No abstract

Analogs of the potent fecal mutagen fecapentaene-12 have been prepared and tested both for mutagenicity and for their ability to serve as biological precursors of 1. It was found that mutagenicity in three different Salmonella tester strains TA96, TA100, and TA104, decreased rapidly as the number of conjugated double bonds was reduced. The aldehyde 8, analogous to the hydrolysis product of 1, showed only low mutagenicity, even in the aldehyde-sensitive strain TA104. None of the polyenes prepared was able to function as a direct biological precursor of 1 under the conditions employed.

In 454 medical and dental students who were vaccinated against hepatitis B by means of a low dose (0.1 ml) of serum‐derived vaccine, seroconversion rates of 27%, 70% and 89% were obtained after the first, second and third doses, respectively. These figures are comparable with the results that have been reported for the conventional intramuscular schedule, as were the final antibody titres. A fourth intradermal dose boosted the percentage of students who were protected from 82% to 87%. There was a significant variation in the response to different batches of vaccine. This study shows that the low‐dose intradermal method is practicable and effective and can be used to achieve great economy in hepatitis B vaccination programmes. The possibility of adding hepatitis B to the present formula of triple antigen should be investigated as a way of extending hepatitis B vaccination to all infants in our community.