Käthe Kollwitz und die Kunst ihrer Zeit: Positionen zur Geburtenpolitik

Als 1931 die Menschen in Massen gegen den §218 auf die Straße zogen, organisierte man in Berlin eine Ausstellung mit dem Titel 'Frauen in Not'. Von dieser ausstellungsgeschichtlich spektakulären Veranstaltung ausgehend, untersucht die Autorin die Wechselbeziehungen zwischen Kunst und den gesellschaftlichen Prozessen im Umfeld der Geburtenpolitik. Damit wird ein Forschungsgebiet geöffnet, in dem sich private und öffentliche Interessen sowie die Ansprüche weiblicher Autonomie und männlicher Macht konfliktreich verschränken. Es wird gezeigt, wie Käthe Kollwitz, die die menschliche Regeneration und ihre soziale Problematik zu einem zentralen Thema erhob, zur Leitfigur in den Auseinandersetzungen werden konnte. Unter dem Aspekt der Geburtenpolitik werden auch zu Hans Baluschek, Ernst Barlach, Otto Dix, Conrad Felixmüller, George Grosz, Sella Hasse, Katharina Heise, Hannah Höch, Hanna Nagel, Felix Nussbaum, Emy Roeder, Arthur Segal, Christoph Voll und Heinrich Zille neue Ergebnisse vorgestellt. Der Blick auf die künstlerischen und ideologischen Interaktionen erhellt eine brisante Phase in der Geschichte der Geschlechterverhältnisse im 20. Jahrhundert

Impaired bone formation in ovariectomized mice reduces implant integration as indicated by longitudinal in vivo micro-computed tomographs

Although osteoporotic bone, with low bone mass and deteriorated bone architecture, provides a less favorable mechanical environment than healthy bone for implant fixation, there is no general agreement on the impact of osteoporosis on peri-implant bone (re)modeling, which is ultimately responsible for the long term stability of the bone-implant system. Here, we inserted an implant in a mouse model mimicking estrogen deficiency-induced bone loss and we monitored with longitudinal in vivo micro-computed tomography the spatio-temporal changes in bone (re)modeling and architecture, considering the separate contributions of trabecular, endocortical and periosteal surfaces. Specifically, 12 week-old C57BL/6J mice underwent OVX/SHM surgery; 9 weeks after we inserted special metal-ceramics implants into the 6th caudal vertebra and we measured bone response with in vivo micro-CT weekly for the following 6 weeks. Our results indicated that ovariectomized mice showed a reduced ability to increase the thickness of the cortical shell close to the implant because of impaired peri-implant bone formation, especially at the periosteal surface. Moreover, we observed that healthy mice had a significantly higher loss of trabecular bone far from the implant than estrogen depleted animals. Such behavior suggests that, in healthy mice, the substantial increase in peri-implant bone formation which rapidly thickened the cortex to secure the implant may raise bone resorption elsewhere and, specifically, in the trabecular network of the same bone but far from the implant. Considering the already deteriorated bone structure of estrogen depleted mice, further bone loss seemed to be hindered. The obtained knowledge on the dynamic response of diseased bone following implant insertion should provide useful guidelines to develop advanced treatments for osteoporotic fracture fixation based on local and selective manipulation of bone turnover in the peri-implant region.ISSN:1932-620

Mechanical regulation of bone formation and resorption around implants in a mouse model of osteopenic bone

Although mechanical stimulation is considered a promising approach to accelerate implant integration, our understanding of load-driven bone formation and resorption around implants is still limited. This lack of knowledge may delay the development of effective loading protocols to prevent implant loosening, especially in osteoporosis. In healthy bone, formation and resorption are mechanoregulated processes. In the intricate context of peri-implant bone regeneration, it is not clear whether bone (re)modelling can still be load-driven. Here, we investigated the mechanical control of peri-implant bone (re)modelling with a well-controlled mechanobiological experiment. We applied cyclic mechanical loading after implant insertion in tail vertebrae of oestrogen depleted mice and we monitored peri-implant bone response by in vivo micro-CT. Experimental data were combined with micro-finite element simulations to estimate local tissue strains in (re)modelling locations. We demonstrated that a substantial increase in bone mass around the implant could be obtained by loading the entire bone. This augmentation could be attributed to a large reduction in bone resorption rather than to an increase in bone formation. We also showed that following implantation, mechanical regulation of bone (re)modelling was transiently lost. Our findings should help to clarify the role of mechanical stimulation on the maintenance of peri-implant bone mass

Changes in the length of the implanted vertebra monitored for the entire experiment (including OVX/SHM surgery and implant insertion).

<p>On the right, a three-dimensional visualization of bone remodeling in the whole vertebra is reported, with the lengthening corresponding to high bone formation localized in the growth plates (which were excluded from the analysis of bone (re)modeling) (a). Time evolution of cortical thickness (Ct.Th) and bone volume fraction (BV/TV) in the peri-implant (b, d) and distant bone (c, e) for ovariectomized (OVX) and sham-ovariectomized (SHM) mice following implantation. Differences in Ct.Th and BV/TV between the first and the last time point in the peri-implant and distant region are also shown in percentage changes (f). * denotes a significant difference (p < 0.05) between groups. Significant differences between first and last time point are marked by # in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184835#pone.0184835.t004" target="_blank">Table 4</a>. Data reported as mean ± standard error.</p

Bone (re)modeling post implantation close to the implant.

<p>Bone (re)modeling post implantation close to the implant.</p

In vivo monitoring of bone architecture and remodeling after implant insertion: The different responses of cortical and trabecular bone

The mechanical integrity of the bone-implant system is maintained by the process of bone remodeling. Specifically, the interplay between bone resorption and bone formation is of paramount importance to fully understand the net changes in bone structure occurring in the pen-implant bone, which are eventually responsible for the mechanical stability of the bone-implant system. Using time-lapsed in vivo micro-computed tomography combined with new composite material implants, we were able to characterize the spatio-temporal changes of bone architecture and bone remodeling following implantation in living mice. After insertion, implant stability was attained by a quick and substantial thickening of the cortical shell which counteracted the observed loss of trabecular bone, probably due to the disruption of the trabecular network. Within the trabecular compartment, the rate of bone formation close to the implant was transiently higher than far from the implant mainly due to an increased mineral apposition rate which indicated a higher osteoblastic activity. Conversely, in cortical bone, the higher rate of bone formation close to the implant compared to far away was mostly related to the recruitment of new osteoblasts as indicated by a prevailing mineralizing surface. The behavior of bone resorption also showed dissimilarities between trabecular and cortical bone. In the former, the rate of bone resorption was higher in the pen-implant region and remained elevated during the entire monitoring period. In the latter, bone resorption rate had a bigger value away from the implant and decreased with time. Our approach may help to tune the development of smart implants that can attain a better long-term stability by a local and targeted manipulation of the remodeling process within the cortical and the trabecular compartments and, particularly, in bone of poor health. (C) 2015 Elsevier Inc. All rights reserved

Changes in bone architecture after estrogen removal.

<p>Changes in bone architecture after estrogen removal.</p

Bone (re)modeling rates for ovariectomized (OVX) and sham-ovariectomized (SHM) mice in peri-implant region of periosteal surface (a, d and g), endocortical surface (b, e and h), and trabecular bone (c, f and i).

<p>* denotes a significant difference (p < 0.05) between groups within the same time interval. Significant differences between first and last time interval are marked by # in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184835#pone.0184835.t002" target="_blank">Table 2</a>. Data reported as mean ± standard error.</p