Our study explored the use of translucent larval skin mutants of the silkworm "o06" strain as a possible substitute for the mouse hyperuricemia model in medical studies. The uric acid (UA) contents were measured in the o06 and Gunma200 (control) strains. The hemolymph UA level was analyzed using high-performance liquid chromatography with ultraviolet detection, which allows for high-sensitivity microliter analysis. The hemolymph of the mutants (at the 5^th instar) contained more (4–6 mg/dL) UA than the normal silkworms.

The UA level in hemolymph of the mutant was affected by diet, but the level of allantoin (Alla) was not. UA was excreted as feces, but Alla was not detected in larval urine. This indicates that the activity of uricase was suppressed so that Alla in hemolymph was maintained at a specific level, and UA was not metabolized but accumulated in hemolymph at 3 to 6day-old mutants. Allopurinol and other treatments effectively reduced the UA levels in the mutants. Moreover, the dose response data suggested that our model can be used for research on reagents that reduce blood UA levels in hyperuricemia. Our results indicate that the o06 strain is a potential substitute for the mouse hyperuricemia model in medical research.

Toxicity tests of pharmaceuticals in the eyes are mainly performed in vivo using rabbit eye testing (Draize testing), as indicated in Organization for Economic Cooperation and Development Test Guideline 405. However, in the spirit of protecting animal rights, it is preferable to utilize alternatives to animal testing when performing eye irritant safety tests. Comparison of safety data that had been previously validated through Draize tests with Hansen solubility parameter (HSP) values for test substances made it possible to obtain the potential HSP for the rabbit eyes. Comparison of these rabbit eye HSP values with Modified Maximum Average Scores (MMASs) calculated based on the R_a values that correspond to the distance between the HSP scores for the test substances and the Draize test results indicated that there was a high correlation between the two (r = 0.904, p = 6.10×10⁻¹³). These results suggest that if the HSP scores for new substances can be identified, then a comparison to the potential parameters for eyes that have been identified in this study may facilitate highly accurate predictions of eye irritation.