Solvent‐Assisted Micromolding of Biohybrid Hydrogels to Maintain Human Hematopoietic Stem and Progenitor Cells Ex Vivo

Array‐format cell‐culture carriers providing tunable matrix cues are instrumental in current cell biology and bioengineering. A new solvent‐assisted demolding approach for the fabrication of microcavity arrays with very small feature sizes down to single‐cell level (3 µm) of very soft biohybrid glycosaminoglycan–poly(ethylene glycol) hydrogels (down to a shear modulus of 1 kPa) is reported. It is further shown that independent additional options of localized conjugation of adhesion ligand peptides, presentation of growth factors through complexation to gel‐based glycosaminoglycans, and secondary gel deposition for 3D cell embedding enable a versatile customization of the hydrogel microcavity arrays for cell culture studies. As a proof of concept, cell‐instructive hydrogel compartment arrays are used to analyze the response of human hematopoietic stem and progenitor cells to defined biomolecular and spatial cues.     

Anpassungsfaktoren für das Lastmodell 1 des DIN‐Fachberichtes 101 für gewichtsbeschränkt beschilderte Straßenbrücken

Correction Factors for the Load Model 1 according to the DIN‐Fachbericht 101 for Weight constricted signposted Road Bridges Since 2003 the DIN‐Fachbericht 101 is the normative basis for the design loads of bridges in Germany. In contrast to the previous code of practice, the DIN 1072, the DIN‐Fachbericht does not include details about bridges, which will be signed with traffic weight limitations. This paper describes the development of reduction factors for the Load Model 1 in the DIN‐Fachbericht and presents the new calculated factors. Therefore the DIN‐Fachbericht Load Model 1 has been extended for the application of traffic weight limitations signed bridges.     

Effect of copolymer composition on the solubility and diffusivity of water and methanol in a series of polyether amides

Sorption and diffusion of water and methanol in polydimethylsiloxane and a series of PEBAX™ copolymers (polyether block amide copolymers) were measured over a wide range of activities near room temperature. The goal was to identify a membrane material for separation of the hazardous air pollutant methanol from wet air streams in the pulp and paper industry. The PEBAX™ copolymer series used here allows a unique insight into transport of small molecules, because solubilities are virtually constant, while diffusion coefficients vary. This is due to the similar chemical structure, but different chain mobility of the homopolymers. The grade PEBAX™ 2533 is most promising for the separation process due to high solubility and diffusivity. The unwanted simultaneous highly selective separation of methanol and water from the targeted air/vapor streams will be addressed in future work. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1983–1993, 1997     

Comparison of the Translational Potential of Human Mesenchymal Progenitor Cells from Different Bone Entities for Autologous 3D Bioprinted Bone Grafts

Reconstruction of segmental bone defects by autologous bone grafting is still the standard of care but presents challenges including anatomical availability and potential donor site morbidity. The process of 3D bioprinting, the application of 3D printing for direct fabrication of living tissue, opens new possibilities for highly personalized tissue implants, making it an appealing alternative to autologous bone grafts. One of the most crucial hurdles for the clinical application of 3D bioprinting is the choice of a suitable cell source, which should be minimally invasive, with high osteogenic potential, with fast, easy expansion. In this study, mesenchymal progenitor cells were isolated from clinically relevant human bone biopsy sites (explant cultures from alveolar bone, iliac crest and fibula; bone marrow aspirates; and periosteal bone shaving from the mastoid) and 3D bioprinted using projection-based stereolithography. Printed constructs were cultivated for 28 days and analyzed regarding their osteogenic potential by assessing viability, mineralization, and gene expression. While viability levels of all cell sources were comparable over the course of the cultivation, cells obtained by periosteal bone shaving showed higher mineralization of the print matrix, with gene expression data suggesting advanced osteogenic differentiation. These results indicate that periosteum-derived cells represent a highly promising cell source for translational bioprinting of bone tissue given their superior osteogenic potential as well as their minimally invasive obtainability.     

Examining the Hostile Media Effect as an Intergroup Phenomenon: The Role of Ingroup Identification and Status

This approach conceptualizes the hostile media effect (HME) as an intergroup phenomenon. Two empirical studies, one quasi‐experimental and one experimental, examine the HME in the context of the abortion debate. Both studies show that ingroup identification and group status qualify the HME. Pro‐choice and pro‐life group members perceived an identical newspaper article as biased against their own viewpoint only if they considered their ingroup to have a lower status in society than the outgroup. In addition, only group members with a stronger ingroup identification showed a HME, particularly because of self‐investment components of ingroup identification. Taken together, the findings confirm the important influence of ingroup status and ingroup identification on the HME.     

Inhibition of mitochondrial respiratory chain complex I by TNF results in cytochrome c release, membrane permeability transition, and apoptosis

Mitochondria have been shown to play a key role in apoptosis induction. However, the sequence of changes that occur in the mitochondria in the initial step of apoptosis has not been clearly elucidated. Here, we showed that mitochondrial respiratory chain (MRC) complex I was inhibited during the early phase of TNF- or serum withdrawal apoptosis. The importance of complex I inhibition in apoptosis is also supported by the observation that rotenone, an inhibitor of complex I but not that of other complexes, could induce apoptosis in a manner comparable to TNF. We hypothesized that inhibition of complex I could affect electron flow through other complexes leading to cytochrome c release by an antioxidant-sensitive pathway and caspase 3 activation followed by the induction of membrane permeability transition (MPT). This hypothesis is supported by the following observations: (1) TNF and rotenone induced MPT and cytochrome c release; (2) TNF-induced complex I inhibition was observed prior to cytochrome c release and MPT induction; (3) MPT induction was inhibited by a caspase 3 inhibitor, z-DEVD-CH2F, and an antioxidant pyrrolidine dithiocarbamate (PDTC), whereas cytochrome c release was only inhibited by PDTC. Thus, these results suggest that MRC complex I plays a key role in apoptosis signalings.