Direct targeting of host microtubule and actin cytoskeletons by a chlamydial pathogenic effector protein.

To propagate within a eukaryotic cell, pathogenic bacteria hijack and remodulate host cell functions. The Gram-negative obligate intracellular Chlamydiaceae, which pose a serious threat to human and animal health, attach to host cells and inject effector proteins that reprogram host cell machineries. Members of the conserved chlamydial TarP family have been characterized as major early effectors that bind to and remodel the host actin cytoskeleton. We now describe a new function for the Chlamydia pneumoniae TarP member CPn0572, namely the ability to bind and alter the microtubule cytoskeleton. Thus, CPn0572 is unique in being the only prokaryotic protein that directly modulates both dynamic cytoskeletons of a eukaryotic cell. Ectopically expressed GFP-CPn0572 associates in a dose-independent manner with either cytoskeleton singly or simultaneously. In vitro, CPn0572 binds directly to microtubules. Expression of a microtubule-only CPn0572 variant resulted in the formation of an aberrantly thick, stabilized microtubule network. Intriguingly, during infection, secreted CPn0572 also colocalized with altered microtubules, suggesting that this protein also affects microtubule dynamics during infection. Our analysis points to a crosstalk between actin and microtubule cytoskeletons via chlamydial CPn0572.

Immune-modulating properties of blue light do not influence reepithelization in vitro.

Phototherapy is gaining more attention in the treatment of various diseases. Especially, blue light seems to be a promising approach for wound healing promotion due to its antimicrobial and immune-modulating properties. Despite this, there is only little research focusing on the immune-modulating properties of blue light and its possible effects on wound healing. Therefore, we investigated the effects of blue light irradiation on peripheral blood mononuclear cells (PBMC) and the influence on reepithelization in vitro. PBMCs were irradiated with DermoDyne® (DermoDyne HealthCare, Berlin, Germany) and effects on cell viability, cytokine expression, and scratch wound closure were evaluated afterwards. Irradiated cells showed a higher Interleukin-γ concentration while irradiation reduced resazurin concentration in a time-dependent manner. No differences in reepithelization were detectable when keratinocytes were treated with the supernatant of these blue light irradiated PBMCs. Blue light-mediated ex vivo stimulation of PBMCs does not cause faster reepithelization in an in vitro setting. Further research is needed to investigate the wound healing effects of phototherapy with blue light.

An evaluation report of multimedia environments as cognitive learning tools.

This article deals with the evaluation of a multimedia learning environment which has been developed and evaluated within the broader context of a research project on the learning-dependent progression of mental models in economics. To carry out formative evaluations, we have adapted a particular evaluation approach which allows and requires the implementation of specific evaluation instruments. The crucial questions of our evaluation studies were the efficacy of a multimedia-based realization of the cognitive apprenticeship (CA) approach, the diagnosis of mental model progression through the CA based instruction, and the effects of implemented metacognitive training. For the assessment of the learning-dependent progression of the mental models, we developed and used a special diagnostic instrument for causal diagrams, which are understood as reproductions of students' mental models. In order to be able to meet statements about the practicability of a multimedia based realization of CA, we measured the results of the tasks of learning during each different learning phase. Additionally, several motivational variables and persistent learning strategies were measured. In this article, we will specify the adapted evaluation instruments. Furthermore, we will report on the results of five replication studies and discuss the consequences for instructional design in connection with the design of constructive learning environments.