[Xeroderma pigmentosum (XP) : A genetic disease sheds light on UV-induced skin cancer]. / Xeroderma pigmentosum : Genetische Modellerkrankung bringt Licht ins Dunkel von UV-induziertem Hautkrebs.

The recessively inherited nucleotide excision repair (NER) defect syndrome xeroderma pigmentosum (XP) serves as a model disease for UV-induced skin cancer. XP is characterized by sun-sensitivity, freckling, and poikilodermic skin changes in sun-exposed areas, and a more than 1000-fold increased risk of skin cancer including melanoma as well as basal and squamous cell carcinomas. Seven XP complementation groups (XP-A to XP-G) are known to date representing the defective genes in XP patients. An additional "variant" form (XPV) which is clinically indistinguishable from the complementation groups exhibits defective translesional synthesis. An enhanced understanding of skin cancer development in general can help to identify individuals at an increased risk who should take special precautions, for example to avoid occupational exposures. The position of skin cancer induced by UV-light as an occupational disease in the ordinance on industrial diseases (BKV) is currently a topic of research and discussion in Germany.

[Disease management guidelines in dermatology: implementation, potentials and limitations exemplified by the guidelines for the management of hand eczema]. / Leitlinien in der Dermatologie : Umsetzung, Möglichkeiten und Grenzen am Beispiel der Leitlinie Management von Handekzemen.

In Germany, the "Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften" (AWMF; consortium of scientific medical societies) constitutes the umbrella organisation to conceive, evaluate, and release guidelines. There are 3 stages of development (S1-S3) according to the evidence level and the process of consensus finding. Currently, 59 dermatologic guidelines have been published under the auspices of the Deutsche Dermatologische Gesellschaft (German Dermatological Society). The guideline for the management of hand dermatitis (AWMF-Register-No: 013/053) is an instructive recent example. This guideline clearly demonstrates the benefits of guidelines, i.e. standardized definition of heterogeneous diseases and disease severity as well as standardized therapy algorithms. This is especially important in diseases difficult-to-treat like chronic hand dermatitis. The effective implementation of guidelines with early incorporation of new therapies, for example alitretinoin in the therapy of hand dermatitis, can considerably improve the quality of life of patients.

Previous extrauterine pregnancies and neonatal outcomes in primiparous women--an analysis of the German Perinatal Survey.

AIM: The aim of this study was to compare neonatal outcomes in primiparous women with and without previous extrauterine pregnancies. MATERIAL AND METHODS: We analysed data from 207 171 singleton pregnancies in primiparous women from the German Perinatal Survey of 1998-2000. To minimise confounding factors, we only included women without previous miscarriages or terminations of pregnancy and performed comparisons separately for 3 maternal age groups as well as for all cases together. RESULTS: Women with and without previous extrauterine pregnancies were of comparable height and weight but women with previous extrauterine pregnancies were on average older (29.2 vs. 26.6 years). The preterm birth rate was higher in women with previous extrauterine pregnancies (9.4% vs. 6.8%, odds ratio 1.42 [95% confidence interval 1.18-1.69], p<0.001; analysing all cases together) as was the rate of neonates with a low birth weight ≤ 2 499 g (7.9% vs. 5.7%, odds ratio 1.43 [95% confidence interval 1.17-1.72], p>0.001; analysing all cases together). The proportions of neonates classified as small, appropriate, or large for gestational age were rather similar in women with and without previous extrauterine pregnancies; likewise Apgar scores differed only slightly, although for some comparisons statistical significance was reached in spite of the small magnitude of differences. CONCLUSIONS: Previous extrauterine pregnancies are associated with higher rates of preterm birth and infants of low birth weight in subsequent pregnancies.

Age-specific preterm birth rates after exclusion of risk factors--an analysis of the german perinatal survey.

AIM: A description of preterm birth rates - specified according to maternal age - after the exclusion of anamnestic risk factors. MATERIAL AND METHODS: Data for this study were taken from the German Perinatal Survey of 1998-2000. We analysed data from 492,576 singleton pregnancies and determined preterm birth rates according to maternal age after a stepwise exclusion of anamnestic risk factors. RESULTS: There was a U-shaped dependence of preterm birth rates on maternal age. The lowest preterm birth rate (without excluding women with anamnestic risk factors) was 5.6% at a maternal age of 29 years. The prevalence of some anamnestic risk factors for preterm birth, such as previous stillbirths, spontaneous and induced abortions, and ectopic pregnancies, increased with maternal age. Excluding women with anamnestic risk factors lowered the preterm birth rates substantially. The lowest preterm birth rates were found in women with one previous live birth, without any anamnestic risk factors, and with a body mass index (BMI) of 25.00-29.99. With these restrictions, we found preterm birth rates of under 2% for women aged 24-31 years. CONCLUSIONS: The magnitude and age-dependence of the preterm birth rate can to some extent be explained with the age-dependent prevalence of anamnestic risk factors for preterm birth. Excluding women with anamnestic risk factors from our study population lowered the preterm birth rates substantially.

Combined analysis of polymorphisms of the tumor necrosis factor-alpha and interleukin-10 promoter regions and polymorphic xenobiotic metabolizing enzymes in psoriasis.

Environmental and genetic factors are thought to interact in the manifestation of psoriasis, but knowledge about the involved genes and antigens is incomplete. This study has focused on the association between psoriasis and inherited variations in xenobiotic metabolism and cytokine production as two components that may influence cutaneous immune responses to foreign substances. Polymorphisms of N-acetyltransferase 2, glutathione S-transferases T1 and M1, and promoter polymorphisms of the genes encoding for tumor necrosis factor-alpha and interleukin-10 were investigated in 151 Caucasian patients with psoriasis (100 with type I and 51 with type II psoriasis) and in 123 healthy controls. Polymorphisms were detected by polymerase chain reaction-based methods, restriction enzyme analysis, and direct sequencing. There were no significant differences in the distribution of enzyme polymorphisms or point mutations at position -1082 of the interleukin-10 promoter between the psoriasis groups and the control group. The G-->A polymorphism at position -238 of the tumor necrosis factor-alpha promoter (TNF alpha-238*A allele) was more common in type I psoriasis (27%) than in the controls [9.8%; odds ratio 3.4 (95% confidence interval 1.6-7.2); p = 0.0012; pcorr = 0.018]. Surprisingly, this overrepresentation of the tumor necrosis factor alpha-238*A allele was observed in male patients [4.1 (1.5-11.0); p = 0.0046; pcorr = 0.064] but not in female patients [1.8 (0.5-6.5); p = 0.5]. The G-->A polymorphism at position -308 of the tumor necrosis factor-alpha promoter was less frequent in type I psoriasis (23%) compared with controls (35.7%), although the negative association was weak [0.54 (0.3-0.97); p = 0.041; pcorr = not significant]. The distribution of the TNF alpha-238*A and TNF alpha-238*A alleles was similar in type II patients and controls. Our results suggest that male carriers of the G-->A polymorphism at position -238 of the tumor necrosis factor-alpha promoter are at an increased risk to develop early-onset psoriasis.

Macromolecular adducts in the use of methyl bromide as fumigant.

An HPLC method for analysis of blood protein adducts of methyl bromide was developed. With this method, the alkylated amino acid S-methylcysteine can be quantified both in globin and in serum albumin. The determination of these adducts was implemented in a field study on fumigators who use methyl bromide for the control of insects, nematodes and fungi. Sister chromatid exchange (SCE) was determined in the lymphocytes of the fumigators as an additional biomonitoring parameter. Exposure of persons living in the vicinity of fumigated objects to methyl bromide has been repeatedly reported in the past. The new method for determination of blood protein adducts can be applied for evaluation of such environmental exposure.

Photometric determination of human serum bromide levels--a convenient biomonitoring parameter for methyl bromide exposure.

Methyl bromide is one of the most important pesticides for the control of insects, fungi and nematodes. Serum bromide has been proposed as a biomonitor for occupational exposure to methyl bromide. Therefore, a novel, sensitive photometric method was developed for the determination of serum bromide at concentrations relevant for such exposure. Further possible applications are monitoring of intoxication victims and halothane narcosis. Using the method we have established a mean serum bromide level of 4.13 +/- S.D. 1.05 mg/l (n/64) in a group of healthy female and male volunteers not knowingly exposed to bromide or bromine containing organics. Serum of a subject accidently exposed to methyl bromide revealed a bromide level of 11.5 mg/l serum, while two individuals exposed to methyl iodide had no elevated levels. A group of 30 agricultural workers showed a mean serum bromide level of 15.33 +/- S.D. 1.90 mg/l at the end of the methyl bromide application season.

Mutagenic and cytotoxic effects of exhaust particulate matter of biodiesel compared to fossil diesel fuel.

The mutagenic and cytotoxic effects of diesel engine exhaust (DEE) from a modern passenger car using rapeseed oil methyl esters (RME, biodiesel) as fuel were directly compared to DEE of diesel fuel (DF) derived from petroleum. Combustion particulate matter was collected on glass fiber filters coated with polytetrafluoroethylene (PTFE) from an exhaust dilution tunnel using three different engine test cycles on a chassis dynamometer. Filters were extracted with dichloromethane in a soxhlet apparatus for 12 h. The mutagenicity of the extracts was tested in the Salmonella typhimurium/mammalian microsome plate-incorporation assay using strains TA97a, TA98, TA100, and TA102. The toxicity to the established cell line L929 (mouse lung fibroblasts) was investigated in the neutral red assay. In the tester strains TA98 and TA100 a significant increase of mutations resulted for the particle extracts of both fuels, but for DF the revertants were significantly higher compared to RME. The highest levels of revertants were observed in tests including a cold start phase. This was probably due to incomplete combustion in the cold engine and a lower conversion rate of the cold catalytic converter. Testing with activated liver S9 fraction induced a slightly lower increase of revertants in most experiments. TA97a and TA102 showed no significant enhancement of spontaneous mutations. In the FTP-75 test cycle RME extracts showed slightly higher toxic effects to the L929 cells than DF, whereas in the other tests no significant differences were observable. These results indicate a higher mutagenic potency of DEE of DF compared to RME. This is probably due to the lower content of polycyclic aromatic compounds (PAC) in RME exhaust, although the emitted masses of RME were higher in most test procedures applied in this study.

Glutathione conjugation and cytochrome P-450 metabolism of methyl chloride in vitro.

Possible carcinogenic properties of methyl chloride (CH(3)Cl) have been under discussion since an increase of renal tumours was observed in male B6C3F(1) mice after a 2-yr inhalation exposure to the substance. This was, however, only observed following exposure of male mice to the highest concentration level and not after exposure of females or F344 rats of both sexes. Accumulation of formaldehyde in the kidneys was thought to be responsible for tumour production. In the experiments presented here, cytosolic enzymes from the liver and kidneys of different mouse strains and F344 rats were incubated in head-space vials with methyl chloride or methyl bromide. Following equilibration, the decrease in the concentration of the gases was monitored by gas chromatography as a parameter for metabolic elimination. The metabolic turnover of the methyl halides was found to be significantly higher in female animals than in the males. In parallel experiments, the glutathione content of the liver and kidneys of mice exposed by inhalation to 1000 ppm methyl chloride was determined. In both organs, the glutathione content diminished rapidly after exposure to the methyl halide. The glutathione depletion was slightly greater in females than in males. Finally, the content of cytochromes P-450, P-420 and b5 was determined in liver and kidneys of different mouse strains by difference spectroscopy. Female mice were found to have a lower content of P-450 and b5 than males in the kidneys; there was no such sex difference in liver tissue. The results show that a sex difference in metabolism is unlikely to be responsible for the unique kidney tumour production in male B6C3F(1) mice. Other possible explanations are discussed.

Combination of equilibrium dialysis, melting behaviour and circular dichroism spectroscopy in the study of genotoxic chemicals using ethylene oxide as a model substance.

Ethylene oxide was incubated with different homobasic polynucleotides or dinucleotides. These were subsequently hybridized in equilibrium dialysis with their complementary or noncomplementary counterparts and the equilibrium constants determined. A change of the equilibrium constants after reaction with ethylene oxide corresponded with a shift in melting temperature of the reacted and hybridized macromolecular polynucleotides. The melting temperature was also changed when calf thymus DNA was reacted with ethylene oxide. In addition, the effect of ethylene oxide on the macromolecular single-stranded and double-stranded nucleic acids was investigated by studying the difference in rotation of circularly polarized light with the technique of circular dichroism spectroscopy. The changes in the spectra showed that ethylene oxide had altered the conformation of the hybridized double strands. These data indicated that binding sites in the pyrimidine bases of nucleic acid molecules, besides the previously known N-7 position in the purine base guanine, are attacked by ethylene oxide. There is evidence for the generation of N(4)-(2-hydroxyethyl)cytosine, O(2)-(2-hydroxyethyl)thymine and O(4)-(2-hydroxyethyl)uracil when the corresponding pyrimidine polynucleotides are incubated with ethylene oxide.

Formation of DNA adducts in F-344 rats after oral administration or inhalation of [14C]methyl bromide.

The genotoxic effects of methyl bromide were investigated in a DNA-binding study. [14C]Methyl bromide was administered to male and female F-344 rats orally, or by inhalation from a closed exposure system. DNA adducts were detected in the liver, lung, stomach and forestomach. [14C]3-Methyladenine, [14C]7-methylguanine and [14C]O6-methylguanine were identified using a combination of three different methods of hydrolysing DNA, followed by HPLC or gas chromatography-mass spectrometry. After both oral and inhalation exposure, the highest levels of methylated guanines, especially those of [14C]O6-methylguanine, were found in the stomach and forestomach of the rats. These results clearly demonstrate a systemic DNA-alkylating potential of methyl bromide.

Inhibition of the human erythrocytic glutathione-S-transferase T1 (GST T1) by thimerosal.

We have investigated the interaction of thimerosal, a widely used antiseptic and preservative, with the human erythrocytic GST T1 (glutathione-S-transferase T1). This detoxifying enzyme is expressed in the erythrocytes of solely the human species and it displays a genetic polymorphism. Due to this polymorphism about 25% of the individuals of the caucasian population lack this activity ("non-conjugators"), while 75% show it ("conjugators") (Hallier, E., et al., 1993). Using our newly developed HPLC-fluorescence detection assay (Müller, M., et al., 2001) we have profiled the kinetics of enzyme inhibition in erythrocyte lysates of two individuals previously identified as "normal conjugator" (medium enzyme activity) and "super-conjugator" (very high activity). For the normal conjugator we have determined a 2.77 mM thimerosal concentration to inhibit 50% of the GST T1 activity. In the case of the super-conjugator a 2.3 mM thimerosal concentration causes a 50% inhibition of the enzyme activity. For both phenotypes a 14.8 mM thimerosal concentration results in residual enzyme activities equal to those typically detected in non-conjugator lysates. Thus, sufficiently high doses of thimerosal may be able to change the phenotypic status of an individual--at least in vitro--by inhibition of the GST T1 enzyme.

Psychological effects upon exposure to polyhalogenated dibenzodioxins and dibenzofurans.

Thirty workers who had been exposed to combustion products for several years due to testing of flame retarding qualities of building materials and 30 controls from the same facility were investigated. Concentrations found in samples taken from different places of the facility were up to 14,660 microg/kg for polybrominated dibenzofurans and up to 67.1 microg/kg for polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs). Physical examination, routine laboratory parameters, and blood fat concentrations of PCDDs and PCDFs revealed normal findings. Neurotoxic symptoms showed a weak tendency of overrepresentation among the exposed workers. The frequency of neurobehavioural symptoms increased significantly with trait anxiety independent of exposure to combustion products.

Distribution of ethylene oxide in human blood and its implications for biomonitoring.

The distribution of radioactivity following the incubation of human blood with radio-labelled ethylene oxide was investigated in vitro. After incubation, the individual blood samples were separated into lymphocytes and high (Mr greater than 10,000) and low (Mr less than 10,000) molecular fractions of erythrocyte cytoplasm and blood plasma. The radioactivity was determined in each sample by liquid scintillation counting. In erythrocyte cytoplasm, the distribution of radioactivity showed marked interindividual differences and two distinct groups could be distinguished. The coincidence of these groups with 'conjugators' and 'non-conjugators', in terms of the enzymatic conjugation of methyl halides to glutathione in erythrocytes, suggests a common principle, such as enzyme polymorphism. Such polymorphism has been described for glutathione S-transferase mu in the human liver, an enzyme that efficiently conjugates epoxides. In the other blood compartments, the interindividual differences were either less significant or were not detectable. Binding products with various macromolecules in blood, such as haemoglobin or lymphocyte DNA, are being discussed as biological monitors for occupational exposure to ethylene oxide. The observation that erythrocytes exhibit interindividual differences as described above make binding products with haemoglobin less suitable for biological monitoring of ethylene oxide exposure than, for example, DNA adducts in lymphocytes.

Effects of variation in detoxification rate on dose monitoring through adducts.

1. Föst et al. (Human & Experimental Toxicology 1991; 10: 25) have shown that ethylene oxide (EO) added to human blood gave rise to a higher level of adducts to haemoglobin (Hb) when the donors were deficient in an erythrocytic glutathione S-transferase (GST, later found to be GST-theta) than in blood from persons possessing this enzyme, and drew the conclusion that this polymorphism in detoxification rendered Hb adducts less suitable for biological monitoring. 2. By fitting a kinetic model to the data, the present study shows that the Hb adduct level gives a correct measure of the dose (concentration integrated over time) relevant to risk estimation. 3. It does illustrate, however, the importance of knowing an individual's detoxification efficiency, when Hb adduct measurements are used to assess environmental exposure, for example in occupational surveillance.

Ether oxygenate additives in gasoline reduce toxicity of exhausts.

UNLABELLED: Fuel additives can improve combustion and knock resistance of gasoline engines. Common additives in commercial fuels are "short-chain, oxygen containing hydrocarbons" such as methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE). Since these additives change the combustion characteristics, this may as well influence toxic effects of the resulting emissions. Therefore we compared toxicity and BTEX emissions of gasoline engine exhaust regarding addition of MTBE or ETBE. Non-reformulated gasoline served as basic fuel. This fuel was supplemented with 10%, 20%, 25% and 30% ETBE or 15% MTBE. The fuels were combusted in a gasoline engine at idling, part load and rated power. Condensates and particulate matter (PM) were collected and PM samples extracted with dichloromethane. Cytotoxic effects were investigated in murine fibroblasts (L929) using the neutral red uptake assay and mutagenicity using the bacterial reverse mutation assay. BTEX emissions were analyzed by gas chromatography. RESULTS: PM-extracts showed mutagenicity with and without metabolic activation. Mutagenicity was reduced by the addition of MTBE and ETBE, 10% ETBE being most effective. The condensates produced no significant mutagenic response. The cytotoxicity of the condensates from ETBE- and MTBE-reformulated fuels was reduced as well. The BTEX content in the exhaust was lowered by the addition of MTBE and ETBE. This effect was significantly related to the ETBE content at rated power and part load. CONCLUSIONS: Addition of MTBE and ETBE to fuels can improve combustion and leads to decreased toxicity and BTEX content of the exhaust. Reduction of mutagenicity in the PM-extracts is most probably caused by a lower content of polycyclic aromatic hydrocarbons.