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)

Pyridostigmine bromide, a quaternary carbamate, is widely used in treatment of myasthenia gravis and has been suggested for use in prophylaxis against intoxication with irreversible cholinesterase inhibitors. Since there are virtually no anatomical data concerning the neuromuscular toxicity of the drug, this study was undertaken to evaluate the effects of acute and subacute doses of pyridostigmine on the ultrastrucutre of nerve terminals in rat diaphragm neuromuscular junctions (NMJs). Pyridostigmine in a Mestinon-equivalent buffer was administered by single, subcutaneous injection (acute exposure; 10-30 min) or by a subcutaneously implanted Alzet osmotic minipump (subacute exposure; 2, 7 or 14 days). Acute exposure doses ranged from 0.0036 mg/kg to 3.6 mg/kg (0.001-1.0 LD50), while subacute exposure doses ranged from 0.43 to 20 mg of the drug. Both acute and subacute exposures resulted in dose dependent alterations of presynaptic elements in diaphragmatic NMJs, which included disruption of organelles in the axon terminal, regional or total withdrawal of the nerve terminal from postsynaptic junctional folds, and invasion of Schwann cell fingers into the synaptic cleft. These ultrastructural observations suggest that the normal cell-to-cell interactions at diaphramatic NMJs are altered by this "reversible," cholinesterase inhibiting drug.
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PMID:Ultrastructural effects of pyridostigmine on neuromuscular junctions in rat diaphragm. 371 19

Motor innervation and acetylcholine receptor distribution of human extraocular muscle (EOM) fibres were investigated by using combined silver and acetylcholinesterase (AChE) staining method and [125I]alpha-bungarotoxin autoradiography. Three types of motor endplates were distinguished; (A) a large compact ending on a large-diameter fibre, (B) several endings regularly spaced on an intermediate-diameter fibre, each of which consisted of small stained particles and (C) numerous small endings scattered as a chain of beads on a small-diameter fibre. Type A fibre was singly innervated, while type B and C had multiterminal (possibly polyneuronal) innervation. These results indicate that the organization of human EOM endplates is quite different from that of limb muscle endplates and may provide some implications to understand the pathophysiology of the neuromuscular diseases, for example, myasthenia gravis.
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PMID:Motor innervation and acetylcholine receptor distribution of human extraocular muscle fibres. 373 34

Fourteen patients (twelve of them were women) with severe myasthenia gravis who had not responded to any treatment at all, were treated by cytostatic drugs. Both azathioprine and cyclophosphamide single or in combination are used. All patients except two were thymectomized and almost all were treated by plasmapheresis and corticosteroid before and during the cytostatic treatment. All patients take cholinesterase inhibitors. No serious complications were observed. The patients received 100-200mg of azathioprine and/or 100-200mg of cyclophosphamide daily by oral route, the first during 20 months and the second one during 6 months. Three patients received cyclophosphamide 1g daily by venous route during 6 months at 15-20 days intervals. The preliminary results were favourable occurring important improvement in 71.4% of the cases. Their performance increased considerably. The progress of the disease was generally stabilized. Exacerbations and crises did not recur, except in one case. Only three patients had not responded to the treatment, one responded poorly but better later and one had an exacerbation after the 24th month. This patient returned to azathioprine.
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PMID:[Treatment of myasthenia gravis by immunosuppressive non-steroidal drugs]. 380 Jun 86

Inhibitors of acetylcholinesterase are commonly used in the treatment of myasthenia gravis. We studied a patient with mainly bulbar myasthenia gravis who did not tolerate oral pyridostigmine despite a clear clinical response. Treatment with nebulized pyridostigmine reduced her symptoms without systemic side effects. This route of therapy may benefit other patients.
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PMID:Topical therapy for oropharyngeal symptoms of myasthenia gravis. 396 62

Ocular myasthenia is a special form of general myasthenia gravis characterized by unilateral or bilateral ptosis and eye muscle pareses of distinct variability, depending on the time of day and the state of fatigue of the patient. Most important for diagnosis is the Tensilon test, which can, however, produce negative results. In such cases a combination of the Tensilon test with electromyography is indispensable. In ocular myasthenia there is not always an increase in the antibody titer against acetylcholine receptors in the blood. The treatment of ocular myasthenia is based on the application of cholinesterase inhibitors. The drug of choice is Mestinon; however, the reaction of the eye muscles to this drug is often unsatisfactory. Local application of cholinesterase inhibitors in the form of Eserine, Prostigmin etc. is an additional important therapy. Also in ocular myasthenia the modern treatment with Cortisone (alternate-day therapy with 100 mg Prednisone every second day) has proved very useful. Another possible method of interfering with the immunological systems of myasthenia is immunosuppression with Azathioprin or Cyclophosphamide. The pathognomonic significance of the thymus in the autoimmune process of myasthenia gravis is demonstrated by the good results obtained by thymectomy, which can also be performed successfully in ocular myasthenia, not only in young patients in whom the condition is severe, but also in older patients in whom it is chronic. Often, the therapeutic measures mentioned have to be tested one after another or in combination in order to achieve an optimal therapeutic effect.
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PMID:[Ocular myasthenia]. 399 98

When a quantum of transmitter is released into a synaptic cleft, the magnitude of the subsynaptic response depends upon how much transmitter becomes bound to receptors. Theoretical considerations lead to the conclusion that if receptor density is normally high enough that most of the quantal transmitter is captured, subsynaptic quantal responses may be insensitive to receptor blockade. The effectiveness of receptor blockers in depressing the subsynaptic response should be diminished by interference with processes that normally dispose of transmitter, but increased if receptor density is reduced. In conformity with equations derived from a simple mathematical model, the apparent potency of (+)-tubocurarine (dTC) to depress the peak height of miniature end-plate currents (MEPCs) in mouse diaphragm was substantially reduced by poisoning of acetylcholinesterase (AChE) and increased by partial blockade of receptors by immunoglobulin G from patients with myasthenia gravis or alpha-bungarotoxin. We calculated from the data that normally capture of quantal acetylcholine (ACh) by receptors is approximately 75% of what it would be if there were no loss of ACh by hydrolysis or diffusion of ACh form the synaptic cleft. This fraction is increased to approximately 90% by poisoning of AChE. Conversely, it normally requires blockade of approximately 80% of receptors-and after AChE poisoning, approximately 90% of receptors-to reduce ACh capture (and MEPC height) by 50%. The apparent potency of dTC to alter MEPC time-course (after AChE poisoning) and to depress responses to superperfused carbachol was much greater than its apparent potency to depress MEPC height, but corresponded closely with the potency of dTC to block receptors as calculated from the action of dTC on MEPC height. These results indicate that the amplitude of the response to nerve-applied acetylcholine does not give a direct measure of receptor blockade; it is, in general, to be expected that an alteration of subsynaptic receptor density may not be equally manifest in responses to exogenous and endogenous neurotransmitter.
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PMID:Relation between subsynaptic receptor blockade and response to quantal transmitter at the mouse neuromuscular junction. 612 Feb 8

In a survey of 21 patients with myasthenia gravis receiving regular acetylcholinesterase inhibitor therapy, 8 were found to have air-flow limitation associated with their antimyasthenic therapy. In 6 of these subjects, detailed assessments were made of the effect of antimyasthenic therapy on airways function. Pyridostigmine was given together with either placebo or the anticholinergic bronchodilator ipratropium bromide (72 micrograms) by inhalation administered double blind on 2 consecutive days. Airways resistance (Raw) increased significantly after pyridostigmine and placebo inhaler (0.49 +/- 0.13 kPa/L/s basal versus 0.60 +/- 0.13 kPa/L/s at 2 h; mean +/- SEM, p less than 0.05), whereas a significant decrease in Raw followed the combination of pyridostigmine with ipratropium bromide (0.57 +/- 0.08 kPa/L/s basal versus 0.41 +/- 0.07 kPa/L/s at 2 h, p less than 0.05). Thus, acetylcholinesterase inhibitor therapy in subjects with myasthenia gravis with airflow limitation led to significant increase in airways resistance that could be completely reversed by the inhalation of the muscarinic receptor blocker ipratropium bromide.
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PMID:Air-flow limitation in myasthenia gravis. The effect of acetylcholinesterase inhibitor therapy on air-flow limitation. 622 24

Twenty cases of failing transcervical thymectomy are reported. They were selected for transsternal re-exploration from a series of 95 patients who had previously undergone transcervical thymectomy because of myasthenia gravis (MG). A specific method for pre-operative detection of remnants of the non-tumorous thymic gland is lacking, but the applied clinical selection criteria were so far reliable: generalized, disabling, fluctuating MG despite cholinesterase inhibitor and/or immunosuppressive treatment, and no or inconsistent improvement after transcervical thymectomy. At transsternal re-exploration the commonest findings were intact lower thymic lobes with persistent venous drainage into the brachiocephalic vein. Presence of thymic tissue was histologically confirmed in all the excised specimens (weight range 10-60, mean 23 g), and the examination showed thymic hyperplasia in 18 cases, fatty involution of the gland in two, and a lympho-epithelial thymoma in one case. The re-operation was followed by objectively registrable improvement in all but one of the 20 patients during observation periods of 8-75 (mean 21) months. There was statistically significant reduction in disability scores (means 8.2-4.9) and in need for anticholinesterase medication (to 67% of pretreatment dose). Immunosuppression became unnecessary in 6 of 11 patients and could be reduced in 4 patients. The incidence of failure in transcervical thymectomy was alarmingly high (27%), and more re-operations are anticipated. Since the transcervical approach involves a high risk of incomplete thymectomy, its use should be abandoned. However, in most of the patients with re-operation, subsequent progress has been sufficiently promising for advocacy of sternotomy whenever the clinical criteria of failure are fulfilled.
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PMID:Failing transcervical thymectomy in myasthenia gravis. An evaluation of transsternal re-exploration. 652 69

A case of severe myasthenia gravis diagnosed in a 12-month-old girl is described. Thymectomy at 15 months of age had only a negligible effect on the course of the disease. Treatment with cholinesterase inhibitors, prednisolone and azathioprine was started. After one year of combined treatment she was symptomfree and 3 years later treatment with cholinesterase inhibitors and prednisolone was discontinued. Attempts to withdraw azathioprine have so far been unsuccessful, leading to relapse of the disease. IgG-antibodies against cholinergic receptors were lowered to near normal, whereas the levels of total plasma immunoglobulins remained normal. The proportion of T-lymphocytes in peripheral blood was reduced during the first weeks after thymectomy, but has since been normal. Lymphocyte function measured by PHA stimulation remained normal all the time. The girl grew and developed normally without complicating infectious diseases in spite of her severe disease, thymectomy and immunosuppressive treatment.
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PMID:Myasthenia gravis. Immunological studies in a young child treated with thymectomy and immunosuppressive drugs. 660 92

To investigate pathogenic mechanisms in experimental autoimmune myasthenia gravis (EAMG) and myasthenia gravis (MG), we studied the acute and chronic effects in rats of injection of rat monoclonal antibodies ( MCABs ) directed against the acetylcholine receptor (AChR). Animals were severely weak 12 h after a single injection, at which time macrophages were found invading endplate regions of muscle and cholinesterase-stained regions were separted from the underlying muscle fibers. Ultrastructural studies showed findings identical to the acute phase of EAMG: degenerating postsynaptic membranes and invasion and phagocytosis of endplate regions by macrophages. Animals receiving sublethal doses of MCAB recovered clinically by 4-5 days after injection. Recovery was accompanied by a progressive decrease in the number of macrophages associated with endplates and reapposition to the myofibers of the cholinesterase-stained regions. Animals injected once, or repeatedly over several months, remained clinically and electromyographically normal after recovery from the initial episode of weakness, but their endplate ultrastructure was highly simplified with blunted or absent synaptic folds and shallow or absent secondary synaptic clefts. These studies demonstrate that anti-AChR MCABs can induce the changes of both acute and chronic EAMG. There is good correlation between the inflammatory changes and the acute clinical disease but poor correlation between morphological and clinical parameters in the chronic syndrome. The latter observation suggests that severe ultrastructural changes, similar to those seen in chronic EAMG and MG, cannot account, at least in rats, for the clinical and electrophysiologic abnormalities of MG.
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PMID:Induction of the morphologic changes of both acute and chronic experimental myasthenia by monoclonal antibody directed against acetylcholine receptor. 661 Feb 75


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