Motome Terao

Nitric oxide participates in cataract development in selenite-treated rats

Purpose. The role of nitric oxide in the development of selenite-induced cataracts in rats was examined using nitric oxide synthase (NOS) inhibitors. Methods. Subcutaneous injection of sodium selenite was used to induce cataracts in rats, with or without pretreatment with NOS inhibitors. The anterior eye segment analysis system (EAS-1000, Nidek) was used to measure lens opacity. The glutathione content of the lenses was determined by an HPLC method and the Ca 2+ content by atomic absorption spectrometry. Nitrite, a stable metabolite of nitric oxide, was determined fluorometrically. NADPH-diaphorase activity staining and Western blot analysis were used to determine NOS levels. Results. Administration of the NOS inhibitor, N G -nitro-l-arginine methyl ester (l-NAME), inhibited lens opacification in selenite-treated rats. N G -nitro-d-arginine methyl ester, an inactive enantiomer of l-NAME, had no effect. Aminoguanidine, another NOS inhibitor, also inhibited the development of cataracts in a dose-dependent manner. On the other hand, l-arginine, a substrate of NOS, accelerated the development of cataracts. Although the opacification of the lenses was apparent approximately 3 days after selenite injection, the nitrite level was increased within one day. In addition, NOS was induced in the eye within one day of selenite injection. Conclusions. The present study demonstrated that NOS inhibitors prevented the development of cataracts in selenite-treated rats. The results also suggest that nitric oxide had an important role in the development of selenite-induced cataracts.

Selective inhibition by ketanserin and spiroperidol of 5-HT-induced myometrial contraction

The inhibitory effects of ketanserin and spiroperidol (a neuroleptic drug) on the contractile response of isolated rat uterus to serotonin (5-HT) were investigated. Ketanserin caused non-competitive inhibition of the contractile response to 5-HT and showed more selective inhibition than the other 5-HT antagonists tested. The inhibitory effect of spiroperidol was comparable with the effects of classical 5-HT antagonists. These results suggest that ketanserin and spiroperidol selectively inhibit the contractile response of isolated rat uterus to 5-HT.

Fluorimetric determination of reducing carbohydrates with malonamide

Abstract Samples are heated for 90 min with malonamide in carbonate buffer (pH 9.2) for measurement at 383 nm (excitation)/425 nm (emission). For D-glucose, relative standard deviations are 1–3% at the 10-6–10-9 mol level. Relative fluorescence intensities are reported for 36 carbohydrates.

Preventive Effect of Diethyldithiocarbamate on Selenite-Induced Opacity in Cultured Rat Lenses

Increasing evidence suggests the involvement of reactive oxygen species in the development of cataracts. In this study, we investigated the preventive effect of diethyldithiocarbamate (DDC) on the selenite-induced opacification of cultured rat lenses. Lens opacity was produced by incubation with 0.2 mM selenite for 24 h, which resulted in an increase in selenium content in the cultured lenses. The increase in selenium content and the onset of opacification and lens membrane damage were inhibited by preincubation with DDC. It is reasonable to assume that DDC contributed to anticataract ability. In addition, selenite resulted in a significant decrease in glutathione and protein thiol content and an increase in lipid peroxidation levels in the lenses. These alterations were also depressed by DDC, suggesting a contribution of an antioxidative effect by DDC in the inhibition of lens opacification. At the same lens selenium content, DDC treatment inhibited opacification and lipid peroxide. In conclusion, we propose that the antioxidative properties of DDC play a major role in its contribution to the anticataract effect.

Periodate oxidation of carbohydrates

Abstract An isotachophoresis method was devised, which allows rapid, simultaneous determination of 5–100 nmole samples of iodate, periodate, and fomate ions with coefficients of variation less than 3.5%, and teh usefulness of this method for the study of periodate oxidation of carbohydrates was demonstrated. The component aldehydes in the dialdehyde fragments formed on periodate oxidation of oligoglycosides were also determined simultaneously by isotachophoresis of the carboxylates derived thereof by subsequent bromine oxidation and hydrolysis.