Technical Report Scintigraphic Evaluation of Bone Formation in Göttingen Minipigs

In experiments and processes requiring the application of nuclear tracers in large animals, statutory provisions  and safety standards as well as a variety of techniques have to be regarded and employed. In order to sufficiently analyze questions pertaining to osseointegration as well as the possibility of ectopic  bone formation in Göttingen minipigs, we decided to use scintigraphic examinations using 99mTc-HDP  (Technetium - hydroxymethane diphosphonate). In this study, metallic implants coated in different forms  with rhBMP-2 (recombinant human bone morphogenetic protein-2) were surgically introduced into the  pigs’ femora. A total of 26 adult female minipigs (Ellegard, Dalmose, Denmark) averaging 40 months in  age were post-surgically evaluated through the application of a radionuclide and its subsequent distribution  using a scintillation camera. Each animal received approximately 10 MBq/kg BW (mega Becquerel per  kilogram bodyweight). This paper describes the procedures of anaesthesia, the quite challenging transvaginal- urethral catheterization,  the application of a catheter in the jugular vein, the radionuclide injection and the disposal of the  sacrificed animals under statutory provisions and safety standards. The technical report reveals that the scintigraphic evaluation in large animal experiments is a practicable  – yet sophisticated – method of examination and also strives to encourage further research groups to implement  this elegant procedure.

Reactions to geovisualization: An experience from a European project

The paper is written jointly by two parties, computer scientists specializing in geovisualization and experts in forestry, who cooperated within a joint project. The authors tell a story about an attempt of the geovisualizers to introduce the foresters to the concept and principles of exploratory data analysis and to the use of visualization for systematic and comprehensive data exploration. This endeavor should be considered as an informal experiment rather than a rigorous scientific study. Unlike customary tests of the usability of specific tools and techniques, the geovisualizers did not give the forestry specialists a series of tasks to carry out by applying geovisualization tools and did not try to measure how well the foresters performed. The idea of the geovisualizers was to demonstrate the principles and power of exploratory data analysis to the foresters by example. For this purpose, the geovisualizers performed an exploration of a non‐trivial data set by themselves and reported the procedure, the principles, the techniques, and the findings to the foresters. The reaction of the foresters uncovered a range of fundamental issues that are relevant to geovisualization and information visualization research. The authors analyze these issues from their perspectives and formulate a set of questions which researchers in geovisualization should be asking

Analysis of the osseointegrative force of a hyperhydrophilic and nanostructured surface refinement for TPS surfaces in a gap healing model with the Göttingen minipig

Background: A lot of advantages can result in a high wettability as well as a nanostructure at a titanium surface on bone implants. Thus, the aim of this study was to evaluate the osseointegrative potential of a titan plasma-sprayed (TPS) surface refinement by acid-etching with chromosulfuric acid. This results in a hyperhydrophilic surface with a nanostructure and an extreme high wetting rate. Methods: In total, 72 dumbbell shape titan implants were inserted in the spongy bone of the femora of 18 Göttingen minipigs in a conservative gap model. Thirty-six titan implants were coated with a standard TPS surface and 36 with the hyperhydrophilic chromosulfuric acid (CSA) surface. After a healing period of 4, 8, and 12 weeks, the animals were killed. The chronological healing process was histomorphometrically analyzed. Results: The de novo bone formation, represented by the bone area (BA), is increased by approximately 1.5 times after 12 weeks with little additional benefit by use of the CSA surface. The bone-to-implant contact (BIC), which represents osseoconductive forces, shows results with a highly increased osteoid production in the CSA implants beginning at 8 and 12 weeks compared to TPS. This culminates in a 17-fold increase in BIC after a healing period of 12 weeks. After 4 weeks, significantly more osteoid was seen in the gap as de novo formation in the CSA group (p = 0.0062). Osteoid was also found more frequently after 12 weeks at the CSA-treated surface (p = 0.0355). The site of implantation, intertrochanteric or intercondylar, may influence on the de novo bone formation in the gap. Conclusions: There is a benefit by the CSA surface treatment of the TPS layer for osseointegration over an observation time up to 12 weeks. Significant differences were able to be shown in two direct comparisons between the CSA and the TPS surface for osteoid formation in the gap model. Further trials may reveal the benefit of the CSA treatment of the TPS layer involving mechanical tests if possible

A test on Ellenberg indicator values in the Mediterranean evergreen woods (Quercetea ilicis)

The consistency and reliability of Ellenberg’s indicator values (Eiv) as ecological descriptors of the Mediterranean evergreen vegetation ascribed to the phytosociological class Quercetea ilicis have been checked on a set of 859 phytosociological relevés × 699 species. Diagnostic species were identified through a Twinspan analysis and their Eiv analyzed and related to the following independent variables: (1) annual mean temperatures, (2) annual rainfall. The results provided interesting insights to disentangle the current syntaxonomical framework at the alliance level demonstrating the usefulness of ecological indicator values to test the efficiency and predictivity of the phytosociological classification

How robust are community-based plant bioindicators? Empirical testing of the relationship between Ellenberg values and direct environmental measures in woodland communities

There are several community-based bioindicator systems that use species presence or abundance data as proxies for environmental variables. One example is the Ellenberg system, whereby vegetation data are used to estimate environmental soil conditions. Despite widespread use of Ellenberg values in ecological research, the correlation between bioindicated values and actual values is often an implicit assumption rather than based on empirical evidence. Here, we correlate unadjusted and UK-adjusted Ellenberg values for soil moisture, pH, and nitrate in relation to direct environmental measures for 50 woodland sites in the UK, which were subject to repeat sampling. Our results show the accuracy of Ellenberg values is parameter specific; pH values were a good proxy for direct environmental measures but this was not true for soil moisture, when relationships were weak and non-significant. For nitrates, there were important seasonal differences, with a strong positive logarithmic relationship in the spring but a non-significant (and negative) correlation in summer. The UK-adjusted values were better than, or equivalent to, Ellenberg’s original ones, which had been quantified originally for Central Europe, in all cases. Somewhat surprisingly, unweighted values correlated with direct environmental measures better than did abundance-weighted ones. This suggests that the presence of rare plants can be highly important in accurate quantification of soil parameters and we recommend using an unweighted approach. However, site profiles created only using rare plants were inferior to profiles based on the whole plant community and thus cannot be used in isolation. We conclude that, for pH and nitrates, the Ellenberg system provides a useful estimate of actual conditions, but recalibration of moisture values should be considered along with the effect of seasonality on the efficacy of the system