2-Segal sets and the Waldhausen construction

It is known by results of Dyckerhoff–Kapranov and of Gálvez-Carrillo–Kock–Tonks that the output of the Waldhausen S • -construction has a unital 2-Segal structure. Here, we prove that a certain S • -functor defines an equivalence between the category of augmented stable double categories and the category of unital 2-Segal sets. The inverse equivalence is described explicitly by a path construction. We illustrate the equivalence for the known examples of partial monoids, cobordism categories with genus constraints and graph coalgebras

IL-13R alpha 2 reverses the effects of IL-13 and IL-4 on bronchial reactivity and acetylcholine-induced Ca2+ signaling

Background: The interleukins IL-4 and IL-13 play a key role in the pathophysiology of asthma. The interleukin receptor IL-13R alpha 2 is believed to act as a decoy receptor, but until now, the functional significance of IL-13R alpha 2 remains vague. Methods: Bronchial reactivity was quantified in murine lung slices by digital video microscopy and acetylcholine (ACH)-induced Ca2+ signaling was measured in human airway smooth muscle cells (ASMC) using fluorescence microscopy. Results: IL-4 or IL-13 up to 50 ng/ml induced bronchial hyperreactivity. But after incubation with 100 ng/ml this effect was lost and bronchial responsiveness was again comparable to the control level. The effects of IL-4 and IL-13 on bronchial reactivity were paralleled by the effects on ASMC proliferation. Fifty nanograms per milliliter of IL-4 and IL-13 increased the Ca2+ response of human ASMC to ACH. At 100 ng/ml, however, the effects of the cytokines on the Ca2+ response were no longer evident. The expression of IL-13R alpha 2 increased with increasing concentrations of IL-4 or IL-13, reaching its maximum at 100 ng/ml. Blocking IL-13R alpha 2, the loss of the effect of IL-4 and IL-13 at 100 ng/ml on human ASMC proliferation and the ACH-induced Ca2+ response were no longer present. Conclusions: IL-4 and IL-13 induce bronchial hyperreactivity by changing the Ca2+ homeostasis of ASMC. These effects are counteracted by IL-13R alpha 2. The biological significance of IL-13R alpha 2 might be a protective function by regulating IL-13- and IL-4-mediated signal transduction and thereby limiting pathological alterations in Th2-mediated inflammatory diseases. Copyright (c) 2007 S. Karger AG, Basel

Flow Equation for Supersymmetric Quantum Mechanics

We study supersymmetric quantum mechanics with the functional RG formulated in terms of an exact and manifestly off-shell supersymmetric flow equation for the effective action. We solve the flow equation nonperturbatively in a systematic super-covariant derivative expansion and concentrate on systems with unbroken supersymmetry. Already at next-to-leading order, the energy of the first excited state for convex potentials is accurately determined within a 1% error for a wide range of couplings including deeply nonperturbative regimes.Comment: 24 pages, 8 figures, references added, typos correcte

Reduced expression of Bax in small cell lung cancer cells is not sufficient to induce cisplatin-resistance

Resistance to cisplatin in the course of chemotherapy contributes to the poor prognosis of small cell lung cancer (SCLC). B cell lymphoma-2 is the founding member of a large family of proteins that either promote or inhibit apoptosis. We aimed at investigating if the pro-apoptotic members Bad, Bax, Bim and Bid are involved in cisplatin-resistance

Nucleosomes indicate the in vitro radiosensitivity of irradiated bronchoepithelial and lung cancer cells

Nucleosomes, which are typical cell death products, are elevated in the serum of cancer patients and are known to rapidly increase during radiotherapy. As both normal and malignant cells are damaged by irradiation, we investigated to which extent both cell types contribute to the release of nucleosomes. We cultured monolayers of normal bronchoepithelial lung cells (BEAS-2B, n = 18) and epithelial lung cancer cells (EPLC, n = 18), exposed them to various radiation doses (0, 10 and 30 Gy) and observed them for 5 days. Culture medium was changed every 24 h. Subsequently, nucleosomes were determined in the supernatant by the Cell Death Detection-ELISA(plus) ( Roche Diagnostics). Additionally, the cell number was estimated after harvesting the cells in a second preparation. After 5 days, the cell number of BEAS-2B cultures in the irradiated groups (10 Gy: median 0.03 x 10(6) cells/culture, range 0.02-0.08 x 10(6) cells/culture; 30 Gy: median 0.08 x 10(6) cells/culture, range 0.02-0.14 x 10(6) cells/culture) decreased significantly (10 Gy: p = 0.005; 30 Gy p = 0.005; Wilcoxon test) compared to the non-irradiated control group (median 4.81 x 10(6) cells/culture, range 1.50-9.54 x 10(6) cells/culture). Consistently, nucleosomes remained low in the supernatant of nonirradiated BEAS-2B. However, at 10 Gy, BEAS-2B showed a considerably increasing release of nucleosomes, with a maximum at 72 h ( before irradiation: 0.24 x 10(3) arbitrary units, AU, range 0.13-4.09 x 10(3) AU, and after 72 h: 1.94 x 10(3) AU, range 0.11-5.70 x 10(3) AU). At 30 Gy, the release was even stronger, reaching the maximum earlier (at 48 h, 11.09 x 10(3) AU, range 6.89-18.28 x 10(3) AU). In non-irradiated EPLC, nucleosomes constantly increased slightly. At 10 Gy, we observed a considerably higher release of nucleosomes in EPLC, with a maximum at 72 h (before irradiation: 2.79 x 10(3) AU, range 2.42-3.80 x 10(3) AU, and after 72 h: 7.16 x 10(3) AU, range 4.30-16.20 x 10(3) AU), which was more than 3.5 times higher than in BEAS-2B. At 30 Gy, the maximum (6.22 x 10(3) AU, range 5.13-9.71 x 10(3) AU) was observed already after 24 h. These results indicate that normal bronchoepithelial and malignant lung cancer cells contribute to the release of nucleosomes during irradiation in a dose-and time-dependent manner with cancer cells having a stronger impact at low doses. Copyright (C) 2004 S. Karger AG, Basel

Genotoxicity of nitroso compounds and sodium dichromate in a model combining organ cultures of human nasal epithelia and the comet assay

Genotoxic effects of xenobiotics are a possible step in tumor initiation in the mucosa of the upper aerodigestive tract. Using the comet assay, detecting genotoxicity in human tissue has been restricted to single incubations in vitro, but in vivo most xenobiotics harm their target in a repetitive or chronic manner. Therefore, we propose a model, which provides repetitive incubations in human upper aerodigestive tract mucosa cultures. Samples of human inferior nasal turbinate mucosa (n = 25) were cultured according to a modified version of a technique originally described by Steinsvag. On day 1 fresh samples and on days 7, 9 and 11 organ cultures were incubated with N-nitrosodiethylamine (NDEA), sodium dichromate (Na2Cr2O7) and N'-methyl-N-nitro-N-nitrosoguanidine(MNNG). Mucosa samples and organ cultures, respectively, underwent a modified comet assay on days 1, 7 and 11. Genotoxicity could be shown for NDEA, Na2Cr2O7 and MNNG on days 1, 7 and 11. Duration of tissue culture and repetitive incubations did not significantly influence the results for NDEA. Nevertheless, Na2Cr2O7 and MNNG caused higher genotoxic effects on cultures subjected to the comet assay on day 11. This model may help to assess genotoxic hazards posed by environ mental pollutants that have a cumulative character in repetitive or chronic exposure in vivo. Copyright (C) 2001 S. Karger AG, Basel