Lambert-Eaton myasthenic syndrome IgG: early morphologic effects and immunolocalization at the motor endplate.
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Animals↗
Biomedical subjects
D Wray
Publications and source records attributed to D Wray.
Oral 'hairy' leukoplakia associated with human immunodeficiency virus infection: report of two cases.
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Acquired Immunodeficiency Syndrome↗
Actions of beta-bungarotoxin on spontaneous release of transmitter at muscle end-plates treated with botulinum toxin.
Rat leg muscles were injected subcutaneously with sublethal doses of type A botulinum neurotoxin, and the extensor digitorum longus muscle removed three days later. Intracellular microelectrode recordings were then made of miniature end-plate potentials (mepps). The mepp frequency was reduced by botulinum toxin, while mepp rise times were slowed. Mepp amplitude distributions became characteristically skew. beta-Bungarotoxin (140 nM) was applied to normal muscles in vitro and recordings were made 10-30 min later. The main effect was an increase in mepp frequency during this period. Mepp rise times were unaffected. When beta-bungarotoxin was applied in vitro to muscles treated with botulinum toxin there was also an increase in mepp frequency, although to a value less than in normal muscles. The mepp rise times were speeded up to normal values. The mepp amplitude and rise time distributions showed no obvious evidence for the addition of a second component to the distribution. The data appear to support the hypothesis that the sites for spontaneous release in botulinised muscle may be located at or near the usual release sites at the active zones.
Animals↗
The effect of chronic neostigmine treatment on channel properties at the rat skeletal neuromuscular junction.
We have studied the effects of chronic neostigmine treatment on single channel properties at the rat skeletal neuromuscular junction. Rats received 0.86 mg kg-1 neostigmine (s.c.) daily for 9-11 days. Microelectrode recordings were then made from the extensor digitorum longus muscle. The amplitude of miniature endplate potentials was significantly reduced in muscles from neostigmine-treated rats as compared with controls. Acetylcholine (2-5 microM) applied in the bath produced a depolarization and associated channel opening frequency (from voltage noise analysis) which were significantly reduced in neostigmine-treated muscles with respect to controls. The depolarization resulting from the opening of a single channel (from voltage noise analysis) and single channel open time and conductance (from current noise analysis) were not significantly changed by chronic neostigmine treatment. It is concluded that chronic neostigmine treatment causes an adaptive reduction in the number of functional acetylcholine receptors at the endplate without otherwise affecting single channel properties themselves.
Animals↗
Anti-acetylcholine receptor antibodies induced in mice by syngeneic receptor without adjuvants.
Acetylcholine receptor (AChR)-bearing membranes from the BC3H-1 cell lines were injected, without adjuvant, either intrathymically (i.t.) followed by intraperitoneal (i.p.) booster doses, or i.p. alone, into (C57BL X BALB/c)F1 mice. Over 75% of the animals developed serum anti-AChRs which reacted with the cell-line AChR and with normal mouse endplate AChR. The titres were within the lower range of those of myasthenia gravis patients, and some mice showed reduced miniature endplate potential (m.e.p.p) amplitudes. these results indicate that loss of tolerance to acetylcholine receptors can result from immunization against syngeneic AChR without adjuvant. This approach may provide a useful model for studying mechanisms of autoimmunity against acetylcholine receptor.
Action Potentials↗
Action of Lambert-Eaton myasthenic syndrome IgG at mouse motor nerve terminals.
We have studied the electrophysiological effects of IgG obtained from four patients with Lambert-Eaton myasthenic syndrome (LEMS) (two with small cell carcinoma), using the mouse passive transfer model. Mice received LEMS or control IgG or plasma, 10 to 60 mg daily. Microelectrode intracellular recordings were made from diaphragm muscle. LEMS IgG and plasma decreased end-plate potential quantal content similarly, confirming IgG as the active factor. LEMS IgG was equally effective in C5-deficient mice, indicating that late complement components are not required. The time course of decline and recovery of quantal content closely followed that of the human IgG in the mouse serum, with time to half-maximal effect of about 1.5 days in each case. Binding/dissociation of IgG or down/up regulation of the antigenic determinants, possibly Ca2+ channels, has a half-life of between 2 and 36 hours. The results confirm our concept that IgG antibody to nerve terminal determinants underlies the disorder of transmitter release in LEMS.
Adult↗
Lytic effects of serum and mononuclear leukocytes on oral epithelial cells in recurrent aphthous stomatitis.
A radioisotope-release assay, utilizing 51Cr-labeled epithelial cells derived from non-keratinizing oral mucosa, was developed to investigate in vitro cytolytic reactions correlating with recurrent aphthous stomatitis (RAS). The cytolytic effects of sera and mononuclear leukocytes from patients in the early stage of ulceration were compared with those from matched RAS-negative control subjects. RAS sera induced significantly more cytolysis than did matched control sera. Heating the RAS or control sera for 30 min at 56 degrees C abrogated their cytotoxic activity. RAS mononuclear leukocytes, like their matched controls, showed no significant direct cytotoxicity. Heat-inactivated RAS or control sera acting in concert with RAS or control mononuclear leukocytes showed no consistent cytolytic effects. However, the heat-inactivated sera of some RAS patients, when combined with autologous mononuclear leukocytes, induced significantly more cytolysis than did either component acting alone. Thus heat-labile humoral factors and, in some cases, mononuclear leukocytes acting in concert with heat-stable serum factors are implicated in RAS-associated in vitro cytolytic reactions. These findings suggest that the effector mechanisms of such reactions include both complement-mediated and antibody-dependent cell-mediated cytotoxicity.
Antibody Formation↗
Electrophysiological effects of myasthenic serum factors studied in mouse muscle.
Miniature end-plate potential (mepp) amplitudes were investigated in mouse diaphragm exposed in vitro to different serum fractions from seven patients with myasthenia gravis who had elevated serum anti-acetylcholine receptor antibody levels and from controls. The mepp amplitudes were significantly reduced by whole myasthenic sera, restored by washing, and not reduced by heated (56 degrees C) myasthenic sera, which would inactivate complement but not antireceptor antibody. Immunoglobulin G (IgG)-depleted myasthenic sera also significantly reduced mepp amplitudes, while the IgG fraction alone or with normal serum did not. The results indicate that in vitro reduction of mepp amplitudes in mouse muscle by myasthenic sera is not dependent on the IgG fraction alone, and requires a heat-sensitive factor.
Adult↗
Antibodies to motor nerve terminals: an electrophysiological study of a human myasthenic syndrome transferred to mouse.
Immunoglobulin G(IgG) prepared from the plasma of patients with a presynaptic disorder of neuromuscular transmission (Lambert-Eaton myasthenic syndrome, l.e.m.s.), or from normal pooled control human plasma, was injected into mice (10 mg daily) for up to 99 days. Micro-electrodes were used to record end-plate potentials from the diaphragm muscle bathed in normal Krebs solution containing tubocurarine (1.0-4.6 microM). At 0.5 Hz nerve stimulation frequency, the quantal content was significantly reduced (P less than 0.01-P less than 0.001) in mice treated with six l.e.m.s. patients' IgG each compared with paired controls. The pooled quantal content was 55 +/- 3 (n = 110 end-plates) for all test animals and 131 +/- 9 (n = 47) for all controls (P less than 0.001). During short trains at 20 or 40 Hz nerve stimulation, control muscles showed marked depression, while test muscles showed either facilitation or less marked depression. Quantal content throughout these trains remained lower than in controls. The results indicate that IgG antibody from l.e.m.s. patients can induce a similar physiologic disorder in injected mice, and they support the view that this antibody interferes with evoked release of transmitter in l.e.m.s. by binding to nerve terminal determinants.
Adult↗
Preparation and characterisation of homogeneous neurotoxin type A from Clostridium botulinum. Its inhibitory action on neuronal release of acetylcholine in the absence and presence of beta-bungarotoxin.
1. Large-scale production and purification of complexes between Clostridium botulinum neurotoxin and haemagglutinin have been achieved. 2. Haemagglutinin-free neurotoxic protein of the complexes was purified to high specific neurotoxicity by affinity chromatography, on p-aminophenyl beta-D-thiogalactopyranoside coupled to Sepharose 4B, followed by chromatography on DEAE-Sephacel. 3. The resultant neurotoxin was homogeneous on isoelectric focussing (pI = 6.3) and on dodecylsulphate/polyacrylamide gel electrophoresis under non-reducing conditions when its Mr was 1.4 X 10(5); after reduction two polypeptides (Mr = 9.9 and 5.5 X 10(4) were present. 4. On double-immunodiffusion gels, using antiserum against neurotoxin-haemagglutinin complex, the neurotoxin showed a single, sharp precipitin line that was immunologically distinct from a relatively non-toxic protein (Mr = 1.3 X 10(5), which co-purifies with the neurotoxin but is removed by the ion-exchange chromatography step. 5. Application of the neurotoxin to animals in vitro or in vivo produced near complete and irreversible blockade of neurotransmission. Botulinisation of rat leg muscles reduced spontaneous transmitter release; the amplitude of miniature end-plate potentials was altered from the normal 'bell-shaped" to a skewed distribution. 6. In normal muscle, a large transient increase in frequency of the miniatures was produced by beta-bungarotoxin. In contrast, with botulinised muscle the latter induced a much smaller increase in the absolute frequency; in addition, the mean amplitude was increased somewhat but the distribution remained skewed. The results show botulinisation of muscle modifies the action of beta-bungarotoxin.
Acetylcholine↗
Food allergens and basophil histamine release in recurrent aphthous stomatitis.
The leukocytes from sixty patients with recurrent aphthous stomatitis were tested for histamine release in response to environmental and food antigens. Eighteen patients (30 percent of the population studied) were atopic, and this history of respiratory allergy was confirmed by an in vitro histamine release assay. The nonatopic patients with recurrent aphthous stomatitis had a significantly higher incidence of in vitro histamine release to foods than did control subjects. The leukocytes from twenty-three patients (38 percent) released histamine to food antigens. Patients eliminated foodstuffs in a double-blind trial to correlate the in vitro histamine release to the development of oral ulcers. Only 30 percent of the patients had a decreased incidence of ulcers after eliminating foods which had induced in vitro histamine release. On rechallenge in the double-blind trial, 30 percent of the foods which caused histamine release also correlated to increased incidence of oral lesions. In eight patients ingestion of certain foodstuffs was correlated to oral ulceration by food diaries and elimination-rechallenge in an open-trial basis. However, dietary manipulation did not completely eliminate the ulceration in any of the patients. The results suggest that food sensitivity may play a minor role in the development of recurrent aphthous stomatitis.
Adolescent↗
A double-blind trial of systemic zinc sulfate in recurrent aphthous stomatitis.
A double-blind crossover study of the effects of systemic zinc sulfate was carried out on twenty-five patients with recurrent aphthous stomatitis. No therapeutic effect was seen with the use of systemic zinc over a 3-month period. This study fails to confirm the beneficial effects of zinc seen in previously reported studies. Four patients had to discontinue the zinc therapy because of side effects. The empirical use of systemic zinc sulfate supplementation in the treatment of recurrent aphthous stomatitis is not recommended.
Adult↗
Lambert-Eaton myasthenic syndrome: electrophysiological evidence for a humoral factor.
Noncarcinomatous Lambert-Eaton myasthenic syndrome (LEMS) often associates with autoimmune disorders. A course of plasma exchange in both carcinomatous and noncarcinomatous LEMS induced clinical and significant electromyographic improvement which reached its peak 10 to 20 days after the last exchange. Prednisolone and azathioprine treatment was associated with striking clinical and electromyographic improvement in the 3 noncarcinomatous patients. The IgG fraction of LEMS plasma, and to a lesser extent plasma itself, injected daily intraperitoneally into mice induced similar electrophysiological changes to human LEMS, the reduction in the quantal content of the end-plate potential (epp) in diaphragm being highly significant. A train of stimuli at 40 Hz produced early facilitation or a less marked decline in epp amplitudes than occurred in mice injected with control IgG. The results indicate that the electrophysiological abnormalities in both forms of LEMS arise from an IgG autoantibody that binds to nerve terminal determinants which are concerned with the quantal release of transmitter.
Adult↗
Role of mucosal injury in initiating recurrent aphthous stomatitis.
The buccal mucosa of 30 patients with recurrent aphthous stomatitis and 15 healthy controls was injured by suture and penetration with a tenaculum and a hypodermic needle and each of the six puncture wounds produced monitored for up to seven days for the development of ulcers. Altogether 26 lesions were induced in 13 patients, whereas none occurred in the controls (p less than 0.001). Sutures caused most of the lesions (15), and those so induced had a mean maximum diameter of 2.3 mm and lasted for an average of four days. Ulcers induced mechanically were clinically indistinguishable from those usually seen in the patients, except that they were generally smaller and healed more quickly. These findings confirm that mechanically induced injury of the oral mucosa may cause ulceration in people susceptible to aphthous stomatitis. Such a procedure may therefore be helpful in identifying subsets of patients.
Adult↗
Autoimmune aetiology for myasthenic (Eaton-Lambert) syndrome.
The myasthenic (Eaton-Lambert) syndrome, associated with carcinoma of the bronchus in one patient and with immunological disorders in two others, improved after plasma exchange--observations supported by electromyographic evidence in two cases. Prednisolone and azathioprine treatment led to almost complete remission in one of the non-neoplastic cases and to improvement in the other. The IgG fraction of plasma from all three patients, injected daily (10 mg) into mice for 37-77 days, significantly reduced the initial compound muscle action potential and the quantal content of the end-plate potential measured in the diaphragm, when compared with control human IgG. These results indicate that an IgG autoantibody, binding to nerve terminal determinants, may be responsible for the disorder of neuromuscular transmission in the myasthenic syndrome, and that immunosuppressive drugs may be useful in treating the nonneoplastic form of the disease.
Adult↗
Gluten-sensitive recurrent aphthous stomatitis.
Twenty selected patients with recurrent aphthous stomatitis in whom celiac disease had been specifically excluded were placed on a gluten-free diet. Five patients (25%) showed a favorable response to gluten withdrawal and a positive gluten challenge. Jejunal morphology was normal in all patients indicating gluten sensitivity without enteropathy. Gluten withdrawal provides a further method of treating some patients with recurrent aphthous stomatitis.
Adolescent↗
Prolonged exposure to acetylcholine: noise analysis and channel inactivation in cat tenuissimus muscle.
1. Micro-electrodes were used to record membrane potential and associated noise at the end-plate region of cat tenuissimus muscle (37 degrees C), during applications of acetylcholine (ACh) in continuously flowing Krebs solution containing eserine and tetrodotoxin. 2. Densensitization was assessed from the frequency of channel opening calculated from the noise variance. 3. At higher concentrations of ACh (10-50 microM), desensitization occurred with an exponential fall to a plateau. 4. At low concentrations of ACh (1-2 microM) only slight desensitization occurred and at a much lower rate. Frequency of channel opening decreased at the rate of 0.045 +/- 0.024 min-1. Maximum frequency was (33 +/- 9) X 10(7)/sec while maximum depolarization was 20.5 +/- 1.4 mV (n = 11 cats). Depolarization was well maintained. 5. This slow rate of desensitization at low concentrations of ACh was confirmed in experiments where voltage clamped current, its associated noise, and miniature end-plate current amplitude were measured. 6. At low concentrations of ACh (1-2 microM) in the presence of eserine there was sustained block in neuromuscular transmission when twitch tension was measured. 8. It is concluded that the mechanism of neuromuscular block by ACh at around 1 microM concentration is by depolarization itself, not desensitization.
Acetylcholine↗