William Harvey revisited

William Harvey's discovery of the circulation of the blood is often described as a product of the Scientific Revolution of the Seventeenth Century. Modern research has, however, shown thatHarvey followed the Aristotelian research tradition and thus tried to reveal the purpose of the organs through examination of various animals. His publication of 1628 has to be read as an argument of natural philosophy, or, more precisely, as a series of linked observations, experiments and philosophical reasonings from which the existence of circulation has to be deduced as a logical consequence. Harvey did not consider experiments as superior to philosophical reasoning nor intended he to create a new system of medicine. He believed in the vitality of the heart and the blood and rejected Francis Bacon's empirism and the mechanistic rationalism of Descartes. Harvey's contribution and originality lied less in his single observations and experiments but in the manner how he linked them with critical reasoning and how he accepted, presented and defended the ensuing radical findings.

[Hyperinsulinemia as a consequence of systemic venous drainage in patients with pancreas transplantation]

To evaluate the metabolic consequences of pancreatic transplantation with systemic venous drainage on beta cell function, we examined insulin and C-peptide responses to arginine and secretin in type I diabetic recipients of pancreas transplantation (n = 16), and normal controls (n = 28). Basal insulin levels were 24 +/- 3 microU/l in pancreas recipients, and 7 +/- 1 microU/l in controls (p less than 0.001). Stimulated insulin levels following arginine (MANOVA, p less than 0.001), and secretin (MANOVA, p less than 0.001) were 1.5 to 3 fold elevated compared to controls. In contrast, integrated C-peptide responses following stimulation with arginine or secretin did not differ significantly between the two groups. We conclude that recipients of pancreas allografts with systemic venous drainage have elevated basal and stimulated insulin levels and that these alterations are primarily due to alterations of first pass hepatic insulin clearance although insulin resistance secondary to immunosuppressive therapy (including prednisone) may also play a contributing role. To avoid hyperinsulinemia and its possible long term adverse consequences, transplantation of pancreas allografts in sites with portal rather than systemic venous drainage may be preferable.

[Intolerance as consequence of hyperreactivity]

Many patients complain about hyperreactivity of the skin or mucosal membranes, whereby rather harmless "triggers" lead to exaggerated reactions like running nose, bronchospasm, urticaria, etc. Most of these hyperreactivities have an underlying inflammation. It is important not to focus only on the triggers, but to look for the agent causing the inflammation and to avoid/treat it: elimination of the cause also eliminates the hyperreactivity. Four examples are presented where this cause--trigger model of hyperreactivity is illustrated (exercise induced asthma, pollen associated food allergy, flare-up reactions in drug allergy and hyperreactivity in chronic urticaria).

Unresolved Problems with the "I", the "A" and the "T": Logical and Psychometric Critique of the Implicit Association Test (IAT)

The Implicit Association Test (IAT) had already gained the status of a prominent assessment procedure before its psychometric properties and underlying task structure were understood. The present critique addresses five major problems that arise when the IAT is used for diagnostic inferences: (1) the asymmetry of causal and diagnostic inferences; (2) the viability of the underlying association model; (3) the lack of a testable model underlying IAT-based inferences; (4) the difficulties of interpreting difference scores; and (5) the susceptibility of the IAT to deliberate faking and strategic processing. Based on a theoretical reflection of these issues, and a comprehensive survey of published IAT studies, it is concluded that a number of uncontrolled factors can produce (or reduce) significant IAT scores independently of the personality attribute that is supposed to be captured by the IAT procedure.

Repeated and predictable patterns of ecotypic differentiation during a biological invasion: lake-stream divergence in parapatric Swiss stickleback

The relative importance of ecological selection and geographical isolation in promoting and constraining genetic and phenotypic differentiation among populations is not always obvious. Interacting with divergent selection, restricted opportunity for gene flow may in some cases be as much a cause as a consequence of adaptation, with the latter being a hallmark of ecologi- cal speciation. Ecological speciation is well studied in parts of the native range of the three-spined stickleback. Here, we study this process in a recently invaded part of its range. Switzerland was colonized within the past 140 years from at least three different colonization events involving differ- ent stickleback lineages. They now occupy diverse habitats, ranging from small streams to the pelagic zone of large lakes. We use replicated systems of parapatric lake and stream populations, some of which trace their origins to different invasive lineages, to ask (i) whether phenotypic divergence occurred among populations inhabiting distinct habitats, (ii) whether trajec- tories of phenotypic divergence follow predictable parallel patterns and (iii) whether gene flow constrains divergent adaptation or vice versa. We find consistent phenotypic divergence between populations occupying distinct habitats. This involves parallel evolution in several traits with known eco- logical relevance in independent evolutionary lineages. Adaptive divergence supersedes homogenizing gene flow even at a small spatial scale. We find evidence that adaptive phenotypic divergence places constraints on gene flow over and above that imposed by geographical distance, signalling the early onset of ecological speciation.