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Biomedical subjects

F Witte

Publications and source records attributed to F Witte.

10 recordsLinked to original sources
PubMed2002

Bone turnover during distraction osteogenesis in an experimental sheep model.

Biochemical serum markers of osteoblastic activity and collagen turnover were measured in a sheep model of distraction osteogenesis. Significant increases of the bone formation marker osteocalcin were found during the first part of the consolidation phase and peaked at a time point equalling the distraction phase. Collagen turnover parameters pyridinoline and the specific type I collagen marker desoxypyridinoline consistently increased during the distraction and consolidation phases. While pyridinoline peaked at a time point similar to osteocalcin, desoxypyridinoline increased to a later stage in consolidation, indicating continuous turnover of bone-specific type I collagen. The results indicate a characteristic pattern of osteoblast cellular activation during distraction osteogenesis with possible consequences for the timing of treatment.

Amino Acids↗
PubMed2002

Use of an injectable calcium phosphate bone cement in the treatment of tibial plateau fractures: a prospective study of twenty-six cases with twenty-month mean follow-up.

OBJECTIVE: To evaluate the potential benefit of a new injectable mineral bone cement (Norian SRS, Cupertino, CA, USA) for the treatment of tibial plateau fractures OTA types 41.B2-B3 and C3. DESIGN: Prospective study with established protocol. SETTING: University hospital; university teaching hospital. PATIENTS: Twenty-six patients gave informed consent to participate in this study and were available for follow-up examinations. All patients had sustained intraarticular tibial plateau fracture types OTA B2-B3 and C3. All cases were followed with a mean follow-up time of 19.7 months (6 to 36 months, median eighteen months). INTERVENTION: Twenty-five cases were treated with open reduction, osteosynthesis with screws or plate, and injection of Norian SRS in the subchondral bone defect. One case had closed reduction, screw osteosynthesis, and percutaneous cement injection. MAIN OUTCOME MEASUREMENTS: Radiographs in two planes were evaluated prospectively at six, twelve, and twenty-six weeks postoperatively and at last follow-up using Rasmussen's radiologic score. Clinical parameters were measured at the same time intervals using Lysholm's and Tegner's knee scores. RESULTS: Two cases required early wound revisions because of sterile drainage. Two cases developed partial loss of reduction of the fracture between four and eight weeks after surgery, requiring revision surgery in one case (total complication rate 15.3 percent). No other patients had complications, and all other fractures healed without any displacement. The high mechanical strength of the cement allowed early weight bearing after a mean postoperative period of 4.5 weeks (1 to 6 weeks). CONCLUSIONS: An injectable mineral bone cement with high initial mechanical strength was used to fill bone defects in unstable tibial plateau fractures with good success. This material offers new perspectives in the treatment of tibial plateau fractures.

Adult↗
PubMed2001

[Osteosynthesis of fractures of the head of the tibia in advanced age. A matched-pair analysis].

In a retrospective study we analyzed 183 patients with tibial head fractures. 15 patients were older than 60 years at the time of accident, with a mean age of 69 (62-81) years. All patients had sustained an isolated tibial plateau fracture with a split-impression fracture in 10 patients, an impression fracture in 2 patients and a bicondylar fracture in 3 patients. The mean time to follow-up was 5.1 years. In a matched-pair-analysis this group was compared to a group of young patients with a mean age of 43 years (26-56) and identical lesions and surgical procedures. The mean time to follow-up in this group was 4.2 years. We observed that fractures at higher age resulted mostly from trivial accidents. Except from a prolonged inpatient time the initial course was comparable. In a 66 year-old woman early implant removal was necessary because of infection. Despite identical surgical treatment we observed a loss of reduction with incongruency of the plateau and deviation of the axis. Correspondingly older patients displayed a statistically significant threefold increase of osteoarthritis compared to younger patients. However, there was no clinical correlation using the Rasmussen, OAK and Lysholm score. Both groups displayed no statistical significant differences for the parameters function, stability and pain. According to the old age the only significant difference was a reduction of the Tegner score. Reduction and internal fixation of tibial plateau fractures in an elderly population displayed mostly a satisfactory clinical result within this 5-year period. The problem of loss of reduction and rapid osteoarthritis remains to be evaluated in a larger group over a longer period of time.

Aged↗
PubMed1989

Constructional constraint and its ecomorphological implications.

This paper analyses the role of constructional morphology in explaining the limitations on the interactions between an organism and those factors in its environment which are potentially relevant to its inclusive fitness. Constructional morphology deals with the relations between functionally relevant anatomical units (apparatuses or functional components) and thereby demonstrates what quantitative and qualitative constraints there are on combining units necessary for environmental interactions. It is argued that investigations on the relations between form and environment (ecological morphology) should (1) consider three types of relations: form-form, form-function and function-environment factor, (2) include behavioral and physiological ecology and (3) not be limited to a particular stage, but include as much of ontogeny as possible.

Anatomy, Comparative↗
PubMedDate not supplied

Structure and software tools of AIDA.

AIDA consists of a set of software tools to allow for fast development and easy-to-maintain Medical Information Systems. AIDA supports all aspects of such a system both during development and operation. It contains tools to build and maintain forms for interactive data entry and on-line input validation, a database management system including a data dictionary and a set of run-time routines for database access, and routines for querying the database and output formatting. Unlike an application generator, the user of AIDA may select parts of the tools to fulfill his needs and program other subsystems not developed with AIDA. The AIDA software uses as host language the ANSI-standard programming language MUMPS, an interpreted language embedded in an integrated database and programming environment. This greatly facilitates the portability of AIDA applications. The database facilities supported by AIDA are based on a relational data model. This data model is built on top of the MUMPS database, the so-called global structure. This relational model overcomes the restrictions of the global structure regarding string length. The global structure is especially powerful for sorting purposes. Using MUMPS as a host language allows the user an easy interface between user-defined data validation checks or other user-defined code and the AIDA tools. AIDA has been designed primarily for prototyping and for the construction of Medical Information Systems in a research environment which requires a flexible approach. The prototyping facility of AIDA operates terminal independent and is even to a great extent multi-lingual. Most of these features are table-driven; this allows on-line changes in the use of terminal type and language, but also causes overhead. AIDA has a set of optimizing tools by which it is possible to build a faster, but (of course) less flexible code from these table definitions. By separating the AIDA software in a source and a run-time version, one is able to write implementation-specific code which can be selected and loaded by a special source loader, being part of the AIDA software. This feature is also accessible for maintaining software on different sites and on different installations.

Database Management Systems↗
PubMedDate not supplied

Cystosarcoma phyllodes of the breast: prognostic significance of proliferation and apoptosis associated genes.

BACKGROUND: Cystosarcoma phyllodes (CP) is a rare fibroepithelial tumor of the breast. So far no valuable prognostic factors are available for predicting the biological behaviour and often unexpected clinical outcome of this tumor. PATIENTS AND METHODS: Using immuno-histochemistry, Mib-1 evaluated proliferative activity and expression of p53, Bcl-2, c-erbB1, c-erbB2, cytokeratin and vimentin were analysed in 17 benign and 12 malignant CP. RESULTS: Cell proliferation was significantly higher in malignant tumors compared to benign ones both in the epithelial and mesenchymal parts. In the epithelial part Bcl-2 positive cells were found more frequently in benign than in malignant lesions. Positive immunoreactivity for p53 was seen in only one malignant case. The reaction was positive in the both epithelial and mesenchymal compartments. Expression of c-erbB-proteins was not found in any case. The intermediate filament proteins indicate clearly the two components of the tumor. CONCLUSIONS: We concluded that increased proliferate activity and downregulation of Bcl-2 may be associated with dedifferentiation of cells and malignant progression. C-erbB-proteins are obviously not involved in carcinogenesis of CP.

Apoptosis↗
PubMedDate not supplied

Helicobacter pylori-induced hyperproliferation: relevance for gastric cancer development in connection with mutagenic factors.

AIMS: Current data on Helicobacter pylori induced regenerative hyperproliferation of the antral gastric mucosa and significance in cancer development are still under discussion and investigation. An improved method for evaluation of the regeneratory process in antral mucosa is introduced and compared with the conventional method used for determination of proliferating cells in perpendicular sections of the gastric mucosa. METHODS: Using a combination of immunohistochemistry and PAS-staining the expression of Ki-67 (MiB1)-proliferation associated antigen was analyzed in 50 Helicobacter pylori (Hp) positive and 35 negative biopsies of the gastric antrum. PAS-staining was performed to identify the proliferative zone of the antral gastric glands. The degree of inflammation was evaluated by grades on routinely H & E-stained slides. RESULTS: Proliferative activity is significantly increased in Hp-positive cases (p = 0.00095) compared to negative ones. By using the conventionally applied proliferation index, every nucleus has to be counted and the proliferation zone is identified by at least one positive stained nucleus. The method presented here seems to be easier because the proliferative zone is clearly identified by PAS staining of neutral glycoproteins characteristic for the proliferation zone of antral glands. The density of labeled nuclei is determined and is expressed as a proliferation factor. This factor gives more distinct values, is easier to evaluate and shows a better correlation with the helicobacter status and the degree of inflammation. These results are discussed in relation to the data from the literature and with a view to other relevant factors in the course of carcinogenesis, such as growth factors, mainly EGF, p53 mutation and role of apoptosis, genetic instability and local production of oxidants. CONCLUSION: Helicobacter pylori induces an increase of regenerative proliferation activity. Under these conditions the chance of mutation is increased and time for DNA repair reduced. This could be at least a part of multiple step carcinogenesis. The newly introduced combination of staining procedures (PAS/MiBI) allows a more differentiated evaluation of the proliferation zone and its widening. This method can be more easily handled in follow-up studies than the method using perpendicular sections because in this method heavy irregularities of gland pattern induced by accompanying inflammatory processes considerably hinder evaluation.

Cell Division↗