Figure 1. FDP levels decrease in the same subjects after moving from Denver, USA, to Seoul, South Korea, during the same winter season.

STS samples were collected from 4 normal, healthy subjects and 1 convalescent AD subject. A total of 10 consecutive STS samples were collected from the same subjects several months apart while they lived in Denver and Seoul. STS samples were processed, and FDP levels were evaluated using liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). (A) PCA. (B) Total UCA. (C) Cis-UCA. (D) Trans-UCA. (E) Cis/trans-UCA. Circles, normal healthy subjects; squares, convalescent AD subjects. n = 5 per group. *P < 0.05, **P < 0.01 by paired 2-tailed Student’s t test.