The effect of light on the Bray-Liebhafsky oscillatory reaction was studied at 55°C. It was found that both the induction time and period decreased with the increasing light intensity, and at a critical value of intensity, dependent on the initial concentration of the reactants, oscillation disappeared. The reaction scheme proposed by Schmitz was extended with a direct reaction of I 2 with H 2 O 2 . By taking into account the latter reaction, the oscillations were numerically calculated and good agreements with the experimental data were found.

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Multifocal motor neuropathy (MMN) is a rare, immune-mediated illness attacking ex­clusively motor nerves. It is known that oxidative stress is present in peripheral neuropathies, but it has not been investigated MMN. We measured in our prospective study the L-arginine, symmetric and asymmetric dimethylarginine (SDMA, ADMA) serum concentrations of 10 patients and 10 controls before and after intravenous immunoglobulin treatment (IVIG), as markers of the L-arginine/NO pathway involved in chronic inflammation and oxidative stress. The functions of motor nerves were tested in all patients and the serum antiganglioside antibody levels were de­tec­ted, as well. MMN patients showed significantly higher ADMA (p = 0.0048; 0.98 and 0.63, respectively) and SDMA le­vels (p = 0.001; 0.88 and 0.51, respectively) than healthy controls, while L-arginine was not different. Controlling for the covariant age, ADMA (B = -0.474; p = 0.041) or SDMA (B = -0.896; p < 0.0005) serum levels proved to be the significant predictors of the presence of MMN. IVIG therapy decreased significantly ADMA concentrations (p = 0.025; 0.98 and 0.84, respectively) and showed a trend to reduce SDMA levels (p = 0.1; 0.88 and 0.74, respectively). The dimethylamine levels did not correlate with the number of affected nerves, disease duration, or the presence of ganglioside antibodies. The conduction block-related peripheral motor dysfunction improved right after the IVIG treatment. Dimethylamine levels are elevated in the serum and are responsive to IVIG therapy in MMN. These findings support the presence of oxidative stress in MMN.