Use of Micro-CT Imaging to Assess Ventral Mandibular Cortical Thickness and Volume in an Experimental Rodent Model With Chronic High-Phosphorus Intake.

Adverse effects of high dietary phosphorus on bone health have been observed in both animal and human studies. The aim of the investigation was to examine chronic effects of high phosphorus diet on the apical mandibular cortical thickness and volume in a hystricomorph rodent (Octodon degus) using microcomputed tomography. Male degus were randomly divided into two groups fed by different mineral contents from the age of 12 weeks till the age of 17 months. The micro-CT scanning and wall thickness analysis were applied on the region of the mandible exactly under the apices of the 4th premolar tooth, first molar tooth, and second molar tooth in two animals from each group. General overview and mapping of the ventral mandibular bone thickness revealed pronounced bony mandibular protrusions in all the animals fed a high-phosphorus diet with obvious bone thinning apically to the 4th premolar and first and second molar tooth apices. Mandibular bone volume and thickness located apically to the premolar and molars were statistically significantly smaller/thinner in the group fed by a high phosphorus diet. The thinnest bone measured 0.004 mm, where the mandibular 4th premolar tooth almost perforated the mandibular cortex. Similar studies of metabolic bone disease and its influence on alveolar bone were also published in rats and mice. The influence of different environmental, infectious, or metabolic factors on the growing tooth, alveolar bone formation, and bone pathologies must be done experimentally on growing animals. In contrast, degus have continuously growing dentition, and the effect of any of the above listed factors can be studied in this animal model at any age and for longer time periods.

An RNA aptamer restores defective bone growth in FGFR3-related skeletal dysplasia in mice.

Achondroplasia is the most prevalent genetic form of dwarfism in humans and is caused by activating mutations in FGFR3 tyrosine kinase. The clinical need for a safe and effective inhibitor of FGFR3 is unmet, leaving achondroplasia currently incurable. Here, we evaluated RBM-007, an RNA aptamer previously developed to neutralize the FGFR3 ligand FGF2, for its activity against FGFR3. In cultured rat chondrocytes or mouse embryonal tibia organ culture, RBM-007 rescued the proliferation arrest, degradation of cartilaginous extracellular matrix, premature senescence, and impaired hypertrophic differentiation induced by FGFR3 signaling. In cartilage xenografts derived from induced pluripotent stem cells from individuals with achondroplasia, RBM-007 rescued impaired chondrocyte differentiation and maturation. When delivered by subcutaneous injection, RBM-007 restored defective skeletal growth in a mouse model of achondroplasia. We thus demonstrate a ligand-trap concept of targeting the cartilage FGFR3 and delineate a potential therapeutic approach for achondroplasia and other FGFR3-related skeletal dysplasias.

Contrast enhanced X-ray computed tomography imaging of amyloid plaques in Alzheimer disease rat model on lab based micro CT system.

Amyloid plaques are small (~ 50 µm), highly-dense aggregates of amyloid beta (Aß) protein in brain tissue, supposed to play a key role in pathogenesis of Alzheimer's disease (AD). Plaques´ in vivo detection, spatial distribution and quantitative characterization could be an essential marker in diagnostics and evaluation of AD progress. However, current imaging methods in clinics possess substantial limits in sensitivity towards Aß plaques to play a considerable role in AD screening. Contrast enhanced X-ray micro computed tomography (micro CT) is an emerging highly sensitive imaging technique capable of high resolution visualization of rodent brain. In this study we show the absorption based contrast enhanced X-ray micro CT imaging is viable method for detection and 3D analysis of Aß plaques in transgenic rodent models of Alzheimer's disease. Using iodine contrasted brain tissue isolated from the Tg-F344-AD rat model we show the micro CT imaging is capable of precise imaging of Aß plaques, making possible to further analyze various aspects of their 3D spatial distribution and other properties.

Interface Behavior and Interface Tensile Strength of a Hardened Concrete Mixture with a Coarse Aggregate for Additive Manufacturing.

3D concrete printing technology (3DCP) is a relatively new technology that was first established in the 1990s. The main weakness of the technology is the interface strength between the extruded layers, which are deposited at different time intervals. Consequently, the interface strength is assumed to vary in relation to the time of concrete casting. The proposed experimental study investigated the behavior of a hardened concrete mixture containing coarse aggregates that were up to 8 mm in size, which is rather unusual for 3DCP technology. The resulting direct tensile strength at the layer interface was investigated for various time intervals of deposition from the initial mixing of concrete components. To better understand the material behavior at the layer interface area, computed tomography (CT) scanning was conducted, where the volumetric and area analysis enabled validation of the pore size and count distribution in accordance with the layer deposition process. The analyzed CT data related the macroscopic anisotropy and the resulting crack pattern to the temporal and spatial variability that is inherent to the additive manufacturing process at construction scales while providing additional insights into the porosity formation during the extrusion of the cementitious composite. The observed results contribute to previous investigations in this field by demonstrating the causal relationships, namely, how the interface strength development is determined by time, deposition process, and pore size distribution. Moreover, in regard to the printability of the proposed coarse aggregate mixture, the specific time interval is presented and its interplay with interface roughness and porosity is discussed.

Qualitative detection of Mg content in a leaf of Hedera helix by using X-ray radiation from a laser plasma source.

In this article, a method to reveal the presence of Mg content inside the different parts of leaves of Hedera helix is presented. In fact a sample of a Hedera helix's leaf, commonly characterized by a green and a white side, is analyzed under X-ray radiation. The presence of two zones with different colors in the Hedera helix's leaf has not been explained. In this connection, there are presently three hypotheses to explain the characteristic double-color appearance of the leaf. The first hypothesis suggests a different cytoplasmic inheritance of chloroplasts at the cell division, the second a different allelic composition, homozygote and heterozygote, between the two zones, and finally the third the action of a virus which changes the color properties in the Hedera's leaves. The resulting effect is a different content of "something" between the green and the white side. We utilized X-ray radiation, obtained from a plasma source with a Mg target, to image Hedera helix leaves and we found that the green side of the leaf is highlighted. We may suppose that the reason why the X-rays from a Mg plasma source, allow us to pick up the green side is probably due to the greater presence of the amount of Mg (from chlorophyll or other complexes and/or salts) in the two sides, green and white, of the leaf.