Neuropathophysiological potential of Guillain-Barré syndrome anti-ganglioside-complex antibodies at mouse motor nerve terminals

Objectives:  Anti-ganglioside antibodies are present in approximately half of Guillain–Barré syndrome (GBS) patients. Recently, it has been shown that a considerable proportion of these patients has serum antibodies against antigenic epitopes formed by a complex of two different gangliosides. However, direct experimental evidence for neuropathogenicity of this special category of antibodies is currently lacking. Here, we explored a series of GBS and GBS-variant sera with anti-ganglioside-complex antibodies for their ability to induce complement-dependent deleterious effects at the living neuronal membrane. Methods:  The neuropathophysiological potential of 31 GBS sera containing either anti-GM1/GD1a- or anti-GM1/GQ1b-ganglioside-complex antibodies was studied at motor nerve terminal presynaptic membranes in the mouse phrenic nerve/diaphragm muscle ex vivo experimental model. With electrophysiological measurements and confocal fluorescence microscopy, we assessed and quantified the damaging effect on neuronal membranes by anti-ganglioside-complex antibodies. Results:  We show that anti-GM1/GD1a- and anti-GM1/GQ1b-ganglioside-complex positive sera can induce complement-mediated functional and morphological injury at mouse motor nerve terminals ex vivo. Of the 31 investigated anti-ganglioside-complex patient sera, 17 sera induced increases in miniature end-plate potential frequency in this experimental model, mostly associated with muscle fibre twitches. Variability in potency was observed, with the anti-GM1/GD1a-complex sera inducing the most outspoken effects.<b></b> Conclusions:  The present study shows the presence of ganglioside-complexes as available antigens in living neuronal membranes and supplies proof-of-principle that anti-ganglioside-complex antibodies in sera from GBS patients can induce complement-mediated damage. This strongly supports the hypothesis that autoimmune targeting of ganglioside-complexes is of pathogenic relevance in a proportion of GBS patients

Determination of Dry Rubber Content of Hevea Latex by Microwave Technique

The measurement of the dry rubber content of the fresh hevea latex by microwave technique is described. In this technique the attenuation of microwave by latex is measured at 10.7 GHz and is then calibrated against the standard laboratory method. Compared with the standard method this instrument is able to reduce the measuring time 8 - 16 hours to three minutes. The correlation coefficient between the DRC determined using this instrument and the standard laboratory method is 0.998 and the standard deviation is less than 0.7%. The reproducibility is at a level of 0.8% unit DRC