Showing papers by "Cornelius Faber published in 2012"

A Novel Mouse Model of Staphylococcus aureus Chronic Osteomyelitis That Closely Mimics the Human Infection: An Integrated View of Disease Pathogenesis

Abstract: Osteomyelitis is a serious bone infection typically caused by Staphylococcus aureus . The pathogenesis of osteomyelitis remains poorly understood, mainly for lack of experimental models that closely mimic human disease. We describe a novel murine model of metastatic chronic osteomyelitis initiated after intravenous inoculation of S. aureus microorganisms. The bacteria entered bones through the bloodstream and, after an acute phase with progressive growth (first 2 weeks after infection), they remained at constant numbers for up to 56 days (chronic phase). Clinical signs of illness and systemic inflammation were apparent only during the acute phase. Bone destruction and remodeling processes were readily detectable by magnetic resonance and X-ray imaging 3 weeks after infection, and high levels of bone deformation were observed during the chronic phase. Histological examination of infected bones demonstrated suppurative inflammation with foci of intense bacterial multiplication and necrosis during acute infection and osteoclastic resorption accompanied by new woven bone formation during chronic infection. Transmission electron microscopy revealed S. aureus microorganisms forming microcolonies within the nonmineralized collagen matrix or located intracellularly within neutrophils. In summary, our mouse model of staphylococcal hematogenous osteomyelitis precisely reproduces most features of the human disease. Although the extent of lesions in the chronic phase was subject to variation, this model is ideal for testing and monitoring novel treatment modalities via noninvasive imaging.

Early detection of lung inflammation: Exploiting T1‐effects of iron oxide particles using UTE MRI

Abstract: At high magnetic fields diagnostic proton MRI of the lung is problematic, because of fast T relaxation. The application of superparamagnetic contrast agents and the exploitation of the corresponding T effect is inefficient with conventional MRI methods, which limits the early detection of lung diseases. However, a simple theoretical treatment shows that in the lung, by the use of ultra-short echo time sequences, T effects can be neglected while T1 shortening effects can be used for signal detection. In our study, we have applied a theoretically and experimentally optimized 3D ultra-short echo time sequence to lung phantoms and to a mouse model of lung inflammation, which was induced by systemic bacterial infection. Following the systemic application of very small superparamagnetic iron oxide nanoparticles, a significant signal increase in the lung of infected animals was detected already at 24 h postinfection, compared to control mice (17%, P < 0.001). Iron accumulation in the lung parenchyma as consequence of the host immune response was histologically confirmed. By conventional T- and T2-weighted imaging, neither structural changes nor formation of substantial edema were observed. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.

Evolution of a novel muscle design in sea urchins (Echinodermata: Echinoidea).

Abstract: The sea urchin (Echinodermata: Echinoidea) masticatory apparatus, or Aristotle's lantern, is a complex structure composed of numerous hard and soft components. The lantern is powered by various paired and unpaired muscle groups. We describe how one set of these muscles, the lantern protractor muscles, has evolved a specialized morphology. This morphology is characterized by the formation of adaxially-facing lobes perpendicular to the main orientation of the muscle, giving the protractor a frilled aspect in horizontal section. Histological and ultrastructural analyses show that the microstructure of frilled muscles is largely identical to that of conventional, flat muscles. Measurements of muscle dimensions in equally-sized specimens demonstrate that the frilled muscle design, in comparison to that of the flat muscle type, considerably increases muscle volume as well as the muscle's surface directed towards the interradial cavity, a compartment of the peripharyngeal coelom. Scanning electron microscopical observations reveal that the insertions of frilled and flat protractor muscles result in characteristic muscle scars on the stereom, reflecting the shapes of individual muscles. Our comparative study of 49 derived “regular” echinoid species using magnetic resonance imaging (MRI) shows that frilled protractor muscles are found only in taxa belonging to the families Toxopneustidae, Echinometridae, and Strongylocentrotidae. The onset of lobe formation during ontogenesis varies between species of these three families. Because frilled protractor muscles are best observed in situ, the application of a non-invasive imaging technique was crucial for the unequivocal identification of this morphological character on a large scale. Although it is currently possible only to speculate on the functional advantages which the frilled muscle morphology might confer, our study forms the anatomical and evolutionary framework for future analyses of this unusual muscle design among sea urchins.

Personality Functioning and the Cortical Midline Structures – An Exploratory fMRI Study

Abstract: Objective: Recent neuroscience studies explored the neuronal mechanisms underlying our sense of self. Thereby the cortical midline structures and their anterior and posterior regions have been shown to be central. What remains unclear though is how both, self and cortical midline structures, are related to the identity of the self which is of central importance in especially personality disorders. Methods: Conducting an exploratory study with a dimensional approach, we here compared subjects with high and low level of personality functioning and identity integration as measured in a standardized way in fMRI during both, emotionand reward-related tasks. Results: Low levels of personality functioning and identity integration were predicted by significantly decreased degrees of deactivation in the anterior and posterior cortical midline structures. Conclusions: Though exploratory our results show for the first time direct relationship between cortical midline structures and personality functioning in terms of identity integration. This does not only contribute to our understanding of the neuronal mechanism underlying self and identity but carries also major implications for the treatment of patients with personality disorders.