A novel modular device for 3-D bone cell culture and non-destructive cell analysis

Synthetic materials have emerged as bone substitutes for filling bone defects of critical sizes. Because bone healing requires a mechanically resistant matrix (scaffold) attractive to osteogenic cells and must allow revascularization for nutrient and oxygen supply, scaffold-based strategies focus on the further development of chemical and physical qualities of the material. Cellular ingrowth towards the scaffold center is critical; therefore selective information from inner regions, in particular from the central part, is essential.In this paper we introduce a novel modular in vitro system for three-dimensional (3-D) in vitro bone cell cultures. This 3-D system is developed exclusively for in vitro research purposes, with special emphasis on the geometrical scaffold design (pore size, pore design). The system is composed of a stack of titanium slices which are mounted on a clamp and which enable the separate monitoring of cell growth patterns on every single slice of the slide stack. In this way we are able to gain selective information about the regulation of the cell physiology in the inner part of the 3-D construct which can be used for the development of an optimized scaffold design for orthopedic implants.     

Role for urea in nitrification by polar marine Archaea

Despite the high abundance of Archaea in the global ocean, their metabolism and biogeochemical roles remain largely unresolved. We investigated the population dynamics and metabolic activity of Thaumarchaeota in polar environments, where these microorganisms are particularly abundant and exhibit seasonal growth. Thaumarchaeota were more abundant in deep Arctic and Antarctic waters and grew throughout the winter at surface and deeper Arctic halocline waters. However, in situ single-cell activity measurements revealed a low activity of this group in the uptake of both leucine and bicarbonate (<5% Thaumarchaeota cells active), which is inconsistent with known heterotrophic and autotrophic thaumarchaeal lifestyles. These results suggested the existence of alternative sources of carbon and energy. Our analysis of an environmental metagenome from the Arctic winter revealed that Thaumarchaeota had pathways for ammonia oxidation and, unexpectedly, an abundance of genes involved in urea transport and degradation. Quantitative PCR analysis confirmed that most polar Thaumarchaeota had the potential to oxidize ammonia, and a large fraction of them had urease genes, enabling the use of urea to fuel nitrification. Thaumarchaeota from Arctic deep waters had a higher abundance of urease genes than those near the surface suggesting genetic differences between closely related archaeal populations. In situ measurements of urea uptake and concentration in Arctic waters showed that small-sized prokaryotes incorporated the carbon from urea, and the availability of urea was often higher than that of ammonium. Therefore, the degradation of urea may be a relevant pathway for Thaumarchaeota and other microorganisms exposed to the low-energy conditions of dark polar waters.     

The immune response at onset and during recovery from Borrelia burgdorferi meningoradiculitis

BACKGROUND: Borrelia burgdorferi causes a wide range of neurologic syndromes. In Europe, acute meningoradiculitis is the most common manifestation. OBJECTIVE: To address the nature of the immune response during the course of B burgdorferi meningoradiculitis, with special respect to the early and late changes in cerebrospinal fluid (CSF). METHODS: Serial immunophenotyping was performed and cytokine measurements were obtained in the peripheral blood and CSF of 12 European patients with definite B burgdorferi meningoradiculitis. RESULTS: Early during infection and before initiation of treatment, we observed high levels of interleukin (IL) 10, IL-6, and IL-8, and large numbers of B cells and plasma cells in the CSF of most patients. At the same time, we found a mainly unspecific intrathecal antibody synthesis. During resolution of the infection, cytokine levels normalized rapidly and plasma cells disappeared from the CSF. In parallel, the percentage of B cells in the CSF increased over several months, accompanied by rising levels of intrathecally produced B burgdorferi-specific antibodies. CONCLUSIONS: Our findings demonstrate that the early phase of B burgdorferi meningoradiculitis is characterized by a well-coordinated immune response involving specific cytokine release and plasma cell recruitment, followed by a long-lasting, antigen-specific B-cell response in the central nervous system.