The Krüppel‐like factors (KLFs) comprise a family of evolutionarily conserved zinc finger transcription factors that regulate numerous biological processes including proliferation, differentiation, development and apoptosis. KLF4 and KLF5 are two closely related members of this family and are both highly expressed in epithelial tissues. In the intestinal epithelium, KLF4 is expressed in terminally differentiated epithelial cells at the villus borders of the mucosa and inhibits cell growth, while KLF5 is expressed in proliferating epithelial cells at the base of the intestinal (...) crypts and promotes cell growth. KLF4 and KLF5 respond to a myriad of external stress stimuli and are likely involved in restoring cellular homeostasis following exposure to stressors. Confirming their importance in maintaining tissue integrity, KLF4 and KLF5 are both dysregulated in various types of cancer. Here we review the recent advances in defining the physiological and pathobiological roles of KLF4 and KLF5, focusing on their functions in the intestinal epithelium. BioEssays 29:549–557, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

SummaryThe germs of future development, contained in Aristotle's logical works, are indicated, and their influence on the later evolution of logic is explained.The history of symbolic logic since Boole's Mathematical analysis and De Morgan's Formal logic, both of which were published in 1847, is divided into four approximately subsequent phases, viz.:1. algebra of logic; this phase is characterized by Boole's work;2. logical foundation of mathematics; this phase is characterized by Frege's, Peano's and Russell's work, by the discovery of the antonomies (...) of logic and set theory, by the Couturat‐Poincaré debate and by the rise of Brouwer's intuitionism;3. intuitive metamathematics, concentrating in Hilbert's attempts towards a consistency proof for classical analysis; the discovery of Gödel's theorem necessitated a change of policy;4. axiomatic methodology, deriving from Hilbert's metamathematics and culminating so far in Tarski's semantics. — E. W. B. (shrink)

The principles of the 3Rs—replacement, refinement, and reduction—strongly shape discussion of methods for performing more humane animal research and the regulation of this contested area of technoscience. This special issue looks back to the origins of the 3Rs principles through five papers that explore how it is enacted and challenged in practice and that develop critical considerations about its future. Three themes connect the papers in this special issue. These are the multiplicity of roles enacted by those who use and (...) care for animals in research, the distribution of “feelings that matter” across species and spaces of laboratory animal practice, and the growing importance of “cultures of care” in animal research. (shrink)

RésuméSelon Descartes, la force démonstrative d'une argumentation peut résulter ou bien de l'application des règles universelles de la logique ou bien d'une intuition particulière. Cette doctrine permet d'éviter le reproche de circularité qui est souvent fait à l'égard de certaines argumentations épistémologiques. D'autre part, elle implique le rejet de la méthode du contre‐exemple. L'acception de certaines argumentations en vertu d'une intuition particulière ne crée pas une situation définitive; elle constitue une phase dans la genèse de ce que Bernays a caractérisé (...) comme une évidence acquise.ZusammenfassungNach Descartes kann die Beweiskraft einer Argumentation entweder von der Anwendung der allgemeingültigen Regeln der Logik oder von einer besonderen Anschauung herrühren. Diese Ansicht erlaubt uns, dem Einwand der Zirkelhaftigkeit zu entgehen, welcher öfters gegen gewisse erkenntnistheoretische Argumentationen erhoben wird. Sie erfordert anderseits den Verzicht auf die Methode der Gegenbeispiele. Die Hinnahme gewisser Argumentationen auf Grund einer besonderen Anschauung schafft niemals eine bleibende Situation; sie bildet eine Phase im Zustandekommen dessen, was Bernays als eine erworbene Evidenz charakterisiert hat.According to Descartes, the demonstrative power of an argumentation may result either from the application of the universal rules of logic or from a particular intuition. This doctrine permits us to avoid the reproach of circularity which is often raised as an objection to certain argumentations in epistemology. On the other hand, it implies the rejection of the method of the counter‐example. The acceptance of certain argumentations based on a particular intuition never creates a permanent situation; it rather constitutes a stage in the genesis of what Bernays has characterized as an évidence acquise. (shrink)

Professor P. Bernays has kindly drawn my attention to the fact that the assignment of Godel numbers to formulas described on page 295 of volume I of this Journal, is not correct. Under this assignment, different formulas may obtain the same Godel number and therefore the argument given on page 296 under (i) is not cogent. The correct assignment would give, for the formula considered as an example, the Godel number 28. 320. 514. 782 The correction to be made on (...) page 294, L 20 is obvious. (shrink)