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Biomedical subjects

D Gebauer

Publications and source records attributed to D Gebauer.

At least 19 recordsLinked to original sources
PubMed2006

[On uniform social medical evaluation of performance capacity in orthopedic rehabilitation].

The need for standardized and unified performance capacity assessment in orthopedic rehabilitation has led to the attempt to use an existing standardized procedure. Graduated disease features have been defined which are relevant for work and their effects on performance capacity been formulated as rules. In this way so-called disease-conditioned performance capacities are obtained which help to identify problems in carrying out various activities. These activities can be directly assessed using tests. Appropriate tests are listed in a table.

Disability Evaluation↗
PubMed2002

The wireless monitoring of vital parameters: a design study.

This project shows the way vital parameters can be transmitted and visualized with no connecting cables necessary to the PDA. This was realized using a sensor developed with an integrated Bluetooth interface and a PDA, also equipped with Bluetooth. This radio connection can span up to 10 m, and parameters, such as pulse frequency, oxygen saturation in blood, ECG measurements and plethysmograms, can be transmitted. Using the software introduced in this work, the transmitted measurements can be displayed numerically or graphically on the PDA. The software simultaneously checks for any limits and sends a warning message if these limits are exceeded. All received data are additionally documented.

Computer Graphics↗
PubMed2000

[Effect of surgical laser on collagen-rich tissue].

The goal of this ex-vivo study was a controlled macroscopical and microscopical comparison of the immediate effects of surgical lasers on dense collagenous tissues. The investigation of the exact denaturizing effects following tissue interaction between lasers and collagenous fibers are of importance for a better understanding of the observed and described healing process. Partial tenotomies were performed ex vivo on sixty tendons of the flexor digitorum profundus muscle of New Zealand White Rabbits using four surgical lasers (Holmium:YAG-, Erbium:YAG-, Neodym:YAG-, and CO2-Laser). The tendons were evaluated macroscopically, histologically and observations were made on the surgical handling of the lasers during the procedure. The choice of lasers allowed the comparison of a wide spectrum of wavelengths (gamma = 1.0 to 10.6 microns). In addition, beam delivery modalities were compared to each other (focus vs. contact). The pulse (frequency and power) was varied within each laser. Other parameters including focus size, absorption, dispersion, and thermal tissue conductivity were maintained constant in this test arrangement in order to allow a later comparison between the observed areas of denaturated collagen. The macroscopical and histological results showed great differences in the effects of the four lasers. Even within each single laser group, the results varied greatly with the choice of variable parameters. Holmium:YAG- and CO2-Laser can produce similar areas of collagen denaturation. When comparing specimens with similar areas of collagen denaturation induced by different laser types, different amounts of charring were observed. Erbium:YAG-Laser tenotomies showed generally inhomogeneous denaturation areas, while tenotomies with Neodym: YAG-Laser used in continuous mode resulted in significant charring and tissue retraction in the area of interaction. These observations help in defining the combination of parameters with which Holmium:YAG-, Erbium:YAG-, and CO2-Lasers can be used for transsection of dense collagenous tissues. In addition, these histological results as well as already published observations on healing patterns following laser surgery allow for the formulation of a hypothesis on the effects of laser in the wound healing process.

Animals↗
PubMed2000

Optical mapping of BAC clones from the human Y chromosome DAZ locus.

The accurate mapping of clones derived from genomic regions containing complex arrangements of repeated elements presents special problems for DNA sequencers. Recent advances in the automation of optical mapping have enabled us to map a set of 16 BAC clones derived from the DAZ locus of the human Y chromosome long arm, a locus in which the entire DAZ gene as well as subsections within the gene copies have been duplicated. High-resolution optical mapping employing seven enzymes places these clones into two contigs representing four distinct copies of the DAZ gene and highlights a number of differences between individual copies of DAZ.

Chromosome Mapping↗
PubMed1999

Abalone (Haliotis tuberculata) hemocyanin type 1 (HtH1). Organization of the approximately 400 kDa subunit, and amino acid sequence of its functional units f, g and h.

We have identified two separate hemocyanin types (HtH1 and HtH2) in the European abalone Haliotis tuberculata. HtH1/HtH2 hybrid molecules were not found. By selective dissociation of HtH2 we isolated HtH1 which, as revealed by electron microscopy and SDS/PAGE, is present as didecamers of a approximately 400 kDa subunit. Immunologically, HtH1 and HtH2 correspond to keyhole limpet hemocyanin (KLH)1 and KLH2, respectively, the two well-studied hemocyanin types of the closely related marine gastropod Megathura crenulata. On the basis of limited proteolytic cleavage, two-dimensional immunoelectrophoresis, SDS/PAGE and N-terminal sequencing, we identified eight different 40-60 kDa functional units in HtH1, termed HtH1-a to HtH1-h, and determined their linear arrangement within the elongated subunit. From Haliotis mantle tissue, rich in hemocyanin-producing pore cells, we isolated mRNA and constructed a cDNA library. By expression screening with HtH-specific rabbit antibodies, a cDNA clone was isolated and sequenced which codes for the three C-terminal functional units f, g and h of HtH1. Their sequences were aligned to those available from other molluscs, notably to functional unit f and functional unit g from the cephalopod Octopus dofleini. HtH1-f, which is the first sequenced functional unit of type f from a gastropod hemocyanin, corresponds to functional unit f from Octopus. Also functional unit g from Haliotis and Octopus correspond to each other. HtH1-h is a gastropod hemocyanin functional unit type which is absent in cephalopods and has not been sequenced previously. It exhibits a unique tail extension of approximately 95 amino acids, which is lacking in functional units a to g and aligns with a published peptide sequence of 48 amino acids from functional unit h of Helix pomatia hemocyanin. The new Haliotis sequences are discussed with respect to their counterparts in Octopus, the 15 A three-dimensional reconstruction of the KLH1 didecamer from electron micrographs, and the recent 2.3 A X-ray structure of functional unit g from Octopus hemocyanin.

Amino Acid Sequence↗
PubMed1998

Identification of a novel mRNA-associated protein in oocytes of Pleurodeles waltl and Xenopus laevis.

Amphibian oocytes accumulate a large pool of mRNA molecules for future embryonic development. Due to their association with specific proteins the stored maternal RNAs are translationally repressed. The identification of these RNA-binding proteins and the characterization of their functional domains may contribute to the understanding of the translational repression mechanisms and the subsequent activation processes during early embryogenesis. Here we present the complete Pleurodeles cDNA sequence of a cytoplasmic protein which is present in oocytes, eggs, and very early cleavage stage embryos but undetectable in postcleavage embryo and adult tissues. The predicted molecular mass of the protein is 55 kDa and the apparent molecular mass as determined by SDS-PAGE, 68 kDa. The deduced amino acid sequence reveals proline- and serine-rich domains in the aminoterminal part as well as two RGG boxes which represent characteristic motifs of several RNA-binding proteins. No distinct homologies to the consensus RNA recognition motif were found. The 55-kDa protein was recovered in cytoplasmic ribonucleoprotein (RNP) particles containing poly(A)+ RNA. It was therefore termed RAP55 for mRNA-associated protein of 55 kDa. However, a direct interaction of RAP55 with mRNA could not be demonstrated by UV-crosslinking experiments, indicating that it is bound to mRNP complexes via protein-protein interactions. RAP55 is evolutionarily conserved since antibodies raised against a recombinant Pleurodeles RAP55 fragment recognize the protein from Pleurodeles and Xenopus. The expression pattern and intracellular distribution of RAP55 suggest that it is part of those mRNP particles which are translationally repressed during oogenesis and become activated upon progesterone-induced oocyte maturation.

Amino Acid Sequence↗
PubMed1998

Changes in cadaveric cancellous vertebral bone strength in relation to time. A biomechanical investigation.

STUDY DESIGN: A biomechanical study was conducted during a 3.5-day period to test for changes occurring in pullout strengths of cancellous screws inserted into human cadaveric vertebral bodies. OBJECTIVES: To quantify, within the testing time of 3.5 days, the possible changes to the mechanical properties of cadaveric vertebral bodies, resulting from structural degradation caused by postmortem, time-dependent, autolytic processes during mechanical testing of implant-bone biomechanics. SUMMARY OF BACKGROUND DATA: Biomechanical testing of whole spinal implants and analysis of the screw-bone interface of spinal implants is an area of clinical interest that frequently requires the use of cadaveric spine specimens. Changes in vertebral bone properties during the testing period may invalidate experimental results, but no data are available on degradation of bone during the testing period. METHODS: Anterior oblique cancellous screws were inserted into human vertebral bodies from which the ventral cortex had been removed. The pullout strength was measured at 0, 24, 60, and 84 hours after insertion. The tests were performed on 48 human vertebral bodies, which were stored by freezing to -23 C, thawed for testing, and kept at room temperature during the testing time for as long as 84 hours. RESULTS: The axial pullout strength showed no statistically significant change during 84 hours (P = 0.15). There were no significant differences attributable to vertebral level from T4 to L4, probably because the ventral cortices had been removed (P = 0.7). CONCLUSIONS: During 3.5 days, there were no changes in pullout strength of vertebral cancellous bone. In biomechanical studies during a maximum period of 3 days with a small number of cadaveric spines (e.g., four spine specimen) the time-dependent changes in pullout strength play a less significant role than do the interspine differences. Interspine differences should be regarded as an important factor to be considered in the design of biomechanical tests.

Autolysis↗
PubMed1998

Ultraflexible vesicles, Transfersomes, have an extremely low pore penetration resistance and transport therapeutic amounts of insulin across the intact mammalian skin.

New vehicles for the non-invasive delivery of agents are introduced. These carriers can transport pharmacological agents, including large polypeptides, through the permeability barriers, such as the intact skin. This capability depends on the self-regulating carrier deformability which exceeds that of the related but not optimized lipid aggregates by several orders of magnitude. Conventional lipid suspensions, such as standard liposomes or mixed lipid micelles, do not mediate a systemic biological effect upon epicutaneous applications. In contrast to this, the properly devised adaptable carriers, when administered on the intact skin, transport therapeutic amounts of biogenic molecules into the body. This process can be nearly as efficient as an injection needle, as seen from the results of experiments in mice and humans with the insulin-carrying vesicles. The carrier-mediated transcutaneous insulin delivery is unlikely to involve shunts, lesions or other types of skin damage. Rather than this, insulin is inferred to be transported into the body between the intact skin cells with a bio-efficiency of at least 50% of the s.c. dose action.

Administration, Cutaneous↗
PubMed1996

A monoclonal antibody against DNA topoisomerase II labels the axial granules of Pleurodeles lampbrush chromosomes.

By immunizing Balb/c mice with oocyte nuclei of Pleurodeles waltl we obtained a monoclonal antibody, mAb 4A6, that labels distinct globular domains of the lampbrush chromosomal axes of Pleurodeles. These domains are found at corresponding sites of homologous chromosomes, often at telomeric and putative centromeric regions, and appear to be devoid of DNA. Because of these characteristic features it is most likely that the mAb 4A6-positive domains correspond to the central part of the "axial granules" of urodelan lampbrush chromosomes. In immunoblotting analyses mAb 4A6 reacts with a nuclear antigen of approximately Mr 180000 and a structurally nonrelated cytoplasmic protein of Mr 98000, which was not characterized any further. Comparative immunofluorescence and immunoblotting studies with mAb 4A6 and an antiserum against DNA topoisomerase II (topo II) as well as immunodepletion experiments demonstrated that the nuclear 4A6 antigen is topo II. Our results indicate that topo II is not a constituent of a continuous, loop-anchoring scaffold in lampbrush chromosomes of Pleurodeles but, rather, is restricted to the axial granules.

Animals↗
PubMed1996

Localization of a high molecular weight form of DNA topoisomerase I in amphibian oocytes.

Xenopus oocytes express a 165 kDa variant of DNA topoisomerase I (topo I) as opposed to the canonical 110 kDa form of somatic cells (Richard and Bogenhagen, Dev. Biol. 146: 4-11, 1991). By immunofluorescence microscopy using variant-specific antibodies we show that this high molecular weight form is associated with lampbrush chromosome loops and the inner regions of the amplified nucleoli. Inhibition of topo I-activity by either Camptothecin-treatment or microinjection of neutralizing antibodies resulted in loop retraction and the condensation of chromosomes and amplified nucleoli. These data indicate that the oocyte-specific 165 kDa form of topo I is involved in transcriptional processes mediated by RNA polymerase I and II and is therefore functionally equivalent to the somatic cell 110 kDa counterpart.

Animals↗
PubMed1989

Micromotions in the primary fixation of cementless femoral stem prostheses.

Thirty cementless femoral stems of six different types of hip endoprostheses were implanted in femurs taken at autopsy and underwent static loading and afterwards dynamic loading of 50,000 cycles to simulate walking during the early months after implantation. After that, the static load tests were performed again. During both static load series a certain amount of micromotion between stem and implantation bed occurred in the frontal and sagittal planes and also during rotation. The six prostheses exhibited clearly differing results. The influence of dynamic load on the extent of micromotion was small.

Bone Cements↗
PubMed1987

[Neurophysiological and biomechanical analysis of a gymnastics accident with high transverse paralysis. An example of a sports medicine research study in the area of prevention of sports accidents].

The development of preventive provisions is an important topic of sport accident research. We demonstrate the stepwise procedure of judging a provision taking the analysis of a gymnastic exercise. This includes determination of the inner and outer reasons of accidents, the biomechanical conditions of the exercise and leads to mathematical and experimental simulation of the dangerous movement. The specific exercise we studied was the efficiency of a coach in protecting position for the handstand somersault with 1 1/2 breakneck leap. The reaction ability of the coach during the exercise and his force capacity to prevent an accident is explored by a newly developed reaction time analyzer and by a catapult apparatus throwing a dummy. Our results show the inadequacy of the prevention provision of a coach in protecting position for the special gymnastic exercise.

Accident Prevention↗
PubMed1983

[Extreme loading as cause of aseptic loosening of the total hip endoprosthesis socket and the resultant therapeutic consequences].

An analysis of the extent of damage in explanted endoprostheses of the hip showed massive destructions of the implanted components, such as fractures of the socket etc. For this reason, the authors designed a mathematical model of the extremity for which a prosthesis is designed; this model can simulate, inter alia, extreme loads of the joint occurring, for example, when a person falls. Self-experiments were helpful in determining the load exercised on the hip joint under such extreme conditions and in defining the effects on implanted joint material and the interface between bone and bone cement. Besides the influence of the body weight and the height of a fall, we also investigated dependence on attenuation promoted by different kinds of shoeware. These extreme loads in everyday life, which result in an excess stress of the materials and the interface, provide a good explanation for the aseptic loosening of the primarily well-fixed socket. From the therapeutic point of view these results suggest that such extreme burdening should be avoided during the time in which repair processes take place to gradually reduce the heat necroses in the osseous bed of the acetabulum which are due to the cement, by exercising a partial load only for three months after the operation rather than applying the full load too early. Attenuation of shock achieved by the use of various shoe materials was studied in self-experiments in which the researcher allowed himself to fall from different heights on to an outstretched leg while wearing different types of shoes.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
PubMed1980

[X-ray transparency of common orthopedic casts].

X-ray permeability is one of the important criterions which qualify a material as orthopedic cast. By using a phantom (amputated human lower leg) standardized conditions were created to compare the five customary casts: Cellamin, Lightcase II, Hexcelite, Neofrakt and Baycast. For judging the perceptibility of osseous structures, especially the details of the fracture, the lower and the upper number of clinically used layers were considered. The blank tested valuation showed the well-known advantages of the plastic materials in comparison with plaster of Paris. Within the group of the plastic materials distinct differences were also found.

Calcium Sulfate↗