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Biomedical subjects

S S Fan

Publications and source records attributed to S S Fan.

11 recordsLinked to original sources
PubMed2006

Controlled synthesis and field emission properties of ZnO nanostructures with different morphologies.

By simply controlling atmosphere, rods, tetraleg-rods, and arrays of ZnO nanostructures have been fabricated respectively through pure zinc powder evaporation without catalyst at temperature of 650 - 700 degrees C. Investigations through HRTEM and XRD showed that the growth of the synthesized ZnO nanostructures was controlled by vapor-solid mechanism. Field emission measurements revealed that all of the structures, owing to their very low turn-on voltage, sufficient emission current and proper linearity of 1/V - Ln(l/V2), are likely to be potential candidates as a field emitter. The results also indicated that field emission properties are relative to morphology and size of the tips of ZnO nanostructures, and the nanorods with sharp tips possess the first-class FE property.

Crystallization↗
PubMed2003

Visualizing caveolin-1 and HDL in cholesterol-loaded aortic endothelial cells.

Caveolae are vesicular invaginations of the plasma membranes that regulate signal transduction and transcytosis, as well as cellular cholesterol homeostasis. Our previous studies indicated that the removal of cholesterol from aortic endothelial cells and smooth muscle cells in the presence of HDL is associated with plasmalemmal invaginations and plasmalemmal vesicles. The goal of the present study was to investigate the location and distribution of caveolin-1, the main structural protein component of caveolae, in cholesterol-loaded aortic endothelial cells after HDL incubation. Confocal microscopic analysis demonstrated that the caveolin-1 appeared to colocalize with HDL-fluorescein 1,1'-dioctadecyl 3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) conjugates on the cell surface. No free HDL-DiI conjugates were revealed in the cytoplasm. Immunoelectron microscopy further demonstrated that caveolin-1 gold (15 nm) conjugates colocalized with HDL gold (10 nm) conjugates in the plasmalemmal invaginations. These morphological results indicated that caveolae are the major membrane domains facilitating the transport of excess cholesterol to HDL on the cell surface of aortic endothelial cells.

Animals↗
PubMed1997

Differential expression of the GABAA receptor alpha 1 subunit in developing chicken brain.

A unique segment of chicken GABAA receptor alpha 1 subunit was expressed in E. coli and used to generate an antiserum 2A specific for the subunit. The DNA fragment encoding the segment of alpha 1 was obtained by selective amplification by polymerase chain reaction (PCR) from a chicken brain cDNA library. The antiserum is characterized by its capacity to immunoprecipitate a [3H]flunitrazepam binding protein of 50 kDa, the chicken GABAA receptor alpha 1 subunit. Subsequent immunoblotting and immunocytochemistry analyses reveal that alpha 1 is expressed in the optic tectum and cerebellum as early as embryonic day 15 (E15), in various areas of telencephalon as early as E20 and distributed heterogeneously among different cell types. The early expression of alpha 1 may imply its functional significance in neurotransmission.

Animals↗
PubMed1997

Glued participates in distinct microtubule-based activities in Drosophila eye development.

A C-terminal truncation of Glued, the Drosophila homolog of the cytoplasmic dynein activating protein, dynactin, results in a severe and complex retinal phenotype, including a roughening of the facet array, malformation of the photosensitive rhabdomeres, and a general deficit and disorder of retinal cells. We have characterized the developmental phenotype in Glued1 and found defects in multiple stages of eye development, including mitosis, nuclear migration, cell fate determination, rhabdomere morphogenesis and cell death. Transgenic flies that express dominant negative Glued under heat-shock control reproduce distinct features of the original Glued1 phenotype depending on the stage of development. The multiple phenotypes effected by truncated Glued point to the multiple roles served by dynactin/dynein during eye development.

Animals↗
PubMed1990

Monoclonal antibodies recognizing the benzodiazepine receptor of chick embryo brain.

The benzodiazepine receptor (BZDR) of the embryonic chick brain contained three subunit proteins with molecular weights of 48-kilodalton (KD), 50-KD and 51-KD at a pI of 5.6, as demonstrated by two-dimensional gel electrophoresis and fluorography of the 3H-flunitrazepam (FNZ)-photolabeled receptor. Monoclonal antibodies (mAB) against the receptor were produced by using the spleen cells of one mouse immunized with the three subunit proteins extracted from SDS-PAGE gels. When the radioligand-labeled membranes were subjected to two-dimensional gel electrophoresis followed by immunoblotting using the mAB 2C3, both 50-KD and 51-KD bands with a pI of 5.6 were immunoreactive and radioactive. Thus, the mAB 2C3 recognized a common epitope on the 50-KD and 51-KD subunits of the BZDR. In addition, the mAB 2C3 was used with immunocytochemistry to determine the distribution of the receptor in the chick embryo brain. The BZDR immunoreactivity was observed among various brain areas, including hippocampus, optic tectum and cerebellum. The reaction product was localized in the neuronal membranes and cytoplasm. Certain neurons in the culture derived from embryonic chick brains were also immunoreactive as detected by immunocytochemical staining.

Animals↗
PubMed1981

Membrane effects of antiinflammatory agents. 1. Interaction of sulindac and its metabolites with phospholipid membrane, a magnetic resonance study.

High-resolution proton NMR and spin-label ESR spectroscopies have been applied to examine the interaction of the nonsteroidal antiinflammatory drug sulindac (1) and its active sulfide metabolite (2) and inactive sulfone metabolite (3) with phospholipid membranes. Only weak interactions were observed with 1 and 3, but a strong interaction with 2 was indicated both by specific changes in the proton transverse relaxation rate (1/T2) of different substituents in 2 and by a unique shift in membrane transition temperature in the presence of 2 as measured by the ESR technique. Since the structural differences of these compounds are confined to a single polar substituent, i.e., the oxidation state of the sulfur atom, the strong interaction of the sulfide metabolite (2) with the neutral phospholipid membrane is ascribed to its high partition coefficient in the lipid membrane and its ability to penetrate into the lipid bilayer with the carboxyl group remaining at the polar membrane surface. As evidenced from the ESR spectra of two spin-labels, C5- and C12-doxylstearic acid, no significant change of the membrane fluidity was induced by the interaction of 2 with phospholipid vesicles.

Electron Spin Resonance Spectroscopy↗
PubMed1981

The mechanism of anticoccidial action of arprinocid-1-N-oxide.

Neither arprinocid nor its liver microsomal metabolite arprinocid-1-N-oxide binds to calf thymus DNA. Neither compound showed an effect on the synthesis of DNA, RNA, or proteins in HeLa cells or on the rate of respiration by Eimeria tenella mitochondria. The 1-N-oxide differs from the parent compound by its toxic effect on HeLa cells (ID50 = 5.0 ppm) reflected primarily through cellular vacuole formation from dilation of rough endoplasmic reticulum structures. Similar vacuole formation was observed in E. tenella merozoites pulse-treated with the drug. This effect on both types of cells is prevented by SKF-525A, an inhibitor of microsomal drug metabolism. Drug-induced visible absorption difference spectra and alterations in the electron paramagnetic signal of rat liver microsomal cytochrome P-450 indicate direct bindings of arprinocid-1-N-oxide to cytochrome P-450. These findings suggest cytochrome P-450 mediated microsomal metabolism involving arprinocid-1-N-oxide as part of the mechanism of antococcidial action of the drug. This metabolism may cause destruction of endoplasmic reticulum leading to cell death.

Adenine↗
PubMed1979

Anticomplementary activity of tuberculin: relationship to platelet aggregation and lytic response.

Experiments were performed to examine the interaction of tuberculin with platelets and complement. Hemolytic complement titrations show that tuberculin consumes complement in human, rabbit, and guinea pig serum. Evidence in support of classical pathway activation was provided by observation of C1 consumption and failure to detect significant conversion of alternative pathway factor B to B by immunoelectrophoresis. Platelets in plasma from guinea pigs deficient in the fourth component of complement were not affected by tuberculin. However, studies on platelet aggregation in plasma chelated with ethyleneglycolbis(beta-aminoethyl ether)-N,N-tetraacetic acid indicated that tuberculin may initiate sluggish activation of the alternative pathway. That the reaction between tuberculin and platelets is a lytic one was evidenced by observing the release of the cytoplasmic enzyme lactic dehydrogenase and efflux of rubidium-86. Studies with C6-deficient rabbits indicated that platelet release of exogenously supplied tritiated serotonin is caused by platelet lysis.

Animals↗