Scavenging or Quenching Effect of Melanin on Superoxide Anion and Singlet Oxygen

Although photoprotective properties of skin melanin have been well documented, a few studies on the effect of melanin on reactive oxygen species (ROS) generated by ultraviolet (UV) irradiation have been reported. To study the interaction of melanin with ROS, scavenging or quenching effect of melanin on O2•− and 1O2 was examined by electron spin resonance (ESR)-spin trapping methods and a spectrophotometric method, respectively. Melanin potently interacted with O2•− generated in a hypoxanthine (HPX)-xanthine oxidase (XOD) reaction, and with 1O2 generated from a peroxidase, H2O2, and halide system. In the HPX-XOD reaction, it was proved that melanin doses not interfere with the enzyme reaction. It is confirmed that one of the mechanisms by which melanin protects UV-induced skin damage is likely scavenging or quenching activity against ROS such as O2•− and 1O2

Generation Mechanism of Radical Species by Tyrosine-Tyrosinase Reaction

Alleviated melanin formation in the skin through inhibition of tyrosine-tyrosinase reaction is one of the major targets of cosmetics for whitening ability. Since melanin has a pivotal role for photoprotection, there are pros and cons of inhibition of melanin formation. This study applying electron spin resonance (ESR)-spin trapping method revealed that •H and •OH are generated through tyrosine-tyrosinase reaction. When deuterium water was used instead of H2O, the signal of 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-H (a spin adduct of DMPO and •H) greatly decreased, whilst DMPO-OH (a spin adduct of DMPO and •OH) did not. Thus, it is suggested that •H was derived from H2O, and •OH through oxidative catalytic process of tyrosine to dopaquinone. Our study suggests that tyrosinase inhibitors might contribute to alleviate the oxidative damage of the skin by inhibiting •OH generation via the enzyme reaction

A 320 k-year record of microparticles in the Dome Fuji, Antarctica ice core measured by laser-light scattering (scientific paper)

A laser-light scattering method was evaluated from the viewpoint of the measurement ability of concentration and size distribution of microparticles in molten ice core samples. It was demonstrated that analysis can be performed with 10 % accuracy by diluting the sample with ultrapure water by 50 times to eliminate coincidence loss. Using this method, the concentration and size distribution of microparticles were determined on 2829 samples from a 2503 m deep ice core drilled at Dome Fuji, Antarctica. The present paper shows the profiles of number and volume concentrations through the whole depth and the changes in the size distribution through three glacial cycles in the past 320 k-years

Geochemistry of syenite of the Phalaborwa Carbonatite Complex, South Africa

We surveyed the Spitskop syenite pipe,one of the satellite bodies of the Phalaborwa Carbonatite Complex located in northeastern Transvaal,South Africa. This pipe is composed of the inner cumulus syenite and outer ring syenite.The brecciation zone between these syenites includes many blocks of syenite,pyroxenite, melanocratic rock,biotite gneiss and granitic rocks.Dolerite dykes intruded into the plug and brecciation zone.Fine-and coarse-grained syenites,melanocratic rock, alkali-feldspar granite and dolerite were collected from the brecciation zone of this pipe.The whole-rock and mineral chemistry suggests that syenites and melanocratic rocks of the brecciation zone were derived from the inner cumulus syenite magma. These rocks do not indicate any clear isochron.It may be a result of mixing of various rocks at the brecciation stage

Myristic Acid, A Side Chain of Phorbol Myristate Acetate (PMA), Can Activate Human Polymorphonuclear Leukocytes to Produce Oxygen Radicals More Potently than PMA

Myristic acid (MyA), which is a saturated fatty acid (C14:0) and a side chain of phorbol 12-myristate 13-acetate (PMA), was examined if MyA stimulates human polymorphonuclear leukocytes (PMNs) to release oxygen radicals comparable to PMA by applying electron paramagnetic resonance (EPR)-spin-trapping method. When MyA was added to isolated human PMNs, spin adducts of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO)-OH and DMPO-OOH were time-dependently observed. The amounts of these spin adducts were larger than those of PMNs stimulated by PMA. These results clearly show that MyA is more potent agent to prime human PMNs than PMA, in a point of view of not only O2·− but also ·OH production. This fact calls attention that too much intake of MyA that is known to be contained vegetable oils can lead to crippling effect through uncontrolled production of reactive oxygen species

Chemical characteristics in a 22-m ice core on the Belukha Glacier, Russia

To better understand how the chemical composition of a glacier in an inland continental region relates to the local climate, we collected ice core samples from the Belukha Glacier, Russia, in July 2001. We analyzed the samples for pH, anions, and cations. The primary soluble ions were SO42-, NO3-, NH4+, Ca2+, and HCOO-. Moreover, we argue the following. 1) Ca2+ and its equivalent SO42-+ NO3- likely originated from terrestrial dust such as soil. 2) HCOO- and its equivalent NH4+ likely originated from vegetation and/or biomass burning. 3) The remaining SO42-+NO3- and NH4+ likely originated from livestock, commercial fertilizers, and natural fertilizers. 4) The NH4+ concentration was low when there was no contribution from vegetation and/or biomass burning

A central extension of \cD Y_{\hbar}(\gtgl_2) and its vertex representations

A central extension of \cD Y_{\hbar}(\gtgl_2) is proposed. The bosonization of level $1$ module and vertex operators are also given.Comment: 10 pages, AmsLatex, to appear in Lett. in Math. Phy