Many studies have suggested that CD8 Abs affect the binding of class I MHC tetramers/multimers to CD8(+) T cells, which has led to the interpretation that CD8 participates directly in multimer binding. In contrast, a recent publication has argued that CD8 Abs instead cause reorganization of TCR distribution and hence have an indirect effect on multimer binding to the TCR alone. We address these...

The TCR alpha-chain is assembled by somatic recombination of variable (V) and joining (J) gene segments at the CD4+ CD8+ stage of development. In this study, we present the first analytical model for deletional rearrangement and show that it is consistent with almost all available data on Valpha Jalpha use in mice and humans. A key feature of the model is that both "local" and "express service"...

Magnetotransport measurements of Y1 xPrxBa2Cu3O7 d (x 1⁄4 0, 0.13, 0.2, 0.32, and 0.42) single crystals reveal two regimes in the pseudogap region for the xP 0:20 samples, with a crossover at a temperature TcrðxÞ. For Tc < T < Tcr, there is a vortex-like response in magnetoresistivity. For T > Tcr, the results are consistent with the picture in which the origin of the pseudogap is the nearly an...

Many tyrosinase inhibitors have been alleged to have serious side effects. To search for relatively mild and safe tyrosinase inhibitors, two new 8-O-4′ neolignans, named huangnin A (1) and B (2), and four known analogs (3-6) were isolated from the seeds of Crataegus pinnatifida. Their structures were elucidated by spectroscopic analyses (1D, 2D NMR, HRESIMS, CD and Rh2(OCOCF3)4-induced CD). In ...

In this issue, Xu et al. (2008) provide evidence for a new mechanism of T cell receptor regulation. Prior to activation, basic residues in the cytoplasmic domain of the signaling subunits of the T cell receptor associate with the plasma membrane such that the key signaling tyrosines are sequestered in the bilayer.