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Article
March 1995

Immunosuppressive Treatment of Motor Neuron Syndromes-Reply

Author Affiliations

San Antonio, Tex
Columbus, Ohio
San Antonio
Columbus
San Antonio
Department of Neurology The Ohio State University 1654 Upham Dr Columbus, OH 43210

Arch Neurol. 1995;52(3):230-231. doi:10.1001/archneur.1995.00540270016005
Abstract

In reply  Pestronk criticized our article1 in two areas. First, he comments that inaccurate statements were made regarding measurements of anti-GM1 ganglioside antibodies in his laboratory. He insists that his methods "correspond closely to the reciprocal of true dilutions," despite the fact that a close inspection reveals that his assay is based on a method of extrapolation. In his assay, serum samples are titered to levels that provide optical densities in a linear range. From the linear range, the expected (not measured) optical density of a 1:100 dilution of the serum is calculated. This value is then multiplied by 1000 and the activity is expressed in units. In the method we1 and others2 employ to measure GM1 antibodies, the results represent the maximum dilution at which reactivity to GM1 is maintained at a level of 3 SDs above normal.A less important point relates

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