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ABSTRACT: Hintergrund. Um DNA-schädigende Potenziale von Umweltstoffen darzustellen, wird humane Mukosa eingesetzt, da sie unmittelbar exponiert
ist und Entstehungsort maligner Entartungen sein kann.Da Mukosaproben in der Regel frisch aufgearbeitet werden und dieses
Vorgehen logistische Probleme aufwerfen kann, berichten wir über Erfahrungen mit Kühl- und Gefrierlagerung von Nasenschleimhaut
im Vergleich zur Frischverarbeitung.
Patienten und Methode. Frische hyperplastische Mukosa wurde sofort enzymatisch in Einzelzellen aufgetrennt, in Joklik-Medium über 24 h bei +4°C
aufbewahrt oder bei −80°C gelagert. Für alle Zellen schloss sich eine Exposition mit Fremdstoffen oder Kontrollsubstanzen
an.Zytotoxische Effekte wurden mit dem Trypanblauausschlusstest, genotoxische Effekte mit der alkalischen Einzelzellmikrogelelektrophorese
quantifiziert.Mit dem Wilcoxontest wurde auf unterschiedliche Verteilungen des Migrationsverhaltens der DNA zwischen Sofortverarbeitung
und Kühllagerung bzw.Gefrierlagerung geprüft.
Ergebnisse. Die Zellvitalitäten lagen zwischen 95% und 100%.Für alle Substanzen bis auf N-Nitrosodiethylamin waren die Fragmentwanderungen
nach Kühllagerung oder Frischverarbeitung gleich. Nach Gefrierlagerung zeigten sich für die Kontroll- und Benzo[a]pyreninkubationen
signifikant und für Natriumdichromat im Trend erhöhte Migrationen im Testsystem.Für die übrigen Stoffe ergaben sich keine
Unterschiede in diesem Vergleich.
Schlussfolgerungen. Für Untersuchungen an Nasenschleimhautzellen mit der alkalischen Einzelzellmikrogelelektrophorese außerhalb eines festen
Studienprotokolls erscheint eine 24-h-Lagerung im Nährmedium abhängig von der zu prüfenden Substanz legitim, eine Kryokonservierung
in dem von uns verwendeten Ansatz jedoch nicht.
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°C or for longer periods
at −80°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°C and cryopreservation at −80°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°C,DNA-migration did not rise compared to the samples which were immediately
processed.
Conclusions. Preservation of mucosal specimens at 4°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.
HNO 04/2012; 51(2):134-139. · 0.40 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
HNO 03/2003; 51(2):134-9. · 0.40 Impact Factor
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ABSTRACT: 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.
Laryngo-Rhino-Otologie 08/2002; 81(7):528-33. · 0.97 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
HNO 06/2001; 49(5):378-81. · 0.40 Impact Factor
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ABSTRACT: 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.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 05/2001; 491(1-2):151-61. · 2.85 Impact Factor
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ABSTRACT: 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.
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).
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.
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.
Laryngo-Rhino-Otologie 05/2001; 80(4):187-90. · 0.97 Impact Factor
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ABSTRACT: Hintergrund und Fragestellung. Gesundheitliche Gefährdungen durch Weichmacher in Kunststoffen werden insbesondere für Kinder vielfältig diskutiert. Derivate
der Phthalate werden Polyvinylchlorid und anderen Plastikmaterialien zugesetzt, um diese elastisch oder formbar zu machen.
Ziel der vorliegenden Untersuchungen ist es, mögliche genotoxische Einflüsse von 2 Vertretern der Stoffgruppe der Phthalate
an menschlichen Mukosaproben des Oropharynx in vitro zu messen.
Patienten und Methodik. Die Einzelzellmikrogelelektrophorese wurde zur Überprüfung der Genotoxizität von Dibutylphthalat (DBP) und Diisobutylphthalat
(DiBP) an n=50 Proben oropharyngealer Schleimhaut in vitro eingesetzt.
Ergebnisse. DBP und DiBP zeigten signifikante genotoxische Schädigungen in humanen Schleimhautzellen des oberen Aerodigestivtraktes;
DiBP hatte einen stärker schädigenden Einfluss auf die DNA als DBP.
Schlussfolgerungen. Eine gesundheitliche Gefährdung für Kinder, die mit phthalathaltigen Spielzeugen in Schleimhautkontakt kommen, kann nicht
ausgeschlossen werden und bedarf weiterer Untersuchungen. Das in der vorliegenden Studie gemessene genotoxische Potential
könnte evtl. einen Baustein in einer multifaktoriellen Tumorgenese des Kopf-Hals-Gebiets darstellen.
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.
HNO 04/2001; 49(5):378-381. · 0.40 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Laryngo-Rhino-Otologie 02/2001; 80(1):23-6. · 0.97 Impact Factor
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ABSTRACT: 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.
Teratogenesis Carcinogenesis and Mutagenesis 01/2001; 21(3):189-96.
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ABSTRACT: 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.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 05/2000; 467(1):21-30. · 2.85 Impact Factor
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ABSTRACT: 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.
Environmental and Molecular Mutagenesis 02/2000; 35(1):9-12. · 3.71 Impact Factor
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ABSTRACT: 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.
Archiv für Klinische und Experimentelle Ohren- Nasen- und Kehlkopfheilkunde 01/2000; 257(6):337-42. · 1.29 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Laryngo-Rhino-Otologie 01/2000; 78(12):679-84. · 0.97 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
MMW Fortschritte der Medizin 11/1999; 141(40):46-9.
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ABSTRACT: Proto-oncogenes encoding growth factor receptors constitute several distinct families with close overall structural homology. The highest degree of homology can be observed in their catalytic domains, which are essential for intrinsic tyrosine kinase activity. Growth factor receptors in several of these families play critical roles in the regulation of normal cell growth and development. Some of these molecules have been implicated in the neoplastic process as well. A related DNA fragment distinct from epidermal growth factor receptor and erbB-2 genes was detected by reduced stringency hybridization of v-erbB to normal genomic human DNA. The expression of erbB-3 was studied by southern and northern blot technique in a subset of nine head and neck tumor cell lines, as well as in three immortalized cultures established from normal human salivary glands. No gene amplification of erb-B-3 was noted in any of the head and neck cell lines. The 6.2 kb transcript of erbB-3 was elevated significantly in an epidermoid carcinoma of the larynx (A388) and an esophageal carcinoma (HA 114).
Archiv für Klinische und Experimentelle Ohren- Nasen- und Kehlkopfheilkunde 02/1993; 250(7):392-5. · 1.29 Impact Factor
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ABSTRACT: Proto-oncogenes encoding growth factor receptors constitute several distinct families with close overall structural homology. The highest degree of homology can be observed in their catalytic domains, which are essential for intrinsic tyrosine kinase activity. Growth factor receptors in several of these families play critical roles in the regulation of normal cell growth and development. Some of these molecules have been implicated in the neoplastic process as well. A related DNA fragment distinct from epidermal growth factor receptor and erbB-2 genes was detected by reduced stringency hybridization of v-erbB to normal genomic human DNA. The expression of erbB-3 was studied by southern and northern blot technique in a subset of nine head and neck tumor cell lines, as well as in three immortalized cultures established from normal human salivary glands. No gene amplification of erb-B-3 was noted in any of the head and neck cell lines. The 6.2 kb transcript of erbB-3 was elevated significantly in an epidermoid carcinoma of the larynx (A388) and an esophageal carcinoma (HA 114).
Archiv für Klinische und Experimentelle Ohren- Nasen- und Kehlkopfheilkunde 01/1993; 250(7):392-395. · 1.29 Impact Factor
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ABSTRACT: 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.
ORL 63(3):141-7. · 0.91 Impact Factor
