Oxidized protein hydrolase (OPH), an 80 kDa serine protease whose activity is inhibited by diisopropyl fluorophosphate (DFP), has been isolated from human erythrocytes [Fujino, T. et al. (1998) J. Biochem. 124, 1077-1085]. The presence of OPH in various biological samples was examined by enzyme-linked immunosorbent assay (ELISA) and immunoblotting using an anti-OPH antibody raised against OPH purified from human erythrocytes, and by [(3)H]DFP-labeling and successive SDS-PAGE/fluorography. Solubilized samples of human cell lines including K-562 cells, THP-1 cells and Jurkat cells, and rat tissues including brain, heart, liver, kidney, and testis, inhibited the anti-OPH antibody binding to OPH in ELISA. Immunoblotting of lysates of K-562 cells, THP-1 cells and Jurkat cells showed four immunoreactive protein bands including an 80 kDa protein. Immunoprecipitation of the [(3)H]DFP-labeled K-562 cell lysate and successive SDS-PAGE/fluorography showed the presence of only the 80 kDa DFP-reactive protein with OPH antigenic activity. The level of the 80 kDa immunoreactive protein in K-562 cells rose as the cells differentiated toward erythrocytes. Immunoblotting of human and rat plasma showed two immunoreactive protein bands, including the 80 kDa protein, and SDS-PAGE/fluorography of [(3)H]DFP-labeled rat and human plasma showed the presence of only the 80 kDa DFP-reactive protein. The results indicate that OPH is present in a wide variety of biological samples.
The plastic fiber humidity sensor, the mechanism of which is based
on an ionization reaction between water vapor and the fluorescent dye-doped
polymer cladding, was studied. The conditions under which to obtain the
maximum sensitivity were derived from the theory and experimental data.
Under these conditions, the fluorescent plastic fiber could be used as an
excellent optical humidity sensor head with good linearity over the wide
humidity range. Due to its reproducibility and fast response property, its
application to a breathing-condition monitor became possible.
An attempt has been made to improve the sensitivity and stability of the polymer optical fiber (POF) sensor for continuous monitoring of gaseous oxygen. It utilizes the quenching phenomenon of cladding fluorescence. Three polymers namely, poly(cyclohexyl methacrylate) (PCMA), poly(l-menthyl methacrylate) (PMtMA) and poly(4-methyl-1-pentene), which have a relatively large oxygen permeability, were used as cladding layer doped with a sensitive dye such as a 9,10-diphenyl anthracene (DPA), on the polymer cores with 1 mm diameter. When these sensor heads were pumped using a D2-lamp, the response at the fluorescence of λ=431 nm was found to be very fast and reversible in all the cases, for oxygen concentrations ranging from 0.5% to 100%. However, the differences in fluorescence quenching rate, stability and response time were observed to be dependent upon the polymer used. In particular, the PCMA sample showed good long-term stability. These comparative studies of POF oxygen sensors seem to be useful for developing practical devices.
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