The high spontaneous mutation rate: Is it a health risk?*

The human mutation rate for base substitutions is much higher in males than in females and increases with paternal age. This effect is mainly, if not entirely, due to the large number of cell divisions in the male germ line. The mutation-rate increase is considerably greater than expected if the mutation rate were simply proportional to the number of cell divisions. In contrast, those mutations that are small deletions or rearrangements do not show the paternal age effect. The observed increase with the age of the father in the incidence of children with different dominant mutations is variable, presumably the result of different mixtures of base substitutions and deletions. In Drosophila, the rate of mutations causing minor deleterious effects is estimated to be about one new mutation per zygote. Because of a larger number of genes and a much larger amount of DNA, the human rate is presumably higher. Recently, the Drosophila data have been reanalyzed and the mutation-rate estimate questioned, but I believe that the totality of evidence supports the original conclusion. The most reasonable way in which a species can cope with a high mutation rate is by quasi-truncation selection, whereby a number of mutant genes are eliminated by one “genetic death.”

Outreach to public health professionals: lessons learned from a collaborative Iowa public health project*

In 1995, the National Library of Medicine (NLM) and the Public Health Service (PHS) recommended that special attention be given to the information needs of unaffiliated public health professionals. In response, the National Network of Libraries of Medicine (NN/LM) Greater Midwest Region initiated a collaborative outreach program for public health professionals working in rural east and central Iowa. Five public health agencies were provided equipment, training, and support for accessing the Internet. Key factors in the success of this project were: (1) the role of collaborating agencies in the implementation and ongoing success of information access outreach projects; (2) knowledge of the socio-cultural factors that influence the information-seeking habits of project participants (public health professionals); and (3) management of changing or varying technological infrastructures. Working with their funding, personnel from federal, state, and local governments enhanced the information-seeking skills of public health professionals in rural eastern and central Iowa communities.