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L Elfman

Publications and source records attributed to L Elfman.

29 records · Page 2Linked to original sources
PubMed1986

Rat and mouse monoclonal antibodies to human myelin basic protein.

BALB/c mice and Lewis rats were immunized with human myelin basic protein and its N- and C-terminal fragments. Mouse X mouse fusions produced seven monoclonal antibodies, all of the IgG class and directed against the N-terminal fragment. Five of the antibodies seemed to be against the same epitope, between amino acid residues 92 and 118. One antibody bound between residues 45 and 91, and the remaining antibody reacted with both peptides 1-44 and 45-91. Three monoclonal antibodies, all of the IgM class, were obtained by rat X rat hybridization. Two monoclonal antibodies, raised against whole myelin basic protein and the C-terminal fragment, respectively, each bound to peptide 118-178. The remaining antibody, raised against the N-terminal fragment, bound to peptide 45-91. These monoclonal antibodies are of interest for use in clinical radioimmunoassays and for immunohistochemical investigation of the structural relationships of the myelin sheath.

Animals↗
PubMed1984

Immunisation with Torpedo acetylcholine receptor.

Acetylcholine mediates the transfer of information between neurons in the electric organ of, for example, Torpedo as well as in vertebrate skeletal muscle. The nicotinic acetylcholine receptor complex translates the binding of acetylcholine into ion permeability changes. This leads to an action potential in the muscle fibre. The nicotinic acetylcholine receptor protein has been purified from Torpedo by use of affinity chromatography. The receptor is an intrinsic membrane glycoprotein composed of five polypeptide chains. When various animals are immunised with the receptor they demonstrate clinical signs of severe muscle weakness coincident with high antibody titres in their sera. The symptoms resemble those found in the autoimmune neuromuscular disease myasthenia gravis in humans. This animal model has constituted a unique model for studying autoimmune diseases. This paper reviews some of the work using Torpedo acetylcholine receptor in order to increase the understanding of the motor nervous system function and myasthenia gravis. It is now known that the nicotinic acetylcholine receptor protein is the antigen involved in myasthenia gravis. The mechanism of immune damage involves a direct block of the receptor function. This depends on the presence of antibodies which crosslink the postsynaptic receptors leading to their degradation. The questions to be answered in the future are; (a) what initiates or triggers the autoimmune response, (b) how do the antibodies cause the symptoms--is there a steric hindrance of the interaction of acetylcholine and the receptor, (c) why is there not a strict relationship between antibody titre and severity of symptoms, and (d) why are some muscles affected and other spared? With help of the experimental model, answers to these questions may result in improved strategies for the treatment of the autoimmune disease myasthenia gravis.

Adjuvants, Immunologic↗
PubMed1984

Adenosine analogues stimulate cyclic AMP-accumulation in cultured neuroblastoma and glioma cells.

The effect of three stable adenosine analogues, L-phenylisopropyl-adenosine (L-PIA), 2-chloroadenosine, and adenosine 5'-ethylcarboxamide (NECA), on cyclic AMP accumulation was studied in five different cell lines derived from the nervous system. In N18-neuroblastoma cells, with cholinergic properties, all three analogues caused an increased accumulation of cyclic AMP with the following relative order of potency: NECA greater than 2-chloroadenosine greater than L-PIA. The half maximal effect of NECA was obtained at close to 10(-8) M concentration. In the two other neuroblastoma cell lines, 41A3 with cholinergic and NIE115 with adrenergic properties, the two analogues NECA and PIA had similar effects. In glioma C6 and 138 MG cells NECA was also found to be more potent that PIA in elevating cyclic AMP levels. However, the absolute potency of NECA in these cell lines was almost 100 times lower. Phosphodiesterase (PDE) activity in crude homogenates of the five cell lines showed essentially similar Km and Vmax, with the exception that the three neuroblastoma cell lines showed biphasic, the glial cell lines monophasic Eadie-Hofstee plots. Theophylline was equally potent as an inhibitor of PDE in all cell lines, but the non-xanthine, inhibitor rolipram, was more potent against neuroblastoma than glial cell PDE. These results indicate that all five cell lines have adenosine receptors of the A2-subtype. However, the apparent affinity of the adenosine analogues to these receptors was markedly different between the neuroblastoma and glial cell lines. The absolute potency of adenosine analogues may be a poor criterion to classify adenosine receptors, into A1 and A2 subtypes, especially when intact cells are used.

2-Chloroadenosine↗
PubMed1983

Morphological changes observed in rats immunized with the Torpedo acetylcholine receptor alpha-chain.

Lewis rats were immunized with nicotinic acetylcholine receptor (nAChR) polypeptides purified from the electric tissue of Torpedo marmorata. Animals immunized with the acetylcholine binding, 41.500 daltons, polypeptide showed comparable fragmentation of the postsynaptic membrane and indications of rearrangement of the adjacent muscle fiber as earlier found in rabbits and rats immunized with the nAChR complex. Thus, these results demonstrate that the alpha-polypeptide chain carries all determinants necessary for onset of Experimental Autoimmune Myasthenia Gravis (EAMG).

Animals↗
PubMed1982

Fractionation of protein components of plasma membranes from the electric organ of Torpedo marmorata.

A procedure has been developed for the separation of intrinsic proteins of plasma membranes from the electric organ of Torpedo marmorata. (Na+ + K+)-ATPase, nicotinic acetylcholine receptor and acetylcholinesterase remained active after solubilization with the nonionic detergent dodecyl octaethylene glycol monoether (C12E8). These components could be separated by ion exchange chromatography on DEAE-Sephadex A-25. Fractions enriched in ouabain-sensitive K+-phosphatase or (Na+ + K+)-ATPase activity showed two bands in sodium dodecyl sulphate polyacrylamide gel electrophoresis corresponding to the alpha- and beta-subunits. The (Na+ + K+)-ATPase was shown to have immunological determinants in common with a 93 kDa polypeptide which copurified with the nicotinic acetylcholine receptor, also after solubilization in Triton X-100 and chromatography on Naja naja siamensis alpha-toxin-Sepharose columns. The data suggest that the alpha-subunit of (Na+ + K+)-ATPase associates with the acetylcholine receptor in the membranes of the electric organ.

Acetylcholinesterase↗
PubMed1978

Binding of thiamine to nicotinic acetylcholine receptor in torpedo marmorata and the frog end plate.

Thiamine was found to bind to the isolated nicotinic receptor (nAChR) from Torpedo marmorata (KD = 3--5 X 10(-5) M). The binding was reversible and inhibited by alpha-neurotoxin from Naja naja siamensis. Acetylcholine binding was not inhibited by thiamine. When thiamine (5 X 10(-4) M) was applied to frog sartorius muscles a decrease of miniature end plate potential amplitudes was seen. This effect was readily reversible after the perfusion fluid of the muscle was changed to normal Ringer solution. Thus both biological and electrophysiological studies indicated a binding of thiamine to the nAChR.

Acetylcholine↗
PubMed1978

Immunological and binding studies on chloroform--methanol extracts from electroplax of Torpedo marmorata and from rat brain cortex. Comparison of the material solubilized by organic solvents with the receptor proteins solubilized by detergents.

We have investigated a chloroform--methanol extracted material from electric organ of Torpedo marmorata with respect to binding of [3H]-acetyl-alpha-neurotoxin and [3H]-acetylcholine. No binding was observed which is in contrast to observations with detergent extracted receptor. Further, no crossreactivity could be demonstrated between the chloroform--methanol extracted proteolipid and antibodies against the detergent extracted receptor. Labelling in the membrane with [3H]-acetyl-alpha-neurotoxin before extraction with chloroform--methanol gave a very low yield of extracted labelled compound. The protein yield is about 0.3% of the total in the homogenate and only 0.04% of the specifically bound neurotoxin. Using the alkylating affinity label [3H]-N-propylbenzilylcholine mustard (1) and also [3H]-atropine, which both bind, at low concentrations, specifically to the muscarinic acetylcholine receptor, binding was studied to the chloroform--methanol extracted proteolipid from rat brain cortex. No specific binding could, however, be demonstrated. Prelabelling in the membrane with 1 and subsequent extraction with chloroform--methanol gave a protein yield of about 1% and an extraction of 26% of the specifically bound label.

Acetylcholine↗
PubMedDate not supplied

Experimental autoimmune myasthenia gravis in the rat: a preliminary report.

In chronic experimental myasthenia gravis (EAMG) in rat, the decrement of electrical and mechanical responses evoked by maximal repetitive (3-167/sec) stimuli to the nerve was greater in the slow-twitch soleus (SOL) than in the fast-twitch extensor digitorum longus (EDL) muscle. Excitation-contraction coupling was impaired in moderate to severe EAMG, as evidenced by a diminished staircase phenomenon and by diminished posttetanic potentiation (PTP) of twitch tension in two EDLs. The only morphologic abnormality observed was an increase in length of the endplates in the EDLs of those animals that had had an acute phase of EAMG. The latter had more than a 90% reduction in the amplitude of the action potential and in the twitch tension of the EDL when stimuli were applied to the nerve. Stimuli applied directly to the muscle evoked a tetanic tension that was one-third of normal. The staircase and PTP were normal. Necrosis occurred in the endplate and in the adjacent segment of muscle fiber; outside the endplate region, the muscle fiber was normal.

Animals↗
PubMedDate not supplied

Different profiles in specific IgE to rBet v 1 and rBet v 2 in patients allergic to birch pollen from six countries.

There are differences in IgE reactivity to rBet v 1 and rBet v 2 among allergic patients from the six countries studied. The complexity of the reactivity profile tends to be greater in individuals from the central/southern parts of Europe compared to Sweden and Finland. There is a good agreement between in vitro diagnosis with Pharmacia CAP System and Skin prick testing when using the same reagents, rBet v 1 and rBet v 2.

Allergens↗