Henrik Lund Frandsen

Acrylamide exposure and incidence of breast cancer among postmenopausal women in the Danish Diet, Cancer and Health Study.

Acrylamide, a probable human carcinogen, is formed in several foods during high‐temperature processing. So far, epidemiological studies have not shown any association between human cancer risk and dietary exposure to acrylamide. The purpose of this study was to conduct a nested case control study within a prospective cohort study on the association between breast cancer and exposure to acrylamide using biomarkers. N‐terminal hemoglobin adduct levels of acrylamide and its genotoxic metabolite, glycidamide in red blood cells were analyzed (by LC/MS/MS) as biomarkers of exposure on 374 breast cancer cases and 374 controls from a cohort of postmenopausal women. The adduct levels of acrylamide and glycidamide were similar in cases and controls, with smokers having much higher levels (∼3 times) than nonsmokers. No association was seen between acrylamide‐hemoglobin levels and breast cancer risk neither unadjusted nor adjusted for the potential confounders HRT duration, parity, BMI, alcohol intake and education. After adjustment for smoking behavior, however, a positive association was seen between acrylamide‐hemoglobin levels and estrogen receptor positive breast cancer with an estimated incidence rate ratio (95% CI) of 2.7 (1.1–6.6) per 10‐fold increase in acrylamide‐hemoglobin level. A weak association between glycidamide hemoglobin levels and incidence of estrogen receptor positive breast cancer was also found, this association, however, entirely disappeared when acrylamide and glycidamide hemoglobin levels were mutually adjusted.

Genotoxicity of unmodified and organo-modified montmorillonite

The natural clay mineral montmorillonite (Cloisite) Na+) and an organo-modified montmorillonite (Cloisite 30B) were investigated for genotoxic potential as crude suspensions and as suspensions filtrated through a 0.2-microm pore-size filter to remove particles above the nanometre range. Filtered and unfiltered water suspensions of both clays did not induce mutations in the Salmonella/microsome assay at concentrations up to 141microg/ml of the crude clay, using the tester strains TA98 and TA100. Filtered and unfiltered Cloisite) Na+ suspensions in culture medium did not induce DNA strand-breaks in Caco-2 cells after 24h of exposure, as tested in the alkaline comet assay. However, both the filtered and the unfiltered samples of Cloisite 30B induced DNA strand-breaks in a concentration-dependent manner and the two highest test concentrations produced statistically significantly different results from those seen with control samples (p<0.01 and p<0.001) and (p<0.05 and p<0.01), respectively. The unfiltered samples were tested up to concentrations of 170microg/ml and the filtered samples up to 216microg/ml before filtration. When tested in the same concentration range as used in the comet assay, none of the clays produced ROS in a cell-free test system (the DCFH-DA assay). Inductively coupled plasma mass-spectrometry (ICP-MS) was used to detect clay particles in the filtered samples using aluminium as a tracer element characteristic to clay. The results indicated that clay particles were absent in the filtered samples, which was independently confirmed by dynamic light-scattering measurements. Detection and identification of free quaternary ammonium modifier in the filtered sample was carried out by HPLC-Q-TOF/MS and revealed a total concentration of a mixture of quaternary ammonium analogues of 1.57microg/ml. These findings suggest that the genotoxicity of organo-modified montmorillonite was caused by the organo-modifier. The detected organo-modifier mixture was synthesized and comet-assay results showed that the genotoxic potency of this synthesized organo-modifier was in the same order of magnitude at equimolar concentrations of organo-modifier in filtrated Cloisite) 30B suspensions, and could therefore at least partly explain the genotoxic effect of Cloisite) 30B.

In utero reproductive study in rats exposed to nonylphenol.

Alkylphenol ethoxylates are widely used non-ionic surfactants. Nonylphenol ethoxylate constitutes 82% of the production of all alkylphenol ethoxylates and the breakdown product of nonylphenol ethoxylate, nonylphenol (NP) has been shown to be estrogenic in both in vitro and in vivo screening assays. To determine the potential reproductive toxicity of NP, a one-generation in utero study was conducted. Rats were dosed from gestation day 11 through 18 with NP at 3, 15, or 75 mg/kg/day or diethylstilbestrol (DES) at 30 microg/kg/day. DES was used as a positive control. Both substances were given orally by gavage. Male offspring were sacrificed at postnatal day (PND) 11, 21, or 110 and reproductive parameters were evaluated. Pup birth weight and body weight and percent motile sperm at age of 110 day were significantly reduced by DES. The absolute weight of the right epididymis was significantly reduced in the DES group. The absolute weight of the right epididymis were also significantly decreased in the animals exposed to 75 or 15 mg/kg/day NP, effects which disappeared when organ weight was related to body weight. This study showed a dose-dependent effect of nonylphenol on male reproductive development at doses of 75 and 15 mg/kg bw/day based on absolute epididymal weight.

A revised multi-Fickian moisture transport model to describe non-Fickian effects in wood

Abstract This paper presents a study and a refinement of the sorption rate model in a so-called multi-Fickian or multi-phase model. This type of model describes the complex moisture transport system in wood, which consists of separate water vapor and bound-water diffusion interacting through sorption. At high relative humidities, the effect of this complex moisture transport system becomes apparent, and since a single Fickian diffusion equation fails to model the behavior, it has been referred to as non-Fickian or anomalous behavior. At low relative humidities, slow bound-water transport and fast sorption allow a simplification of the system to be modeled by a single Fickian diffusion equation. To determine the response of the system, the sorption rate model is essential. Here the function modeling the moisture-dependent adsorption rate is investigated based on existing experiments on thin wood specimens. In these specimens diffusion is shown to be negligible, allowing a separate study of the adsorption rate. The desorption rate has been observed to be slower at higher relative humidities as well, and an expression analogous to the adsorption rate model is proposed. Furthermore, the boundary conditions for the model are discussed, since discrepancies from corresponding models of moisture transport in paper products have been found.

Biomarkers of Human Exposure to Acrylamide and Relation to Polymorphisms in Metabolizing Genes

Acrylamide (AA) is formed in heat treated carbohydrate rich foods in the so-called Maillard reaction. AA is readily absorbed in the body and converted to glycidamide (GA) by epoxidation by the CYP2E1 (cytochrome P450 2E) enzyme. Both AA and GA may be detoxified through direct conjunction to glutathione by glutathione-S-transferases and GA by hydrolysis to glyceramide. Recently, we reported that biomarkers of AA exposure reflect intake of major food sources of AA; there were large interindividual variations in the blood ratio of GA-Hb/AA-Hb (GA- and AA-hemoglobin adducts). In this study we investigated whether the ratio of GA-Hb/AA-Hb in subjects could be related to polymorphic differences in genes coding for metabolizing enzymes CYP2E1, EPHX1 (microsomal epoxide hydrolase), GSTM1, GSTT1, and GSTP1, all being expected to be involved in the activation and detoxification of AA-associated adducts. We found significant associations between GSTM1 and GSTT1 genotypes and the ratio of GA-Hb/AA-Hb (p = 0.039 and p = 0.006, respectively). The ratio of GA-Hb/AA-Hb in individuals with the combined GSTM1- and GSTT1-null variants was significantly (p = 0.029) higher than those with the wild-type genotypes. Although the number of subjects was small, there were also significant associations with other combinations; CYP2E1 (Val179Val) plus GSTM1-null (p = 0.022); CYP2E1 (Val/Val), GSTM1-null plus GSTT1-null (p = 0.047); and CYP2E1 (Val/Val), GSTT1 null, EPHX1 (Tyr113Tyr) plus EPHX1 (His139Arg) (p = 0.018). Individuals with these combined genotypes had significantly higher blood ratio of GA-Hb/AA-Hb than other combinations. The observed associations correspond with what would be expected from the relative roles of these enzymes in activation and detoxification of AA, except for individuals with the EPHX1 (His139Arg) variant. The internal dose of genotoxic metabolite and also the concentration of AA in blood seem to be affected by these polymorphic genes. The genotypes and their combination may constitute useful biomarkers for the assessment of individual susceptibility to AA intake, and could add to the precision of epidemiological studies of dietary cancer.

Atherosclerosis in Watanabe heritable hyperlipidaemic rabbits

The spontaneous development of atherosclerotic disease in 38 homozygous and 34 heterozygous Watanabe heritable hyperlipidaemic rabbits was evaluated by qualitative and quantitative light microscopy in aorta, coronary, pulmonary and renal arteries, by naked eye and macroscopic morphometric estimation of aortic atherosclerosis extent and by biochemical analysis of aortic cholesterol content. No noteworthy atherosclerosis was demonstrated within 19 months in heterozygous rabbits. In homozygous rabbits, atherosclerotic lesions were seen from the age of 4 months and progressed with age. All 19‐month‐old rabbits had severe atherosclerotic disease. As much as 64% of the variation in atherosclerosis extent/severity could be explained by serum cholesterol and age. A highly significant correlation between the various methods for quantitation of atherosclerosis extent and/or severity was demonstrated, suggesting that quantitative microscopy, macroscopic morphometry and determination of aortic cholesterol content may be equally valid as a measure of atherosclerosis in WHHL rabbits and are therefore interchangeable.

Comparison of the effects of fish oil and olive oil on blood lipids and aortic atherosclerosis in Watanabe heritable hyperlipidaemic rabbits.

To compare the effects of fish oil and olive oil on the development of atherosclerosis in Watanabe heritable hyperlipidaemic (WHHL) rabbits, 6-week-old animals were given a daily dose (1.5 ml/kg body weight) of fish oil (n 10) or olive oil (n 10) by oral administration for 16 weeks. Plasma cholesterol and triacylglycerols were measured once monthly, and their concentrations in lipoproteins, together with susceptibility of LDL to oxidation were measured in vitro at the termination of the experiment. Aortic atherosclerosis was quantified biochemically and microscopically. After 4 weeks of treatment, and throughout the study thereafter, blood lipids were significantly (P < 0.05) lower in the fish-oil group than in the olive-oil group (cholesterol: 17.0 v. 30.3 mmol/l, triacylglycerols 2.97 v. 6.25 mmol/l, at termination). In the fish-oil group cholesterol was significantly lower in intermediate-density lipoproteins (2.69 v. 6.76 mmol/l) and VLDL (3.36 v. 11.51 mmol/l). Triacylglycerol levels of intermediate-density lipoproteins and VLDL in the fish-oil group were also significantly lower when compared with the olive-oil group (0.54 v 1.36 mmol/l and 0.92 v. 2.87 mmol/l respectively). No group differences were recorded for LDL- and HDL-cholesterol or triacylglycerol levels. A significantly higher oxidation of LDL was recorded 1 h after exposure to CuSO4 in the fish-oil group when compared with the olive-oil group (0.465 v. 0.202, arbitrary units). The following indicators of atherosclerosis development were significantly lower in the fish-oil group than in the olive-oil group: the cholesterol content (mg/g tissue) in the ascending aorta (29.8 v. 48.9), the intima:media value (4.81 v. 18.24) and the area of intima (0.10 v. 0.57 mm2) in the thoracic aorta. It was concluded that fish-oil treatment decreased blood lipids and the development of aortic atherosclerosis in WHHL rabbits when compared with olive-oil treatment.

A hysteresis model suitable for numerical simulation of moisture content in wood

Abstract The equilibrium moisture content in wood depends not only on the current relative humidity in ambient air, but also on the history of relative humidity variations. This hysteresis dependence of sorption in wood implies that in the worst case the moisture content for a given relative humidity may deviate by 30–35%. While researchers seem to have reached a general agreement on the hypothesis for the sorption hysteresis phenomenon, only a few models describing the phenomenon are available. Current models such as the independent domain model have numerical deficiencies and drawbacks. This paper presents a new hysteresis model, which mathematically resolves in closed-form expressions, with the current relative humidity and moisture content as the only input parameters. Furthermore, the model has the advantage of being applicable to different sorption isotherms, i.e., different species and different temperatures. These features make the model relatively easy to implement into a numerical method such as the finite element method.

Nanoparticulate silver increases uric acid and allantoin excretion in rats, as identified by metabolomics

Metabolomic investigation of rat urine was employed to identify mammalian metabolites affected by ionic or nanoparticulate silver. Female and male Wistar rats were administered silver nanoparticles (2.25, 4.5 or 9.0 mg kg−1 body weight per day) or ionic silver (silver acetate, 9.0 mg silver kg−1 bw per day) by oral gavage for 28 days. On day 18, urine was collected for 24 h and subjected to metabolomics with high performance liquid chromatography–quadropole time‐of‐flight mass spectrometry (HPLC‐QTOF‐MS)‐based separation and detection. Principal component analysis was subsequently applied to the data. Metabolomic differences in urine composition were found in female rats but not in male rats. Several metabolites were identified by the use of elemental composition calculated from the exact mass combined with searches in the Human Metabolome Database.The metabolite identities were eventually verified by co‐chromatography with authentic standards. Differences were found in uric acid and its degradation product, allantoin. Administration of nanoparticulate silver increased both metabolites, whereas ionic silver only increased allantoin. In conclusion, metabolomic investigation of rat urine showed that increased levels of uric acid and allantoin were associated with exposure to nanoparticulate silver. Copyright

Curvature and Strength of Ni-YSZ Solid Oxide Half-cells after RedOx Treatments

One of the main drawbacks of anode-supported solid oxide fuel cell technology is the limited capability to withstand reduction and oxidation (“RedOx”) of the Ni phase. This study compares the effect of RedOx cycles on curvature and strength of half-cells, composed of a Ni-YSZ support, a Ni- YSZ anode and an 8YSZ electrolyte. Five different treatments were studied: (i) reduction at 600°C, (ii) reduction at 1000°C, (iii) 1 RedOx cycle at 750°C, (iv) 5 RedOx cycles at 750°C and (v) 5 RedOx cycles at 600°C. The strength was measured by the ball-on-ring method, where it is calculated analytically from the force. In this calculation the thermal stresses have been estimated from the curvature of the half-cell. For each treatment, more than 30 samples were tested. About 20 ball-on-ring samples were laser cut from one original 12x12 cm2 half-cell. Curvature and porosity were measured for each sample before and after RedOx treatments. The first observations show that increasing the reduction temperature enhance strength but does not influence the curvature, whereas 1 RedOx cycle at 750°C increases the curvature without changing the strength. Consecutive RedOx cycles seem to decrease anode-supported cell strength, but this is coupled to lower porosity of the sample.