Buried free flaps in head and neck reconstruction: higher risk of free flap failure?

Thrombosis of the pedicle is central to free flap failure, and early revision of a compromised flap is the key to successfully salvage a flap. Therefore, the majority of free flaps in reconstructive head and neck surgery are used with the ability to visually examine the flap. Sometimes, due to intra-operative circumstances, it is necessary to use a flap that cannot be monitored externally. These flaps are called buried flaps and have the reputation of being put at risk. The current literature provides only limited data to support or disprove this position. A single institution retrospective review of patient charts between 2007 and 2015 was performed. Flap monitoring was carried out with hand-held Doppler of the pedicle hourly for the first 72 h in all cases. Additional duplex ultrasound was performed in the majority of buried flaps. A total of 437 flaps were included into the study. 37 flaps (7.8 %) were identified to fulfill the criteria of a buried free flap. In total, four patients had complications, three of which required operative reexploration. All interventions were successful, resulting in no flap loss in our series. An accurate operation technique combined with meticulous monitoring protocols supported by duplex ultrasound can result in satisfactory outcome of buried flaps. No enhanced risk of flap loss of buried flaps was found in our cohort.

Clinical impact of malnutrition on complication rate and length of stay in elective ENT patients: a prospective cohort study.

Malnutrition is considered as an independent risk factor for morbidity, mortality and a prolonged hospital stay for in-hospital patients. While most available data on the impact of malnutrition on health-related and financial implications refer to gastroenterologic or abdominal surgery patients, little is known about the impact of malnutrition on Ear Nose Throat (ENT)/head and neck surgery patients. The objective of this study was to investigate the impact of malnutrition on morbidity and length of hospital stay in an elective ENT/head and neck surgery patient cohort. The study was performed as a single-center, prospective cohort study at a tertiary referral centre. Nutritional risk at admission was assessed using the NRS-2002 screening tool. Multivariate regression models were used to determine independent risk factors for complications and a prolonged hospitalization. Three hundred fifty one participants were included in the study. A malignant disease was found in 62 participants (17.7 %). 62 patients (17.7 %) were at a moderate to severe risk of malnutrition. A bad general health condition and complications during hospital stay could be identified as independent risk factors for a prolonged hospitalization. Patients with a malignant tumor showed a more than fourfold higher risk of developing at least one complication. Malnutrition, however, was not statistically associated with a higher complication rate or a prolonged hospital stay. Our data suggests that malnutrition does not seem to play such an important role as a risk factor for complications and a prolonged hospital stay in ENT patients as it does in other disciplines like abdominal surgery or gastroenterology.

[The supraclavicular flap for reconstruction of the head and neck]. / Der supraclaviculäre Lappen zur Rekonstruktion im Kopf-Hals-Bereich.

The complex anatomy of the head and neck region requires the ability to raise a wide spectrum of pedicled and free flaps, to ensure optimal reconstruction of various defects by the reconstructive surgeon. The supraclavicular (island) flap, which has almost been buried in oblivion, provides excellent potential to reconstruct even bigger defects of the head and neck region, while causing minimal donor site morbidity at the same time. Its benefits lie in the reliable skin island and its wide arc of rotation, resulting in excellent cosmetic and functional outcomes.

Context-dependent adaption of EpCAM expression in early systemic esophageal cancer.

The role of the epithelial cell adhesion molecule EpCAM in cancer progression remains largely unclear. High expression of EpCAM in primary tumors is often associated with more aggressive phenotypes and EpCAM is the prime epithelial antigen in use to isolate circulating tumor cells (CTCs) and characterize disseminated tumor cells (DTCs). However, reduced expression of EpCAM was associated with epithelial-to-mesenchymal transition (EMT) and reports on a lack of EpCAM on CTCs emerged. These contradictory observations might reflect a context-dependent adaption of EpCAM expression during metastatic progression. To test this, EpCAM expression was monitored in esophageal cancer at different sites of early systemic disease. Although most of the primary esophageal tumors expressed high levels of EpCAM, the majority of DTCs in bone marrow lacked EpCAM. In vitro, downregulation of EpCAM expression at the plasma membrane was observed in migrating and invading cells, and was associated with a partial loss of the epithelial phenotype and with significantly decreased proliferation. Accordingly, induction of EMT through the action of TGFß resulted in substantial loss of EpCAM cell surface expression on esophageal cancer cells. Knock-down or natural loss of EpCAM recapitulated these effects as it reduced proliferation while enhancing migration and invasion of cancer cells. Importantly, expression of EpCAM on DTCs was significantly associated with the occurrence of lymph node metastases and with significantly decreased overall survival of esophageal cancer patients. We validated this observation by showing that high expression of EpCAM promoted tumor outgrowth after xenotransplantation of esophageal carcinoma cells. The present data disclose a dynamic expression of EpCAM throughout tumor progression, where EpCAM(high) phenotypes correlate with proliferative stages, whereas EpCAM(low/negative) phenotypes associated with migration, invasion and dissemination. Thus, differing expression levels of EpCAM must be taken into consideration for therapeutic approaches and during clinical retrieval of disseminated tumor cells.

[Surgical errors and risks--the head and neck cancer patient]. / Fehler und Gefahren: Onkochirurgie im Kopf-Hals-Bereich.

Head and neck surgery is one of the basic principles of head and neck cancer therapy. Surgical errors and malpractice can have fatal consequences for the treated patients. This can lead into functional impairment and even have impact in future chances for disease related survival. There are many risks for head and neck surgeons which can cause errors and malpractice. To avoid surgical errors, thorough preoperative management of patients is demanded for. Such is ensuring operability, cautious evaluation of preoperative diagnostics and operative planning. Moreover knowledge of anatomical structures of the head and neck, of medical studies and data as well as qualifications in modern surgical techniques and the surgeons ability for critical self assessment are basic but important prerequisites for head and neck surgeons in order to prevent from mistakes. Moreover it is important to have profound knowledge in nutrition management of cancer patients, wound healing and to realize and be capable of dealing with complications, when they occur.Despite all preventive precaution and surgical care, mistakes cannot always be avoided. For that it is important to be able to deal with errors and to establish an appropriate and clear communication and management for such events. The manuscript comments on recognition and prevention of risks and mistakes in the preoperative, operative and postoperative phase of head and neck cancer surgery.

[Development of an ICF-based clinical practice guideline for the assessment of function in head and neck cancer]. / Entwicklung eines ICF-basierten Leitfadens für die Beurteilung funktioneller Aspekte bei Kopf-Hals-Tumoren.

BACKGROUND: Functional outcome following head and neck cancer is not regularly assessed in a standardized way in clinical practice. Clinical trials assessing functional outcome apply many different instruments. Therefore, results are not always comparable and have limited clinical implications. Aim of this study was the identification, interdisciplinary evaluation, and recommendation of functional outcome instruments for use in clinical practice and clinical trials in patients with HNC. MATERIAL: Preparatory studies came up with a shortlist of outcome instruments on the basis of previously determined criteria. An interdisciplinary expert group evaluated these instruments and decided on which ones can be recommended for use in 3 application areas: screening, therapy evaluation/planning, and clinical trials. Decision making health professionals included physicians (ENT and maxillofacial surgeons, radiotherapists, oncologists), medical psychologists, speech and language therapists, physiotherapists, and social workers. RESULTS: 98 instruments were presented at the consensus conference. Altogether 21 participants recommended for each of the 3 application areas a basic set of measures for the evaluation of impairment in 6 functional domains: follow-up therapy monitoring, pain, ingestion, voice/speaking, other organic problems, and psychosocial problems. CONCLUSION: A multi-professional expert's pool discussed and adopted recommendations for the use of functional outcome instruments in clinical praxis and/or in research. The re-commended instruments are now available for use in clinical routine.

EpCAM regulates cell cycle progression via control of cyclin D1 expression.

The epithelial cell adhesion molecule (EpCAM) is an integral transmembrane protein that is frequently overexpressed in embryonic stem cells, tissue progenitors, carcinomas and cancer-initiating cells. In cancer cells, expression of EpCAM is associated with enhanced proliferation and upregulation of target genes including c-myc. However, the exact molecular mechanisms underlying the observed EpCAM-dependent cell proliferation remained unexplored. Here, we show that EpCAM directly affects cell cycle progression via its capacity to regulate the expression of cyclin D1 at the transcriptional level and depending on the direct interaction partner FHL2 (four-and-a-half LIM domains protein 2). As a result, downstream events such as phosphorylation of the retinoblastoma protein (Rb) and expression of cyclins E and A are similarly affected. In vivo, EpCAM expression strength and pattern are both positively correlated with the proliferation marker Ki67, high expression and nuclear localisation of cyclin D1, and Rb phosphorylation. Thus, EpCAM enhances cell cycle progression via the classical cyclin-regulated pathway.

Endoscopic measurements of free-flap perfusion in the head and neck region using red-excited Indocyanine Green: preliminary results.

BACKGROUND: Free-tissue transfer has become a standard procedure for reconstructive surgery in the head and neck area. Flap failures are relatively rare (or=64% for all other examinations. CONCLUSIONS: It was possible to prove the feasibility of endoscopic ICG fluorescence angiography in patients undergoing free-flap transfer to the UADT. The method provides instant information about the perfusion state of the tissue and is easily performed without greater patient discomfort or risk of side effects. Due to the endoscopic approach, the method seems highly promising for this indication and merits further evaluation.

Chemopreventive action of dexamethasone and alpha-tocopherol in oxidative stressed cells.

INTRODUCTION: Recent research indicates a close connection of inflammation and cancer as presumed by Virchow in 1893. The growing understanding of cellular signalling and regulatory pathways reveals multiple links between inflammation and cancer. This study was designed to evaluate the influence of the anti-inflammatory drug dexamethasone and the antioxidant alpha-tocopherol on oxidative induced DNA damage, a major factor in the development of malignancies. MATERIAL AND METHODS: Miniorgan cultures (MOC) of fresh biopsied human nasal mucosa were used to keep cells in their microenvironment and thus to mimic in vivo conditions. MOC were pretreated with dexamethasone and alpha-tocopherol in different concentrations on 1 or on 5 days before oxidative DNA damage was introduced by hydrogen peroxide. The effect of these substances on DNA damage was evaluated using the alkaline single cell microgel electrophoresis (Comet Assay). RESULTS: Dexamethasone induced slight, but considerable DNA fragmentation by itself. It effectively protected cells from hydrogen peroxide induced DNA damage, leading to a maximum decrease of about 45% when preincubated on 5 days at 20 microM. alpha-Tocopherol most effectively reduced oxidative DNA fragmentation by about 38% when MOC were pretreated 5 days at 20 microM. DISCUSSION: Our experimental data clearly shows the DNA protective action of dexamethasone and alpha-tocopherol with regard to oxidatively induced DNA damage, a major pathogenetic factor that inflammation and cancer have in common.

Content comparison of quality of life questionnaires used in head and neck cancer based on the international classification of functioning, disability and health: a systematic review.

The objective of this study is to provide a content comparison of frequently used questionnaires that assess health-related quality of life (hrQOL) in head and neck cancer (HNC) survivors. This systematic content comparison describes which specific areas of hr-QOL research are covered by each questionnaire. Thereby, it shall assist the clinician in the decision process of instrument selection depending on the content of the study question. As a reference, we chose the international classification of functioning, disability and health (ICF), which was adopted by the WHO in 2001. A systematic literature review identified current hrQOL questionnaires relevant for HNC. The concepts of functioning contained in each questionnaire were translated (linked") to the ICF according to standardized guidelines. Nine questionnaires were selected for further analyses: EORTC-QLQ (C30 + HN35), FACT (G + HN), UW_QOL, QOL-RTI, HN-QOL, PSS-HN, VHI, LORQ, XQ. Within the selected questionnaires, there are 474 concepts, matching 74 second-level ICF categories. The results are presented in tables, showing for each of the validated questionnaires, which of these 74 categories of functioning are addressed. In terms of diversification of content among the questionnaires, there are just eight categories that are used rather frequently and apply to at least five (out of nine) of the questionnaires: e110 Products for personal consumption (i.e., food, drugs), b510 ingestion function, b152 emotional function, b280 sensation of pain, b310 voice, d550 eating, b130 energy and drive function and d850 employment. This ICF-based content comparison provides detailed information on the content that is covered in each questionnaire and thereby assists questionnaire selection. The results question the assumption that HNC-specific questionnaires generally cover the same content. Depending on the study question, the population to be studied and the intervention, there is no unique ideal questionnaire. Compared with other types of qualitative review, the most important advantage of content comparison based on the ICF is the use of an external and independent reference.

[DNA-protective potential of polyphenols in human mucosa cell cultures]. / DNA-protektives Potential von Polyphenolen in humanen Schleimhautzellkulturen.

BACKGROUND: The concept of field cancerization in the head and neck offers an excellent basis for chemopreventive interventions. Within the last few years, polyphenols, the most abundant phytochemicals in our diet, have been identified as interesting chemopreventive agents based on their multiple actions. This study was designed to add more experimental data regarding the chemopreventive features of epigallocatechin gallate (EGCG) and tannin (TA) in cultures of fresh biopsied tissue to epidemiologic studies and animal and cell line experiments. MATERIALS AND METHODS: Miniorgan cultures (MOC) were produced from oropharyngeal mucosa-cubes about 1 mm(3), epithelialized and with their tissue structure preserved. The MOC were incubated with EGCG (0.1 and 5 microM) and TA (1 and 5 microM) for 30 min on three consecutive days. On the 3rd day, DNA damage was introduced with metabolically activated tobacco carcinogen benzo[a]pyren-7,8-dihydrodiol-9,10-epoxid (BPDE) [9 microM] for 60 min. The resulting DNA damage was measured with alkaline single-cell microgel electrophoresis (comet assay) and quantified using the olive tail moment (OTM). RESULTS: By incubating MOC with the polyphenols, the DNA damage caused by BPDE was significantly decreased at all concentrations. CONCLUSION: To our knowledge, this is the first test using cell cultures produced from fresh biopsies that demonstrates ECGC and TA as promising chemopreventive agents and confirms nutritional studies.

[Does nicotine add to the carcinogenic strain of tobacco smoke?]. / Trägt Nikotin zur Krebsentstehung im oberen Aerodigestivtrakt bei?

BACKGROUND: It is accepted that nicotine in tobacco smoke causes addiction via nicotinic acetylcholine receptors in the central nervous system. For a long time, the tumorigenic potential of smoking was attributed to compounds other than nicotine. However, more recently data have accumulated which suggest that nicotine may add to the cancer risk by stimulating cellular growth via non-neuronal acetylcholine receptors, by suppressing apoptosis, and by inducing angiogenesis not only in atheromatous plaques but also in tumors. In the present study the possible direct genotoxic effects of nicotine on DNA were investigated in human target cells of carcinogenesis in the upper aerodigestive tract. PATIENTS AND METHODS: Human nasal mucosa, lymphatic tissue of the palatine tonsils, supraglottic epithelium of the larynx, and peripheral lymphocytes were exposed to rising concentrations of nicotine. DNA damage was investigated by alkaline single-cell microgel electrophoresis (Comet) assay. Cytotoxicity was assessed by trypan blue exclusion. RESULTS: Nicotine induced dose-dependent DNA damage in all cell types at low cytotoxic concentrations that allowed viabilities well above 80%. The lowest nicotine concentrations eliciting a significant increase in DNA migration were 1 mM for tonsillar cells and 0.25 mM for all other cell types. CONCLUSION: Nicotine induces genotoxic effects in human target cells of carcinogenesis in the upper aerodigestive tract at relevant concentrations. Thus, nicotine may contribute directly to tumor initiation resulting from smoking.

[Susac's syndrome. A rare microangiopathy of cochlea, retina, and brain]. / Susac-Syndrom. Eine sehr seltene Mikroangiopathie von Kochlea, Retina und Gehirn.

Susac's syndrome is a rare disease characterized by encephalopathy, retinal artery occlusion, and a sensorineural hearing loss. Diagnosis may be difficult since most specialists are not familiar with this angiopathy. However, the typical symptom complex can mimic different pathologies, therefore requiring the attention of radiologists, ENT specialists, and ophthalmologists. We present a rare case of Susac's syndrome unveiled by audiometry results, MR imaging of the brain, and the ophthalmological findings..

[Mini-organ cultures of human nasal mucosa. A model for eco-genotoxicological investigations]. / Miniorgankulturen humaner nasaler Mukosa. Ein Modell für ökogenotoxikologische Untersuchungen.

BACKGROUND: Volatile and ingestive xenobiotics may induce cancer in the mucosa of the upper aerodigestive tract. A new model is presented combining mini-organ cultures of human mucosa and the Comet assay that allows investigation of tumor initiation steps in vitro. METHOD: Specimens of human mucosa of the inferior nasal turbinates were cultured as mini-organs and exposed to xenobiotics once, twice or three times with consecutive repair intervals. The cultures were monitored for structural integrity (inverse microscopy, histology), DNA fragmentation and repair activity (Comet assay), induction of apoptosis (annexin V assay), and production of IL-8 and GM-CSF (ELISA). RESULTS: Mini-organ cultures showed a good structural integrity during the whole culture period. Exposure to N-nitrosodiethylamine (NDEA) and benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) induced significant DNA fragmentation. Sodium dichromate (Na2Cr2O7) had an additive DNA fragmentation effect with repetitive exposure. Significant DNA repair was seen after strand break induction by Na2Cr2O7, only. Apoptosis was seen after three exposures to BPDE und Na2Cr2O7, but not NDEA. Inflammatory cytokine release was unaltered by NDEA. However, BPDE and Na2Cr2O7 reduced GM-CSF and Na2Cr2O7 reduced IL-8 excretion. CONCLUSION: This three dimensional mini-organ culture system proved to be very helpful in characterizing volatile and ingestive xenobiotics potentially hazardous to humans. Beside the information concerning genotoxicity, it allows cytological and immunological studies. In contrast to investigations with fresh specimens, repetitive or chronic exposure to xenobiotics is possible in mucosal cells with their epithelial structural integrity. Therefore, mini-organ cultures of human upper aerodigestive tract epithelia represent a model closely resembling the in vivo situation.

[Carcinogenic and co-carcinogenic effects of metals and ethanol on human salivary gland tissue]. / Karzinogene und kokarzinogene Effekte von Metallen und Ethylalkohol in humanen Speicheldrüsenzellen.

BACKGROUND: The etiology of malignomas of human salivary glands is examined. MATERIAL AND METHODS: Macroscopic, healthy salivary gland tissue from 46 donors was harvested during surgery. Single cells were isolated by enzymatic digestion. These were then incubated for 60 min with Na(2)Cr(2)O(7), NiSO(4), CdSO(4), ZnCl(2) and ethanol. Additionally, incubation with Na(2)Cr(2)O(7) was combined with NiSO(4), CdSO(4), ZnCl(2) and ethanol. The influence of CdSO(4) was analyzed by altered combinations with Na(2)Cr(2)O(7) during incubation and by the DNA-repair period. Evaluation was performed using fluorescent staining and digital analysis. RESULTS: Of all of the substances tested, only Na(2)Cr(2)O(7) showed genotoxic effects. NiSO(4), ZnCl(2) and ethanol had neither genotoxic nor cofactorial impacts. CdSO(4), however, caused additional genotoxic effects in combination with Na(2)Cr(2)O(7), although it lacked direct genotoxic potential. A reduction of DNA-repair of Na(2)Cr(2)O(7)-induced oxidative damage by CdSO(4) could be demonstrated. CONCLUSIONS: In this investigation, sodium dichromate was identified as genotoxic in association with human salivary gland tissue. These effects could be increased by CdSO(4), reinforcing DNA damage based on oxidative stress.

Toxicological assessment of noxious inhalants.

In the past centuries mankind has been exposed to various forms of air pollution not only at his occupational but also in his social environment. He mainly gets exposed with these pollutants through the respiratory organs and partially absorbs them into the body. Many of these airborne substances can be harmful for humans and some of them may account for tumorigenic effects.The following essay describes the main features of toxicological assessment of inhalative environmental and workplace xenobiotics. The essay also explains relevant characteristics and limit values of noxious compounds and gases and depicts modern testing methods. To this end, emphasis is given on methods characterizing the different stages of tumorigenic processes. Various test systems have been developed which can be used in vivo, ex vivo or in vitro. They are to a great part based on the evidence of changes in DNA or particular genes of cells. Among others they have highlighted the impact of interindividual variability on enzymatic activation of xenobiotics and on susceptibility of the host to tumor diseases.Unfortunately, for many inhalative environmental noxious agents no sufficient risk profiles have been developed. The completion of these profiles should be the goal of toxicological assessment in order to allow reasonable socioeconomic or individual-based risk reduction.

[Preservation of mucosal specimens before processing in the alkaline single cell microgel electrophoresis assay]. / Lagerung humaner nasaler Mukosa für die Einzelzell-Mikrogelelektrophorese.

BACKGROUND: Human mucosal biopsies are established in ecogenotoxicological studies, but up until now they have demanded immediate processing after harvesting. We report our experience with the preservation of specimens either for 24 h at 4 degrees C or for longer periods at -80 degrees C and compare the results with fresh specimens using the alkaline single cell microgel electrophoresis assay. PATIENTS AND METHODS: Nasal mucosa was harvested from ten patients, transferred to the laboratory and divided into groups for immediate processing,24 h preservation at 4 degrees C and cryopreservation at -80 degrees C. Alkaline single cell microgel electrophoresis assays were performed after separating the specimens into single cells and after exposure to benzo[a]pyrene,benzo[a]pyrene-diolepoxide, N-nitrosodiethylamine, or sodium dichromate. The trypan blue exclusion test was used to assess cytotoxicity. RESULTS: Despite of the fact that cell viability remained stable, after cryopreservation DNA-migration increased significantly for the negative control and benzo[a]pyrene. Although an increase was also seen for sodium dichromate, this was not significant. For benzo[a]pyrene-diolepoxide, N-nitrosodiethylamine and N-methyl-N'-nitro-N-nitrosoguanidine there were no significant changes in DNA-migration. After 24 h in cell medium at 4 degrees C,DNA-migration did not rise compared to the samples which were immediately processed. CONCLUSIONS: Preservation of mucosal specimens at 4 degrees C for 24 h may be legitimate in order to facilitate laboratory practice. However, cryopreservation should not be applied because it leads to higher rates of DNA migration in some tested substances in the alkaline single cell microgel electrophoresis assay.

[Chromosome 5q-syndrome-ENT pathologies]. / Chromosom-5q-Syndrom aus HNO-ärztlicher Sicht.

INTRODUCTION: The interstitial deletion of chromosome 5q is a disease of rare incidence, which might be hereditary or caused by spontaneous changes within the chromosome respectively. The pathology is based on the loss of chromosomal material within the long arm of chromosome 5. Clinical manifestations are mainly known in hematology, particular such as malignancies or hematopoetic malformation. Other morphological characteristics that have been described following deletion of chromosome 5q are deformity of the skull and the joints as well as heart defects. In the following we will present some pathologic findings focussing on the head and neck. PATIENT: We introduce a young female patient of 8 months with deletion of the long arm of chromosome 5q. In addition to the known skeletal and hematopoetic disorders we discovered a unilateral deafness and a contralateral middle-graded combined hearing-loss as well as laryngomalacia. CONCLUSION: Infants with chromosome 5 syndrome should undergo an otorhinolaryngological examination to investigate anatomic malformations. In particular a brainstem electric response audiometry should be considered for early diagnosis and treatment of a possible hearing-loss. This ensures adequate and early support of the patients physical and psychological development.

[The single cell microgelelectrophoresis technique in ecogenotoxicology]. / Stellenwert der Einzelzell Mikrogelelektrophorese in der Okogenotoxikologie.

BACKGROUND: The development of carcinoma in the upper aerodigestive tract is often associated with exposure to xenobiotics. Therefore, the identification of such tumor initiating substances is relevant. Most genotoxicity test systems require mammalian cells, human lymphocytes or cell cultures to detect genotoxicity caused by carcinogens. The single cell microgelelectrophoresis technique (Comet assay) is presented, being a sensitive method, identifying DNA strand breaks, alkali labile sites and DNA repair in human epithelial cells of the upper aerodigestive tract. It is compared to other common techniques for the identification of genotoxic damage. Future applications and contributions of the method are introduced. GENOTOXICITY TEST SYSTEMS: Using the alkaline microgel electrophoresis assay, freshly isolated single epithelial cells are incubated with xenobiotics causing DNA strand breaks and alkali labile sites. Data are examined using a digital computer analysis. The method is described for the application of epithelial cells of the upper aerodigestive tract and compared to other procedures for the monitoring of genotoxicity. These are the Ames test identifying mutagenicity in bacteria, the sister chromatid exchange and the micronucleus test demonstrating genomic instability in lymphocytes and cultured mammalian cells. CONCLUSIONS: The microgel electrophoresis technique is a sensitive method to detect genotoxic effects and DNA repair in human epithelia of the upper aerodigestive tract. The assay offers considerable advantages to other common genotoxicity tests. However, combining of the Comet assay with mini organ cultures allows to use repetitive incubations with xenobiotics. Furthermore, signalling selected chromosomal material by the combination of the assay with the fluorescence in situ hybridisation, DNA-damage and -repair mechanisms within comets can be identified.