Harn-Jou Yeh

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Platelet-derived growth factor (PDGF) may be a critical factor in the temporal differentiation of glial elements in the mammalian central nervous system. We have used in situ hybridization and immunoperoxidase staining to investigate the localization of PDGF A and have observed high levels of PDGF A-chain mRNA and immunoreactive PDGF A in neurons of(More)
We recently reported that the platelet-derived growth factor (PDGF) A-chain gene is highly expressed in neurons of embryonic and adult mouse central nervous system and suggested that its secretion by neurons may support development and maintenance of glia. We have now analyzed the levels and sites of expression of the cognate PDGF alpha-receptor gene in(More)
Pleiotrophin (PTN) is a heparin-binding, 18 kDa secretory protein that functions to induce mitogenesis, angiogenesis, differentiation, and transformation in vitro. PTN gene (Ptn) expression is highly regulated during development and is highest at sites in which mitogenesis, angiogenesis, and differentiation are active. In striking contrast, with the(More)
Algorithms for identifying closed form surface patches on the boundary of 5DOF manipulator workspaces are developed and illustrated. Numerical algorithms for the determination of three-and four-DOF manipulator workspaces are available, but formulations for determining equations of surface patches bounding the workspace of five-DOF manipulators were never(More)
A general formulation for determining complex sweeps comprising a multiple of parameters has been presented by the authors in recent work. This paper investigates the boundaries to swept volumes, and in specific, addresses the problem of determination of voids in the volume. The determination of voids has become of major concern in CAD software, where the(More)
Trophic factors are being increasingly recognized as important contributors to growth, differentiation, and maintenance of viability within the mammalian nervous system during development. Pleiotrophin (PTN) is a secreted 18-kDa heparin binding protein that stimulates mitogenesis and angiogenesis and neurite and glial process outgrowth guidance activities(More)