Can one really measure magnesium deficiency using the short-term magnesium loading test?

Objective: To compare a 1-h-version of a magnesium-loading-test (MLT) designed for outpatients in healthy controls with the 8-h standard; to establish the test in patients after renal transplantation prone to develop magnesium (Mg) deficiency; to correlate femur Mg-concentration and percentage retention of the given load.

Design: Comparison of mean values from healthy controls with respective from the literature; a prospective, randomized, controlled 4-month study; an intra-individual correlation of Mg-serum values and loading-test data with femur-Mg concentrations.

Setting: One centre study in a medical university; outpatients from the transplant unit; inpatients from the orthopedic unit.

The presaccadic cortical negativity prior to self-paced saccades with and without visual guidance.

The presaccadic negativity (PSN) of the scalp EEG potential prior to self-initiated saccades aimed either at a visual target or at the remembered position of that target in total darkness was analysed in 10 normal subjects. Under both conditions a PSN with a negligible EOG contamination was found, showing 4 characteristics: (1) In both conditions, the PSN maximum is localized at the vertex, probably containing the activity of the supplementary motor area. (2) At an electrode placed over the frontal eye field (FEF) contralateral to the saccade direction, there is a temporary, circumscribed maximum prior to saccades to the visual target, thus probably reflecting activity of the FEF.