PubMed Health⌕ Search

Biomedical subjects

W L Ling

Publications and source records attributed to W L Ling.

7 recordsLinked to original sources
PubMed2005

Twin boundaries can be moved by step edges during film growth.

We track individual twin boundaries in Ag films on Ru(0001) using low-energy electron microscopy. The twin boundaries, which separate film regions whose close-packed planes are stacked differently, move readily during film growth but relatively little during annealing. The growth-driven motion of twin boundaries occurs as film steps advance across the surface--as a new atomic Ag layer reaches an fcc twin boundary, the advancing step edge carries along the boundary. This coupling of the microstructural defect (twin boundary) and the surface step during growth can produce film regions over 10 microm wide that are twin free.

Journal Article↗
PubMed2004

Enhanced self-diffusion on Cu(111) by trace amounts of s: chemical-reaction-limited kinetics.

We find that less than 0.01 monolayer of S can enhance surface self-diffusion on Cu(111) by several orders of magnitude. The measured dependence of two-dimensional island decay rates on S coverage (theta(S)) is consistent with the proposal that Cu3S3 clusters are responsible for the enhancement. Unexpectedly, the decay and ripening are diffusion limited with very low and very high theta(S) but not for intermediate theta(S). To explain this result we propose that surface mass transport in the intermediate region is limited by the rate of reaction to form Cu3S3 clusters on the terraces.

Journal Article↗
PubMed2004

Strain relief through heterophase interface reconstruction: Ag(111)/Ru(0001).

We report an experimental (scanning tunneling microscopy) and theoretical (embedded atom method) study of a heterophase interface reconstruction between Ag(111) and Ru(0001). Despite the large 7% mismatch, the second layer of Ag from the Ru exhibits a hexagonal structure with Ag bulk spacing, providing a close match to bulk Ag. The first layer of Ag (next to Ru) is reconstructed in a highly symmetrical and regular structure containing monolayer long threading dislocations. We argue that this structure may generally occur to relieve strain in a certain class of heterophase interfaces.

Journal Article↗
PubMed1998

The use of permeabilized cells to investigate secretory granule biogenesis.

To investigate the mechanism of secretory granule biogenesis in endocrine cells, our laboratory used rat anterior pituitary GH3 cells which secrete growth hormone and prolactin. Here we describe a simple and rapid procedure for generating permeabilized cells to dissect molecular mechanisms involved in nascent secretory vesicle budding from the trans-Golgi network (TGN). Using this system, we demonstrate that vesicle budding is temperature, energy, and cytosol dependent; in addition, cytosol from a variety of cells, including yeast (Saccharomyces cerevisiae), can support vesicle release. The budding of nascent secretory vesicles from the TGN is stimulated by a phospholipase D activity that is associated with Golgi membranes. Our results suggest that phospholipid metabolism plays an important role in the release of nascent secretory vesicles from the TGN.

ADP-Ribosylation Factors↗
PubMed1996

Formation of secretory vesicles in permeabilized cells: a salt extract from yeast membranes promotes budding of nascent secretory vesicles from the trans-Golgi network of endocrine cells.

The mechanism of secretory-vesicle formation from the trans-Golgi network (TGN) of endocrine cells is poorly understood. To identify cytosolic activities that facilitate the formation and fission of nascent secretory vesicles, we treated permeabilized pituitary GH3 cells with high salt to remove endogenous budding factors. Using this cell preparation, secretory-vesicle budding from the TGN required addition of exogenous cytosol and energy. Mammalian cytosols (GH3 cells and bovine brain) promoted post-TGN vesicle formation. Most significantly, a salt extract of membranes from the yeast Saccharomyces cerevisiae, a cell lacking a regulated secretory pathway, stimulated secretory vesicle budding in the absence of mammalian cytosolic factors. These results demonstrate that the factors which promote secretory-vesicle release from the TGN are conserved between yeast and mammalian cells.

Animals↗
PubMed1991

Characterization of a monoclonal antibody (RJ5) against the immunodominant 41-kD antigen of Candida albicans.

A 41-kD component of Candida albicans was identified to be the major antigen radioimmunoprecipitated by antibodies with increased titers in the sera of patients with invasive candidiasis. A mouse monoclonal antibody (RJ5) was generated which, by immunoblotting, showed positive reactivity to the immunoprecipitated 41-kD component. By two-dimensional gel electrophoresis and immunoblotting, MoAb RJ5 was shown to react with different isoforms of the 41-kD component with pI values from 6.1 to 6.9. Furthermore, MoAb RJ5 showed positive reactivity to cytoplasmic antigens of C. albicans by frozen section and immunoperoxidase staining. By SDS-polyacrylamide gel electrophoresis and immunoblotting, MoAb RJ5 showed no cross-reactivity to antigens of Candida tropicalis and Candida parapsilosis. The epitope of the 41-kD molecule recognized by MoAb RJ5 was susceptible to treatment of proteinase K at concentrations of greater than or equal to 5 micrograms/ml, and was relatively resistant to periodate oxidation with concentration of NaIO4 up to 20 mM. This MoAb may be useful in the purification and characterization of the immunodominant 41-kD antigen of C. albicans, and as a probe in the detection of Candida antigens in the sera of patients with invasive candidiasis.

Antibodies↗