Shinro Mashiko

Generation of O−2 and tyrosine cation-mediated chemiluminescence during the fertilization of sea urchin eggs

Sea urchin eggs emit light in the visible region during their fertilization. Judging from the chemiluminescence spectra, one of the excited species generated is considered to have originated from a tyrosine cation radical‐mediated reaction. Chemiluminescence probes such as luminol or a cypridina luciferin analog (2‐methyl‐6‐[p‐methoxyphenyl]‐3,7‐dihydroimidazo‐[1,2‐a]pyrazin‐3‐one) are useful for detecting the ovoperoxidase+H2O2 reaction associated with membrane hardening and O− 2 generation, respectively, during the fertilization of sea urchin eggs.

The first observation of O2− generation in in situ lungs of rats treated with drugs to induce experimental acute respiratory distress syndrome

To investigate O2 − generation in in situ lungs of rats treated with drugs to induce experimental acute respiratory distress syndrome, phorbol myristate acetate (PMA) or endotoxin were injected into rats, who had been continuously infused with 2(methyl‐6‐[p‐methoxyphenyl]‐3,7‐dihydro‐imidazo[l,2‐α]pyrazin‐3‐one (MCLA) and the chemiluminescence in in situ lung was detected by a sensitive photon counter. In PMA‐treated rats, two phases of chemiluminescence over non‐specific chemiluminescence were observed. The first phase luminescence was sensitive to Cu‐Zn superoxide dismutase, while the second phase chemiluminescence was less sensitive to Cu‐Zn Superoxide dismutase. Similar chemiluminescence was detected in the rats treated with endotoxin instead of PMA, but not in neutropenic rats.

Antioxidative Activity of Amino Acids and Sulfur-containing Compounds to Superoxide : Measurement by Quenching the Chemiluminescence of a Cypridina Luciferin Analogue

Reaction rate constants between superoxide (O2(-)) and natural anti-oxidants, amino acids and some related sulfur-containing compounds were determined by quenching the chemiluminescence of a Cypridina luciferin analogue, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (CLA) in pH 7.0 buffer solutions at 25°C as described in our previous report. The results are discussed in comparison with the literature data. We found that the present method can be applied to measured antioxidative activity of even a fairly unstable sample.

Spectroscopic and quantitative measurements of singlet oxygen molecules generated in laser-excited photosensitive dyes

The therapeutic efficacy of photodynamic therapy (PDT) of malignant tumors utilizing is related to the capability of the photosensitizer to produce excited singlet molecular oxygen(1-0). This work is devoted to the study on detection of 102 molecules produced by two chlorin-type dyes, pheophorbide a (PPa) and chlorin e6Na (Chl) using a highly sensitive near-infrared spectrometer and comparison of their emitted intensity was made with hematoporphyrin derivative (HpD) and Rhordamin 123 (Rd) in water and methanol. By the irradiation of an Ar or Kr laser light, near-infrared emission spectra around 1.27 jim from the 102 molecules were detected in HpD and Chi aqueous solutions, as well as in Chl, PPa, and Rd methanol solutions. The ratio of their emission intensities at 1.27 jim is found to be 1 : 3.7 : 22 : 15 1 for HpD and Chi aqueous solutions and Chl, PPa, and Rd methanol solutions, respectively. These quantitative results support the conclusion that because of greater production of 102 molecules, PPa and Chl provide more effective SPIE Vol. 1203 Photodynamic Therapy: Mechanisms 11(1990) / 97 photosensitized dyes for the PDT following 102 molecule generation than HpD or Rd when used in conjunction with the laser-excitation and endoscopy.