Collagens - structure, function and biosynthesis.

The extracellular matrix represents a complex alloy of variable members of diverse protein families defining structural integrity and various physiological functions. The most abundant family is the collagens with more than 20 different collagen types identified so far. Collagens are centrally involved in the formation of fibrillar and microfibrillar networks of the extracellular matrix, basement membranes as well as other structures of the extracellular matrix. This review focuses on the distribution and function of various collagen types in different tissues. It introduces their basic structural subunits and points out major steps in the biosynthesis and supramolecular processing of fibrillar collagens as prototypical members of this protein family. A final outlook indicates the importance of different collagen types not only for the understanding of collagen-related diseases, but also as a basis for the therapeutical use of members of this protein family discussed in other chapters of this issue

Large-scale albuminuria screen for nephropathy models in chemically induced mouse mutants

Background/Aim: Phenotype-driven screening of a great pool of randomly mutant mice and subsequent selection of animals showing symptoms equivalent to human kidney diseases may result in the generation of novel suitable models for the study of the pathomechanisms and the identification of genes involved in kidney dysfunction. Methods: We carried out a large-scale analysis of ethylnitrosourea (ENU)-induced mouse mutants for albuminuria by using qualitative SDS-polyacrylamide gel electrophoresis. Results: The primary albuminuria screen preceded the comprehensive phenotypic mutation analysis in a part of the mice of the Munich ENU project to avoid loss of mutant animals as a consequence of prolonged suffering from severe nephropathy. The primary screen detected six confirmed phenotypic variants in 2,011 G1 animals screened for dominant mutations and no variant in 48 G3 pedigrees screened for recessive mutations. Further breeding experiments resulted in two lines showing a low phenotypic penetrance of albuminuria. The secondary albuminuria screen was carried out in mutant lines which were established in the Munich ENU project without preceding primary albuminuria analysis. Two lines showing increased plasma urea levels were chosen to clarify if severe kidney lesions are involved in the abnormal phenotype. This analysis revealed severe albuminuria in mice which are affected by a recessive mutation leading to increased plasma urea and cholesterol levels. Conclusion: Thus, the phenotypic selection of ENU-induced mutants according to the parameter proteinuria in principle demonstrates the feasibility to identify nephropathy phenotypes in ENU-mutagenized mice. Copyright (C) 2005 S. Karger AG, Basel

A note on the Cops & Robber game on graphs embedded in non-orientable surfaces

The Cops and Robber game is played on undirected finite graphs. A number of cops and one robber are positioned on vertices and take turns in sliding along edges. The cops win if they can catch the robber. The minimum number of cops needed to win on a graph is called its cop number. It is known that the cop number of a graph embedded on a surface $X$ of genus $g$ is at most $3g/2 + 3$, if $X$ is orientable (Schroeder 2004), and at most $2g+1$, otherwise (Nowakowski & Schroeder 1997). We improve the bounds for non-orientable surfaces by reduction to the orientable case using covering spaces. As corollaries, using Schroeder's results, we obtain the following: the maximum cop number of graphs embeddable in the projective plane is 3; the cop number of graphs embeddable in the Klein Bottle is at most 4, and an upper bound is $3g/2 + 3/2$ for all other $g$.Comment: 5 pages, 1 figur

Organized Current Patterns in Disordered Conductors

We present a general theory of current deviations in straight current carrying wires with random imperfections, which quantitatively explains the recent observations of organized patterns of magnetic field corrugations above micron-scale evaporated wires. These patterns originate from the most efficient electron scattering by Fourier components of the wire imperfections with wavefronts along the $\pm 45^{\circ}$ direction. We show that long range effects of surface or bulk corrugations are suppressed for narrow wires or wires having an electrically anisotropic resistivity

Spontaner und posttherapeutischer Knorpelrepair: Bewertungskriterien

Zusammenfassung: Der für das Funktionieren der großen Gelenke entscheidende Gelenkknorpel besitzt beim Erwachsenen praktische keine Reparaturkapazität, weshalb einmal entstandene Schäden chronisch erhalten bleiben und sich zumeist sogar ausbreiten und in eine Osteoarthrose überzugehen drohen. Seit einem Jahrzehnt sind verschiedene neue und innovative Therapien entwickelt worden, um Regenerate zu implantieren oder intraartikulär zu induzieren und deren Funktionalität und Belastbarkeit zu erhöhen. Ein wesentlicher Parameter zur Erfassung der Funktionalität der erzeugten Regenerate ist hierbei das morphologisch erfassbare Bild, da dieses im Moment am ehesten erlaubt, Vorraussagen über die Funktionalität und Haltbarkeit der Regenerate zu treffen. Um die vielerorts laufenden Studien international vergleichend auswertbar zu machen, wurde eine Konsensusbeurteilungsskala durch die ICRS (International Cartilage Repair Society) kürzlich veröffentlicht, welche in diesem Übersichtsartikel vorgestellt und erläutert wir

Long-Range Order in Electronic Transport through Disordered Metal Films

Ultracold atom magnetic field microscopy enables the probing of current flow patterns in planar structures with unprecedented sensitivity. In polycrystalline metal (gold) films we observe long-range correlations forming organized patterns oriented at +/- 45 deg relative to the mean current flow, even at room temperature and at length scales orders of magnitude larger than the diffusion length or the grain size. The preference to form patterns at these angles is a direct consequence of universal scattering properties at defects. The observed amplitude of the current direction fluctuations scales inversely to that expected from the relative thickness variations, the grain size and the defect concentration, all determined independently by standard methods. This indicates that ultracold atom magnetometry enables new insight into the interplay between disorder and transport

Relations between M\"obius and coboundary polynomial

It is known that, in general, the coboundary polynomial and the M\"obius polynomial of a matroid do not determine each other. Less is known about more specific cases. In this paper, we will try to answer if it is possible that the M\"obius polynomial of a matroid, together with the M\"obius polynomial of the dual matroid, define the coboundary polynomial of the matroid. In some cases, the answer is affirmative, and we will give two constructions to determine the coboundary polynomial in these cases.Comment: 12 page