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.

Genotoxicity and cytotoxicity of dental materials in human lymphocytes as assessed by the single cell microgel electrophoresis (comet) assay

OBJECTIVES

Resin monomers may be released from restorative dental materials and can diffuse into the tooth pulp or the gingiva, and can reach the saliva and the circulating blood. Whereas the cytotoxic potential of some components has been clearly documented, possible genotoxicity in human target cells demands further investigation.

METHODS

The Comet assay was used to quantify DNA single strand breaks, alkali labile and incomplete excision repair sites in lymphocytes of 10 volunteers. The xenobiotics investigated were 2-hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and bisphenol A-glycidyl methacrylate (Bis-GMA) with N-methyl-N'-nitro-N-nitrosoguanidine and dimethyl sulfoxide as controls. DNA migration was quantified using the tail moment according to Olive (OTM) and DNA migration was considered to be elevated at OTM levels above 2. Cytotoxicity was monitored using trypan blue.

RESULTS

In the negative controls, OTM ranged between 1.0 and 1.2. With HEMA concentrations above 10(-6)M, TEGDMA 10(-3)M, Bis-GMA 10(-4)M, and UDMA above 10(-6)M relevant enhancements of DNA migration (OTM>2) were achieved. At higher concentrations of up to 2.5x10(-2) induced DNA migration was expressed by OTM of 3.3 for HEMA, 4.5 for TEGDMA, 7.4 for Bis-GMA, and 2.8 for UDMA. Relevant cytotoxic effects were also seen but vitality levels were at a critical range of 71% for Bis-GMA and 73% for TEGDMA, only.

SIGNIFICANCE

In higher concentration levels, all tested substances induced significant but minor enhancement of DNA migration in the Comet assay as a possible sign for limited genotoxic effects. However, with the highest levels of DNA migration being combined with elevated cytotoxic effects, a low in vivo genotoxic strain appears to be posed by the resin components.

The tobacco alkaloid nicotine demonstrates genotoxicity in human tonsillar tissue and lymphocytes

Recent studies suggest a direct contribution of nicotine, the addictive component of tobacco and tobacco smoke, to human carcinogenesis. To assess the genotoxicity of nicotine, the DNA-damaging effect on human lymphocytes and target cells from lymphatic tissue of the palatine tonsils from 10 healthy patients was tested with the alkaline single-cell microgel electrophoresis (Comet) assay. The degree of DNA migration, a measure of possible DNA single strand breaks, alkali labile sites, and incomplete excision repair sites, was expressed as the Olive tail moment, the percentage of DNA in the tail, and the tail length. One hour exposure to nicotine at 0.125, 0.25, 0.5, 1, 2, and 4 mM induced a statistically significant dose-dependent increase of DNA migration up to 3.8-fold and 3.2-fold in tonsillar cells and lymphocytes, respectively. The lowest concentration eliciting significant DNA damage was 0.5 mM nicotine. The genotoxic effect was confirmed in a second series of experiments using nicotine of high purity from two different suppliers. There were no significant differences between the two series, excluding artifacts from the source of nicotine. Finally, DNA damage by nicotine was compared in cells incubated in medium strictly adjusted to neutral pH, with non-adjusted medium becoming alkaline with increasing nicotine concentrations. Again no differences in DNA migration were observed. The data indicate that nicotine expresses significant direct genotoxic effects in human target cells in vitro. However, no differences in DNA damage were observed in cells from smokers and nonsmokers incubated without nicotine. The lack of higher DNA damage in smokers compared to nonsmokers could be a question of nicotine dose, rapid DNA repair, or interactions with other smoke constituents. These results require further investigations on the contribution of nicotine to tobacco carcinogenesis.

Frequency of bilateral cervical metastases in oropharyngeal squamous cell carcinoma: a retrospective analysis of 352 cases after bilateral neck dissection

BACKGROUND

The decision whether to perform an elective neck dissection in patients with head and neck squamous cell carcinoma (HNSCC) and clinically negative lymph nodes (cN0) is made based on the probability of micrometastases in the neck for the given subsite and size of the primary. To date there is limited information about contralateral and bilateral cervical lymph node metastases of oropharyngeal carcinoma.

METHODS

A retrospective chart review was performed of 352 patients with oropharyngeal SCC who received a bilateral neck dissection. The frequency of histologically unveiled bilateral neck metastases was determined.

RESULTS

Carcinomas of the tonsillar fossa starting with a T2 classification and carcinomas of the soft palate, base of tongue, and pharyngeal wall at any stage showed a high frequency of bilateral metastases.

CONCLUSIONS

Bilateral neck dissection should be recommended for all but T1 and selected cases of T2 carcinomas of the tonsillar fossa.

Genotoxicity of di-butyl-phthalate and di-iso-butyl-phthalate in human lymphocytes and mucosal cells

The genotoxicity of phthalates, widely used plasticizers, has been shown previously for di-butyl-phthalate (DBP) and di-iso-butyl-phthalate (DBP) in human mucosal cells of the upper aerodigestive tract in a previous study using the Comet assay. Furthermore, higher genotoxic sensitivities of patients with squamous cell carcinomas of either the larynx or the oropharynx compared to non-tumor patients were described. Other authors have demonstrated DNA damage by a different phthalate in human lymphocytes. It was the aim of the present study to determine whether there is a correlation between the genotoxic sensitivities to DBP and its isomer DiBP in either mucosal cells or lymphocytes. The single-cell microgel electrophoresis assay (Comet assay) was applied to detect DNA strand breaks in human epithelial cells of the upper aerodigestive tract (n=132 specimens). Human mucosa was harvested from the oropharynx in non-tumor patients and patients with squamous cell carcinomas of the oropharynx. Laryngeal mucosa of patients with laryngeal squamous cell carcinomas was harvested as well. Peripheral lymphocytes (n=49 specimens) were separated from peripheral blood. Xenobiotics investigated were DBP, DiBP, and N'methyl-N'-nitro-N-nitrosoguanidine (MNNG) as positive control, respectively. For statistical analysis, the SPSS correlation analysis according to Pearson and the Wilcoxon test were performed. Genotoxicity was found for DBP and DiBP in epithelial cells and lymphocytes (P<0.001). MNNG caused severe DNA damage. In analyzing DBP and DiBP results, genotoxic impacts in mucosal cells showed an intermediate correlation (r=0.570). Correlation in lymphocytes was the same (r=0.570). Phthalates have been investigated as a potential health hazard for a variety of reasons, including possible xenoestrogenic impact, peroxisome proliferation, and membrane destabilization. The present investigation suggests a correlated DNA-damaging impact of DBP and DiBP in human mucosal cells and in lymphocytes, respectively.

Genotoxic effects of myosmine in human lymphocytes and upper aerodigestive tract epithelial cells

Myosmine, 3-(1-pyrroline-2-yl)pyridine, is an alkaloid found in tobacco plants. Recently, it was also detected in various edibles and staple foods. Whereas other tobacco alkaloids such as nicotine and nornicotine and their nitrosation products, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN), have been widely discussed, the mutagenic impact of myosmine has not been investigated in detail. In the present study, possible genotoxic effects of myosmine were studied in human lymphocytes and nasal mucosal cells using the alkaline single cell microgel electrophoresis (Comet) assay. DNA single strand breaks, alkali labile sites and incomplete excision repair sites were expressed using the Olive tail moment (OTM). One hour incubation with myosmine at 0, 5, 10, 25 and 50 mM induced a low but significantly dose-dependent increase of DNA migration from 1.29 +/- 0.13 to 18.25 +/- 1.59 (OTM, mean +/- S.E., N=11) in lymphocytes. In nasal mucosal cells a similar although somewhat less extensive DNA damage from 1.17 +/- 0.12 to 21.67 +/- 2.97 (OTM, mean +/- S.E., N=10-11) was obtained after 1 h incubation with myosmine at 0, 10, 25, 50 and 100 mM. After prolonged incubation of human lymphocytes with 10mM myosmine for 1, 3, 6, and 24 h, a significant time-dependent increase of DNA migration from 3.45 +/- 0.43 to 57.77 +/- 8.24 (OTM, mean +/- S.E., N=4) was observed. Our data indicate that myosmine expresses significant genotoxic effects in human target cells of carcinogenesis. This result warrants further investigations on the impact of this dietary component on human health.

Phthalates demonstrate genotoxicity on human mucosa of the upper aerodigestive tract

Various phthalate compounds are used as softeners and plasticizers in a wide range of plastic materials. There has been a growing concern regarding a possible health hazard to humans. The mucosa of the upper aerodigestive tract is the organ of first contact for the majority of xenobiotics, such as phthalates, entering the body. Still, there is a lack of information concerning possible carcinogenicity of phthalates in the upper aerodigestive tract. This motivated us to investigate their genotoxic effects on human epithelia: human mucosal cells derived from biopsies harvested during surgery of the oropharynx and the inferior nasal turbinate, respectively. The alkaline version of the microgel electrophoresis assay was used to detect single-strand breaks in the DNA following incubation with dibutylphthalate (DBP) and diisobutylphthalate (DiBP). DNA damage was induced by both DBP and DiBP in oropharyngeal and nasal mucosa, though the effect of DiBP was more pronounced than that of DBP. Nasal mucosa proved to be more sensitive than oropharyngeal epithelia. The results demonstrate genotoxic effects of phthalates on human mucosal cells of the upper aerodigestive tract, in contrast to earlier findings in animal models.

Genotoxicity of nicotine in mini-organ cultures of human upper aerodigestive tract epithelia

The direct role of nicotine in tobacco carcinogenesis is still controversial. Recently, DNA damage by nicotine has been demonstrated in isolated human tonsillar tissue cells. Presently, these effects were investigated using mini-organ cultures (MOC) of human nasal epithelia. Intact MOC were repeatedly exposed to 2 and 4 mM nicotine for 1 h on culture days 7, 9, and 11. N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) served as a positive control. DNA damage was examined by Comet assay either directly after exposure or following a 24-h recovery period. Cell viability was not reduced by any treatment. On day 7, 1 h exposure to 2 and 4 mM nicotine caused a significant dose-dependent 3.3- and 5.6-fold increase in DNA damage compared to solvent controls. Although there was no evidence of significant repair within 24 h recovery, DNA damage was not further increased by nicotine on days 9 and 11. After double and triple exposure to 4 mM nicotine a significant reduction in DNA damage following 24 h recovery was observed. In contrast, treatment with MNNG resulted in a highly significant and cumulative increase in DNA migration up to 110-fold compared to controls. During recovery periods, MNNG-induced DNA damage was significantly repaired, leading to a 1.5- to 1.8-fold reduction in DNA migration within 24 h. These results confirm genotoxic effects of nicotine on human nasal epithelia. Further studies are needed to explain the lack of cumulative DNA-damaging effects of nicotine and the absence of significant DNA repair. These studies should include a battery of assays with multiple end points.

The use of mini-organ cultures of human upper aerodigestive tract epithelia in ecogenotoxicology

The carcinogenic potential of xenobiotics and possible confounders are often difficult to differentiate in in vivo studies. In contrast, in vitro studies allow investigation of the impact of carcinogens on human target cells under standardized conditions. The aim of the present study is to demonstrate whether three-dimensional mini organ-cultures (MOCs) of human inferior nasal turbinate epithelia may represent a useful model to study genotoxic effects of xenobiotics in vitro. Culture of mini organs was performed by cutting 1mm3 pieces from fresh specimens of inferior nasal turbinates. After a period of 5-6 days the specimens were fully covered with epithelium. On days 7, 9, and 11 of culture, intact MOCs from 25 tissue donors were incubated with dimethyl sulfoxide (DMSO) as a negative control, or with mono(2-ethylhexyl) phthalate (MEHP), benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). On days 7 and 11, MOCs were analyzed by the alkaline Comet assay to detect DNA-single-strand breaks, alkali-labile sites and incomplete excision-repair sites. DNA migration after single exposure of non-cultivated fresh specimens was also analyzed. In order to detect regimen-specific effects, DNA fragmentation after single exposure of intact MOCs was compared with that of cells after separation of MOCs on day 7 of culture and consecutive exposure of individual cells. Significant DNA migration as a measure of DNA single-strand breaks, alkali-labile sites and incomplete excision repair sites, was found after electrophoresis due to single and triple exposure of MOCs to MEHP, BPDE and MNNG. Triple exposure of MOCs compared to single exposure revealed no difference after exposure to DMSO or MEHP, and an increased migration after exposure to BPDE and MNNG. When single exposure of isolated cells from fresh specimens was compared with that of intact MOCs, DMSO and MNNG had no significantly different effect, whereas exposure to MEHP or BPDE caused a reduced migration in cells from MOCs. When exposure of isolated cells harvested from MOCs was compared with exposure of intact MOCs, MEHP and BPDE caused a significantly lower DNA migration in intact MOCs. MOCs provide an in vitro model suitable for the assessment of genotoxic effects of environmental pollutants both after single or repetitive exposure. Due to the intact structure of the exposed mucosa this model may be a helpful tool in mimicking the in vivo situation in ecogenotoxicology studies.

Comparing the genotoxic sensitivities of human peripheral blood lymphocytes and mucosa cells of the upper aerodigestive tract using the Comet assay

Carcinogenesis in the upper aerodigestive tract is influenced by multiple factors. Besides tobacco and alcohol consumption, specific pollutants such as phthalates, nitrosamines, and polycyclic aromatic carbohydrates may be important in tumor initiation. Genetic factors related to mutagen sensitivity and DNA repair capacity also play a role. The aim of this study was to investigate whether human peripheral blood lymphocytes and mucosal epithelium of the upper aerodigestive tract, the target for volatile and liquid xenobiotics, are equally sensitive to genotoxic agents. The Comet assay was used to detect for DNA damage induced by genotoxic agents in mucosal epithelial cells and peripheral blood lymphocytes of 60 volunteers. Mucosa was harvested from larynx, oropharynx, and inferior nasal turbinates. Xenobiotics investigated were dibutylphthalate (DBP), diisobutylphthalate (DiBP), N'-nitrosodiethylamine (NDELA), benzo[a]pyrene (B[a]P), and N'-methyl-N'-nitro-N-nitrosoguanidine (MNNG). DBP, DiBP, B[a]P, NDELA and MNNG induced a significant increase in DNA migration in both cell populations. Peripheral blood lymphocytes were more sensitive than mucosal cells to DBP and DiBP, but not to NDELA and B[a]P. The correlation, in terms of DNA migration, between lymphocytes and mucosal cells among volunteers was relatively poor. Based on the poor correlation in response between the two cell types, the sensitivity of peripheral blood lymphocytes to genotoxic agents appears to be a poor predictor of sensitivity in the target cells of the upper aerodigestive tract. Further attention should be focused on intra-individual mutagen sensitivities and inter-individual genetic differences as regards susceptibility to upper aerodigestive tract cancer.

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.

Hemoglobin adducts of the human bladder carcinogen o-toluidine after treatment with the local anesthetic prilocaine

Prilocaine, a widely used local anesthetic, is metabolized to o-toluidine which is classified as human carcinogen. We aimed to assess the impact of prilocaine-treatment on hemoglobin adducts from o-toluidine. Blood samples were obtained before and 24h after receiving prilocaine local anesthesia (Xylonest, 100mg) from 20 head and neck surgery patients and 6 healthy volunteers. Hemoglobin adducts of o-toluidine and 4-aminobiphenyl were determined by gas chromatography/mass spectrometry. Hemoglobin adducts of o-toluidine were significantly increased 24h after 100mg prilocaine-treatment by 21.6+/-12.8ng/g hemoglobin (mean+/-S.D., N=26; P<0.0001). This corresponds to a 6-360-fold increase of o-toluidine adduct levels in 25 patients from 0.54+/-0.95ng/g before treatment to 22.0+/-13.2ng/g 24h after surgery (mean+/-S.D.). Because of an extremely high background level the increase was only 1.6-fold in one patient (40.9ng/g before and 64.4ng/g 24h after prilocaine injection). Current smoking had no influence on background values and on the increase of o-toluidine adducts. No treatment-related differences were seen in mean hemoglobin adduct levels of 4-aminobiphenyl which were significantly higher in smokers, 0.149+/-0.096ng/g (mean+/-S.D., N=8) as compared to nonsmokers 0.036+/-0.035ng/g (mean+/-S.D., N=16; P<0.01). In conclusion, prilocaine anesthesia leads to a massive increase of hemoglobin adducts of the carcinogenic arylamine o-toluidine. This implies a carcinogenic risk which should be taken into account in preventive hazard minimization.

Perioperative management of antithrombotic medication in head and neck reconstruction-a retrospective analysis of 137 patients

PURPOSE

Various protocols exist to prevent thrombosis after free flap surgery in the head and neck. This study reviews the outcome and incidence of perioperative complications in patients undergoing head and neck reconstruction, simply using subcutaneous low-molecular-weight heparin.

MATERIALS AND METHODS

A total of 137 free tissue transfers performed between 2007 and 2010 were reviewed. All patients received a general thrombosis prophylaxis with subcutaneous low-molecular-weight enoxaparin. No aspirin, dextran, or additional antithrombotic medication was administered.

RESULTS

Overall flap survival was 97.1%. A total of 3 complete and 1 partial flap loss occurred, all due to venous thrombosis. Five cases of venous congestion were successfully revised.

CONCLUSION

The free flap survival rate using simple subcutaneous heparin seems to be equivalent to other management regimens. Therefore, we suggest that no additional antithrombotic treatment is needed for patients who undergo head and neck reconstruction with free tissue transfer.

[Cytotoxicity and genotoxicity of fluorides in human mucosa and lymphocytes]

BACKGROUND

Fluorides are widely used in dental health products and drinking water, due to their beneficial effects in caries-prophylaxis and -treatment. Nevertheless, irritation of the gingiva and oropharyngeal mucosa as well as in gastric mucosa is observed since neither local nor systemic application is restricted to the teeth. These effects may partly be attributed to a known cytotoxicity of fluorides. Whether fluorides also have genotoxic effects on human mucosa or lymphocytes as a possible factor in tumor initiation was investigated in this study.

MATERIAL AND METHODS

Human oropharyngeal epithelial cells and peripheral lymphocytes were incubated after single cell preparation with the aminefluoride Olaflur at concentrations of 2 ppm, 21 ppm, 35 ppm, 71 ppm and 213 ppm. The extent of cytotoxicity was investigated using the trypan blue exclusion test. Following incubation, electrophoresis for migration of DNA fragments, fluorescence staining and digital image analysis according to a standard protocol of the single cell microgel electrophoresis assay (Comet assay) followed. DNA damage was characterized using the Olive Tail Moment (OTM).

RESULTS

For fluoride concentrations of 2 ppm to 35 ppm, non vital cells of less than 10% could be shown. After incubation with 71 ppm and 213 ppm Olaflur, there were 15% and 43% of damaged cells, respectively. Weak genotoxic effects on mucosal cells as well as on lymphocytes could be demonstrated at all concentrations tested. In fluoride concentrations of 213 ppm genotoxicity increased to max. OTM-levels of 23.

CONCLUSIONS

Beside the cytotoxic effect of fluorides, also a minor genotoxic impact on human mucosa and on peripheral lymphocytes could be demonstrated using the Comet assay. Further investigations are warranted to examine fluorides in a model allowing for repeated or long term incubations on structurally intact human mucosa in vitro. Such a model will help to distinguish between DNA damage that may be repaired successfully and other impairments that may show an additive character in repetitive or chronic exposure in vivo.

Genotoxicity of nitroso compounds and sodium dichromate in a model combining organ cultures of human nasal epithelia and the comet assay

Genotoxic effects of xenobiotics are a possible step in tumor initiation in the mucosa of the upper aerodigestive tract. Using the comet assay, detecting genotoxicity in human tissue has been restricted to single incubations in vitro, but in vivo most xenobiotics harm their target in a repetitive or chronic manner. Therefore, we propose a model, which provides repetitive incubations in human upper aerodigestive tract mucosa cultures. Samples of human inferior nasal turbinate mucosa (n = 25) were cultured according to a modified version of a technique originally described by Steinsvåg. On day 1 fresh samples and on days 7, 9 and 11 organ cultures were incubated with N-nitrosodiethylamine (NDEA), sodium dichromate (Na2Cr2O7) and N'-methyl-N-nitro-N-nitrosoguanidine (MNNG). Mucosa samples and organ cultures, respectively, underwent a modified comet assay on days 1, 7 and 11. Genotoxicity could be shown for NDEA, Na2Cr2O7 and MNNG on days 1, 7 and 11. Duration of tissue culture and repetitive incubations did not significantly influence the results for NDEA. Nevertheless, Na2Cr2O7 and MNNG caused higher genotoxic effects on cultures subjected to the comet assay on day 11. This model may help to assess genotoxic hazards posed by environmental pollutants that have a cumulative character in repetitive or chronic exposure in vivo.

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.

Vacuum assisted closure in the management of wound healing disorders in the head and neck: a retrospective analysis of 23 cases

BACKGROUND

Since the middle of the 1990s vacuum-assisted closure (VAC) has been used in many areas of surgery to manage complex wounds and impaired wound healing. Until recently, little attention has been paid to this treatment modality in the field of head and neck surgery. The evaluation of its efficacy in wound healing disorders of the head and neck was the aim of this study.

MATERIAL AND METHODS

Patients with complex wounds and impaired healing treated with VAC therapy between 2008 and 2011 were included into the study. VAC dressings were changed every 3 days and improvements in wound healing were documented.

RESULTS

23 patients were treated with VAC therapy, in 18 cases (78%) closure of the defect could be reached without any further surgical procedure. 5 patients needed subsequent regional flap reconstruction to close the remaining defect. All of these patients had undergone salvage surgery in a previously irradiated neck before.

CONCLUSION

Vacuum assisted closure is an effective treatment in the management of wound healing disorders and complex wounds in the head and neck. It offers a useful, non-invasive modality to close even large defects in the area. Previous irradiation seems to have a significant negative influence on the outcome of the therapy, but more data are required to assess these effects.

Medical nowcasting using Google Trends: application in otolaryngology

Google Trends is a valuable new additional tool for medical research, mainly for epidemiological and economical issues, which is fast and inexpensive to use and may be especially helpful when analyzing patient collectives who go to general practitioners or specialists in private practice rather than public or university clinics, where data for statistics are most often collected from.

Curcumin and other polyphenolic compounds in head and neck cancer chemoprevention

Despite clear results of observational studies linking a diet rich in fruits and vegetables to a decreased cancer risk, large interventional trials evaluating the impact of dietary micronutrient supplementation, mostly vitamins, could not show any beneficial effects. Today it has become clear that a single micronutrient, given in supernutritional doses, cannot match cancer preventive effects of whole fruits and vegetables. In this regard polyphenols came into focus, not only because of their antioxidant potential but also because of their ability to interact with molecular targets within the cells. Because polyphenols occur in many foods and beverages in high concentration and evidence for their anticancer activity is best for tissues they can come into direct contact with, field cancerization predestines upper aerodigestive tract epithelium for cancer chemoprevention by polyphenols. In this paper, we summarize cancer chemopreventive attempts with emphasis on head and neck carcinogenesis and discuss some methodological issues. We present data regarding antimutagenic effects of curcumin and epigallocatechin-3-gallate in human oropharyngeal mucosa cultures exposed to cigarette smoke condensate.

Mercuric dichloride induces DNA damage in human salivary gland tissue cells and lymphocytes

Amalgam is still one of the most frequently used dental filling materials. However, the possible adverse effects especially that of the mercuric component have led to continued controversy. Considering that mercury may be released from amalgam fillings into the oral cavity and also reach the circulating blood after absorption and resorption, it eventually may contribute to tumorigenesis in a variety of target cells. The present investigation focuses on genotoxic effects below a cytotoxic dose level of mercuric dichloride (HgCl(2)) in human samples of salivary glands and lymphocytes to elucidate a possible role in tumor initiation. DNA migration due to single strand breaks, alkali labile sites and incomplete excision repair was quantified with the aid of the single cell microgel electrophoresis (Comet) assay. The concepts of Olive Tail Moment, percentage of DNA in the Tail and Tail Length were used as measures of DNA damage. To control for cytotoxic effects, the trypan blue exclusion test was applied. Human samples of the parotid salivary gland and lymphocytes of ten donors were exposed to HgCl(2)concentrations from 1 to 50 microM. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and dimethyl sulfoxide (DMSO) served as controls. Increasing dose-dependent DNA migration could be demonstrated after exposure to HgCl(2) in cells of the salivary glands and lymphocytes. In both cell types a significant increase in DNA migration could be shown starting from HgCl(2)concentrations of 5 microM in comparison to the negative control. The viability of the cell systems was not affected except at the highest concentration (50 microM) tested. These data indicate genotoxic effects of mercuric dichloride in human salivary glands and lymphocytes at concentrations not leading to cytotoxic effects or cell death. Consequently, a contributory role in oral salivary gland tumor initiation warrants further investigation.

Influential factors on tumor recurrence in head and neck cancer patients

Alcohol consumption and cigarette smoking play a key role in the development and progression of head and neck cancer. Additionally, epidemiologic studies have given evidence that other environmental and genetic factors are relevant. We present a prospective study including 465 head and neck cancer patients. All patients were recruited between 1994 and 1998 during the initial tumor diagnosis. Three hundred twelve patients could be followed over 5 years after histologically proven curative surgical treatment. All clinical data were recorded (i.e., age, gender, TNM stage, histological grading, smoking and drinking habits) and genetic variations at loci encoding detoxifying enzymes (glutathione S-transferase and cytochrome P450); immune modulating cytokines (tumor necrosis factor) and cell cycle regulating proteins (cyclin D1) were determined. Parameters with an impact on recurrence-free survival were analyzed. A strong influence could be attributed to the tumor size at the time of presentation. Additionally, the grading of the tumor showed a strong influence (5 years recurrence free: G1: 87% and G1: 61%). Furthermore, it could be shown that the recurrence-free survival was significantly influenced by cyclin D1 genotypes (CCND1GG: P =0.01; HR=3.72) and TNF microsatellite haplotypes (TNFB1D5: P =0.043; HR=2.05). These findings are compatible with the view that genetic predisposition is important in determining recurrence-free survival after surgical treatment of head and neck cancer.

Surgical errors and risks - the head and neck cancer patient

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. It can lead to functional impairment and has impact in future chances for disease related survival. There are many risks for head and neck surgeons that can cause errors and malpractice.

To avoid surgical mistakes, thorough preoperative management of patients is mandatory. As there are ensuring operability, cautious evaluation of preoperative diagnostics and operative planning. Moreover knowledge of anatomical structures of the head and neck, of the medical studies and data as well as qualification in modern surgical techniques and the surgeons ability for critical self assessment are basic and important prerequisites for head and neck surgeons in order to make out risks and to prevent from mistakes. Additionally it is important to have profound knowledge in nutrition management of cancer patients, wound healing and to realize and to be able to deal with complications, when they occur.

Despite all precaution and surgical care, errors and mistakes cannot always be avoided. For that it is important to be able to deal with mistakes 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.

Surgically treated oropharyngeal cancer: risk factors and tumor characteristics

PURPOSE

To assess risk factors of patients with oropharyngeal squamous cell carcinoma in the Munich area of Southern Germany in relation to human papillomavirus (HPV) association of the tumors. To demonstrate differences in tumor characteristics and their impact on adjuvant treatment.

METHODS

Between November 2010 and July 2013, patients were prospectively interviewed for risk factors before they underwent surgical resection of their tumors. HPV association was evaluated by p16 immunohistochemistry; tumor characteristics and type of adjuvant treatment were recorded. Follow-up data were collected after a median follow-up of 12.1 month.

RESULTS

In contrast to many recent studies, we could not detect any difference in overall age and age at sexual debut between p16-positive and p16-negative patients. P16-negative patients are characterized by a more intensive tobacco and alcohol use, a more abusive way of consumption, less nonoral and less oral sex partners. P16-positive patients had a significantly higher risk of lymph node metastases, but nevertheless a significant lower risk to recur or to die. No difference in the incidence of synchronous second primary tumors was seen. P16-positive patients generally received a more aggressive adjuvant treatment because of more frequently involved lymph nodes.

CONCLUSION

Lifestyle risk factors such as smoking, drinking, and sexual habits were independent from age, but showed marked differences between the p16-positive and p16-negative group. Since p16-positive patients were treated more aggressively, it is not possible to distinguish whether the better outcome of HPV-positive patients is a result of less aggressive cancers or more aggressive treatment. With regard to the ongoing debate about treatment deintensification, we should keep in mind that the survival of HPV-positive cancer patients is not 100 %.

Primary cold atmospheric plasma combined with low dose cisplatin as a possible adjuvant combination therapy for HNSCC cells-an in-vitro study

BACKGROUND

The aim of the present study was to examine the cytostatic effects of cold atmospheric plasma (CAP) on different head and neck squamous carcinoma (HNSCC) cell lines either in isolation or in combination with low dose cisplatin. The effect of CAP treatment was investigated by using three different HNSCC cell lines (chemo-resistant Cal 27, chemo-sensitive FaDu and OSC 19).

MATERIALS AND METHOD

Cell lines were exposed to CAP treatment for 30, 60, 90, 120 and 180 s (s). Cisplatin was added concurrently (cc) or 24 h after CAP application (cs). Cell viability, DNA damage and apoptosis was evaluated by dye exclusion, MTT, alkaline microgel electrophoresis assay and Annexin V-Fit-C/PI respectively.

RESULTS

In all cell lines, 120 s of CAP exposure resulted in a significant reduction of cell viability. DNA damage significantly increased after 60 s. Combined treatment of cells with CAP and low dose cisplatin showed additive effects. A possible sensitivity to cisplatin could be restored in Cal 27 cells by CAP application.

CONCLUSION

CAP shows strong cytostatic effects in HNSCC cell lines that can be increased by concurrent cisplatin treatment, suggesting that CAP may enhance the therapeutic efficacy of low dose cisplatin.