Graphical Representation of the Generalized Hooke’s Law

The anisotropic linear elastic behavior of single crystals can be described equivalently by a 4th-order elasticity tensor or two functions E(d) and K(d). These functions represent Young’s modulus and a generalized bulk modulus as functions of the tensile direction d in a tension test. In the present paper three- and two-dimensional graphical representations of Young’s modulus and the generalized bulk modulus are given for single crystals belonging to one of the following symmetry groups: monoclinic, rhombic, trigonal, tetragonal, hemagonal, and cubic symmetry

Deciphering the Intracellular Fate of Propionibacterium acnes in Macrophages

Propionibacterium acnes is a Gram-positive bacterium that colonizes various niches of the human body, particularly the sebaceous follicles of the skin. Over the last years a role of this common skin bacterium as an opportunistic pathogen has been explored. Persistence of P. acnes in host tissue has been associated with chronic inflammation and disease development, for example, in prostate pathologies. This study investigated the intracellular fate of P. acnes in macrophages after phagocytosis. In a mouse model of P. acnes-induced chronic prostatic inflammation, the bacterium could be detected in prostate-infiltrating macrophages at 2 weeks postinfection. Further studies performed in the human macrophage cell line THP-1 revealed intracellular survival and persistence of P. acnes but no intracellular replication or escape from the host cell. Confocal analyses of phagosome acidification and maturation were performed. Acidification of P. acnes-containing phagosomes was observed at 6 h postinfection but then lost again, indicative of cytosolic escape of P. acnes or intraphagosomal pH neutralization. No colocalization with the lysosomal markers LAMP1 and cathepsin D was observed, implying that the P. acnes-containing phagosome does not fuse with lysosomes. Our findings give first insights into the intracellular fate of P. acnes; its persistency is likely to be important for the development of P. acnes-associated inflammatory diseases

Propionibacterium acnes inhibits FOXM1 and induces cell cycle alterations in human primary prostate cells

AbstractPropionibacterium acnes has been detected in diseased human prostate tissue, and cell culture experiments suggest that the bacterium can establish a low-grade inflammation. Here, we investigated its impact on human primary prostate epithelial cells. Microarray analysis confirmed the inflammation-inducing capability of P. acnes but also showed deregulation of genes involved in the cell cycle. qPCR experiments showed that viable P. acnes downregulates a master regulator of cell cycle progression, FOXM1. Flow cytometry experiments revealed that P. acnes increases the number of cells in S-phase. We tested the hypothesis that a P. acnes-produced berninamycin-like thiopeptide is responsible for this effect, since it is related to the FOXM1 inhibitor siomycin. The thiopeptide biosynthesis gene cluster was strongly expressed; it is present in subtype IB of P. acnes, but absent from type IA, which is most abundant on human skin. A knock-out mutant lacking the gene encoding the berninamycin-like peptide precursor was unable to downregulate FOXM1 and to halt the cell cycle. Our study reveals a novel host cell-interacting activity of P. acnes

Comparative genomics reveals distinct host-interacting traits of three major human-associated propionibacteria

BACKGROUND: Propionibacteria are part of the human microbiota. Many studies have addressed the predominant colonizer of sebaceous follicles of the skin, Propionibacterium acnes, and investigated its association with the skin disorder acne vulgaris, and lately with prostate cancer. Much less is known about two other propionibacterial species frequently found on human tissue sites, Propionibacterium granulosum and Propionibacterium avidum. Here we analyzed two and three genomes of P. granulosum and P. avidum, respectively, and compared them to two genomes of P. acnes; we further highlight differences among the three cutaneous species with proteomic and microscopy approaches. RESULTS: Electron and atomic force microscopy revealed an exopolysaccharide (EPS)-like structure surrounding P. avidum cells, that is absent in P. acnes and P. granulosum. In contrast, P. granulosum possesses pili-like appendices, which was confirmed by surface proteome analysis. The corresponding genes were identified; they are clustered with genes encoding sortases. Both, P. granulosum and P. avidum lack surface or secreted proteins for predicted host-interacting factors of P. acnes, including several CAMP factors, sialidases, dermatan-sulphate adhesins, hyaluronidase and a SH3 domain-containing lipoprotein; accordingly, only P. acnes exhibits neuraminidase and hyaluronidase activities. These functions are encoded on previously unrecognized island-like regions in the genome of P. acnes. CONCLUSIONS: Despite their omnipresence on human skin little is known about the role of cutaneous propionibacteria. All three species are associated with a variety of diseases, including postoperative and device-related abscesses and infections. We showed that the three organisms have evolved distinct features to interact with their human host. Whereas P. avidum and P. granulosum produce an EPS-like surface structure and pili-like appendices, respectively, P. acnes possesses a number of unique surface-exposed proteins with host-interacting properties. The different surface properties of the three cutaneous propionibacteria are likely to determine their colonizing ability and pathogenic potential on the skin and at non-skin sites

KINEMATIC PROFILE OF THE ELITE HANDCYCLIST

A handcycle is a relatively new sports equipment that is a combination of the traditional race wheelchair and a hand operated bicycle crank (Abel, Schneider, Platen, & Struder, 2006). The high mechanical efficiency of this geared fixed-frame racing cycle in comparison to a manual wheelchair can potentially increase the distance a person with a loss of lower limb function can travel. To guide the optimal setup for the handcyclist the influence of crank length (Goosey-Tolfrey, Alfano, & Fowler, 2008; Kramer, Hilker, & Bohm, 2009) and crank configuration (Faupin, Gorce, Meyer, & Thevenon, 2008a; Mossberg, Willman, Topor, Crook, & Patak, 1999) have been investigated. Actual neither research has been done on the upper body kinematics of elite athletes nor on relations between kinematics and performance. The aim of this study was to provide first sport specific information in this area with regards to athletes competing at an international level