Effect of Population Heterogenization on the Reproducibility of Mouse Behavior : A Multi-Laboratory Study

Peer reviewe

Protection for the smallest occupant - status quo and potentials concerning the development of child restraint systems

The use of proper child restraint systems (CRS) is mandatory for children travelling in cars in most countries of the world. The analysis of the quantity of restrained children shows that more than 90% of the children in Germany are restrained. Looking at the quality of the protection, a large discrepancy between restrained and well protected children can be seen. Two out of three children in Germany are not properly restrained. In addition, considerable difference exists with respect to the technical performance of CRS. For that reason investigations and optimisations on two different topics are necessary: The technical improvement of CRS and the ease of use of CRS. Consideration of the knowledge gained by the comparison of different CRS in crash tests would lead to some improvements of the CRS. But improvement of child safety is not only a technical issue. People should use CRS in the correct way. Misuse and incorrect handling could lead to less safety than correct usage of a poor CRS. For that reason new technical issues are necessary to improve the child safety AND the ease of use. Only the combination of both parts can significantly increase child safety. For the assessment of the safety level of common CRS, frontal and lateral sled tests simulating different severity levels were conducted comparing pairs of CRS which were felt to be good and CRS which were felt to be poor. The safety of some CRS is currently at a high level. All well known products were not damaged in the performed tests. The performance of non-branded CRS was mostly worse than that of the well known products. Although the branded child restraint systems already show a high safety level it is still possible to further improve their technical performance as demonstrated with a baby shell and a harness type CRS

Protective role of RAD50 on chromatin bridges during abnormal cytokinesis

Faithful chromosome segregation is required for preserving genomic integrity. Failure of this process may entail chromatin bridges preventing normal cytokinesis. To test whether RAD50, a protein normally involved in DNA double-strand break repair, is involved in abnormal cytokinesis and formation of chromatin bridges, we used immunocytochemical and protein interaction assays. RAD50 localizes to chromatin bridges during aberrant cytokinesis and subsequent stages of the cell cycle, either decorating the entire bridge or focally accumulating at the midbody zone. Ionizing radiation led to an ̃4-fold increase in the rate of chromatin bridges in an ataxia telangiectatica mutated (ATM)-dependent manner in human RAD50-proficient fibroblasts but not in RAD50-deficient cells. Cells with a RAD50-positive chromatin bridge were able to continue cell cycling and to progress through S phase (44%), whereas RAD50 knockdown caused a deficiency in chromatin bridges as well as an ̃4-fold prolonged duration of mitosis. RAD50 colocalized and directly interacted with Aurora B kinase and phospho-histone H3, and Aurora B kinase inhibition led to a deficiency in RAD50-positive bridges. Based on these observations, we propose that RAD50 is a crucial factor for the stabilization and shielding of chromatin bridges. Our study provides evidence for a hitherto unknown role of RAD50 in abnormal cytokinesis

Maca against Echinococcosis?-A Reverse Approach from Patient to In Vitro Testing.

Drug-based treatment of alveolar echinococcosis (AE) with benzimidazoles is in most cases non-curative, thus has to be taken lifelong. Here, we report on a 56-year-old male AE patient who received standard benzimidazole treatment and biliary plastic stents, and additionally self-medicated himself with the Peruvian plant extract Maca (Lepidium meyenii). After 42 months, viable parasite tissue had disappeared. Based on this striking observation, the anti-echinococcal activity of Maca was investigated in vitro and in mice experimentally infected with Echinococcus multilocularis metacestodes. Albendazole (ABZ)-treated mice and mice treated with an ABZ+Maca combination exhibited a significantly reduced parasite burden compared to untreated or Maca-treated mice. As shown by a newly established UHPLC-MS/MS-based measurement of ABZ-metabolites, the presence of Maca during the treatment did not alter ABZ plasma levels. In vitro assays corroborated these findings, as exposure to Maca had no notable effect on E. multilocularis metacestodes, and in cultures of germinal layer cells, possibly unspecific, cytotoxic effects of Maca were observed. However, in the combined treatments, Maca inhibited the activity of ABZ in vitro. While Maca had no direct anti-parasitic activity, it induced in vitro proliferation of murine spleen cells, suggesting that immunomodulatory properties could have contributed to the curative effect seen in the patient

F-ratios of all behavioral measures for the main effects of ‘strain’ and ‘laboratory’ based on the GLM (split by experimental design): y = strain+laboratory+strain×laboratory; p≤0.001***, p≤0.01**, p≤0.05*, p>0.05 NS.

<p>F-ratios of all behavioral measures for the main effects of ‘strain’ and ‘laboratory’ based on the GLM (split by experimental design): y = strain+laboratory+strain×laboratory; p≤0.001***, p≤0.01**, p≤0.05*, p>0.05 NS.</p

Variation of strain main effects across the six laboratories in both designs.

<p>For each laboratory and experimental design, the main effect of ‘strain’ was separately calculated and displayed in terms of the mean F-ratio (+ s.e.m., square-root-transformed) across all 29 behavioral measures. Although the strain effect varied considerably among laboratories in the heterogenized design, the standardized design produced even more variable outcomes. Moreover, average F-ratios for ‘strain’ were considerably higher in the standardized design, indicating that treatment effects may be systematically overestimated by standardization.</p

Number of stretched postures on the elevated zero maze shown by C57BL/6NCrl and DBA/2NCrl mice.

<p>Data are presented as means (+ s.e.m., square-root-transformed, n = 16/strain and laboratory). The example illustrates large effects of the laboratory in the standardized (<b>A</b>) and heterogenized (<b>B</b>) design. Moreover, the direction of strain difference differed between Giessen and Munich in the standardized design.</p

Between-experiment variation versus within-experiment variation.

<p>To assess the relative weight of between-laboratory variation versus within-laboratory variation, an F-ratio was calculated that reflects the partitioning of the ‘strain-by-block’ variance between all 24 blocks of one experimental design into variance due to variation between laboratories and variance due to variation within laboratories. For this, the mean squares of the ‘strain-by-laboratory’ interaction term were divided by the mean squares of the ‘strain-by-block’ interaction term. Data are displayed as mean F-ratios (+ s.e.m.; square-root-transformed) across all 29 behavioral measures for both conditions. F-ratios were significantly smaller in the heterogenized design (F_1,28 = 4.678, p = 0.039), demonstrating that heterogenization increased within-experiment variation relative to between-experiment variation.</p

Laboratory-specific testing procedures and apparatuses.

<p>Laboratory-specific testing procedures and apparatuses.</p

Complete list of behavioral measures used for the analysis and the transformations applied to meet the assumptions of parametric analysis (NT = no transformation, log = log₁₀(y+1)-transformed, sqrt = square-root-transformed, angular = arcsin(square-root(y))-transformed).

<p>Complete list of behavioral measures used for the analysis and the transformations applied to meet the assumptions of parametric analysis (NT = no transformation, log = log₁₀(y+1)-transformed, sqrt = square-root-transformed, angular = arcsin(square-root(y))-transformed).</p