Zoltan Rakonczay

Bio: Zoltan Rakonczay is an academic researcher from Mayo Clinic. The author has contributed to research in topics: Acetylcholinesterase & Cholinergic neuron. The author has an hindex of 7, co-authored 10 publications receiving 210 citations.

Monoclonal Antibodies to Rat Brain Acetylcholinesterase: Comparative Affinity for Soluble and Membrane‐Associated Enzyme and for Enzyme from Different Vertebrate Species

Abstract: Seven unique monoclonal antibodies were generated to rat brain acetylcholinesterase. Upon density gradient ultracentrifugation, immunoglobulin complexes with the monomenc enzyme appeared as single peaks of acetylcholinesterase activity with a sedimentation coefficient approximately 3S greater than that of the free enzyme. This behavior is consistent with the assumption of one binding site per enzyme molecule. Apparent dissociation constants of these antibodies for rat brain acetylcholinesterase calculated on the basis of this assumption ranged from about 10 nA/ to more than 1,000 nM. Some of the antibodies were less able to bind the membrane-associated enzyme that required detergent for solubilization than the naturally soluble acetylcholinesterase of detergent-free brain extracts. Species cross-reactivity was investigated with crude brain extracts from mammals (human, mouse, rabbit, guinea pig, cow, and cat) and from other vertebrates (chicken, frog, and electric eel). Three antibodies bound rat acetylcholinesterase exclusively; one had nearly the same affinity for all mammalian acetylcholinesterases investigated; the remaining three showed irregular binding patterns. None of the antibodies recognized frog and electric eel enzyme. Pooled antibody was found to be suitable for specific immunofluorescence staining of large neurons in the ventral horn of the rat spinal cord and smaller cells in the caudate nucleus. Other potential applications of these antibodies are discussed.

Biochemistry and Pathophysiology of the Molecular Forms of Cholinesterases

Abstract: Acetylcholinesterase (acetylcholine acetylhydrolase, AChE: EC 3.1.1.7) and butyrylcholinesterase (acylcholine acylhydrolase, BuChE: EC 3.1.1.8) both possess the capacity to hydrolyze choline esters, although the latter accepts a much wider variety of substrates. These two enzymes are found in a large number of excitable and nonexcitable tissues in most species, including humans (for review see Silver, 1974). The two types of ChE (generic abbreviation for any Cholinesterase) are readily distinguished not only by their substrate specificity but also by their response to selective inhibitors.

Immunology and molecular biology of the cholinesterases: current results and prospects.

Abstract: Publisher Summary This chapter discusses the application of modern immunology and molecular biology to the study of cholinesterases The combined approaches of immunology and molecular biology may resolve many problems concerning the structure, function, localization, and dynamics of these enzymes The homologies between butyrylcholine esterase (BuChE) and acetylcholinesteras (AChE) and the precursor-product relations among the molecular forms of these enzymes are discussed Rapid and convenient purification procedures, perhaps starting with genetically engineered organisms, make it easy to obtain enzyme preparations suitable for large-scale structural studies It will become feasible to observe particular enzyme forms specifically and directly or even to induce their synthesis in certain types of cells, aiding attempts to clarify their physiological significance Sensitive immunoassays are available for experiments in which measurements of enzyme activity are an unreliable guide It is possible to track enzyme molecules as they make their way through the cell, to gain increased understanding of the regulation of their synthesis, assembly into complex forms, delivery to destinations, and metabolism

Monoclonal antibodies to human brain acetylcholinesterase: properties and applications

Abstract: 1. Acetylcholinesterase (AChE) was purified 20,000-fold in a 43% yield from 90 g of human cerebellum by combined immunoaffinity and ligand affinity chromatography. The purified enzyme migrated as a 68,000-dalton band during polyacrylamide gel electrophoresis under denaturing and reducing conditions. 2. Balb/c mice were immunized with multiple 10-micrograms injections of this material in order to raise monoclonal antibodies to human brain AChE. Three such antibodies were obtained and characterized. 3. Each antibody cross-reacted distinctively with AChEs from other mammals. No antibody recognized human plasma butyrylcholinesterase but all reacted with AChE from human red blood cells. 4. Antibodies HR5 and HR3 performed well in two-site immunoassays for AChE. With these assays we compared autopsy samples of cortical region A9 from six controls (nonneurological cases) and five patients with Alzheimer's disease. The latter showed a highly significant 60% deficit of AChE protein. 5. The present antibodies will permit additional immunochemical studies of cholinergic systems in dementia.

Albumin Fusion Proteins

Abstract: The present invention encompasses albumin fusion proteins. Nucleic acid molecules encoding the albumin fusion proteins of the invention are also encompassed by the invention, as are vectors containing these nucleic acids, host cells transformed with these nucleic acids vectors, and methods of making the albumin fusion proteins of the invention and using these nucleic acids, vectors, and/or host cells. Additionally the present invention encompasses pharmaceutical compositions comprising albumin fusion proteins and methods of treating, preventing, or ameliorating diseases, disorders or conditions using albumin fusion proteins of the invention.

Complete and selective cholinergic denervation of rat neocortex and hippocampus but not amygdala by an immunotoxin against the p75 NGF receptor

Abstract: The immunotoxin 192 IgG-saporin, produced by coupling the ribosome-inactivating protein saporin to the monoclonal 192 IgG antibody against the low-affinity p75 NGF receptor (NGFr), was injected into the cerebral ventricle, septal area, and substantia innominata of adult rats. Injections into the cerebral ventricle induced a complete loss of NGFr-positive basal forebrain neurons and their axons. Extensive loss of cholinergic neurons was found in the septum, diagonal band, and magnocellular preoptic nucleus but not in the nucleus basalis-substantia innominata complex, where many cholinergic, presumably NGFr-negative, neurons remained intact. Cholinergic fibers were completely lost in the neocortex and hippocampus, showed some preservation in allocortical areas, and showed only minor loss in the amygdala. The NGFr-positive cholinergic basal forebrain neurons progressively degenerated during the first 5 d and did not recover after 180 d. The effect of intraventricular 192 IgG-saporin injections on NGFr-positive basal forebrain neurons could be blocked by simultaneous intraventricular injection of colchicine. Intraparenchymal injections into the septal area or substantia innominata damaged cholinergic neurons mainly around the injection sites and reduced their respective cortical and hippocampal projections. Noncholinergic septal neurons containing parvalbumin and noncholinergic neurons containing calbindin-D28k or NADPHd, which were adjacent to cholinergic nucleus basalis-substantia innominata neurons, were not affected by 192 IgG-saporin. The ChAT immunoreactivity in cortical interneurons, habenula, and brainstem was unchanged. Dopaminergic and noradrenergic cortical afferents remained intact. 192 IgG-saporin damaged two neuronal groups outside the basal forebrain that express the p75 NGF receptor: NGFr-positive cerebellar Purkinje cells after intraventricular injection and cholinergic striatal interneurons after injections into the substantia innominata. These results indicate that the immunotoxin 192 IgG-saporin induces a complete and selective lesion of NGFr-positive cholinergic basal forebrain neurons projecting to hippocampus and neocortex.