UVA-INDUCED AUTOCRINE STIMULATION OF FIBROBLAST-DERIVED COLLAGENASE/MMP-1 BY INTERRELATED LOOPS OFINTERLEUKIN–1 andINTERLEUKIN–6

Abstract— Previous work has shown that fibroblast-derived collagenase/matrix-metalloproteinase-1(MMP–1), responsible for the breakdown of dermal interstitial collagen, was dose-dependently induced in vitro and in vivo by UVA irradiation and this induction was at least partly mediated byinterleukin–6(IL–6). We here provide evidence that UVA-inducedIL–1α andIL–1β play a central role in the induction of the synthesis both ofIL–6 and collagenase/MMP–1. In contrast to the late increase ofIL–1α andIL–1β mRNA levels at 6 h postirradiation, bioactivity ofIL–1 is already detectable at 1 h postirradiation. This early peak ofIL–1 bioactivity appears to be responsible for the induction ofIL–6 synthesis and together withIL–6 lead to an increase of the steady-state mRNA level of collagenase/MMP–1 as deduced from studies usingIL–1α andIL–1β antisense oligonucleotides or neutralizing antibodies againstIL–1α andIL–1β Besides the early posttranslationally controlled release of intracellularIL–1, a latter pretranslationally controlled synthesis and release ofIL–1 perpetuates the UV response. From these data we suggest a UV-induced cytokine network consisting ofIL–1α,IL–1β andIL–6, which via interrelated autocrine loops induce collagenase/MMP–1 and thus may contribute to the loss of interstitial collagen in cutaneous photoaging.     

Ultraviolet B Wavelength Dependence for the Regulation of Two Major Matrix-Metalloproteinases and Their Inhibitor TIMP-1 in Human Dermal Fibroblasts

Abstract— The wavelength dependence for the regulation of two major matrix-metalloproteinases, interstitial collagenase (MMP-1) and stromelysin-1 (MMP-3), and their major inhibitor, tissue inhibitor of metalloproteinases (TIMP-1), was studied in human dermal fibroblasts in vitro. Monochromatic irradiation at 302, 307, 312 and 317 nm with intensities ranging from 20 to 300 J/m² increased MMP-1 and MMP-3 mRNA steady-state levels and the secretion of the corresponding proteins up to 4.4-fold, whereas almost no increase was observed at wavelengths <290 nm. In contrast, the synthesis of TIMP-1 increased only marginally. This unbalance may contribute to the severe connective tissue damage related to photoaging of the skin. The wavelengths responsible for MMP-1 and MMP-3 induction reported here are distinct from the absorption spectrum of DNA and are different from results previously reported in the literature. Importantly, they overlap with wavelengths whose intensity is predicted to increase on the earth's surface upon ozone depletion. Intensities and particular wavelengths used in our studies in vitro can be absorbed readily by fibroblasts within the skin in vivo and, thus, are relevant for risk assessment and development of protective agents.     

Coulomb traction on a penny-shaped crack in a three dimensional piezoelectric body

The axisymmetric problem of a penny-shaped crack embedded in an infinite three-dimensional (3D) piezoelectric body is considered. A general formulation of Coulomb traction on the crack surfaces can be obtained based on thermodynamical considerations of electromechanical systems. Three-dimensional electroelastic solutions are derived by the classical complex potential theory when Coulomb traction is taken into account and the poling direction of piezoelectric body is perpendicular to the crack surfaces. Numerical results show that the magnitude of Coulomb tractions can be large, especially when a large electric field in connection with a small mechanical load is applied. Unlike the traditional traction-free crack model, Coulomb tractions induced by an applied electric field influence the Mode I stress intensity factor for a penny-shaped crack in 3D piezoelectric body. Moreover, compared to the current model, the traditional traction-free crack model always overestimates the effect of the applied electric load on the field intensity factors and energy release rates, which has consequences for 3D piezoelectric fracture mechanics.     

Higher genus minimal surfaces by growing handles out of a catenoid

Starting with the catenoid we derive global Weierstraß representations for minimal surfaces obtained by pushing and pulling handles and by adding ends. The Weierstraß data are obtained from Riemann surfaces given by algebraic functions. Modifying the equations for these curves gives the new surfaces. New and well known examples are treated.     

Indolalkaloide aus dem blätterpilz cortinarius infractus (agaricales)

From fruit bodies of the gilled agaric $\text{Cortinarius infractus}$ three new β-carboline derivatives infractin (1), 6-hydroxyinfractin (2) and infractopicrin (4) have been isolated. 4 is responsible for the bitter taste of the toadstool.     

New nickel(II) diimine complexes and the control of polyethylene microstructure by catalyst design

Starting from differently substituted boronic acids as versatile building block, new "ortho-aryl" alpha-diimine ligands a-h were synthesized in an easy, high-yielding route. Reaction of the complex precursor diacetylacetonato-nickel(II) with a trityl salt, like [CPh3] [B(C6F5)4] or [CPh3] [SbCl6], in the presence of the diimine ligands afford the monocationic, square planar complexes 2a-g in almost quantitative yields. Suitable crystals (2d',e,f,g) were submitted for X-ray diffraction analysis. A geometry model was developed to describe the orientation of ligand fragments around the nickel(II) center that influence the polymer microstructure. At elevated reaction temperature and pressure, and in the presence of hydrogen, 2a-e catalyze the homopolymerization of ethylene to give branched PE products ranging from HD- to LLD-PE grades. The polymerization results indicate the possibility of precise microstructure control depending on the particular complex substitution. Preliminary investigations on material density and mechanical behavior by uniaxial stretching until failure point toward new material properties that can result from the simple ethylene monomer by catalyst design.     

Modelling of interfacial damage and delamination of sprayed coatings with cohesive elements

Delamination of thermally sprayed corrosion protection coatings as a consequence of thermo-mechanical fatigue is investigated. This study focusses on the modelling of interfacial damage initiation and evolution under cyclic loading with the help of a cohesive zone model. The presented model features a slight non-linearity at unloading from the exponential “damage locus” as well as cyclic damage accumulation restricted to (re)loading conditions. Additionally, an endurance limit is introduced indicating the maximum sustainable traction for an infinite number of load cycles. The capability of the model is demonstrated. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)