Cortical glutamate levels decrease in a non-human primate model of dopamine deficiency.

While Parkinson's disease is the result of dopaminergic dysfunction of the nigrostriatal system, the clinical manifestations of Parkinson's disease are brought about by alterations in multiple neural components, including cortical areas. We examined how 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration affected extracellular cortical glutamate levels by comparing glutamate levels in normal and MPTP-lesioned nonhuman primates (Macaca mulatta). Extracellular glutamate levels were measured using glutamate microelectrode biosensors. Unilateral MPTP-administration rendered the animals with hemiparkinsonian symptoms, including dopaminergic deficiencies in the substantia nigra and the premotor and motor cortices, and with statistically significant decreases in basal glutamate levels in the primary motor cortex on the side ipsilateral to the MPTP-lesion. These results suggest that the functional changes of the glutamatergic system, especially in the motor cortex, in models of Parkinson's disease could provide important insights into the mechanisms of this disease.

Effects of taurine supplementation on VDT work induced visual stress.

In order to evaluate the effects of dietary taurine supplementation on visual fatigue induced by visual display terminals (VDT) work, 25 male college students aged from 20 to 24 years who were not engaged in VDT work were selected to participate in the study. Volunteers were randomly assigned to either the taurine supplementation (n=13) or the placebo supplementation control group (n=12). Before and after 12 days of taurine (3 g/day) or placebo supplementation, two identical 2.5-hr VDT work tests were performed while recording the P100, N75 and N145 latencies and P100 amplitude of pattern visual evoked potential (PVEP) and the frequency of critical flicker fusion (CFF). Following 2.5-hr of VDT work, the P100 and N75 latencies of PVEP increased ( P<0.01) while the P100 amplitude decreased significantly ( P<0.01). The frequency of CFF also reduced significantly ( P<0.01). After 12 days of taurine supplementation, the reduction in P100 amplitude after VDT work alleviated significantly ( P<0.05). The results suggest that taurine supplementation alleviates visual fatigue induced by VDT work.

The primary structure of a human MAP kinase activated protein kinase 2.

Mitogen-activated protein (MAP) kinase is of central importance in mediating intracellular actions in response to a variety of extracellular stimuli. MAP kinase activated protein (MAPKAP) kinase 2 is one of the two known protein kinases that can be phosphorylated and activated by MAP kinase. Here we present the first complete primary structure of MAPKAP kinase 2 elucidated from a human cDNA sequence. Sequence analysis reveals that MAPKAP kinase 2 is a 370 amino acid protein containing a proline-rich N-terminal region and a well conserved catalytic domain. Northern blot analysis of MAPKAP kinase 2 showed a 4.8 kb mRNA species in HL-60 cells. In addition, we also show the first evidence that recombinant MAPKAP kinase 2 is phosphorylated and activated by MAP kinase in vitro.