Browsing by Author "Chang, H. C."

Fabrication and characterization of microstructured polymer optical fibers (MPOFs) are presented. The effects of drawing temperature and heating time during the fabrication processes are studied. The fibers exhibit single-mode characteristics as predicted by numerical simulation.

The effect of propofol on the hepatic and extrahepatic conjugation enzyme systems was assessed in vitro using microsomal and cytosolic preparations of human liver, hamster kidney, lung and gut. The functional activities of phase-II enzymes, including uridine diphosphate- glucuronosyltransferase (UDPGT), glutathione S-transferase ( GST) and N- acetyltransferase (NAT) were evaluated in the presence of various concentrations of propofol (0.05-1.0 mmol litre(-1)), using 1-naphthol, 1- chloro-2,4- dinitrobenzene and p-aminobenzoic acid as substrates respectively. Propofol produced concentration-dependent inhibition of UDPGT activity in human liver microsomes. Propofol did not produce significant inhibition of human hepatic GST activity at concentrations below 1.0 mmol litre( -1). In contrast, NAT activity was unaffected by propofol 0. 05-1.0 mmol litre(-1) in human liver cytosolic preparations . in extrahepatic tissues, hamster renal and intestinal UDPGT activities were significantly inhibited by propofol at 0.25-1.0 mmol litre(-1). In these tissues, GST and NAT were unaffected by propofol at 1.0 mmol litre(- 1). Propofol produced differential inhibition of human liver and hamster extrahepatic conjugation enzymes as a result of different substrate and tissue specificities. The potential interference of the metabolic profile of phase-II enzymes as a result of inhibition by propofol (especially of UDPGT and GST) should be considered when using propofol with other drugs for anaesthesia.

Nanodiamonds containing high density ensembles of negatively charged nitrogen-vacancy (NV-) centers are promising fluorescent biomarkers due to their excellent photostability and biocompatibility. The NV-?' centers in the particles have a fluorescence lifetime of up to 20ns ...ns, which distinctly differs from those (<10 ...ns) of cell and tissue autofluorescence, making it possible to achieve background-free detection in vivo by time gating. Here, we demonstrate the feasibility of using fluorescent nanodiamonds (FNDs) as optical labels for wide-field time-gated fluorescence imaging and flow cytometric analysis of cancer cells with a nanosecond intensified charge-coupled device (ICCD) as the detector. The combined technique has allowed us to acquire fluorescence images of FND-labeled HeLa cells in whole blood covered with a chicken breast of ?0.1-mm thickness at the single cell level, and to detect individual FND-labeled HeLa cells in blood flowing through a microfluidic device at a frame rate of 23 ...Hz, as well as to locate and trace FND-labeled lung cancer cells in the blood vessels of a mouse ear. It opens a new window for real-time imaging and tracking of transplanted cells (such as stem cells) in vivo.