Cosmosil 5c18 paq

Synthetic single-strand (ss) RNA and ssDNA (8 and 14 mers for each), dissolved in distilled water at a concentration of 1 nmol/μl, were purified in an HP1100 HPLC system using a C₁₈ reversed-phase column (COSMOSIL 5C₁₈-PAQ, 4.6 × 150 mm, 5 μm, Nacalai Tesque). Both ssRNA and ssDNA were separated using a linear gradient 5 to 80% in 40 min of solvent B (25% ACN in 0.075 M TEA-acetic acid (TEAA) buffer, pH 7.0) in solvent A (0.1 M TEAA buffer, pH 7.0) at a flow rate of 1 ml/min. The purified ssRNA (8-mer and 14-mer) and ssDNA (8-mer and 14-mer) were dissolved in 10 mM NH₄OAc pH 7.0, and then, equimolar mixtures, i.e., RNA/DNA hybrids, were prepared on the basis of the concentrations obtained from the absorption at 260 nm.

WT mice were randomly divided into the control group or the G-Hes group. Before starting the experiment, the G-Hes group was treated with G-Hes (500 mg/kg body weight) in saline solution by a single oral administration for 2 h, while the control group was treated with saline solution. After 2 h, all mice were treated with the uricase inhibitor, potassium oxonate (250 mg/kg i.p., FUJIFILM Wako)^{55 (link)} in saline solution. Blood samples (100 μl each) were collected at 0, 0.5, 1, and 2 h after potassium oxonate injection by cutting the tail tip. Prior to G-Hes treatment, blood was also collected as the basal urate level. Plasma was obtained by centrifugation at 3000 rpm, for 10 min, and at 4 °C. Plasma urate levels were determined by high-performance liquid chromatography (HPLC) using a Cosmosil 5C₁₈-PAQ (4.6 × 250 mm; Nacalai Tesque, Kyoto, Japan) with an isocratic elution of 20 mM phosphate buffer (pH 2.5) at a flow rate of 0.5 ml/min, a temperature of 30 °C, and a monitored wavelength of 290 nm.