Development of an in vitro model on cellular adhesion on granular natural bone mineral under dynamic seeding condition- A pilot study

Adhesion of osteogenic cells on biomaterials can be studied with static in vitro models, whereas models representing dynamic seeding conditions are rare. Herein, we present an in vitro model to study cell adhesion on granular biomaterials under dynamic seeding conditions. Radiolabeled osteogenic MC3T3-E1 cells were allowed to adhere to granules of natural bovine bone mineral (NBM) under constant rotation. Adhesion of MC3T3-E1 cells was determined by liquid scintillation counting, and cell morphology was visualized by scanning electron microscopy. Cell viability was determined by MTT assay under static and dynamic conditions, at room and body temperature, and in the presence or absence of serum. We show here that MC3T3-E1 cells rapidly adhere to NBM, reaching a peak 3 h after seeding. Attached cells display characteristic signs of spreading. Five to ten percent of total radioactivity remained on NBM after the removal of nonadherent cells. Viability is maintained at room temperature and under rotation for upto 3 h. This data suggests that the dynamic in vitro model presented here provides a tool to study cell adhesion on granular biomaterial

Exposure assessment of process-related contaminants in food by biomarker monitoring

Exposure assessment is a fundamental part of the risk assessment paradigm, but can often present a number of challenges and uncertainties. This is especially the case for process contaminants formed during the processing, e.g. heating of food, since they are in part highly reactive and/or volatile, thus making exposure assessment by analysing contents in food unreliable. New approaches are therefore required to accurately assess consumer exposure and thus better inform the risk assessment. Such novel approaches may include the use of biomarkers, physiologically based kinetic (PBK) modelling-facilitated reverse dosimetry, and/or duplicate diet studies. This review focuses on the state of the art with respect to the use of biomarkers of exposure for the process contaminants acrylamide, 3-MCPD esters, glycidyl esters, furan and acrolein. From the overview presented, it becomes clear that the field of assessing human exposure to process-related contaminants in food by biomarker monitoring is promising and strongly developing. The current state of the art as well as the existing data gaps and challenges for the future were defined. They include (1) using PBK modelling and duplicate diet studies to establish, preferably in humans, correlations between external exposure and biomarkers; (2) elucidation of the possible endogenous formation of the process-related contaminants and the resulting biomarker levels; (3) the influence of inter-individual variations and how to include that in the biomarker-based exposure predictions; (4) the correction for confounding factors; (5) the value of the different biomarkers in relation to exposure scenario’s and risk assessment, and (6) the possibilities of novel methodologies. In spite of these challenges it can be concluded that biomarker-based exposure assessment provides a unique opportunity to more accurately assess consumer exposure to process-related contaminants in food and thus to better inform risk assessment

The evolution of primate short-term memory

Short-term memory is implicated in a range of cognitive abilities and is critical for understanding primate cognitive evolution. To investigate the effects of phylogeny, ecology and sociality on short-term memory, we tested the largest and most diverse primate sample to date (421 non-human primates across 41 species) in an experimental delayed-response task. Our results confirm previous findings that longer delays decrease memory performance across species and taxa. Our analyses demonstrate a considerable contribution of phylogeny over ecological and social factors on the distribution of short-term memory performance in primates; closely related species had more similar short-term memory abilities. Overall, individuals in the branch of Hominoidea performed better compared to Cercopithecoidea, who in turn performed above Platyrrhini and Strepsirrhini. Interdependencies between phylogeny and socioecology of a given species presented an obstacle to disentangling the effects of each of these factors on the evolution of shortterm memory capacity. However, this study offers an important step forward in understanding the interspecies and individual variation in short-term memory ability by providing the first phylogenetic reconstruction of this trait’s evolutionary history. The dataset constitutes a unique resource for studying the evolution of primate cognition and the role of short-term memory in other cognitive abilities

Cathepsin K levels in crevicular fluid of dental implants

Objective: To determine the concentration of cathepsin K secreted into the crevicular fluid around dental implants and its correlation with clinical parameters of healthy implants and implants showing clinical signs of peri-implantitis. Material and Methods: Nineteen patients with 40 implants with and without peri-implantitis were enrolled in the study. Peri-implantitis was diagnosed by the pocket probing depth (PD), the modified bleeding index (MBI), the modified plaque index (MPI) and by radiographic signs of bone loss. Gingival crevicular fluid collected from the buccal and lingual sites was adsorbed to filter strips. Cathepsin K levels and total protein within the crevicular fluid were determined by immunoassay and the bicinchoninic method, respectively. Results: Cathepsin K per filter strip normalized to the time of collection was 10.1 (0-33.5) pmol/sample around control implants and 22.4 (3.7-56.3) pmol/sample in the peri-implantitis group. The difference between the medians was significant (p<0.01). Absolute cathepsin K levels in the crevicular fluid of all implants investigated showed a positive correlation with PD (R=0.25; p=0.03), MPI (R=0.28; p=0.01) and MBI (R=0.32; p<0.01). Absolute cathepsin K levels in the crevicular fluid also correlated with the adsorbed volume of gingival crevicular fluid (R=0.51; p<0.01). When normalized to the adsorbed volume of gingival crevicular fluid, the concentration of cathepsin K was 2.2 (0.01-6.4) nM around control implants and 1.7 (0.4-4.6) nM in the peri-implantitis group (p=0.33). Patients' age correlated with sample volume and with cathepsin K normalized to the adsorbed volume of gingival crevicular fluid (R=0.39; p<0.01). Moreover, significant differences between male and female (p<0.01, p<0.01), and between mandible and maxilla (p<0.05, p<0.01), but not between buccal and lingual sites (p=0.99, p=0.93), were observed when analysed for the parameters adsorbed volume and absolute cathepsin K levels. Conclusion: Clinical parameters of peri-implantitis are associated with a higher amount of cathepsin K and a higher volume adsorbed to filters strips. To establish cathepsin K as a biochemical parameter to monitor peri-implant tissue health, age, sex and collection site should be considered to avoid interfering influences because of sample inhomogenity. Also a prospective study over time including more patients would be necessary