Biomedical subjects

Rainer Staudenmaier

Publications and source records attributed to Rainer Staudenmaier.

11 recordsLinked to original sources

PubMed2006

Round window stimulation with an implantable hearing aid (Soundbridge) combined with autogenous reconstruction of the auricle - a new approach.

BACKGROUND: Congenital malformations of the auricle are often combined with atresia of the outer ear canal and malformations of the ossicles, representing aesthetic as well as functional deficits. Optimal treatment should therefore address both aspects equally. This report describes a new approach, combining the reconstruction of the auricle with implantation of an active middle ear hearing aid, stimulating the round window membrane. METHOD: A 33-year-old male patient, with bilateral ear microtia, fibrous atresia of the external ear canals and malformation of the ossicles due to Treacher Collins-Franceschetti syndrome was included in the study. In stage one, the cartilage framework of the new auricle, made of autogenous rib cartilage, was fabricated and implanted. During stage two, the auricle was elevated, a retro-auricular sulcus was formed and a Vibrant MED-EL Soundbridge device was implanted. The transducer was coupled to the round window membrane. RESULTS: Both functional and aesthetical results were favourable. Aided thresholds were between 15 and 30 dB in the frequency range of 0.75-6 kHz, monosyllabic word understanding at 65 dB SPL increased from 0 to 80%. DISCUSSION: Combining aesthetic and functional rehabilitation, autogenous reconstruction of a new auricle together with the implantation of an active middle ear hearing aid, coupled to the round window membrane, is a promising new approach.

Adult↗

PubMed2006

Long-term stable fibrin gels for cartilage engineering.

It is essential that hydrogel scaffold systems maintain long-term shape stability and mechanical integrity for applications in cartilage tissue engineering. Within this study, we aimed at the improvement of a commercially available fibrin gel in order to develop a long-term stable fibrin gel and, subsequently, investigated the suitability of the optimized gel for in vitro cartilage engineering. Only fibrin gels with a final fibrinogen concentration of 25mg/ml or higher, a Ca(2+) concentration of 20mm and a pH between 6.8 and 9 were transparent and stable for three weeks, the duration of the experiment. In contrast, when preparing fibrin gels with concentrations out of these ranges, turbid gels were obtained that shrank and completely dissolved within a few weeks. In rheological characterization experiments, the optimized gels showed a broad linear viscoelastic region and withstood mechanical loadings of up to 10,000 Pa. Bovine chondrocytes suspended in the optimized fibrin gels proliferated well and produced the extracellular matrix (ECM) components glycosaminoglycans and collagen type II. When initially seeding 3 million cells or more per construct (5mm diameter, 2mm thick), after 5 weeks of culture, a coherent cartilaginous ECM was obtained that was homogenously distributed throughout the whole construct. The developed fibrin gels are suggested also for other tissue engineering applications in which long-term stable hydrogels appear desirable.

Animals↗

PubMed2006

Cellulose-based scaffold materials for cartilage tissue engineering.

Non-woven cellulose II fabrics were used as scaffolds for in vitro cartilage tissue engineering. The scaffolds were activated in a saturated Ca(OH)(2) solution and subsequently coated with a calcium phosphate layer precipitated from a supersaturated physiological solution. Chondrocyte cell response and cartilage development were investigated. The cell adherence was significantly improved compared to untreated cellulose fabrics, and the proliferation and vitality of the adhered chondrocytes were excellent, indicating the biocompatibility of these materials. A homogeneous distribution of the seeded cells was possible and the development of cartilageous tissue could be proved. In contact with a physiological chondrocyte solution, calcium is expected to be leached out from the precipitated layer, which might lead to a microenvironment that triggers the development of cartilage in a way similar to cartilage repair in the vicinity of subchondral bone.

Animals↗

PubMed2005

Cytotoxic and genotoxic effects of resin monomers in human salivary gland tissue and lymphocytes as assessed by the single cell microgel electrophoresis (Comet) assay.

Malignant tumors of the three major pairs and the numerous minor salivary glands in humans are rare, and little is known about their various etiologies. Considering the fact that resin monomers from dental restorative materials are released into the saliva and diffuse into the tooth pulp or gingiva, mucosa, and salivary glands, this may potentially contribute to tumorigenesis. Resin monomers may also be reabsorbed and reach the circulating blood as well. Whereas the cytotoxic potential of some components has been clearly documented, data on genotoxicity in human target cells require further investigation. In the present study, genotoxic and cytotoxic effects of three common methacrylates are investigated in human samples of salivary glands and peripheral lymphocytes. The Comet assay was used to quantify DNA single strand breaks, alkali labile and incomplete excision repair sites in salivary gland probes and lymphocytes of 10 volunteers. The xenobiotics investigated were triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and 2-hydroxyethylmethacrylate (HEMA), with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and dimethyl sulfoxide (DMSO) as controls. DNA migration was analyzed using the tail moment according to Olive (OTM). Cytotoxicity was monitored using trypan blue staining. With TEGDMA concentrations at 10(-5)m (10(-3)m), UDMA at 10(-7)m (10(-7)m), and HEMA at 10(-3)m (10(-5)m) significant enhancements of DNA migration were achieved in tissue cells (lymphocytes) as compared to the negative controls. At higher concentrations of up to 2.5x10(-2)m, induced DNA migration was expressed by OTM at 10.7 for TEGDMA in tissue cells (8.7 in lymphocytes), 10.5 for UDMA (6.4), and 9.7 for HEMA (6.1). The viability of the cell systems was not affected as concerns the threshold level for the assay of 75% viable cells except for the highest concentration tested for TEGDMA and UDMA in tissue cells. At higher concentration levels, all tested substances induced significant enhancement of DNA migration in the Comet assay as a possible sign for genotoxic effects in human salivary glands and lymphocytes. These data add to the results of prior studies in human peripheral lymphocytes and give evidence of a possible risk factor for tumor initiation in human salivary glands.

Aged↗

PubMed2005

Neovascularization in prefabricated flaps using a tissue expander and an implanted arteriovenous pedicle.

Creating prefabricated flaps using tissue expanders in combination with the implantation of maximal blood flow vascular pedicles into suitable tissue areas represents a new tendency in the reconstruction of large skin defects. In 42 Chinchilla Bastard female rabbits weighing 3,700-4,600 g, skeletonized arteriovenous pedicles with maximal blood flow, dissected from the femoral and saphena magna bundles, were implanted underneath abdominal fasciocutaneous flaps. Oval tissue expanders of 250 ml were placed and fixed on the abdominal wall to expand these prefabricated flaps. The evaluation parameters were macroscopic observation, blood analysis, selective microangiography, histology, and scintigraphy. The study results showed that neovascularization in expanded prefabricated flaps was established from newly formed vessels generated from the implanted pedicles and their vascular connections with the originally available vasculature in the flap. After 20 days of prefabrication, the entirety of the expanded prefabricated flaps was perfused by blood flow supplied from newly implanted arteriovenous pedicles. The study indicated that an expanded prefabricated flap can be successfully created by the simultaneous implantation of a maximal blood flow pedicle in combination with flap expansion.

Animals↗

PubMed2005

Proposed new method for angiographically quantifying neovascularization in prefabricated flaps.

Prefabricated flaps have many potential applications in plastic and reconstructive surgery. Despite numerous experimental investigations and clinical applications, a standard quantification procedure for analyzing neovascularization in prefabricated flaps has not yet been established in the literature. In this study, we developed a new method for quantifying neovascularization, using a standard integral line plate including 25 evenly spaced lines corresponding to a 15-cm flap length, which was subsequently analyzed under a 2x magnification loupe. Vessel quantity was determined by counting the total number of times that vessels perfused by Micropaque intersected the integral lines over the entire surface of the flap. This new method was used for quantifying neovascularization in 156 prefabricated flaps, and we concluded that this technique is very simple and useful, allowing precise determination of the amount of neovascularization in prefabricated flaps on angiograms. Based on this principle, the quantification of neovascularization in any size of prefabricated flap can be easily performed using suitably modified integral line plates corresponding to the various flap dimensions.

Angiography↗

PubMed2005

Study of the neovascularisation of prefabrication of flaps using a silicone sheet and an isolated arterial pedicle: experimental study in rabbits.

Use of an isolated artery as an implanted pedicle in prefabricated flaps has rarely been reported either clinically or experimentally. In Chinchilla Bastard rabbits (n = 36), we dissected an isolated arterial pedicle from the femoral and saphenous artery, anastomosed it end-to-end to the femoral vein at the inguinal ligament and created an isolated arterial loop pedicle. This was implanted and fixed with polyglactin 9/0 under a random-pattern vascularised abdominal fasciocutaneous flap. The neovascularisation in the prefabricated flaps was evaluated macroscopically, by blood analysis, selective microangiography, and histology. The results showed a progressive degree of neovascularisation that corresponded to the increasing length of time that the pedicle was implanted in the flaps. Twenty days after prefabrication, the abdominal fasciocutaneous flap was readily perfused by the blood supply from the arterial pedicle. The capacity of the vessels in this group as seen on angiograms had increased to 258 vessels (108%) compared with the control group (239 vessels, 100%).

Anastomosis, Surgical↗

PubMed2004

Mono(2-ethylhexyl)phthalate exhibits genotoxic effects in human lymphocytes and mucosal cells of the upper aerodigestive tract in the comet assay.

Phthalic acid esters such as di(2-ethylhexyl)phthalate (DEHP) are widely used as plasticizers in PVC products manufactured for commercial, medical, and consumer purposes. Humans are exposed to phthalates originating, e.g., from blood storage bags, tubing materials, and from food-wrapping. While xenoestrogenic and chronic toxic effects of phthalates have been extensively discussed, there is little data on genotoxic effects in human cells. The alkaline comet assay was used to detect single-strand breaks and alkali labile sites of DNA after incubation of human nasal mucosal cells (n = 11) and peripheral lymphocytes (n = 11) with mono(2-ethylhexyl)phthalate (MEHP), the principal hydrolysis product of DEHP. MEHP showed a dose-dependent enhancement of DNA migration both in human mucosal cells and in lymphocytes. This effect indicates a genotoxic potential of MEHP in human mucosal cells. It confirms previous data obtained on the effect of MEHP on lymphocytes.

Adult↗

PubMed2004

Flap prefabrication and prelamination with tissue-engineered cartilage.

In reconstructive surgery, the integration of tissue-engineered cartilage in a prefabricated free flap may make it possible to generate flaps combining a variety of tissue components, to meet the special requirements of particular defects. One aim of the present study was to investigate prefabrication of a microvascular free flap by implanting a vessel loop under a skin flap in a rabbit model. A second aim was to report on the authors' preliminary experiences in prelaminating prefabricated flaps with autologous tissue-engineered cartilage, in terms of matrix development, inflammatory reaction, and host-tissue interaction. The flap was prefabricated by implanting a vessel loop under a random-pattern abdominal skin flap. The tissue-engineered cartilage constructs were made by isolating chondrocytes from auricular biopsies. Following a period of amplification, the cells were seeded onto a non-woven scaffold made of a hyaluronic-acid derivative and cultivated for 2 weeks. One cell-biomaterial construct was placed beneath the prefabicated flap, and two additional constructs were placed subcutaneously and intramuscularly. In addition, a biomaterial sample without cells was placed subcutaneously to provide a control. All implanted specimens were left in position for 6 or 12 weeks. Neovascularization in the prefabricated flap and biomaterial construct was analyzed by angiography. After explantation, the specimens were examined by histologic and immunohistochemical methods. The prefabricated flaps showed a well-developed network of blood vessels between the implanted vessel loop and the original random-pattern blood supply. The tissue-engineered constructs remained stable in size and showed signs of tissue similar to hyaline cartilage, as evidenced by the expression of cartilage-specific collagen type II and proteoglycans. No inflammatory reactions were observed. The physiologic environment of the autologous rabbit model provided favorable conditions for matrix deposition and maturation of the cell-biomaterial constructs. These initial results demonstrated the potential of prefabricating an axial perfused flap, combined with tissue-engineered cartilage, thus creating functionally competent tissue components for reconstructive surgery with minimal donor-site morbidity.

Angiography↗

PubMed2003

Genotoxic effects of vanadium pentoxide on human peripheral lymphocytes and mucosal cells of the upper aerodigestive tract.

In addition to tobacco and alcohol consumption, pollutants found in certain industries and in the environment play an important role in carcinogenesis in the upper aerodigestive tract. The aim of the present study was to investigate whether vanadium pentoxide may have a genotoxic effect on human mucosal cells and lymphocytes. The single cell microgel electrophoresis assay (Comet assay) was used to detect DNA damage induced by vanadium pentoxide in human nasal epithelia (n = 11) and in lymphocytes (n = 11). Mucosa was harvested from inferior nasal turbinates, while lymphocytes were obtained via venous puncture. Vanadium pentoxide was applied at concentrations of 0.06 mM, 0.12 mM, 0.24 mM, and 0.47 mM. Aqua bidestillata served as solvent and negative control and N-methyl-N'-nitro-N-nitrosoguanidine at 0.07 mM (MNNG) was used as positive control. The trypan blue exclusion test was applied to assess cytotoxicity. Whereas vanadium pentoxide induced dose-dependent DNA migration in lymphocytes, mucosal cells did not show comparable genotoxic effects. Cytotoxic effects allowed for viabilities exceeding 80%. The results indicate that vanadium pentoxide is capable of inducing single-strand-breaks and/or alkali-labile damage in the DNA of human lymphocytes. By contrast, mucosal cells proved not to be sensitive in this setting. Thus, a possible role of vanadium in the tumorigenesis of head and neck cancer appears unrelated to direct genotoxic effects.

Adult↗

PubMed2002

The characterisation of human respiratory epithelial cells cultured on resorbable scaffolds: first steps towards a tissue engineered tracheal replacement.

In this study we have used lectin histochemistry and scanning electron microscopy (SEM) to assess the growth and characterise the differentiation of human respiratory epithelial cells (REC) cultured on two biomaterial scaffolds. The first scaffold, based on a hyaluronic acid derivative, was observed to be non-adhesive for REC. This lack of adhesion was found to be unrelated to the presence of the hyaluronic acid binding domain on the surface of isolated REC. The other scaffold, consisting of equine collagen. was observed to encourage REC spreading and adhesion. Positive Ulex Europaeus agglutinin (UEA) lectin staining of this preparation indicated the presence of ciliated REC on the scaffold surface. However, the marked decrease in peanut agglutinin (PNA) positive staining, relative to that of control cultures and native tissue, indicates a dedifferentiation of the secretory cells of the REC monolayer. SEM analysis of REC cultured on the collagen scaffold confirmed the presence of ciliated cells thereby validating the UEA positive staining. The presence of both established and developing cilia was also verified. This study indicates that collagen biomaterials are appropriate for the tissue engineering of REC. Furthermore, that UEA and PNA staining is a useful tool in the characterisation of cells cultured on biomaterials, therefore helpful in identifying biomaterials that are suitable for specific tissue engineering purposes.

Adult↗