[Development of an ICF-based clinical practice guideline for the assessment of function in head and neck cancer]

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.

Cytochrome P4502A6 stability in a mini organ culture model of human nasal mucosa for genotoxicology studies as detected by flow cytometry

Three dimensional mini organ cultures (MOCs) of human nasal turbinate epithelia have been shown to be a relevant tool in genotoxicology studies. MOCs allow repetitive or chronic exposure of cells in an organ specific mucosal architecture for an extended period of time and monitoring of possible adverse effects with, e.g., the comet assay. It is the aim to demonstrate whether the proteins of key enzymes of xenobiotic metabolism, represented by cytochrome P450 2A6 (CYP2A6), remain on a stable level for a culture period that allows repetitive or chronic exposure to xenobiotics. Culture of mini organs was performed by cutting pieces of 1 mm(3) from fresh specimens of human nasal turbinates. MOCs of five tissue donors were incubated on multi-well plates with BEBM, on days 0, 4, 7, 9, and 11 aliquots were transmitted to flow cytometric quantification of the CYP2A6 protein. The CYP2A6 protein could be demonstrated on all days of culture investigated. Interindividual differences were more pronounced on day 0 than at later stages of culture. Although there appeared to be a slight decrease over the culture period, flow cytometric analysis did not reveal a significant loss of the signals up to day 11. The present data could show a pre-requisite of metabolic competence of MOCs that is in contrast to single cell cultures. Thus, this type of organ culture provides an in vitro model suitable for the assessment of genotoxic effects of environmental pollutants mimicking the in vivo situation with target cells of carcinogens in their functional organ specific architecture.

[Does nicotine add to the carcinogenic strain of tobacco smoke?]

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.

Cumulative genotoxic and apoptotic effects of xenobiotics in a mini organ culture model of human nasal mucosa as detected by the alkaline single cell microgel electrophoresis assay and the annexin V-affinity assay

Three-dimensional mini organ cultures of human inferior nasal turbinate epithelia have proved to be a useful tool in genotoxicology studies. They allow repetitive or chronic exposure of cells to xenobiotics in a well-preserved organ-specific mucosal architecture for an extended period of time. It is the aim of the present study to concurrently monitor cumulative genotoxic and apoptotic effects of sodium dichromate, N-nitrosodiethylamine (NDEA) and N-methyl-N-nitro-N-nitroso-guanidine (MNNG). Mini organs were raised by separating fresh specimens of human inferior nasal turbinates (n=11) into 1 mm3 sized pieces and culturing them on multiwell plates with bronchial epithelial basal medium for 6 days. Aliquots of the mini organs were subsequently exposed to sodium dichromate (1.0 mM, 1h), NDEA (50 mM, 1h) or MNNG (0.07 mM, 1h) on days 7, 9 and 11 versus a single exposure on day 11 only. DNA fragmentation and apoptotic events were assessed on day 11 using the alkaline single cell microgel electrophoresis assay (comet assay) and the annexin V-affinity assay. Significant DNA fragmentation could be demonstrated after a single exposure of the mini organs to sodium dichromate. Following three subsequent incubations, there was a further increase in the genetic damage observed, accompanied by an increase in the rate of apoptotic cells. In contrast, after single and triple incubation with NDEA there was neither an increase in genetic damage nor in the fraction of apoptotic cells detectable. Repetitive exposure to MNNG resulted in an accumulation of DNA damage without an observable increase in apoptosis. The results verify the need to assess apoptosis in genotoxicology research and to investigate cumulative effects of xenobiotics. Three-dimensional mini organ cultures of human upper aerodigestive tract epithelia have shown to be well-suited for improving the ability to distinguish between cumulative genotoxic and apoptotic effects.

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.

[Mini-organ cultures of human nasal mucosa. A model for eco-genotoxicological investigations]

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.

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 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 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.

Karzinogene und kokarzinogene Effekte von Metallen und Ethylalkohol in humanen Speicheldr�senzellen

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.

DNA repair capacity in lymphocytes of nasopharyngeal cancer patients

Possible hereditary factors in the tumorigenesis of nasopharyngeal cancer (NPC) have not yet been clearly identified. In the present study, the DNA repair capacity of lymphocytes after exposure to the nitrosamine NDEA was quantified in order to elucidate whether this measure may be a factor in susceptibility to NPC. The alkaline single-cell microgel electrophoresis (Comet) assay was used to quantify chemically induced DNA damage and repair capacity in lymphocytes of 30 NPC patients (NPC) and 29 non-tumor donors (NTD). The induction of DNA single strand breaks, alkali labile and incomplete excision repair sites after exposure of lymphocytes to NDEA was assessed as differences between repair intervals of 0 min, 15 min, 30 min and 60 min, respectively. A RC(total) was assessed using the difference between the OTMs of 0 min of repair time and the 60-min repair interval for both groups. Repair capacities (RC) were calculated for the intervals according to the Olive Tail Moment (OTM), a quantitative measure for DNA migration in the Comet assay for the group of NPC patients and the NTD, accordingly. RCs were compared between the two groups using the Mann-Whitney U-Test. RC(15 min), RC(30 min) RC(60 min) and the RC(total) after a 60-min repair interval demonstrated no significant difference between the two groups. Furthermore, when comparing grades of DNA migration (OTM<2, 2-5, 5-10, 10-20, 20-30 and >30), there were no differences evident. In this investigation, rejoining of DNA single strand breaks in lymphocytes of NPC and NTD appeared to be accomplished to an equal degree and in equal time periods. However, the applied method does not give evidence concerning the quality of the single strand break rejoining processes. In this group of patients, tumorigenesis in NPC could not be associated with a decreased DNA repair capacity.

Sensitivity to DNA-damage induction and chromosomal alterations in mucosa cells from patients with and without cancer of the oropharynx detected by a combination of Comet assay and fluorescence in situ hybridization

In addition to exogenous risk factors, the development of head and neck cancer is based on genetic alterations and individual sensitivity to mutagens. The DNA-damaging effect of xenobiotics and the location of chromosomal changes warrant further investigation. The aim of this study was to evaluate variance in structural genetic changes in human epithelia as target cells for head and neck carcinogenesis. The combination of the single-cell gel electrophoresis (Comet) assay with the fluorescence in situ hybridization (FISH) technique is presented to examine differences in sensitivity to DNA-damage induction and in alterations of chromosomes 1, 3, 5 and 8 in patients with and without squamous cell carcinoma of the oropharynx. Macroscopically healthy biopsies from the mucosa, taken at a distance from the tumor of 10 patients with oropharyngeal carcinoma and from 10 patients without tumor were harvested during surgery. Cells were isolated by enzymatic digestion and incubated with benzo[a]pyrene-diolepoxide (BPDE), causing DNA-adduct formation by covalent binding of BPDE with DNA bases. The cells were subsequently analyzed by means of the Comet assay to separate DNA fragments and to visualize the DNA-damage. A hybridization mixture with whole-chromosome paints for Chr1, Chr3, Chr5 and Chr8 was added. After fluorescent staining, the entire DNA and the DNA of chromosomes 1, 3, 5 and 8 were evaluated by digital analysis. BPDE caused significant DNA damage in oropharyngeal mucosa cells of patients with and patients without carcinoma. No differences in the amount of DNA damage could be observed between patients suffering from sqamous cell carcinoma and patients without malignancy. Evaluation of chromosomal alterations, however, revealed significantly higher damage levels in chromosomes 3, 5 and 8 compared with chromosome 1 in tumor patients. In contrast, for patients without oropharyngeal carcinoma no differences in chromosomal alterations could be observed. The Comet assay could be combined with FISH to examine the sensitivity to DNA-damage induction and chromosomal alterations in human epithelial cells exposed to a genotoxic agent. Chromosomal breakage is increased for chromosomes 3, 5 and 8 as compared with chromosome 1, indicating a higher sensitivity of these chromosomes in epithelial cells of tumor patients. Using Comet/FISH on human epithelia, selected genetic alterations can be detected, which supports description of endogenous risk factors in carcinogenesis of the upper aerodigestive tract.

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.

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.

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.

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.

[Preservation of mucosal specimens before processing in the alkaline single cell microgel electrophoresis assay]

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]

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]

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.

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.

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.

[Genotoxicity of phthalates. On the discussion of plasticizers in children's toys]

BACKGROUND AND OBJECTIVE

Recently, health hazards caused by phthalates, which are added as softeners to plastic materials, have been subject to discussion. The aim of the present study was to measure possible genotoxic impacts on mucosal cells of the upper aerodigestive tract.

PATIENTS AND METHODS

Genotoxicity tests for dibutyl phthalate (DBP) and diisobutyl phthalate (DiBP) on human oropharyngeal mucosa in vitro were performed using the alkaline comet assay. Specimens (n = 50) were harvested from the surface of ectomized tonsils.

RESULTS

DBP and DiBP caused significant DNA damage in human mucosal cells of the upper aerodigestive tract. The impact of DiBP was higher than that of DBP.

CONCLUSIONS

A genotoxic impact of phthalates on human epithelial cells as a hazard to babies and children chewing these materials cannot be excluded and demands further investigation. The DNA damage measured in this study may represent one factor in the complex genesis of neoplasms in the upper aerodigestive tract.

Mutagen sensitivity of nasopharyngeal cancer patients

Primary nasopharyngeal carcinomas (NPCs) may be of various types, including squamous cell carcinomas, undifferentiated carcinomas, and lymphoepitheliomas. Tumor initiation has been linked to the Epstein-Barr virus and, in some geographical regions, to alimentary factors. Possible hereditary components for the appearance of NPCs have not yet been clearly identified. In this study, genetic sensitivity to the genotoxic effects of carcinogenic xenobiotics as an endogenous risk factor of tumor initiation was investigated. The single cell microgel electrophoresis assay was used to quantify chemically-induced DNA damage in lymphocytes of 30 NPC patients and 30 non-tumor donors. The xenobiotics investigated were N'-nitrosodiethylamine, sodium dichromate, and nickel sulphate, with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and dimethyl sulfoxide (DMSO) as positive and negative controls, respectively. The extent of DNA migration in the solvent control cultures was not significantly different between the two groups (1.2+/-0.5 mean Olive tail moment and standard deviation of 30 individuals for NPC patients; 1.1+/-0.4 for non-tumor donors). With constant exposure and electrophoretic conditions, genotoxic effects of varying degrees were induced by the different xenobiotics in tumor and non-tumor patients (nickel sulphate: 7.1+/-2.5 for NPC patients and 5.9+/-1.6 for non-tumor donors; sodium dichromate: 18.1+/-5.3 for NPC patients and 16.2+/-5.4 for non-tumor donors; MNNG: 47.8+/-13.3 for NPC patients and 52.7+/-13.6 for non-tumor donors). Only N'-nitrosodiethylamine proved to induce significantly more DNA migration in lymphocytes of tumor patients (9.8+/-3.1) as compared to non-tumor patients (8.2+/-2.3). Although for sodium dichromate the degree of DNA migration did not significantly differ, variability in migration patterns proved to be lower in the tumor group. Mutagen sensitivity of NPC patients was shown to be elevated for a selected xenobiotic, whereas a general elevation of DNA fragility was not present. Further studies on mutagen sensitivity as an endogenous risk factor influencing the susceptibility of patients at the time of first diagnosis of nasopharyngeal carcinomas are warranted.

[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.

Altered genotoxicity in mucosal cells of head and neck cancer patients due to environmental pollutants

The complexity of carcinogenesis in squamous cell cancer (SCC) of the upper aerodigestive tract requires examining environmental risk factors, including mutagen sensitivities to xenobiotics. Three environmental, occupational, and habitual pollutants - dibutylphthalate (DBP), diisobutylphthalate (DiBP), and N'nitrosodiethylamine (NDELA) - were submitted to genotoxicity testing on mucosal biopsy specimens of tumor and nontumor patients in vitro. The single-cell microgel electrophoresis (Comet) assay was applied to detect DNA strand breaks in human epithelial cells of the pharynx and larynx from nontumor patients, patients with SCC of the oropharynx and patients with SCC of the larynx. Genotoxicity was found for DBP, DiBP, and NDELA in cells derived from nontumor and tumor patients. With respect to phthalates, Olive tail moment (OTM) levels were higher in patients with SCC of the oropharynx and SCC of the larynx (P < 0.01), the latter showing even more pronounced genotoxicity for DiBP. Testing epithelial cells of the patients with either oropharyngeal or laryngeal SCC for NDELA demonstrated results similar to the nontumor patients. Present findings indicate heterogeneous mutagen sensitivities to some but not all xenobiotics.

[DNA repair if mucous membrane cells and lymphocytes with the comet assay]

BACKGROUND

Exogenous and endogenous risk factors are involved in human carcinogenesis of the head and neck. Noteworthy hereditary factors include mutagen sensitivity and the individual's capacity for DNA repair. Repair mechanisms influence different phases of mutation and malignant transformation. The present study introduces a highly sensitive method for evaluating the repair capacity of human mucosal cells and lymphocytes.

METHOD

Human epithelia of the nose and peripheral lymphocytes were incubated with the tobacco-related carcinogen N'nitrosodiethylamine (NDEA). The solvent dimethylsulfoxide (DMSO) served as negative control. Following repair times of 0 min, 15 min and 30 min, the cells were subjected to a modified version of the alkaline microgel electrophoresis technique (Comet assay). The data were digitally analyzed after fluorescent staining.

RESULTS

Using the Comet assay, DNA repair could be quantified in human mucosal cells and in lymphocytes. The majority of DNA strand breaks induced by NDEA were repaired within 15 min in both cell types.

CONCLUSIONS

Up to now, the Comet assay has been the preferred method for demonstrating substance-induced DNA damage. It has been used in repair studies involving lymphocytes, bacterial systems and animal-derived cells. A modified version of this method, however, can be used to quantify DNA repair in human mucosal cells and peripheral lymphocytes targeted by carcinogens. It is thus possible to evaluate an endogenous factor involved in the development of malignant transformations in mucosal cells of the upper aerodigestive tract.

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.

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.

[Mutagen sensitivity of patients with laryngeal and oropharyngeal carcinoma]

BACKGROUND

Carcinogenesis in the larynx and oropharynx is often associated with excessive exposure to tobacco smoke and alcohol. However, attention is increasingly being focused on genetically determined mutagen sensitivities and on the mutagenic impact of xenobiotics. The purpose of this study was to evaluate the genotoxicity of phthalates (plasticizers widely used in synthetic materials), as well as nitrosamines and polycyclic aromatic carbohydrates, on laryngeal and oropharyngeal epithelia and peripheral lymphocytes of patients with laryngeal and oropharyngeal carcinomas.

METHODS

The comet assay was used to detect induced DNA strand breaks. Macroscopically healthy supraglottic and oropharyngeal epithelia of patients with laryngeal and oropharyngeal tumors, respectively, and lymphocytes were investigated with dibutyl phthalate (DBP), diisobutylphthalate (DiBP). N'nitrosodiethylamine (NDELA), and benzo[a]pyrene (BaP). The Olive Tail Moment (OTM) was used to quantify genotoxicity.

RESULTS

For the first time, the genotoxicity of DBP and DiBP was demonstrated in laryngeal and oropharyngeal epithelia, as well as in peripheral lymphocytes, of patients suffering from laryngeal and oropharyngeal carcinomas. OTM levels for NDELA were higher than for phthalates; levels for BaP were lower. Testing of lymphocytes and mucosa showed no significant differences among the various substances.

CONCLUSIONS

Phthalates show a genotoxic impact on epithelia of tumor patients. OTM levels were higher than in nasal and oropharyngeal mucosa of healthy donors in results reported earlier. Thus, specific susceptibilities to these xenobiotics need to be discussed. No such effect was demonstrated for NDELA and BaP. In tumor patients, no significant differences could be shown in mutagenic sensitivities in mucosal cells and lymphocytes.

[Softeners in synthetic materials--are they harmful to humans? First indication of genotoxic effect of phthalates]

BACKGROUND

A wide range of phthalate derivatives are added to plastic materials, including PVC, as softeners. Although the possibility that these substances pose a risk to human health continues to be discussed, a definitive answer has yet to be found. In particular, their genotoxic potential has not so far been investigated in human material.

METHOD

The literature is reviewed to provide an overview of the present state of such discussions. We carried out our own in vitro investigations into the genotoxicity of dibutylphthalate (DBP) and diisobutylphthalate (DIBP) in human mucosa with the aid of the alkaline version of single-cell microgel electrophoresis.

RESULTS

Various effects of phthalates have been identified in the animal model, for example, changes in blood count, anti-androgenic or xenoestrogenic effects, proliferation of peroxisomes and progression of liver cell tumors. In humans, elevated phthalate levels following treatment with extracorporeal oxygenation have not been found to have any direct toxic effects. Initial results of our in vitro studies revealed a clear genotoxic potential in human oropharyngeal and nasal mucosa.

CONCLUSION

Using suitable test methods, phthalates need further investigation for their health hazard potential in humans. In vitro experiments with two substances of this class involving human mucosa, indicate the possibility of geno-toxic effects.