Characterization of the CNS effects of naftidrofuryl (Praxilène) by quantitative EEG and functional MRI: a study in healthy elderly subjects

In the present study, we investigated the effects of a single and a repeated (5 days) administration of naftidrofuryl, a serotonin 5-HT2 receptor inhibitor having neuroprotective properties, on functional brain physiology in male healthy elderly subjects, using quantitative electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Twelve subjects aged 60 +/- 3.8 years completed the quantitative EEG study, where the effects of 400 and 600 mg were assessed, and 12 other subjects (aged 56 +/- 4.7 years) completed the fMRI study, where the effect of 400 mg was assessed on the brain activation induced by the continuous performance test (CPT). Naftidrofuryl induced a transient reduction in alpha activity followed by a specific synchronisation of the 9.5- to 11-Hz EEG activity most pronounced after repeated administration. Such regimen also increased the CPT-induced brain activation visualized by way of fMRI. The results of the present study can be interpreted at the functional level that naftidrofuryl induced an improved level of vigilance or an increased capacity of alertness in healthy elderly subjects.

Monoclonal anti-conjugated acetylcholine antibody and immunohistochemical applications in rat nervous system

Acetylcholine (ACh) conjugates were injected into AKR and DBA mice over a period of 10 weeks. The polyclonal antisera were tested at various immunization times for affinity and specificity using an enzyme-linked immunosorbent assay (ELISA). The most immunoreactive compound was found to be choline-glutaryl-bovine serum albumin (or conjugated ACh). The AKR and DBA mice yielding the highest apparent affinity were killed, and the spleen cells were fused with X63 or SP2/O/Ag mouse myeloma cells. Supernatants of confluent cultures were tested for the presence of anti-conjugated ACh antibodies using the same ELISA method. The best results were obtained with the hybridomas from AKR spleen cells and X63 mouse myeloma cells. Monoclonal antibody affinity and specificity were then evaluated by a radioimmunological procedure using iodinated monoclonal anti-conjugated ACh antibody. From competition experiments, the most immunoreactive compound was choline-glutaryl-protein. The other related compounds were recognized either poorly or not at all. The high affinity and specificity of our monoclonal antibody enabled us to visualize ACh molecules on fixed rat brain sections. ACh was fixed with a mixture of nitrobenzyl alcohol and glutaraldehyde. Many ACh-immunoreactive cell bodies and fibers were seen on sections from the basal forebrain and spinal cord. Preadsorption and other immunohistochemical tests demonstrated that the ACh staining was highly specific.

[Anti-acetylcholine and anti-receptor antibodies in myasthenia]

The presence of anti-acetylcholine antibodies has been demonstrated in 24 patients with myasthenia gravis. Their titer was moderately but significantly higher than in controls. There was no significant correlation between the titer of these anti-acetylcholine antibodies and the clinical severity of the disease or the titer of anti-receptor antibodies in the same patients. Several populations of antibodies are present in myasthenia gravis according to an idiotype-anti-idiotype process, reflecting the complexity of immune reactions.

Immunocytochemical localization of acetylcholine receptors in locust brain using auto-anti-idiotypic acetylcholine antibodies

Auto-anti-idiotypic antibodies have been detected in antisera of rabbits immunized with an acetylcholine (ACh) conjugate. These antibodies were found to bind to ACh receptor (ACh-R) purified from different species membranes. They competed with the ACh-R antagonist alpha-bungarotoxin and some agonists such as ACh conjugate and ACh itself. They did not recognize acetylcholinesterase. Their characterization 'in vitro' suggested their employment as an immunohistological marker for ACh-R. In the locust brain, specific immunoreactivity was found in neuropils of the protocerebrum, the optic lobes, the deutocerebrum and the tritocerebrum.

Anti-acetylcholine antibodies and the pathogenesis of myasthenia gravis

Using an ELISA system, antibodies recognizing conjugated acetylcholine (ACh) were detected in sera of patients suffering from myasthenia gravis. The mean antibody level was three times higher in sera from myasthenic than from control patients. No correlation was found between anti-ACh antibody levels and anti-ACh receptor (AChR) titer. Also, the anti-ACh antibody titers were independent of sex and age of patients. Competition experiments demonstrated that the most immunoreactive compounds were choline-glutaryl-bovine serum albumin (BSA) and choline-succinyl-BSA. Antibodies present in the sera of myasthenic patients recognized an antigenic determinant mimicking conjugated ACh. The antibody affinity and specificity were sufficiently high for the detection of ACh in locust brain.

Immunological similarities between an experimental autoimmune myasthenia gravis model and human myasthenia gravis

The induction of experimental autoimmune myasthenia gravis (EAMG) in rabbits after immunization with an acetylcholine (ACh) conjugate was found to possess immunological similarities with human myasthenia gravis. Anti-ACh antibodies, present in human sera, recognized the antigenic determinant, glutarylcholine, used to raise anti-ACh antibodies in rabbits. Identification of anti-anti-ACh antibodies in MG patients enabled us to test for recognition of the anti-ACh antibodies present in rabbit sera. The reverse, the recognition of rabbit auto-anti-anti-ACh antibodies by human anti-ACh antibodies was also tested and found to be specific.

Detection of anti-acetylcholine antibodies in myasthenic patients

Antibodies, directed against an acetylcholine (ACh) conjugate, were found in the sera of myasthenic patients by using a modified enzyme-linked immunosorbent assay method. Binding of sera from control patients to the conjugate was extremely low. From competition experiments, done with compounds close to ACh, a good antibody specificity for the ACh conjugate was demonstrated in the sera of myasthenic patients. Laboratory tests will be done to help a more precise diagnostic of the disease to be given. These results may also be of value in further understanding of the process of the disease itself.

A new model of experimental auto-immune myasthenia gravis

Experimental auto-immune myasthenia gravis (EAMG) was observed in rabbits during the time course of immunization with an acetylcholine (ACh) conjugate: choline-glutaryl-protein. This synthesized antigenic determinant mimics the molecular structure of ACh. The presence of both anti-ACh and auto-anti-idiotypic antibodies was demonstrated. These latter antibodies recognized the ACh receptor, and could have been the triggering agents in this auto-immune condition. Clinical and electromyographic investigations confirmed the myasthenic symptomatology observed after immunization with the ACh conjugate.

Immunocytochemical detection of acetylcholine in the rat central nervous system

A specific antibody to acetylcholine was raised and used as a marker for cholinergic neurons in the rat central nervous system. The acetylcholine conjugate was obtained by a two-step immunogen synthesis procedure. An enzyme-linked immunosorbent assay was used to test the specificity and affinity of the antibody in vitro; the results indicated high affinity. A chemical perfusion mixture of allyl alcohol and glutaraldehyde was used to fix the acetylcholine in the nervous tissue. Peroxidase-antiperoxidase immunocytochemistry showed many acetylcholine-immunoreactive cells and fibers in sections from the medial septum region.