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)

Professor P. Bernays has kindly drawn my attention to the tact that the assignment of Gödel 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 Gödel 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 Gödel number 23. 329. 514. 732 The correction to be made on (...) page 294, l. 20 is obvious. (shrink)