Biomedical subjects

Marcel Müller

Publications and source records attributed to Marcel Müller.

4 recordsLinked to original sources

PubMed2005

Computed Quality Assessment of MPEG4-compressed DICOM Video Data.

Digital Imaging and Communication in Medicine (DICOM) has become one of the most popular standards in medicine. This standard specifies the exact procedures in which digital images are exchanged between devices, either using a network or storage medium. Sources for images vary; therefore there exist definitions for the exchange for CR, CT, NMR, angiography, sonography and so on. With its spreading, with the increasing amount of sources included, data volume is increasing, too. This affects storage and traffic. While for long-time storage data compression is generally not accepted at the moment, there are many situations where data compression is possible: Telemedicine for educational purposes (e.g. students at home using low speed internet connections), presentations with standard-resolution video projectors, or even the supply on wards combined receiving written findings. DICOM comprises compression: for still image there is JPEG, for video MPEG-2 is adopted. Within the last years MPEG-2 has been evolved to MPEG-4, which squeezes data even better, but the risk of significant errors increases, too. Within the last years effects of compression have been analyzed for entertainment movies, but these are not comparable to videos of physical examinations (e.g. echocardiography). In medical videos an individual image plays a more important role. Erroneous single images affect total quality even more. Additionally, the effect of compression can not be generalized from one test series to all videos. The result depends strongly on the source. Some investigations have been presented, where different MPEG-4 algorithms compressed videos have been compared and rated manually. But they describe only the results in an elected testbed. In this paper some methods derived from video rating are presented and discussed for an automatically created quality control for the compression of medical videos, primary stored in DICOM containers.

Algorithms↗

PubMed2004

The Clinical Document Architecture (CDA) enables electronic medical records to wireless mobile computing.

The Clinical Document Architecture (CDA) has proved to be a valuable and powerful standard for a structured exchange of clinical documents between heterogeneous software systems like a Hospital Information System and a Physician Office System. In this paper we want to show how the CDA can additionally be used in order to enhance the Hospital Information System's functionality: each patient related document contained in or generated from the HIS can be converted to a CDA/XML document. With the XML/XSLT-based transformation methods, those documents can be device-specifically transformed. We use this method to display HIS-content on mobile devices like Personal Digital Assistants (PDAs) by extracting the respective data fields from the HIS database, converting them to a CDA/XML document, which is transformed and sent to the mobile devices using a wireless intranet connection. Preliminary results and users' comments are promising, but further evaluation will be necessary. Our approach shows a generic model how clinical data can be dis-played on different devices independently from the underlying HIS using CDA.

Computer Communication Networks↗

PubMed2002

Maturation of Pichia pastoris-derived recombinant pro-Der p 1 induced by deglycosylation and by the natural cysteine protease Der p 1 from house dust mite.

The mature cysteine protease from Dermatophgoides pteronyssinus, Der p 1, is a major house dust mite allergen. Its enzymatic activity has been shown to have pro-inflammatory effects that could also negatively influence efficacy of allergen-specific immunotherapy. The aim of this study was to express recombinant pro-Der p 1 (rpro-Der p 1) in the yeast Pichia pastoris and to study its maturation. Expression was achieved at a concentration ranging from 45 mg.L-1 (methanol-induced expression) to 168 mg.L-1 (constitutive expression). No significant spontaneous maturation of the secreted proenzyme was observed. rpro-Der p 1 with a sequence-based molecular mass of 34 kDa was hyperglycosylated by the yeast, migrating at 50-60 kDa on SDS/PAGE. Compared with its natural counterpart (nDer p 1), the recombinant proenzyme demonstrated decreased IgE reactivity, resulting in a 30-fold lower capacity to induce histamine release from human basophils. Decreased immunoreactivity was also shown by competitive RIA and sandwich ELISA with Der p 1-specific antibody reagents. CD spectra of rpro-Der p 1 and nDer p 1 revealed significant structural differences. Deglycosylation of rpro-Der p 1 with endoglycosidase H resulted in a decrease in apparent molecular mass from 50 kDa to 34 kDa, but did not affect nDer p 1. On removal of N-glycans from rpro-Der p 1, which harbours two putative N-glycosylation sites in both propeptide and mature sequence, the mature rDer p 1 appeared. This suggests that hyperglycosylation hampers spontaneous maturation. Maturation of the recombinant pro-enzyme was also achieved by addition of the active natural cysteine protease, nDer p 1. In conclusion, high-level expression of rpro-Der p 1 in P. pastoris results in a stable hypoallergenic proenzyme with potential for use in allergen-specific immunotherapy.

Allergens↗

PubMed2002

Guideline based structured documentation: the final goal?

Structured documentation of medical procedures facilitates information retrieval for research and therapy and may help to improve patient care. Most medical documents until today however consist mainly of unstructured narrative text. Here we present an application for endoscopy which is not only fully integrated into a comprehensive clinical information system, but which also supports various degrees of structuring examination reports. The application is used routinely in a German University hospital since summer 2000. We present the first unstructured version which permits storage of a free text report together with selected examination images. The next step added improved structure to the document using a catalogue of index terms. The practical advantages of selective patient retrieval are described. Today we use a version which supports fully structured, guideline based documentation of endoscopy reports in order to automatically generate essential classification codes and the narrative examination report All versions have advantages and disadvantages and we conclude that guideline based documentation may not be suitable for all endoscopy cases.

Documentation↗