Munich Oktoberfest experience: remarkable impact of sex and age in ethanol intoxication

Approximately 5,000 of 6 million annual visitors of the Oktoberfest in Munich have to undergo medical treatment. Patients with alcohol intoxication without trauma or further complications are all treated in a specialized medical camp. We studied these patients in order to identify risk factors and to assess the relevance of the Glasgow Coma Score (GCS) and of ethanol blood concentrations for patient management. In 2004 totally 405 patients suffering from ethanol intoxication without trauma were treated in the medical camp. A complete set of the following data was obtained from all 405 patients: GCS, ethanol blood concentration, age, sex, blood pressure (mean, systolic and diastolic), body temperature, heart rate, blood sugar, GOT, gamma-GT, and CK. A multivariate logistic regression model was applied to identify risk factors predicting patients at increased risk of hospitalization. Low GCS (< or =8 vs. >8, OR: 4.18, CI: 1.96-8.65) low age (20-29 vs. > or =30 years, OR: 2.35, CI: 1.05-5.65) and male gender (male vs. female, OR: 3.58, CI: 1.36-9.34) independently predicted patients that had to be hospitalized. All other parameters including ethanol blood concentrations were not explanatory. Patients with GCS < or = 8 (n = 66) had a lower median blood pressure (P = 0.0312) and showed a smaller increase in blood pressure during the observation period compared to patients with GCS > 8 (P < 0.001), suggesting that this subgroup may require longer recovery periods. Men aged 20-29 years were at highest risk for hospital admission. Increased risk could not be explained by higher ethanol blood concentrations in this subgroup. Importantly, GCS < 6 does not justify endotracheal intubation in ethanol intoxicated patients, when further complications, such as trauma, can be excluded.

Relevance of the deletion polymorphisms of the glutathione S-transferases GSTT1 and GSTM1 in pharmacology and toxicology

Although cytosolic glutathione S-transferase (GST) enzymes occupy a key position in biological detoxification processes, two of the most relevant human isoenzymes, GSTT1-1 and GSTM1-1, are genetically deleted (non-functional alleles GSTT1*0 and GSTM1*0) in a high percentage of the human population, with major ethnic differences. The structures of the GSTT and GSTM gene areas explain the underlying genetic processes. GSTT1-1 is highly conserved during evolution and plays a major role in phase-II biotransformation of a number of drugs and industrial chemicals, e.g. cytostatic drugs, hydrocarbons and halogenated hydrocarbons. GSTM1-1 is particularly relevant in the deactivation of carcinogenic intermediates of polycyclic aromatic hydrocarbons. Several lines of evidence suggest that hGSTT1-1 and/or hGSTM1-1 play a role in the deactivation of reactive oxygen species that are likely to be involved in cellular processes of inflammation, ageing and degenerative diseases. There is cumulating evidence that combinations of the GSTM1*0 state with other genetic traits affecting the metabolism of carcinogens (CYP1A1, GSTP1) may predispose the aero-digestive tract and lung, especially in smokers, to a higher risk of cancer. The GSTM1*0 status appears also associated with a modest increase in the risk of bladder cancer, consistent with a GSTM1 interaction with carcinogenic tobacco smoke constituents. Both human GST deletions, although largely counterbalanced by overlapping substrate affinities within the GST superfamily, have consequences when the organism comes into contact with distinct man-made chemicals. This appears relevant in industrial toxicology and in drug metabolism.

Expression of cytochrome P450 enzymes CYP1A1, CYP1B1, CYP2E1 and CYP4B1 in cultured transitional cells from specimens of the human urinary tract and from urinary sediments

Expression of cytochromes P450 CYP1A1, CYP1B1, CYP2E1 and CYP4B1 was analysed on the transcript level in human urothelial cells obtained by various methods. As a source of urothelial cells, exfoliated cells in urine samples were used. Their expression profiles were determined either immediately after centrifugal enrichment (n=4) or after their cultivation and propagation (n=8). Another source of urothelial cells were ureter specimens from surgical subjects (n=4). Generally, expression was most prominent for CYP1B1 and CYP4B1 among the CYP transcripts analysed. CYP1B1 mRNA was detected in all samples investigated except for one ureter specimen. CYP4B1 mRNA was present in cell cultures from three out of eight healthy subjects, in three out of four directly investigated urinary sediments and in the cells of all five ureter specimens of four donors investigated after resection and subsequent cell culture. In most cases, CYP2E1 transcript levels were lower than those of CYP1B1 and CYP4B1. CYP2E1 mRNA was detected in cell cultures of six out of eight healthy subjects, in one out of four urinary sediments and in three out of five ureter specimens. CYP1A1 mRNA was clearly observed only in cells from resected ureters. In cell cultures the relative mRNA expression levels varied with subjects interindividually, intraindividually and also during the time of cell culture. The study demonstrates constitutive mRNA expressions of xenobiotic metabolising CYP enzymes in human urothelial cells obtained by different methods. In particular, transcripts of CYP1B1 and CYP4B1 are present, coding for enzymes which are active in the metabolism of polycyclic aromatic hydrocarbons and arylamines, respectively.

Challenges to environmental toxicology and epidemiology: where do we stand and which way do we go?

Modern toxicology investigates a wide array of both old and new health hazards. Priority setting is needed to select agents for research from the plethora of exposure circumstances. The changing societies and a growing fraction of the aged have to be taken into consideration. A precise exposure assessment is of importance for risk estimation and regulation. Toxicology contributes to the exploration of pathomechanisms to specify the exposure metrics for risk estimation. Combined effects of co-existing agents are not yet sufficiently understood. Animal experiments allow a separate administration of agents which can not be disentangled by epidemiological means, but their value is limited for low exposure levels in many of today's settings. As an experimental science, toxicology has to keep pace with the rapidly growing knowledge about the language of the genome and the changing paradigms in cancer development. During the pioneer era of assembling a working draft of the human genome, toxicogenomics has been developed. Gene and pathway complexity have to be considered when investigating gene-environment interactions. For a best conduct of studies, modern toxicology needs a close liaison with many other disciplines like epidemiology and bioinformatics.

Comparative responses of three rat strains (DA/Han, Sprague-Dawley and Wistar) to treatment with environmental estrogens

The rat uterotrophic assay is a widely used screening test for the detection of estrogenic, endocrine-disrupting chemicals. Although much attention has been paid to identifying protocol variables and reproducibility between laboratories the question whether toxicodynamic and toxicokinetic variations of different strains may affect their sensitivity to estrogenic stimuli has been rarely addressed. We have compared the estrogenic activity of the environmental chemicals genistein (GEN), bisphenol A (BPA) and p- tert-octylphenol (OCT) in DA/Han (DA), Sprague-Dawley (SD) and Wistar (WIS) rats after repeated oral application. Rats were treated per os for 3 days with different doses of these weakly estrogenic compounds and the potent reference estrogen ethinylestradiol (EE). Then uterine wet weight, thickness of the uterine epithelium, uterine gene expression of clusterin (CLU), and thickness of the vaginal epithelium were examined as parameters for estrogenic potency of the test compounds in the three strains of rats. The uterotrophic response to treatment with BPA, OCT and GEN was similar in the three strains, and allowed us to rank them as GEN being more potent than OCT, and BPA being the weakest estrogen. This was confirmed by analysis of other biological endpoints, despite some differences in the magnitude of their response among strains and to distinct compounds. For instance, the uterus wet weight response to EE treatment indicated lower sensitivity of SD rats than that of DA and WIS rats, but this was not observed for responses of the uterine or vaginal epithelium. Moreover, blood concentrations were assessed at the time of killing and related to biological responses: plasma levels of total and unconjugated BPA and GEN depended upon the dose administered and varied to some extent within treatment groups and among the three rat strains. However, there was no good correlation in the three strains between individual compound concentrations analysed 24 h after the last dose and the uterotrophic wet weights. Summarising our results, we conclude that the sensitivity of various biological endpoints can differ slightly between strains of rats. On the other hand, our data demonstrate that the choice of the rat strain does not lead to pronounced differences in the evaluation of estrogenic activities of chemicals, especially when different biological endpoints are included in the analysis.

Reliability of non-invasively acquired human genomic DNA as a substrate for real-time PCR-assisted analysis of genetic polymorphisms

Molecular epidemiological studies require high numbers of participants. The combination of an non-invasive access to human DNA with a rapid genotyping analysis, e.g. by use of LightCycler assisted real-time polymerase chain reaction (PCR), can be helpful in conducting such trials. The aim of our study was to define, for the first time, the use of LightCycler technology in analysis of non-invasively derived DNA. DNA extracted from blood, mouthwash and buccal cytobrush samples from 100 volunteers was analyzed for the genotypes of cytochrome P450 CYP1B1, and glutathione S-transferases GSTT1, GSTM1 and GSTP1. The median amounts of DNA isolated from blood, mouthwash and buccal cytobrush samples were 95, 11 and 8 microg, respectively. While genotyping for CYP1B1 codon 432 polymorphism and GSTP1 codon 105 polymorphism resulted in a complete correspondence for all three modes of sampling, the identification of individuals with null-genotype for GSTT1 or GSTM1 failed in some cases due to atypical courses of the corresponding melting curves, leading to high false-positive rates in the group of non-invasively derived samples. Thus, the results presented here call for caution in using LightCycler assisted real-time PCR in non-invasively collected samples, at least when appropriate control strategies are not implemented.

Challenging dogma: thresholds for genotoxic carcinogens? The case of vinyl acetate

Although many questions remain unanswered, the general principle of the sequence of events leading to cancer after exposure to genotoxic carcinogens has become increasingly clear. This helps to understand the parameters that influence the shape of the dose-effect curve for carcinogenesis, including metabolic activation and inactivation of carcinogens, DNA repair, cell cycle control, apoptosis, and control by the immune system. A linear dose-response relationship with no observable threshold seems to be a conservative but adequate description for the carcinogenic activity of many genotoxic carcinogens, such as aflatoxin B1, the tobacco-specific nitrosoketone NNK, and probably N,N-diethylnitrosamine. However, extrapolation models connecting the high-level risk to the zero intercept have clearly resulted in overestimations of risk. Vinyl acetate is an example that is discussed extensively in this review. At extremely high and toxic doses, vinyl acetate is carcinogenic in rats and mice and causes chromosomal aberrations. In tissues of contact, vinyl acetate is converted to acetic acid and acetaldehyde. Only when threshold levels are achieved do critical steps in the mechanism ultimately leading to cancer become active, namely pH reduction in exposed cells of more than 0.15 units leading to cytotoxicity, damage to DNA, and regenerative proliferation. Consistent with the known exposure to endogenous acetic acid and acetaldehyde, tissues sustain a certain level of exposure without adverse effects. Physiological modeling shows that the conditions necessary for carcinogenesis are in place only when threshold levels of vinyl acetate are exceeded. The example of vinyl acetate underlines the importance of toxicological research that unequivocally identifies genotoxic carcinogens acting through a threshold process.

Interaction of metal salts with cytoskeletal motor protein systems

Interactions of chemicals with the microtubular network of cells may lead to genotoxicity. Micronuclei (MN) might be caused by interaction of metals with tubulin and/or kinesin. The genotoxic effects of inorganic lead and mercury salts were studied using the MN assay and the CREST analysis in V79 Chinese hamster fibroblasts. Effects on the functional activity of motor protein systems were examined by measurement of tubulin assembly and kinesin-driven motility. Lead and mercury salts induced MN dose-dependently. The no-effect-concentration for MN induction was 1.1 microM PbCl(2), 0.05 microM Pb(OAc)(2) and 0.01 microM HgCl(2). The in vitro results obtained for PbCl(2) correspond to reported MN induction in workers occupationally exposed to lead, starting at 1.2 microM Hg(II) (Vaglenov et al., 2001, Environ. Health Perspect. 109, 295-298). The CREST Analysis indicate aneugenic effects of Pb(II) and aneugenic and additionally clastogenic effects of Hg(II). Lead (chloride, acetate, and nitrate) and mercury (chloride and nitrate) interfered dose-dependently with tubulin assembly in vitro. The no-effect-concentration for lead salts in this assay was 10 microM. Inhibition of tubulin assembly by mercury started at 2 microM. The gliding velocity of microtubules along immobilised kinesin molecules was affected by 25 microM Pb(NO(3))(2) and 0.1 microM HgCl(2) in a dose-dependent manner. Our data support the hypothesis that lead and mercury genotoxicity may result, at least in part, via disturbance of chromosome segregation via interaction with cytoskeletal proteins.

Children as a sensitive subgroup and their role in regulatory toxicology: DGPT workshop report

There is increasing discussion that children might be considered as a specific subgroup in public health regulations which could be more sensitive than the average "adult" human being. Differences between children and adults, with regard to susceptibility towards toxicants, may result from a combination of toxicokinetic, toxicodynamic and exposure factors. Kinetic factors are of importance mainly in the early postnatal period, largely as the result of immature elimination systems, i.e. metabolising enzymes and/or renal function. Specific vulnerability may prevail during several time periods, related to the development and maturation of organs (for example, brain, bone, endocrine system). For some substances, it has been shown that children at a specific age are less sensitive than adults. Specific exposures of toddlers to environmental chemicals may be high due to their moving behaviour and hand-to-mouth activities. Existing scenarios and models for exposure of children should be improved, in particular with respect to different ages. The outcome of model calculations must be verified by human biomonitoring analysis. At present, there is ongoing discussion of toxicological test models suitable to delineate human postnatal development. Experience with infant-orientated test systems is scarce (for example in developmental neurotoxicity). In general, tools for predicting toxicological sensitivity of children must be further improved. Regulators should also be aware that reduction of lifestyle-related toxic exposures such as smoking and drug abuse in children and adolescents is now an increasing public health problem in many countries.

Transplacental transfer of the phytoestrogen daidzein in DA/Han rats

Disposition and transplacental transfer of the phytoestrogen daidzein was studied in pregnant DA/Han rats on day 18 of gestation. Daidzein concentrations were determined by HPLC in maternal blood, maternal organs (liver, kidney, uterus), placenta and fetuses (liver and residual tissues) at specific times (5, 10, 20, 40 and 120 min) after intravenous administration of 10 mg/kg body weight. Early after injection, the majority of circulating daidzein was still in the aglycone form; at later time points the majority consisted of conjugates. The initially high isoflavone concentration in maternal plasma (about 25 microg/ml at 5 min) decreased rapidly within the first hour, and after 2 h total daidzein was below 1 microg/ml. Despite its efficient conjugation, daidzein was rapidly distributed in the organism: peak concentrations were attained 10 min after intravenous administration in all tissues analysed, with mean values of about 31 microg/g in maternal liver, 13 microg/g in kidneys and 5 microg/g in the uterus. Placenta contained about one-tenth the hepatic daidzein concentration, and fetal liver about 1/30 the peak concentration of maternal liver (i.e. 1.3 microg/g, which is one-third the placental concentration). Daidzein levels in tissues then declined in parallel with those in maternal blood. The data show that daidzein is transferred across the placenta of DA/Han rats to fetuses. This is indicative of a rapid transfer from the mother to the fetus, but also that efficient hepatic extraction of daidzein from the maternal blood occurs. Since dietary phytoestrogens account for a significant proportion of human exposure to potential endocrine modulators, and since the placenta does not represent a barrier to daidzein or related estrogenic isoflavones, the consequences of these exposures early in life should be examined and monitored carefully.

Influence of polymorphisms of the human glutathione transferases and cytochrome P450 2E1 enzyme on the metabolism and toxicity of ethylene oxide and acrylonitrile

A cohort of 59 persons with industrial handling of low levels of acrylonitrile is being studied as part of a medical surveillance programme. Previously, an extended haemoglobin adduct monitoring (N-(cyanoethyl)valine and N-(hydroxyethyl)-valine) was performed regarding the glutathione transferases hGSTM1 and hGSTT1 polymorphisms but no influence of hGSTM1 or hGSTT1 polymorphisms on specific adduct levels was found. A compilation of case reports of human accidental poisonings had pointed to significant individual differences in human acrylonitrile metabolism and toxicity. Therefore, a re-evaluation of the industrial cohort included known polymorphisms of the glutathione transferases hGSTM3 and hGSTP1 as well as of the cytochrome P450 CYP2E1. A detailed statistical analysis revealed that exposed carriers of the allelic variants of hGSTP1, hGSTP1*B/hGSTP1*C, characterized by a single nucleotide polymorphism at nucleotide 313 which results in a change from Ile to Val at codon 104, had higher levels of the acrylonitrile-specific haemoglobin adduct N-(cyanoethyl)valine compared to the carriers of the codon 113 alleles hGSTP1*A and hGSTP1*D. The single nucleotide polymorphism at codon 113 of hGSTP1 (hGSTP1*A/hGSTP1*B versus hGSTP1*C/hGSTP1*D) did not show an effect, and also no influence was seen on specific haemoglobin adduct levels of the polymorphisms of hGSTM3 or CYP2E1. The data, therefore, point to a possible influence of a human enzyme polymorphism of the GSTP1 gene at codon 104 on the detoxication of acrylonitrile which calls for experimental toxicological investigation. The study also confirmed the impact of GSTT1 polymorphism on background N-(hydroxyethyl)-valine adduct levels in haemoglobin which are caused by endogenous ethylene oxide.

Procedures for health risk assessment in Europe

This report compares cancer classification systems, health risk assessment approaches, and procedures used for establishing occupational exposure limits (OELs), in various European countries and scientific organizations. The objectives were to highlight and compare key aspects of these processes and to identify the basis for differences in cancer classifications and OELs between various scientific organizations and countries. Differences in cancer classification exist in part due to differences in the ultimate purpose of classification and to the relative importance of different types of data (i.e., animal vs human data, mechanistic data, and data from benign vs malignant tumors). In general, the groups surveyed tend to agree on classification of chemicals with good evidence of carcinogenicity in humans, and agree less on classification of chemicals with positive evidence in animals and inadequate or limited evidence in humans. Most entities surveyed distinguish between genotoxic and nongenotoxic chemicals when conducting risk assessments. Although the risk assessment approach used for nongenotoxic chemicals is fairly similar among groups, risk assessment approaches for genotoxic carcinogens vary widely. In addition to risk assessment approaches, other factors which can affect OELs include selection of the critical effect, use of health-based vs technology-based exposure limits, and consideration of technological feasibility and socioeconomic factors.

N-acetyltransferase 2 phenotype in painters with bladder cancer and controls

AIM

This study was designed to evaluate the impact of N-acetyltransferase 2 (NAT2, substrate: aromatic amines) in painters with bladder cancer and controls.

BACKGROUND

Until the beginning of the 1960s, painters in Germany have used, among others, azo dyes based on carcinogenic aromatic amines.

MATERIALS AND METHODS

Sixteen painters with bladder cancer and 26 healthy painters (controls) who were from the same area in Germany and in the same age group (+/-5 years) were recruited into the study. All subjects were phenotyped for NAT2 by the molar ratio of two caffeine metabolites in the urine which was determined by the high performance liquid chromatography (HPLC) method. The number of years working as a painter, age at first exposure to paints and the life-time smoking habits of subjects were noted.

RESULTS

Fourteen cases and 23 controls had been exposed to paints before 1960. Age at first exposure to paint was 15.5 years (SD 5.3) in cases and 16.3 (SD 4.9) years in controls. Cases had worked 31.1 years (SD 15.0) and controls had worked 44.8 years (SD 7.2) as painters. Four cases and 7 controls were non-smokers. In this study, 88% of cases and 65% of controls were of the "slow" acetylation and phenotype,

CONCLUSION

The result point to and impact of the slow acetylation status as an individual risk factor for bladder cancer in persons occupationally exposed to amounts of carcinogenic aromatic amines released from water-soluble azo dyes.

Biological monitoring in workers in a nitrobenzene reduction plant: haemoglobin versus serum albumin adducts

The high priority of monitoring workers exposed to nitrobenzene is a consequence of clear findings of experimental carcinogenicity of nitrobenzene and the associated evaluations by the International Agency for Research on Cancer. Eighty male employees of a nitrobenzene reduction plant, with potential skin contact with nitrobenzene and aniline, participated in a current medical surveillance programme. Blood samples were routinely taken and analysed for aniline, 4-aminodiphenyl (4-ADP) and benzidine adducts of haemoglobin (Hb) and human serum albumin (HSA). Also, levels of methaemoglobin (Met-Hb) and of carbon monoxide haemoglobin (CO-Hb) were monitored. Effects of smoking were straightforward. Using the rank sum test of Wilcoxon, we found that very clear-cut and statistically significant smoking effects (about 3-fold increases) were apparent on CO-Hb (P = 0.00085) and on the Hb adduct of 4-ADP (P = 0.0006). The mean aniline-Hb adduct level in smokers was 1.5 times higher than in non-smokers; the significance (P = 0.05375) was close to the 5% level. The strongest correlation was evident between the Hb and HSA adducts of aniline (r(s) = 0.846). Less pronounced correlations (but with P values < 0.02) appeared between aniline-Hb and 4-ADP-Hb adducts (r(s) = 0.388), between 4-ADP and 4-ADP-HSA adducts (r(s) = 0.373), and between 4-ADP-Hb and aniline-HSA adducts (r(s) = 0.275). In view of the proposal for additional use of the aniline-HSA adduct for biological monitoring, particularly in cases of acute overexposures or poisonings, the strong correlation of the Hb and HSA conjugates is noteworthy; the ratio aniline-HSA:aniline-Hb was 1:42 for the entire cohort.

Real-time PCR analysis of the N-acetyltransferase NAT1 allele *3, *4, *10, *11, *14 and *17 polymorphism in squamous cell cancer of head and neck

Although tobacco smoke has been established as a main risk factor in the development of head and neck squamous cell cancer (HNSCC), genetic polymorphisms of xenobiotic metabolizing enzymes are supposed to modulate an individual's susceptibility to smoking-related HNSCC. N-acetyltransferase (NAT) 1 gene is known to be polymorphic and its protein product is implicated in the activation and detoxification of carcinogens, such as aromatic amines, present in tobacco smoke. We developed a rapid and reproducible LightCycler-assisted real-time polymerase chain reaction (PCR) for NAT1 genotyping, which allowed the parallel differentiation of NAT1*3, *4, *10 and *11 alleles and separately of NAT1*14 and *17 alleles within 60 min without the need for further post-PCR processing. In order to investigate the role of the NAT1 gene polymorphism as a risk-modifying factor in HNSCC, we tested for the presence of NAT1*3, *4, *10, *11, *14 and *17 alleles in a case-control study of 291 HNSCC patients and 300 healthy controls of Caucasian origin. Our findings suggest that in Caucasians, the risk of HNSCC is not associated with NAT1 polymorphism. The overall distribution of NAT1 allele frequencies was not significantly different among cases and controls. The presence of the fast acetylator NAT1*10 and NAT1*11 alleles did not significantly increase the risk of HNSCC and no modifying effect of NAT1*10 was observed among smokers. This new approach in NAT1 genotyping substantially increases throughput of sample analysis and, therefore, enhances opportunities to study NAT1 as a risk factor in different cancers in large-scale studies.

Re-evaluation of the effect of smoking on the methylation of N-terminal valine in haemoglobin

In view of the established extrapulmonary cancer sites targeted by smoking a multiplicity of compounds and mechanisms might be involved. It has been debated that smoking caused increased incidence of N-methylvaline at the N-terminus of haemoglobin. Because this could indicate a relevance of methylating nitrosamines in tobacco smoke, data are presented from an industrial cohort of 35 smokers and 21 non-smokers repeatedly monitored between 1994 and 1999. In general, N-methylvaline adduct levels in haemoglobin of smokers were approximately 50% higher than those of non-smokers. The smoking-induced methylation of haemoglobin is likely to be caused by dimethylnitrosamine (N-nitroso-dimethylamine), a major nitrosamine in side-stream tobacco smoke. The biomonitoring data emphasise the potential value of N-methylvaline as a smoking-related biomarker and call for intensified research on tobacco smoke compounds that lead to macromolecular methylation processes.

Pathological excretion patterns of urinary proteins in miners highly exposed to dinitrotoluene

A cohort of 161 underground miners who had been highly exposed to dinitrotoluene (DNT) in the copper-mining industry of the former German Democratic Republic was reinvestigated for signs of subclinical renal damage. The study included a screening of urinary proteins excreted by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and quantitations of the specific urinary proteins alpha 1-microglobulin and glutathione-S-transferase alpha (GST alpha) as biomarkers for damage of the proximal tubule and glutathione-S-transferase pi (GST pi) for damage of the distal tubule. The exposures were categorized semiquantitatively (low, medium, high, and very high), according to the type and duration of professional contact with DNT. A straight dose-dependence of pathological protein excretion patterns with the semiquantitative ranking of DNT exposure was seen. Most of the previously reported cancer cases of the urinary tract, especially those in the higher exposed groups, were confined to pathological urinary protein excretion patterns. The damage from DNT was directed toward the tubular system. In many cases, the appearance of Tamm-Horsfall protein, a 105-kD protein marker, was noted. Data on the biomarkers alpha 1-microglobulin, GST alpha, and GST pi consistently demonstrated a dose-dependent increase in tubular damage, which confirmed the results of screening by SDS-PAGE and clearly indicated a nephrotoxic effect of DNT under the given conditions of exposure. Within the cluster of cancer patients observed among the DNT-exposed workers, only in exceptional cases were normal biomarker excretions found.

Association of CYP1B1 codon 432 mutant allele in head and neck squamous cell cancer is reflected by somatic mutations of p53 in tumor tissue

Tobacco use is causally associated with head and neck squamous cell cancer (HNSCC). Here, we present the results of a case-control study that investigated the effects that the genetic variants of the cytochrome (CYP)1A1, CYP1B1, glutathione-S-transferase (GST)M1, GSTT1, and GSTP1 genes have on modifying the risk of smoking-related HNSCC. Allelisms of the CYP1A1, GSTT1, GSTM1, and GSTT1 genes alone were not associated with an increased risk. CYP1B1 codon 432 polymorphism was found to be a putative susceptibility factor in smoking-related HNSCC. The frequency of CYP1B1 polymorphism was significantly higher (P < 0.001) in the group of smoking cases when compared with smoking controls. Additionally, an odds ratio (OR) of 4.53 (2.62-7.98) was discovered when investigating smoking and nonsmoking cases for the susceptible genotype CYP1B1*2/*2, when compared with the presence of the genotype wild type. In combination with polymorphic variants of the GST genes, a synergistic-effect OR was observed. The calculated OR for the combined genotype CYP1B1*2/*2 and GSTM1*2/*2 was 12.8 (4.09-49.7). The calculated OR for the combined genotype was 13.4 (2.92-97.7) for CYP1B1*2/*2 and GSTT1*2/*2, and 24.1 (9.36-70.5) for the combination of CYP1B1*2/*2 and GSTT1-expressors. The impact of the polymorphic variants of the CYP1B1 gene on HNSCC risk is reflected by the strong association with the frequency of somatic mutations of the p53 gene. Smokers with susceptible genotype CYP1B1*2/*2 were 20 times more likely to show evidence of p53 mutations than were those with CYP1B1 wild type. Combined genotype analysis of CYP1B1 and GSTM1 or GSTT1 revealed interactive effects on the occurrence of p53 gene mutations. The results of the present study indicate that polymorphic variants of CYP1B1 relate significantly to the individual susceptibility of smokers to HNSCC.

Real-time genotyping of cytochrome P4501A1 A4889G and T6235C polymorphisms

Single nucleotide polymorphisms, such as the cytochrome P450 1A1 (CYP1A1) A4889G and T6235C variants, have been reported to be associated with an increased cancer risk. In order to study their role in molecular-epidemiological studies, we developed a single-step procedure for genotyping these two CYP1A1 polymorphisms using real-time polymerase chain reaction (PCR) and subsequent melting curve analysis. Genotypes of 300 unrelated Caucasians, without prior history of cancer, were determined by real-time PCR and compared to genotypes obtained by restriction fragment length polymorphism PCR. In the population examined, the allele frequency of the CYP1A1 G allele at position 4889 was 0.042, and the frequency of the T allele at position 6235 was 0.10. Five percent of samples disagreed between methods. Sequence analysis of discordant samples revealed that the differences are likely attributed to incomplete digestion of amplicons by the RFLP method. These findings confirm the reliability and utility of real-time PCR as a method for large-scale genotyping.