Injury to the central nervous system initiates an uncontrolled inflammatory response that results in both tissue repair and destruction. Here, we showed that, in rodents and humans, injury to the spinal cord triggered surface expression of CD95 ligand (CD95L, FasL) on peripheral blood myeloid cells. CD95L stimulation of CD95 on these cells activated phosphoinositide 3-kinase (PI3K) and metalloproteinase-9 (MMP-9) via recruitment and activation of Syk kinase, ultimately leading to increased migration. Exclusive CD95L deletion in myeloid cells greatly decreased the number of neutrophils and macrophages infiltrating the injured spinal cord or the inflamed peritoneum after thioglycollate injection. Importantly, deletion of myeloid CD95L, but not of CD95 on neural cells, led to functional recovery of spinal injured animals. Our results indicate that CD95L acts on peripheral myeloid cells to induce tissue damage. Thus, neutralization of CD95L should be considered as a means to create a controlled beneficial inflammatory response.

The Schur Horn Convexity Theorem states that for a in Rwhere p denotes the projection on the diagonal. In this paper we generalize this result to the setting of arbitrary separable Hilbert spaces. It turns out that the theorem still holds, if we take the l -closure on both sides. We will also give a description of the left-hand side for nondiagonalizable hermitian operators. In the last section we use this result to get an extension theorem for invariant closed convex subsets of the diagonal operators. Academic Press

There is a controversy about the biocompatibility of silicon nitride ceramics contained in the literature, which appears to be related to a factor of the individual chemical composition of different qualities of silicon nitride ceramics and of the different surface properties. This study attempts to investigate the cytotoxicity of different qualities of industrial silicon nitride ceramics applying an L929-cell culture model in a direct contact assay combined with a cell viability assessment. Five different qualities of industrial standard silicon nitride ceramics were chosen for in vitro testing. The chemical composition was determined by EDS analysis. Different biomedically approved aluminium oxide qualities, a titanium alloy, glass and polyvinylchloride (PVC) served as control materials. L929 mice fibroblasts were incubated directly on the materials for 24 h, stained with bisbenzimide and propidium iodine for double fluorochromasia viability testing, and evaluated by inversion-fluorescence microscopy to control cell morphology, viability and cell counts compared to empty well values. Scanning electron microscopy was applied to additionally investigate cell morphology. There was no observation of cytotoxic effects on the silicon nitride ceramic samples; moreover cell morphology remained the same as on aluminium oxide and titanium. Viability testing revealed the presence of avital cells exclusively on PVC, which served as a negative control. Cell counts on all polished surfaces showed significantly higher numbers, whereas some rough surface samples showed significantly lower numbers. We conclude that silicon nitride ceramics show no cytotoxic effects and should be considered for biomedical application owing to its favourable physiochemical properties, especially its superior resistance to mechanical stress, which would be useful for compression loaded conditions. Polished surfaces would appear to promote advanced biocompatibility.

The general skull morphology of the head of the Cavalier King Charles Spaniel (CKCS) was examined and compared with cephalometric indices of brachycephalic, mesaticephalic, and dolichocephalic heads. Measurements were taken from computed tomography images. Defined landmarks for linear measurements of were identified using three-dimensional (3D) models. The calculated parameters of the CKCS were different from all parameters of mesaticephalic dogs but were the same as parameters from brachycephalic dogs. However, the CKCS had a wider braincase in relation to length than in other brachycephalic breeds. Studies of the etiology of the chiari-like malformation in the CKCS should therefore focus on brachycephalic control groups. As Chari-like malformation has only been reported in brachycephalic breeds, its etiology could be associated with a higher grade of brachycephaly, meaning a shorter longitudinal extension of the skull. This has been suggested for other breeds.

Solar thermal energy systems often use optical imaging concentrators. The image size and shape produced in the focal plane of the concentrator system depends on the solar brightness distribution. Therefore, the forward scattering of solar radiation by the Earth’s atmosphere modifies the solar brightness distribution and creates a circumsolar aureole. The circumsolar ratio, the energy contained in the solar aureole compared to the total solar energy, can have an impact on the performance of these concentrating systems. Based on about 2300 sunshape measurements from sites in France, Germany and Spain made with a camera system developed by the German Aerospace Center (DLR), average solar brightness profiles with a circumsolar ratio of about 0%, 5%, 10%, 20%, 30%, and 40% were generated. These profiles are compared to the measurements taken by the Lawrence Berkeley Laboratory (LBL) in the late 1970’s and a commonly used limb-darkened solar brightness profile, as known from astronomy. A statistical analysis gives information on the frequency of occurrence of each of the average profiles. The profiles combined with the statistical weight should offer a numerical database for calculating the influence of variable conditions of the sunlight scattering on solar concentrating systems. Furthermore, a single average profile was calculated from the DLR data.

The palisade cartilage technique is suitable to manage difficult pathologic conditions in middle ear surgery. It was demonstrated that the palisade cartilage technique can be combined safely with titanium ossicular replacement prostheses. Regarding postoperative hearing results, the negative preselection of pathologic conditions must be considered.

Solar thermal energy systems often use optical imaging concentrators. The image size and shape produced in the focal plane of the concentrator system depends on the solar brightness distribution. Therefore, the forward scattering of solar radiation by the Earth’s atmosphere modifies the solar brightness distribution and creates a circumsolar aureole. The circumsolar ratio, the energy contained in the solar aureole compared to total energy, can impact the performance of these concentrating systems. Based on about 2300 sunshape measurements from sites in France, Germany, and Spain made with a camera system developed by the German Aerospace Center (DLR), average solar brightness profiles with a circumsolar ratio of about 0%, 5%, 10%, 20%, 30%, and 40% were generated. These profiles are compared to the measurements taken by the Lawrence Berkeley Laboratory (LBL) in the late 1970s and a commonly used limb-darkened solar brightness profile, as known from astronomy. A statistical analysis gives information on the frequency of occurrence of each of the average profiles. The profiles combined with the statistical weight should offer a numerical database for calculating the influence of variable conditions of the sunlight scattering on solar concentrating systems. Furthermore, a single average profile was calculated from the DLR data.

Silicon nitride (Si 3 N 4 ) is a ceramic known for its high performance characterized by fracture toughness, high wear resistance and low coefficient of friction. It has therefore been considered as a biomaterial especially for orthopaedic and dental indications. There is a controversy concerning the biocompatibility among the limited number of authors dealing with this material. Own investigations, applying the L929-fibroblast cell culture model revealed good biocompatibilty. The aim of this study is to verify these findings in the animal model. 36 cylinders of Si 3 N 4 and the established biomaterial aluminum oxide (Al 2 O 3 ) were implanted "press fit" into the lateral condyli of the femurs of 6 New Zealand white male rabbits (three implants per condylus, materials randomized). The right femur of each animal was prepared for microradiographs and grounded sections, the left for histological sections, respectively. Animals were divided into 2 groups with 3 rabbits each. One group was sacrificed after a period of 4 weeks and the other after 8 weeks. Morphometric assessment of bone-implant attachment was performed using a digital image analyzing system. Percentages of bone-implant attachment ranged from 44 to 82 %. There was no statistically different percentage of bone-implant attachment between Al 2 O 3 and Si 3 N 4 after 4 and 8 weeks, except in the histological section after 8 weeks of implantation. During the period of 4 to 8 weeks after implantation there was no significant decrease of bone-implant contact except for Al 2 O 3 in the histological sections. No local or generalized immuno-inflammatory reactions were observed. The lamellar bone in direct contact to the materials showed no histological evidence of round cell infiltration or giant cell reactions. Our investigations suggest that Si 3 N 4 shows good biocompatibility and presumably even better osseointegration than Al 2 O 3 .Key words: Silicon nitride, biocompatibility, femoral implantation, rabbit