Investigation of Stent Prototypes for the Eustachian Tube in Human Donor Bodies

Chronic otitis media is often connected to Eustachian tube dysfunction. As successful treatment cannot be guaranteed with the currently available options, the aim is to develop a stent for the Eustachian tube (ET). Over the course of this development, different prototypes were generated and tested in ex vivo experiments. Four different prototypes of an ET stent and one commercially available coronary stent were implanted in the ET of seven human donor bodies. The position of the stents was verified by cone beam CT. The implanted ETs were harvested, embedded in resin and ground at 200 µm steps. Resulting images of the single steps were used to generate 3D models. The 3D models were then evaluated regarding position of the stent in the ET, its diameters, amount of squeezing, orientation of the axes and other parameters. Virtual reconstruction of the implanted ET was successful in all cases and revealed one incorrect stent placement. The cross-section increased for all metal stents in direction from the isthmus towards the pharyngeal orifice of the ET. Depending on the individual design of the metal stents (open or closed design), the shape varied also between different positions along a single stent. In contrast, the cross-section area and shape remained constant along the polymeric prototype. With the current investigation, insight into the behavior of different prototypes of ET stents was gained, which can help in defining the specifications for the intended ET stent.

Functional cleft palate surgery

Cleft lip and palate (CLP) as a dislocation malformation confronts parents with a malformation of their child that could not be more central and visible: the face. In addition to the stigmatizing appearance, however, in cases of a CLP, food intake, physiological breathing, speech and hearing are also affected. In this paper, the principles of morphofunctional surgical reconstruction of the cleft palate are presented. With the closure of the palate, and restoration of the anatomy, a situation is achieved enabling nasal respiration, normal or near normal speech without nasality, improved ventilation of the middle ear, normal oral functions with coordinated interaction of the tongue with the hard and soft palate important for the oral and pharyngeal phases of feeding. With the establishment of physiological function, in the early phases of the infant and toddler, these activities initiate essential growth stimulation, leading to normalisation of facial and cranial growth. If these functional considerations are disregarded during primary closure, lifelong impairment of one or more of the abovementioned processes often follows. In many cases, despite secondary surgery and revision, it might not be possible to correct and achieve the best possible outcomes, especially if critical stages of development and growth have been missed or there has been significant tissue loss due to resection of existing tissue while primary surgery. This paper describes functional surgical methods and reviews long term, over many decades, results of children with cleft palate.

Intravascular Ultrasonography (IVUS)-A Tool for Imaging the Eustachian Tube?

The Eustachian tube (ET) has a key role in the pathogenesis of otitis media. Until now, there has been a lack of meaningful imaging methods to investigate the ET and its surrounding tissue. The aim of the current study was to investigate the possibilities of imaging the ET using Intravascular Ultrasonography (IVUS). ETs from sheep were scanned ex vivo and in vivo with different IVUS probes. In addition to native ETs, water was also used to improve coupling. Scans were subsequently compared with histological sections and a 3D model of the ET. In addition, ETs with a stenosis induced by a hyaluronic acid depot, after stent insertion, and during lower jaw movement were examined. The IVUS catheter was inserted into the ET lumen without any problems or injuries in all cases. The surrounding structures of the ET were identified in the ultrasound image. In addition, a change in size of the ET lumen due to movement was observed, and the position of the stent and the depot of hyaluronic acid could be examined. With the use of IVUS, a non-invasive possibility to examine the ET over its course with the adjacent structures as well as after different treatments is presented.

Development of an In Vivo Model for Eustachian Tube Dysfunction

Otitis media is often connected to Eustachian tube dysfunction (ETD). Until now, there was no large animal model available for the examination of new treatment methods such as stents for the Eustachian tube (ET). Thus, the aim of the study was to develop a method to reproducibly induce ETD by injection of fillers and without permanent closure of the ET. Tools for safe injection of hyaluronic acid (HA) in the surrounding of the ET were developed. In ex vivo experiments, HA mixed with Imeron^® was injected close to the nasopharyngeal orifice of the ET of blackface sheep. The established depot was visualized using cone beam computer tomography and magnetic resonance imaging, and stents could be placed into the ET. A reliable position of the HA depot was achieved. This method was transferred to in vivo, and middle ear ventilation was investigated by tympanometry. ETD was achieved with amounts of 2.5 mL HA or higher. None of the animals showed any sign of discomfort or complications. The induced ETD lasted for 3 to 13 (maximum observation period) weeks and was also combined with middle ear effusion. A model of ETD based on injection of HA next to the ET was successfully established and is now available to test novel treatment options for ET functionality.

Polymeric stents for the Eustachian tube: development and human cadaver study

Impairment of Eustachian tube function with nonsufficient ventilation of the middle ear is a main cause for chronic otitis media. To provide an effective and safe therapy, the innovative concept of Eustachian tube stenting was established. Biodegradable polymeric stents are developed to restore impaired tube function and dissolve after fulfilling their supportive purpose. To evaluate the applicability of the stents in the Eustachian tube, prototypes in conjunction with corresponding implantation instruments were tested in human cadaver studies. Radiopaque markers and a diaphanoscopic approach were tested as additional features to prove correct positioning of catheter and stent in the tube. In the current study biodegradable polymeric stents were implanted in the Eustachian tube of human cadavers without difficulty. Correct positioning of the stents in the tube was proved by diaphanoscopy during intervention and postoperative tomographic and histological analyses. Once designs are optimized on the basis of cadaver studies, preclinical safety and efficacy studies using animal models will be initiated.

Development of biodegradable stents for the treatment of Eustachian tube dysfunction

To provide an effective and safe therapy for chronic Eustachian tube dysfunction (ETD), biodegradable stents should be developed to restore important functions, e.g. middle ear ventilation and drainage. After defining general requirements specifications, stent designs of cardiovascular polymeric stents were modified according to dimensions and conditions of the Eustachian tube. Finite element simulations demonstrated the crimping capacity of the developed stent design and the ability of expansion in the specific geometry of the target location. Subsequent in vitro tests of stent prototypes showed satisfying properties concerning crimpability, expansion behavior and elastic recoil to demonstrate general feasibility. Further developments and additional testing will advance the implementation of a new treatment option of ETD.

Tympanometric measurements in conscious sheep - a diagnostic tool for pre-clinical middle ear implant studies

OBJECTIVE

To investigate and establish the use of tympanometry in conscious sheep to provide a means of objective assessment of tympanic membrane integrity, middle ear ventilation and functioning of the Eustachian tube (ET).

DESIGN

After conditioning the sheep for four weeks, tympanometric measurements at 226 Hz were carried out weekly for 13 weeks. Before measurements, the external ear canal had been cleaned. Resultant curves were classified according to human reference values.

STUDY SAMPLE

Tests were performed on 12 female blackface sheep.

RESULTS

After cleaning of the external ear canal under otoscopic control, tympanic membranes were intact with no evidence of acute or chronic middle ear inflammation, middle ear effusion or retraction. Cleaning ensured valid, objective and reproducible measurements. As the majority of normal tympanograms were notched without the appearance of any malformation, an additional tympanogram type (A_N) was introduced. The notched appearance can most likely be explained by the anatomy of the middle ear of the sheep and the test frequency that was used.

CONCLUSION

The current study demonstrated how tympanometry can be used to evaluate treatment modalities for middle ear and ET function in conscious sheep. This provided a large animal model for further human research in otology.

Analysis of differentially expressed proteins in oral squamous cell carcinoma by MALDI-TOF MS

PURPOSE

To explore the presence of differentially expressed proteins in OSCC for discrimination of tumour and normal mucosa to establish potential biomarkers and therapeutic targets.

EXPERIMENTAL DESIGN

Paired protein samples of 12 individuals (tongue cancer and non-cancerous mucosa) were separated by two-dimensional polyacrylamid gel electrophoresis. The protein patterns were compared pairwise and protein spots were quantified. We identified about 70 regulated proteins which we subsequently identified by MALDI-TOF mass spectrometry.

RESULTS

Cancerous and non-cancerous tissues could be most precisely distinguished by a panel of proteins. They include the heat shock proteins (hsp)70 and 90, keratins (ck) 5, 6, 13, 14, 16, 17 and 19, beta globin, alpha-2-actin, stratifin, tropomyosin, calreticulin precursor, beta-2-tubulin, galectin7, thioredoxin, involucrin, adenylyl-cyclase-associated protein, disulfide isomerase-associated protein, thyrosine 3-monooxygenase, MYL2 and the s100 calcium binding protein. MYL3, cardiac muscle alpha actin 1 proprotein and transferrin were under-represented in OSCC. Six biomarkers, ck6 und ck13, beta globin, alpha-2-actin, hsp70 and hsp90 discriminated best between cancerous and non-cancerous oral tissues. All over-expressed proteins were analysed by STRING-analysis to highlight experimentally determined and computationally predicted interactions between the proteins. Especially involucrin, hsp70, calreticulin precursor, stratifin, (ck) 5, 6, 14, 19, tyrosine 3-monooxygenase, beta-2-tubulin and disulfide isomerase associated protein showed multiple relations.

CONCLUSION

We identified six proteins which are differentially expressed in most OSCC compared to healthy tissues. Of those, by string analysis, multiple interaction partners are assumed for hsp70. This protein is supposed to be the most promising candidate as marker molecule and target for OSCC therapy.

Immunohistochemical analysis of growth mechanisms in juvenile nasopharyngeal angiofibroma

Angiogenic factors are discussed to participate in growth and promotion of juvenile nasopharyngeal angiofibroma (JNA). However, only few data are available and mechanisms remain unclear. In the presented study we analysed the expression and subcellular distribution of several angiogenic growth factors and receptors potentially involved in JNA-growth and -vascularisation. In a retrospective, descriptive, multicenter-study, we analysed 13 formalin-fixed, paraffin-embedded or cryopreserved JNA-tumors (eleven primary tumors and two recurrent ones) after immunohistochemical staining. We used monoclonal antibodies specific for transforming growth factor beta 1 (TGF-beta(1)), basic fibroblast growth factor (bFGF), the VEGF-receptors 1 and -2 (FLT-1 and FLK-1), and the hypoxia inducible factor (Hif-1alpha). Data were compared to the vessel density. Quantitative analysis of staining intensities was performed by a computer assisted quantification technique. Endothelial and stromal compartments of the samples were analysed separately. Data were compared to vessel densities and patients data. The VEGF-Receptor-2 (FLK) was frequently unregulated in the stroma and endothelium of those samples with high vessel densities. Similarly, we observed high bFGF- and TGF-beta(1) levels in the stroma of strong vascularised samples. No correlations of expression levels to patients' data were found. The reported data support the concept of JNA-growth and -vascularisation driven by factors released from stromal fibroblasts. Therefore, inhibition of these factors might be beneficial for the therapy of inoperable JNA.

[Ultrasound of hypopharyngeal and oesophageal cancer: possibilities and limitations to staging and planning of therapy]

Sonographic examination of the hypopharynx and the extrathoracic oesophagus can be difficult. Therefore, most surgeons prefer to utilise CT or MRI scanning. Surgery is planned on the basis of endoscopic findings combined with radiologic information. The aim of the present prospective study was to demonstrate that the combination of ultrasonography and endoscopy provides a sufficient basis for the planning of surgical interventions in patients suffering from hypopharyngeal cancer or cancer of the proximal oesophagus. In 10 patients with squamous cell carcinoma of the hypopharynx/proximal oesophagus (8T4, 2T2) and 2 patients with a T4 squamous cell carcinoma of the larynx, both preoperative CT and ultrasound were performed and compared with the extent of the tumour seen during endoscopy. With ultrasound, the T4 tumours of the hypopharynx were recognized well as opposed to the T2 tumours which were not detected. The CT results were similar. An infiltration of the proximal oesophagus was seen with both imaging techniques in all affected patients. In contrast to CT, intralaryngeal tumour spread was not seen with ultrasound as long as the laryngeal skeleton was intact. The retropharyngeal region could also not be examined by ultrasound. Nevertheless, these results show that in all patients included in this study the extent of the tumour could have been estimated correctly by using ultrasound plus endoscopic examination alone. The reliable examination of this anatomically difficult region, however, requires examiner experience.

Increased PGE2 levels in nonmalignant mucosa adjacent to squamous cell carcinoma of the head and neck

OBJECTIVE

The cyclooxygenases (COX) 1 and 2 are the rate-limiting enzymes of prostaglandin E(2) (PGE(2)) synthesis, and the upregulation of COX-2 has been reported in tumors of different origins. The aim of our study was to quantify the PGE(2) expression in squamous cell carcinoma and surrounding mucosa, to analyze the potential of acetylsalicylic acid (ASA) for reducing PGE(2) levels in these tissues, and to improve our understanding of potential tumor-derived stimulation of surrounding mucosa by PGE(2).

STUDY DESIGN AND SETTING

Intracellular PGE(2) levels in primary head and neck squamous cell carcinoma (HNSCC) and the surrounding mucosa at 1 and 2 cm distance were analyzed ex vivo by ELISA. Subsequently, we treated in vitro tumor and normal mucosal cells from turbinates with recombinant PGE(2) and ASA, and quantified intracellular PGE(2) levels.

RESULTS

We observed high PGE(2) levels in the tumor samples and in tumor-surrounding mucosa. The addition of PGE(2) and arachidonic acid to tumor cell cultures resulted in no further increase in intracellular PGE(2) levels, while ASA reduced PGE(2) levels by up to 40%. In normal epithelial cell cultures, less PGE(2) (6% of that found in the tumor cells) was expressed, but stimulation with PGE(2) resulted in levels comparable to those of the tumor samples.

CONCLUSION AND SIGNIFICANCE

We conclude that HNSCC and the surrounding mucosa express high levels of PGE(2). This expression is reduced efficiently by ASA. We propose a stimulation of PGE(2) expression in the epithelium surrounding HNSCC by tumor-derived PGE(2) with a potential impact on tumor growth.

[Interdisciplinary therapy management in malignancy of the paranasal sinus tumors in children]

BACKGROUND

Malignant tumors of the paranasal sinuses, such as rhabdomyosarcoma or Ewing's tumors, often have a mesenchymal origin. In the recent years, several prospective, randomized, multicenter studies have demonstrated a better outcome after new oncology therapy protocols.

PATIENTS AND RESULTS

In the period from January 2000 to June 2001, we operated 610 patients with sinus disease. Only 23/610 were children or teenagers (3.8%). Half of the juvenile group suffered from chronic sinusitis, but 5/23 (22%) had a malignoma of the paranasal sinuses. In the adult population, malignoma was diagnosed in less than 1% of cases. We diagnosed and treated, in cooperation with our radiology, pathology and children's hematooncology department, one rhabdomyosarcoma, two malignant peripheral neuroectodermal tumors (PNET), one myelosarcoma and one malignant lymphoma in the paranasal sinuses. Two patients died.

SUMMARY AND CONCLUSION

These five cases of paranasal sinus malignomas are discussed in relation to their history and clinical course. We suggest that interdisciplinary treatment involving otorhinolaryngology, pathology, children's hematooncology, radiology and radiation therapy is obligatory for the therapy and for the best possible outcome of such cases.

[The need for 24-h double probe pH monitoring in the diagnosis of laryngo-pharyngeal reflux]

BACKGROUND

Laryngopharyngeal reflux disease (LPRD) can have various causes. Because LPRD differs from gastroesophageal reflux disease (GERD), the pH monitoring has to be performed directly next to the entrance of the larynx. This is now possible using a new system called pH-RESPONSE.

METHODS

The ambulatory pH was monitored using the double probe pH-RESPONSE in 20 patients with suspected LPRD. The number of refluxes, the number of long refluxes and the period in which the pH was below 4 were compared at the level of the larynx with the data from the esophageal electrode. The DeMeester score was also determined.

RESULTS

The system was well tolerated by 19/20 patients. In 12 patients a GERD could be proved and ten also had LPRD. Surprisingly, these patients had no typical signs such as heart burn. The number of refluxes measured in the esophagus was a third that of the larynx. The average time of pH below 4 was 30 min.

CONCLUSION

The pH-RESPONSE easily allows ambulatory 24 -h double probe pH monitoring to diagnose LPRD. Because large differences were found between data form the esophagus from the level of the larynx, 24-h double probe pH monitoring should be a standard procedure before starting any therapy for LPRD.

[Experimental study on the biomechanical stability of different internal fixators for use in the mandible]

BACKGROUND

Comparative studies of different forms of osteosynthesis require that biomechanical and biological criteria be observed. The conditions in experimental studies should be as close as possible to the in vivo situation. The aim of our study was to develop a fracture model that would allow determination of the micromovements in the gap tissue following different forms of internal fixation in fractured human mandibles.

METHODS

Micromovements in the gap tissue of five human mandibles treated with different osteosynthetic systems (DCP, EDCP, Miniplates, 3-D systems) following osteotomy or fracture in the region of the corpus and median region were investigated by means of strain gauges. By fitting the human mandibles in plaster according to a method of our own it was possible to create fractures at predictable and comparable localizations.

RESULTS

Our investigations show that the micromovements in the gap tissue of osteotomied and fractured mandibles are different and not dependent on the form of osteosynthesis applied. Physiological micromovements in the gap tissue were found under strain for all osteosynthetic systems used in fractured and congruently reset mandibles.

DISCUSSION

Our fracture and osteosynthesis model allows the quantitative determination of micromovements in the gap tissue and shows the importance of ideal realignment, which has a decisive influence on micromovements in the gap tissue.

[Experimental and finite-element models for the assessment of mandibular deformation under mechanical loading]

Biomechanical investigations of the mandible are difficult to perform due to a variety of conditions involved. For the appropriate reconstruction of biomechanical properties, a geometrically correct body model has to be established which fits to complex in vivo conditions. The aim of our study was to evaluate the use of finite-element models (FEM) for the assessment of mandibular deformation under mechanical loading. Explanted human mandibles (n = 5) were investigated by strain gauges to determine the individual strain distribution under mechanical loading. FEM analysis based on a computed tomograph (CT) was performed and the results were matched with the test data. Our study demonstrates only minor interindividual differences in the strain distribution for each load studied. The mechanical response in terms of deformation was found to depend mainly on gross geometrical properties and to a minor extent on the various other variables. At all positions the maximum principal strain was tensile, the minimum principal strain was compressive, and the absolute strain values were correlated with the magnitude of the applied force. CT-based FEM analysis revealed the utility of mathematical models to approximate simulated data our experimental results. Hence, FEM analysis is a non-invasive tool in the prediction of biomechanical behaviour of individual mandibles and therefore may help in trauma reconstruction and treatment planning.