Cong Yu — Page 2 | PubMed Health

PubMed2002

What role for FTY720, a novel immunosuppressive agent, in canine nonmyeloablative hematopoietic stem cell transplantation?

BACKGROUND: Stable mixed donor/host hematopoietic chimerism was almost uniformly achieved in dogs given 200 cGy total body irradiation (TBI) before, and a short course of immunosuppression after, transplantation of marrow from dog leukocyte antigen-identical littermates, but was transient when the TBI dose was decreased to 100 cGy. Here, we examined whether stable engraftment could be achieved in five dogs given FTY720 (days -5 and -4), followed by 100 cGy TBI, dog leukocyte antigen-identical marrow grafts, and mycophenolate mofetil/cyclosporine. RESULTS AND CONCLUSIONS: Although all five dogs showed initial engraftment, four dogs rejected their grafts within 11 weeks, whereas one dog was euthanized on day 17 due to enteritis. This was not different from the control dogs not given FTY720 (P=0.32). Thus, FTY720 failed to enhance allogeneic engraftment in this model, perhaps due to in vivo T-cell depletion of the graft resulting from sequestration of donor lymphocytes in host central lymphoid tissues.

Animals↗

PubMed2002

Facilitation of contrast detection by cross-oriented surround stimuli and its psychophysical mechanisms.

Neurophysiological and psychophysical evidence indicates that neuronal surround modulation at cross-orientation (orthogonal to the preferred orientation of the classical receptive field) plays a key role in intermediate-level visual tasks, such as textural segregation and perceptual pop-out. What is missing is a psychophysical description of cross surround modulation at the spatial filter level in low-level vision. Moreover, neurophysiological evidence for how cross surround modulation is expressed at the neuronal level has been inconsistent. Here we report evidence for psychophysical facilitation of contrast detection by cross surround stimuli (orthogonal to the target orientation) that may provide insights into both the neurophysiology and psychophysics of cross surround modulation. We found that cross surround facilitation is a surround-contrast dependent effect mainly evident at low surround contrasts, and is narrowly tuned to spatial frequency and broadly tuned to orientation. To understand whether cross surround facilitation results from low-level processing of signal-to-noise enhancement or is due to uncertainty reduction at a higher-level decision stage, we (1) studied cross surround facilitation with an equivalent noise protocol, (2) estimated the changes in the slope of the psychometric function and the uncertainty parameter, M, and (3) measured cross surround effects at the dipper of the TvC function. The converging evidence suggests that cross surround facilitation of contrast detection is mainly a result of low-level signal-to-noise enhancement, and is little affected by uncertainty change.

Contrast Sensitivity↗