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Dive into the research topics where Hermann Seifert is active.

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Featured researches published by Hermann Seifert.


Hippocampus | 2010

Modulation of neurogenesis by targeted hippocampal irradiation fails to affect kindling progression.

Anton Pekcec; Matthias Lüpke; Rolf Baumann; Hermann Seifert; Heidrun Potschka

Changes in the rate of dentate granule cell neurogenesis and in the fate of newborn granule cells have been implicated in the development and progression of epilepsies. Strategies to normalize neurogenesis in chronic epilepsy models are thought to increase our understanding of the functional consequences of aberrant neurogenesis in the epileptic brain. Therefore, we modulated neurogenesis in an amygdala kindling paradigm in rats by targeted irradiation of the hippocampus using a medical linear accelerator device. Selective irradiation normalized the hippocampal cell proliferation rate in kindled animals. Both, in kindled and nonkindled rats the number of BrdU/NeuN‐labeled newborn neurons was reduced in response to irradiation. Whereas kindling resulted in a pronounced increase in the number of neuroblasts identified based on doublecortin‐labeling, irradiation prevented the expansion of the neuroblast population. Moreover, irradiation counteracted the kindling‐associated increase in hilar basal dendrites, and kept the fraction of cells with basal dendrites at control levels. Despite the efficacious modulation of neurogenesis, irradiation did not affect the rate of kindling progression. Both, the number of stimulations as well as the cumulative afterdischarge duration to reach respective seizure stages were comparable in animals with and without irradiation. In addition, pre‐ and postkindling thresholds as well as seizure parameters recorded at threshold stimulation remained unaffected by irradiation. In conclusion, the fact that the efficacious modulation of neurogenesis by irradiation did not exert any effects on kindling acquisition and kindled seizures suggests that newborn neurons do not critically contribute to the hyperexcitable state in the chronic epilepsy model used.


BMC Veterinary Research | 2012

Periodontal biomechanics: finite element simulations of closing stroke and power stroke in equine cheek teeth

Vanessa Cordes; Matthias Lüpke; Moritz Gardemin; Hermann Seifert; Carsten Staszyk

BackgroundIn equine dentistry periodontal diseases, especially periapical inflammation, are frequently occurring problems. Anachoresis is believed to be the most common cause for the development of such disorders. Nevertheless, there is still no substantiated explanation why settlement of pathogen microorganisms occurs in equine periodontal tissues. It is expected that excessive strains and stresses occurring in the periodontal ligament (PDL) during the horse’s chewing cycle might be a predisposing factor. In this study this assumption was examined by finite element (FE) analyses on virtual 3-D models of equine maxillary and mandibular cheek teeth, established on the basis of μCT datasets. Calculations were conducted both under conditions of closing and power stroke.ResultsResults showed a uniform distribution of low stresses and strain energy density (SED) during closing stroke, whereas during power stroke an occurrence of high stresses and SED could be observed in the PDL near the alveolar crest and in periapical regions.ConclusionThe concentration of forces during power stroke in these specific areas of the PDL may cause local tissue necrosis and inflammation and thus establish a suitable environment for the settlement of microorganisms.


BMC Veterinary Research | 2013

Functional magnetic resonance imaging of the ascending stages of the auditory system in dogs

Jan-Peter Bach; Matthias Lüpke; Peter Dziallas; Stefan Uppenkamp; Hermann Seifert; Ingo Nolte

BackgroundFunctional magnetic resonance imaging (fMRI) is a technique able to localize neural activity in the brain by detecting associated changes in blood flow. It is an essential tool for studying human functional neuroanatomy including the auditory system. There are only a few studies, however, using fMRI to study canine brain functions. In the current study ten anesthetized dogs were scanned during auditory stimulation. Two functional sequences, each in combination with a suitable stimulation paradigm, were used in each subject. Sequence 1 provided periods of silence during which acoustic stimuli could be presented unmasked by scanner noise (sparse temporal sampling) whereas in sequence 2 the scanner noise was present throughout the entire session (continuous imaging). The results obtained with the two different functional sequences were compared.ResultsThis study shows that with the proper experimental setup it is possible to detect neural activity in the auditory system of dogs. In contrast to human fMRI studies the strongest activity was found in the subcortical parts of the auditory pathways. Especially sequence 1 showed a high reliability in detecting activated voxels in brain regions associated with the auditory system.ConclusionThese results indicate that fMRI is applicable for studying the canine auditory system and could become an additional method for the clinical evaluation of the auditory function of dogs. Additionally, fMRI is an interesting technique for future studies concerned with canine functional neuroanatomy.


BMC Veterinary Research | 2014

Actinobacillus pleuropneumoniae challenge in swine: diagnostic of lung alterations by infrared thermography

Anne Menzel; Martin Beyerbach; Carsten Siewert; Melanie Gundlach; Doris Hoeltig; Robert Graage; Hermann Seifert; Karl-Heinz Waldmann; Jutta Verspohl; Isabel Hennig-Pauka

BackgroundActinobacillus pleuropneumoniae (A.pp.) is the causative agent of porcine pleuropneumonia leading to high economic losses in the pig industry. Infrared thermography (IRT) of the thorax might offer a new method to select swine with lung alterations for further diagnostics.In this study 50 german landrace pigs were infected with A.pp. in an established model for respiratory tract disease, while 10 healthy pigs served as control animals. To avoid drift errors during IR measurements absolute skin temperatures and temperature differences between a thoracal and an abdominal region were assessed for its diagnostic validity.ResultsIRT findings during the course of experimental A.pp.-infection were verified by computed tomography (CT) before and on days 4 and 21 after infection. Significant correlations were found between clinical scores, CT score and lung lesion score. Ambient temperature, body temperature and abdominal surface temperature were factors influencing the skin surface temperature of the thorax. On day 4 but not on day 21 after infection the right thoracal temperature was significantly higher and the difference between a thoracal region in the height of the left 10th vertebra and an abdominal region was significantly lower in infected pigs than in control pigs. At a cut off of 28°C of right thoracal temperature the specificity of the method was 100% (CI 95%: 69-100%) and the sensitivity 66% (CI 95%: 51-79%).At a cut off of 2°C temperature difference between thoracal and abdominal region on the left body site the specificity of the method was 100% (CI 95%: 69-100%) and the sensitivity 32% (CI 95%: 19-47%) with all control pigs detected negative.Orientation for lung biopsy by IRT resulted in 100% specificity and sensitivity (CI 95%: 69-100%) of bacteriological examination of tissue samples during the acute stage of infection.ConclusionIRT might be a valuable tool for the detection of inflammatory lung alterations in pigs, especially during the acute stage of infection and if ambient temperatures are constant during individual measurements. External and internal factors interfere with this method, so that its application in the field might be restricted to a selection of pigs for further diagnostic with adequate specificity.


Meat Science | 2005

Extraction of meat juices for isotopic analysis

Ines Thiem; Matthias Lüpke; Hermann Seifert

So far no standard procedure exists to obtain water of meat for isotopic (18)O/(16)O-water analysis. Fast extraction via heating the tissues is possible when considering certain boundary conditions. A specially designed vessel was tested with water and was then used for meat juice extraction. The reproducibility (σ) of δ(18)O-values was 0.12‰. Meat samples of six different species were analysed. Water of pork samples was extracted after open storage. Here, decreases in meat weight correspond to decreases in extract yield and to an increase in the (18)O/(16)O-ratio. The mean water contents in extracts was almost constant [93.2±0.05 wt% (p>0.05)]. The technique offers an opportunity to develop an automatic, mobile extraction device and to obtain extracts with no further influences on their quality. This method could also be useful for the determination of meat quality attributes as cooking loss or drip without evaporative losses.


Materials | 2017

Osteointegration of Porous Poly-ε-Caprolactone-Coated and Previtalised Magnesium Implants in Critically Sized Calvarial Bone Defects in the Mouse Model

Michael Grau; Christian Seiler; Laura Roland; Julia Matena; Claudia Windhövel; Michael Teske; Hugo Murua Escobar; Matthias Lüpke; Hermann Seifert; Nils-Claudius Gellrich; Heinz Haferkamp; Ingo Nolte

Metallic biomaterials are widely used in maxillofacial surgery. While titanium is presumed to be the gold standard, magnesium-based implants are a current topic of interest and investigation due to their biocompatible, osteoconductive and degradable properties. This study investigates the effects of poly-ε-caprolactone-coated and previtalised magnesium implants on osteointegration within murine calvarial bone defects: After setting a 3 mm × 3 mm defect into the calvaria of 40 BALB/c mice the animals were treated with poly-ε-caprolactone-coated porous magnesium implants (without previtalisation or previtalised with either osteoblasts or adipose derived mesenchymal stem cells), porous Ti6Al4V implants or without any implant. To evaluate bone formation and implant degradation, micro-computertomographic scans were performed at day 0, 28, 56 and 84 after surgery. Additionally, histological thin sections were prepared and evaluated histomorphometrically. The outcomes revealed no significant differences within the differently treated groups regarding bone formation and the amount of osteoid. While the implant degradation resulted in implant shifting, both implant geometry and previtalisation appeared to have positive effects on vascularisation. Although adjustments in degradation behaviour and implant fixation are indicated, this study still considers magnesium as a promising alternative to titanium-based implants in maxillofacial surgery in future.


Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren | 2012

Phantomuntersuchungen an einem hochauflösenden CT zur Ex-vivo-Darstellung von degradierbaren Magnesiumimplantaten und simulierten periimplantären Knochenschichten in Kaninchentibiae

J Schulman; F. Goblet; D. Bormann; W. Stiller; Hermann Seifert

PURPOSE Evaluation of the suitability of the high-resolution CT XtremeCT for ex vivo imaging of degradable magnesium implants with simulated peri-implant bone formation in rabbit tibiae and development of a method for calibrating the mass concentration of a magnesium alloy in an implant volume. MATERIALS AND METHODS Using specially designed phantoms, degradable magnesium implants of the alloys LAE442, ZEK100, AX30 and MgCa 0.8 %, without coating and with peri-implant bone formation simulated by a coating, as well as rabbit tibiae were scanned. CT numbers and the contrast-to-noise-ratio (CNR) of the studied materials were determined. The visual distinction between implant and coating was evaluated. To calibrate the implant density, exemplary LAE442 pins with different mass concentrations were scanned using a specially constructed phantom. Subsequently, CT numbers corresponding to the appropriate mass concentration were determined. RESULTS The implants, coating and substantia corticalis showed a similar density. Visual distinction between coating and implant was strongly dependent on the respective magnesium alloy and chosen scan parameter. A CNR of at least 0.2 was required for a distinction between implant and coating. For the mass concentration, a high CT number linearity (R2=0.99) throughout the measuring range (1811-1273 mg/cm3 LAE442) was found. CONCLUSION As expected, the XtremeCT is primarily suitable for the imaging of bone tissue and implants. Good visual distinction of peri-implant bone formation on magnesium implants in an ex vivo phantom model ranges from possible to difficult depending on the bone density and alloy composition.


Acta Veterinaria Hungarica | 2011

Optimising magnetic resonance image quality of the ear in healthy dogs

Davina Wolf; Matthias Lüpke; Thilo von Klopmann; Ingo Nolte; Hermann Seifert

The aim of this study was to develop an examination protocol for magnetic resonance imaging, in order to display diagnostically important information of the canine middle and inner ear. To ensure that this protocol could also be used as a basis for determining pathological changes, the anatomical structures of the ear were presented in detail. To minimise stress through anaesthesia in live animals, preliminary examinations were carried out on four dog cadavers. During these initial examinations, three-dimensional (3D) sequences proved to be superior to two-dimensional ones. Therefore, only 3D sequences were applied for the main examinations performed on six clinically healthy Beagles. The anonymised MR images were rated by three experienced reviewers using a five-point scale. The most valuable sequence was a T2-weighted CISS sequence (TR = 16.7 ms, TE = 8.08 ms). This sequence proved to be most suitable for illustrating the inner ear structures and enabled good tissue contrasts. The sequence ranked second best was also a T2-weighted DESS sequence (TR = 19 ms, TE = 6 ms), allowing the imaging of the tympanic cavity and enabling 3D reconstruction due to its isotropic voxels. Due to low contrast and strong noise, the other sequences (TSE, FISP, MP RAGE) were not suitable for anatomical illustration of the middle and inner ear.


Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren | 2018

Evaluation of the static magnetic field interactions for a newly developed magnetic ophthalmic implant at 3 Tesla MRI

Ann-Kathrin Bodenstein; Matthias Lüpke; Christian Seiler; Frank Goblet; Stephan Nikolic; Ulf Hinze; Boris N. Chichkov; Claudia Windhövel; Jan-Peter Bach; Lisa Harder; Hermann Seifert

PURPOSE  The purpose of this study is to analyze the static magnetic field interactions for an ophthalmic-magnetic shunt implant with a ferromagnetic steel plate in a thin silicon layer. The plate is used for opening of a valve flap. Ten different sizes of this steel plate were investigated to characterize the relationship between the size of the metal and the magnetic forces of the static magnetic field of a 3.0 T MRI. MATERIALS AND METHODS  The magnetic translation force Fz was quantified by determining the deflection angle using the deflection angle test (ASTM F 2052). The torque was qualitatively estimated by using a 5-point grading scale (0: no torque; + 4: very strong torque) according to Sommer et al. 11. For the visual investigation of the function of the metal plate both prototypes were positioned at the magnetic fields spatial gradient and at the magnets isocenter. The stitches were exposed to the thousandfold of the translational force by a dynamometer. RESULTS  The translational force was found to be 10 times greater than the weight of a single plate. The plates were exposed to a high torque (grade 3 to 4). The seams and the tissue withstood more than a thousandfold of the determined translational force. No spontaneous, uncontrolled opening of the valve flap was visible in the MRI, as a result of which the intraocular pressure could decrease considerably. CONCLUSION  Due to the small size of the plates the translational force and the torque will be compensated by the silicon layer and also by the fixation in the eye. KEY POINTS   · Magnetic forces will be compensated by silicon layer and fixation in the eye.. · The magnetic-ophthalmological implant is not restricted in its function by the MRI magnetic field.. · The ophthalmic magnetic shunt implant can be considered conditionally MRI-safe.. CITATION FORMAT · Bodenstein A, Lüpke M, Seiler C et al. Evaluation of the static magnetic field interactions for a newly developed magnetic ophthalmic implant at 3 Tesla MRI. Fortschr Röntgenstr 2019; 191: 209 - 215.


BMC Veterinary Research | 2016

Auditory functional magnetic resonance imaging in dogs--normalization and group analysis and the processing of pitch in the canine auditory pathways.

Jan-Peter Bach; Matthias Lüpke; Peter Dziallas; Stefan Uppenkamp; Hermann Seifert; Ingo Nolte

BackgroundFunctional magnetic resonance imaging (fMRI) is an advanced and frequently used technique for studying brain functions in humans and increasingly so in animals. A key element of analyzing fMRI data is group analysis, for which valid spatial normalization is a prerequisite. In the current study we applied normalization and group analysis to a dataset from an auditory functional MRI experiment in anesthetized beagles. The stimulation paradigm used in the experiment was composed of simple Gaussian noise and regular interval sounds (RIS), which included a periodicity pitch as an additional sound feature. The results from the performed group analysis were compared with those from single animal analysis. In addition to this, the data were examined for brain regions showing an increased activation associated with the perception of pitch.ResultsWith the group analysis, significant activations matching the position of the right superior olivary nucleus, lateral lemniscus and internal capsule were identified, which could not be detected in the single animal analysis. In addition, a large cluster of activated voxels in the auditory cortex was found. The contrast of the RIS condition (including pitch) with Gaussian noise (no pitch) showed a significant effect in a region matching the location of the left medial geniculate nucleus.ConclusionBy using group analysis additional activated areas along the canine auditory pathways could be identified in comparison to single animal analysis. It was possible to demonstrate a pitch-specific effect, indicating that group analysis is a suitable method for improving the results of auditory fMRI studies in dogs and extending our knowledge of canine neuroanatomy.

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Isabel Hennig-Pauka

University of Veterinary Medicine Vienna

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