ABSTRACT
Objective: To make an initial assessment of the correlation between immersive virtual reality-based (ILBT) line bisection testing and paper-and-pencil-based line bisection (PLBT) testing in healthy subjects. Design: Diagnostic study. Setting: Research laboratory. Participants: Twenty healthy adults (51.5 [11.0] years old, 55% women; N=20). Interventions: Participants underwent an ILBT and a conventional PLBT in near space (NS) and more distant space (MDS). Correlations between the ILBT and PLBT, deviation rates in the NS and MDS, horizontal gaze distribution, and presence of virtual reality sickness (VRS) were evaluated. Main Outcome Measures: Correlation between the deviation rates of the PLBT and ILBT. Results: There was no significant correlation between the ILBT and PLBT for evaluating the deviation rate of the line bisection test (LBT). There was no significant difference in the deviation rate of the LBTs between the NS and MDS, but there was a significant difference in the horizontal line-of-sight distribution. VRS was not observed as an adverse event. Conclusions: In healthy adult subjects, our results suggested that there was no significant correlation between the deviation rates of the ILBT and PLBT. We also found that the ILBT is a useful and safe method for evaluating the horizontal line-of-sight distribution and percentage deviation of line segments from the center in the NS and MDS without inducing VRS.
ABSTRACT
Stem cell factor is essential to the migration and differentiation of melanocytes during embryogenesis based on the observation that mutations in either the stem cell factor gene, or its ligand, KIT, result in defects in coat pigmentation in mice. Stem cell factor is also required for the survival of melanocyte precursors while they are migrating towards the skin. Transforming growth factor beta1 has been implicated in the regulation of both cellular proliferation and differentiation. NCC-melb4, an immortal cloned cell line, was cloned from a mouse neural crest cell. NCC-melb4 cells provide a model to study the specific stage of differentiation and proliferation of melanocytes. They also express KIT as a melanoblast marker. Using the NCC-melb4 cell line, we investigated the effect of transforming growth factor beta1 on the differentiation and proliferation of immature melanocyte precursors. Immunohistochemically, NCC-melb4 cells showed transforming growth factor beta1 expression. The anti-transforming growth factor beta1 antibody inhibited the cell growth, and downregulated the KIT protein and mRNA expression. To investigate further the activation of autocrine transforming growth factor beta1, NCC-melb4 cells were incubated in nonexogenous transforming growth factor beta1 culture medium. KIT protein decreased with anti-transforming growth factor beta1 antibody concentration in a concentration-dependent manner. We concluded that in NCC-melb4 cells, transforming growth factor beta1 promotes melanocyte precursor proliferation in autocrine and/or paracrine regulation. We further investigated the influence of transforming growth factor beta1 in vitro using a neural crest cell primary culture system from wild-type mice. Anti-transforming growth factor beta1 antibody decreased the number of KIT positive neural crest cell. In addition, the anti-transforming growth factor beta1 antibody supplied within the wild-type neural crest explants abolished the growth of the neural crest cell. These results indicate that transforming growth factor beta1 affect melanocyte precursor proliferation and differentiation in the presence of stem cell factor/KIT in an autocrine/paracrine manner.
