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We prove a representation theorem for Boolean contact algebras which implies that the axioms for the Region Connection Calculus [23] (RCC) are complete for the class of subalgebras of the algebras of regular closed sets of weakly regular connected T 1 spaces.

Background/Aims: Urocortin II (UcnII) is a neuropeptide that binds with high affinity to the corticotropinreleasing hormone receptor 2 (CRHR2) in peripheral tissues. UcnII is synthesised in the intestine, but its role in human intestinal inflammation is largely unknown. Methods: Responses of human colonic epithelial cells expressing CRHR2 to stimulation by UcnII were measured using ELISA, western blot analysis, real-time reverse transcription-PCR (RT-PCR) and interleukin (IL)8 promoter activity. Expression levels of CRHR2 and UcnII in human colitis were determined by immunofluorescence and real-time RT-PCR in mucosal biopsies from patients with Crohn's and ulcerative colitis, and in human intestinal xenografts after exposure to Clostridium difficile toxin A. Results: It is reported here that expression of CRHR2 mRNA and protein in human colonic epithelial cells (HT-29) are increased by exposure to C difficile toxin A or tumour necrosis factor (TNF)a. Stimulation of nontransformed NCM460 colonocytes overexpressing CRHR2a receptor with UcnII resulted in a time-and concentration-dependent increase in IL8 production. UcnII stimulation also led to activation of nuclear factorkB (NF-kB) and mitogen-acivated protein (MAP) kinase in these cells, as evidenced by degradation of IkBa and phosphorylation of the p65 subunit of NF-kB and extracellularly regulated kinase (ERK) 1/2. Furthermore, expression of UcnII and CRHR2 mRNA was increased in mucosal samples of patients with inflammatory bowel disease, and after exposure of human intestinal xenografts to C difficile toxin A. Conclusions: These results suggest that UcnII has pro-inflammatory effects in human intestinal cells via the CRHR2a receptor and may play an important role in the pathophysiology of colitis in humans.

A very sensitive dielectric resonator technique is employed to measure loss tangent tan δ and relative permittivity εr of lanthanum aluminate (LaAlO3) single crystals at 4–300 K and 4–12 GHz. A variety of single crystals grown by different techniques and purchased from different suppliers are considered. For T>150 K the loss tangent tan δ is almost sample independent with linear frequency dependence and monotonous temperature variation from 8×10−6 at 300 K to 2.5×10−6 at 150 K and 4.1 GHz. In this temperature range the experimental data are explained by a model based on lifetime broadened two-phonon difference processes. The loss tangent below 150 K is characterized by a peak in tan δ(T) at about 70 K. The height of this peak is frequency and strongly sample dependent. This leads to a variation of the loss tangent from 10−6 to 1.5×10−5 at 77 K and 8.6 GHz, the lowest values are generally achieved with Verneuil grown crystals and approach the intrinsic lower limit predicted by the phonon model. The peak is explained by defect dipole relaxation (local motions of ions). The activation energy of the relaxation process is determined from the measured data to be 31 meV. This low value indicates that the defect dipoles are associated with interstitials, possibly impurities in interstitial positions. Considering absorption due to phonons and due to defect dipole relaxation the loss tangent is calculated for a wide frequency range.