Yoshifumi Miyakawa

Chromosome aberrations induced by pyrolysates of carbohydrates in Chinese hamster V79 cells

The clastogenic activity of some pyrolysates of carbohydrates was examined in cultured Chinese hamster V79 cells. These pyrolysates include levoglucosan (LG-I), levoglucosenone (LG-II), furfural (FF), 5-(hydroxymethyl)-2-furfural (HMF), glyoxal (GL), methylglyoxal (MGL), 3-deoxy-D-glucosone (DG) and thiazolidine (TZ). LG-I did not induce a significant number of chromosome aberrations at doses up to 8000 micrograms/ml. In contrast, the related compound LG-II induced aberrations and reduced mitosis in a dose-dependent fashion at around 1/2000 of the LG-I doses. Both furan derivatives, FF and HMF, and both glyoxal derivatives, GL and MGL, induced a significant number of chromosome aberrations and a significant lowering of mitotic activity. Among these compounds, FF and MGL showed stronger clastogenic activity than HMF and GL, respectively. DG slightly but positively induced chromosome aberrations. TZ was one of the most potent clastogens among the compounds examined in this study, showing the highest incidence of aberrant cells with many exchanges at doses inducing a significant lowering of mitotic activity. The results of this study indicate the need for a re-evaluation of the thermal decomposition of carbohydrates as a source of genotoxic contaminants.

Basal Cell Tumor, Skin, Mouse

The gross appearance of basal cell tumors may vary considerably. Some are superficial with a granular surface, and others are protuberant nodules. The tumors are usually solitary but are occasionally multiple. Sometimes, the tumor is palpable under the intact skin as a hard nodule. The cut surface is solid and grayish-white.

Mast Cell Tumor, Skin, Mouse

Mast cell tumor is not usually detected with the naked eye, although the tumor may become large and appear as a yellowish-white, opaque, soft mass underneath the epidermis.

Squamous Cell Carcinoma, Skin, Mouse

Most squamous cell carcinomas are seen grossly as solid masses of subepidermal induration. Sometimes, small sessile papillary tumors are histologically recognized as carcinomas. The tumor surface is usually irregular, necrotic, and hemorrhagic with erosions and defects that, in advanced carcinomas, give rise to wide annular ulcerations (Fig.43). The cut surface is whitish to whitish-red, with conspicuous thickening of the skin and prominent subcutaneous growth (Fig. 44). The presence of metastases in regional lymph nodes or in other organs is sometimes observed.