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Biomedical subjects

S Fuchs

Publications and source records attributed to S Fuchs.

At least 127 records · Page 7Linked to original sources
PubMed1979

Immunological cross-reactivity between electric-eel acetylcholinesterase and rat-tail-tendon collagen.

Immunological cross-reactivity between acetylcholinesterase from the electric organ of the electric eel and rat tail tendon collagen was examined both on the cellular and humoral levels. 1. Guinea pigs immunized with rat tail tendon collagen displayed a strong delayed-type skin reaction when tested with the elongated acetylcholinesterase preparation (i.e. 14-S + 18-S molecular forms). However, when the glubular 11-S enzyme was tested, almost no cross-reactivity was obtained. Similarly, guinea pigs immunized with 14-S + 18-S preparation exhibited skin sensitization to rat tail tendon collagen. 2. Using a radioimmunoassay, it was observed that 125I-labeled 14-S + 18-S acetylcholinesterase binds efficiently to rabbit antiserum elicited against rat tail tendon collagen, whereas 125I-labeled 11-S enzyme does not bind at all to this antiserum. Similar results were obtained by passive hemagglutination assay. The experiments suggest that 14-S + 18-S acetylcholinesterase, but not 11-S enzyme, which is devoid of the tail structure, has antigenic determinants in common with collagen from rat tail tendon.

Acetylcholinesterase↗
PubMed1978

Competitive inhibition of benzodiazepine binding by fractions from porcine brain.

Fractions of porcine cerebral cortex extract separated by molecular weight on a Sephadex G-75 column were tested for their activities and potencies to inhibit [3H]benzodiazepine binding to rat brain homogenates. The fractions spanned molecular weights from 500 to 100,000. A potent inhibitor (benzodiazepine-competitive factor I, BCF-I) was discovered in the fraction containing substances with molecular weights from 40,000 to 70,000. Equilibrium binding studies indicated that BCF-I was a competitive inhibitor, making it a candidate as a benzodiazepine endogenous factor or profactor. BCF-I was heat stable, but trypsin digestion destroyed its activity. Another inhibitory fraction (BCF-II) was 1/5th as active as BCF-I and contained substances with molecular weights from 1000 to 2000.

Animals↗
PubMed1978

Localization of acetylcholine receptor in excitable membrane from the electric organ of Torpedo: Evidence for exposure of receptor antigenic sites on both sides of the membrane.

Nicotinic acetylcholine receptor was localized in a receptor-rich membrane preparation from the electric organ of Torpedo californica by applying an immunoferritin technique. The membrane preparation was incubated with (Fab')2 fragments derived from specific rabbit antibodies against the purified acetylcholine receptor and subsequently with ferritin-conjugated goat antiserum to rabbit immunoglobulin. More than 50% of the vesicles were found to be labeled with ferritin while the rest remained unlabeled. Ferritin labeling on both sides of the membrane was evident in open membrane vesicles, whereas in closed vescles the labeling was confined to the outer surface due to the inability of the tracer to penetrate the membrane. These data suggest that antigenic sites of the receptor molecule are exposed on both sides of the excitable membrane, and that acetylcholine receptor may be a transmembrane protein.

Animals↗
PubMed1978

Specific immunosuppression of experimental autoimmune myasthenia gravis by denatured acetylcholine receptor.

Specific immunosuppression of experimental autoimmune myasthenia gravis (EAMG) was achieved by the use of a denatured preparation of the acetylcholine receptor (AcChoR) that did not in itself induce the disease. Torpedo californica AcChoR was irreversibly denatured by complete reduction and carboxymethylation in 6 M guanidine hydrochloride. Rabbits immunized with reduced carboxymethylated receptor (RCM-AcChoR) produced antibodies that reacted with both RCM-AcChoR and intact AcChoR. The specificity of anti-RCM-AcChoR antibodies is different from that of anti-AcChoR antibodies because the former are directed to only part of the antigenic determinants present in the intact receptor. RCM-AcChoR, which by itself is completely nonmyasthenic, was shown to be capable of both preventing the onset of EAMG and of reversing the clinical symptoms in myasthenic rabbits. In all cases the therapeutic effect of RCM-AcChoR administration on EAMG was accompanied by a change in the immunological specificity of the antibodies. The crossreactivity between AcChoR and RCM-AcChoR and the nonpathogenicity of RCM-AcChoR appear to be crucial in governing the specific immunosuppressive effects of RCM-AcChoR on EAMG.

Acetylcholine↗
PubMed1977

Cytophilic antibodies in experimental autoimmune myasthenia gravis.

Macrophage-cytophilic antibodies, with acetylcholine receptor specificity, are present in rabbits with experimental autoimmune myasthenia gravis (EAMG). Such antibodies may have a significant role in the immunologic mechanism involved in the pathogenesis of myasthenia gravis. The induction of EAMG in rabbits was performed by injection of purified AChR from the electric organ of Torpedo californica. Both the binding of AChR specific cytophilic antibodies to normal macrophages and the presence of such antibodies bound in vivo to macrophages of sick animals were demonstrated in vitro. The amount of cytophilic antibodies was determined by measuring cell-associated radioactivity after the addition of 125I-AChR. Cytophilic antibodies capable of binding to normal alveolar macrophages were detected in all animals 14 days after immunization, and were maintained through the severe stages of the disease. In addition, cytophilic anti-AChR antibodies were shown to be bound in vivo to alveolar macrophages drawn from severely sick rabbits, as was measured by a direct 125I-AChR binding to such macrophages. The role of cytophilic antibodies and in particular of macrophage-associated cytophilic antibodies in the pathogenesis of autoimmune diseases is not clear yet. The availability of AChR specific cytophilic antibodies can now be utilized for studying their role in the immunopathogenesis of EAMG.

Acetylcholine↗
PubMed1976

The effect of antisynaptosomal plasma membrane antibodies on memory.

Antisynaptosomal plasma membrane antibodies were introduced through an infusion cannula into rat brain and their effects on behaviour were tested. Four different learning paradigms were used, two appetitively and two aversively motivated, to show impairment in memory retrieval. No effects were found on aquisition, motor activity, or motivation.

Animals↗