Induction of intracranial tumors in mice by human adenovirus type 12. II. Enhancement by N,N'-dimethylnitrosourea

Newborn mice of C3Hf/Bi (Zb) strain were divided into three groups and injected, intracranially with adenovirus type 12 alone, subcutaneously with 20 mgjkg of N, N'-dimethylnitrosourea following intracranial inoculation of adenovirus type 12, and subcutaneously with 20 mgjkg of N, N'-dimethylnitrosourea alone at 10 days of age, respectively. With adenovirus type 12 alone, intracranial tumors were induced in 12 out of the 25 effective animals. With N, N'-dimethylnitrosourea following adenovirus type 12, intracranial tumors were produced in 19 out of the 21 effective animals and these tumors were virus-induced ones. With N, N'-dimethylnitrosourea alone, no intracranial tumors were induced. In control mice, administered subcutaneously with 20 mgjkg of N, N'.dimethylnitrosourea within 24 hr after birth, necrosis of the external granular cells and hypoplasia of the granular layer of the cerebellum was observed.