No abstract

Loxoscelism (bites by spiders of the genus Loxosceles) is the only proven arachnological cause of dermonecrosis. Although Loxosceles spiders can be found worldwide, their distribution is heavily concentrated in the Western Hemisphere, particularly the tropical urban regions of South America. Although Loxosceles bites are usually mild, they may ulcerate or cause more severe, systemic reactions. These injuries mostly are due to sphingomyelinase D in the spider venom. There is no proven effective therapy for Loxosceles bites, although many therapies are reported in the literature.

Malignant melanoma presents a substantial clinical challenge. Current diagnostic methods are limited in their ability to diagnose early disease and accurately predict individual risk of disease progression and outcome. The lack of adequate approaches to properly define disease subgroups precludes rational treatment design and selection. Better tools are urgently needed to provide more accurate

No abstract

Summit metabolic rate (M sum , maximum cold-induced metabolic rate) is positively correlated with cold tolerance in birds, suggesting that high M sum is important for residency in cold climates. However, the phylogenetic distribution of high M sum among birds and the impact of its evolution on current distributions are not well understood. Two potential adaptive hypotheses might explain the phylogenetic distribution of high M sum among birds. The cold adaptation hypothesis contends that species wintering in cold climates should have higher M sum than species wintering in warmer climates. The flight adaptation hypothesis suggests that volant birds might be capable of generating high M sum as a byproduct of their muscular capacity for flight; thus, variation in M sum should be associated with capacity for sustained flight, one indicator of which is migration. We collected M sum data from the literature for 44 bird species and conducted both conventional and phylogenetically informed statistical analyses to examine the predictors of M sum variation. Significant phylogenetic signal was present for log body mass, log mass-adjusted M sum , and average temperature in the winter range. In multiple regression models, log body mass, winter temperature, and clade were significant predictors of log M sum . These results are consistent with a role for climate in determining M sum in birds, but also indicate that phylogenetic signal remains even after accounting for associations indicative of adaptation to winter temperature. Migratory strategy was never a significant predictor of log M sum in multiple regressions, a result that is not consistent with the flight adaptation hypothesis. The interplay between physiology and climate can have important consequences for animal distributions. Cold climates require high thermoregulatory energy expenditures for endothermic vertebrates, particularly for small species with high surface area to volume ratios and limited insulatory capacities (Schmidt-Nielsen 1984). Basal (BMR) and maximal cold-induced (=summit metabolism, M sum ) metabolic rates are correlated with climate in mammals, with higher metabolic rates associated with the higher thermoregulatory demands of cold climates (Bozinovic and Rosenmann 1989;Rezende et al. 2004). A similar correlation of BMR with climate also occurs in birds (Weathers 1979), but such correlations of M sum with climate for birds have not been established, primarily because measurements of M sum have mostly been restricted to cold-climate species. The role of winter temperature and the interplay between temperature and metabolism in affecting bird distributions are unclear. Root (1988) found that 1 8 4