Jens E. Meyer

Pronounced infracuticular endocytosis in mammalian outer hair cells

Endocytosis in cochlear hair cells was investigated by staining with the vital fluorescent dye FM 1-43, that partitions reversibly into membranes and is trapped in vesicles during endocytosis. The temporal development and spatial distribution of FM 1-43 induced fluorescence was investigated using confocal laser-scanning microscopy. FM 1-43 rapidly and intensely stained cochlear hair cells, leaving the supporting cells unstained. For short application (0.2-30 s), only the infracuticular region of outer hair cells (OHCs) was labeled, whereas for long application (30-60 s), the OHCs were also labeled in the infranuclear zone and along a central strand extending from the infracuticular zone down to the nucleus, as well as along the entire cell membrane. Except for the cell membrane, the infracuticular zone, directly below the cuticular plate, showed the most rapid and intense staining, and in most cases staining was spherically shaped with a diameter of 3-7 microm. Localization and size of this infracuticular staining coincided with Hensens body, a specialized variant of the endoplasmic reticulum. In contrast to the OHCs, apical fluorescence of inner hair cells presented a homogeneous distribution. When OHCs were incubated in FM 1-43 for longer than 1 min, many points of contact between the central strand, the infracuticular zone and the lateral cell membrane were observed. Since Hensens bodies are a specialty of OHCs and the fluorescent staining pattern of these cells was unique, it is proposed that Hensens body is involved in the turnover of OHC-specific proteins, such as those involved in the molecular machinery of the motor action of the plasma membrane.

The Oral Serine Protease Inhibitor WX-671 – First Experience in Patients with Advanced Head and Neck Carcinoma

Tumour invasion and metastasis depend on the capacity of tumour cells to coordinate various biological processes such as detachment of cells from their original localisation, cancer cell migration, invasion of cancer cells into surrounding tissue, access to blood and lymphatic vessels and adhesion to and invasion through the endothelium, allowing colonisation at distant sites of the organism. This complex scenario requires the concerted and regulated expression of extracellular proteolytic systems, integrins and adhesion proteins. Degradation of proteins in basement membranes and extracellular matrix is the prerequisite for the invasion of cells and the formation of metastases. This is mediated by various extracellular proteolytic enzymes including serine proteinases, metalloproteinases and cysteine proteinases [1]. There is abundant experimental evidence that the plasminogen activator system plays an essential role in these processes [1,2,3,4,5,6,7,8]. It consists of two serine proteinases, urokinase-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA), the cell surface uPA receptor (uPAR) and the plasminogen activator inhibitors 1 and 2 (PAI-1, PAI-2). uPA is agreed to be the enzyme with the major influence on cancer-related processes, whereas the primary role of tPA is the generation of plasmin for fibrinolysis of blood vessels [9]. Besides its proteolytic activity, uPA in concert with uPAR also mediates mitogenic, adhesive and migratory processes [10]. Clinical studies have demonstrated the relevance of uPA, uPAR and PAI-1 in malignant tumours such as breast, ovary, cervical, upper urinary, gastrointestinal, lung, prostate and other cancers. Elevated levels of these factors correlate with increased malignancy and poor patient outcome [1, 7, 11, 12]. For head and neck squamous cell carcinoma (HNSCC) the role of the uPA system has been extensively investigated [13,14,15,16,17]. In tumour lysates, it has been demonstrated that both uPA and PAI-1 may play a specific role in the process of invasion and metastasis and might also be of prognostic value in this carcinoma [18, 19]. Recently, Wilex developed a serine protease inhibitor of the uPA system, the intravenous drug WX-UK1, and its new orally administered pro-drug WX-671 to treat cancer. Once WX-671 is absorbed, the hydroxyamidino function is reductively converted to the amidino function, thereby generating pharmacologically active WX-UK1. In rat, dog and monkey, WX-671 is effectively absorbed, although with varying rates between species, and readily metabolised to WX-UK1. In rat models, WX-671 has been shown to be efficacious at inhibiting tumour growth and spread. For clinical testing in man, hard gelatine capsules are available that contain WX-671 hydrogen sulphate equivalent to 50 mg and 200 mg WX-671 (free base). The aim of this study was to evaluate the pharmacokinetics of both the oral pro-drug WX-671 and the metabolite WX-UK1 in human tissue and plasma of patients with HNSCC. In addition, the safety and tolerability as well as the effects on the uPA system of WX-671 were assessed.

Mechanical Transduction in Outer Hair Cells

The outer hair cells are responsible for the exquisite sensitivity, frequency selectivity and dynamic range of the cochlea. These cells are part of a mechanical feedback system involving the basilar membrane and tectorial membrane. Transverse displacement of the basilar membrane results in relative motion between the tectorial membrane and the reticular lamina, causing deflection of the stereocilia and modulation of the open probability of their transduction channels. The resulting current causes a change of membrane potential, which in turn produces mechanical force, that is fed back into the motion of the basilar membrane. Experiments were conducted to address mechanical transduction mechanisms in both the stereocilia and the basolateral cell membrane, as well as modes of coupling of the outer hair cell force to the organ of Corti.

Perioperative Intensity-Modulated Brachytherapy for Refractory Orbital Rhabdomyosarcomas in Children

Purpose:To evaluate the feasibility and toxicity of perioperative intensity-modulated brachytherapy (IMBT) as well as functional outcome in children with therapy-refractory orbital rhabdomyosarcomas (RMS).Patients and Methods:Since 1993, children with therapy-refractory orbital RMS have been treated by a multidisciplinary approach combining function-preserving, mostly R1 tumor resection and perioperative IMBT at the University Hospital of Schleswig-Holstein, Germany. All children with orbital RMS, who were enrolled in this multidisciplinary treatment protocol between 1993 and 2002, were prospectively assessed with respect to evaluation of side effects and functional outcome.Results:Ten children (six boys, four girls) were included. Median age was 6.5 years (range, 1–19 years) at the beginning of our treatment and 6.0 years (range 1–17 years) at diagnosis. All children were in Intergroup Rhabdomyosarcoma Study Group (IRSG) group III and had embryonal subtype. Estimated 5-year survival was 62% ± 18%. There was no radiation-related toxicity grade 3 or 4 observed. The eyes were primarily preserved in all cases. One child underwent secondary orbital exenteration 10 months after completion of IMBT. Visual acuity could be preserved apart from one child developing significant visual deterioration due to radiation cataract grade 2. The cosmetic results were good or very good in eight and moderate in two children. Four children died of their disease.Conclusion:This interdisciplinary, individually tailored and function-preserving treatment procedure has proven to be a well-tolerated therapeutic option in cases with refractory orbital RMS. It provides both improvement of local tumor control and quality of life.Ziel:Die Durchführbarkeit und Verträglichkeit der perioperativen intensitätsmodulierten Brachytherapie (IMBT) bei Kindern mit refraktären orbitalen Rhabdomyosarkomen (RMS) sowie deren funktionelles Ergebnis sollten untersucht werden.Patienten und Methodik:Seit 1993 werden Kinder mit therapierefraktären orbitalen RMS mittels einer multidisziplinären Behandlungsmethode am Universitätsklinikum Schleswig-Holstein behandelt, welche eine funktionserhaltende, meist R1-Tumorresektion mit einer perioperativen IMBT kombiniert. Ausgewertet wurden alle Kinder mit orbitalem RMS, die zwischen 1993 und 2002 in dieses multidisziplinäre Behandlungsprotokoll eingeschlossen und prospektiv hinsichtlich Verträglichkeit und funktionellem Ergebnis untersucht worden waren.Ergebnisse:Es wurden zehn Kinder (sechs Jungen, vier Mädchen) behandelt. Das mediane Alter betrug 6,5 Jahre (Spannweite 1–19 Jahre) bei unserem Behandlungsbeginn und 6,0 Jahre (Spannweite 1–17 Jahre) bei Diagnosestellung. Bei allen Kindern lagen ein Stadium III gemäß Intergroup Rhabdomyosarcoma Study Group (IRSG) und ein embryonaler Subtyp vor. Die geschätzte 5-Jahres-Überlebensrate betrug 62% ± 18%. Es wurde keine Strahlentoxizität Grad 3 oder 4 beobachtet. Die Augen wurden primär in allen Fällen erhalten, nur bei einem Kind war 10 Monate nach IMBT eine sekundäre Orbitaexenteration erforderlich. Die Sehschärfe wurde überwiegend geschont. Lediglich ein Kind entwickelte eine signifikante Sehverschlechterung aufgrund einer radiogenen Katarakt Grad 2. Die kosmetischen Ergebnisse waren bei acht Kindern gut oder sehr gut und bei zwei Kindern moderat. Vier Kinder starben an ihrem Tumor.Schlussfolgerung:Diese interdisziplinäre, individuell zugeschnittene funktionserhaltende Behandlungsprozedur hat sich als gut verträgliche palliative therapeutische Option in Fällen refraktärer orbitaler RMS erwiesen. Sie ermöglicht sowohl eine Verbesserung der lokalen Tumorkontrolle als auch der Lebensqualität.

Aspirin Sensitivity and Chronic Rhinosinusitis with Polyps: A Fatal Combination

Aspirin-exacerbated respiratory disease (AERD) refers to aspirin sensitivity, chronic rhinosinusitis (CRS), nasal polyposis, asthma, eosinophil inflammation in the upper and lower airways, urticaria, angioedema, and anaphylaxis following the ingestion of NSAIDs. Epidemiologic and pathophysiological links between these diseases are established. The precise pathogenesis remains less defined, even though there is some progress in the understanding of several molecular mechanisms. Nevertheless, these combinations of diseases in patients classified by AERD constitute a fatal combination and may be difficult to treat with standard medical and surgical interventions. This paper reviews in brief the epidemiology, clinical features, diagnosis, molecular pathogenesis, and specific therapies of patients classified by AERD and postulates future attempts to gain new insights into this disease.

Tonic mechanosensitivity of outer hair cells after loss of tip links

Tip links - the extracellular connectors between the distal ends of adjacent stereocilia - are essential for the fast mechanical gating of hair-cell transducer channels. Transduction in the absence of tip links was investigated for outer hair cells of the adult guinea-pig cochlea by patch-clamp recordings of the whole-cell current during mechanical stimulation of the hair bundle. Loss of tip links induced by application of BAPTA led to permanently opened transducer channels, as evidenced by a constant inward current, loss of response to sinusoidal mechanical deflection of the hair bundle and block by the open-channel blocker dihydrostreptomycin (100 microM). Step deflection of the hair bundle (200-500 nm) in the inhibitory direction exponentially reduced this current to a constant value with time constant, tau(on), of the order of seconds. The current returned exponentially to the pre-stimulus level with time-constant, tau(off), also of the order of seconds. tau(on) was dependent on the inter-stimulus interval, Deltat, such that reducing this interval below about 40 s resulted in an exponentially faster response. tau(off) was independent of Deltat. Application of the calcium ionophore, ionomycin (10 microM), showed that tau(on) became independent of Deltat after saturating elevation of the intracellular Ca(2+) concentration. Flash-photolytic release of intracellular caged calcium (25-microM NP-EGTA/AM) showed that tau(on) is dependent on intracellular Ca(2+) concentration. These experiments imply an intracellular, calcium-dependent gating mechanism for hair-cell transducer channels.

Functional effects of a monoclonal antibody on mechanoelectrical transduction in outer hair cells.

The functional effect of a monoclonal antibody, RA6.3, on mechanoelectrical transduction (MET) of outer hair cells (OHCs) isolated from the adult guinea-pig cochlea was investigated. This antibody was raised by an antiidiotypic approach against amiloride binding sites. RA6.3 irreversibly reduced the receptor current, independent of membrane potential. The time course of the functional block was independent of dilution (1:100, 50 and 10), beginning 1.2+/-0.5 min after the start of application and decreasing exponentially with a time constant of 0.29+/-0.18 min to 53+/-8% of the control current. The residual current was reversibly blocked by amiloride (300 microM), mainly at negative membrane potentials. Block of control current by amiloride was competitively inhibited by simultaneous application of RA6.3. These results suggest that RA6.3 binds to or in close proximity to amiloride receptor sites associated with the MET channels. Irreversibility, incompleteness, independence of membrane potential and independence of antibody dilution of the functional block can all be explained by irreversible binding of one antibody molecule to a receptor site, yielding a non-blocked state, followed by a relatively slow, reversible transition to a blocked state. It is proposed that the reversible transition might represent intramolecular binding of the second antibody combining site to the second receptor site.

Brachytherapie in Kombination mit zurückhaltender Chirurgie

A multimodal, interdisciplinary approach known as intensity-modified brachytherapy is a promising alternative for patients with advanced head and neck cancer infiltrating the orbita and skull base. An 87-year-old man presented with a recurrence of squamous cell carcinoma of the medial corner of the left eye that had been locally resected and irradiated by external beam radiotherapy multiple times. The cancer was resected with preservation of the eye with close margins, implantation of afterloading catheters, and reconstruction of the defect with a median forehead flap. The patient was irradiated with a total radiation dose of 30 Gy IMBT. After 1 year, there was no evidence of locoregional recurrence. The background of this therapeutic process and analysis of the current literature regarding this interdisciplinary treatment of head and neck cancer infiltrating the orbita and skull base are discussed based on this case report.

Brachytherapie für die Behandlung von Kopf-Hals-Karzinomen

Image-Adapted brachytherapy (IABT) is a modern interdisciplinary development of classic radiation therapy, which allows the application of a high radiation dose while avoiding severe adverse events, thereby improving the prognosis of our patients. Indications in head and neck squamous cell carcinoma (HNSCC) include tumours of the floor of mouth, the face, the paranasal sinuses, the naso- and oropharynx, recurrent cancer and incomplete resections due to close vicinity of the tumor to important structures. The application type can be classified as curative, adjuvant, perioperative as a boost with or without external beam radiation (EBRT) or as a palliative treatment. The published results encourage the integration of IABT as part of the therapy of HNSCC, thereby improving the prognosis and quality of life of our patients.ZusammenfassungDie Image-Adaptierte Brachytherapie (IABT) ist eine moderne interdisziplinäre Weiterentwicklung der Strahlentherapie, welche die Applikation einer hohen Strahlendosis unter Minderung von schweren Toxizitäten ermöglicht und auf diese Weise die Prognose unserer Patienten verbessern kann. Indikationen im Bereich der Kopf-Hals-Karzinome (HNSCC, „head and neck squamous cell cancer“) finden sich bei Tumoren der Mundhöhle, des Gesichts, der Nasennebenhöhlen, des Naso- und Oropharynx. Zudem ist die IABT auch eine gute Therapieform für die Rezidivsituationen oder Non-in-sano-Resektionen an wichtigen Strukturen, die einen Organerhalt fordern. Die Applikationsform kann alleinig kurativ, adjuvant, perioperativ als Boost zur lokalen Dosisaufsättigung mit und ohne eine externe Strahlentherapie (EBRT, „external beam radiation therapy“) oder aber in palliativer Intention erfolgen. Die erzielten Erfolge ermutigen, die IABT als einen festen Bestandteil in der Therapie von Kopf-Hals-Karzinomen zu etablieren und dadurch die Prognose und Lebensqualität unserer Patienten weiter auszubauen.AbstractImage-Adapted brachytherapy (IABT) is a modern interdisciplinary development of classic radiation therapy, which allows the application of a high radiation dose while avoiding severe adverse events, thereby improving the prognosis of our patients. Indications in head and neck squamous cell carcinoma (HNSCC) include tumours of the floor of mouth, the face, the paranasal sinuses, the naso- and oropharynx, recurrent cancer and incomplete resections due to close vicinity of the tumor to important structures. The application type can be classified as curative, adjuvant, perioperative as a boost with or without external beam radiation (EBRT) or as a palliative treatment. The published results encourage the integration of IABT as part of the therapy of HNSCC, thereby improving the prognosis and quality of life of our patients.

Brachytherapy for the treatment of head and neck cancer

Image-Adapted brachytherapy (IABT) is a modern interdisciplinary development of classic radiation therapy, which allows the application of a high radiation dose while avoiding severe adverse events, thereby improving the prognosis of our patients. Indications in head and neck squamous cell carcinoma (HNSCC) include tumours of the floor of mouth, the face, the paranasal sinuses, the naso- and oropharynx, recurrent cancer and incomplete resections due to close vicinity of the tumor to important structures. The application type can be classified as curative, adjuvant, perioperative as a boost with or without external beam radiation (EBRT) or as a palliative treatment. The published results encourage the integration of IABT as part of the therapy of HNSCC, thereby improving the prognosis and quality of life of our patients.ZusammenfassungDie Image-Adaptierte Brachytherapie (IABT) ist eine moderne interdisziplinäre Weiterentwicklung der Strahlentherapie, welche die Applikation einer hohen Strahlendosis unter Minderung von schweren Toxizitäten ermöglicht und auf diese Weise die Prognose unserer Patienten verbessern kann. Indikationen im Bereich der Kopf-Hals-Karzinome (HNSCC, „head and neck squamous cell cancer“) finden sich bei Tumoren der Mundhöhle, des Gesichts, der Nasennebenhöhlen, des Naso- und Oropharynx. Zudem ist die IABT auch eine gute Therapieform für die Rezidivsituationen oder Non-in-sano-Resektionen an wichtigen Strukturen, die einen Organerhalt fordern. Die Applikationsform kann alleinig kurativ, adjuvant, perioperativ als Boost zur lokalen Dosisaufsättigung mit und ohne eine externe Strahlentherapie (EBRT, „external beam radiation therapy“) oder aber in palliativer Intention erfolgen. Die erzielten Erfolge ermutigen, die IABT als einen festen Bestandteil in der Therapie von Kopf-Hals-Karzinomen zu etablieren und dadurch die Prognose und Lebensqualität unserer Patienten weiter auszubauen.AbstractImage-Adapted brachytherapy (IABT) is a modern interdisciplinary development of classic radiation therapy, which allows the application of a high radiation dose while avoiding severe adverse events, thereby improving the prognosis of our patients. Indications in head and neck squamous cell carcinoma (HNSCC) include tumours of the floor of mouth, the face, the paranasal sinuses, the naso- and oropharynx, recurrent cancer and incomplete resections due to close vicinity of the tumor to important structures. The application type can be classified as curative, adjuvant, perioperative as a boost with or without external beam radiation (EBRT) or as a palliative treatment. The published results encourage the integration of IABT as part of the therapy of HNSCC, thereby improving the prognosis and quality of life of our patients.