should be familiar with the medical consequences of toxin exposure, and understand the pathophysiology and management of resulting illness.
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PMID:Microbiological, biological, and chemical weapons of warfare and terrorism. 1207 87

Pesticides, such as parathion, are metabolized by cytochrome p-450 system to paraoxon, which is a potent cholinesterase inhibitor. Paraoxonase (PON) catalyzes the hydrolysis of these toxic metabolites and protects against pesticide toxicity. A glutamine/arginine (Gln/Arg) polymorphism at amino acid position 192 of PON has been described. The Arg/Arg genotype is associated with higher serum paraoxonase activity compared to Gln/Gln. The Arg/Gln genotype is associated with intermediate serum PON activity. The potential association between PON genotype and symptoms of chronic pesticide toxicity was examined among 100 farm workers. As part of a cross-sectional study of pesticide toxicity among mixed-race farm workers in the Western Cape. South Africa, 100 farm workers were genotyped for polymorphism of the paraoxonase gene at amino acid position 192. Subjects with two or more of the following symptoms were considered to have evidence of chronic toxicity: abdominal pain, nausea, rhinorrhea, dizziness, headache, somnolence, fatigue, gait disturbance, limb numbness, paresthesias, limb pain, or limb weakness. In multivariable logistic regression analysis, the independent predictors of chronic toxicity were previous history of head trauma resulting in loss of consciousness (OR 2.8, 95% CI = 1.7-6.7), having worked as a pesticide applicator (OR 5.4, 95% CI = 3.2-8.9), and having one of the two "slow metabolism" (Gln/Gln or Gln/Arg) genotypes (OR 2.9, 95% CI = 1.7-6.9). Furthermore, the prevalence of chronic toxicity increased in a stepwise fashion from 15% among pesticide nonapplicators with a "fast metabolism" (Arg/Arg) genotype, to 42.9% among pesticide nonapplicators with "slow metabolism" (Gln/Gln or Gln/Arg) genotypes, to 58.8% among pesticide applicators with "fast metabolism" genotype, and 75.0% among pesticide applicators with "slow metabolism" genotypes (P = 0.001). Age, number of years on the job, smoking history, alcohol history, education level, plasma or red blood cell cholinesterase level, or previous history of acute organophosphate poisoning were not statistically significant predictors of chronic toxicity. The PON genotype is an important determinant of a farmworker's susceptibility to chronic pesticide poisoning.
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PMID:Association between human paraoxonase gene polymorphism and chronic symptoms in pesticide-exposed workers. 1262 27

Psychosis only rarely occurs in patients with untreated Parkinson's disease. Much more commonly, psychosis is induced by drug therapy for Parkinson's disease and is the strongest known risk factor for nursing home placement. Delusions are less frequent than hallucinations, but are more concerning as they are often paranoid in nature. Treatment begins with a search for correctable infectious, toxic, and metabolic aetiologies. If symptoms persist, anti-Parkinson's disease medications are slowly reduced. However, withdrawal of these drugs usually worsens parkinsonism and is often not tolerated. Certain atypical antipsychotics can be used to treat psychosis without compromising motor function. The choice of atypical antipsychotic is largely based on ease of use and adverse effect profile as most have comparable efficacy in improving psychosis. Currently, there are five marketed atypical drugs - clozapine, risperidone, olanzapine, quetiapine and ziprasidone. Ziprasidone is the only agent whose adverse effect profile has not been reported in Parkinson's disease. The most common adverse effects of clozapine in Parkinson's disease are sedation, orthostatic hypotension and sialorrhoea. Sedation is generally helpful since these patients are frequently awake at night and tend to have worse behavioural problems then. Clozapine does not induce deterioration of motor function, but it has the potential to cause agranulocytosis, which is idiosyncratic and not dose-related. In risperidone-treated Parkinson's disease patients, reported adverse effects include somnolence, sialorrhoea, dizziness, palpitations, constipation, delirium, fatigue, leg cramps, depression, urinary incontinence and hypotension. Although in some Parkinson's disease studies, risperidone has been well tolerated, others have shown that many patients are unable to tolerate the drug due to deterioration of motor function. While an initial study of olanzapine in Parkinson's disease psychosis showed the drug to be effective without deterioration of motor function, succeeding reports demonstrated a deleterious effect of the drug on motor functioning. The most common adverse effects of quetiapine in Parkinson's disease patients are sedation and orthostatic hypotension. There is a lack of double-blind trials; however, cumulative reports involving >200 Parkinson's disease patients strongly suggest that quetiapine is well tolerated and effective. Unlike clozapine, it does not improve tremor and may induce mild deterioration of motor function. Recently, cholinesterase inhibitors have been reported to alleviate psychosis in Parkinson's disease. Although ondansetron, an antiemetic with antiserotonergic properties, has been reported to relieve psychosis in Parkinson's disease, its prohibitive cost has prevented further study in this population. Electroconvulsive treatment is generally reserved for the patient with psychotic depression who is unable to tolerate any pharmacological therapy.
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PMID:Treatment of psychosis in Parkinson's disease: safety considerations. 1281 32


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