[Use of alcohol and narcotics among Danish adolescents in the 1980's]. / Alkohol-og narkotikabrug blandt danske unge i 1980'erne.

A review is presented of the results of epidemiological investigations from 1980 to 1988 concerning the use of alcohol and narcotics among adolescents in Denmark. The material includes ten anonymous questionnaire investigations in all of which school pupils participated and a qualitative interview investigation. Comparison of the age-specific prevalence rates reveals that the use of alcohol and narcotics increases with age and that the intake of alcohol is slightly higher in boys than in girls. The majority of the adolescents drink mainly at weekends and in connection with social events. The use of hash is greatest among boys and the average age for commencing is slightly higher than for alcohol. Apart from hash, the employment of narcotics is low in school pupils. Although approximately 24,000 adolescents were questioned, the investigations together provide an uncertain picture of the habits as these are not representative for Danish adolescents. It is not possible to indicate genuine risk groups. It is concluded that initiatives for prophylactic efforts do not have any basis for action. Repeated national representative questionnaire investigations are proposed supplemented by qualitative interviews with particularly selected adolescents and local key-persons.

Increasing melanoma incidence: putatively explainable by retrotransposons. Experimental contributions of the xiphophorine Gordon-Kosswig melanoma system.

The worldwide accelerating increase of neoplasia in humans is difficult to explain. We use the Xiphophorus tumor model to approach this problem by melanoma provocation with X-rays. Melanoma develops following inappropriate expression of x-erb B-conducted developmental genes and their controllers. These oncodeterminants are inherited according to Mendelian rules. We detected a new type of oncodeterminants that, following a single treatment of embryos with X-rays, generates a self-generating non-Mendelian melanoma transmission and accelerating increase of its incidence in succeeding generations (e.g., 0-->18-->33-->52%). To localize these oncodeterminants, we crossed nonirradiated fish having half of their chromosomes irradiated with nonirradiated fish having none of, half of, or all of their chromosomes irradiated. Because tumor rate and expression in the following generations correspond to the rates of treated chromosomes, we conclude that the new oncodeterminants are distributed over the chromosomes of the fish, where they may increase in the changing generations. By means of xiphophorine-specific retroviral DNA, we isolated two retrotransposons that behave hereditarily like the new transgenerational oncodeterminants. Sequence analysis revealed three ORFs flanked by LTRs containing motives of regulatory sequences typical for known retroviral and retrotransposal LTRs. Pol- and env-resembling sequences are lacking. Southern and in situ hybridization showed their multiple and repetitive nature distributed throughout the chromosomes and indications for their capability to increase in number without further treatment. Their transcripts are expressed in concert with those of most of the other known xiphophorine tumor determinants. Their expression is extremely high in cell cultures from tumorous embryos derived from ancestors treated as embryos with X-rays.