Identity cards for patients infected with HIV?

Dr A C Srivastava has written to us to describe a case that raises the suggestion that people infected with the human immuno-deficiency virus (HIV) should carry identity cards. We asked two physicians, a general practitioner working with patients with the acquired immune deficiency syndrome (AIDS), and a general practitioner with a special interest in medical ethics to respond to the broad issues raised by Dr Srivastava''s letter.     

Strongyloidiasis in Canadian Far East war veterans

A survey was done of Canadians who had been interned by the Japanese during World War II to assess the prevalence of latent infection with Strongyloides stercoralis in this group. Packages containing three mail-in kits and a questionnaire were sent to 992 men, 694 (70%) of whom responded. Larvae were found in the stool specimens of four of the respondents. Examination of stool specimens after formalin-ether concentration was the most successful method of detecting Strongyloides larvae. The Baermann concentration technique yielded negative results in all four men. Three of the four cases of strongyloidiasis were detected after sampling of three fecal specimens. In the fourth case additional specimens were requested on the basis of data derived from the questionnaire. The most frequently cited clinical manifestations were abdominal pain, weight loss, diarrhea and rashes.     

Within- and between-species patterns of allocation to pulp and seed in vertebrate dispersed plants

Non-uniform scaling of pulp and seed mass has been shown to alter dispersal probabilities in vertebrate dispersed species. Since dispersal in tropical forests is strongly linked to establishment success, processes determining allocation to pulp and seed are likely to impact on parental fitness, and therefore should be under the control of natural selection. In this study I examine size-dependent dry mass allocation pattern to pulp and seed mass both among and within 20 fruit-producing plant species of tropical rainforest in northeast Queensland, Australia. Reduced major axis analyses using mean values for each species showed significant isometry, indicating that at the community level, plant species that employ vertebrates as a means of seed dispersal tend to allocate an equivalent mean relative proportion of the overall dry weight investment in fruit to pulp. However, identical analyses conducted for each species separately revealed that relationships within individual species do not reflect the inter-specific relationship. These results imply two influences on dry mass allocation to fruit components; the first (within-species allometry) determines how fruits vary within each species. The second (between-species allometry) operates in a similar manner across species to produce equal ratios of mean pulp and seed mass independent of within-species allometries.     

What Can We Learn from the Evolution of Protein-Ligand Interactions to Aid the Design of New Therapeutics?

Efforts to increase affinity in the design of new therapeutic molecules have tended to lead to greater lipophilicity, a factor that is generally agreed to be contributing to the low success rate of new drug candidates. Our aim is to provide a structural perspective to the study of lipophilic efficiency and to compare molecular interactions created over evolutionary time with those designed by humans. We show that natural complexes typically engage in more polar contacts than synthetic molecules bound to proteins. The synthetic molecules also have a higher proportion of unmatched heteroatoms at the interface than the natural sets. These observations suggest that there are lessons to be learnt from Nature, which could help us to improve the characteristics of man-made molecules. In particular, it is possible to increase the density of polar contacts without increasing lipophilicity and this is best achieved early in discovery while molecules remain relatively small.