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S Bartling

Publications and source records attributed to S Bartling.

5 recordsLinked to original sources

[3D-Visualisation of the middle ear by computer-assisted post-processing of helical multi-slice CT data].

Post-processing of CT-data allows non-invasive 3D-Visualisation of the middle ear for diagnosis and surgical planning. In this study different post-processing techniques and the clinical application of a 3D-postprocessing algorithm in a large number of patients are presented. 20 normal patients, 6 dissected temporal bones and 213 patients with suspected middle ear pathology were examined using a low-dosage Multi-Slice CT protocol. Virtual endoscopic views of the middle ear and 3D-images of the ossicles were generated using a standardised algorithm. Evaluation of the image quality was performed. The virtual views of the dissected temporal bones were compared to real views. In 32 patients high-quality 3D-models of the individual anatomical structures were generated and displayed using different visualisation techniques. The standardised and evaluated method enabled visualisation of the normal middle ear anatomy. Assessment of different pathologies, especially malformation, trauma, implants and postoperative alterations, was facilitated. The high-quality 3D-models allowed precise imaging of the anatomical structures. 3D-Visualisation of the middle ear using CT-data is beneficial for radiological diagnosis and surgical planning in cases of complex middle ear pathology as a complementary examination technique.

Adolescent↗

3D visualisation of the middle ear and adjacent structures using reconstructed multi-slice CT datasets, correlating 3D images and virtual endoscopy to the 2D cross-sectional images.

The 3D imaging of the middle ear facilitates better understanding of the patient's anatomy. Cross-sectional slices, however, often allow a more accurate evaluation of anatomical structures, as some detail may be lost through post-processing. In order to demonstrate the advantages of combining both approaches, we performed computed tomography (CT) imaging in two normal and 15 different pathological cases, and the 3D models were correlated to the cross-sectional CT slices. Reconstructed CT datasets were acquired by multi-slice CT. Post-processing was performed using the in-house software "3D Slicer", applying thresholding and manual segmentation. 3D models of the individual anatomical structures were generated and displayed in different colours. The display of relevant anatomical and pathological structures was evaluated in the greyscale 2D slices, 3D images, and the 2D slices showing the segmented 2D anatomy in different colours for each structure. Correlating 2D slices to the 3D models and virtual endoscopy helps to combine the advantages of each method. As generating 3D models can be extremely time-consuming, this approach can be a clinically applicable way of gaining a 3D understanding of the patient's anatomy by using models as a reference. Furthermore, it can help radiologists and otolaryngologists evaluating the 2D slices by adding the correct 3D information that would otherwise have to be mentally integrated. The method can be applied to radiological diagnosis, surgical planning, and especially, to teaching.

Adolescent↗

Expression of an Erwinia pectate lyase in three species of Aspergillus.

Transgenic filamentous fungi of the species Aspergillus niger, A. nidulans and A. awamori expressing and secreting Erwinia carotovora subsp. atroseptica pectate lyase 3 (PL3) were generated. Correct processing of the pre-enzyme was achieved using the A. niger pectin lyase A (PEL A) signal peptide. With the prepro-peptide of A. niger polygalacturonase II, secreted enzymes still possessed the 6- aa pro-sequence, indicating the importance of the conformation of the precursor protein for correct cleavage of the signal sequence. PL3 expression was markedly increased in media optimized for limited protease activity, and reached 0.4, 0.8 and 2.0 mg/l for expression in A. niger, A. awamori and A. nidulans, respectively. Glycans attached to the PL3 enzymes exhibited species-specific differences, and an increase of molecular mass coincided with reduced specific activities of the enzymes.

Amino Acid Sequence↗

Synergism between Erwinia pectate lyase isoenzymes that depolymerize both pectate and pectin.

Phytopathogenic Erwinia bacteria cause tissue maceration by secretion of pectinolytic enzymes such as pectate lyase (PL). Sequencing of overlapping genomic fragments from Erwinia carotovora subsp. atroseptica established the organization of a 7.5 kbp region encoding PL isoenzymes. Two intergenic regions of 656 and 645 bp separate three enzyme coding regions of 1125 bp exhibiting approximately 80% positional identity. The promoters of each of the three genes contain a segment with high homology to the binding sequence of the E. chrysanthemi KdgR transcription repressor, implying similar mechanisms of gene regulation in the two bacterial species. Separate expression of the pel genes in the Escherichia coli-pT7-7 system and purification of their products yielded PLs at 7-33 mg (I culture)-1 with greater than 95% purity. Availability of the recombinant enzymes allowed determination of the kinetic differences amongst the PL isoforms, PL1, PL2 and PL3. The results show that PL is not strictly confined to depolymerization of pectate since each isoenzyme more readily degrades 31% esterified pectin. Addition of isoenzyme combinations revealed no synergism with respect to degradation of pectate or 31% esterified pectin. However, addition of enzyme combinations containing PL3 enhanced the activity towards 68% esterified pectin, against which individual PL activities were low, by up to 64%. These data suggest that the combination of PL isoenzymes extends the range of pectic substrates which the bacterium can degrade.

Amino Acid Sequence↗