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ln 2018 komt er een einde aan de aanwezigheid van TNO aan de Utrechtseweg 48 in Zeist. Duizenden TNO'ers (en bezoekers) zijn gedurende vele jaren het markante gebouw met de nog markantere trap binnengekomen en hebben gedurende die jaren daar hun beste krachten gegeven. Wanneer het gebouw kon spreken, dan zouden we wellicht versteld staan wat er zich binnen de muren allemaal heeft afgespeeld. Vreugde en verdriet, prachtig onderzoek, hartelijke collega's, vaak ruimte voor eigen initiatief, maar ook strakke werkvormen en dingen die we nooit geweten hebben en zullen weten. Het gebouw kan niet spreken en daarom is dit boekje samengesteld. Het bevat een keur aan artikelen, anekdotes en foto's die de geschiedenis doen herbeleven.

Multiblock or multiset methods are starting to be used in chemistry and biology to study complex data sets. In chemometrics, sequential multiblock methods are popular; that is, methods that calculate one component at a time and use deflation for finding the next component. In this paper a framework is provided for sequential multiblock methods, including hierarchical PCA (HPCA; two versions), consensus PCA (CPCA; two versions) and generalized PCA (GPCA). Properties of the methods are derived and characteristics of the methods are discussed. All this is illustrated with a real five-block example from chromatography. The only methods with clear optimization criteria are GPCA and one version of CPCA. Of these, GPCA is shown to give inferior results compared with CPCA. Copyright © 2003 John Wiley & Sons, Ltd.

Although there is much epidemiological evidence for an interaction between diet and colorectal cancer risk, the mechanisms by which diet might protect against colorectal cancer are still unclear. Here we report the significant up-regulation of carcinogen-induced apoptosis in the colon of rats fed a diet containing low-risk factors for colon cancer, namely low fat content, high calcium and high non-digestible carbohydrate. The dose-dependent induction of apoptosis in colonic crypts by the carcinogen 1,2-dimethylhydrazine (DMH) was significantly greater in rats receiving the low-risk compared with a high-risk (high fat, low calcium, low non-digestible carbohydrate) diet (P

The acceptable daily intake (ADI) for food additives is commonly derived from the NOAEL (no-observed-adverse-effect level) in long-term animal in vivo studies. To derive an ADI a safety or uncertainty factor (commonly 100) is applied to the NOAEL in the most sensitive test species. The 100-fold safety factor is considered to be the product of both species and inter-individual differences in toxicokinetics and toxicodynamics. Although in vitro data have previously been considered during the risk assessment of food additives, they have generally had no direct influence on the calculation of ADI values. In this review 18 food additives are evaluated for the availability of in vitro toxicity data which might be used for the derivation of a specific data-derived uncertainty factor. For the majority of the food additives reviewed, additional in vitro tests have been conducted which supplement and support the short- and long-term in vivo toxicity studies. However, it was recognized that these in vitro studies could not be used in isolation to derive an ADI; only when sufficient in vivo mechanistic data are available can such information be used in a regulatory context. Additional short-term studies are proposed for the food additives which, if conducted, would provide data that could then be used for the calculation of data-derived uncertainty factors. Copyright (C) 2000 Elsevier Science B.V.

In order to study the surface behaviour of puroindoline-a (PIN-a) in the presence of lipid monolayers, protein solutions were injected beneath films of the polar wheat lipid diacylgalactosylglycerol (MGDG). It was found that injection of PIN-a into the sub-phase caused a surface pressure increase of monolayers consisting of MGDG. When PIN-a was injected beneath an MGDG film at an initial surface pressure (π-initial) between 9 and 15 mN/m, a relatively fast increase in the surface pressure to 17 ± 2 mN/m was observed (the maximum surface pressure that could be reached by the protein alone). Then a much more gradual increase in π was observed. At πinitial values exceeding 35 mN/ m, injection of PIN-a resulted in a gradual increase in π to 49 ± 1 mN/m, which is equal to the collapse pressure of a pure MGDG monolayer. A gradual increase in the surface pressure was observed after injection of PIN-a beneath an MGDG monolayer with πinitial values between 15 and 35 mN/m, but the final value was lower than the collapse pressure of pure MGDG. Injection of peptide-a (a peptide comprising the tryptophan-rich domain of PIN-a) beneath MGDG monolayers also led to a considerable increase in surface pressure. The data are interpreted as insertion of PIN-a or peptide-a into the MGDG films. In contrast to this, lipid-transfer protein did not show this behaviour under the same conditions. The present data suggest that PIN-a may be present at the gas-cell surface in dough. However, although the elasticity of mixed PIN-a/MGDG films somewhat decreased owing to protein insertion, the resulting monolayer would still retard disproportionation. © 1998 Academic Press.

OBJECTIVES: To assess family resemblance in fat intake in a representative sample of Dutch families. DESIGN AND SUBJECTS: Households (n = 1077) with children between 1 and 30 y old were selected from the data set of the Dutch National Food Consumption Survey 1992. Two-day diet records were available for all household members. RESULTS: Pearson correlation coefficients for fat and fatty acid intakes (En%) ranged from r = 0.51 to r = 0.61 between parents, and from r = 0.52 to r = 0.72 between siblings. The mean associations in fat and fatty acid intake (En%) between mothers or fathers and children ranged from r = 0.37 to r = 0.50, and they were surprisingly similar for children from 1-3 y of age up to children above 21 y of age. Associations were consistently high for foods eaten at home, and weak for foods eaten outside of the home. Similar within-family associations were found in a set of 1052 households of the Dutch National Food Consumption Survey of 1987. Reported adherence to a therapeutic diet by one of the parents did not erase within-family intake correlations, suggesting that family resemblance is a dynamic phenomenon. CONCLUSION: Dutch parents and children living together resemble each other in short term intake of fats and fatty acids. SPONSORSHIP: This study was supported by the Ministry of Agriculture, Nature Management and Fisheries. DESCRIPTORS: Fat intake; dietary intake; social environment; family resemblance.

Pea lectin (PSL) is a secretory sugar-binding protein, readily soluble in aqueous solutions of low osmolarity. However, PSL also appears to be associated with the plasma membrane at the tip of young pea root hairs. By using the Wilhelmy plate method, we found that PSL can insert into a lipid monolayer. This property appeared to be independent of the sugar- binding ability of the protein. This result suggests that PSL may be directly involved in membrane-mediated interactions with saccharide ligands, for example during root hair infection by symbiotic rhizobia. Chemicals/CAS: Lectins; pea lectin; Phospholipids; Plant Lectins

Salt intake, cured meat consumption, refrigerator use and stomach cancer incidence: a prospective cohort study (Netherlands). van den Brandt PA, Botterweck AA, Goldbohm RA. Department of Epidemiology, Maastricht University, Maastricht, The Netherlands. pa.vandenbrandt@epid.unimaas.nl OBJECTIVE: Many case-control studies have reported that salt and cured meat intake are positively, and refrigerator use is inversely, associated with stomach cancer risk. In the current prospective study these associations were evaluated. METHODS: The Netherlands Cohort Study consisted of 120,852 men and women ages 55-69 years at baseline in 1986. Salt exposure was measured by calculating mean daily sodium intake (dietary salt) from 150 food items and by specific salt questions. After 6.3 years of follow-up, 282 incident stomach cancer cases were available for analyses. Case-cohort analyses were based on the 282 cases and 3123 subcohort members. RESULTS: In multivariate analyses adjusted for age, sex, smoking, education, stomach disorders, history of stomach cancer in the family, rate ratios (RR) for increasing quintiles of energy-adjusted intake of dietary salt were 1.00, 1.49, 1.03, 1.54 and 1.18, respectively (p trend = 0.43). An inverse association was found between stomach cancer and salt added at the hot meal (p trend = 0.04). For salt added to home-made soup, use of salt at the table, salt preference and duration of refrigerator use, no associations were observed. Positive associations were found for bacon (RR highest/lowest intake = 1.33; 95% CI = 1.03-1.71) and other sliced cold meat (RR highest/lowest intake = 1.29; 95% CI = 0.96-1.72), but not for smoked sausage, total cold meats, rashers/bacon, boiled ham and smoked beef/pork loin roll. Separate analyses among subjects with self-reported stomach disorders revealed higher RR of stomach cancer for dietary salt and several types of cured meat. CONCLUSION: The present findings suggest that intake of dietary salt and several types of cured meat were weakly positively associated with stomach cancer risk

Subclinical vitamin B-12 deficiency is common in the elderly. Encouraged by early indications, we investigated the plasma vitamin B-12 status in association with bone mineral content (BMC) and bone mineral density (BMD) in frail elderly people. Data of 194 free-living Dutch frail elderly (143 women and 51 men) were available. BMC and BMD were measured by dual energy X-ray analysis. Biochemical analyses were performed on plasma or serum including vitamin B-12, methylmalonic acid, homocysteine, 25-hydroxy vitamin D and parathyroid hormone. Women had higher plasma vitamin B-12 (288 and 238 pmol/L, respectively) and lower plasma homocysteine levels (15.8 and 21.3 μmol/L, respectively) than men. Of the total explained variance of BMC and BMD in women (46 and 22%, respectively), 1.3-3.1% was explained by plasma vitamin B-12, in addition to weight and height or energy intake. In men, the variance of BMC and BMD was explained by weight, smoking and/or height (total R2 was 53 and 25%, respectively), but not by plasma vitamin B-12. Osteoporosis occurred more often among women whose vitamin B-12 status was considered marginal or deficient than in women with a normal status, i.e., the prevalence odds ratios (after adjustment for weight, age and calcium intake) (95% confidence intervals) were 4.5 (0.8; 24.8) and 6.9 (1.2;39.4), respectively. These results suggest that vitamin B-12 status is associated with bone health in elderly women. Future studies on bone health should take into account a possible role of vitamin B-12 status in different populations. Chemicals/CAS: 25 hydroxyvitamin D, 64719-49-9; cyanocobalamin, 53570-76-6, 68-19-9, 8064-09-3; homocysteine, 454-28-4, 6027-13-0; methylmalonic acid, 516-05-2; parathyroid hormone, 12584-96-2, 68893-82-3, 9002-64-6; 25-hydroxyvitamin D, 64719-49-9; Calcium, Dietary; Homocysteine, 454-28-4; Methylmalonic Acid, 516-05-2; Parathyroid Hormone; Vitamin B 12, 68-19-9; Vitamin D, 1406-16-2

The effects of excessive non-toxic dietary Vitamin D3 supplementation on Ca homeostasis with specific effects on endochondral ossification and skeletal remodeling were investigated in a group of growing Great Dane dogs supplemented with cholecalciferol (Vitamin D3; HVitD) versus a control group (CVitD) (1350 μg versus 11.4 μg Vitamin D3 per kilogram diet) from 6 to 21 weeks of age. There were no differences between groups in plasma concentrations of total Ca, inorganic phosphate, growth hormone, and insulin-like growth factor I and no signs of Vitamin D3 intoxication in HVitD. For the duration of the study in HVitD compared to CVitD, plasma levels of parathyroid hormone (PTH) decreased, calcitonin (CT) increased, 25-hydroxycholecalciferol [25(OH)D3] increased 30- to 75-fold, 24,25-dihydroxycholecalciferol [24,25(OH)2D3] increased 12- to 16-fold, and 1,25-dihydroxycholecalciferol [1,25(OH)2D3] decreased by approximately 40%. The latter was attributed to the two-fold increased metabolic clearance rate in the HVitD versus CVitD accompanied by the absence of the anabolic effect of PTH on the production of 1,25(OH)2D3. Fractional Ca absorption (α) did not differ between groups at 8 and 14 weeks of age, whereas at 20 weeks of age α increased by only 16.4% in HViAtD compared to CVitD. Excessive non-toxic Vitamin D3 supplementation resulted in decreased bone remodeling and focal enlargement of the growth plate with morphology resembling those induced by administration of CT. Hypercalcitoninemia and the imbalanced relationship between 1,25(OH)2D3 and 24,25(OH)2D3 are potent candidates for the disturbed endochondral ossification. © 2003 Elsevier Science Inc. All rights reserved.

Many organisms have the ability to form spores, a remarkable phase in their life cycles. Compared with vegetative cells, spores have several advantages (e.g. resistance to toxic compounds, temperature, desiccation and radiation) making them well suited to various applications. The applications of spores that first spring to mind are bio-warfare and the related, but more positive, field of biological control. Although they are often considered metabolically inert, spores can also be used as biocatalysts. Other uses for spores are found in the fields of probiotics, tumour detection and treatment, biosensing and in the 'war against drugs'.

Background: Flow mediated dilatation (FMD) of the brachial artery and soluble intercellular adhesion molecule 1 (sICAM-1) are measures of distinct functions of the endothelium, reflecting nitric oxide (NO)-mediated and pro-inflammatory status, respectively. The comparative value of the two measures in relation to cardiovascular risk is unknown. Objective: To study and quantify the relation between these two measures, and their relative value in relation to the risk of coronary heart disease as estimated by the Framingham risk function. Methods: We performed a single centre population-based study of 85 men and 81 women, aged 18-73 years. Endothelial function was assessed biochemically by sICAM-1 and functionally by FMD. In addition traditional cardiovascular risk factors, CRP, leukocyte count, homocysteine and fibrinogen were determined. Analyses were performed with multivariate linear regression, adjusted for age, gender, and CRP. Results: Median sICAM-1 levels were 217.0 μg/l (interquartile range: 174.0-348.5). Mean FMD was 4.5% (S.D.: 3.9). The regression coefficient for the association between sICAM-1 and FMD was -3.3 μg/l (95% CI: -6.0;-0.6) per percentage rise in FMD, after adjustment for age, gender, smoking, oral contraceptives (OC) use, classical risk factors and CRP. After adjustment for CRP and sICAM-1, the estimated risk of coronary heart disease in the next 10 years varied from 1.55% (95%CI: 0.89; 2.70) in the highest quintile of FMD to 3.92% (95% CI: 2.23; 6.92) in the lowest quintile. For sICAM-1, estimated risk, adjusted for FMD and CRP varied from 1.50% (95%CI: 0.85; 2.64) in the lowest quintile of sICAM-1 to 4.15% (95%CI: 2.35; 7.34) in the highest quintile. P-values for trends were 0.02 and 0.01 for quintiles of FMD and quintiles of sICAM-1, respectively. Conclusion: These findings indicate that sICAM-1 and FMD are related in healthy individuals, independently of cardiovascular risk factors and CRP, and that they are both related to the estimated risk of coronary heart disease, independently of each other. © 2003 Elsevier Ireland Ltd. All rights reserved.

The current knowledge on biological protein acetylation is confined to acetyl CoA-dependent acetylation of protein catalyzed by specific acetyl transferases and the non-enzymatic acetylation of protein by acetylated xenobiotics such as aspirin. We have discovered a membrane-bound enzyme catalyzing the transfer of acetyl groups from the acetyl donor 7,8-diacetoxy-4-methyl coumarin (DAMC) to glutathione S-transferase 3-3 (GST3-3), termed DAMC:protein transacetylase (TAase). The purified enzyme was incubated with recombinant GST3-3 subunit and DAMC, the modified protein was isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in gel digested with trypsin and the tryptic digest was analyzed by mass spectrometry. The N-terminus and six lysines, Lys-51, -82, -124, -181, -191 and -210, were found to be acetylated. The acetylation of GST3-3 described above was not observed in the absence of either DAMC or TAase. These results clearly establish the phenomenon of protein acetylation independent of acetyl CoA catalyzed by a hitherto unknown enzyme (TAase) utilizing a certain xenobiotic acetate (DAMC) as the active acetyl donor. © 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved. Chemicals/CAS: 7,8-diacetoxy-4-methylcoumarin; Acetyl Coenzyme A, 72-89-9; Acetylesterase, EC 3.1.1.6; Coumarins; Glutathione Transferase, EC 2.5.1.18; Recombinant Proteins

Background: A high plasma total homocysteine concentration is associated with increased risk of cardiovascular disease. Consumption of unfiltered or filtered coffee raises total homocysteine concentrations in healthy volunteers. The responsible compound, however, is unknown. Objective: The objective was to determine whether caffeine explains the homocysteine-raising effect of coffee. Design: Forty-eight subjects aged 19-65 y completed this randomized crossover study with 3 treatments, each lasting 2 wk. Subjects consumed 6 capsules providing 870 mg caffeine/d (test treatment), 0.9 L paper-filtered coffee providing ≈870 mg caffeine/d, or 6 placebo capsules. Blood samples were drawn fasting and 4 h after consumption of 0.45 L coffee or 3 capsules. Results: The mean fasting plasma homocysteine concentration after the placebo treatment was 9.6 ± 3.1 μmol/L. The caffeine and coffee treatments increased fasting homocysteine by 0.4 μmol/L (95% CI: 0.1, 0.7; P = 0.04), or 5%, and by 0.9 μmol/L (95% CI: 0.6, 1.2; P = 0.0001), or 11%, respectively, compared with placebo. The increase in homocysteine concentrations 4 h after consumption of 0.45 L coffee relative to consumption of 3 placebo capsules was 19% (P = 0.0001). Caffeine treatment had a much weaker acute effect on homocysteine (4%; P = 0.09). Effects of caffeine were stronger in women than in men, but the effects of coffee did not differ significantly between men and women. Conclusions: Caffeine is partly responsible for the homocysteineraising effect of coffee. Coffee, but not caffeine, affects homocysteine metabolism within hours after intake, although the effect is still substantial after an overnight fast. Chemicals/CAS: Caffeine, 58-08-2; Homocysteine, 454-28-4; Placebos; Vitamin B 12, 68-19-9; Vitamin B 6, 8059-24-3

Over the past few years the presence of p53-like proteins in plants was frequently reported, by using the monoclonal antibody Pab240. By means of protein purification and screening a cDNA library, a Pab240 cross-reacting protein and a cDNA clone were isolated from barley. Peptide- and DNA-sequence analysis identified one and the same protein: 2-oxoglutarate dehydrogenase. Sequence analysis of 2-oxoglutarate dehydrogenase revealed that the protein contains a perfect Pab240 epitope. In barley, the 110 kDa oxoglutarate dehydrogenase was degraded during isolation to a 53 kDa Pab240 cross-reacting polypeptide, thereby mimicking curiously p53-like properties. © 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved. Chemicals/CAS: Ketoglutarate Dehydrogenase Complex, EC 1.2.4.2; Plant Proteins; Tumor Suppressor Protein p53

Chemicals/CAS: Biological Products; Ethylmercury Compounds; Food Additives; Pharmaceutical Preparations; Preservatives, Pharmaceutical; Thimerosal, 54-64-8

A new in-house designed and constructed injection valve for capillary electrochromatography (CEC) based on a rotating injection part with compartments for the eluent as well as for the sample has been coupled to a mass spectrometer via a sheath flow electrospray ionisation (ESI) interface, using short capillary columns of 15 cm length. The CEC columns were packed with 3 μm C18 bonded silica particles, and a mixture of peptides was analysed using an ammonium acetate/acetonitrile eluent. A significant increase in the signal-to-noise ratio was obtained when the peptides were dissolved in water with the same content of organic modifier as in the eluent with an addition of 0.5% (v/v) acetic acid. When the CEC analysis was performed without any additional pressure, the separation current sometimes dropped tremendously due to bubble formation, caused by different permeability in the frits and packed part of the column causing an extremely low electroosmotic flow. The separation current was restored to its original value by applying only 7 bar at the inlet of the CEC column, and the separation performance for the test peptides was recovered. A comparison of the CEC performance of peptides in pure CEC mode and in low-pressure CEC mode is reported. Copyright © 2001 John Wiley & Sons, Ltd.

Over the past decades the description of quantitative structure-activity relationships (QSARs) has been undertaken in order to find predictive models and/or mechanistic explanations for chemical as well as biological activities. This includes QSAR studies in toxicology. In an approach beyond the classical QSAR approaches, attempts have been made to define parameters for the QSAR studies on the basis of quantum mechanical computer calculations. The conversion of relatively small xenobiotics within the active sites of biotransformation enzymes can be expected to follow the general rules of chemistry. This makes the description of QSARs on the basis of only one parameter, chosen on the basis of insight in the mechanism, feasible. In contrast, toxicological endpoints can very often be the result of more than one physico-chemical interaction of the compound with the model system of interest. Therefore the description of quantitative structure-toxicity relationships often does not follow a one-descriptor mechanistic approach but starts from the other end, describing QSARs by multi-parameter approaches. The present paper focuses on the possibilities and restrictions of using computer-based QSAR modeling for analyzing experimental toxicological data, with emphasis on examples from the field of biotransformation and toxicity. © 2001 Elsevier Science Ltd. All rights reserved. Chemicals/CAS: Hazardous Substances

A physiologically-based pharmacokinetic (PB-PK) model was developed for ethylene dibromide (1,2-dibromoethane, EDB) for rats and humans, partly based on previously published in vitro data (Ploemen et al., 1997). In the present study, this PB-PK model has been validated for the rat. In addition, new data were used for the human class ΘGST T1-1. Validation experiments are described in order to test the predictive value of kinetics to describe 'whole-body' metabolism. For the validation experiments, groups of cannulated rats were dosed orally or intravenously with different doses of EDB. Obtained blood concentration-time curves of EDB for all dosing groups were compared to model predictions. It appeared that metabolism, which previously was assumed to be restricted to the liver, was underestimated. Therefore, we extended the PB-PK model to include all the extrahepatic organs, in which the enzymes involved in EDB metabolism have been detected and quantified. With this extended model, the blood concentrations were much more accurately described compared to the predictions of the 'liver-model'. Therefore, extrahepatic metabolism was also included in the human model. The present study illustrates the potential application of in vitro metabolic parameters in risk assessment, as well as the use of PB-PK modelling as a tool to understand and predict in vivo data.

The maintenance of the major hepatic cytochrome P450 (CYP) enzymes has been studied in precision-cut human liver slices cultured for up to 72 h in supplemented RPMI 1640 medium. The relative apoprotein levels of 11 CYP enzymes were determined using a panel of antipeptide antibodes. In addition, 7-ethoxyresorufin O-deethylase, tolbutamide methylhydroxylase, debrisoquine 4-hydroxylase, and testosterone 6β-hydroxylase activities were determined as enzymatic markers for CYP1A2, CYP2C9, CYP2D6, and CYP3A4, respectively. There was a large variation in the rate of decline of different CYP levels with time in culture. Based on the rate of decrease, CYP enzymes could be separated into two groups, with CYP2C9, CYP2D6, CYP3A4, and CYP4A11 being relatively stable (half-lives between 70 and 104 h), compared with CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, and CYP3A5, which were relatively unstable (half-lives between 23 and 36 h). Enzyme activities decreased at rates similar to those of their corresponding apoproteins. There was also a large difference in the stability of individual CYP enzymes from different liver donors, particularly for the most rapidly declining CYP enzymes. Similar losses of CYP enzymes were found when human river slices were cultured in supplemented Williams' medium E for 72 h, except that CYP2E1 apoprotein levels were better maintained. Because of the variable decreases of CYP enzymes, xenobiotic metabolism studies are best performed with freshly cut rather than cultured human liver slices. Chemicals/CAS: Culture Media; Cytochrome P-450 Enzyme System, 9035-51-2; Isoenzymes

Moderate alcohol consumption is associated with a reduced risk of coronary heart disease. Earlier studies in men have shown that moderate alcohol consumption affects lipoprotein metabolism and hemostasis. In this diet-controlled, randomized, crossover trial, we investigated the effect on lipoprotein metabolism of moderate consumption of red wine or red grape juice with evening dinner for 3 weeks in premenopausal women using oral contraceptives and in postmenopausal women. After 3 weeks, blood samples were collected 1 hour before dinner up to 19 hours after starting dinner at 2-hour or 4-hour intervals. Plasma triglyceride concentrations and very low density lipoprotein (VLDL) triglyceride levels peaked 3 hours after dinner with wine in both premenopausal and postmenopausal women. After wine consumption, the overall high-density lipoprotein (HDL) cholesterol level was increased in postmenopausal women (mean increase 0.17 mmol/L, or 12%, p = 0.03), and the plasma low-density lipoprotein (LDL) cholesterol level was reduced in premenopausal women (mean reduction 0.35 mmol/L, or 12%, p = 0.01) as compared with grape juice consumption. The findings suggest that postprandial lipoprotein metabolism after moderate alcohol consumption differs between oral contraceptive-using premenopausal women and postmenopausal women. The response of postmenopausal women to alcohol resembled the response found in earlier studies in men.

Objective: The purpose was to study the association between vegetable and fruit consumption and lung cancer incidence using 1074 cases after 6.3 years of follow-up in the Netherlands Cohort Study. Methods: Dietary intake was assessed using a 150-item food-frequency questionnaire. Multivariate models were used including age, sex, family history of lung cancer, highest educational level attained, and smoking history. Results: Statistically significant inverse associations were found with total vegetables and most vegetable groups. Rate ratios (RRs) based on consumption frequency showed the strongest effect of vegetables from the Brassica group (RR 0.5, 95% confidence interval (95% CI) 0.3-0.9, for consumption greater than or equal to 3 times per week versus less than or equal to once a month). RR of highest versus lowest quintile of total vegetable consumption was 0.7 (95% CI 0.5-1.0, p-trend 0.001). Statistically significant inverse associations were found for all fruits listed in the questionnaire. RRs for quintiles of total fruit intake were 1.0, 0.7, 0.6, 0.6 and 0.8 respectively (p-trend

Abstract In isolated embryos from dormant barley grains, synergistic effects of fusicoccin (FC) and gibberellic acid (GA3) were observed on the induction of α-amylase mRNA expression. However, no α-amylase mRNA expression could be induced by both agents in embryos from non-dormant grains. Both light- and electron-microscopy studies demonstrated that there were large numbers of starch granules present in mature embryos (mainly in scutellum) from dormant barley grains but none or almost none in embryos from non-dormant grains. Furthermore, the content of reducing sugars in embryos from dormant grains was about half of that from non-dormant grains. In contrast to GA3, FC was able to induce a strong acidification of extracellular pH (pHe). Clamping the pHeto prevent FC-induced acidification, by using 50 mM MES buffer (pH 5.6), caused an inhibition of GA3- or FC-induced α-amylase mRNA expression but did not affect the germination of embryos from dormant grains. In addition, in MES buffer, addition of FC or a combination of FC and GA3increased the germination rate of embryos isolated from dormant grains, though large numbers of starch granules were still present in these embryos. Based on these observations, the presence of starch granules and a low reducing sugar level in embryos from dormant grains is not a factor for control of grain dormancy and germination.

Primary structures of the N-glycans of two major pollen allergens (Lol p 11 and Ole e 1) and a major peanut allergen (Ara h 1) were determined. Ole e 1 and Ara h 1 carried high mannose and complex N-glycans, whereas Lol p 11 carried only the complex. The complex structures all had a beta(1,2)-xylose linked to the core mannose. Substitution of the proximal N-acetylglucosamine with an alpha(1, 3)-fucose was observed on Lol p 11 and a minor fraction of Ole e 1 but not on Ara h 1. To elucidate the structural basis for IgE recognition of plant N-glycans, radioallergosorbent test analysis with protease digests of the three allergens and a panel of glycoproteins with known N-glycan structures was performed. It was demonstrated that both alpha(1,3)-fucose and beta(1,2)-xylose are involved in IgE binding. Surprisingly, xylose-specific IgE antibodies that bound to Lol p 11 and bromelain did not recognize closely related xylose-containing structures on horseradish peroxidase, phytohemeagglutinin, Ole e 1, and Ara h 1. On Lol p 11 and bromelain, the core beta-mannose is substituted with just an alpha(1,6)-mannose. On the other xylose-containing N-glycans, an additional alpha(1,3)-mannose is present. These observations indicate that IgE binding to xylose is sterically hampered by the presence of an alpha(1,3)-antenna.

In order to manufacture complete and balanced dog diets, it is important to know the nutrient requirements of dogs and the availability of these nutrients from food. As pet food manufacturers are restricted in their options for (invasive) animal studies, due to ethical constraints, it is important to have alternative methods for researching the effects of various dog diets. To simulate the gastrointestinal tract of the dog, the dynamic gastrointestinal tract model developed by Minekus et al. was further developed and modified in this study. The model consists of four compartments which simulate the stomach and small intestine (duodenum, jejunum and ileum). Each compartment is made of glass, with a flexible inner wall. This wall can be compressed by increasing the pressure of the surrounding water, mimicking the peristaltic movements and mixing seen in vivo. The model is computer- controlled to simulate physiological parameters such as pH, transit time and secretion of digestive juices, as derived from the literature. Gastric meal delivery and the effects of intestinal transit time on protein digestibility and availability for absorption of calcium from dog food were studied to evaluate the model. The gastric meal delivery of dry dog food was identical to a preset curve, which was based on in vivo data from healthy dogs. The emptying time for canned dog food was somewhat slower than the preset values, probably due to the viscosity of the meal. The differences between the preset values and the measured delivery were not significant. The digestibility of protein and the availability of calcium for absorption increased with a longer transit time A significant difference was found between medium and slow transit times for the nitrogen content in the ileal delivery effluent and the jejunal dialysates (p < 0.05). The same trend was seen for calcium (not significant). The overall conclusion is that the model is a useful tool for mimicking the gastrointestinal tract of dogs. Parameters such as pH, transit time and enzyme activity can be mimicked and can be kept within a physiological range.

To evaluate risk from dermal exposure, the amount of material on the skin must first be measured. The potential for dermal uptake must then be assessed for the potential health effects from systemic exposure. No standard methods exist for studying these processes, and published data are not comparable because of the different techniques used. Future validated methodology should provide a sound scientific basis for risk assessment. Methods for measuring skin and surface contamination will require development of reference contaminated surfaces and skin as part of quality control procedures. Biological monitoring is a valuable tool in the assessment of dermal absorption, in contributing to the validation of in vitro techniques, and in risk assessment and management. It will be necessary to conduct detailed investigations to support risk assessment for dermal exposure. Ultimately, predictive models will be established for exposure and for dermal absorption to support a generic approach and allow risk assessment strategies appropriate to actual workplace situations. This work is licensed under a Creative Commons Attribution 4.0 International License.

The TEAC (Trolox equivalent antioxidant capacity) assay is based on scavenging of 2,2'-azinobis-(3- ethylbenzothiazoline-6-sulfonate) radical anions (ABTS(.-)). In this report we describe a modification based on pre-generation of the ABTS radical anions with a thermolabile azo compound, 2,2'-azobis- (2-amidinopropane)HCl (ABAP). This modification makes the assay less susceptible to artefacts, e.g. influence on the radical generation process. For most antioxidants tested, a biphasic reaction pattern was seen, i.e. a fast and slow scavenging rate. We evaluated application of the assay with both lipophilic and hydrophilic compounds with antioxidant capacity. Several organic solvents, compatible with water, were tested with α-tocopherol, quercetin and β-carotene. It was found that the TEACs differed in various solvents. Under standardized conditions additivity of TEACs obtained from individual antioxidants could be demonstrated. This might enable application of the assay for the identification of 'unknown' antioxidants. Copyright (C) 1999 Elsevier Science Ltd. Chemicals/CAS: 2,2' azobis(2 amidinopropane), 13217-66-8; alpha tocopherol, 1406-18-4, 1406-70-8, 52225-20-4, 58-95-7, 59-02-9; ascorbic acid, 134-03-2, 15421-15-5, 50-81-7; aurantiin, 10236-47-2, 12619-61-3, 29658-83-1, 82350-96-7; beta carotene, 7235-40-7; cryptoxanthin, 472-70-8; dehydroascorbic acid, 33124-69-5, 490-83-5; hesperidin, 520-26-3; lycopene, 502-65-8; quercetin, 117-39-5; trolox C, 56305-04-5; zeaxanthin, 144-68-3

Department of Epidemiology, Maastricht University, The Netherlands. OBJECTIVES: In The Netherlands, part of the population experienced food restriction and severe famine during World War II. The purpose of this study was to study the effects of severe undernutrition during adolescence on the risk of breast cancer later in life. METHODS: We examined the hypothesis in the Netherlands Cohort Study on diet and cancer (NLCS), among 62,573 women aged 55-69 years. Baseline information on diet and other risk factors was collected with a questionnaire in 1986. Information was collected on residence in the Hunger winter (1944-1945) and War years (1940-1944) and fathers' employment status in 1932-1940 as indicators of exposure. After 6.3 years of follow-up, 1009 incident breast cases were available for analysis. RESULTS: In multivariate case-cohort analysis, residents of the western part of the country in 1944-1945 had an increased breast cancer risk (western city RR = 1.1, 95% CI: 0.9-1.4, western rural area RR = 1.5, 95% CI: 1.1-1.9). For the War years (1940-1944) we found no association between breast cancer risk and urban vs. rural residence. Women whose fathers were unemployed during the Depression years (1932-1940) had a non-significant decrease in breast cancer risk (RR = 0.9, 95% CI: 0.7-1.2). Exposure to energy restriction during the adolescent growth spurt or during the period between menarche and birth of the first child did not change the RRs substantially. CONCLUSIONS: We found no clear evidence in this study for the hypothesis that energy restriction in adolescence leads to a decreased breast cancer risk.

The theoretical mathematical models described in this paper are used to evaluate the effects of fungal biomass inactivation kinetics on a non- isothermal tray solid-state fermentation (SSF). The inactivation kinetics, derived from previously reported experiments done under isothermal conditions and using glucosamine content to represent the amount of biomass, are described in different ways leading to four models. The model predictions show only significant effects of inactivation kinetics on temperature and biomass patterns in the tray SSF after long fermentation periods. The models in which inactivation is triggered by low specific growth rates can predict restricted biomass evolution in combination with a fast temperature increase followed by a slower temperature decrease. Such inactivation might occur when substrate is limiting or products are formed in toxic concentrations. Temperature is predicted to be the key parameter. Oxygen concentration is predicted to become limiting only at high heat conduction and low oxygen diffusion rates. Desiccation of the substrate is predicted not to occur.

A biochemical dosimeter was developed to study the attenuation of biologically effective UV radiation in marine tropical waters. Small quartz vials were used containing a solution of DNA molecules; the vials were incubated at discrete water depths. Subsequently, DNA damage was determined in these samples, using an antibody directed against thymine dimers followed by chemiluminescent detection. Measurements of DNA damage were compared with calculated biologically effective doses, as derived from spectroradiometer measurements. The bio-dosimeter was found to be a reliable and easy tool to determine levels of harmful UV radiation in marine waters. The highest attenuation coefficient (1.60 m(-1)) measured with the biochemical dosimeter was found in eutrophic waters, at a coastal station off Curabcao, Netherlands Antilles. At the other stations attenuation coefficients ranged from 0.18 m(-1) in central Atlantic waters to 0.43 m(-1) close to the Curabcao coast line. Latter results indicate that biologically effective UV radiation may easily reach ecologically significant depths, e.g. coral reef communities.

Capillary zone electrophoresis (CZE) was coupled to mass spectrometry (MS) via a nanoelectrospray interface (nESI), using conductively coated tips (8 μm orifice) butted to the end of a fused-silica capillary. The CZE/nESI-MS system was carefully optimised to achieve a stable operation of the arrangement in order to run also MS/MS experiments. Mixtures of β-agonists were successfully separated using 5 mmol/L ammonium acetate in 80% MeOH as a buffer. The limit of detection was 500 attomole of a substance injected. The system was also investigated from the point of view of quantification of the substances. Careful measures were taken to avoid any systematic errors (evaporative loss during the electrokinetic injection and reduction of migration times due to the electrospray pull during the CE run). The data show that the response of a mass spectrometric detector in the low-femtomole range not only depends on the concentration of the analyte but also on the properties of the nanoelectrospray process itself, that is why the linearity of the response can be compromised.

Background: Response to cisplatin-therapy is assumed to be related to the formation of platinum (Pt)-DNA adducts. Measurement of these adducts prior to therapy could be of value to improve cisplatin based cancer therapy. Materials and methods: We determined Pt-GG and Pt-AG adduct levels by use of 32P-postlabeling after ex vivo cisplatin treatment of fragments of head and neck squamous cell carcinoma (HNSCC) xenografts (five lines), and of tumor biopsies from patients with HNSCC (n = 8) and testicular cancer (n = 8). Results: Adduct levels in fragments (3 x 3 x 3 mm) exposed to 10 to 80 μM cisplatin for one hour, showed positive correlations with the in vivo response to cisplatin treatment (P < 0.05), as well as with the xenograft adduct levels observed after in vivo cisplatin treatment (P < 0.02). After an additional five-hour drug-free incubation period the correlations were absent. When patient tumor fragments were exposed ex vivo to 80 μM cisplatin for one hour, adduct levels were similar in HNSCC and testicular cancer. Persistence of adducts was observed for testicular cancer in the additional drug-free period. The adduct levels in the samples of two HNSCC patients who received cisplatin chemotherapy were in line with the hypothesis that higher adduct levels are associated with a better response. Conclusion: Our preliminary results show that analysis of DNA adducts following ex vivo drug treatment is a feasible approach towards a predictive assay, which warrants further investigation.

Large deformation rheological properties of short doughs of various composition prepared under various mixing times were determined in uniaxial compression. Sucrose-syrup doughs exhibited prominent yielding and flow behaviour. Their apparent biaxial extensional viscosity decreased with increasing sucrose content. The stress-strain curves for the sugar-free doughs indicated a stronger elastic contribution to deformation than did those for the sucrose-syrup doughs. The deformability of the former doughs increased with increasing water content. Regardless of dough type, mixing time had a pronounced effect on dough consistency. In addition, it drastically changed the shape of the stress-strain curve for a sugar-free dough. These results are discussed in terms of the structure of short doughs. It is concluded that sucrose delays, if not inhibits, gluten development and promotes formation of a non-fat continuous phase, whereas mixing promotes formation of a continuous fat phase. © 1999 Academic Press.

The aim of the present study was to investigate the effects of intravenously administered sulfadoxine (5 mg kg-1 bodyweight) or sulfaphenazole (5 mg kg-1 bodyweight) on the in vivo elimination of i.v. tolbutamide (5 mg kg-1 bodyweight), as both compounds were shown to inhibit tolbutamide hydroxylation in vitro. It was shown that relative large differences in tolbutamide clearance exist among goats (n = 6). A high correlation was seen between tolbutamide and sulfadoxine clearances. Tolbutamide clearance was significantly reduced by concommitant administration of sulfaphenazole. Sulfadoxine (SDX) had a less consistent effect. Mean tolbutamide plasma clearance was not significantly affected due to the fact that three animals showed an inhibition, whereas three others apparently did not respond. A negative correlation was found between the amount of N4-acetyl SDX in urine and the SDX clearance. Approximately 93 per cent of tolbutamide was bound to plasma proteins. However, there was no evidence for displacement of tolbutamide from its protein binding sites by sulfaphenazole or sulfadoxine. The results described in the present study confirm previous in vitro data obtained with goat hepatocytes. Although quantitative differences in inhibition exist between in vivo and in vitro results, hepatocytes are a good model to study potential drug-drug interactions at the level of biotransformation processes.

1. An earlier study by our group revealed that the viscosity of faeces from patients with Crohn's disease is significantly lower than that of healthy subjects. This is due to low concentrations of a high-molecular-mass carbohydrate, probably of bacterial origin. The cause of this phenomenon might be the impaired barrier function of the gut mucosa. Low viscosity may allow close contact of intestinal contents (bacterial products and toxins) with the intestinal wall. This could play a role in the maintenance of the disease. 2. The first aim of this study was to investigate the high-molecular-mass carbohydrate fraction, responsible for viscosity, in detail. We also tried (in a pilot study) to raise the intestinal viscosity of patients with Crohn's disease with the undegradable food additive hydroxypropylcellulose (E463), in an attempt to alleviate clinical symptoms. 3. The high-molecular-mass fraction (> 300 kDa) responsible for faecal viscosity was sensitive to lysozyme and contained high levels of muramic acid. It was concluded that this material consisted mainly of peptidoglycan polysaccharides and was consequently of bacterial origin. The muramic acid in material from patients with Crohn's disease was 7.5 (1.5-13.9)%, which was less than in healthy subjects [11.4 (8.5-24.1)%; P = 0.0004]. Furthermore, viscosity in material from patients with Crohn's disease was found to be half [14.9 (1.0-33.6) cP] of that found in healthy subjects [35.0 (2.7-90.7) cP; P = 0.004]. 4. A daily dose of 1 g of hydroxypropylcellulose caused an increase in faecal viscosity in patients with Crohn's disease (from 1.4 to 2.3 cP) and in healthy subjects (from 4.9 to 7.5 cP). Faecal consistency improved in patients with Crohn's disease (from watery and loose to formed) and the defecation frequency decreased from 3-4 to about 2 times a day. No changes in defecation patterns were found in healthy subjects. 5. These data indicate that the high-molecular-mass fraction that is responsible for faecal viscosity is peptidoglycan. Furthermore, a daily dose of a hydroxypropylcellulose solution to increase the viscosity of the intestinal contents of patients with Crohn's disease might be beneficial. This approach merits further study.

In the Netherlands, the nationwide Fat Watch campaign aiming at a reduction in fat consumption was organized from 1991 onwards. This study describes the effects of the first three consecutive campaign years on attention to fat, diet and health, attitudes, self-efficacy expectations and intentions related to dietary fat reduction, and self-rated fat intake. Data were collected each year according to the Solomon design, by telephone interviews among about 1200 consumers responsible for household purchases. Campaign awareness was high in each campaign year, but a decrease in campaign awareness was found after the first campaign in 1991. The 1991 campaign was primarily aimed at getting the attention of the Dutch public for the fat-reduction message and indeed resulted in increased attention. The second campaign year resulted in small but statistically significant positive changes in attitudes, which was the specific target of the 1992 campaign. Intention to buy low-fat food products was also significantly increased. The 1993 campaign failed to realize the targeted increases in self-efficacy among the study population, but a significant campaign effect on intentions was found. The evaluation of all three campaigns indicated that the Dutch underestimate their personal fat intake and this has been identified as an important barrier to a further reduction in fat consumption. Making subjects aware of their personal fat consumption will be given priority in future campaigns. Chemicals/CAS: Dietary Fats

The endogenous ABA contents of dormant and nondormant barley grains were determined following application of different compounds to break dormancy. The chemicals used for breaking of dormancy in intact dormant grains were weak and strong acids, alcohols, hydrogen peroxide, cyanide, nitrate, salicylic acid, gibberellic acid and fusicoccin. The dormancy-breaking compounds could be classified into two major groups: compounds that caused a decrease in endogenous ABA (class I) and compounds which did not affect endogenous ABA (class II). Class I compounds included gibberellic acid, ethanol, hydrogen peroxide, nitrate, salicylic acid; class II compounds were fusicoccin, acid (H2SO4), sodium azide, n-caproic acid. In addition, these dormancy-breaking compounds were able to stimulate the germination rate when applied to embryos isolated from dormant grains. The concentrations necessary for stimulation of germination of isolated embryos were much lower than the concentrations for breaking the dormancy of intact grains. After embryos were isolated from dormant grains and incubated in water, ABA was determined in both embryos and in the incubation media. The class I compounds stated above also reduced ABA content in the incubation medium of isolated embryos, while class II compounds had no effect on ABA content of the medium. External application of ABA could overcome the effect of dormancy-breaking compounds of class I but not of class II. The results suggest that in the presence of the agents belonging to class II, ABA responsiveness of isolated embryos from dormant grains is decreased, compared to nontreated embryos.

As part of a health-hazard survey on the health risk of hospital cleaning workers from exposure to Lyorthol, a hazard assessment of o-phenylphenol (and its sodium salt), one of the constituents of Lyorthol, has been prepared, In this paper, the physical and chemical characteristics, kinetics and effects of o-phenylphenol and its sodium salt are described and discussed, and an overall, summarizing hazard evaluation is presented. Chemicals/CAS: 2-phenylphenol, 90-43-7; Biphenyl Compounds; Disinfectants

The present study was aimed to assess the psychological status of young healthy women after the administration of a triphasic contraceptive steroid preparation for six complete menstrual cycles. Subjects had never used oral contraceptives (OC) and had neither a familial history of depression nor psychological disturbances. OC-induced psychological disturbances were interpreted for years as evidence of pyridoxine (vitamin B6) deficiency. Other nutritional deficiencies, namely in cobalamin, folate and iron, can disturb the functioning of the central nervous system. In addition, a deficiency of any of these nutrients can lead to several anemia-induced symptoms that are highly susceptible to influence the psychological status. For ample evidence, nutritional status was then evaluated in parallel to psychological testing. Blood iron and vitamin levels of interest were found to be adequate and could not have biaised the response to a psychological test (MMPI). This study showed that a 6-month Triphasil® treatment did not modify significantly the psychological status of subjects. To our knowledge, this is the first psychological study on young never OC-users taking an identical triphasic contraceptive steroid preparation to investigate early psychological side-effects due to OC, at a similar time of the menstrual cycle, when nutritional status was also evaluated. Chemicals/CAS: Contraceptives, Oral; Ethinyl Estradiol-Norgestrel Combination, 8056-51-7; Ferritins, 9007-73-2; Pyridoxine, 65-23-6

The synthesis of a new acridinium sulphonylamide label for the liquid chromatographic determination of carboxylic acids is described. The label 10-methyl-N-(p-tolyl)-N-(p-iodoacetamidobenzenesulphonyl)-9-acridinium carboxamide iodide is synthesized from 9-acridinecarboxylic acid by a seven-step reaction. Ibuprofen, used as test compound, is coupled to the reactive iodoacetamide group of the label by means of an alkylation reaction in dry acetonitrile for 20 min at 50°C in the presence of 18-crown-6 and potassium carbonate as base catalyst. The reaction mixture is injected into a liquid chromatographic system with chemiluminescence detection. Separation is performed on a Zorbax C18 column with acetonitrile-water-tetrahydrofuran (39:57:4, v/v/v) containing 10 mmol/L TBABr and 0.035% H2O2 as the mobile phase at a flow rate of 1.0 ml/min. Chemiluminescence detection is achieved by the postcolumn addition of 200 mmol/L potassium hydroxide dissolved in methanol-water (1:1, v/v) at a flow rate of 20 μL/min. The detection limit (S/N = 3) of derivatized ibuprofen is 60 pg (3 pg injected). © 1998 John Wiley & Sons, Ltd. Chemicals/CAS: 10-methyl-N-(p-tolyl)-N-(p-iodoacetamidobenzenesulfonyl)-9-acridinium carboxamide; Acridines; Carboxylic Acids; Hydroxides; Ibuprofen, 15687-27-1; Molecular Probes; Potassium Compounds; potassium hydroxide, 1310-58-3; Solvents; Sulfonamides

The ecotoxicity of lactic acid, its alkyl esters and selected metal salts was studied experimentally with the micro alga Selenastrum capricornutum, the crustacean Daphnia magna and the fish species Brachydanio rerio and Pimephales promelas. In addition, the biodegradation of lactate esters was also studied. The aim of the study was to provide predicted environmental data for additional alkyl homologues and metal salts. The ecotoxicity data are evaluated by means of Structure Activity Relations (SAR), using literature data on a non-polar narcotic mechanism of toxicity as a baseline for comparison. Lactate salts were evaluated by comparison to the toxicity of the metal ion. For the fish and D. magna, it was evident that methyl, ethyl, propyl and to a lesser extent butyl lactate were slightly more toxic in comparison to baseline non-polar narcotic toxicity data. The toxicity tests carried out with lactate-salts demonstrated clearly that the toxicity in standard tests is only determined by the associated cation and not by the lactate part. Lactic acid and its alkyl esters were degraded for more than 60% in the ready biodegradability tests and from the data presented, it is evident that the majority of alkyl lactates are readily biodegradable. The results presented in this study indicate that alkyl lactate esters show some differences in their ecotoxicity when compared to non-polar narcotic compounds in but that these differences are generally small. When aquatic toxicity is considered together with their rapid tendency to biodegrade, it is concluded that lactate esters show generally favourable environmental characteristics. Chemicals/CAS: Esters; Lactates; Lactic Acid, 50-21-5

Acrylonitrile is a monomer used extensively as a raw material in the manufacturing of acrylic fibers, plastics, synthetic rubbers, and acrylamide. It has been classified as a probable human carcinogen according to the results of numerous chronic rat bioassays. The present report summarizes the toxicity data on acrylonitrile and reviews available data concerning the mechanism (genetic versus epigenetic) by which acrylonitrile is carcinogenic in rats. From the evaluation of the relevant toxicity data, it can be concluded that acrylonitrile is indeed carcinogenic to rats after either oral or inhalational exposure. However, information on other mammalian species is lacking, and, moreover, the exact mechanism of the carcinogenic process is unclear. Therefore, it is recommended to conduct an additional long-term inhalation carcinogenicity study with acrylonitrile in mice, as well as studies into the mechanism by which acrylonitrile induces (brain) tumors in rats (genetic versus epigenetic). Chemicals/CAS: Acrylonitrile, 107-13-1; Carcinogens; Mutagens

OBJECTIVE: To examine any possible links between exposure to DDE (1,1-dichloro-2,2-bis (p-chlorophenyl)ethylene), the persistent metabolite of the pesticide dicophane (DDT), and breast cancer. DESIGN: Multicentre study of exposure to DDE by measurement of adipose tissue aspirated from the buttocks. Laboratory measurements were conducted in a single laboratory. Additional data on risk factors for breast cancer were obtained by standard questionnaires. SETTING: Centres in Germany, the Netherlands, Northern Ireland, Switzerland, and Spain. SUBJECTS: 265 postmenopausal women with breast cancer and 341 controls matched for age and centre. MAIN OUTCOME MEASURE: Adipose DDE concentrations. RESULTS: Women with breast cancer had adipose DDE concentrations 9.2% lower than control women. No increased risk of breast cancer was found at higher concentrations. The odds ratio of breast cancer, adjusted for age and centre, for the highest versus the lowest fourth of DDE distribution was 0.73 (95% confidence interval 0.44 to 1.21) and decreased to 0.48 (0.25 to 0.95; P for trend = 0.02) after adjustment for body mass index, age at first birth, and current alcohol drinking. Adjustment for other risk factors did not materially affect these estimates. CONCLUSIONS: The lower DDE concentrations observed among the women with breast cancer may be secondary to disease inception. This study does not support the hypothesis that DDE increases risk of breast cancer in postmenopausal women in Europe.