Separation and detection of D-/L-serine by conventional HPLC.

D-serine has a role as an endogenous allosteric agonist of N-methyl-D-aspartate (NMDA) receptor in the mammalian brain. In this study, we present a detailed description of our method that measures D-/L-serine by using conventional high performance liquid chromatography (HPLC). • We reacted D-serine and L-serine with ortho-phthalaldehyde (OPA) and N-acetyl-L-cysteine (NAC) to form diastereomeric isoindole derivatives, then we separated and detected them by conventional reversed phase HPLC with electrochemical detector (ECD). • We present typical measurement data of rat brain homogenate as an example of a convenient, appropriate method for measuring brain concentrations of D-serine. • Since many peaks appear in biological samples, we confirmed that the peaks were derived from serine by treating the sample with D-amino oxidase and catalase to decompose D-serine. As a results, one peak disappeared, suggesting that it is derived from D-serine.

Increased blood-brain barrier vulnerability to systemic inflammation in an Alzheimer disease mouse model.

Behavioral and psychological problems are often observed in patients with dementia such as that associated with Alzheimer disease, and these noncognitive symptoms place an extremely heavy burden on the family and caregivers. Although it is well know that these symptoms often are triggered by infection of peripheral organs, the underlying mechanisms for these pathological conditions are still unclear. In this study, using an Alzheimer amyloid precursor protein (APP)-transgenic mouse, we analyzed behavioral changes and brain inflammatory response induced by peripheral administration of lipopolysaccharide. Application of a unique in vivo microdialysis system revealed that the increase in brain inflammatory cytokine (interleukin-6) level was significantly higher in APP-Tg than in wild-type mice after peripheral lipopolysaccharide injection, which was associated with more severe sickness behaviors. The blood-brain barrier became more permeable in APP-Tg mice during peripherally evoked inflammation, suggesting the increased vulnerability of the blood-brain barrier to inflammation in this animal model of Alzheimer's disease. These findings might provide insight into the pathogenesis of noncognitive symptoms in dementia and a basis to develop new therapeutic treatments for them.

A high recovery microsampling device based on a microdialysis probe for peptide sampling.

A high recovery microsampling probe based on microdialysis was devised. The new probe showed a high recovery (100%) of peptides in vitro at different perfusion flow rates (0.1-1.0 microl/min). At a high flow rate, 1.0 microl/min, a 10-fold increased in recovery of peptides compared to the conventional microdialysis probe was achieved. A probe made of a low molecular weight cutoff membrane is suitable for filtering off proteins. The new probe can be a useful tool for high recovery of peptides from living tissues.