The aim of this research is to make a detailed analysis of neuromuscular transmission in human diseases affecting the neuromuscular junction. The proposed studies are concerned particularly with aspects of neuromuscular transmission in five newly recognized congenital myasthenic syndromes and in the myasthenic syndrome sometimes associated with small cell bronchial carcinoma (Lambert-Eaton syndrome, LES). Familial, congenital myasthenia gravis in dogs is being studied as a model for one form of congenital myasthenic syndrome in man. Electrophysiologic methods will be used including electromyographic techniques to study the patient, and intracellular microelectrode techniques to record the events of neuromuscular transmission in single muscle fibers of biopsied muscles. The purpose is to determine in detail which step in the chain of events in neuromuscular transmission is abnormal and to identify causative factors. A continuing search is being made for a circulating factor from small cell carcinomas as a cause of the defect of neuromuscular transmission in LES. The possibility that the defect in LES associated with bronchial carcinoma may result from an immune response to tumor antigens is being tested. In view of the high probability that LES with and without tumor is an organ-specific autoimmune disease, studies are also being directed to identifying the relevant antigen of cholinergic nerve terminals. The effects on neuromuscular tranmission of a compound 3,4-diaminopyridine will be studied; this compound has been found in limited tests by European investigators to be more effective and less toxic than currently available drugs for the treatment of the specific type of defect of neuromuscular transmission in LES. Investigations of the effects on rat neuromuscular transmission of monoclonal antibodies reactive with defined sites of the human muscle acetylcholine receptor (AChR) are aimed at determining in more detail the mechanism of action of antibodies in acquired MG. Studies of neuromuscular transmission in defined strains of mice immunized with AChR will give information about the genetic control of susceptibility to acquired MG. The long term goal is to improve criteria for the diagnosis of different defects of neuromuscular transmission in man and to provide information required for devising appropriate treatment.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS023691-03
Application #
3407466
Study Section
Neurology B Subcommittee 1 (NEUB)
Project Start
1985-09-01
Project End
1989-11-30
Budget Start
1986-12-01
Budget End
1987-12-14
Support Year
3
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Type
Schools of Medicine
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Yoshikawa, H; Lambert, E H; Walser-Kuntz, D R et al. (1997) A 17-Mer self-peptide of acetylcholine receptor binds to B cell MHC class II, activates helper T cells, and stimulates autoantibody production and electrophysiologic signs of myasthenia gravis. J Immunol 159:1570-7
Sano, M; Lambert, E H; McCormick, D J et al. (1992) Muscle acetylcholine receptors complexed with autologous IgG reflect seropositivity but not necessarily in vivo binding. Neurology 42:218-22
Lennon, V A; Lambert, E H; Leiby, K R et al. (1991) Recombinant human acetylcholine receptor alpha-subunit induces chronic experimental autoimmune myasthenia gravis. J Immunol 146:2245-8
Lennon, V A; Lambert, E H (1989) Autoantibodies bind solubilized calcium channel-omega-conotoxin complexes from small cell lung carcinoma: a diagnostic aid for Lambert-Eaton myasthenic syndrome. Mayo Clin Proc 64:1498-504
De Aizpurua, H J; Griesmann, G E; Lambert, E H et al. (1988) Voltage-dependent Ca2+ channels in small cell carcinomas are blocked by autoantibodies from patients with Lambert-Eaton myasthenic syndrome. Ann N Y Acad Sci 540:369-71
De Aizpurua, H J; Lambert, E H; Griesmann, G E et al. (1988) Antagonism of voltage-gated calcium channels in small cell carcinomas of patients with and without Lambert-Eaton myasthenic syndrome by autoantibodies omega-conotoxin and adenosine. Cancer Res 48:4719-24
Lambert, E H; Lennon, V A (1988) Selected IgG rapidly induces Lambert-Eaton myasthenic syndrome in mice: complement independence and EMG abnormalities. Muscle Nerve 11:1133-45
Lennon, V A; Huang, Z X; McCormick, D J et al. (1988) Synthetic peptide of human acetylcholine receptor alpha-subunit sequence 125-147 (methionine 144), a more potent autoantigen than its norleucine 144 analog. Ann N Y Acad Sci 540:516-9
McCormick, D J; Griesmann, G E; Huang, Z X et al. (1987) Myasthenogenicity of human acetylcholine receptor synthetic alpha-subunit peptide 125-147 does not require intramolecular disulfide cyclization. J Immunol 139:2615-9
Lennon, V A; Griesmann, G A; McCormick, D J et al. (1987) Definition of myasthenogenic sites of the human acetylcholine receptor using synthetic peptides. Ann N Y Acad Sci 505:439-50