The gut protozoan parasite, Giardia duodenalis, is the best characterized example of the most ancient eukaryotes, which are anaerobic and appear to be primitively amitochondrial. Apart from its obvious medical importance, Giardia is fascinating in its own right. Its prokaryotic-like anaerobic metabolism renders it selectively sensitive to some bacterial drugs, especially the nitroimidazoles, which are activated to form toxic radicals. Other features, including an enzyme that reduces oxygen directly to water, cysteine as the keeper of redox balance, a plasmid, and (...) toxin-like genes are also distinctly prokaryotic-like. But, unlike prokaryotes, Giardia has a sophisticated, highly developed cytoskeleton, bounded nuclei, linear chromosomes capped with telomeric repeats, and telomere positional regulation of gene expression. BioEssays 20:256–263, 1998.© 1998 John Wiley & Sons, Inc. (shrink)

A comprehensive study of the ethics of killing in cases in which the metaphysical or moral status of the individual killed is uncertain or controversial. Among those beings whose status is questionable or marginal in this way are human embryos and fetuses, newborn infants, animals, anencephalic infants, human beings with severe congenital and cognitive impairments, and human beings who have become severely demented or irreversibly comatose. In an effort to understand the moral status of these beings, this book develops and (...) defends distinctive accounts of the nature of personal identity, the evaluation of death, and the wrongness of killing. The central metaphysical claim of the book is that we are neither nonmaterial souls nor human organisms but are instead embodied minds. In ethical theory, one of the central claims is that the morality of killing is not unitary; rather, the principles that determine the morality of killing in marginal cases are different from those that govern the killing of persons who are self‐conscious and rational. Another important theme is that killing in marginal cases should be evaluated in terms of the impact it would have on the victim at the time rather than on the value of the victim's life as a whole. What primarily matters is how killing would affect that which would be rational for the victim to care about at the time of death. By appealing to various foundational claims about identity, death, and the morality of killing, this book yields novel conclusions about such issues as abortion, prenatal injury, infanticide, the killing of animals, the significance of brain death, the termination of life support in cases of persistent vegetative state, the use of anencephalic infants as sources of organs for transplantation, euthanasia, assisted suicide, and advance directives in cases of dementia. In particular, the book defends the moral permissibility of abortion, infanticide, and euthanasia in certain cases and argues that brain death is not the appropriate criterion of death either for a person or a human organism. (shrink)