Free University of Berlin

About: Free University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Population & Context (language use). The organization has 35195 authors who have published 66525 publications receiving 2094403 citations. The organization is also known as: FU Berlin.

A Novel Type of Skeleton for Polygons

Abstract: A new internal structure for simple polygons, the straight skeleton, is introduced and discussed. It is composed of pieces of angular bisectores which partition the interior of a given n-gon P in a tree-like fashion into n monotone polygons. Its straight-line structure and its lower combinatorial complexity may make the straight skeleton preferable to the widely used medial axis of a polygon. As a seemingly unrelated application, the straight skeleton provides a canonical way of constructing a polygonal roof above a general layout of ground walls.

How to overcome health-compromising behaviors: The health action process approach

Abstract: Health-compromising behaviors such as cigarette smoking and poor dietary habits are difficult to change. Most social-cognitive theories assume that the intention to change is the best predictor of actual change, but people often do not behave in accordance with their intentions. Unforeseen barriers emerge, or people give in to temptations. Therefore, intentions should be supplemented by more proximal predictors that might facilitate the translation of intentions into action. Some self-regulatory mediators have been identified, such as perceived self-efficacy and strategic planning. They help to bridge the intention-behavior gap. The Health Action Process Approach (HAPA) suggests a distinction between (1) a preintentional motivation process that leads to a behavioral intention and (2) a postintentional volition process that facilitates the adoption and maintenance of health behaviors. In this article, two studies are reported that examine mediators between intentions and two behaviors. One behavior is smok...

Human defensins

Abstract: Antimicrobial peptides are small, cationic, amphiphilic peptides of 12–50 amino acids with microbicidal activity against both bacteria and fungi. The eukaryotic antimicrobial peptides may be divided into four distinct groups according to their structural features: cysteine-free α-helices, extended cysteine-free α-helices with a predominance of one or two amino acids, loop structures with one intramolecular disulfide bond, and β-sheet structures which are stabilised by two or three intramolecular disulfide bonds. Mammalian defensins are part of the last-mentioned group. The mammalian defensins can be subdivided into three main classes according to their structural differences: the α-defensins, β-defensins and the recently described θ-defensins. Mammalian α-defensins are predominantly found in neutrophils and in small intestinal Paneth cells, whereas mammalian β-defensins have been isolated from both leukocytes and epithelial cells. Recently, two novel human β-defensins, human beta-defensin-3 (HBD-3), and human beta-defensin-4 (HBD-4) have been discovered. Similar to HBD-1 and HBD-2, HBD-3 has microbicidal activity towards the Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli) and the yeasts Candida albicans and Malassezia furfur. In addition, HBD-3 kills Gram-positive bacteria such as Streptococcus pyogenes or Staphylococcus aureus, including multi-resistant S. aureus strains, and even vancomycin-resistant Enterococcus faecium. In contrast to HBD-1 and HBD-2, significant expression of HBD-3 has been demonstrated in non-epithelial tissues, such as leukocytes, heart and skeletal muscle. HBD-4 is expressed in certain epithelia and in neutrophils. Its bactericidal activity against P. aeruginosa is stronger than that of the other known β-defensins. Here we present an overview of human antimicrobial peptides with some emphasis on their antifungal properties.

Extended-spectrum beta-lactamases producing E. coli in wildlife, yet another form of environmental pollution?

Abstract: Wildlife is normally not exposed to antimicrobial agents but can acquire antimicrobial resistant bacteria through contact with humans, domesticated animals and the environment, where water polluted with faeces seems to be the most important vector. E. coli, a ubiquitous commensal bacterial species colonizing the intestinal tract of mammals and birds, is also found in the environment. Extended-spectrum beta-lactamases producing E. coli (ESBL-E. coli) represent a major problem in human and veterinary medicine, particular in nosocomial infections. Additionally an onset of community acquired ESBL-E. coli infections and an emergence in livestock farming has been observed in recent years, suggesting a successful transmission as well as persistence of ESBL-E. coli strains outside clinical settings. Another parallel worldwide phenomenon is the spread of ESBL-E. coli into the environment beyond human and domesticated animal populations, and this seems to be directly influenced by antibiotic practice. This might be a collateral consequence of the community onset of ESBL-E. coli infections but can result (a) in a subsequent colonization of wild animal populations which can turn into an infectious source or even a reservoir of ESBL-E.coli, (b) in a contribution of wildlife to the spread and transmission of ESBL-E. coli into fragile environmental niches, (c) in new putative infection cycles between wildlife, domesticated animals and humans, and (d) in problems in the medical treatment of wildlife. This review aims to summarize the current knowledge on ESBL-E. coli in wildlife, in turn underlining the need for more large scale investigations, in particular sentinel studies to monitor the impact of multiresistant bacteria on wildlife.

Cutting Edge: Immune Stimulation by Neisserial Porins Is Toll-Like Receptor 2 and MyD88 Dependent

Abstract: The immunopotentiating activity of neisserial porins, the major outer membrane protein of the pathogenic Neisseria, is mediated by its ability to stimulate B cells and up-regulate the surface expression of B7-2. This ability is dependent on MyD88 and Toll-like receptor (TLR)2 expression, as demonstrated by a lack of a response by B cells from MyD88 or TLR2 knockout mice to the porins. Using previously described TLR2-dependent reporter constructs, these results were confirmed and were shown to be due to induction of NF-κB nuclear translocation. This is the first demonstration of known vaccine adjuvant to stimulate immune cells via TLR2.