Malic dehydrogenase has been used in a study to assess the effect of an immunomodulator S2 complex on the enzymes of the parasites.  It has also been used in a study to investigate the heterogeneity of lactic and malic dehydrogenase in cerebrospinal fluid. 
Malic Dehydrogenase (MDH) plays an important role in the citric acid cycle in mitochondria. It catalyzes the interconversion of substrates malate and oxaloacetate with the simultaneous oxidation/reduction of NAD/NADH+. MDH present in the cytosol is involved in the shuttling of malate/aspartate.
One unit will convert 1.0 μmole of oxalacetate and β-NADH to L-malate and β-NAD per min at pH 7.5 at 25°C.